[RESEND,v6,0/5] proc: subset=pid: Relax check of mount visibility

Message

Alexey Gladkov July 16, 2021, 10:45 a.m. UTC

Allow to mount procfs with subset=pid option even if the entire procfs
is not fully accessible to the mounter.

Changelog
---------
v6:
* Add documentation about procfs mount restrictions.
* Reorder commits for better review.

v4:
* Set SB_I_DYNAMIC only if pidonly is set.
* Add an error message if subset=pid is canceled during remount.

v3:
* Add 'const' to struct cred *mounter_cred (fix kernel test robot warning).

v2:
* cache the mounters credentials and make access to the net directories
  contingent of the permissions of the mounter of procfs.

--

Alexey Gladkov (5):
  docs: proc: add documentation about mount restrictions
  proc: subset=pid: Show /proc/self/net only for CAP_NET_ADMIN
  proc: Disable cancellation of subset=pid option
  proc: Relax check of mount visibility
  docs: proc: add documentation about relaxing visibility restrictions

 Documentation/filesystems/proc.rst | 15 +++++++++++++++
 fs/namespace.c                     | 30 ++++++++++++++++++------------
 fs/proc/proc_net.c                 |  8 ++++++++
 fs/proc/root.c                     | 24 +++++++++++++++++++-----
 include/linux/fs.h                 |  1 +
 include/linux/proc_fs.h            |  1 +
 6 files changed, 62 insertions(+), 17 deletions(-)