mirror of https://gitee.com/openkylin/linux.git
5003 lines
133 KiB
C
5003 lines
133 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/namei.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* Some corrections by tytso.
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*/
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/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
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* lookup logic.
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*/
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/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
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*/
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#include <linux/init.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/pagemap.h>
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#include <linux/fsnotify.h>
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#include <linux/personality.h>
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#include <linux/security.h>
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#include <linux/ima.h>
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#include <linux/syscalls.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/capability.h>
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#include <linux/file.h>
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#include <linux/fcntl.h>
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#include <linux/device_cgroup.h>
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#include <linux/fs_struct.h>
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#include <linux/posix_acl.h>
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#include <linux/hash.h>
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#include <linux/bitops.h>
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#include <linux/init_task.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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#include "mount.h"
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/* [Feb-1997 T. Schoebel-Theuer]
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* Fundamental changes in the pathname lookup mechanisms (namei)
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* were necessary because of omirr. The reason is that omirr needs
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* to know the _real_ pathname, not the user-supplied one, in case
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* of symlinks (and also when transname replacements occur).
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*
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* The new code replaces the old recursive symlink resolution with
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* an iterative one (in case of non-nested symlink chains). It does
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* this with calls to <fs>_follow_link().
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* As a side effect, dir_namei(), _namei() and follow_link() are now
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* replaced with a single function lookup_dentry() that can handle all
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* the special cases of the former code.
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*
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* With the new dcache, the pathname is stored at each inode, at least as
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* long as the refcount of the inode is positive. As a side effect, the
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* size of the dcache depends on the inode cache and thus is dynamic.
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*
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* [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
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* resolution to correspond with current state of the code.
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*
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* Note that the symlink resolution is not *completely* iterative.
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* There is still a significant amount of tail- and mid- recursion in
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* the algorithm. Also, note that <fs>_readlink() is not used in
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* lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
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* may return different results than <fs>_follow_link(). Many virtual
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* filesystems (including /proc) exhibit this behavior.
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*/
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/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
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* New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
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* and the name already exists in form of a symlink, try to create the new
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* name indicated by the symlink. The old code always complained that the
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* name already exists, due to not following the symlink even if its target
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* is nonexistent. The new semantics affects also mknod() and link() when
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* the name is a symlink pointing to a non-existent name.
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*
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* I don't know which semantics is the right one, since I have no access
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* to standards. But I found by trial that HP-UX 9.0 has the full "new"
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* semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
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* "old" one. Personally, I think the new semantics is much more logical.
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* Note that "ln old new" where "new" is a symlink pointing to a non-existing
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* file does succeed in both HP-UX and SunOs, but not in Solaris
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* and in the old Linux semantics.
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*/
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/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
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* semantics. See the comments in "open_namei" and "do_link" below.
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*
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* [10-Sep-98 Alan Modra] Another symlink change.
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*/
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/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
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* inside the path - always follow.
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* in the last component in creation/removal/renaming - never follow.
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* if LOOKUP_FOLLOW passed - follow.
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* if the pathname has trailing slashes - follow.
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* otherwise - don't follow.
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* (applied in that order).
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*
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* [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
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* restored for 2.4. This is the last surviving part of old 4.2BSD bug.
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* During the 2.4 we need to fix the userland stuff depending on it -
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* hopefully we will be able to get rid of that wart in 2.5. So far only
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* XEmacs seems to be relying on it...
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*/
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/*
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* [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
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* implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
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* any extra contention...
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*/
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/* In order to reduce some races, while at the same time doing additional
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* checking and hopefully speeding things up, we copy filenames to the
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* kernel data space before using them..
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*
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* POSIX.1 2.4: an empty pathname is invalid (ENOENT).
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* PATH_MAX includes the nul terminator --RR.
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*/
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#define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
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struct filename *
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getname_flags(const char __user *filename, int flags, int *empty)
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{
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struct filename *result;
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char *kname;
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int len;
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result = audit_reusename(filename);
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if (result)
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return result;
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result = __getname();
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if (unlikely(!result))
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return ERR_PTR(-ENOMEM);
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/*
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* First, try to embed the struct filename inside the names_cache
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* allocation
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*/
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kname = (char *)result->iname;
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result->name = kname;
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len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
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if (unlikely(len < 0)) {
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__putname(result);
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return ERR_PTR(len);
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}
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/*
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* Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
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* separate struct filename so we can dedicate the entire
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* names_cache allocation for the pathname, and re-do the copy from
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* userland.
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*/
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if (unlikely(len == EMBEDDED_NAME_MAX)) {
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const size_t size = offsetof(struct filename, iname[1]);
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kname = (char *)result;
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/*
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* size is chosen that way we to guarantee that
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* result->iname[0] is within the same object and that
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* kname can't be equal to result->iname, no matter what.
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*/
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result = kzalloc(size, GFP_KERNEL);
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if (unlikely(!result)) {
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__putname(kname);
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return ERR_PTR(-ENOMEM);
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}
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result->name = kname;
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len = strncpy_from_user(kname, filename, PATH_MAX);
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if (unlikely(len < 0)) {
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__putname(kname);
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kfree(result);
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return ERR_PTR(len);
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}
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if (unlikely(len == PATH_MAX)) {
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__putname(kname);
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kfree(result);
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return ERR_PTR(-ENAMETOOLONG);
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}
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}
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result->refcnt = 1;
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/* The empty path is special. */
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if (unlikely(!len)) {
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if (empty)
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*empty = 1;
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if (!(flags & LOOKUP_EMPTY)) {
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putname(result);
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return ERR_PTR(-ENOENT);
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}
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}
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result->uptr = filename;
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result->aname = NULL;
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audit_getname(result);
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return result;
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}
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struct filename *
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getname_uflags(const char __user *filename, int uflags)
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{
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int flags = (uflags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
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return getname_flags(filename, flags, NULL);
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}
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struct filename *
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getname(const char __user * filename)
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{
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return getname_flags(filename, 0, NULL);
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}
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struct filename *
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getname_kernel(const char * filename)
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{
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struct filename *result;
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int len = strlen(filename) + 1;
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result = __getname();
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if (unlikely(!result))
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return ERR_PTR(-ENOMEM);
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if (len <= EMBEDDED_NAME_MAX) {
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result->name = (char *)result->iname;
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} else if (len <= PATH_MAX) {
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const size_t size = offsetof(struct filename, iname[1]);
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struct filename *tmp;
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tmp = kmalloc(size, GFP_KERNEL);
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if (unlikely(!tmp)) {
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__putname(result);
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return ERR_PTR(-ENOMEM);
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}
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tmp->name = (char *)result;
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result = tmp;
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} else {
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__putname(result);
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return ERR_PTR(-ENAMETOOLONG);
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}
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memcpy((char *)result->name, filename, len);
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result->uptr = NULL;
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result->aname = NULL;
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result->refcnt = 1;
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audit_getname(result);
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return result;
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}
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void putname(struct filename *name)
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{
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if (IS_ERR(name))
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return;
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BUG_ON(name->refcnt <= 0);
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if (--name->refcnt > 0)
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return;
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if (name->name != name->iname) {
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__putname(name->name);
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kfree(name);
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} else
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__putname(name);
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}
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/**
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* check_acl - perform ACL permission checking
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* @mnt_userns: user namespace of the mount the inode was found from
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* @inode: inode to check permissions on
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
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*
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* This function performs the ACL permission checking. Since this function
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* retrieve POSIX acls it needs to know whether it is called from a blocking or
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* non-blocking context and thus cares about the MAY_NOT_BLOCK bit.
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*
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* If the inode has been found through an idmapped mount the user namespace of
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* the vfsmount must be passed through @mnt_userns. This function will then take
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* care to map the inode according to @mnt_userns before checking permissions.
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* On non-idmapped mounts or if permission checking is to be performed on the
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* raw inode simply passs init_user_ns.
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*/
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static int check_acl(struct user_namespace *mnt_userns,
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struct inode *inode, int mask)
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{
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#ifdef CONFIG_FS_POSIX_ACL
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struct posix_acl *acl;
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if (mask & MAY_NOT_BLOCK) {
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acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
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if (!acl)
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return -EAGAIN;
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/* no ->get_acl() calls in RCU mode... */
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if (is_uncached_acl(acl))
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return -ECHILD;
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return posix_acl_permission(mnt_userns, inode, acl, mask);
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}
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acl = get_acl(inode, ACL_TYPE_ACCESS);
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if (IS_ERR(acl))
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return PTR_ERR(acl);
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if (acl) {
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int error = posix_acl_permission(mnt_userns, inode, acl, mask);
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posix_acl_release(acl);
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return error;
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}
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#endif
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return -EAGAIN;
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}
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/**
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* acl_permission_check - perform basic UNIX permission checking
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* @mnt_userns: user namespace of the mount the inode was found from
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* @inode: inode to check permissions on
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
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*
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* This function performs the basic UNIX permission checking. Since this
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* function may retrieve POSIX acls it needs to know whether it is called from a
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* blocking or non-blocking context and thus cares about the MAY_NOT_BLOCK bit.
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*
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* If the inode has been found through an idmapped mount the user namespace of
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* the vfsmount must be passed through @mnt_userns. This function will then take
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* care to map the inode according to @mnt_userns before checking permissions.
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* On non-idmapped mounts or if permission checking is to be performed on the
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* raw inode simply passs init_user_ns.
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*/
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static int acl_permission_check(struct user_namespace *mnt_userns,
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struct inode *inode, int mask)
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{
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unsigned int mode = inode->i_mode;
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kuid_t i_uid;
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/* Are we the owner? If so, ACL's don't matter */
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i_uid = i_uid_into_mnt(mnt_userns, inode);
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if (likely(uid_eq(current_fsuid(), i_uid))) {
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mask &= 7;
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mode >>= 6;
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return (mask & ~mode) ? -EACCES : 0;
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}
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/* Do we have ACL's? */
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if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
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int error = check_acl(mnt_userns, inode, mask);
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if (error != -EAGAIN)
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return error;
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}
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/* Only RWX matters for group/other mode bits */
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mask &= 7;
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/*
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* Are the group permissions different from
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* the other permissions in the bits we care
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* about? Need to check group ownership if so.
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*/
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if (mask & (mode ^ (mode >> 3))) {
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kgid_t kgid = i_gid_into_mnt(mnt_userns, inode);
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if (in_group_p(kgid))
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mode >>= 3;
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}
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/* Bits in 'mode' clear that we require? */
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return (mask & ~mode) ? -EACCES : 0;
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}
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/**
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* generic_permission - check for access rights on a Posix-like filesystem
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* @mnt_userns: user namespace of the mount the inode was found from
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* @inode: inode to check access rights for
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC,
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* %MAY_NOT_BLOCK ...)
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*
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* Used to check for read/write/execute permissions on a file.
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* We use "fsuid" for this, letting us set arbitrary permissions
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* for filesystem access without changing the "normal" uids which
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* are used for other things.
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*
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* generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
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* request cannot be satisfied (eg. requires blocking or too much complexity).
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* It would then be called again in ref-walk mode.
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*
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* If the inode has been found through an idmapped mount the user namespace of
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* the vfsmount must be passed through @mnt_userns. This function will then take
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* care to map the inode according to @mnt_userns before checking permissions.
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* On non-idmapped mounts or if permission checking is to be performed on the
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* raw inode simply passs init_user_ns.
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*/
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int generic_permission(struct user_namespace *mnt_userns, struct inode *inode,
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int mask)
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{
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int ret;
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/*
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* Do the basic permission checks.
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*/
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ret = acl_permission_check(mnt_userns, inode, mask);
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if (ret != -EACCES)
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return ret;
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if (S_ISDIR(inode->i_mode)) {
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/* DACs are overridable for directories */
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if (!(mask & MAY_WRITE))
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if (capable_wrt_inode_uidgid(mnt_userns, inode,
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CAP_DAC_READ_SEARCH))
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return 0;
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if (capable_wrt_inode_uidgid(mnt_userns, inode,
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CAP_DAC_OVERRIDE))
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return 0;
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return -EACCES;
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}
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/*
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* Searching includes executable on directories, else just read.
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*/
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mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
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if (mask == MAY_READ)
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if (capable_wrt_inode_uidgid(mnt_userns, inode,
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CAP_DAC_READ_SEARCH))
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return 0;
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/*
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* Read/write DACs are always overridable.
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* Executable DACs are overridable when there is
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* at least one exec bit set.
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*/
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if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
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if (capable_wrt_inode_uidgid(mnt_userns, inode,
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CAP_DAC_OVERRIDE))
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return 0;
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return -EACCES;
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}
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EXPORT_SYMBOL(generic_permission);
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/**
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* do_inode_permission - UNIX permission checking
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* @mnt_userns: user namespace of the mount the inode was found from
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* @inode: inode to check permissions on
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC ...)
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*
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* We _really_ want to just do "generic_permission()" without
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* even looking at the inode->i_op values. So we keep a cache
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* flag in inode->i_opflags, that says "this has not special
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* permission function, use the fast case".
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*/
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static inline int do_inode_permission(struct user_namespace *mnt_userns,
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struct inode *inode, int mask)
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{
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if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
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if (likely(inode->i_op->permission))
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return inode->i_op->permission(mnt_userns, inode, mask);
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/* This gets set once for the inode lifetime */
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spin_lock(&inode->i_lock);
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inode->i_opflags |= IOP_FASTPERM;
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spin_unlock(&inode->i_lock);
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}
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return generic_permission(mnt_userns, inode, mask);
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}
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/**
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* sb_permission - Check superblock-level permissions
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* @sb: Superblock of inode to check permission on
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* @inode: Inode to check permission on
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* @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
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*
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* Separate out file-system wide checks from inode-specific permission checks.
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*/
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static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
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{
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if (unlikely(mask & MAY_WRITE)) {
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umode_t mode = inode->i_mode;
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/* Nobody gets write access to a read-only fs. */
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if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
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return -EROFS;
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}
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return 0;
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}
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/**
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* inode_permission - Check for access rights to a given inode
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* @mnt_userns: User namespace of the mount the inode was found from
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* @inode: Inode to check permission on
|
|
* @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
|
|
*
|
|
* Check for read/write/execute permissions on an inode. We use fs[ug]id for
|
|
* this, letting us set arbitrary permissions for filesystem access without
|
|
* changing the "normal" UIDs which are used for other things.
|
|
*
|
|
* When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
|
|
*/
|
|
int inode_permission(struct user_namespace *mnt_userns,
|
|
struct inode *inode, int mask)
|
|
{
|
|
int retval;
|
|
|
|
retval = sb_permission(inode->i_sb, inode, mask);
|
|
if (retval)
|
|
return retval;
|
|
|
|
if (unlikely(mask & MAY_WRITE)) {
|
|
/*
|
|
* Nobody gets write access to an immutable file.
|
|
*/
|
|
if (IS_IMMUTABLE(inode))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* Updating mtime will likely cause i_uid and i_gid to be
|
|
* written back improperly if their true value is unknown
|
|
* to the vfs.
|
|
*/
|
|
if (HAS_UNMAPPED_ID(mnt_userns, inode))
|
|
return -EACCES;
|
|
}
|
|
|
|
retval = do_inode_permission(mnt_userns, inode, mask);
|
|
if (retval)
|
|
return retval;
|
|
|
|
retval = devcgroup_inode_permission(inode, mask);
|
|
if (retval)
|
|
return retval;
|
|
|
|
return security_inode_permission(inode, mask);
|
|
}
|
|
EXPORT_SYMBOL(inode_permission);
|
|
|
|
/**
|
|
* path_get - get a reference to a path
|
|
* @path: path to get the reference to
|
|
*
|
|
* Given a path increment the reference count to the dentry and the vfsmount.
|
|
*/
|
|
void path_get(const struct path *path)
|
|
{
|
|
mntget(path->mnt);
|
|
dget(path->dentry);
|
|
}
|
|
EXPORT_SYMBOL(path_get);
|
|
|
|
/**
|
|
* path_put - put a reference to a path
|
|
* @path: path to put the reference to
|
|
*
|
|
* Given a path decrement the reference count to the dentry and the vfsmount.
|
|
*/
|
|
void path_put(const struct path *path)
|
|
{
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
}
|
|
EXPORT_SYMBOL(path_put);
|
|
|
|
#define EMBEDDED_LEVELS 2
|
|
struct nameidata {
|
|
struct path path;
|
|
struct qstr last;
|
|
struct path root;
|
|
struct inode *inode; /* path.dentry.d_inode */
|
|
unsigned int flags, state;
|
|
unsigned seq, m_seq, r_seq;
|
|
int last_type;
|
|
unsigned depth;
|
|
int total_link_count;
|
|
struct saved {
|
|
struct path link;
|
|
struct delayed_call done;
|
|
const char *name;
|
|
unsigned seq;
|
|
} *stack, internal[EMBEDDED_LEVELS];
|
|
struct filename *name;
|
|
struct nameidata *saved;
|
|
unsigned root_seq;
|
|
int dfd;
|
|
kuid_t dir_uid;
|
|
umode_t dir_mode;
|
|
} __randomize_layout;
|
|
|
|
#define ND_ROOT_PRESET 1
|
|
#define ND_ROOT_GRABBED 2
|
|
#define ND_JUMPED 4
|
|
|
|
static void __set_nameidata(struct nameidata *p, int dfd, struct filename *name)
|
|
{
|
|
struct nameidata *old = current->nameidata;
|
|
p->stack = p->internal;
|
|
p->depth = 0;
|
|
p->dfd = dfd;
|
|
p->name = name;
|
|
p->path.mnt = NULL;
|
|
p->path.dentry = NULL;
|
|
p->total_link_count = old ? old->total_link_count : 0;
|
|
p->saved = old;
|
|
current->nameidata = p;
|
|
}
|
|
|
|
static inline void set_nameidata(struct nameidata *p, int dfd, struct filename *name,
|
|
const struct path *root)
|
|
{
|
|
__set_nameidata(p, dfd, name);
|
|
p->state = 0;
|
|
if (unlikely(root)) {
|
|
p->state = ND_ROOT_PRESET;
|
|
p->root = *root;
|
|
}
|
|
}
|
|
|
|
static void restore_nameidata(void)
|
|
{
|
|
struct nameidata *now = current->nameidata, *old = now->saved;
|
|
|
|
current->nameidata = old;
|
|
if (old)
|
|
old->total_link_count = now->total_link_count;
|
|
if (now->stack != now->internal)
|
|
kfree(now->stack);
|
|
}
|
|
|
|
static bool nd_alloc_stack(struct nameidata *nd)
|
|
{
|
|
struct saved *p;
|
|
|
|
p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved),
|
|
nd->flags & LOOKUP_RCU ? GFP_ATOMIC : GFP_KERNEL);
|
|
if (unlikely(!p))
|
|
return false;
|
|
memcpy(p, nd->internal, sizeof(nd->internal));
|
|
nd->stack = p;
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* path_connected - Verify that a dentry is below mnt.mnt_root
|
|
*
|
|
* Rename can sometimes move a file or directory outside of a bind
|
|
* mount, path_connected allows those cases to be detected.
|
|
*/
|
|
static bool path_connected(struct vfsmount *mnt, struct dentry *dentry)
|
|
{
|
|
struct super_block *sb = mnt->mnt_sb;
|
|
|
|
/* Bind mounts can have disconnected paths */
|
|
if (mnt->mnt_root == sb->s_root)
|
|
return true;
|
|
|
|
return is_subdir(dentry, mnt->mnt_root);
|
|
}
|
|
|
|
static void drop_links(struct nameidata *nd)
|
|
{
|
|
int i = nd->depth;
|
|
while (i--) {
|
|
struct saved *last = nd->stack + i;
|
|
do_delayed_call(&last->done);
|
|
clear_delayed_call(&last->done);
|
|
}
|
|
}
|
|
|
|
static void terminate_walk(struct nameidata *nd)
|
|
{
|
|
drop_links(nd);
|
|
if (!(nd->flags & LOOKUP_RCU)) {
|
|
int i;
|
|
path_put(&nd->path);
|
|
for (i = 0; i < nd->depth; i++)
|
|
path_put(&nd->stack[i].link);
|
|
if (nd->state & ND_ROOT_GRABBED) {
|
|
path_put(&nd->root);
|
|
nd->state &= ~ND_ROOT_GRABBED;
|
|
}
|
|
} else {
|
|
nd->flags &= ~LOOKUP_RCU;
|
|
rcu_read_unlock();
|
|
}
|
|
nd->depth = 0;
|
|
nd->path.mnt = NULL;
|
|
nd->path.dentry = NULL;
|
|
}
|
|
|
|
/* path_put is needed afterwards regardless of success or failure */
|
|
static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq)
|
|
{
|
|
int res = __legitimize_mnt(path->mnt, mseq);
|
|
if (unlikely(res)) {
|
|
if (res > 0)
|
|
path->mnt = NULL;
|
|
path->dentry = NULL;
|
|
return false;
|
|
}
|
|
if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) {
|
|
path->dentry = NULL;
|
|
return false;
|
|
}
|
|
return !read_seqcount_retry(&path->dentry->d_seq, seq);
|
|
}
|
|
|
|
static inline bool legitimize_path(struct nameidata *nd,
|
|
struct path *path, unsigned seq)
|
|
{
|
|
return __legitimize_path(path, seq, nd->m_seq);
|
|
}
|
|
|
|
static bool legitimize_links(struct nameidata *nd)
|
|
{
|
|
int i;
|
|
if (unlikely(nd->flags & LOOKUP_CACHED)) {
|
|
drop_links(nd);
|
|
nd->depth = 0;
|
|
return false;
|
|
}
|
|
for (i = 0; i < nd->depth; i++) {
|
|
struct saved *last = nd->stack + i;
|
|
if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
|
|
drop_links(nd);
|
|
nd->depth = i + 1;
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static bool legitimize_root(struct nameidata *nd)
|
|
{
|
|
/*
|
|
* For scoped-lookups (where nd->root has been zeroed), we need to
|
|
* restart the whole lookup from scratch -- because set_root() is wrong
|
|
* for these lookups (nd->dfd is the root, not the filesystem root).
|
|
*/
|
|
if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED))
|
|
return false;
|
|
/* Nothing to do if nd->root is zero or is managed by the VFS user. */
|
|
if (!nd->root.mnt || (nd->state & ND_ROOT_PRESET))
|
|
return true;
|
|
nd->state |= ND_ROOT_GRABBED;
|
|
return legitimize_path(nd, &nd->root, nd->root_seq);
|
|
}
|
|
|
|
/*
|
|
* Path walking has 2 modes, rcu-walk and ref-walk (see
|
|
* Documentation/filesystems/path-lookup.txt). In situations when we can't
|
|
* continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
|
|
* normal reference counts on dentries and vfsmounts to transition to ref-walk
|
|
* mode. Refcounts are grabbed at the last known good point before rcu-walk
|
|
* got stuck, so ref-walk may continue from there. If this is not successful
|
|
* (eg. a seqcount has changed), then failure is returned and it's up to caller
|
|
* to restart the path walk from the beginning in ref-walk mode.
|
|
*/
|
|
|
|
/**
|
|
* try_to_unlazy - try to switch to ref-walk mode.
|
|
* @nd: nameidata pathwalk data
|
|
* Returns: true on success, false on failure
|
|
*
|
|
* try_to_unlazy attempts to legitimize the current nd->path and nd->root
|
|
* for ref-walk mode.
|
|
* Must be called from rcu-walk context.
|
|
* Nothing should touch nameidata between try_to_unlazy() failure and
|
|
* terminate_walk().
|
|
*/
|
|
static bool try_to_unlazy(struct nameidata *nd)
|
|
{
|
|
struct dentry *parent = nd->path.dentry;
|
|
|
|
BUG_ON(!(nd->flags & LOOKUP_RCU));
|
|
|
|
nd->flags &= ~LOOKUP_RCU;
|
|
if (unlikely(!legitimize_links(nd)))
|
|
goto out1;
|
|
if (unlikely(!legitimize_path(nd, &nd->path, nd->seq)))
|
|
goto out;
|
|
if (unlikely(!legitimize_root(nd)))
|
|
goto out;
|
|
rcu_read_unlock();
|
|
BUG_ON(nd->inode != parent->d_inode);
|
|
return true;
|
|
|
|
out1:
|
|
nd->path.mnt = NULL;
|
|
nd->path.dentry = NULL;
|
|
out:
|
|
rcu_read_unlock();
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* try_to_unlazy_next - try to switch to ref-walk mode.
|
|
* @nd: nameidata pathwalk data
|
|
* @dentry: next dentry to step into
|
|
* @seq: seq number to check @dentry against
|
|
* Returns: true on success, false on failure
|
|
*
|
|
* Similar to to try_to_unlazy(), but here we have the next dentry already
|
|
* picked by rcu-walk and want to legitimize that in addition to the current
|
|
* nd->path and nd->root for ref-walk mode. Must be called from rcu-walk context.
|
|
* Nothing should touch nameidata between try_to_unlazy_next() failure and
|
|
* terminate_walk().
|
|
*/
|
|
static bool try_to_unlazy_next(struct nameidata *nd, struct dentry *dentry, unsigned seq)
|
|
{
|
|
BUG_ON(!(nd->flags & LOOKUP_RCU));
|
|
|
|
nd->flags &= ~LOOKUP_RCU;
|
|
if (unlikely(!legitimize_links(nd)))
|
|
goto out2;
|
|
if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq)))
|
|
goto out2;
|
|
if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref)))
|
|
goto out1;
|
|
|
|
/*
|
|
* We need to move both the parent and the dentry from the RCU domain
|
|
* to be properly refcounted. And the sequence number in the dentry
|
|
* validates *both* dentry counters, since we checked the sequence
|
|
* number of the parent after we got the child sequence number. So we
|
|
* know the parent must still be valid if the child sequence number is
|
|
*/
|
|
if (unlikely(!lockref_get_not_dead(&dentry->d_lockref)))
|
|
goto out;
|
|
if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
|
|
goto out_dput;
|
|
/*
|
|
* Sequence counts matched. Now make sure that the root is
|
|
* still valid and get it if required.
|
|
*/
|
|
if (unlikely(!legitimize_root(nd)))
|
|
goto out_dput;
|
|
rcu_read_unlock();
|
|
return true;
|
|
|
|
out2:
|
|
nd->path.mnt = NULL;
|
|
out1:
|
|
nd->path.dentry = NULL;
|
|
out:
|
|
rcu_read_unlock();
|
|
return false;
|
|
out_dput:
|
|
rcu_read_unlock();
|
|
dput(dentry);
|
|
return false;
|
|
}
|
|
|
|
static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
|
|
{
|
|
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
|
|
return dentry->d_op->d_revalidate(dentry, flags);
|
|
else
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* complete_walk - successful completion of path walk
|
|
* @nd: pointer nameidata
|
|
*
|
|
* If we had been in RCU mode, drop out of it and legitimize nd->path.
|
|
* Revalidate the final result, unless we'd already done that during
|
|
* the path walk or the filesystem doesn't ask for it. Return 0 on
|
|
* success, -error on failure. In case of failure caller does not
|
|
* need to drop nd->path.
|
|
*/
|
|
static int complete_walk(struct nameidata *nd)
|
|
{
|
|
struct dentry *dentry = nd->path.dentry;
|
|
int status;
|
|
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
/*
|
|
* We don't want to zero nd->root for scoped-lookups or
|
|
* externally-managed nd->root.
|
|
*/
|
|
if (!(nd->state & ND_ROOT_PRESET))
|
|
if (!(nd->flags & LOOKUP_IS_SCOPED))
|
|
nd->root.mnt = NULL;
|
|
nd->flags &= ~LOOKUP_CACHED;
|
|
if (!try_to_unlazy(nd))
|
|
return -ECHILD;
|
|
}
|
|
|
|
if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) {
|
|
/*
|
|
* While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't
|
|
* ever step outside the root during lookup" and should already
|
|
* be guaranteed by the rest of namei, we want to avoid a namei
|
|
* BUG resulting in userspace being given a path that was not
|
|
* scoped within the root at some point during the lookup.
|
|
*
|
|
* So, do a final sanity-check to make sure that in the
|
|
* worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED)
|
|
* we won't silently return an fd completely outside of the
|
|
* requested root to userspace.
|
|
*
|
|
* Userspace could move the path outside the root after this
|
|
* check, but as discussed elsewhere this is not a concern (the
|
|
* resolved file was inside the root at some point).
|
|
*/
|
|
if (!path_is_under(&nd->path, &nd->root))
|
|
return -EXDEV;
|
|
}
|
|
|
|
if (likely(!(nd->state & ND_JUMPED)))
|
|
return 0;
|
|
|
|
if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE)))
|
|
return 0;
|
|
|
|
status = dentry->d_op->d_weak_revalidate(dentry, nd->flags);
|
|
if (status > 0)
|
|
return 0;
|
|
|
|
if (!status)
|
|
status = -ESTALE;
|
|
|
|
return status;
|
|
}
|
|
|
|
static int set_root(struct nameidata *nd)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
|
|
/*
|
|
* Jumping to the real root in a scoped-lookup is a BUG in namei, but we
|
|
* still have to ensure it doesn't happen because it will cause a breakout
|
|
* from the dirfd.
|
|
*/
|
|
if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED))
|
|
return -ENOTRECOVERABLE;
|
|
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
unsigned seq;
|
|
|
|
do {
|
|
seq = read_seqcount_begin(&fs->seq);
|
|
nd->root = fs->root;
|
|
nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
|
|
} while (read_seqcount_retry(&fs->seq, seq));
|
|
} else {
|
|
get_fs_root(fs, &nd->root);
|
|
nd->state |= ND_ROOT_GRABBED;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int nd_jump_root(struct nameidata *nd)
|
|
{
|
|
if (unlikely(nd->flags & LOOKUP_BENEATH))
|
|
return -EXDEV;
|
|
if (unlikely(nd->flags & LOOKUP_NO_XDEV)) {
|
|
/* Absolute path arguments to path_init() are allowed. */
|
|
if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt)
|
|
return -EXDEV;
|
|
}
|
|
if (!nd->root.mnt) {
|
|
int error = set_root(nd);
|
|
if (error)
|
|
return error;
|
|
}
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
struct dentry *d;
|
|
nd->path = nd->root;
|
|
d = nd->path.dentry;
|
|
nd->inode = d->d_inode;
|
|
nd->seq = nd->root_seq;
|
|
if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
|
|
return -ECHILD;
|
|
} else {
|
|
path_put(&nd->path);
|
|
nd->path = nd->root;
|
|
path_get(&nd->path);
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
}
|
|
nd->state |= ND_JUMPED;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Helper to directly jump to a known parsed path from ->get_link,
|
|
* caller must have taken a reference to path beforehand.
|
|
*/
|
|
int nd_jump_link(struct path *path)
|
|
{
|
|
int error = -ELOOP;
|
|
struct nameidata *nd = current->nameidata;
|
|
|
|
if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS))
|
|
goto err;
|
|
|
|
error = -EXDEV;
|
|
if (unlikely(nd->flags & LOOKUP_NO_XDEV)) {
|
|
if (nd->path.mnt != path->mnt)
|
|
goto err;
|
|
}
|
|
/* Not currently safe for scoped-lookups. */
|
|
if (unlikely(nd->flags & LOOKUP_IS_SCOPED))
|
|
goto err;
|
|
|
|
path_put(&nd->path);
|
|
nd->path = *path;
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
nd->state |= ND_JUMPED;
|
|
return 0;
|
|
|
|
err:
|
|
path_put(path);
|
|
return error;
|
|
}
|
|
|
|
static inline void put_link(struct nameidata *nd)
|
|
{
|
|
struct saved *last = nd->stack + --nd->depth;
|
|
do_delayed_call(&last->done);
|
|
if (!(nd->flags & LOOKUP_RCU))
|
|
path_put(&last->link);
|
|
}
|
|
|
|
int sysctl_protected_symlinks __read_mostly = 0;
|
|
int sysctl_protected_hardlinks __read_mostly = 0;
|
|
int sysctl_protected_fifos __read_mostly;
|
|
int sysctl_protected_regular __read_mostly;
|
|
|
|
/**
|
|
* may_follow_link - Check symlink following for unsafe situations
|
|
* @nd: nameidata pathwalk data
|
|
*
|
|
* In the case of the sysctl_protected_symlinks sysctl being enabled,
|
|
* CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
|
|
* in a sticky world-writable directory. This is to protect privileged
|
|
* processes from failing races against path names that may change out
|
|
* from under them by way of other users creating malicious symlinks.
|
|
* It will permit symlinks to be followed only when outside a sticky
|
|
* world-writable directory, or when the uid of the symlink and follower
|
|
* match, or when the directory owner matches the symlink's owner.
|
|
*
|
|
* Returns 0 if following the symlink is allowed, -ve on error.
|
|
*/
|
|
static inline int may_follow_link(struct nameidata *nd, const struct inode *inode)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
kuid_t i_uid;
|
|
|
|
if (!sysctl_protected_symlinks)
|
|
return 0;
|
|
|
|
mnt_userns = mnt_user_ns(nd->path.mnt);
|
|
i_uid = i_uid_into_mnt(mnt_userns, inode);
|
|
/* Allowed if owner and follower match. */
|
|
if (uid_eq(current_cred()->fsuid, i_uid))
|
|
return 0;
|
|
|
|
/* Allowed if parent directory not sticky and world-writable. */
|
|
if ((nd->dir_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
|
|
return 0;
|
|
|
|
/* Allowed if parent directory and link owner match. */
|
|
if (uid_valid(nd->dir_uid) && uid_eq(nd->dir_uid, i_uid))
|
|
return 0;
|
|
|
|
if (nd->flags & LOOKUP_RCU)
|
|
return -ECHILD;
|
|
|
|
audit_inode(nd->name, nd->stack[0].link.dentry, 0);
|
|
audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link");
|
|
return -EACCES;
|
|
}
|
|
|
|
/**
|
|
* safe_hardlink_source - Check for safe hardlink conditions
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @inode: the source inode to hardlink from
|
|
*
|
|
* Return false if at least one of the following conditions:
|
|
* - inode is not a regular file
|
|
* - inode is setuid
|
|
* - inode is setgid and group-exec
|
|
* - access failure for read and write
|
|
*
|
|
* Otherwise returns true.
|
|
*/
|
|
static bool safe_hardlink_source(struct user_namespace *mnt_userns,
|
|
struct inode *inode)
|
|
{
|
|
umode_t mode = inode->i_mode;
|
|
|
|
/* Special files should not get pinned to the filesystem. */
|
|
if (!S_ISREG(mode))
|
|
return false;
|
|
|
|
/* Setuid files should not get pinned to the filesystem. */
|
|
if (mode & S_ISUID)
|
|
return false;
|
|
|
|
/* Executable setgid files should not get pinned to the filesystem. */
|
|
if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
|
|
return false;
|
|
|
|
/* Hardlinking to unreadable or unwritable sources is dangerous. */
|
|
if (inode_permission(mnt_userns, inode, MAY_READ | MAY_WRITE))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* may_linkat - Check permissions for creating a hardlink
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @link: the source to hardlink from
|
|
*
|
|
* Block hardlink when all of:
|
|
* - sysctl_protected_hardlinks enabled
|
|
* - fsuid does not match inode
|
|
* - hardlink source is unsafe (see safe_hardlink_source() above)
|
|
* - not CAP_FOWNER in a namespace with the inode owner uid mapped
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*
|
|
* Returns 0 if successful, -ve on error.
|
|
*/
|
|
int may_linkat(struct user_namespace *mnt_userns, struct path *link)
|
|
{
|
|
struct inode *inode = link->dentry->d_inode;
|
|
|
|
/* Inode writeback is not safe when the uid or gid are invalid. */
|
|
if (!uid_valid(i_uid_into_mnt(mnt_userns, inode)) ||
|
|
!gid_valid(i_gid_into_mnt(mnt_userns, inode)))
|
|
return -EOVERFLOW;
|
|
|
|
if (!sysctl_protected_hardlinks)
|
|
return 0;
|
|
|
|
/* Source inode owner (or CAP_FOWNER) can hardlink all they like,
|
|
* otherwise, it must be a safe source.
|
|
*/
|
|
if (safe_hardlink_source(mnt_userns, inode) ||
|
|
inode_owner_or_capable(mnt_userns, inode))
|
|
return 0;
|
|
|
|
audit_log_path_denied(AUDIT_ANOM_LINK, "linkat");
|
|
return -EPERM;
|
|
}
|
|
|
|
/**
|
|
* may_create_in_sticky - Check whether an O_CREAT open in a sticky directory
|
|
* should be allowed, or not, on files that already
|
|
* exist.
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @nd: nameidata pathwalk data
|
|
* @inode: the inode of the file to open
|
|
*
|
|
* Block an O_CREAT open of a FIFO (or a regular file) when:
|
|
* - sysctl_protected_fifos (or sysctl_protected_regular) is enabled
|
|
* - the file already exists
|
|
* - we are in a sticky directory
|
|
* - we don't own the file
|
|
* - the owner of the directory doesn't own the file
|
|
* - the directory is world writable
|
|
* If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2
|
|
* the directory doesn't have to be world writable: being group writable will
|
|
* be enough.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*
|
|
* Returns 0 if the open is allowed, -ve on error.
|
|
*/
|
|
static int may_create_in_sticky(struct user_namespace *mnt_userns,
|
|
struct nameidata *nd, struct inode *const inode)
|
|
{
|
|
umode_t dir_mode = nd->dir_mode;
|
|
kuid_t dir_uid = nd->dir_uid;
|
|
|
|
if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) ||
|
|
(!sysctl_protected_regular && S_ISREG(inode->i_mode)) ||
|
|
likely(!(dir_mode & S_ISVTX)) ||
|
|
uid_eq(i_uid_into_mnt(mnt_userns, inode), dir_uid) ||
|
|
uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)))
|
|
return 0;
|
|
|
|
if (likely(dir_mode & 0002) ||
|
|
(dir_mode & 0020 &&
|
|
((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) ||
|
|
(sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) {
|
|
const char *operation = S_ISFIFO(inode->i_mode) ?
|
|
"sticky_create_fifo" :
|
|
"sticky_create_regular";
|
|
audit_log_path_denied(AUDIT_ANOM_CREAT, operation);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* follow_up - Find the mountpoint of path's vfsmount
|
|
*
|
|
* Given a path, find the mountpoint of its source file system.
|
|
* Replace @path with the path of the mountpoint in the parent mount.
|
|
* Up is towards /.
|
|
*
|
|
* Return 1 if we went up a level and 0 if we were already at the
|
|
* root.
|
|
*/
|
|
int follow_up(struct path *path)
|
|
{
|
|
struct mount *mnt = real_mount(path->mnt);
|
|
struct mount *parent;
|
|
struct dentry *mountpoint;
|
|
|
|
read_seqlock_excl(&mount_lock);
|
|
parent = mnt->mnt_parent;
|
|
if (parent == mnt) {
|
|
read_sequnlock_excl(&mount_lock);
|
|
return 0;
|
|
}
|
|
mntget(&parent->mnt);
|
|
mountpoint = dget(mnt->mnt_mountpoint);
|
|
read_sequnlock_excl(&mount_lock);
|
|
dput(path->dentry);
|
|
path->dentry = mountpoint;
|
|
mntput(path->mnt);
|
|
path->mnt = &parent->mnt;
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(follow_up);
|
|
|
|
static bool choose_mountpoint_rcu(struct mount *m, const struct path *root,
|
|
struct path *path, unsigned *seqp)
|
|
{
|
|
while (mnt_has_parent(m)) {
|
|
struct dentry *mountpoint = m->mnt_mountpoint;
|
|
|
|
m = m->mnt_parent;
|
|
if (unlikely(root->dentry == mountpoint &&
|
|
root->mnt == &m->mnt))
|
|
break;
|
|
if (mountpoint != m->mnt.mnt_root) {
|
|
path->mnt = &m->mnt;
|
|
path->dentry = mountpoint;
|
|
*seqp = read_seqcount_begin(&mountpoint->d_seq);
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static bool choose_mountpoint(struct mount *m, const struct path *root,
|
|
struct path *path)
|
|
{
|
|
bool found;
|
|
|
|
rcu_read_lock();
|
|
while (1) {
|
|
unsigned seq, mseq = read_seqbegin(&mount_lock);
|
|
|
|
found = choose_mountpoint_rcu(m, root, path, &seq);
|
|
if (unlikely(!found)) {
|
|
if (!read_seqretry(&mount_lock, mseq))
|
|
break;
|
|
} else {
|
|
if (likely(__legitimize_path(path, seq, mseq)))
|
|
break;
|
|
rcu_read_unlock();
|
|
path_put(path);
|
|
rcu_read_lock();
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
return found;
|
|
}
|
|
|
|
/*
|
|
* Perform an automount
|
|
* - return -EISDIR to tell follow_managed() to stop and return the path we
|
|
* were called with.
