Root/crypto/chainiv.c

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
27enum {
28    CHAINIV_STATE_INUSE = 0,
29};
30
31struct chainiv_ctx {
32    spinlock_t lock;
33    char iv[];
34};
35
36struct 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
48static 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
77unlock:
78    spin_unlock_bh(&ctx->lock);
79
80    return err;
81}
82
83static 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
98unlock:
99    spin_unlock_bh(&ctx->lock);
100
101    if (err)
102        return err;
103
104    return chainiv_givencrypt(req);
105}
106
107static 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
114static 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
123static 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_atomic();
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
140out:
141    return err;
142}
143
144static 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
161static 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
177out:
178    return async_chainiv_schedule_work(ctx);
179}
180
181static 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
204postpone:
205    return async_chainiv_postpone_request(req);
206}
207
208static 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
225unlock:
226    clear_bit(CHAINIV_STATE_INUSE, &ctx->state);
227
228    if (err)
229        return err;
230
231out:
232    return async_chainiv_givencrypt(req);
233}
234
235static 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
264static 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
276static 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
285static struct crypto_template chainiv_tmpl;
286
287static 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
326out:
327    return inst;
328
329put_rng:
330    crypto_put_default_rng();
331    goto out;
332}
333
334static void chainiv_free(struct crypto_instance *inst)
335{
336    skcipher_geniv_free(inst);
337    crypto_put_default_rng();
338}
339
340static struct crypto_template chainiv_tmpl = {
341    .name = "chainiv",
342    .alloc = chainiv_alloc,
343    .free = chainiv_free,
344    .module = THIS_MODULE,
345};
346
347static int __init chainiv_module_init(void)
348{
349    return crypto_register_template(&chainiv_tmpl);
350}
351
352static void chainiv_module_exit(void)
353{
354    crypto_unregister_template(&chainiv_tmpl);
355}
356
357module_init(chainiv_module_init);
358module_exit(chainiv_module_exit);
359
360MODULE_LICENSE("GPL");
361MODULE_DESCRIPTION("Chain IV Generator");
362

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