The tracefs and eventfs permissions are created dynamically based on what the mount point inode has or the instances directory inode has. But the way it worked had some inconsistencies that could lead to security issues as the file system is not behaving like admins would expect.
The files and directories could ignore the remount option that changes the gid or uid ownerships, leaving files susceptable to access that is not expected. This happens if a file had its value changed previously and then a remount changed all the files permissions. The one that was changed previously would not be affected. This change set resolves these inconsistencies. This also fixes the test_ownership.tc test as it would pass on the first time it is run, but fail on the second time, because of the inconsistant state of the permissions. Now you can run that test multiple times and it will always pass. Steven Rostedt (Google) (5): tracefs: Reset permissions on remount if permissions are options tracefs: Still use mount point as default permissions for instances eventfs: Do not differentiate the toplevel events directory eventfs: Do not treat events directory different than other directories eventfs: Have "events" directory get permissions from its parent ---- fs/tracefs/event_inode.c | 102 ++++++++++++++++++++++++++++------------------- fs/tracefs/inode.c | 67 +++++++++++++++++++++++++++++-- fs/tracefs/internal.h | 9 +++-- 3 files changed, 130 insertions(+), 48 deletions(-)