gcm.c

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/*
 * GCM: Galois/Counter Mode.
 *
 * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include <crypto/gf128mul.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/internal/hash.h>
#include <crypto/scatterwalk.h>
#include <crypto/hash.h>
#include "internal.h"
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>

struct gcm_instance_ctx {
    struct crypto_skcipher_spawn ctr;
    struct crypto_ahash_spawn ghash;
};

struct crypto_gcm_ctx {
    struct crypto_ablkcipher *ctr;
    struct crypto_ahash *ghash;
};

struct crypto_rfc4106_ctx {
    struct crypto_aead *child;
    u8 nonce[4];
};

struct crypto_rfc4543_ctx {
    struct crypto_aead *child;
    u8 nonce[4];
};

struct crypto_rfc4543_req_ctx {
    u8 auth_tag[16];
    struct scatterlist cipher[1];
    struct scatterlist payload[2];
    struct scatterlist assoc[2];
    struct aead_request subreq;
};

struct crypto_gcm_ghash_ctx {
    unsigned int cryptlen;
    struct scatterlist *src;
    void (*complete)(struct aead_request *req, int err);
};

struct crypto_gcm_req_priv_ctx {
    u8 auth_tag[16];
    u8 iauth_tag[16];
    struct scatterlist src[2];
    struct scatterlist dst[2];
    struct crypto_gcm_ghash_ctx ghash_ctx;
    union {
        struct ahash_request ahreq;
        struct ablkcipher_request abreq;
    } u;
};

struct crypto_gcm_setkey_result {
    int err;
    struct completion completion;
};

static void *gcm_zeroes;

static inline struct crypto_gcm_req_priv_ctx *crypto_gcm_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 void crypto_gcm_setkey_done(struct crypto_async_request *req, int err)
{
    struct crypto_gcm_setkey_result *result = req->data;

    if (err == -EINPROGRESS)
        return;

    result->err = err;
    complete(&result->completion);
}

static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
                 unsigned int keylen)
{
    struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
    struct crypto_ahash *ghash = ctx->ghash;
    struct crypto_ablkcipher *ctr = ctx->ctr;
    struct {
        be128 hash;
        u8 iv[8];

        struct crypto_gcm_setkey_result result;

        struct scatterlist sg[1];
        struct ablkcipher_request req;
    } *data;
    int err;

    crypto_ablkcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
    crypto_ablkcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
                   CRYPTO_TFM_REQ_MASK);

    err = crypto_ablkcipher_setkey(ctr, key, keylen);
    if (err)
        return err;

    crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
                       CRYPTO_TFM_RES_MASK);

    data = kzalloc(sizeof(*data) + crypto_ablkcipher_reqsize(ctr),
               GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    init_completion(&data->result.completion);
    sg_init_one(data->sg, &data->hash, sizeof(data->hash));
    ablkcipher_request_set_tfm(&data->req, ctr);
    ablkcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
                            CRYPTO_TFM_REQ_MAY_BACKLOG,
                    crypto_gcm_setkey_done,
                    &data->result);
    ablkcipher_request_set_crypt(&data->req, data->sg, data->sg,
                     sizeof(data->hash), data->iv);

    err = crypto_ablkcipher_encrypt(&data->req);
    if (err == -EINPROGRESS || err == -EBUSY) {
        err = wait_for_completion_interruptible(
            &data->result.completion);
        if (!err)
            err = data->result.err;
    }

    if (err)
        goto out;

    crypto_ahash_clear_flags(ghash, CRYPTO_TFM_REQ_MASK);
    crypto_ahash_set_flags(ghash, crypto_aead_get_flags(aead) &
                   CRYPTO_TFM_REQ_MASK);
    err = crypto_ahash_setkey(ghash, (u8 *)&data->hash, sizeof(be128));
    crypto_aead_set_flags(aead, crypto_ahash_get_flags(ghash) &
                  CRYPTO_TFM_RES_MASK);

out:
    kfree(data);
    return err;
}

static int crypto_gcm_setauthsize(struct crypto_aead *tfm,
                  unsigned int authsize)
{
    switch (authsize) {
    case 4:
    case 8:
    case 12:
    case 13:
    case 14:
    case 15:
    case 16:
        break;
    default:
        return -EINVAL;
    }