|
|
*/
|
|
static int follow_automount(struct path *path, int *count, unsigned lookup_flags)
|
|
{
|
|
struct dentry *dentry = path->dentry;
|
|
|
|
/* We don't want to mount if someone's just doing a stat -
|
|
* unless they're stat'ing a directory and appended a '/' to
|
|
* the name.
|
|
*
|
|
* We do, however, want to mount if someone wants to open or
|
|
* create a file of any type under the mountpoint, wants to
|
|
* traverse through the mountpoint or wants to open the
|
|
* mounted directory. Also, autofs may mark negative dentries
|
|
* as being automount points. These will need the attentions
|
|
* of the daemon to instantiate them before they can be used.
|
|
*/
|
|
if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
|
|
LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
|
|
dentry->d_inode)
|
|
return -EISDIR;
|
|
|
|
if (count && (*count)++ >= MAXSYMLINKS)
|
|
return -ELOOP;
|
|
|
|
return finish_automount(dentry->d_op->d_automount(path), path);
|
|
}
|
|
|
|
/*
|
|
* mount traversal - out-of-line part. One note on ->d_flags accesses -
|
|
* dentries are pinned but not locked here, so negative dentry can go
|
|
* positive right under us. Use of smp_load_acquire() provides a barrier
|
|
* sufficient for ->d_inode and ->d_flags consistency.
|
|
*/
|
|
static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped,
|
|
int *count, unsigned lookup_flags)
|
|
{
|
|
struct vfsmount *mnt = path->mnt;
|
|
bool need_mntput = false;
|
|
int ret = 0;
|
|
|
|
while (flags & DCACHE_MANAGED_DENTRY) {
|
|
/* Allow the filesystem to manage the transit without i_mutex
|
|
* being held. */
|
|
if (flags & DCACHE_MANAGE_TRANSIT) {
|
|
ret = path->dentry->d_op->d_manage(path, false);
|
|
flags = smp_load_acquire(&path->dentry->d_flags);
|
|
if (ret < 0)
|
|
break;
|
|
}
|
|
|
|
if (flags & DCACHE_MOUNTED) { // something's mounted on it..
|
|
struct vfsmount *mounted = lookup_mnt(path);
|
|
if (mounted) { // ... in our namespace
|
|
dput(path->dentry);
|
|
if (need_mntput)
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
// here we know it's positive
|
|
flags = path->dentry->d_flags;
|
|
need_mntput = true;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
if (!(flags & DCACHE_NEED_AUTOMOUNT))
|
|
break;
|
|
|
|
// uncovered automount point
|
|
ret = follow_automount(path, count, lookup_flags);
|
|
flags = smp_load_acquire(&path->dentry->d_flags);
|
|
if (ret < 0)
|
|
break;
|
|
}
|
|
|
|
if (ret == -EISDIR)
|
|
ret = 0;
|
|
// possible if you race with several mount --move
|
|
if (need_mntput && path->mnt == mnt)
|
|
mntput(path->mnt);
|
|
if (!ret && unlikely(d_flags_negative(flags)))
|
|
ret = -ENOENT;
|
|
*jumped = need_mntput;
|
|
return ret;
|
|
}
|
|
|
|
static inline int traverse_mounts(struct path *path, bool *jumped,
|
|
int *count, unsigned lookup_flags)
|
|
{
|
|
unsigned flags = smp_load_acquire(&path->dentry->d_flags);
|
|
|
|
/* fastpath */
|
|
if (likely(!(flags & DCACHE_MANAGED_DENTRY))) {
|
|
*jumped = false;
|
|
if (unlikely(d_flags_negative(flags)))
|
|
return -ENOENT;
|
|
return 0;
|
|
}
|
|
return __traverse_mounts(path, flags, jumped, count, lookup_flags);
|
|
}
|
|
|
|
int follow_down_one(struct path *path)
|
|
{
|
|
struct vfsmount *mounted;
|
|
|
|
mounted = lookup_mnt(path);
|
|
if (mounted) {
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(follow_down_one);
|
|
|
|
/*
|
|
* Follow down to the covering mount currently visible to userspace. At each
|
|
* point, the filesystem owning that dentry may be queried as to whether the
|
|
* caller is permitted to proceed or not.
|
|
*/
|
|
int follow_down(struct path *path)
|
|
{
|
|
struct vfsmount *mnt = path->mnt;
|
|
bool jumped;
|
|
int ret = traverse_mounts(path, &jumped, NULL, 0);
|
|
|
|
if (path->mnt != mnt)
|
|
mntput(mnt);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(follow_down);
|
|
|
|
/*
|
|
* Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
|
|
* we meet a managed dentry that would need blocking.
|
|
*/
|
|
static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
|
|
struct inode **inode, unsigned *seqp)
|
|
{
|
|
struct dentry *dentry = path->dentry;
|
|
unsigned int flags = dentry->d_flags;
|
|
|
|
if (likely(!(flags & DCACHE_MANAGED_DENTRY)))
|
|
return true;
|
|
|
|
if (unlikely(nd->flags & LOOKUP_NO_XDEV))
|
|
return false;
|
|
|
|
for (;;) {
|
|
/*
|
|
* Don't forget we might have a non-mountpoint managed dentry
|
|
* that wants to block transit.
|
|
*/
|
|
if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) {
|
|
int res = dentry->d_op->d_manage(path, true);
|
|
if (res)
|
|
return res == -EISDIR;
|
|
flags = dentry->d_flags;
|
|
}
|
|
|
|
if (flags & DCACHE_MOUNTED) {
|
|
struct mount *mounted = __lookup_mnt(path->mnt, dentry);
|
|
if (mounted) {
|
|
path->mnt = &mounted->mnt;
|
|
dentry = path->dentry = mounted->mnt.mnt_root;
|
|
nd->state |= ND_JUMPED;
|
|
*seqp = read_seqcount_begin(&dentry->d_seq);
|
|
*inode = dentry->d_inode;
|
|
/*
|
|
* We don't need to re-check ->d_seq after this
|
|
* ->d_inode read - there will be an RCU delay
|
|
* between mount hash removal and ->mnt_root
|
|
* becoming unpinned.
|
|
*/
|
|
flags = dentry->d_flags;
|
|
continue;
|
|
}
|
|
if (read_seqretry(&mount_lock, nd->m_seq))
|
|
return false;
|
|
}
|
|
return !(flags & DCACHE_NEED_AUTOMOUNT);
|
|
}
|
|
}
|
|
|
|
static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
|
|
struct path *path, struct inode **inode,
|
|
unsigned int *seqp)
|
|
{
|
|
bool jumped;
|
|
int ret;
|
|
|
|
path->mnt = nd->path.mnt;
|
|
path->dentry = dentry;
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
unsigned int seq = *seqp;
|
|
if (unlikely(!*inode))
|
|
return -ENOENT;
|
|
if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
|
|
return 0;
|
|
if (!try_to_unlazy_next(nd, dentry, seq))
|
|
return -ECHILD;
|
|
// *path might've been clobbered by __follow_mount_rcu()
|
|
path->mnt = nd->path.mnt;
|
|
path->dentry = dentry;
|
|
}
|
|
ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags);
|
|
if (jumped) {
|
|
if (unlikely(nd->flags & LOOKUP_NO_XDEV))
|
|
ret = -EXDEV;
|
|
else
|
|
nd->state |= ND_JUMPED;
|
|
}
|
|
if (unlikely(ret)) {
|
|
dput(path->dentry);
|
|
if (path->mnt != nd->path.mnt)
|
|
mntput(path->mnt);
|
|
} else {
|
|
*inode = d_backing_inode(path->dentry);
|
|
*seqp = 0; /* out of RCU mode, so the value doesn't matter */
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This looks up the name in dcache and possibly revalidates the found dentry.
|
|
* NULL is returned if the dentry does not exist in the cache.
|
|
*/
|
|
static struct dentry *lookup_dcache(const struct qstr *name,
|
|
struct dentry *dir,
|
|
unsigned int flags)
|
|
{
|
|
struct dentry *dentry = d_lookup(dir, name);
|
|
if (dentry) {
|
|
int error = d_revalidate(dentry, flags);
|
|
if (unlikely(error <= 0)) {
|
|
if (!error)
|
|
d_invalidate(dentry);
|
|
dput(dentry);
|
|
return ERR_PTR(error);
|
|
}
|
|
}
|
|
return dentry;
|
|
}
|
|
|
|
/*
|
|
* Parent directory has inode locked exclusive. This is one
|
|
* and only case when ->lookup() gets called on non in-lookup
|
|
* dentries - as the matter of fact, this only gets called
|
|
* when directory is guaranteed to have no in-lookup children
|
|
* at all.
|
|
*/
|
|
static struct dentry *__lookup_hash(const struct qstr *name,
|
|
struct dentry *base, unsigned int flags)
|
|
{
|
|
struct dentry *dentry = lookup_dcache(name, base, flags);
|
|
struct dentry *old;
|
|
struct inode *dir = base->d_inode;
|
|
|
|
if (dentry)
|
|
return dentry;
|
|
|
|
/* Don't create child dentry for a dead directory. */
|
|
if (unlikely(IS_DEADDIR(dir)))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
dentry = d_alloc(base, name);
|
|
if (unlikely(!dentry))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
old = dir->i_op->lookup(dir, dentry, flags);
|
|
if (unlikely(old)) {
|
|
dput(dentry);
|
|
dentry = old;
|
|
}
|
|
return dentry;
|
|
}
|
|
|
|
static struct dentry *lookup_fast(struct nameidata *nd,
|
|
struct inode **inode,
|
|
unsigned *seqp)
|
|
{
|
|
struct dentry *dentry, *parent = nd->path.dentry;
|
|
int status = 1;
|
|
|
|
/*
|
|
* Rename seqlock is not required here because in the off chance
|
|
* of a false negative due to a concurrent rename, the caller is
|
|
* going to fall back to non-racy lookup.
|
|
*/
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
unsigned seq;
|
|
dentry = __d_lookup_rcu(parent, &nd->last, &seq);
|
|
if (unlikely(!dentry)) {
|
|
if (!try_to_unlazy(nd))
|
|
return ERR_PTR(-ECHILD);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* This sequence count validates that the inode matches
|
|
* the dentry name information from lookup.
|
|
*/
|
|
*inode = d_backing_inode(dentry);
|
|
if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
|
|
return ERR_PTR(-ECHILD);
|
|
|
|
/*
|
|
* This sequence count validates that the parent had no
|
|
* changes while we did the lookup of the dentry above.
|
|
*
|
|
* The memory barrier in read_seqcount_begin of child is
|
|
* enough, we can use __read_seqcount_retry here.
|
|
*/
|
|
if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq)))
|
|
return ERR_PTR(-ECHILD);
|
|
|
|
*seqp = seq;
|
|
status = d_revalidate(dentry, nd->flags);
|
|
if (likely(status > 0))
|
|
return dentry;
|
|
if (!try_to_unlazy_next(nd, dentry, seq))
|
|
return ERR_PTR(-ECHILD);
|
|
if (status == -ECHILD)
|
|
/* we'd been told to redo it in non-rcu mode */
|
|
status = d_revalidate(dentry, nd->flags);
|
|
} else {
|
|
dentry = __d_lookup(parent, &nd->last);
|
|
if (unlikely(!dentry))
|
|
return NULL;
|
|
status = d_revalidate(dentry, nd->flags);
|
|
}
|
|
if (unlikely(status <= 0)) {
|
|
if (!status)
|
|
d_invalidate(dentry);
|
|
dput(dentry);
|
|
return ERR_PTR(status);
|
|
}
|
|
return dentry;
|
|
}
|
|
|
|
/* Fast lookup failed, do it the slow way */
|
|
static struct dentry *__lookup_slow(const struct qstr *name,
|
|
struct dentry *dir,
|
|
unsigned int flags)
|
|
{
|
|
struct dentry *dentry, *old;
|
|
struct inode *inode = dir->d_inode;
|
|
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
|
|
|
|
/* Don't go there if it's already dead */
|
|
if (unlikely(IS_DEADDIR(inode)))
|
|
return ERR_PTR(-ENOENT);
|
|
again:
|
|
dentry = d_alloc_parallel(dir, name, &wq);
|
|
if (IS_ERR(dentry))
|
|
return dentry;
|
|
if (unlikely(!d_in_lookup(dentry))) {
|
|
int error = d_revalidate(dentry, flags);
|
|
if (unlikely(error <= 0)) {
|
|
if (!error) {
|
|
d_invalidate(dentry);
|
|
dput(dentry);
|
|
goto again;
|
|
}
|
|
dput(dentry);
|
|
dentry = ERR_PTR(error);
|
|
}
|
|
} else {
|
|
old = inode->i_op->lookup(inode, dentry, flags);
|
|
d_lookup_done(dentry);
|
|
if (unlikely(old)) {
|
|
dput(dentry);
|
|
dentry = old;
|
|
}
|
|
}
|
|
return dentry;
|
|
}
|
|
|
|
static struct dentry *lookup_slow(const struct qstr *name,
|
|
struct dentry *dir,
|
|
unsigned int flags)
|
|
{
|
|
struct inode *inode = dir->d_inode;
|
|
struct dentry *res;
|
|
inode_lock_shared(inode);
|
|
res = __lookup_slow(name, dir, flags);
|
|
inode_unlock_shared(inode);
|
|
return res;
|
|
}
|
|
|
|
static inline int may_lookup(struct user_namespace *mnt_userns,
|
|
struct nameidata *nd)
|
|
{
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
int err = inode_permission(mnt_userns, nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
|
|
if (err != -ECHILD || !try_to_unlazy(nd))
|
|
return err;
|
|
}
|
|
return inode_permission(mnt_userns, nd->inode, MAY_EXEC);
|
|
}
|
|
|
|
static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq)
|
|
{
|
|
if (unlikely(nd->total_link_count++ >= MAXSYMLINKS))
|
|
return -ELOOP;
|
|
|
|
if (likely(nd->depth != EMBEDDED_LEVELS))
|
|
return 0;
|
|
if (likely(nd->stack != nd->internal))
|
|
return 0;
|
|
if (likely(nd_alloc_stack(nd)))
|
|
return 0;
|
|
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
// we need to grab link before we do unlazy. And we can't skip
|
|
// unlazy even if we fail to grab the link - cleanup needs it
|
|
bool grabbed_link = legitimize_path(nd, link, seq);
|
|
|
|
if (!try_to_unlazy(nd) != 0 || !grabbed_link)
|
|
return -ECHILD;
|
|
|
|
if (nd_alloc_stack(nd))
|
|
return 0;
|
|
}
|
|
return -ENOMEM;
|
|
}
|
|
|
|
enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
|
|
|
|
static const char *pick_link(struct nameidata *nd, struct path *link,
|
|
struct inode *inode, unsigned seq, int flags)
|
|
{
|
|
struct saved *last;
|
|
const char *res;
|
|
int error = reserve_stack(nd, link, seq);
|
|
|
|
if (unlikely(error)) {
|
|
if (!(nd->flags & LOOKUP_RCU))
|
|
path_put(link);
|
|
return ERR_PTR(error);
|
|
}
|
|
last = nd->stack + nd->depth++;
|
|
last->link = *link;
|
|
clear_delayed_call(&last->done);
|
|
last->seq = seq;
|
|
|
|
if (flags & WALK_TRAILING) {
|
|
error = may_follow_link(nd, inode);
|
|
if (unlikely(error))
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS) ||
|
|
unlikely(link->mnt->mnt_flags & MNT_NOSYMFOLLOW))
|
|
return ERR_PTR(-ELOOP);
|
|
|
|
if (!(nd->flags & LOOKUP_RCU)) {
|
|
touch_atime(&last->link);
|
|
cond_resched();
|
|
} else if (atime_needs_update(&last->link, inode)) {
|
|
if (!try_to_unlazy(nd))
|
|
return ERR_PTR(-ECHILD);
|
|
touch_atime(&last->link);
|
|
}
|
|
|
|
error = security_inode_follow_link(link->dentry, inode,
|
|
nd->flags & LOOKUP_RCU);
|
|
if (unlikely(error))
|
|
return ERR_PTR(error);
|
|
|
|
res = READ_ONCE(inode->i_link);
|
|
if (!res) {
|
|
const char * (*get)(struct dentry *, struct inode *,
|
|
struct delayed_call *);
|
|
get = inode->i_op->get_link;
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
res = get(NULL, inode, &last->done);
|
|
if (res == ERR_PTR(-ECHILD) && try_to_unlazy(nd))
|
|
res = get(link->dentry, inode, &last->done);
|
|
} else {
|
|
res = get(link->dentry, inode, &last->done);
|
|
}
|
|
if (!res)
|
|
goto all_done;
|
|
if (IS_ERR(res))
|
|
return res;
|
|
}
|
|
if (*res == '/') {
|
|
error = nd_jump_root(nd);
|
|
if (unlikely(error))
|
|
return ERR_PTR(error);
|
|
while (unlikely(*++res == '/'))
|
|
;
|
|
}
|
|
if (*res)
|
|
return res;
|
|
all_done: // pure jump
|
|
put_link(nd);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Do we need to follow links? We _really_ want to be able
|
|
* to do this check without having to look at inode->i_op,
|
|
* so we keep a cache of "no, this doesn't need follow_link"
|
|
* for the common case.
|
|
*/
|
|
static const char *step_into(struct nameidata *nd, int flags,
|
|
struct dentry *dentry, struct inode *inode, unsigned seq)
|
|
{
|
|
struct path path;
|
|
int err = handle_mounts(nd, dentry, &path, &inode, &seq);
|
|
|
|
if (err < 0)
|
|
return ERR_PTR(err);
|
|
if (likely(!d_is_symlink(path.dentry)) ||
|
|
((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) ||
|
|
(flags & WALK_NOFOLLOW)) {
|
|
/* not a symlink or should not follow */
|
|
if (!(nd->flags & LOOKUP_RCU)) {
|
|
dput(nd->path.dentry);
|
|
if (nd->path.mnt != path.mnt)
|
|
mntput(nd->path.mnt);
|
|
}
|
|
nd->path = path;
|
|
nd->inode = inode;
|
|
nd->seq = seq;
|
|
return NULL;
|
|
}
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
/* make sure that d_is_symlink above matches inode */
|
|
if (read_seqcount_retry(&path.dentry->d_seq, seq))
|
|
return ERR_PTR(-ECHILD);
|
|
} else {
|
|
if (path.mnt == nd->path.mnt)
|
|
mntget(path.mnt);
|
|
}
|
|
return pick_link(nd, &path, inode, seq, flags);
|
|
}
|
|
|
|
static struct dentry *follow_dotdot_rcu(struct nameidata *nd,
|
|
struct inode **inodep,
|
|
unsigned *seqp)
|
|
{
|
|
struct dentry *parent, *old;
|
|
|
|
if (path_equal(&nd->path, &nd->root))
|
|
goto in_root;
|
|
if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) {
|
|
struct path path;
|
|
unsigned seq;
|
|
if (!choose_mountpoint_rcu(real_mount(nd->path.mnt),
|
|
&nd->root, &path, &seq))
|
|
goto in_root;
|
|
if (unlikely(nd->flags & LOOKUP_NO_XDEV))
|
|
return ERR_PTR(-ECHILD);
|
|
nd->path = path;
|
|
nd->inode = path.dentry->d_inode;
|
|
nd->seq = seq;
|
|
if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
|
|
return ERR_PTR(-ECHILD);
|
|
/* we know that mountpoint was pinned */
|
|
}
|
|
old = nd->path.dentry;
|
|
parent = old->d_parent;
|
|
*inodep = parent->d_inode;
|
|
*seqp = read_seqcount_begin(&parent->d_seq);
|
|
if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
|
|
return ERR_PTR(-ECHILD);
|
|
if (unlikely(!path_connected(nd->path.mnt, parent)))
|
|
return ERR_PTR(-ECHILD);
|
|
return parent;
|
|
in_root:
|
|
if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
|
|
return ERR_PTR(-ECHILD);
|
|
if (unlikely(nd->flags & LOOKUP_BENEATH))
|
|
return ERR_PTR(-ECHILD);
|
|
return NULL;
|
|
}
|
|
|
|
static struct dentry *follow_dotdot(struct nameidata *nd,
|
|
struct inode **inodep,
|
|
unsigned *seqp)
|
|
{
|
|
struct dentry *parent;
|
|
|
|
if (path_equal(&nd->path, &nd->root))
|
|
goto in_root;
|
|
if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) {
|
|
struct path path;
|
|
|
|
if (!choose_mountpoint(real_mount(nd->path.mnt),
|
|
&nd->root, &path))
|
|
goto in_root;
|
|
path_put(&nd->path);
|
|
nd->path = path;
|
|
nd->inode = path.dentry->d_inode;
|
|
if (unlikely(nd->flags & LOOKUP_NO_XDEV))
|
|
return ERR_PTR(-EXDEV);
|
|
}
|
|
/* rare case of legitimate dget_parent()... */
|
|
parent = dget_parent(nd->path.dentry);
|
|
if (unlikely(!path_connected(nd->path.mnt, parent))) {
|
|
dput(parent);
|
|
return ERR_PTR(-ENOENT);
|
|
}
|
|
*seqp = 0;
|
|
*inodep = parent->d_inode;
|
|
return parent;
|
|
|
|
in_root:
|
|
if (unlikely(nd->flags & LOOKUP_BENEATH))
|
|
return ERR_PTR(-EXDEV);
|
|
dget(nd->path.dentry);
|
|
return NULL;
|
|
}
|
|
|
|
static const char *handle_dots(struct nameidata *nd, int type)
|
|
{
|
|
if (type == LAST_DOTDOT) {
|
|
const char *error = NULL;
|
|
struct dentry *parent;
|
|
struct inode *inode;
|
|
unsigned seq;
|
|
|
|
if (!nd->root.mnt) {
|
|
error = ERR_PTR(set_root(nd));
|
|
if (error)
|
|
return error;
|
|
}
|
|
if (nd->flags & LOOKUP_RCU)
|
|
parent = follow_dotdot_rcu(nd, &inode, &seq);
|
|
else
|
|
parent = follow_dotdot(nd, &inode, &seq);
|
|
if (IS_ERR(parent))
|
|
return ERR_CAST(parent);
|
|
if (unlikely(!parent))
|
|
error = step_into(nd, WALK_NOFOLLOW,
|
|
nd->path.dentry, nd->inode, nd->seq);
|
|
else
|
|
error = step_into(nd, WALK_NOFOLLOW,
|
|
parent, inode, seq);
|
|
if (unlikely(error))
|
|
return error;
|
|
|
|
if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) {
|
|
/*
|
|
* If there was a racing rename or mount along our
|
|
* path, then we can't be sure that ".." hasn't jumped
|
|
* above nd->root (and so userspace should retry or use
|
|
* some fallback).
