/*
 * CCM: Counter with CBC-MAC
 *
 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
 *
 * 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/internal/aead.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>

#include "internal.h"

struct ccm_instance_ctx {
        struct crypto_skcipher_spawn ctr;
        struct crypto_ahash_spawn mac;
};

struct crypto_ccm_ctx {
        struct crypto_ahash *mac;
        struct crypto_skcipher *ctr;
};

struct crypto_rfc4309_ctx {
        struct crypto_aead *child;
        u8 nonce[3];
};

struct crypto_rfc4309_req_ctx {
        struct scatterlist src[3];
        struct scatterlist dst[3];
        struct aead_request subreq;
};

struct crypto_ccm_req_priv_ctx {
        u8 odata[16];
        u8 idata[16];
        u8 auth_tag[16];
        u32 flags;
        struct scatterlist src[3];
        struct scatterlist dst[3];
        union {
                struct ahash_request ahreq;
                struct skcipher_request skreq;
        };
};

struct cbcmac_tfm_ctx {
        struct crypto_cipher *child;
};

struct cbcmac_desc_ctx {
        unsigned int len;
};

static inline struct crypto_ccm_req_priv_ctx *crypto_ccm_reqctx(
        struct aead_request *req)
{
        unsigned long align = crypto_aead_alignmask(crypto_aead_reqtfm(req));

        return (void *)PTR_ALIGN((u8 *)aead_request_ctx(req), align + 1);
}

static int set_msg_len(u8 *block, unsigned int msglen, int csize)
{
        __be32 data;

        memset(block, 0, csize);
        block += csize;

        if (csize >= 4)
                csize = 4;
        else if (msglen > (1 << (8 * csize)))
                return -EOVERFLOW;

        data = cpu_to_be32(msglen);
        memcpy(block - csize, (u8 *)&data + 4 - csize, csize);

        return 0;
}

static int crypto_ccm_setkey(struct crypto_aead *aead, const u8 *key,
                             unsigned int keylen)
{
        struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
        struct crypto_skcipher *ctr = ctx->ctr;
        struct crypto_ahash *mac = ctx->mac;
        int err = 0;

        crypto_skcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
        crypto_skcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
                                       CRYPTO_TFM_REQ_MASK);
        err = crypto_skcipher_setkey(ctr, key, keylen);
        crypto_aead_set_flags(aead, crypto_skcipher_get_flags(ctr) &
                              CRYPTO_TFM_RES_MASK);
        if (err)
                goto out;

        crypto_ahash_clear_flags(mac, CRYPTO_TFM_REQ_MASK);
        crypto_ahash_set_flags(mac, crypto_aead_get_flags(aead) &
                                    CRYPTO_TFM_REQ_MASK);
        err = crypto_ahash_setkey(mac, key, keylen);
        crypto_aead_set_flags(aead, crypto_ahash_get_flags(mac) &
                              CRYPTO_TFM_RES_MASK);

out:
        return err;
}

static int crypto_ccm_setauthsize(struct crypto_aead *tfm,
                                  unsigned int authsize)
{
        switch (authsize) {
        case 4:
        case 6:
        case 8:
        case 10:
        case 12:
        case 14:
        case 16:
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int format_input(u8 *info, struct aead_request *req,
                        unsigned int cryptlen)
{
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        unsigned int lp = req->iv[0];
        unsigned int l = lp + 1;
        unsigned int m;

        m = crypto_aead_authsize(aead);

        memcpy(info, req->iv, 16);

        /* format control info per RFC 3610 and
         * NIST Special Publication 800-38C
         */
        *info |= (8 * ((m - 2) / 2));
        if (req->assoclen)
                *info |= 64;

        return set_msg_len(info + 16 - l, cryptlen, l);
}

static int format_adata(u8 *adata, unsigned int a)
{
        int len = 0;

