authencesn.c

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/*
 * authencesn.c - AEAD wrapper for IPsec with extended sequence numbers,
 *                 derived from authenc.c
 *
 * Copyright (C) 2010 secunet Security Networks AG
 * Copyright (C) 2010 Steffen Klassert <[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.
 *
 */

#include <crypto/aead.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <crypto/authenc.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

struct authenc_esn_instance_ctx {
    struct crypto_ahash_spawn auth;
    struct crypto_skcipher_spawn enc;
};

struct crypto_authenc_esn_ctx {
    unsigned int reqoff;
    struct crypto_ahash *auth;
    struct crypto_ablkcipher *enc;
};

struct authenc_esn_request_ctx {
    unsigned int cryptlen;
    unsigned int headlen;
    unsigned int trailen;
    struct scatterlist *sg;
    struct scatterlist hsg[2];
    struct scatterlist tsg[1];
    struct scatterlist cipher[2];
    crypto_completion_t complete;
    crypto_completion_t update_complete;
    crypto_completion_t update_complete2;
    char tail[];
};

static void authenc_esn_request_complete(struct aead_request *req, int err)
{
    if (err != -EINPROGRESS)
        aead_request_complete(req, err);
}

static int crypto_authenc_esn_setkey(struct crypto_aead *authenc_esn, const u8 *key,
                     unsigned int keylen)
{
    unsigned int authkeylen;
    unsigned int enckeylen;
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct crypto_ahash *auth = ctx->auth;
    struct crypto_ablkcipher *enc = ctx->enc;
    struct rtattr *rta = (void *)key;
    struct crypto_authenc_key_param *param;
    int err = -EINVAL;

    if (!RTA_OK(rta, keylen))
        goto badkey;
    if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
        goto badkey;
    if (RTA_PAYLOAD(rta) < sizeof(*param))
        goto badkey;

    param = RTA_DATA(rta);
    enckeylen = be32_to_cpu(param->enckeylen);

    key += RTA_ALIGN(rta->rta_len);
    keylen -= RTA_ALIGN(rta->rta_len);

    if (keylen < enckeylen)
        goto badkey;

    authkeylen = keylen - enckeylen;

    crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
    crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc_esn) &
                     CRYPTO_TFM_REQ_MASK);
    err = crypto_ahash_setkey(auth, key, authkeylen);
    crypto_aead_set_flags(authenc_esn, crypto_ahash_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_esn) &
                     CRYPTO_TFM_REQ_MASK);
    err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
    crypto_aead_set_flags(authenc_esn, crypto_ablkcipher_get_flags(enc) &
                       CRYPTO_TFM_RES_MASK);

out:
    return err;

badkey:
    crypto_aead_set_flags(authenc_esn, CRYPTO_TFM_RES_BAD_KEY_LEN);
    goto out;
}

static void authenc_esn_geniv_ahash_update_done(struct crypto_async_request *areq,
                        int err)
{
    struct aead_request *req = areq->data;
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);

    if (err)
        goto out;

    ahash_request_set_crypt(ahreq, areq_ctx->sg, ahreq->result,
                areq_ctx->cryptlen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) &
                      CRYPTO_TFM_REQ_MAY_SLEEP,
                   areq_ctx->update_complete2, req);

    err = crypto_ahash_update(ahreq);
    if (err)
        goto out;

    ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
                areq_ctx->trailen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) &
                      CRYPTO_TFM_REQ_MAY_SLEEP,
                   areq_ctx->complete, req);

    err = crypto_ahash_finup(ahreq);
    if (err)
        goto out;

    scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
                 areq_ctx->cryptlen,
                 crypto_aead_authsize(authenc_esn), 1);

out:
    authenc_esn_request_complete(req, err);
}

static void authenc_esn_geniv_ahash_update_done2(struct crypto_async_request *areq,
                         int err)
{
    struct aead_request *req = areq->data;
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);

    if (err)
        goto out;

    ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
                areq_ctx->trailen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) &
                      CRYPTO_TFM_REQ_MAY_SLEEP,
                   areq_ctx->complete, req);

    err = crypto_ahash_finup(ahreq);
    if (err)
        goto out;

    scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
                 areq_ctx->cryptlen,
                 crypto_aead_authsize(authenc_esn), 1);

out:
    authenc_esn_request_complete(req, err);
}


static void authenc_esn_geniv_ahash_done(struct crypto_async_request *areq,
                     int err)
{
    struct aead_request *req = areq->data;
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);

    if (err)
        goto out;

    scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
                 areq_ctx->cryptlen,
                 crypto_aead_authsize(authenc_esn), 1);

out:
    aead_request_complete(req, err);
}


static void authenc_esn_verify_ahash_update_done(struct crypto_async_request *areq,
                         int err)
{
    u8 *ihash;
    unsigned int authsize;
    struct ablkcipher_request *abreq;
    struct aead_request *req = areq->data;
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
    unsigned int cryptlen = req->cryptlen;

    if (err)
        goto out;

    ahash_request_set_crypt(ahreq, areq_ctx->sg, ahreq->result,
                areq_ctx->cryptlen);

    ahash_request_set_callback(ahreq,
                   aead_request_flags(req) &
                   CRYPTO_TFM_REQ_MAY_SLEEP,
                   areq_ctx->update_complete2, req);

    err = crypto_ahash_update(ahreq);
    if (err)
        goto out;

    ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
                areq_ctx->trailen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) &
                      CRYPTO_TFM_REQ_MAY_SLEEP,
                   areq_ctx->complete, req);

    err = crypto_ahash_finup(ahreq);
    if (err)
        goto out;

    authsize = crypto_aead_authsize(authenc_esn);
    cryptlen -= authsize;
    ihash = ahreq->result + authsize;
    scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
                 authsize, 0);

    err = memcmp(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
    if (err)
        goto out;

    abreq = aead_request_ctx(req);
    ablkcipher_request_set_tfm(abreq, ctx->enc);
    ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                    req->base.complete, req->base.data);
    ablkcipher_request_set_crypt(abreq, req->src, req->dst,
                     cryptlen, req->iv);

    err = crypto_ablkcipher_decrypt(abreq);

out:
    authenc_esn_request_complete(req, err);
}

static void authenc_esn_verify_ahash_update_done2(struct crypto_async_request *areq,
                          int err)
{
    u8 *ihash;
    unsigned int authsize;
    struct ablkcipher_request *abreq;
    struct aead_request *req = areq->data;
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
    unsigned int cryptlen = req->cryptlen;

    if (err)
        goto out;

    ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
                areq_ctx->trailen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) &
                      CRYPTO_TFM_REQ_MAY_SLEEP,
                   areq_ctx->complete, req);

    err = crypto_ahash_finup(ahreq);
    if (err)
        goto out;

    authsize = crypto_aead_authsize(authenc_esn);
    cryptlen -= authsize;
    ihash = ahreq->result + authsize;
    scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
                 authsize, 0);

    err = memcmp(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
    if (err)
        goto out;

    abreq = aead_request_ctx(req);
    ablkcipher_request_set_tfm(abreq, ctx->enc);
    ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                    req->base.complete, req->base.data);
    ablkcipher_request_set_crypt(abreq, req->src, req->dst,
                     cryptlen, req->iv);

    err = crypto_ablkcipher_decrypt(abreq);

out:
    authenc_esn_request_complete(req, err);
}


static void authenc_esn_verify_ahash_done(struct crypto_async_request *areq,
                      int err)
{
    u8 *ihash;
    unsigned int authsize;
    struct ablkcipher_request *abreq;
    struct aead_request *req = areq->data;
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
    unsigned int cryptlen = req->cryptlen;

    if (err)
        goto out;

