path: root/crypto/gcm.c

/*
 * GCM: Galois/Counter Mode.
 *
 * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include <crypto/gf128mul.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/internal/hash.h>
#include <crypto/scatterwalk.h>
#include <crypto/hash.h>
#include "internal.h"
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>

struct gcm_instance_ctx {
	struct crypto_skcipher_spawn ctr;
	struct crypto_ahash_spawn ghash;
};

struct crypto_gcm_ctx {
	struct crypto_ablkcipher *ctr;
	struct crypto_ahash *ghash;
};

struct crypto_rfc4106_ctx {
	struct crypto_aead *child;
	u8 nonce[4];
};

struct crypto_gcm_ghash_ctx {
	unsigned int cryptlen;
	struct scatterlist *src;
	crypto_completion_t complete;
};

struct crypto_gcm_req_priv_ctx {
	u8 auth_tag[16];
	u8 iauth_tag[16];
	struct scatterlist src[2];
	struct scatterlist dst[2];
	struct crypto_gcm_ghash_ctx ghash_ctx;
	union {
		struct ahash_request ahreq;
		struct ablkcipher_request abreq;
	} u;
};

struct crypto_gcm_setkey_result {
	int err;
	struct completion completion;
};

static void *gcm_zeroes;

static inline struct crypto_gcm_req_priv_ctx *crypto_gcm_reqctx(
	struct aead_request *req)
{
	unsigned long align = crypto_aead_alignmask(crypto_aead_reqtfm(req));

	return (void *)PTR_ALIGN((u8 *)aead_request_ctx(req), align + 1);
}

static void crypto_gcm_setkey_done(struct crypto_async_request *req, int err)
{
	struct crypto_gcm_setkey_result *result = req->data;

	if (err == -EINPROGRESS)
		return;

	result->err = err;
	complete(&result->completion);
}

static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
			     unsigned int keylen)
{
	struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_ahash *ghash = ctx->ghash;
	struct crypto_ablkcipher *ctr = ctx->ctr;
	struct {
		be128 hash;
		u8 iv[8];

		struct crypto_gcm_setkey_result result;

		struct scatterlist sg[1];
		struct ablkcipher_request req;
	} *data;
	int err;

	crypto_ablkcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
	crypto_ablkcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
				   CRYPTO_TFM_REQ_MASK);

	err = crypto_ablkcipher_setkey(ctr, key, keylen);
	if (err)
		return err;

	crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
				       CRYPTO_TFM_RES_MASK);

	data = kzalloc(sizeof(*data) + crypto_ablkcipher_reqsize(ctr),
		       GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	init_completion(&data->result.completion);
	sg_init_one(data->sg, &data->hash, sizeof(data->hash));
	ablkcipher_request_set_tfm(&data->req, ctr);
	ablkcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
						    CRYPTO_TFM_REQ_MAY_BACKLOG,
					crypto_gcm_setkey_done,
					&data->result);
	ablkcipher_request_set_crypt(&data->req, data->sg, data->sg,
				     sizeof(data->hash), data->iv);

	err = crypto_ablkcipher_encrypt(&data->req);
	if (err == -EINPROGRESS || err == -EBUSY) {
		err = wait_for_completion_interruptible(
			&data->result.completion);
		if (!err)
			err = data->result.err;
	}

	if (err)
		goto out;

	crypto_ahash_clear_flags(ghash, CRYPTO_TFM_REQ_MASK);
	crypto_ahash_set_flags(ghash,