lsm: replace the name field with a pointer to the lsm_id struct

Reduce the duplication between the lsm_id struct and the DEFINE_LSM()
definition by linking the lsm_id struct directly into the individual
LSM's DEFINE_LSM() instance.

Linking the lsm_id into the LSM definition also allows us to simplify
the security_add_hooks() function by removing the code which populates
the lsm_idlist[] array and moving it into the normal LSM startup code
where the LSM list is parsed and the individual LSMs are enabled,
making for a cleaner implementation with less overhead at boot.

Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

include/linux/lsm_hooks.h

@@ -152,7 +152,7 @@ enum lsm_order {
 };
 
 struct lsm_info {
-	const char *name;	/* Required. */
+	const struct lsm_id *id;
 	enum lsm_order order;	/* Optional: default is LSM_ORDER_MUTABLE */
 	unsigned long flags;	/* Optional: flags describing LSM */
 	int *enabled;		/* Optional: controlled by CONFIG_LSM */

security/apparmor/lsm.c

@@ -2555,7 +2555,7 @@ static int __init apparmor_init(void)
 }
 
 DEFINE_LSM(apparmor) = {
-	.name = "apparmor",
+	.id = &apparmor_lsmid,
 	.flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
 	.enabled = &apparmor_enabled,
 	.blobs = &apparmor_blob_sizes,

security/bpf/hooks.c

@@ -33,7 +33,7 @@ struct lsm_blob_sizes bpf_lsm_blob_sizes __ro_after_init = {
 };
 
 DEFINE_LSM(bpf) = {
-	.name = "bpf",
+	.id = &bpf_lsmid,
 	.init = bpf_lsm_init,
 	.blobs = &bpf_lsm_blob_sizes
 };

security/commoncap.c

@@ -1505,7 +1505,7 @@ static int __init capability_init(void)
 }
 
 DEFINE_LSM(capability) = {
-	.name = "capability",
+	.id = &capability_lsmid,
 	.order = LSM_ORDER_FIRST,
 	.init = capability_init,
 };

security/integrity/evm/evm_main.c

@@ -1175,7 +1175,7 @@ struct lsm_blob_sizes evm_blob_sizes __ro_after_init = {
 };
 
 DEFINE_LSM(evm) = {
-	.name = "evm",
+	.id = &evm_lsmid,
 	.init = init_evm_lsm,
 	.order = LSM_ORDER_LAST,
 	.blobs = &evm_blob_sizes,

security/integrity/ima/ima_main.c

@@ -1279,7 +1279,7 @@ struct lsm_blob_sizes ima_blob_sizes __ro_after_init = {
 };
 
 DEFINE_LSM(ima) = {
-	.name = "ima",
+	.id = &ima_lsmid,
 	.init = init_ima_lsm,
 	.order = LSM_ORDER_LAST,
 	.blobs = &ima_blob_sizes,

security/ipe/ipe.c

@@ -92,7 +92,7 @@ static int __init ipe_init(void)
 }
 
 DEFINE_LSM(ipe) = {
-	.name = "ipe",
+	.id = &ipe_lsmid,
 	.init = ipe_init,
 	.blobs = &ipe_blobs,
 };

security/landlock/setup.c

@@ -75,7 +75,7 @@ static int __init landlock_init(void)
 }
 
 DEFINE_LSM(LANDLOCK_NAME) = {
-	.name = LANDLOCK_NAME,
+	.id = &landlock_lsmid,
 	.init = landlock_init,
 	.blobs = &landlock_blob_sizes,
 };

security/loadpin/loadpin.c

@@ -271,7 +271,7 @@ static int __init loadpin_init(void)
 }
 
 DEFINE_LSM(loadpin) = {
-	.name = "loadpin",
+	.id = &loadpin_lsmid,
 	.init = loadpin_init,
 };
 

