From 2e828220579e3ada74ed0613871ec6ec61d669ba Mon Sep 17 00:00:00 2001
From: Ed Maste <emaste@FreeBSD.org>
Date: Mon, 6 Feb 2023 11:45:52 -0500
Subject: [PATCH] ssh: Be more paranoid with host/domain names coming from the

never write a name with bad characters to a known_hosts file.

replace recently-added valid_domain() check for hostnames going to
known_hosts with a more relaxed check for bad characters.

Obtained from:	OpenSSH-portable commit 445363433ba2
Obtained from:	OpenSSH-portable commit 3cae9f92a318
Sponsored by:	The FreeBSD Foundation
---
 crypto/openssh/ssh.c        |  8 ++++++--
 crypto/openssh/sshconnect.c | 15 +++++++++++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/crypto/openssh/ssh.c b/crypto/openssh/ssh.c
index 9b5ec2dfd14b..b7dd6ca8bff4 100644
--- a/crypto/openssh/ssh.c
+++ b/crypto/openssh/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.576 2022/09/17 10:33:18 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.579 2022/10/24 22:43:36 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -251,6 +251,7 @@ static struct addrinfo *
 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
 {
 	char strport[NI_MAXSERV];
+	const char *errstr = NULL;
 	struct addrinfo hints, *res;
 	int gaierr;
 	LogLevel loglevel = SYSLOG_LEVEL_DEBUG1;
@@ -276,7 +277,10 @@ resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
 		return NULL;
 	}
 	if (cname != NULL && res->ai_canonname != NULL) {
-		if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
+		if (!valid_domain(res->ai_canonname, 0, &errstr)) {
+			error("ignoring bad CNAME \"%s\" for host \"%s\": %s",
+			    res->ai_canonname, name, errstr);
+		} else if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
 			error_f("host \"%s\" cname \"%s\" too long (max %lu)",
 			    name,  res->ai_canonname, (u_long)clen);
 			if (clen > 0)
diff --git a/crypto/openssh/sshconnect.c b/crypto/openssh/sshconnect.c
index 7b3f260ee788..0fca52b220ff 100644
--- a/crypto/openssh/sshconnect.c
+++ b/crypto/openssh/sshconnect.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.c,v 1.358 2022/08/26 08:16:27 djm Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.360 2022/11/03 21:59:20 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -935,7 +935,7 @@ check_host_key(char *hostname, const struct ssh_conn_info *cinfo,
 	char *ip = NULL, *host = NULL;
 	char hostline[1000], *hostp, *fp, *ra;
 	char msg[1024];
-	const char *type, *fail_reason;
+	const char *type, *fail_reason = NULL;
 	const struct hostkey_entry *host_found = NULL, *ip_found = NULL;
 	int len, cancelled_forwarding = 0, confirmed;
 	int local = sockaddr_is_local(hostaddr);
@@ -960,6 +960,17 @@ check_host_key(char *hostname, const struct ssh_conn_info *cinfo,
 		return 0;
 	}
 
+	/*
+	 * Don't ever try to write an invalid name to a known hosts file.
+	 * Note: do this before get_hostfile_hostname_ipaddr() to catch
+	 * '[' or ']' in the name before they are added.
+	 */
+	if (strcspn(hostname, "@?*#[]|'\'\"\\") != strlen(hostname)) {
+		debug_f("invalid hostname \"%s\"; will not record: %s",
+		    hostname, fail_reason);
+		readonly = RDONLY;
+	}
+
 	/*
 	 * Prepare the hostname and address strings used for hostkey lookup.
 	 * In some cases, these will have a port number appended.