lsm: rename the lsm order variables for consistency

Rename the builtin_lsm_order variable to lsm_order_builtin,
chosen_lsm_order to lsm_order_cmdline, chosen_major_lsm to
lsm_order_legacy, ordered_lsms[] to lsm_order[], and exclusive
to lsm_exclusive.

This patch also renames the associated kernel command line parsing
functions and adds some basic function comment blocks. The parsing
function choose_major_lsm() was renamed to lsm_choose_security(),
choose_lsm_order() to lsm_choose_lsm(), and enable_debug() to
lsm_debug_enable().

Reviewed-by: Kees Cook <[e-mail]>
Reviewed-by: John Johansen <[e-mail]>
Reviewed-by: Casey Schaufler <[e-mail]>
Reviewed-by: Mimi Zohar <[e-mail]>
Signed-off-by: Paul Moore <[e-mail]>

security/lsm_init.c

···
 extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
 extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];
 
-/* Boot-time LSM user choice */
-static __initconst const char *const builtin_lsm_order = CONFIG_LSM;
-static __initdata const char *chosen_lsm_order;
-static __initdata const char *chosen_major_lsm;
+/* Build and boot-time LSM ordering. */
+static __initconst const char *const lsm_order_builtin = CONFIG_LSM;
+static __initdata const char *lsm_order_cmdline;
+static __initdata const char *lsm_order_legacy;
 
 /* Ordered list of LSMs to initialize. */
-static __initdata struct lsm_info *ordered_lsms[MAX_LSM_COUNT + 1];
-static __initdata struct lsm_info *exclusive;
+static __initdata struct lsm_info *lsm_order[MAX_LSM_COUNT + 1];
+static __initdata struct lsm_info *lsm_exclusive;
 
 static __initdata bool debug;
 #define init_debug(...)							\
···
 	} while (0)
 
 #define lsm_order_for_each(iter)					\
-	for ((iter) = ordered_lsms; *(iter); (iter)++)
+	for ((iter) = lsm_order; *(iter); (iter)++)
 #define lsm_for_each_raw(iter)						\
 	for ((iter) = __start_lsm_info;					\
 	     (iter) < __end_lsm_info; (iter)++)
···
 	for ((iter) = __start_early_lsm_info;				\
 	     (iter) < __end_early_lsm_info; (iter)++)
 
-static int lsm_append(const char *new, char **result);
-
-/* Save user chosen LSM */
-static int __init choose_major_lsm(char *str)
+/**
+ * lsm_choose_security - Legacy "major" LSM selection
+ * @str: kernel command line parameter
+ */
+static int __init lsm_choose_security(char *str)
 {
-	chosen_major_lsm = str;
+	lsm_order_legacy = str;
 	return 1;
 }
-__setup("security=", choose_major_lsm);
+__setup("security=", lsm_choose_security);
 
-/* Explicitly choose LSM initialization order. */
-static int __init choose_lsm_order(char *str)
+/**
+ * lsm_choose_lsm - Modern LSM selection
+ * @str: kernel command line parameter
+ */
+static int __init lsm_choose_lsm(char *str)
 {
-	chosen_lsm_order = str;
+	lsm_order_cmdline = str;
 	return 1;
 }
-__setup("lsm=", choose_lsm_order);
+__setup("lsm=", lsm_choose_lsm);
 
-/* Enable LSM order debugging. */
-static int __init enable_debug(char *str)
+/**
+ * lsm_debug_enable - Enable LSM framework debugging
+ * @str: kernel command line parameter
+ *
+ * Currently we only provide debug info during LSM initialization, but we may
+ * want to expand this in the future.
+ */
+static int __init lsm_debug_enable(char *str)
 {
 	debug = true;
 	return 1;
 }
-__setup("lsm.debug", enable_debug);
+__setup("lsm.debug", lsm_debug_enable);
 
 /* Mark an LSM's enabled flag. */
 static int lsm_enabled_true __initdata = 1;
···
 	/* Enable this LSM, if it is not already set. */
 	if (!lsm->enabled)
 		lsm->enabled = &lsm_enabled_true;
-	ordered_lsms[last_lsm] = lsm;
+	lsm_order[last_lsm] = lsm;
 	lsm_idlist[last_lsm++] = lsm->id;
 
 	init_debug("%s ordered: %s (%s)\n", from, lsm->id->name,
···
 	if (!is_enabled(lsm)) {
 		set_enabled(lsm, false);
 		return;
-	} else if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && exclusive) {
+	} else if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && lsm_exclusive) {
 		init_debug("exclusive disabled: %s\n", lsm->id->name);
 		set_enabled(lsm, false);
 		return;
···
 
 	/* Mark the LSM as enabled. */
 	set_enabled(lsm, true);
-	if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !exclusive) {
+	if ((lsm->flags & LSM_FLAG_EXCLUSIVE) && !lsm_exclusive) {
 		init_debug("exclusive chosen:   %s\n", lsm->id->name);
-		exclusive = lsm;
+		lsm_exclusive = lsm;
 	}
 
 	/* Register the LSM blob sizes. */
···
 	}
 
 	/* Process "security=", if given. */
-	if (chosen_major_lsm) {
+	if (lsm_order_legacy) {
 		struct lsm_info *major;
 
 		/*
···
 		 */
 		lsm_for_each_raw(major) {
 			if ((major->flags & LSM_FLAG_LEGACY_MAJOR) &&
-			    strcmp(major->id->name, chosen_major_lsm) != 0) {
+			    strcmp(major->id->name, lsm_order_legacy) != 0) {
 				set_enabled(major, false);
 				init_debug("security=%s disabled: %s (only one legacy major LSM)\n",
-					   chosen_major_lsm, major->id->name);
+					   lsm_order_legacy, major->id->name);
 			}
 		}
 	}
···
 	}
 
 	/* Process "security=", if given. */
-	if (chosen_major_lsm) {
+	if (lsm_order_legacy) {
 		lsm_for_each_raw(lsm) {
 			if (exists_ordered_lsm(lsm))
 				continue;
-			if (strcmp(lsm->id->name, chosen_major_lsm) == 0)
+			if (strcmp(lsm->id->name, lsm_order_legacy) == 0)
 				append_ordered_lsm(lsm, "security=");
 		}
 	}
···
 	struct lsm_info **lsm;
 	struct lsm_info *early;
 
-	if (chosen_lsm_order) {
-		if (chosen_major_lsm) {
+	if (lsm_order_cmdline) {
+		if (lsm_order_legacy) {
 			pr_warn("security=%s is ignored because it is superseded by lsm=%s\n",
-				chosen_major_lsm, chosen_lsm_order);
-			chosen_major_lsm = NULL;
+				lsm_order_legacy, lsm_order_cmdline);
+			lsm_order_legacy = NULL;
 		}
-		ordered_lsm_parse(chosen_lsm_order, "cmdline");
+		ordered_lsm_parse(lsm_order_cmdline, "cmdline");
 	} else
-		ordered_lsm_parse(builtin_lsm_order, "builtin");
+		ordered_lsm_parse(lsm_order_builtin, "builtin");
 
 	lsm_order_for_each(lsm) {
 		lsm_prepare(*lsm);
···
 {
 	struct lsm_info *lsm;
 
-	init_debug("legacy security=%s\n", chosen_major_lsm ? : " *unspecified*");
-	init_debug("  CONFIG_LSM=%s\n", builtin_lsm_order);
-	init_debug("boot arg lsm=%s\n", chosen_lsm_order ? : " *unspecified*");
+	init_debug("legacy security=%s\n", lsm_order_legacy ? : " *unspecified*");
+	init_debug("  CONFIG_LSM=%s\n", lsm_order_builtin);
+	init_debug("boot arg lsm=%s\n", lsm_order_cmdline ? : " *unspecified*");
 
 	/*
 	 * Append the names of the early LSM modules now that kmalloc() is