From cf6ddb95b1f75d3cefc23ddc18a29293d912bf22 Mon Sep 17 00:00:00 2001 From: simon Date: Fri, 23 Apr 2010 18:32:15 +0000 Subject: [PATCH] New SSH bug flag, for 'can't handle SSH2_MSG_IGNORE'. Another user today reported an SSH2_MSG_UNIMPLEMENTED from a Cisco router which looks as if it was triggered by SSH2_MSG_IGNORE, so I'm experimentally putting this flag in. Currently must be manually enabled, though if it turns out to solve the user's problem then I'll probably add at least one version string... [Edited commit message: actually, I also committed in error a piece of experimental code as part of this checkin. Serve me right for not running 'svn diff' first.] git-svn-id: svn://svn.tartarus.org/sgt/putty@8926 cda61777-01e9-0310-a592-d414129be87e --- config.c | 3 +++ doc/config.but | 20 +++++++++++++++++--- putty.h | 4 +++- settings.c | 2 ++ ssh.c | 36 ++++++++++++++++++++++++++++-------- terminal.c | 25 +++++++++++++++++++++++++ windows/window.c | 4 ++++ 7 files changed, 82 insertions(+), 12 deletions(-) diff --git a/config.c b/config.c index 464a2415..bc48e271 100644 --- a/config.c +++ b/config.c @@ -2284,6 +2284,9 @@ void setup_config_box(struct controlbox *b, int midsession, ctrl_droplist(s, "Chokes on SSH-1 RSA authentication", 'r', 20, HELPCTX(ssh_bugs_rsa1), sshbug_handler, I(offsetof(Config,sshbug_rsa1))); + ctrl_droplist(s, "Chokes on SSH-2 ignore messages", '2', 20, + HELPCTX(ssh_bugs_ignore2), + sshbug_handler, I(offsetof(Config,sshbug_ignore2))); ctrl_droplist(s, "Miscomputes SSH-2 HMAC keys", 'm', 20, HELPCTX(ssh_bugs_hmac2), sshbug_handler, I(offsetof(Config,sshbug_hmac2))); diff --git a/doc/config.but b/doc/config.but index 27704ee9..c36e8184 100644 --- a/doc/config.but +++ b/doc/config.but @@ -2948,9 +2948,6 @@ enabled when talking to a correct server, the session will succeed, but keepalives will not work and the session might be more vulnerable to eavesdroppers than it could be. -This is an SSH-1-specific bug. No known SSH-2 server fails to deal -with SSH-2 ignore messages. - \S{config-ssh-bug-plainpw1} \q{Refuses all SSH-1 \i{password camouflage}} \cfg{winhelp-topic}{ssh.bugs.plainpw1} @@ -2992,6 +2989,23 @@ will be impossible. This is an SSH-1-specific bug. +\S{config-ssh-bug-ignore2} \q{Chokes on SSH-2 \i{ignore message}s} + +\cfg{winhelp-topic}{ssh.bugs.ignore2} + +An ignore message (SSH_MSG_IGNORE) is a message in the SSH protocol +which can be sent from the client to the server, or from the server +to the client, at any time. Either side is required to ignore the +message whenever it receives it. PuTTY uses ignore messages in SSH-2 +to confuse the encrypted data stream and make it harder to +cryptanalyse. It also uses ignore messages for connection +\i{keepalives} (see \k{config-keepalive}). + +If it believes the server to have this bug, PuTTY will stop using +ignore messages. If this bug is enabled when talking to a correct +server, the session will succeed, but keepalives will not work and +the session might be less cryptographically secure than it could be. + \S{config-ssh-bug-hmac2} \q{Miscomputes SSH-2 HMAC keys} \cfg{winhelp-topic}{ssh.bugs.hmac2} diff --git a/putty.h b/putty.h index 6303968b..ca232bc2 100644 --- a/putty.h +++ b/putty.h @@ -592,7 +592,8 @@ struct config_tag { /* SSH bug