From: Miklos Szeredi <mszeredi@xxxxxxx>
Add a new ia_valid flag: ATTR_TIMES_SET, to handle the
UTIMES_OMIT/UTIMES_NOW and UTIMES_NOW/UTIMES_OMIT cases. In these
cases neither ATTR_MTIME_SET nor ATTR_ATIME_SET is in the flags, yet
the POSIX draft specifies that permission checking is performed the
same way as if one or both of the times was explicitly set to a
timestamp.
See the path "vfs: utimensat(): fix error checking for
{UTIME_NOW,UTIME_OMIT} case" by Michael Kerrisk for the patch
introducing this behavior.
This is a cleanup, as well as allowing filesystems (NFS/fuse/...) to
perform their own permission checking instead of the default.
CC: Ulrich Drepper <drepper@xxxxxxxxxx>
CC: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
fs/attr.c | 2 +-
fs/utimes.c | 17 ++++-------------
include/linux/fs.h | 33 +++++++++++++++++----------------
3 files changed, 22 insertions(+), 30 deletions(-)
Index: linux-2.6/fs/attr.c
===================================================================
--- linux-2.6.orig/fs/attr.c 2008-06-27 22:09:08.000000000 +0200
+++ linux-2.6/fs/attr.c 2008-07-01 13:52:20.000000000 +0200
@@ -51,7 +51,7 @@ int inode_change_ok(struct inode *inode,
}
/* Check for setting the inode time. */
- if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
+ if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
if (!is_owner_or_cap(inode))
goto error;
}
Index: linux-2.6/fs/utimes.c
===================================================================
--- linux-2.6.orig/fs/utimes.c 2008-07-01 08:10:12.000000000 +0200
+++ linux-2.6/fs/utimes.c 2008-07-01 13:52:20.000000000 +0200
@@ -101,7 +101,6 @@ long do_utimes(int dfd, char __user *fil
times[1].tv_nsec == UTIME_NOW)
times = NULL;
- /* In most cases, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
error = -EPERM;
@@ -123,21 +122,13 @@ long do_utimes(int dfd, char __user *fil
newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
newattrs.ia_valid |= ATTR_MTIME_SET;
}
-
/*
- * For the UTIME_OMIT/UTIME_NOW and UTIME_NOW/UTIME_OMIT
- * cases, we need to make an extra check that is not done by
- * inode_change_ok().
+ * Tell inode_change_ok(), that this is an explicit time
+ * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
+ * were used.
*/
- if (((times[0].tv_nsec == UTIME_NOW &&
- times[1].tv_nsec == UTIME_OMIT)
- ||
- (times[0].tv_nsec == UTIME_OMIT &&
- times[1].tv_nsec == UTIME_NOW))
- && !is_owner_or_cap(inode))
- goto mnt_drop_write_and_out;
+ newattrs.ia_valid |= ATTR_TIMES_SET;
} else {
-
/*
* If times is NULL (or both times are UTIME_NOW),
* then we need to check permissions, because
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h 2008-07-01 13:52:19.000000000 +0200
+++ linux-2.6/include/linux/fs.h 2008-07-01 13:52:20.000000000 +0200
@@ -317,22 +317,23 @@ typedef void (dio_iodone_t)(struct kiocb
* Attribute flags. These should be or-ed together to figure out what
* has been changed!
*/
-#define ATTR_MODE 1
-#define ATTR_UID 2
-#define ATTR_GID 4
-#define ATTR_SIZE 8
-#define ATTR_ATIME 16
-#define ATTR_MTIME 32
-#define ATTR_CTIME 64
-#define ATTR_ATIME_SET 128
-#define ATTR_MTIME_SET 256
-#define ATTR_FORCE 512 /* Not a change, but a change it */
-#define ATTR_ATTR_FLAG 1024
-#define ATTR_KILL_SUID 2048
-#define ATTR_KILL_SGID 4096
-#define ATTR_FILE 8192
-#define ATTR_KILL_PRIV 16384
-#define ATTR_OPEN 32768 /* Truncating from open(O_TRUNC) */
+#define ATTR_MODE (1 << 0)
+#define ATTR_UID (1 << 1)
+#define ATTR_GID (1 << 2)
+#define ATTR_SIZE (1 << 3)
+#define ATTR_ATIME (1 << 4)
+#define ATTR_MTIME (1 << 5)
+#define ATTR_CTIME (1 << 6)
+#define ATTR_ATIME_SET (1 << 7)
+#define ATTR_MTIME_SET (1 << 8)
+#define ATTR_FORCE (1 << 9) /* Not a change, but a change it */
+#define ATTR_ATTR_FLAG (1 << 10)
+#define ATTR_KILL_SUID (1 << 11)
+#define ATTR_KILL_SGID (1 << 12)
+#define ATTR_FILE (1 << 13)
+#define ATTR_KILL_PRIV (1 << 14)
+#define ATTR_OPEN (1 << 15) /* Truncating from open(O_TRUNC) */
+#define ATTR_TIMES_SET (1 << 16)
/*
* This is the Inode Attributes structure, used for notify_change(). It
--
--
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