root/crypto/akcipher.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Public Key Encryption
 *
 * Copyright (c) 2015, Intel Corporation
 * Authors: Tadeusz Struk <tadeusz.struk@intel.com>
 */
#include <crypto/internal/akcipher.h>
#include <linux/cryptouser.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <net/netlink.h>

#include "internal.h"

#define CRYPTO_ALG_TYPE_AHASH_MASK      0x0000000e

struct crypto_akcipher_sync_data {
        struct crypto_akcipher *tfm;
        const void *src;
        void *dst;
        unsigned int slen;
        unsigned int dlen;

        struct akcipher_request *req;
        struct crypto_wait cwait;
        struct scatterlist sg;
        u8 *buf;
};

static int __maybe_unused crypto_akcipher_report(
        struct sk_buff *skb, struct crypto_alg *alg)
{
        struct crypto_report_akcipher rakcipher;

        memset(&rakcipher, 0, sizeof(rakcipher));

        strscpy(rakcipher.type, "akcipher", sizeof(rakcipher.type));

        return nla_put(skb, CRYPTOCFGA_REPORT_AKCIPHER,
                       sizeof(rakcipher), &rakcipher);
}

static void __maybe_unused crypto_akcipher_show(struct seq_file *m,
                                                struct crypto_alg *alg)
{
        seq_puts(m, "type         : akcipher\n");
}

static void crypto_akcipher_exit_tfm(struct crypto_tfm *tfm)
{
        struct crypto_akcipher *akcipher = __crypto_akcipher_tfm(tfm);
        struct akcipher_alg *alg = crypto_akcipher_alg(akcipher);

        alg->exit(akcipher);
}

static int crypto_akcipher_init_tfm(struct crypto_tfm *tfm)
{
        struct crypto_akcipher *akcipher = __crypto_akcipher_tfm(tfm);
        struct akcipher_alg *alg = crypto_akcipher_alg(akcipher);

        if (alg->exit)
                akcipher->base.exit = crypto_akcipher_exit_tfm;

        if (alg->init)
                return alg->init(akcipher);

        return 0;
}

static void crypto_akcipher_free_instance(struct crypto_instance *inst)
{
        struct akcipher_instance *akcipher = akcipher_instance(inst);

        akcipher->free(akcipher);
}

static const struct crypto_type crypto_akcipher_type = {
        .extsize = crypto_alg_extsize,
        .init_tfm = crypto_akcipher_init_tfm,
        .free = crypto_akcipher_free_instance,
#ifdef CONFIG_PROC_FS
        .show = crypto_akcipher_show,
#endif
#if IS_ENABLED(CONFIG_CRYPTO_USER)
        .report = crypto_akcipher_report,
#endif
        .maskclear = ~CRYPTO_ALG_TYPE_MASK,
        .maskset = CRYPTO_ALG_TYPE_AHASH_MASK,
        .type = CRYPTO_ALG_TYPE_AKCIPHER,
        .tfmsize = offsetof(struct crypto_akcipher, base),
        .algsize = offsetof(struct akcipher_alg, base),
};

int crypto_grab_akcipher(struct crypto_akcipher_spawn *spawn,
                         struct crypto_instance *inst,
                         const char *name, u32 type, u32 mask)
{
        spawn->base.frontend = &crypto_akcipher_type;
        return crypto_grab_spawn(&spawn->base, inst, name, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_grab_akcipher);

struct crypto_akcipher *crypto_alloc_akcipher(const char *alg_name, u32 type,
                                              u32 mask)
{
        return crypto_alloc_tfm(alg_name, &crypto_akcipher_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_akcipher);

static void akcipher_prepare_alg(struct akcipher_alg *alg)
{
        struct crypto_alg *base = &alg->base;

        base->cra_type = &crypto_akcipher_type;
        base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
        base->cra_flags |= CRYPTO_ALG_TYPE_AKCIPHER;
}

static int akcipher_default_op(struct akcipher_request *req)
{
        return -ENOSYS;
}

static int akcipher_default_set_key(struct crypto_akcipher *tfm,
                                     const void *key, unsigned int keylen)
{
        return -ENOSYS;
}

int crypto_register_akcipher(struct akcipher_alg *alg)
{
        struct crypto_alg *base = &alg->base;

        if (!alg->encrypt)
                alg->encrypt = akcipher_default_op;
        if (!alg->decrypt)
                alg->decrypt = akcipher_default_op;
        if (!alg->set_priv_key)
                alg->set_priv_key = akcipher_default_set_key;

        akcipher_prepare_alg(alg);
        return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_akcipher);

void crypto_unregister_akcipher(struct akcipher_alg *alg)
{
        crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_akcipher);

int akcipher_register_instance(struct crypto_template *tmpl,
                               struct akcipher_instance *inst)
{
        if (WARN_ON(!inst->free))
                return -EINVAL;
        akcipher_prepare_alg(&inst->alg);
        return crypto_register_instance(tmpl, akcipher_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(akcipher_register_instance);

static int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data)
{
        unsigned int reqsize = crypto_akcipher_reqsize(data->tfm);
        struct akcipher_request *req;
        struct scatterlist *sg;
        unsigned int mlen;
        unsigned int len;
        u8 *buf;

        mlen = max(data->slen, data->dlen);

        len = sizeof(*req) + reqsize + mlen;
        if (len < mlen)
                return -EOVERFLOW;

        req = kzalloc(len, GFP_KERNEL);
        if (!req)
                return -ENOMEM;

        data->req = req;
        akcipher_request_set_tfm(req, data->tfm);

        buf = (u8 *)(req + 1) + reqsize;
        data->buf = buf;
        memcpy(buf, data->src, data->slen);

        sg = &data->sg;
        sg_init_one(sg, buf, mlen);
        akcipher_request_set_crypt(req, sg, sg, data->slen, data->dlen);

        crypto_init_wait(&data->cwait);
        akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
                                      crypto_req_done, &data->cwait);

        return 0;
}

static int crypto_akcipher_sync_post(struct crypto_akcipher_sync_data *data,
                                     int err)
{
        err = crypto_wait_req(err, &data->cwait);
        memcpy(data->dst, data->buf, data->dlen);
        data->dlen = data->req->dst_len;
        kfree_sensitive(data->req);
        return err;
}

int crypto_akcipher_sync_encrypt(struct crypto_akcipher *tfm,
                                 const void *src, unsigned int slen,
                                 void *dst, unsigned int dlen)
{
        struct crypto_akcipher_sync_data data = {
                .tfm = tfm,
                .src = src,
                .dst = dst,
                .slen = slen,
                .dlen = dlen,
        };

        return crypto_akcipher_sync_prep(&data) ?:
               crypto_akcipher_sync_post(&data,
                                         crypto_akcipher_encrypt(data.req));
}
EXPORT_SYMBOL_GPL(crypto_akcipher_sync_encrypt);

int crypto_akcipher_sync_decrypt(struct crypto_akcipher *tfm,
                                 const void *src, unsigned int slen,
                                 void *dst, unsigned int dlen)
{
        struct crypto_akcipher_sync_data data = {
                .tfm = tfm,
                .src = src,
                .dst = dst,
                .slen = slen,
                .dlen = dlen,
        };

        return crypto_akcipher_sync_prep(&data) ?:
               crypto_akcipher_sync_post(&data,
                                         crypto_akcipher_decrypt(data.req)) ?:
               data.dlen;
}
EXPORT_SYMBOL_GPL(crypto_akcipher_sync_decrypt);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Generic public key cipher type");