// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Authenc: Simple AEAD wrapper for IPsec
 *
 * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
 */

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

struct authenc_instance_ctx {
        struct crypto_ahash_spawn auth;
        struct crypto_skcipher_spawn enc;
        unsigned int reqoff;
};

struct crypto_authenc_ctx {
        struct crypto_ahash *auth;
        struct crypto_skcipher *enc;
};

struct authenc_request_ctx {
        struct scatterlist src[2];
        struct scatterlist dst[2];
        char tail[];
};

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

int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
                               unsigned int keylen)
{
        struct rtattr *rta = (struct rtattr *)key;
        struct crypto_authenc_key_param *param;

        if (!RTA_OK(rta, keylen))
                return -EINVAL;
        if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
                return -EINVAL;

        /*
         * RTA_OK() didn't align the rtattr's payload when validating that it
         * fits in the buffer.  Yet, the keys should start on the next 4-byte
         * aligned boundary.  To avoid confusion, require that the rtattr
         * payload be exactly the param struct, which has a 4-byte aligned size.
         */
        if (RTA_PAYLOAD(rta) != sizeof(*param))
                return -EINVAL;
        BUILD_BUG_ON(sizeof(*param) % RTA_ALIGNTO);

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

        key += rta->rta_len;
        keylen -= rta->rta_len;

        if (keylen < keys->enckeylen)
                return -EINVAL;

        keys->authkeylen = keylen - keys->enckeylen;
        keys->authkey = key;
        keys->enckey = key + keys->authkeylen;

        return 0;
}
EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);

static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
                                 unsigned int keylen)
{
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
        struct crypto_ahash *auth = ctx->auth;
        struct crypto_skcipher *enc = ctx->enc;
        struct crypto_authenc_keys keys;
        int err = -EINVAL;

        if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
                goto out;

        crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
        crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
                                    CRYPTO_TFM_REQ_MASK);
        err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
        if (err)
                goto out;

        crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
        crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
                                       CRYPTO_TFM_REQ_MASK);
        err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
out:
        memzero_explicit(&keys, sizeof(keys));
        return err;
}

static void authenc_geniv_ahash_finish(struct aead_request *req)
{
        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
        struct aead_instance *inst = aead_alg_instance(authenc);
        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);

        scatterwalk_map_and_copy(ahreq->result, req->dst,
                                 req->assoclen + req->cryptlen,
                                 crypto_aead_authsize(authenc), 1);
}

static void authenc_geniv_ahash_done(void *data, int err)
{
        struct aead_request *req = data;

        if (!err)
                authenc_geniv_ahash_finish(req);
        aead_request_complete(req, err);
}

/*
 * Used when the ahash request was invoked in the async callback context
 * of the previous skcipher request.  Eat any EINPROGRESS notifications.
 */
static void authenc_geniv_ahash_done2(void *data, int err)
{
        struct aead_request *req = data;

        if (!err)
                authenc_geniv_ahash_finish(req);
        authenc_request_complete(req, err);
}

static int crypto_authenc_genicv(struct aead_request *req, unsigned int mask)
{
        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
        struct aead_instance *inst = aead_alg_instance(authenc);
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
        struct crypto_ahash *auth = ctx->auth;
        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
        unsigned int flags = aead_request_flags(req) & ~mask;
        u8 *hash = areq_ctx->tail;
        int err;

        ahash_request_set_tfm(ahreq, auth);
        ahash_request_set_crypt(ahreq, req->dst, hash,
                                req->assoclen + req->cryptlen);
        ahash_request_set_callback(ahreq, flags,
                                   mask ? authenc_geniv_ahash_done2 :
                                          authenc_geniv_ahash_done, req);

        err = crypto_ahash_digest(ahreq);
        if (err)
                return err;

        scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
                                 crypto_aead_authsize(authenc), 1);

        return 0;
}

static void crypto_authenc_encrypt_done(void *data, int err)
{
        struct aead_request *areq = data;

        if (err) {
                aead_request_complete(areq, err);
                return;
        }
        err = crypto_authenc_genicv(areq, CRYPTO_TFM_REQ_MAY_SLEEP);
        authenc_request_complete(areq, err);
}

static int crypto_authenc_encrypt(struct aead_request *req)
{
        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
        struct aead_instance *inst = aead_alg_instance(authenc);
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
        struct crypto_skcipher *enc = ctx->enc;
        unsigned int cryptlen = req->cryptlen;
        struct skcipher_request *skreq = (void *)(areq_ctx->tail +
                                                  ictx->reqoff);
        struct scatterlist *src, *dst;
        int err;

        src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
        dst = src;

        if (req->src != req->dst) {
                memcpy_sglist(req->dst, req->src, req->assoclen);
                dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
        }

        skcipher_request_set_tfm(skreq, enc);
        skcipher_request_set_callback(skreq, aead_request_flags(req),
                                      crypto_authenc_encrypt_done, req);
        skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);

        err = crypto_skcipher_encrypt(skreq);
        if (err)
                return err;

        return crypto_authenc_genicv(req, 0);
}

static void authenc_decrypt_tail_done(void *data, int err)
{
        struct aead_request *req = data;

