Re-arrange code in send_to_group() and in fanotify_should_send_event()
so that the code processing inode_mark does not refer directly to
vfsmount_mark and vice versa.
The new code has indetical behavior to old code with one exception -
the corner case of event with FS_EVENT_ON_CHILD bit handled by fanotify
group when both inode_mark and vfsmount_mark are present and when
inode_mark->mask does not have the FS_EVENT_ON_CHILD bit set.
With old code, fanotify_should_send_event() may return true if other
event bits match the marks mask.
With new code, fanotify_should_send_event() will return false.
Normally, this event should not reach fanotify_should_send_event() at all,
because this condition is being tested earlier in __fsnotify_parent().
But even in case the event does reach fanotify_should_send_event(), the
change of behavior actually prevents the same event from being reported
twice to a group on (i.e. with and w/o FS_EVENT_ON_CHILD bit).
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify.c | 20 ++++++++------------
fs/notify/fsnotify.c | 15 ++++++++-------
2 files changed, 16 insertions(+), 19 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index bbc175d..fc7658f8 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -92,7 +92,7 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
u32 event_mask,
const void *data, int data_type)
{
- __u32 marks_mask, marks_ignored_mask;
+ __u32 marks_mask = 0, marks_ignored_mask = 0;
const struct path *path = data;
pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
@@ -108,10 +108,7 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
!d_can_lookup(path->dentry))
return false;
- if (inode_mark && vfsmnt_mark) {
- marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
- marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
- } else if (inode_mark) {
+ if (inode_mark) {
/*
* if the event is for a child and this inode doesn't care about
* events on the child, don't send it!
@@ -119,13 +116,12 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
if ((event_mask & FS_EVENT_ON_CHILD) &&
!(inode_mark->mask & FS_EVENT_ON_CHILD))
return false;
- marks_mask = inode_mark->mask;
- marks_ignored_mask = inode_mark->ignored_mask;
- } else if (vfsmnt_mark) {
- marks_mask = vfsmnt_mark->mask;
- marks_ignored_mask = vfsmnt_mark->ignored_mask;
- } else {
- BUG();
+ marks_mask |= inode_mark->mask;
+ marks_ignored_mask |= inode_mark->ignored_mask;
+ }
+ if (vfsmnt_mark) {
+ marks_mask |= vfsmnt_mark->mask;
+ marks_ignored_mask |= vfsmnt_mark->ignored_mask;
}
if (d_is_dir(path->dentry) &&
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index b41515d..138e066 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -132,6 +132,7 @@ static int send_to_group(struct inode *to_tell,
struct fsnotify_group *group = NULL;
__u32 inode_test_mask = 0;
__u32 vfsmount_test_mask = 0;
+ __u32 ignored_mask = 0;
if (unlikely(!inode_mark && !vfsmount_mark)) {
BUG();
@@ -153,7 +154,8 @@ static int send_to_group(struct inode *to_tell,
group = inode_mark->group;
inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
inode_test_mask &= inode_mark->mask;
- inode_test_mask &= ~inode_mark->ignored_mask;
+ ignored_mask |= inode_mark->ignored_mask;
+ inode_test_mask &= ~ignored_mask;
}
/* does the vfsmount_mark tell us to do something? */
@@ -161,17 +163,16 @@ static int send_to_group(struct inode *to_tell,
vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
group = vfsmount_mark->group;
vfsmount_test_mask &= vfsmount_mark->mask;
- vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
- if (inode_mark)
- vfsmount_test_mask &= ~inode_mark->ignored_mask;
+ ignored_mask |= vfsmount_mark->ignored_mask;
+ vfsmount_test_mask &= ~ignored_mask;
}
pr_debug("%s: group=%p to_tell=%p mask=%x inode_mark=%p"
" inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
- " data=%p data_is=%d cookie=%d\n",
+ " ignored_mask=%x data=%p data_is=%d cookie=%d\n",
__func__, group, to_tell, mask, inode_mark,
- inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
- data_is, cookie);
+ inode_test_mask, vfsmount_mark, vfsmount_test_mask,
+ ignored_mask, data, data_is, cookie);
if (!inode_test_mask && !vfsmount_test_mask)
return 0;
--
2.7.4
--
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