    return 0;
}

static void crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
                  struct aead_request *req,
                  unsigned int cryptlen)
{
    struct crypto_aead *aead = crypto_aead_reqtfm(req);
    struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    struct scatterlist *dst;
    __be32 counter = cpu_to_be32(1);

    memset(pctx->auth_tag, 0, sizeof(pctx->auth_tag));
    memcpy(req->iv + 12, &counter, 4);

    sg_init_table(pctx->src, 2);
    sg_set_buf(pctx->src, pctx->auth_tag, sizeof(pctx->auth_tag));
    scatterwalk_sg_chain(pctx->src, 2, req->src);

    dst = pctx->src;
    if (req->src != req->dst) {
        sg_init_table(pctx->dst, 2);
        sg_set_buf(pctx->dst, pctx->auth_tag, sizeof(pctx->auth_tag));
        scatterwalk_sg_chain(pctx->dst, 2, req->dst);
        dst = pctx->dst;
    }

    ablkcipher_request_set_tfm(ablk_req, ctx->ctr);
    ablkcipher_request_set_crypt(ablk_req, pctx->src, dst,
                     cryptlen + sizeof(pctx->auth_tag),
                     req->iv);
}

static inline unsigned int gcm_remain(unsigned int len)
{
    len &= 0xfU;
    return len ? 16 - len : 0;
}

static void gcm_hash_len_done(struct crypto_async_request *areq, int err);
static void gcm_hash_final_done(struct crypto_async_request *areq, int err);

static int gcm_hash_update(struct aead_request *req,
               struct crypto_gcm_req_priv_ctx *pctx,
               crypto_completion_t complete,
               struct scatterlist *src,
               unsigned int len)
{
    struct ahash_request *ahreq = &pctx->u.ahreq;

    ahash_request_set_callback(ahreq, aead_request_flags(req),
                   complete, req);
    ahash_request_set_crypt(ahreq, src, NULL, len);

    return crypto_ahash_update(ahreq);
}

static int gcm_hash_remain(struct aead_request *req,
               struct crypto_gcm_req_priv_ctx *pctx,
               unsigned int remain,
               crypto_completion_t complete)
{
    struct ahash_request *ahreq = &pctx->u.ahreq;

    ahash_request_set_callback(ahreq, aead_request_flags(req),
                   complete, req);
    sg_init_one(pctx->src, gcm_zeroes, remain);
    ahash_request_set_crypt(ahreq, pctx->src, NULL, remain);

    return crypto_ahash_update(ahreq);
}

static int gcm_hash_len(struct aead_request *req,
            struct crypto_gcm_req_priv_ctx *pctx)
{
    struct ahash_request *ahreq = &pctx->u.ahreq;
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
    u128 lengths;

    lengths.a = cpu_to_be64(req->assoclen * 8);
    lengths.b = cpu_to_be64(gctx->cryptlen * 8);
    memcpy(pctx->iauth_tag, &lengths, 16);
    sg_init_one(pctx->src, pctx->iauth_tag, 16);
    ahash_request_set_callback(ahreq, aead_request_flags(req),
                   gcm_hash_len_done, req);
    ahash_request_set_crypt(ahreq, pctx->src,
                NULL, sizeof(lengths));

    return crypto_ahash_update(ahreq);
}

static int gcm_hash_final(struct aead_request *req,
              struct crypto_gcm_req_priv_ctx *pctx)
{
    struct ahash_request *ahreq = &pctx->u.ahreq;

    ahash_request_set_callback(ahreq, aead_request_flags(req),
                   gcm_hash_final_done, req);
    ahash_request_set_crypt(ahreq, NULL, pctx->iauth_tag, 0);

    return crypto_ahash_final(ahreq);
}

static void __gcm_hash_final_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;

    if (!err)
        crypto_xor(pctx->auth_tag, pctx->iauth_tag, 16);

    gctx->complete(req, err);
}

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

    __gcm_hash_final_done(req, err);
}

static void __gcm_hash_len_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

    if (!err) {
        err = gcm_hash_final(req, pctx);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
    }

    __gcm_hash_final_done(req, err);
}

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

    __gcm_hash_len_done(req, err);
}

static void __gcm_hash_crypt_remain_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

    if (!err) {
        err = gcm_hash_len(req, pctx);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
    }

