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>
49 #include "monitor_wrap.h"
51 extern ServerOptions options;
53 static ssh_gssapi_client gssapi_client =
54 { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
55 GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
57 ssh_gssapi_mech gssapi_null_mech =
58 { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
61 extern ssh_gssapi_mech gssapi_kerberos_mech;
64 ssh_gssapi_mech* supported_mechs[]= {
66 &gssapi_kerberos_mech,
73 ssh_gssapi_server_mechanisms() {
74 gss_OID_set supported;
76 ssh_gssapi_supported_oids(&supported);
77 return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech,
83 ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data) {
87 res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid)));
88 ssh_gssapi_delete_ctx(&ctx);
95 ssh_gssapi_supported_oids(gss_OID_set *oidset)
100 gss_OID_set supported;
102 gss_create_empty_oid_set(&min_status, oidset);
103 gss_indicate_mechs(&min_status, &supported);
105 while (supported_mechs[i]->name != NULL) {
106 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
107 &supported_mechs[i]->oid, supported, &present)))
110 gss_add_oid_set_member(&min_status,
111 &supported_mechs[i]->oid, oidset);
115 gss_release_oid_set(&min_status, &supported);
119 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
122 ssh_gssapi_delete_ctx(ctx);
123 ssh_gssapi_build_ctx(ctx);
124 ssh_gssapi_set_oid(*ctx, oid);
125 return (ssh_gssapi_acquire_cred(*ctx));
128 /* Acquire credentials for a server running on the current host.
129 * Requires that the context structure contains a valid OID
132 /* Returns a GSSAPI error code */
134 ssh_gssapi_acquire_cred(Gssctxt *ctx)
137 char lname[MAXHOSTNAMELEN];
140 if (options.gss_strict_acceptor) {
141 gss_create_empty_oid_set(&status, &oidset);
142 gss_add_oid_set_member(&status, ctx->oid, &oidset);
144 if (gethostname(lname, MAXHOSTNAMELEN)) {
145 gss_release_oid_set(&status, &oidset);
149 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
150 gss_release_oid_set(&status, &oidset);
154 if ((ctx->major = gss_acquire_cred(&ctx->minor,
155 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds,
157 ssh_gssapi_error(ctx);
159 gss_release_oid_set(&status, &oidset);
162 ctx->name = GSS_C_NO_NAME;
163 ctx->creds = GSS_C_NO_CREDENTIAL;
165 return GSS_S_COMPLETE;
169 /* Wrapper around accept_sec_context
170 * Requires that the context contains:
172 * credentials (from ssh_gssapi_acquire_cred)
176 ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
177 gss_buffer_desc *send_tok, OM_uint32 *flags)
182 ctx->major = gss_accept_sec_context(&ctx->minor,
183 &ctx->context, ctx->creds, recv_tok,
184 GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
185 send_tok, flags, NULL, &ctx->client_creds);
187 if (GSS_ERROR(ctx->major))
188 ssh_gssapi_error(ctx);
190 if (ctx->client_creds)
191 debug("Received some client credentials");
193 debug("Got no client credentials");
197 /* Now, if we're complete and we have the right flags, then
198 * we flag the user as also having been authenticated
201 if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
202 (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
203 if (ssh_gssapi_getclient(ctx, &gssapi_client))
204 fatal("Couldn't convert client name");
211 * This parses an exported name, extracting the mechanism specific portion
212 * to use for ACL checking. It verifies that the name belongs the mechanism
213 * originally selected.
216 ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
225 * Check that ename is long enough for all of the fixed length
226 * header, and that the initial ID bytes are correct
229 if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
230 return GSS_S_FAILURE;
233 * Extract the OID, and check it. Here GSSAPI breaks with tradition
234 * and does use the OID type and length bytes. To confuse things
235 * there are two lengths - the first including these, and the
239 oidl = get_u16(tok+2); /* length including next two bytes */
240 oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
243 * Check the BER encoding for correct type and length, that the
244 * string is long enough and that the OID matches that in our context
246 if (tok[4] != 0x06 || tok[5] != oidl ||
247 ename->length < oidl+6 ||
248 !ssh_gssapi_check_oid(ctx, tok+6, oidl))
249 return GSS_S_FAILURE;
253 if (ename->length < offset+4)
254 return GSS_S_FAILURE;
256 name->length = get_u32(tok+offset);
259 if (ename->length < offset+name->length)
260 return GSS_S_FAILURE;
262 name->value = xmalloc(name->length+1);
263 memcpy(name->value, tok+offset, name->length);
264 ((char *)name->value)[name->length] = 0;
266 return GSS_S_COMPLETE;
269 /* Extract the client details from a given context. This can only reliably
270 * be called once for a context */
272 /* Privileged (called from accept_secure_ctx) */
274 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
278 gss_buffer_desc ename;
282 while (supported_mechs[i]->name != NULL) {
283 if (supported_mechs[i]->oid.length == ctx->oid->length &&
284 (memcmp(supported_mechs[i]->oid.elements,
285 ctx->oid->elements, ctx->oid->length) == 0))
286 client->mech = supported_mechs[i];
290 if (client->mech == NULL)
291 return GSS_S_FAILURE;
293 if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
294 &client->displayname, NULL))) {
295 ssh_gssapi_error(ctx);
299 if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
301 ssh_gssapi_error(ctx);
305 if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
306 &client->exportedname))) {
310 /* We can't copy this structure, so we just move the pointer to it */
311 client->creds = ctx->client_creds;
312 ctx->client_creds = GSS_C_NO_CREDENTIAL;
316 /* As user - called on fatal/exit */
318 ssh_gssapi_cleanup_creds(void)
320 if (gssapi_client.store.filename != NULL) {
321 /* Unlink probably isn't sufficient */
322 debug("removing gssapi cred file\"%s\"",
323 gssapi_client.store.filename);
324 unlink(gssapi_client.store.filename);
330 ssh_gssapi_storecreds(void)
332 if (gssapi_client.mech && gssapi_client.mech->storecreds) {
333 (*gssapi_client.mech->storecreds)(&gssapi_client);
335 debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
338 /* This allows GSSAPI methods to do things to the childs environment based
339 * on the passed authentication process and credentials.
343 ssh_gssapi_do_child(char ***envp, u_int *envsizep)
346 if (gssapi_client.store.envvar != NULL &&
347 gssapi_client.store.envval != NULL) {
348 debug("Setting %s to %s", gssapi_client.store.envvar,
349 gssapi_client.store.envval);
350 child_set_env(envp, envsizep, gssapi_client.store.envvar,
351 gssapi_client.store.envval);
357 ssh_gssapi_userok(char *user)
361 if (gssapi_client.exportedname.length == 0 ||
362 gssapi_client.exportedname.value == NULL) {
363 debug("No suitable client data");
366 if (gssapi_client.mech && gssapi_client.mech->userok)
367 if ((*gssapi_client.mech->userok)(&gssapi_client, user))
370 /* Destroy delegated credentials if userok fails */
371 gss_release_buffer(&lmin, &gssapi_client.displayname);
372 gss_release_buffer(&lmin, &gssapi_client.exportedname);
373 gss_release_cred(&lmin, &gssapi_client.creds);
374 memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
378 debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");