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 <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/spinlock.h>
23 #include <linux/string.h>
24 #include <linux/workqueue.h>
25
26 enum {
27 CHAINIV_STATE_INUSE = 0,
28 };
29
30 struct chainiv_ctx {
31 spinlock_t lock;
32 char iv[];
33 };
34
35 struct async_chainiv_ctx {
36 unsigned long state;
37
38 spinlock_t lock;
39 int err;
40
41 struct crypto_queue queue;
42 struct work_struct postponed;
43
44 char iv[];
45 };
46
chainiv_givencrypt(struct skcipher_givcrypt_request * req)47 static int chainiv_givencrypt(struct skcipher_givcrypt_request *req)
48 {
49 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
50 struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
51 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
52 unsigned int ivsize;
53 int err;
54
55 ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
56 ablkcipher_request_set_callback(subreq, req->creq.base.flags &
57 ~CRYPTO_TFM_REQ_MAY_SLEEP,
58 req->creq.base.complete,
59 req->creq.base.data);
60 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
61 req->creq.nbytes, req->creq.info);
62
63 spin_lock_bh(&ctx->lock);
64
65 ivsize = crypto_ablkcipher_ivsize(geniv);
66
67 memcpy(req->giv, ctx->iv, ivsize);
68 memcpy(subreq->info, ctx->iv, ivsize);
69
70 err = crypto_ablkcipher_encrypt(subreq);
71 if (err)
72 goto unlock;
73
74 memcpy(ctx->iv, subreq->info, ivsize);
75
76 unlock:
77 spin_unlock_bh(&ctx->lock);
78
79 return err;
80 }
81
chainiv_givencrypt_first(struct skcipher_givcrypt_request * req)82 static int chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
83 {
84 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
85 struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
86 int err = 0;
87
88 spin_lock_bh(&ctx->lock);
89 if (crypto_ablkcipher_crt(geniv)->givencrypt !=
90 chainiv_givencrypt_first)
91 goto unlock;
92
93 crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
94 err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
95 crypto_ablkcipher_ivsize(geniv));
96
97 unlock:
98 spin_unlock_bh(&ctx->lock);
99
100 if (err)
101 return err;
102
103 return chainiv_givencrypt(req);
104 }
105
chainiv_init_common(struct crypto_tfm * tfm)106 static int chainiv_init_common(struct crypto_tfm *tfm)
107 {
108 tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
109
110 return skcipher_geniv_init(tfm);
111 }
112
chainiv_init(struct crypto_tfm * tfm)113 static int chainiv_init(struct crypto_tfm *tfm)
114 {
115 struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
116
117 spin_lock_init(&ctx->lock);
118
119 return chainiv_init_common(tfm);
120 }
121
async_chainiv_schedule_work(struct async_chainiv_ctx * ctx)122 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
123 {
124 int queued;
125 int err = ctx->err;
126
127 if (!ctx->queue.qlen) {
128 smp_mb__before_clear_bit();
129 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
130
131 if (!ctx->queue.qlen ||
132 test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
133 goto out;
134 }
135
136 queued = schedule_work(&ctx->postponed);
137 BUG_ON(!queued);
138
139 out:
140 return err;
141 }
142
async_chainiv_postpone_request(struct skcipher_givcrypt_request * req)143 static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
144 {
145 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
146 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
147 int err;
148
149 spin_lock_bh(&ctx->lock);
150 err = skcipher_enqueue_givcrypt(&ctx->queue, req);
151 spin_unlock_bh(&ctx->lock);
152
153 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
154 return err;
155
156 ctx->err = err;
157 return async_chainiv_schedule_work(ctx);
158 }
159
async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request * req)160 static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
161 {
162 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
163 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
164 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
165 unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
166
167 memcpy(req->giv, ctx->iv, ivsize);
168 memcpy(subreq->info, ctx->iv, ivsize);
169
170 ctx->err = crypto_ablkcipher_encrypt(subreq);
171 if (ctx->err)
172 goto out;
173
174 memcpy(ctx->iv, subreq->info, ivsize);
175
176 out:
177 return async_chainiv_schedule_work(ctx);
178 }
179
async_chainiv_givencrypt(struct skcipher_givcrypt_request * req)180 static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
181 {
182 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
183 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
184 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
185
186 ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
187 ablkcipher_request_set_callback(subreq, req->creq.base.flags,
188 req->creq.base.complete,
189 req->creq.base.data);
190 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
191 req->creq.nbytes, req->creq.info);
192
193 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
194 goto postpone;
195
196 if (ctx->queue.qlen) {
197 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
198 goto postpone;
199 }
200
201 return async_chainiv_givencrypt_tail(req);
202
203 postpone:
204 return async_chainiv_postpone_request(req);
205 }
206
async_chainiv_givencrypt_first(struct skcipher_givcrypt_request * req)207 static int async_chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
208 {
209 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
210 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
211 int err = 0;
212
213 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
214 goto out;
215
216 if (crypto_ablkcipher_crt(geniv)->givencrypt !=
217 async_chainiv_givencrypt_first)
218 goto unlock;
219
220 crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt;
221 err = crypto_rng_get_bytes(crypto_default_rng, ctx->iv,
222 crypto_ablkcipher_ivsize(geniv));
223
224 unlock:
225 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
226
227 if (err)
228 return err;
229
230 out:
231 return async_chainiv_givencrypt(req);
232 }
233
async_chainiv_do_postponed(struct work_struct * work)234 static void async_chainiv_do_postponed(struct work_struct *work)
235 {
236 struct async_chainiv_ctx *ctx = container_of(work,
237 struct async_chainiv_ctx,
238 postponed);
239 struct skcipher_givcrypt_request *req;
240 struct ablkcipher_request *subreq;
241 int err;
242
243 /* Only handle one request at a time to avoid hogging keventd. */
244 spin_lock_bh(&ctx->lock);
245 req = skcipher_dequeue_givcrypt(&ctx->queue);
246 spin_unlock_bh(&ctx->lock);
247
248 if (!req) {
249 async_chainiv_schedule_work(ctx);
250 return;
251 }
252
253 subreq = skcipher_givcrypt_reqctx(req);
254 subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
255
256 err = async_chainiv_givencrypt_tail(req);
257
258 local_bh_disable();
259 skcipher_givcrypt_complete(req, err);
260 local_bh_enable();
261 }
262
async_chainiv_init(struct crypto_tfm * tfm)263 static int async_chainiv_init(struct crypto_tfm *tfm)
264 {
265 struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
266
267 spin_lock_init(&ctx->lock);
268
269 crypto_init_queue(&ctx->queue, 100);
270 INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
271
272 return chainiv_init_common(tfm);
273 }
274
async_chainiv_exit(struct crypto_tfm * tfm)275 static void async_chainiv_exit(struct crypto_tfm *tfm)
276 {
277 struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
278
279 BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
280
281 skcipher_geniv_exit(tfm);
282 }
283
284 static struct crypto_template chainiv_tmpl;
285
chainiv_alloc(struct rtattr ** tb)286 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
287 {
288 struct crypto_attr_type *algt;
289 struct crypto_instance *inst;
290 int err;
291
292 algt = crypto_get_attr_type(tb);
293 err = PTR_ERR(algt);
294 if (IS_ERR(algt))
295 return ERR_PTR(err);
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
chainiv_free(struct crypto_instance * inst)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
chainiv_module_init(void)347 static int __init chainiv_module_init(void)
348 {
349 return crypto_register_template(&chainiv_tmpl);
350 }
351
chainiv_module_exit(void)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