    __gcm_hash_len_done(req, err);
}

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

    __gcm_hash_crypt_remain_done(req, err);
}

static void __gcm_hash_crypt_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
    unsigned int remain;

    if (!err) {
        remain = gcm_remain(gctx->cryptlen);
        BUG_ON(!remain);
        err = gcm_hash_remain(req, pctx, remain,
                      gcm_hash_crypt_remain_done);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
    }

    __gcm_hash_crypt_remain_done(req, err);
}

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

    __gcm_hash_crypt_done(req, err);
}

static void __gcm_hash_assoc_remain_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
    crypto_completion_t complete;
    unsigned int remain = 0;

    if (!err && gctx->cryptlen) {
        remain = gcm_remain(gctx->cryptlen);
        complete = remain ? gcm_hash_crypt_done :
            gcm_hash_crypt_remain_done;
        err = gcm_hash_update(req, pctx, complete,
                      gctx->src, gctx->cryptlen);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
    }

    if (remain)
        __gcm_hash_crypt_done(req, err);
    else
        __gcm_hash_crypt_remain_done(req, err);
}

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

    __gcm_hash_assoc_remain_done(req, err);
}

static void __gcm_hash_assoc_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    unsigned int remain;

    if (!err) {
        remain = gcm_remain(req->assoclen);
        BUG_ON(!remain);
        err = gcm_hash_remain(req, pctx, remain,
                      gcm_hash_assoc_remain_done);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
    }

    __gcm_hash_assoc_remain_done(req, err);
}

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

    __gcm_hash_assoc_done(req, err);
}

static void __gcm_hash_init_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    crypto_completion_t complete;
    unsigned int remain = 0;

    if (!err && req->assoclen) {
        remain = gcm_remain(req->assoclen);
        complete = remain ? gcm_hash_assoc_done :
            gcm_hash_assoc_remain_done;
        err = gcm_hash_update(req, pctx, complete,
                      req->assoc, req->assoclen);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
    }

    if (remain)
        __gcm_hash_assoc_done(req, err);
    else
        __gcm_hash_assoc_remain_done(req, err);
}

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

    __gcm_hash_init_done(req, err);
}

static int gcm_hash(struct aead_request *req,
            struct crypto_gcm_req_priv_ctx *pctx)
{
    struct ahash_request *ahreq = &pctx->u.ahreq;
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
    struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(req->base.tfm);
    unsigned int remain;
    crypto_completion_t complete;
    int err;

    ahash_request_set_tfm(ahreq, ctx->ghash);

    ahash_request_set_callback(ahreq, aead_request_flags(req),
                   gcm_hash_init_done, req);
    err = crypto_ahash_init(ahreq);
    if (err)
        return err;
    remain = gcm_remain(req->assoclen);
    complete = remain ? gcm_hash_assoc_done : gcm_hash_assoc_remain_done;
    err = gcm_hash_update(req, pctx, complete, req->assoc, req->assoclen);
    if (err)
        return err;
    if (remain) {
        err = gcm_hash_remain(req, pctx, remain,
                      gcm_hash_assoc_remain_done);
        if (err)
            return err;
    }
    remain = gcm_remain(gctx->cryptlen);
    complete = remain ? gcm_hash_crypt_done : gcm_hash_crypt_remain_done;
    err = gcm_hash_update(req, pctx, complete, gctx->src, gctx->cryptlen);
    if (err)
        return err;
    if (remain) {
        err = gcm_hash_remain(req, pctx, remain,
                      gcm_hash_crypt_remain_done);
        if (err)
            return err;
    }
    err = gcm_hash_len(req, pctx);
    if (err)
        return err;
    err = gcm_hash_final(req, pctx);
    if (err)
        return err;

    return 0;
}

static void gcm_enc_copy_hash(struct aead_request *req,
                  struct crypto_gcm_req_priv_ctx *pctx)
{
    struct crypto_aead *aead = crypto_aead_reqtfm(req);
    u8 *auth_tag = pctx->auth_tag;

    scatterwalk_map_and_copy(auth_tag, req->dst, req->cryptlen,
                 crypto_aead_authsize(aead), 1);
}

static void gcm_enc_hash_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

    if (!err)
        gcm_enc_copy_hash(req, pctx);

    aead_request_complete(req, err);
}

static void gcm_encrypt_done(struct crypto_async_request *areq, int err)
{
    struct aead_request *req = areq->data;
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

    if (!err) {
        err = gcm_hash(req, pctx);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
        else if (!err) {
            crypto_xor(pctx->auth_tag, pctx->iauth_tag, 16);
            gcm_enc_copy_hash(req, pctx);
        }
    }

    aead_request_complete(req, err);
}

static int crypto_gcm_encrypt(struct aead_request *req)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    struct ablkcipher_request *abreq = &pctx->u.abreq;
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
    int err;

    crypto_gcm_init_crypt(abreq, req, req->cryptlen);
    ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                    gcm_encrypt_done, req);

    gctx->src = req->dst;
    gctx->cryptlen = req->cryptlen;
    gctx->complete = gcm_enc_hash_done;

