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[mirror_ubuntu-zesty-kernel.git] / crypto / gcm.c

/*
 * GCM: Galois/Counter Mode.
 *
 * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
 *
 * 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/null.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_skcipher *ctr;
        struct crypto_ahash *ghash;
};

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

struct crypto_rfc4106_req_ctx {
        struct scatterlist src[3];
        struct scatterlist dst[3];
        struct aead_request subreq;
};

struct crypto_rfc4543_instance_ctx {
        struct crypto_aead_spawn aead;
};

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

struct crypto_rfc4543_req_ctx {
        struct aead_request subreq;
};

struct crypto_gcm_ghash_ctx {
        unsigned int cryptlen;
        struct scatterlist *src;
        int (*complete)(struct aead_request *req, u32 flags);
};

struct crypto_gcm_req_priv_ctx {
        u8 iv[16];
        u8 auth_tag[16];
        u8 iauth_tag[16];
        struct scatterlist src[3];
        struct scatterlist dst[3];
        struct scatterlist sg;
        struct crypto_gcm_ghash_ctx ghash_ctx;
        union {
                struct ahash_request ahreq;
                struct skcipher_request skreq;
        } u;
};

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

static struct {
        u8 buf[16];
        struct scatterlist sg;
} *gcm_zeroes;

static int crypto_rfc4543_copy_src_to_dst(struct aead_request *req, bool enc);

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_skcipher *ctr = ctx->ctr;
        struct {
                be128 hash;
                u8 iv[16];

                struct crypto_gcm_setkey_result result;

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

        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)
                return err;

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

        init_completion(&data->result.completion);
        sg_init_one(data->sg, &data->hash, sizeof(data->hash));
        skcipher_request_set_tfm(&data->req, ctr);
        skcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
                                                  CRYPTO_TFM_REQ_MAY_BACKLOG,
                                      crypto_gcm_setkey_done,
                                      &data->result);
        skcipher_request_set_crypt(&data->req, data->sg, data->sg,
                                   sizeof(data->hash), data->iv);

        err = crypto_skcipher_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:
        kzfree(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_common(struct aead_request *req)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        __be32 counter = cpu_to_be32(1);
        struct scatterlist *sg;

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

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

static void crypto_gcm_init_crypt(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 skcipher_request *skreq = &pctx->u.skreq;
        struct scatterlist *dst;

        dst = req->src == req->dst ? pctx->src : pctx->dst;

        skcipher_request_set_tfm(skreq, ctx->ctr);
        skcipher_request_set_crypt(skreq, pctx->src, dst,
                                     cryptlen + sizeof(pctx->auth_tag),
                                     pctx->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 int gcm_hash_update(struct aead_request *req,
                           crypto_completion_t compl,
                           struct scatterlist *src,
                           unsigned int len, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct ahash_request *ahreq = &pctx->u.ahreq;

        ahash_request_set_callback(ahreq, flags, compl, req);
        ahash_request_set_crypt(ahreq, src, NULL, len);

        return crypto_ahash_update(ahreq);
}

static int gcm_hash_remain(struct aead_request *req,
                           unsigned int remain,
                           crypto_completion_t compl, u32 flags)
{
        return gcm_hash_update(req, compl, &gcm_zeroes->sg, remain, flags);
}

static int gcm_hash_len(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        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->sg, pctx->iauth_tag, 16);
        ahash_request_set_callback(ahreq, flags, gcm_hash_len_done, req);
        ahash_request_set_crypt(ahreq, &pctx->sg,
                                pctx->iauth_tag, sizeof(lengths));

        return crypto_ahash_finup(ahreq);
}

static int gcm_hash_len_continue(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;

        return gctx->complete(req, flags);
}

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

        if (err)
                goto out;

        err = gcm_hash_len_continue(req, 0);
        if (err == -EINPROGRESS)
                return;

out:
        aead_request_complete(req, err);
}

static int gcm_hash_crypt_remain_continue(struct aead_request *req, u32 flags)
{
        return gcm_hash_len(req, flags) ?:
               gcm_hash_len_continue(req, flags);
}

