1 /* $OpenBSD: gss-genr.c,v 1.17 2006/08/29 12:02:30 dtucker Exp $ */ 2 3 /* 4 * Copyright (c) 2001-2006 Simon Wilkinson. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #ifdef GSSAPI 30 31 #include <sys/types.h> 32 #include <sys/param.h> 33 34 #include <stdarg.h> 35 #include <string.h> 36 #include <unistd.h> 37 38 #include "xmalloc.h" 39 #include "buffer.h" 40 #include "log.h" 41 #include "ssh2.h" 42 43 #include "ssh-gss.h" 44 45 extern u_char *session_id2; 46 extern u_int session_id2_len; 47 48 /* Check that the OID in a data stream matches that in the context */ 49 int 50 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) 51 { 52 return (ctx != NULL && ctx->oid != GSS_C_NO_OID && 53 ctx->oid->length == len && 54 memcmp(ctx->oid->elements, data, len) == 0); 55 } 56 57 /* Set the contexts OID from a data stream */ 58 void 59 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) 60 { 61 if (ctx->oid != GSS_C_NO_OID) { 62 xfree(ctx->oid->elements); 63 xfree(ctx->oid); 64 } 65 ctx->oid = xmalloc(sizeof(gss_OID_desc)); 66 ctx->oid->length = len; 67 ctx->oid->elements = xmalloc(len); 68 memcpy(ctx->oid->elements, data, len); 69 } 70 71 /* Set the contexts OID */ 72 void 73 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) 74 { 75 ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length); 76 } 77 78 /* All this effort to report an error ... */ 79 void 80 ssh_gssapi_error(Gssctxt *ctxt) 81 { 82 char *s; 83 84 s = ssh_gssapi_last_error(ctxt, NULL, NULL); 85 debug("%s", s); 86 xfree(s); 87 } 88 89 char * 90 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status, 91 OM_uint32 *minor_status) 92 { 93 OM_uint32 lmin; 94 gss_buffer_desc msg = GSS_C_EMPTY_BUFFER; 95 OM_uint32 ctx; 96 Buffer b; 97 char *ret; 98 99 buffer_init(&b); 100 101 if (major_status != NULL) 102 *major_status = ctxt->major; 103 if (minor_status != NULL) 104 *minor_status = ctxt->minor; 105 106 ctx = 0; 107 /* The GSSAPI error */ 108 do { 109 gss_display_status(&lmin, ctxt->major, 110 GSS_C_GSS_CODE, GSS_C_NULL_OID, &ctx, &msg); 111 112 buffer_append(&b, msg.value, msg.length); 113 buffer_put_char(&b, '\n'); 114 115 gss_release_buffer(&lmin, &msg); 116 } while (ctx != 0); 117 118 /* The mechanism specific error */ 119 do { 120 gss_display_status(&lmin, ctxt->minor, 121 GSS_C_MECH_CODE, GSS_C_NULL_OID, &ctx, &msg); 122 123 buffer_append(&b, msg.value, msg.length); 124 buffer_put_char(&b, '\n'); 125 126 gss_release_buffer(&lmin, &msg); 127 } while (ctx != 0); 128 129 buffer_put_char(&b, '\0'); 130 ret = xmalloc(buffer_len(&b)); 131 buffer_get(&b, ret, buffer_len(&b)); 132 buffer_free(&b); 133 return (ret); 134 } 135 136 /* 137 * Initialise our GSSAPI context. We use this opaque structure to contain all 138 * of the data which both the client and server need to persist across 139 * {accept,init}_sec_context calls, so that when we do it from the userauth 140 * stuff life is a little easier 141 */ 142 void 143 ssh_gssapi_build_ctx(Gssctxt **ctx) 144 { 145 *ctx = xcalloc(1, sizeof (Gssctxt)); 146 (*ctx)->context = GSS_C_NO_CONTEXT; 147 (*ctx)->name = GSS_C_NO_NAME; 148 (*ctx)->oid = GSS_C_NO_OID; 149 (*ctx)->creds = GSS_C_NO_CREDENTIAL; 150 (*ctx)->client = GSS_C_NO_NAME; 151 (*ctx)->client_creds = GSS_C_NO_CREDENTIAL; 152 } 153 154 /* Delete our context, providing it has been built correctly */ 155 void 156 ssh_gssapi_delete_ctx(Gssctxt **ctx) 157 { 158 OM_uint32 ms; 159 160 if ((*ctx) == NULL) 161 return; 162 if ((*ctx)->context != GSS_C_NO_CONTEXT) 163 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER); 164 if ((*ctx)->name != GSS_C_NO_NAME) 165 gss_release_name(&ms, &(*ctx)->name); 166 if ((*ctx)->oid != GSS_C_NO_OID) { 167 xfree((*ctx)->oid->elements); 168 xfree((*ctx)->oid); 169 (*ctx)->oid = GSS_C_NO_OID; 170 } 171 if ((*ctx)->creds != GSS_C_NO_CREDENTIAL) 172 gss_release_cred(&ms, &(*ctx)->creds); 173 if ((*ctx)->client != GSS_C_NO_NAME) 174 gss_release_name(&ms, &(*ctx)->client); 175 if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL) 176 