This is a note to let you know that I've just added the patch titled tomoyo: Check exceeded quota early in tomoyo_domain_quota_is_ok(). to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tomoyo-check-exceeded-quota-early-in-tomoyo_domain_q.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8c317b75abba79bec54eaaac5b2ec916f43f068c Author: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Date: Tue Dec 14 10:45:26 2021 +0100 tomoyo: Check exceeded quota early in tomoyo_domain_quota_is_ok(). [ Upstream commit 04e57a2d952bbd34bc45744e72be3eecdc344294 ] If tomoyo is used in a testing/fuzzing environment in learning mode, for lots of domains the quota will be exceeded and stay exceeded for prolonged periods of time. In such cases it's pointless (and slow) to walk the whole acl list again and again just to rediscover that the quota is exceeded. We already have the TOMOYO_DIF_QUOTA_WARNED flag that notes the overflow condition. Check it early to avoid the slowdown. [penguin-kernel] This patch causes a user visible change that the learning mode will not be automatically resumed after the quota is increased. To resume the learning mode, administrator will need to explicitly clear TOMOYO_DIF_QUOTA_WARNED flag after increasing the quota. But I think that this change is generally preferable, for administrator likely wants to optimize the acl list for that domain before increasing the quota, or that domain likely hits the quota again. Therefore, don't try to care to clear TOMOYO_DIF_QUOTA_WARNED flag automatically when the quota for that domain changed. Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/security/tomoyo/util.c b/security/tomoyo/util.c index 1da2e3722b126..af8cd2af3466d 100644 --- a/security/tomoyo/util.c +++ b/security/tomoyo/util.c @@ -1051,6 +1051,8 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_request_info *r) return false; if (!domain) return true; + if (READ_ONCE(domain->flags[TOMOYO_DIF_QUOTA_WARNED])) + return false; list_for_each_entry_rcu(ptr, &domain->acl_info_list, list, srcu_read_lock_held(&tomoyo_ss)) { u16 perm; @@ -1096,14 +1098,12 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_request_info *r) if (count < tomoyo_profile(domain->ns, domain->profile)-> pref[TOMOYO_PREF_MAX_LEARNING_ENTRY]) return true; - if (!domain->flags[TOMOYO_DIF_QUOTA_WARNED]) { - domain->flags[TOMOYO_DIF_QUOTA_WARNED] = true; - /* r->granted = false; */ - tomoyo_write_log(r, "%s", tomoyo_dif[TOMOYO_DIF_QUOTA_WARNED]); + WRITE_ONCE(domain->flags[TOMOYO_DIF_QUOTA_WARNED], true); + /* r->granted = false; */ + tomoyo_write_log(r, "%s", tomoyo_dif[TOMOYO_DIF_QUOTA_WARNED]); #ifndef CONFIG_SECURITY_TOMOYO_INSECURE_BUILTIN_SETTING - pr_warn("WARNING: Domain '%s' has too many ACLs to hold. Stopped learning mode.\n", - domain->domainname->name); + pr_warn("WARNING: Domain '%s' has too many ACLs to hold. Stopped learning mode.\n", + domain->domainname->name); #endif - } return false; }