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

        if (err)
                goto out;

        err = gcm_hash_crypt_remain_continue(req, 0);
        if (err == -EINPROGRESS)
                return;

out:
        aead_request_complete(req, err);
}

static int gcm_hash_crypt_continue(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
        unsigned int remain;

        remain = gcm_remain(gctx->cryptlen);
        if (remain)
                return gcm_hash_remain(req, remain,
                                       gcm_hash_crypt_remain_done, flags) ?:
                       gcm_hash_crypt_remain_continue(req, flags);

        return gcm_hash_crypt_remain_continue(req, flags);
}

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

        if (err)
                goto out;

        err = gcm_hash_crypt_continue(req, 0);
        if (err == -EINPROGRESS)
                return;

out:
        aead_request_complete(req, err);
}

static int gcm_hash_assoc_remain_continue(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;

        if (gctx->cryptlen)
                return gcm_hash_update(req, gcm_hash_crypt_done,
                                       gctx->src, gctx->cryptlen, flags) ?:
                       gcm_hash_crypt_continue(req, flags);

        return gcm_hash_crypt_remain_continue(req, flags);
}

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

        if (err)
                goto out;

        err = gcm_hash_assoc_remain_continue(req, 0);
        if (err == -EINPROGRESS)
                return;

out:
        aead_request_complete(req, err);
}

static int gcm_hash_assoc_continue(struct aead_request *req, u32 flags)
{
        unsigned int remain;

        remain = gcm_remain(req->assoclen);
        if (remain)
                return gcm_hash_remain(req, remain,
                                       gcm_hash_assoc_remain_done, flags) ?:
                       gcm_hash_assoc_remain_continue(req, flags);

        return gcm_hash_assoc_remain_continue(req, flags);
}

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

        if (err)
                goto out;

        err = gcm_hash_assoc_continue(req, 0);
        if (err == -EINPROGRESS)
                return;

out:
        aead_request_complete(req, err);
}

static int gcm_hash_init_continue(struct aead_request *req, u32 flags)
{
        if (req->assoclen)
                return gcm_hash_update(req, gcm_hash_assoc_done,
                                       req->src, req->assoclen, flags) ?:
                       gcm_hash_assoc_continue(req, flags);

        return gcm_hash_assoc_remain_continue(req, flags);
}

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

        if (err)
                goto out;

        err = gcm_hash_init_continue(req, 0);
        if (err == -EINPROGRESS)
                return;

out:
        aead_request_complete(req, err);
}

static int gcm_hash(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct ahash_request *ahreq = &pctx->u.ahreq;
        struct crypto_gcm_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));

        ahash_request_set_tfm(ahreq, ctx->ghash);

        ahash_request_set_callback(ahreq, flags, gcm_hash_init_done, req);
        return crypto_ahash_init(ahreq) ?:
               gcm_hash_init_continue(req, flags);
}

static int gcm_enc_copy_hash(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        u8 *auth_tag = pctx->auth_tag;

        crypto_xor(auth_tag, pctx->iauth_tag, 16);
        scatterwalk_map_and_copy(auth_tag, req->dst,
                                 req->assoclen + req->cryptlen,
                                 crypto_aead_authsize(aead), 1);
        return 0;
}

static int gcm_encrypt_continue(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;

        gctx->src = sg_next(req->src == req->dst ? pctx->src : pctx->dst);
        gctx->cryptlen = req->cryptlen;
        gctx->complete = gcm_enc_copy_hash;

        return gcm_hash(req, flags);
}

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

        if (err)
                goto out;

        err = gcm_encrypt_continue(req, 0);
        if (err == -EINPROGRESS)
                return;

out:
        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 skcipher_request *skreq = &pctx->u.skreq;
        u32 flags = aead_request_flags(req);

        crypto_gcm_init_common(req);
        crypto_gcm_init_crypt(req, req->cryptlen);
        skcipher_request_set_callback(skreq, flags, gcm_encrypt_done, req);

        return crypto_skcipher_encrypt(skreq) ?:
               gcm_encrypt_continue(req, flags);
}

static int crypto_gcm_verify(struct aead_request *req)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        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,
                                 req->assoclen + cryptlen, authsize, 0);
        return crypto_memneq(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;