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

    err = gcm_hash(req, pctx);
    if (err)
        return err;

    crypto_xor(pctx->auth_tag, pctx->iauth_tag, 16);
    gcm_enc_copy_hash(req, pctx);

    return 0;
}

static int crypto_gcm_verify(struct aead_request *req,
                 struct crypto_gcm_req_priv_ctx *pctx)
{
    struct crypto_aead *aead = crypto_aead_reqtfm(req);
    u8 *auth_tag = pctx->auth_tag;
    u8 *iauth_tag = pctx->iauth_tag;
    unsigned int authsize = crypto_aead_authsize(aead);
    unsigned int cryptlen = req->cryptlen - authsize;

    crypto_xor(auth_tag, iauth_tag, 16);
    scatterwalk_map_and_copy(iauth_tag, req->src, cryptlen, authsize, 0);
    return memcmp(iauth_tag, auth_tag, authsize) ? -EBADMSG : 0;
}

static void gcm_decrypt_done(struct crypto_async_request *areq, int err)
{
    struct aead_request *req = areq->data;
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);

    if (!err)
        err = crypto_gcm_verify(req, pctx);

    aead_request_complete(req, err);
}

static void gcm_dec_hash_done(struct aead_request *req, int err)
{
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    struct ablkcipher_request *abreq = &pctx->u.abreq;
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;

    if (!err) {
        ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                        gcm_decrypt_done, req);
        crypto_gcm_init_crypt(abreq, req, gctx->cryptlen);
        err = crypto_ablkcipher_decrypt(abreq);
        if (err == -EINPROGRESS || err == -EBUSY)
            return;
        else if (!err)
            err = crypto_gcm_verify(req, pctx);
    }

    aead_request_complete(req, err);
}

static int crypto_gcm_decrypt(struct aead_request *req)
{
    struct crypto_aead *aead = crypto_aead_reqtfm(req);
    struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
    struct ablkcipher_request *abreq = &pctx->u.abreq;
    struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
    unsigned int authsize = crypto_aead_authsize(aead);
    unsigned int cryptlen = req->cryptlen;
    int err;

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

    gctx->src = req->src;
    gctx->cryptlen = cryptlen;
    gctx->complete = gcm_dec_hash_done;

    err = gcm_hash(req, pctx);
    if (err)
        return err;

    ablkcipher_request_set_callback(abreq, aead_request_flags(req),
                    gcm_decrypt_done, req);
    crypto_gcm_init_crypt(abreq, req, cryptlen);
    err = crypto_ablkcipher_decrypt(abreq);
    if (err)
        return err;

    return crypto_gcm_verify(req, pctx);
}

static int crypto_gcm_init_tfm(struct crypto_tfm *tfm)
{
    struct crypto_instance *inst = (void *)tfm->__crt_alg;
    struct gcm_instance_ctx *ictx = crypto_instance_ctx(inst);
    struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
    struct crypto_ablkcipher *ctr;
    struct crypto_ahash *ghash;
    unsigned long align;
    int err;

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

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

    ctx->ctr = ctr;
    ctx->ghash = ghash;

    align = crypto_tfm_alg_alignmask(tfm);
    align &= ~(crypto_tfm_ctx_alignment() - 1);
    tfm->crt_aead.reqsize = align +
        offsetof(struct crypto_gcm_req_priv_ctx, u) +
        max(sizeof(struct ablkcipher_request) +
            crypto_ablkcipher_reqsize(ctr),
            sizeof(struct ahash_request) +
            crypto_ahash_reqsize(ghash));

    return 0;

err_free_hash:
    crypto_free_ahash(ghash);
    return err;
}

static void crypto_gcm_exit_tfm(struct crypto_tfm *tfm)
{
    struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);

