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/algapi.h> 18 #include <crypto/internal/skcipher.h> 19 #include <linux/err.h> 20 #include <linux/init.h> 21 #include <linux/kernel.h> 22 #include <linux/module.h> 23 #include <linux/slab.h> 24 #include <linux/compiler.h> 25 26 struct crypto_pcbc_ctx { 27 struct crypto_cipher *child; 28 }; 29 30 static int crypto_pcbc_setkey(struct crypto_skcipher *parent, const u8 *key, 31 unsigned int keylen) 32 { 33 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(parent); 34 struct crypto_cipher *child = ctx->child; 35 int err; 36 37 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 38 crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) & 39 CRYPTO_TFM_REQ_MASK); 40 err = crypto_cipher_setkey(child, key, keylen); 41 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) & 42 CRYPTO_TFM_RES_MASK); 43 return err; 44 } 45 46 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req, 47 struct skcipher_walk *walk, 48 struct crypto_cipher *tfm) 49 { 50 int bsize = crypto_cipher_blocksize(tfm); 51 unsigned int nbytes = walk->nbytes; 52 u8 *src = walk->src.virt.addr; 53 u8 *dst = walk->dst.virt.addr; 54 u8 *iv = walk->iv; 55 56 do { 57 crypto_xor(iv, src, bsize); 58 crypto_cipher_encrypt_one(tfm, dst, iv); 59 crypto_xor_cpy(iv, dst, src, bsize); 60 61 src += bsize; 62 dst += bsize; 63 } while ((nbytes -= bsize) >= bsize); 64 65 return nbytes; 66 } 67 68 static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req, 69 struct skcipher_walk *walk, 70 struct crypto_cipher *tfm) 71 { 72 int bsize = crypto_cipher_blocksize(tfm); 73 unsigned int nbytes = walk->nbytes; 74 u8 *src = walk->src.virt.addr; 75 u8 *iv = walk->iv; 76 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE]; 77 78 do { 79 memcpy(tmpbuf, src, bsize); 80 crypto_xor(iv, src, bsize); 81 crypto_cipher_encrypt_one(tfm, src, iv); 82 crypto_xor_cpy(iv, tmpbuf, 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 crypto_xor_cpy(iv, dst, src, bsize); 130 131 src += bsize; 132 dst += bsize; 133 } while ((nbytes -= bsize) >= bsize); 134 135 memcpy(walk->iv, iv, bsize); 136 137 return nbytes; 138 } 139 140 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req, 141 struct skcipher_walk *walk, 142 struct crypto_cipher *tfm) 143 { 144 int bsize = crypto_cipher_blocksize(tfm); 145 unsigned int nbytes = walk->nbytes; 146 u8 *src = walk->src.virt.addr; 147 u8 *iv = walk->iv; 148 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32)); 149 150 do { 151 memcpy(tmpbuf, src, bsize); 152 crypto_cipher_decrypt_one(tfm, src, src); 153 crypto_xor(src, iv, bsize); 154 crypto_xor_cpy(iv, src, tmpbuf, bsize); 155 156 src += bsize; 157 } while ((nbytes -= bsize) >= bsize); 158 159 memcpy(walk->iv, iv, bsize); 160 161 return nbytes; 162 } 163 164 static int crypto_pcbc_decrypt(struct skcipher_request *req) 165 { 166 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 167 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 168 struct crypto_cipher *child = ctx->child; 169 struct skcipher_walk walk; 170 unsigned int nbytes; 171 int err; 172 173 err = skcipher_walk_virt(&walk, req, false); 174 175 while ((nbytes = walk.nbytes)) { 176 if (walk.src.virt.addr == walk.dst.virt.addr) 177 nbytes = crypto_pcbc_decrypt_inplace(req, &walk, 178 child); 179 else 180 nbytes = crypto_pcbc_decrypt_segment(req, &walk, 181 child); 182 err = skcipher_walk_done(&walk, nbytes); 183 } 184 185 return