558 lines
14 KiB
C
558 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* linux/fs/readdir.c
|
|
*
|
|
* Copyright (C) 1995 Linus Torvalds
|
|
*/
|
|
|
|
#include <linux/stddef.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/export.h>
|
|
#include <linux/time.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/stat.h>
|
|
#include <linux/file.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/fsnotify.h>
|
|
#include <linux/dirent.h>
|
|
#include <linux/security.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/unistd.h>
|
|
#include <linux/compat.h>
|
|
#include <linux/uaccess.h>
|
|
|
|
#include <asm/unaligned.h>
|
|
|
|
/*
|
|
* Note the "unsafe_put_user() semantics: we goto a
|
|
* label for errors.
|
|
*/
|
|
#define unsafe_copy_dirent_name(_dst, _src, _len, label) do { \
|
|
char __user *dst = (_dst); \
|
|
const char *src = (_src); \
|
|
size_t len = (_len); \
|
|
unsafe_put_user(0, dst+len, label); \
|
|
unsafe_copy_to_user(dst, src, len, label); \
|
|
} while (0)
|
|
|
|
|
|
int iterate_dir(struct file *file, struct dir_context *ctx)
|
|
{
|
|
struct inode *inode = file_inode(file);
|
|
bool shared = false;
|
|
int res = -ENOTDIR;
|
|
if (file->f_op->iterate_shared)
|
|
shared = true;
|
|
else if (!file->f_op->iterate)
|
|
goto out;
|
|
|
|
res = security_file_permission(file, MAY_READ);
|
|
if (res)
|
|
goto out;
|
|
|
|
if (shared)
|
|
res = down_read_killable(&inode->i_rwsem);
|
|
else
|
|
res = down_write_killable(&inode->i_rwsem);
|
|
if (res)
|
|
goto out;
|
|
|
|
res = -ENOENT;
|
|
if (!IS_DEADDIR(inode)) {
|
|
ctx->pos = file->f_pos;
|
|
if (shared)
|
|
res = file->f_op->iterate_shared(file, ctx);
|
|
else
|
|
res = file->f_op->iterate(file, ctx);
|
|
file->f_pos = ctx->pos;
|
|
fsnotify_access(file);
|
|
file_accessed(file);
|
|
}
|
|
if (shared)
|
|
inode_unlock_shared(inode);
|
|
else
|
|
inode_unlock(inode);
|
|
out:
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(iterate_dir);
|
|
|
|
/*
|
|
* POSIX says that a dirent name cannot contain NULL or a '/'.
|
|
*
|
|
* It's not 100% clear what we should really do in this case.
|
|
* The filesystem is clearly corrupted, but returning a hard
|
|
* error means that you now don't see any of the other names
|
|
* either, so that isn't a perfect alternative.
|
|
*
|
|
* And if you return an error, what error do you use? Several
|
|
* filesystems seem to have decided on EUCLEAN being the error
|
|
* code for EFSCORRUPTED, and that may be the error to use. Or
|
|
* just EIO, which is perhaps more obvious to users.
|
|
*
|
|
* In order to see the other file names in the directory, the
|
|
* caller might want to make this a "soft" error: skip the
|
|
* entry, and return the error at the end instead.
|
|
*
|
|
* Note that this should likely do a "memchr(name, 0, len)"
|
|
* check too, since that would be filesystem corruption as
|
|
* well. However, that case can't actually confuse user space,
|
|
* which has to do a strlen() on the name anyway to find the
|
|
* filename length, and the above "soft error" worry means
|
|
* that it's probably better left alone until we have that
|
|
* issue clarified.
|
|
*
|
|
* Note the PATH_MAX check - it's arbitrary but the real
|
|
* kernel limit on a possible path component, not NAME_MAX,
|
|
* which is the technical standard limit.
|
|
*/
|
|
static int verify_dirent_name(const char *name, int len)
|
|
{
|
|
if (len <= 0 || len >= PATH_MAX)
|
|
return -EIO;
|
|
if (memchr(name, '/', len))
|
|
return -EIO;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Traditional linux readdir() handling..
|
|
*
|
|
* "count=1" is a special case, meaning that the buffer is one
|
|
* dirent-structure in size and that the code can't handle more
|
|
* anyway. Thus the special "fillonedir()" function for that
|
|
* case (the low-level handlers don't need to care about this).