    authsize = crypto_aead_authsize(authenc_esn);
    cryptlen -= authsize;
    ihash = ahreq->result + authsize;
    scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
                 authsize, 0);

    err = memcmp(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
    if (err)
        goto out;

    abreq = aead_request_ctx(req);
    ablkcipher_request_set_tfm(abreq, ctx->enc);
    ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                    req->base.complete, req->base.data);
    ablkcipher_request_set_crypt(abreq, req->src, req->dst,
                     cryptlen, req->iv);

    err = crypto_ablkcipher_decrypt(abreq);

out:
    authenc_esn_request_complete(req, err);
}

static u8 *crypto_authenc_esn_ahash(struct aead_request *req,
                    unsigned int flags)
{
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct crypto_ahash *auth = ctx->auth;
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
    u8 *hash = areq_ctx->tail;
    int err;

    hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
                crypto_ahash_alignmask(auth) + 1);

    ahash_request_set_tfm(ahreq, auth);

    err = crypto_ahash_init(ahreq);
    if (err)
        return ERR_PTR(err);

    ahash_request_set_crypt(ahreq, areq_ctx->hsg, hash, areq_ctx->headlen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
                   areq_ctx->update_complete, req);

    err = crypto_ahash_update(ahreq);
    if (err)
        return ERR_PTR(err);

    ahash_request_set_crypt(ahreq, areq_ctx->sg, hash, areq_ctx->cryptlen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
                   areq_ctx->update_complete2, req);

    err = crypto_ahash_update(ahreq);
    if (err)
        return ERR_PTR(err);

    ahash_request_set_crypt(ahreq, areq_ctx->tsg, hash,
                areq_ctx->trailen);
    ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
                   areq_ctx->complete, req);

    err = crypto_ahash_finup(ahreq);
    if (err)
        return ERR_PTR(err);

    return hash;
}

static int crypto_authenc_esn_genicv(struct aead_request *req, u8 *iv,
                     unsigned int flags)
{
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct scatterlist *dst = req->dst;
    struct scatterlist *assoc = req->assoc;
    struct scatterlist *cipher = areq_ctx->cipher;
    struct scatterlist *hsg = areq_ctx->hsg;
    struct scatterlist *tsg = areq_ctx->tsg;
    struct scatterlist *assoc1;
    struct scatterlist *assoc2;
    unsigned int ivsize = crypto_aead_ivsize(authenc_esn);
    unsigned int cryptlen = req->cryptlen;
    struct page *dstp;
    u8 *vdst;
    u8 *hash;

    dstp = sg_page(dst);
    vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;

    if (ivsize) {
        sg_init_table(cipher, 2);
        sg_set_buf(cipher, iv, ivsize);
        scatterwalk_crypto_chain(cipher, dst, vdst == iv + ivsize, 2);
        dst = cipher;
        cryptlen += ivsize;
    }

    if (sg_is_last(assoc))
        return -EINVAL;

    assoc1 = assoc + 1;
    if (sg_is_last(assoc1))
        return -EINVAL;

    assoc2 = assoc + 2;
    if (!sg_is_last(assoc2))
        return -EINVAL;

    sg_init_table(hsg, 2);
    sg_set_page(hsg, sg_page(assoc), assoc->length, assoc->offset);
    sg_set_page(hsg + 1, sg_page(assoc2), assoc2->length, assoc2->offset);

    sg_init_table(tsg, 1);
    sg_set_page(tsg, sg_page(assoc1), assoc1->length, assoc1->offset);

    areq_ctx->cryptlen = cryptlen;
    areq_ctx->headlen = assoc->length + assoc2->length;
    areq_ctx->trailen = assoc1->length;
    areq_ctx->sg = dst;

    areq_ctx->complete = authenc_esn_geniv_ahash_done;
    areq_ctx->update_complete = authenc_esn_geniv_ahash_update_done;
    areq_ctx->update_complete2 = authenc_esn_geniv_ahash_update_done2;