        /* add control info for associated data
         * RFC 3610 and NIST Special Publication 800-38C
         */
        if (a < 65280) {
                *(__be16 *)adata = cpu_to_be16(a);
                len = 2;
        } else  {
                *(__be16 *)adata = cpu_to_be16(0xfffe);
                *(__be32 *)&adata[2] = cpu_to_be32(a);
                len = 6;
        }

        return len;
}

static int crypto_ccm_auth(struct aead_request *req, struct scatterlist *plain,
                           unsigned int cryptlen)
{
        struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
        struct ahash_request *ahreq = &pctx->ahreq;
        unsigned int assoclen = req->assoclen;
        struct scatterlist sg[3];
        u8 *odata = pctx->odata;
        u8 *idata = pctx->idata;
        int ilen, err;

        /* format control data for input */
        err = format_input(odata, req, cryptlen);
        if (err)
                goto out;

        sg_init_table(sg, 3);
        sg_set_buf(&sg[0], odata, 16);

        /* format associated data and compute into mac */
        if (assoclen) {
                ilen = format_adata(idata, assoclen);
                sg_set_buf(&sg[1], idata, ilen);
                sg_chain(sg, 3, req->src);
        } else {
                ilen = 0;
                sg_chain(sg, 2, req->src);
        }

        ahash_request_set_tfm(ahreq, ctx->mac);
        ahash_request_set_callback(ahreq, pctx->flags, NULL, NULL);
        ahash_request_set_crypt(ahreq, sg, NULL, assoclen + ilen + 16);
        err = crypto_ahash_init(ahreq);
        if (err)
                goto out;
        err = crypto_ahash_update(ahreq);
        if (err)
                goto out;

        /* we need to pad the MAC input to a round multiple of the block size */
        ilen = 16 - (assoclen + ilen) % 16;
        if (ilen < 16) {
                memset(idata, 0, ilen);
                sg_init_table(sg, 2);
                sg_set_buf(&sg[0], idata, ilen);
                if (plain)
                        sg_chain(sg, 2, plain);
                plain = sg;
                cryptlen += ilen;
        }

        ahash_request_set_crypt(ahreq, plain, pctx->odata, cryptlen);
        err = crypto_ahash_finup(ahreq);
out:
        return err;
}

static void crypto_ccm_encrypt_done(struct crypto_async_request *areq, int err)
{
        struct aead_request *req = areq->data;
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
        u8 *odata = pctx->odata;

        if (!err)
                scatterwalk_map_and_copy(odata, req->dst,
                                         req->assoclen + req->cryptlen,
                                         crypto_aead_authsize(aead), 1);
        aead_request_complete(req, err);
}

static inline int crypto_ccm_check_iv(const u8 *iv)
{
        /* 2 <= L <= 8, so 1 <= L' <= 7. */
        if (1 > iv[0] || iv[0] > 7)
                return -EINVAL;

        return 0;
}

static int crypto_ccm_init_crypt(struct aead_request *req, u8 *tag)
{
        struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
        struct scatterlist *sg;
        u8 *iv = req->iv;
        int err;

        err = crypto_ccm_check_iv(iv);
        if (err)
                return err;

        pctx->flags = aead_request_flags(req);

         /* Note: rfc 3610 and NIST 800-38C require counter of
         * zero to encrypt auth tag.
         */
        memset(iv + 15 - iv[0], 0, iv[0] + 1);

        sg_init_table(pctx->src, 3);
        sg_set_buf(pctx->src, tag, 16);
        sg = scatterwalk_ffwd(pctx->src + 1, req->src, req->assoclen);
        if (sg != pctx->src + 1)
                sg_chain(pctx->src, 2, sg);

        if (req->src != req->dst) {
                sg_init_table(pctx->dst, 3);
                sg_set_buf(pctx->dst, tag, 16);
                sg = scatterwalk_ffwd(pctx->dst + 1, req->dst, req->assoclen);
                if (sg != pctx->dst + 1)
                        sg_chain(pctx->dst, 2, sg);
        }

