LoadPin: Rename boot param "enabled" to "enforce"

LoadPin's "enabled" setting is really about enforcement, not whether
or not the LSM is using LSM hooks. Instead, split this out so that LSM
enabling can be logically distinct from whether enforcement is happening
(for example, the pinning happens when the LSM is enabled, but the pin
is only checked when "enforce" is set). This allows LoadPin to continue
to operate sanely in test environments once LSM enable/disable is
centrally handled (i.e. we want LoadPin to be enabled separately from
its enforcement).

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>

diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig
index dd01aa91e521d05cd77afdf15d842293c8bcfb4a..a0d70d82b98ea4d4fa2e8be8af72589f93d78e0f 100644 (file)
--- a/security/loadpin/Kconfig
+++ b/security/loadpin/Kconfig
@@ -10,10 +10,10 @@ config SECURITY_LOADPIN
          have a root filesystem backed by a read-only device such as
          dm-verity or a CDROM.
 
-config SECURITY_LOADPIN_ENABLED
+config SECURITY_LOADPIN_ENFORCE
        bool "Enforce LoadPin at boot"
        depends on SECURITY_LOADPIN
        help
          If selected, LoadPin will enforce pinning at boot. If not
          selected, it can be enabled at boot with the kernel parameter
-         "loadpin.enabled=1".
+         "loadpin.enforce=1".

diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index f062672d6b35f8b3c9dfd0e7295e2ce0e25921d0..48f39631b370a45677f166f8f746b8918c5dfe83 100644 (file)
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c
@@ -44,7 +44,7 @@ static void report_load(const char *origin, struct file *file, char *operation)
        kfree(pathname);
 }
 
-static int enabled = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENABLED);
+static int enforce = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENFORCE);
 static struct super_block *pinned_root;
 static DEFINE_SPINLOCK(pinned_root_spinlock);
 
@@ -60,8 +60,8 @@ static struct ctl_path loadpin_sysctl_path[] = {
 
 static struct ctl_table loadpin_sysctl_table[] = {
        {
-               .procname       = "enabled",
-               .data           = &enabled,
+               .procname       = "enforce",
+               .data           = &enforce,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
@@ -100,7 +100,7 @@ static void check_pinning_enforcement(struct super_block *mnt_sb)
                                           loadpin_sysctl_table))
                        pr_notice("sysctl registration failed!\n");
                else
-                       pr_info("load pinning can be disabled.\n");
+                       pr_info("enforcement can be disabled.\n");
        } else
                pr_info("load pinning engaged.\n");
 }
@@ -131,7 +131,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
 
        /* This handles the older init_module API that has a NULL file. */
        if (!file) {
-               if (!enabled) {
+               if (!enforce) {
                        report_load(origin, NULL, "old-api-pinning-ignored");
                        return 0;
                }
@@ -154,7 +154,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
                 * Unlock now since it's only pinned_root we care about.
                 * In the worst case, we will (correctly) report pinning
                 * failures before we have announced that pinning is
-                * enabled. This would be purely cosmetic.
+                * enforcing. This would be purely cosmetic.
                 */
                spin_unlock(&pinned_root_spinlock);
                check_pinning_enforcement(pinned_root);
@@ -164,7 +164,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
        }
 
        if (IS_ERR_OR_NULL(pinned_root) || load_root != pinned_root) {
-               if (unlikely(!enabled)) {
+               if (unlikely(!enforce)) {
                        report_load(origin, file, "pinning-ignored");
                        return 0;
                }
@@ -189,10 +189,11 @@ static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = {
 
 void __init loadpin_add_hooks(void)
 {
-       pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis");
+       pr_info("ready to pin (currently %senforcing)\n",
+               enforce ? "" : "not ");
        security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin");
 }
 
 /* Should not be mutable after boot, so not listed in sysfs (perm == 0). */
-module_param(enabled, int, 0);
-MODULE_PARM_DESC(enabled, "Pin module/firmware loading (default: true)");
+module_param(enforce, int, 0);
+MODULE_PARM_DESC(enforce, "Enforce module/firmware pinning");