[openssh-commits] [openssh] 04/15: upstream: when ordering the hostkey algorithms to request from a

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commit 05a651400da6fbe12296c34e3d3bcf09f034fbbf
Author: djm at openbsd.org <djm at openbsd.org>
Date:   Wed May 13 09:52:41 2020 +0000

    upstream: when ordering the hostkey algorithms to request from a
    
    server, prefer certificate types if the known_hosts files contain a key
    marked as a @cert-authority; bz#3157 ok markus@
    
    OpenBSD-Commit-ID: 8f194573e5bb7c01b69bbfaabc68f27c9fa5e0db
---
 hostfile.c    | 14 +++++++++++++-
 hostfile.h    |  3 ++-
 sshconnect2.c | 20 ++++++++++++++++----
 3 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/hostfile.c b/hostfile.c
index a4a35597..a91dbbd9 100644
--- a/hostfile.c
+++ b/hostfile.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: hostfile.c,v 1.79 2020/03/06 18:25:12 markus Exp $ */
+/* $OpenBSD: hostfile.c,v 1.80 2020/05/13 09:52:41 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo at cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -406,6 +406,18 @@ lookup_key_in_hostkeys_by_type(struct hostkeys *hostkeys, int keytype,
 	    found) == HOST_FOUND);
 }
 
+int
+lookup_marker_in_hostkeys(struct hostkeys *hostkeys, int want_marker)
+{
+	u_int i;
+
+	for (i = 0; i < hostkeys->num_entries; i++) {
+		if (hostkeys->entries[i].marker == (HostkeyMarker)want_marker)
+			return 1;
+	}
+	return 0;
+}
+
 static int
 write_host_entry(FILE *f, const char *host, const char *ip,
     const struct sshkey *key, int store_hash)
diff --git a/hostfile.h b/hostfile.h
index bd210437..49fcbb7e 100644
--- a/hostfile.h
+++ b/hostfile.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: hostfile.h,v 1.24 2015/02/16 22:08:57 djm Exp $ */
+/* $OpenBSD: hostfile.h,v 1.25 2020/05/13 09:52:41 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo at cs.hut.fi>
@@ -39,6 +39,7 @@ HostStatus check_key_in_hostkeys(struct hostkeys *, struct sshkey *,
     const struct hostkey_entry **);
 int	 lookup_key_in_hostkeys_by_type(struct hostkeys *, int,
     const struct hostkey_entry **);
+int	 lookup_marker_in_hostkeys(struct hostkeys *, int);
 
 int	 hostfile_read_key(char **, u_int *, struct sshkey *);
 int	 add_host_to_hostfile(const char *, const char *,
diff --git a/sshconnect2.c b/sshconnect2.c
index 1a6545ed..08b4f855 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect2.c,v 1.321 2020/04/17 03:38:47 djm Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.322 2020/05/13 09:52:41 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
@@ -135,11 +135,23 @@ order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
 	while ((alg = strsep(&avail, ",")) && *alg != '\0') {
 		if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
 			fatal("%s: unknown alg %s", __func__, alg);
+		/*
+		 * If we have a @cert-authority marker in known_hosts then
+		 * prefer all certificate algorithms.
+		 */
+		if (sshkey_type_is_cert(ktype) &&
+		    lookup_marker_in_hostkeys(hostkeys, MRK_CA)) {
+			ALG_APPEND(first, alg);
+			continue;
+		}
+		/* If the key appears in known_hosts then prefer it */
 		if (lookup_key_in_hostkeys_by_type(hostkeys,
-		    sshkey_type_plain(ktype), NULL))
+		    sshkey_type_plain(ktype), NULL)) {
 			ALG_APPEND(first, alg);
-		else
-			ALG_APPEND(last, alg);
+			continue;
+		}
+		/* Otherwise, put it last */
+		ALG_APPEND(last, alg);
 	}
 #undef ALG_APPEND
 	xasprintf(&ret, "%s%s%s", first,

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