crypto/chainiv.c

   1 /*
   2  * chainiv: Chain IV Generator
   3  *
   4  * Generate IVs simply be using the last block of the previous encryption.
   5  * This is mainly useful for CBC with a synchronous algorithm.
   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/skcipher.h>
  17 #include <linux/err.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/random.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/string.h>
  24 #include <linux/workqueue.h>
  25
  26 enum {
  27         CHAINIV_STATE_INUSE = 0,
  28 };
  29
  30 struct chainiv_ctx {
  31         spinlock_t lock;
  32         char iv[];
  33 };
  34
  35 struct async_chainiv_ctx {
  36         unsigned long state;
  37
  38         spinlock_t lock;
  39         int err;
  40
  41         struct crypto_queue queue;
  42         struct work_struct postponed;
  43
  44         char iv[];
  45 };
  46
  47 static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
  48 {
  49         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
  50         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
  51         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
  52         unsigned int ivsize;
  53         int err;
  54
  55         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
  56         ablkcipher_request_set_callback(subreq, req->creq.base.flags &
  57                                                 ~CRYPTO_TFM_REQ_MAY_SLEEP,
  58                                         req->creq.base.complete,
  59                                         req->creq.base.data);
  60         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
  61                                      req->creq.nbytes, req->creq.info);
  62
  63         spin_lock_bh(&ctx->lock);
  64
  65         ivsize = crypto_ablkcipher_ivsize(geniv);
  66
  67         memcpy(req->giv, ctx->iv, ivsize);
  68         memcpy(subreq->info, ctx->iv, ivsize);
  69
  70         err = crypto_ablkcipher_encrypt(subreq);
  71         if (err)
  72                 goto unlock;
  73
  74         memcpy(ctx->iv, subreq->info, ivsize);
  75
  76 unlock:
  77         spin_unlock_bh(&ctx->lock);
  78
  79         return err;
  80 }
  81
  82 static int chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
  83 {
  84         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
  85         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
  86
  87         spin_lock_bh(&ctx->lock);
  88         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
  89             chainiv_givencrypt_first)
  90                 goto unlock;
  91
  92         crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
  93         get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv));
  94
  95 unlock:
  96         spin_unlock_bh(&ctx->lock);
  97
  98         return chainiv_givencrypt(req);
  99 }
 100
 101 static int chainiv_init_common(struct crypto_tfm *tfm)
 102 {
 103         tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
 104
 105         return skcipher_geniv_init(tfm);
 106 }
 107
 108 static int chainiv_init(struct crypto_tfm *tfm)
 109 {
 110         struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 111
 112         spin_lock_init(&ctx->lock);
 113
 114         return chainiv_init_common(tfm);
 115 }
 116
 117 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
 118 {
 119         int queued;
 120
 121         if (!ctx->queue.qlen) {
 122                 smp_mb__before_clear_bit();
 123                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 124
 125                 if (!ctx->queue.qlen ||
 126                     test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 127                         goto out;
 128         }
 129
 130         queued = schedule_work(&ctx->postponed);
 131         BUG_ON(!queued);
 132
 133 out:
 134         return ctx->err;
 135 }
 136
 137 static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
 138 {
 139         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 140         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 141         int err;
 142
 143         spin_lock_bh(&ctx->lock);
 144         err = skcipher_enqueue_givcrypt(&ctx->queue, req);
 145         spin_unlock_bh(&ctx->lock);
 146
 147         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 148                 return err;
 149
 150         ctx->err = err;
 151         return async_chainiv_schedule_work(ctx);
 152 }
 153
 154 static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
 155 {
 156         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 157         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 158         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 159         unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
 160
 161         memcpy(req->giv, ctx->iv, ivsize);
 162         memcpy(subreq->info, ctx->iv, ivsize);
 163
 164         ctx->err = crypto_ablkcipher_encrypt(subreq);
 165         if (ctx->err)
 166                 goto out;
 167
 168         memcpy(ctx->iv, subreq->info, ivsize);
 169
 170 out:
 171         return async_chainiv_schedule_work(ctx);
 172 }
 173
 174 static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
 175 {
