From: tb <tb@openbsd.org>
Date: Mon, 3 Jun 2024 12:58:39 +0000 (+0000)
Subject: Rework SIA handling to be less incorrect
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=c5305b1da563242eb69f257b4d535147d939611b;p=openbsd

Rework SIA handling to be less incorrect

Currently we would only accept rsync URIs in caRepository and rpkiManifest.
This is wrong. The specification requires at least one rsync URI to be
resent, but allows for other URI types, ordered by descending CA preference.
With this diff we will still only respect the first rsync address, but we
will no longer reject certificates listing other URIs. Make the warning
conditional on verbose mode.

Also make it clearer that sbgp_sia() (which is poorly named) is for CA
certs while x509_get_sia() is for EE certs.

input/ok claudio
---

diff --git a/usr.sbin/rpki-client/cert.c b/usr.sbin/rpki-client/cert.c
index d180c68176e..625f0479301 100644
--- a/usr.sbin/rpki-client/cert.c
+++ b/usr.sbin/rpki-client/cert.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cert.c,v 1.132 2024/05/31 02:45:15 tb Exp $ */
+/*	$OpenBSD: cert.c,v 1.133 2024/06/03 12:58:39 tb Exp $ */
 /*
  * Copyright (c) 2022 Theo Buehler <tb@openbsd.org>
  * Copyright (c) 2021 Job Snijders <job@openbsd.org>
@@ -495,7 +495,8 @@ sbgp_ipaddrblk(const char *fn, struct cert *cert, X509_EXTENSION *ext)
 }
 
 /*
- * Parse "Subject Information Access" extension, RFC 6487 4.8.8.
+ * Parse "Subject Information Access" extension for a CA cert,
+ * RFC 6487, section 4.8.8.1 and RFC 8182, section 3.2.
  * Returns zero on failure, non-zero on success.
  */
 static int
@@ -505,8 +506,11 @@ sbgp_sia(const char *fn, struct cert *cert, X509_EXTENSION *ext)
 	ACCESS_DESCRIPTION	*ad;
 	ASN1_OBJECT		*oid;
 	const char		*mftfilename;
+	char			*carepo = NULL, *rpkimft = NULL;
 	int			 i, rc = 0;
 
+	assert(cert->repo == NULL && cert->mft == NULL && cert->notify == NULL);
+
 	if (X509_EXTENSION_get_critical(ext)) {
 		warnx("%s: RFC 6487 section 4.8.8: SIA: "
 		    "extension not non-critical", fn);
@@ -525,13 +529,35 @@ sbgp_sia(const char *fn, struct cert *cert, X509_EXTENSION *ext)
 		oid = ad->method;
 
 		if (OBJ_cmp(oid, carepo_oid) == 0) {
-			if (!x509_location(fn, "SIA: caRepository",
-			    RSYNC_PROTO, ad->location, &cert->repo))
+			if (!x509_location(fn, "SIA: caRepository", NULL,
+			    ad->location, &carepo))
 				goto out;
+			if (cert->repo == NULL && strncasecmp(carepo,
+			    RSYNC_PROTO, RSYNC_PROTO_LEN) == 0) {
+				cert->repo = carepo;
+				carepo = NULL;
+				continue;
+			}
+			if (verbose)
+				warnx("%s: RFC 6487 section 4.8.8: SIA: "
+				    "ignoring location %s", fn, carepo);
+			free(carepo);
+			carepo = NULL;
 		} else if (OBJ_cmp(oid, manifest_oid) == 0) {
-			if (!x509_location(fn, "SIA: rpkiManifest",
-			    RSYNC_PROTO, ad->location, &cert->mft))
+			if (!x509_location(fn, "SIA: rpkiManifest", NULL,
+			    ad->location, &rpkimft))
 				goto out;
+			if (cert->mft == NULL && strncasecmp(rpkimft,
+			    RSYNC_PROTO, RSYNC_PROTO_LEN) == 0) {
+				cert->mft = rpkimft;
+				rpkimft = NULL;
+				continue;
+			}
+			if (verbose)
+				warnx("%s: RFC 6487 section 4.8.8: SIA: "
+				    "ignoring location %s", fn, rpkimft);
+			free(rpkimft);
+			rpkimft = NULL;
 		} else if (OBJ_cmp(oid, notify_oid) == 0) {
 			if (!x509_location(fn, "SIA: rpkiNotify",
 			    HTTPS_PROTO, ad->location, &cert->notify))
@@ -844,6 +870,10 @@ cert_parse_pre(const char *fn, const unsigned char *der, size_t len)
 		case NID_sinfo_access:
 			if (sia++ > 0)
 				goto dup;
+			/*
+			 * This will fail for BGPsec certs, but they must omit
+			 * this extension anyway (RFC 8209, section 3.1.3.3).
+			 */
 			if (!sbgp_sia(fn, cert, ext))
 				goto out;
 			break;
diff --git a/usr.sbin/rpki-client/x509.c b/usr.sbin/rpki-client/x509.c
index 0b28d6ee451..1aad594f318 100644
--- a/usr.sbin/rpki-client/x509.c
+++ b/usr.sbin/rpki-client/x509.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: x509.c,v 1.90 2024/05/31 11:27:34 tb Exp $ */
+/*	$OpenBSD: x509.c,v 1.91 2024/06/03 12:58:39 tb Exp $ */
 /*
  * Copyright (c) 2022 Theo Buehler <tb@openbsd.org>
  * Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
@@ -467,8 +467,8 @@ out:
 }
 
 /*
- * Parse the Subject Information Access (SIA) extension
- * See RFC 6487, section 4.8.8 for details.
+ * Parse the Subject Information Access (SIA) extension for an EE cert.
+ * See RFC 6487, section 4.8.8.2 for details.
  * Returns NULL on failure, on success returns the SIA signedObject URI
  * (which has to be freed after use).
  */