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 <crypto/rng.h>
  18 #include <crypto/crypto_wq.h>
  19 #include <linux/err.h>
  20 #include <linux/init.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/string.h>
  25 #include <linux/workqueue.h>
  26
  27 enum {
  28         CHAINIV_STATE_INUSE = 0,
  29 };
  30
  31 struct chainiv_ctx {
  32         spinlock_t lock;
  33         char iv[];
  34 };
  35
  36 struct async_chainiv_ctx {
  37         unsigned long state;
  38
  39         spinlock_t lock;
  40         int err;
  41
  42         struct crypto_queue queue;
  43         struct work_struct postponed;
  44
  45         char iv[];
  46 };
  47
  48 static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
  49 {
  50         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
  51         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
  52         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
  53         unsigned int ivsize;
  54         int err;
  55
  56         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
  57         ablkcipher_request_set_callback(subreq, req->creq.base.flags &
  58                                                 ~CRYPTO_TFM_REQ_MAY_SLEEP,
  59                                         req->creq.base.complete,
  60                                         req->creq.base.data);
  61         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
  62                                      req->creq.nbytes, req->creq.info);
  63
  64         spin_lock_bh(&ctx->lock);
  65
  66         ivsize = crypto_ablkcipher_ivsize(geniv);
  67
  68         memcpy(req->giv, ctx->iv, ivsize);
  69         memcpy(subreq->info, ctx->iv, ivsize);
  70
  71         err = crypto_ablkcipher_encrypt(subreq);
  72         if (err)
  73                 goto unlock;
  74
  75         memcpy(ctx->iv, subreq->info, ivsize);
  76
  77 unlock:
  78         spin_unlock_bh(&ctx->lock);
  79
  80         return err;
  81 }
  82
  83 static int chainiv_init_common(struct crypto_tfm *tfm, char iv[])
  84 {
  85         struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
  86         int err = 0;
  87
  88         tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
  89
  90         if (iv) {
  91                 err = crypto_rng_get_bytes(crypto_default_rng, iv,
  92                                            crypto_ablkcipher_ivsize(geniv));
  93                 crypto_put_default_rng();
  94         }
  95
  96         return err ?: skcipher_geniv_init(tfm);
  97 }
  98
  99 static int chainiv_init(struct crypto_tfm *tfm)
 100 {
 101         struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
 102         struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 103         char *iv;
 104
 105         spin_lock_init(&ctx->lock);
 106
 107         iv = NULL;
 108         if (!crypto_get_default_rng()) {
 109                 crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
 110                 iv = ctx->iv;
 111         }
 112
 113         return chainiv_init_common(tfm, iv);
 114 }
 115
 116 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
 117 {
 118         int queued;
 119         int err = ctx->err;
 120
 121         if (!ctx->queue.qlen) {
 122                 smp_mb__before_atomic();
 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 = queue_work(kcrypto_wq, &ctx->postponed);
 131         BUG_ON(!queued);
 132
 133 out:
 134         return 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 void async_chainiv_do_postponed(struct work_struct *work)
 202 {
 203         struct async_chainiv_ctx *ctx = container_of(work,
 204                                                      struct async_chainiv_ctx,
 205                                                      postponed);
 206         struct skcipher_givcrypt_request *req;
 207         struct ablkcipher_request *subreq;
 208         int err;
 209
 210         /* Only handle one request at a time to avoid hogging keventd. */
 211         spin_lock_bh(&ctx->lock);
 212         req = skcipher_dequeue_givcrypt(&ctx->queue);
 213         spin_unlock_bh(&ctx->lock);
 214
 215         if (!req) {
 216                 async_chainiv_schedule_work(ctx);
 217                 return;
 218         }
 219
 220         subreq = skcipher_givcrypt_reqctx(req);
 221         subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
 222
 223         err = async_chainiv_givencrypt_tail(req);
 224
 225         local_bh_disable();
 226         skcipher_givcrypt_complete(req, err);
 227         local_bh_enable();
 228 }
 229
 230 static int async_chainiv_init(struct crypto_tfm *tfm)
 231 {
 232         struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
 233         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 234         char *iv;
 235
 236         spin_lock_init(&ctx->lock);
 237
 238         crypto_init_queue(&ctx->queue, 100);
 239         INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
 240
 241         iv = NULL;
 242         if (!crypto_get_default_rng()) {
 243                 crypto_ablkcipher_crt(geniv)->givencrypt =
 244                         async_chainiv_givencrypt;
 245                 iv = ctx->iv;
 246         }
 247
 248         return chainiv_init_common(tfm, iv);
 249 }
 250
 251 static void async_chainiv_exit(struct crypto_tfm *tfm)
 252 {
 253         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
 254
 255         BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
 256
 257         skcipher_geniv_exit(tfm);
 258 }
 259
 260 static struct crypto_template chainiv_tmpl;
 261
 262 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
 263 {
 264         struct crypto_attr_type *algt;
 265         struct crypto_instance *inst;
 266
 267         algt = crypto_get_attr_type(tb);
 268         if (IS_ERR(algt))
 269                 return ERR_CAST(algt);
 270
 271         inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
 272         if (IS_ERR(inst))
 273                 goto out;
 274
 275         inst->alg.cra_init = chainiv_init;
 276         inst->alg.cra_exit = skcipher_geniv_exit;
 277
 278         inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
 279
 280         if (!crypto_requires_sync(algt->type, algt->mask)) {
 281                 inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
 282
 283                 inst->alg.cra_init = async_chainiv_init;
 284                 inst->alg.cra_exit = async_chainiv_exit;
 285
 286                 inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
 287         }
 288
 289         inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
 290
 291 out:
 292         return inst;
 293 }
 294
 295 static struct crypto_template chainiv_tmpl = {
 296         .name = "chainiv",
 297         .alloc = chainiv_alloc,
 298         .free = skcipher_geniv_free,
 299         .module = THIS_MODULE,
 300 };
 301
 302 static int __init chainiv_module_init(void)
 303 {
 304         return crypto_register_template(&chainiv_tmpl);
 305 }
 306
 307 static void chainiv_module_exit(void)
 308 {
 309         crypto_unregister_template(&chainiv_tmpl);
 310 }
 311
 312 module_init(chainiv_module_init);
 313 module_exit(chainiv_module_exit);
 314
 315 MODULE_LICENSE("GPL");
 316 MODULE_DESCRIPTION("Chain IV Generator");
 317 MODULE_ALIAS_CRYPTO("chainiv");