Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 1 | /* |
| 2 | * CBC: Cipher Block Chaining mode |
| 3 | * |
| 4 | * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify it |
| 7 | * under the terms of the GNU General Public License as published by the Free |
| 8 | * Software Foundation; either version 2 of the License, or (at your option) |
| 9 | * any later version. |
| 10 | * |
| 11 | */ |
| 12 | |
| 13 | #include <crypto/algapi.h> |
| 14 | #include <linux/err.h> |
| 15 | #include <linux/init.h> |
| 16 | #include <linux/kernel.h> |
| 17 | #include <linux/module.h> |
| 18 | #include <linux/scatterlist.h> |
| 19 | #include <linux/slab.h> |
| 20 | |
| 21 | struct crypto_cbc_ctx { |
| 22 | struct crypto_cipher *child; |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 23 | }; |
| 24 | |
| 25 | static int crypto_cbc_setkey(struct crypto_tfm *parent, const u8 *key, |
| 26 | unsigned int keylen) |
| 27 | { |
| 28 | struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(parent); |
| 29 | struct crypto_cipher *child = ctx->child; |
| 30 | int err; |
| 31 | |
| 32 | crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); |
| 33 | crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & |
| 34 | CRYPTO_TFM_REQ_MASK); |
| 35 | err = crypto_cipher_setkey(child, key, keylen); |
| 36 | crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & |
| 37 | CRYPTO_TFM_RES_MASK); |
| 38 | return err; |
| 39 | } |
| 40 | |
| 41 | static int crypto_cbc_encrypt_segment(struct blkcipher_desc *desc, |
| 42 | struct blkcipher_walk *walk, |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 43 | struct crypto_cipher *tfm) |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 44 | { |
| 45 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = |
| 46 | crypto_cipher_alg(tfm)->cia_encrypt; |
| 47 | int bsize = crypto_cipher_blocksize(tfm); |
| 48 | unsigned int nbytes = walk->nbytes; |
| 49 | u8 *src = walk->src.virt.addr; |
| 50 | u8 *dst = walk->dst.virt.addr; |
| 51 | u8 *iv = walk->iv; |
| 52 | |
| 53 | do { |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 54 | crypto_xor(iv, src, bsize); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 55 | fn(crypto_cipher_tfm(tfm), dst, iv); |
| 56 | memcpy(iv, dst, bsize); |
| 57 | |
| 58 | src += bsize; |
| 59 | dst += bsize; |
| 60 | } while ((nbytes -= bsize) >= bsize); |
| 61 | |
| 62 | return nbytes; |
| 63 | } |
| 64 | |
| 65 | static int crypto_cbc_encrypt_inplace(struct blkcipher_desc *desc, |
| 66 | struct blkcipher_walk *walk, |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 67 | struct crypto_cipher *tfm) |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 68 | { |
| 69 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = |
| 70 | crypto_cipher_alg(tfm)->cia_encrypt; |
| 71 | int bsize = crypto_cipher_blocksize(tfm); |
| 72 | unsigned int nbytes = walk->nbytes; |
| 73 | u8 *src = walk->src.virt.addr; |
| 74 | u8 *iv = walk->iv; |
| 75 | |
| 76 | do { |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 77 | crypto_xor(src, iv, bsize); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 78 | fn(crypto_cipher_tfm(tfm), src, src); |
| 79 | iv = src; |
| 80 | |
| 81 | src += bsize; |
| 82 | } while ((nbytes -= bsize) >= bsize); |
| 83 | |
| 84 | memcpy(walk->iv, iv, bsize); |
| 85 | |
| 86 | return nbytes; |
| 87 | } |
| 88 | |
| 89 | static int crypto_cbc_encrypt(struct blkcipher_desc *desc, |
| 90 | struct scatterlist *dst, struct scatterlist *src, |
| 91 | unsigned int nbytes) |
| 92 | { |
| 93 | struct blkcipher_walk walk; |
| 94 | struct crypto_blkcipher *tfm = desc->tfm; |
| 95 | struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm); |
| 96 | struct crypto_cipher *child = ctx->child; |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 97 | int err; |
| 98 | |
| 99 | blkcipher_walk_init(&walk, dst, src, nbytes); |
| 100 | err = blkcipher_walk_virt(desc, &walk); |
| 101 | |
| 102 | while ((nbytes = walk.nbytes)) { |
