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TOMOYO Linux Cross Reference
Linux/crypto/chainiv.c

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  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_givencrypt_first(struct skcipher_givcrypt_request *req)
 84 {
 85         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 86         struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 87         int err = 0;
 88 
 89         spin_lock_bh(&ctx->lock);
 90         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
 91             chainiv_givencrypt_first)
 92                 goto unlock;
 93 
 94         crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
 95         err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
 96                                    crypto_ablkcipher_ivsize(geniv));
 97 
 98 unlock:
 99         spin_unlock_bh(&ctx->lock);
100 
101         if (err)
102                 return err;
103 
104         return chainiv_givencrypt(req);
105 }
106 
107 static int chainiv_init_common(struct crypto_tfm *tfm)
108 {
109         tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
110 
111         return skcipher_geniv_init(tfm);
112 }
113 
114 static int chainiv_init(struct crypto_tfm *tfm)
115 {
116         struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
117 
118         spin_lock_init(&ctx->lock);
119 
120         return chainiv_init_common(tfm);
121 }
122 
123 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
124 {
125         int queued;
126         int err = ctx->err;
127 
128         if (!ctx->queue.qlen) {
129                 smp_mb__before_clear_bit();
130                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
131 
132                 if (!ctx->queue.qlen ||
133                     test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
134                         goto out;
135         }
136 
137         queued = queue_work(kcrypto_wq, &ctx->postponed);
138         BUG_ON(!queued);
139 
140 out:
141         return err;
142 }
143 
144 static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
145 {
146         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
147         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
148         int err;
149 
150         spin_lock_bh(&ctx->lock);
151         err = skcipher_enqueue_givcrypt(&ctx->queue, req);
152         spin_unlock_bh(&ctx->lock);
153 
154         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
155                 return err;
156 
157         ctx->err = err;
158         return async_chainiv_schedule_work(ctx);
159 }
160 
161 static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
162 {
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);
166         unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
167 
168         memcpy(req->giv, ctx->iv, ivsize);
169         memcpy(subreq->info, ctx->iv, ivsize);
170 
171         ctx->err = crypto_ablkcipher_encrypt(subreq);
172         if (ctx->err)
173                 goto out;
174 
175         memcpy(ctx->iv, subreq->info, ivsize);
176 
177 out:
178         return async_chainiv_schedule_work(ctx);
179 }
180 
181 static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
182 {
183         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
184         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
185         struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
186 
187         ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
188         ablkcipher_request_set_callback(subreq, req->creq.base.flags,
189                                         req->creq.base.complete,
190                                         req->creq.base.data);
191         ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
192                                      req->creq.nbytes, req->creq.info);
193 
194         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
195                 goto postpone;
196 
197         if (ctx->queue.qlen) {
198                 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
199                 goto postpone;
200         }
201 
202         return async_chainiv_givencrypt_tail(req);
203 
204 postpone:
205         return async_chainiv_postpone_request(req);
206 }
207 
208 static int async_chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
209 {
210         struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
211         struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
212         int err = 0;
213 
214         if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
215                 goto out;
216 
217         if (crypto_ablkcipher_crt(geniv)->givencrypt !=
218             async_chainiv_givencrypt_first)
219                 goto unlock;
220 
221         crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt;
222         err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
223                                    crypto_ablkcipher_ivsize(geniv));
224 
225 unlock:
226         clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
227 
228         if (err)
229                 return err;
230 
231 out:
232         return async_chainiv_givencrypt(req);
233 }
234 
235 static void async_chainiv_do_postponed(struct work_struct *work)
236 {
237         struct async_chainiv_ctx *ctx = container_of(work,
238                                                      struct async_chainiv_ctx,
239                                                      postponed);
240         struct skcipher_givcrypt_request *req;
241         struct ablkcipher_request *subreq;
242         int err;
243 
244         /* Only handle one request at a time to avoid hogging keventd. */
245         spin_lock_bh(&ctx->lock);
246         req = skcipher_dequeue_givcrypt(&ctx->queue);
247         spin_unlock_bh(&ctx->lock);
248 
249         if (!req) {
250                 async_chainiv_schedule_work(ctx);
251                 return;
252         }
253 
254         subreq = skcipher_givcrypt_reqctx(req);
255         subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
256 
257         err = async_chainiv_givencrypt_tail(req);
258 
259         local_bh_disable();
260         skcipher_givcrypt_complete(req, err);
261         local_bh_enable();
262 }
263 
264 static int async_chainiv_init(struct crypto_tfm *tfm)
265 {
266         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
267 
268         spin_lock_init(&ctx->lock);
269 
270         crypto_init_queue(&ctx->queue, 100);
271         INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
272 
273         return chainiv_init_common(tfm);
274 }
275 
276 static void async_chainiv_exit(struct crypto_tfm *tfm)
277 {
278         struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
279 
280         BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
281 
282         skcipher_geniv_exit(tfm);
283 }
284 
285 static struct crypto_template chainiv_tmpl;
286 
287 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
288 {
289         struct crypto_attr_type *algt;
290         struct crypto_instance *inst;
291         int err;
292 
293         algt = crypto_get_attr_type(tb);
294         if (IS_ERR(algt))
295                 return ERR_CAST(algt);
296 
297         err = crypto_get_default_rng();
298         if (err)
299                 return ERR_PTR(err);
300 
301         inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
302         if (IS_ERR(inst))
303                 goto put_rng;
304 
305         inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first;
306 
307         inst->alg.cra_init = chainiv_init;
308         inst->alg.cra_exit = skcipher_geniv_exit;
309 
310         inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
311 
312         if (!crypto_requires_sync(algt->type, algt->mask)) {
313                 inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
314 
315                 inst->alg.cra_ablkcipher.givencrypt =
316                         async_chainiv_givencrypt_first;
317 
318                 inst->alg.cra_init = async_chainiv_init;
319                 inst->alg.cra_exit = async_chainiv_exit;
320 
321                 inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
322         }
323 
324         inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
325 
326 out:
327         return inst;
328 
329 put_rng:
330         crypto_put_default_rng();
331         goto out;
332 }
333 
334 static void chainiv_free(struct crypto_instance *inst)
335 {
336         skcipher_geniv_free(inst);
337         crypto_put_default_rng();
338 }
339 
340 static struct crypto_template chainiv_tmpl = {
341         .name = "chainiv",
342         .alloc = chainiv_alloc,
343         .free = chainiv_free,
344         .module = THIS_MODULE,
345 };
346 
347 static int __init chainiv_module_init(void)
348 {
349         return crypto_register_template(&chainiv_tmpl);
350 }
351 
352 static void chainiv_module_exit(void)
353 {
354         crypto_unregister_template(&chainiv_tmpl);
355 }
356 
357 module_init(chainiv_module_init);
358 module_exit(chainiv_module_exit);
359 
360 MODULE_LICENSE("GPL");
361 MODULE_DESCRIPTION("Chain IV Generator");
362 MODULE_ALIAS_CRYPTO("chainiv");
363 

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