mirror of https://gitee.com/openkylin/linux.git
89 lines
2.2 KiB
C
89 lines
2.2 KiB
C
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/* Filesystem access-by-fd.
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*
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* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/fs_context.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/syscalls.h>
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#include <linux/security.h>
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#include <linux/anon_inodes.h>
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#include <linux/namei.h>
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#include <linux/file.h>
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#include <uapi/linux/mount.h>
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#include "mount.h"
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static int fscontext_release(struct inode *inode, struct file *file)
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{
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struct fs_context *fc = file->private_data;
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if (fc) {
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file->private_data = NULL;
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put_fs_context(fc);
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}
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return 0;
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}
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const struct file_operations fscontext_fops = {
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.release = fscontext_release,
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.llseek = no_llseek,
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};
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/*
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* Attach a filesystem context to a file and an fd.
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*/
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static int fscontext_create_fd(struct fs_context *fc, unsigned int o_flags)
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{
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int fd;
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fd = anon_inode_getfd("fscontext", &fscontext_fops, fc,
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O_RDWR | o_flags);
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if (fd < 0)
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put_fs_context(fc);
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return fd;
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}
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/*
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* Open a filesystem by name so that it can be configured for mounting.
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*
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* We are allowed to specify a container in which the filesystem will be
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* opened, thereby indicating which namespaces will be used (notably, which
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* network namespace will be used for network filesystems).
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*/
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SYSCALL_DEFINE2(fsopen, const char __user *, _fs_name, unsigned int, flags)
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{
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struct file_system_type *fs_type;
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struct fs_context *fc;
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const char *fs_name;
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if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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if (flags & ~FSOPEN_CLOEXEC)
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return -EINVAL;
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fs_name = strndup_user(_fs_name, PAGE_SIZE);
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if (IS_ERR(fs_name))
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return PTR_ERR(fs_name);
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fs_type = get_fs_type(fs_name);
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kfree(fs_name);
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if (!fs_type)
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return -ENODEV;
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fc = fs_context_for_mount(fs_type, 0);
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put_filesystem(fs_type);
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if (IS_ERR(fc))
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return PTR_ERR(fc);
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fc->phase = FS_CONTEXT_CREATE_PARAMS;
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return fscontext_create_fd(fc, flags & FSOPEN_CLOEXEC ? O_CLOEXEC : 0);
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}
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