[PATCH security-next v5 20/30] LSM: Prepare for reorganizing "security=" logic

From: Kees Cook <keescook@chromium.org>
To: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>,
	Casey Schaufler <casey@schaufler-ca.com>,
	John Johansen <john.johansen@canonical.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Paul Moore <paul@paul-moore.com>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	LSM <linux-security-module@vger.kernel.org>,
	linux-doc@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH security-next v5 20/30] LSM: Prepare for reorganizing "security=" logic
Date: Wed, 10 Oct 2018 17:18:36 -0700	[thread overview]
Message-ID: <20181011001846.30964-21-keescook@chromium.org> (raw)
In-Reply-To: <20181011001846.30964-1-keescook@chromium.org>

This moves the string handling for "security=" boot parameter into
a stored pointer instead of a string duplicate. This will allow
easier handling of the string when switching logic to use the coming
enable/disable infrastructure.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
---
 security/security.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/security/security.c b/security/security.c
index f3777ed4ca80..1b1ee823457c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -34,9 +34,6 @@
 
 #define MAX_LSM_EVM_XATTR	2
 
-/* Maximum number of letters for an LSM name string */
-#define SECURITY_NAME_MAX	10
-
 /* How many LSMs were built into the kernel? */
 #define LSM_COUNT (__end_lsm_info - __start_lsm_info)
 
@@ -45,9 +42,8 @@ static ATOMIC_NOTIFIER_HEAD(lsm_notifier_chain);
 
 char *lsm_names;
 /* Boot-time LSM user choice */
-static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
-	CONFIG_DEFAULT_SECURITY;
 static __initdata const char *chosen_lsm_order;
+static __initdata const char *chosen_major_lsm;
 
 static __initconst const char * const builtin_lsm_order = CONFIG_LSM;
 
@@ -138,7 +134,7 @@ static bool __init lsm_allowed(struct lsm_info *lsm)
 		return true;
 
 	/* Disabled if this LSM isn't the chosen one. */
-	if (strcmp(lsm->name, chosen_lsm) != 0)
+	if (strcmp(lsm->name, chosen_major_lsm) != 0)
 		return false;
 
 	return true;
@@ -195,6 +191,9 @@ static void __init ordered_lsm_init(void)
 	ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
 				GFP_KERNEL);
 
+	if (!chosen_major_lsm)
+		chosen_major_lsm = CONFIG_DEFAULT_SECURITY;
+
 	if (chosen_lsm_order)
 		ordered_lsm_parse(chosen_lsm_order, "cmdline");
 	else
@@ -257,12 +256,12 @@ int __init security_init(void)
 }
 
 /* Save user chosen LSM */
-static int __init choose_lsm(char *str)
+static int __init choose_major_lsm(char *str)
 {
-	strncpy(chosen_lsm, str, SECURITY_NAME_MAX);
+	chosen_major_lsm = str;
 	return 1;
 }
-__setup("security=", choose_lsm);
+__setup("security=", choose_major_lsm);
 
 /* Explicitly choose LSM initialization order. */
 static int __init choose_lsm_order(char *str)
-- 
2.17.1