        return 0;
}

static int crypto_ccm_encrypt(struct aead_request *req)
{
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
        struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
        struct skcipher_request *skreq = &pctx->skreq;
        struct scatterlist *dst;
        unsigned int cryptlen = req->cryptlen;
        u8 *odata = pctx->odata;
        u8 *iv = req->iv;
        int err;

        err = crypto_ccm_init_crypt(req, odata);
        if (err)
                return err;

        err = crypto_ccm_auth(req, sg_next(pctx->src), cryptlen);
        if (err)
                return err;

        dst = pctx->src;
        if (req->src != req->dst)
                dst = pctx->dst;

        skcipher_request_set_tfm(skreq, ctx->ctr);
        skcipher_request_set_callback(skreq, pctx->flags,
                                      crypto_ccm_encrypt_done, req);
        skcipher_request_set_crypt(skreq, pctx->src, dst, cryptlen + 16, iv);
        err = crypto_skcipher_encrypt(skreq);
        if (err)
                return err;

        /* copy authtag to end of dst */
        scatterwalk_map_and_copy(odata, sg_next(dst), cryptlen,
                                 crypto_aead_authsize(aead), 1);
        return err;
}

static void crypto_ccm_decrypt_done(struct crypto_async_request *areq,
                                   int err)
{
        struct aead_request *req = areq->data;
        struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        unsigned int authsize = crypto_aead_authsize(aead);
        unsigned int cryptlen = req->cryptlen - authsize;
        struct scatterlist *dst;

        pctx->flags = 0;

        dst = sg_next(req->src == req->dst ? pctx->src : pctx->dst);

        if (!err) {
                err = crypto_ccm_auth(req, dst, cryptlen);
                if (!err && crypto_memneq(pctx->auth_tag, pctx->odata, authsize))
                        err = -EBADMSG;
        }
        aead_request_complete(req, err);
}

static int crypto_ccm_decrypt(struct aead_request *req)
{
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead);
        struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req);
        struct skcipher_request *skreq = &pctx->skreq;
        struct scatterlist *dst;
        unsigned int authsize = crypto_aead_authsize(aead);
        unsigned int cryptlen = req->cryptlen;
        u8 *authtag = pctx->auth_tag;
        u8 *odata = pctx->odata;
        u8 *iv = pctx->idata;
        int err;

        cryptlen -= authsize;

        err = crypto_ccm_init_crypt(req, authtag);
        if (err)
                return err;

        scatterwalk_map_and_copy(authtag, sg_next(pctx->src), cryptlen,
                                 authsize, 0);

        dst = pctx->src;
        if (req->src != req->dst)
                dst = pctx->dst;

        memcpy(iv, req->iv, 16);

        skcipher_request_set_tfm(skreq, ctx->ctr);
        skcipher_request_set_callback(skreq, pctx->flags,
                                      crypto_ccm_decrypt_done, req);
        skcipher_request_set_crypt(skreq, pctx->src, dst, cryptlen + 16, iv);
        err = crypto_skcipher_decrypt(skreq);
        if (err)
                return err;

        err = crypto_ccm_auth(req, sg_next(dst), cryptlen);
        if (err)
                return err;

        /* verify */
        if (crypto_memneq(authtag, odata, authsize))
                return -EBADMSG;

        return err;
}

static int crypto_ccm_init_tfm(struct crypto_aead *tfm)
{
        struct aead_instance *inst = aead_alg_instance(tfm);
        struct ccm_instance_ctx *ictx = aead_instance_ctx(inst);
        struct crypto_ccm_ctx *ctx = crypto_aead_ctx(tfm);
        struct crypto_ahash *mac;
        struct crypto_skcipher *ctr;
        unsigned long align;
        int err;

