Commit 1e5de283 authored Jul 08, 2007 by Linus Torvalds

Fix permission checking for the new utimensat() system call



Commit 1c710c89 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>

parent 4e99325b

fs/utimes.c

+10 −3

Original line number	Diff line number	Diff line
		@@ -106,9 +106,16 @@ long do_utimes(int dfd, char __user filename, struct timespec times, int flags
		if (IS_IMMUTABLE(inode))
		goto dput_and_out;

		if (current->fsuid != inode->i_uid &&
		(error = vfs_permission(&nd, MAY_WRITE)) != 0)
		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);

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