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/aead.h> 17#include <crypto/internal/skcipher.h> 18#include <crypto/rng.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/spinlock.h> 25#include <linux/string.h> 26 27struct seqiv_ctx { 28 spinlock_t lock; 29 u8 salt[] __attribute__ ((aligned(__alignof__(u32)))); 30}; 31 32static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err) 33{ 34 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); 35 struct crypto_ablkcipher *geniv; 36 37 if (err == -EINPROGRESS) 38 return; 39 40 if (err) 41 goto out; 42 43 geniv = skcipher_givcrypt_reqtfm(req); 44 memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv)); 45 46out: 47 kfree(subreq->info); 48} 49 50static void seqiv_complete(struct crypto_async_request *base, int err) 51{ 52 struct skcipher_givcrypt_request *req = base->data; 53 54 seqiv_complete2(req, err); 55 skcipher_givcrypt_complete(req, err); 56} 57 58static void seqiv_aead_complete2(struct aead_givcrypt_request *req, int err) 59{ 60 struct aead_request *subreq = aead_givcrypt_reqctx(req); 61 struct crypto_aead *geniv; 62 63 if (err == -EINPROGRESS) 64 return; 65 66 if (err) 67 goto out; 68 69 geniv = aead_givcrypt_reqtfm(req); 70 memcpy(req->areq.iv, subreq->iv, crypto_aead_ivsize(geniv)); 71 72out: 73 kfree(subreq->iv); 74} 75 76static void seqiv_aead_complete(struct crypto_async_request *base, int err) 77{ 78 struct aead_givcrypt_request *req = base->data; 79 80 seqiv_aead_complete2(req, err); 81 aead_givcrypt_complete(req, err); 82} 83 84static void seqiv_geniv(struct seqiv_ctx *ctx, u8 *info, u64 seq, 85 unsigned int ivsize) 86{ 87 unsigned int len = ivsize; 88 89 if (ivsize > sizeof(u64)) { 90 memset(info, 0, ivsize - sizeof(u64)); 91 len = sizeof(u64); 92 } 93 seq = cpu_to_be64(seq); 94 memcpy(info + ivsize - len, &seq, len); 95 crypto_xor(info, ctx->salt, ivsize); 96} 97 98static int seqiv_givencrypt(struct skcipher_givcrypt_request *req) 99{ 100 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); 101 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 102 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); 103 crypto_completion_t complete; 104 void *data; 105 u8 *info; 106 unsigned int ivsize; 107 int err; 108 109 ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); 110 111 complete = req->creq.base.complete; 112 data = req->creq.base.data; 113 info = req->creq.info; 114 115 ivsize = crypto_ablkcipher_ivsize(geniv); 116 117 if (unlikely(!IS_ALIGNED((unsigned long)info, 118 crypto_ablkcipher_alignmask(geniv) + 1))) { 119 info = kmalloc(ivsize, req->creq.base.flags & 120 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: 121 GFP_ATOMIC); 122 if (!info) 123 return -ENOMEM; 124 125 complete = seqiv_complete; 126 data = req; 127 } 128 129 ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete, 130 data); 131 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst, 132 req->creq.nbytes, info); 133 134 seqiv_geniv(ctx, info, req->seq, ivsize); 135 memcpy(req->giv, info, ivsize); 136 137 err = crypto_ablkcipher_encrypt(subreq); 138 if (unlikely(info != req->creq.info)) 139 seqiv_complete2(req, err); 140 return err; 141} 142 143static int seqiv_aead_givencrypt(struct aead_givcrypt_request *req) 144{ 145 struct crypto_aead *geniv = aead_givcrypt_reqtfm(req); 146 struct seqiv_ctx *ctx = crypto_aead_ctx(geniv); 147 struct aead_request *areq = &req->areq; 148 struct aead_request *subreq = aead_givcrypt_reqctx(req); 149 crypto_completion_t complete; 150 void *data; 151 u8 *info; 152 unsigned int ivsize; 153 int err; 154 155 aead_request_set_tfm(subreq, aead_geniv_base(geniv)); 156 157 complete = areq->base.complete; 158 data = areq->base.data; 159 info = areq->iv; 160 161 ivsize = crypto_aead_ivsize(geniv); 162 163 if (unlikely(!IS_ALIGNED((unsigned long)info, 164 crypto_aead_alignmask(geniv) + 1))) { 165 info = kmalloc(ivsize, areq->base.flags & 166 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: 167 GFP_ATOMIC); 168 if (!info) 169 return -ENOMEM; 170 171 complete = seqiv_aead_complete; 172 data = req; 173 } 174 175 aead_request_set_callback(subreq, areq->base.flags, complete, data); 176 aead_request_set_crypt(subreq, areq->src, areq->dst, areq->cryptlen, 177 info); 178 aead_request_set_assoc(subreq, areq->assoc, areq->assoclen); 179 180 seqiv_geniv(ctx, info, req->seq, ivsize); 181 memcpy(req->giv, info, ivsize); 182 183 err = crypto_aead_encrypt(subreq); 184 if (unlikely(info != areq->iv)) 