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

        ctr = crypto_spawn_skcipher(&ictx->ctr);
        err = PTR_ERR(ctr);
        if (IS_ERR(ctr))
                goto err_free_mac;

        ctx->mac = mac;
        ctx->ctr = ctr;

        align = crypto_aead_alignmask(tfm);
        align &= ~(crypto_tfm_ctx_alignment() - 1);
        crypto_aead_set_reqsize(
                tfm,
                align + sizeof(struct crypto_ccm_req_priv_ctx) +
                max(crypto_ahash_reqsize(mac), crypto_skcipher_reqsize(ctr)));

        return 0;

err_free_mac:
        crypto_free_ahash(mac);
        return err;
}

static void crypto_ccm_exit_tfm(struct crypto_aead *tfm)
{
        struct crypto_ccm_ctx *ctx = crypto_aead_ctx(tfm);

        crypto_free_ahash(ctx->mac);
        crypto_free_skcipher(ctx->ctr);
}

static void crypto_ccm_free(struct aead_instance *inst)
{
        struct ccm_instance_ctx *ctx = aead_instance_ctx(inst);

        crypto_drop_ahash(&ctx->mac);
        crypto_drop_skcipher(&ctx->ctr);
        kfree(inst);
}

static int crypto_ccm_create_common(struct crypto_template *tmpl,
                                    struct rtattr **tb,
                                    const char *full_name,
                                    const char *ctr_name,
                                    const char *mac_name)
{
        struct crypto_attr_type *algt;
        struct aead_instance *inst;
        struct skcipher_alg *ctr;
        struct crypto_alg *mac_alg;
        struct hash_alg_common *mac;
        struct ccm_instance_ctx *ictx;
        int err;

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

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

        mac_alg = crypto_find_alg(mac_name, &crypto_ahash_type,
                                  CRYPTO_ALG_TYPE_HASH,
                                  CRYPTO_ALG_TYPE_AHASH_MASK |
                                  CRYPTO_ALG_ASYNC);
        if (IS_ERR(mac_alg))
                return PTR_ERR(mac_alg);

        mac = __crypto_hash_alg_common(mac_alg);
        err = -EINVAL;
        if (mac->digestsize != 16)
                goto out_put_mac;

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

        ictx = aead_instance_ctx(inst);
        err = crypto_init_ahash_spawn(&ictx->mac, mac,
                                      aead_crypto_instance(inst));
        if (err)
                goto err_free_inst;

        crypto_set_skcipher_spawn(&ictx->ctr, aead_crypto_instance(inst));
        err = crypto_grab_skcipher(&ictx->ctr, ctr_name, 0,
                                   crypto_requires_sync(algt->type,
                                                        algt->mask));
        if (err)
                goto err_drop_mac;

        ctr = crypto_spawn_skcipher_alg(&ictx->ctr);

        /* Not a stream cipher? */
        err = -EINVAL;
        if (ctr->base.cra_blocksize != 1)
                goto err_drop_ctr;

        /* We want the real thing! */
        if (crypto_skcipher_alg_ivsize(ctr) != 16)
                goto err_drop_ctr;

        err = -ENAMETOOLONG;
        if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
                     "ccm_base(%s,%s)", ctr->base.cra_driver_name,
                     mac->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
                goto err_drop_ctr;

        memcpy(inst->alg.base.cra_name, full_name, CRYPTO_MAX_ALG_NAME);

        inst->alg.base.cra_flags = ctr->base.cra_flags & CRYPTO_ALG_ASYNC;
        inst->alg.base.cra_priority = (mac->base.cra_priority +
                                       ctr->base.cra_priority) / 2;
        inst->alg.base.cra_blocksize = 1;
        inst->alg.base.cra_alignmask = mac->base.cra_alignmask |
                                       ctr->base.cra_alignmask;
        inst->alg.ivsize = 16;
        inst->alg.chunksize = crypto_skcipher_alg_chunksize(ctr);
        inst->alg.maxauthsize = 16;
        inst->alg.base.cra_ctxsize = sizeof(struct crypto_ccm_ctx);
        inst->alg.init = crypto_ccm_init_tfm;
        inst->alg.exit = crypto_ccm_exit_tfm;
        inst->alg.setkey = crypto_ccm_setkey;
        inst->alg.setauthsize = crypto_ccm_setauthsize;
        inst->alg.encrypt = crypto_ccm_encrypt;
        inst->alg.decrypt = crypto_ccm_decrypt;