| 103 | if (walk.src.virt.addr == walk.dst.virt.addr) |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 104 | nbytes = crypto_cbc_encrypt_inplace(desc, &walk, child); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 105 | else |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 106 | nbytes = crypto_cbc_encrypt_segment(desc, &walk, child); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 107 | err = blkcipher_walk_done(desc, &walk, nbytes); |
| 108 | } |
| 109 | |
| 110 | return err; |
| 111 | } |
| 112 | |
| 113 | static int crypto_cbc_decrypt_segment(struct blkcipher_desc *desc, |
| 114 | struct blkcipher_walk *walk, |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 115 | struct crypto_cipher *tfm) |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 116 | { |
| 117 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = |
| 118 | crypto_cipher_alg(tfm)->cia_decrypt; |
| 119 | int bsize = crypto_cipher_blocksize(tfm); |
| 120 | unsigned int nbytes = walk->nbytes; |
| 121 | u8 *src = walk->src.virt.addr; |
| 122 | u8 *dst = walk->dst.virt.addr; |
| 123 | u8 *iv = walk->iv; |
| 124 | |
| 125 | do { |
| 126 | fn(crypto_cipher_tfm(tfm), dst, src); |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 127 | crypto_xor(dst, iv, bsize); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 128 | iv = src; |
| 129 | |
| 130 | src += bsize; |
| 131 | dst += bsize; |
| 132 | } while ((nbytes -= bsize) >= bsize); |
| 133 | |
| 134 | memcpy(walk->iv, iv, bsize); |
| 135 | |
| 136 | return nbytes; |
| 137 | } |
| 138 | |
| 139 | static int crypto_cbc_decrypt_inplace(struct blkcipher_desc *desc, |
| 140 | struct blkcipher_walk *walk, |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 141 | struct crypto_cipher *tfm) |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 142 | { |
| 143 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = |
| 144 | crypto_cipher_alg(tfm)->cia_decrypt; |
| 145 | int bsize = crypto_cipher_blocksize(tfm); |
| 146 | unsigned long alignmask = crypto_cipher_alignmask(tfm); |
| 147 | unsigned int nbytes = walk->nbytes; |
| 148 | u8 *src = walk->src.virt.addr; |
| 149 | u8 stack[bsize + alignmask]; |
| 150 | u8 *first_iv = (u8 *)ALIGN((unsigned long)stack, alignmask + 1); |
| 151 | |
| 152 | memcpy(first_iv, walk->iv, bsize); |
| 153 | |
| 154 | /* Start of the last block. */ |
| 155 | src += nbytes - nbytes % bsize - bsize; |
| 156 | memcpy(walk->iv, src, bsize); |
| 157 | |
| 158 | for (;;) { |
| 159 | fn(crypto_cipher_tfm(tfm), src, src); |
| 160 | if ((nbytes -= bsize) < bsize) |
| 161 | break; |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 162 | crypto_xor(src, src - bsize, bsize); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 163 | src -= bsize; |
| 164 | } |
| 165 | |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 166 | crypto_xor(src, first_iv, bsize); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 167 | |
| 168 | return nbytes; |
| 169 | } |
| 170 | |
| 171 | static int crypto_cbc_decrypt(struct blkcipher_desc *desc, |
| 172 | struct scatterlist *dst, struct scatterlist *src, |
| 173 | unsigned int nbytes) |
| 174 | { |
| 175 | struct blkcipher_walk walk; |
| 176 | struct crypto_blkcipher *tfm = desc->tfm; |
| 177 | struct crypto_cbc_ctx *ctx = crypto_blkcipher_ctx(tfm); |
| 178 | struct crypto_cipher *child = ctx->child; |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 179 | int err; |
| 180 | |
| 181 | blkcipher_walk_init(&walk, dst, src, nbytes); |
| 182 | err = blkcipher_walk_virt(desc, &walk); |
| 183 | |
| 184 | while ((nbytes = walk.nbytes)) { |
| 185 | if (walk.src.virt.addr == walk.dst.virt.addr) |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 186 | nbytes = crypto_cbc_decrypt_inplace(desc, &walk, child); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 187 | else |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 188 | nbytes = crypto_cbc_decrypt_segment(desc, &walk, child); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 189 | err = blkcipher_walk_done(desc, &walk, nbytes); |
| 190 | } |
| 191 | |
| 192 | return err; |
| 193 | } |
| 194 | |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 195 | static int crypto_cbc_init_tfm(struct crypto_tfm *tfm) |
| 196 | { |
| 197 | struct crypto_instance *inst = (void *)tfm->__crt_alg; |
| 198 | struct crypto_spawn *spawn = crypto_instance_ctx(inst); |
| 199 | struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm); |
Herbert Xu | 2e306ee | 2006-12-17 10:05:58 +1100 | [diff] [blame] | 200 | struct crypto_cipher *cipher; |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 201 | |
Herbert Xu | 2e306ee | 2006-12-17 10:05:58 +1100 | [diff] [blame] | 202 | cipher = crypto_spawn_cipher(spawn); |
| 203 | if (IS_ERR(cipher)) |
| 204 | return PTR_ERR(cipher); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 205 | |
Herbert Xu | 2e306ee | 2006-12-17 10:05:58 +1100 | [diff] [blame] | 206 | ctx->child = cipher; |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 207 | return 0; |
| 208 | } |
| 209 | |
| 210 | static void crypto_cbc_exit_tfm(struct crypto_tfm *tfm) |
| 211 | { |
| 212 | struct crypto_cbc_ctx *ctx = crypto_tfm_ctx(tfm); |
| 213 | crypto_free_cipher(ctx->child); |
| 214 | } |
| 215 | |
Herbert Xu | ebc610e | 2007-01-01 18:37:02 +1100 | [diff] [blame] | 216 | static struct crypto_instance *crypto_cbc_alloc(struct rtattr **tb) |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 217 | { |
| 218 | struct crypto_instance *inst; |
| 219 | struct crypto_alg *alg; |
Herbert Xu | ebc610e | 2007-01-01 18:37:02 +1100 | [diff] [blame] | 220 | int err; |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 221 | |
Herbert Xu | ebc610e | 2007-01-01 18:37:02 +1100 | [diff] [blame] | 222 | err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); |
| 223 | if (err) |
| 224 | return ERR_PTR(err); |
| 225 | |
| 226 | alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, |
| 227 | CRYPTO_ALG_TYPE_MASK); |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 228 | if (IS_ERR(alg)) |
| 229 | return ERR_PTR(PTR_ERR(alg)); |
| 230 | |
| 231 | inst = crypto_alloc_instance("cbc", alg); |
| 232 | if (IS_ERR(inst)) |
| 233 | goto out_put_alg; |
| 234 | |
| 235 | inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; |
| 236 | inst->alg.cra_priority = alg->cra_priority; |
| 237 | inst->alg.cra_blocksize = alg->cra_blocksize; |
| 238 | inst->alg.cra_alignmask = alg->cra_alignmask; |
| 239 | inst->alg.cra_type = &crypto_blkcipher_type; |
| 240 | |
Herbert Xu | 3c7f076 | 2007-11-20 17:33:39 +0800 | [diff] [blame^] | 241 | /* We access the data as u32s when xoring. */ |
| 242 | inst->alg.cra_alignmask |= __alignof__(u32) - 1; |
| 243 | |
Herbert Xu | db131ef | 2006-09-21 11:44:08 +1000 | [diff] [blame] | 244 | inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; |
| 245 | inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize; |
| 246 | inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; |
| 247 | |
| 248 | inst->alg.cra_ctxsize = sizeof(struct crypto_cbc_ctx); |
| 249 | |
| 250 | inst->alg.cra_init = crypto_cbc_init_tfm; |
| 251 | inst->alg.cra_exit = crypto_cbc_exit_tfm; |
| 252 | |
| 253 | inst->alg.cra_blkcipher.setkey = crypto_cbc_setkey; |
| 254 | inst->alg.cra_blkcipher.encrypt = crypto_cbc_encrypt; |
| 255 | inst->alg.cra_blkcipher.decrypt = crypto_cbc_decrypt; |
| 256 | |
| 257 | out_put_alg: |
| 258 | crypto_mod_put(alg); |
| 259 | return inst; |
| 260 | } |
| 261 | |
| 262 | static void crypto_cbc_free(struct crypto_instance *inst) |
| 263 | { |
| 264 | crypto_drop_spawn(crypto_instance_ctx(inst)); |
| 265 | kfree(inst); |
| 266 | } |
| 267 | |
| 268 | static struct crypto_template crypto_cbc_tmpl = { |
| 269 | .name = "cbc", |
| 270 | .alloc = crypto_cbc_alloc, |
| 271 | .free = crypto_cbc_free, |
| 272 | .module = THIS_MODULE, |
| 273 | }; |
| 274 | |
| 275 | static int __init crypto_cbc_module_init(void) |
| 276 | { |
| 277 | return crypto_register_template(&crypto_cbc_tmpl); |
| 278 | } |
| 279 | |
| 280 | static void __exit crypto_cbc_module_exit(void) |
| 281 | { |
| 282 | crypto_unregister_template(&crypto_cbc_tmpl); |
| 283 | } |
| 284 | |
| 285 | module_init(crypto_cbc_module_init); |
| 286 | module_exit(crypto_cbc_module_exit); |
| 287 | |
| 288 | MODULE_LICENSE("GPL"); |
| 289 | MODULE_DESCRIPTION("CBC block cipher algorithm"); |