Root/crypto/seqiv.c

1/*
2 * seqiv: Sequence Number IV Generator
3 *
4 * This generator generates an IV based on a sequence number by xoring it
5 * with a salt. This algorithm is mainly useful for CTR and similar modes.
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/aead.h>
17#include <crypto/internal/skcipher.h>
18#include <crypto/rng.h>
19#include <linux/err.h>
20#include <linux/init.h>
21#include <linux/kernel.h>
22#include <linux/module.h>
23#include <linux/slab.h>
24#include <linux/spinlock.h>
25#include <linux/string.h>
26
27struct seqiv_ctx {
28    spinlock_t lock;
29    u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
30};
31
32static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err)
33{
34    struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
35    struct crypto_ablkcipher *geniv;
36
37    if (err == -EINPROGRESS)
38        return;
39
40    if (err)
41        goto out;
42
43    geniv = skcipher_givcrypt_reqtfm(req);
44    memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv));
45
46out:
47    kfree(subreq->info);
48}
49
50static void seqiv_complete(struct crypto_async_request *base, int err)
51{
52    struct skcipher_givcrypt_request *req = base->data;
53
54    seqiv_complete2(req, err);
55    skcipher_givcrypt_complete(req, err);
56}
57
58static void seqiv_aead_complete2(struct aead_givcrypt_request *req, int err)
59{
60    struct aead_request *subreq = aead_givcrypt_reqctx(req);
61    struct crypto_aead *geniv;
62
63    if (err == -EINPROGRESS)
64        return;
65
66    if (err)
67        goto out;
68
69    geniv = aead_givcrypt_reqtfm(req);
70    memcpy(req->areq.iv, subreq->iv, crypto_aead_ivsize(geniv));
71
72out:
73    kfree(subreq->iv);
74}
75
76static void seqiv_aead_complete(struct crypto_async_request *base, int err)
77{
78    struct aead_givcrypt_request *req = base->data;
79
80    seqiv_aead_complete2(req, err);
81    aead_givcrypt_complete(req, err);
82}
83
84static void seqiv_geniv(struct seqiv_ctx *ctx, u8 *info, u64 seq,
85            unsigned int ivsize)
86{
87    unsigned int len = ivsize;
88
89    if (ivsize > sizeof(u64)) {
90        memset(info, 0, ivsize - sizeof(u64));
91        len = sizeof(u64);
92    }
93    seq = cpu_to_be64(seq);
94    memcpy(info + ivsize - len, &seq, len);
95    crypto_xor(info, ctx->salt, ivsize);
96}
97
98static int seqiv_givencrypt(struct skcipher_givcrypt_request *req)
99{
100    struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
101    struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
102    struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
103    crypto_completion_t compl;
104    void *data;
105    u8 *info;
106    unsigned int ivsize;
107    int err;
108
109    ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
110
111    compl = req->creq.base.complete;
112    data = req->creq.base.data;
113    info = req->creq.info;
114
115    ivsize = crypto_ablkcipher_ivsize(geniv);
116
117    if (unlikely(!IS_ALIGNED((unsigned long)info,
118                 crypto_ablkcipher_alignmask(geniv) + 1))) {
119        info = kmalloc(ivsize, req->creq.base.flags &
120                       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
121                                  GFP_ATOMIC);
122        if (!info)
123            return -ENOMEM;
124
125        compl = seqiv_complete;
126        data = req;
127    }
128
129    ablkcipher_request_set_callback(subreq, req->creq.base.flags, compl,
130                    data);
131    ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
132                     req->creq.nbytes, info);
133
134    seqiv_geniv(ctx, info, req->seq, ivsize);
135    memcpy(req->giv, info, ivsize);
136
137    err = crypto_ablkcipher_encrypt(subreq);
138    if (unlikely(info != req->creq.info))
139        seqiv_complete2(req, err);
140    return err;
141}
142
143static int seqiv_aead_givencrypt(struct aead_givcrypt_request *req)
144{
145    struct crypto_aead *geniv = aead_givcrypt_reqtfm(req);
146    struct seqiv_ctx *ctx = crypto_aead_ctx(geniv);
147    struct aead_request *areq = &req->areq;
148    struct aead_request *subreq = aead_givcrypt_reqctx(req);
149    crypto_completion_t compl;
150    void *data;
151    u8 *info;
152    unsigned int ivsize;
153    int err;
154
155    aead_request_set_tfm(subreq, aead_geniv_base(geniv));
156
157    compl = areq->base.complete;
158    data = areq->base.data;
159    info = areq->iv;
160
161    ivsize = crypto_aead_ivsize(geniv);
162
163    if (unlikely(!IS_ALIGNED((unsigned long)info,
164                 crypto_aead_alignmask(geniv) + 1))) {
165        info = kmalloc(ivsize, areq->base.flags &
166                       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
167                                  GFP_ATOMIC);
168        if (!info)
169            return -ENOMEM;
170
171        compl = seqiv_aead_complete;
172        data = req;
173    }
174
175    aead_request_set_callback(subreq, areq->base.flags, compl, data);
176    aead_request_set_crypt(subreq, areq->src, areq->dst, areq->cryptlen,
177                   info);