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

        aead_request_complete(req, err);
}

static int gcm_dec_hash_continue(struct aead_request *req, u32 flags)
{
        struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
        struct skcipher_request *skreq = &pctx->u.skreq;
        struct crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;

        crypto_gcm_init_crypt(req, gctx->cryptlen);
        skcipher_request_set_callback(skreq, flags, gcm_decrypt_done, req);
        return crypto_skcipher_decrypt(skreq) ?: crypto_gcm_verify(req);
}

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 crypto_gcm_ghash_ctx *gctx = &pctx->ghash_ctx;
        unsigned int authsize = crypto_aead_authsize(aead);
        unsigned int cryptlen = req->cryptlen;
        u32 flags = aead_request_flags(req);

        cryptlen -= authsize;

        crypto_gcm_init_common(req);

        gctx->src = sg_next(pctx->src);
        gctx->cryptlen = cryptlen;
        gctx->complete = gcm_dec_hash_continue;

        return gcm_hash(req, flags);
}

static int crypto_gcm_init_tfm(struct crypto_aead *tfm)
{
        struct aead_instance *inst = aead_alg_instance(tfm);
        struct gcm_instance_ctx *ictx = aead_instance_ctx(inst);
        struct crypto_gcm_ctx *ctx = crypto_aead_ctx(tfm);
        struct crypto_skcipher *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_aead_alignmask(tfm);
        align &= ~(crypto_tfm_ctx_alignment() - 1);
        crypto_aead_set_reqsize(tfm,
                align + offsetof(struct crypto_gcm_req_priv_ctx, u) +
                max(sizeof(struct skcipher_request) +
                    crypto_skcipher_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_aead *tfm)
{
        struct crypto_gcm_ctx *ctx = crypto_aead_ctx(tfm);

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

static void crypto_gcm_free(struct aead_instance *inst)
{
        struct gcm_instance_ctx *ctx = aead_instance_ctx(inst);

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

static int crypto_gcm_create_common(struct crypto_template *tmpl,
                                    struct rtattr **tb,
                                    const char *full_name,
                                    const char *ctr_name,
                                    const char *ghash_name)
{
        struct crypto_attr_type *algt;
        struct aead_instance *inst;
        struct skcipher_alg *ctr;
        struct crypto_alg *ghash_alg;
        struct hash_alg_common *ghash;
        struct gcm_instance_ctx *ctx;
        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;

        ghash_alg = crypto_find_alg(ghash_name, &crypto_ahash_type,
                                    CRYPTO_ALG_TYPE_HASH,
                                    CRYPTO_ALG_TYPE_AHASH_MASK |
                                    crypto_requires_sync(algt->type,
                                                         algt->mask));
        if (IS_ERR(ghash_alg))
                return PTR_ERR(ghash_alg);

        ghash = __crypto_hash_alg_common(ghash_alg);

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

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

        err = -EINVAL;
        if (ghash->digestsize != 16)
                goto err_drop_ghash;

        crypto_set_skcipher_spawn(&ctx->ctr, aead_crypto_instance(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_spawn_skcipher_alg(&ctx->ctr);

        /* We only support 16-byte blocks. */
        err = -EINVAL;
        if (crypto_skcipher_alg_ivsize(ctr) != 16)
                goto out_put_ctr;

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

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

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

        inst->alg.base.cra_flags = (ghash->base.cra_flags |
                                    ctr->base.cra_flags) & CRYPTO_ALG_ASYNC;
        inst->alg.base.cra_priority = (ghash->base.cra_priority +
                                       ctr->base.cra_priority) / 2;
        inst->alg.base.cra_blocksize = 1;
        inst->alg.base.cra_alignmask = ghash->base.cra_alignmask |
                                       ctr->base.cra_alignmask;
        inst->alg.base.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
        inst->alg.ivsize = 12;
        inst->alg.chunksize = crypto_skcipher_alg_chunksize(ctr);
        inst->alg.maxauthsize = 16;
        inst->alg.init = crypto_gcm_init_tfm;
        inst->alg.exit = crypto_gcm_exit_tfm;
        inst->alg.setkey = crypto_gcm_setkey;
        inst->alg.setauthsize = crypto_gcm_setauthsize;
        inst->alg.encrypt = crypto_gcm_encrypt;
        inst->alg.decrypt = crypto_gcm_decrypt;

        inst->free = crypto_gcm_free;

