auth2-gss.c revision 162852
1162852Sdes/* $OpenBSD: auth2-gss.c,v 1.15 2006/08/03 03:34:41 deraadt Exp $ */ 2124208Sdes 3124208Sdes/* 4124208Sdes * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. 5124208Sdes * 6124208Sdes * Redistribution and use in source and binary forms, with or without 7124208Sdes * modification, are permitted provided that the following conditions 8124208Sdes * are met: 9124208Sdes * 1. Redistributions of source code must retain the above copyright 10124208Sdes * notice, this list of conditions and the following disclaimer. 11124208Sdes * 2. Redistributions in binary form must reproduce the above copyright 12124208Sdes * notice, this list of conditions and the following disclaimer in the 13124208Sdes * documentation and/or other materials provided with the distribution. 14124208Sdes * 15124208Sdes * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR 16124208Sdes * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17124208Sdes * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18124208Sdes * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19124208Sdes * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20124208Sdes * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21124208Sdes * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22124208Sdes * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23124208Sdes * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24124208Sdes * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25124208Sdes */ 26124208Sdes 27124208Sdes#include "includes.h" 28124208Sdes 29124208Sdes#ifdef GSSAPI 30124208Sdes 31162852Sdes#include <sys/types.h> 32162852Sdes 33162852Sdes#include <stdarg.h> 34162852Sdes 35162852Sdes#include "xmalloc.h" 36162852Sdes#include "key.h" 37162852Sdes#include "hostfile.h" 38124208Sdes#include "auth.h" 39124208Sdes#include "ssh2.h" 40124208Sdes#include "log.h" 41124208Sdes#include "dispatch.h" 42162852Sdes#include "buffer.h" 43124208Sdes#include "servconf.h" 44124208Sdes#include "packet.h" 45162852Sdes#include "ssh-gss.h" 46124208Sdes#include "monitor_wrap.h" 47124208Sdes 48124208Sdesextern ServerOptions options; 49124208Sdes 50124208Sdesstatic void input_gssapi_token(int type, u_int32_t plen, void *ctxt); 51126274Sdesstatic void input_gssapi_mic(int type, u_int32_t plen, void *ctxt); 52124208Sdesstatic void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt); 53124208Sdesstatic void input_gssapi_errtok(int, u_int32_t, void *); 54124208Sdes 55124208Sdes/* 56124208Sdes * We only support those mechanisms that we know about (ie ones that we know 57157016Sdes * how to check local user kuserok and the like) 58124208Sdes */ 59124208Sdesstatic int 60124208Sdesuserauth_gssapi(Authctxt *authctxt) 61124208Sdes{ 62137015Sdes gss_OID_desc goid = {0, NULL}; 63124208Sdes Gssctxt *ctxt = NULL; 64124208Sdes int mechs; 65124208Sdes gss_OID_set supported; 66124208Sdes int present; 67124208Sdes OM_uint32 ms; 68124208Sdes u_int len; 69149749Sdes u_char *doid = NULL; 70124208Sdes 71124208Sdes if (!authctxt->valid || authctxt->user == NULL) 72124208Sdes return (0); 73124208Sdes 74124208Sdes mechs = packet_get_int(); 75124208Sdes if (mechs == 0) { 76124208Sdes debug("Mechanism negotiation is not supported"); 77124208Sdes return (0); 78124208Sdes } 79124208Sdes 80124208Sdes ssh_gssapi_supported_oids(&supported); 81124208Sdes do { 82124208Sdes mechs--; 83124208Sdes 84124208Sdes if (doid) 85124208Sdes xfree(doid); 86124208Sdes 87126274Sdes present = 0; 88124208Sdes doid = packet_get_string(&len); 89124208Sdes 90149749Sdes if (len > 2 && doid[0] == SSH_GSS_OIDTYPE && 91149749Sdes doid[1] == len - 2) { 92137015Sdes goid.elements = doid + 2; 93137015Sdes goid.length = len - 2; 94137015Sdes gss_test_oid_set_member(&ms, &goid, supported, 95126274Sdes &present); 96126274Sdes } else { 97126274Sdes logit("Badly formed OID received"); 98124208Sdes } 99124208Sdes } while (mechs > 0 && !present); 100124208Sdes 101124208Sdes gss_release_oid_set(&ms, &supported); 102124208Sdes 103124208Sdes if (!present) { 104124208Sdes xfree(doid); 105124208Sdes return (0); 106124208Sdes } 107124208Sdes 108137015Sdes if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) { 109162852Sdes if (ctxt != NULL) 110162852Sdes ssh_gssapi_delete_ctx(&ctxt); 111124208Sdes xfree(doid); 112124208Sdes return (0); 113124208Sdes } 114124208Sdes 115157016Sdes authctxt->methoddata = (void *)ctxt; 116124208Sdes 117124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); 118124208Sdes 119126274Sdes /* Return the OID that we received */ 120124208Sdes packet_put_string(doid, len); 121124208Sdes 122124208Sdes packet_send(); 123124208Sdes xfree(doid); 124124208Sdes 125124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 126124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 127124208Sdes authctxt->postponed = 1; 128124208Sdes 129124208Sdes return (0); 130124208Sdes} 131124208Sdes 132124208Sdesstatic void 133124208Sdesinput_gssapi_token(int type, u_int32_t plen, void *ctxt) 134124208Sdes{ 135124208Sdes Authctxt *authctxt = ctxt; 136124208Sdes Gssctxt *gssctxt; 137124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 138124208Sdes gss_buffer_desc recv_tok; 139126274Sdes OM_uint32 maj_status, min_status, flags; 140124208Sdes u_int len; 141124208Sdes 142124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 143124208Sdes fatal("No authentication or GSSAPI context"); 144124208Sdes 145124208Sdes gssctxt = authctxt->methoddata; 146124208Sdes recv_tok.value = packet_get_string(&len); 147124208Sdes recv_tok.length = len; /* u_int vs. size_t */ 148124208Sdes 149124208Sdes packet_check_eom(); 150124208Sdes 151124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 152126274Sdes &send_tok, &flags)); 