|
|
*/
|
|
|
|
#ifdef __ARCH_WANT_OLD_READDIR
|
|
|
|
struct old_linux_dirent {
|
|
unsigned long d_ino;
|
|
unsigned long d_offset;
|
|
unsigned short d_namlen;
|
|
char d_name[1];
|
|
};
|
|
|
|
struct readdir_callback {
|
|
struct dir_context ctx;
|
|
struct old_linux_dirent __user * dirent;
|
|
int result;
|
|
};
|
|
|
|
static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
|
|
loff_t offset, u64 ino, unsigned int d_type)
|
|
{
|
|
struct readdir_callback *buf =
|
|
container_of(ctx, struct readdir_callback, ctx);
|
|
struct old_linux_dirent __user * dirent;
|
|
unsigned long d_ino;
|
|
|
|
if (buf->result)
|
|
return -EINVAL;
|
|
d_ino = ino;
|
|
if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
|
|
buf->result = -EOVERFLOW;
|
|
return -EOVERFLOW;
|
|
}
|
|
buf->result++;
|
|
dirent = buf->dirent;
|
|
if (!access_ok(dirent,
|
|
(unsigned long)(dirent->d_name + namlen + 1) -
|
|
(unsigned long)dirent))
|
|
goto efault;
|
|
if ( __put_user(d_ino, &dirent->d_ino) ||
|
|
__put_user(offset, &dirent->d_offset) ||
|
|
__put_user(namlen, &dirent->d_namlen) ||
|
|
__copy_to_user(dirent->d_name, name, namlen) ||
|
|
__put_user(0, dirent->d_name + namlen))
|
|
goto efault;
|
|
return 0;
|
|
efault:
|
|
buf->result = -EFAULT;
|
|
return -EFAULT;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
|
|
struct old_linux_dirent __user *, dirent, unsigned int, count)
|
|
{
|
|
int error;
|
|
struct fd f = fdget_pos(fd);
|
|
struct readdir_callback buf = {
|
|
.ctx.actor = fillonedir,
|
|
.dirent = dirent
|
|
};
|
|
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
error = iterate_dir(f.file, &buf.ctx);
|
|
if (buf.result)
|
|
error = buf.result;
|
|
|
|
fdput_pos(f);
|
|
return error;
|
|
}
|
|
|
|
#endif /* __ARCH_WANT_OLD_READDIR */
|
|
|
|
/*
|
|
* New, all-improved, singing, dancing, iBCS2-compliant getdents()
|
|
* interface.
|
|
*/
|
|
struct linux_dirent {
|
|
unsigned long d_ino;
|
|
unsigned long d_off;
|
|
unsigned short d_reclen;
|
|
char d_name[1];
|
|
};
|
|
|
|
struct getdents_callback {
|
|
struct dir_context ctx;
|
|
struct linux_dirent __user * current_dir;
|
|
int prev_reclen;
|
|
int count;
|
|
int error;
|
|
};
|
|
|
|
static int filldir(struct dir_context *ctx, const char *name, int namlen,
|
|
loff_t offset, u64 ino, unsigned int d_type)
|
|
{
|
|
struct linux_dirent __user *dirent, *prev;
|
|
struct getdents_callback *buf =
|
|
container_of(ctx, struct getdents_callback, ctx);
|
|
unsigned long d_ino;
|
|
int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
|
|
sizeof(long));
|
|
int prev_reclen;
|
|
|
|
buf->error = verify_dirent_name(name, namlen);
|
|
if (unlikely(buf->error))
|
|
return buf->error;
|
|
buf->error = -EINVAL; /* only used if we fail.. */
|
|
if (reclen > buf->count)
|
|
return -EINVAL;
|
|
d_ino = ino;
|
|
if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
|
|
buf->error = -EOVERFLOW;
|
|
return -EOVERFLOW;
|
|
}
|
|
prev_reclen = buf->prev_reclen;
|
|
if (prev_reclen && signal_pending(current))
|
|
return -EINTR;
|
|
dirent = buf->current_dir;
|
|
prev = (void __user *) dirent - prev_reclen;
|
|
if (!user_access_begin(prev, reclen + prev_reclen))
|
|
goto efault;
|
|
|
|
/* This might be 'dirent->d_off', but if so it will get overwritten */
|
|
unsafe_put_user(offset, &prev->d_off, efault_end);
|
|
unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
|
|
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
|
|
unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end);
|
|
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
|
|
user_access_end();
|
|
|
|
buf->current_dir = (void __user *)dirent + reclen;
|
|
buf->prev_reclen = reclen;
|
|
buf->count -= reclen;
|
|
return 0;
|
|
efault_end:
|
|
user_access_end();
|
|
efault:
|
|
buf->error = -EFAULT;
|
|
return -EFAULT;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(getdents, unsigned int, fd,