        inst->free = crypto_ccm_free;

        err = aead_register_instance(tmpl, inst);
        if (err)
                goto err_drop_ctr;

out_put_mac:
        crypto_mod_put(mac_alg);
        return err;

err_drop_ctr:
        crypto_drop_skcipher(&ictx->ctr);
err_drop_mac:
        crypto_drop_ahash(&ictx->mac);
err_free_inst:
        kfree(inst);
        goto out_put_mac;
}

static int crypto_ccm_create(struct crypto_template *tmpl, struct rtattr **tb)
{
        const char *cipher_name;
        char ctr_name[CRYPTO_MAX_ALG_NAME];
        char mac_name[CRYPTO_MAX_ALG_NAME];
        char full_name[CRYPTO_MAX_ALG_NAME];

        cipher_name = crypto_attr_alg_name(tb[1]);
        if (IS_ERR(cipher_name))
                return PTR_ERR(cipher_name);

        if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
                     cipher_name) >= CRYPTO_MAX_ALG_NAME)
                return -ENAMETOOLONG;

        if (snprintf(mac_name, CRYPTO_MAX_ALG_NAME, "cbcmac(%s)",
                     cipher_name) >= CRYPTO_MAX_ALG_NAME)
                return -ENAMETOOLONG;

        if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm(%s)", cipher_name) >=
            CRYPTO_MAX_ALG_NAME)
                return -ENAMETOOLONG;

        return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name,
                                        mac_name);
}

static struct crypto_template crypto_ccm_tmpl = {
        .name = "ccm",
        .create = crypto_ccm_create,
        .module = THIS_MODULE,
};

static int crypto_ccm_base_create(struct crypto_template *tmpl,
                                  struct rtattr **tb)
{
        const char *ctr_name;
        const char *cipher_name;
        char full_name[CRYPTO_MAX_ALG_NAME];

        ctr_name = crypto_attr_alg_name(tb[1]);
        if (IS_ERR(ctr_name))
                return PTR_ERR(ctr_name);

        cipher_name = crypto_attr_alg_name(tb[2]);
        if (IS_ERR(cipher_name))
                return PTR_ERR(cipher_name);

        if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "ccm_base(%s,%s)",
                     ctr_name, cipher_name) >= CRYPTO_MAX_ALG_NAME)
                return -ENAMETOOLONG;

        return crypto_ccm_create_common(tmpl, tb, full_name, ctr_name,
                                        cipher_name);
}

static struct crypto_template crypto_ccm_base_tmpl = {
        .name = "ccm_base",
        .create = crypto_ccm_base_create,
        .module = THIS_MODULE,
};

static int crypto_rfc4309_setkey(struct crypto_aead *parent, const u8 *key,
                                 unsigned int keylen)
{
        struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(parent);
        struct crypto_aead *child = ctx->child;
        int err;

        if (keylen < 3)
                return -EINVAL;

        keylen -= 3;
        memcpy(ctx->nonce, key + keylen, 3);

        crypto_aead_clear_flags(child, CRYPTO_TFM_REQ_MASK);
        crypto_aead_set_flags(child, crypto_aead_get_flags(parent) &
                                     CRYPTO_TFM_REQ_MASK);
        err = crypto_aead_setkey(child, key, keylen);
        crypto_aead_set_flags(parent, crypto_aead_get_flags(child) &
                                      CRYPTO_TFM_RES_MASK);

        return err;
}

static int crypto_rfc4309_setauthsize(struct crypto_aead *parent,
                                      unsigned int authsize)
{
        struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(parent);

        switch (authsize) {
        case 8:
        case 12:
        case 16:
                break;
        default:
                return -EINVAL;
        }

        return crypto_aead_setauthsize(ctx->child, authsize);
}

static struct aead_request *crypto_rfc4309_crypt(struct aead_request *req)
{
        struct crypto_rfc4309_req_ctx *rctx = aead_request_ctx(req);
        struct aead_request *subreq = &rctx->subreq;
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(aead);
        struct crypto_aead *child = ctx->child;
        struct scatterlist *sg;
        u8 *iv = PTR_ALIGN((u8 *)(subreq + 1) + crypto_aead_reqsize(child),
                           crypto_aead_alignmask(child) + 1);

