seqiv.c

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    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 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 
  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 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 
  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         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 
  327 out:
  328         return inst;
  329 
  330 put_rng:
  331         crypto_put_default_rng();
  332         goto out;
  333 }
  334 
  335 static 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 
  344 static struct crypto_template seqiv_tmpl = {
  345         .name = "seqiv",
  346         .alloc = seqiv_alloc,
  347         .free = seqiv_free,
  348         .module = THIS_MODULE,
  349 };
  350 
  351 static int __init seqiv_module_init(void)
  352 {
  353         return crypto_register_template(&seqiv_tmpl);
  354 }
  355 
  356 static void __exit seqiv_module_exit(void)
  357 {
  358         crypto_unregister_template(&seqiv_tmpl);
  359 }
  360 
  361 module_init(seqiv_module_init);
  362 module_exit(seqiv_module_exit);
  363 
  364 MODULE_LICENSE("GPL");
  365 MODULE_DESCRIPTION("Sequence Number IV Generator");
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FreeBSD/Linux Kernel Cross Reference sys/crypto/seqiv.c

FreeBSD/Linux Kernel Cross Reference
sys/crypto/seqiv.c
