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cfb664ff2b
Move the X.509 trust validation code out to its own file so that it can be generalised. Signed-off-by: David Howells <dhowells@redhat.com>
107 lines
2.8 KiB
C
107 lines
2.8 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 <keys/system_keyring.h>
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#include <crypto/hash.h>
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#include <crypto/public_key.h>
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#include "asymmetric_keys.h"
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#include "x509_parser.h"
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static bool use_builtin_keys;
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static struct asymmetric_key_id *ca_keyid;
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#ifndef MODULE
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static struct {
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struct asymmetric_key_id id;
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unsigned char data[10];
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} cakey;
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static int __init ca_keys_setup(char *str)
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{
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if (!str) /* default system keyring */
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return 1;
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if (strncmp(str, "id:", 3) == 0) {
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struct asymmetric_key_id *p = &cakey.id;
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size_t hexlen = (strlen(str) - 3) / 2;
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int ret;
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if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
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pr_err("Missing or invalid ca_keys id\n");
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return 1;
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}
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ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
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if (ret < 0)
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pr_err("Unparsable ca_keys id hex string\n");
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else
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ca_keyid = p; /* owner key 'id:xxxxxx' */
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} else if (strcmp(str, "builtin") == 0) {
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use_builtin_keys = true;
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}
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return 1;
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}
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__setup("ca_keys=", ca_keys_setup);
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#endif
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/*
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* Check the new certificate against the ones in the trust keyring. If one of
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* those is the signing key and validates the new certificate, then mark the
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* new certificate as being trusted.
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*
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* Return 0 if the new certificate was successfully validated, 1 if we couldn't
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* find a matching parent certificate in the trusted list and an error if there
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* is a matching certificate but the signature check fails.
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*/
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int x509_validate_trust(struct x509_certificate *cert,
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struct key *trust_keyring)
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{
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struct public_key_signature *sig = cert->sig;
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struct key *key;
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int ret = 1;
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if (!sig->auth_ids[0] && !sig->auth_ids[1])
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return 1;
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if (!trust_keyring)
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return -EOPNOTSUPP;
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if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
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return -EPERM;
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if (cert->unsupported_sig)
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return -ENOPKG;
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key = find_asymmetric_key(trust_keyring,
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sig->auth_ids[0], sig->auth_ids[1],
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false);
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if (IS_ERR(key))
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return PTR_ERR(key);
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if (!use_builtin_keys ||
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test_bit(KEY_FLAG_BUILTIN, &key->flags)) {
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ret = verify_signature(key, cert->sig);
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if (ret == -ENOPKG)
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cert->unsupported_sig = true;
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}
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key_put(key);
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return ret;
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}
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EXPORT_SYMBOL_GPL(x509_validate_trust);
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