240 lines
6.8 KiB
C
240 lines
6.8 KiB
C
/* Instantiate a public key crypto key from an X.509 Certificate
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#define pr_fmt(fmt) "X.509: "fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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#include <linux/mpi.h>
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#include <linux/asn1_decoder.h>
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#include <keys/asymmetric-subtype.h>
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#include <keys/asymmetric-parser.h>
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#include <crypto/hash.h>
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#include "asymmetric_keys.h"
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#include "public_key.h"
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#include "x509_parser.h"
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static const
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struct public_key_algorithm *x509_public_key_algorithms[PKEY_ALGO__LAST] = {
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[PKEY_ALGO_DSA] = NULL,
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#if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \
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defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE)
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[PKEY_ALGO_RSA] = &RSA_public_key_algorithm,
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#endif
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};
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/*
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* Check the signature on a certificate using the provided public key
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*/
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static int x509_check_signature(const struct public_key *pub,
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const struct x509_certificate *cert)
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{
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struct public_key_signature *sig;
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struct crypto_shash *tfm;
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struct shash_desc *desc;
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size_t digest_size, desc_size;
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int ret;
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pr_devel("==>%s()\n", __func__);
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/* Allocate the hashing algorithm we're going to need and find out how
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* big the hash operational data will be.
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*/
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tfm = crypto_alloc_shash(pkey_hash_algo[cert->sig_hash_algo], 0, 0);
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if (IS_ERR(tfm))
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return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
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desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
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digest_size = crypto_shash_digestsize(tfm);
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/* We allocate the hash operational data storage on the end of our
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* context data.
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*/
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ret = -ENOMEM;
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sig = kzalloc(sizeof(*sig) + desc_size + digest_size, GFP_KERNEL);
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if (!sig)
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goto error_no_sig;
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sig->pkey_hash_algo = cert->sig_hash_algo;
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sig->digest = (u8 *)sig + sizeof(*sig) + desc_size;
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sig->digest_size = digest_size;
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desc = (void *)sig + sizeof(*sig);
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desc->tfm = tfm;
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desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
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ret = crypto_shash_init(desc);
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if (ret < 0)
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goto error;
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ret = -ENOMEM;
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sig->rsa.s = mpi_read_raw_data(cert->sig, cert->sig_size);
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if (!sig->rsa.s)
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goto error;
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ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest);
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if (ret < 0)
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goto error_mpi;
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ret = pub->algo->verify_signature(pub, sig);
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pr_debug("Cert Verification: %d\n", ret);
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error_mpi:
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mpi_free(sig->rsa.s);
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error:
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kfree(sig);
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error_no_sig:
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crypto_free_shash(tfm);
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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/*
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* Attempt to parse a data blob for a key as an X509 certificate.
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*/
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static int x509_key_preparse(struct key_preparsed_payload *prep)
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{
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struct x509_certificate *cert;
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struct tm now;
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size_t srlen, sulen;
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char *desc = NULL;
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int ret;
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cert = x509_cert_parse(prep->data, prep->datalen);
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if (IS_ERR(cert))
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return PTR_ERR(cert);
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pr_devel("Cert Issuer: %s\n", cert->issuer);
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pr_devel("Cert Subject: %s\n", cert->subject);
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pr_devel("Cert Key Algo: %s\n", pkey_algo[cert->pkey_algo]);
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pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
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cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
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cert->valid_from.tm_mday, cert->valid_from.tm_hour,
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cert->valid_from.tm_min, cert->valid_from.tm_sec);
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pr_devel("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n",
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cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1,
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cert->valid_to.tm_mday, cert->valid_to.tm_hour,
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cert->valid_to.tm_min, cert->valid_to.tm_sec);
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pr_devel("Cert Signature: %s + %s\n",
