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");
363
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