1 /* $OpenBSD: gss-serv.c,v 1.20 2006/08/03 03:34:42 deraadt Exp $ */
4 * Copyright (c) 2001-2006 Simon Wilkinson. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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.
31 #include <sys/types.h>
50 #include "monitor_wrap.h"
52 extern ServerOptions options;
54 static ssh_gssapi_client gssapi_client =
55 { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
56 GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
58 ssh_gssapi_mech gssapi_null_mech =
59 { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
62 extern ssh_gssapi_mech gssapi_kerberos_mech;
65 extern ssh_gssapi_mech gssapi_gsi_mech;
68 ssh_gssapi_mech* supported_mechs[]= {
70 &gssapi_kerberos_mech,
78 #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG
79 static int limited = 0;
84 ssh_gssapi_server_mechanisms() {
85 gss_OID_set supported;
87 ssh_gssapi_supported_oids(&supported);
88 return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech,
94 ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data) {
98 res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid)));
99 ssh_gssapi_delete_ctx(&ctx);
106 ssh_gssapi_supported_oids(gss_OID_set *oidset)
109 OM_uint32 min_status;
111 gss_OID_set supported;
113 gss_create_empty_oid_set(&min_status, oidset);
114 /* Ask priviledged process what mechanisms it supports. */
115 PRIVSEP(gss_indicate_mechs(&min_status, &supported));
117 while (supported_mechs[i]->name != NULL) {
118 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
119 &supported_mechs[i]->oid, supported, &present)))
122 gss_add_oid_set_member(&min_status,
123 &supported_mechs[i]->oid, oidset);
127 gss_release_oid_set(&min_status, &supported);
131 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
134 ssh_gssapi_delete_ctx(ctx);
135 ssh_gssapi_build_ctx(ctx);
136 ssh_gssapi_set_oid(*ctx, oid);
137 return (ssh_gssapi_acquire_cred(*ctx));
140 /* Acquire credentials for a server running on the current host.
141 * Requires that the context structure contains a valid OID
144 /* Returns a GSSAPI error code */
146 ssh_gssapi_acquire_cred(Gssctxt *ctx)
149 char lname[MAXHOSTNAMELEN];
152 if (options.gss_strict_acceptor) {
153 gss_create_empty_oid_set(&status, &oidset);
154 gss_add_oid_set_member(&status, ctx->oid, &oidset);
156 if (gethostname(lname, MAXHOSTNAMELEN)) {
157 gss_release_oid_set(&status, &oidset);
161 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
162 gss_release_oid_set(&status, &oidset);
166 if ((ctx->major = gss_acquire_cred(&ctx->minor,
167 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds,
169 ssh_gssapi_error(ctx);
171 gss_release_oid_set(&status, &oidset);
174 ctx->name = GSS_C_NO_NAME;
175 ctx->creds = GSS_C_NO_CREDENTIAL;
177 return GSS_S_COMPLETE;
181 /* Wrapper around accept_sec_context
182 * Requires that the context contains:
184 * credentials (from ssh_gssapi_acquire_cred)
188 ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
189 gss_buffer_desc *send_tok, OM_uint32 *flags)
194 ctx->major = gss_accept_sec_context(&ctx->minor,
195 &ctx->context, ctx->creds, recv_tok,
196 GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
197 send_tok, flags, NULL, &ctx->client_creds);
199 if (GSS_ERROR(ctx->major))
200 ssh_gssapi_error(ctx);
202 if (ctx->client_creds)
203 debug("Received some client credentials");
205 debug("Got no client credentials");
209 /* Now, if we're complete and we have the right flags, then
210 * we flag the user as also having been authenticated
213 if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
214 (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
215 if (ssh_gssapi_getclient(ctx, &gssapi_client))
216 fatal("Couldn't convert client name");
217 #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG
218 if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG))
227 * This parses an exported name, extracting the mechanism specific portion
228 * to use for ACL checking. It verifies that the name belongs the mechanism
229 * originally selected.
