Improve debug output for kernel keyring.

Add more context to possibly failing kernel keyring routines
in log debug output.

Mostly split debug output for errors while trying to search the kernel
key by description and errors while trying to read/unlink the key
by its id.

lib/utils_keyring.c

@@ -270,6 +270,52 @@ int keyring_find_and_get_key_by_name(const char *key_name,
 	return 0;
 }
 
+key_serial_t keyring_request_key_id(key_type_t key_type,
+		const char *key_description)
+{
+	key_serial_t kid;
+
+	do {
+		kid = request_key(key_type_name(key_type), key_description, NULL, 0);
+	} while (kid < 0 && errno == EINTR);
+
+	return kid;
+}
+
+int keyring_read_key(key_serial_t kid,
+		char **key,
+		size_t *key_size)
+{
+	long r;
+	char *buf = NULL;
+	size_t len = 0;
+
+	assert(key);
+	assert(key_size);
+
+	/* just get payload size */
+	r = keyctl_read(kid, NULL, 0);
+	if (r > 0) {
+		len = r;
+		buf = crypt_safe_alloc(len);
+		if (!buf)
+			return -ENOMEM;
+
+		/* retrieve actual payload data */
+		r = keyctl_read(kid, buf, len);
+	}
+
+	if (r < 0) {
+		crypt_safe_free(buf);
+		return -EINVAL;
+	}
+
+	*key = buf;
+	*key_size = len;
+
+	return 0;
+}
+
 int keyring_get_user_key(const char *key_desc,
 		    char **key,
 		    size_t *key_size)
@@ -316,6 +362,11 @@ int keyring_unlink_key_from_keyring(key_serial_t kid, key_serial_t keyring_id)
 	return keyctl_unlink(kid, keyring_id) < 0 ? -EINVAL : 0;
 }
 
+int keyring_unlink_key_from_thread_keyring(key_serial_t kid)
+{
+	return keyctl_unlink(kid, KEY_SPEC_THREAD_KEYRING) < 0 ? -EINVAL : 0;
+}
+
 static int keyring_revoke_and_unlink_key_type(const char *type_name, const char *key_desc)
 {
 	key_serial_t kid;
@@ -489,6 +540,19 @@ int keyring_find_and_get_key_by_name(const char *key_name,
 	return -ENOTSUP;
 }
 
+key_serial_t keyring_request_key_id(key_type_t key_type,
+		const char *key_description)
+{
+	return -ENOTSUP;
+}
+
+int keyring_read_key(key_serial_t kid,
+		char **key,
+		size_t *key_size)
+{
+	return -ENOTSUP;
+}
+
 int keyring_read_by_id(const char *key_desc, char **passphrase, size_t *passphrase_len)
 {
 	return -ENOTSUP;
@@ -537,4 +601,9 @@ int keyring_unlink_key_from_keyring(key_serial_t kid, key_serial_t keyring_id)
 {
 	return -ENOTSUP;
 }
+
+int keyring_unlink_key_from_thread_keyring(key_serial_t kid)
+{
+	return -ENOTSUP;
+}
 #endif