[build] Inhibit spurious array bounds warning on some versions of gcc
[ipxe.git] / 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 .refcnt = REF_INIT ( ref_no_free ),
75 .digest = &sha256_algorithm,
76 .count = ( sizeof ( fingerprints ) / FINGERPRINT_LEN ),
77 .fingerprints = fingerprints,
78 };
79
80 /**
81 * Initialise root certificate
82 *
83 * The list of trusted root certificates can be specified at build
84 * time using the TRUST= build parameter. If no certificates are
85 * specified, then the default iPXE root CA certificate is trusted.
86 *
87 * If no certificates were explicitly specified, then we allow the
88 * list of trusted root certificate fingerprints to be overridden
89 * using the "trust" setting, but only at the point of iPXE
90 * initialisation. This prevents untrusted sources of settings
91 * (e.g. DHCP) from subverting the chain of trust, while allowing
92 * trustworthy sources (e.g. VMware GuestInfo or non-volatile stored
93 * options) to specify the trusted root certificate without requiring
94 * a rebuild.
95 */
96 static void rootcert_init ( void ) {
97 static int initialised;
98 void *external = NULL;
99 int len;
100
101 /* Allow trusted root certificates to be overridden only if
102 * not explicitly specified at build time.
103 */
104 if ( ALLOW_TRUST_OVERRIDE && ( ! initialised ) ) {
105
106 /* Fetch copy of "trust" setting, if it exists. This
107 * memory will never be freed.
108 */
109 if ( ( len = fetch_raw_setting_copy ( NULL, &trust_setting,
110 &external ) ) >= 0 ) {
111 root_certificates.fingerprints = external;
112 root_certificates.count = ( len / FINGERPRINT_LEN );
113 }
114
115 /* Prevent subsequent modifications */
116 initialised = 1;
117 }
118
119 DBGC ( &root_certificates, "ROOTCERT using %d %s certificate(s):\n",
120 root_certificates.count, ( external ? "external" : "built-in" ));
121 DBGC_HDA ( &root_certificates, 0, root_certificates.fingerprints,
122 ( root_certificates.count * FINGERPRINT_LEN ) );
123 }
124
125 /** Root certificate initialiser */
126 struct startup_fn rootcert_startup_fn __startup_fn ( STARTUP_LATE ) = {
127 .name = "rootcert",
128 .startup = rootcert_init,
129 };