These changes update the ipc sysctls so that they are fundamentally
per ipc namespace.  Previously these sysctls depended upon a hack to
simulate being per ipc namespace by looking up the ipc namespace in
read or write.  With this set of changes the ipc sysctls are
registered per ipc namespace and open looks up the ipc namespace.

Not only does this series of changes ensure the traditional binding at
open time happens, but it sets a foundation for being able to relax the
permission checks to allow a user namspace root to change the ipc sysctls
for an ipc namespace that the user namespace root requires.  To do this
requires the ipc namespace to be known at open time.

These changes were sent for v5.18[1] but were dropped because some
additional cleanups were requested.  Linus has given his nod[2] to the
cleanups so I hope enough cleanups are present this time.

[1] https://lkml.kernel.org/r/877d8kfmdp.fsf@email.froward.int.ebiederm.org
[2] https://lkml.kernel.org/r/CAHk-=whi2SzU4XT_FsdTCAuK2qtYmH+-hwi1cbSdG8zu0KXL=g@mail.gmail.com

Alexey Gladkov (6):
      ipc: Store mqueue sysctls in the ipc namespace
      ipc: Store ipc sysctls in the ipc namespace
      ipc: Use the same namespace to modify and validate
      ipc: Remove extra1 field abuse to pass ipc namespace
      ipc: Check permissions for checkpoint_restart sysctls at open time
      ipc: Remove extra braces

 include/linux/ipc_namespace.h |  37 +++++++-
 ipc/ipc_sysctl.c              | 205 +++++++++++++++++++++++++-----------------
 ipc/mq_sysctl.c               | 121 +++++++++++++------------
 ipc/mqueue.c                  |  10 +--
 ipc/namespace.c               |  10 +++
 5 files changed, 238 insertions(+), 145 deletions(-)

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

ipc: Remove extra braces

Fix coding style. In the previous commit, I added braces because,
in addition to changing .data, .extra1 also changed. Now this is not
needed.

Fixes: 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace")
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/37687827f630bc150210f5b8abeeb00f1336814e.1651584847.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>