        /* L' */
        iv[0] = 3;

        memcpy(iv + 1, ctx->nonce, 3);
        memcpy(iv + 4, req->iv, 8);

        scatterwalk_map_and_copy(iv + 16, req->src, 0, req->assoclen - 8, 0);

        sg_init_table(rctx->src, 3);
        sg_set_buf(rctx->src, iv + 16, req->assoclen - 8);
        sg = scatterwalk_ffwd(rctx->src + 1, req->src, req->assoclen);
        if (sg != rctx->src + 1)
                sg_chain(rctx->src, 2, sg);

        if (req->src != req->dst) {
                sg_init_table(rctx->dst, 3);
                sg_set_buf(rctx->dst, iv + 16, req->assoclen - 8);
                sg = scatterwalk_ffwd(rctx->dst + 1, req->dst, req->assoclen);
                if (sg != rctx->dst + 1)
                        sg_chain(rctx->dst, 2, sg);
        }

        aead_request_set_tfm(subreq, child);
        aead_request_set_callback(subreq, req->base.flags, req->base.complete,
                                  req->base.data);
        aead_request_set_crypt(subreq, rctx->src,
                               req->src == req->dst ? rctx->src : rctx->dst,
                               req->cryptlen, iv);
        aead_request_set_ad(subreq, req->assoclen - 8);

        return subreq;
}

static int crypto_rfc4309_encrypt(struct aead_request *req)
{
        if (req->assoclen != 16 && req->assoclen != 20)
                return -EINVAL;

        req = crypto_rfc4309_crypt(req);

        return crypto_aead_encrypt(req);
}

static int crypto_rfc4309_decrypt(struct aead_request *req)
{
        if (req->assoclen != 16 && req->assoclen != 20)
                return -EINVAL;

        req = crypto_rfc4309_crypt(req);

        return crypto_aead_decrypt(req);
}

static int crypto_rfc4309_init_tfm(struct crypto_aead *tfm)
{
        struct aead_instance *inst = aead_alg_instance(tfm);
        struct crypto_aead_spawn *spawn = aead_instance_ctx(inst);
        struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(tfm);
        struct crypto_aead *aead;
        unsigned long align;

        aead = crypto_spawn_aead(spawn);
        if (IS_ERR(aead))
                return PTR_ERR(aead);

        ctx->child = aead;

        align = crypto_aead_alignmask(aead);
        align &= ~(crypto_tfm_ctx_alignment() - 1);
        crypto_aead_set_reqsize(
                tfm,
                sizeof(struct crypto_rfc4309_req_ctx) +
                ALIGN(crypto_aead_reqsize(aead), crypto_tfm_ctx_alignment()) +
                align + 32);

        return 0;
}

static void crypto_rfc4309_exit_tfm(struct crypto_aead *tfm)
{
        struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(tfm);

        crypto_free_aead(ctx->child);
}

static void crypto_rfc4309_free(struct aead_instance *inst)
{
        crypto_drop_aead(aead_instance_ctx(inst));
        kfree(inst);
}

static int crypto_rfc4309_create(struct crypto_template *tmpl,
                                 struct rtattr **tb)
{
        struct crypto_attr_type *algt;
        struct aead_instance *inst;
        struct crypto_aead_spawn *spawn;
        struct aead_alg *alg;
        const char *ccm_name;
        int err;

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

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

        ccm_name = crypto_attr_alg_name(tb[1]);
        if (IS_ERR(ccm_name))
                return PTR_ERR(ccm_name);

        inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
        if (!inst)
                return -ENOMEM;

        spawn = aead_instance_ctx(inst);
        crypto_set_aead_spawn(spawn, aead_crypto_instance(inst));
        err = crypto_grab_aead(spawn, ccm_name, 0,
                               crypto_requires_sync(algt->type, algt->mask));
        if (err)
                goto out_free_inst;

        alg = crypto_spawn_aead_alg(spawn);

        err = -EINVAL;

