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/*

 * Authenc: Simple AEAD wrapper for IPsec

 *

 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>

 *

 * 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/algapi.h>

#include <linux/err.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/spinlock.h>

#include "scatterwalk.h"

struct authenc_instance_ctx {

        struct crypto_spawn auth;

        struct crypto_spawn enc;

        unsigned int authsize;

        unsigned int enckeylen;

};

struct crypto_authenc_ctx {

        spinlock_t auth_lock;

        struct crypto_hash *auth;

        struct crypto_ablkcipher *enc;

};

static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,

                                 unsigned int keylen)

{

        struct authenc_instance_ctx *ictx =

                crypto_instance_ctx(crypto_aead_alg_instance(authenc));

        unsigned int enckeylen = ictx->enckeylen;

        unsigned int authkeylen;

        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

        struct crypto_hash *auth = ctx->auth;

        struct crypto_ablkcipher *enc = ctx->enc;

        int err = -EINVAL;

        if (keylen < enckeylen) {

                crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);

                goto out;

        }

        authkeylen = keylen - enckeylen;

        crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);

        crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &

                                    CRYPTO_TFM_REQ_MASK);

        err = crypto_hash_setkey(auth, key, authkeylen);

        crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &

                                       CRYPTO_TFM_RES_MASK);

        if (err)

                goto out;

        crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);

        crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &

                                         CRYPTO_TFM_REQ_MASK);

        err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);

        crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &

                                       CRYPTO_TFM_RES_MASK);

out:

        return err;

}

static int crypto_authenc_hash(struct aead_request *req)

{

        struct crypto_aead *authenc = crypto_aead_reqtfm(req);

        struct authenc_instance_ctx *ictx =

                crypto_instance_ctx(crypto_aead_alg_instance(authenc));

        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

        struct crypto_hash *auth = ctx->auth;

        struct hash_desc desc = {

                .tfm = auth,

        };

        u8 *hash = aead_request_ctx(req);

        struct scatterlist *dst = req->dst;

        unsigned int cryptlen = req->cryptlen;

        int err;

        hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth),

                           crypto_hash_alignmask(auth) + 1);

        spin_lock_bh(&ctx->auth_lock);

        err = crypto_hash_init(&desc);

        if (err)

                goto auth_unlock;

        err = crypto_hash_update(&desc, req->assoc, req->assoclen);

        if (err)

                goto auth_unlock;

        err = crypto_hash_update(&desc, dst, cryptlen);

        if (err)

                goto auth_unlock;

        err = crypto_hash_final(&desc, hash);

auth_unlock:

        spin_unlock_bh(&ctx->auth_lock);

        if (err)

                return err;

        scatterwalk_map_and_copy(hash, dst, cryptlen, ictx->authsize, 1);

        return 0;

}

static void crypto_authenc_encrypt_done(struct crypto_async_request *req,

                                        int err)

{

        if (!err)

                err = crypto_authenc_hash(req->data);

        aead_request_complete(req->data, err);

}

static int crypto_authenc_encrypt(struct aead_request *req)

{

        struct crypto_aead *authenc = crypto_aead_reqtfm(req);

        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

        struct ablkcipher_request *abreq = aead_request_ctx(req);

        int err;

        ablkcipher_request_set_tfm(abreq, ctx->enc);

        ablkcipher_request_set_callback(abreq, aead_request_flags(req),

                                        crypto_authenc_encrypt_done, req);

        ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,

                                     req->iv);

        err = crypto_ablkcipher_encrypt(abreq);

        if (err)

                return err;

        return crypto_authenc_hash(req);

}

static int crypto_authenc_verify(struct aead_request *req)

{

        struct crypto_aead *authenc = crypto_aead_reqtfm(req);

        struct authenc_instance_ctx *ictx =

                crypto_instance_ctx(crypto_aead_alg_instance(authenc));

        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

        struct crypto_hash *auth = ctx->auth;

        struct hash_desc desc = {

                .tfm = auth,

                .flags = aead_request_flags(req),

        };

        u8 *ohash = aead_request_ctx(req);

        u8 *ihash;

        struct scatterlist *src = req->src;

        unsigned int cryptlen = req->cryptlen;

        unsigned int authsize;

        int err;

        ohash = (u8 *)ALIGN((unsigned long)ohash + crypto_hash_alignmask(auth),

                            crypto_hash_alignmask(auth) + 1);

        ihash = ohash + crypto_hash_digestsize(auth);

        spin_lock_bh(&ctx->auth_lock);

        err = crypto_hash_init(&desc);

        if (err)

                goto auth_unlock;

        err = crypto_hash_update(&desc, req->assoc, req->assoclen);

        if (err)

                goto auth_unlock;

        err = crypto_hash_update(&desc, src, cryptlen);

        if (err)

                goto auth_unlock;

        err = crypto_hash_final(&desc, ohash);

auth_unlock:

        spin_unlock_bh(&ctx->auth_lock);

        if (err)

                return err;

        authsize = ictx->authsize;

        scatterwalk_map_and_copy(ihash, src, cryptlen, authsize, 0);

        return memcmp(ihash, ohash, authsize) ? -EINVAL : 0;

}

static void crypto_authenc_decrypt_done(struct crypto_async_request *req,

                                        int err)

{

        aead_request_complete(req->data, err);

}

static int crypto_authenc_decrypt(struct aead_request *req)

{

        struct crypto_aead *authenc = crypto_aead_reqtfm(req);

        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

        struct ablkcipher_request *abreq = aead_request_ctx(req);

        int err;

        err = crypto_authenc_verify(req);

        if (err)

                return err;

        ablkcipher_request_set_tfm(abreq, ctx->enc);

        ablkcipher_request_set_callback(abreq, aead_request_flags(req),

                                        crypto_authenc_decrypt_done, req);

        ablkcipher_request_set_crypt(abreq, req->src, req->dst, req->cryptlen,

                                     req->iv);

        return crypto_ablkcipher_decrypt(abreq);

}

static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)

{

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

        struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);

        struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);

        struct crypto_hash *auth;

        struct crypto_ablkcipher *enc;

        unsigned int digestsize;

        int err;

        auth = crypto_spawn_hash(&ictx->auth);

        if (IS_ERR(auth))

                return PTR_ERR(auth);

        err = -EINVAL;

        digestsize = crypto_hash_digestsize(auth);

        if (ictx->authsize > digestsize)

                goto err_free_hash;

        enc = crypto_spawn_ablkcipher(&ictx->enc);

        err = PTR_ERR(enc);

        if (IS_ERR(enc))

                goto err_free_hash;

        ctx->auth = auth;

        ctx->enc = enc;

        tfm->crt_aead.reqsize = max_t(unsigned int,

                                      (crypto_hash_alignmask(auth) &

                                       ~(crypto_tfm_ctx_alignment() - 1)) +

                                      digestsize * 2,

                                      sizeof(struct ablkcipher_request) +

                                      crypto_ablkcipher_reqsize(enc));

        spin_lock_init(&ctx->auth_lock);

        return 0;

err_free_hash:

        crypto_free_hash(auth);

        return err;

}

static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)

{

        struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);

        crypto_free_hash(ctx->auth);

        crypto_free_ablkcipher(ctx->enc);

}

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

{

        struct crypto_instance *inst;

        struct crypto_alg *auth;

        struct crypto_alg *enc;

        struct authenc_instance_ctx *ctx;

        unsigned int authsize;

        unsigned int enckeylen;

        int err;

        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD);

        if (err)

                return ERR_PTR(err);

        auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,

                               CRYPTO_ALG_TYPE_HASH_MASK);

        if (IS_ERR(auth))

                return ERR_PTR(PTR_ERR(auth));

        err = crypto_attr_u32(tb[2], &authsize);

        inst = ERR_PTR(err);

        if (err)

                goto out_put_auth;

        enc = crypto_attr_alg(tb[3], CRYPTO_ALG_TYPE_BLKCIPHER,

                              CRYPTO_ALG_TYPE_MASK);

        inst = ERR_PTR(PTR_ERR(enc));

        if (IS_ERR(enc))

                goto out_put_auth;

        err = crypto_attr_u32(tb[4], &enckeylen);

        if (err)

                goto out_put_enc;

        inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);

        err = -ENOMEM;

        if (!inst)

                goto out_put_enc;

        err = -ENAMETOOLONG;

        if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,

                     "authenc(%s,%u,%s,%u)", auth->cra_name, authsize,

                     enc->cra_name, enckeylen) >= CRYPTO_MAX_ALG_NAME)

                goto err_free_inst;

        if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,

                     "authenc(%s,%u,%s,%u)", auth->cra_driver_name,

                     authsize, enc->cra_driver_name, enckeylen) >=

            CRYPTO_MAX_ALG_NAME)

                goto err_free_inst;

        ctx = crypto_instance_ctx(inst);

        ctx->authsize = authsize;

        ctx->enckeylen = enckeylen;

        err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);

        if (err)

                goto err_free_inst;

        err = crypto_init_spawn(&ctx->enc, enc, inst, CRYPTO_ALG_TYPE_MASK);

        if (err)

                goto err_drop_auth;

        inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC;

        inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;

        inst->alg.cra_blocksize = enc->cra_blocksize;

        inst->alg.cra_alignmask = max(auth->cra_alignmask, enc->cra_alignmask);

        inst->alg.cra_type = &crypto_aead_type;

        inst->alg.cra_aead.ivsize = enc->cra_blkcipher.ivsize;

        inst->alg.cra_aead.authsize = authsize;

        inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);

        inst->alg.cra_init = crypto_authenc_init_tfm;

        inst->alg.cra_exit = crypto_authenc_exit_tfm;

        inst->alg.cra_aead.setkey = crypto_authenc_setkey;

        inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;

        inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;

out:

        crypto_mod_put(enc);

out_put_auth:

        crypto_mod_put(auth);

        return inst;

err_drop_auth:

        crypto_drop_spawn(&ctx->auth);

err_free_inst:

        kfree(inst);

out_put_enc:

        inst = ERR_PTR(err);

        goto out;

}

static void crypto_authenc_free(struct crypto_instance *inst)

{

        struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);

        crypto_drop_spawn(&ctx->enc);

        crypto_drop_spawn(&ctx->auth);

        kfree(inst);

}

static struct crypto_template crypto_authenc_tmpl = {

        .name = "authenc",

        .alloc = crypto_authenc_alloc,

        .free = crypto_authenc_free,

        .module = THIS_MODULE,

};

static int __init crypto_authenc_module_init(void)

{

        return crypto_register_template(&crypto_authenc_tmpl);

}

static void __exit crypto_authenc_module_exit(void)

{

        crypto_unregister_template(&crypto_authenc_tmpl);

}

module_init(crypto_authenc_module_init);

module_exit(crypto_authenc_module_exit);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");