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 <linux/err.h> 19 #include <linux/init.h> 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 #include <linux/random.h> 23 #include <linux/spinlock.h> 24 #include <linux/string.h> 25 26 struct seqiv_ctx { 27 spinlock_t lock; 28 u8 salt[] __attribute__ ((aligned(__alignof__(u32)))); 29 }; 30 31 static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err) 32 { 33 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); 34 struct crypto_ablkcipher *geniv; 35 36 if (err == -EINPROGRESS) 37 return; 38 39 if (err) 40 goto out; 41 42 geniv = skcipher_givcrypt_reqtfm(req); 43 memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv)); 44 45 out: 46 kfree(subreq->info); 47 } 48 49 static void seqiv_complete(struct crypto_async_request *base, int err) 50 { 51 struct skcipher_givcrypt_request *req = base->data; 52 53 seqiv_complete2(req, err); 54 skcipher_givcrypt_complete(req, err); 55 } 56 57 static void seqiv_aead_complete2(struct aead_givcrypt_request *req, int err) 58 { 59 struct aead_request *subreq = aead_givcrypt_reqctx(req); 60 struct crypto_aead *geniv; 61 62 if (err == -EINPROGRESS) 63 return; 64 65 if (err) 66 goto out; 67 68 geniv = aead_givcrypt_reqtfm(req); 69 memcpy(req->areq.iv, subreq->iv, crypto_aead_ivsize(geniv)); 70 71 out: 72 kfree(subreq->iv); 73 } 74 75 static void seqiv_aead_complete(struct crypto_async_request *base, int err) 76 { 77 struct aead_givcrypt_request *req = base->data; 78 79 seqiv_aead_complete2(req, err); 80 aead_givcrypt_complete(req, err); 81 } 82 83 static void seqiv_geniv(struct seqiv_ctx *ctx, u8 *info, u64 seq, 84 unsigned int ivsize) 85 { 86 unsigned int len = ivsize; 87 88 if (ivsize > sizeof(u64)) { 89 memset(info, 0, ivsize - sizeof(u64)); 90 len = sizeof(u64); 91 } 92 seq = cpu_to_be64(seq); 93 memcpy(info + ivsize - len, &seq, len); 94 crypto_xor(info, ctx->salt, ivsize); 95 } 96 97 static int seqiv_givencrypt(struct skcipher_givcrypt_request *req) 98 { 99 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); 100 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 101 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); 102 crypto_completion_t complete; 103 void *data; 104 u8 *info; 105 unsigned int ivsize; 106 int err; 107 108 ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); 109 110 complete = req->creq.base.complete; 111 data = req->creq.base.data; 112 info = req->creq.info; 113 114 ivsize = crypto_ablkcipher_ivsize(geniv); 115 116 if (unlikely(!IS_ALIGNED((unsigned long)info, 117 crypto_ablkcipher_alignmask(geniv) + 1))) { 118 info = kmalloc(ivsize, req->creq.base.flags & 119 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: 120 GFP_ATOMIC); 121 if (!info) 122 return -ENOMEM; 123 124 complete = seqiv_complete; 125 data = req; 126 } 127 128 ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete, 129 data); 130 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst, 131 req->creq.nbytes, info); 132 133 seqiv_geniv(ctx, info, req->seq, ivsize); 134 memcpy(req->giv, info, ivsize); 135 136 err = crypto_ablkcipher_encrypt(subreq); 137 if (unlikely(info != req->creq.info)) 138 seqiv_complete2(req, err); 139 return err; 140 } 141 142 static int seqiv_aead_givencrypt(struct aead_givcrypt_request *req) 143 { 144 struct crypto_aead *geniv = aead_givcrypt_reqtfm(req); 145 struct seqiv_ctx *ctx = crypto_aead_ctx(geniv); 146 struct aead_request *areq = &req->areq; 147 struct aead_request *subreq = aead_givcrypt_reqctx(req); 148 crypto_completion_t complete; 149 void *data; 150 u8 *info; 151 unsigned int ivsize; 152 int err; 153 154 aead_request_set_tfm(subreq, aead_geniv_base(geniv)); 155 156 complete = areq->base.complete; 157 data = areq->base.data; 158 info = areq->iv; 159 160 ivsize = crypto_aead_ivsize(geniv); 161 162 if (unlikely(!IS_ALIGNED((unsigned long)info, 163 crypto_aead_alignmask(geniv) + 1))) { 164 info = kmalloc(ivsize, areq->base.flags & 165 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: 166 GFP_ATOMIC); 167 if (!info) 168 return -ENOMEM; 169 170 complete = seqiv_aead_complete; 171 data = req; 172 } 173 174 aead_request_set_callback(subreq, areq->base.flags, complete, data); 175 aead_request_set_crypt(subreq, areq->src, areq->dst, areq->cryptlen, 176 info); 177 aead_request_set_assoc(subreq, areq->assoc, areq->assoclen); 