        /* We only support 16-byte blocks. */
        if (crypto_aead_alg_ivsize(alg) != 16)
                goto out_drop_alg;

        /* Not a stream cipher? */
        if (alg->base.cra_blocksize != 1)
                goto out_drop_alg;

        err = -ENAMETOOLONG;
        if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
                     "rfc4309(%s)", alg->base.cra_name) >=
            CRYPTO_MAX_ALG_NAME ||
            snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
                     "rfc4309(%s)", alg->base.cra_driver_name) >=
            CRYPTO_MAX_ALG_NAME)
                goto out_drop_alg;

        inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
        inst->alg.base.cra_priority = alg->base.cra_priority;
        inst->alg.base.cra_blocksize = 1;
        inst->alg.base.cra_alignmask = alg->base.cra_alignmask;

        inst->alg.ivsize = 8;
        inst->alg.chunksize = crypto_aead_alg_chunksize(alg);
        inst->alg.maxauthsize = 16;

        inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc4309_ctx);

        inst->alg.init = crypto_rfc4309_init_tfm;
        inst->alg.exit = crypto_rfc4309_exit_tfm;

        inst->alg.setkey = crypto_rfc4309_setkey;
        inst->alg.setauthsize = crypto_rfc4309_setauthsize;
        inst->alg.encrypt = crypto_rfc4309_encrypt;
        inst->alg.decrypt = crypto_rfc4309_decrypt;

        inst->free = crypto_rfc4309_free;

        err = aead_register_instance(tmpl, inst);
        if (err)
                goto out_drop_alg;

out:
        return err;

out_drop_alg:
        crypto_drop_aead(spawn);
out_free_inst:
        kfree(inst);
        goto out;
}

static struct crypto_template crypto_rfc4309_tmpl = {
        .name = "rfc4309",
        .create = crypto_rfc4309_create,
        .module = THIS_MODULE,
};

static int crypto_cbcmac_digest_setkey(struct crypto_shash *parent,
                                     const u8 *inkey, unsigned int keylen)
{
        struct cbcmac_tfm_ctx *ctx = crypto_shash_ctx(parent);

        return crypto_cipher_setkey(ctx->child, inkey, keylen);
}

static int crypto_cbcmac_digest_init(struct shash_desc *pdesc)
{
        struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
        int bs = crypto_shash_digestsize(pdesc->tfm);
        u8 *dg = (u8 *)ctx + crypto_shash_descsize(pdesc->tfm) - bs;

        ctx->len = 0;
        memset(dg, 0, bs);

        return 0;
}

static int crypto_cbcmac_digest_update(struct shash_desc *pdesc, const u8 *p,
                                       unsigned int len)
{
        struct crypto_shash *parent = pdesc->tfm;
        struct cbcmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
        struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
        struct crypto_cipher *tfm = tctx->child;
        int bs = crypto_shash_digestsize(parent);
        u8 *dg = (u8 *)ctx + crypto_shash_descsize(parent) - bs;

        while (len > 0) {
                unsigned int l = min(len, bs - ctx->len);

                crypto_xor(dg + ctx->len, p, l);
                ctx->len +=l;
                len -= l;
                p += l;

                if (ctx->len == bs) {
                        crypto_cipher_encrypt_one(tfm, dg, dg);
                        ctx->len = 0;
                }
        }

        return 0;
}

static int crypto_cbcmac_digest_final(struct shash_desc *pdesc, u8 *out)
{
        struct crypto_shash *parent = pdesc->tfm;
        struct cbcmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
        struct cbcmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
        struct crypto_cipher *tfm = tctx->child;
        int bs = crypto_shash_digestsize(parent);
        u8 *dg = (u8 *)ctx + crypto_shash_descsize(parent) - bs;

