diff options
| author | djm <djm> | 2014-04-20 03:23:43 +0000 |
|---|---|---|
| committer | djm <djm> | 2014-04-20 03:23:43 +0000 |
| commit | 07742efd45cd02828bae526530eeb71b0ee40392 (patch) | |
| tree | ef90c46524b5b4f02c22cad3a8d095471602722d | |
| parent | abadd929ae21dfd651b9ee08064dad0dde653d09 (diff) | |
| download | openssh-07742efd45cd02828bae526530eeb71b0ee40392.tar.gz | |
- djm@cvs.openbsd.org 2014/04/01 03:34:10
[sshconnect.c]
When using VerifyHostKeyDNS with a DNSSEC resolver, down-convert any
certificate keys to plain keys and attempt SSHFP resolution.
Prevents a server from skipping SSHFP lookup and forcing a new-hostkey
dialog by offering only certificate keys.
Reported by mcv21 AT cam.ac.uk
| -rw-r--r-- | ChangeLog | 9 | ||||
| -rw-r--r-- | sshconnect.c | 44 |
2 files changed, 36 insertions, 17 deletions
@@ -73,6 +73,15 @@ [ssh-keysign.c] include fingerprint of key not found use arc4random_buf() instead of loop+arc4random() + - djm@cvs.openbsd.org 2014/04/01 03:34:10 + [sshconnect.c] + When using VerifyHostKeyDNS with a DNSSEC resolver, down-convert any + certificate keys to plain keys and attempt SSHFP resolution. + + Prevents a server from skipping SSHFP lookup and forcing a new-hostkey + dialog by offering only certificate keys. + + Reported by mcv21 AT cam.ac.uk 20140401 - (djm) On platforms that support it, use prctl() to prevent sftp-server diff --git a/sshconnect.c b/sshconnect.c index 573d7a8e..ca6e4cc9 100644 --- a/sshconnect.c +++ b/sshconnect.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshconnect.c,v 1.246 2014/02/06 22:21:01 djm Exp $ */ +/* $OpenBSD: sshconnect.c,v 1.247 2014/04/01 03:34:10 djm Exp $ */ /* * Author: Tatu Ylonen <ylo@cs.hut.fi> * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland @@ -1219,29 +1219,39 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) { int flags = 0; char *fp; + Key *plain = NULL; fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); debug("Server host key: %s %s", key_type(host_key), fp); free(fp); - /* XXX certs are not yet supported for DNS */ - if (!key_is_cert(host_key) && options.verify_host_key_dns && - verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) { - if (flags & DNS_VERIFY_FOUND) { - - if (options.verify_host_key_dns == 1 && - flags & DNS_VERIFY_MATCH && - flags & DNS_VERIFY_SECURE) - return 0; - - if (flags & DNS_VERIFY_MATCH) { - matching_host_key_dns = 1; - } else { - warn_changed_key(host_key); - error("Update the SSHFP RR in DNS with the new " - "host key to get rid of this message."); + if (options.verify_host_key_dns) { + /* + * XXX certs are not yet supported for DNS, so downgrade + * them and try the plain key. + */ + plain = key_from_private(host_key); + if (key_is_cert(plain)) + key_drop_cert(plain); + if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { + if (flags & DNS_VERIFY_FOUND) { + if (options.verify_host_key_dns == 1 && + flags & DNS_VERIFY_MATCH && + flags & DNS_VERIFY_SECURE) { + key_free(plain); + return 0; + } + if (flags & DNS_VERIFY_MATCH) { + matching_host_key_dns = 1; + } else { + warn_changed_key(plain); + error("Update the SSHFP RR in DNS " + "with the new host key to get rid " + "of this message."); + } } } + key_free(plain); } return check_host_key(host, hostaddr, options.port, host_key, RDRW, |