|
|
*/
|
|
smp_rmb();
|
|
if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq)))
|
|
return ERR_PTR(-EAGAIN);
|
|
if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq)))
|
|
return ERR_PTR(-EAGAIN);
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
static const char *walk_component(struct nameidata *nd, int flags)
|
|
{
|
|
struct dentry *dentry;
|
|
struct inode *inode;
|
|
unsigned seq;
|
|
/*
|
|
* "." and ".." are special - ".." especially so because it has
|
|
* to be able to know about the current root directory and
|
|
* parent relationships.
|
|
*/
|
|
if (unlikely(nd->last_type != LAST_NORM)) {
|
|
if (!(flags & WALK_MORE) && nd->depth)
|
|
put_link(nd);
|
|
return handle_dots(nd, nd->last_type);
|
|
}
|
|
dentry = lookup_fast(nd, &inode, &seq);
|
|
if (IS_ERR(dentry))
|
|
return ERR_CAST(dentry);
|
|
if (unlikely(!dentry)) {
|
|
dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags);
|
|
if (IS_ERR(dentry))
|
|
return ERR_CAST(dentry);
|
|
}
|
|
if (!(flags & WALK_MORE) && nd->depth)
|
|
put_link(nd);
|
|
return step_into(nd, flags, dentry, inode, seq);
|
|
}
|
|
|
|
/*
|
|
* We can do the critical dentry name comparison and hashing
|
|
* operations one word at a time, but we are limited to:
|
|
*
|
|
* - Architectures with fast unaligned word accesses. We could
|
|
* do a "get_unaligned()" if this helps and is sufficiently
|
|
* fast.
|
|
*
|
|
* - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
|
|
* do not trap on the (extremely unlikely) case of a page
|
|
* crossing operation.
|
|
*
|
|
* - Furthermore, we need an efficient 64-bit compile for the
|
|
* 64-bit case in order to generate the "number of bytes in
|
|
* the final mask". Again, that could be replaced with a
|
|
* efficient population count instruction or similar.
|
|
*/
|
|
#ifdef CONFIG_DCACHE_WORD_ACCESS
|
|
|
|
#include <asm/word-at-a-time.h>
|
|
|
|
#ifdef HASH_MIX
|
|
|
|
/* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
|
|
|
|
#elif defined(CONFIG_64BIT)
|
|
/*
|
|
* Register pressure in the mixing function is an issue, particularly
|
|
* on 32-bit x86, but almost any function requires one state value and
|
|
* one temporary. Instead, use a function designed for two state values
|
|
* and no temporaries.
|
|
*
|
|
* This function cannot create a collision in only two iterations, so
|
|
* we have two iterations to achieve avalanche. In those two iterations,
|
|
* we have six layers of mixing, which is enough to spread one bit's
|
|
* influence out to 2^6 = 64 state bits.
|
|
*
|
|
* Rotate constants are scored by considering either 64 one-bit input
|
|
* deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
|
|
* probability of that delta causing a change to each of the 128 output
|
|
* bits, using a sample of random initial states.
|
|
*
|
|
* The Shannon entropy of the computed probabilities is then summed
|
|
* to produce a score. Ideally, any input change has a 50% chance of
|
|
* toggling any given output bit.
|
|
*
|
|
* Mixing scores (in bits) for (12,45):
|
|
* Input delta: 1-bit 2-bit
|
|
* 1 round: 713.3 42542.6
|
|
* 2 rounds: 2753.7 140389.8
|
|
* 3 rounds: 5954.1 233458.2
|
|
* 4 rounds: 7862.6 256672.2
|
|
* Perfect: 8192 258048
|
|
* (64*128) (64*63/2 * 128)
|
|
*/
|
|
#define HASH_MIX(x, y, a) \
|
|
( x ^= (a), \
|
|
y ^= x, x = rol64(x,12),\
|
|
x += y, y = rol64(y,45),\
|
|
y *= 9 )
|
|
|
|
/*
|
|
* Fold two longs into one 32-bit hash value. This must be fast, but
|
|
* latency isn't quite as critical, as there is a fair bit of additional
|
|
* work done before the hash value is used.
|
|
*/
|
|
static inline unsigned int fold_hash(unsigned long x, unsigned long y)
|
|
{
|
|
y ^= x * GOLDEN_RATIO_64;
|
|
y *= GOLDEN_RATIO_64;
|
|
return y >> 32;
|
|
}
|
|
|
|
#else /* 32-bit case */
|
|
|
|
/*
|
|
* Mixing scores (in bits) for (7,20):
|
|
* Input delta: 1-bit 2-bit
|
|
* 1 round: 330.3 9201.6
|
|
* 2 rounds: 1246.4 25475.4
|
|
* 3 rounds: 1907.1 31295.1
|
|
* 4 rounds: 2042.3 31718.6
|
|
* Perfect: 2048 31744
|
|
* (32*64) (32*31/2 * 64)
|
|
*/
|
|
#define HASH_MIX(x, y, a) \
|
|
( x ^= (a), \
|
|
y ^= x, x = rol32(x, 7),\
|
|
x += y, y = rol32(y,20),\
|
|
y *= 9 )
|
|
|
|
static inline unsigned int fold_hash(unsigned long x, unsigned long y)
|
|
{
|
|
/* Use arch-optimized multiply if one exists */
|
|
return __hash_32(y ^ __hash_32(x));
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* Return the hash of a string of known length. This is carfully
|
|
* designed to match hash_name(), which is the more critical function.
|
|
* In particular, we must end by hashing a final word containing 0..7
|
|
* payload bytes, to match the way that hash_name() iterates until it
|
|
* finds the delimiter after the name.
|
|
*/
|
|
unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
|
|
{
|
|
unsigned long a, x = 0, y = (unsigned long)salt;
|
|
|
|
for (;;) {
|
|
if (!len)
|
|
goto done;
|
|
a = load_unaligned_zeropad(name);
|
|
if (len < sizeof(unsigned long))
|
|
break;
|
|
HASH_MIX(x, y, a);
|
|
name += sizeof(unsigned long);
|
|
len -= sizeof(unsigned long);
|
|
}
|
|
x ^= a & bytemask_from_count(len);
|
|
done:
|
|
return fold_hash(x, y);
|
|
}
|
|
EXPORT_SYMBOL(full_name_hash);
|
|
|
|
/* Return the "hash_len" (hash and length) of a null-terminated string */
|
|
u64 hashlen_string(const void *salt, const char *name)
|
|
{
|
|
unsigned long a = 0, x = 0, y = (unsigned long)salt;
|
|
unsigned long adata, mask, len;
|
|
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
|
|
|
|
len = 0;
|
|
goto inside;
|
|
|
|
do {
|
|
HASH_MIX(x, y, a);
|
|
len += sizeof(unsigned long);
|
|
inside:
|
|
a = load_unaligned_zeropad(name+len);
|
|
} while (!has_zero(a, &adata, &constants));
|
|
|
|
adata = prep_zero_mask(a, adata, &constants);
|
|
mask = create_zero_mask(adata);
|
|
x ^= a & zero_bytemask(mask);
|
|
|
|
return hashlen_create(fold_hash(x, y), len + find_zero(mask));
|
|
}
|
|
EXPORT_SYMBOL(hashlen_string);
|
|
|
|
/*
|
|
* Calculate the length and hash of the path component, and
|
|
* return the "hash_len" as the result.
|
|
*/
|
|
static inline u64 hash_name(const void *salt, const char *name)
|
|
{
|
|
unsigned long a = 0, b, x = 0, y = (unsigned long)salt;
|
|
unsigned long adata, bdata, mask, len;
|
|
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
|
|
|
|
len = 0;
|
|
goto inside;
|
|
|
|
do {
|
|
HASH_MIX(x, y, a);
|
|
len += sizeof(unsigned long);
|
|
inside:
|
|
a = load_unaligned_zeropad(name+len);
|
|
b = a ^ REPEAT_BYTE('/');
|
|
} while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
|
|
|
|
adata = prep_zero_mask(a, adata, &constants);
|
|
bdata = prep_zero_mask(b, bdata, &constants);
|
|
mask = create_zero_mask(adata | bdata);
|
|
x ^= a & zero_bytemask(mask);
|
|
|
|
return hashlen_create(fold_hash(x, y), len + find_zero(mask));
|
|
}
|
|
|
|
#else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
|
|
|
|
/* Return the hash of a string of known length */
|
|
unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
|
|
{
|
|
unsigned long hash = init_name_hash(salt);
|
|
while (len--)
|
|
hash = partial_name_hash((unsigned char)*name++, hash);
|
|
return end_name_hash(hash);
|
|
}
|
|
EXPORT_SYMBOL(full_name_hash);
|
|
|
|
/* Return the "hash_len" (hash and length) of a null-terminated string */
|
|
u64 hashlen_string(const void *salt, const char *name)
|
|
{
|
|
unsigned long hash = init_name_hash(salt);
|
|
unsigned long len = 0, c;
|
|
|
|
c = (unsigned char)*name;
|
|
while (c) {
|
|
len++;
|
|
hash = partial_name_hash(c, hash);
|
|
c = (unsigned char)name[len];
|
|
}
|
|
return hashlen_create(end_name_hash(hash), len);
|
|
}
|
|
EXPORT_SYMBOL(hashlen_string);
|
|
|
|
/*
|
|
* We know there's a real path component here of at least
|
|
* one character.
|
|
*/
|
|
static inline u64 hash_name(const void *salt, const char *name)
|
|
{
|
|
unsigned long hash = init_name_hash(salt);
|
|
unsigned long len = 0, c;
|
|
|
|
c = (unsigned char)*name;
|
|
do {
|
|
len++;
|
|
hash = partial_name_hash(c, hash);
|
|
c = (unsigned char)name[len];
|
|
} while (c && c != '/');
|
|
return hashlen_create(end_name_hash(hash), len);
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* Name resolution.
|
|
* This is the basic name resolution function, turning a pathname into
|
|
* the final dentry. We expect 'base' to be positive and a directory.
|
|
*
|
|
* Returns 0 and nd will have valid dentry and mnt on success.
|
|
* Returns error and drops reference to input namei data on failure.
|
|
*/
|
|
static int link_path_walk(const char *name, struct nameidata *nd)
|
|
{
|
|
int depth = 0; // depth <= nd->depth
|
|
int err;
|
|
|
|
nd->last_type = LAST_ROOT;
|
|
nd->flags |= LOOKUP_PARENT;
|
|
if (IS_ERR(name))
|
|
return PTR_ERR(name);
|
|
while (*name=='/')
|
|
name++;
|
|
if (!*name) {
|
|
nd->dir_mode = 0; // short-circuit the 'hardening' idiocy
|
|
return 0;
|
|
}
|
|
|
|
/* At this point we know we have a real path component. */
|
|
for(;;) {
|
|
struct user_namespace *mnt_userns;
|
|
const char *link;
|
|
u64 hash_len;
|
|
int type;
|
|
|
|
mnt_userns = mnt_user_ns(nd->path.mnt);
|
|
err = may_lookup(mnt_userns, nd);
|
|
if (err)
|
|
return err;
|
|
|
|
hash_len = hash_name(nd->path.dentry, name);
|
|
|
|
type = LAST_NORM;
|
|
if (name[0] == '.') switch (hashlen_len(hash_len)) {
|
|
case 2:
|
|
if (name[1] == '.') {
|
|
type = LAST_DOTDOT;
|
|
nd->state |= ND_JUMPED;
|
|
}
|
|
break;
|
|
case 1:
|
|
type = LAST_DOT;
|
|
}
|
|
if (likely(type == LAST_NORM)) {
|
|
struct dentry *parent = nd->path.dentry;
|
|
nd->state &= ~ND_JUMPED;
|
|
if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
|
|
struct qstr this = { { .hash_len = hash_len }, .name = name };
|
|
err = parent->d_op->d_hash(parent, &this);
|
|
if (err < 0)
|
|
return err;
|
|
hash_len = this.hash_len;
|
|
name = this.name;
|
|
}
|
|
}
|
|
|
|
nd->last.hash_len = hash_len;
|
|
nd->last.name = name;
|
|
nd->last_type = type;
|
|
|
|
name += hashlen_len(hash_len);
|
|
if (!*name)
|
|
goto OK;
|
|
/*
|
|
* If it wasn't NUL, we know it was '/'. Skip that
|
|
* slash, and continue until no more slashes.
|
|
*/
|
|
do {
|
|
name++;
|
|
} while (unlikely(*name == '/'));
|
|
if (unlikely(!*name)) {
|
|
OK:
|
|
/* pathname or trailing symlink, done */
|
|
if (!depth) {
|
|
nd->dir_uid = i_uid_into_mnt(mnt_userns, nd->inode);
|
|
nd->dir_mode = nd->inode->i_mode;
|
|
nd->flags &= ~LOOKUP_PARENT;
|
|
return 0;
|
|
}
|
|
/* last component of nested symlink */
|
|
name = nd->stack[--depth].name;
|
|
link = walk_component(nd, 0);
|
|
} else {
|
|
/* not the last component */
|
|
link = walk_component(nd, WALK_MORE);
|
|
}
|
|
if (unlikely(link)) {
|
|
if (IS_ERR(link))
|
|
return PTR_ERR(link);
|
|
/* a symlink to follow */
|
|
nd->stack[depth++].name = name;
|
|
name = link;
|
|
continue;
|
|
}
|
|
if (unlikely(!d_can_lookup(nd->path.dentry))) {
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
if (!try_to_unlazy(nd))
|
|
return -ECHILD;
|
|
}
|
|
return -ENOTDIR;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* must be paired with terminate_walk() */
|
|
static const char *path_init(struct nameidata *nd, unsigned flags)
|
|
{
|
|
int error;
|
|
const char *s = nd->name->name;
|
|
|
|
/* LOOKUP_CACHED requires RCU, ask caller to retry */
|
|
if ((flags & (LOOKUP_RCU | LOOKUP_CACHED)) == LOOKUP_CACHED)
|
|
return ERR_PTR(-EAGAIN);
|
|
|
|
if (!*s)
|
|
flags &= ~LOOKUP_RCU;
|
|
if (flags & LOOKUP_RCU)
|
|
rcu_read_lock();
|
|
|
|
nd->flags = flags;
|
|
nd->state |= ND_JUMPED;
|
|
|
|
nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount);
|
|
nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount);
|
|
smp_rmb();
|
|
|
|
if (nd->state & ND_ROOT_PRESET) {
|
|
struct dentry *root = nd->root.dentry;
|
|
struct inode *inode = root->d_inode;
|
|
if (*s && unlikely(!d_can_lookup(root)))
|
|
return ERR_PTR(-ENOTDIR);
|
|
nd->path = nd->root;
|
|
nd->inode = inode;
|
|
if (flags & LOOKUP_RCU) {
|
|
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
nd->root_seq = nd->seq;
|
|
} else {
|
|
path_get(&nd->path);
|
|
}
|
|
return s;
|
|
}
|
|
|
|
nd->root.mnt = NULL;
|
|
|
|
/* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */
|
|
if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) {
|
|
error = nd_jump_root(nd);
|
|
if (unlikely(error))
|
|
return ERR_PTR(error);
|
|
return s;
|
|
}
|
|
|
|
/* Relative pathname -- get the starting-point it is relative to. */
|
|
if (nd->dfd == AT_FDCWD) {
|
|
if (flags & LOOKUP_RCU) {
|
|
struct fs_struct *fs = current->fs;
|
|
unsigned seq;
|
|
|
|
do {
|
|
seq = read_seqcount_begin(&fs->seq);
|
|
nd->path = fs->pwd;
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
} while (read_seqcount_retry(&fs->seq, seq));
|
|
} else {
|
|
get_fs_pwd(current->fs, &nd->path);
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
}
|
|
} else {
|
|
/* Caller must check execute permissions on the starting path component */
|
|
struct fd f = fdget_raw(nd->dfd);
|
|
struct dentry *dentry;
|
|
|
|
if (!f.file)
|
|
return ERR_PTR(-EBADF);
|
|
|
|
dentry = f.file->f_path.dentry;
|
|
|
|
if (*s && unlikely(!d_can_lookup(dentry))) {
|
|
fdput(f);
|
|
return ERR_PTR(-ENOTDIR);
|
|
}
|
|
|
|
nd->path = f.file->f_path;
|
|
if (flags & LOOKUP_RCU) {
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
|
|
} else {
|
|
path_get(&nd->path);
|
|
nd->inode = nd->path.dentry->d_inode;
|
|
}
|
|
fdput(f);
|
|
}
|
|
|
|
/* For scoped-lookups we need to set the root to the dirfd as well. */
|
|
if (flags & LOOKUP_IS_SCOPED) {
|
|
nd->root = nd->path;
|
|
if (flags & LOOKUP_RCU) {
|
|
nd->root_seq = nd->seq;
|
|
} else {
|
|
path_get(&nd->root);
|
|
nd->state |= ND_ROOT_GRABBED;
|
|
}
|
|
}
|
|
return s;
|
|
}
|
|
|
|
static inline const char *lookup_last(struct nameidata *nd)
|
|
{
|
|
if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
|
|
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
|
|
return walk_component(nd, WALK_TRAILING);
|
|
}
|
|
|
|
static int handle_lookup_down(struct nameidata *nd)
|
|
{
|
|
if (!(nd->flags & LOOKUP_RCU))
|
|
dget(nd->path.dentry);
|
|
return PTR_ERR(step_into(nd, WALK_NOFOLLOW,
|
|
nd->path.dentry, nd->inode, nd->seq));
|
|
}
|
|
|
|
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
|
|
static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path)
|
|
{
|
|
const char *s = path_init(nd, flags);
|
|
int err;
|
|
|
|
if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) {
|
|
err = handle_lookup_down(nd);
|
|
if (unlikely(err < 0))
|
|
s = ERR_PTR(err);
|
|
}
|
|
|
|
while (!(err = link_path_walk(s, nd)) &&
|
|
(s = lookup_last(nd)) != NULL)
|
|
;
|
|
if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) {
|
|
err = handle_lookup_down(nd);
|
|
nd->state &= ~ND_JUMPED; // no d_weak_revalidate(), please...
