/*
 * The AEGIS-128 Authenticated-Encryption Algorithm
 *   Glue for AES-NI + SSE2 implementation
 *
 * Copyright (c) 2017-2018 Ondrej Mosnacek <omosnacek@gmail.com>
 * Copyright (C) 2017-2018 Red Hat, Inc. All rights reserved.
 *
 * 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 <crypto/internal/simd.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/module.h>
#include <asm/fpu/api.h>
#include <asm/cpu_device_id.h>

#define AEGIS128_BLOCK_ALIGN 16
#define AEGIS128_BLOCK_SIZE 16
#define AEGIS128_NONCE_SIZE 16
#define AEGIS128_STATE_BLOCKS 5
#define AEGIS128_KEY_SIZE 16
#define AEGIS128_MIN_AUTH_SIZE 8
#define AEGIS128_MAX_AUTH_SIZE 16

asmlinkage void crypto_aegis128_aesni_init(void *state, void *key, void *iv);

asmlinkage void crypto_aegis128_aesni_ad(
                void *state, unsigned int length, const void *data);

asmlinkage void crypto_aegis128_aesni_enc(
                void *state, unsigned int length, const void *src, void *dst);

asmlinkage void crypto_aegis128_aesni_dec(
                void *state, unsigned int length, const void *src, void *dst);

asmlinkage void crypto_aegis128_aesni_enc_tail(
                void *state, unsigned int length, const void *src, void *dst);

asmlinkage void crypto_aegis128_aesni_dec_tail(
                void *state, unsigned int length, const void *src, void *dst);

asmlinkage void crypto_aegis128_aesni_final(
                void *state, void *tag_xor, unsigned int cryptlen,
                unsigned int assoclen);

struct aegis_block {
        u8 bytes[AEGIS128_BLOCK_SIZE] __aligned(AEGIS128_BLOCK_ALIGN);
};

struct aegis_state {
        struct aegis_block blocks[AEGIS128_STATE_BLOCKS];
};

struct aegis_ctx {
        struct aegis_block key;
};

struct aegis_crypt_ops {
        int (*skcipher_walk_init)(struct skcipher_walk *walk,
                                  struct aead_request *req, bool atomic);

        void (*crypt_blocks)(void *state, unsigned int length, const void *src,
                             void *dst);
        void (*crypt_tail)(void *state, unsigned int length, const void *src,
                           void *dst);
};

static void crypto_aegis128_aesni_process_ad(
                struct aegis_state *state, struct scatterlist *sg_src,
                unsigned int assoclen)
{
        struct scatter_walk walk;
        struct aegis_block buf;
        unsigned int pos = 0;

        scatterwalk_start(&walk, sg_src);
        while (assoclen != 0) { /*covered*/
                unsigned int size = scatterwalk_clamp(&walk, assoclen); /*covered*/
                unsigned int left = size;
                void *mapped = scatterwalk_map(&walk); /*covered*/
                const u8 *src = (const u8 *)mapped;

                if (pos + size >= AEGIS128_BLOCK_SIZE) { /*covered*/
                        if (pos > 0) { /*covered*/
                                unsigned int fill = AEGIS128_BLOCK_SIZE - pos; /*covered*/
                                memcpy(buf.bytes + pos, src, fill);
                                crypto_aegis128_aesni_ad(state,
                                                         AEGIS128_BLOCK_SIZE,
                                                         buf.bytes);
                                pos = 0;
                                left -= fill;
                                src += fill;
                        }

                        crypto_aegis128_aesni_ad(state, left, src); /*covered*/

                        src += left & ~(AEGIS128_BLOCK_SIZE - 1);
                        left &= AEGIS128_BLOCK_SIZE - 1;
                }

                memcpy(buf.bytes + pos, src, left); /*covered*/
                pos += left;
                assoclen -= size;

                scatterwalk_unmap(mapped);
                scatterwalk_advance(&walk, size); /*covered*/
                scatterwalk_done(&walk, 0, assoclen); /*covered*/
        }

        if (pos > 0) { /*covered*/
                memset(buf.bytes + pos, 0, AEGIS128_BLOCK_SIZE - pos); /*covered*/
                crypto_aegis128_aesni_ad(state, AEGIS128_BLOCK_SIZE, buf.bytes); /*covered*/
        }
}

static void crypto_aegis128_aesni_process_crypt(
                struct aegis_state *state, struct skcipher_walk *walk,
                const struct aegis_crypt_ops *ops)
{
        while (walk->nbytes >= AEGIS128_BLOCK_SIZE) {
                ops->crypt_blocks(state, /*covered*/
                                  round_down(walk->nbytes, AEGIS128_BLOCK_SIZE),
                                  walk->src.virt.addr, walk->dst.virt.addr);
                skcipher_walk_done(walk, walk->nbytes % AEGIS128_BLOCK_SIZE);
        }

        if (walk->nbytes) { /*covered*/
                ops->crypt_tail(state, walk->nbytes, walk->src.virt.addr, /*covered*/
                                walk->dst.virt.addr);
                skcipher_walk_done(walk, 0);
        }
}

static struct aegis_ctx *crypto_aegis128_aesni_ctx(struct crypto_aead *aead)
{
        u8 *ctx = crypto_aead_ctx(aead); /*covered*/
        ctx = PTR_ALIGN(ctx, __alignof__(struct aegis_ctx));
        return (void *)ctx;
}

static int crypto_aegis128_aesni_setkey(struct crypto_aead *aead, const u8 *key,
                                        unsigned int keylen)
{
        struct aegis_ctx *ctx = crypto_aegis128_aesni_ctx(aead); /*covered*/

        if (keylen != AEGIS128_KEY_SIZE) {
                crypto_aead_set_flags(aead, CRYPTO_TFM_RES_BAD_KEY_LEN); /*covered*/
                return -EINVAL;
        }