|
|
struct linux_dirent __user *, dirent, unsigned int, count)
|
|
{
|
|
struct fd f;
|
|
struct getdents_callback buf = {
|
|
.ctx.actor = filldir,
|
|
.count = count,
|
|
.current_dir = dirent
|
|
};
|
|
int error;
|
|
|
|
if (!access_ok(dirent, count))
|
|
return -EFAULT;
|
|
|
|
f = fdget_pos(fd);
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
error = iterate_dir(f.file, &buf.ctx);
|
|
if (error >= 0)
|
|
error = buf.error;
|
|
if (buf.prev_reclen) {
|
|
struct linux_dirent __user * lastdirent;
|
|
lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
|
|
|
|
if (put_user(buf.ctx.pos, &lastdirent->d_off))
|
|
error = -EFAULT;
|
|
else
|
|
error = count - buf.count;
|
|
}
|
|
fdput_pos(f);
|
|
return error;
|
|
}
|
|
|
|
struct getdents_callback64 {
|
|
struct dir_context ctx;
|
|
struct linux_dirent64 __user * current_dir;
|
|
int prev_reclen;
|
|
int count;
|
|
int error;
|
|
};
|
|
|
|
static int filldir64(struct dir_context *ctx, const char *name, int namlen,
|
|
loff_t offset, u64 ino, unsigned int d_type)
|
|
{
|
|
struct linux_dirent64 __user *dirent, *prev;
|
|
struct getdents_callback64 *buf =
|
|
container_of(ctx, struct getdents_callback64, ctx);
|
|
int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
|
|
sizeof(u64));
|
|
int prev_reclen;
|
|
|
|
buf->error = verify_dirent_name(name, namlen);
|
|
if (unlikely(buf->error))
|
|
return buf->error;
|
|
buf->error = -EINVAL; /* only used if we fail.. */
|
|
if (reclen > buf->count)
|
|
return -EINVAL;
|
|
prev_reclen = buf->prev_reclen;
|
|
if (prev_reclen && signal_pending(current))
|
|
return -EINTR;
|
|
dirent = buf->current_dir;
|
|
prev = (void __user *)dirent - prev_reclen;
|
|
if (!user_access_begin(prev, reclen + prev_reclen))
|
|
goto efault;
|
|
|
|
/* This might be 'dirent->d_off', but if so it will get overwritten */
|
|
unsafe_put_user(offset, &prev->d_off, efault_end);
|
|
unsafe_put_user(ino, &dirent->d_ino, efault_end);
|
|
unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
|
|
unsafe_put_user(d_type, &dirent->d_type, efault_end);
|
|
unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
|
|
user_access_end();
|
|
|
|
buf->prev_reclen = reclen;
|
|
buf->current_dir = (void __user *)dirent + reclen;
|
|
buf->count -= reclen;
|
|
return 0;
|
|
|
|
efault_end:
|
|
user_access_end();
|
|
efault:
|
|
buf->error = -EFAULT;
|
|
return -EFAULT;
|
|
}
|
|
|
|
int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
|
|
unsigned int count)
|
|
{
|
|
struct fd f;
|
|
struct getdents_callback64 buf = {
|
|
.ctx.actor = filldir64,
|
|
.count = count,
|
|
.current_dir = dirent
|
|
};
|
|
int error;
|
|
|
|
if (!access_ok(dirent, count))
|
|
return -EFAULT;
|
|
|
|
f = fdget_pos(fd);
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
error = iterate_dir(f.file, &buf.ctx);
|
|
if (error >= 0)
|
|
error = buf.error;
|
|
if (buf.prev_reclen) {
|
|
struct linux_dirent64 __user * lastdirent;
|
|
typeof(lastdirent->d_off) d_off = buf.ctx.pos;
|
|
|
|
lastdirent = (void __user *) buf.current_dir - buf.prev_reclen;
|
|
if (__put_user(d_off, &lastdirent->d_off))
|
|
error = -EFAULT;
|
|
else
|
|
error = count - buf.count;
|
|
}
|
|
fdput_pos(f);
|
|
return error;
|
|
}
|
|
|
|
|
|
SYSCALL_DEFINE3(getdents64, unsigned int, fd,
|
|
struct linux_dirent64 __user *, dirent, unsigned int, count)
|
|
{
|
|
return ksys_getdents64(fd, dirent, count);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
struct compat_old_linux_dirent {
|
|
compat_ulong_t d_ino;
|
|
compat_ulong_t d_offset;
|
|
unsigned short d_namlen;
|
|
char d_name[1];
|
|
};
|
|
|
|
struct compat_readdir_callback {
|
|
struct dir_context ctx;
|
|
struct compat_old_linux_dirent __user *dirent;
|
|
int result;
|
|
};
|
|
|
|
static int compat_fillonedir(struct dir_context *ctx, const char *name,
|
|
int namlen, loff_t offset, u64 ino,
|
|
unsigned int d_type)
|
|
{
|
|
