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

/*
 * echainiv: Encrypted Chain 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.
 *
 * This generator can only be used by algorithms where authentication
 * is performed after encryption (i.e., authenc).
 *
 * Copyright (c) 2015 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/geniv.h>
#include <crypto/scatterwalk.h>
#include <crypto/skcipher.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/spinlock.h>
#include <linux/string.h>

#define MAX_IV_SIZE 16

static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv);

/* We don't care if we get preempted and read/write IVs from the next CPU. */
static void echainiv_read_iv(u8 *dst, unsigned size)
{
	u32 *a = (u32 *)dst;
	u32 __percpu *b = echainiv_iv;

	for (; size >= 4; size -= 4) {
		*a++ = this_cpu_read(*b);
		b++;
	}
}

static void echainiv_write_iv(const u8 *src, unsigned size)
{
	const u32 *a = (const u32 *)src;
	u32 __percpu *b = echainiv_iv;

	for (; size >= 4; size -= 4) {
		this_cpu_write(*b, *a);
		a++;
		b++;
	}
}

static void echainiv_encrypt_complete2(struct aead_request *req, int err)
{
	struct aead_request *subreq = aead_request_ctx(req);
	struct crypto_aead *geniv;
	unsigned int ivsize;

	if (err == -EINPROGRESS)
		return;

	if (err)
		goto out;

	geniv = crypto_aead_reqtfm(req);
	ivsize = crypto_aead_ivsize(geniv);

	echainiv_write_iv(subreq->iv, ivsize);

	if (req->iv != subreq->iv)
		memcpy(req->iv, subreq->iv, ivsize);

out:
	if (req->iv != subreq->iv)
		kzfree(subreq->iv);
}

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

	echainiv_encrypt_complete2(req, err);
	aead_request_complete(req, err);
}

static int echainiv_encrypt(struct aead_request *req)
{
	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
	struct aead_request *subreq = aead_request_ctx(req);
	crypto_completion_t compl;
	void *data;
	u8 *info;
	unsigned int ivsize = crypto_aead_ivsize(geniv);
	int err;

	if (req->cryptlen < ivsize)
		return -EINVAL;

	aead_request_set_tfm(subreq, ctx->child);

	compl = echainiv_encrypt_complete;
	data = req;
	info = req->iv;

	if (req->src != req->dst) {
		SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);

		skcipher_request_set_tfm(nreq, ctx->sknull);
		skcipher_request_set_callback(nreq, req->base.flags,
					      NULL, NULL);
		skcipher_request_set_crypt(nreq, req->src, req->dst,
					   req->assoclen + req->cryptlen,
					   NULL);

		err = crypto_skcipher_encrypt(nreq);
		if (err)
			return err;
	}

	if (unlikely(!IS_ALIGNED((unsigned long)info,
				 crypto_aead_alignmask(geniv) + 1))) {
		info = kmalloc(ivsize, req->base.flags &
				       CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
								  GFP_ATOMIC);
		if (!info)
			return -ENOMEM;

		memcpy(info, req->iv, ivsize);
	}

	aead_request_set_callback(subreq, req->base.flags, compl, data);
	aead_request_set_crypt(subreq, req->dst, req->dst,
			       req->cryptlen, info);
	aead_request_set_ad(subreq, req->assoclen);

	crypto_xor(info, ctx->salt, ivsize);
	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
	echainiv_read_iv(info, ivsize);

	err = crypto_aead_encrypt(subreq);
	echainiv_encrypt_complete2(req, err);
	return err;
}

static int echainiv_decrypt(struct aead_request *req)
{
	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
	struct aead_request *subreq = aead_request_ctx(req);
	crypto_completion_t compl;
	void *data;
	unsigned int ivsize = crypto_aead_ivsize(geniv);

	if (req->cryptlen < ivsize)
		return -EINVAL;

	aead_request_set_tfm(subreq, ctx->child);

	compl = req->base.complete;
	data = req->base.data;

	aead_request_set_callback(subreq, req->base.flags, compl, data);
	aead_request_set_crypt(subreq, req->src, req->dst,
			       req->cryptlen - ivsize, req->iv);
	aead_request_set_ad(subreq, req->assoclen + ivsize);