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pkey_algo[cert->sig_pkey_algo],
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pkey_hash_algo[cert->sig_hash_algo]);
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if (!cert->fingerprint || !cert->authority) {
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pr_warn("Cert for '%s' must have SubjKeyId and AuthKeyId extensions\n",
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cert->subject);
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ret = -EKEYREJECTED;
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goto error_free_cert;
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}
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time_to_tm(CURRENT_TIME.tv_sec, 0, &now);
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pr_devel("Now: %04ld-%02d-%02d %02d:%02d:%02d\n",
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now.tm_year + 1900, now.tm_mon + 1, now.tm_mday,
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now.tm_hour, now.tm_min, now.tm_sec);
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if (now.tm_year < cert->valid_from.tm_year ||
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(now.tm_year == cert->valid_from.tm_year &&
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(now.tm_mon < cert->valid_from.tm_mon ||
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(now.tm_mon == cert->valid_from.tm_mon &&
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(now.tm_mday < cert->valid_from.tm_mday ||
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(now.tm_mday == cert->valid_from.tm_mday &&
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(now.tm_hour < cert->valid_from.tm_hour ||
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(now.tm_hour == cert->valid_from.tm_hour &&
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(now.tm_min < cert->valid_from.tm_min ||
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(now.tm_min == cert->valid_from.tm_min &&
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(now.tm_sec < cert->valid_from.tm_sec
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))))))))))) {
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pr_warn("Cert %s is not yet valid\n", cert->fingerprint);
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ret = -EKEYREJECTED;
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goto error_free_cert;
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}
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if (now.tm_year > cert->valid_to.tm_year ||
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(now.tm_year == cert->valid_to.tm_year &&
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(now.tm_mon > cert->valid_to.tm_mon ||
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(now.tm_mon == cert->valid_to.tm_mon &&
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(now.tm_mday > cert->valid_to.tm_mday ||
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(now.tm_mday == cert->valid_to.tm_mday &&
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(now.tm_hour > cert->valid_to.tm_hour ||
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(now.tm_hour == cert->valid_to.tm_hour &&
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(now.tm_min > cert->valid_to.tm_min ||
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(now.tm_min == cert->valid_to.tm_min &&
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(now.tm_sec > cert->valid_to.tm_sec
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))))))))))) {
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pr_warn("Cert %s has expired\n", cert->fingerprint);
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ret = -EKEYEXPIRED;
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goto error_free_cert;
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}
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cert->pub->algo = x509_public_key_algorithms[cert->pkey_algo];
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cert->pub->id_type = PKEY_ID_X509;
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/* Check the signature on the key */
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if (strcmp(cert->fingerprint, cert->authority) == 0) {
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ret = x509_check_signature(cert->pub, cert);
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if (ret < 0)
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goto error_free_cert;
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}
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/* Propose a description */
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sulen = strlen(cert->subject);
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srlen = strlen(cert->fingerprint);
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ret = -ENOMEM;
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desc = kmalloc(sulen + 2 + srlen + 1, GFP_KERNEL);
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if (!desc)
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goto error_free_cert;
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memcpy(desc, cert->subject, sulen);
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desc[sulen] = ':';
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desc[sulen + 1] = ' ';
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memcpy(desc + sulen + 2, cert->fingerprint, srlen);
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desc[sulen + 2 + srlen] = 0;
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/* We're pinning the module by being linked against it */
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__module_get(public_key_subtype.owner);
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prep->type_data[0] = &public_key_subtype;
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prep->type_data[1] = cert->fingerprint;
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prep->payload = cert->pub;
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prep->description = desc;
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prep->quotalen = 100;
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/* We've finished with the certificate */
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cert->pub = NULL;
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cert->fingerprint = NULL;
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desc = NULL;
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ret = 0;
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error_free_cert:
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x509_free_certificate(cert);
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return ret;
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}
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static struct asymmetric_key_parser x509_key_parser = {
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.owner = THIS_MODULE,
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.name = "x509",
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.parse = x509_key_preparse,
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};
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/*
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* Module stuff
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*/
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static int __init x509_key_init(void)
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{
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return register_asymmetric_key_parser(&x509_key_parser);
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}
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static void __exit x509_key_exit(void)
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{
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unregister_asymmetric_key_parser(&x509_key_parser);
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}
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module_init(x509_key_init);
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module_exit(x509_key_exit);
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