security/lockdown/lockdown.c

@@ -168,6 +168,6 @@ DEFINE_EARLY_LSM(lockdown) = {
 #else
 DEFINE_LSM(lockdown) = {
 #endif
-	.name = "lockdown",
+	.id = &lockdown_lsmid,
 	.init = lockdown_lsm_init,
 };

security/lsm_init.c

@@ -127,9 +127,10 @@ static void __init append_ordered_lsm(struct lsm_info *lsm, const char *from)
 	/* Enable this LSM, if it is not already set. */
 	if (!lsm->enabled)
 		lsm->enabled = &lsm_enabled_true;
-	ordered_lsms[last_lsm++] = lsm;
+	ordered_lsms[last_lsm] = lsm;
+	lsm_idlist[last_lsm++] = lsm->id;
 
-	init_debug("%s ordered: %s (%s)\n", from, lsm->name,
+	init_debug("%s ordered: %s (%s)\n", from, lsm->id->name,
 		   is_enabled(lsm) ? "enabled" : "disabled");
 }
 
@@ -157,7 +158,7 @@ static void __init lsm_prepare(struct lsm_info *lsm)
 		set_enabled(lsm, false);
 		return;
 	} else if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && exclusive) {
-		init_debug("exclusive disabled: %s\n", lsm->name);
+		init_debug("exclusive disabled: %s\n", lsm->id->name);
 		set_enabled(lsm, false);
 		return;
 	}
@@ -165,7 +166,7 @@ static void __init lsm_prepare(struct lsm_info *lsm)
 	/* Mark the LSM as enabled. */
 	set_enabled(lsm, true);
 	if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !exclusive) {
-		init_debug("exclusive chosen:   %s\n", lsm->name);
+		init_debug("exclusive chosen:   %s\n", lsm->id->name);
 		exclusive = lsm;
 	}
 
@@ -200,9 +201,9 @@ static void __init initialize_lsm(struct lsm_info *lsm)
 	if (is_enabled(lsm)) {
 		int ret;
 
-		init_debug("initializing %s\n", lsm->name);
+		init_debug("initializing %s\n", lsm->id->name);
 		ret = lsm->init();
-		WARN(ret, "%s failed to initialize: %d\n", lsm->name, ret);
+		WARN(ret, "%s failed to initialize: %d\n", lsm->id->name, ret);
 	}
 }
 
@@ -236,10 +237,10 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
 		 */
 		lsm_for_each_raw(major) {
 			if ((major->flags & LSM_FLAG_LEGACY_MAJOR) &&
-			    strcmp(major->name, chosen_major_lsm) != 0) {
+			    strcmp(major->id->name, chosen_major_lsm) != 0) {
 				set_enabled(major, false);
 				init_debug("security=%s disabled: %s (only one legacy major LSM)\n",
-					   chosen_major_lsm, major->name);
+					   chosen_major_lsm, major->id->name);
 			}
 		}
 	}
@@ -251,7 +252,7 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
 		bool found = false;
 
 		lsm_for_each_raw(lsm) {
-			if (strcmp(lsm->name, name) == 0) {
+			if (strcmp(lsm->id->name, name) == 0) {
 				if (lsm->order == LSM_ORDER_MUTABLE)
 					append_ordered_lsm(lsm, origin);
 				found = true;
@@ -268,7 +269,7 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
 		lsm_for_each_raw(lsm) {
 			if (exists_ordered_lsm(lsm))
 				continue;
-			if (strcmp(lsm->name, chosen_major_lsm) == 0)
+			if (strcmp(lsm->id->name, chosen_major_lsm) == 0)
 				append_ordered_lsm(lsm, "security=");
 		}
 	}
@@ -285,7 +286,7 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
 			continue;
 		set_enabled(lsm, false);
 		init_debug("%s skipped: %s (not in requested order)\n",
-			   origin, lsm->name);
+			   origin, lsm->id->name);
 	}
 
