1 /* 2 * seqiv: Sequence Number IV Generator 3 * 4 * This generator generates an IV based on a sequence number by xoring it 5 * with a salt. This algorithm is mainly useful for CTR and similar modes. 6 * 7 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License as published by the Free 11 * Software Foundation; either version 2 of the License, or (at your option) 12 * any later version. 13 * 14 */ 15 16 #include <crypto/internal/geniv.h> 17 #include <crypto/internal/skcipher.h> 18 #include <crypto/rng.h> 19 #include <crypto/scatterwalk.h> 20 #include <linux/err.h> 21 #include <linux/init.h> 22 #include <linux/kernel.h> 23 #include <linux/module.h> 24 #include <linux/slab.h> 25 #include <linux/spinlock.h> 26 #include <linux/string.h> 27 28 struct seqiv_ctx { 29 spinlock_t lock; 30 u8 salt[] __attribute__ ((aligned(__alignof__(u32)))); 31 }; 32 33 static void seqiv_free(struct crypto_instance *inst); 34 35 static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err) 36 { 37 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); 38 struct crypto_ablkcipher *geniv; 39 40 if (err == -EINPROGRESS) 41 return; 42 43 if (err) 44 goto out; 45 46 geniv = skcipher_givcrypt_reqtfm(req); 47 memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv)); 48 49 out: 50 kfree(subreq->info); 51 } 52 53 static void seqiv_complete(struct crypto_async_request *base, int err) 54 { 55 struct skcipher_givcrypt_request *req = base->data; 56 57 seqiv_complete2(req, err); 58 skcipher_givcrypt_complete(req, err); 59 } 60 61 static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err) 62 { 63 struct aead_request *subreq = aead_request_ctx(req); 64 struct crypto_aead *geniv; 65 66 if (err == -EINPROGRESS) 67 return; 68 69 if (err) 70 goto out; 71 72 geniv = crypto_aead_reqtfm(req); 73 memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv)); 74 75 out: 76 kzfree(subreq->iv); 77 } 78 79 static void seqiv_aead_encrypt_complete(struct crypto_async_request *base, 80 int err) 81 { 82 struct aead_request *req = base->data; 83 84 seqiv_aead_encrypt_complete2(req, err); 85 aead_request_complete(req, err); 86 } 87 88 static void seqiv_geniv(struct seqiv_ctx *ctx, u8 *info, u64 seq, 89 unsigned int ivsize) 90 { 91 unsigned int len = ivsize; 92 93 if (ivsize > sizeof(u64)) { 94 memset(info, 0, ivsize - sizeof(u64)); 95 len = sizeof(u64); 96 } 97 seq = cpu_to_be64(seq); 98 memcpy(info + ivsize - len, &seq, len); 99 crypto_xor(info, ctx->salt, ivsize); 100 } 101 102 static int seqiv_givencrypt(struct skcipher_givcrypt_request *req) 103 { 104 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); 105 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 106 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); 107 crypto_completion_t compl; 108 void *data; 109 u8 *info; 110 unsigned int ivsize; 111 int err; 112 113 ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); 114 115 compl = req->creq.base.complete; 116 data = req->creq.base.data; 117 info = req->creq.info; 118 119 ivsize = crypto_ablkcipher_ivsize(geniv); 120 121 if (unlikely(!IS_ALIGNED((unsigned long)info, 122 crypto_ablkcipher_alignmask(geniv) + 1))) { 123 info = kmalloc(ivsize, req->creq.base.flags & 124 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: 125 GFP_ATOMIC); 126 if (!info) 127 return -ENOMEM; 128 129 compl = seqiv_complete; 130 data = req; 131 } 132 133 ablkcipher_request_set_callback(subreq, req->creq.base.flags, compl, 134 data); 135 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst, 136 req->creq.nbytes, info); 137 138 seqiv_geniv(ctx, info, req->seq, ivsize); 139 memcpy(req->giv, info, ivsize); 140 141 err = crypto_ablkcipher_encrypt(subreq); 142 if (unlikely(info != req->creq.info)) 143 seqiv_complete2(req, err); 144 return err; 145 } 146 147 static int seqiv_aead_encrypt(struct aead_request *req) 148 { 149 struct crypto_aead *geniv = crypto_aead_reqtfm(req); 150 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); 151 struct aead_request *subreq = aead_request_ctx(req); 152 crypto_completion_t compl; 153 void *data; 154 u8 *info; 155 unsigned int ivsize = 8; 156 int err; 157 158 if (req->cryptlen < ivsize) 159 return -EINVAL; 160 161 aead_request_set_tfm(subreq, ctx->child); 162 163 compl = req->base.complete; 164 data = req->base.data; 165 info = req->iv; 166 167 if (req->src != req->dst) { 168 struct blkcipher_desc desc = { 169 .tfm = ctx->null, 170 }; 171 172 err = crypto_blkcipher_encrypt(&desc, req->dst, req->src, 173 req->assoclen + req->cryptlen); 174 if (err) 175 return err; 176 } 177 178 if (unlikely(!IS_ALIGNED((unsigned long)info, 179 crypto_aead_alignmask(geniv) + 1))) { 180 info = kmalloc(ivsize, req->base.flags & 181 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: 182 GFP_ATOMIC); 183 if (!info) 184 return -ENOMEM; 185 186 memcpy(info, req->iv, ivsize); 187 compl = seqiv_aead_encrypt_complete; 188 data = req; 189 } 