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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 |
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