1 files changed, 253 insertions, 0 deletions
diff --git a/lib/loopaes/loopaes.c b/lib/loopaes/loopaes.c
new file mode 100644
index 0000000..e281fc8
--- /dev/null
+++ b/lib/loopaes/loopaes.c
@@ -0,0 +1,253 @@
+/*
+ * loop-AES compatible volume handling
+ *
+ * Copyright (C) 2011-2021 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2011-2021 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 <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libcryptsetup.h"
+#include "loopaes.h"
+#include "internal.h"
+
+static const char *get_hash(unsigned int key_size)
+{
+	const char *hash;
+
+	switch (key_size) {
+		case 16: hash = "sha256"; break;
+		case 24: hash = "sha384"; break;
+		case 32: hash = "sha512"; break;
+		default: hash = NULL;
+	}
+
+	return hash;
+}
+
+static unsigned char get_tweak(unsigned int keys_count)
+{
+	switch (keys_count) {
+		case 64: return 0x55;
+		case 65: return 0xF4;
+		default: break;
+	}
+	return 0x00;
+}
+
+static int hash_key(const char *src, size_t src_len,
+		    char *dst, size_t dst_len,
+		    const char *hash_name)
+{
+	struct crypt_hash *hd = NULL;
+	int r;
+
+	if (crypt_hash_init(&hd, hash_name))
+		return -EINVAL;
+
+	r = crypt_hash_write(hd, src, src_len);
+	if (!r)
+		r = crypt_hash_final(hd, dst, dst_len);
+
+	crypt_hash_destroy(hd);
+	return r;
+}
+
+static int hash_keys(struct crypt_device *cd,
+		     struct volume_key **vk,
+		     const char *hash_override,
+		     const char **input_keys,
+		     unsigned int keys_count,
+		     unsigned int key_len_output,
+		     unsigned int key_len_input)
+{
+	const char *hash_name;
+	char tweak, *key_ptr;
+	unsigned int i;
+	int r = 0;
+
+	hash_name = hash_override ?: get_hash(key_len_output);
+	tweak = get_tweak(keys_count);
+
+	if (!keys_count || !key_len_output || !hash_name || !key_len_input) {
+		log_err(cd, _("Key processing error (using hash %s)."),
+			hash_name ?: "[none]");
+		return -EINVAL;
+	}
+
+	*vk = crypt_alloc_volume_key((size_t)key_len_output * keys_count, NULL);
+	if (!*vk)
+		return -ENOMEM;
+
+	for (i = 0; i < keys_count; i++) {
+		key_ptr = &(*vk)->key[i * key_len_output];
+		r = hash_key(input_keys[i], key_len_input, key_ptr,
+			     key_len_output, hash_name);
+		if (r < 0)
+			break;
+
+		key_ptr[0] ^= tweak;
+	}
+
+	if (r < 0 && *vk) {
+		crypt_free_volume_key(*vk);
+		*vk = NULL;
+	}
+	return r;
+}
+
+static int keyfile_is_gpg(char *buffer, size_t buffer_len)
+{
+	int r = 0;
+	int index = buffer_len < 100 ? buffer_len - 1 : 100;
+	char eos = buffer[index];
+
+	buffer[index] = '\0';
+	if (strstr(buffer, "BEGIN PGP MESSAGE"))
+		r = 1;
+	buffer[index] = eos;
+	return r;
+}
+
+int LOOPAES_parse_keyfile(struct crypt_device *cd,
+			  struct volume_key **vk,
+			  const char *hash,
+			  unsigned int *keys_count,
+			  char *buffer,
+			  size_t buffer_len)
+{
+	const char *keys[LOOPAES_KEYS_MAX];
+	unsigned int key_lengths[LOOPAES_KEYS_MAX];
+	unsigned int i, key_index, key_len, offset;
+
+	log_dbg(cd, "Parsing loop-AES keyfile of size %zu.", buffer_len);
+
+	if (!buffer_len)
+		return -EINVAL;