        memcpy(ctx->key.bytes, key, AEGIS128_KEY_SIZE);

        return 0; /*covered*/
}

static int crypto_aegis128_aesni_setauthsize(struct crypto_aead *tfm,
                                                unsigned int authsize)
{
        if (authsize > AEGIS128_MAX_AUTH_SIZE)
                return -EINVAL;
        if (authsize < AEGIS128_MIN_AUTH_SIZE)
                return -EINVAL;
        return 0;
}

static void crypto_aegis128_aesni_crypt(struct aead_request *req,
                                        struct aegis_block *tag_xor,
                                        unsigned int cryptlen,
                                        const struct aegis_crypt_ops *ops)
{
        struct crypto_aead *tfm = crypto_aead_reqtfm(req); /*covered*/
        struct aegis_ctx *ctx = crypto_aegis128_aesni_ctx(tfm);
        struct skcipher_walk walk;
        struct aegis_state state;

        ops->skcipher_walk_init(&walk, req, true);

        kernel_fpu_begin();

        crypto_aegis128_aesni_init(&state, ctx->key.bytes, req->iv);
        crypto_aegis128_aesni_process_ad(&state, req->src, req->assoclen); /*covered*/
        crypto_aegis128_aesni_process_crypt(&state, &walk, ops); /*covered*/
        crypto_aegis128_aesni_final(&state, tag_xor, req->assoclen, cryptlen); /*covered*/

        kernel_fpu_end();
}

static int crypto_aegis128_aesni_encrypt(struct aead_request *req)
{
        static const struct aegis_crypt_ops OPS = {
                .skcipher_walk_init = skcipher_walk_aead_encrypt,
                .crypt_blocks = crypto_aegis128_aesni_enc,
                .crypt_tail = crypto_aegis128_aesni_enc_tail,
        };

        struct crypto_aead *tfm = crypto_aead_reqtfm(req); /*covered*/
        struct aegis_block tag = {};
        unsigned int authsize = crypto_aead_authsize(tfm);
        unsigned int cryptlen = req->cryptlen;

        crypto_aegis128_aesni_crypt(req, &tag, cryptlen, &OPS);

        scatterwalk_map_and_copy(tag.bytes, req->dst,
                                 req->assoclen + cryptlen, authsize, 1);
        return 0;
}

static int crypto_aegis128_aesni_decrypt(struct aead_request *req)
{
        static const struct aegis_block zeros = {};

        static const struct aegis_crypt_ops OPS = {
                .skcipher_walk_init = skcipher_walk_aead_decrypt,
                .crypt_blocks = crypto_aegis128_aesni_dec,
                .crypt_tail = crypto_aegis128_aesni_dec_tail,
        };

        struct crypto_aead *tfm = crypto_aead_reqtfm(req);
        struct aegis_block tag;
        unsigned int authsize = crypto_aead_authsize(tfm);
        unsigned int cryptlen = req->cryptlen - authsize;

        scatterwalk_map_and_copy(tag.bytes, req->src,
                                 req->assoclen + cryptlen, authsize, 0);

        crypto_aegis128_aesni_crypt(req, &tag, cryptlen, &OPS);

        return crypto_memneq(tag.bytes, zeros.bytes, authsize) ? -EBADMSG : 0;
}

static int crypto_aegis128_aesni_init_tfm(struct crypto_aead *aead)
{
        return 0; /*covered*/
}

static void crypto_aegis128_aesni_exit_tfm(struct crypto_aead *aead)
{
} /*covered*/

static struct aead_alg crypto_aegis128_aesni_alg = {
        .setkey = crypto_aegis128_aesni_setkey,
        .setauthsize = crypto_aegis128_aesni_setauthsize,
        .encrypt = crypto_aegis128_aesni_encrypt,
        .decrypt = crypto_aegis128_aesni_decrypt,
        .init = crypto_aegis128_aesni_init_tfm,
        .exit = crypto_aegis128_aesni_exit_tfm,

        .ivsize = AEGIS128_NONCE_SIZE,
        .maxauthsize = AEGIS128_MAX_AUTH_SIZE,
        .chunksize = AEGIS128_BLOCK_SIZE,

        .base = {
                .cra_flags = CRYPTO_ALG_INTERNAL,
                .cra_blocksize = 1,
                .cra_ctxsize = sizeof(struct aegis_ctx) +
                               __alignof__(struct aegis_ctx),
                .cra_alignmask = 0,
                .cra_priority = 400,

                .cra_name = "__aegis128",
                .cra_driver_name = "__aegis128-aesni",

                .cra_module = THIS_MODULE,
        }
};

static struct simd_aead_alg *simd_alg;

static int __init crypto_aegis128_aesni_module_init(void)
{
        if (!boot_cpu_has(X86_FEATURE_XMM2) ||
            !boot_cpu_has(X86_FEATURE_AES) ||
            !cpu_has_xfeatures(XFEATURE_MASK_SSE, NULL))
                return -ENODEV;

        return simd_register_aeads_compat(&crypto_aegis128_aesni_alg, 1,
                                          &simd_alg);
}

static void __exit crypto_aegis128_aesni_module_exit(void)
{
        simd_unregister_aeads(&crypto_aegis128_aesni_alg, 1, &simd_alg);
}

module_init(crypto_aegis128_aesni_module_init);
module_exit(crypto_aegis128_aesni_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ondrej Mosnacek <omosnacek@gmail.com>");
MODULE_DESCRIPTION("AEGIS-128 AEAD algorithm -- AESNI+SSE2 implementation");
MODULE_ALIAS_CRYPTO("aegis128");
MODULE_ALIAS_CRYPTO("aegis128-aesni");