linux-kernel - [PATCH 1/1] selinux: simplify avc_xperms_audit

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Message-ID: <20240822140858.1998-1-thunder.leizhen@huawei.com>
Date: Thu, 22 Aug 2024 22:08:58 +0800
From: Zhen Lei <thunder.leizhen@...wei.com>
To: Paul Moore <paul@...l-moore.com>, Stephen Smalley
	<stephen.smalley.work@...il.com>, Ondrej Mosnacek <omosnace@...hat.com>,
	<selinux@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH 1/1] selinux: simplify avc_xperms_audit_required()

By associative and commutative laws, the result of the two 'audited' is
zero. Take the second 'audited' as an example:
  1) audited = requested & avd->auditallow;
  2) audited &= ~requested;
  ==> audited = ~requested & (requested & avd->auditallow);
  ==> audited = (~requested & requested) & avd->auditallow;
  ==> audited = 0 & avd->auditallow;
  ==> audited = 0;

In fact, it is more readable to directly write zero. The value of the
first 'audited' is 0 because AUDIT is not allowed. The second 'audited'
is zero because there is no AUDITALLOW permission.

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 security/selinux/avc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index b49c44869dc4627..21f5bbba50caaeb 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -396,7 +396,7 @@ static inline u32 avc_xperms_audit_required(u32 requested,
 		audited = denied & avd->auditdeny;
 		if (audited && xpd) {
 			if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
-				audited &= ~requested;
+				audited = 0;
 		}
 	} else if (result) {
 		audited = denied = requested;
@@ -404,7 +404,7 @@ static inline u32 avc_xperms_audit_required(u32 requested,
 		audited = requested & avd->auditallow;
 		if (audited && xpd) {
 			if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
-				audited &= ~requested;
+				audited = 0;
 		}
 	}
 
-- 
2.34.1