    crypto_free_ahash(ctx->ghash);
    crypto_free_ablkcipher(ctx->ctr);
}

static struct crypto_instance *crypto_gcm_alloc_common(struct rtattr **tb,
                               const char *full_name,
                               const char *ctr_name,
                               const char *ghash_name)
{
    struct crypto_attr_type *algt;
    struct crypto_instance *inst;
    struct crypto_alg *ctr;
    struct crypto_alg *ghash_alg;
    struct ahash_alg *ghash_ahash_alg;
    struct gcm_instance_ctx *ctx;
    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);

    ghash_alg = crypto_find_alg(ghash_name, &crypto_ahash_type,
                    CRYPTO_ALG_TYPE_HASH,
                    CRYPTO_ALG_TYPE_AHASH_MASK);
    err = PTR_ERR(ghash_alg);
    if (IS_ERR(ghash_alg))
        return ERR_PTR(err);

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

    ctx = crypto_instance_ctx(inst);
    ghash_ahash_alg = container_of(ghash_alg, struct ahash_alg, halg.base);
    err = crypto_init_ahash_spawn(&ctx->ghash, &ghash_ahash_alg->halg,
                      inst);
    if (err)
        goto err_free_inst;

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

    ctr = crypto_skcipher_spawn_alg(&ctx->ctr);

    /* We only support 16-byte blocks. */
    if (ctr->cra_ablkcipher.ivsize != 16)
        goto out_put_ctr;

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

    err = -ENAMETOOLONG;
    if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
             "gcm_base(%s,%s)", ctr->cra_driver_name,
             ghash_alg->cra_driver_name) >=
        CRYPTO_MAX_ALG_NAME)
        goto out_put_ctr;

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

    inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
    inst->alg.cra_flags |= ctr->cra_flags & CRYPTO_ALG_ASYNC;
    inst->alg.cra_priority = ctr->cra_priority;
    inst->alg.cra_blocksize = 1;
    inst->alg.cra_alignmask = ctr->cra_alignmask | (__alignof__(u64) - 1);
    inst->alg.cra_type = &crypto_aead_type;
    inst->alg.cra_aead.ivsize = 16;
    inst->alg.cra_aead.maxauthsize = 16;
    inst->alg.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
    inst->alg.cra_init = crypto_gcm_init_tfm;
    inst->alg.cra_exit = crypto_gcm_exit_tfm;
    inst->alg.cra_aead.setkey = crypto_gcm_setkey;
    inst->alg.cra_aead.setauthsize = crypto_gcm_setauthsize;
    inst->alg.cra_aead.encrypt = crypto_gcm_encrypt;
    inst->alg.cra_aead.decrypt = crypto_gcm_decrypt;

out:
    crypto_mod_put(ghash_alg);
    return inst;

out_put_ctr:
    crypto_drop_skcipher(&ctx->ctr);
err_drop_ghash:
    crypto_drop_ahash(&ctx->ghash);
err_free_inst:
    kfree(inst);
out_put_ghash:
    inst = ERR_PTR(err);
    goto out;
}

static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
{
    int err;
    const char *cipher_name;
    char ctr_name[CRYPTO_MAX_ALG_NAME];
    char full_name[CRYPTO_MAX_ALG_NAME];

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

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

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

    return crypto_gcm_alloc_common(tb, full_name, ctr_name, "ghash");
}

static void crypto_gcm_free(struct crypto_instance *inst)
{
    struct gcm_instance_ctx *ctx = crypto_instance_ctx(inst);

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

static struct crypto_template crypto_gcm_tmpl = {
    .name = "gcm",
    .alloc = crypto_gcm_alloc,
    .free = crypto_gcm_free,
    .module = THIS_MODULE,
};

static struct crypto_instance *crypto_gcm_base_alloc(struct rtattr **tb)
{
    int err;
    const char *ctr_name;
    const char *ghash_name;
    char full_name[CRYPTO_MAX_ALG_NAME];