compatibility modes */ int sshbug_ignore1, sshbug_plainpw1, sshbug_rsa1, sshbug_hmac2, sshbug_derivekey2, sshbug_rsapad2, - sshbug_pksessid2, sshbug_rekey2, sshbug_maxpkt2; + sshbug_pksessid2, sshbug_rekey2, sshbug_maxpkt2, + sshbug_ignore2; /* * ssh_simple means that we promise never to open any channel other * than the main one, which means it can safely use a very large @@ -825,6 +826,7 @@ void term_free(Terminal *); void term_size(Terminal *, int, int, int); void term_paint(Terminal *, Context, int, int, int, int, int); void term_scroll(Terminal *, int, int); +void term_scroll_to_selection(Terminal *, int); void term_pwron(Terminal *, int); void term_clrsb(Terminal *); void term_mouse(Terminal *, Mouse_Button, Mouse_Button, Mouse_Action, diff --git a/settings.c b/settings.c index 9985e2d1..38c41881 100644 --- a/settings.c +++ b/settings.c @@ -477,6 +477,7 @@ void save_open_settings(void *sesskey, Config *cfg) write_setting_i(sesskey, "BugIgnore1", 2-cfg->sshbug_ignore1); write_setting_i(sesskey, "BugPlainPW1", 2-cfg->sshbug_plainpw1); write_setting_i(sesskey, "BugRSA1", 2-cfg->sshbug_rsa1); + write_setting_i(sesskey, "BugIgnore2", 2-cfg->sshbug_ignore2); write_setting_i(sesskey, "BugHMAC2", 2-cfg->sshbug_hmac2); write_setting_i(sesskey, "BugDeriveKey2", 2-cfg->sshbug_derivekey2); write_setting_i(sesskey, "BugRSAPad2", 2-cfg->sshbug_rsapad2); @@ -817,6 +818,7 @@ void load_open_settings(void *sesskey, Config *cfg) gppi(sesskey, "BugIgnore1", 0, &i); cfg->sshbug_ignore1 = 2-i; gppi(sesskey, "BugPlainPW1", 0, &i); cfg->sshbug_plainpw1 = 2-i; gppi(sesskey, "BugRSA1", 0, &i); cfg->sshbug_rsa1 = 2-i; + gppi(sesskey, "BugIgnore2", 0, &i); cfg->sshbug_ignore2 = 2-i; { int i; gppi(sesskey, "BugHMAC2", 0, &i); cfg->sshbug_hmac2 = 2-i; diff --git a/ssh.c b/ssh.c index 8887d9b4..029c78a7 100644 --- a/ssh.c +++ b/ssh.c @@ -194,6 +194,7 @@ static const char *const ssh2_disconnect_reasons[] = { #define BUG_SSH2_REKEY 64 #define BUG_SSH2_PK_SESSIONID 128 #define BUG_SSH2_MAXPKT 256 +#define BUG_CHOKES_ON_SSH2_IGNORE 512 /* * Codes for terminal modes. @@ -2011,7 +2012,8 @@ static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt, int noignore) { int len; if (ssh->cscipher != NULL && (ssh->cscipher->flags & SSH_CIPHER_IS_CBC) && - ssh->deferred_len == 0 && !noignore) { + ssh->deferred_len == 0 && !noignore && + !(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) { /* * Interpose an SSH_MSG_IGNORE to ensure that user data don't * get encrypted with a known IV. @@ -2141,7 +2143,8 @@ static void ssh2_pkt_send_with_padding(Ssh ssh, struct Packet *pkt, * unavailable, we don't do this trick at all, because we * gain nothing by it.) */ - if (ssh->cscipher) { + if (ssh->cscipher && + !(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) { int stringlen, i; stringlen = (256 - ssh->deferred_len); @@ -2508,6 +2511,15 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring) ssh->remote_bugs |= BUG_SSH2_MAXPKT; logevent("We believe remote version ignores SSH-2 maximum packet size"); } + + if (ssh->cfg.sshbug_ignore2 == FORCE_ON) { + /* + * Servers that don't support SSH2_MSG_IGNORE. Currently, + * none detected automatically. + */ + ssh->remote_bugs |= BUG_CHOKES_ON_SSH2_IGNORE; + logevent("We believe remote version has SSH-2 ignore