src/crypto/rootcert.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  *
  19  * You can also choose to distribute this program under the terms of
  20  * the Unmodified Binary Distribution Licence (as given in the file
  21  * COPYING.UBDL), provided that you have satisfied its requirements.
  22  */
  23
  24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  25
  26 #include <stdlib.h>
  27 #include <ipxe/crypto.h>
  28 #include <ipxe/sha256.h>
  29 #include <ipxe/x509.h>
  30 #include <ipxe/settings.h>
  31 #include <ipxe/dhcp.h>
  32 #include <ipxe/init.h>
  33 #include <ipxe/rootcert.h>
  34
  35 /** @file
  36  *
  37  * Root certificate store
  38  *
  39  */
  40
  41 /** Length of a root certificate fingerprint */
  42 #define FINGERPRINT_LEN SHA256_DIGEST_SIZE
  43
  44 /* Allow trusted certificates to be overridden if not explicitly specified */
  45 #ifdef TRUSTED
  46 #define ALLOW_TRUST_OVERRIDE 0
  47 #else
  48 #define ALLOW_TRUST_OVERRIDE 1
  49 #endif
  50
  51 /* Use iPXE root CA if no trusted certificates are explicitly specified */
  52 #ifndef TRUSTED
  53 #define TRUSTED                                                         \
  54         /* iPXE root CA */                                              \
  55         0x9f, 0xaf, 0x71, 0x7b, 0x7f, 0x8c, 0xa2, 0xf9, 0x3c, 0x25,     \
  56         0x6c, 0x79, 0xf8, 0xac, 0x55, 0x91, 0x89, 0x5d, 0x66, 0xd1,     \
  57         0xff, 0x3b, 0xee, 0x63, 0x97, 0xa7, 0x0d, 0x29, 0xc6, 0x5e,     \
  58         0xed, 0x1a,
  59 #endif
  60
  61 /** Root certificate fingerprints */
  62 static const uint8_t fingerprints[] = { TRUSTED };
  63
  64 /** Root certificate fingerprint setting */
  65 static struct setting trust_setting __setting ( SETTING_CRYPTO, trust ) = {
  66         .name = "trust",
  67         .description = "Trusted root certificate fingerprints",
  68         .tag = DHCP_EB_TRUST,
  69         .type = &setting_type_hex,
  70 };
  71
  72 /** Root certificates */
  73 struct x509_root root_certificates = {
  74         .digest = &sha256_algorithm,
  75         .count = ( sizeof ( fingerprints ) / FINGERPRINT_LEN ),
  76         .fingerprints = fingerprints,
  77 };
  78
  79 /**
  80  * Initialise root certificate
  81  *
  82  * The list of trusted root certificates can be specified at build
  83  * time using the TRUST= build parameter.  If no certificates are
  84  * specified, then the default iPXE root CA certificate is trusted.
  85  *
  86  * If no certificates were explicitly specified, then we allow the
  87  * list of trusted root certificate fingerprints to be overridden
  88  * using the "trust" setting, but only at the point of iPXE
  89  * initialisation.  This prevents untrusted sources of settings
  90  * (e.g. DHCP) from subverting the chain of trust, while allowing
  91  * trustworthy sources (e.g. VMware GuestInfo or non-volatile stored
  92  * options) to specify the trusted root certificate without requiring
  93  * a rebuild.
  94  */
  95 static void rootcert_init ( void ) {
  96         void *external = NULL;
  97         int len;
  98
  99         /* Allow trusted root certificates to be overridden only if
 100          * not explicitly specified at build time.
 101          */
 102         if ( ALLOW_TRUST_OVERRIDE ) {
 103
 104                 /* Fetch copy of "trust" setting, if it exists.  This
 105                  * memory will never be freed.
 106                  */
 107                 if ( ( len = fetch_raw_setting_copy ( NULL, &trust_setting,
 108                                                       &external ) ) >= 0 ) {
 109                         root_certificates.fingerprints = external;
 110                         root_certificates.count = ( len / FINGERPRINT_LEN );
 111                 }
 112         }
 113
 114         DBGC ( &root_certificates, "ROOTCERT using %d %s certificate(s):\n",
 115                root_certificates.count, ( external ? "external" : "built-in" ));
 116         DBGC_HDA ( &root_certificates, 0, root_certificates.fingerprints,
 117                    ( root_certificates.count * FINGERPRINT_LEN ) );
 118 }
 119
 120 /** Root certificate initialiser */
 121 struct init_fn rootcert_init_fn __init_fn ( INIT_LATE ) = {
 122         .initialise = rootcert_init,
 123 };