185 seqiv_aead_complete2(req, err); 186 return err; 187} 188 189static int seqiv_givencrypt_first(struct skcipher_givcrypt_request *req) 190{ 191 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); 192 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 193 int err = 0; 194 195 spin_lock_bh(&ctx->lock); 196 if (crypto_ablkcipher_crt(geniv)->givencrypt != seqiv_givencrypt_first) 197 goto unlock; 198 199 crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt; 200 err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt, 201 crypto_ablkcipher_ivsize(geniv)); 202 203unlock: 204 spin_unlock_bh(&ctx->lock); 205 206 if (err) 207 return err; 208 209 return seqiv_givencrypt(req); 210} 211 212static int seqiv_aead_givencrypt_first(struct aead_givcrypt_request *req) 213{ 214 struct crypto_aead *geniv = aead_givcrypt_reqtfm(req); 215 struct seqiv_ctx *ctx = crypto_aead_ctx(geniv); 216 int err = 0; 217 218 spin_lock_bh(&ctx->lock); 219 if (crypto_aead_crt(geniv)->givencrypt != seqiv_aead_givencrypt_first) 220 goto unlock; 221 222 crypto_aead_crt(geniv)->givencrypt = seqiv_aead_givencrypt; 223 err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt, 224 crypto_aead_ivsize(geniv)); 225 226unlock: 227 spin_unlock_bh(&ctx->lock); 228 229 if (err) 230 return err; 231 232 return seqiv_aead_givencrypt(req); 233} 234 235static int seqiv_init(struct crypto_tfm *tfm) 236{ 237 struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); 238 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 239 240 spin_lock_init(&ctx->lock); 241 242 tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); 243 244 return skcipher_geniv_init(tfm); 245} 246 247static int seqiv_aead_init(struct crypto_tfm *tfm) 248{ 249 struct crypto_aead *geniv = __crypto_aead_cast(tfm); 250 struct seqiv_ctx *ctx = crypto_aead_ctx(geniv); 251 252 spin_lock_init(&ctx->lock); 253 254 tfm->crt_aead.reqsize = sizeof(struct aead_request); 255 256 return aead_geniv_init(tfm); 257} 258 259static struct crypto_template seqiv_tmpl; 260 261static struct crypto_instance *seqiv_ablkcipher_alloc(struct rtattr **tb) 262{ 263 struct crypto_instance *inst; 264 265 inst = skcipher_geniv_alloc(&seqiv_tmpl, tb, 0, 0); 266 267 if (IS_ERR(inst)) 268 goto out; 269 270 inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first; 271 272 inst->alg.cra_init = seqiv_init; 273 inst->alg.cra_exit = skcipher_geniv_exit; 274 275 inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; 276 277out: 278 return inst; 279} 280 281static struct crypto_instance *seqiv_aead_alloc(struct rtattr **tb) 282{ 283 struct crypto_instance *inst; 284 285 inst = aead_geniv_alloc(&seqiv_tmpl, tb, 0, 0); 286 287 if (IS_ERR(inst)) 288 goto out; 289 290 inst->alg.cra_aead.givencrypt = seqiv_aead_givencrypt_first; 291 292 inst->alg.cra_init = seqiv_aead_init; 293 inst->alg.cra_exit = aead_geniv_exit; 294 295 inst->alg.cra_ctxsize = inst->alg.cra_aead.ivsize; 296 297out: 298 return inst; 299} 300 301static struct crypto_instance *seqiv_alloc(struct rtattr **tb) 302{ 303 struct crypto_attr_type *algt; 304 struct crypto_instance *inst; 305 int err; 306 307 algt = crypto_get_attr_type(tb); 308 err = PTR_ERR(algt); 309 if (IS_ERR(algt)) 310 return ERR_PTR(err); 311 312 err = crypto_get_default_rng(); 313 if (err) 314 return ERR_PTR(err); 315 316 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 317 inst = seqiv_ablkcipher_alloc(tb); 318 else 319 inst = seqiv_aead_alloc(tb); 320 321 if (IS_ERR(inst)) 322 goto put_rng; 323 324 inst->alg.cra_alignmask |= __alignof__(u32) - 1; 325 inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx); 326 327out: 328 return inst; 329 330put_rng: 331 crypto_put_default_rng(); 332 goto out; 333} 334 335static void seqiv_free(struct crypto_instance *inst) 336{ 337 if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 338 skcipher_geniv_free(inst); 339 else 340 aead_geniv_free(inst); 341 crypto_put_default_rng(); 342} 343 344static struct crypto_template seqiv_tmpl = { 345 .name = "seqiv", 346 .alloc = seqiv_alloc, 347 .free = seqiv_free, 348 .module = THIS_MODULE, 349}; 350 351static int __init seqiv_module_init(void) 352{ 353 return crypto_register_template(&seqiv_tmpl); 354} 355 356static void __exit seqiv_module_exit(void) 357{ 358 crypto_unregister_template(&seqiv_tmpl); 359} 360 361module_init(seqiv_module_init); 362module_exit(seqiv_module_exit); 363 364MODULE_LICENSE("GPL"); 365MODULE_DESCRIPTION("Sequence Number IV Generator"); 366