From f382c87d3cc301abe6c3670f70bb79b6915c2e91 Mon Sep 17 00:00:00 2001 From: simon Date: Tue, 11 Jan 2005 10:37:55 +0000 Subject: [PATCH] Servers announcing themselves as `Sun_SSH_1.0' apparently cannot deal with rekeys at all: they totally ignore mid-session KEXINIT sent by the client. Hence, a new bug entry so we don't try it. git-svn-id: svn://svn.tartarus.org/sgt/putty@5092 cda61777-01e9-0310-a592-d414129be87e --- config.c | 3 +++ doc/config.but | 18 +++++++++++++++++ putty.h | 2 +- settings.c | 1 + ssh.c | 60 ++++++++++++++++++++++++++++++++++++++++--------------- windows/winhelp.h | 1 + 6 files changed, 68 insertions(+), 17 deletions(-) diff --git a/config.c b/config.c index a685ed2f..2e3822ac 100644 --- a/config.c +++ b/config.c @@ -1839,6 +1839,9 @@ void setup_config_box(struct controlbox *b, struct sesslist *sesslist, ctrl_droplist(s, "Misuses the session ID in PK auth", 'n', 20, HELPCTX(ssh_bugs_pksessid2), sshbug_handler, I(offsetof(Config,sshbug_pksessid2))); + ctrl_droplist(s, "Ignores key re-exchange completely", 'k', 20, + HELPCTX(ssh_bugs_rekey2), + sshbug_handler, I(offsetof(Config,sshbug_rekey2))); } } } diff --git a/doc/config.but b/doc/config.but index c59881e7..dcbce98c 100644 --- a/doc/config.but +++ b/doc/config.but @@ -2662,6 +2662,24 @@ SSH2 public-key authentication will fail. This is an SSH2-specific bug. +\S{config-ssh-bug-rekey} \q{Ignores key re-exchange completely} + +\cfg{winhelp-topic}{ssh.bugs.rekey2} + +Some very old SSH servers cannot cope with repeat key exchange at +all, and will ignore attempts by the client to start one. Since +PuTTY pauses the session while performing a repeat key exchange, the +effect of this would be to cause the session to hang after an hour +(unless you have your rekey timeout set differently; see +\k{config-ssh-kex-rekey} for more about rekeys). + +If this bug is detected, PuTTY will never initiate a repeat key +exchange. If this bug is enabled when talking to a correct server, +the session should still function, but may be less secure than you +would expect. + +This is an SSH2-specific bug. + \H{config-file} Storing configuration in a file PuTTY does not currently support storing its configuration in a file diff --git a/putty.h b/putty.h index 6f62afef..7686e6b2 100644 --- a/putty.h +++ b/putty.h @@ -540,7 +540,7 @@ struct config_tag { /* SSH bug compatibility modes */ int sshbug_ignore1, sshbug_plainpw1, sshbug_rsa1, sshbug_hmac2, sshbug_derivekey2, sshbug_rsapad2, - sshbug_pksessid2; + sshbug_pksessid2, sshbug_rekey2; /* Options for pterm. Should split out into platform-dependent part. */ int stamp_utmp; int login_shell; diff --git a/settings.c b/settings.c index eaae3436..aa234fe6 100644 --- a/settings.c +++ b/settings.c @@ -719,6 +719,7 @@ void load_open_settings(void *sesskey, int do_host, Config *cfg) gppi(sesskey, "BugDeriveKey2", 0, &i); cfg->sshbug_derivekey2 = 2-i; gppi(sesskey, "BugRSAPad2", 0, &i); cfg->sshbug_rsapad2 = 2-i; gppi(sesskey, "BugPKSessID2", 0, &i); cfg->sshbug_pksessid2 = 2-i; + gppi(sesskey, "BugRekey2", 0, &i); cfg->sshbug_rekey2 = 2-i; gppi(sesskey, "StampUtmp", 1, &cfg->stamp_utmp); gppi(sesskey, "LoginShell", 1, &cfg->login_shell); gppi(sesskey, "ScrollbarOnLeft", 0, &cfg->scrollbar_on_left); diff --git a/ssh.c b/ssh.c index 3ca48c5d..f4b61542 100644 --- a/ssh.c +++ b/ssh.c @@ -163,7 +163,7 @@ static const char *const ssh2_disconnect_reasons[] = { #define BUG_CHOKES_ON_RSA 8 #define BUG_SSH2_RSA_PADDING 16 #define BUG_SSH2_DERIVEKEY 32 -/* 64 was BUG_SSH2_DH_GEX, now spare */ +#define BUG_SSH2_REKEY 64 #define BUG_SSH2_PK_SESSIONID 128 #define translate(x) if (type == x) return #x @@ -1739,8 +1739,7 @@ static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt) if (!ssh->kex_in_progress && ssh->max_data_size != 0 && ssh->outgoing_data_size > ssh->max_data_size) - do_ssh2_transport(ssh, "Initiating key re-exchange " - "(too much data sent)", -1, NULL); + do_ssh2_transport(ssh, "too much data sent", -1, NULL); ssh_free_packet(pkt); } @@ -1830,8 +1829,7 @@ static void ssh_pkt_defersend(Ssh ssh) if (!ssh->kex_in_progress && ssh->max_data_size != 0 && ssh->outgoing_data_size > ssh->max_data_size) - do_ssh2_transport(ssh, "Initiating key re-exchange " - "(too