2 * Generic wrapper for storage encryption modes and Initial Vectors
3 * (reimplementation of some functions from Linux dm-crypt kernel)
5 * Copyright (C) 2014-2020 Milan Broz
7 * This file is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * This file is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this file; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
25 #include "crypto_backend.h"
27 #define SECTOR_SHIFT 9
31 * IV documentation: https://gitlab.com/cryptsetup/cryptsetup/wikis/DMCrypt
33 struct crypt_sector_iv {
34 enum { IV_NONE, IV_NULL, IV_PLAIN, IV_PLAIN64, IV_ESSIV, IV_BENBI, IV_PLAIN64BE, IV_EBOIV } type;
37 struct crypt_cipher *cipher;
41 /* Block encryption storage context */
42 struct crypt_storage {
43 unsigned sector_shift;
45 struct crypt_cipher *cipher;
46 struct crypt_sector_iv cipher_iv;
49 static int int_log2(unsigned int x)
52 for (x >>= 1; x > 0; x >>= 1)
57 static int crypt_sector_iv_init(struct crypt_sector_iv *ctx,
58 const char *cipher_name, const char *mode_name,
59 const char *iv_name, const void *key, size_t key_length, size_t sector_size)
63 memset(ctx, 0, sizeof(*ctx));
65 ctx->iv_size = crypt_cipher_ivsize(cipher_name, mode_name);
69 if (!strcmp(cipher_name, "cipher_null") ||
70 !strcmp(mode_name, "ecb")) {
76 } else if (!iv_name) {
78 } else if (!strcasecmp(iv_name, "null")) {
80 } else if (!strcasecmp(iv_name, "plain64")) {
81 ctx->type = IV_PLAIN64;
82 } else if (!strcasecmp(iv_name, "plain64be")) {
83 ctx->type = IV_PLAIN64BE;
84 } else if (!strcasecmp(iv_name, "plain")) {
86 } else if (!strncasecmp(iv_name, "essiv:", 6)) {
87 struct crypt_hash *h = NULL;
88 char *hash_name = strchr(iv_name, ':');
95 hash_size = crypt_hash_size(++hash_name);
99 if ((unsigned)hash_size > sizeof(tmp))
102 if (crypt_hash_init(&h, hash_name))
105 r = crypt_hash_write(h, key, key_length);
107 crypt_hash_destroy(h);
111 r = crypt_hash_final(h, tmp, hash_size);
112 crypt_hash_destroy(h);
114 crypt_backend_memzero(tmp, sizeof(tmp));
118 r = crypt_cipher_init(&ctx->cipher, cipher_name, "ecb",
120 crypt_backend_memzero(tmp, sizeof(tmp));
124 ctx->type = IV_ESSIV;
125 } else if (!strncasecmp(iv_name, "benbi", 5)) {
126 int log = int_log2(ctx->iv_size);
127 if (log > SECTOR_SHIFT)
130 ctx->type = IV_BENBI;
131 ctx->shift = SECTOR_SHIFT - log;
132 } else if (!strncasecmp(iv_name, "eboiv", 5)) {
133 r = crypt_cipher_init(&ctx->cipher, cipher_name, "ecb",
138 ctx->type = IV_EBOIV;
139 ctx->shift = int_log2(sector_size);
143 ctx->iv = malloc(ctx->iv_size);
150 static int crypt_sector_iv_generate(struct crypt_sector_iv *ctx, uint64_t sector)
158 memset(ctx->iv, 0, ctx->iv_size);
161 memset(ctx->iv, 0, ctx->iv_size);
162 *(uint32_t *)ctx->iv = cpu_to_le32(sector & 0xffffffff);
165 memset(ctx->iv, 0, ctx->iv_size);
166 *(uint64_t *)ctx->iv = cpu_to_le64(sector);
169 memset(ctx->iv, 0, ctx->iv_size);
170 *(uint64_t *)&ctx->iv[ctx->iv_size - sizeof(uint64_t)] = cpu_to_be64(sector);
173 memset(ctx->iv, 0, ctx->iv_size);
174 *(uint64_t *)ctx->iv = cpu_to_le64(sector);
175 return crypt_cipher_encrypt(ctx->cipher,
176 ctx->iv, ctx->iv, ctx->iv_size, NULL, 0);
179 memset(ctx->iv, 0, ctx->iv_size);
180 val = cpu_to_be64((sector << ctx->shift) + 1);
181 memcpy(ctx->iv + ctx->iv_size - sizeof(val), &val, sizeof(val));
184 memset(ctx->iv, 0, ctx->iv_size);
185 *(uint64_t *)ctx->iv = cpu_to_le64(sector << ctx->shift);
186 return crypt_cipher_encrypt(ctx->cipher,
187 ctx->iv, ctx->iv, ctx->iv_size, NULL, 0);
196 static void crypt_sector_iv_destroy(struct crypt_sector_iv *ctx)
198 if (ctx->type == IV_ESSIV || ctx->type == IV_EBOIV)
199 crypt_cipher_destroy(ctx->cipher);
202 memset(ctx->iv, 0, ctx->iv_size);
206 memset(ctx, 0, sizeof(*ctx));
209 /* Block encryption storage wrappers */
211 int crypt_storage_init(struct crypt_storage **ctx,
214 const char *cipher_mode,
215 const void *key, size_t key_length)
217 struct crypt_storage *s;
219 char *cipher_iv = NULL;
222 if (sector_size < (1 << SECTOR_SHIFT) ||
223 sector_size > (1 << (SECTOR_SHIFT + 3)) ||
224 sector_size & (sector_size - 1))
227 s = malloc(sizeof(*s));
230 memset(s, 0, sizeof(*s));
232 /* Remove IV if present */
233 strncpy(mode_name, cipher_mode, sizeof(mode_name));
234 mode_name[sizeof(mode_name) - 1] = 0;
235 cipher_iv = strchr(mode_name, '-');
241 r = crypt_cipher_init(&s->cipher, cipher, mode_name, key, key_length);
243 crypt_storage_destroy(s);
247 r = crypt_sector_iv_init(&s->cipher_iv, cipher, mode_name, cipher_iv, key, key_length, sector_size);
249 crypt_storage_destroy(s);
253 s->sector_shift = int_log2(sector_size);
254 s->iv_shift = s->sector_shift - SECTOR_SHIFT;
260 int crypt_storage_decrypt(struct crypt_storage *ctx,
262 uint64_t length, char *buffer)
267 if (length & ((1 << ctx->sector_shift) - 1))
270 length >>= ctx->sector_shift;
272 for (i = 0; i < length; i++) {
273 r = crypt_sector_iv_generate(&ctx->cipher_iv, iv_offset + (uint64_t)(i << ctx->iv_shift));
276 r = crypt_cipher_decrypt(ctx->cipher,
277 &buffer[i << ctx->sector_shift],
278 &buffer[i << ctx->sector_shift],
279 1 << ctx->sector_shift,
281 ctx->cipher_iv.iv_size);
289 int crypt_storage_encrypt(struct crypt_storage *ctx,
291 uint64_t length, char *buffer)
296 if (length & ((1 << ctx->sector_shift) - 1))
299 length >>= ctx->sector_shift;
301 for (i = 0; i < length; i++) {
302 r = crypt_sector_iv_generate(&ctx->cipher_iv, iv_offset + (i << ctx->iv_shift));
305 r = crypt_cipher_encrypt(ctx->cipher,
306 &buffer[i << ctx->sector_shift],
307 &buffer[i << ctx->sector_shift],
308 1 << ctx->sector_shift,
310 ctx->cipher_iv.iv_size);
318 void crypt_storage_destroy(struct crypt_storage *ctx)
323 crypt_sector_iv_destroy(&ctx->cipher_iv);
326 crypt_cipher_destroy(ctx->cipher);
328 memset(ctx, 0, sizeof(*ctx));
332 bool crypt_storage_kernel_only(struct crypt_storage *ctx)
334 return crypt_cipher_kernel_only(ctx->cipher);