178 179 seqiv_geniv(ctx, info, req->seq, ivsize); 180 memcpy(req->giv, info, ivsize); 181 182 err = crypto_aead_encrypt(subreq); 183 if (unlikely(info != areq->iv)) 184 seqiv_aead_complete2(req, err); 185 return err; 186 } 187 188 static int seqiv_givencrypt_first(struct skcipher_givcrypt_request *req) 189 { 190 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); 191 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 192 193 spin_lock_bh(&ctx->lock); 194 if (crypto_ablkcipher_crt(geniv)->givencrypt != seqiv_givencrypt_first) 195 goto unlock; 196 197 crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt; 198 get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv)); 199 200 unlock: 201 spin_unlock_bh(&ctx->lock); 202 203 return seqiv_givencrypt(req); 204 } 205 206 static int seqiv_aead_givencrypt_first(struct aead_givcrypt_request *req) 207 { 208 struct crypto_aead *geniv = aead_givcrypt_reqtfm(req); 209 struct seqiv_ctx *ctx = crypto_aead_ctx(geniv); 210 211 spin_lock_bh(&ctx->lock); 212 if (crypto_aead_crt(geniv)->givencrypt != seqiv_aead_givencrypt_first) 213 goto unlock; 214 215 crypto_aead_crt(geniv)->givencrypt = seqiv_aead_givencrypt; 216 get_random_bytes(ctx->salt, crypto_aead_ivsize(geniv)); 217 218 unlock: 219 spin_unlock_bh(&ctx->lock); 220 221 return seqiv_aead_givencrypt(req); 222 } 223 224 static int seqiv_init(struct crypto_tfm *tfm) 225 { 226 struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); 227 struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); 228 229 spin_lock_init(&ctx->lock); 230 231 tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); 232 233 return skcipher_geniv_init(tfm); 234 } 235 236 static int seqiv_aead_init(struct crypto_tfm *tfm) 237 { 238 struct crypto_aead *geniv = __crypto_aead_cast(tfm); 239 struct seqiv_ctx *ctx = crypto_aead_ctx(geniv); 240 241 spin_lock_init(&ctx->lock); 242 243 tfm->crt_aead.reqsize = sizeof(struct aead_request); 244 245 return aead_geniv_init(tfm); 246 } 247 248 static struct crypto_template seqiv_tmpl; 249 250 static struct crypto_instance *seqiv_ablkcipher_alloc(struct rtattr **tb) 251 { 252 struct crypto_instance *inst; 253 254 inst = skcipher_geniv_alloc(&seqiv_tmpl, tb, 0, 0); 255 256 if (IS_ERR(inst)) 257 goto out; 258 259 inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first; 260 261 inst->alg.cra_init = seqiv_init; 262 inst->alg.cra_exit = skcipher_geniv_exit; 263 264 inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; 265 266 out: 267 return inst; 268 } 269 270 static struct crypto_instance *seqiv_aead_alloc(struct rtattr **tb) 271 { 272 struct crypto_instance *inst; 273 274 inst = aead_geniv_alloc(&seqiv_tmpl, tb, 0, 0); 275 276 if (IS_ERR(inst)) 277 goto out; 278 279 inst->alg.cra_aead.givencrypt = seqiv_aead_givencrypt_first; 280 281 inst->alg.cra_init = seqiv_aead_init; 282 inst->alg.cra_exit = aead_geniv_exit; 283 284 inst->alg.cra_ctxsize = inst->alg.cra_aead.ivsize; 285 286 out: 287 return inst; 288 } 289 290 static struct crypto_instance *seqiv_alloc(struct rtattr **tb) 291 { 292 struct crypto_attr_type *algt; 293 struct crypto_instance *inst; 294 int err; 295 296 algt = crypto_get_attr_type(tb); 297 err = PTR_ERR(algt); 298 if (IS_ERR(algt)) 299 return ERR_PTR(err); 300 301 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 302 inst = seqiv_ablkcipher_alloc(tb); 303 else 304 inst = seqiv_aead_alloc(tb); 305 306 if (IS_ERR(inst)) 307 goto out; 308 309 inst->alg.cra_alignmask |= __alignof__(u32) - 1; 310 inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx); 311 312 out: 313 return inst; 314 } 315 316 static void seqiv_free(struct crypto_instance *inst) 317 { 318 if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 319 skcipher_geniv_free(inst); 320 else 321 aead_geniv_free(inst); 322 } 323 324 static struct crypto_template seqiv_tmpl = { 325 .name = "seqiv", 326 .alloc = seqiv_alloc, 327 .free = seqiv_free, 328 .module = THIS_MODULE, 329 }; 330 331 static int __init seqiv_module_init(void) 332 { 333 return crypto_register_template(&seqiv_tmpl); 334 } 335 336 static void __exit seqiv_module_exit(void) 337 { 338 crypto_unregister_template(&seqiv_tmpl); 339 } 340 341 module_init(seqiv_module_init); 342 module_exit(seqiv_module_exit); 343 344 MODULE_LICENSE("GPL"); 345 MODULE_DESCRIPTION("Sequence Number IV Generator"); 346