/*
 * AEAD: Authenticated Encryption with Associated Data
 * 
 * This file provides API support for AEAD algorithms.
 *
 * 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/aead.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/seq_file.h>

#include "internal.h"

static int setkey_unaligned(struct crypto_aead *tfm, const u8 *key,
			    unsigned int keylen)
{
	struct aead_alg *aead = crypto_aead_alg(tfm);
	unsigned long alignmask = crypto_aead_alignmask(tfm);
	int ret;
	u8 *buffer, *alignbuffer;
	unsigned long absize;

	absize = keylen + alignmask;
	buffer = kmalloc(absize, GFP_ATOMIC);
	if (!buffer)
		return -ENOMEM;

	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
	memcpy(alignbuffer, key, keylen);
	ret = aead->setkey(tfm, alignbuffer, keylen);
	memset(alignbuffer, 0, keylen);
	kfree(buffer);
	return ret;
}

static int setkey(struct crypto_aead *tfm, const u8 *key, unsigned int keylen)
{
	struct aead_alg *aead = crypto_aead_alg(tfm);
	unsigned long alignmask = crypto_aead_alignmask(tfm);

	if ((unsigned long)key & alignmask)
		return setkey_unaligned(tfm, key, keylen);

	return aead->setkey(tfm, key, keylen);
}

int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
	struct aead_tfm *crt = crypto_aead_crt(tfm);
	int err;

	if (authsize > crypto_aead_alg(tfm)->maxauthsize)
		return -EINVAL;

	if (crypto_aead_alg(tfm)->setauthsize) {
		err = crypto_aead_alg(tfm)->setauthsize(crt->base, authsize);
		if (err)
			return err;
	}

	crypto_aead_crt(crt->base)->authsize = authsize;
	crt->authsize = authsize;
	return 0;
}
EXPORT_SYMBOL_GPL(crypto_aead_setauthsize);

static unsigned int crypto_aead_ctxsize(struct crypto_alg *alg, u32 type,
					u32 mask)
{
	return alg->cra_ctxsize;
}

static int no_givcrypt(struct aead_givcrypt_request *req)
{
	return -ENOSYS;
}

static int crypto_init_aead_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
{
	struct aead_alg *alg = &tfm->__crt_alg->cra_aead;
	struct aead_tfm *crt = &tfm->crt_aead;

	if (max(alg->maxauthsize, alg->ivsize) > PAGE_SIZE / 8)
		return -EINVAL;

	crt->setkey = tfm->__crt_alg->cra_flags & CRYPTO_ALG_GENIV ?
		      alg->setkey : setkey;
	crt->encrypt = alg->encrypt;
	crt->decrypt = alg->decrypt;
	crt->givencrypt = alg->givencrypt ?: no_givcrypt;
	crt->givdecrypt = alg->givdecrypt ?: no_givcrypt;
	crt->base = __crypto_aead_cast(tfm);
	crt->ivsize = alg->ivsize;
	crt->authsize = alg->maxauthsize;

	return 0;
}

static void crypto_aead_show(struct seq_file *m, struct crypto_alg *alg)
	__attribute__ ((unused));
static void crypto_aead_show(struct seq_file *m, struct crypto_alg *alg)
{
	struct aead_alg *aead = &alg->cra_aead;

	seq_printf(m, "type         : aead\n");
	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
	seq_printf(m, "ivsize       : %u\n", aead->ivsize);
	seq_printf(m, "maxauthsize  : %u\n", aead->maxauthsize);
	seq_printf(m, "geniv        : %s\n", aead->geniv ?: "<built-in>");
}

const struct crypto_type crypto_aead_type = {
	.ctxsize = crypto_aead_ctxsize,
	.init = crypto_init_aead_ops,
#ifdef CONFIG_PROC_FS
	.show = crypto_aead_show,
#endif
};
EXPORT_SYMBOL_GPL(crypto_aead_type);

static int aead_null_givencrypt(struct aead_givcrypt_request *req)
{
	return crypto_aead_encrypt(&req->areq);
}

static int aead_null_givdecrypt(struct aead_givcrypt_request *req)
{
	return crypto_aead_decrypt(&req->areq);
}

static int crypto_init_nivaead_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
{
	struct aead_alg *alg = &tfm->__crt_alg->cra_aead;
	struct aead_tfm *crt = &tfm->crt_aead;

	if (max(alg->maxauthsize, alg->ivsize) > PAGE_SIZE / 8)
		return -EINVAL;

	crt->setkey = setkey;
	crt->encrypt = alg->encrypt;
	crt->decrypt = alg->decrypt;
	if (!alg->ivsize) {
		crt->givencrypt = aead_null_givencrypt;
		crt->givdecrypt = aead_null_givdecrypt;
	}
	crt->base = __crypto_aead_cast(tfm);
	crt->ivsize = alg->ivsize;
	crt->authsize = alg->maxauthsize;

	return 0;
}

static void crypto_nivaead_show(struct seq_file *m, struct crypto_alg *alg)
	__attribute__ ((unused));
static void crypto_nivaead_show(struct seq_file *m, struct crypto_alg *alg)
{
	struct aead_alg *aead = &alg->cra_aead;

	seq_printf(m, "type         : nivaead\n");
	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
	seq_printf(m, "ivsize       : %u\n", aead->ivsize);
	seq_printf(m, "maxauthsize  : %u\n", aead->maxauthsize);
	seq_printf(m, "geniv        : %s\n", aead->geniv);
}

