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authorDave Hansen <dave.hansen@linux.intel.com>2015-11-05 18:43:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-05 19:34:48 -0800
commit6933599697c96c3213c95f5f1fc7cb6abfd08c54 (patch)
tree56814d66a4500336a614e067e3ffea1a8069a30b /fs/notify
parent8e483ed1342a4ea45b70f0f33ac54eff7a33d918 (diff)
inotify: hide internal kernel bits from fdinfo
There was a report that my patch: inotify: actually check for invalid bits in sys_inotify_add_watch() broke CRIU. The reason is that CRIU looks up raw flags in /proc/$pid/fdinfo/* to figure out how to rebuild inotify watches and then passes those flags directly back in to the inotify API. One of those flags (FS_EVENT_ON_CHILD) is set in mark->mask, but is not part of the inotify API. It is used inside the kernel to _implement_ inotify but it is not and has never been part of the API. My patch above ensured that we only allow bits which are part of the API (IN_ALL_EVENTS). This broke CRIU. FS_EVENT_ON_CHILD is really internal to the kernel. It is set _anyway_ on all inotify marks. So, CRIU was really just trying to set a bit that was already set. This patch hides that bit from fdinfo. CRIU will not see the bit, not try to set it, and should work as before. We should not have been exposing this bit in the first place, so this is a good patch independent of the CRIU problem. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reported-by: Andrey Wagin <avagin@gmail.com> Acked-by: Andrey Vagin <avagin@openvz.org> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Acked-by: Eric Paris <eparis@redhat.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: John McCutchan <john@johnmccutchan.com> Cc: Robert Love <rlove@rlove.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/notify')
-rw-r--r--fs/notify/fdinfo.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c
index 6b6f0d472ae8..fd98e5100cab 100644
--- a/fs/notify/fdinfo.c
+++ b/fs/notify/fdinfo.c
@@ -83,9 +83,16 @@ static void inotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
inode_mark = container_of(mark, struct inotify_inode_mark, fsn_mark);
inode = igrab(mark->inode);
if (inode) {
+ /*
+ * IN_ALL_EVENTS represents all of the mask bits
+ * that we expose to userspace. There is at
+ * least one bit (FS_EVENT_ON_CHILD) which is
+ * used only internally to the kernel.
+ */
+ u32 mask = mark->mask & IN_ALL_EVENTS;
seq_printf(m, "inotify wd:%x ino:%lx sdev:%x mask:%x ignored_mask:%x ",
inode_mark->wd, inode->i_ino, inode->i_sb->s_dev,
- mark->mask, mark->ignored_mask);
+ mask, mark->ignored_mask);
show_mark_fhandle(m, inode);
seq_putc(m, '\n');
iput(inode);