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Subject[BUG][PATCH][2.6.36-rc3] fanotify: Do not ignore result of permission decisions
Date

Current code ignores access replies to permission decisions so
fix it in a way which will allow all listeners to still receive
non permission events.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@sophos.com>
---
fs/notify/fsnotify.c | 25 +++++++++++++++++--------
include/linux/fsnotify_backend.h | 4 ++++
2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 3680242..37fd072 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -224,7 +224,7 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
struct fsnotify_group *inode_group, *vfsmount_group;
struct fsnotify_event *event = NULL;
struct vfsmount *mnt;
- int idx, ret = 0;
+ int idx, ret = 0, res;
/* global tests shouldn't care about events on child only the specific event */
__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);

@@ -275,18 +275,27 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,

if (inode_group > vfsmount_group) {
/* handle inode */
- send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
- data_is, cookie, file_name, &event);
+ res = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
+ data_is, cookie, file_name, &event);
/* we didn't use the vfsmount_mark */
vfsmount_group = NULL;
} else if (vfsmount_group > inode_group) {
- send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
- data_is, cookie, file_name, &event);
+ res = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
+ data_is, cookie, file_name, &event);
inode_group = NULL;
} else {
- send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
- mask, data, data_is, cookie, file_name,
- &event);
+ res = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
+ mask, data, data_is, cookie, file_name,
+ &event);
+ }
+
+ /* If a listener denied on a permission hook we will remember the reason
+ and run the rest with a non-permission mask only. This allows other
+ listeners to receive non-permission notifications but we do not care
+ about further permission checks. */
+ if (unlikely((res == -EPERM) && (mask & FS_ALL_PERM_EVENTS))) {
+ mask &= ~FS_ALL_PERM_EVENTS;
+ ret = res;
}

if (inode_group)
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index e40190d..c8aea03 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -64,6 +64,10 @@

#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)

+/* All events which require a permission response from userspace */
+#define FS_ALL_PERM_EVENTS (FS_OPEN_PERM |\
+ FS_ACCESS_PERM)
+
#define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
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