|
|
}
|
|
if (!err)
|
|
err = complete_walk(nd);
|
|
|
|
if (!err && nd->flags & LOOKUP_DIRECTORY)
|
|
if (!d_can_lookup(nd->path.dentry))
|
|
err = -ENOTDIR;
|
|
if (!err) {
|
|
*path = nd->path;
|
|
nd->path.mnt = NULL;
|
|
nd->path.dentry = NULL;
|
|
}
|
|
terminate_walk(nd);
|
|
return err;
|
|
}
|
|
|
|
int filename_lookup(int dfd, struct filename *name, unsigned flags,
|
|
struct path *path, struct path *root)
|
|
{
|
|
int retval;
|
|
struct nameidata nd;
|
|
if (IS_ERR(name))
|
|
return PTR_ERR(name);
|
|
set_nameidata(&nd, dfd, name, root);
|
|
retval = path_lookupat(&nd, flags | LOOKUP_RCU, path);
|
|
if (unlikely(retval == -ECHILD))
|
|
retval = path_lookupat(&nd, flags, path);
|
|
if (unlikely(retval == -ESTALE))
|
|
retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path);
|
|
|
|
if (likely(!retval))
|
|
audit_inode(name, path->dentry,
|
|
flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0);
|
|
restore_nameidata();
|
|
return retval;
|
|
}
|
|
|
|
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
|
|
static int path_parentat(struct nameidata *nd, unsigned flags,
|
|
struct path *parent)
|
|
{
|
|
const char *s = path_init(nd, flags);
|
|
int err = link_path_walk(s, nd);
|
|
if (!err)
|
|
err = complete_walk(nd);
|
|
if (!err) {
|
|
*parent = nd->path;
|
|
nd->path.mnt = NULL;
|
|
nd->path.dentry = NULL;
|
|
}
|
|
terminate_walk(nd);
|
|
return err;
|
|
}
|
|
|
|
/* Note: this does not consume "name" */
|
|
static int filename_parentat(int dfd, struct filename *name,
|
|
unsigned int flags, struct path *parent,
|
|
struct qstr *last, int *type)
|
|
{
|
|
int retval;
|
|
struct nameidata nd;
|
|
|
|
if (IS_ERR(name))
|
|
return PTR_ERR(name);
|
|
set_nameidata(&nd, dfd, name, NULL);
|
|
retval = path_parentat(&nd, flags | LOOKUP_RCU, parent);
|
|
if (unlikely(retval == -ECHILD))
|
|
retval = path_parentat(&nd, flags, parent);
|
|
if (unlikely(retval == -ESTALE))
|
|
retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent);
|
|
if (likely(!retval)) {
|
|
*last = nd.last;
|
|
*type = nd.last_type;
|
|
audit_inode(name, parent->dentry, AUDIT_INODE_PARENT);
|
|
}
|
|
restore_nameidata();
|
|
return retval;
|
|
}
|
|
|
|
/* does lookup, returns the object with parent locked */
|
|
static struct dentry *__kern_path_locked(struct filename *name, struct path *path)
|
|
{
|
|
struct dentry *d;
|
|
struct qstr last;
|
|
int type, error;
|
|
|
|
error = filename_parentat(AT_FDCWD, name, 0, path, &last, &type);
|
|
if (error)
|
|
return ERR_PTR(error);
|
|
if (unlikely(type != LAST_NORM)) {
|
|
path_put(path);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
|
|
d = __lookup_hash(&last, path->dentry, 0);
|
|
if (IS_ERR(d)) {
|
|
inode_unlock(path->dentry->d_inode);
|
|
path_put(path);
|
|
}
|
|
return d;
|
|
}
|
|
|
|
struct dentry *kern_path_locked(const char *name, struct path *path)
|
|
{
|
|
struct filename *filename = getname_kernel(name);
|
|
struct dentry *res = __kern_path_locked(filename, path);
|
|
|
|
putname(filename);
|
|
return res;
|
|
}
|
|
|
|
int kern_path(const char *name, unsigned int flags, struct path *path)
|
|
{
|
|
struct filename *filename = getname_kernel(name);
|
|
int ret = filename_lookup(AT_FDCWD, filename, flags, path, NULL);
|
|
|
|
putname(filename);
|
|
return ret;
|
|
|
|
}
|
|
EXPORT_SYMBOL(kern_path);
|
|
|
|
/**
|
|
* vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @mnt: pointer to vfs mount of the base directory
|
|
* @name: pointer to file name
|
|
* @flags: lookup flags
|
|
* @path: pointer to struct path to fill
|
|
*/
|
|
int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
|
|
const char *name, unsigned int flags,
|
|
struct path *path)
|
|
{
|
|
struct filename *filename;
|
|
struct path root = {.mnt = mnt, .dentry = dentry};
|
|
int ret;
|
|
|
|
filename = getname_kernel(name);
|
|
/* the first argument of filename_lookup() is ignored with root */
|
|
ret = filename_lookup(AT_FDCWD, filename, flags, path, &root);
|
|
putname(filename);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(vfs_path_lookup);
|
|
|
|
static int lookup_one_common(struct user_namespace *mnt_userns,
|
|
const char *name, struct dentry *base, int len,
|
|
struct qstr *this)
|
|
{
|
|
this->name = name;
|
|
this->len = len;
|
|
this->hash = full_name_hash(base, name, len);
|
|
if (!len)
|
|
return -EACCES;
|
|
|
|
if (unlikely(name[0] == '.')) {
|
|
if (len < 2 || (len == 2 && name[1] == '.'))
|
|
return -EACCES;
|
|
}
|
|
|
|
while (len--) {
|
|
unsigned int c = *(const unsigned char *)name++;
|
|
if (c == '/' || c == '\0')
|
|
return -EACCES;
|
|
}
|
|
/*
|
|
* See if the low-level filesystem might want
|
|
* to use its own hash..
|
|
*/
|
|
if (base->d_flags & DCACHE_OP_HASH) {
|
|
int err = base->d_op->d_hash(base, this);
|
|
if (err < 0)
|
|
return err;
|
|
}
|
|
|
|
return inode_permission(mnt_userns, base->d_inode, MAY_EXEC);
|
|
}
|
|
|
|
/**
|
|
* try_lookup_one_len - filesystem helper to lookup single pathname component
|
|
* @name: pathname component to lookup
|
|
* @base: base directory to lookup from
|
|
* @len: maximum length @len should be interpreted to
|
|
*
|
|
* Look up a dentry by name in the dcache, returning NULL if it does not
|
|
* currently exist. The function does not try to create a dentry.
|
|
*
|
|
* Note that this routine is purely a helper for filesystem usage and should
|
|
* not be called by generic code.
|
|
*
|
|
* The caller must hold base->i_mutex.
|
|
*/
|
|
struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len)
|
|
{
|
|
struct qstr this;
|
|
int err;
|
|
|
|
WARN_ON_ONCE(!inode_is_locked(base->d_inode));
|
|
|
|
err = lookup_one_common(&init_user_ns, name, base, len, &this);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
return lookup_dcache(&this, base, 0);
|
|
}
|
|
EXPORT_SYMBOL(try_lookup_one_len);
|
|
|
|
/**
|
|
* lookup_one_len - filesystem helper to lookup single pathname component
|
|
* @name: pathname component to lookup
|
|
* @base: base directory to lookup from
|
|
* @len: maximum length @len should be interpreted to
|
|
*
|
|
* Note that this routine is purely a helper for filesystem usage and should
|
|
* not be called by generic code.
|
|
*
|
|
* The caller must hold base->i_mutex.
|
|
*/
|
|
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
|
|
{
|
|
struct dentry *dentry;
|
|
struct qstr this;
|
|
int err;
|
|
|
|
WARN_ON_ONCE(!inode_is_locked(base->d_inode));
|
|
|
|
err = lookup_one_common(&init_user_ns, name, base, len, &this);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
dentry = lookup_dcache(&this, base, 0);
|
|
return dentry ? dentry : __lookup_slow(&this, base, 0);
|
|
}
|
|
EXPORT_SYMBOL(lookup_one_len);
|
|
|
|
/**
|
|
* lookup_one - filesystem helper to lookup single pathname component
|
|
* @mnt_userns: user namespace of the mount the lookup is performed from
|
|
* @name: pathname component to lookup
|
|
* @base: base directory to lookup from
|
|
* @len: maximum length @len should be interpreted to
|
|
*
|
|
* Note that this routine is purely a helper for filesystem usage and should
|
|
* not be called by generic code.
|
|
*
|
|
* The caller must hold base->i_mutex.
|
|
*/
|
|
struct dentry *lookup_one(struct user_namespace *mnt_userns, const char *name,
|
|
struct dentry *base, int len)
|
|
{
|
|
struct dentry *dentry;
|
|
struct qstr this;
|
|
int err;
|
|
|
|
WARN_ON_ONCE(!inode_is_locked(base->d_inode));
|
|
|
|
err = lookup_one_common(mnt_userns, name, base, len, &this);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
dentry = lookup_dcache(&this, base, 0);
|
|
return dentry ? dentry : __lookup_slow(&this, base, 0);
|
|
}
|
|
EXPORT_SYMBOL(lookup_one);
|
|
|
|
/**
|
|
* lookup_one_len_unlocked - filesystem helper to lookup single pathname component
|
|
* @name: pathname component to lookup
|
|
* @base: base directory to lookup from
|
|
* @len: maximum length @len should be interpreted to
|
|
*
|
|
* Note that this routine is purely a helper for filesystem usage and should
|
|
* not be called by generic code.
|
|
*
|
|
* Unlike lookup_one_len, it should be called without the parent
|
|
* i_mutex held, and will take the i_mutex itself if necessary.
|
|
*/
|
|
struct dentry *lookup_one_len_unlocked(const char *name,
|
|
struct dentry *base, int len)
|
|
{
|
|
struct qstr this;
|
|
int err;
|
|
struct dentry *ret;
|
|
|
|
err = lookup_one_common(&init_user_ns, name, base, len, &this);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
ret = lookup_dcache(&this, base, 0);
|
|
if (!ret)
|
|
ret = lookup_slow(&this, base, 0);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(lookup_one_len_unlocked);
|
|
|
|
/*
|
|
* Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT)
|
|
* on negatives. Returns known positive or ERR_PTR(); that's what
|
|
* most of the users want. Note that pinned negative with unlocked parent
|
|
* _can_ become positive at any time, so callers of lookup_one_len_unlocked()
|
|
* need to be very careful; pinned positives have ->d_inode stable, so
|
|
* this one avoids such problems.
|
|
*/
|
|
struct dentry *lookup_positive_unlocked(const char *name,
|
|
struct dentry *base, int len)
|
|
{
|
|
struct dentry *ret = lookup_one_len_unlocked(name, base, len);
|
|
if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
|
|
dput(ret);
|
|
ret = ERR_PTR(-ENOENT);
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(lookup_positive_unlocked);
|
|
|
|
#ifdef CONFIG_UNIX98_PTYS
|
|
int path_pts(struct path *path)
|
|
{
|
|
/* Find something mounted on "pts" in the same directory as
|
|
* the input path.
|
|
*/
|
|
struct dentry *parent = dget_parent(path->dentry);
|
|
struct dentry *child;
|
|
struct qstr this = QSTR_INIT("pts", 3);
|
|
|
|
if (unlikely(!path_connected(path->mnt, parent))) {
|
|
dput(parent);
|
|
return -ENOENT;
|
|
}
|
|
dput(path->dentry);
|
|
path->dentry = parent;
|
|
child = d_hash_and_lookup(parent, &this);
|
|
if (!child)
|
|
return -ENOENT;
|
|
|
|
path->dentry = child;
|
|
dput(parent);
|
|
follow_down(path);
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
|
|
struct path *path, int *empty)
|
|
{
|
|
struct filename *filename = getname_flags(name, flags, empty);
|
|
int ret = filename_lookup(dfd, filename, flags, path, NULL);
|
|
|
|
putname(filename);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(user_path_at_empty);
|
|
|
|
int __check_sticky(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct inode *inode)
|
|
{
|
|
kuid_t fsuid = current_fsuid();
|
|
|
|
if (uid_eq(i_uid_into_mnt(mnt_userns, inode), fsuid))
|
|
return 0;
|
|
if (uid_eq(i_uid_into_mnt(mnt_userns, dir), fsuid))
|
|
return 0;
|
|
return !capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FOWNER);
|
|
}
|
|
EXPORT_SYMBOL(__check_sticky);
|
|
|
|
/*
|
|
* Check whether we can remove a link victim from directory dir, check
|
|
* whether the type of victim is right.
|
|
* 1. We can't do it if dir is read-only (done in permission())
|
|
* 2. We should have write and exec permissions on dir
|
|
* 3. We can't remove anything from append-only dir
|
|
* 4. We can't do anything with immutable dir (done in permission())
|
|
* 5. If the sticky bit on dir is set we should either
|
|
* a. be owner of dir, or
|
|
* b. be owner of victim, or
|
|
* c. have CAP_FOWNER capability
|
|
* 6. If the victim is append-only or immutable we can't do antyhing with
|
|
* links pointing to it.
|
|
* 7. If the victim has an unknown uid or gid we can't change the inode.
|
|
* 8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
|
|
* 9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
|
|
* 10. We can't remove a root or mountpoint.
|
|
* 11. We don't allow removal of NFS sillyrenamed files; it's handled by
|
|
* nfs_async_unlink().
|
|
*/
|
|
static int may_delete(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct dentry *victim, bool isdir)
|
|
{
|
|
struct inode *inode = d_backing_inode(victim);
|
|
int error;
|
|
|
|
if (d_is_negative(victim))
|
|
return -ENOENT;
|
|
BUG_ON(!inode);
|
|
|
|
BUG_ON(victim->d_parent->d_inode != dir);
|
|
|
|
/* Inode writeback is not safe when the uid or gid are invalid. */
|
|
if (!uid_valid(i_uid_into_mnt(mnt_userns, inode)) ||
|
|
!gid_valid(i_gid_into_mnt(mnt_userns, inode)))
|
|
return -EOVERFLOW;
|
|
|
|
audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
|
|
|
|
error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
|
|
if (error)
|
|
return error;
|
|
if (IS_APPEND(dir))
|
|
return -EPERM;
|
|
|
|
if (check_sticky(mnt_userns, dir, inode) || IS_APPEND(inode) ||
|
|
IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) ||
|
|
HAS_UNMAPPED_ID(mnt_userns, inode))
|
|
return -EPERM;
|
|
if (isdir) {
|
|
if (!d_is_dir(victim))
|
|
return -ENOTDIR;
|
|
if (IS_ROOT(victim))
|
|
return -EBUSY;
|
|
} else if (d_is_dir(victim))
|
|
return -EISDIR;
|
|
if (IS_DEADDIR(dir))
|
|
return -ENOENT;
|
|
if (victim->d_flags & DCACHE_NFSFS_RENAMED)
|
|
return -EBUSY;
|
|
return 0;
|
|
}
|
|
|
|
/* Check whether we can create an object with dentry child in directory
|
|
* dir.
|
|
* 1. We can't do it if child already exists (open has special treatment for
|
|
* this case, but since we are inlined it's OK)
|
|
* 2. We can't do it if dir is read-only (done in permission())
|
|
* 3. We can't do it if the fs can't represent the fsuid or fsgid.
|
|
* 4. We should have write and exec permissions on dir
|
|
* 5. We can't do it if dir is immutable (done in permission())
|
|
*/
|
|
static inline int may_create(struct user_namespace *mnt_userns,
|
|
struct inode *dir, struct dentry *child)
|
|
{
|
|
audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
|
|
if (child->d_inode)
|
|
return -EEXIST;
|
|
if (IS_DEADDIR(dir))
|
|
return -ENOENT;
|
|
if (!fsuidgid_has_mapping(dir->i_sb, mnt_userns))
|
|
return -EOVERFLOW;
|
|
|
|
return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
|
|
}
|
|
|
|
/*
|
|
* p1 and p2 should be directories on the same fs.
|
|
*/
|
|
struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
|
|
{
|
|
struct dentry *p;
|
|
|
|
if (p1 == p2) {
|
|
inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
|
|
return NULL;
|
|
}
|
|
|
|
mutex_lock(&p1->d_sb->s_vfs_rename_mutex);
|
|
|
|
p = d_ancestor(p2, p1);
|
|
if (p) {
|
|
inode_lock_nested(p2->d_inode, I_MUTEX_PARENT);
|
|
inode_lock_nested(p1->d_inode, I_MUTEX_CHILD);
|
|
return p;
|
|
}
|
|
|
|
p = d_ancestor(p1, p2);
|
|
if (p) {
|
|
inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
|
|
inode_lock_nested(p2->d_inode, I_MUTEX_CHILD);
|
|
return p;
|
|
}
|
|
|
|
inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
|
|
inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(lock_rename);
|
|
|
|
void unlock_rename(struct dentry *p1, struct dentry *p2)
|
|
{
|
|
inode_unlock(p1->d_inode);
|
|
if (p1 != p2) {
|
|
inode_unlock(p2->d_inode);
|
|
mutex_unlock(&p1->d_sb->s_vfs_rename_mutex);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(unlock_rename);
|
|
|
|
/**
|
|
* vfs_create - create new file
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @dir: inode of @dentry
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @mode: mode of the new file
|
|
* @want_excl: whether the file must not yet exist
|
|
*
|
|
* Create a new file.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
int vfs_create(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct dentry *dentry, umode_t mode, bool want_excl)
|
|
{
|
|
int error = may_create(mnt_userns, dir, dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->create)
|
|
return -EACCES; /* shouldn't it be ENOSYS? */
|
|
mode &= S_IALLUGO;
|
|
mode |= S_IFREG;
|
|
error = security_inode_create(dir, dentry, mode);
|
|
if (error)
|
|
return error;
|
|
error = dir->i_op->create(mnt_userns, dir, dentry, mode, want_excl);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_create);
|
|
|
|
int vfs_mkobj(struct dentry *dentry, umode_t mode,
|
|
int (*f)(struct dentry *, umode_t, void *),
|
|
void *arg)
|
|
{
|
|
struct inode *dir = dentry->d_parent->d_inode;
|
|
int error = may_create(&init_user_ns, dir, dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
mode &= S_IALLUGO;
|
|
mode |= S_IFREG;
|
|
error = security_inode_create(dir, dentry, mode);
|
|
if (error)
|
|
return error;
|
|
error = f(dentry, mode, arg);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_mkobj);
|
|
|
|
bool may_open_dev(const struct path *path)
|
|
{
|
|
return !(path->mnt->mnt_flags & MNT_NODEV) &&
|
|
!(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
|
|
}
|
|
|
|
static int may_open(struct user_namespace *mnt_userns, const struct path *path,
|
|
int acc_mode, int flag)
|
|
{
|
|
struct dentry *dentry = path->dentry;
|
|
struct inode *inode = dentry->d_inode;
|
|
int error;
|
|
|
|
if (!inode)
|
|
return -ENOENT;
|
|
|
|
switch (inode->i_mode & S_IFMT) {
|
|
case S_IFLNK:
|
|
return -ELOOP;
|
|
case S_IFDIR:
|
|
if (acc_mode & MAY_WRITE)
|
|
return -EISDIR;
|
|
if (acc_mode & MAY_EXEC)
|
|
return -EACCES;
|
|
break;
|
|
case S_IFBLK:
|
|
case S_IFCHR:
|
|
if (!may_open_dev(path))
|
|
return -EACCES;
|
|
fallthrough;
|
|
case S_IFIFO:
|
|
case S_IFSOCK:
|
|
if (acc_mode & MAY_EXEC)
|
|
return -EACCES;
|
|
flag &= ~O_TRUNC;
|
|
break;
|
|
case S_IFREG:
|
|
if ((acc_mode & MAY_EXEC) && path_noexec(path))
|
|
return -EACCES;
|
|
break;
|
|
}
|
|
|
|
error = inode_permission(mnt_userns, inode, MAY_OPEN | acc_mode);
|
|
if (error)
|
|
return error;
|
|
|
|
/*
|
|
* An append-only file must be opened in append mode for writing.
