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authorMiklos Szeredi <mszeredi@redhat.com>2016-09-16 12:44:20 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-10-22 12:26:56 +0200
commitb3b4283f7e46f563b438e587a0a567118a45a3fd (patch)
tree2639531ebe0eba5fdc715778a4cca2a8952259cc /fs
parent1832397d8ce4de6827fb102a70649c63e7a2f9a2 (diff)
vfs: move permission checking into notify_change() for utimes(NULL)
commit f2b20f6ee842313a0d681dbbf7f87b70291a6a3b upstream. This fixes a bug where the permission was not properly checked in overlayfs. The testcase is ltp/utimensat01. It is also cleaner and safer to do the permission checking in the vfs helper instead of the caller. This patch introduces an additional ia_valid flag ATTR_TOUCH (since touch(1) is the most obvious user of utimes(NULL)) that is passed into notify_change whenever the conditions for this special permission checking mode are met. Reported-by: Aihua Zhang <zhangaihua1@huawei.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Tested-by: Aihua Zhang <zhangaihua1@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/attr.c15
-rw-r--r--fs/utimes.c16
2 files changed, 16 insertions, 15 deletions
diff --git a/fs/attr.c b/fs/attr.c
index 6530ced19697..d62f674a605f 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -202,6 +202,21 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de
return -EPERM;
}
+ /*
+ * If utimes(2) and friends are called with times == NULL (or both
+ * times are UTIME_NOW), then we need to check for write permission
+ */
+ if (ia_valid & ATTR_TOUCH) {
+ if (IS_IMMUTABLE(inode))
+ return -EPERM;
+
+ if (!inode_owner_or_capable(inode)) {
+ error = inode_permission(inode, MAY_WRITE);
+ if (error)
+ return error;
+ }
+ }
+
if ((ia_valid & ATTR_MODE)) {
umode_t amode = attr->ia_mode;
/* Flag setting protected by i_mutex */
diff --git a/fs/utimes.c b/fs/utimes.c
index aa138d64560a..cb771c30d102 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -87,20 +87,7 @@ static int utimes_common(struct path *path, struct timespec *times)
*/
newattrs.ia_valid |= ATTR_TIMES_SET;
} else {
- /*
- * If times is NULL (or both times are UTIME_NOW),
- * then we need to check permissions, because
- * inode_change_ok() won't do it.
- */
- error = -EACCES;
- if (IS_IMMUTABLE(inode))
- goto mnt_drop_write_and_out;
-
- if (!inode_owner_or_capable(inode)) {
- error = inode_permission(inode, MAY_WRITE);
- if (error)
- goto mnt_drop_write_and_out;
- }
+ newattrs.ia_valid |= ATTR_TOUCH;
}
retry_deleg:
mutex_lock(&inode->i_mutex);
@@ -112,7 +99,6 @@ retry_deleg:
goto retry_deleg;
}
-mnt_drop_write_and_out:
mnt_drop_write(path->mnt);
out:
return error;