struct compat_readdir_callback *buf =
|
|
container_of(ctx, struct compat_readdir_callback, ctx);
|
|
struct compat_old_linux_dirent __user *dirent;
|
|
compat_ulong_t d_ino;
|
|
|
|
if (buf->result)
|
|
return -EINVAL;
|
|
d_ino = ino;
|
|
if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
|
|
buf->result = -EOVERFLOW;
|
|
return -EOVERFLOW;
|
|
}
|
|
buf->result++;
|
|
dirent = buf->dirent;
|
|
if (!access_ok(dirent,
|
|
(unsigned long)(dirent->d_name + namlen + 1) -
|
|
(unsigned long)dirent))
|
|
goto efault;
|
|
if ( __put_user(d_ino, &dirent->d_ino) ||
|
|
__put_user(offset, &dirent->d_offset) ||
|
|
__put_user(namlen, &dirent->d_namlen) ||
|
|
__copy_to_user(dirent->d_name, name, namlen) ||
|
|
__put_user(0, dirent->d_name + namlen))
|
|
goto efault;
|
|
return 0;
|
|
efault:
|
|
buf->result = -EFAULT;
|
|
return -EFAULT;
|
|
}
|
|
|
|
COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
|
|
struct compat_old_linux_dirent __user *, dirent, unsigned int, count)
|
|
{
|
|
int error;
|
|
struct fd f = fdget_pos(fd);
|
|
struct compat_readdir_callback buf = {
|
|
.ctx.actor = compat_fillonedir,
|
|
.dirent = dirent
|
|
};
|
|
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
error = iterate_dir(f.file, &buf.ctx);
|
|
if (buf.result)
|
|
error = buf.result;
|
|
|
|
fdput_pos(f);
|
|
return error;
|
|
}
|
|
|
|
struct compat_linux_dirent {
|
|
compat_ulong_t d_ino;
|
|
compat_ulong_t d_off;
|
|
unsigned short d_reclen;
|
|
char d_name[1];
|
|
};
|
|
|
|
struct compat_getdents_callback {
|
|
struct dir_context ctx;
|
|
struct compat_linux_dirent __user *current_dir;
|
|
struct compat_linux_dirent __user *previous;
|
|
int count;
|
|
int error;
|
|
};
|
|
|
|
static int compat_filldir(struct dir_context *ctx, const char *name, int namlen,
|
|
loff_t offset, u64 ino, unsigned int d_type)
|
|
{
|
|
struct compat_linux_dirent __user * dirent;
|
|
struct compat_getdents_callback *buf =
|
|
container_of(ctx, struct compat_getdents_callback, ctx);
|
|
compat_ulong_t d_ino;
|
|
int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) +
|
|
namlen + 2, sizeof(compat_long_t));
|
|
|
|
buf->error = -EINVAL; /* only used if we fail.. */
|
|
if (reclen > buf->count)
|
|
return -EINVAL;
|
|
d_ino = ino;
|
|
if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
|
|
buf->error = -EOVERFLOW;
|
|
return -EOVERFLOW;
|
|
}
|
|
dirent = buf->previous;
|
|
if (dirent) {
|
|
if (signal_pending(current))
|
|
return -EINTR;
|
|
if (__put_user(offset, &dirent->d_off))
|
|
goto efault;
|
|
}
|
|
dirent = buf->current_dir;
|
|
if (__put_user(d_ino, &dirent->d_ino))
|
|
goto efault;
|
|
if (__put_user(reclen, &dirent->d_reclen))
|
|
goto efault;
|
|
if (copy_to_user(dirent->d_name, name, namlen))
|
|
goto efault;
|
|
if (__put_user(0, dirent->d_name + namlen))
|
|
goto efault;
|
|
if (__put_user(d_type, (char __user *) dirent + reclen - 1))
|
|
goto efault;
|
|
buf->previous = dirent;
|
|
dirent = (void __user *)dirent + reclen;
|
|
buf->current_dir = dirent;
|
|
buf->count -= reclen;
|
|
return 0;
|
|
efault:
|
|
buf->error = -EFAULT;
|
|
return -EFAULT;
|
|
}
|
|
|
|
COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,
|
|
struct compat_linux_dirent __user *, dirent, unsigned int, count)
|
|
{
|
|
struct fd f;
|
|
struct compat_linux_dirent __user * lastdirent;
|
|
struct compat_getdents_callback buf = {
|
|
.ctx.actor = compat_filldir,
|
|
.current_dir = dirent,
|
|
.count = count
|
|
};
|
|
int error;
|
|
|
|
if (!access_ok(dirent, count))
|
|
return -EFAULT;
|
|
|
|
f = fdget_pos(fd);
|
|
if (!f.file)
|
|
return -EBADF;
|
|
|
|
error = iterate_dir(f.file, &buf.ctx);
|
|
if (error >= 0)
|
|
error = buf.error;
|
|
lastdirent = buf.previous;
|
|
if (lastdirent) {
|
|
if (put_user(buf.ctx.pos, &lastdirent->d_off))
|
|
error = -EFAULT;
|
|
else
|
|
error = count - buf.count;
|
|
}
|
|
fdput_pos(f);
|
|
return error;
|
|
}
|
|
#endif
|