[linux.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 <[email protected]>
 *
 * 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 void eseqiv_chain(struct scatterlist *head, struct scatterlist *sg,
			 int chain)
{
	if (chain) {
		head->length += sg->length;
		sg = scatterwalk_sg_next(sg);
	}

	if (sg)
		scatterwalk_sg_chain(head, 2, sg);
	else
		sg_mark_end(head);
}

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);
	eseqiv_chain(reqctx->src, osrc, vsrc == giv + ivsize);

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

		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 <[email protected]>
	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
	65	static 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
	79	static 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,
46f8153c HX	139	req->creq.nbytes + ivsize,
46f8153c HX	140	req->creq.info);
806d183a HX	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
abe5fa78 SK	156	if (giv != req->giv)
abe5fa78 SK	157	eseqiv_complete2(req);
806d183a HX	158
	159	out:
	160	return err;
	161	}
	162
	163	static 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);
a0f000ec	167	int err = 0;
806d183a HX	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;
a0f000ec HX	174	err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
a0f000ec HX	175	crypto_ablkcipher_ivsize(geniv));
806d183a HX	176
	177	unlock:
	178	spin_unlock_bh(&ctx->lock);
	179
a0f000ec HX	180	if (err)
	181	return err;
	182
806d183a HX	183	return eseqiv_givencrypt(req);
	184	}
	185
	186	static 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
	218	static struct crypto_template eseqiv_tmpl;
	219
	220	static struct crypto_instance eseqiv_alloc(struct rtattr *tb)
	221	{
	222	struct crypto_instance *inst;
	223	int err;
	224
a0f000ec HX	225	err = crypto_get_default_rng();
	226	if (err)
	227	return ERR_PTR(err);
	228
806d183a HX	229	inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0);
806d183a HX	230	if (IS_ERR(inst))
a0f000ec	231	goto put_rng;
806d183a HX	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
	245	out:
	246	return inst;
	247
	248	free_inst:
	249	skcipher_geniv_free(inst);
	250	inst = ERR_PTR(err);
a0f000ec HX	251	put_rng:
a0f000ec HX	252	crypto_put_default_rng();
806d183a HX	253	goto out;
	254	}
	255
a0f000ec HX	256	static void eseqiv_free(struct crypto_instance *inst)
	257	{
	258	skcipher_geniv_free(inst);
	259	crypto_put_default_rng();
	260	}
	261
806d183a HX	262	static struct crypto_template eseqiv_tmpl = {
	263	.name = "eseqiv",
	264	.alloc = eseqiv_alloc,
a0f000ec	265	.free = eseqiv_free,
806d183a HX	266	.module = THIS_MODULE,
	267	};
	268
5be5e667	269	static int __init eseqiv_module_init(void)
806d183a HX	270	{
	271	return crypto_register_template(&eseqiv_tmpl);
	272	}
	273
5be5e667	274	static void __exit eseqiv_module_exit(void)
806d183a HX	275	{
	276	crypto_unregister_template(&eseqiv_tmpl);
	277	}
5be5e667 HX	278
	279	module_init(eseqiv_module_init);
	280	module_exit(eseqiv_module_exit);
	281
	282	MODULE_LICENSE("GPL");
	283	MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator");