2 * Generic wrapper for storage encryption modes and Initial Vectors
3 * (reimplementation of some functions from Linux dm-crypt kernel)
5 * Copyright (C) 2014-2021 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 {
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,
64 memset(ctx, 0, sizeof(*ctx));
66 ctx->iv_size = crypt_cipher_ivsize(cipher_name, mode_name);
67 if (ctx->iv_size < 0 || (strcmp(mode_name, "ecb") && ctx->iv_size < 8))
70 if (!strcmp(cipher_name, "cipher_null") ||
71 !strcmp(mode_name, "ecb")) {
77 } else if (!iv_name) {
79 } else if (!strcasecmp(iv_name, "null")) {
81 } else if (!strcasecmp(iv_name, "plain64")) {
82 ctx->type = IV_PLAIN64;
83 } else if (!strcasecmp(iv_name, "plain64be")) {
84 ctx->type = IV_PLAIN64BE;
85 } else if (!strcasecmp(iv_name, "plain")) {
87 } else if (!strncasecmp(iv_name, "essiv:", 6)) {
88 struct crypt_hash *h = NULL;
89 char *hash_name = strchr(iv_name, ':');
96 hash_size = crypt_hash_size(++hash_name);
100 if ((unsigned)hash_size > sizeof(tmp))
103 if (crypt_hash_init(&h, hash_name))
106 r = crypt_hash_write(h, key, key_length);
108 crypt_hash_destroy(h);
112 r = crypt_hash_final(h, tmp, hash_size);
113 crypt_hash_destroy(h);
115 crypt_backend_memzero(tmp, sizeof(tmp));
119 r = crypt_cipher_init(&ctx->cipher, cipher_name, "ecb",
121 crypt_backend_memzero(tmp, sizeof(tmp));
125 ctx->type = IV_ESSIV;
126 } else if (!strncasecmp(iv_name, "benbi", 5)) {
127 int log = int_log2(ctx->iv_size);
128 if (log > SECTOR_SHIFT)
131 ctx->type = IV_BENBI;
132 ctx->shift = SECTOR_SHIFT - log;
133 } else if (!strncasecmp(iv_name, "eboiv", 5)) {
134 r = crypt_cipher_init(&ctx->cipher, cipher_name, "ecb",
139 ctx->type = IV_EBOIV;
140 ctx->shift = int_log2(sector_size);
144 ctx->iv = malloc(ctx->iv_size);
151 static int crypt_sector_iv_generate(struct crypt_sector_iv *ctx, uint64_t sector)
159 memset(ctx->iv, 0, ctx->iv_size);
162 memset(ctx->iv, 0, ctx->iv_size);
163 *(uint32_t *)ctx->iv = cpu_to_le32(sector & 0xffffffff);
166 memset(ctx->iv, 0, ctx->iv_size);
167 *(uint64_t *)ctx->iv = cpu_to_le64(sector);
170 memset(ctx->iv, 0, ctx->iv_size);
171 *(uint64_t *)&ctx->iv[ctx->iv_size - sizeof(uint64_t)] = cpu_to_be64(sector);
174 memset(ctx->iv, 0, ctx->iv_size);
175 *(uint64_t *)ctx->iv = cpu_to_le64(sector);
176 return crypt_cipher_encrypt(ctx->cipher,
177 ctx->iv, ctx->iv, ctx->iv_size, NULL, 0);
180 memset(ctx->iv, 0, ctx->iv_size);
181 val = cpu_to_be64((sector << ctx->shift) + 1);
182 memcpy(ctx->iv + ctx->iv_size - sizeof(val), &val, sizeof(val));
185 memset(ctx->iv, 0, ctx->iv_size);
186 *(uint64_t *)ctx->iv = cpu_to_le64(sector << ctx->shift);
187 return crypt_cipher_encrypt(ctx->cipher,
188 ctx->iv, ctx->iv, ctx->iv_size, NULL, 0);
197 static void crypt_sector_iv_destroy(struct crypt_sector_iv *ctx)
199 if (ctx->type == IV_ESSIV || ctx->type == IV_EBOIV)
200 crypt_cipher_destroy(ctx->cipher);
203 memset(ctx->iv, 0, ctx->iv_size);
207 memset(ctx, 0, sizeof(*ctx));
210 /* Block encryption storage wrappers */
212 int crypt_storage_init(struct crypt_storage **ctx,
215 const char *cipher_mode,
216 const void *key, size_t key_length,
219 struct crypt_storage *s;
221 char *cipher_iv = NULL;
224 if (sector_size < (1 << SECTOR_SHIFT) ||
225 sector_size > (1 << (SECTOR_SHIFT + 3)) ||
226 sector_size & (sector_size - 1))
229 s = malloc(sizeof(*s));
232 memset(s, 0, sizeof(*s));
234 /* Remove IV if present */
235 strncpy(mode_name, cipher_mode, sizeof(mode_name));
236 mode_name[sizeof(mode_name) - 1] = 0;
237 cipher_iv = strchr(mode_name, '-');
243 r = crypt_cipher_init(&s->cipher, cipher, mode_name, key, key_length);
245 crypt_storage_destroy(s);
249 r = crypt_sector_iv_init(&s->cipher_iv, cipher, mode_name, cipher_iv, key, key_length, sector_size);
251 crypt_storage_destroy(s);
255 s->sector_size = sector_size;
256 s->iv_shift = large_iv ? int_log2(sector_size) - SECTOR_SHIFT : 0;
262 int crypt_storage_decrypt(struct crypt_storage *ctx,
264 uint64_t length, char *buffer)
269 if (length & (ctx->sector_size - 1))
272 if (iv_offset & ((ctx->sector_size >> SECTOR_SHIFT) - 1))
275 for (i = 0; i < length; i += ctx->sector_size) {
276 r = crypt_sector_iv_generate(&ctx->cipher_iv, (iv_offset + (i >> SECTOR_SHIFT)) >> ctx->iv_shift);
279 r = crypt_cipher_decrypt(ctx->cipher,
284 ctx->cipher_iv.iv_size);
292 int crypt_storage_encrypt(struct crypt_storage *ctx,
294 uint64_t length, char *buffer)
299 if (length & (ctx->sector_size - 1))
302 if (iv_offset & ((ctx->sector_size >> SECTOR_SHIFT) - 1))
305 for (i = 0; i < length; i += ctx->sector_size) {
306 r = crypt_sector_iv_generate(&ctx->cipher_iv, (iv_offset + (i >> SECTOR_SHIFT)) >> ctx->iv_shift);
309 r = crypt_cipher_encrypt(ctx->cipher,
314 ctx->cipher_iv.iv_size);
322 void crypt_storage_destroy(struct crypt_storage *ctx)
327 crypt_sector_iv_destroy(&ctx->cipher_iv);
330 crypt_cipher_destroy(ctx->cipher);
332 memset(ctx, 0, sizeof(*ctx));
336 bool crypt_storage_kernel_only(struct crypt_storage *ctx)
338 return crypt_cipher_kernel_only(ctx->cipher);