diff options
| author | djm@openbsd.org <djm@openbsd.org> | 2017-12-18 23:16:23 +0000 |
|---|---|---|
| committer | Damien Miller <djm@mindrot.org> | 2017-12-19 15:21:37 +1100 |
| commit | 7860731ef190b52119fa480f8064ab03c44a120a (patch) | |
| tree | 758274280fa590762fac827aae5b9aa3ee56c946 /serverloop.c | |
| parent | 966ef478339ad5e631fb684d2a8effe846ce3fd4 (diff) | |
upstream commit
unbreak hostkey rotation; attempting to sign with a
desired signature algorithm of kex->hostkey_alg is incorrect when the key
type isn't capable of making those signatures. ok markus@
OpenBSD-Commit-ID: 35ae46864e1f5859831ec0d115ee5ea50953a906
Diffstat (limited to 'serverloop.c')
| -rw-r--r-- | serverloop.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/serverloop.c b/serverloop.c index fb298056..615921c3 100644 --- a/serverloop.c +++ b/serverloop.c @@ -1,4 +1,4 @@ -/* $OpenBSD: serverloop.c,v 1.201 2017/12/18 02:25:15 djm Exp $ */ +/* $OpenBSD: serverloop.c,v 1.202 2017/12/18 23:16:24 djm Exp $ */ /* * Author: Tatu Ylonen <ylo@cs.hut.fi> * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland @@ -671,7 +671,7 @@ server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) struct sshbuf *resp = NULL; struct sshbuf *sigbuf = NULL; struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; - int r, ndx, success = 0; + int r, ndx, kexsigtype, use_kexsigtype, success = 0; const u_char *blob; u_char *sig = 0; size_t blen, slen; @@ -679,6 +679,8 @@ server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) fatal("%s: sshbuf_new", __func__); + kexsigtype = sshkey_type_plain( + sshkey_type_from_name(ssh->kex->hostkey_alg)); while (ssh_packet_remaining(ssh) > 0) { sshkey_free(key); key = NULL; @@ -709,6 +711,12 @@ server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) sshbuf_reset(sigbuf); free(sig); sig = NULL; + /* + * For RSA keys, prefer to use the signature type negotiated + * during KEX to the default (SHA1). + */ + use_kexsigtype = kexsigtype == KEY_RSA && + sshkey_type_plain(key->type) == KEY_RSA; if ((r = sshbuf_put_cstring(sigbuf, "hostkeys-prove-00@openssh.com")) != 0 || (r = sshbuf_put_string(sigbuf, @@ -716,7 +724,7 @@ server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) (r = sshkey_puts(key, sigbuf)) != 0 || (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), - ssh->kex->hostkey_alg, 0)) != 0 || + use_kexsigtype ? ssh->kex->hostkey_alg : NULL, 0)) != 0 || (r = sshbuf_put_string(resp, sig, slen)) != 0) { error("%s: couldn't prepare signature: %s", __func__, ssh_err(r)); |