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

    ghash_name = crypto_attr_alg_name(tb[2]);
    err = PTR_ERR(ghash_name);
    if (IS_ERR(ghash_name))
        return ERR_PTR(err);

    if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm_base(%s,%s)",
             ctr_name, ghash_name) >= CRYPTO_MAX_ALG_NAME)
        return ERR_PTR(-ENAMETOOLONG);

    return crypto_gcm_alloc_common(tb, full_name, ctr_name, ghash_name);
}

static struct crypto_template crypto_gcm_base_tmpl = {
    .name = "gcm_base",
    .alloc = crypto_gcm_base_alloc,
    .free = crypto_gcm_free,
    .module = THIS_MODULE,
};

static int crypto_rfc4106_setkey(struct crypto_aead *parent, const u8 *key,
                 unsigned int keylen)
{
    struct crypto_rfc4106_ctx *ctx = crypto_aead_ctx(parent);
    struct crypto_aead *child = ctx->child;
    int err;

    if (keylen < 4)
        return -EINVAL;

    keylen -= 4;
    memcpy(ctx->nonce, key + keylen, 4);

    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_rfc4106_setauthsize(struct crypto_aead *parent,
                      unsigned int authsize)
{
    struct crypto_rfc4106_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_rfc4106_crypt(struct aead_request *req)
{
    struct aead_request *subreq = aead_request_ctx(req);
    struct crypto_aead *aead = crypto_aead_reqtfm(req);
    struct crypto_rfc4106_ctx *ctx = crypto_aead_ctx(aead);
    struct crypto_aead *child = ctx->child;
    u8 *iv = PTR_ALIGN((u8 *)(subreq + 1) + crypto_aead_reqsize(child),
               crypto_aead_alignmask(child) + 1);

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

    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, req->src, req->dst, req->cryptlen, iv);
    aead_request_set_assoc(subreq, req->assoc, req->assoclen);

    return subreq;
}

static int crypto_rfc4106_encrypt(struct aead_request *req)
{
    req = crypto_rfc4106_crypt(req);

    return crypto_aead_encrypt(req);
}

static int crypto_rfc4106_decrypt(struct aead_request *req)
{
    req = crypto_rfc4106_crypt(req);

    return crypto_aead_decrypt(req);
}

static int crypto_rfc4106_init_tfm(struct crypto_tfm *tfm)
{
    struct crypto_instance *inst = (void *)tfm->__crt_alg;
    struct crypto_aead_spawn *spawn = crypto_instance_ctx(inst);
    struct crypto_rfc4106_ctx *ctx = crypto_tfm_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);
    tfm->crt_aead.reqsize = sizeof(struct aead_request) +
                ALIGN(crypto_aead_reqsize(aead),
                      crypto_tfm_ctx_alignment()) +
                align + 16;

    return 0;
}

static void crypto_rfc4106_exit_tfm(struct crypto_tfm *tfm)
{
    struct crypto_rfc4106_ctx *ctx = crypto_tfm_ctx(tfm);

    crypto_free_aead(ctx->child);
}

static struct crypto_instance *crypto_rfc4106_alloc(struct rtattr **tb)
{
    struct crypto_attr_type *algt;
    struct crypto_instance *inst;
    struct crypto_aead_spawn *spawn;
    struct crypto_alg *alg;
    const char *ccm_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);

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

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

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

    alg = crypto_aead_spawn_alg(spawn);

    err = -EINVAL;

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

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

    err = -ENAMETOOLONG;
    if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
             "rfc4106(%s)", alg->cra_name) >= CRYPTO_MAX_ALG_NAME ||
        snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
             "rfc4106(%s)", alg->cra_driver_name) >=
        CRYPTO_MAX_ALG_NAME)
        goto out_drop_alg;

    inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
    inst->alg.cra_flags |= alg->cra_flags & CRYPTO_ALG_ASYNC;
    inst->alg.cra_priority = alg->cra_priority;
    inst->alg.cra_blocksize = 1;
    inst->alg.cra_alignmask = alg->cra_alignmask;
    inst->alg.cra_type = &crypto_nivaead_type;

    inst->alg.cra_aead.ivsize = 8;
    inst->alg.cra_aead.maxauthsize = 16;

    inst->alg.cra_ctxsize = sizeof(struct crypto_rfc4106_ctx);

    inst->alg.cra_init = crypto_rfc4106_init_tfm;
    inst->alg.cra_exit = crypto_rfc4106_exit_tfm;

    inst->alg.cra_aead.setkey = crypto_rfc4106_setkey;
    inst->alg.cra_aead.setauthsize = crypto_rfc4106_setauthsize;
    inst->alg.cra_aead.encrypt = crypto_rfc4106_encrypt;
    inst->alg.cra_aead.decrypt = crypto_rfc4106_decrypt;

    inst->alg.cra_aead.geniv = "seqiv";

out:
    return inst;

