1264377Sdes/* $OpenBSD: auth2-gss.c,v 1.21 2014/02/26 20:28:44 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 int present; 66124208Sdes OM_uint32 ms; 67124208Sdes u_int len; 68149749Sdes u_char *doid = NULL; 69124208Sdes 70124208Sdes if (!authctxt->valid || authctxt->user == NULL) 71124208Sdes return (0); 72124208Sdes 73124208Sdes mechs = packet_get_int(); 74124208Sdes if (mechs == 0) { 75124208Sdes debug("Mechanism negotiation is not supported"); 76124208Sdes return (0); 77124208Sdes } 78124208Sdes 79124208Sdes do { 80124208Sdes mechs--; 81124208Sdes 82255767Sdes free(doid); 83124208Sdes 84126274Sdes present = 0; 85124208Sdes doid = packet_get_string(&len); 86124208Sdes 87149749Sdes if (len > 2 && doid[0] == SSH_GSS_OIDTYPE && 88149749Sdes doid[1] == len - 2) { 89137015Sdes goid.elements = doid + 2; 90137015Sdes goid.length = len - 2; 91264377Sdes ssh_gssapi_test_oid_supported(&ms, &goid, &present); 92126274Sdes } else { 93126274Sdes logit("Badly formed OID received"); 94124208Sdes } 95124208Sdes } while (mechs > 0 && !present); 96124208Sdes 97124208Sdes if (!present) { 98255767Sdes free(doid); 99226046Sdes authctxt->server_caused_failure = 1; 100124208Sdes return (0); 101124208Sdes } 102124208Sdes 103137015Sdes if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) { 104162852Sdes if (ctxt != NULL) 105162852Sdes ssh_gssapi_delete_ctx(&ctxt); 106255767Sdes free(doid); 107226046Sdes authctxt->server_caused_failure = 1; 108124208Sdes return (0); 109124208Sdes } 110124208Sdes 111157016Sdes authctxt->methoddata = (void *)ctxt; 112124208Sdes 113124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); 114124208Sdes 115126274Sdes /* Return the OID that we received */ 116124208Sdes packet_put_string(doid, len); 117124208Sdes 118124208Sdes packet_send(); 119255767Sdes free(doid); 120124208Sdes 121124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 122124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 123124208Sdes authctxt->postponed = 1; 124124208Sdes 125124208Sdes return (0); 126124208Sdes} 127124208Sdes 128124208Sdesstatic void 129124208Sdesinput_gssapi_token(int type, u_int32_t plen, void *ctxt) 130124208Sdes{ 131124208Sdes Authctxt *authctxt = ctxt; 132124208Sdes Gssctxt *gssctxt; 133124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 134124208Sdes gss_buffer_desc recv_tok; 135126274Sdes OM_uint32 maj_status, min_status, flags; 136124208Sdes u_int len; 137124208Sdes 138124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 139124208Sdes fatal("No authentication or GSSAPI context"); 140124208Sdes 141124208Sdes gssctxt = authctxt->methoddata; 142124208Sdes recv_tok.value = packet_get_string(&len); 143124208Sdes recv_tok.length = len; /* u_int vs. size_t */ 144124208Sdes 145124208Sdes packet_check_eom(); 146124208Sdes 147124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 148126274Sdes &send_tok, &flags)); 149124208Sdes 150255767Sdes free(recv_tok.value); 151124208Sdes 152124208Sdes if (GSS_ERROR(maj_status)) { 153124208Sdes if (send_tok.length != 0) { 154124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 155124208Sdes packet_put_string(send_tok.value, send_tok.length); 156124208Sdes packet_send(); 157124208Sdes } 158124208Sdes authctxt->postponed = 0; 159124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 160248619Sdes userauth_finish(authctxt, 0, "gssapi-with-mic", NULL); 161124208Sdes } else { 162124208Sdes if (send_tok.length != 0) { 163124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 164124208Sdes packet_put_string(send_tok.value, send_tok.length); 165124208Sdes packet_send(); 166124208Sdes } 167124208Sdes if (maj_status == GSS_S_COMPLETE) { 168124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 169126274Sdes if (flags & GSS_C_INTEG_FLAG) 170126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, 171126274Sdes &input_gssapi_mic); 172126274Sdes else 173126274Sdes dispatch_set( 174126274Sdes SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, 175126274Sdes &input_gssapi_exchange_complete); 176124208Sdes } 177124208Sdes } 178124208Sdes 179124208Sdes gss_release_buffer(&min_status, &send_tok); 180124208Sdes} 181124208Sdes 182124208Sdesstatic void 183124208Sdesinput_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 