	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);

	return crypto_aead_decrypt(subreq);
}

static int echainiv_aead_create(struct crypto_template *tmpl,
				struct rtattr **tb)
{
	struct aead_instance *inst;
	struct crypto_aead_spawn *spawn;
	struct aead_alg *alg;
	int err;

	inst = aead_geniv_alloc(tmpl, tb, 0, 0);

	if (IS_ERR(inst))
		return PTR_ERR(inst);

	spawn = aead_instance_ctx(inst);
	alg = crypto_spawn_aead_alg(spawn);

	err = -EINVAL;
	if (inst->alg.ivsize & (sizeof(u32) - 1) ||
	    inst->alg.ivsize > MAX_IV_SIZE)
		goto free_inst;

	inst->alg.encrypt = echainiv_encrypt;
	inst->alg.decrypt = echainiv_decrypt;

	inst->alg.init = aead_init_geniv;
	inst->alg.exit = aead_exit_geniv;

	inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
	inst->alg.base.cra_ctxsize += inst->alg.ivsize;

	inst->free = aead_geniv_free;

	err = aead_register_instance(tmpl, inst);
	if (err)
		goto free_inst;

out:
	return err;

free_inst:
	aead_geniv_free(inst);
	goto out;
}

static void echainiv_free(struct crypto_instance *inst)
{
	aead_geniv_free(aead_instance(inst));
}

static struct crypto_template echainiv_tmpl = {
	.name = "echainiv",
	.create = echainiv_aead_create,
	.free = echainiv_free,
	.module = THIS_MODULE,
};

static int __init echainiv_module_init(void)
{
	return crypto_register_template(&echainiv_tmpl);
}

static void __exit echainiv_module_exit(void)
{
	crypto_unregister_template(&echainiv_tmpl);
}

