[linux-2.6-block.git] / crypto / eseqiv.c

/*
 * eseqiv: Encrypted Sequence Number IV Generator
 *
 * This generator generates an IV based on a sequence number by xoring it
 * with a salt and then encrypting it with the same key as used to encrypt
 * the plain text.  This algorithm requires that the block size be equal
 * to the IV size.  It is mainly useful for CBC.
 *
 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#include <crypto/internal/skcipher.h>
#include <crypto/rng.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/spinlock.h>
#include <linux/string.h>

struct eseqiv_request_ctx {
	struct scatterlist src[2];
	struct scatterlist dst[2];
	char tail[];
};

struct eseqiv_ctx {
	spinlock_t lock;
	unsigned int reqoff;
	char salt[];
};

static void eseqiv_complete2(struct skcipher_givcrypt_request *req)
{
	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
	struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);

	memcpy(req->giv, PTR_ALIGN((u8 *)reqctx->tail,
			 crypto_ablkcipher_alignmask(geniv) + 1),
	       crypto_ablkcipher_ivsize(geniv));
}

static void eseqiv_complete(struct crypto_async_request *base, int err)
{
	struct skcipher_givcrypt_request *req = base->data;

	if (err)
		goto out;

	eseqiv_complete2(req);

out:
	skcipher_givcrypt_complete(req, err);
}

static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req)
{
	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
	struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
	struct ablkcipher_request *subreq;
	crypto_completion_t complete;
	void *data;
	struct scatterlist *osrc, *odst;
	struct scatterlist *dst;
	struct page *srcp;
	struct page *dstp;
	u8 *giv;
	u8 *vsrc;
	u8 *vdst;
	__be64 seq;
	unsigned int ivsize;
	unsigned int len;
	int err;

	subreq = (void *)(reqctx->tail + ctx->reqoff);
	ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));

	giv = req->giv;
	complete = req->creq.base.complete;
	data = req->creq.base.data;

	osrc = req->creq.src;
	odst = req->creq.dst;
	srcp = sg_page(osrc);
	dstp = sg_page(odst);
	vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset;
	vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset;

	ivsize = crypto_ablkcipher_ivsize(geniv);

	if (vsrc != giv + ivsize && vdst != giv + ivsize) {
		giv = PTR_ALIGN((u8 *)reqctx->tail,
				crypto_ablkcipher_alignmask(geniv) + 1);
		complete = eseqiv_complete;
		data = req;
	}

	ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete,
					data);

	sg_init_table(reqctx->src, 2);
	sg_set_buf(reqctx->src, giv, ivsize);
	scatterwalk_crypto_chain(reqctx->src, osrc, vsrc == giv + ivsize, 2);

	dst = reqctx->src;
	if (osrc != odst) {
		sg_init_table(reqctx->dst, 2);
		sg_set_buf(reqctx->dst, giv, ivsize);
		scatterwalk_crypto_chain(reqctx->dst, odst, vdst == giv + ivsize, 2);

		dst = reqctx->dst;
	}

	ablkcipher_request_set_crypt(subreq, reqctx->src, dst,
				     req->creq.nbytes + ivsize,
				     req->creq.info);

	memcpy(req->creq.info, ctx->salt, ivsize);

	len = ivsize;
	if (ivsize > sizeof(u64)) {
		memset(req->giv, 0, ivsize - sizeof(u64));
		len = sizeof(u64);
	}
	seq = cpu_to_be64(req->seq);
	memcpy(req->giv + ivsize - len, &seq, len);

	err = crypto_ablkcipher_encrypt(subreq);
	if (err)
		goto out;

	if (giv != req->giv)
		eseqiv_complete2(req);

out:
	return err;
}

static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req)
{
	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
	int err = 0;

	spin_lock_bh(&ctx->lock);
	if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first)
		goto unlock;

	crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt;
	err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
				   crypto_ablkcipher_ivsize(geniv));

unlock:
	spin_unlock_bh(&ctx->lock);

	if (err)
		return err;

	return eseqiv_givencrypt(req);
}

static int eseqiv_init(struct crypto_tfm *tfm)
{
	struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
	unsigned long alignmask;
	unsigned int reqsize;

	spin_lock_init(&ctx->lock);

	alignmask = crypto_tfm_ctx_alignment() - 1;
	reqsize = sizeof(struct eseqiv_request_ctx);

	if (alignmask & reqsize) {
		alignmask &= reqsize;
		alignmask--;
	}

	alignmask = ~alignmask;
	alignmask &= crypto_ablkcipher_alignmask(geniv);

	reqsize += alignmask;
	reqsize += crypto_ablkcipher_ivsize(geniv);
	reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment());

	ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx);

	tfm->crt_ablkcipher.reqsize = reqsize +
				      sizeof(struct ablkcipher_request);

	return skcipher_geniv_init(tfm);
}

static struct crypto_template eseqiv_tmpl;

static struct crypto_instance *eseqiv_alloc(struct rtattr **tb)
{
	struct crypto_instance *inst;
	int err;

	err = crypto_get_default_rng();
	if (err)
		return ERR_PTR(err);

	inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0);
	if (IS_ERR(inst))
		goto put_rng;

	err = -EINVAL;
	if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize)
		goto free_inst;

	inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first;

	inst->alg.cra_init = eseqiv_init;
	inst->alg.cra_exit = skcipher_geniv_exit;

	inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx);
	inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;

out:
	return inst;

free_inst:
	skcipher_geniv_free(inst);
	inst = ERR_PTR(err);
put_rng:
	crypto_put_default_rng();
	goto out;
}

static void eseqiv_free(struct crypto_instance *inst)
{
	skcipher_geniv_free(inst);
	crypto_put_default_rng();
}

static struct crypto_template eseqiv_tmpl = {
	.name = "eseqiv",
	.alloc = eseqiv_alloc,
	.free = eseqiv_free,
	.module = THIS_MODULE,
};

static int __init eseqiv_module_init(void)
{
	return crypto_register_template(&eseqiv_tmpl);
}

static void __exit eseqiv_module_exit(void)
{
	crypto_unregister_template(&eseqiv_tmpl);
}

module_init(eseqiv_module_init);
module_exit(eseqiv_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator");
Commit	Line	Data
806d183a HX	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>
a0f000ec	19	#include <crypto/rng.h>
806d183a HX	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>
806d183a HX	26	#include <linux/scatterlist.h>
	27	#include <linux/spinlock.h>
	28	#include <linux/string.h>
	29
	30	struct eseqiv_request_ctx {
	31	struct scatterlist src[2];
	32	struct scatterlist dst[2];
	33	char tail[];
	34	};
	35
	36	struct eseqiv_ctx {
	37	spinlock_t lock;
	38	unsigned int reqoff;
	39	char salt[];
	40	};
	41
	42	static 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
	52	static 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
	61	out:
	62	skcipher_givcrypt_complete(req, err);
	63	}
	64
806d183a HX	65	static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req)
	66	{
	67	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
	68	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
	69	struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
	70	struct ablkcipher_request *subreq;
	71	crypto_completion_t complete;
	72	void *data;
	73	struct scatterlist osrc, odst;
	74	struct scatterlist *dst;
	75	struct page *srcp;
	76	struct page *dstp;
	77	u8 *giv;
	78	u8 *vsrc;
	79	u8 *vdst;
	80	__be64 seq;
	81	unsigned int ivsize;
	82	unsigned int len;
	83	int err;
	84
	85	subreq = (void *)(reqctx->tail + ctx->reqoff);
	86	ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
	87
	88	giv = req->giv;
	89	complete = req->creq.base.complete;
	90	data = req->creq.base.data;
	91
	92	osrc = req->creq.src;
	93	odst = req->creq.dst;
	94	srcp = sg_page(osrc);
	95	dstp = sg_page(odst);
	96	vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset;
	97	vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset;
	98
	99	ivsize = crypto_ablkcipher_ivsize(geniv);
	100
	101	if (vsrc != giv + ivsize && vdst != giv + ivsize) {
	102	giv = PTR_ALIGN((u8 *)reqctx->tail,
	103	crypto_ablkcipher_alignmask(geniv) + 1);
	104	complete = eseqiv_complete;
	105	data = req;
	106	}
	107
	108	ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete,
	109	data);
	110
	111	sg_init_table(reqctx->src, 2);
	112	sg_set_buf(reqctx->src, giv, ivsize);
c920fa60	113	scatterwalk_crypto_chain(reqctx->src, osrc, vsrc == giv + ivsize, 2);
806d183a HX	114
	115	dst = reqctx->src;
	116	if (osrc != odst) {
	117	sg_init_table(reqctx->dst, 2);
	118	sg_set_buf(reqctx->dst, giv, ivsize);
c920fa60	119	scatterwalk_crypto_chain(reqctx->dst, odst, vdst == giv + ivsize, 2);
806d183a HX	120
	121	dst = reqctx->dst;
	122	}
	123
	124	ablkcipher_request_set_crypt(subreq, reqctx->src, dst,
46f8153c HX	125	req->creq.nbytes + ivsize,
46f8153c HX	126	req->creq.info);
806d183a HX	127
	128	memcpy(req->creq.info, ctx->salt, ivsize);
	129
	130	len = ivsize;
	131	if (ivsize > sizeof(u64)) {
	132	memset(req->giv, 0, ivsize - sizeof(u64));
	133	len = sizeof(u64);
	134	}
	135	seq = cpu_to_be64(req->seq);
	136	memcpy(req->giv + ivsize - len, &seq, len);
	137
	138	err = crypto_ablkcipher_encrypt(subreq);
	139	if (err)
	140	goto out;
	141
abe5fa78 SK	142	if (giv != req->giv)
abe5fa78 SK	143	eseqiv_complete2(req);
806d183a HX	144
	145	out:
	146	return err;
	147	}
	148
	149	static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req)
	150	{
	151	struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
	152	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
a0f000ec	153	int err = 0;
806d183a HX	154
	155	spin_lock_bh(&ctx->lock);
	156	if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first)
	157	goto unlock;
	158
	159	crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt;
a0f000ec HX	160	err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
a0f000ec HX	161	crypto_ablkcipher_ivsize(geniv));
806d183a HX	162
	163	unlock:
	164	spin_unlock_bh(&ctx->lock);
	165
a0f000ec HX	166	if (err)
	167	return err;
	168
806d183a HX	169	return eseqiv_givencrypt(req);
	170	}
	171
	172	static int eseqiv_init(struct crypto_tfm *tfm)
	173	{
	174	struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
	175	struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
	176	unsigned long alignmask;
	177	unsigned int reqsize;
	178
	179	spin_lock_init(&ctx->lock);
	180
	181	alignmask = crypto_tfm_ctx_alignment() - 1;
	182	reqsize = sizeof(struct eseqiv_request_ctx);
	183
	184	if (alignmask & reqsize) {
	185	alignmask &= reqsize;
	186	alignmask--;
	187	}
	188
	189	alignmask = ~alignmask;
	190	alignmask &= crypto_ablkcipher_alignmask(geniv);
	191
	192	reqsize += alignmask;
	193	reqsize += crypto_ablkcipher_ivsize(geniv);
	194	reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment());
	195
	196	ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx);
	197
	198	tfm->crt_ablkcipher.reqsize = reqsize +
	199	sizeof(struct ablkcipher_request);
	200
	201	return skcipher_geniv_init(tfm);
	202	}
	203
	204	static struct crypto_template eseqiv_tmpl;
	205
	206	static struct crypto_instance eseqiv_alloc(struct rtattr *tb)
	207	{
	208	struct crypto_instance *inst;
	209	int err;
	210
a0f000ec HX	211	err = crypto_get_default_rng();
	212	if (err)
	213	return ERR_PTR(err);
	214
806d183a HX	215	inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0);
806d183a HX	216	if (IS_ERR(inst))
a0f000ec	217	goto put_rng;
806d183a HX	218
	219	err = -EINVAL;
	220	if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize)
	221	goto free_inst;
	222
	223	inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first;
	224
	225	inst->alg.cra_init = eseqiv_init;
	226	inst->alg.cra_exit = skcipher_geniv_exit;
	227
	228	inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx);
	229	inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
	230
	231	out:
	232	return inst;
	233
	234	free_inst:
	235	skcipher_geniv_free(inst);
	236	inst = ERR_PTR(err);
a0f000ec HX	237	put_rng:
a0f000ec HX	238	crypto_put_default_rng();
806d183a HX	239	goto out;
	240	}
	241
a0f000ec HX	242	static void eseqiv_free(struct crypto_instance *inst)
	243	{
	244	skcipher_geniv_free(inst);
	245	crypto_put_default_rng();
	246	}
	247
806d183a HX	248	static struct crypto_template eseqiv_tmpl = {
	249	.name = "eseqiv",
	250	.alloc = eseqiv_alloc,
a0f000ec	251	.free = eseqiv_free,
806d183a HX	252	.module = THIS_MODULE,
	253	};
	254
5be5e667	255	static int __init eseqiv_module_init(void)
806d183a HX	256	{
	257	return crypto_register_template(&eseqiv_tmpl);
	258	}
	259
5be5e667	260	static void __exit eseqiv_module_exit(void)
806d183a HX	261	{
	262	crypto_unregister_template(&eseqiv_tmpl);
	263	}
5be5e667 HX	264
	265	module_init(eseqiv_module_init);
	266	module_exit(eseqiv_module_exit);
	267
	268	MODULE_LICENSE("GPL");
	269	MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator");