1 /* 2 * PCBC: Propagating Cipher Block Chaining mode 3 * 4 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 * 7 * Derived from cbc.c 8 * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License as published by the Free 12 * Software Foundation; either version 2 of the License, or (at your option) 13 * any later version. 14 * 15 */ 16 17 #include <crypto/internal/skcipher.h> 18 #include <linux/err.h> 19 #include <linux/init.h> 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 #include <linux/slab.h> 23 24 struct crypto_pcbc_ctx { 25 struct crypto_cipher *child; 26 }; 27 28 static int crypto_pcbc_setkey(struct crypto_skcipher *parent, const u8 *key, 29 unsigned int keylen) 30 { 31 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(parent); 32 struct crypto_cipher *child = ctx->child; 33 int err; 34 35 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 36 crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) & 37 CRYPTO_TFM_REQ_MASK); 38 err = crypto_cipher_setkey(child, key, keylen); 39 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) & 40 CRYPTO_TFM_RES_MASK); 41 return err; 42 } 43 44 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req, 45 struct skcipher_walk *walk, 46 struct crypto_cipher *tfm) 47 { 48 int bsize = crypto_cipher_blocksize(tfm); 49 unsigned int nbytes = walk->nbytes; 50 u8 *src = walk->src.virt.addr; 51 u8 *dst = walk->dst.virt.addr; 52 u8 *iv = walk->iv; 53 54 do { 55 crypto_xor(iv, src, bsize); 56 crypto_cipher_encrypt_one(tfm, dst, iv); 57 memcpy(iv, dst, bsize); 58 crypto_xor(iv, src, bsize); 59 60 src += bsize; 61 dst += bsize; 62 } while ((nbytes -= bsize) >= bsize); 63 64 return nbytes; 65 } 66 67 static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req, 68 struct skcipher_walk *walk, 69 struct crypto_cipher *tfm) 70 { 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 u8 tmpbuf[bsize]; 76 77 do { 78 memcpy(tmpbuf, src, bsize); 79 crypto_xor(iv, src, bsize); 80 crypto_cipher_encrypt_one(tfm, src, iv); 81 memcpy(iv, tmpbuf, bsize); 82 crypto_xor(iv, src, bsize); 83 84 src += bsize; 85 } while ((nbytes -= bsize) >= bsize); 86 87 memcpy(walk->iv, iv, bsize); 88 89 return nbytes; 90 } 91 92 static int crypto_pcbc_encrypt(struct skcipher_request *req) 93 { 94 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 95 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 96 struct crypto_cipher *child = ctx->child; 97 struct skcipher_walk walk; 98 unsigned int nbytes; 99 int err; 100 101 err = skcipher_walk_virt(&walk, req, false); 102 103 while ((nbytes = walk.nbytes)) { 104 if (walk.src.virt.addr == walk.dst.virt.addr) 105 nbytes = crypto_pcbc_encrypt_inplace(req, &walk, 106 child); 107 else 108 nbytes = crypto_pcbc_encrypt_segment(req, &walk, 109 child); 110 err = skcipher_walk_done(&walk, nbytes); 111 } 112 113 return err; 114 } 115 116 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req, 117 struct skcipher_walk *walk, 118 struct crypto_cipher *tfm) 119 { 120 int bsize = crypto_cipher_blocksize(tfm); 121 unsigned int nbytes = walk->nbytes; 122 u8 *src = walk->src.virt.addr; 123 u8 *dst = walk->dst.virt.addr; 124 u8 *iv = walk->iv; 125 126 do { 127 crypto_cipher_decrypt_one(tfm, dst, src); 128 crypto_xor(dst, iv, bsize); 129 memcpy(iv, src, bsize); 130 crypto_xor(iv, dst, bsize); 131 132 src += bsize; 133 dst += bsize; 134 } while ((nbytes -= bsize) >= bsize); 135 136 memcpy(walk->iv, iv, bsize); 137 138 return nbytes; 139 } 140 141 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req, 142 struct skcipher_walk *walk, 143 struct crypto_cipher *tfm) 144 { 145 int bsize = crypto_cipher_blocksize(tfm); 146 unsigned int nbytes = walk->nbytes; 147 u8 *src = walk->src.virt.addr; 148 u8 *iv = walk->iv; 149 u8 tmpbuf[bsize] __attribute__ ((aligned(__alignof__(u32)))); 150 151 do { 152 memcpy(tmpbuf, src, bsize); 153 crypto_cipher_decrypt_one(tfm, src, src); 154 crypto_xor(src, iv, bsize); 155 memcpy(iv, tmpbuf, bsize); 156 crypto_xor(iv, src, bsize); 157 158 src += bsize; 159 } while ((nbytes -= bsize) >= bsize); 160 161 memcpy(walk->iv, iv, bsize); 162 163 return nbytes; 164 } 165 166 static int