module_init(echainiv_module_init);
module_exit(echainiv_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Encrypted Chain IV Generator");
MODULE_ALIAS_CRYPTO("echainiv");
Commit	Line	Data
	1	/*
	2	* echainiv: Encrypted Chain 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	* This generator can only be used by algorithms where authentication
	10	* is performed after encryption (i.e., authenc).
	11	*
	12	* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
	13	*
	14	* This program is free software; you can redistribute it and/or modify it
	15	* under the terms of the GNU General Public License as published by the Free
	16	* Software Foundation; either version 2 of the License, or (at your option)
	17	* any later version.
	18	*
	19	*/
	20
	21	#include <crypto/internal/geniv.h>
	22	#include <crypto/scatterwalk.h>
	23	#include <crypto/skcipher.h>
	24	#include <linux/err.h>
	25	#include <linux/init.h>
	26	#include <linux/kernel.h>
	27	#include <linux/mm.h>
	28	#include <linux/module.h>
	29	#include <linux/percpu.h>
	30	#include <linux/spinlock.h>
	31	#include <linux/string.h>
	32
	33	#define MAX_IV_SIZE 16
	34
	35	static DEFINE_PER_CPU(u32 [MAX_IV_SIZE / sizeof(u32)], echainiv_iv);
	36
	37	/* We don't care if we get preempted and read/write IVs from the next CPU. */
	38	static void echainiv_read_iv(u8 *dst, unsigned size)
	39	{
	40	u32 a = (u32 )dst;
	41	u32 __percpu *b = echainiv_iv;
	42
	43	for (; size >= 4; size -= 4) {
	44	a++ = this_cpu_read(b);
	45	b++;
	46	}
	47	}
	48
	49	static void echainiv_write_iv(const u8 *src, unsigned size)
	50	{
	51	const u32 a = (const u32 )src;
	52	u32 __percpu *b = echainiv_iv;
	53
	54	for (; size >= 4; size -= 4) {
	55	this_cpu_write(b, a);
	56	a++;
	57	b++;
	58	}
	59	}
	60
	61	static void echainiv_encrypt_complete2(struct aead_request *req, int err)
	62	{
	63	struct aead_request *subreq = aead_request_ctx(req);
	64	struct crypto_aead *geniv;
	65	unsigned int ivsize;
	66
	67	if (err == -EINPROGRESS)
	68	return;
	69
	70	if (err)
	71	goto out;
	72
	73	geniv = crypto_aead_reqtfm(req);
	74	ivsize = crypto_aead_ivsize(geniv);
	75
	76	echainiv_write_iv(subreq->iv, ivsize);
	77
	78	if (req->iv != subreq->iv)
	79	memcpy(req->iv, subreq->iv, ivsize);
	80
	81	out:
	82	if (req->iv != subreq->iv)
	83	kzfree(subreq->iv);
	84	}
	85
	86	static void echainiv_encrypt_complete(struct crypto_async_request *base,
	87	int err)
	88	{
	89	struct aead_request *req = base->data;
	90
	91	echainiv_encrypt_complete2(req, err);
	92	aead_request_complete(req, err);
	93	}
	94
	95	static int echainiv_encrypt(struct aead_request *req)
	96	{
	97	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
	98	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
	99	struct aead_request *subreq = aead_request_ctx(req);
	100	crypto_completion_t compl;
	101	void *data;
	102	u8 *info;
	103	unsigned int ivsize = crypto_aead_ivsize(geniv);
	104	int err;
	105
	106	if (req->cryptlen < ivsize)
	107	return -EINVAL;
	108
	109	aead_request_set_tfm(subreq, ctx->child);
	110
	111	compl = echainiv_encrypt_complete;
	112	data = req;
	113	info = req->iv;
	114
	115	if (req->src != req->dst) {
	116	SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
	117
	118	skcipher_request_set_tfm(nreq, ctx->sknull);
	119	skcipher_request_set_callback(nreq, req->base.flags,
	120	NULL, NULL);
	121	skcipher_request_set_crypt(nreq, req->src, req->dst,
	122	req->assoclen + req->cryptlen,
	123	NULL);
	124
	125	err = crypto_skcipher_encrypt(nreq);
	126	if (err)
	127	return err;
	128	}
	129
	130	if (unlikely(!IS_ALIGNED((unsigned long)info,
	131	crypto_aead_alignmask(geniv) + 1))) {
	132	info = kmalloc(ivsize, req->base.flags &
	133	CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
	134	GFP_ATOMIC);
	135	if (!info)
	136	return -ENOMEM;
	137
	138	memcpy(info, req->iv, ivsize);
	139	}
	140
	141	aead_request_set_callback(subreq, req->base.flags, compl, data);
	142	aead_request_set_crypt(subreq, req->dst, req->dst,
	143	req->cryptlen, info);
	144	aead_request_set_ad(subreq, req->assoclen);
	145
	146	crypto_xor(info, ctx->salt, ivsize);
	147	scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
	148	echainiv_read_iv(info, ivsize);
	149
	150	err = crypto_aead_encrypt(subreq);
	151	echainiv_encrypt_complete2(req, err);
	152	return err;
	153	}
	154
	155	static int echainiv_decrypt(struct aead_request *req)
	156	{
	157	struct crypto_aead *geniv = crypto_aead_reqtfm(req);
	158	struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
	159	struct aead_request *subreq = aead_request_ctx(req);
	160	crypto_completion_t compl;
	161	void *data;
	162	unsigned int ivsize = crypto_aead_ivsize(geniv);
	163
	164	if (req->cryptlen < ivsize)
	165	return -EINVAL;
	166
	167	aead_request_set_tfm(subreq, ctx->child);
	168
	169	compl = req->base.complete;
	170	data = req->base.data;
	171
	172	aead_request_set_callback(subreq, req->base.flags, compl, data);
	173	aead_request_set_crypt(subreq, req->src, req->dst,
	174	req->cryptlen - ivsize, req->iv);
	175	aead_request_set_ad(subreq, req->assoclen + ivsize);
	176
	177	scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
	178
	179	return crypto_aead_decrypt(subreq);
	180	}
	181
	182	static int echainiv_aead_create(struct crypto_template *tmpl,
	183	struct rtattr **tb)
	184	{
	185	struct aead_instance *inst;
	186	struct crypto_aead_spawn *spawn;
	187	struct aead_alg *alg;
	188	int err;
	189
	190	inst = aead_geniv_alloc(tmpl, tb, 0, 0);
	191
	192	if (IS_ERR(inst))
	193	return PTR_ERR(inst);
	194
	195	spawn = aead_instance_ctx(inst);
	196	alg = crypto_spawn_aead_alg(spawn);
	197
	198	err = -EINVAL;
	199	if (inst->alg.ivsize & (sizeof(u32) - 1) \|\|
	200	inst->alg.ivsize > MAX_IV_SIZE)
	201	goto free_inst;
	202
	203	inst->alg.encrypt = echainiv_encrypt;
	204	inst->alg.decrypt = echainiv_decrypt;
	205
	206	inst->alg.init = aead_init_geniv;
	207	inst->alg.exit = aead_exit_geniv;
	208
	209	inst->alg.base.cra_alignmask \|= __alignof__(u32) - 1;
	210	inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
	211	inst->alg.base.cra_ctxsize += inst->alg.ivsize;
	212
	213	inst->free = aead_geniv_free;
	214
	215	err = aead_register_instance(tmpl, inst);
	216	if (err)
	217	goto free_inst;
	218
	219	out:
	220	return err;
	221
	222	free_inst:
	223	aead_geniv_free(inst);
	224	goto out;
	225	}
	226
	227	static void echainiv_free(struct crypto_instance *inst)
	228	{
	229	aead_geniv_free(aead_instance(inst));
	230	}
	231
	232	static struct crypto_template echainiv_tmpl = {
	233	.name = "echainiv",
	234	.create = echainiv_aead_create,
	235	.free = echainiv_free,
	236	.module = THIS_MODULE,
	237	};
	238
	239	static int __init echainiv_module_init(void)
	240	{
	241	return crypto_register_template(&echainiv_tmpl);
	242	}
	243
	244	static void __exit echainiv_module_exit(void)
	245	{
	246	crypto_unregister_template(&echainiv_tmpl);
	247	}
	248
	249	module_init(echainiv_module_init);
	250	module_exit(echainiv_module_exit);
	251
	252	MODULE_LICENSE("GPL");
	253	MODULE_DESCRIPTION("Encrypted Chain IV Generator");
	254	MODULE_ALIAS_CRYPTO("echainiv");