LSM: Remove double path_rename hook calls for RENAME_EXCHANGE
authorMickaël Salaün <mic@digikod.net>
Fri, 6 May 2022 16:10:56 +0000 (18:10 +0200)
committerMickaël Salaün <mic@digikod.net>
Mon, 23 May 2022 11:27:58 +0000 (13:27 +0200)
commit100f59d964050020285f0c8264ce520f0c406c13
tree037d009604dce35f82e15cdc324258d39dbaed9b
parent9da82b20fde95814af721a2a7b1796a5b4a3d78e
LSM: Remove double path_rename hook calls for RENAME_EXCHANGE

In order to be able to identify a file exchange with renameat2(2) and
RENAME_EXCHANGE, which will be useful for Landlock [1], propagate the
rename flags to LSMs.  This may also improve performance because of the
switch from two set of LSM hook calls to only one, and because LSMs
using this hook may optimize the double check (e.g. only one lock,
reduce the number of path walks).

AppArmor, Landlock and Tomoyo are updated to leverage this change.  This
should not change the current behavior (same check order), except
(different level of) speed boosts.

[1] https://lore.kernel.org/r/20220221212522.320243-1-mic@digikod.net

Cc: James Morris <jmorris@namei.org>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Serge E. Hallyn <serge@hallyn.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20220506161102.525323-7-mic@digikod.net
include/linux/lsm_hook_defs.h
include/linux/lsm_hooks.h
security/apparmor/lsm.c
security/landlock/fs.c
security/security.c
security/tomoyo/tomoyo.c