auth2-gss.c revision 137015
1137015Sdes/* $OpenBSD: auth2-gss.c,v 1.8 2004/06/21 17:36:31 avsm 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 31124208Sdes#include "auth.h" 32124208Sdes#include "ssh2.h" 33124208Sdes#include "xmalloc.h" 34124208Sdes#include "log.h" 35124208Sdes#include "dispatch.h" 36124208Sdes#include "servconf.h" 37124208Sdes#include "compat.h" 38124208Sdes#include "packet.h" 39124208Sdes#include "monitor_wrap.h" 40124208Sdes 41124208Sdes#include "ssh-gss.h" 42124208Sdes 43124208Sdesextern ServerOptions options; 44124208Sdes 45124208Sdesstatic void input_gssapi_token(int type, u_int32_t plen, void *ctxt); 46126274Sdesstatic void input_gssapi_mic(int type, u_int32_t plen, void *ctxt); 47124208Sdesstatic void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt); 48124208Sdesstatic void input_gssapi_errtok(int, u_int32_t, void *); 49124208Sdes 50124208Sdes/* 51124208Sdes * We only support those mechanisms that we know about (ie ones that we know 52124208Sdes * how to check local user kuserok and the like 53124208Sdes */ 54124208Sdesstatic int 55124208Sdesuserauth_gssapi(Authctxt *authctxt) 56124208Sdes{ 57137015Sdes gss_OID_desc goid = {0, NULL}; 58124208Sdes Gssctxt *ctxt = NULL; 59124208Sdes int mechs; 60124208Sdes gss_OID_set supported; 61124208Sdes int present; 62124208Sdes OM_uint32 ms; 63124208Sdes u_int len; 64124208Sdes char *doid = NULL; 65124208Sdes 66124208Sdes if (!authctxt->valid || authctxt->user == NULL) 67124208Sdes return (0); 68124208Sdes 69124208Sdes mechs = packet_get_int(); 70124208Sdes if (mechs == 0) { 71124208Sdes debug("Mechanism negotiation is not supported"); 72124208Sdes return (0); 73124208Sdes } 74124208Sdes 75124208Sdes ssh_gssapi_supported_oids(&supported); 76124208Sdes do { 77124208Sdes mechs--; 78124208Sdes 79124208Sdes if (doid) 80124208Sdes xfree(doid); 81124208Sdes 82126274Sdes present = 0; 83124208Sdes doid = packet_get_string(&len); 84124208Sdes 85126274Sdes if (len > 2 && 86126274Sdes doid[0] == SSH_GSS_OIDTYPE && 87126274Sdes doid[1] == len - 2) { 88137015Sdes goid.elements = doid + 2; 89137015Sdes goid.length = len - 2; 90137015Sdes gss_test_oid_set_member(&ms, &goid, supported, 91126274Sdes &present); 92126274Sdes } else { 93126274Sdes logit("Badly formed OID received"); 94124208Sdes } 95124208Sdes } while (mechs > 0 && !present); 96124208Sdes 97124208Sdes gss_release_oid_set(&ms, &supported); 98124208Sdes 99124208Sdes if (!present) { 100124208Sdes xfree(doid); 101124208Sdes return (0); 102124208Sdes } 103124208Sdes 104137015Sdes if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) { 105124208Sdes xfree(doid); 106124208Sdes return (0); 107124208Sdes } 108124208Sdes 109124208Sdes authctxt->methoddata=(void *)ctxt; 110124208Sdes 111124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); 112124208Sdes 113126274Sdes /* Return the OID that we received */ 114124208Sdes packet_put_string(doid, len); 115124208Sdes 116124208Sdes packet_send(); 117124208Sdes xfree(doid); 118124208Sdes 119124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); 120124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); 121124208Sdes authctxt->postponed = 1; 122124208Sdes 123124208Sdes return (0); 124124208Sdes} 125124208Sdes 126124208Sdesstatic void 127124208Sdesinput_gssapi_token(int type, u_int32_t plen, void *ctxt) 128124208Sdes{ 129124208Sdes Authctxt *authctxt = ctxt; 130124208Sdes Gssctxt *gssctxt; 131124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 132124208Sdes gss_buffer_desc recv_tok; 133126274Sdes OM_uint32 maj_status, min_status, flags; 134124208Sdes u_int len; 135124208Sdes 136124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 137124208Sdes fatal("No authentication or GSSAPI context"); 138124208Sdes 139124208Sdes gssctxt = authctxt->methoddata; 140124208Sdes recv_tok.value = packet_get_string(&len); 141124208Sdes recv_tok.length = len; /* u_int vs. size_t */ 142124208Sdes 143124208Sdes packet_check_eom(); 144124208Sdes 145124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 146126274Sdes &send_tok, &flags)); 147124208Sdes 148124208Sdes xfree(recv_tok.value); 149124208Sdes 150124208Sdes if (GSS_ERROR(maj_status)) { 151124208Sdes if (send_tok.length != 0) { 152124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); 153124208Sdes packet_put_string(send_tok.value, send_tok.length); 154124208Sdes packet_send(); 155124208Sdes } 156124208Sdes authctxt->postponed = 0; 157124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 158126274Sdes userauth_finish(authctxt, 0, "gssapi-with-mic"); 159124208Sdes } else { 160124208Sdes if (send_tok.length != 0) { 161124208Sdes packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); 162124208Sdes packet_put_string(send_tok.value, send_tok.length); 163124208Sdes packet_send(); 164124208Sdes } 165124208Sdes if (maj_status == GSS_S_COMPLETE) { 166124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 167126274Sdes if (flags & GSS_C_INTEG_FLAG) 168126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, 169126274Sdes &input_gssapi_mic); 170126274Sdes else 171126274Sdes dispatch_set( 172126274Sdes SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, 173126274Sdes &input_gssapi_exchange_complete); 174124208Sdes } 175124208Sdes } 176124208Sdes 177124208Sdes gss_release_buffer(&min_status, &send_tok); 178124208Sdes} 179124208Sdes 180124208Sdesstatic void 181124208Sdesinput_gssapi_errtok(int type, u_int32_t plen, void *ctxt) 182124208Sdes{ 183124208Sdes Authctxt *authctxt = ctxt; 184124208Sdes Gssctxt *gssctxt; 185124208Sdes gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; 186124208Sdes gss_buffer_desc recv_tok; 187124208Sdes OM_uint32 maj_status; 188124208Sdes u_int len; 189124208Sdes 190124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 191124208Sdes fatal("No authentication or GSSAPI context"); 192124208Sdes 193124208Sdes gssctxt = authctxt->methoddata; 194124208Sdes recv_tok.value = packet_get_string(&len); 195124208Sdes recv_tok.length = len; 196124208Sdes 197124208Sdes packet_check_eom(); 198124208Sdes 199124208Sdes /* Push the error token into GSSAPI to see what it says */ 200124208Sdes maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, 201124208Sdes &send_tok, NULL)); 202124208Sdes 203124208Sdes xfree(recv_tok.value); 204124208Sdes 205124208Sdes /* We can't return anything to the client, even if we wanted to */ 206124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 207124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 208124208Sdes 209124208Sdes /* The client will have already moved on to the next auth */ 210124208Sdes 211124208Sdes gss_release_buffer(&maj_status, &send_tok); 212124208Sdes} 213124208Sdes 214124208Sdes/* 215124208Sdes * This is called when the client thinks we've completed authentication. 216124208Sdes * It should only be enabled in the dispatch handler by the function above, 217124208Sdes * which only enables it once the GSSAPI exchange is complete. 218124208Sdes */ 219124208Sdes 220124208Sdesstatic void 221124208Sdesinput_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) 222124208Sdes{ 223124208Sdes Authctxt *authctxt = ctxt; 224124208Sdes Gssctxt *gssctxt; 225124208Sdes int authenticated; 226124208Sdes 227124208Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 228124208Sdes fatal("No authentication or GSSAPI context"); 229124208Sdes 230124208Sdes gssctxt = authctxt->methoddata; 231124208Sdes 232124208Sdes /* 233126274Sdes * We don't need to check the status, because we're only enabled in 234126274Sdes * the dispatcher once the exchange is complete 235124208Sdes */ 236124208Sdes 237124208Sdes packet_check_eom(); 238124208Sdes 239124208Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 240124208Sdes 241124208Sdes authctxt->postponed = 0; 242124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 243124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 244126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 245124208Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 246126274Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic"); 247124208Sdes} 248124208Sdes 249126274Sdesstatic void 250126274Sdesinput_gssapi_mic(int type, u_int32_t plen, void *ctxt) 251126274Sdes{ 252126274Sdes Authctxt *authctxt = ctxt; 253126274Sdes Gssctxt *gssctxt; 254126274Sdes int authenticated = 0; 255126274Sdes Buffer b; 256126274Sdes gss_buffer_desc mic, gssbuf; 257126274Sdes u_int len; 258126274Sdes 259126274Sdes if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) 260126274Sdes fatal("No authentication or GSSAPI context"); 261126274Sdes 262126274Sdes gssctxt = authctxt->methoddata; 263126274Sdes 264126274Sdes mic.value = packet_get_string(&len); 265126274Sdes mic.length = len; 266126274Sdes 267126274Sdes ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, 268126274Sdes "gssapi-with-mic"); 269126274Sdes 270126274Sdes gssbuf.value = buffer_ptr(&b); 271126274Sdes gssbuf.length = buffer_len(&b); 272126274Sdes 273126274Sdes if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) 274126274Sdes authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); 275126274Sdes else 276126274Sdes logit("GSSAPI MIC check failed"); 277126274Sdes 278126274Sdes buffer_free(&b); 279126274Sdes xfree(mic.value); 280126274Sdes 281126274Sdes authctxt->postponed = 0; 282126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 283126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); 284126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); 285126274Sdes dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 286126274Sdes userauth_finish(authctxt, authenticated, "gssapi-with-mic"); 287126274Sdes} 288126274Sdes 289124208SdesAuthmethod method_gssapi = { 290126274Sdes "gssapi-with-mic", 291124208Sdes userauth_gssapi, 292124208Sdes &options.gss_authentication 293124208Sdes}; 294124208Sdes 295124208Sdes#endif /* GSSAPI */ 296