232 ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
240 #ifdef GSI /* GSI gss_export_name() is broken. */
241 if ((ctx->oid->length == gssapi_gsi_mech.oid.length) &&
242 (memcmp(ctx->oid->elements, gssapi_gsi_mech.oid.elements,
243 gssapi_gsi_mech.oid.length) == 0)) {
244 name->length = ename->length;
245 name->value = xmalloc(ename->length+1);
246 memcpy(name->value, ename->value, ename->length);
247 return GSS_S_COMPLETE;
252 * Check that ename is long enough for all of the fixed length
253 * header, and that the initial ID bytes are correct
256 if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
257 return GSS_S_FAILURE;
260 * Extract the OID, and check it. Here GSSAPI breaks with tradition
261 * and does use the OID type and length bytes. To confuse things
262 * there are two lengths - the first including these, and the
266 oidl = get_u16(tok+2); /* length including next two bytes */
267 oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
270 * Check the BER encoding for correct type and length, that the
271 * string is long enough and that the OID matches that in our context
273 if (tok[4] != 0x06 || tok[5] != oidl ||
274 ename->length < oidl+6 ||
275 !ssh_gssapi_check_oid(ctx, tok+6, oidl))
276 return GSS_S_FAILURE;
280 if (ename->length < offset+4)
281 return GSS_S_FAILURE;
283 name->length = get_u32(tok+offset);
286 if (ename->length < offset+name->length)
287 return GSS_S_FAILURE;
289 name->value = xmalloc(name->length+1);
290 memcpy(name->value, tok+offset, name->length);
291 ((char *)name->value)[name->length] = 0;
293 return GSS_S_COMPLETE;
296 /* Extract the client details from a given context. This can only reliably
297 * be called once for a context */
299 /* Privileged (called from accept_secure_ctx) */
301 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
305 gss_buffer_desc ename;
309 while (supported_mechs[i]->name != NULL) {
310 if (supported_mechs[i]->oid.length == ctx->oid->length &&
311 (memcmp(supported_mechs[i]->oid.elements,
312 ctx->oid->elements, ctx->oid->length) == 0))
313 client->mech = supported_mechs[i];
317 if (client->mech == NULL)
318 return GSS_S_FAILURE;
320 if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
321 &client->displayname, NULL))) {
322 ssh_gssapi_error(ctx);
326 if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
328 ssh_gssapi_error(ctx);
332 if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
333 &client->exportedname))) {
337 /* We can't copy this structure, so we just move the pointer to it */
338 client->creds = ctx->client_creds;
339 ctx->client_creds = GSS_C_NO_CREDENTIAL;
341 /* needed for globus_gss_assist_map_and_authorize() */
342 client->context = ctx->context;
347 /* As user - called on fatal/exit */
349 ssh_gssapi_cleanup_creds(void)
351 if (gssapi_client.store.filename != NULL) {
352 /* Unlink probably isn't sufficient */
353 debug("removing gssapi cred file\"%s\"",
354 gssapi_client.store.filename);
355 unlink(gssapi_client.store.filename);
361 ssh_gssapi_storecreds(void)
363 if (gssapi_client.mech && gssapi_client.mech->storecreds) {
364 (*gssapi_client.mech->storecreds)(&gssapi_client);
366 debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
369 /* This allows GSSAPI methods to do things to the childs environment based
370 * on the passed authentication process and credentials.
374 ssh_gssapi_do_child(char ***envp, u_int *envsizep)
377 if (gssapi_client.store.envvar != NULL &&
378 gssapi_client.store.envval != NULL) {
379 debug("Setting %s to %s", gssapi_client.store.envvar,
380 gssapi_client.store.envval);
381 child_set_env(envp, envsizep, gssapi_client.store.envvar,
382 gssapi_client.store.envval);
388 ssh_gssapi_userok(char *user)
392 if (gssapi_client.exportedname.length == 0 ||
393 gssapi_client.exportedname.value == NULL) {
394 debug("No suitable client data");
397 #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG
398 if (limited && options.gsi_allow_limited_proxy != 1) {
399 debug("limited proxy not acceptable for remote login");
403 if (gssapi_client.mech && gssapi_client.mech->userok)
404 if ((*gssapi_client.mech->userok)(&gssapi_client, user))
407 /* Destroy delegated credentials if userok fails */
408 gss_release_buffer(&lmin, &gssapi_client.displayname);
409 gss_release_buffer(&lmin, &gssapi_client.exportedname);
410 gss_release_cred(&lmin, &gssapi_client.creds);
411 memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
415 debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
421 ssh_gssapi_localname(char **user)
424 if (gssapi_client.displayname.length==0 ||
425 gssapi_client.displayname.value==NULL) {
426 debug("No suitable client data");
429 if (gssapi_client.mech && gssapi_client.mech->localname) {
430 return((*gssapi_client.mech->localname)(&gssapi_client,user));
432 debug("Unknown client authentication type");