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 <keesc...@chromium.org>
---
 security/Kconfig    | 43 ++++---------------------------------------
 security/security.c | 23 +----------------------
 2 files changed, 5 insertions(+), 61 deletions(-)

diff --git a/security/Kconfig b/security/Kconfig
index e37de9a44747..efa4826c3d99 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 5a3e19f1fe48..fedc26fb8554 100644
--- a/security/security.c
+++ b/security/security.c
@@ -154,7 +154,6 @@ 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;
@@ -186,8 +185,7 @@ 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");
        }
 
@@ -245,18 +243,6 @@ 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,
                                    void (*set)(struct lsm_info *, bool),
                                    bool enabled)
@@ -290,8 +276,6 @@ static void __init prepare_lsm_enable(void)
        parse_lsm_enable(chosen_lsm_disable, set_enabled, false);
 
        /* Process "security=", if given. */
-       if (!chosen_major_lsm)
-               chosen_major_lsm = CONFIG_DEFAULT_SECURITY;
        if (chosen_major_lsm) {
                struct lsm_info *lsm;
 
@@ -334,11 +318,6 @@ 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

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