gss-serv.c revision 126274
1126274Sdes/* $OpenBSD: gss-serv.c,v 1.5 2003/11/17 11:06:07 markus 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 "bufaux.h" 32124208Sdes#include "compat.h" 33124208Sdes#include "auth.h" 34124208Sdes#include "log.h" 35124208Sdes#include "channels.h" 36124208Sdes#include "session.h" 37124208Sdes#include "servconf.h" 38124208Sdes#include "monitor_wrap.h" 39124208Sdes#include "xmalloc.h" 40124208Sdes#include "getput.h" 41124208Sdes 42124208Sdes#include "ssh-gss.h" 43124208Sdes 44124208Sdesextern ServerOptions options; 45124208Sdes 46124208Sdesstatic ssh_gssapi_client gssapi_client = 47124208Sdes { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, 48124208Sdes GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; 49124208Sdes 50124208Sdesssh_gssapi_mech gssapi_null_mech = 51124208Sdes { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; 52124208Sdes 53124208Sdes#ifdef KRB5 54124208Sdesextern ssh_gssapi_mech gssapi_kerberos_mech; 55124208Sdes#endif 56124208Sdes 57124208Sdesssh_gssapi_mech* supported_mechs[]= { 58124208Sdes#ifdef KRB5 59124208Sdes &gssapi_kerberos_mech, 60124208Sdes#endif 61124208Sdes &gssapi_null_mech, 62124208Sdes}; 63124208Sdes 64124208Sdes/* Unpriviledged */ 65124208Sdesvoid 66124208Sdesssh_gssapi_supported_oids(gss_OID_set *oidset) 67124208Sdes{ 68124208Sdes int i = 0; 69124208Sdes OM_uint32 min_status; 70124208Sdes int present; 71124208Sdes gss_OID_set supported; 72124208Sdes 73124208Sdes gss_create_empty_oid_set(&min_status, oidset); 74124208Sdes gss_indicate_mechs(&min_status, &supported); 75124208Sdes 76124208Sdes while (supported_mechs[i]->name != NULL) { 77124208Sdes if (GSS_ERROR(gss_test_oid_set_member(&min_status, 78124208Sdes &supported_mechs[i]->oid, supported, &present))) 79124208Sdes present = 0; 80124208Sdes if (present) 81124208Sdes gss_add_oid_set_member(&min_status, 82124208Sdes &supported_mechs[i]->oid, oidset); 83124208Sdes i++; 84124208Sdes } 85124208Sdes} 86124208Sdes 87124208Sdes 88124208Sdes/* Wrapper around accept_sec_context 89124208Sdes * Requires that the context contains: 90124208Sdes * oid 91124208Sdes * credentials (from ssh_gssapi_acquire_cred) 92124208Sdes */ 93124208Sdes/* Priviledged */ 94124208SdesOM_uint32 95124208Sdesssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, 96124208Sdes gss_buffer_desc *send_tok, OM_uint32 *flags) 97124208Sdes{ 98124208Sdes OM_uint32 status; 99124208Sdes gss_OID mech; 100124208Sdes 101124208Sdes ctx->major = gss_accept_sec_context(&ctx->minor, 102124208Sdes &ctx->context, ctx->creds, recv_tok, 103124208Sdes GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, 104124208Sdes send_tok, flags, NULL, &ctx->client_creds); 105124208Sdes 106124208Sdes if (GSS_ERROR(ctx->major)) 107124208Sdes ssh_gssapi_error(ctx); 108124208Sdes 109124208Sdes if (ctx->client_creds) 110124208Sdes debug("Received some client credentials"); 111124208Sdes else 112124208Sdes debug("Got no client credentials"); 113124208Sdes 114124208Sdes status = ctx->major; 115124208Sdes 116124208Sdes /* Now, if we're complete and we have the right flags, then 117124208Sdes * we flag the user as also having been authenticated 118124208Sdes */ 119124208Sdes 120124208Sdes if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && 121124208Sdes (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { 122124208Sdes if (ssh_gssapi_getclient(ctx, &gssapi_client)) 123124208Sdes fatal("Couldn't convert client name"); 124124208Sdes } 125124208Sdes 126124208Sdes return (status); 127124208Sdes} 128124208Sdes 129124208Sdes/* 130124208Sdes * This parses an exported name, extracting the mechanism specific portion 131124208Sdes * to use for ACL checking. It verifies that the name belongs the mechanism 132124208Sdes * originally selected. 133124208Sdes */ 134124208Sdesstatic OM_uint32 135124208Sdesssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) 136124208Sdes{ 137124208Sdes char *tok; 138124208Sdes OM_uint32 offset; 139124208Sdes OM_uint32 oidl; 140124208Sdes 141124208Sdes tok=ename->value; 142124208Sdes 143124208Sdes /* 144124208Sdes * Check that ename is long enough for all of the fixed length 145124208Sdes * header, and that the initial ID bytes are correct 146124208Sdes */ 147124208Sdes 148124208Sdes if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0) 149124208Sdes return GSS_S_FAILURE; 150124208Sdes 151124208Sdes /* 152124208Sdes * Extract the OID, and check it. Here GSSAPI breaks with tradition 153124208Sdes * and does use the OID type and length bytes. To confuse things 154124208Sdes * there are two lengths - the first including these, and the 155124208Sdes * second without. 