/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Public Key Signature Algorithm
 *
 * Copyright (c) 2023 Herbert Xu <herbert@gondor.apana.org.au>
 */

#include <crypto/internal/sig.h>
#include <linux/cryptouser.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <net/netlink.h>

#include "internal.h"

static void crypto_sig_exit_tfm(struct crypto_tfm *tfm)
{
        struct crypto_sig *sig = __crypto_sig_tfm(tfm);
        struct sig_alg *alg = crypto_sig_alg(sig);

        alg->exit(sig);
}

static int crypto_sig_init_tfm(struct crypto_tfm *tfm)
{
        struct crypto_sig *sig = __crypto_sig_tfm(tfm);
        struct sig_alg *alg = crypto_sig_alg(sig);

        if (alg->exit)
                sig->base.exit = crypto_sig_exit_tfm;

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

        return 0;
}

static void crypto_sig_free_instance(struct crypto_instance *inst)
{
        struct sig_instance *sig = sig_instance(inst);

        sig->free(sig);
}

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

static int __maybe_unused crypto_sig_report(struct sk_buff *skb,
                                            struct crypto_alg *alg)
{
        struct crypto_report_sig rsig = {};

        strscpy(rsig.type, "sig", sizeof(rsig.type));

        return nla_put(skb, CRYPTOCFGA_REPORT_SIG, sizeof(rsig), &rsig);
}

static const struct crypto_type crypto_sig_type = {
        .extsize = crypto_alg_extsize,
        .init_tfm = crypto_sig_init_tfm,
        .free = crypto_sig_free_instance,
#ifdef CONFIG_PROC_FS
        .show = crypto_sig_show,
#endif
#if IS_ENABLED(CONFIG_CRYPTO_USER)
        .report = crypto_sig_report,
#endif
        .maskclear = ~CRYPTO_ALG_TYPE_MASK,
        .maskset = CRYPTO_ALG_TYPE_MASK,
        .type = CRYPTO_ALG_TYPE_SIG,
        .tfmsize = offsetof(struct crypto_sig, base),
        .algsize = offsetof(struct sig_alg, base),
};

struct crypto_sig *crypto_alloc_sig(const char *alg_name, u32 type, u32 mask)
{
        return crypto_alloc_tfm(alg_name, &crypto_sig_type, type, mask);
}
EXPORT_SYMBOL_GPL(crypto_alloc_sig);

static int sig_default_sign(struct crypto_sig *tfm,
                            const void *src, unsigned int slen,
                            void *dst, unsigned int dlen)
{
        return -ENOSYS;
}

static int sig_default_verify(struct crypto_sig *tfm,
                              const void *src, unsigned int slen,
                              const void *dst, unsigned int dlen)
{
        return -ENOSYS;
}

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

static unsigned int sig_default_size(struct crypto_sig *tfm)
{
        return DIV_ROUND_UP_POW2(crypto_sig_keysize(tfm), BITS_PER_BYTE);
}

static int sig_prepare_alg(struct sig_alg *alg)
{
        struct crypto_alg *base = &alg->base;

        if (!alg->sign)
                alg->sign = sig_default_sign;
        if (!alg->verify)
                alg->verify = sig_default_verify;
        if (!alg->set_priv_key)
                alg->set_priv_key = sig_default_set_key;
        if (!alg->set_pub_key)
                return -EINVAL;
        if (!alg->key_size)
                return -EINVAL;
        if (!alg->max_size)
                alg->max_size = sig_default_size;
        if (!alg->digest_size)
                alg->digest_size = sig_default_size;

        base->cra_type = &crypto_sig_type;
        base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
        base->cra_flags |= CRYPTO_ALG_TYPE_SIG;

        return 0;
}

int crypto_register_sig(struct sig_alg *alg)
{
        struct crypto_alg *base = &alg->base;
        int err;

        err = sig_prepare_alg(alg);
        if (err)
                return err;

        return crypto_register_alg(base);
}
EXPORT_SYMBOL_GPL(crypto_register_sig);

void crypto_unregister_sig(struct sig_alg *alg)
{
        crypto_unregister_alg(&alg->base);
}
EXPORT_SYMBOL_GPL(crypto_unregister_sig);

int sig_register_instance(struct crypto_template *tmpl,
                          struct sig_instance *inst)
{
        int err;

        if (WARN_ON(!inst->free))
                return -EINVAL;

        err = sig_prepare_alg(&inst->alg);
        if (err)
                return err;

        return crypto_register_instance(tmpl, sig_crypto_instance(inst));
}
EXPORT_SYMBOL_GPL(sig_register_instance);

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

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Public Key Signature Algorithms");