178    aead_request_set_assoc(subreq, areq->assoc, areq->assoclen);
179
180    seqiv_geniv(ctx, info, req->seq, ivsize);
181    memcpy(req->giv, info, ivsize);
182
183    err = crypto_aead_encrypt(subreq);
184    if (unlikely(info != areq->iv))
185        seqiv_aead_complete2(req, err);
186    return err;
187}
188
189static int seqiv_givencrypt_first(struct skcipher_givcrypt_request *req)
190{
191    struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
192    struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
193    int err = 0;
194
195    spin_lock_bh(&ctx->lock);
196    if (crypto_ablkcipher_crt(geniv)->givencrypt != seqiv_givencrypt_first)
197        goto unlock;
198
199    crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt;
200    err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
201                   crypto_ablkcipher_ivsize(geniv));
202
203unlock:
204    spin_unlock_bh(&ctx->lock);
205
206    if (err)
207        return err;
208
209    return seqiv_givencrypt(req);
210}
211
212static int seqiv_aead_givencrypt_first(struct aead_givcrypt_request *req)
213{
214    struct crypto_aead *geniv = aead_givcrypt_reqtfm(req);
215    struct seqiv_ctx *ctx = crypto_aead_ctx(geniv);
216    int err = 0;
217
218    spin_lock_bh(&ctx->lock);
219    if (crypto_aead_crt(geniv)->givencrypt != seqiv_aead_givencrypt_first)
220        goto unlock;
221
222    crypto_aead_crt(geniv)->givencrypt = seqiv_aead_givencrypt;
223    err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
224                   crypto_aead_ivsize(geniv));
225
226unlock:
227    spin_unlock_bh(&ctx->lock);
228
229    if (err)
230        return err;
231
232    return seqiv_aead_givencrypt(req);
233}
234
235static int seqiv_init(struct crypto_tfm *tfm)
236{
237    struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
238    struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
239
240    spin_lock_init(&ctx->lock);
241
242    tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
243
244    return skcipher_geniv_init(tfm);
245}
246
247static int seqiv_aead_init(struct crypto_tfm *tfm)
248{
249    struct crypto_aead *geniv = __crypto_aead_cast(tfm);
250    struct seqiv_ctx *ctx = crypto_aead_ctx(geniv);
251
252    spin_lock_init(&ctx->lock);
253
254    tfm->crt_aead.reqsize = sizeof(struct aead_request);
255
256    return aead_geniv_init(tfm);
257}
258
259static struct crypto_template seqiv_tmpl;
260
261static struct crypto_instance *seqiv_ablkcipher_alloc(struct rtattr **tb)
262{
263    struct crypto_instance *inst;
264
265    inst = skcipher_geniv_alloc(&seqiv_tmpl, tb, 0, 0);
266
267    if (IS_ERR(inst))
268        goto out;
269
270    inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first;
271
272    inst->alg.cra_init = seqiv_init;
273    inst->alg.cra_exit = skcipher_geniv_exit;
274
275    inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
276
277out:
278    return inst;
279}
280
281static struct crypto_instance *seqiv_aead_alloc(struct rtattr **tb)
282{
283    struct crypto_instance *inst;
284
285    inst = aead_geniv_alloc(&seqiv_tmpl, tb, 0, 0);
286
287    if (IS_ERR(inst))
288        goto out;
289
290    inst->alg.cra_aead.givencrypt = seqiv_aead_givencrypt_first;
291
292    inst->alg.cra_init = seqiv_aead_init;
293    inst->alg.cra_exit = aead_geniv_exit;
294
295    inst->alg.cra_ctxsize = inst->alg.cra_aead.ivsize;
296
297out:
298    return inst;
299}
300
301static struct crypto_instance *seqiv_alloc(struct rtattr **tb)
302{
303    struct crypto_attr_type *algt;
304    struct crypto_instance *inst;
305    int err;
306
307    algt = crypto_get_attr_type(tb);
308    if (IS_ERR(algt))
309        return ERR_CAST(algt);
310
311    err = crypto_get_default_rng();
312    if (err)
313        return ERR_PTR(err);
314
315    if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
316        inst = seqiv_ablkcipher_alloc(tb);
317    else
318        inst = seqiv_aead_alloc(tb);
319
320    if (IS_ERR(inst))
321        goto put_rng;
322
323    inst->alg.cra_alignmask |= __alignof__(u32) - 1;
324    inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx);
325
326out:
327    return inst;
328
329put_rng:
330    crypto_put_default_rng();
331    goto out;
332}
333
334static void seqiv_free(struct crypto_instance *inst)
335{
336    if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
337        skcipher_geniv_free(inst);
338    else
339        aead_geniv_free(inst);
340    crypto_put_default_rng();
341}
342
343static struct crypto_template seqiv_tmpl = {
344    .name = "seqiv",
345    .alloc = seqiv_alloc,
346    .free = seqiv_free,
347    .module = THIS_MODULE,
348};
349
350static int __init seqiv_module_init(void)
351{
352    return crypto_register_template(&seqiv_tmpl);
353}
354
355static void __exit seqiv_module_exit(void)
356{
357    crypto_unregister_template(&seqiv_tmpl);
358}
359
360module_init(seqiv_module_init);
361module_exit(seqiv_module_exit);
362
363MODULE_LICENSE("GPL");
364MODULE_DESCRIPTION("Sequence Number IV Generator");
365

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