gss_release_cred(&ms, &(*ctx)->client_creds); 177 178 xfree(*ctx); 179 *ctx = NULL; 180 } 181 182 /* 183 * Wrapper to init_sec_context 184 * Requires that the context contains: 185 * oid 186 * server name (from ssh_gssapi_import_name) 187 */ 188 OM_uint32 189 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, 190 gss_buffer_desc* send_tok, OM_uint32 *flags) 191 { 192 int deleg_flag = 0; 193 194 if (deleg_creds) { 195 deleg_flag = GSS_C_DELEG_FLAG; 196 debug("Delegating credentials"); 197 } 198 199 ctx->major = gss_init_sec_context(&ctx->minor, 200 GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, 201 GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, 202 0, NULL, recv_tok, NULL, send_tok, flags, NULL); 203 204 if (GSS_ERROR(ctx->major)) 205 ssh_gssapi_error(ctx); 206 207 return (ctx->major); 208 } 209 210 /* Create a service name for the given host */ 211 OM_uint32 212 ssh_gssapi_import_name(Gssctxt *ctx, const char *host) 213 { 214 gss_buffer_desc gssbuf; 215 char *val; 216 217 xasprintf(&val, "host@%s", host); 218 gssbuf.value = val; 219 gssbuf.length = strlen(gssbuf.value); 220 221 if ((ctx->major = gss_import_name(&ctx->minor, 222 &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name))) 223 ssh_gssapi_error(ctx); 224 225 xfree(gssbuf.value); 226 return (ctx->major); 227 } 228 229 /* Acquire credentials for a server running on the current host. 230 * Requires that the context structure contains a valid OID 231 */ 232 233 /* Returns a GSSAPI error code */ 234 OM_uint32 235 ssh_gssapi_acquire_cred(Gssctxt *ctx) 236 { 237 OM_uint32 status; 238 char lname[MAXHOSTNAMELEN]; 239 gss_OID_set oidset; 240 241 gss_create_empty_oid_set(&status, &oidset); 242 gss_add_oid_set_member(&status, ctx->oid, &oidset); 243 244 if (gethostname(lname, MAXHOSTNAMELEN)) { 245 gss_release_oid_set(&status, &oidset); 246 return (-1); 247 } 248 249 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) { 250 gss_release_oid_set(&status, &oidset); 251 return (ctx->major); 252 } 253 254 if ((ctx->major = gss_acquire_cred(&ctx->minor, 255 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL))) 256 ssh_gssapi_error(ctx); 257 258 gss_release_oid_set(&status, &oidset); 259 return (ctx->major); 260 } 261 262 OM_uint32 263 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) 264 { 265 if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, 266 GSS_C_QOP_DEFAULT, buffer, hash))) 267 ssh_gssapi_error(ctx); 268 269 return (ctx->major); 270 } 271 272 void 273 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service, 274 const char *context) 275 { 276 buffer_init(b); 277 buffer_put_string(b, session_id2, session_id2_len); 278 buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST); 279 buffer_put_cstring(b, user); 280 buffer_put_cstring(b, service); 281 buffer_put_cstring(b, context); 282 } 283 284 OM_uint32 285 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) 286 { 287 if (*ctx) 288 ssh_gssapi_delete_ctx(ctx); 289 ssh_gssapi_build_ctx(ctx); 290 ssh_gssapi_set_oid(*ctx, oid); 291 return (ssh_gssapi_acquire_cred(*ctx)); 292 } 293 294 int 295 ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host) 296 { 297 gss_buffer_desc token = GSS_C_EMPTY_BUFFER; 298 OM_uint32 major, minor; 299 gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"}; 300 301 /* RFC 4462 says we MUST NOT do SPNEGO */ 302 if (oid->length == spnego_oid.length && 303 (memcmp(oid->elements, spnego_oid.elements, oid->length) == 0)) 304 return 0; /* false */ 305 306 ssh_gssapi_build_ctx(ctx); 307 ssh_gssapi_set_oid(*ctx, oid); 308 major = ssh_gssapi_import_name(*ctx, host); 309 if (!GSS_ERROR(major)) { 310 major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, 311 NULL); 312 gss_release_buffer(&minor, &token); 313 if ((*ctx)->context != GSS_C_NO_CONTEXT) 314 gss_delete_sec_context(&minor, &(*ctx)->context, 315 GSS_C_NO_BUFFER); 316 } 317 318 if (GSS_ERROR(major)) 319 ssh_gssapi_delete_ctx(ctx); 320 321 return (!GSS_ERROR(major)); 322 } 323 324 #endif /* GSSAPI */ 325