much data sent)", -1, NULL); + do_ssh2_transport(ssh, "too much data sent", -1, NULL); ssh->deferred_data_size = 0; } @@ -2138,6 +2136,16 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring) ssh->remote_bugs |= BUG_SSH2_PK_SESSIONID; logevent("We believe remote version has SSH2 public-key-session-ID bug"); } + + if (ssh->cfg.sshbug_rekey2 == FORCE_ON || + (ssh->cfg.sshbug_rekey2 == AUTO && + wc_match("Sun_SSH_1.0", imp))) { + /* + * These versions have the SSH2 ignore-rekey bug. + */ + ssh->remote_bugs |= BUG_SSH2_REKEY; + logevent("We believe remote version has SSH2 ignore-rekey bug"); + } } /* @@ -5307,12 +5315,35 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, */ while (!((pktin && pktin->type == SSH2_MSG_KEXINIT) || (!pktin && inlen == -1))) { + wait_for_rekey: crReturn(1); } if (pktin) { logevent("Server initiated key re-exchange"); } else { - logevent((char *)in); + /* + * Special case: if the server bug is set that doesn't + * allow rekeying, we give a different log message and + * continue waiting. (If such a server _initiates_ a rekey, + * we process it anyway!) + */ + if ((ssh->remote_bugs & BUG_SSH2_REKEY)) { + logeventf(ssh, "Server bug prevents key re-exchange (%s)", + (char *)in); + /* Reset the counters, so that at least this message doesn't + * hit the event log _too_ often. */ + ssh->outgoing_data_size = 0; + ssh->incoming_data_size = 0; + if (ssh->cfg.ssh_rekey_time != 0) { + ssh->next_rekey = + schedule_timer(ssh->cfg.ssh_rekey_time*60*TICKSPERSEC, + ssh2_timer, ssh); + } + goto wait_for_rekey; /* this is utterly horrid */ + } else { + logeventf(ssh, "Initiating key re-exchange (%s)", (char *)in); + logevent((char *)in); + } } goto begin_key_exchange; @@ -7286,8 +7317,7 @@ static void ssh2_timer(void *ctx, long now) if (!ssh->kex_in_progress && ssh->cfg.ssh_rekey_time != 0 && now - ssh->next_rekey >= 0) { - do_ssh2_transport(ssh, "Initiating key re-exchange (timeout)", - -1, NULL); + do_ssh2_transport(ssh, "timeout", -1, NULL); } } @@ -7302,8 +7332,7 @@ static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen, if (!ssh->kex_in_progress && ssh->max_data_size != 0 && ssh->incoming_data_size > ssh->max_data_size) - do_ssh2_transport(ssh, "Initiating key re-exchange " - "(too much data received)", -1, NULL); + do_ssh2_transport(ssh, "too much data received", -1, NULL); } if (pktin && ssh->packet_dispatch[pktin->type]) { @@ -7544,7 +7573,7 @@ static void ssh_reconfig(void *handle, Config *cfg) long now = GETTICKCOUNT(); if (new_next - now < 0) { - rekeying = "Initiating key re-exchange (timeout shortened)"; + rekeying = "timeout shortened"; } else { ssh->next_rekey = schedule_timer(new_next - now, ssh2_timer, ssh); } @@ -7556,18 +7585,18 @@ static void ssh_reconfig(void *handle, Config *cfg) ssh->max_data_size != 0) { if (ssh->outgoing_data_size > ssh->max_data_size || ssh->incoming_data_size > ssh->max_data_size) - rekeying = "Initiating key re-exchange (data limit lowered)"; + rekeying = "data limit lowered"; } if (ssh->cfg.compression != cfg->compression) { - rekeying = "Initiating key re-exchange (compression setting changed)"; + rekeying = "compression setting changed"; rekey_mandatory = TRUE; } if (ssh->cfg.ssh2_des_cbc != cfg->ssh2_des_cbc || memcmp(ssh->cfg.ssh_cipherlist, cfg->ssh_cipherlist, sizeof(ssh->cfg.ssh_cipherlist))) { - rekeying = "Initiating key re-exchange (cipher settings changed)"; + rekeying = "cipher settings changed"; rekey_mandatory = TRUE; } @@ -7780,8 +7809,7 @@ static void ssh_special(void *handle, Telnet_Special code) } } else if (code == TS_REKEY) { if (!ssh->kex_in_progress && ssh->version == 2) { - do_ssh2_transport(ssh, "Initiating key re-exchange at" - " user request", -1, NULL); + do_ssh2_transport(ssh, "at user request", -1, NULL); } } else if (code == TS_BRK) { if (ssh->state == SSH_STATE_CLOSED diff --git a/windows/winhelp.h b/windows/winhelp.h index 743852bc..30b110bf 100644 --- a/windows/winhelp.h +++ b/windows/winhelp.h @@ -121,3 +121,4 @@ #define WINHELP_CTX_ssh_bugs_derivekey2 "ssh.bugs.derivekey2" #define WINHELP_CTX_ssh_bugs_rsapad2 "ssh.bugs.rsapad2" #define WINHELP_CTX_ssh_bugs_pksessid2 "ssh.bugs.pksessid2" +#define WINHELP_CTX_ssh_bugs_rekey2 "ssh.bugs.rekey2" -- 2.11.0