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/crypto/eseqiv.c

https://bitbucket.org/cresqo/cm7-p500-kernel
C | 283 lines | 209 code | 58 blank | 16 comment | 23 complexity | 4cf7aad48d6ede1d7ad5dfb762a5a1c3 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 * eseqiv: Encrypted Sequence Number IV Generator
  3 *
  4 * This generator generates an IV based on a sequence number by xoring it
  5 * with a salt and then encrypting it with the same key as used to encrypt
  6 * the plain text.  This algorithm requires that the block size be equal
  7 * to the IV size.  It is mainly useful for CBC.
  8 *
  9 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
 10 *
 11 * This program is free software; you can redistribute it and/or modify it
 12 * under the terms of the GNU General Public License as published by the Free
 13 * Software Foundation; either version 2 of the License, or (at your option)
 14 * any later version.
 15 *
 16 */
 17
 18#include <crypto/internal/skcipher.h>
 19#include <crypto/rng.h>
 20#include <crypto/scatterwalk.h>
 21#include <linux/err.h>
 22#include <linux/init.h>
 23#include <linux/kernel.h>
 24#include <linux/mm.h>
 25#include <linux/module.h>
 26#include <linux/scatterlist.h>
 27#include <linux/spinlock.h>
 28#include <linux/string.h>
 29
 30struct eseqiv_request_ctx {
 31	struct scatterlist src[2];
 32	struct scatterlist dst[2];
 33	char tail[];
 34};
 35
 36struct eseqiv_ctx {
 37	spinlock_t lock;
 38	unsigned int reqoff;
 39	char salt[];
 40};
 41
 42static void eseqiv_complete2(struct skcipher_givcrypt_request *req)
 43{
 44	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 45	struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
 46
 47	memcpy(req->giv, PTR_ALIGN((u8 *)reqctx->tail,
 48			 crypto_ablkcipher_alignmask(geniv) + 1),
 49	       crypto_ablkcipher_ivsize(geniv));
 50}
 51
 52static void eseqiv_complete(struct crypto_async_request *base, int err)
 53{
 54	struct skcipher_givcrypt_request *req = base->data;
 55
 56	if (err)
 57		goto out;
 58
 59	eseqiv_complete2(req);
 60
 61out:
 62	skcipher_givcrypt_complete(req, err);
 63}
 64
 65static void eseqiv_chain(struct scatterlist *head, struct scatterlist *sg,
 66			 int chain)
 67{
 68	if (chain) {
 69		head->length += sg->length;
 70		sg = scatterwalk_sg_next(sg);
 71	}
 72
 73	if (sg)
 74		scatterwalk_sg_chain(head, 2, sg);
 75	else
 76		sg_mark_end(head);
 77}
 78
 79static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req)
 80{
 81	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
 82	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
 83	struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
 84	struct ablkcipher_request *subreq;
 85	crypto_completion_t complete;
 86	void *data;
 87	struct scatterlist *osrc, *odst;
 88	struct scatterlist *dst;
 89	struct page *srcp;
 90	struct page *dstp;
 91	u8 *giv;
 92	u8 *vsrc;
 93	u8 *vdst;
 94	__be64 seq;
 95	unsigned int ivsize;
 96	unsigned int len;
 97	int err;
 98
 99	subreq = (void *)(reqctx->tail + ctx->reqoff);
100	ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
101
102	giv = req->giv;
103	complete = req->creq.base.complete;
104	data = req->creq.base.data;
105
106	osrc = req->creq.src;
107	odst = req->creq.dst;
108	srcp = sg_page(osrc);
109	dstp = sg_page(odst);
110	vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset;
111	vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset;
112
113	ivsize = crypto_ablkcipher_ivsize(geniv);
114
115	if (vsrc != giv + ivsize && vdst != giv + ivsize) {
116		giv = PTR_ALIGN((u8 *)reqctx->tail,
117				crypto_ablkcipher_alignmask(geniv) + 1);
118		complete = eseqiv_complete;
119		data = req;
120	}
121
122	ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete,
123					data);
124
125	sg_init_table(reqctx->src, 2);
126	sg_set_buf(reqctx->src, giv, ivsize);
127	eseqiv_chain(reqctx->src, osrc, vsrc == giv + ivsize);
128
129	dst = reqctx->src;
130	if (osrc != odst) {
131		sg_init_table(reqctx->dst, 2);
132		sg_set_buf(reqctx->dst, giv, ivsize);
133		eseqiv_chain(reqctx->dst, odst, vdst == giv + ivsize);
134
135		dst = reqctx->dst;
136	}
137
138	ablkcipher_request_set_crypt(subreq, reqctx->src, dst,
139				     req->creq.nbytes + ivsize,
140				     req->creq.info);
141
142	memcpy(req->creq.info, ctx->salt, ivsize);
143
144	len = ivsize;
145	if (ivsize > sizeof(u64)) {
146		memset(req->giv, 0, ivsize - sizeof(u64));
147		len = sizeof(u64);
148	}
149	seq = cpu_to_be64(req->seq);
150	memcpy(req->giv + ivsize - len, &seq, len);
151
152	err = crypto_ablkcipher_encrypt(subreq);
153	if (err)
154		goto out;
155
156	if (giv != req->giv)
157		eseqiv_complete2(req);
158
159out:
160	return err;
161}
162
163static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req)
164{
165	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
166	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
167	int err = 0;
168
169	spin_lock_bh(&ctx->lock);
170	if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first)
171		goto unlock;
172
173	crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt;
174	err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
175				   crypto_ablkcipher_ivsize(geniv));
176
177unlock:
178	spin_unlock_bh(&ctx->lock);
179
180	if (err)
181		return err;
182
183	return eseqiv_givencrypt(req);
184}
185
186static int eseqiv_init(struct crypto_tfm *tfm)
187{
188	struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
189	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
190	unsigned long alignmask;
191	unsigned int reqsize;
192
193	spin_lock_init(&ctx->lock);
194
195	alignmask = crypto_tfm_ctx_alignment() - 1;
196	reqsize = sizeof(struct eseqiv_request_ctx);
197
198	if (alignmask & reqsize) {
199		alignmask &= reqsize;
200		alignmask--;
201	}
202
203	alignmask = ~alignmask;
204	alignmask &= crypto_ablkcipher_alignmask(geniv);
205
206	reqsize += alignmask;
207	reqsize += crypto_ablkcipher_ivsize(geniv);
208	reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment());
209
210	ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx);
211
212	tfm->crt_ablkcipher.reqsize = reqsize +
213				      sizeof(struct ablkcipher_request);
214
215	return skcipher_geniv_init(tfm);
216}
217
218static struct crypto_template eseqiv_tmpl;
219
220static struct crypto_instance *eseqiv_alloc(struct rtattr **tb)
221{
222	struct crypto_instance *inst;
223	int err;
224
225	err = crypto_get_default_rng();
226	if (err)
227		return ERR_PTR(err);
228
229	inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0);
230	if (IS_ERR(inst))
231		goto put_rng;
232
233	err = -EINVAL;
234	if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize)
235		goto free_inst;
236
237	inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first;
238
239	inst->alg.cra_init = eseqiv_init;
240	inst->alg.cra_exit = skcipher_geniv_exit;
241
242	inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx);
243	inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
244
245out:
246	return inst;
247
248free_inst:
249	skcipher_geniv_free(inst);
250	inst = ERR_PTR(err);
251put_rng:
252	crypto_put_default_rng();
253	goto out;
254}
255
256static void eseqiv_free(struct crypto_instance *inst)
257{
258	skcipher_geniv_free(inst);
259	crypto_put_default_rng();
260}
261
262static struct crypto_template eseqiv_tmpl = {
263	.name = "eseqiv",
264	.alloc = eseqiv_alloc,
265	.free = eseqiv_free,
266	.module = THIS_MODULE,
267};
268
269static int __init eseqiv_module_init(void)
270{
271	return crypto_register_template(&eseqiv_tmpl);
272}
273
274static void __exit eseqiv_module_exit(void)
275{
276	crypto_unregister_template(&eseqiv_tmpl);
277}
278
279module_init(eseqiv_module_init);
280module_exit(eseqiv_module_exit);
281
282MODULE_LICENSE("GPL");
283MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator");