linux-kernel - [PATCH] selinux: optimize major part with a kernel config in selinux_mmap

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Message-Id: <20230710082500.1838896-1-lsahn@wewakecorp.com>
Date:   Mon, 10 Jul 2023 17:25:00 +0900
From:   Leesoo Ahn <lsahn@...eel.net>
To:     lsahn@...akecorp.com
Cc:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>, selinux@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] selinux: optimize major part with a kernel config in selinux_mmap_addr()

The major part, the conditional branch in selinux_mmap_addr() is always to be
false so long as CONFIG_LSM_MMAP_MIN_ADDR is set to zero at compile time.

This usually happens in some linux distros, for instance Ubuntu, which
the config is set to zero in release version. Therefore it could be a bit
optimized with '#if <expr>' at compile time.

Signed-off-by: Leesoo Ahn <lsahn@...akecorp.com>
---
 security/selinux/hooks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d06e350fedee..a049aab6524b 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3723,11 +3723,13 @@ static int selinux_mmap_addr(unsigned long addr)
 {
 	int rc = 0;
 
+#if CONFIG_LSM_MMAP_MIN_ADDR > 0
 	if (addr < CONFIG_LSM_MMAP_MIN_ADDR) {
 		u32 sid = current_sid();
 		rc = avc_has_perm(sid, sid, SECCLASS_MEMPROTECT,
 				  MEMPROTECT__MMAP_ZERO, NULL);
 	}
+#endif
 
 	return rc;
 }
-- 
2.34.1