upstream commit

include the peer's offer when logging a failure to
 negotiate a mutual set of algorithms (kex, pubkey, ciphers, etc.) ok markus@

Upstream-ID: bbb8caabf5c01790bb845f5ce135565248d7c796

diff --git a/kex.c b/kex.c
index dbc55ef7ee0878874860835874a41c51edeeb039..5e8b51394222db5c4db0a327a1ff2ec3bc2e996c 100644 (file)
--- a/kex.c
+++ b/kex.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.c,v 1.106 2015/04/17 13:25:52 djm Exp $ */
+/* $OpenBSD: kex.c,v 1.107 2015/07/29 04:43:06 djm Exp $ */
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *
@@ -448,6 +448,7 @@ kex_free(struct kex *kex)
        free(kex->session_id);
        free(kex->client_version_string);
        free(kex->server_version_string);
+       free(kex->failed_choice);
        free(kex);
 }
 
@@ -626,17 +627,26 @@ kex_choose_conf(struct ssh *ssh)
                nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
                ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
                if ((r = choose_enc(&newkeys->enc, cprop[nenc],
-                   sprop[nenc])) != 0)
+                   sprop[nenc])) != 0) {
+                       kex->failed_choice = peer[nenc];
+                       peer[nenc] = NULL;
                        goto out;
+               }
                authlen = cipher_authlen(newkeys->enc.cipher);
                /* ignore mac for authenticated encryption */
                if (authlen == 0 &&
                    (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
-                   sprop[nmac])) != 0)
+                   sprop[nmac])) != 0) {
+                       kex->failed_choice = peer[nmac];
+                       peer[nmac] = NULL;
                        goto out;
+               }
                if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
-                   sprop[ncomp])) != 0)
+                   sprop[ncomp])) != 0) {
+                       kex->failed_choice = peer[ncomp];
+                       peer[ncomp] = NULL;
                        goto out;
+               }
                debug("kex: %s %s %s %s",
                    ctos ? "client->server" : "server->client",
                    newkeys->enc.name,
@@ -644,10 +654,17 @@ kex_choose_conf(struct ssh *ssh)
                    newkeys->comp.name);
        }
        if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
-           sprop[PROPOSAL_KEX_ALGS])) != 0 ||
-           (r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
-           sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0)
+           sprop[PROPOSAL_KEX_ALGS])) != 0) {
+               kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
+               peer[PROPOSAL_KEX_ALGS] = NULL;
                goto out;
+       }
+       if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
+           sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
+               kex->failed_choice = cprop[PROPOSAL_SERVER_HOST_KEY_ALGS];
+               cprop[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
+               goto out;
+       }
        need = dh_need = 0;
        for (mode = 0; mode < MODE_MAX; mode++) {
                newkeys = kex->newkeys[mode];

diff --git a/kex.h b/kex.h
index f70b81fc143e581efc9713ab0d8c4dbd376d07db..fea5a75dd6972268c05818e222468d76fb6a88a6 100644 (file)
--- a/kex.h
+++ b/kex.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: kex.h,v 1.71 2015/02/16 22:13:32 djm Exp $ */
+/* $OpenBSD: kex.h,v 1.72 2015/07/29 04:43:06 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -141,6 +141,7 @@ struct kex {
        int     ec_nid;
        char    *client_version_string;
        char    *server_version_string;
+       char    *failed_choice;
        int     (*verify_host_key)(struct sshkey *, struct ssh *);
        struct sshkey *(*load_host_public_key)(int, int, struct ssh *);
        struct sshkey *(*load_host_private_key)(int, int, struct ssh *);

diff --git a/packet.c b/packet.c
index a7727ef655cbe43eb8cf8a840cb3beda6cff992b..6008c2d946503768848da05060169f6038dfc48c 100644 (file)
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.212 2015/05/01 07:10:01 djm Exp $ */
+/* $OpenBSD: packet.c,v 1.213 2015/07/29 04:43:06 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1933,6 +1933,17 @@ sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
                        cleanup_exit(255);
                }
                /* FALLTHROUGH */
+       case SSH_ERR_NO_CIPHER_ALG_MATCH:
+       case SSH_ERR_NO_MAC_ALG_MATCH:
+       case SSH_ERR_NO_COMPRESS_ALG_MATCH:
+       case SSH_ERR_NO_KEX_ALG_MATCH:
+       case SSH_ERR_NO_HOSTKEY_ALG_MATCH:
+               if (ssh && ssh->kex && ssh->kex->failed_choice) {
+                       fatal("Unable to negotiate with %.200s: %s. "
+                           "Their offer: %s", ssh_remote_ipaddr(ssh),
+                           ssh_err(r), ssh->kex->failed_choice);
+               }
+               /* FALLTHROUGH */
        default:
                fatal("%s%sConnection to %.200s: %s",
                    tag != NULL ? tag : "", tag != NULL ? ": " : "",