diff options
| -rw-r--r-- | auth2-pubkey.c | 37 | ||||
| -rw-r--r-- | monitor.c | 26 |
2 files changed, 50 insertions, 13 deletions
diff --git a/auth2-pubkey.c b/auth2-pubkey.c index ed3e74c3..9c2298fc 100644 --- a/auth2-pubkey.c +++ b/auth2-pubkey.c @@ -1,4 +1,4 @@ -/* $OpenBSD: auth2-pubkey.c,v 1.111 2021/12/19 22:12:07 djm Exp $ */ +/* $OpenBSD: auth2-pubkey.c,v 1.112 2021/12/19 22:12:30 djm Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. * @@ -67,6 +67,7 @@ #include "authfile.h" #include "match.h" #include "ssherr.h" +#include "kex.h" #include "channels.h" /* XXX for session.h */ #include "session.h" /* XXX for child_set_env(); refactor? */ #include "sk-api.h" @@ -91,19 +92,34 @@ userauth_pubkey(struct ssh *ssh, const char *method) Authctxt *authctxt = ssh->authctxt; struct passwd *pw = authctxt->pw; struct sshbuf *b = NULL; - struct sshkey *key = NULL; + struct sshkey *key = NULL, *hostkey = NULL; char *pkalg = NULL, *userstyle = NULL, *key_s = NULL, *ca_s = NULL; u_char *pkblob = NULL, *sig = NULL, have_sig; size_t blen, slen; - int r, pktype; + int hostbound, r, pktype; int req_presence = 0, req_verify = 0, authenticated = 0; struct sshauthopt *authopts = NULL; struct sshkey_sig_details *sig_details = NULL; + hostbound = strcmp(method, "publickey-hostbound-v00@openssh.com") == 0; + if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0 || (r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 || (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0) - fatal_fr(r, "parse packet"); + fatal_fr(r, "parse %s packet", method); + + /* hostbound auth includes the hostkey offered at initial KEX */ + if (hostbound) { + if ((r = sshpkt_getb_froms(ssh, &b)) != 0 || + (r = sshkey_fromb(b, &hostkey)) != 0) + fatal_fr(r, "parse %s hostkey", method); + if (ssh->kex->initial_hostkey == NULL) + fatal_f("internal error: initial hostkey not recorded"); + if (!sshkey_equal(hostkey, ssh->kex->initial_hostkey)) + fatal_f("%s packet contained wrong host key", method); + sshbuf_free(b); + b = NULL; + } if (log_level_get() >= SYSLOG_LEVEL_DEBUG2) { char *keystring; @@ -166,7 +182,8 @@ userauth_pubkey(struct ssh *ssh, const char *method) ca_s = format_key(key->cert->signature_key); if (have_sig) { - debug3_f("have %s signature for %s%s%s", pkalg, key_s, + debug3_f("%s have %s signature for %s%s%s", + method, pkalg, key_s, ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s); if ((r = sshpkt_get_string(ssh, &sig, &slen)) != 0 || (r = sshpkt_get_end(ssh)) != 0) @@ -196,7 +213,10 @@ userauth_pubkey(struct ssh *ssh, const char *method) (r = sshbuf_put_u8(b, have_sig)) != 0 || (r = sshbuf_put_cstring(b, pkalg)) != 0 || (r = sshbuf_put_string(b, pkblob, blen)) != 0) - fatal_fr(r, "reconstruct packet"); + fatal_fr(r, "reconstruct %s packet", method); + if (hostbound && + (r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0) + fatal_fr(r, "reconstruct %s packet", method); #ifdef DEBUG_PK sshbuf_dump(b, stderr); #endif @@ -246,7 +266,7 @@ userauth_pubkey(struct ssh *ssh, const char *method) } auth2_record_key(authctxt, authenticated, key); } else { - debug_f("test pkalg %s pkblob %s%s%s", pkalg, key_s, + debug_f("%s test pkalg %s pkblob %s%s%s", method, pkalg, key_s, ca_s == NULL ? "" : " CA ", ca_s == NULL ? "" : ca_s); if ((r = sshpkt_get_end(ssh)) != 0) @@ -285,6 +305,7 @@ done: sshbuf_free(b); sshauthopt_free(authopts); sshkey_free(key); + sshkey_free(hostkey); free(userstyle); free(pkalg); free(pkblob); @@ -1067,7 +1088,7 @@ user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key, Authmethod method_pubkey = { "publickey", - NULL, + "publickey-hostbound-v00@openssh.com", userauth_pubkey, &options.pubkey_authentication }; @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor.c,v 1.228 2021/08/11 05:20:17 djm Exp $ */ +/* $OpenBSD: monitor.c,v 1.229 2021/12/19 22:12:30 djm Exp $ */ /* * Copyright 2002 Niels Provos <provos@citi.umich.edu> * Copyright 2002 Markus Friedl <markus@openbsd.org> @@ -1246,11 +1246,12 @@ static int monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) { struct sshbuf *b; + struct sshkey *hostkey = NULL; const u_char *p; char *userstyle, *cp; size_t len; u_char type; - int r, fail = 0; + int hostbound = 0, r, fail = 0; if ((b = sshbuf_from(data, datalen)) == NULL) fatal_f("sshbuf_from"); @@ -1291,19 +1292,34 @@ monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) if ((r = sshbuf_skip_string(b)) != 0 || /* service */ (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) fatal_fr(r, "parse method"); - if (strcmp("publickey", cp) != 0) - fail++; + if (strcmp("publickey", cp) != 0) { + if (strcmp("publickey-hostbound-v00@openssh.com", cp) == 0) + hostbound = 1; + else + fail++; + } free(cp); if ((r = sshbuf_get_u8(b, &type)) != 0) fatal_fr(r, "parse pktype"); if (type == 0) fail++; if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ - (r = sshbuf_skip_string(b)) != 0) /* pkblob */ + (r = sshbuf_skip_string(b)) != 0 || /* pkblob */ + (hostbound && (r = sshkey_froms(b, &hostkey)) != 0)) fatal_fr(r, "parse pk"); if (sshbuf_len(b) != 0) fail++; sshbuf_free(b); + if (hostkey != NULL) { + /* + * Ensure this is actually one of our hostkeys; unfortunately + * can't check ssh->kex->initial_hostkey directly at this point + * as packet state has not yet been exported to monitor. + */ + if (get_hostkey_index(hostkey, 1, ssh) == -1) + fatal_f("hostbound hostkey does not match"); + sshkey_free(hostkey); + } return (fail == 0); } |