![Michael Brown](/assets/img/avatar_default.png)
If a root certificate has been explicitly specified at build time using TRUST=/path/to/cert then do not allow this to be overridden even from a trustworthy settings source (such as VMware GuestInfo). Similarly, if a client certificate (and private key) has been explicitly specified at build time, then do not allow it to be overridden at runtime. Signed-off-by: Michael Brown <mcb30@ipxe.org>
133 lines
4.1 KiB
C
133 lines
4.1 KiB
C
/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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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 License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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#include <stdlib.h>
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#include <ipxe/crypto.h>
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#include <ipxe/sha256.h>
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#include <ipxe/x509.h>
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#include <ipxe/settings.h>
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#include <ipxe/dhcp.h>
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#include <ipxe/init.h>
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#include <ipxe/rootcert.h>
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/** @file
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*
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* Root certificate store
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*
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*/
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/** Length of a root certificate fingerprint */
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#define FINGERPRINT_LEN SHA256_DIGEST_SIZE
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/* Allow trusted certificates to be overridden if not explicitly specified */
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#ifdef TRUSTED
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#define ALLOW_TRUST_OVERRIDE 0
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#else
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#define ALLOW_TRUST_OVERRIDE 1
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#endif
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/* Use iPXE root CA if no trusted certificates are explicitly specified */
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#ifndef TRUSTED
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#define TRUSTED \
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/* iPXE root CA */ \
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0x9f, 0xaf, 0x71, 0x7b, 0x7f, 0x8c, 0xa2, 0xf9, 0x3c, 0x25, \
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0x6c, 0x79, 0xf8, 0xac, 0x55, 0x91, 0x89, 0x5d, 0x66, 0xd1, \
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0xff, 0x3b, 0xee, 0x63, 0x97, 0xa7, 0x0d, 0x29, 0xc6, 0x5e, \
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0xed, 0x1a,
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#endif
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/** Root certificate fingerprints */
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static const uint8_t fingerprints[] = { TRUSTED };
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/** Root certificate fingerprint setting */
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static struct setting trust_setting __setting ( SETTING_CRYPTO ) = {
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.name = "trust",
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.description = "Trusted root certificate fingerprints",
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.tag = DHCP_EB_TRUST,
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.type = &setting_type_hex,
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};
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/** Root certificates */
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struct x509_root root_certificates = {
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.digest = &sha256_algorithm,
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.count = ( sizeof ( fingerprints ) / FINGERPRINT_LEN ),
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.fingerprints = fingerprints,
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};
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/**
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* Initialise root certificate
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*
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* The list of trusted root certificates can be specified at build
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* time using the TRUST= build parameter. If no certificates are
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* specified, then the default iPXE root CA certificate is trusted.
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*
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* If no certificates were explicitly specified, then we allow the
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* list of trusted root certificate fingerprints to be overridden
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* using the "trust" setting, but only at the point of iPXE
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* initialisation. This prevents untrusted sources of settings
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* (e.g. DHCP) from subverting the chain of trust, while allowing
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* trustworthy sources (e.g. VMware GuestInfo or non-volatile stored
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* options) to specify the trusted root certificate without requiring
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* a rebuild.
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*/
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static void rootcert_init ( void ) {
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void *external = NULL;
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int len;
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int rc;
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/* Allow trusted root certificates to be overridden only if
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* not explicitly specified at build time.
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*/
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if ( ALLOW_TRUST_OVERRIDE ) {
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/* Fetch copy of "trust" setting, if it exists. This
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* memory will never be freed.
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*/
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len = fetch_setting_copy ( NULL, &trust_setting, &external );
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if ( len < 0 ) {
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rc = len;
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DBGC ( &root_certificates, "ROOTCERT cannot fetch "
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"trusted root certificate fingerprints: %s\n",
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strerror ( rc ) );
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/* No way to prevent startup; fail safe by
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* trusting no certificates.
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*/
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root_certificates.count = 0;
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return;
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}
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/* Use certificates from "trust" setting, if present */
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if ( external ) {
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root_certificates.fingerprints = external;
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root_certificates.count = ( len / FINGERPRINT_LEN );
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}
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}
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DBGC ( &root_certificates, "ROOTCERT using %d %s certificate(s):\n",
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root_certificates.count, ( external ? "external" : "built-in" ));
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DBGC_HDA ( &root_certificates, 0, root_certificates.fingerprints,
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( root_certificates.count * FINGERPRINT_LEN ) );
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}
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/** Root certificate initialiser */
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struct init_fn rootcert_init_fn __init_fn ( INIT_LATE ) = {
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.initialise = rootcert_init,
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};
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