|
|
*/
|
|
if (IS_APPEND(inode)) {
|
|
if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
|
|
return -EPERM;
|
|
if (flag & O_TRUNC)
|
|
return -EPERM;
|
|
}
|
|
|
|
/* O_NOATIME can only be set by the owner or superuser */
|
|
if (flag & O_NOATIME && !inode_owner_or_capable(mnt_userns, inode))
|
|
return -EPERM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int handle_truncate(struct user_namespace *mnt_userns, struct file *filp)
|
|
{
|
|
const struct path *path = &filp->f_path;
|
|
struct inode *inode = path->dentry->d_inode;
|
|
int error = get_write_access(inode);
|
|
if (error)
|
|
return error;
|
|
/*
|
|
* Refuse to truncate files with mandatory locks held on them.
|
|
*/
|
|
error = security_path_truncate(path);
|
|
if (!error) {
|
|
error = do_truncate(mnt_userns, path->dentry, 0,
|
|
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
|
|
filp);
|
|
}
|
|
put_write_access(inode);
|
|
return error;
|
|
}
|
|
|
|
static inline int open_to_namei_flags(int flag)
|
|
{
|
|
if ((flag & O_ACCMODE) == 3)
|
|
flag--;
|
|
return flag;
|
|
}
|
|
|
|
static int may_o_create(struct user_namespace *mnt_userns,
|
|
const struct path *dir, struct dentry *dentry,
|
|
umode_t mode)
|
|
{
|
|
int error = security_path_mknod(dir, dentry, mode, 0);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!fsuidgid_has_mapping(dir->dentry->d_sb, mnt_userns))
|
|
return -EOVERFLOW;
|
|
|
|
error = inode_permission(mnt_userns, dir->dentry->d_inode,
|
|
MAY_WRITE | MAY_EXEC);
|
|
if (error)
|
|
return error;
|
|
|
|
return security_inode_create(dir->dentry->d_inode, dentry, mode);
|
|
}
|
|
|
|
/*
|
|
* Attempt to atomically look up, create and open a file from a negative
|
|
* dentry.
|
|
*
|
|
* Returns 0 if successful. The file will have been created and attached to
|
|
* @file by the filesystem calling finish_open().
|
|
*
|
|
* If the file was looked up only or didn't need creating, FMODE_OPENED won't
|
|
* be set. The caller will need to perform the open themselves. @path will
|
|
* have been updated to point to the new dentry. This may be negative.
|
|
*
|
|
* Returns an error code otherwise.
|
|
*/
|
|
static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry,
|
|
struct file *file,
|
|
int open_flag, umode_t mode)
|
|
{
|
|
struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
|
|
struct inode *dir = nd->path.dentry->d_inode;
|
|
int error;
|
|
|
|
if (nd->flags & LOOKUP_DIRECTORY)
|
|
open_flag |= O_DIRECTORY;
|
|
|
|
file->f_path.dentry = DENTRY_NOT_SET;
|
|
file->f_path.mnt = nd->path.mnt;
|
|
error = dir->i_op->atomic_open(dir, dentry, file,
|
|
open_to_namei_flags(open_flag), mode);
|
|
d_lookup_done(dentry);
|
|
if (!error) {
|
|
if (file->f_mode & FMODE_OPENED) {
|
|
if (unlikely(dentry != file->f_path.dentry)) {
|
|
dput(dentry);
|
|
dentry = dget(file->f_path.dentry);
|
|
}
|
|
} else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
|
|
error = -EIO;
|
|
} else {
|
|
if (file->f_path.dentry) {
|
|
dput(dentry);
|
|
dentry = file->f_path.dentry;
|
|
}
|
|
if (unlikely(d_is_negative(dentry)))
|
|
error = -ENOENT;
|
|
}
|
|
}
|
|
if (error) {
|
|
dput(dentry);
|
|
dentry = ERR_PTR(error);
|
|
}
|
|
return dentry;
|
|
}
|
|
|
|
/*
|
|
* Look up and maybe create and open the last component.
|
|
*
|
|
* Must be called with parent locked (exclusive in O_CREAT case).
|
|
*
|
|
* Returns 0 on success, that is, if
|
|
* the file was successfully atomically created (if necessary) and opened, or
|
|
* the file was not completely opened at this time, though lookups and
|
|
* creations were performed.
|
|
* These case are distinguished by presence of FMODE_OPENED on file->f_mode.
|
|
* In the latter case dentry returned in @path might be negative if O_CREAT
|
|
* hadn't been specified.
|
|
*
|
|
* An error code is returned on failure.
|
|
*/
|
|
static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
|
|
const struct open_flags *op,
|
|
bool got_write)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
struct dentry *dir = nd->path.dentry;
|
|
struct inode *dir_inode = dir->d_inode;
|
|
int open_flag = op->open_flag;
|
|
struct dentry *dentry;
|
|
int error, create_error = 0;
|
|
umode_t mode = op->mode;
|
|
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
|
|
|
|
if (unlikely(IS_DEADDIR(dir_inode)))
|
|
return ERR_PTR(-ENOENT);
|
|
|
|
file->f_mode &= ~FMODE_CREATED;
|
|
dentry = d_lookup(dir, &nd->last);
|
|
for (;;) {
|
|
if (!dentry) {
|
|
dentry = d_alloc_parallel(dir, &nd->last, &wq);
|
|
if (IS_ERR(dentry))
|
|
return dentry;
|
|
}
|
|
if (d_in_lookup(dentry))
|
|
break;
|
|
|
|
error = d_revalidate(dentry, nd->flags);
|
|
if (likely(error > 0))
|
|
break;
|
|
if (error)
|
|
goto out_dput;
|
|
d_invalidate(dentry);
|
|
dput(dentry);
|
|
dentry = NULL;
|
|
}
|
|
if (dentry->d_inode) {
|
|
/* Cached positive dentry: will open in f_op->open */
|
|
return dentry;
|
|
}
|
|
|
|
/*
|
|
* Checking write permission is tricky, bacuse we don't know if we are
|
|
* going to actually need it: O_CREAT opens should work as long as the
|
|
* file exists. But checking existence breaks atomicity. The trick is
|
|
* to check access and if not granted clear O_CREAT from the flags.
|
|
*
|
|
* Another problem is returing the "right" error value (e.g. for an
|
|
* O_EXCL open we want to return EEXIST not EROFS).
|
|
*/
|
|
if (unlikely(!got_write))
|
|
open_flag &= ~O_TRUNC;
|
|
mnt_userns = mnt_user_ns(nd->path.mnt);
|
|
if (open_flag & O_CREAT) {
|
|
if (open_flag & O_EXCL)
|
|
open_flag &= ~O_TRUNC;
|
|
if (!IS_POSIXACL(dir->d_inode))
|
|
mode &= ~current_umask();
|
|
if (likely(got_write))
|
|
create_error = may_o_create(mnt_userns, &nd->path,
|
|
dentry, mode);
|
|
else
|
|
create_error = -EROFS;
|
|
}
|
|
if (create_error)
|
|
open_flag &= ~O_CREAT;
|
|
if (dir_inode->i_op->atomic_open) {
|
|
dentry = atomic_open(nd, dentry, file, open_flag, mode);
|
|
if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT))
|
|
dentry = ERR_PTR(create_error);
|
|
return dentry;
|
|
}
|
|
|
|
if (d_in_lookup(dentry)) {
|
|
struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry,
|
|
nd->flags);
|
|
d_lookup_done(dentry);
|
|
if (unlikely(res)) {
|
|
if (IS_ERR(res)) {
|
|
error = PTR_ERR(res);
|
|
goto out_dput;
|
|
}
|
|
dput(dentry);
|
|
dentry = res;
|
|
}
|
|
}
|
|
|
|
/* Negative dentry, just create the file */
|
|
if (!dentry->d_inode && (open_flag & O_CREAT)) {
|
|
file->f_mode |= FMODE_CREATED;
|
|
audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
|
|
if (!dir_inode->i_op->create) {
|
|
error = -EACCES;
|
|
goto out_dput;
|
|
}
|
|
|
|
error = dir_inode->i_op->create(mnt_userns, dir_inode, dentry,
|
|
mode, open_flag & O_EXCL);
|
|
if (error)
|
|
goto out_dput;
|
|
}
|
|
if (unlikely(create_error) && !dentry->d_inode) {
|
|
error = create_error;
|
|
goto out_dput;
|
|
}
|
|
return dentry;
|
|
|
|
out_dput:
|
|
dput(dentry);
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
static const char *open_last_lookups(struct nameidata *nd,
|
|
struct file *file, const struct open_flags *op)
|
|
{
|
|
struct dentry *dir = nd->path.dentry;
|
|
int open_flag = op->open_flag;
|
|
bool got_write = false;
|
|
unsigned seq;
|
|
struct inode *inode;
|
|
struct dentry *dentry;
|
|
const char *res;
|
|
|
|
nd->flags |= op->intent;
|
|
|
|
if (nd->last_type != LAST_NORM) {
|
|
if (nd->depth)
|
|
put_link(nd);
|
|
return handle_dots(nd, nd->last_type);
|
|
}
|
|
|
|
if (!(open_flag & O_CREAT)) {
|
|
if (nd->last.name[nd->last.len])
|
|
nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
/* we _can_ be in RCU mode here */
|
|
dentry = lookup_fast(nd, &inode, &seq);
|
|
if (IS_ERR(dentry))
|
|
return ERR_CAST(dentry);
|
|
if (likely(dentry))
|
|
goto finish_lookup;
|
|
|
|
BUG_ON(nd->flags & LOOKUP_RCU);
|
|
} else {
|
|
/* create side of things */
|
|
if (nd->flags & LOOKUP_RCU) {
|
|
if (!try_to_unlazy(nd))
|
|
return ERR_PTR(-ECHILD);
|
|
}
|
|
audit_inode(nd->name, dir, AUDIT_INODE_PARENT);
|
|
/* trailing slashes? */
|
|
if (unlikely(nd->last.name[nd->last.len]))
|
|
return ERR_PTR(-EISDIR);
|
|
}
|
|
|
|
if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
|
|
got_write = !mnt_want_write(nd->path.mnt);
|
|
/*
|
|
* do _not_ fail yet - we might not need that or fail with
|
|
* a different error; let lookup_open() decide; we'll be
|
|
* dropping this one anyway.
|
|
*/
|
|
}
|
|
if (open_flag & O_CREAT)
|
|
inode_lock(dir->d_inode);
|
|
else
|
|
inode_lock_shared(dir->d_inode);
|
|
dentry = lookup_open(nd, file, op, got_write);
|
|
if (!IS_ERR(dentry) && (file->f_mode & FMODE_CREATED))
|
|
fsnotify_create(dir->d_inode, dentry);
|
|
if (open_flag & O_CREAT)
|
|
inode_unlock(dir->d_inode);
|
|
else
|
|
inode_unlock_shared(dir->d_inode);
|
|
|
|
if (got_write)
|
|
mnt_drop_write(nd->path.mnt);
|
|
|
|
if (IS_ERR(dentry))
|
|
return ERR_CAST(dentry);
|
|
|
|
if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) {
|
|
dput(nd->path.dentry);
|
|
nd->path.dentry = dentry;
|
|
return NULL;
|
|
}
|
|
|
|
finish_lookup:
|
|
if (nd->depth)
|
|
put_link(nd);
|
|
res = step_into(nd, WALK_TRAILING, dentry, inode, seq);
|
|
if (unlikely(res))
|
|
nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Handle the last step of open()
|
|
*/
|
|
static int do_open(struct nameidata *nd,
|
|
struct file *file, const struct open_flags *op)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
int open_flag = op->open_flag;
|
|
bool do_truncate;
|
|
int acc_mode;
|
|
int error;
|
|
|
|
if (!(file->f_mode & (FMODE_OPENED | FMODE_CREATED))) {
|
|
error = complete_walk(nd);
|
|
if (error)
|
|
return error;
|
|
}
|
|
if (!(file->f_mode & FMODE_CREATED))
|
|
audit_inode(nd->name, nd->path.dentry, 0);
|
|
mnt_userns = mnt_user_ns(nd->path.mnt);
|
|
if (open_flag & O_CREAT) {
|
|
if ((open_flag & O_EXCL) && !(file->f_mode & FMODE_CREATED))
|
|
return -EEXIST;
|
|
if (d_is_dir(nd->path.dentry))
|
|
return -EISDIR;
|
|
error = may_create_in_sticky(mnt_userns, nd,
|
|
d_backing_inode(nd->path.dentry));
|
|
if (unlikely(error))
|
|
return error;
|
|
}
|
|
if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
|
|
return -ENOTDIR;
|
|
|
|
do_truncate = false;
|
|
acc_mode = op->acc_mode;
|
|
if (file->f_mode & FMODE_CREATED) {
|
|
/* Don't check for write permission, don't truncate */
|
|
open_flag &= ~O_TRUNC;
|
|
acc_mode = 0;
|
|
} else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) {
|
|
error = mnt_want_write(nd->path.mnt);
|
|
if (error)
|
|
return error;
|
|
do_truncate = true;
|
|
}
|
|
error = may_open(mnt_userns, &nd->path, acc_mode, open_flag);
|
|
if (!error && !(file->f_mode & FMODE_OPENED))
|
|
error = vfs_open(&nd->path, file);
|
|
if (!error)
|
|
error = ima_file_check(file, op->acc_mode);
|
|
if (!error && do_truncate)
|
|
error = handle_truncate(mnt_userns, file);
|
|
if (unlikely(error > 0)) {
|
|
WARN_ON(1);
|
|
error = -EINVAL;
|
|
}
|
|
if (do_truncate)
|
|
mnt_drop_write(nd->path.mnt);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* vfs_tmpfile - create tmpfile
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @mode: mode of the new tmpfile
|
|
* @open_flag: flags
|
|
*
|
|
* Create a temporary file.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
|
|
struct dentry *dentry, umode_t mode, int open_flag)
|
|
{
|
|
struct dentry *child = NULL;
|
|
struct inode *dir = dentry->d_inode;
|
|
struct inode *inode;
|
|
int error;
|
|
|
|
/* we want directory to be writable */
|
|
error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
|
|
if (error)
|
|
goto out_err;
|
|
error = -EOPNOTSUPP;
|
|
if (!dir->i_op->tmpfile)
|
|
goto out_err;
|
|
error = -ENOMEM;
|
|
child = d_alloc(dentry, &slash_name);
|
|
if (unlikely(!child))
|
|
goto out_err;
|
|
error = dir->i_op->tmpfile(mnt_userns, dir, child, mode);
|
|
if (error)
|
|
goto out_err;
|
|
error = -ENOENT;
|
|
inode = child->d_inode;
|
|
if (unlikely(!inode))
|
|
goto out_err;
|
|
if (!(open_flag & O_EXCL)) {
|
|
spin_lock(&inode->i_lock);
|
|
inode->i_state |= I_LINKABLE;
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
ima_post_create_tmpfile(mnt_userns, inode);
|
|
return child;
|
|
|
|
out_err:
|
|
dput(child);
|
|
return ERR_PTR(error);
|
|
}
|
|
EXPORT_SYMBOL(vfs_tmpfile);
|
|
|
|
static int do_tmpfile(struct nameidata *nd, unsigned flags,
|
|
const struct open_flags *op,
|
|
struct file *file)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
struct dentry *child;
|
|
struct path path;
|
|
int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path);
|
|
if (unlikely(error))
|
|
return error;
|
|
error = mnt_want_write(path.mnt);
|
|
if (unlikely(error))
|
|
goto out;
|
|
mnt_userns = mnt_user_ns(path.mnt);
|
|
child = vfs_tmpfile(mnt_userns, path.dentry, op->mode, op->open_flag);
|
|
error = PTR_ERR(child);
|
|
if (IS_ERR(child))
|
|
goto out2;
|
|
dput(path.dentry);
|
|
path.dentry = child;
|
|
audit_inode(nd->name, child, 0);
|
|
/* Don't check for other permissions, the inode was just created */
|
|
error = may_open(mnt_userns, &path, 0, op->open_flag);
|
|
if (!error)
|
|
error = vfs_open(&path, file);
|
|
out2:
|
|
mnt_drop_write(path.mnt);
|
|
out:
|
|
path_put(&path);
|
|
return error;
|
|
}
|
|
|
|
static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file)
|
|
{
|
|
struct path path;
|
|
int error = path_lookupat(nd, flags, &path);
|
|
if (!error) {
|
|
audit_inode(nd->name, path.dentry, 0);
|
|
error = vfs_open(&path, file);
|
|
path_put(&path);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
static struct file *path_openat(struct nameidata *nd,
|
|
const struct open_flags *op, unsigned flags)
|
|
{
|
|
struct file *file;
|
|
int error;
|
|
|
|
file = alloc_empty_file(op->open_flag, current_cred());
|
|
if (IS_ERR(file))
|
|
return file;
|
|
|
|
if (unlikely(file->f_flags & __O_TMPFILE)) {
|
|
error = do_tmpfile(nd, flags, op, file);
|
|
} else if (unlikely(file->f_flags & O_PATH)) {
|
|
error = do_o_path(nd, flags, file);
|
|
} else {
|
|
const char *s = path_init(nd, flags);
|
|
while (!(error = link_path_walk(s, nd)) &&
|
|
(s = open_last_lookups(nd, file, op)) != NULL)
|
|
;
|
|
if (!error)
|
|
error = do_open(nd, file, op);
|
|
terminate_walk(nd);
|
|
}
|
|
if (likely(!error)) {
|
|
if (likely(file->f_mode & FMODE_OPENED))
|
|
return file;
|
|
WARN_ON(1);
|
|
error = -EINVAL;
|
|
}
|
|
fput(file);
|
|
if (error == -EOPENSTALE) {
|
|
if (flags & LOOKUP_RCU)
|
|
error = -ECHILD;
|
|
else
|
|
error = -ESTALE;
|
|
}
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
struct file *do_filp_open(int dfd, struct filename *pathname,
|
|
const struct open_flags *op)
|
|
{
|
|
struct nameidata nd;
|
|
int flags = op->lookup_flags;
|
|
struct file *filp;
|
|
|
|
set_nameidata(&nd, dfd, pathname, NULL);
|
|
filp = path_openat(&nd, op, flags | LOOKUP_RCU);
|
|
if (unlikely(filp == ERR_PTR(-ECHILD)))
|
|
filp = path_openat(&nd, op, flags);
|
|
if (unlikely(filp == ERR_PTR(-ESTALE)))
|
|
filp = path_openat(&nd, op, flags | LOOKUP_REVAL);
|
|
restore_nameidata();
|
|
return filp;
|
|
}
|
|
|
|
struct file *do_file_open_root(const struct path *root,
|
|
const char *name, const struct open_flags *op)
|
|
{
|
|
struct nameidata nd;
|
|
struct file *file;
|
|
struct filename *filename;
|
|
int flags = op->lookup_flags;
|
|
|
|
if (d_is_symlink(root->dentry) && op->intent & LOOKUP_OPEN)
|
|
return ERR_PTR(-ELOOP);
|
|
|
|
filename = getname_kernel(name);
|
|
if (IS_ERR(filename))
|
|
return ERR_CAST(filename);
|
|
|
|
set_nameidata(&nd, -1, filename, root);
|
|
file = path_openat(&nd, op, flags | LOOKUP_RCU);
|
|
if (unlikely(file == ERR_PTR(-ECHILD)))
|
|
file = path_openat(&nd, op, flags);
|
|
if (unlikely(file == ERR_PTR(-ESTALE)))
|
|
file = path_openat(&nd, op, flags | LOOKUP_REVAL);
|
|
restore_nameidata();
|
|
putname(filename);
|
|
return file;
|
|
}
|
|
|
|
static struct dentry *filename_create(int dfd, struct filename *name,
|
|
struct path *path, unsigned int lookup_flags)
|
|
{
|
|
struct dentry *dentry = ERR_PTR(-EEXIST);
|
|
struct qstr last;
|
|
int type;
|
|
int err2;
|
|
int error;
|
|
bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);
|
|
|
|
/*
|
|
* Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
|
|
* other flags passed in are ignored!
|
|
*/
|
|
lookup_flags &= LOOKUP_REVAL;
|
|
|
|
error = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
|
|
if (error)
|
|
return ERR_PTR(error);
|
|
|
|
/*
|
|
* Yucky last component or no last component at all?
