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authorDavid Howells <dhowells@redhat.com>2017-04-26 22:15:55 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2017-04-26 15:05:47 -0700
commit1e2f82d1e9d12223b4cbd1feb3f2b5596f8049eb (patch)
tree7eeeb6ba287547adc07c8fd6f916bfda60414e54 /fs/stat.c
parentfc08b197bb8c3bebda27b9e9884aaf7557fab53f (diff)
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statx: Kill fd-with-NULL-path support in favour of AT_EMPTY_PATH
With the new statx() syscall, the following both allow the attributes of the file attached to a file descriptor to be retrieved: statx(dfd, NULL, 0, ...); and: statx(dfd, "", AT_EMPTY_PATH, ...); Change the code to reject the first option, though this means copying the path and engaging pathwalk for the fstat() equivalent. dfd can be a non-directory provided path is "". [ The timing of this isn't wonderful, but applying this now before we have statx() in any released kernel, before anybody starts using the NULL special case. - Linus ] Fixes: a528d35e8bfc ("statx: Add a system call to make enhanced file info available") Reported-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: Eric Sandeen <sandeen@sandeen.net> cc: fstests@vger.kernel.org cc: linux-api@vger.kernel.org cc: linux-man@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/stat.c')
-rw-r--r--fs/stat.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/fs/stat.c b/fs/stat.c
index c6c963b2546b..3d85747bd86e 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -547,13 +547,13 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
/**
* sys_statx - System call to get enhanced stats
* @dfd: Base directory to pathwalk from *or* fd to stat.
- * @filename: File to stat *or* NULL.
+ * @filename: File to stat or "" with AT_EMPTY_PATH
* @flags: AT_* flags to control pathwalk.
* @mask: Parts of statx struct actually required.
* @buffer: Result buffer.
*
- * Note that if filename is NULL, then it does the equivalent of fstat() using
- * dfd to indicate the file of interest.
+ * Note that fstat() can be emulated by setting dfd to the fd of interest,
+ * supplying "" as the filename and setting AT_EMPTY_PATH in the flags.
*/
SYSCALL_DEFINE5(statx,
int, dfd, const char __user *, filename, unsigned, flags,
@@ -567,11 +567,10 @@ SYSCALL_DEFINE5(statx,
return -EINVAL;
if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
return -EINVAL;
+ if (!filename)
+ return -EINVAL;
- if (filename)
- error = vfs_statx(dfd, filename, flags, &stat, mask);
- else
- error = vfs_statx_fd(dfd, &stat, mask, flags);
+ error = vfs_statx(dfd, filename, flags, &stat, mask);
if (error)
return error;