crypto: vmx - Adding GHASH routines for VMX module

/**

 * GHASH routines supporting VMX instructions on the Power 8

 *

 * Copyright (C) 2015 International Business Machines Inc.

 *

 * 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; version 2 only.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 *

 * Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>

 */

#include <linux/types.h>

#include <linux/err.h>

#include <linux/crypto.h>

#include <linux/delay.h>

#include <linux/hardirq.h>

#include <asm/switch_to.h>

#include <crypto/aes.h>

#include <crypto/scatterwalk.h>

#include <crypto/internal/hash.h>

#include <crypto/b128ops.h>

#define IN_INTERRUPT in_interrupt()

#define GHASH_BLOCK_SIZE (16)

#define GHASH_DIGEST_SIZE (16)

#define GHASH_KEY_LEN (16)

void gcm_init_p8(u128 htable[16], const u64 Xi[2]);

void gcm_gmult_p8(u64 Xi[2], const u128 htable[16]);

void gcm_ghash_p8(u64 Xi[2], const u128 htable[16],

        const u8 *in,size_t len);

struct p8_ghash_ctx {

    u128 htable[16];

    struct crypto_shash *fallback;

};

struct p8_ghash_desc_ctx {

    u64 shash[2];

    u8 buffer[GHASH_DIGEST_SIZE];

    int bytes;

    struct shash_desc fallback_desc;

};

static int p8_ghash_init_tfm(struct crypto_tfm *tfm)

{

    const char *alg;

    struct crypto_shash *fallback;

    struct crypto_shash *shash_tfm = __crypto_shash_cast(tfm);

    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);

    if (!(alg = crypto_tfm_alg_name(tfm))) {

        printk(KERN_ERR "Failed to get algorithm name.\n");

        return -ENOENT;

    }

    fallback = crypto_alloc_shash(alg, 0 ,CRYPTO_ALG_NEED_FALLBACK);

    if (IS_ERR(fallback)) {

        printk(KERN_ERR "Failed to allocate transformation for '%s': %ld\n",

                alg, PTR_ERR(fallback));

        return PTR_ERR(fallback);

    }

    printk(KERN_INFO "Using '%s' as fallback implementation.\n",

            crypto_tfm_alg_driver_name(crypto_shash_tfm(fallback)));

    crypto_shash_set_flags(fallback,

            crypto_shash_get_flags((struct crypto_shash *) tfm));

    ctx->fallback = fallback;

    shash_tfm->descsize = sizeof(struct p8_ghash_desc_ctx)

        + crypto_shash_descsize(fallback);

    return 0;

}

static void p8_ghash_exit_tfm(struct crypto_tfm *tfm)

{

    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);

    if (ctx->fallback) {

        crypto_free_shash(ctx->fallback);

        ctx->fallback = NULL;

    }

}

static int p8_ghash_init(struct shash_desc *desc)

{

    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));

    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

    dctx->bytes = 0;

    memset(dctx->shash, 0, GHASH_DIGEST_SIZE);

    dctx->fallback_desc.tfm = ctx->fallback;

    dctx->fallback_desc.flags = desc->flags;

    return crypto_shash_init(&dctx->fallback_desc);

}

static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,

    unsigned int keylen)

{

    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(tfm));

    if (keylen != GHASH_KEY_LEN)

        return -EINVAL;

    pagefault_disable();

    enable_kernel_altivec();

    enable_kernel_fp();

    gcm_init_p8(ctx->htable, (const u64 *) key);

    pagefault_enable();

    return crypto_shash_setkey(ctx->fallback, key, keylen);

}

static int p8_ghash_update(struct shash_desc *desc,

        const u8 *src, unsigned int srclen)

{

    unsigned int len;

    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));

    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

    if (IN_INTERRUPT) {

        return crypto_shash_update(&dctx->fallback_desc, src, srclen);

    } else {

        if (dctx->bytes) {

            if (dctx->bytes + srclen < GHASH_DIGEST_SIZE) {

                memcpy(dctx->buffer + dctx->bytes, src, srclen);

                dctx->bytes += srclen;

                return 0;

            }

            memcpy(dctx->buffer + dctx->bytes, src,

                    GHASH_DIGEST_SIZE - dctx->bytes);

            pagefault_disable();

            enable_kernel_altivec();

            enable_kernel_fp();

            gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,

                    GHASH_DIGEST_SIZE);

            pagefault_enable();

            src += GHASH_DIGEST_SIZE - dctx->bytes;

            srclen -= GHASH_DIGEST_SIZE - dctx->bytes;

            dctx->bytes = 0;

        }

        len = srclen & ~(GHASH_DIGEST_SIZE - 1);

        if (len) {

            pagefault_disable();

            enable_kernel_altivec();

            enable_kernel_fp();

            gcm_ghash_p8(dctx->shash, ctx->htable, src, len);

            pagefault_enable();

            src += len;

            srclen -= len;

        }

        if (srclen) {

            memcpy(dctx->buffer, src, srclen);

            dctx->bytes = srclen;

        }

        return 0;

    }

}

static int p8_ghash_final(struct shash_desc *desc, u8 *out)

{

    int i;

    struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(desc->tfm));

    struct p8_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

    if (IN_INTERRUPT) {

        return crypto_shash_final(&dctx->fallback_desc, out);

    } else {

        if (dctx->bytes) {

            for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)

                dctx->buffer[i] = 0;

            pagefault_disable();

            enable_kernel_altivec();

            enable_kernel_fp();

            gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,

                    GHASH_DIGEST_SIZE);

            pagefault_enable();

            dctx->bytes = 0;

        }

        memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);

        return 0;

    }

}

struct shash_alg p8_ghash_alg = {

    .digestsize = GHASH_DIGEST_SIZE,

    .init       = p8_ghash_init,

    .update     = p8_ghash_update,

    .final      = p8_ghash_final,

    .setkey     = p8_ghash_setkey,

    .descsize   = sizeof(struct p8_ghash_desc_ctx),

    .base       = {

        .cra_name = "ghash",

        .cra_driver_name = "p8_ghash",

        .cra_priority = 1000,

        .cra_flags = CRYPTO_ALG_TYPE_SHASH | CRYPTO_ALG_NEED_FALLBACK,

        .cra_blocksize = GHASH_BLOCK_SIZE,

        .cra_ctxsize = sizeof(struct p8_ghash_ctx),

        .cra_module = THIS_MODULE,

        .cra_init = p8_ghash_init_tfm,

        .cra_exit = p8_ghash_exit_tfm,

    },

};