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 27 struct seqiv_ctx { 28 spinlock_t lock; 29 u8 salt[] __attribute__ ((aligned(__alignof__(u32)))); 30 }; 31 32 static 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 46 out: 47 kfree(subreq->info); 48 } 49 50 static 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 58 static 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 72 out: 73 kfree(subreq->iv); 74 } 75 76 static 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 84 static 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 98 static 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 compl; 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 compl = 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 compl = seqiv_complete; 126 data = req; 127 } 128 129 ablkcipher_request_set_callback(subreq, req->creq.base.flags, compl, 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 } 142 143 static 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 compl; 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 compl = 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 compl = seqiv_aead_complete; 172 data = req; 173 } 174 175 aead_request_set_callback(subreq, areq->base.flags, compl, 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 } 188 189 static 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)); 202 203 unlock: 204 spin_unlock_bh(&ctx->lock); 205 206 if (err) 207 return err; 208 209 return seqiv_givencrypt(req); 210 } 211 212 static 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)); 225 226 unlock: 227 spin_unlock_bh(&ctx->lock); 228 229 if (err) 230 return err; 231 232 return seqiv_aead_givencrypt(req); 233 } 234 235 static 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 } 246 247 static 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 } 258 259 static struct crypto_template seqiv_tmpl; 260 261 static 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; 276 277 out: 278 return inst; 279 } 280 281 static 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; 296 297 out: 298 return inst; 299 } 300 301 static 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 if (IS_ERR(algt)) 309 return ERR_CAST(algt); 310 311 err = crypto_get_default_rng(); 312 if (err) 313 return ERR_PTR(err); 314 315 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 316 inst = seqiv_ablkcipher_alloc(tb); 317 else 318 inst = seqiv_aead_alloc(tb); 319 320 if (IS_ERR(inst)) 321 goto put_rng; 322 323 inst->alg.cra_alignmask |= __alignof__(u32) - 1; 324 inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx); 325 326 out: 327 return inst; 328 329 put_rng: 330 crypto_put_default_rng(); 331 goto out; 332 } 333 334 static void seqiv_free(struct crypto_instance *inst) 335 { 336 if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 337 skcipher_geniv_free(inst); 338 else 339 aead_geniv_free(inst); 340 crypto_put_default_rng(); 341 } 342 343 static struct crypto_template seqiv_tmpl = { 344 .name = "seqiv", 345 .alloc = seqiv_alloc, 346 .free = seqiv_free, 347 .module = THIS_MODULE, 348 }; 349 350 static int __init seqiv_module_init(void) 351 { 352 return crypto_register_template(&seqiv_tmpl); 353 } 354 355 static void __exit seqiv_module_exit(void) 356 { 357 crypto_unregister_template(&seqiv_tmpl); 358 } 359 360 module_init(seqiv_module_init); 361 module_exit(seqiv_module_exit); 362 363 MODULE_LICENSE("GPL"); 364 MODULE_DESCRIPTION("Sequence Number IV Generator"); 365 MODULE_ALIAS_CRYPTO("seqiv"); 366