156124208Sdes */ 157124208Sdes 158124208Sdes oidl = GET_16BIT(tok+2); /* length including next two bytes */ 159124208Sdes oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ 160124208Sdes 161124208Sdes /* 162124208Sdes * Check the BER encoding for correct type and length, that the 163124208Sdes * string is long enough and that the OID matches that in our context 164124208Sdes */ 165124208Sdes if (tok[4] != 0x06 || tok[5] != oidl || 166124208Sdes ename->length < oidl+6 || 167124208Sdes !ssh_gssapi_check_oid(ctx,tok+6,oidl)) 168124208Sdes return GSS_S_FAILURE; 169124208Sdes 170124208Sdes offset = oidl+6; 171124208Sdes 172124208Sdes if (ename->length < offset+4) 173124208Sdes return GSS_S_FAILURE; 174124208Sdes 175124208Sdes name->length = GET_32BIT(tok+offset); 176124208Sdes offset += 4; 177124208Sdes 178124208Sdes if (ename->length < offset+name->length) 179124208Sdes return GSS_S_FAILURE; 180124208Sdes 181124208Sdes name->value = xmalloc(name->length+1); 182124208Sdes memcpy(name->value,tok+offset,name->length); 183124208Sdes ((char *)name->value)[name->length] = 0; 184124208Sdes 185124208Sdes return GSS_S_COMPLETE; 186124208Sdes} 187124208Sdes 188124208Sdes/* Extract the client details from a given context. This can only reliably 189124208Sdes * be called once for a context */ 190124208Sdes 191124208Sdes/* Priviledged (called from accept_secure_ctx) */ 192124208SdesOM_uint32 193124208Sdesssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) 194124208Sdes{ 195124208Sdes int i = 0; 196124208Sdes 197124208Sdes gss_buffer_desc ename; 198124208Sdes 199124208Sdes client->mech = NULL; 200124208Sdes 201124208Sdes while (supported_mechs[i]->name != NULL) { 202124208Sdes if (supported_mechs[i]->oid.length == ctx->oid->length && 203124208Sdes (memcmp(supported_mechs[i]->oid.elements, 204124208Sdes ctx->oid->elements, ctx->oid->length) == 0)) 205124208Sdes client->mech = supported_mechs[i]; 206124208Sdes i++; 207124208Sdes } 208124208Sdes 209124208Sdes if (client->mech == NULL) 210124208Sdes return GSS_S_FAILURE; 211124208Sdes 212124208Sdes if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, 213124208Sdes &client->displayname, NULL))) { 214124208Sdes ssh_gssapi_error(ctx); 215124208Sdes return (ctx->major); 216124208Sdes } 217124208Sdes 218124208Sdes if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, 219124208Sdes &ename))) { 220124208Sdes ssh_gssapi_error(ctx); 221124208Sdes return (ctx->major); 222124208Sdes } 223124208Sdes 224124208Sdes if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, 225124208Sdes &client->exportedname))) { 226124208Sdes return (ctx->major); 227124208Sdes } 228124208Sdes 229124208Sdes /* We can't copy this structure, so we just move the pointer to it */ 230124208Sdes client->creds = ctx->client_creds; 231124208Sdes ctx->client_creds = GSS_C_NO_CREDENTIAL; 232124208Sdes return (ctx->major); 233124208Sdes} 234124208Sdes 235126274Sdes/* As user - called on fatal/exit */ 236124208Sdesvoid 237126274Sdesssh_gssapi_cleanup_creds(void) 238124208Sdes{ 239124208Sdes if (gssapi_client.store.filename != NULL) { 240124208Sdes /* Unlink probably isn't sufficient */ 241124208Sdes debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename); 242124208Sdes unlink(gssapi_client.store.filename); 243124208Sdes } 244124208Sdes} 245124208Sdes 246124208Sdes/* As user */ 247124208Sdesvoid 248124208Sdesssh_gssapi_storecreds(void) 249124208Sdes{ 250124208Sdes if (gssapi_client.mech && gssapi_client.mech->storecreds) { 251124208Sdes (*gssapi_client.mech->storecreds)(&gssapi_client); 252124208Sdes } else 253124208Sdes debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); 254124208Sdes} 255124208Sdes 256124208Sdes/* This allows GSSAPI methods to do things to the childs environment based 257124208Sdes * on the passed authentication process and credentials. 258124208Sdes */ 259124208Sdes/* As user */ 260124208Sdesvoid 261124208Sdesssh_gssapi_do_child(char ***envp, u_int *envsizep) 262124208Sdes{ 263124208Sdes 264124208Sdes if (gssapi_client.store.envvar != NULL && 265124208Sdes gssapi_client.store.envval != NULL) { 266124208Sdes 267124208Sdes debug("Setting %s to %s", gssapi_client.store.envvar, 268124208Sdes gssapi_client.store.envval); 269124208Sdes child_set_env(envp, envsizep, gssapi_client.store.envvar, 270124208Sdes gssapi_client.store.envval); 271124208Sdes } 272124208Sdes} 273124208Sdes 274124208Sdes/* Priviledged */ 275124208Sdesint 276124208Sdesssh_gssapi_userok(char *user) 277124208Sdes{ 278124208Sdes if (gssapi_client.exportedname.length == 0 || 279124208Sdes gssapi_client.exportedname.value == NULL) { 280124208Sdes debug("No suitable client data"); 281124208Sdes return 0; 282124208Sdes } 283124208Sdes if (gssapi_client.mech && gssapi_client.mech->userok) 284124208Sdes return ((*gssapi_client.mech->userok)(&gssapi_client, user)); 285124208Sdes else 286124208Sdes debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); 287124208Sdes return (0); 288124208Sdes} 289124208Sdes 290126274Sdes/* Priviledged */ 291126274SdesOM_uint32 292126274Sdesssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) 293126274Sdes{ 294126274Sdes ctx->major = gss_verify_mic(&ctx->minor, ctx->context, 295126274Sdes gssbuf, gssmic, NULL); 296126274Sdes 297126274Sdes return (ctx->major); 298126274Sdes} 299126274Sdes 300124208Sdes#endif 301