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	if (inst->alg.cra_ablkcipher.ivsize < sizeof(u64)) {
271		skcipher_geniv_free(inst);
272		inst = ERR_PTR(-EINVAL);
273		goto out;
274	}
275
276	inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first;
277
278	inst->alg.cra_init = seqiv_init;
279	inst->alg.cra_exit = skcipher_geniv_exit;
280
281	inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
282
283out:
284	return inst;
285}
286
287static struct crypto_instance *seqiv_aead_alloc(struct rtattr **tb)
288{
289	struct crypto_instance *inst;
290
291	inst = aead_geniv_alloc(&seqiv_tmpl, tb, 0, 0);
292
293	if (IS_ERR(inst))
294		goto out;
295
296	if (inst->alg.cra_aead.ivsize < sizeof(u64)) {
297		aead_geniv_free(inst);
298		inst = ERR_PTR(-EINVAL);
299		goto out;
300	}
301
302	inst->alg.cra_aead.givencrypt = seqiv_aead_givencrypt_first;
303
304	inst->alg.cra_init = seqiv_aead_init;
305	inst->alg.cra_exit = aead_geniv_exit;
306
307	inst->alg.cra_ctxsize = inst->alg.cra_aead.ivsize;
308
309out:
310	return inst;
311}
312
313static struct crypto_instance *seqiv_alloc(struct rtattr **tb)
314{
315	struct crypto_attr_type *algt;
316	struct crypto_instance *inst;
317	int err;
318
319	algt = crypto_get_attr_type(tb);
320	if (IS_ERR(algt))
321		return ERR_CAST(algt);
322
323	err = crypto_get_default_rng();
324	if (err)
325		return ERR_PTR(err);
326
327	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
328		inst = seqiv_ablkcipher_alloc(tb);
329	else
330		inst = seqiv_aead_alloc(tb);
331
332	if (IS_ERR(inst))
333		goto put_rng;
334
335	inst->alg.cra_alignmask |= __alignof__(u32) - 1;
336	inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx);
337
338out:
339	return inst;
340
341put_rng:
342	crypto_put_default_rng();
343	goto out;
344}
345
346static void seqiv_free(struct crypto_instance *inst)
347{
348	if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
349		skcipher_geniv_free(inst);
350	else
351		aead_geniv_free(inst);
352	crypto_put_default_rng();
353}
354
355static struct crypto_template seqiv_tmpl = {
356	.name = "seqiv",
357	.alloc = seqiv_alloc,
358	.free = seqiv_free,
359	.module = THIS_MODULE,
360};
361
362static int __init seqiv_module_init(void)
363{
364	return crypto_register_template(&seqiv_tmpl);
365}
366
367static void __exit seqiv_module_exit(void)
368{
369	crypto_unregister_template(&seqiv_tmpl);
370}
371
372module_init(seqiv_module_init);
373module_exit(seqiv_module_exit);
374
375MODULE_LICENSE("GPL");
376MODULE_DESCRIPTION("Sequence Number IV Generator");
377MODULE_ALIAS_CRYPTO("seqiv");
378