const struct crypto_type crypto_nivaead_type = {
	.ctxsize = crypto_aead_ctxsize,
	.init = crypto_init_nivaead_ops,
#ifdef CONFIG_PROC_FS
	.show = crypto_nivaead_show,
#endif
};
EXPORT_SYMBOL_GPL(crypto_nivaead_type);

static int crypto_grab_nivaead(struct crypto_aead_spawn *spawn,
			       const char *name, u32 type, u32 mask)
{
	struct crypto_alg *alg;
	int err;

	type &= ~(CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV);
	type |= CRYPTO_ALG_TYPE_AEAD;
	mask |= CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV;

	alg = crypto_alg_mod_lookup(name, type, mask);
	if (IS_ERR(alg))
		return PTR_ERR(alg);

	err = crypto_init_spawn(&spawn->base, alg, spawn->base.inst, mask);
	crypto_mod_put(alg);
	return err;
}

struct crypto_instance *aead_geniv_alloc(struct crypto_template *tmpl,
					 struct rtattr **tb, u32 type,
					 u32 mask)
{
	const char *name;
	struct crypto_aead_spawn *spawn;
	struct crypto_attr_type *algt;
	struct crypto_instance *inst;
	struct crypto_alg *alg;
	int err;

	algt = crypto_get_attr_type(tb);
	err = PTR_ERR(algt);
	if (IS_ERR(algt))
		return ERR_PTR(err);

	if ((algt->type ^ (CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_GENIV)) &
	    algt->mask)
		return ERR_PTR(-EINVAL);

	name = crypto_attr_alg_name(tb[1]);
	err = PTR_ERR(name);
	if (IS_ERR(name))
		return ERR_PTR(err);

	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
	if (!inst)
		return ERR_PTR(-ENOMEM);

	spawn = crypto_instance_ctx(inst);

	/* Ignore async algorithms if necessary. */
	mask |= crypto_requires_sync(algt->type, algt->mask);

	crypto_set_aead_spawn(spawn, inst);
	err = crypto_grab_nivaead(spawn, name, type, mask);
	if (err)
		goto err_free_inst;

	alg = crypto_aead_spawn_alg(spawn);

	err = -EINVAL;
	if (!alg->cra_aead.ivsize)
		goto err_drop_alg;

	/*
	 * This is only true if we're constructing an algorithm with its
	 * default IV generator.  For the default generator we elide the
	 * template name and double-check the IV generator.
	 */
	if (algt->mask & CRYPTO_ALG_GENIV) {
		if (strcmp(tmpl->name, alg->cra_aead.geniv))
			goto err_drop_alg;

		memcpy(inst->alg.cra_name, alg->cra_name, CRYPTO_MAX_ALG_NAME);
		memcpy(inst->alg.cra_driver_name, alg->cra_driver_name,
		       CRYPTO_MAX_ALG_NAME);
	} else {
		err = -ENAMETOOLONG;
		if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
			     "%s(%s)", tmpl->name, alg->cra_name) >=
		    CRYPTO_MAX_ALG_NAME)
			goto err_drop_alg;
		if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
			     "%s(%s)", tmpl->name, alg->cra_driver_name) >=
		    CRYPTO_MAX_ALG_NAME)
			goto err_drop_alg;
	}

	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_GENIV;
	inst->alg.cra_flags |= alg->cra_flags & CRYPTO_ALG_ASYNC;
	inst->alg.cra_priority = alg->cra_priority;
	inst->alg.cra_blocksize = alg->cra_blocksize;
	inst->alg.cra_alignmask = alg->cra_alignmask;
	inst->alg.cra_type = &crypto_aead_type;

	inst->alg.cra_aead.ivsize = alg->cra_aead.ivsize;
	inst->alg.cra_aead.maxauthsize = alg->cra_aead.maxauthsize;
	inst->alg.cra_aead.geniv = alg->cra_aead.geniv;

	inst->alg.cra_aead.setkey = alg->cra_aead.setkey;
	inst->alg.cra_aead.setauthsize = alg->cra_aead.setauthsize;
	inst->alg.cra_aead.encrypt = alg->cra_aead.encrypt;
	inst->alg.cra_aead.decrypt = alg->cra_aead.decrypt;

out:
	return inst;

err_drop_alg:
	crypto_drop_aead(spawn);
err_free_inst:
	kfree(inst);
	inst = ERR_PTR(err);
	goto out;
}
EXPORT_SYMBOL_GPL(aead_geniv_alloc);

void aead_geniv_free(struct crypto_instance *inst)
{
	crypto_drop_aead(crypto_instance_ctx(inst));
	kfree(inst);
}
EXPORT_SYMBOL_GPL(aead_geniv_free);

int aead_geniv_init(struct crypto_tfm *tfm)
{
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
	struct crypto_aead *aead;

	aead = crypto_spawn_aead(crypto_instance_ctx(inst));
	if (IS_ERR(aead))
		return PTR_ERR(aead);

	tfm->crt_aead.base = aead;
	tfm->crt_aead.reqsize += crypto_aead_reqsize(aead);

	return 0;
}
EXPORT_SYMBOL_GPL(aead_geniv_init);

void aead_geniv_exit(struct crypto_tfm *tfm)
{
	crypto_free_aead(tfm->crt_aead.base);
}
EXPORT_SYMBOL_GPL(aead_geniv_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Authenticated Encryption with Associated Data (AEAD)");