eventfs: Have event files and directories default to parent uid and gid
authorSteven Rostedt (Google) <rostedt@goodmis.org>
Wed, 20 Dec 2023 15:50:17 +0000 (10:50 -0500)
committerSteven Rostedt (Google) <rostedt@goodmis.org>
Thu, 21 Dec 2023 14:58:02 +0000 (09:58 -0500)
commit0dfc852b6fe3cbecbea67332a0dce2bebeba540d
treed698fe39ea2d842f71bf0e969290d77b64481dd7
parent7beb82b7d590e51f698b1cf590b0e2785db1c498
eventfs: Have event files and directories default to parent uid and gid

Dongliang reported:

  I found that in the latest version, the nodes of tracefs have been
  changed to dynamically created.

  This has caused me to encounter a problem where the gid I specified in
  the mounting parameters cannot apply to all files, as in the following
  situation:

  /data/tmp/events # mount | grep tracefs
  tracefs on /data/tmp type tracefs (rw,seclabel,relatime,gid=3012)

  gid 3012 = readtracefs

  /data/tmp # ls -lh
  total 0
  -r--r-----   1 root readtracefs 0 1970-01-01 08:00 README
  -r--r-----   1 root readtracefs 0 1970-01-01 08:00 available_events

  ums9621_1h10:/data/tmp/events # ls -lh
  total 0
  drwxr-xr-x 2 root root 0 2023-12-19 00:56 alarmtimer
  drwxr-xr-x 2 root root 0 2023-12-19 00:56 asoc

  It will prevent certain applications from accessing tracefs properly, I
  try to avoid this issue by making the following modifications.

To fix this, have the files created default to taking the ownership of
the parent dentry unless the ownership was previously set by the user.

Link: https://lore.kernel.org/linux-trace-kernel/1703063706-30539-1-git-send-email-dongliang.cui@unisoc.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231220105017.1489d790@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Hongyu Jin <hongyu.jin@unisoc.com>
Fixes: 28e12c09f5aa0 ("eventfs: Save ownership and mode")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: Dongliang Cui <cuidongliang390@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
fs/tracefs/event_inode.c