Excerpts from the release notes: * ssh-agent(1): PKCS#11 modules must now be specified by their full paths. Previously dlopen(3) could search for them in system library directories. * ssh(1): allow forwarding Unix Domain sockets via ssh -W. * ssh(1): add support for configuration tags to ssh(1). This adds a ssh_config(5) "Tag" directive and corresponding "Match tag" predicate that may be used to select blocks of configuration similar to the pf.conf(5) keywords of the same name. * ssh(1): add a "match localnetwork" predicate. This allows matching on the addresses of available network interfaces and may be used to vary the effective client configuration based on network location. * ssh-agent(1): improve isolation between loaded PKCS#11 modules by running separate ssh-pkcs11-helpers for each loaded provider. * ssh-agent(1), ssh(1): improve defences against invalid PKCS#11 modules being loaded by checking that the requested module contains the required symbol before loading it. * ssh(1): don't incorrectly disable hostname canonicalization when CanonicalizeHostname=yes and ProxyJump was expicitly set to "none". bz3567 Full release notes at https://www.openssh.com/txt/release-9.4 Relnotes: Yes Sponsored by: The FreeBSD Foundation
344 lines
9.8 KiB
C
344 lines
9.8 KiB
C
/* $OpenBSD: auth2-gss.c,v 1.34 2023/03/31 04:22:27 djm Exp $ */
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/*
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* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#ifdef GSSAPI
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#include <sys/types.h>
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#include <stdarg.h>
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#include "xmalloc.h"
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#include "sshkey.h"
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#include "hostfile.h"
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#include "auth.h"
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#include "ssh2.h"
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#include "log.h"
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#include "dispatch.h"
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#include "sshbuf.h"
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#include "ssherr.h"
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#include "misc.h"
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#include "servconf.h"
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#include "packet.h"
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#include "kex.h"
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#include "ssh-gss.h"
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#include "monitor_wrap.h"
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#define SSH_GSSAPI_MAX_MECHS 2048
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extern ServerOptions options;
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static int input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh);
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static int input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh);
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static int input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh);
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static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
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/*
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* We only support those mechanisms that we know about (ie ones that we know
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* how to check local user kuserok and the like)
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*/
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static int
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userauth_gssapi(struct ssh *ssh, const char *method)
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{
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Authctxt *authctxt = ssh->authctxt;
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gss_OID_desc goid = {0, NULL};
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Gssctxt *ctxt = NULL;
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int r, present;
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u_int mechs;
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OM_uint32 ms;
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size_t len;
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u_char *doid = NULL;
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if ((r = sshpkt_get_u32(ssh, &mechs)) != 0)
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fatal_fr(r, "parse packet");
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if (mechs == 0) {
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logit_f("mechanism negotiation is not supported");
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return (0);
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} else if (mechs > SSH_GSSAPI_MAX_MECHS) {
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logit_f("too many mechanisms requested %u > %u", mechs,
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SSH_GSSAPI_MAX_MECHS);
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return (0);
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}
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do {
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mechs--;
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free(doid);
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present = 0;
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if ((r = sshpkt_get_string(ssh, &doid, &len)) != 0)
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fatal_fr(r, "parse oid");
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if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
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doid[1] == len - 2) {
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goid.elements = doid + 2;
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goid.length = len - 2;
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ssh_gssapi_test_oid_supported(&ms, &goid, &present);
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} else {
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logit_f("badly formed OID received");
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}
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} while (mechs > 0 && !present);
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if (!present) {
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free(doid);
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authctxt->server_caused_failure = 1;
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return (0);
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}
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if (!authctxt->valid || authctxt->user == NULL) {
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debug2_f("disabled because of invalid user");
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free(doid);
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return (0);
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}
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if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
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if (ctxt != NULL)
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ssh_gssapi_delete_ctx(&ctxt);
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free(doid);
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authctxt->server_caused_failure = 1;
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return (0);
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}
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authctxt->methoddata = (void *)ctxt;
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/* Return the OID that we received */
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if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE)) != 0 ||
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(r = sshpkt_put_string(ssh, doid, len)) != 0 ||
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(r = sshpkt_send(ssh)) != 0)
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fatal_fr(r, "send packet");
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free(doid);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
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authctxt->postponed = 1;
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return (0);
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}
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static int
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input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
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{
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Authctxt *authctxt = ssh->authctxt;
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Gssctxt *gssctxt;
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gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc recv_tok;
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OM_uint32 maj_status, min_status, flags;
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u_char *p;
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size_t len;
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int r;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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gssctxt = authctxt->methoddata;
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if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
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(r = sshpkt_get_end(ssh)) != 0)
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fatal_fr(r, "parse packet");
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recv_tok.value = p;
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recv_tok.length = len;
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maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
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&send_tok, &flags));
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free(p);
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if (GSS_ERROR(maj_status)) {
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if (send_tok.length != 0) {
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if ((r = sshpkt_start(ssh,
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SSH2_MSG_USERAUTH_GSSAPI_ERRTOK)) != 0 ||
