lsm: rework lsm_active_cnt and lsm_idlist[]

JIRA: https://issues.redhat.com/browse/RHEL-179440
CVE: CVE-2026-46054

commit 250898ca335f337bc032a9693dc0a30a1cb85825
Author: Paul Moore <paul@paul-moore.com>
Date:   Wed Feb 12 15:36:51 2025 -0500

    lsm: rework lsm_active_cnt and lsm_idlist[]

    Move the LSM active count and lsm_id list declarations out of a header
    that is visible across the kernel and into a header that is limited to
    the LSM framework.  This not only helps keep the include/linux headers
    smaller and cleaner, it helps prevent misuse of these variables.

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

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>

include/linux/security.h

@@ -167,8 +167,6 @@ struct lsm_prop {
 };
 
 extern const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1];
-extern u32 lsm_active_cnt;
-extern const struct lsm_id *lsm_idlist[];
 
 /* These functions are in security/commoncap.c */
 extern int cap_capable(const struct cred *cred, struct user_namespace *ns,

security/lsm.h

@@ -7,6 +7,11 @@
 #define _LSM_H_
 
 #include <linux/lsm_hooks.h>
+#include <linux/lsm_count.h>
+
+/* List of configured LSMs */
+extern unsigned int lsm_active_cnt;
+extern const struct lsm_id *lsm_idlist[];
 
 /* LSM blob configuration */
 extern struct lsm_blob_sizes blob_sizes;

security/lsm_init.c

@@ -214,12 +214,6 @@ static void __init initialize_lsm(struct lsm_info *lsm)
 	}
 }
 
-/*
- * Current index to use while initializing the lsm id list.
- */
-u32 lsm_active_cnt __ro_after_init;
-const struct lsm_id *lsm_idlist[MAX_LSM_COUNT];
-
 /* Populate ordered LSMs list from comma-separated LSM name list. */
 static void __init ordered_lsm_parse(const char *order, const char *origin)
 {

security/lsm_syscalls.c

@@ -17,6 +17,8 @@
 #include <linux/lsm_hooks.h>
 #include <uapi/linux/lsm.h>
 
+#include "lsm.h"
+
 /**
  * lsm_name_to_attr - map an LSM attribute name to its ID
  * @name: name of the attribute

security/security.c

@@ -74,6 +74,9 @@ const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX + 1] = {
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
 
+unsigned int lsm_active_cnt __ro_after_init;
+const struct lsm_id *lsm_idlist[MAX_LSM_COUNT];
+
 struct lsm_blob_sizes blob_sizes;
 
 struct kmem_cache *lsm_file_cache;