Move generic ciper backend utilities to separate file.

And add wrapped key check.

lib/crypto_backend/Makemodule.am

@@ -8,7 +8,8 @@ libcrypto_backend_la_SOURCES = \
 	lib/crypto_backend/crypto_storage.c \
 	lib/crypto_backend/pbkdf_check.c \
 	lib/crypto_backend/crc32.c \
-	lib/crypto_backend/argon2_generic.c
+	lib/crypto_backend/argon2_generic.c \
+	lib/crypto_backend/cipher_generic.c
 
 if CRYPTO_BACKEND_GCRYPT
 libcrypto_backend_la_SOURCES += lib/crypto_backend/crypto_gcrypt.c

lib/crypto_backend/cipher_generic.c

@@ -0,0 +1,78 @@
+/*
+ * Linux kernel cipher generic utilities
+ *
+ * Copyright (C) 2018, Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2018, Milan Broz
+ *
+ * This file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This file is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this file; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <string.h>
+#include <stdbool.h>
+#include <errno.h>
+#include "crypto_backend.h"
+
+struct cipher_alg {
+	const char *name;
+	int blocksize;
+	bool wrapped_key;
+};
+
+/* FIXME: Getting block size should be dynamic from cipher backend. */
+static const struct cipher_alg cipher_algs[] = {
+	{ "cipher_null", 16, false },
+	{ "aes",         16, false },
+	{ "serpent",     16, false },
+	{ "twofish",     16, false },
+	{ "anubis",      16, false },
+	{ "blowfish",     8, false },
+	{ "camellia",    16, false },
+	{ "cast5",        8, false },
+	{ "cast6",       16, false },
+	{ "des",          8, false },
+	{ "des3_ede",     8, false },
+	{ "khazad",       8, false },
+	{ "seed",        16, false },
+	{ "tea",          8, false },
+	{ "xtea",         8, false },
+	{ "paes",        16,  true }, /* protected AES, s390 wrapped key scheme */
+	{ NULL,           0, false }
+};
+
+static const struct cipher_alg *_get_alg(const char *name)
+{
+	int i = 0;
+
+	while (name && cipher_algs[i].name) {
+		if (!strcasecmp(name, cipher_algs[i].name))
+			return &cipher_algs[i];
+		i++;
+	}
+	return NULL;
+}
+
+int crypt_cipher_blocksize(const char *name)
+{
+	const struct cipher_alg *ca = _get_alg(name);
+
+	return ca ? ca->blocksize : -EINVAL;
+}
+
+int crypt_cipher_wrapped_key(const char *name)
+{
+	const struct cipher_alg *ca = _get_alg(name);
+
+	return ca ? (int)ca->wrapped_key : 0;
+}

lib/crypto_backend/crypto_backend.h

@@ -100,6 +100,7 @@ uint32_t crypt_crc32(uint32_t seed, const unsigned char *buf, size_t len);
 
 /* ciphers */
 int crypt_cipher_blocksize(const char *name);
+int crypt_cipher_wrapped_key(const char *name);
 int crypt_cipher_init(struct crypt_cipher **ctx, const char *name,
 		    const char *mode, const void *key, size_t key_length);
 void crypt_cipher_destroy(struct crypt_cipher *ctx);

lib/crypto_backend/crypto_cipher_kernel.c

@@ -44,50 +44,6 @@ struct crypt_cipher {
 	int opfd;
 };
 
-struct cipher_alg {
-	const char *name;
-	int blocksize;
-};
-
-/* FIXME: Getting block size should be dynamic from cipher backend. */
-static struct cipher_alg cipher_algs[] = {
-	{ "cipher_null", 16 },
-	{ "aes",         16 },
-	{ "serpent",     16 },
-	{ "twofish",     16 },
-	{ "anubis",      16 },
-	{ "blowfish",     8 },
-	{ "camellia",    16 },
-	{ "cast5",        8 },
-	{ "cast6",       16 },
-	{ "des",          8 },
-	{ "des3_ede",     8 },
-	{ "khazad",       8 },
-	{ "seed",        16 },
-	{ "tea",          8 },
-	{ "xtea",         8 },
-	{ NULL,           0 }
-};
-
-static struct cipher_alg *_get_alg(const char *name)
-{
-	int i = 0;
-
-	while (name && cipher_algs[i].name) {
-		if (!strcasecmp(name, cipher_algs[i].name))
-			return &cipher_algs[i];
-		i++;
-	}
-	return NULL;
-}
-
-int crypt_cipher_blocksize(const char *name)
-{
-	struct cipher_alg *ca = _get_alg(name);
-
-	return ca ? ca->blocksize : -EINVAL;
-}
-
 /*
  * ciphers
  *
@@ -236,12 +192,6 @@ void crypt_cipher_destroy(struct crypt_cipher *ctx)
 }
 
 #else /* ENABLE_AF_ALG */
-
-int crypt_cipher_blocksize(const char *name)
-{
-	return -EINVAL;
-}
-
 int crypt_cipher_init(struct crypt_cipher **ctx, const char *name,
 		    const char *mode, const void *buffer, size_t length)
 {

lib/luks2/luks2_keyslot.c

@@ -125,8 +125,8 @@ int LUKS2_keyslot_cipher_incompatible(struct crypt_device *cd)
 	if (crypt_get_integrity_tag_size(cd) || !cipher)
 		return 1;
 
-	/* protected AES (PAES) is a wrapped key scheme, not a block cipher */
+	/* Wrapped key schemes cannot be used for keyslot encryption */
-	if (!strncmp("paes", cipher, 4))
+	if (crypt_cipher_wrapped_key(cipher))
 		return 1;
 
 	return 0;