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 <linux/err.h>
18 #include <linux/init.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/random.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
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
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
87 spin_lock_bh(&ctx->lock);
88 if (crypto_ablkcipher_crt(geniv)->givencrypt !=
89 chainiv_givencrypt_first)
90 goto unlock;
91
92 crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt;
93 get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv));
94
95 unlock:
96 spin_unlock_bh(&ctx->lock);
97
98 return chainiv_givencrypt(req);
99 }
100
101 static int chainiv_init_common(struct crypto_tfm *tfm)
102 {
103 tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
104
105 return skcipher_geniv_init(tfm);
106 }
107
108 static int chainiv_init(struct crypto_tfm *tfm)
109 {
110 struct chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
111
112 spin_lock_init(&ctx->lock);
113
114 return chainiv_init_common(tfm);
115 }
116
117 static int async_chainiv_schedule_work(struct async_chainiv_ctx *ctx)
118 {
119 int queued;
120
121 if (!ctx->queue.qlen) {
122 smp_mb__before_clear_bit();
123 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
124
125 if (!ctx->queue.qlen ||
126 test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
127 goto out;
128 }
129
130 queued = schedule_work(&ctx->postponed);
131 BUG_ON(!queued);
132
133 out:
134 return ctx->err;
135 }
136
137 static int async_chainiv_postpone_request(struct skcipher_givcrypt_request *req)
138 {
139 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
140 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
141 int err;
142
143 spin_lock_bh(&ctx->lock);
144 err = skcipher_enqueue_givcrypt(&ctx->queue, req);
145 spin_unlock_bh(&ctx->lock);
146
147 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
148 return err;
149
150 ctx->err = err;
151 return async_chainiv_schedule_work(ctx);
152 }
153
154 static int async_chainiv_givencrypt_tail(struct skcipher_givcrypt_request *req)
155 {
156 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
157 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
158 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
159 unsigned int ivsize = crypto_ablkcipher_ivsize(geniv);
160
161 memcpy(req->giv, ctx->iv, ivsize);
162 memcpy(subreq->info, ctx->iv, ivsize);
163
164 ctx->err = crypto_ablkcipher_encrypt(subreq);
165 if (ctx->err)
166 goto out;
167
168 memcpy(ctx->iv, subreq->info, ivsize);
169
170 out:
171 return async_chainiv_schedule_work(ctx);
172 }
173
174 static int async_chainiv_givencrypt(struct skcipher_givcrypt_request *req)
175 {
176 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
177 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
178 struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
179
180 ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
181 ablkcipher_request_set_callback(subreq, req->creq.base.flags,
182 req->creq.base.complete,
183 req->creq.base.data);
184 ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
185 req->creq.nbytes, req->creq.info);
186
187 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
188 goto postpone;
189
190 if (ctx->queue.qlen) {
191 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
192 goto postpone;
193 }
194
195 return async_chainiv_givencrypt_tail(req);
196
197 postpone:
198 return async_chainiv_postpone_request(req);
199 }
200
201 static int async_chainiv_givencrypt_first(struct skcipher_givcrypt_request *req)
202 {
203 struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
204 struct async_chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
205
206 if (test_and_set_bit(CHAINIV_STATE_INUSE, &ctx->state))
207 goto out;
208
209 if (crypto_ablkcipher_crt(geniv)->givencrypt !=
210 async_chainiv_givencrypt_first)
211 goto unlock;
212
213 crypto_ablkcipher_crt(geniv)->givencrypt = async_chainiv_givencrypt;
214 get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv));
215
216 unlock:
217 clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
218
219 out:
220 return async_chainiv_givencrypt(req);
221 }
222
223 static void async_chainiv_do_postponed(struct work_struct *work)
224 {
225 struct async_chainiv_ctx *ctx = container_of(work,
226 struct async_chainiv_ctx,
227 postponed);
228 struct skcipher_givcrypt_request *req;
229 struct ablkcipher_request *subreq;
230
231 /* Only handle one request at a time to avoid hogging keventd. */
232 spin_lock_bh(&ctx->lock);
233 req = skcipher_dequeue_givcrypt(&ctx->queue);
234 spin_unlock_bh(&ctx->lock);
235
236 if (!req) {
237 async_chainiv_schedule_work(ctx);
238 return;
239 }
240
241 subreq = skcipher_givcrypt_reqctx(req);
242 subreq->base.flags |= CRYPTO_TFM_REQ_MAY_SLEEP;
243
244 async_chainiv_givencrypt_tail(req);
245 }
246
247 static int async_chainiv_init(struct crypto_tfm *tfm)
248 {
249 struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
250
251 spin_lock_init(&ctx->lock);
252
253 crypto_init_queue(&ctx->queue, 100);
254 INIT_WORK(&ctx->postponed, async_chainiv_do_postponed);
255
256 return chainiv_init_common(tfm);
257 }
258
259 static void async_chainiv_exit(struct crypto_tfm *tfm)
260 {
261 struct async_chainiv_ctx *ctx = crypto_tfm_ctx(tfm);
262
263 BUG_ON(test_bit(CHAINIV_STATE_INUSE, &ctx->state) || ctx->queue.qlen);
264
265 skcipher_geniv_exit(tfm);
266 }
267
268 static struct crypto_template chainiv_tmpl;
269
270 static struct crypto_instance *chainiv_alloc(struct rtattr **tb)
271 {
272 struct crypto_attr_type *algt;
273 struct crypto_instance *inst;
274 int err;
275
276 algt = crypto_get_attr_type(tb);
277 err = PTR_ERR(algt);
278 if (IS_ERR(algt))
279 return ERR_PTR(err);
280
281 inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, 0);
282 if (IS_ERR(inst))
283 goto out;
284
285 inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first;
286
287 inst->alg.cra_init = chainiv_init;
288 inst->alg.cra_exit = skcipher_geniv_exit;
289
290 inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx);
291
292 if (!crypto_requires_sync(algt->type, algt->mask)) {
293 inst->alg.cra_flags |= CRYPTO_ALG_ASYNC;
294
295 inst->alg.cra_ablkcipher.givencrypt =
296 async_chainiv_givencrypt_first;
297
298 inst->alg.cra_init = async_chainiv_init;
299 inst->alg.cra_exit = async_chainiv_exit;
300
301 inst->alg.cra_ctxsize = sizeof(struct async_chainiv_ctx);
302 }
303
304 inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
305
306 out:
307 return inst;
308 }
309
310 static struct crypto_template chainiv_tmpl = {
311 .name = "chainiv",
312 .alloc = chainiv_alloc,
313 .free = skcipher_geniv_free,
314 .module = THIS_MODULE,
315 };
316
317 int __init chainiv_module_init(void)
318 {
319 return crypto_register_template(&chainiv_tmpl);
320 }
321
322 void chainiv_module_exit(void)
323 {
324 crypto_unregister_template(&chainiv_tmpl);
325 }
326
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