// SPDX-License-Identifier: GPL-2.0-or-later
/* PKCS#8 Private Key parser [RFC 5208].
 *
 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) "PKCS8: "fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/oid_registry.h>
#include <keys/asymmetric-subtype.h>
#include <keys/asymmetric-parser.h>
#include <crypto/public_key.h>
#include "pkcs8.asn1.h"

struct pkcs8_parse_context {
        struct public_key *pub;
        unsigned long   data;                   /* Start of data */
        enum OID        last_oid;               /* Last OID encountered */
        enum OID        algo_oid;               /* Algorithm OID */
        u32             key_size;
        const void      *key;
};

/*
 * Note an OID when we find one for later processing when we know how to
 * interpret it.
 */
int pkcs8_note_OID(void *context, size_t hdrlen,
                   unsigned char tag,
                   const void *value, size_t vlen)
{
        struct pkcs8_parse_context *ctx = context;

        ctx->last_oid = look_up_OID(value, vlen);
        if (ctx->last_oid == OID__NR) {
                char buffer[50];

                sprint_oid(value, vlen, buffer, sizeof(buffer));
                pr_info("Unknown OID: [%lu] %s\n",
                        (unsigned long)value - ctx->data, buffer);
        }
        return 0;
}

/*
 * Note the version number of the ASN.1 blob.
 */
int pkcs8_note_version(void *context, size_t hdrlen,
                       unsigned char tag,
                       const void *value, size_t vlen)
{
        if (vlen != 1 || ((const u8 *)value)[0] != 0) {
                pr_warn("Unsupported PKCS#8 version\n");
                return -EBADMSG;
        }
        return 0;
}

/*
 * Note the public algorithm.
 */
int pkcs8_note_algo(void *context, size_t hdrlen,
                    unsigned char tag,
                    const void *value, size_t vlen)
{
        struct pkcs8_parse_context *ctx = context;

        if (ctx->last_oid != OID_rsaEncryption)
                return -ENOPKG;

        ctx->pub->pkey_algo = "rsa";
        return 0;
}

/*
 * Note the key data of the ASN.1 blob.
 */
int pkcs8_note_key(void *context, size_t hdrlen,
                   unsigned char tag,
                   const void *value, size_t vlen)
{
        struct pkcs8_parse_context *ctx = context;

        ctx->key = value;
        ctx->key_size = vlen;
        return 0;
}

/*
 * Parse a PKCS#8 private key blob.
 */
static struct public_key *pkcs8_parse(const void *data, size_t datalen)
{
        struct pkcs8_parse_context ctx;
        struct public_key *pub;
        long ret;

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

        ret = -ENOMEM;
        ctx.pub = kzalloc_obj(struct public_key);
        if (!ctx.pub)
                goto error;

        ctx.data = (unsigned long)data;

        /* Attempt to decode the private key */
        ret = asn1_ber_decoder(&pkcs8_decoder, &ctx, data, datalen);
        if (ret < 0)
                goto error_decode;

        ret = -ENOMEM;
        pub = ctx.pub;
        pub->key = kmemdup(ctx.key, ctx.key_size, GFP_KERNEL);
        if (!pub->key)
                goto error_decode;

        pub->keylen = ctx.key_size;
        pub->key_is_private = true;
        return pub;

error_decode:
        kfree(ctx.pub);
error:
        return ERR_PTR(ret);
}

/*
 * Attempt to parse a data blob for a key as a PKCS#8 private key.
 */
static int pkcs8_key_preparse(struct key_preparsed_payload *prep)
{
        struct public_key *pub;

        pub = pkcs8_parse(prep->data, prep->datalen);
        if (IS_ERR(pub))
                return PTR_ERR(pub);

        pr_devel("Cert Key Algo: %s\n", pub->pkey_algo);
        pub->id_type = "PKCS8";

        /* We're pinning the module by being linked against it */
        __module_get(public_key_subtype.owner);
        prep->payload.data[asym_subtype] = &public_key_subtype;
        prep->payload.data[asym_key_ids] = NULL;
        prep->payload.data[asym_crypto] = pub;
        prep->payload.data[asym_auth] = NULL;
        prep->quotalen = 100;
        return 0;
}

static struct asymmetric_key_parser pkcs8_key_parser = {
        .owner  = THIS_MODULE,
        .name   = "pkcs8",
        .parse  = pkcs8_key_preparse,
};

/*
 * Module stuff
 */
static int __init pkcs8_key_init(void)
{
        return register_asymmetric_key_parser(&pkcs8_key_parser);
}

static void __exit pkcs8_key_exit(void)
{
        unregister_asymmetric_key_parser(&pkcs8_key_parser);
}

module_init(pkcs8_key_init);
module_exit(pkcs8_key_exit);

MODULE_DESCRIPTION("PKCS#8 certificate parser");
MODULE_LICENSE("GPL");