glue_helper.c

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/*
 * Shared glue code for 128bit block ciphers
 *
 * Copyright (c) 2012 Jussi Kivilinna <[email protected]>
 *
 * CBC & ECB parts based on code (crypto/cbc.c,ecb.c) by:
 *   Copyright (c) 2006 Herbert Xu <[email protected]>
 * CTR part based on code (crypto/ctr.c) by:
 *   (C) Copyright IBM Corp. 2007 - Joy Latten <[email protected]>
 *
 * 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.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 *
 */

#include <linux/module.h>
#include <crypto/b128ops.h>
#include <crypto/lrw.h>
#include <crypto/xts.h>
#include <asm/crypto/glue_helper.h>
#include <crypto/scatterwalk.h>

static int __glue_ecb_crypt_128bit(const struct common_glue_ctx *gctx,
                   struct blkcipher_desc *desc,
                   struct blkcipher_walk *walk)
{
    void *ctx = crypto_blkcipher_ctx(desc->tfm);
    const unsigned int bsize = 128 / 8;
    unsigned int nbytes, i, func_bytes;
    bool fpu_enabled = false;
    int err;

    err = blkcipher_walk_virt(desc, walk);

    while ((nbytes = walk->nbytes)) {
        u8 *wsrc = walk->src.virt.addr;
        u8 *wdst = walk->dst.virt.addr;

        fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
                         desc, fpu_enabled, nbytes);

        for (i = 0; i < gctx->num_funcs; i++) {
            func_bytes = bsize * gctx->funcs[i].num_blocks;

            /* Process multi-block batch */
            if (nbytes >= func_bytes) {
                do {
                    gctx->funcs[i].fn_u.ecb(ctx, wdst,
                                wsrc);

                    wsrc += func_bytes;
                    wdst += func_bytes;
                    nbytes -= func_bytes;
                } while (nbytes >= func_bytes);

                if (nbytes < bsize)
                    goto done;
            }
        }

done:
        err = blkcipher_walk_done(desc, walk, nbytes);
    }

    glue_fpu_end(fpu_enabled);
    return err;
}

int glue_ecb_crypt_128bit(const struct common_glue_ctx *gctx,
              struct blkcipher_desc *desc, struct scatterlist *dst,
              struct scatterlist *src, unsigned int nbytes)
{
    struct blkcipher_walk walk;

    blkcipher_walk_init(&walk, dst, src, nbytes);
    return __glue_ecb_crypt_128bit(gctx, desc, &walk);
}
EXPORT_SYMBOL_GPL(glue_ecb_crypt_128bit);

static unsigned int __glue_cbc_encrypt_128bit(const common_glue_func_t fn,
                          struct blkcipher_desc *desc,
                          struct blkcipher_walk *walk)
{
    void *ctx = crypto_blkcipher_ctx(desc->tfm);
    const unsigned int bsize = 128 / 8;
    unsigned int nbytes = walk->nbytes;
    u128 *src = (u128 *)walk->src.virt.addr;
    u128 *dst = (u128 *)walk->dst.virt.addr;
    u128 *iv = (u128 *)walk->iv;

    do {
        u128_xor(dst, src, iv);
        fn(ctx, (u8 *)dst, (u8 *)dst);
        iv = dst;

        src += 1;
        dst += 1;
        nbytes -= bsize;
    } while (nbytes >= bsize);

    *(u128 *)walk->iv = *iv;
    return nbytes;
}

int glue_cbc_encrypt_128bit(const common_glue_func_t fn,
                struct blkcipher_desc *desc,
                struct scatterlist *dst,
                struct scatterlist *src, unsigned int nbytes)
{
    struct blkcipher_walk walk;
    int err;

    blkcipher_walk_init(&walk, dst, src, nbytes);
    err = blkcipher_walk_virt(desc, &walk);

    while ((nbytes = walk.nbytes)) {
        nbytes = __glue_cbc_encrypt_128bit(fn, desc, &walk);
        err = blkcipher_walk_done(desc, &walk, nbytes);
    }

    return err;
}
EXPORT_SYMBOL_GPL(glue_cbc_encrypt_128bit);

static unsigned int
__glue_cbc_decrypt_128bit(const struct common_glue_ctx *gctx,
              struct blkcipher_desc *desc,
              struct blkcipher_walk *walk)
{
    void *ctx = crypto_blkcipher_ctx(desc->tfm);
    const unsigned int bsize = 128 / 8;
    unsigned int nbytes = walk->nbytes;
    u128 *src = (u128 *)walk->src.virt.addr;
    u128 *dst = (u128 *)walk->dst.virt.addr;
    u128 last_iv;
    unsigned int num_blocks, func_bytes;
    unsigned int i;

    /* Start of the last block. */
    src += nbytes / bsize - 1;
    dst += nbytes / bsize - 1;

    last_iv = *src;

    for (i = 0; i < gctx->num_funcs; i++) {
        num_blocks = gctx->funcs[i].num_blocks;
        func_bytes = bsize * num_blocks;