err; 186 } 187 188 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm) 189 { 190 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 191 struct crypto_spawn *spawn = skcipher_instance_ctx(inst); 192 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 193 struct crypto_cipher *cipher; 194 195 cipher = crypto_spawn_cipher(spawn); 196 if (IS_ERR(cipher)) 197 return PTR_ERR(cipher); 198 199 ctx->child = cipher; 200 return 0; 201 } 202 203 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm) 204 { 205 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 206 207 crypto_free_cipher(ctx->child); 208 } 209 210 static void crypto_pcbc_free(struct skcipher_instance *inst) 211 { 212 crypto_drop_skcipher(skcipher_instance_ctx(inst)); 213 kfree(inst); 214 } 215 216 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb) 217 { 218 struct skcipher_instance *inst; 219 struct crypto_attr_type *algt; 220 struct crypto_spawn *spawn; 221 struct crypto_alg *alg; 222 int err; 223 224 algt = crypto_get_attr_type(tb); 225 if (IS_ERR(algt)) 226 return PTR_ERR(algt); 227 228 if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) & 229 ~CRYPTO_ALG_INTERNAL) 230 return -EINVAL; 231 232 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 233 if (!inst) 234 return -ENOMEM; 235 236 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER | 237 (algt->type & CRYPTO_ALG_INTERNAL), 238 CRYPTO_ALG_TYPE_MASK | 239 (algt->mask & CRYPTO_ALG_INTERNAL)); 240 err = PTR_ERR(alg); 241 if (IS_ERR(alg)) 242 goto err_free_inst; 243 244 spawn = skcipher_instance_ctx(inst); 245 err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst), 246 CRYPTO_ALG_TYPE_MASK); 247 if (err) 248 goto err_put_alg; 249 250 err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg); 251 if (err) 252 goto err_drop_spawn; 253 254 inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL; 255 inst->alg.base.cra_priority = alg->cra_priority; 256 inst->alg.base.cra_blocksize = alg->cra_blocksize; 257 inst->alg.base.cra_alignmask = alg->cra_alignmask; 258 259 inst->alg.ivsize = alg->cra_blocksize; 260 inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize; 261 inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize; 262 263 inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx); 264 265 inst->alg.init = crypto_pcbc_init_tfm; 266 inst->alg.exit = crypto_pcbc_exit_tfm; 267 268 inst->alg.setkey = crypto_pcbc_setkey; 269 inst->alg.encrypt = crypto_pcbc_encrypt; 270 inst->alg.decrypt = crypto_pcbc_decrypt; 271 272 inst->free = crypto_pcbc_free; 273 274 err = skcipher_register_instance(tmpl, inst); 275 if (err) 276 goto err_drop_spawn; 277 crypto_mod_put(alg); 278 279 out: 280 return err; 281 282 err_drop_spawn: 283 crypto_drop_spawn(spawn); 284 err_put_alg: 285 crypto_mod_put(alg); 286 err_free_inst: 287 kfree(inst); 288 goto out; 289 } 290 291 static struct crypto_template crypto_pcbc_tmpl = { 292 .name = "pcbc", 293 .create = crypto_pcbc_create, 294 .module = THIS_MODULE, 295 }; 296 297 static int __init crypto_pcbc_module_init(void) 298 { 299 return crypto_register_template(&crypto_pcbc_tmpl); 300 } 301 302 static void __exit crypto_pcbc_module_exit(void) 303 { 304 crypto_unregister_template(&crypto_pcbc_tmpl); 305 } 306 307 module_init(crypto_pcbc_module_init); 308 module_exit(crypto_pcbc_module_exit); 309 310 MODULE_LICENSE("GPL"); 311 MODULE_DESCRIPTION("PCBC block cipher algorithm"); 312 MODULE_ALIAS_CRYPTO("pcbc"); 313