        if (ctx->len)
                crypto_cipher_encrypt_one(tfm, dg, dg);

        memcpy(out, dg, bs);
        return 0;
}

static int cbcmac_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 cbcmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);

        cipher = crypto_spawn_cipher(spawn);
        if (IS_ERR(cipher))
                return PTR_ERR(cipher);

        ctx->child = cipher;

        return 0;
};

static void cbcmac_exit_tfm(struct crypto_tfm *tfm)
{
        struct cbcmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
        crypto_free_cipher(ctx->child);
}

static int cbcmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
        struct shash_instance *inst;
        struct crypto_alg *alg;
        int err;

        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
        if (err)
                return err;

        alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
                                  CRYPTO_ALG_TYPE_MASK);
        if (IS_ERR(alg))
                return PTR_ERR(alg);

        inst = shash_alloc_instance("cbcmac", alg);
        err = PTR_ERR(inst);
        if (IS_ERR(inst))
                goto out_put_alg;

        err = crypto_init_spawn(shash_instance_ctx(inst), alg,
                                shash_crypto_instance(inst),
                                CRYPTO_ALG_TYPE_MASK);
        if (err)
                goto out_free_inst;

        inst->alg.base.cra_priority = alg->cra_priority;
        inst->alg.base.cra_blocksize = 1;

        inst->alg.digestsize = alg->cra_blocksize;
        inst->alg.descsize = ALIGN(sizeof(struct cbcmac_desc_ctx),
                                   alg->cra_alignmask + 1) +
                             alg->cra_blocksize;

        inst->alg.base.cra_ctxsize = sizeof(struct cbcmac_tfm_ctx);
        inst->alg.base.cra_init = cbcmac_init_tfm;
        inst->alg.base.cra_exit = cbcmac_exit_tfm;

        inst->alg.init = crypto_cbcmac_digest_init;
        inst->alg.update = crypto_cbcmac_digest_update;
        inst->alg.final = crypto_cbcmac_digest_final;
        inst->alg.setkey = crypto_cbcmac_digest_setkey;

        err = shash_register_instance(tmpl, inst);

out_free_inst:
        if (err)
                shash_free_instance(shash_crypto_instance(inst));

out_put_alg:
        crypto_mod_put(alg);
        return err;
}

static struct crypto_template crypto_cbcmac_tmpl = {
        .name = "cbcmac",
        .create = cbcmac_create,
        .free = shash_free_instance,
        .module = THIS_MODULE,
};

static int __init crypto_ccm_module_init(void)
{
        int err;

        err = crypto_register_template(&crypto_cbcmac_tmpl);
        if (err)
                goto out;

        err = crypto_register_template(&crypto_ccm_base_tmpl);
        if (err)
                goto out_undo_cbcmac;

        err = crypto_register_template(&crypto_ccm_tmpl);
        if (err)
                goto out_undo_base;

        err = crypto_register_template(&crypto_rfc4309_tmpl);
        if (err)
                goto out_undo_ccm;

out:
        return err;

out_undo_ccm:
        crypto_unregister_template(&crypto_ccm_tmpl);
out_undo_base:
        crypto_unregister_template(&crypto_ccm_base_tmpl);
out_undo_cbcmac:
        crypto_register_template(&crypto_cbcmac_tmpl);
        goto out;
}

static void __exit crypto_ccm_module_exit(void)
{
        crypto_unregister_template(&crypto_rfc4309_tmpl);
        crypto_unregister_template(&crypto_ccm_tmpl);
        crypto_unregister_template(&crypto_ccm_base_tmpl);
        crypto_unregister_template(&crypto_cbcmac_tmpl);
}

module_init(crypto_ccm_module_init);
module_exit(crypto_ccm_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Counter with CBC MAC");
MODULE_ALIAS_CRYPTO("ccm_base");
MODULE_ALIAS_CRYPTO("rfc4309");
MODULE_ALIAS_CRYPTO("ccm");