auth2-gss.c revision 248619
1248619Sdes/* $OpenBSD: auth2-gss.c,v 1.18 2012/12/02 20:34:09 djm 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); 105226046Sdes authctxt->server_caused_failure = 1; 106124208Sdes return (0); 107124208Sdes } 108124208Sdes 109137015Sdes if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) { 110162852Sdes if (ctxt != NULL) 111162852Sdes ssh_gssapi_delete_ctx(&ctxt); 112124208Sdes xfree(doid); 113226046Sdes authctxt->server_caused_failure = 1; 114124208Sdes return (0); 115124208Sdes } 116124208Sdes 117157016Sdes authctxt->methoddata = (void *)ctxt; 118124208Sdes 119124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); 120124208Sdes 121126274Sdes /* Return the OID that we received */ 122124208Sdes packet_put_string(doid, len); 123124208Sdes 124124208Sdes packet_send(); 125124208Sdes xfree(doid); 126124208Sdes 127124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 128124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 129124208Sdes authctxt->postponed = 1; 130124208Sdes 131124208Sdes return (0); 132124208Sdes} 133124208Sdes 134124208Sdesstatic void 135124208Sdesinput_gssapi_token(int type, u_int32_t plen, void *ctxt) 136124208Sdes{ 137124208Sdes Authctxt *authctxt = ctxt; 138124208Sdes Gssctxt *gssctxt; 139124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 140124208Sdes gss_buffer_desc recv_tok; 141126274Sdes OM_uint32 maj_status, min_status, flags; 142124208Sdes u_int len; 143124208Sdes 144124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 145124208Sdes fatal("No authentication or GSSAPI context"); 146124208Sdes 147124208Sdes gssctxt = authctxt->methoddata; 148124208Sdes recv_tok.value = packet_get_string(&len); 149124208Sdes recv_tok.length = len; /* u_int vs. size_t */ 150124208Sdes 151124208Sdes packet_check_eom(); 152124208Sdes 153124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 154126274Sdes &send_tok, &flags)); 155124208Sdes 156124208Sdes xfree(recv_tok.value); 157124208Sdes 158124208Sdes if (GSS_ERROR(maj_status)) { 159124208Sdes if (send_tok.length != 0) { 160124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 161124208Sdes packet_put_string(send_tok.value, send_tok.length); 162124208Sdes packet_send(); 163124208Sdes } 164124208Sdes authctxt->postponed = 0; 165124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 166248619Sdes userauth_finish(authctxt, 0, "gssapi-with-mic", NULL); 167124208Sdes } else { 168124208Sdes if (send_tok.length != 0) { 169124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 170124208Sdes packet_put_string(send_tok.value, send_tok.length); 171124208Sdes packet_send(); 172124208Sdes } 173124208Sdes if (maj_status == GSS_S_COMPLETE) { 174124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 175126274Sdes if (flags & GSS_C_INTEG_FLAG) 176126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, 177126274Sdes &input_gssapi_mic); 178126274Sdes else 179126274Sdes dispatch_set( 180126274Sdes SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, 181126274Sdes &input_gssapi_exchange_complete); 182124208Sdes } 183124208Sdes } 184124208Sdes 185124208Sdes gss_release_buffer(&min_status, &send_tok); 186124208Sdes} 187124208Sdes 188124208Sdesstatic void 189124208Sdesinput_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 190124208Sdes{ 191124208Sdes Authctxt *authctxt = ctxt; 192124208Sdes Gssctxt *gssctxt; 193124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 194124208Sdes gss_buffer_desc recv_tok; 195124208Sdes OM_uint32 maj_status; 196124208Sdes u_int len; 197124208Sdes 198124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 199124208Sdes fatal("No authentication or GSSAPI context"); 200124208Sdes 201124208Sdes gssctxt = authctxt->methoddata; 202124208Sdes recv_tok.value = packet_get_string(&len); 203124208Sdes recv_tok.length = len; 204124208Sdes 205124208Sdes packet_check_eom(); 206124208Sdes 207124208Sdes /* Push the error token into GSSAPI to see what it says */ 208124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 209124208Sdes &send_tok, NULL)); 210124208Sdes 211124208Sdes xfree(recv_tok.value); 212124208Sdes 213124208Sdes /* We can't return anything to the client, even if we wanted to */ 214124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 215124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 216124208Sdes 217124208Sdes /* The client will have already moved on to the next auth */ 218124208Sdes 219124208Sdes gss_release_buffer(&maj_status, &send_tok); 220124208Sdes} 221124208Sdes 222124208Sdes/* 223124208Sdes * This is called when the client thinks we've completed authentication. 224124208Sdes * It should only be enabled in the dispatch handler by the function above, 225124208Sdes * which only enables it once the GSSAPI exchange is complete. 226124208Sdes */ 227124208Sdes 228124208Sdesstatic void 229124208Sdesinput_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) 230124208Sdes{ 231124208Sdes Authctxt *authctxt = ctxt; 232124208Sdes Gssctxt *gssctxt; 233124208Sdes int authenticated; 234124208Sdes 235124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 236124208Sdes fatal("No authentication or GSSAPI context"); 237124208Sdes 238124208Sdes gssctxt = authctxt->methoddata; 239124208Sdes 240124208Sdes /* 241126274Sdes * We don't need to check the status, because we're only enabled in 242126274Sdes * the dispatcher once the exchange is complete 243124208Sdes */ 244124208Sdes 245124208Sdes packet_check_eom(); 246124208Sdes 247124208Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 248124208Sdes 249124208Sdes authctxt->postponed = 0; 250124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 251124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 252126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 253124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 254248619Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL); 255124208Sdes} 256124208Sdes 257126274Sdesstatic void 258126274Sdesinput_gssapi_mic(int type, u_int32_t plen, void *ctxt) 259126274Sdes{ 260126274Sdes Authctxt *authctxt = ctxt; 261126274Sdes Gssctxt *gssctxt; 262126274Sdes int authenticated = 0; 263126274Sdes Buffer b; 264126274Sdes gss_buffer_desc mic, gssbuf; 265126274Sdes u_int len; 266126274Sdes 267126274Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 268126274Sdes fatal("No authentication or GSSAPI context"); 269126274Sdes 270126274Sdes gssctxt = authctxt->methoddata; 271126274Sdes 272126274Sdes mic.value = packet_get_string(&len); 273126274Sdes mic.length = len; 274126274Sdes 275126274Sdes ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, 276126274Sdes "gssapi-with-mic"); 277126274Sdes 278126274Sdes gssbuf.value = buffer_ptr(&b); 279126274Sdes gssbuf.length = buffer_len(&b); 280126274Sdes 281126274Sdes if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) 282126274Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 283126274Sdes else 284126274Sdes logit("GSSAPI MIC check failed"); 285126274Sdes 286126274Sdes buffer_free(&b); 287126274Sdes xfree(mic.value); 288126274Sdes 289126274Sdes authctxt->postponed = 0; 290126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 291126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 292126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 293126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 294248619Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL); 295126274Sdes} 296126274Sdes 297124208SdesAuthmethod method_gssapi = { 298126274Sdes "gssapi-with-mic", 299124208Sdes userauth_gssapi, 300124208Sdes &options.gss_authentication 301124208Sdes}; 302124208Sdes 303124208Sdes#endif /* GSSAPI */ 304