kernel-ark/fs/utimes.c
Linus Torvalds 1e5de2837c Fix permission checking for the new utimensat() system call
Commit 1c710c896e added the utimensat()
system call, but didn't handle the case of checking for the writability
of the target right, when the target was a file descriptor, not a
filename.

We cannot use vfs_permission(MAY_WRITE) for that case, and need to
simply check whether the file descriptor is writable.  The oops from
using the wrong function was noticed and narrowed down by Markus
Trippelsdorf.

Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-08 12:02:55 -07:00

188 lines
4.9 KiB
C

#include <linux/compiler.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/linkage.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/utime.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#ifdef __ARCH_WANT_SYS_UTIME
/*
* sys_utime() can be implemented in user-level using sys_utimes().
* Is this for backwards compatibility? If so, why not move it
* into the appropriate arch directory (for those architectures that
* need it).
*/
/* If times==NULL, set access and modification to current time,
* must be owner or have write permission.
* Else, update from *times, must be owner or super user.
*/
asmlinkage long sys_utime(char __user *filename, struct utimbuf __user *times)
{
struct timespec tv[2];
if (times) {
if (get_user(tv[0].tv_sec, &times->actime) ||
get_user(tv[1].tv_sec, &times->modtime))
return -EFAULT;
tv[0].tv_nsec = 0;
tv[1].tv_nsec = 0;
}
return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
}
#endif
/* If times==NULL, set access and modification to current time,
* must be owner or have write permission.
* Else, update from *times, must be owner or super user.
*/
long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags)
{
int error;
struct nameidata nd;
struct dentry *dentry;
struct inode *inode;
struct iattr newattrs;
struct file *f = NULL;
error = -EINVAL;
if (flags & ~AT_SYMLINK_NOFOLLOW)
goto out;
if (filename == NULL && dfd != AT_FDCWD) {
error = -EINVAL;
if (flags & AT_SYMLINK_NOFOLLOW)
goto out;
error = -EBADF;
f = fget(dfd);
if (!f)
goto out;
dentry = f->f_path.dentry;
} else {
error = __user_walk_fd(dfd, filename, (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW, &nd);
if (error)
goto out;
dentry = nd.dentry;
}
inode = dentry->d_inode;
error = -EROFS;
if (IS_RDONLY(inode))
goto dput_and_out;
/* Don't worry, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
error = -EPERM;
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
goto dput_and_out;
if (times[0].tv_nsec == UTIME_OMIT)
newattrs.ia_valid &= ~ATTR_ATIME;
else if (times[0].tv_nsec != UTIME_NOW) {
newattrs.ia_atime.tv_sec = times[0].tv_sec;
newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
newattrs.ia_valid |= ATTR_ATIME_SET;
}
if (times[1].tv_nsec == UTIME_OMIT)
newattrs.ia_valid &= ~ATTR_MTIME;
else if (times[1].tv_nsec != UTIME_NOW) {
newattrs.ia_mtime.tv_sec = times[1].tv_sec;
newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
newattrs.ia_valid |= ATTR_MTIME_SET;
}
} else {
error = -EACCES;
if (IS_IMMUTABLE(inode))
goto dput_and_out;
if (current->fsuid != inode->i_uid) {
if (f) {
if (!(f->f_mode & FMODE_WRITE))
goto dput_and_out;
} else {
error = vfs_permission(&nd, MAY_WRITE);
if (error)
goto dput_and_out;
}
}
}
mutex_lock(&inode->i_mutex);
error = notify_change(dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
dput_and_out:
if (f)
fput(f);
else
path_release(&nd);
out:
return error;
}
asmlinkage long sys_utimensat(int dfd, char __user *filename, struct timespec __user *utimes, int flags)
{
struct timespec tstimes[2];
if (utimes) {
if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))
return -EFAULT;
if ((tstimes[0].tv_nsec == UTIME_OMIT ||
tstimes[0].tv_nsec == UTIME_NOW) &&
tstimes[0].tv_sec != 0)
return -EINVAL;
if ((tstimes[1].tv_nsec == UTIME_OMIT ||
tstimes[1].tv_nsec == UTIME_NOW) &&
tstimes[1].tv_sec != 0)
return -EINVAL;
/* Nothing to do, we must not even check the path. */
if (tstimes[0].tv_nsec == UTIME_OMIT &&
tstimes[1].tv_nsec == UTIME_OMIT)
return 0;
}
return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
}
asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
{
struct timeval times[2];
struct timespec tstimes[2];
if (utimes) {
if (copy_from_user(&times, utimes, sizeof(times)))
return -EFAULT;
/* This test is needed to catch all invalid values. If we
would test only in do_utimes we would miss those invalid
values truncated by the multiplication with 1000. Note
that we also catch UTIME_{NOW,OMIT} here which are only
valid for utimensat. */
if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
return -EINVAL;
tstimes[0].tv_sec = times[0].tv_sec;
tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
tstimes[1].tv_sec = times[1].tv_sec;
tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
}
return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
}
asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
{
return sys_futimesat(AT_FDCWD, filename, utimes);
}