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From 5e021158aa22cc64da4fca1618ee0bfd2d031049 Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Fri, 16 Nov 2018 02:43:56 +0000
Subject: upstream: fix bug in HostbasedAcceptedKeyTypes and
PubkeyAcceptedKeyTypes options. If only RSA-SHA2 siganture types were
specified, then authentication would always fail for RSA keys as the monitor
checks only the base key (not the signature algorithm) type against
*AcceptedKeyTypes. bz#2746; reported by Jakub Jelen; ok dtucker
OpenBSD-Commit-ID: 117bc3dc54578dbdb515a1d3732988cb5b00461b
Origin: upstream, https://anongit.mindrot.org/openssh.git/commit/?id=cd9467318b56e6e93ff9575c906ff8350af9b8a2
Last-Update: 2019-02-28
Patch-Name: fix-key-type-check.patch
---
monitor.c | 39 ++++++++++++++++++++++++++++++++++-----
1 file changed, 34 insertions(+), 5 deletions(-)
diff --git a/monitor.c b/monitor.c
index 08fddabd7..037d6d333 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.186 2018/07/20 03:46:34 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.188 2018/11/16 02:43:56 djm Exp $ */
/*
* Copyright 2002 Niels Provos <provos@citi.umich.edu>
* Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -892,6 +892,35 @@ mm_answer_authrole(int sock, struct sshbuf *m)
return (0);
}
+/*
+ * Check that the key type appears in the supplied pattern list, ignoring
+ * mismatches in the signature algorithm. (Signature algorithm checks are
+ * performed in the unprivileged authentication code).
+ * Returns 1 on success, 0 otherwise.
+ */
+static int
+key_base_type_match(const char *method, const struct sshkey *key,
+ const char *list)
+{
+ char *s, *l, *ol = xstrdup(list);
+ int found = 0;
+
+ l = ol;
+ for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) {
+ if (sshkey_type_from_name(s) == key->type) {
+ found = 1;
+ break;
+ }
+ }
+ if (!found) {
+ error("%s key type %s is not in permitted list %s", method,
+ sshkey_ssh_name(key), list);
+ }
+
+ free(ol);
+ return found;
+}
+
int
mm_answer_authpassword(int sock, struct sshbuf *m)
{
@@ -1197,8 +1226,8 @@ mm_answer_keyallowed(int sock, struct sshbuf *m)
break;
if (auth2_key_already_used(authctxt, key))
break;
- if (match_pattern_list(sshkey_ssh_name(key),
- options.pubkey_key_types, 0) != 1)
+ if (!key_base_type_match(auth_method, key,
+ options.pubkey_key_types))
break;
allowed = user_key_allowed(ssh, authctxt->pw, key,
pubkey_auth_attempt, &opts);
@@ -1209,8 +1238,8 @@ mm_answer_keyallowed(int sock, struct sshbuf *m)
break;
if (auth2_key_already_used(authctxt, key))
break;
- if (match_pattern_list(sshkey_ssh_name(key),
- options.hostbased_key_types, 0) != 1)
+ if (!key_base_type_match(auth_method, key,
+ options.hostbased_key_types))
break;
allowed = hostbased_key_allowed(authctxt->pw,
cuser, chost, key);
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