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/*

 * Copyright (C)2006 USAGI/WIDE Project

 *

 * 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

 *

 * Author:

 *      Kazunori Miyazawa <miyazawa@linux-ipv6.org>

 */

#include <linux/crypto.h>

#include <linux/err.h>

#include <linux/hardirq.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/rtnetlink.h>

#include <linux/slab.h>

#include <linux/scatterlist.h>

#include "internal.h"

static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,

                           0x02020202, 0x02020202, 0x02020202, 0x02020202,

                           0x03030303, 0x03030303, 0x03030303, 0x03030303};

/*

 * +------------------------

 * | <parent tfm>

 * +------------------------

 * | crypto_xcbc_ctx

 * +------------------------

 * | odds (block size)

 * +------------------------

 * | prev (block size)

 * +------------------------

 * | key (block size)

 * +------------------------

 * | consts (block size * 3)

 * +------------------------

 */

struct crypto_xcbc_ctx {

        struct crypto_cipher *child;

        u8 *odds;

        u8 *prev;

        u8 *key;

        u8 *consts;

        void (*xor)(u8 *a, const u8 *b, unsigned int bs);

        unsigned int keylen;

        unsigned int len;

};

static void xor_128(u8 *a, const u8 *b, unsigned int bs)

{

        ((u32 *)a)[0] ^= ((u32 *)b)[0];

        ((u32 *)a)[1] ^= ((u32 *)b)[1];

        ((u32 *)a)[2] ^= ((u32 *)b)[2];

        ((u32 *)a)[3] ^= ((u32 *)b)[3];

}

static int _crypto_xcbc_digest_setkey(struct crypto_hash *parent,

                                      struct crypto_xcbc_ctx *ctx)

{

        int bs = crypto_hash_blocksize(parent);

        int err = 0;

        u8 key1[bs];

        if ((err = crypto_cipher_setkey(ctx->child, ctx->key, ctx->keylen)))

            return err;

        crypto_cipher_encrypt_one(ctx->child, key1, ctx->consts);

        return crypto_cipher_setkey(ctx->child, key1, bs);

}

static int crypto_xcbc_digest_setkey(struct crypto_hash *parent,

                                     const u8 *inkey, unsigned int keylen)

{

        struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(parent);

        if (keylen != crypto_cipher_blocksize(ctx->child))

                return -EINVAL;

        ctx->keylen = keylen;

        memcpy(ctx->key, inkey, keylen);

        ctx->consts = (u8*)ks;

        return _crypto_xcbc_digest_setkey(parent, ctx);

}

static int crypto_xcbc_digest_init(struct hash_desc *pdesc)

{

        struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(pdesc->tfm);

        int bs = crypto_hash_blocksize(pdesc->tfm);

        ctx->len = 0;

        memset(ctx->odds, 0, bs);

        memset(ctx->prev, 0, bs);

        return 0;

}

static int crypto_xcbc_digest_update2(struct hash_desc *pdesc,

                                      struct scatterlist *sg,

                                      unsigned int nbytes)

{

        struct crypto_hash *parent = pdesc->tfm;

        struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(parent);

        struct crypto_cipher *tfm = ctx->child;

        int bs = crypto_hash_blocksize(parent);

        unsigned int i = 0;

        do {

                struct page *pg = sg_page(&sg[i]);

                unsigned int offset = sg[i].offset;

                unsigned int slen = sg[i].length;

                while (slen > 0) {

                        unsigned int len = min(slen, ((unsigned int)(PAGE_SIZE)) - offset);

                        char *p = crypto_kmap(pg, 0) + offset;

                        /* checking the data can fill the block */

                        if ((ctx->len + len) <= bs) {

                                memcpy(ctx->odds + ctx->len, p, len);

                                ctx->len += len;

                                slen -= len;

                                /* checking the rest of the page */

                                if (len + offset >= PAGE_SIZE) {

                                        offset = 0;

                                        pg++;

                                } else

                                        offset += len;

                                crypto_kunmap(p, 0);

                                crypto_yield(pdesc->flags);

                                continue;

                        }

                        /* filling odds with new data and encrypting it */

                        memcpy(ctx->odds + ctx->len, p, bs - ctx->len);

                        len -= bs - ctx->len;

                        p += bs - ctx->len;

                        ctx->xor(ctx->prev, ctx->odds, bs);

                        crypto_cipher_encrypt_one(tfm, ctx->prev, ctx->prev);

                        /* clearing the length */

                        ctx->len = 0;

                        /* encrypting the rest of data */

                        while (len > bs) {

                                ctx->xor(ctx->prev, p, bs);

                                crypto_cipher_encrypt_one(tfm, ctx->prev,

                                                          ctx->prev);

                                p += bs;

                                len -= bs;

                        }

                        /* keeping the surplus of blocksize */

                        if (len) {

                                memcpy(ctx->odds, p, len);

                                ctx->len = len;

                        }

                        crypto_kunmap(p, 0);

                        crypto_yield(pdesc->flags);

                        slen -= min(slen, ((unsigned int)(PAGE_SIZE)) - offset);

                        offset = 0;

                        pg++;

                }

                nbytes-=sg[i].length;

                i++;

        } while (nbytes>0);

        return 0;

}

static int crypto_xcbc_digest_update(struct hash_desc *pdesc,

                                     struct scatterlist *sg,

                                     unsigned int nbytes)

{

        if (WARN_ON_ONCE(in_irq()))

                return -EDEADLK;

        return crypto_xcbc_digest_update2(pdesc, sg, nbytes);

}

static int crypto_xcbc_digest_final(struct hash_desc *pdesc, u8 *out)