        authenc_request_complete(req, err);
}

static int crypto_authenc_decrypt_tail(struct aead_request *req,
                                       unsigned int mask)
{
        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
        struct aead_instance *inst = aead_alg_instance(authenc);
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
        struct skcipher_request *skreq = (void *)(areq_ctx->tail +
                                                  ictx->reqoff);
        unsigned int authsize = crypto_aead_authsize(authenc);
        unsigned int flags = aead_request_flags(req) & ~mask;
        u8 *ihash = ahreq->result + authsize;
        struct scatterlist *src, *dst;

        scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);

        if (crypto_memneq(ihash, ahreq->result, authsize))
                return -EBADMSG;

        src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
        dst = src;

        if (req->src != req->dst)
                dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);

        skcipher_request_set_tfm(skreq, ctx->enc);
        skcipher_request_set_callback(skreq, flags,
                                      mask ? authenc_decrypt_tail_done :
                                             req->base.complete,
                                      mask ? req : req->base.data);
        skcipher_request_set_crypt(skreq, src, dst,
                                   req->cryptlen - authsize, req->iv);

        return crypto_skcipher_decrypt(skreq);
}

static void authenc_verify_ahash_done(void *data, int err)
{
        struct aead_request *req = data;

        if (err) {
                aead_request_complete(req, err);
                return;
        }
        err = crypto_authenc_decrypt_tail(req, CRYPTO_TFM_REQ_MAY_SLEEP);
        authenc_request_complete(req, err);
}

static int crypto_authenc_decrypt(struct aead_request *req)
{
        struct crypto_aead *authenc = crypto_aead_reqtfm(req);
        unsigned int authsize = crypto_aead_authsize(authenc);
        struct aead_instance *inst = aead_alg_instance(authenc);
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
        struct crypto_ahash *auth = ctx->auth;
        struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
        struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
        u8 *hash = areq_ctx->tail;
        int err;

        ahash_request_set_tfm(ahreq, auth);
        ahash_request_set_crypt(ahreq, req->src, hash,
                                req->assoclen + req->cryptlen - authsize);
        ahash_request_set_callback(ahreq, aead_request_flags(req),
                                   authenc_verify_ahash_done, req);

        err = crypto_ahash_digest(ahreq);
        if (err)
                return err;

        return crypto_authenc_decrypt_tail(req, 0);
}

static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
{
        struct aead_instance *inst = aead_alg_instance(tfm);
        struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
        struct crypto_ahash *auth;
        struct crypto_skcipher *enc;
        int err;

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

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

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

        crypto_aead_set_reqsize(
                tfm,
                sizeof(struct authenc_request_ctx) +
                ictx->reqoff +
                max_t(unsigned int,
                      crypto_ahash_reqsize(auth) +
                      sizeof(struct ahash_request),
                      sizeof(struct skcipher_request) +
                      crypto_skcipher_reqsize(enc)));

        return 0;

err_free_ahash:
        crypto_free_ahash(auth);
        return err;
}

static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
{
        struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);

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

static void crypto_authenc_free(struct aead_instance *inst)
{
        struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);

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

static int crypto_authenc_create(struct crypto_template *tmpl,
                                 struct rtattr **tb)
{
        u32 mask;
        struct aead_instance *inst;
        struct authenc_instance_ctx *ctx;
        struct skcipher_alg_common *enc;
        struct hash_alg_common *auth;
        struct crypto_alg *auth_base;
        int err;

        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
        if (err)
                return err;

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

        err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
                                crypto_attr_alg_name(tb[1]), 0, mask);
        if (err)
                goto err_free_inst;
        auth = crypto_spawn_ahash_alg(&ctx->auth);
        auth_base = &auth->base;

        err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
                                   crypto_attr_alg_name(tb[2]), 0, mask);
        if (err)
                goto err_free_inst;
        enc = crypto_spawn_skcipher_alg_common(&ctx->enc);

        ctx->reqoff = 2 * auth->digestsize;

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

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

        inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
                                      auth_base->cra_priority;
        inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
        inst->alg.base.cra_alignmask = enc->base.cra_alignmask;
        inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);

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

        inst->alg.init = crypto_authenc_init_tfm;
        inst->alg.exit = crypto_authenc_exit_tfm;

        inst->alg.setkey = crypto_authenc_setkey;
        inst->alg.encrypt = crypto_authenc_encrypt;
        inst->alg.decrypt = crypto_authenc_decrypt;

        inst->free = crypto_authenc_free;

        err = aead_register_instance(tmpl, inst);
        if (err) {
err_free_inst:
                crypto_authenc_free(inst);
        }
        return err;
}

static struct crypto_template crypto_authenc_tmpl = {
        .name = "authenc",
        .create = crypto_authenc_create,
        .module = THIS_MODULE,
};

static int __init crypto_authenc_module_init(void)
{
        return crypto_register_template(&crypto_authenc_tmpl);
}

static void __exit crypto_authenc_module_exit(void)
{
        crypto_unregister_template(&crypto_authenc_tmpl);
}

module_init(crypto_authenc_module_init);
module_exit(crypto_authenc_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
MODULE_ALIAS_CRYPTO("authenc");