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

static void crypto_rfc4106_free(struct crypto_instance *inst)
{
    crypto_drop_spawn(crypto_instance_ctx(inst));
    kfree(inst);
}

static struct crypto_template crypto_rfc4106_tmpl = {
    .name = "rfc4106",
    .alloc = crypto_rfc4106_alloc,
    .free = crypto_rfc4106_free,
    .module = THIS_MODULE,
};

static inline struct crypto_rfc4543_req_ctx *crypto_rfc4543_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 crypto_rfc4543_setkey(struct crypto_aead *parent, const u8 *key,
                 unsigned int keylen)
{
    struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(parent);
    struct crypto_aead *child = ctx->child;
    int err;

    if (keylen < 4)
        return -EINVAL;

    keylen -= 4;
    memcpy(ctx->nonce, key + keylen, 4);

    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_rfc4543_setauthsize(struct crypto_aead *parent,
                      unsigned int authsize)
{
    struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(parent);

    if (authsize != 16)
        return -EINVAL;

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

static struct aead_request *crypto_rfc4543_crypt(struct aead_request *req,
                         int enc)
{
    struct crypto_aead *aead = crypto_aead_reqtfm(req);
    struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(aead);
    struct crypto_rfc4543_req_ctx *rctx = crypto_rfc4543_reqctx(req);
    struct aead_request *subreq = &rctx->subreq;
    struct scatterlist *dst = req->dst;
    struct scatterlist *cipher = rctx->cipher;
    struct scatterlist *payload = rctx->payload;
    struct scatterlist *assoc = rctx->assoc;
    unsigned int authsize = crypto_aead_authsize(aead);
    unsigned int assoclen = req->assoclen;
    struct page *dstp;
    u8 *vdst;
    u8 *iv = PTR_ALIGN((u8 *)(rctx + 1) + crypto_aead_reqsize(ctx->child),
               crypto_aead_alignmask(ctx->child) + 1);

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

    /* construct cipher/plaintext */
    if (enc)
        memset(rctx->auth_tag, 0, authsize);
    else
        scatterwalk_map_and_copy(rctx->auth_tag, dst,
                     req->cryptlen - authsize,
                     authsize, 0);

    sg_init_one(cipher, rctx->auth_tag, authsize);

    /* construct the aad */
    dstp = sg_page(dst);
    vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;

    sg_init_table(payload, 2);
    sg_set_buf(payload, req->iv, 8);
    scatterwalk_crypto_chain(payload, dst, vdst == req->iv + 8, 2);
    assoclen += 8 + req->cryptlen - (enc ? 0 : authsize);

    sg_init_table(assoc, 2);
    sg_set_page(assoc, sg_page(req->assoc), req->assoc->length,
            req->assoc->offset);
    scatterwalk_crypto_chain(assoc, payload, 0, 2);

    aead_request_set_tfm(subreq, ctx->child);
    aead_request_set_callback(subreq, req->base.flags, req->base.complete,
                  req->base.data);
    aead_request_set_crypt(subreq, cipher, cipher, enc ? 0 : authsize, iv);
    aead_request_set_assoc(subreq, assoc, assoclen);

    return subreq;
}

static int crypto_rfc4543_encrypt(struct aead_request *req)
{
    struct crypto_aead *aead = crypto_aead_reqtfm(req);
    struct crypto_rfc4543_req_ctx *rctx = crypto_rfc4543_reqctx(req);
    struct aead_request *subreq;
    int err;

    subreq = crypto_rfc4543_crypt(req, 1);
    err = crypto_aead_encrypt(subreq);
    if (err)
        return err;

    scatterwalk_map_and_copy(rctx->auth_tag, req->dst, req->cryptlen,
                 crypto_aead_authsize(aead), 1);

    return 0;
}

static int crypto_rfc4543_decrypt(struct aead_request *req)
{
    req = crypto_rfc4543_crypt(req, 0);

