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/geniv.h>
17#include <crypto/internal/skcipher.h>
18#include <crypto/rng.h>
19#include <crypto/scatterwalk.h>
20#include <linux/err.h>
21#include <linux/init.h>
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/slab.h>
25#include <linux/spinlock.h>
26#include <linux/string.h>
27
28struct seqiv_ctx {
29	spinlock_t lock;
30	u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
31};
32
33static void seqiv_free(struct crypto_instance *inst);
34
35static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err)
36{
37	struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
38	struct crypto_ablkcipher *geniv;
39
40	if (err == -EINPROGRESS)
41		return;
42
43	if (err)
44		goto out;
45
46	geniv = skcipher_givcrypt_reqtfm(req);
47	memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv));
48
49out:
50	kfree(subreq->info);
51}
52
53static void seqiv_complete(struct crypto_async_request *base, int err)
54{
55	struct skcipher_givcrypt_request *req = base->data;
56
57	seqiv_complete2(req, err);
58	skcipher_givcrypt_complete(req, err);
59}
60
61static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err)
62{
63	struct aead_request *subreq = aead_request_ctx(req);
64	struct crypto_aead *geniv;
65
66	if (err == -EINPROGRESS)
67		return;
68
69	if (err)
70		goto out;
71
72	geniv = crypto_aead_reqtfm(req);
73	memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv));
74
75out:
76	kzfree(subreq->iv);
77}
78
79static void seqiv_aead_encrypt_complete(struct crypto_async_request *base,
80					int err)
81{
82	struct aead_request *req = base->data;
83
84	seqiv_aead_encrypt_complete2(req, err);
85	aead_request_complete(req, err);
86}
87
88static void seqiv_geniv(struct seqiv_ctx *ctx, u8 *info, u64 seq,
89			unsigned int ivsize)
90{
91	unsigned int len = ivsize;
92
93	if (ivsize > sizeof(u64)) {
94		memset(info, 0, ivsize - sizeof(u64));
95		len = sizeof(u64);
96	}
97	seq = cpu_to_be64(seq);
98	memcpy(info + ivsize - len, &seq, len);
99	crypto_xor(info, ctx->salt, ivsize);
100}
101
102static int seqiv_givencrypt(struct skcipher_givcrypt_request *req)
103{
104	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
105	struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
106	struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
107	crypto_completion_t compl;
108	void *data;
109	u8 *info;
110	unsigned int ivsize;
111	int err;
112
113	ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
114
115	compl = req->creq.base.complete;
116	data = req->creq.base.data;
117	info = req->creq.info;
118
119	ivsize = crypto_ablkcipher_ivsize(geniv);
120
121	if (unlikely(!IS_ALIGNED((unsigned long)info,
122				 crypto_ablkcipher_alignmask(geniv) + 1))) {
123		info = kmalloc(ivsize, req->creq.base.flags &
124				       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
125								  GFP_ATOMIC);
126		if (!info)
127			return -ENOMEM;
128
129		compl = seqiv_complete;
130		data = req;
131	}
132
133	ablkcipher_request_set_callback(subreq, req->creq.base.flags, compl,
134					data);
135	ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
136				     req->creq.nbytes, info);
137
138	seqiv_geniv(ctx, info, req->seq, ivsize);
139	memcpy(req->giv, info, ivsize);
140
141	err = crypto_ablkcipher_encrypt(subreq);
142	if (unlikely(info != req->creq.info))
143		seqiv_complete2(req, err);
144	return err;
145}
146
147static int seqiv_aead_encrypt(struct aead_request *req)
148{
149	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
150	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
151	struct aead_request *subreq = aead_request_ctx(req);
152	crypto_completion_t compl;
153	void *data;
154	u8 *info;
155	unsigned int ivsize = 8;
156	int err;
157
158	if (req->cryptlen < ivsize)
159		return -EINVAL;
160
161	aead_request_set_tfm(subreq, ctx->child);
162
163	compl = req->base.complete;
164	data = req->base.data;
165	info = req->iv;
166
167	if (req->src != req->dst) {
168		struct blkcipher_desc desc = {
169			.tfm = ctx->null,
170		};
171
172		err = crypto_blkcipher_encrypt(&desc, req->dst, req->src,
173					       req->assoclen + req->cryptlen);
174		if (err)
175			return err;
176	}
177
178	if (unlikely(!IS_ALIGNED((unsigned long)info,
179				 crypto_aead_alignmask(geniv) + 1))) {
180		info = kmalloc(ivsize, req->base.flags &
181				       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
182								  GFP_ATOMIC);
183		if (!info)
184			return -ENOMEM;
185
186		memcpy(info, req->iv, ivsize);
187		compl = seqiv_aead_encrypt_complete;
188		data = req;
189	}
190
191	aead_request_set_callback(subreq, req->base.flags, compl, data);
192	aead_request_set_crypt(subreq, req->dst, req->dst,
193			       req->cryptlen - ivsize, info);
194	aead_request_set_ad(subreq, req->assoclen + ivsize);
195
196	crypto_xor(info, ctx->salt, ivsize);
197	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
198
199	err = crypto_aead_encrypt(subreq);
200	if (unlikely(info != req->iv))
201		seqiv_aead_encrypt_complete2(req, err);
202	return err;
203}
204
205static int seqiv_aead_decrypt(struct aead_request *req)
206{
207	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
208	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
209	struct aead_request *subreq = aead_request_ctx(req);
210	crypto_completion_t compl;
211	void *data;
212	unsigned int ivsize = 8;
213
214	if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
215		return -EINVAL;
216
217	aead_request_set_tfm(subreq, ctx->child);
218
219	compl = req->base.complete;
220	data = req->base.data;
221
222	aead_request_set_callback(subreq, req->base.flags, compl, data);
223	aead_request_set_crypt(subreq, req->src, req->dst,
224			       req->cryptlen - ivsize, req->iv);
225	aead_request_set_ad(subreq, req->assoclen + ivsize);
226
227	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
228
229	return crypto_aead_decrypt(subreq);
230}
231
232static int seqiv_init(struct crypto_tfm *tfm)
233{
234	struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
235	struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
236	int err;
237
238	spin_lock_init(&ctx->lock);
239
240	tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
241
242	err = 0;
243	if (!crypto_get_default_rng()) {
244		crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt;
245		err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
246					   crypto_ablkcipher_ivsize(geniv));
247		crypto_put_default_rng();
248	}
249
250	return err ?: skcipher_geniv_init(tfm);
251}
252
253static int seqiv_ablkcipher_create(struct crypto_template *tmpl,
254				   struct rtattr **tb)
255{
256	struct crypto_instance *inst;
257	int err;
258
259	inst = skcipher_geniv_alloc(tmpl, tb, 0, 0);
260
261	if (IS_ERR(inst))
262		return PTR_ERR(inst);
263
264	err = -EINVAL;
265	if (inst->alg.cra_ablkcipher.ivsize < sizeof(u64))
266		goto free_inst;
267
268	inst->alg.cra_init = seqiv_init;
269	inst->alg.cra_exit = skcipher_geniv_exit;
270
271	inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
272	inst->alg.cra_ctxsize += sizeof(struct seqiv_ctx);
273
274	inst->alg.cra_alignmask |= __alignof__(u32) - 1;
275
276	err = crypto_register_instance(tmpl, inst);
277	if (err)
278		goto free_inst;
279
280out:
281	return err;
282
283free_inst:
284	skcipher_geniv_free(inst);
285	goto out;
286}
287
288static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
289{
290	struct aead_instance *inst;
291	struct crypto_aead_spawn *spawn;
292	struct aead_alg *alg;
293	int err;
294
295	inst = aead_geniv_alloc(tmpl, tb, 0, 0);
296
297	if (IS_ERR(inst))
298		return PTR_ERR(inst);
299
300	inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
301
302	spawn = aead_instance_ctx(inst);
303	alg = crypto_spawn_aead_alg(spawn);
304
305	err = -EINVAL;
306	if (inst->alg.ivsize != sizeof(u64))
307		goto free_inst;
308
309	inst->alg.encrypt = seqiv_aead_encrypt;
310	inst->alg.decrypt = seqiv_aead_decrypt;
311
312	inst->alg.init = aead_init_geniv;
313	inst->alg.exit = aead_exit_geniv;
314
315	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
316	inst->alg.base.cra_ctxsize += inst->alg.ivsize;
317
318	err = aead_register_instance(tmpl, inst);
319	if (err)
320		goto free_inst;
321
322out:
323	return err;
324
325free_inst:
326	aead_geniv_free(inst);
327	goto out;
328}
329
330static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb)
331{
332	struct crypto_attr_type *algt;
333	int err;
334
335	algt = crypto_get_attr_type(tb);
336	if (IS_ERR(algt))
337		return PTR_ERR(algt);
338
339	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
340		err = seqiv_ablkcipher_create(tmpl, tb);
341	else
342		err = seqiv_aead_create(tmpl, tb);
343
344	return err;
345}
346
347static void seqiv_free(struct crypto_instance *inst)
348{
349	if ((inst->alg.cra_flags ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
350		skcipher_geniv_free(inst);
351	else
352		aead_geniv_free(aead_instance(inst));
353}
354
355static struct crypto_template seqiv_tmpl = {
356	.name = "seqiv",
357	.create = seqiv_create,
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