crypto_pcbc_decrypt(struct skcipher_request *req) 167 { 168 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 169 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 170 struct crypto_cipher *child = ctx->child; 171 struct skcipher_walk walk; 172 unsigned int nbytes; 173 int err; 174 175 err = skcipher_walk_virt(&walk, req, false); 176 177 while ((nbytes = walk.nbytes)) { 178 if (walk.src.virt.addr == walk.dst.virt.addr) 179 nbytes = crypto_pcbc_decrypt_inplace(req, &walk, 180 child); 181 else 182 nbytes = crypto_pcbc_decrypt_segment(req, &walk, 183 child); 184 err = skcipher_walk_done(&walk, nbytes); 185 } 186 187 return err; 188 } 189 190 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm) 191 { 192 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 193 struct crypto_spawn *spawn = skcipher_instance_ctx(inst); 194 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 195 struct crypto_cipher *cipher; 196 197 cipher = crypto_spawn_cipher(spawn); 198 if (IS_ERR(cipher)) 199 return PTR_ERR(cipher); 200 201 ctx->child = cipher; 202 return 0; 203 } 204 205 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm) 206 { 207 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 208 209 crypto_free_cipher(ctx->child); 210 } 211 212 static void crypto_pcbc_free(struct skcipher_instance *inst) 213 { 214 crypto_drop_skcipher(skcipher_instance_ctx(inst)); 215 kfree(inst); 216 } 217 218 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb) 219 { 220 struct skcipher_instance *inst; 221 struct crypto_attr_type *algt; 222 struct crypto_spawn *spawn; 223 struct crypto_alg *alg; 224 int err; 225 226 algt = crypto_get_attr_type(tb); 227 if (IS_ERR(algt)) 228 return PTR_ERR(algt); 229 230 if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) & 231 ~CRYPTO_ALG_INTERNAL) 232 return -EINVAL; 233 234 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 235 if (!inst) 236 return -ENOMEM; 237 238 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER | 239 (algt->type & CRYPTO_ALG_INTERNAL), 240 CRYPTO_ALG_TYPE_MASK | 241 (algt->mask & CRYPTO_ALG_INTERNAL)); 242 err = PTR_ERR(alg); 243 if (IS_ERR(alg)) 244 goto err_free_inst; 245 246 spawn = skcipher_instance_ctx(inst); 247 err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst), 248 CRYPTO_ALG_TYPE_MASK); 249 crypto_mod_put(alg); 250 if (err) 251 goto err_free_inst; 252 253 err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg); 254 if (err) 255 goto err_drop_spawn; 256 257 inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL; 258 inst->alg.base.cra_priority = alg->cra_priority; 259 inst->alg.base.cra_blocksize = alg->cra_blocksize; 260 inst->alg.base.cra_alignmask = alg->cra_alignmask; 261 262 /* We access the data as u32s when xoring. */ 263 inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; 264 265 inst->alg.ivsize = alg->cra_blocksize; 266 inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize; 267 inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize; 268 269 inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx); 270 271 inst->alg.init = crypto_pcbc_init_tfm; 272 inst->alg.exit = crypto_pcbc_exit_tfm; 273 274 inst->alg.setkey = crypto_pcbc_setkey; 275 inst->alg.encrypt = crypto_pcbc_encrypt; 276 inst->alg.decrypt = crypto_pcbc_decrypt; 277 278 inst->free = crypto_pcbc_free; 279 280 err = skcipher_register_instance(tmpl, inst); 281 if (err) 282 goto err_drop_spawn; 283 284 out: 285 return err; 286 287 err_drop_spawn: 288 crypto_drop_spawn(spawn); 289 err_free_inst: 290 kfree(inst); 291 goto out; 292 } 293 294 static struct crypto_template crypto_pcbc_tmpl = { 295 .name = "pcbc", 296 .create = crypto_pcbc_create, 297 .module = THIS_MODULE, 298 }; 299 300 static int __init crypto_pcbc_module_init(void) 301 { 302 return crypto_register_template(&crypto_pcbc_tmpl); 303 } 304 305 static void __exit crypto_pcbc_module_exit(void) 306 { 307 crypto_unregister_template(&crypto_pcbc_tmpl); 308 } 309 310 module_init(crypto_pcbc_module_init); 311 module_exit(crypto_pcbc_module_exit); 312 313 MODULE_LICENSE("GPL"); 314 MODULE_DESCRIPTION("PCBC block cipher algorithm"); 315 MODULE_ALIAS_CRYPTO("pcbc"); 316