[crypto] Generalise X.509 cache to a full certificate store

Expand the concept of the X.509 cache to provide the functionality of
a certificate store.  Certificates in the store will be automatically
used to complete certificate chains where applicable.

The certificate store may be prepopulated at build time using the
CERT=... build command line option.  For example:

  make bin/ipxe.usb CERT=mycert1.crt,mycert2.crt

Certificates within the certificate store are not implicitly trusted;
the trust list is specified using TRUST=... as before.  For example:

  make bin/ipxe.usb CERT=root.crt TRUST=root.crt

This can be used to embed the full trusted root certificate within the
iPXE binary, which is potentially useful in an HTTPS-only environment
in which there is no HTTP server from which to automatically download
cross-signed certificates or other certificate chain fragments.

This usage of CERT= extends the existing use of CERT= to specify the
client certificate.  The client certificate is now identified
automatically by checking for a match against the private key.  For
example:

  make bin/ipxe.usb CERT=root.crt,client.crt TRUST=root.crt KEY=client.key

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 118 insertions, 0 deletions

diff --git a/src/crypto/privkey.c b/src/crypto/privkey.c
new file mode 100644
index 00000000..e010649c
--- /dev/null
+++ b/src/crypto/privkey.c
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ipxe/dhcp.h>
+#include <ipxe/settings.h>
+#include <ipxe/x509.h>
+#include <ipxe/privkey.h>
+
+/** @file
+ *
+ * Private key
+ *
+ * Life would in theory be easier if we could use a single file to
+ * hold both the certificate and corresponding private key.
+ * Unfortunately, the only common format which supports this is
+ * PKCS#12 (aka PFX), which is too ugly to be allowed anywhere near my
+ * codebase.  See, for reference and amusement:
+ *
+ *    http://www.cs.auckland.ac.nz/~pgut001/pubs/pfx.html
+ */
+
+/* Allow private key to be overridden if not explicitly specified */
+#ifdef PRIVATE_KEY
+#define ALLOW_KEY_OVERRIDE 0
+#else
+#define ALLOW_KEY_OVERRIDE 1
+#endif
+
+/* Raw private key data */
+extern char private_key_data[];
+extern char private_key_len[];
+__asm__ ( ".section \".rodata\", \"a\", @progbits\n\t"
+	  "\nprivate_key_data:\n\t"
+#ifdef PRIVATE_KEY
+	  ".incbin \"" PRIVATE_KEY "\"\n\t"
+#endif /* PRIVATE_KEY */
+	  ".size private_key_data, ( . - private_key_data )\n\t"
+	  ".equ private_key_len, ( . - private_key_data )\n\t"
+	  ".previous\n\t" );
+
+/** Private key */
+struct asn1_cursor private_key = {
+	.data = private_key_data,
+	.len = ( ( size_t ) private_key_len ),
+};
+
+/** Private key setting */
+static struct setting privkey_setting __setting ( SETTING_CRYPTO, privkey ) = {
+	.name = "privkey",
+	.description = "Private key",
+	.tag = DHCP_EB_KEY,
+	.type = &setting_type_hex,
+};
+
+/**
+ * Apply private key configuration settings
+ *
+ * @ret rc		Return status code
+ */
+static int privkey_apply_settings ( void ) {
+	static void *key_data = NULL;
+	int len;
+
+	/* Allow private key to be overridden only if not explicitly
+	 * specified at build time.
+	 */
+	if ( ALLOW_KEY_OVERRIDE ) {
+
+		/* Restore default private key */
+		private_key.data = private_key_data;
+		private_key.len = ( ( size_t ) private_key_len );
+
+		/* Fetch new private key, if any */
+		free ( key_data );
+		if ( ( len = fetch_raw_setting_copy ( NULL, &privkey_setting,
+						      &key_data ) ) >= 0 ) {
+			private_key.data = key_data;
+			private_key.len = len;
+		}
+	}
+
+	/* Debug */
+	if ( private_key.len ) {
+		DBGC ( &private_key, "PRIVKEY using %s private key:\n",
+		       ( key_data ? "external" : "built-in" ) );
+		DBGC_HDA ( &private_key, 0, private_key.data, private_key.len );
+	} else {
+		DBGC ( &private_key, "PRIVKEY has no private key\n" );
+	}
+
+	return 0;
+}
+
+/** Private key settings applicator */
+struct settings_applicator privkey_applicator __settings_applicator = {
+	.apply = privkey_apply_settings,
+};