LSM: Add /sys/kernel/security/lsm

I am still tired of having to find indirect ways to determine
what security modules are active on a system. I have added
/sys/kernel/security/lsm, which contains a comma separated
list of the active security modules. No more groping around
in /proc/filesystems or other clever hacks.

Unchanged from previous versions except for being updated
to the latest security next branch.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/security/security.c b/security/security.c
index f825304f04a7..f0a802ee29b6 100644
--- a/security/security.c
+++ b/security/security.c
@@ -32,6 +32,7 @@
 /* Maximum number of letters for an LSM name string */
 #define SECURITY_NAME_MAX	10
 
+char *lsm_names;
 /* Boot-time LSM user choice */
 static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
 	CONFIG_DEFAULT_SECURITY;
@@ -78,6 +79,22 @@ static int __init choose_lsm(char *str)
 }
 __setup("security=", choose_lsm);
 
+static int lsm_append(char *new, char **result)
+{
+	char *cp;
+
+	if (*result == NULL) {
+		*result = kstrdup(new, GFP_KERNEL);
+	} else {
+		cp = kasprintf(GFP_KERNEL, "%s,%s", *result, new);
+		if (cp == NULL)
+			return -ENOMEM;
+		kfree(*result);
+		*result = cp;
+	}
+	return 0;
+}
+
 /**
  * security_module_enable - Load given security module on boot ?
  * @module: the name of the module
@@ -97,6 +114,27 @@ int __init security_module_enable(const char *module)
 	return !strcmp(module, chosen_lsm);
 }
 
+/**
+ * security_add_hooks - Add a modules hooks to the hook lists.
+ * @hooks: the hooks to add
+ * @count: the number of hooks to add
+ * @lsm: the name of the security module
+ *
+ * Each LSM has to register its hooks with the infrastructure.
+ */
+void __init security_add_hooks(struct security_hook_list *hooks, int count,
+				char *lsm)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		hooks[i].lsm = lsm;
+		list_add_tail_rcu(&hooks[i].list, hooks[i].head);
+	}
+	if (lsm_append(lsm, &lsm_names) < 0)
+		panic("%s - Cannot get early memory.\n", __func__);
+}
+
 /*
  * Hook list operation macros.
  *