iPXE
rootcert.c
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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 */
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  static int initialised;
97  void *external = NULL;
98  int len;
99 
100  /* Allow trusted root certificates to be overridden only if
101  * not explicitly specified at build time.
102  */
103  if ( ALLOW_TRUST_OVERRIDE && ( ! initialised ) ) {
104 
105  /* Fetch copy of "trust" setting, if it exists. This
106  * memory will never be freed.
107  */
108  if ( ( len = fetch_raw_setting_copy ( NULL, &trust_setting,
109  &external ) ) >= 0 ) {
110  root_certificates.fingerprints = external;
112  }
113 
114  /* Prevent subsequent modifications */
115  initialised = 1;
116  }
117 
118  DBGC ( &root_certificates, "ROOTCERT using %d %s certificate(s):\n",
119  root_certificates.count, ( external ? "external" : "built-in" ));
122 }
123 
124 /** Root certificate initialiser */
125 struct startup_fn rootcert_startup_fn __startup_fn ( STARTUP_LATE ) = {
126  .name = "rootcert",
127  .startup = rootcert_init,
128 };
Dynamic Host Configuration Protocol.
#define TRUSTED
Definition: rootcert.c:53
static struct setting trust_setting __setting(SETTING_CRYPTO, trust)
Root certificate fingerprint setting.
int fetch_raw_setting_copy(struct settings *settings, const struct setting *setting, void **data)
Fetch value of setting.
Definition: settings.c:820
static void rootcert_init(void)
Initialise root certificate.
Definition: rootcert.c:95
struct x509_root root_certificates
Root certificates.
Definition: rootcert.c:73
#define DBGC(...)
Definition: compiler.h:505
#define DHCP_EB_TRUST
Trusted root certficate fingerprints.
Definition: dhcp.h:392
Cryptographic API.
const char * name
Definition: init.h:42
#define STARTUP_LATE
Late startup.
Definition: init.h:64
const char * name
Name.
Definition: settings.h:28
A startup/shutdown function.
Definition: init.h:41
#define DBGC_HDA(...)
Definition: compiler.h:506
struct digest_algorithm * digest
Fingerprint digest algorithm.
Definition: x509.h:346
#define ALLOW_TRUST_OVERRIDE
Definition: rootcert.c:48
struct startup_fn rootcert_startup_fn __startup_fn(STARTUP_LATE)
Root certificate initialiser.
Configuration settings.
#define FINGERPRINT_LEN
Length of a root certificate fingerprint.
Definition: rootcert.c:42
unsigned char uint8_t
Definition: stdint.h:10
X.509 certificates.
A setting.
Definition: settings.h:23
An X.509 root certificate store.
Definition: x509.h:344
struct digest_algorithm sha256_algorithm
SHA-256 algorithm.
Definition: sha256.c:265
uint32_t len
Length.
Definition: ena.h:14
unsigned int count
Number of certificates.
Definition: x509.h:348
Root certificate store.
#define SETTING_CRYPTO
Cryptography settings.
Definition: settings.h:79
const void * fingerprints
Certificate fingerprints.
Definition: x509.h:350
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)
static const uint8_t fingerprints[]
Root certificate fingerprints.
Definition: rootcert.c:62
SHA-256 algorithm.
#define NULL
NULL pointer (VOID *)
Definition: Base.h:362