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

out_put_ghash:
        crypto_mod_put(ghash_alg);
        return err;

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

static int crypto_gcm_create(struct crypto_template *tmpl, struct rtattr **tb)
{
        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]);
        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(full_name, CRYPTO_MAX_ALG_NAME, "gcm(%s)", cipher_name) >=
            CRYPTO_MAX_ALG_NAME)
                return -ENAMETOOLONG;

        return crypto_gcm_create_common(tmpl, tb, full_name,
                                        ctr_name, "ghash");
}

static struct crypto_template crypto_gcm_tmpl = {
        .name = "gcm",
        .create = crypto_gcm_create,
        .module = THIS_MODULE,
};

static int crypto_gcm_base_create(struct crypto_template *tmpl,
                                  struct rtattr **tb)
{
        const char *ctr_name;
        const char *ghash_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);

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

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

        return crypto_gcm_create_common(tmpl, tb, full_name,
                                        ctr_name, ghash_name);
}

static struct crypto_template crypto_gcm_base_tmpl = {
        .name = "gcm_base",
        .create = crypto_gcm_base_create,
        .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 crypto_rfc4106_req_ctx *rctx = aead_request_ctx(req);
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_rfc4106_ctx *ctx = crypto_aead_ctx(aead);
        struct aead_request *subreq = &rctx->subreq;
        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);

        scatterwalk_map_and_copy(iv + 12, req->src, 0, req->assoclen - 8, 0);

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

        sg_init_table(rctx->src, 3);
        sg_set_buf(rctx->src, iv + 12, 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 + 12, 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_rfc4106_encrypt(struct aead_request *req)
{
        if (req->assoclen != 16 && req->assoclen != 20)
                return -EINVAL;

        req = crypto_rfc4106_crypt(req);

        return crypto_aead_encrypt(req);
}

static int crypto_rfc4106_decrypt(struct aead_request *req)
{
        if (req->assoclen != 16 && req->assoclen != 20)
                return -EINVAL;

        req = crypto_rfc4106_crypt(req);

        return crypto_aead_decrypt(req);
}

static int crypto_rfc4106_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_rfc4106_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_rfc4106_req_ctx) +
                ALIGN(crypto_aead_reqsize(aead), crypto_tfm_ctx_alignment()) +
                align + 24);

        return 0;
}

static void crypto_rfc4106_exit_tfm(struct crypto_aead *tfm)
{
        struct crypto_rfc4106_ctx *ctx = crypto_aead_ctx(tfm);

        crypto_free_aead(ctx->child);
}

static void crypto_rfc4106_free(struct aead_instance *inst)
{
        crypto_drop_aead(aead_instance_ctx(inst));
        kfree(inst);
}

static int crypto_rfc4106_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;

        /* Underlying IV size must be 12. */
        if (crypto_aead_alg_ivsize(alg) != 12)
                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,
                     "rfc4106(%s)", alg->base.cra_name) >=
            CRYPTO_MAX_ALG_NAME ||
            snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
                     "rfc4106(%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.base.cra_ctxsize = sizeof(struct crypto_rfc4106_ctx);

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

        inst->alg.init = crypto_rfc4106_init_tfm;
        inst->alg.exit = crypto_rfc4106_exit_tfm;

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

        inst->free = crypto_rfc4106_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_rfc4106_tmpl = {
        .name = "rfc4106",
        .create = crypto_rfc4106_create,
        .module = THIS_MODULE,
};

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 int crypto_rfc4543_crypt(struct aead_request *req, bool enc)
{
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(aead);
        struct crypto_rfc4543_req_ctx *rctx = aead_request_ctx(req);
        struct aead_request *subreq = &rctx->subreq;
        unsigned int authsize = crypto_aead_authsize(aead);
        u8 *iv = PTR_ALIGN((u8 *)(rctx + 1) + crypto_aead_reqsize(ctx->child),
                           crypto_aead_alignmask(ctx->child) + 1);
        int err;

        if (req->src != req->dst) {
                err = crypto_rfc4543_copy_src_to_dst(req, enc);
                if (err)
                        return err;
        }