|
|
* (foo/., foo/.., /////)
|
|
*/
|
|
if (unlikely(type != LAST_NORM))
|
|
goto out;
|
|
|
|
/* don't fail immediately if it's r/o, at least try to report other errors */
|
|
err2 = mnt_want_write(path->mnt);
|
|
/*
|
|
* Do the final lookup.
|
|
*/
|
|
lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL;
|
|
inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
|
|
dentry = __lookup_hash(&last, path->dentry, lookup_flags);
|
|
if (IS_ERR(dentry))
|
|
goto unlock;
|
|
|
|
error = -EEXIST;
|
|
if (d_is_positive(dentry))
|
|
goto fail;
|
|
|
|
/*
|
|
* Special case - lookup gave negative, but... we had foo/bar/
|
|
* From the vfs_mknod() POV we just have a negative dentry -
|
|
* all is fine. Let's be bastards - you had / on the end, you've
|
|
* been asking for (non-existent) directory. -ENOENT for you.
|
|
*/
|
|
if (unlikely(!is_dir && last.name[last.len])) {
|
|
error = -ENOENT;
|
|
goto fail;
|
|
}
|
|
if (unlikely(err2)) {
|
|
error = err2;
|
|
goto fail;
|
|
}
|
|
return dentry;
|
|
fail:
|
|
dput(dentry);
|
|
dentry = ERR_PTR(error);
|
|
unlock:
|
|
inode_unlock(path->dentry->d_inode);
|
|
if (!err2)
|
|
mnt_drop_write(path->mnt);
|
|
out:
|
|
path_put(path);
|
|
return dentry;
|
|
}
|
|
|
|
struct dentry *kern_path_create(int dfd, const char *pathname,
|
|
struct path *path, unsigned int lookup_flags)
|
|
{
|
|
struct filename *filename = getname_kernel(pathname);
|
|
struct dentry *res = filename_create(dfd, filename, path, lookup_flags);
|
|
|
|
putname(filename);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(kern_path_create);
|
|
|
|
void done_path_create(struct path *path, struct dentry *dentry)
|
|
{
|
|
dput(dentry);
|
|
inode_unlock(path->dentry->d_inode);
|
|
mnt_drop_write(path->mnt);
|
|
path_put(path);
|
|
}
|
|
EXPORT_SYMBOL(done_path_create);
|
|
|
|
inline struct dentry *user_path_create(int dfd, const char __user *pathname,
|
|
struct path *path, unsigned int lookup_flags)
|
|
{
|
|
struct filename *filename = getname(pathname);
|
|
struct dentry *res = filename_create(dfd, filename, path, lookup_flags);
|
|
|
|
putname(filename);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(user_path_create);
|
|
|
|
/**
|
|
* vfs_mknod - create device node or file
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @dir: inode of @dentry
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @mode: mode of the new device node or file
|
|
* @dev: device number of device to create
|
|
*
|
|
* Create a device node or file.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
int vfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct dentry *dentry, umode_t mode, dev_t dev)
|
|
{
|
|
bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV;
|
|
int error = may_create(mnt_userns, dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if ((S_ISCHR(mode) || S_ISBLK(mode)) && !is_whiteout &&
|
|
!capable(CAP_MKNOD))
|
|
return -EPERM;
|
|
|
|
if (!dir->i_op->mknod)
|
|
return -EPERM;
|
|
|
|
error = devcgroup_inode_mknod(mode, dev);
|
|
if (error)
|
|
return error;
|
|
|
|
error = security_inode_mknod(dir, dentry, mode, dev);
|
|
if (error)
|
|
return error;
|
|
|
|
error = dir->i_op->mknod(mnt_userns, dir, dentry, mode, dev);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_mknod);
|
|
|
|
static int may_mknod(umode_t mode)
|
|
{
|
|
switch (mode & S_IFMT) {
|
|
case S_IFREG:
|
|
case S_IFCHR:
|
|
case S_IFBLK:
|
|
case S_IFIFO:
|
|
case S_IFSOCK:
|
|
case 0: /* zero mode translates to S_IFREG */
|
|
return 0;
|
|
case S_IFDIR:
|
|
return -EPERM;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
static int do_mknodat(int dfd, struct filename *name, umode_t mode,
|
|
unsigned int dev)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = 0;
|
|
|
|
error = may_mknod(mode);
|
|
if (error)
|
|
goto out1;
|
|
retry:
|
|
dentry = filename_create(dfd, name, &path, lookup_flags);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto out1;
|
|
|
|
if (!IS_POSIXACL(path.dentry->d_inode))
|
|
mode &= ~current_umask();
|
|
error = security_path_mknod(&path, dentry, mode, dev);
|
|
if (error)
|
|
goto out2;
|
|
|
|
mnt_userns = mnt_user_ns(path.mnt);
|
|
switch (mode & S_IFMT) {
|
|
case 0: case S_IFREG:
|
|
error = vfs_create(mnt_userns, path.dentry->d_inode,
|
|
dentry, mode, true);
|
|
if (!error)
|
|
ima_post_path_mknod(mnt_userns, dentry);
|
|
break;
|
|
case S_IFCHR: case S_IFBLK:
|
|
error = vfs_mknod(mnt_userns, path.dentry->d_inode,
|
|
dentry, mode, new_decode_dev(dev));
|
|
break;
|
|
case S_IFIFO: case S_IFSOCK:
|
|
error = vfs_mknod(mnt_userns, path.dentry->d_inode,
|
|
dentry, mode, 0);
|
|
break;
|
|
}
|
|
out2:
|
|
done_path_create(&path, dentry);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out1:
|
|
putname(name);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
|
|
unsigned int, dev)
|
|
{
|
|
return do_mknodat(dfd, getname(filename), mode, dev);
|
|
}
|
|
|
|
SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
|
|
{
|
|
return do_mknodat(AT_FDCWD, getname(filename), mode, dev);
|
|
}
|
|
|
|
/**
|
|
* vfs_mkdir - create directory
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @dir: inode of @dentry
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @mode: mode of the new directory
|
|
*
|
|
* Create a directory.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
int vfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct dentry *dentry, umode_t mode)
|
|
{
|
|
int error = may_create(mnt_userns, dir, dentry);
|
|
unsigned max_links = dir->i_sb->s_max_links;
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->mkdir)
|
|
return -EPERM;
|
|
|
|
mode &= (S_IRWXUGO|S_ISVTX);
|
|
error = security_inode_mkdir(dir, dentry, mode);
|
|
if (error)
|
|
return error;
|
|
|
|
if (max_links && dir->i_nlink >= max_links)
|
|
return -EMLINK;
|
|
|
|
error = dir->i_op->mkdir(mnt_userns, dir, dentry, mode);
|
|
if (!error)
|
|
fsnotify_mkdir(dir, dentry);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_mkdir);
|
|
|
|
int do_mkdirat(int dfd, struct filename *name, umode_t mode)
|
|
{
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_DIRECTORY;
|
|
|
|
retry:
|
|
dentry = filename_create(dfd, name, &path, lookup_flags);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto out_putname;
|
|
|
|
if (!IS_POSIXACL(path.dentry->d_inode))
|
|
mode &= ~current_umask();
|
|
error = security_path_mkdir(&path, dentry, mode);
|
|
if (!error) {
|
|
struct user_namespace *mnt_userns;
|
|
mnt_userns = mnt_user_ns(path.mnt);
|
|
error = vfs_mkdir(mnt_userns, path.dentry->d_inode, dentry,
|
|
mode);
|
|
}
|
|
done_path_create(&path, dentry);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out_putname:
|
|
putname(name);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
|
|
{
|
|
return do_mkdirat(dfd, getname(pathname), mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
|
|
{
|
|
return do_mkdirat(AT_FDCWD, getname(pathname), mode);
|
|
}
|
|
|
|
/**
|
|
* vfs_rmdir - remove directory
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @dir: inode of @dentry
|
|
* @dentry: pointer to dentry of the base directory
|
|
*
|
|
* Remove a directory.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
int vfs_rmdir(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct dentry *dentry)
|
|
{
|
|
int error = may_delete(mnt_userns, dir, dentry, 1);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->rmdir)
|
|
return -EPERM;
|
|
|
|
dget(dentry);
|
|
inode_lock(dentry->d_inode);
|
|
|
|
error = -EBUSY;
|
|
if (is_local_mountpoint(dentry))
|
|
goto out;
|
|
|
|
error = security_inode_rmdir(dir, dentry);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = dir->i_op->rmdir(dir, dentry);
|
|
if (error)
|
|
goto out;
|
|
|
|
shrink_dcache_parent(dentry);
|
|
dentry->d_inode->i_flags |= S_DEAD;
|
|
dont_mount(dentry);
|
|
detach_mounts(dentry);
|
|
fsnotify_rmdir(dir, dentry);
|
|
|
|
out:
|
|
inode_unlock(dentry->d_inode);
|
|
dput(dentry);
|
|
if (!error)
|
|
d_delete(dentry);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_rmdir);
|
|
|
|
int do_rmdir(int dfd, struct filename *name)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
int error;
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
struct qstr last;
|
|
int type;
|
|
unsigned int lookup_flags = 0;
|
|
retry:
|
|
error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
|
|
if (error)
|
|
goto exit1;
|
|
|
|
switch (type) {
|
|
case LAST_DOTDOT:
|
|
error = -ENOTEMPTY;
|
|
goto exit2;
|
|
case LAST_DOT:
|
|
error = -EINVAL;
|
|
goto exit2;
|
|
case LAST_ROOT:
|
|
error = -EBUSY;
|
|
goto exit2;
|
|
}
|
|
|
|
error = mnt_want_write(path.mnt);
|
|
if (error)
|
|
goto exit2;
|
|
|
|
inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
|
|
dentry = __lookup_hash(&last, path.dentry, lookup_flags);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto exit3;
|
|
if (!dentry->d_inode) {
|
|
error = -ENOENT;
|
|
goto exit4;
|
|
}
|
|
error = security_path_rmdir(&path, dentry);
|
|
if (error)
|
|
goto exit4;
|
|
mnt_userns = mnt_user_ns(path.mnt);
|
|
error = vfs_rmdir(mnt_userns, path.dentry->d_inode, dentry);
|
|
exit4:
|
|
dput(dentry);
|
|
exit3:
|
|
inode_unlock(path.dentry->d_inode);
|
|
mnt_drop_write(path.mnt);
|
|
exit2:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
exit1:
|
|
putname(name);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
|
|
{
|
|
return do_rmdir(AT_FDCWD, getname(pathname));
|
|
}
|
|
|
|
/**
|
|
* vfs_unlink - unlink a filesystem object
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @dir: parent directory
|
|
* @dentry: victim
|
|
* @delegated_inode: returns victim inode, if the inode is delegated.
|
|
*
|
|
* The caller must hold dir->i_mutex.
|
|
*
|
|
* If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
|
|
* return a reference to the inode in delegated_inode. The caller
|
|
* should then break the delegation on that inode and retry. Because
|
|
* breaking a delegation may take a long time, the caller should drop
|
|
* dir->i_mutex before doing so.
|
|
*
|
|
* Alternatively, a caller may pass NULL for delegated_inode. This may
|
|
* be appropriate for callers that expect the underlying filesystem not
|
|
* to be NFS exported.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
int vfs_unlink(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct dentry *dentry, struct inode **delegated_inode)
|
|
{
|
|
struct inode *target = dentry->d_inode;
|
|
int error = may_delete(mnt_userns, dir, dentry, 0);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->unlink)
|
|
return -EPERM;
|
|
|
|
inode_lock(target);
|
|
if (IS_SWAPFILE(target))
|
|
error = -EPERM;
|
|
else if (is_local_mountpoint(dentry))
|
|
error = -EBUSY;
|
|
else {
|
|
error = security_inode_unlink(dir, dentry);
|
|
if (!error) {
|
|
error = try_break_deleg(target, delegated_inode);
|
|
if (error)
|
|
goto out;
|
|
error = dir->i_op->unlink(dir, dentry);
|
|
if (!error) {
|
|
dont_mount(dentry);
|
|
detach_mounts(dentry);
|
|
fsnotify_unlink(dir, dentry);
|
|
}
|
|
}
|
|
}
|
|
out:
|
|
inode_unlock(target);
|
|
|
|
/* We don't d_delete() NFS sillyrenamed files--they still exist. */
|
|
if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
|
|
fsnotify_link_count(target);
|
|
d_delete(dentry);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_unlink);
|
|
|
|
/*
|
|
* Make sure that the actual truncation of the file will occur outside its
|
|
* directory's i_mutex. Truncate can take a long time if there is a lot of
|
|
* writeout happening, and we don't want to prevent access to the directory
|
|
* while waiting on the I/O.
|
|
*/
|
|
int do_unlinkat(int dfd, struct filename *name)
|
|
{
|
|
int error;
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
struct qstr last;
|
|
int type;
|
|
struct inode *inode = NULL;
|
|
struct inode *delegated_inode = NULL;
|
|
unsigned int lookup_flags = 0;
|
|
retry:
|
|
error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
|
|
if (error)
|
|
goto exit1;
|
|
|
|
error = -EISDIR;
|
|
if (type != LAST_NORM)
|
|
goto exit2;
|
|
|
|
error = mnt_want_write(path.mnt);
|
|
if (error)
|
|
goto exit2;
|
|
retry_deleg:
|
|
inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
|
|
dentry = __lookup_hash(&last, path.dentry, lookup_flags);
|
|
error = PTR_ERR(dentry);
|
|
if (!IS_ERR(dentry)) {
|
|
struct user_namespace *mnt_userns;
|
|
|
|
/* Why not before? Because we want correct error value */
|
|
if (last.name[last.len])
|
|
goto slashes;
|
|
inode = dentry->d_inode;
|
|
if (d_is_negative(dentry))
|
|
goto slashes;
|
|
ihold(inode);
|
|
error = security_path_unlink(&path, dentry);
|
|
if (error)
|
|
goto exit3;
|
|
mnt_userns = mnt_user_ns(path.mnt);
|
|
error = vfs_unlink(mnt_userns, path.dentry->d_inode, dentry,
|
|
&delegated_inode);
|
|
exit3:
|
|
dput(dentry);
|
|
}
|
|
inode_unlock(path.dentry->d_inode);
|
|
if (inode)
|
|
iput(inode); /* truncate the inode here */
|
|
inode = NULL;
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
mnt_drop_write(path.mnt);
|
|
exit2:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
inode = NULL;
|
|
goto retry;
|
|
}
|
|
exit1:
|
|
putname(name);
|
|
return error;
|
|
|
|
slashes:
|
|
if (d_is_negative(dentry))
|
|
error = -ENOENT;
|
|
else if (d_is_dir(dentry))
|
|
error = -EISDIR;
|
|
else
|
|
error = -ENOTDIR;
|
|
goto exit3;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
|
|
{
|
|
if ((flag & ~AT_REMOVEDIR) != 0)
|
|
return -EINVAL;
|
|
|
|
if (flag & AT_REMOVEDIR)
|
|
return do_rmdir(dfd, getname(pathname));
|
|
return do_unlinkat(dfd, getname(pathname));
|
|
}
|
|
|
|
SYSCALL_DEFINE1(unlink, const char __user *, pathname)
|
|
{
|
|
return do_unlinkat(AT_FDCWD, getname(pathname));
|
|
}
|
|
|
|
/**
|
|
* vfs_symlink - create symlink
|
|
* @mnt_userns: user namespace of the mount the inode was found from
|
|
* @dir: inode of @dentry
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @oldname: name of the file to link to
|
|
*
|
|
* Create a symlink.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
int vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
|
|
struct dentry *dentry, const char *oldname)
|
|
{
|
|
int error = may_create(mnt_userns, dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->symlink)
|
|
return -EPERM;
|
|
|
|
error = security_inode_symlink(dir, dentry, oldname);
|
|
if (error)
|
|
return error;
|
|
|
|
error = dir->i_op->symlink(mnt_userns, dir, dentry, oldname);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_symlink);
|
|
|
|
int do_symlinkat(struct filename *from, int newdfd, struct filename *to)
|
|
{
|
|
int error;
|
|
struct dentry *dentry;
|
|
struct path path;
|
|
unsigned int lookup_flags = 0;
|
|
|
|
if (IS_ERR(from)) {
|
|
error = PTR_ERR(from);
|
|
goto out_putnames;
|
|
}
|
|
retry:
|
|
dentry = filename_create(newdfd, to, &path, lookup_flags);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto out_putnames;
|
|
|
|
error = security_path_symlink(&path, dentry, from->name);
|
|
if (!error) {
|
|
struct user_namespace *mnt_userns;
|
|
|
|
mnt_userns = mnt_user_ns(path.mnt);
|
|
error = vfs_symlink(mnt_userns, path.dentry->d_inode, dentry,
|
|
from->name);
|
|
}
|
|
done_path_create(&path, dentry);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out_putnames:
|
|
putname(to);
|
|
putname(from);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname)
|
|
{
|
|
return do_symlinkat(getname(oldname), newdfd, getname(newname));
|
|
}
|
|
|
|
SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return do_symlinkat(getname(oldname), AT_FDCWD, getname(newname));
|
|
}
|
|
|
|
/**
|
|
* vfs_link - create a new link
|
|
* @old_dentry: object to be linked
|
|
* @mnt_userns: the user namespace of the mount
|
|
* @dir: new parent
|
|
* @new_dentry: where to create the new link
|
|
* @delegated_inode: returns inode needing a delegation break
|
|
*
|
|
* The caller must hold dir->i_mutex
|
|
*
|
|
* If vfs_link discovers a delegation on the to-be-linked file in need
|
|
* of breaking, it will return -EWOULDBLOCK and return a reference to the
|
|
* inode in delegated_inode. The caller should then break the delegation
|
|
* and retry. Because breaking a delegation may take a long time, the
|
|
* caller should drop the i_mutex before doing so.
|
|
*
|
|
* Alternatively, a caller may pass NULL for delegated_inode. This may
|
|
* be appropriate for callers that expect the underlying filesystem not
|
|
* to be NFS exported.
|
|
*
|
|
* If the inode has been found through an idmapped mount the user namespace of
|
|
* the vfsmount must be passed through @mnt_userns. This function will then take
|
|
* care to map the inode according to @mnt_userns before checking permissions.
|
|
* On non-idmapped mounts or if permission checking is to be performed on the
|
|
* raw inode simply passs init_user_ns.
|
|
*/
|
|
int vfs_link(struct dentry *old_dentry, struct user_namespace *mnt_userns,
|
|
struct inode *dir, struct dentry *new_dentry,
|
|
struct inode **delegated_inode)
|
|
{
|
|
struct inode *inode = old_dentry->d_inode;
|
|
unsigned max_links = dir->i_sb->s_max_links;
|
|
int error;
|
|
|
|
if (!inode)
|
|
return -ENOENT;
|
|
|
|
error = may_create(mnt_userns, dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
if (dir->i_sb != inode->i_sb)
|
|
return -EXDEV;
|
|
|
|
/*
|
|
* A link to an append-only or immutable file cannot be created.
|
|
*/
|
|
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
|
|
return -EPERM;
|
|
/*
|
|
* Updating the link count will likely cause i_uid and i_gid to
|
|
* be writen back improperly if their true value is unknown to
|
|
* the vfs.
|
|
*/
|
|
if (HAS_UNMAPPED_ID(mnt_userns, inode))
|
|
return -EPERM;
|
|
if (!dir->i_op->link)
|
|
return -EPERM;
|
|
if (S_ISDIR(inode->i_mode))
|
|
return -EPERM;
|
|
|
|
error = security_inode_link(old_dentry, dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
inode_lock(inode);
|
|
/* Make sure we don't allow creating hardlink to an unlinked file */
|
|
if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))
|
|
error = -ENOENT;
|
|
else if (max_links && inode->i_nlink >= max_links)
|
|
error = -EMLINK;
|
|
else {
|
|
error = try_break_deleg(inode, delegated_inode);
|
|
if (!error)
|
|
error = dir->i_op->link(old_dentry, dir, new_dentry);
|
|
}
|
|
|
|
if (!error && (inode->i_state & I_LINKABLE)) {
|
|
spin_lock(&inode->i_lock);
|
|
inode->i_state &= ~I_LINKABLE;
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
inode_unlock(inode);
|
|
if (!error)
|
|
fsnotify_link(dir, inode, new_dentry);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_link);
|
|
|
|
/*
|
|
* Hardlinks are often used in delicate situations. We avoid
|
|
* security-related surprises by not following symlinks on the
|
|
* newname. --KAB
|
|
*
|
|
* We don't follow them on the oldname either to be compatible
|
|
* with linux 2.0, and to avoid hard-linking to directories
|
|
* and other special files. --ADM
|
|
*/
|
|
int do_linkat(int olddfd, struct filename *old, int newdfd,
|
|
struct filename *new, int flags)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
struct dentry *new_dentry;
|
|
struct path old_path, new_path;
|
|
struct inode *delegated_inode = NULL;
|
|
int how = 0;
|
|
int error;
|
|
|
|
if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) {
|
|
error = -EINVAL;
|
|
goto out_putnames;
|
|
}
|
|
/*
|
|
* To use null names we require CAP_DAC_READ_SEARCH
|
|
* This ensures that not everyone will be able to create
|
|
* handlink using the passed filedescriptor.
