From 22376d27a349f62c502fec3396dfe0fdcb2a40b7 Mon Sep 17 00:00:00 2001 From: "djm@openbsd.org" Date: Sun, 3 Sep 2017 23:33:13 +0000 Subject: upstream commit Expand ssh_config's StrictModes option with two new settings: StrictModes=accept-new will automatically accept hitherto-unseen keys but will refuse connections for changed or invalid hostkeys. StrictModes=off is the same as StrictModes=no Motivation: StrictModes=no combines two behaviours for host key processing: automatically learning new hostkeys and continuing to connect to hosts with invalid/changed hostkeys. The latter behaviour is quite dangerous since it removes most of the protections the SSH protocol is supposed to provide. Quite a few users want to automatically learn hostkeys however, so this makes that feature available with less danger. At some point in the future, StrictModes=no will change to be a synonym for accept-new, with its current behaviour remaining available via StrictModes=off. bz#2400, suggested by Michael Samuel; ok markus Upstream-ID: 0f55502bf75fc93a74fb9853264a8276b9680b64 --- sshconnect.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) (limited to 'sshconnect.c') diff --git a/sshconnect.c b/sshconnect.c index 4013ec7db..2842d9e59 100644 --- a/sshconnect.c +++ b/sshconnect.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshconnect.c,v 1.284 2017/09/01 05:53:56 djm Exp $ */ +/* $OpenBSD: sshconnect.c,v 1.285 2017/09/03 23:33:13 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -891,7 +891,8 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, if (readonly || want_cert) goto fail; /* The host is new. */ - if (options.strict_host_key_checking == 1) { + if (options.strict_host_key_checking == + SSH_STRICT_HOSTKEY_YES) { /* * User has requested strict host key checking. We * will not add the host key automatically. The only @@ -900,7 +901,8 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, error("No %s host key is known for %.200s and you " "have requested strict checking.", type, host); goto fail; - } else if (options.strict_host_key_checking == 2) { + } else if (options.strict_host_key_checking == + SSH_STRICT_HOSTKEY_ASK) { char msg1[1024], msg2[1024]; if (show_other_keys(host_hostkeys, host_key)) @@ -944,8 +946,8 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, hostkey_trusted = 1; /* user explicitly confirmed */ } /* - * If not in strict mode, add the key automatically to the - * local known_hosts file. + * If in "new" or "off" strict mode, add the key automatically + * to the local known_hosts file. */ if (options.check_host_ip && ip_status == HOST_NEW) { snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); @@ -987,7 +989,8 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, * If strict host key checking is in use, the user will have * to edit the key manually and we can only abort. */ - if (options.strict_host_key_checking) { + if (options.strict_host_key_checking != + SSH_STRICT_HOSTKEY_OFF) { error("%s host key for %.200s was revoked and you have " "requested strict checking.", type, host); goto fail; @@ -1040,7 +1043,8 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, * If strict host key checking is in use, the user will have * to edit the key manually and we can only abort. */ - if (options.strict_host_key_checking) { + if (options.strict_host_key_checking != + SSH_STRICT_HOSTKEY_OFF) { error("%s host key for %.200s has changed and you have " "requested strict checking.", type, host); goto fail; @@ -1127,15 +1131,17 @@ check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, "\nMatching host key in %s:%lu", host_found->file, host_found->line); } - if (options.strict_host_key_checking == 1) { - logit("%s", msg); - error("Exiting, you have requested strict checking."); - goto fail; - } else if (options.strict_host_key_checking == 2) { + if (options.strict_host_key_checking == + SSH_STRICT_HOSTKEY_ASK) { strlcat(msg, "\nAre you sure you want " "to continue connecting (yes/no)? ", sizeof(msg)); if (!confirm(msg)) goto fail; + } else if (options.strict_host_key_checking != + SSH_STRICT_HOSTKEY_OFF) { + logit("%s", msg); + error("Exiting, you have requested strict checking."); + goto fail; } else { logit("%s", msg); } -- cgit v1.2.3