public_key.c

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/* In-software asymmetric public-key crypto subtype
 *
 * See Documentation/crypto/asymmetric-keys.txt
 *
 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#define pr_fmt(fmt) "PKEY: "fmt
#include <linux/module.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <keys/asymmetric-subtype.h>
#include "public_key.h"

MODULE_LICENSE("GPL");

const char *const pkey_algo[PKEY_ALGO__LAST] = {
    [PKEY_ALGO_DSA]     = "DSA",
    [PKEY_ALGO_RSA]     = "RSA",
};
EXPORT_SYMBOL_GPL(pkey_algo);

const char *const pkey_hash_algo[PKEY_HASH__LAST] = {
    [PKEY_HASH_MD4]     = "md4",
    [PKEY_HASH_MD5]     = "md5",
    [PKEY_HASH_SHA1]    = "sha1",
    [PKEY_HASH_RIPE_MD_160] = "rmd160",
    [PKEY_HASH_SHA256]  = "sha256",
    [PKEY_HASH_SHA384]  = "sha384",
    [PKEY_HASH_SHA512]  = "sha512",
    [PKEY_HASH_SHA224]  = "sha224",
};
EXPORT_SYMBOL_GPL(pkey_hash_algo);

const char *const pkey_id_type[PKEY_ID_TYPE__LAST] = {
    [PKEY_ID_PGP]       = "PGP",
    [PKEY_ID_X509]      = "X509",
};
EXPORT_SYMBOL_GPL(pkey_id_type);

/*
 * Provide a part of a description of the key for /proc/keys.
 */
static void public_key_describe(const struct key *asymmetric_key,
                struct seq_file *m)
{
    struct public_key *key = asymmetric_key->payload.data;

    if (key)
        seq_printf(m, "%s.%s",
               pkey_id_type[key->id_type], key->algo->name);
}

/*
 * Destroy a public key algorithm key.
 */
void public_key_destroy(void *payload)
{
    struct public_key *key = payload;
    int i;

    if (key) {
        for (i = 0; i < ARRAY_SIZE(key->mpi); i++)
            mpi_free(key->mpi[i]);
        kfree(key);
    }
}
EXPORT_SYMBOL_GPL(public_key_destroy);

/*
 * Verify a signature using a public key.
 */
static int public_key_verify_signature(const struct key *key,
                       const struct public_key_signature *sig)
{
    const struct public_key *pk = key->payload.data;

    if (!pk->algo->verify_signature)
        return -ENOTSUPP;

    if (sig->nr_mpi != pk->algo->n_sig_mpi) {
        pr_debug("Signature has %u MPI not %u\n",
             sig->nr_mpi, pk->algo->n_sig_mpi);
        return -EINVAL;
    }

    return pk->algo->verify_signature(pk, sig);
}

/*
 * Public key algorithm asymmetric key subtype
 */
struct asymmetric_key_subtype public_key_subtype = {
    .owner          = THIS_MODULE,
    .name           = "public_key",
    .describe       = public_key_describe,
    .destroy        = public_key_destroy,
    .verify_signature   = public_key_verify_signature,
};
EXPORT_SYMBOL_GPL(public_key_subtype);