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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 | err = PTR_ERR(algt); | |
295 | if (IS_ERR(algt)) | |
296 | return ERR_PTR(err); | |
297 | ||
298 | err = crypto_get_default_rng(); | |
299 | if (err) | |
300 | return ERR_PTR(err); | |
301 | ||
302 | inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0); | |
303 | if (IS_ERR(inst)) | |
304 | goto put_rng; | |
305 | ||
306 | inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first; | |
307 | ||
308 | inst->alg.cra_init = chainiv_init; | |
309 | inst->alg.cra_exit = skcipher_geniv_exit; | |
310 | ||
311 | inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx); | |
312 | ||
313 | if (!crypto_requires_sync(algt->type, algt->mask)) { | |
314 | inst->alg.cra_flags |= CRYPTO_ALG_ASYNC; | |
315 | ||
316 | inst->alg.cra_ablkcipher.givencrypt = | |
317 | async_chainiv_givencrypt_first; | |
318 | ||
319 | inst->alg.cra_init = async_chainiv_init; | |
320 | inst->alg.cra_exit = async_chainiv_exit; | |
321 | ||
322 | inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx); | |
323 | } | |
324 | ||
325 | inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; | |
326 | ||
327 | out: | |
328 | return inst; | |
329 | ||
330 | put_rng: | |
331 | crypto_put_default_rng(); | |
332 | goto out; | |
333 | } | |
334 | ||
335 | static void chainiv_free(struct crypto_instance *inst) | |
336 | { | |
337 | skcipher_geniv_free(inst); | |
338 | crypto_put_default_rng(); | |
339 | } | |
340 | ||
341 | static struct crypto_template chainiv_tmpl = { | |
342 | .name = "chainiv", | |
343 | .alloc = chainiv_alloc, | |
344 | .free = chainiv_free, | |
345 | .module = THIS_MODULE, | |
346 | }; | |
347 | ||
348 | static int __init chainiv_module_init(void) | |
349 | { | |
350 | return crypto_register_template(&chainiv_tmpl); | |
351 | } | |
352 | ||
353 | static void chainiv_module_exit(void) | |
354 | { | |
355 | crypto_unregister_template(&chainiv_tmpl); | |
356 | } | |
357 | ||
358 | module_init(chainiv_module_init); | |
359 | module_exit(chainiv_module_exit); | |
360 | ||
361 | MODULE_LICENSE("GPL"); | |
362 | MODULE_DESCRIPTION("Chain IV Generator"); |