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(r = sshpkt_put_string(ssh, send_tok.value,
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send_tok.length)) != 0 ||
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(r = sshpkt_send(ssh)) != 0)
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fatal_fr(r, "send ERRTOK packet");
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}
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authctxt->postponed = 0;
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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userauth_finish(ssh, 0, "gssapi-with-mic", NULL);
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} else {
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if (send_tok.length != 0) {
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if ((r = sshpkt_start(ssh,
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SSH2_MSG_USERAUTH_GSSAPI_TOKEN)) != 0 ||
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(r = sshpkt_put_string(ssh, send_tok.value,
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send_tok.length)) != 0 ||
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(r = sshpkt_send(ssh)) != 0)
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fatal_fr(r, "send TOKEN packet");
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}
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if (maj_status == GSS_S_COMPLETE) {
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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if (flags & GSS_C_INTEG_FLAG)
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_MIC,
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&input_gssapi_mic);
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else
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ssh_dispatch_set(ssh,
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SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
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&input_gssapi_exchange_complete);
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}
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}
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gss_release_buffer(&min_status, &send_tok);
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return 0;
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}
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static int
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input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
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{
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Authctxt *authctxt = ssh->authctxt;
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Gssctxt *gssctxt;
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gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc recv_tok;
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OM_uint32 maj_status;
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int r;
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u_char *p;
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size_t len;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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gssctxt = authctxt->methoddata;
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if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
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(r = sshpkt_get_end(ssh)) != 0)
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fatal_fr(r, "parse packet");
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recv_tok.value = p;
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recv_tok.length = len;
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/* Push the error token into GSSAPI to see what it says */
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maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
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&send_tok, NULL));
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free(recv_tok.value);
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/* We can't return anything to the client, even if we wanted to */
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
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/* The client will have already moved on to the next auth */
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gss_release_buffer(&maj_status, &send_tok);
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return 0;
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}
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/*
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* This is called when the client thinks we've completed authentication.
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* It should only be enabled in the dispatch handler by the function above,
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* which only enables it once the GSSAPI exchange is complete.
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*/
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static int
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input_gssapi_exchange_complete(int type, u_int32_t plen, struct ssh *ssh)
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{
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Authctxt *authctxt = ssh->authctxt;
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int r, authenticated;
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const char *displayname;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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/*
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* We don't need to check the status, because we're only enabled in
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* the dispatcher once the exchange is complete
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*/
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if ((r = sshpkt_get_end(ssh)) != 0)
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fatal_fr(r, "parse packet");
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authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
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if ((!use_privsep || mm_is_monitor()) &&
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(displayname = ssh_gssapi_displayname()) != NULL)
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auth2_record_info(authctxt, "%s", displayname);
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authctxt->postponed = 0;
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
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userauth_finish(ssh, authenticated, "gssapi-with-mic", NULL);
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return 0;
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}
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static int
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input_gssapi_mic(int type, u_int32_t plen, struct ssh *ssh)
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{
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Authctxt *authctxt = ssh->authctxt;
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Gssctxt *gssctxt;
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int r, authenticated = 0;
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struct sshbuf *b;
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gss_buffer_desc mic, gssbuf;
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const char *displayname;
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u_char *p;
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size_t len;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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gssctxt = authctxt->methoddata;
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if ((r = sshpkt_get_string(ssh, &p, &len)) != 0)
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fatal_fr(r, "parse packet");
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if ((b = sshbuf_new()) == NULL)
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fatal_f("sshbuf_new failed");
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mic.value = p;
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mic.length = len;
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ssh_gssapi_buildmic(b, authctxt->user, authctxt->service,
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"gssapi-with-mic", ssh->kex->session_id);
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if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
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fatal_f("sshbuf_mutable_ptr failed");
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gssbuf.length = sshbuf_len(b);
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if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
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authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
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else
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logit("GSSAPI MIC check failed");
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sshbuf_free(b);
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free(mic.value);
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if ((!use_privsep || mm_is_monitor()) &&
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(displayname = ssh_gssapi_displayname()) != NULL)
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auth2_record_info(authctxt, "%s", displayname);
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authctxt->postponed = 0;
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
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ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
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userauth_finish(ssh, authenticated, "gssapi-with-mic", NULL);
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return 0;
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}
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Authmethod method_gssapi = {
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"gssapi-with-mic",
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NULL,
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userauth_gssapi,
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&options.gss_authentication
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};
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#endif /* GSSAPI */
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