integrity: provide a function to load x509 certificate from the kernel

Provide the function to load x509 certificates from the kernel into the
integrity kernel keyring.

Changes in v2:
* configuration option removed
* function declared as '__init'
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

security/integrity/digsig.c

@@ -14,7 +14,7 @@
 
 #include <linux/err.h>
 #include <linux/sched.h>
-#include <linux/rbtree.h>
+#include <linux/slab.h>
 #include <linux/cred.h>
 #include <linux/key-type.h>
 #include <linux/digsig.h>
@@ -84,3 +84,37 @@ int __init integrity_init_keyring(const unsigned int id)
 	}
 	return err;
 }
+
+int __init integrity_load_x509(const unsigned int id, char *path)
+{
+	key_ref_t key;
+	char *data;
+	int rc;
+
+	if (!keyring[id])
+		return -EINVAL;
+
+	rc = integrity_read_file(path, &data);
+	if (rc < 0)
+		return rc;
+
+	key = key_create_or_update(make_key_ref(keyring[id], 1),
+				   "asymmetric",
+				   NULL,
+				   data,
+				   rc,
+				   ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
+				    KEY_USR_VIEW | KEY_USR_READ),
+				   KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_TRUSTED);
+	if (IS_ERR(key)) {
+		rc = PTR_ERR(key);
+		pr_err("Problem loading X.509 certificate (%d): %s\n",
+		       rc, path);
+	} else {
+		pr_notice("Loaded X.509 cert '%s': %s\n",
+			  key_ref_to_ptr(key)->description, path);
+		key_ref_put(key);
+	}
+	kfree(data);
+	return 0;
+}

security/integrity/integrity.h

@@ -134,6 +134,7 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 			    const char *digest, int digestlen);
 
 int __init integrity_init_keyring(const unsigned int id);
+int __init integrity_load_x509(const unsigned int id, char *path);
 #else
 
 static inline int integrity_digsig_verify(const unsigned int id,
@@ -147,6 +148,7 @@ static inline int integrity_init_keyring(const unsigned int id)
 {
 	return 0;
 }
+
 #endif /* CONFIG_INTEGRITY_SIGNATURE */
 
 #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS