LSM: Ignore "security=" when "lsm=" is specified

To avoid potential confusion, explicitly ignore "security=" when "lsm=" is
used on the command line, and report that it is happening.

Suggested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

2 files changed, 10 insertions, 8 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index e59e1471d4db..91c0251fdb86 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2321,7 +2321,7 @@
 
         lsm=lsm1,...,lsmN
                         [SECURITY] Choose order of LSM initialization. This
-                        overrides CONFIG_LSM.
+                        overrides CONFIG_LSM, and the "security=" parameter.
 
         machvec=        [IA-64] Force the use of a particular machine-vector
                         (machvec) in a generic kernel.
@@ -4094,11 +4094,9 @@
                         Note: increases power consumption, thus should only be
                         enabled if running jitter sensitive (HPC/RT) workloads.
 
-        security=       [SECURITY] Choose a security module to enable at boot.
-                        If this boot parameter is not specified, only the first
-                        security module asking for security registration will be
-                        loaded. An invalid security module name will be treated
-                        as if no module has been chosen.
+        security=       [SECURITY] Choose a legacy "major" security module to
+                        enable at boot. This has been deprecated by the
+                        "lsm=" parameter.
 
         selinux=        [SELINUX] Disable or enable SELinux at boot time.
                         Format: { "0" | "1" }
diff --git a/security/security.c b/security/security.c
index b6bff646d373..ed9b8cbf21cf 100644
--- a/security/security.c
+++ b/security/security.c
@@ -288,9 +288,13 @@ static void __init ordered_lsm_init(void)
         ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
                                 GFP_KERNEL);
 
-        if (chosen_lsm_order)
+        if (chosen_lsm_order) {
+                if (chosen_major_lsm) {
+                        pr_info("security= is ignored because it is superseded by lsm=\n");
+                        chosen_major_lsm = NULL;
+                }
                 ordered_lsm_parse(chosen_lsm_order, "cmdline");
-        else
+        } else
                 ordered_lsm_parse(builtin_lsm_order, "builtin");
 
         for (lsm = ordered_lsms; *lsm; lsm++)