bug"); + } } /* @@ -9426,8 +9438,10 @@ static const struct telnet_special *ssh_get_specials(void *handle) static const struct telnet_special ssh1_ignore_special[] = { {"IGNORE message", TS_NOP} }; - static const struct telnet_special ssh2_transport_specials[] = { + static const struct telnet_special ssh2_ignore_special[] = { {"IGNORE message", TS_NOP}, + }; + static const struct telnet_special ssh2_rekey_special[] = { {"Repeat key exchange", TS_REKEY}, }; static const struct telnet_special ssh2_session_specials[] = { @@ -9452,7 +9466,8 @@ static const struct telnet_special *ssh_get_specials(void *handle) {NULL, TS_EXITMENU} }; /* XXX review this length for any changes: */ - static struct telnet_special ssh_specials[lenof(ssh2_transport_specials) + + static struct telnet_special ssh_specials[lenof(ssh2_ignore_special) + + lenof(ssh2_rekey_special) + lenof(ssh2_session_specials) + lenof(specials_end)]; Ssh ssh = (Ssh) handle; @@ -9471,7 +9486,10 @@ static const struct telnet_special *ssh_get_specials(void *handle) if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE)) ADD_SPECIALS(ssh1_ignore_special); } else if (ssh->version == 2) { - ADD_SPECIALS(ssh2_transport_specials); + if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) + ADD_SPECIALS(ssh2_ignore_special); + if (!(ssh->remote_bugs & BUG_SSH2_REKEY)) + ADD_SPECIALS(ssh2_rekey_special); if (ssh->mainchan) ADD_SPECIALS(ssh2_session_specials); } /* else we're not ready yet */ @@ -9521,9 +9539,11 @@ static void ssh_special(void *handle, Telnet_Special code) if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE)) send_packet(ssh, SSH1_MSG_IGNORE, PKT_STR, "", PKT_END); } else { - pktout = ssh2_pkt_init(SSH2_MSG_IGNORE); - ssh2_pkt_addstring_start(pktout); - ssh2_pkt_send_noqueue(ssh, pktout); + if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) { + pktout = ssh2_pkt_init(SSH2_MSG_IGNORE); + ssh2_pkt_addstring_start(pktout); + ssh2_pkt_send_noqueue(ssh, pktout); + } } } else if (code == TS_REKEY) { if (!ssh->kex_in_progress && ssh->version == 2) { diff --git a/terminal.c b/terminal.c index aaf8705a..c0c809c6 100644 --- a/terminal.c +++ b/terminal.c @@ -5137,6 +5137,31 @@ void term_scroll(Terminal *term, int rel, int where) } /* + * Scroll the scrollback to centre it on the beginning or end of the + * current selection, if any. + */ +void term_scroll_to_selection(Terminal *term, int which_end) +{ + pos target; + int y; + int sbtop = -sblines(term); + + if (term->selstate != SELECTED) + return; + if (which_end) + target = term->selend; + else + target = term->selstart; + + y = target.y - term->rows/2; + if (y < sbtop) + y = sbtop; + else if (y > 0) + y = 0; + term_scroll(term, -1, y); +} + +/* * Helper routine for clipme(): growing buffer. */ typedef struct { diff --git a/windows/window.c b/windows/window.c index 3f092ae5..96f64999 100644 --- a/windows/window.c +++ b/windows/window.c @@ -3811,6 +3811,10 @@ static int TranslateKey(UINT message, WPARAM wParam, LPARAM lParam, SendMessage(hwnd, WM_VSCROLL, SB_LINEDOWN, 0); return 0; } + if ((wParam == VK_PRIOR || wParam == VK_NEXT) && shift_state == 3) { + term_scroll_to_selection(term, (wParam == VK_PRIOR ? 0 : 1)); + return 0; + } if (wParam == VK_INSERT && shift_state == 1) { request_paste(NULL); return 0; -- 2.11.0