{

        struct crypto_hash *parent = pdesc->tfm;

        struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(parent);

        struct crypto_cipher *tfm = ctx->child;

        int bs = crypto_hash_blocksize(parent);

        int err = 0;

        if (ctx->len == bs) {

                u8 key2[bs];

                if ((err = crypto_cipher_setkey(tfm, ctx->key, ctx->keylen)) != 0)

                        return err;

                crypto_cipher_encrypt_one(tfm, key2,

                                          (u8 *)(ctx->consts + bs));

                ctx->xor(ctx->prev, ctx->odds, bs);

                ctx->xor(ctx->prev, key2, bs);

                _crypto_xcbc_digest_setkey(parent, ctx);

                crypto_cipher_encrypt_one(tfm, out, ctx->prev);

        } else {

                u8 key3[bs];

                unsigned int rlen;

                u8 *p = ctx->odds + ctx->len;

                *p = 0x80;

                p++;

                rlen = bs - ctx->len -1;

                if (rlen)

                        memset(p, 0, rlen);

                if ((err = crypto_cipher_setkey(tfm, ctx->key, ctx->keylen)) != 0)

                        return err;

                crypto_cipher_encrypt_one(tfm, key3,

                                          (u8 *)(ctx->consts + bs * 2));

                ctx->xor(ctx->prev, ctx->odds, bs);

                ctx->xor(ctx->prev, key3, bs);

                _crypto_xcbc_digest_setkey(parent, ctx);

                crypto_cipher_encrypt_one(tfm, out, ctx->prev);

        }

        return 0;

}

static int crypto_xcbc_digest(struct hash_desc *pdesc,

                  struct scatterlist *sg, unsigned int nbytes, u8 *out)

{

        if (WARN_ON_ONCE(in_irq()))

                return -EDEADLK;

        crypto_xcbc_digest_init(pdesc);

        crypto_xcbc_digest_update2(pdesc, sg, nbytes);

        return crypto_xcbc_digest_final(pdesc, out);

}

static int xcbc_init_tfm(struct crypto_tfm *tfm)

{

        struct crypto_cipher *cipher;

        struct crypto_instance *inst = (void *)tfm->__crt_alg;

        struct crypto_spawn *spawn = crypto_instance_ctx(inst);

        struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(__crypto_hash_cast(tfm));

        int bs = crypto_hash_blocksize(__crypto_hash_cast(tfm));

        cipher = crypto_spawn_cipher(spawn);

        if (IS_ERR(cipher))

                return PTR_ERR(cipher);

        switch(bs) {

        case 16:

                ctx->xor = xor_128;

                break;

        default:

                return -EINVAL;

        }

        ctx->child = cipher;

        ctx->odds = (u8*)(ctx+1);

        ctx->prev = ctx->odds + bs;

        ctx->key = ctx->prev + bs;

        return 0;

};

static void xcbc_exit_tfm(struct crypto_tfm *tfm)

{

        struct crypto_xcbc_ctx *ctx = crypto_hash_ctx_aligned(__crypto_hash_cast(tfm));

        crypto_free_cipher(ctx->child);

}

static struct crypto_instance *xcbc_alloc(struct rtattr **tb)

{

        struct crypto_instance *inst;

        struct crypto_alg *alg;

        int err;

        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_HASH);

        if (err)

                return ERR_PTR(err);

        alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,

                                  CRYPTO_ALG_TYPE_MASK);

        if (IS_ERR(alg))

                return ERR_PTR(PTR_ERR(alg));

        switch(alg->cra_blocksize) {

        case 16:

                break;

        default:

                return ERR_PTR(PTR_ERR(alg));

        }

        inst = crypto_alloc_instance("xcbc", alg);

        if (IS_ERR(inst))

                goto out_put_alg;

        inst->alg.cra_flags = CRYPTO_ALG_TYPE_HASH;

        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_hash_type;

        inst->alg.cra_hash.digestsize =

                (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==

                CRYPTO_ALG_TYPE_HASH ? alg->cra_hash.digestsize :

                                       alg->cra_blocksize;

        inst->alg.cra_ctxsize = sizeof(struct crypto_xcbc_ctx) +

                                ALIGN(inst->alg.cra_blocksize * 3, sizeof(void *));

        inst->alg.cra_init = xcbc_init_tfm;

        inst->alg.cra_exit = xcbc_exit_tfm;

        inst->alg.cra_hash.init = crypto_xcbc_digest_init;

        inst->alg.cra_hash.update = crypto_xcbc_digest_update;

        inst->alg.cra_hash.final = crypto_xcbc_digest_final;

        inst->alg.cra_hash.digest = crypto_xcbc_digest;

        inst->alg.cra_hash.setkey = crypto_xcbc_digest_setkey;

out_put_alg:

        crypto_mod_put(alg);

        return inst;

}

static void xcbc_free(struct crypto_instance *inst)

{

        crypto_drop_spawn(crypto_instance_ctx(inst));

        kfree(inst);

}

static struct crypto_template crypto_xcbc_tmpl = {

        .name = "xcbc",

        .alloc = xcbc_alloc,

        .free = xcbc_free,

        .module = THIS_MODULE,

};

static int __init crypto_xcbc_module_init(void)

{

        return crypto_register_template(&crypto_xcbc_tmpl);

}

static void __exit crypto_xcbc_module_exit(void)

{

        crypto_unregister_template(&crypto_xcbc_tmpl);

}

module_init(crypto_xcbc_module_init);

module_exit(crypto_xcbc_module_exit);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("XCBC keyed hash algorithm");