190 191 aead_request_set_callback(subreq, req->base.flags, compl, data); 192 aead_request_set_crypt(subreq, req->dst, req->dst, 193 req->cryptlen - ivsize, info); 194 aead_request_set_ad(subreq, req->assoclen + ivsize); 195 196 crypto_xor(info, ctx->salt, ivsize); 197 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); 198 199 err = crypto_aead_encrypt(subreq); 200 if (unlikely(info != req->iv)) 201 seqiv_aead_encrypt_complete2(req, err); 202 return err; 203 } 204 205 static int seqiv_aead_decrypt(struct aead_request *req) 206 { 207 struct crypto_aead *geniv = crypto_aead_reqtfm(req); 208 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); 209 struct aead_request *subreq = aead_request_ctx(req); 210 crypto_completion_t compl; 211 void *data; 212 unsigned int ivsize = 8; 213 214 if (req->cryptlen < ivsize + crypto_aead_authsize(geniv)) 215 return -EINVAL; 216 217 aead_request_set_tfm(subreq, ctx->child); 218 219 compl = req->base.complete; 220 data = req->base.data; 221 222 aead_request_set_callback(subreq, req->base.flags, compl, data); 223 aead_request_set_crypt(subreq, req->src, req->dst, 224 req->cryptlen - ivsize, req->iv); 225 aead_request_set_ad(subreq, req->assoclen + ivsize); 226 227 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); 228 229 return crypto_aead_decrypt(subreq); 230 } 231 232 static int seqiv_init(struct crypto_tfm *tfm) 233 { 234 struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); 235 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 236 int err; 237 238 spin_lock_init(&ctx->lock); 239 240 tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); 241 242 err = 0; 243 if (!crypto_get_default_rng()) { 244 crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt; 245 err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt, 246 crypto_ablkcipher_ivsize(geniv)); 247 crypto_put_default_rng(); 248 } 249 250 return err ?: skcipher_geniv_init(tfm); 251 } 252 253 static int seqiv_ablkcipher_create(struct crypto_template *tmpl, 254 struct rtattr **tb) 255 { 256 struct crypto_instance *inst; 257 int err; 258 259 inst = skcipher_geniv_alloc(tmpl, tb, 0, 0); 260 261 if (IS_ERR(inst)) 262 return PTR_ERR(inst); 263 264 err = -EINVAL; 265 if (inst->alg.cra_ablkcipher.ivsize < sizeof(u64)) 266 goto free_inst; 267 268 inst->alg.cra_init = seqiv_init; 269 inst->alg.cra_exit = skcipher_geniv_exit; 270 271 inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; 272 inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx); 273 274 inst->alg.cra_alignmask |= __alignof__(u32) - 1; 275 276 err = crypto_register_instance(tmpl, inst); 277 if (err) 278 goto free_inst; 279 280 out: 281 return err; 282 283 free_inst: 284 skcipher_geniv_free(inst); 285 goto out; 286 } 287 288 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb) 289 { 290 struct aead_instance *inst; 291 struct crypto_aead_spawn *spawn; 292 struct aead_alg *alg; 293 int err; 294 295 inst = aead_geniv_alloc(tmpl, tb, 0, 0); 296 297 if (IS_ERR(inst)) 298 return PTR_ERR(inst); 299 300 inst->alg.base.cra_alignmask |= __alignof__(u32) - 1; 301 302 spawn = aead_instance_ctx(inst); 303 alg = crypto_spawn_aead_alg(spawn); 304 305 err = -EINVAL; 306 if (inst->alg.ivsize != sizeof(u64)) 307 goto free_inst; 308 309 inst->alg.encrypt = seqiv_aead_encrypt; 310 inst->alg.decrypt = seqiv_aead_decrypt; 311 312 inst->alg.init = aead_init_geniv; 313 inst->alg.exit = aead_exit_geniv; 314 315 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx); 316 inst->alg.base.cra_ctxsize += inst->alg.ivsize; 317 318 err = aead_register_instance(tmpl, inst); 319 if (err) 320 goto free_inst; 321 322 out: 323 return err; 324 325 free_inst: 326 aead_geniv_free(inst); 327 goto out; 328 } 329 330 static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb) 331 { 332 struct crypto_attr_type *algt; 333 int err; 334 335 algt = crypto_get_attr_type(tb); 336 if (IS_ERR(algt)) 337 return PTR_ERR(algt); 338 339 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 340 err = seqiv_ablkcipher_create(tmpl, tb); 341 else 342 err = seqiv_aead_create(tmpl, tb); 343 344 return err; 345 } 346 347 static void seqiv_free(struct crypto_instance *inst) 348 { 349 if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 350 skcipher_geniv_free(inst); 351 else 352 aead_geniv_free(aead_instance(inst)); 353 } 354 355 static struct crypto_template seqiv_tmpl = { 356 .name = "seqiv", 357 .create = seqiv_create, 358 .free = seqiv_free, 359 .module = THIS_MODULE, 360 }; 361 362 static int __init seqiv_module_init(void) 363 { 364 return crypto_register_template(&seqiv_tmpl); 365 } 366 367 static void __exit seqiv_module_exit(void) 368 { 369 crypto_unregister_template(&seqiv_tmpl); 370 } 371 372 module_init(seqiv_module_init); 373 module_exit(seqiv_module_exit); 374 375 MODULE_LICENSE("GPL"); 376 MODULE_DESCRIPTION("Sequence Number IV Generator"); 377 MODULE_ALIAS_CRYPTO("seqiv"); 378