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

        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, req->src, req->dst,
                               enc ? 0 : authsize, iv);
        aead_request_set_ad(subreq, req->assoclen + req->cryptlen -
                                    subreq->cryptlen);

        return enc ? crypto_aead_encrypt(subreq) : crypto_aead_decrypt(subreq);
}

static int crypto_rfc4543_copy_src_to_dst(struct aead_request *req, bool enc)
{
        struct crypto_aead *aead = crypto_aead_reqtfm(req);
        struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(aead);
        unsigned int authsize = crypto_aead_authsize(aead);
        unsigned int nbytes = req->assoclen + req->cryptlen -
                              (enc ? 0 : authsize);
        SKCIPHER_REQUEST_ON_STACK(nreq, ctx->null);

        skcipher_request_set_tfm(nreq, ctx->null);
        skcipher_request_set_callback(nreq, req->base.flags, NULL, NULL);
        skcipher_request_set_crypt(nreq, req->src, req->dst, nbytes, NULL);

        return crypto_skcipher_encrypt(nreq);
}

static int crypto_rfc4543_encrypt(struct aead_request *req)
{
        return crypto_rfc4543_crypt(req, true);
}

static int crypto_rfc4543_decrypt(struct aead_request *req)
{
        return crypto_rfc4543_crypt(req, false);
}

static int crypto_rfc4543_init_tfm(struct crypto_aead *tfm)
{
        struct aead_instance *inst = aead_alg_instance(tfm);
        struct crypto_rfc4543_instance_ctx *ictx = aead_instance_ctx(inst);
        struct crypto_aead_spawn *spawn = &ictx->aead;
        struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(tfm);
        struct crypto_aead *aead;
        struct crypto_skcipher *null;
        unsigned long align;
        int err = 0;

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

        null = crypto_get_default_null_skcipher2();
        err = PTR_ERR(null);
        if (IS_ERR(null))
                goto err_free_aead;

        ctx->child = aead;
        ctx->null = null;

        align = crypto_aead_alignmask(aead);
        align &= ~(crypto_tfm_ctx_alignment() - 1);
        crypto_aead_set_reqsize(
                tfm,
                sizeof(struct crypto_rfc4543_req_ctx) +
                ALIGN(crypto_aead_reqsize(aead), crypto_tfm_ctx_alignment()) +
                align + 12);

        return 0;

err_free_aead:
        crypto_free_aead(aead);
        return err;
}

static void crypto_rfc4543_exit_tfm(struct crypto_aead *tfm)
{
        struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(tfm);

        crypto_free_aead(ctx->child);
        crypto_put_default_null_skcipher2();
}

static void crypto_rfc4543_free(struct aead_instance *inst)
{
        struct crypto_rfc4543_instance_ctx *ctx = aead_instance_ctx(inst);

        crypto_drop_aead(&ctx->aead);

        kfree(inst);
}

static int crypto_rfc4543_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;
        struct crypto_rfc4543_instance_ctx *ctx;
        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(*ctx), GFP_KERNEL);
        if (!inst)
                return -ENOMEM;

        ctx = aead_instance_ctx(inst);
        spawn = &ctx->aead;
        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;

        /* Underlying IV size must be 12. */
        if (crypto_aead_alg_ivsize(alg) != 12)
                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,
                     "rfc4543(%s)", alg->base.cra_name) >=
            CRYPTO_MAX_ALG_NAME ||
            snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
                     "rfc4543(%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.base.cra_ctxsize = sizeof(struct crypto_rfc4543_ctx);

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

        inst->alg.init = crypto_rfc4543_init_tfm;
        inst->alg.exit = crypto_rfc4543_exit_tfm;

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

        inst->free = crypto_rfc4543_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_rfc4543_tmpl = {
        .name = "rfc4543",
        .create = crypto_rfc4543_create,
        .module = THIS_MODULE,
};

static int __init crypto_gcm_module_init(void)
{
        int err;

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

        sg_init_one(&gcm_zeroes->sg, gcm_zeroes->buf, sizeof(gcm_zeroes->buf));

        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 <mh1@iki.fi>");
MODULE_ALIAS_CRYPTO("gcm_base");
MODULE_ALIAS_CRYPTO("rfc4106");
MODULE_ALIAS_CRYPTO("rfc4543");
MODULE_ALIAS_CRYPTO("gcm");