 176         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 177         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 178         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
 179
 180         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
 181         ablkcipher_request_set_callback(subreq, req->creq.base.flags,
 182                                         req->creq.base.complete,
 183                                         req->creq.base.data);
 184         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
 185                                      req->creq.nbytes, req->creq.info);
 186
 187         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 188                 goto postpone;
 189
 190         if (ctx->queue.qlen) {
 191                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 192                 goto postpone;
 193         }
 194
 195         return async_chainiv_givencrypt_tail(req);
 196
 197 postpone:
 198         return async_chainiv_postpone_request(req);
 199 }
 200
 201 static int async_chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
 202 {
 203         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 204         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 205
 206         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
 207                 goto out;
 208
 209         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
 210             async_chainiv_givencrypt_first)
 211                 goto unlock;
 212
 213         crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt;
 214         get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv));
 215
 216 unlock:
 217         clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
 218
 219 out:
 220         return async_chainiv_givencrypt(req);
 221 }
 222
 223 static void async_chainiv_do_postponed(struct work_struct *work)
 224 {
 225         struct async_chainiv_ctx *ctx = container_of(work,
 226                                                      struct async_chainiv_ctx,
 227                                                      postponed);
 228         struct skcipher_givcrypt_request *req;
 229         struct ablkcipher_request *subreq;
 230
 231         /* Only handle one request at a time to avoid hogging keventd. */
 232         spin_lock_bh(&ctx->lock);
 233         req = skcipher_dequeue_givcrypt(&ctx->queue);
 234         spin_unlock_bh(&ctx->lock);
 235
 236         if (!req) {
 237                 async_chainiv_schedule_work(ctx);
 238                 return;
 239         }
 240
 241         subreq = skcipher_givcrypt_reqctx(req);
 242         subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
 243
 244         async_chainiv_givencrypt_tail(req);
 245 }
 246
 247 static int async_chainiv_init(struct crypto_tfm *tfm)
 248 {
 249         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 250
 251         spin_lock_init(&ctx->lock);
 252
 253         crypto_init_queue(&ctx->queue, 100);
 254         INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
 255
 256         return chainiv_init_common(tfm);
 257 }
 258
 259 static void async_chainiv_exit(struct crypto_tfm *tfm)
 260 {
 261         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 262
 263         BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
 264
 265         skcipher_geniv_exit(tfm);
 266 }
 267
 268 static struct crypto_template chainiv_tmpl;
 269
 270 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
 271 {
 272         struct crypto_attr_type *algt;
 273         struct crypto_instance *inst;
 274         int err;
 275
 276         algt = crypto_get_attr_type(tb);
 277         err = PTR_ERR(algt);
 278         if (IS_ERR(algt))
 279                 return ERR_PTR(err);
 280
 281         inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
 282         if (IS_ERR(inst))
 283                 goto out;
 284
 285         inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first;
 286
 287         inst->alg.cra_init = chainiv_init;
 288         inst->alg.cra_exit = skcipher_geniv_exit;
 289
 290         inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
 291
 292         if (!crypto_requires_sync(algt->type, algt->mask)) {
 293                 inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
 294
 295                 inst->alg.cra_ablkcipher.givencrypt =
 296                         async_chainiv_givencrypt_first;
 297
 298                 inst->alg.cra_init = async_chainiv_init;
 299                 inst->alg.cra_exit = async_chainiv_exit;
 300
 301                 inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
 302         }
 303
 304         inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
 305
 306 out:
 307         return inst;
 308 }
 309
 310 static struct crypto_template chainiv_tmpl = {
 311         .name = "chainiv",
 312         .alloc = chainiv_alloc,
 313         .free = skcipher_geniv_free,
 314         .module = THIS_MODULE,
 315 };
 316
 317 static int __init chainiv_module_init(void)
 318 {
 319         return crypto_register_template(&chainiv_tmpl);
 320 }
 321
 322 static void __exit chainiv_module_exit(void)
 323 {
 324         crypto_unregister_template(&chainiv_tmpl);
 325 }
 326
 327 module_init(chainiv_module_init);
 328 module_exit(chainiv_module_exit);
 329
 330 MODULE_LICENSE("GPL");
 331 MODULE_DESCRIPTION("Chain IV Generator");