+
+	if (keyfile_is_gpg(buffer, buffer_len)) {
+		log_err(cd, _("Detected not yet supported GPG encrypted keyfile."));
+		log_std(cd, _("Please use gpg --decrypt <KEYFILE> | cryptsetup --keyfile=- ...\n"));
+		return -EINVAL;
+	}
+
+	/* Remove EOL in buffer */
+	for (i = 0; i < buffer_len; i++)
+		if (buffer[i] == '\n' || buffer[i] == '\r')
+			buffer[i] = '\0';
+
+	offset = 0;
+	key_index = 0;
+	key_lengths[0] = 0;
+	while (offset < buffer_len && key_index < LOOPAES_KEYS_MAX) {
+		keys[key_index] = &buffer[offset];
+		key_lengths[key_index] = 0;;
+		while (offset < buffer_len && buffer[offset]) {
+			offset++;
+			key_lengths[key_index]++;
+		}
+		if (offset == buffer_len) {
+			log_dbg(cd, "Unterminated key #%d in keyfile.", key_index);
+			log_err(cd, _("Incompatible loop-AES keyfile detected."));
+			return -EINVAL;
+		}
+		while (offset < buffer_len && !buffer[offset])
+			offset++;
+		key_index++;
+	}
+
+	/* All keys must be the same length */
+	key_len = key_lengths[0];
+	for (i = 0; i < key_index; i++)
+		if (!key_lengths[i] || (key_lengths[i] != key_len)) {
+			log_dbg(cd, "Unexpected length %d of key #%d (should be %d).",
+				key_lengths[i], i, key_len);
+			key_len = 0;
+			break;
+		}
+
+	if (offset != buffer_len || key_len == 0 ||
+	   (key_index != 1 && key_index !=64 && key_index != 65)) {
+		log_err(cd, _("Incompatible loop-AES keyfile detected."));
+		return -EINVAL;
+	}
+
+	log_dbg(cd, "Keyfile: %d keys of length %d.", key_index, key_len);
+
+	*keys_count = key_index;
+	return hash_keys(cd, vk, hash, keys, key_index,
+			 crypt_get_volume_key_size(cd), key_len);
+}
+
+int LOOPAES_activate(struct crypt_device *cd,
+		     const char *name,
+		     const char *base_cipher,
+		     unsigned int keys_count,
+		     struct volume_key *vk,
+		     uint32_t flags)
+{
+	int r;
+	uint32_t req_flags, dmc_flags;
+	char *cipher = NULL;
+	struct crypt_dm_active_device dmd = {
+		.flags = flags,
+	};
+
+	r = device_block_adjust(cd, crypt_data_device(cd), DEV_EXCL,
+				crypt_get_data_offset(cd), &dmd.size, &dmd.flags);
+	if (r)
+		return r;
+
+	if (keys_count == 1) {
+		req_flags = DM_PLAIN64_SUPPORTED;
+		r = asprintf(&cipher, "%s-%s", base_cipher, "cbc-plain64");
+	} else {
+		req_flags = DM_LMK_SUPPORTED;
+		r = asprintf(&cipher, "%s:%d-%s", base_cipher, 64, "cbc-lmk");
+	}
+	if (r < 0)
+		return -ENOMEM;
+
+	r = dm_crypt_target_set(&dmd.segment, 0, dmd.size, crypt_data_device(cd),
+			vk, cipher, crypt_get_iv_offset(cd),
+			crypt_get_data_offset(cd), crypt_get_integrity(cd),
+			crypt_get_integrity_tag_size(cd), crypt_get_sector_size(cd));
+
+	if (r) {
+		free(cipher);
+		return r;
+	}
+
+	log_dbg(cd, "Trying to activate loop-AES device %s using cipher %s.",
+		name, cipher);
+
+	r = dm_create_device(cd, name, CRYPT_LOOPAES, &dmd);
+
+	if (r < 0 && !dm_flags(cd, DM_CRYPT, &dmc_flags) &&
+	    (dmc_flags & req_flags) != req_flags) {
+		log_err(cd, _("Kernel does not support loop-AES compatible mapping."));
+		r = -ENOTSUP;
+	}
+
+	dm_targets_free(cd, &dmd);
+	free(cipher);
+
+	return r;
+}