 	kfree(sep);
@@ -317,11 +318,13 @@ static void __init lsm_init_ordered(void)
 	pr_info("initializing lsm=");
 	lsm_early_for_each_raw(early) {
 		if (is_enabled(early))
-			pr_cont("%s%s", first++ == 0 ? "" : ",", early->name);
+			pr_cont("%s%s",
+				first++ == 0 ? "" : ",", early->id->name);
 	}
 	lsm_order_for_each(lsm) {
 		if (is_enabled(*lsm))
-			pr_cont("%s%s", first++ == 0 ? "" : ",", (*lsm)->name);
+			pr_cont("%s%s",
+				first++ == 0 ? "" : ",", (*lsm)->id->name);
 	}
 	pr_cont("\n");
 
@@ -432,18 +435,6 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
 {
 	int i;
 
-	/*
-	 * A security module may call security_add_hooks() more
-	 * than once during initialization, and LSM initialization
-	 * is serialized. Landlock is one such case.
-	 * Look at the previous entry, if there is one, for duplication.
-	 */
-	if (lsm_active_cnt == 0 || lsm_idlist[lsm_active_cnt - 1] != lsmid) {
-		if (lsm_active_cnt >= MAX_LSM_COUNT)
-			panic("%s Too many LSMs registered.\n", __func__);
-		lsm_idlist[lsm_active_cnt++] = lsmid;
-	}
-
 	for (i = 0; i < count; i++) {
 		hooks[i].lsmid = lsmid;
 		lsm_static_call_init(&hooks[i]);
@@ -491,10 +482,10 @@ int __init security_init(void)
 	 * available
 	 */
 	lsm_early_for_each_raw(lsm) {
-		init_debug("  early started: %s (%s)\n", lsm->name,
+		init_debug("  early started: %s (%s)\n", lsm->id->name,
 			   is_enabled(lsm) ? "enabled" : "disabled");
 		if (lsm->enabled)
-			lsm_append(lsm->name, &lsm_names);
+			lsm_append(lsm->id->name, &lsm_names);
 	}
 
 	/* Load LSMs in specified order. */

security/safesetid/lsm.c

@@ -287,6 +287,6 @@ static int __init safesetid_security_init(void)
 }
 
 DEFINE_LSM(safesetid_security_init) = {
+	.id = &safesetid_lsmid,
 	.init = safesetid_security_init,
-	.name = "safesetid",
 };

security/selinux/hooks.c

@@ -7639,7 +7639,7 @@ void selinux_complete_init(void)
 /* SELinux requires early initialization in order to label
    all processes and objects when they are created. */
 DEFINE_LSM(selinux) = {
-	.name = "selinux",
+	.id = &selinux_lsmid,
 	.flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
 	.enabled = &selinux_enabled_boot,
 	.blobs = &selinux_blob_sizes,

security/smack/smack_lsm.c

@@ -5280,7 +5280,7 @@ static __init int smack_init(void)
  * all processes and objects when they are created.
  */
 DEFINE_LSM(smack) = {
-	.name = "smack",
+	.id = &smack_lsmid,
 	.flags = LSM_FLAG_LEGACY_MAJOR | LSM_FLAG_EXCLUSIVE,
 	.blobs = &smack_blob_sizes,
 	.init = smack_init,

security/tomoyo/tomoyo.c

@@ -612,7 +612,7 @@ static int __init tomoyo_init(void)
 }
 
 DEFINE_LSM(tomoyo) = {
-	.name = "tomoyo",
+	.id = &tomoyo_lsmid,
 	.enabled = &tomoyo_enabled,
 	.flags = LSM_FLAG_LEGACY_MAJOR,
 	.blobs = &tomoyo_blob_sizes,

security/yama/yama_lsm.c

@@ -476,6 +476,6 @@ static int __init yama_init(void)
 }
 
 DEFINE_LSM(yama) = {
-	.name = "yama",
+	.id = &yama_lsmid,
 	.init = yama_init,
 };