153124208Sdes 154124208Sdes xfree(recv_tok.value); 155124208Sdes 156124208Sdes if (GSS_ERROR(maj_status)) { 157124208Sdes if (send_tok.length != 0) { 158124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 159124208Sdes packet_put_string(send_tok.value, send_tok.length); 160124208Sdes packet_send(); 161124208Sdes } 162124208Sdes authctxt->postponed = 0; 163124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 164126274Sdes userauth_finish(authctxt, 0, "gssapi-with-mic"); 165124208Sdes } else { 166124208Sdes if (send_tok.length != 0) { 167124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 168124208Sdes packet_put_string(send_tok.value, send_tok.length); 169124208Sdes packet_send(); 170124208Sdes } 171124208Sdes if (maj_status == GSS_S_COMPLETE) { 172124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 173126274Sdes if (flags & GSS_C_INTEG_FLAG) 174126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, 175126274Sdes &input_gssapi_mic); 176126274Sdes else 177126274Sdes dispatch_set( 178126274Sdes SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, 179126274Sdes &input_gssapi_exchange_complete); 180124208Sdes } 181124208Sdes } 182124208Sdes 183124208Sdes gss_release_buffer(&min_status, &send_tok); 184124208Sdes} 185124208Sdes 186124208Sdesstatic void 187124208Sdesinput_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 188124208Sdes{ 189124208Sdes Authctxt *authctxt = ctxt; 190124208Sdes Gssctxt *gssctxt; 191124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 192124208Sdes gss_buffer_desc recv_tok; 193124208Sdes OM_uint32 maj_status; 194124208Sdes u_int len; 195124208Sdes 196124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 197124208Sdes fatal("No authentication or GSSAPI context"); 198124208Sdes 199124208Sdes gssctxt = authctxt->methoddata; 200124208Sdes recv_tok.value = packet_get_string(&len); 201124208Sdes recv_tok.length = len; 202124208Sdes 203124208Sdes packet_check_eom(); 204124208Sdes 205124208Sdes /* Push the error token into GSSAPI to see what it says */ 206124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 207124208Sdes &send_tok, NULL)); 208124208Sdes 209124208Sdes xfree(recv_tok.value); 210124208Sdes 211124208Sdes /* We can't return anything to the client, even if we wanted to */ 212124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 213124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 214124208Sdes 215124208Sdes /* The client will have already moved on to the next auth */ 216124208Sdes 217124208Sdes gss_release_buffer(&maj_status, &send_tok); 218124208Sdes} 219124208Sdes 220124208Sdes/* 221124208Sdes * This is called when the client thinks we've completed authentication. 222124208Sdes * It should only be enabled in the dispatch handler by the function above, 223124208Sdes * which only enables it once the GSSAPI exchange is complete. 224124208Sdes */ 225124208Sdes 226124208Sdesstatic void 227124208Sdesinput_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) 228124208Sdes{ 229124208Sdes Authctxt *authctxt = ctxt; 230124208Sdes Gssctxt *gssctxt; 231124208Sdes int authenticated; 232124208Sdes 233124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 234124208Sdes fatal("No authentication or GSSAPI context"); 235124208Sdes 236124208Sdes gssctxt = authctxt->methoddata; 237124208Sdes 238124208Sdes /* 239126274Sdes * We don't need to check the status, because we're only enabled in 240126274Sdes * the dispatcher once the exchange is complete 241124208Sdes */ 242124208Sdes 243124208Sdes packet_check_eom(); 244124208Sdes 245124208Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 246124208Sdes 247124208Sdes authctxt->postponed = 0; 248124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 249124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 250126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 251124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 252126274Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic"); 253124208Sdes} 254124208Sdes 255126274Sdesstatic void 256126274Sdesinput_gssapi_mic(int type, u_int32_t plen, void *ctxt) 257126274Sdes{ 258126274Sdes Authctxt *authctxt = ctxt; 259126274Sdes Gssctxt *gssctxt; 260126274Sdes int authenticated = 0; 261126274Sdes Buffer b; 262126274Sdes gss_buffer_desc mic, gssbuf; 263126274Sdes u_int len; 264126274Sdes 265126274Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 266126274Sdes fatal("No authentication or GSSAPI context"); 267126274Sdes 268126274Sdes gssctxt = authctxt->methoddata; 269126274Sdes 270126274Sdes mic.value = packet_get_string(&len); 271126274Sdes mic.length = len; 272126274Sdes 273126274Sdes ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, 274126274Sdes "gssapi-with-mic"); 275126274Sdes 276126274Sdes gssbuf.value = buffer_ptr(&b); 277126274Sdes gssbuf.length = buffer_len(&b); 278126274Sdes 279126274Sdes if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) 280126274Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 281126274Sdes else 282126274Sdes logit("GSSAPI MIC check failed"); 283126274Sdes 284126274Sdes buffer_free(&b); 285126274Sdes xfree(mic.value); 286126274Sdes 287126274Sdes authctxt->postponed = 0; 288126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 289126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 290126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 291126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 292126274Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic"); 293126274Sdes} 294126274Sdes 295124208SdesAuthmethod method_gssapi = { 296126274Sdes "gssapi-with-mic", 297124208Sdes userauth_gssapi, 298124208Sdes &options.gss_authentication 299124208Sdes}; 300124208Sdes 301124208Sdes#endif /* GSSAPI */ 302