    return crypto_aead_decrypt(req);
}

static int crypto_rfc4543_init_tfm(struct crypto_tfm *tfm)
{
    struct crypto_instance *inst = (void *)tfm->__crt_alg;
    struct crypto_aead_spawn *spawn = crypto_instance_ctx(inst);
    struct crypto_rfc4543_ctx *ctx = crypto_tfm_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);
    tfm->crt_aead.reqsize = sizeof(struct crypto_rfc4543_req_ctx) +
                ALIGN(crypto_aead_reqsize(aead),
                      crypto_tfm_ctx_alignment()) +
                align + 16;

    return 0;
}

static void crypto_rfc4543_exit_tfm(struct crypto_tfm *tfm)
{
    struct crypto_rfc4543_ctx *ctx = crypto_tfm_ctx(tfm);

    crypto_free_aead(ctx->child);
}

static struct crypto_instance *crypto_rfc4543_alloc(struct rtattr **tb)
{
    struct crypto_attr_type *algt;
    struct crypto_instance *inst;
    struct crypto_aead_spawn *spawn;
    struct crypto_alg *alg;
    const char *ccm_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);

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

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

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

    alg = crypto_aead_spawn_alg(spawn);

    err = -EINVAL;

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

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

    err = -ENAMETOOLONG;
    if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
             "rfc4543(%s)", alg->cra_name) >= CRYPTO_MAX_ALG_NAME ||
        snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
             "rfc4543(%s)", alg->cra_driver_name) >=
        CRYPTO_MAX_ALG_NAME)
        goto out_drop_alg;

    inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
    inst->alg.cra_flags |= alg->cra_flags & CRYPTO_ALG_ASYNC;
    inst->alg.cra_priority = alg->cra_priority;
    inst->alg.cra_blocksize = 1;
    inst->alg.cra_alignmask = alg->cra_alignmask;
    inst->alg.cra_type = &crypto_nivaead_type;

    inst->alg.cra_aead.ivsize = 8;
    inst->alg.cra_aead.maxauthsize = 16;

    inst->alg.cra_ctxsize = sizeof(struct crypto_rfc4543_ctx);

    inst->alg.cra_init = crypto_rfc4543_init_tfm;
    inst->alg.cra_exit = crypto_rfc4543_exit_tfm;

    inst->alg.cra_aead.setkey = crypto_rfc4543_setkey;
    inst->alg.cra_aead.setauthsize = crypto_rfc4543_setauthsize;
    inst->alg.cra_aead.encrypt = crypto_rfc4543_encrypt;
    inst->alg.cra_aead.decrypt = crypto_rfc4543_decrypt;

    inst->alg.cra_aead.geniv = "seqiv";

out:
    return inst;

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

static void crypto_rfc4543_free(struct crypto_instance *inst)
{
    crypto_drop_spawn(crypto_instance_ctx(inst));
    kfree(inst);
}

static struct crypto_template crypto_rfc4543_tmpl = {
    .name = "rfc4543",
    .alloc = crypto_rfc4543_alloc,
    .free = crypto_rfc4543_free,
    .module = THIS_MODULE,
};

static int __init crypto_gcm_module_init(void)
{
    int err;

    gcm_zeroes = kzalloc(16, GFP_KERNEL);
    if (!gcm_zeroes)
        return -ENOMEM;

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

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

    err = crypto_register_template(&crypto_rfc4106_tmpl);
    if (err)
        goto out_undo_gcm;

    err = crypto_register_template(&crypto_rfc4543_tmpl);
    if (err)
        goto out_undo_rfc4106;

    return 0;

out_undo_rfc4106:
    crypto_unregister_template(&crypto_rfc4106_tmpl);
out_undo_gcm:
    crypto_unregister_template(&crypto_gcm_tmpl);
out_undo_base:
    crypto_unregister_template(&crypto_gcm_base_tmpl);
out:
    kfree(gcm_zeroes);
    return err;
}

static void __exit crypto_gcm_module_exit(void)
{
    kfree(gcm_zeroes);
    crypto_unregister_template(&crypto_rfc4543_tmpl);
    crypto_unregister_template(&crypto_rfc4106_tmpl);
    crypto_unregister_template(&crypto_gcm_tmpl);
    crypto_unregister_template(&crypto_gcm_base_tmpl);
}

module_init(crypto_gcm_module_init);
module_exit(crypto_gcm_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Galois/Counter Mode");
MODULE_AUTHOR("Mikko Herranen <[email protected]>");
MODULE_ALIAS("gcm_base");
MODULE_ALIAS("rfc4106");
MODULE_ALIAS("rfc4543");