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 memcpy(iv, dst, bsize); 59 crypto_xor(iv, 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[bsize]; 77 78 do { 79 memcpy(tmpbuf, src, bsize); 80 crypto_xor(iv, src, bsize); 81 crypto_cipher_encrypt_one(tfm, src, iv); 82 memcpy(iv, tmpbuf, bsize); 83 crypto_xor(iv, src, bsize); 84 85 src += bsize; 86 } while ((nbytes -= bsize) >= bsize); 87 88 memcpy(walk->iv, iv, bsize); 89 90 return nbytes; 91 } 92 93 static int crypto_pcbc_encrypt(struct skcipher_request *req) 94 { 95 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 96 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 97 struct crypto_cipher *child = ctx->child; 98 struct skcipher_walk walk; 99 unsigned int nbytes; 100 int err; 101 102 err = skcipher_walk_virt(&walk, req, false); 103 104 while ((nbytes = walk.nbytes)) { 105 if (walk.src.virt.addr == walk.dst.virt.addr) 106 nbytes = crypto_pcbc_encrypt_inplace(req, &walk, 107 child); 108 else 109 nbytes = crypto_pcbc_encrypt_segment(req, &walk, 110 child); 111 err = skcipher_walk_done(&walk, nbytes); 112 } 113 114 return err; 115 } 116 117 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req, 118 struct skcipher_walk *walk, 119 struct crypto_cipher *tfm) 120 { 121 int bsize = crypto_cipher_blocksize(tfm); 122 unsigned int nbytes = walk->nbytes; 123 u8 *src = walk->src.virt.addr; 124 u8 *dst = walk->dst.virt.addr; 125 u8 *iv = walk->iv; 126 127 do { 128 crypto_cipher_decrypt_one(tfm, dst, src); 129 crypto_xor(dst, iv, bsize); 130 memcpy(iv, src, bsize); 131 crypto_xor(iv, dst, bsize); 132 133 src += bsize; 134 dst += bsize; 135 } while ((nbytes -= bsize) >= bsize); 136 137 memcpy(walk->iv, iv, bsize); 138 139 return nbytes; 140 } 141 142 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req, 143 struct skcipher_walk *walk, 144 struct crypto_cipher *tfm) 145 { 146 int bsize = crypto_cipher_blocksize(tfm); 147 unsigned int nbytes = walk->nbytes; 148 u8 *src = walk->src.virt.addr; 149 u8 *iv = walk->iv; 150 u8 tmpbuf[bsize] __aligned(__alignof__(u32)); 151 152 do { 153 memcpy(tmpbuf, src, bsize); 154 crypto_cipher_decrypt_one(tfm, src, src); 155 crypto_xor(src, iv, bsize); 156 memcpy(iv, tmpbuf, bsize); 157 crypto_xor(iv, src, bsize); 158 159 src += bsize; 160 } while ((nbytes -= bsize) >= bsize); 161 162 memcpy(walk->iv, iv, bsize); 163 164 return nbytes; 165 } 166 167 static int crypto_pcbc_decrypt(struct skcipher_request *req) 168 { 169 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); 170 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 171 struct crypto_cipher *child = ctx->child; 172 struct skcipher_walk walk; 173 unsigned int nbytes; 174 int err; 175 176 err = skcipher_walk_virt(&walk, req, false); 177 178 while ((nbytes = walk.nbytes)) { 179 if (walk.src.virt.addr == walk.dst.virt.addr) 180 nbytes = crypto_pcbc_decrypt_inplace(req, &walk, 181 child); 182 else 183 nbytes = crypto_pcbc_decrypt_segment(req, &walk, 184 child); 185 err = skcipher_walk_done(&walk, nbytes); 186 } 187 188 return err; 189 } 190 191 static int crypto_pcbc_init_tfm(struct crypto_skcipher *tfm) 192 { 193 struct skcipher_instance *inst = skcipher_alg_instance(tfm); 194 struct crypto_spawn *spawn = skcipher_instance_ctx(inst); 