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 #include <linux/compiler.h> 24 25 struct crypto_pcbc_ctx { 26 struct crypto_cipher *child; 27 }; 28 29 static int crypto_pcbc_setkey(struct crypto_skcipher *parent, const u8 *key, 30 unsigned int keylen) 31 { 32 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(parent); 33 struct crypto_cipher *child = ctx->child; 34 int err; 35 36 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); 37 crypto_cipher_set_flags(child, crypto_skcipher_get_flags(parent) & 38 CRYPTO_TFM_REQ_MASK); 39 err = crypto_cipher_setkey(child, key, keylen); 40 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) & 41 CRYPTO_TFM_RES_MASK); 42 return err; 43 } 44 45 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req, 46 struct skcipher_walk *walk, 47 struct crypto_cipher *tfm) 48 { 49 int bsize = crypto_cipher_blocksize(tfm); 50 unsigned int nbytes = walk->nbytes; 51 u8 *src = walk->src.virt.addr; 52 u8 *dst = walk->dst.virt.addr; 53 u8 *iv = walk->iv; 54 55 do { 56 crypto_xor(iv, src, bsize); 57 crypto_cipher_encrypt_one(tfm, dst, iv); 58 crypto_xor_cpy(iv, dst, 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 crypto_xor_cpy(iv, tmpbuf, src, bsize); 82 83 src += bsize; 84 } while ((nbytes -= bsize) >= bsize); 85 86 memcpy(walk->iv, iv, bsize); 87 88 return nbytes; 89 } 90 91 static int crypto_pcbc_encrypt(struct skcipher_request *req) 92 { 93 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 94 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 95 struct crypto_cipher *child = ctx->child; 96 struct skcipher_walk walk; 97 unsigned int nbytes; 98 int err; 99 100 err = skcipher_walk_virt(&walk, req, false); 101 102 while ((nbytes = walk.nbytes)) { 103 if (walk.src.virt.addr == walk.dst.virt.addr) 104 nbytes = crypto_pcbc_encrypt_inplace(req, &walk, 105 child); 106 else 107 nbytes = crypto_pcbc_encrypt_segment(req, &walk, 108 child); 109 err = skcipher_walk_done(&walk, nbytes); 110 } 111 112 return err; 113 } 114 115 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req, 116 struct skcipher_walk *walk, 117 struct crypto_cipher *tfm) 118 { 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 crypto_cipher_decrypt_one(tfm, dst, src); 127 crypto_xor(dst, iv, bsize); 128 crypto_xor_cpy(iv, dst, src, bsize); 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_pcbc_decrypt_inplace(struct skcipher_request *req, 140 struct skcipher_walk *walk, 141 struct crypto_cipher *tfm) 142 { 143 int bsize = crypto_cipher_blocksize(tfm); 144 unsigned int nbytes = walk->nbytes; 145 u8 *src = walk->src.virt.addr; 146 u8 *iv = walk->iv; 147 u8 tmpbuf[bsize] __aligned(__alignof__(u32)); 148 149 do { 150 memcpy(tmpbuf, src, bsize); 151 crypto_cipher_decrypt_one(tfm, src, src); 152 crypto_xor(src, iv, bsize); 153 crypto_xor_cpy(iv, src, tmpbuf, bsize); 154 155 src += bsize; 156 } while ((nbytes -= bsize) >= bsize); 157 158 memcpy(walk->iv, iv, bsize); 159 160 return nbytes; 161 } 162 163 static int crypto_pcbc_decrypt(struct skcipher_request *req) 164 { 165 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 166 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 167 struct crypto_cipher *child = ctx->child; 168 struct skcipher_walk walk; 169 unsigned int nbytes; 170 int err; 171 172 err = skcipher_walk_virt(&walk, req, false); 173 174 while ((nbytes = walk.nbytes)) { 175 if (walk.src.virt.addr == walk.dst.virt.addr) 176 nbytes = crypto_pcbc_decrypt_inplace(req, &walk, 177 child); 178 else 179 nbytes = crypto_pcbc_decrypt_segment(req, &walk, 180 child); 181 err = skcipher_walk_done(&walk, nbytes); 182 } 183 184 return err; 185 } 186 187 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm) 188 { 189 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 190 struct crypto_spawn *spawn = skcipher_instance_ctx(inst); 191 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 192 struct crypto_cipher *cipher; 193 194 cipher = crypto_spawn_cipher(spawn); 195 if (IS_ERR(cipher)) 196 return PTR_ERR(cipher); 197 198 ctx->child = cipher; 199 return 0; 200 } 201 202 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm) 203 { 204 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 205 206 crypto_free_cipher(ctx->child); 207 } 208 209 static void crypto_pcbc_free(struct skcipher_instance *inst) 210 { 211 crypto_drop_skcipher(skcipher_instance_ctx(inst)); 212 kfree(inst); 213 } 214 215 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb) 216 { 217 struct skcipher_instance *inst; 218 struct crypto_attr_type *algt; 219 struct crypto_spawn *spawn; 220 struct crypto_alg *alg; 221 int err; 222 223 algt = crypto_get_attr_type(tb); 224 if (IS_ERR(algt)) 225 return PTR_ERR(algt); 226 227 if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) & 228 ~CRYPTO_ALG_INTERNAL) 229 return -EINVAL; 230 231 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 232 if (!inst) 233 return -ENOMEM; 234 235 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER | 236 (algt->type & CRYPTO_ALG_INTERNAL), 237 CRYPTO_ALG_TYPE_MASK | 238 (algt->mask & CRYPTO_ALG_INTERNAL)); 239 err = PTR_ERR(alg); 240 if (IS_ERR(alg)) 241 goto err_free_inst; 242 243 spawn = skcipher_instance_ctx(inst); 244 err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst), 245 CRYPTO_ALG_TYPE_MASK); 246 crypto_mod_put(alg); 247 if (err) 248 goto err_free_inst; 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; 277 278 out: 279 return err; 280 281 err_drop_spawn: 282 crypto_drop_spawn(spawn); 283 err_free_inst: 284 kfree(inst); 285 goto out; 286 } 287 288 static struct crypto_template crypto_pcbc_tmpl = { 289 .name = "pcbc", 290 .create = crypto_pcbc_create, 291 .module = THIS_MODULE, 292 }; 293 294 static int __init crypto_pcbc_module_init(void) 295 { 296 return crypto_register_template(&crypto_pcbc_tmpl); 297 } 298 299 static void __exit crypto_pcbc_module_exit(void) 300 { 301 crypto_unregister_template(&crypto_pcbc_tmpl); 302 } 303 304 module_init(crypto_pcbc_module_init); 305 module_exit(crypto_pcbc_module_exit); 306 307 MODULE_LICENSE("GPL"); 308 MODULE_DESCRIPTION("PCBC block cipher algorithm"); 309 MODULE_ALIAS_CRYPTO("pcbc"); 310