184124208Sdes{ 185124208Sdes Authctxt *authctxt = ctxt; 186124208Sdes Gssctxt *gssctxt; 187124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 188124208Sdes gss_buffer_desc recv_tok; 189124208Sdes OM_uint32 maj_status; 190124208Sdes u_int len; 191124208Sdes 192124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 193124208Sdes fatal("No authentication or GSSAPI context"); 194124208Sdes 195124208Sdes gssctxt = authctxt->methoddata; 196124208Sdes recv_tok.value = packet_get_string(&len); 197124208Sdes recv_tok.length = len; 198124208Sdes 199124208Sdes packet_check_eom(); 200124208Sdes 201124208Sdes /* Push the error token into GSSAPI to see what it says */ 202124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 203124208Sdes &send_tok, NULL)); 204124208Sdes 205255767Sdes free(recv_tok.value); 206124208Sdes 207124208Sdes /* We can't return anything to the client, even if we wanted to */ 208124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 209124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 210124208Sdes 211124208Sdes /* The client will have already moved on to the next auth */ 212124208Sdes 213124208Sdes gss_release_buffer(&maj_status, &send_tok); 214124208Sdes} 215124208Sdes 216124208Sdes/* 217124208Sdes * This is called when the client thinks we've completed authentication. 218124208Sdes * It should only be enabled in the dispatch handler by the function above, 219124208Sdes * which only enables it once the GSSAPI exchange is complete. 220124208Sdes */ 221124208Sdes 222124208Sdesstatic void 223124208Sdesinput_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) 224124208Sdes{ 225124208Sdes Authctxt *authctxt = ctxt; 226124208Sdes int authenticated; 227124208Sdes 228124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 229124208Sdes fatal("No authentication or GSSAPI context"); 230124208Sdes 231124208Sdes /* 232126274Sdes * We don't need to check the status, because we're only enabled in 233126274Sdes * the dispatcher once the exchange is complete 234124208Sdes */ 235124208Sdes 236124208Sdes packet_check_eom(); 237124208Sdes 238124208Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 239124208Sdes 240124208Sdes authctxt->postponed = 0; 241124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 242124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 243126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 244124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 245248619Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL); 246124208Sdes} 247124208Sdes 248126274Sdesstatic void 249126274Sdesinput_gssapi_mic(int type, u_int32_t plen, void *ctxt) 250126274Sdes{ 251126274Sdes Authctxt *authctxt = ctxt; 252126274Sdes Gssctxt *gssctxt; 253126274Sdes int authenticated = 0; 254126274Sdes Buffer b; 255126274Sdes gss_buffer_desc mic, gssbuf; 256126274Sdes u_int len; 257126274Sdes 258126274Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 259126274Sdes fatal("No authentication or GSSAPI context"); 260126274Sdes 261126274Sdes gssctxt = authctxt->methoddata; 262126274Sdes 263126274Sdes mic.value = packet_get_string(&len); 264126274Sdes mic.length = len; 265126274Sdes 266126274Sdes ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, 267126274Sdes "gssapi-with-mic"); 268126274Sdes 269126274Sdes gssbuf.value = buffer_ptr(&b); 270126274Sdes gssbuf.length = buffer_len(&b); 271126274Sdes 272126274Sdes if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) 273126274Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 274126274Sdes else 275126274Sdes logit("GSSAPI MIC check failed"); 276126274Sdes 277126274Sdes buffer_free(&b); 278255767Sdes free(mic.value); 279126274Sdes 280126274Sdes authctxt->postponed = 0; 281126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 282126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 283126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 284126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 285248619Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL); 286126274Sdes} 287126274Sdes 288124208SdesAuthmethod method_gssapi = { 289126274Sdes "gssapi-with-mic", 290124208Sdes userauth_gssapi, 291124208Sdes &options.gss_authentication 292124208Sdes}; 293124208Sdes 294124208Sdes#endif /* GSSAPI */ 295