195 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 196 struct crypto_cipher *cipher; 197 198 cipher = crypto_spawn_cipher(spawn); 199 if (IS_ERR(cipher)) 200 return PTR_ERR(cipher); 201 202 ctx->child = cipher; 203 return 0; 204 } 205 206 static void crypto_pcbc_exit_tfm(struct crypto_skcipher *tfm) 207 { 208 struct crypto_pcbc_ctx *ctx = crypto_skcipher_ctx(tfm); 209 210 crypto_free_cipher(ctx->child); 211 } 212 213 static void crypto_pcbc_free(struct skcipher_instance *inst) 214 { 215 crypto_drop_skcipher(skcipher_instance_ctx(inst)); 216 kfree(inst); 217 } 218 219 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb) 220 { 221 struct skcipher_instance *inst; 222 struct crypto_attr_type *algt; 223 struct crypto_spawn *spawn; 224 struct crypto_alg *alg; 225 int err; 226 227 algt = crypto_get_attr_type(tb); 228 if (IS_ERR(algt)) 229 return PTR_ERR(algt); 230 231 if (((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) & 232 ~CRYPTO_ALG_INTERNAL) 233 return -EINVAL; 234 235 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); 236 if (!inst) 237 return -ENOMEM; 238 239 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER | 240 (algt->type & CRYPTO_ALG_INTERNAL), 241 CRYPTO_ALG_TYPE_MASK | 242 (algt->mask & CRYPTO_ALG_INTERNAL)); 243 err = PTR_ERR(alg); 244 if (IS_ERR(alg)) 245 goto err_free_inst; 246 247 spawn = skcipher_instance_ctx(inst); 248 err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst), 249 CRYPTO_ALG_TYPE_MASK); 250 crypto_mod_put(alg); 251 if (err) 252 goto err_free_inst; 253 254 err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg); 255 if (err) 256 goto err_drop_spawn; 257 258 inst->alg.base.cra_flags = alg->cra_flags & CRYPTO_ALG_INTERNAL; 259 inst->alg.base.cra_priority = alg->cra_priority; 260 inst->alg.base.cra_blocksize = alg->cra_blocksize; 261 inst->alg.base.cra_alignmask = alg->cra_alignmask; 262 263 inst->alg.ivsize = alg->cra_blocksize; 264 inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize; 265 inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize; 266 267 inst->alg.base.cra_ctxsize = sizeof(struct crypto_pcbc_ctx); 268 269 inst->alg.init = crypto_pcbc_init_tfm; 270 inst->alg.exit = crypto_pcbc_exit_tfm; 271 272 inst->alg.setkey = crypto_pcbc_setkey; 273 inst->alg.encrypt = crypto_pcbc_encrypt; 274 inst->alg.decrypt = crypto_pcbc_decrypt; 275 276 inst->free = crypto_pcbc_free; 277 278 err = skcipher_register_instance(tmpl, inst); 279 if (err) 280 goto err_drop_spawn; 281 282 out: 283 return err; 284 285 err_drop_spawn: 286 crypto_drop_spawn(spawn); 287 err_free_inst: 288 kfree(inst); 289 goto out; 290 } 291 292 static struct crypto_template crypto_pcbc_tmpl = { 293 .name = "pcbc", 294 .create = crypto_pcbc_create, 295 .module = THIS_MODULE, 296 }; 297 298 static int __init crypto_pcbc_module_init(void) 299 { 300 return crypto_register_template(&crypto_pcbc_tmpl); 301 } 302 303 static void __exit crypto_pcbc_module_exit(void) 304 { 305 crypto_unregister_template(&crypto_pcbc_tmpl); 306 } 307 308 module_init(crypto_pcbc_module_init); 309 module_exit(crypto_pcbc_module_exit); 310 311 MODULE_LICENSE("GPL"); 312 MODULE_DESCRIPTION("PCBC block cipher algorithm"); 313 MODULE_ALIAS_CRYPTO("pcbc"); 314