Validate the session_id to be a real UUID.

RFC 8182 requires the session_id to be a version 4 random UUID (using
variant 1). Now checking the version and variant is currently disabled
because there is at least one CA with a session_id that is all random
and therefor the version check triggers there.
Joint work with job@. OK job@, tb@

5 files changed, 55 insertions, 8 deletions

diff --git a/usr.sbin/rpki-client/extern.h b/usr.sbin/rpki-client/extern.h
index 6bd5632fa3c..ed76f358463 100644
--- a/usr.sbin/rpki-client/extern.h
+++ b/usr.sbin/rpki-client/extern.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: extern.h,v 1.165 2022/12/28 21:30:18 jmc Exp $ */
+/*	$OpenBSD: extern.h,v 1.166 2023/01/04 14:22:43 claudio Exp $ */
 /*
  * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -659,6 +659,7 @@ int		 valid_rsc(const char *, struct cert *, struct rsc *);
 int		 valid_econtent_version(const char *, const ASN1_INTEGER *);
 int		 valid_aspa(const char *, struct cert *, struct aspa *);
 int		 valid_geofeed(const char *, struct cert *, struct geofeed *);
+int		 valid_uuid(const char *);
 
 /* Working with CMS. */
 unsigned char	*cms_parse_validate(X509 **, const char *,
diff --git a/usr.sbin/rpki-client/rrdp_delta.c b/usr.sbin/rpki-client/rrdp_delta.c
index 97b563daa9b..d8b12ae6d95 100644
--- a/usr.sbin/rpki-client/rrdp_delta.c
+++ b/usr.sbin/rpki-client/rrdp_delta.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rrdp_delta.c,v 1.8 2022/05/15 16:43:35 tb Exp $ */
+/*	$OpenBSD: rrdp_delta.c,v 1.9 2023/01/04 14:22:43 claudio Exp $ */
 /*
  * Copyright (c) 2020 Nils Fisher <nils_fisher@hotmail.com>
  * Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
@@ -77,7 +77,8 @@ start_delta_elem(struct delta_xml *dxml, const char **attr)
 			if (errstr == NULL)
 				continue;
 		}
-		if (strcmp("session_id", attr[i]) == 0) {
+		if (strcmp("session_id", attr[i]) == 0 &&
+		    valid_uuid(attr[i + 1])) {
 			dxml->session_id = xstrdup(attr[i + 1]);
 			continue;
 		}
diff --git a/usr.sbin/rpki-client/rrdp_notification.c b/usr.sbin/rpki-client/rrdp_notification.c
index 016385d7252..b135ecaf32c 100644
--- a/usr.sbin/rpki-client/rrdp_notification.c
+++ b/usr.sbin/rpki-client/rrdp_notification.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rrdp_notification.c,v 1.16 2022/06/16 16:09:56 claudio Exp $ */
+/*	$OpenBSD: rrdp_notification.c,v 1.17 2023/01/04 14:22:43 claudio Exp $ */
 /*
  * Copyright (c) 2020 Nils Fisher <nils_fisher@hotmail.com>
  * Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
@@ -125,7 +125,8 @@ start_notification_elem(struct notification_xml *nxml, const char **attr)
 			has_xmlns = 1;
 			continue;
 		}
-		if (strcmp("session_id", attr[i]) == 0) {
+		if (strcmp("session_id", attr[i]) == 0 &&
+		    valid_uuid(attr[i + 1])) {
 			nxml->session_id = xstrdup(attr[i + 1]);
 			continue;
 		}
diff --git a/usr.sbin/rpki-client/rrdp_snapshot.c b/usr.sbin/rpki-client/rrdp_snapshot.c
index 47423c12548..2d276423b49 100644
--- a/usr.sbin/rpki-client/rrdp_snapshot.c
+++ b/usr.sbin/rpki-client/rrdp_snapshot.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rrdp_snapshot.c,v 1.6 2022/02/03 18:19:32 claudio Exp $ */
+/*	$OpenBSD: rrdp_snapshot.c,v 1.7 2023/01/04 14:22:43 claudio Exp $ */
 /*
  * Copyright (c) 2020 Nils Fisher <nils_fisher@hotmail.com>
  * Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
@@ -69,7 +69,8 @@ start_snapshot_elem(struct snapshot_xml *sxml, const char **attr)
 			if (errstr == NULL)
 				continue;
 		}
-		if (strcmp("session_id", attr[i]) == 0) {
+		if (strcmp("session_id", attr[i]) == 0 &&
+		    valid_uuid(attr[i + 1])) {
 			sxml->session_id = xstrdup(attr[i + 1]);
 			continue;
 		}
diff --git a/usr.sbin/rpki-client/validate.c b/usr.sbin/rpki-client/validate.c
index f363dfa2c81..7183ffca59d 100644
--- a/usr.sbin/rpki-client/validate.c
+++ b/usr.sbin/rpki-client/validate.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: validate.c,v 1.51 2022/11/30 08:17:21 job Exp $ */
+/*	$OpenBSD: validate.c,v 1.52 2023/01/04 14:22:43 claudio Exp $ */
 /*
  * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -546,3 +546,46 @@ valid_geofeed(const char *fn, struct cert *cert, struct geofeed *g)
 
 	return 1;
 }
+
+/*
+ * Validate whether a given string is a valid UUID.
+ * Returns 1 if valid, 0 otherwise.
+ */
+int
+valid_uuid(const char *s)
+{
+	int n = 0;
+
+	while (1) {
+		switch (n) {
+		case 8:
+		case 13:
+		case 18:
+		case 23:
+			if (s[n] != '-')
+				return 0;
+			break;
+#ifdef NOTYET	/* World is not yet ready to enfoce UUID version and variant */
+		/* Check UUID is version 4 */
+		case 14:
+			if (s[n] != '4')
+				return 0;
+			break;
+		/* Check UUID variant is 1 */
+		case 19:
+			if (s[n] != '8' && s[n] != '9' && s[n] != 'a' &&
+			    s[n] != 'A' && s[n] != 'b' && s[n] != 'B')
+				return 0;
+			break;
+#endif
+		case 36:
+			return s[n] == '\0';
+		default:
+			if (!isxdigit((unsigned char)s[n]))
+				return 0;
+			break;
+		}
+		n++;
+	}
+}
+