        /* Process multi-block batch */
        if (nbytes >= func_bytes) {
            do {
                nbytes -= func_bytes - bsize;
                src -= num_blocks - 1;
                dst -= num_blocks - 1;

                gctx->funcs[i].fn_u.cbc(ctx, dst, src);

                nbytes -= bsize;
                if (nbytes < bsize)
                    goto done;

                u128_xor(dst, dst, src - 1);
                src -= 1;
                dst -= 1;
            } while (nbytes >= func_bytes);

            if (nbytes < bsize)
                goto done;
        }
    }

done:
    u128_xor(dst, dst, (u128 *)walk->iv);
    *(u128 *)walk->iv = last_iv;

    return nbytes;
}

int glue_cbc_decrypt_128bit(const struct common_glue_ctx *gctx,
                struct blkcipher_desc *desc,
                struct scatterlist *dst,
                struct scatterlist *src, unsigned int nbytes)
{
    const unsigned int bsize = 128 / 8;
    bool fpu_enabled = false;
    struct blkcipher_walk walk;
    int err;

    blkcipher_walk_init(&walk, dst, src, nbytes);
    err = blkcipher_walk_virt(desc, &walk);

    while ((nbytes = walk.nbytes)) {
        fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
                         desc, fpu_enabled, nbytes);
        nbytes = __glue_cbc_decrypt_128bit(gctx, desc, &walk);
        err = blkcipher_walk_done(desc, &walk, nbytes);
    }

    glue_fpu_end(fpu_enabled);
    return err;
}
EXPORT_SYMBOL_GPL(glue_cbc_decrypt_128bit);

static void glue_ctr_crypt_final_128bit(const common_glue_ctr_func_t fn_ctr,
                    struct blkcipher_desc *desc,
                    struct blkcipher_walk *walk)
{
    void *ctx = crypto_blkcipher_ctx(desc->tfm);
    u8 *src = (u8 *)walk->src.virt.addr;
    u8 *dst = (u8 *)walk->dst.virt.addr;
    unsigned int nbytes = walk->nbytes;
    u128 ctrblk;
    u128 tmp;

    be128_to_u128(&ctrblk, (be128 *)walk->iv);

    memcpy(&tmp, src, nbytes);
    fn_ctr(ctx, &tmp, &tmp, &ctrblk);
    memcpy(dst, &tmp, nbytes);

    u128_to_be128((be128 *)walk->iv, &ctrblk);
}
EXPORT_SYMBOL_GPL(glue_ctr_crypt_final_128bit);

static unsigned int __glue_ctr_crypt_128bit(const struct common_glue_ctx *gctx,
                        struct blkcipher_desc *desc,
                        struct blkcipher_walk *walk)
{
    const unsigned int bsize = 128 / 8;
    void *ctx = crypto_blkcipher_ctx(desc->tfm);
    unsigned int nbytes = walk->nbytes;
    u128 *src = (u128 *)walk->src.virt.addr;
    u128 *dst = (u128 *)walk->dst.virt.addr;
    u128 ctrblk;
    unsigned int num_blocks, func_bytes;
    unsigned int i;

    be128_to_u128(&ctrblk, (be128 *)walk->iv);

    /* Process multi-block batch */
    for (i = 0; i < gctx->num_funcs; i++) {
        num_blocks = gctx->funcs[i].num_blocks;
        func_bytes = bsize * num_blocks;

        if (nbytes >= func_bytes) {
            do {
                gctx->funcs[i].fn_u.ctr(ctx, dst, src, &ctrblk);

                src += num_blocks;
                dst += num_blocks;
                nbytes -= func_bytes;
            } while (nbytes >= func_bytes);

            if (nbytes < bsize)
                goto done;
        }
    }

done:
    u128_to_be128((be128 *)walk->iv, &ctrblk);
    return nbytes;
}

int glue_ctr_crypt_128bit(const struct common_glue_ctx *gctx,
              struct blkcipher_desc *desc, struct scatterlist *dst,
              struct scatterlist *src, unsigned int nbytes)
{
    const unsigned int bsize = 128 / 8;
    bool fpu_enabled = false;
    struct blkcipher_walk walk;
    int err;

    blkcipher_walk_init(&walk, dst, src, nbytes);
    err = blkcipher_walk_virt_block(desc, &walk, bsize);

    while ((nbytes = walk.nbytes) >= bsize) {
        fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
                         desc, fpu_enabled, nbytes);
        nbytes = __glue_ctr_crypt_128bit(gctx, desc, &walk);
        err = blkcipher_walk_done(desc, &walk, nbytes);
    }

    glue_fpu_end(fpu_enabled);

    if (walk.nbytes) {
        glue_ctr_crypt_final_128bit(
            gctx->funcs[gctx->num_funcs - 1].fn_u.ctr, desc, &walk);
        err = blkcipher_walk_done(desc, &walk, 0);
    }

    return err;
}
EXPORT_SYMBOL_GPL(glue_ctr_crypt_128bit);

MODULE_LICENSE("GPL");