    hash = crypto_authenc_esn_ahash(req, flags);
    if (IS_ERR(hash))
        return PTR_ERR(hash);

    scatterwalk_map_and_copy(hash, dst, cryptlen,
                 crypto_aead_authsize(authenc_esn), 1);
    return 0;
}


static void crypto_authenc_esn_encrypt_done(struct crypto_async_request *req,
                        int err)
{
    struct aead_request *areq = req->data;

    if (!err) {
        struct crypto_aead *authenc_esn = crypto_aead_reqtfm(areq);
        struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
        struct ablkcipher_request *abreq = aead_request_ctx(areq);
        u8 *iv = (u8 *)(abreq + 1) +
             crypto_ablkcipher_reqsize(ctx->enc);

        err = crypto_authenc_esn_genicv(areq, iv, 0);
    }

    authenc_esn_request_complete(areq, err);
}

static int crypto_authenc_esn_encrypt(struct aead_request *req)
{
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct crypto_ablkcipher *enc = ctx->enc;
    struct scatterlist *dst = req->dst;
    unsigned int cryptlen = req->cryptlen;
    struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
                            + ctx->reqoff);
    u8 *iv = (u8 *)abreq - crypto_ablkcipher_ivsize(enc);
    int err;

    ablkcipher_request_set_tfm(abreq, enc);
    ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                    crypto_authenc_esn_encrypt_done, req);
    ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);

    memcpy(iv, req->iv, crypto_aead_ivsize(authenc_esn));

    err = crypto_ablkcipher_encrypt(abreq);
    if (err)
        return err;

    return crypto_authenc_esn_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
}

static void crypto_authenc_esn_givencrypt_done(struct crypto_async_request *req,
                           int err)
{
    struct aead_request *areq = req->data;

    if (!err) {
        struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);

        err = crypto_authenc_esn_genicv(areq, greq->giv, 0);
    }

    authenc_esn_request_complete(areq, err);
}

static int crypto_authenc_esn_givencrypt(struct aead_givcrypt_request *req)
{
    struct crypto_aead *authenc_esn = aead_givcrypt_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct aead_request *areq = &req->areq;
    struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
    u8 *iv = req->giv;
    int err;

    skcipher_givcrypt_set_tfm(greq, ctx->enc);
    skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
                       crypto_authenc_esn_givencrypt_done, areq);
    skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
                    areq->iv);
    skcipher_givcrypt_set_giv(greq, iv, req->seq);

    err = crypto_skcipher_givencrypt(greq);
    if (err)
        return err;

    return crypto_authenc_esn_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
}

static int crypto_authenc_esn_verify(struct aead_request *req)
{
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    u8 *ohash;
    u8 *ihash;
    unsigned int authsize;

    areq_ctx->complete = authenc_esn_verify_ahash_done;
    areq_ctx->update_complete = authenc_esn_verify_ahash_update_done;

    ohash = crypto_authenc_esn_ahash(req, CRYPTO_TFM_REQ_MAY_SLEEP);
    if (IS_ERR(ohash))
        return PTR_ERR(ohash);

    authsize = crypto_aead_authsize(authenc_esn);
    ihash = ohash + authsize;
    scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
                 authsize, 0);
    return memcmp(ihash, ohash, authsize) ? -EBADMSG : 0;
}

static int crypto_authenc_esn_iverify(struct aead_request *req, u8 *iv,
                      unsigned int cryptlen)
{
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
    struct scatterlist *src = req->src;
    struct scatterlist *assoc = req->assoc;
    struct scatterlist *cipher = areq_ctx->cipher;
    struct scatterlist *hsg = areq_ctx->hsg;
    struct scatterlist *tsg = areq_ctx->tsg;
    struct scatterlist *assoc1;
    struct scatterlist *assoc2;
    unsigned int ivsize = crypto_aead_ivsize(authenc_esn);
    struct page *srcp;
    u8 *vsrc;

    srcp = sg_page(src);
    vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;

    if (ivsize) {
        sg_init_table(cipher, 2);
        sg_set_buf(cipher, iv, ivsize);
        scatterwalk_crypto_chain(cipher, src, vsrc == iv + ivsize, 2);
        src = cipher;
        cryptlen += ivsize;
    }

    if (sg_is_last(assoc))
        return -EINVAL;

    assoc1 = assoc + 1;
    if (sg_is_last(assoc1))
        return -EINVAL;

    assoc2 = assoc + 2;
    if (!sg_is_last(assoc2))
        return -EINVAL;

    sg_init_table(hsg, 2);
    sg_set_page(hsg, sg_page(assoc), assoc->length, assoc->offset);
    sg_set_page(hsg + 1, sg_page(assoc2), assoc2->length, assoc2->offset);

    sg_init_table(tsg, 1);
    sg_set_page(tsg, sg_page(assoc1), assoc1->length, assoc1->offset);

    areq_ctx->cryptlen = cryptlen;
    areq_ctx->headlen = assoc->length + assoc2->length;
    areq_ctx->trailen = assoc1->length;
    areq_ctx->sg = src;

    areq_ctx->complete = authenc_esn_verify_ahash_done;
    areq_ctx->update_complete = authenc_esn_verify_ahash_update_done;
    areq_ctx->update_complete2 = authenc_esn_verify_ahash_update_done2;

    return crypto_authenc_esn_verify(req);
}

static int crypto_authenc_esn_decrypt(struct aead_request *req)
{
    struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
    struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
    struct ablkcipher_request *abreq = aead_request_ctx(req);
    unsigned int cryptlen = req->cryptlen;
    unsigned int authsize = crypto_aead_authsize(authenc_esn);
    u8 *iv = req->iv;
    int err;

    if (cryptlen < authsize)
        return -EINVAL;
    cryptlen -= authsize;

    err = crypto_authenc_esn_iverify(req, iv, cryptlen);
    if (err)
        return err;

    ablkcipher_request_set_tfm(abreq, ctx->enc);
    ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                    req->base.complete, req->base.data);
    ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);

    return crypto_ablkcipher_decrypt(abreq);
}

static int crypto_authenc_esn_init_tfm(struct crypto_tfm *tfm)
{
    struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
    struct authenc_esn_instance_ctx *ictx = crypto_instance_ctx(inst);
    struct crypto_authenc_esn_ctx *ctx = crypto_tfm_ctx(tfm);
    struct crypto_ahash *auth;
    struct crypto_ablkcipher *enc;
    int err;

    auth = crypto_spawn_ahash(&ictx->auth);
    if (IS_ERR(auth))
        return PTR_ERR(auth);

    enc = crypto_spawn_skcipher(&ictx->enc);
    err = PTR_ERR(enc);
    if (IS_ERR(enc))
        goto err_free_ahash;

    ctx->auth = auth;
    ctx->enc = enc;

    ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth) +
                crypto_ahash_alignmask(auth),
                crypto_ahash_alignmask(auth) + 1) +
              crypto_ablkcipher_ivsize(enc);

    tfm->crt_aead.reqsize = sizeof(struct authenc_esn_request_ctx) +
                ctx->reqoff +
                max_t(unsigned int,
                crypto_ahash_reqsize(auth) +
                sizeof(struct ahash_request),
                sizeof(struct skcipher_givcrypt_request) +
                crypto_ablkcipher_reqsize(enc));

    return 0;

err_free_ahash:
    crypto_free_ahash(auth);
    return err;
}

static void crypto_authenc_esn_exit_tfm(struct crypto_tfm *tfm)
{
    struct crypto_authenc_esn_ctx *ctx = crypto_tfm_ctx(tfm);

    crypto_free_ahash(ctx->auth);
    crypto_free_ablkcipher(ctx->enc);
}

static struct crypto_instance *crypto_authenc_esn_alloc(struct rtattr **tb)
{
    struct crypto_attr_type *algt;
    struct crypto_instance *inst;
    struct hash_alg_common *auth;
    struct crypto_alg *auth_base;
    struct crypto_alg *enc;
    struct authenc_esn_instance_ctx *ctx;
    const char *enc_name;
    int err;

    algt = crypto_get_attr_type(tb);
    err = PTR_ERR(algt);
    if (IS_ERR(algt))
        return ERR_PTR(err);

    if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
        return ERR_PTR(-EINVAL);

    auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
                   CRYPTO_ALG_TYPE_AHASH_MASK);
    if (IS_ERR(auth))
        return ERR_CAST(auth);

    auth_base = &auth->base;

    enc_name = crypto_attr_alg_name(tb[2]);
    err = PTR_ERR(enc_name);
    if (IS_ERR(enc_name))
        goto out_put_auth;

    inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
    err = -ENOMEM;
    if (!inst)
        goto out_put_auth;

    ctx = crypto_instance_ctx(inst);

    err = crypto_init_ahash_spawn(&ctx->auth, auth, inst);
    if (err)
        goto err_free_inst;

    crypto_set_skcipher_spawn(&ctx->enc, inst);
    err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
                   crypto_requires_sync(algt->type,
                            algt->mask));
    if (err)
        goto err_drop_auth;

    enc = crypto_skcipher_spawn_alg(&ctx->enc);

    err = -ENAMETOOLONG;
    if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
             "authencesn(%s,%s)", auth_base->cra_name, enc->cra_name) >=
        CRYPTO_MAX_ALG_NAME)
        goto err_drop_enc;

    if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
             "authencesn(%s,%s)", auth_base->cra_driver_name,
             enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
        goto err_drop_enc;

    inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
    inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
    inst->alg.cra_priority = enc->cra_priority *
                 10 + auth_base->cra_priority;
    inst->alg.cra_blocksize = enc->cra_blocksize;
    inst->alg.cra_alignmask = auth_base->cra_alignmask | enc->cra_alignmask;
    inst->alg.cra_type = &crypto_aead_type;

    inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
    inst->alg.cra_aead.maxauthsize = auth->digestsize;

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

    inst->alg.cra_init = crypto_authenc_esn_init_tfm;
    inst->alg.cra_exit = crypto_authenc_esn_exit_tfm;

    inst->alg.cra_aead.setkey = crypto_authenc_esn_setkey;
    inst->alg.cra_aead.encrypt = crypto_authenc_esn_encrypt;
    inst->alg.cra_aead.decrypt = crypto_authenc_esn_decrypt;
    inst->alg.cra_aead.givencrypt = crypto_authenc_esn_givencrypt;

out:
    crypto_mod_put(auth_base);
    return inst;

err_drop_enc:
    crypto_drop_skcipher(&ctx->enc);
err_drop_auth:
    crypto_drop_ahash(&ctx->auth);
err_free_inst:
    kfree(inst);
out_put_auth:
    inst = ERR_PTR(err);
    goto out;
}

static void crypto_authenc_esn_free(struct crypto_instance *inst)
{
    struct authenc_esn_instance_ctx *ctx = crypto_instance_ctx(inst);

    crypto_drop_skcipher(&ctx->enc);
    crypto_drop_ahash(&ctx->auth);
    kfree(inst);
}

static struct crypto_template crypto_authenc_esn_tmpl = {
    .name = "authencesn",
    .alloc = crypto_authenc_esn_alloc,
    .free = crypto_authenc_esn_free,
    .module = THIS_MODULE,
};

static int __init crypto_authenc_esn_module_init(void)
{
    return crypto_register_template(&crypto_authenc_esn_tmpl);
}

static void __exit crypto_authenc_esn_module_exit(void)
{
    crypto_unregister_template(&crypto_authenc_esn_tmpl);
}

module_init(crypto_authenc_esn_module_init);
module_exit(crypto_authenc_esn_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Steffen Klassert <[email protected]>");
MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");