From af85d1772e31fed34165a1b3decef340cf4080c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ondrej=20Mosn=C3=A1=C4=8Dek?= <omosnace@redhat.com>
Date: Tue, 5 Jun 2018 11:00:10 +0200
Subject: [PATCH] audit: Fix extended comparison of GID/EGID
Git-commit: af85d1772e31fed34165a1b3decef340cf4080c0
Patch-mainline: v4.19-rc1
References: bsc#1051510

The audit_filter_rules() function in auditsc.c used the in_[e]group_p()
functions to check GID/EGID match, but these functions use the current
task's credentials, while the comparison should use the credentials of
the task given to audit_filter_rules() as a parameter (tsk).

Note that we can use group_search(cred->group_info, ...) as a
replacement for both in_group_p and in_egroup_p as these functions only
compare the parameter to cred->fsgid/egid and then call group_search.

In fact, the usage of in_group_p was even more incorrect: it compares to
cred->fsgid (which is usually equal to cred->egid) and not cred->gid.

GitHub issue:
https://github.com/linux-audit/audit-kernel/issues/82

Fixes: 37eebe39c973 ("audit: improve GID/EGID comparation logic")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 kernel/auditsc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 5f0bd5ece578..d762e0b8160e 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -494,20 +494,20 @@ static int audit_filter_rules(struct task_struct *tsk,
 			result = audit_gid_comparator(cred->gid, f->op, f->gid);
 			if (f->op == Audit_equal) {
 				if (!result)
-					result = in_group_p(f->gid);
+					result = groups_search(cred->group_info, f->gid);
 			} else if (f->op == Audit_not_equal) {
 				if (result)
-					result = !in_group_p(f->gid);
+					result = !groups_search(cred->group_info, f->gid);
 			}
 			break;
 		case AUDIT_EGID:
 			result = audit_gid_comparator(cred->egid, f->op, f->gid);
 			if (f->op == Audit_equal) {
 				if (!result)
-					result = in_egroup_p(f->gid);
+					result = groups_search(cred->group_info, f->gid);
 			} else if (f->op == Audit_not_equal) {
 				if (result)
-					result = !in_egroup_p(f->gid);
+					result = !groups_search(cred->group_info, f->gid);
 			}
 			break;
 		case AUDIT_SGID:
-- 
2.18.0