|
|
*/
|
|
if (flags & AT_EMPTY_PATH && !capable(CAP_DAC_READ_SEARCH)) {
|
|
error = -ENOENT;
|
|
goto out_putnames;
|
|
}
|
|
|
|
if (flags & AT_SYMLINK_FOLLOW)
|
|
how |= LOOKUP_FOLLOW;
|
|
retry:
|
|
error = filename_lookup(olddfd, old, how, &old_path, NULL);
|
|
if (error)
|
|
goto out_putnames;
|
|
|
|
new_dentry = filename_create(newdfd, new, &new_path,
|
|
(how & LOOKUP_REVAL));
|
|
error = PTR_ERR(new_dentry);
|
|
if (IS_ERR(new_dentry))
|
|
goto out_putpath;
|
|
|
|
error = -EXDEV;
|
|
if (old_path.mnt != new_path.mnt)
|
|
goto out_dput;
|
|
mnt_userns = mnt_user_ns(new_path.mnt);
|
|
error = may_linkat(mnt_userns, &old_path);
|
|
if (unlikely(error))
|
|
goto out_dput;
|
|
error = security_path_link(old_path.dentry, &new_path, new_dentry);
|
|
if (error)
|
|
goto out_dput;
|
|
error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode,
|
|
new_dentry, &delegated_inode);
|
|
out_dput:
|
|
done_path_create(&new_path, new_dentry);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error) {
|
|
path_put(&old_path);
|
|
goto retry;
|
|
}
|
|
}
|
|
if (retry_estale(error, how)) {
|
|
path_put(&old_path);
|
|
how |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out_putpath:
|
|
path_put(&old_path);
|
|
out_putnames:
|
|
putname(old);
|
|
putname(new);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname, int, flags)
|
|
{
|
|
return do_linkat(olddfd, getname_uflags(oldname, flags),
|
|
newdfd, getname(newname), flags);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return do_linkat(AT_FDCWD, getname(oldname), AT_FDCWD, getname(newname), 0);
|
|
}
|
|
|
|
/**
|
|
* vfs_rename - rename a filesystem object
|
|
* @rd: pointer to &struct renamedata info
|
|
*
|
|
* The caller must hold multiple mutexes--see lock_rename()).
|
|
*
|
|
* If vfs_rename discovers a delegation in need of breaking at either
|
|
* the source or destination, it will return -EWOULDBLOCK and return a
|
|
* reference to the inode in delegated_inode. The caller should then
|
|
* break the delegation and retry. Because breaking a delegation may
|
|
* take a long time, the caller should drop all locks before doing
|
|
* so.
|
|
*
|
|
* Alternatively, a caller may pass NULL for delegated_inode. This may
|
|
* be appropriate for callers that expect the underlying filesystem not
|
|
* to be NFS exported.
|
|
*
|
|
* The worst of all namespace operations - renaming directory. "Perverted"
|
|
* doesn't even start to describe it. Somebody in UCB had a heck of a trip...
|
|
* Problems:
|
|
*
|
|
* a) we can get into loop creation.
|
|
* b) race potential - two innocent renames can create a loop together.
|
|
* That's where 4.4 screws up. Current fix: serialization on
|
|
* sb->s_vfs_rename_mutex. We might be more accurate, but that's another
|
|
* story.
|
|
* c) we have to lock _four_ objects - parents and victim (if it exists),
|
|
* and source (if it is not a directory).
|
|
* And that - after we got ->i_mutex on parents (until then we don't know
|
|
* whether the target exists). Solution: try to be smart with locking
|
|
* order for inodes. We rely on the fact that tree topology may change
|
|
* only under ->s_vfs_rename_mutex _and_ that parent of the object we
|
|
* move will be locked. Thus we can rank directories by the tree
|
|
* (ancestors first) and rank all non-directories after them.
|
|
* That works since everybody except rename does "lock parent, lookup,
|
|
* lock child" and rename is under ->s_vfs_rename_mutex.
|
|
* HOWEVER, it relies on the assumption that any object with ->lookup()
|
|
* has no more than 1 dentry. If "hybrid" objects will ever appear,
|
|
* we'd better make sure that there's no link(2) for them.
|
|
* d) conversion from fhandle to dentry may come in the wrong moment - when
|
|
* we are removing the target. Solution: we will have to grab ->i_mutex
|
|
* in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
|
|
* ->i_mutex on parents, which works but leads to some truly excessive
|
|
* locking].
|
|
*/
|
|
int vfs_rename(struct renamedata *rd)
|
|
{
|
|
int error;
|
|
struct inode *old_dir = rd->old_dir, *new_dir = rd->new_dir;
|
|
struct dentry *old_dentry = rd->old_dentry;
|
|
struct dentry *new_dentry = rd->new_dentry;
|
|
struct inode **delegated_inode = rd->delegated_inode;
|
|
unsigned int flags = rd->flags;
|
|
bool is_dir = d_is_dir(old_dentry);
|
|
struct inode *source = old_dentry->d_inode;
|
|
struct inode *target = new_dentry->d_inode;
|
|
bool new_is_dir = false;
|
|
unsigned max_links = new_dir->i_sb->s_max_links;
|
|
struct name_snapshot old_name;
|
|
|
|
if (source == target)
|
|
return 0;
|
|
|
|
error = may_delete(rd->old_mnt_userns, old_dir, old_dentry, is_dir);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!target) {
|
|
error = may_create(rd->new_mnt_userns, new_dir, new_dentry);
|
|
} else {
|
|
new_is_dir = d_is_dir(new_dentry);
|
|
|
|
if (!(flags & RENAME_EXCHANGE))
|
|
error = may_delete(rd->new_mnt_userns, new_dir,
|
|
new_dentry, is_dir);
|
|
else
|
|
error = may_delete(rd->new_mnt_userns, new_dir,
|
|
new_dentry, new_is_dir);
|
|
}
|
|
if (error)
|
|
return error;
|
|
|
|
if (!old_dir->i_op->rename)
|
|
return -EPERM;
|
|
|
|
/*
|
|
* If we are going to change the parent - check write permissions,
|
|
* we'll need to flip '..'.
|
|
*/
|
|
if (new_dir != old_dir) {
|
|
if (is_dir) {
|
|
error = inode_permission(rd->old_mnt_userns, source,
|
|
MAY_WRITE);
|
|
if (error)
|
|
return error;
|
|
}
|
|
if ((flags & RENAME_EXCHANGE) && new_is_dir) {
|
|
error = inode_permission(rd->new_mnt_userns, target,
|
|
MAY_WRITE);
|
|
if (error)
|
|
return error;
|
|
}
|
|
}
|
|
|
|
error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry,
|
|
flags);
|
|
if (error)
|
|
return error;
|
|
|
|
take_dentry_name_snapshot(&old_name, old_dentry);
|
|
dget(new_dentry);
|
|
if (!is_dir || (flags & RENAME_EXCHANGE))
|
|
lock_two_nondirectories(source, target);
|
|
else if (target)
|
|
inode_lock(target);
|
|
|
|
error = -EPERM;
|
|
if (IS_SWAPFILE(source) || (target && IS_SWAPFILE(target)))
|
|
goto out;
|
|
|
|
error = -EBUSY;
|
|
if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry))
|
|
goto out;
|
|
|
|
if (max_links && new_dir != old_dir) {
|
|
error = -EMLINK;
|
|
if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links)
|
|
goto out;
|
|
if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir &&
|
|
old_dir->i_nlink >= max_links)
|
|
goto out;
|
|
}
|
|
if (!is_dir) {
|
|
error = try_break_deleg(source, delegated_inode);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
if (target && !new_is_dir) {
|
|
error = try_break_deleg(target, delegated_inode);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
error = old_dir->i_op->rename(rd->new_mnt_userns, old_dir, old_dentry,
|
|
new_dir, new_dentry, flags);
|
|
if (error)
|
|
goto out;
|
|
|
|
if (!(flags & RENAME_EXCHANGE) && target) {
|
|
if (is_dir) {
|
|
shrink_dcache_parent(new_dentry);
|
|
target->i_flags |= S_DEAD;
|
|
}
|
|
dont_mount(new_dentry);
|
|
detach_mounts(new_dentry);
|
|
}
|
|
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) {
|
|
if (!(flags & RENAME_EXCHANGE))
|
|
d_move(old_dentry, new_dentry);
|
|
else
|
|
d_exchange(old_dentry, new_dentry);
|
|
}
|
|
out:
|
|
if (!is_dir || (flags & RENAME_EXCHANGE))
|
|
unlock_two_nondirectories(source, target);
|
|
else if (target)
|
|
inode_unlock(target);
|
|
dput(new_dentry);
|
|
if (!error) {
|
|
fsnotify_move(old_dir, new_dir, &old_name.name, is_dir,
|
|
!(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
|
|
if (flags & RENAME_EXCHANGE) {
|
|
fsnotify_move(new_dir, old_dir, &old_dentry->d_name,
|
|
new_is_dir, NULL, new_dentry);
|
|
}
|
|
}
|
|
release_dentry_name_snapshot(&old_name);
|
|
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(vfs_rename);
|
|
|
|
int do_renameat2(int olddfd, struct filename *from, int newdfd,
|
|
struct filename *to, unsigned int flags)
|
|
{
|
|
struct renamedata rd;
|
|
struct dentry *old_dentry, *new_dentry;
|
|
struct dentry *trap;
|
|
struct path old_path, new_path;
|
|
struct qstr old_last, new_last;
|
|
int old_type, new_type;
|
|
struct inode *delegated_inode = NULL;
|
|
unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET;
|
|
bool should_retry = false;
|
|
int error = -EINVAL;
|
|
|
|
if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
|
|
goto put_names;
|
|
|
|
if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) &&
|
|
(flags & RENAME_EXCHANGE))
|
|
goto put_names;
|
|
|
|
if (flags & RENAME_EXCHANGE)
|
|
target_flags = 0;
|
|
|
|
retry:
|
|
error = filename_parentat(olddfd, from, lookup_flags, &old_path,
|
|
&old_last, &old_type);
|
|
if (error)
|
|
goto put_names;
|
|
|
|
error = filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last,
|
|
&new_type);
|
|
if (error)
|
|
goto exit1;
|
|
|
|
error = -EXDEV;
|
|
if (old_path.mnt != new_path.mnt)
|
|
goto exit2;
|
|
|
|
error = -EBUSY;
|
|
if (old_type != LAST_NORM)
|
|
goto exit2;
|
|
|
|
if (flags & RENAME_NOREPLACE)
|
|
error = -EEXIST;
|
|
if (new_type != LAST_NORM)
|
|
goto exit2;
|
|
|
|
error = mnt_want_write(old_path.mnt);
|
|
if (error)
|
|
goto exit2;
|
|
|
|
retry_deleg:
|
|
trap = lock_rename(new_path.dentry, old_path.dentry);
|
|
|
|
old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags);
|
|
error = PTR_ERR(old_dentry);
|
|
if (IS_ERR(old_dentry))
|
|
goto exit3;
|
|
/* source must exist */
|
|
error = -ENOENT;
|
|
if (d_is_negative(old_dentry))
|
|
goto exit4;
|
|
new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags);
|
|
error = PTR_ERR(new_dentry);
|
|
if (IS_ERR(new_dentry))
|
|
goto exit4;
|
|
error = -EEXIST;
|
|
if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry))
|
|
goto exit5;
|
|
if (flags & RENAME_EXCHANGE) {
|
|
error = -ENOENT;
|
|
if (d_is_negative(new_dentry))
|
|
goto exit5;
|
|
|
|
if (!d_is_dir(new_dentry)) {
|
|
error = -ENOTDIR;
|
|
if (new_last.name[new_last.len])
|
|
goto exit5;
|
|
}
|
|
}
|
|
/* unless the source is a directory trailing slashes give -ENOTDIR */
|
|
if (!d_is_dir(old_dentry)) {
|
|
error = -ENOTDIR;
|
|
if (old_last.name[old_last.len])
|
|
goto exit5;
|
|
if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len])
|
|
goto exit5;
|
|
}
|
|
/* source should not be ancestor of target */
|
|
error = -EINVAL;
|
|
if (old_dentry == trap)
|
|
goto exit5;
|
|
/* target should not be an ancestor of source */
|
|
if (!(flags & RENAME_EXCHANGE))
|
|
error = -ENOTEMPTY;
|
|
if (new_dentry == trap)
|
|
goto exit5;
|
|
|
|
error = security_path_rename(&old_path, old_dentry,
|
|
&new_path, new_dentry, flags);
|
|
if (error)
|
|
goto exit5;
|
|
|
|
rd.old_dir = old_path.dentry->d_inode;
|
|
rd.old_dentry = old_dentry;
|
|
rd.old_mnt_userns = mnt_user_ns(old_path.mnt);
|
|
rd.new_dir = new_path.dentry->d_inode;
|
|
rd.new_dentry = new_dentry;
|
|
rd.new_mnt_userns = mnt_user_ns(new_path.mnt);
|
|
rd.delegated_inode = &delegated_inode;
|
|
rd.flags = flags;
|
|
error = vfs_rename(&rd);
|
|
exit5:
|
|
dput(new_dentry);
|
|
exit4:
|
|
dput(old_dentry);
|
|
exit3:
|
|
unlock_rename(new_path.dentry, old_path.dentry);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
mnt_drop_write(old_path.mnt);
|
|
exit2:
|
|
if (retry_estale(error, lookup_flags))
|
|
should_retry = true;
|
|
path_put(&new_path);
|
|
exit1:
|
|
path_put(&old_path);
|
|
if (should_retry) {
|
|
should_retry = false;
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
put_names:
|
|
putname(from);
|
|
putname(to);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname, unsigned int, flags)
|
|
{
|
|
return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname),
|
|
flags);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname)
|
|
{
|
|
return do_renameat2(olddfd, getname(oldname), newdfd, getname(newname),
|
|
0);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return do_renameat2(AT_FDCWD, getname(oldname), AT_FDCWD,
|
|
getname(newname), 0);
|
|
}
|
|
|
|
int readlink_copy(char __user *buffer, int buflen, const char *link)
|
|
{
|
|
int len = PTR_ERR(link);
|
|
if (IS_ERR(link))
|
|
goto out;
|
|
|
|
len = strlen(link);
|
|
if (len > (unsigned) buflen)
|
|
len = buflen;
|
|
if (copy_to_user(buffer, link, len))
|
|
len = -EFAULT;
|
|
out:
|
|
return len;
|
|
}
|
|
|
|
/**
|
|
* vfs_readlink - copy symlink body into userspace buffer
|
|
* @dentry: dentry on which to get symbolic link
|
|
* @buffer: user memory pointer
|
|
* @buflen: size of buffer
|
|
*
|
|
* Does not touch atime. That's up to the caller if necessary
|
|
*
|
|
* Does not call security hook.
|
|
*/
|
|
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
|
|
{
|
|
struct inode *inode = d_inode(dentry);
|
|
DEFINE_DELAYED_CALL(done);
|
|
const char *link;
|
|
int res;
|
|
|
|
if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) {
|
|
if (unlikely(inode->i_op->readlink))
|
|
return inode->i_op->readlink(dentry, buffer, buflen);
|
|
|
|
if (!d_is_symlink(dentry))
|
|
return -EINVAL;
|
|
|
|
spin_lock(&inode->i_lock);
|
|
inode->i_opflags |= IOP_DEFAULT_READLINK;
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
|
|
link = READ_ONCE(inode->i_link);
|
|
if (!link) {
|
|
link = inode->i_op->get_link(dentry, inode, &done);
|
|
if (IS_ERR(link))
|
|
return PTR_ERR(link);
|
|
}
|
|
res = readlink_copy(buffer, buflen, link);
|
|
do_delayed_call(&done);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(vfs_readlink);
|
|
|
|
/**
|
|
* vfs_get_link - get symlink body
|
|
* @dentry: dentry on which to get symbolic link
|
|
* @done: caller needs to free returned data with this
|
|
*
|
|
* Calls security hook and i_op->get_link() on the supplied inode.
|
|
*
|
|
* It does not touch atime. That's up to the caller if necessary.
|
|
*
|
|
* Does not work on "special" symlinks like /proc/$$/fd/N
|
|
*/
|
|
const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)
|
|
{
|
|
const char *res = ERR_PTR(-EINVAL);
|
|
struct inode *inode = d_inode(dentry);
|
|
|
|
if (d_is_symlink(dentry)) {
|
|
res = ERR_PTR(security_inode_readlink(dentry));
|
|
if (!res)
|
|
res = inode->i_op->get_link(dentry, inode, done);
|
|
}
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(vfs_get_link);
|
|
|
|
/* get the link contents into pagecache */
|
|
const char *page_get_link(struct dentry *dentry, struct inode *inode,
|
|
struct delayed_call *callback)
|
|
{
|
|
char *kaddr;
|
|
struct page *page;
|
|
struct address_space *mapping = inode->i_mapping;
|
|
|
|
if (!dentry) {
|
|
page = find_get_page(mapping, 0);
|
|
if (!page)
|
|
return ERR_PTR(-ECHILD);
|
|
if (!PageUptodate(page)) {
|
|
put_page(page);
|
|
return ERR_PTR(-ECHILD);
|
|
}
|
|
} else {
|
|
page = read_mapping_page(mapping, 0, NULL);
|
|
if (IS_ERR(page))
|
|
return (char*)page;
|
|
}
|
|
set_delayed_call(callback, page_put_link, page);
|
|
BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM);
|
|
kaddr = page_address(page);
|
|
nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1);
|
|
return kaddr;
|
|
}
|
|
|
|
EXPORT_SYMBOL(page_get_link);
|
|
|
|
void page_put_link(void *arg)
|
|
{
|
|
put_page(arg);
|
|
}
|
|
EXPORT_SYMBOL(page_put_link);
|
|
|
|
int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
|
|
{
|
|
DEFINE_DELAYED_CALL(done);
|
|
int res = readlink_copy(buffer, buflen,
|
|
page_get_link(dentry, d_inode(dentry),
|
|
&done));
|
|
do_delayed_call(&done);
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(page_readlink);
|
|
|
|
/*
|
|
* The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
|
|
*/
|
|
int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct page *page;
|
|
void *fsdata;
|
|
int err;
|
|
unsigned int flags = 0;
|
|
if (nofs)
|
|
flags |= AOP_FLAG_NOFS;
|
|
|
|
retry:
|
|
err = pagecache_write_begin(NULL, mapping, 0, len-1,
|
|
flags, &page, &fsdata);
|
|
if (err)
|
|
goto fail;
|
|
|
|
memcpy(page_address(page), symname, len-1);
|
|
|
|
err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
|
|
page, fsdata);
|
|
if (err < 0)
|
|
goto fail;
|
|
if (err < len-1)
|
|
goto retry;
|
|
|
|
mark_inode_dirty(inode);
|
|
return 0;
|
|
fail:
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(__page_symlink);
|
|
|
|
int page_symlink(struct inode *inode, const char *symname, int len)
|
|
{
|
|
return __page_symlink(inode, symname, len,
|
|
!mapping_gfp_constraint(inode->i_mapping, __GFP_FS));
|
|
}
|
|
EXPORT_SYMBOL(page_symlink);
|
|
|
|
const struct inode_operations page_symlink_inode_operations = {
|
|
.get_link = page_get_link,
|
|
};
|
|
EXPORT_SYMBOL(page_symlink_inode_operations);
|