2 * chainiv: Chain IV Generator
4 * Generate IVs simply be using the last block of the previous encryption.
5 * This is mainly useful for CBC with a synchronous algorithm.
7 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
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)
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>
28 CHAINIV_STATE_INUSE = 0,
36 struct async_chainiv_ctx {
42 struct crypto_queue queue;
43 struct work_struct postponed;
48 static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
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);
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,
61 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
62 req->creq.nbytes, req->creq.info);
64 spin_lock_bh(&ctx->lock);
66 ivsize = crypto_ablkcipher_ivsize(geniv);
68 memcpy(req->giv, ctx->iv, ivsize);
69 memcpy(subreq->info, ctx->iv, ivsize);
71 err = crypto_ablkcipher_encrypt(subreq);
75 memcpy(ctx->iv, subreq->info, ivsize);
78 spin_unlock_bh(&ctx->lock);
83 static int chainiv_init_common(struct crypto_tfm *tfm, char iv[])
85 struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
87 tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
89 return crypto_rng_get_bytes(crypto_default_rng, iv,
90 crypto_ablkcipher_ivsize(geniv)) ?:
91 skcipher_geniv_init(tfm);
94 static int chainiv_init(struct crypto_tfm *tfm)
96 struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
98 spin_lock_init(&ctx->lock);
100 return chainiv_init_common(tfm, ctx->iv);
103 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
108 if (!ctx->queue.qlen) {
109 smp_mb__before_atomic();
110 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
112 if (!ctx->queue.qlen ||
113 test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
117 queued = queue_work(kcrypto_wq, &ctx->postponed);
124 static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
126 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
127 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
130 spin_lock_bh(&ctx->lock);
131 err = skcipher_enqueue_givcrypt(&ctx->queue, req);
132 spin_unlock_bh(&ctx->lock);
134 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
138 return async_chainiv_schedule_work(ctx);
141 static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
143 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
144 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
145 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
146 unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
148 memcpy(req->giv, ctx->iv, ivsize);
149 memcpy(subreq->info, ctx->iv, ivsize);
151 ctx->err = crypto_ablkcipher_encrypt(subreq);
155 memcpy(ctx->iv, subreq->info, ivsize);
158 return async_chainiv_schedule_work(ctx);
161 static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
163 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
164 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
165 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
167 ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
168 ablkcipher_request_set_callback(subreq, req->creq.base.flags,
169 req->creq.base.complete,
170 req->creq.base.data);
171 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
172 req->creq.nbytes, req->creq.info);
174 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
177 if (ctx->queue.qlen) {
178 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
182 return async_chainiv_givencrypt_tail(req);
185 return async_chainiv_postpone_request(req);
188 static void async_chainiv_do_postponed(struct work_struct *work)
190 struct async_chainiv_ctx *ctx = container_of(work,
191 struct async_chainiv_ctx,
193 struct skcipher_givcrypt_request *req;
194 struct ablkcipher_request *subreq;
197 /* Only handle one request at a time to avoid hogging keventd. */
198 spin_lock_bh(&ctx->lock);
199 req = skcipher_dequeue_givcrypt(&ctx->queue);
200 spin_unlock_bh(&ctx->lock);
203 async_chainiv_schedule_work(ctx);
207 subreq = skcipher_givcrypt_reqctx(req);
208 subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
210 err = async_chainiv_givencrypt_tail(req);
213 skcipher_givcrypt_complete(req, err);
217 static int async_chainiv_init(struct crypto_tfm *tfm)
219 struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
221 spin_lock_init(&ctx->lock);
223 crypto_init_queue(&ctx->queue, 100);
224 INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
226 return chainiv_init_common(tfm, ctx->iv);
229 static void async_chainiv_exit(struct crypto_tfm *tfm)
231 struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
233 BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
235 skcipher_geniv_exit(tfm);
238 static struct crypto_template chainiv_tmpl;
240 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
242 struct crypto_attr_type *algt;
243 struct crypto_instance *inst;
246 algt = crypto_get_attr_type(tb);
248 return ERR_CAST(algt);
250 err = crypto_get_default_rng();
254 inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
258 inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt;
260 inst->alg.cra_init = chainiv_init;
261 inst->alg.cra_exit = skcipher_geniv_exit;
263 inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
265 if (!crypto_requires_sync(algt->type, algt->mask)) {
266 inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
268 inst->alg.cra_ablkcipher.givencrypt = async_chainiv_givencrypt;
270 inst->alg.cra_init = async_chainiv_init;
271 inst->alg.cra_exit = async_chainiv_exit;
273 inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
276 inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
282 crypto_put_default_rng();
286 static void chainiv_free(struct crypto_instance *inst)
288 skcipher_geniv_free(inst);
289 crypto_put_default_rng();
292 static struct crypto_template chainiv_tmpl = {
294 .alloc = chainiv_alloc,
295 .free = chainiv_free,
296 .module = THIS_MODULE,
299 static int __init chainiv_module_init(void)
301 return crypto_register_template(&chainiv_tmpl);
304 static void chainiv_module_exit(void)
306 crypto_unregister_template(&chainiv_tmpl);
309 module_init(chainiv_module_init);
310 module_exit(chainiv_module_exit);
312 MODULE_LICENSE("GPL");
313 MODULE_DESCRIPTION("Chain IV Generator");
314 MODULE_ALIAS_CRYPTO("chainiv");