[PATCH security-next v4 32/32] LSM: Add all exclusive LSMs to ordered initialization

[Kees Cook]

This removes CONFIG_DEFAULT_SECURITY in favor of the explicit build-time
ordering offered by CONFIG_LSM_ORDER, and adds all the exclusive LSMs to
the ordered LSM initialization. The old meaning of CONFIG_DEFAULT_SECURITY
is now captured by which exclusive LSM is listed first in the LSM order.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
---
 security/Kconfig    | 43 ++++---------------------------------------
 security/security.c | 23 +----------------------
 2 files changed, 5 insertions(+), 61 deletions(-)

diff --git a/security/Kconfig b/security/Kconfig
index c459d2b4c7bd..cc8bb1c344f5 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -239,43 +239,6 @@ source security/yama/Kconfig
 
 source security/integrity/Kconfig
 
-choice
-	prompt "Default security module"
-	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
-	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
-	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
-	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
-	default DEFAULT_SECURITY_DAC
-
-	help
-	  Select the security module that will be used by default if the
-	  kernel parameter security= is not specified.
-
-	config DEFAULT_SECURITY_SELINUX
-		bool "SELinux" if SECURITY_SELINUX=y
-
-	config DEFAULT_SECURITY_SMACK
-		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
-
-	config DEFAULT_SECURITY_TOMOYO
-		bool "TOMOYO" if SECURITY_TOMOYO=y
-
-	config DEFAULT_SECURITY_APPARMOR
-		bool "AppArmor" if SECURITY_APPARMOR=y
-
-	config DEFAULT_SECURITY_DAC
-		bool "Unix Discretionary Access Controls"
-
-endchoice
-
-config DEFAULT_SECURITY
-	string
-	default "selinux" if DEFAULT_SECURITY_SELINUX
-	default "smack" if DEFAULT_SECURITY_SMACK
-	default "tomoyo" if DEFAULT_SECURITY_TOMOYO
-	default "apparmor" if DEFAULT_SECURITY_APPARMOR
-	default "" if DEFAULT_SECURITY_DAC
-
 config LSM_ENABLE
 	string "LSMs to enable at boot time"
 	default "all"
@@ -293,12 +256,14 @@ config LSM_ENABLE
 
 config LSM_ORDER
 	string "Default initialization order of builtin LSMs"
-	default "yama,loadpin,integrity"
+	default "yama,loadpin,integrity,selinux,smack,tomoyo,apparmor"
 	help
 	  A comma-separated list of LSMs, in initialization order.
 	  Any LSMs left off this list will be link-order initialized
 	  after any listed LSMs. Any LSMs listed here but not built in
-	  the kernel will be ignored.
+	  the kernel will be ignored. If the boot parameter
+	  "lsm.order=" is used, it will override this order, with any
+	  unlisted LSMs falling back to the order of this config, etc.
 
 	  If unsure, leave this as the default.
 
diff --git a/security/security.c b/security/security.c
index 7d542e78b7e8..d682342b6450 100644
--- a/security/security.c
+++ b/security/security.c
@@ -146,7 +146,6 @@ static void __init parse_lsm_order(const char *order, const char *origin)
 
 		for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
 			if (lsm->order == LSM_ORDER_MUTABLE &&
-			    (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0 &&
 			    strcmp(lsm->name, name) == 0) {
 				append_ordered_lsm(lsm, origin);
 				found = true;
@@ -178,8 +177,7 @@ static void __init prepare_lsm_order(void)
 
 	/* Add any missing LSMs, in link order. */
 	for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
-		if (lsm->order == LSM_ORDER_MUTABLE &&
-		    (lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0)
+		if (lsm->order == LSM_ORDER_MUTABLE)
 			append_ordered_lsm(lsm, "link-time");
 	}
 
@@ -237,18 +235,6 @@ static void __init ordered_lsm_init(void)
 		maybe_initialize_lsm(*lsm);
 }
 
-static void __init major_lsm_init(void)
-{
-	struct lsm_info *lsm;
-
-	for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
-		if ((lsm->flags & LSM_FLAG_LEGACY_MAJOR) == 0)
-			continue;
-
-		maybe_initialize_lsm(lsm);
-	}
-}
-
 static void __init parse_lsm_enable(const char *str,
 				    bool enabled)
 {
@@ -282,8 +268,6 @@ static void __init prepare_lsm_enable(void)
 	parse_lsm_enable(chosen_lsm_disable, false);
 
 	/* Process "security=", if given. */
-	if (!chosen_major_lsm)
-		chosen_major_lsm = CONFIG_DEFAULT_SECURITY;
 	if (chosen_major_lsm) {
 		struct lsm_info *lsm;
 
@@ -326,11 +310,6 @@ int __init security_init(void)
 	prepare_lsm_order();
 	ordered_lsm_init();
 
-	/*
-	 * Load all the remaining security modules.
-	 */
-	major_lsm_init();
-
 	kfree(ordered_lsms);
 	return 0;
 }
-- 
2.17.1