1 /* $OpenBSD: gss-serv.c,v 1.30 2017/06/24 06:34:38 djm Exp $ */
4 * Copyright (c) 2001-2003 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>
37 #include "openbsd-compat/sys-queue.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, 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,
72 * ssh_gssapi_supported_oids() can cause sandbox violations, so prepare the
73 * list of supported mechanisms before privsep is set up.
75 static gss_OID_set supported_oids;
78 ssh_gssapi_prepare_supported_oids(void)
80 ssh_gssapi_supported_oids(&supported_oids);
84 ssh_gssapi_test_oid_supported(OM_uint32 *ms, gss_OID member, int *present)
86 if (supported_oids == NULL)
87 ssh_gssapi_prepare_supported_oids();
88 return gss_test_oid_set_member(ms, member, supported_oids, present);
92 * Acquire credentials for a server running on the current host.
93 * Requires that the context structure contains a valid OID
96 /* Returns a GSSAPI error code */
97 /* Privileged (called from ssh_gssapi_server_ctx) */
99 ssh_gssapi_acquire_cred(Gssctxt *ctx)
102 char lname[NI_MAXHOST];
105 if (options.gss_strict_acceptor) {
106 gss_create_empty_oid_set(&status, &oidset);
107 gss_add_oid_set_member(&status, ctx->oid, &oidset);
109 if (gethostname(lname, MAXHOSTNAMELEN)) {
110 gss_release_oid_set(&status, &oidset);
114 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
115 gss_release_oid_set(&status, &oidset);
119 if ((ctx->major = gss_acquire_cred(&ctx->minor,
120 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds,
122 ssh_gssapi_error(ctx);
124 gss_release_oid_set(&status, &oidset);
127 ctx->name = GSS_C_NO_NAME;
128 ctx->creds = GSS_C_NO_CREDENTIAL;
130 return GSS_S_COMPLETE;
135 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
138 ssh_gssapi_delete_ctx(ctx);
139 ssh_gssapi_build_ctx(ctx);
140 ssh_gssapi_set_oid(*ctx, oid);
141 return (ssh_gssapi_acquire_cred(*ctx));
146 ssh_gssapi_supported_oids(gss_OID_set *oidset)
149 OM_uint32 min_status;
151 gss_OID_set supported;
153 gss_create_empty_oid_set(&min_status, oidset);
154 gss_indicate_mechs(&min_status, &supported);
156 while (supported_mechs[i]->name != NULL) {
157 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
158 &supported_mechs[i]->oid, supported, &present)))
161 gss_add_oid_set_member(&min_status,
162 &supported_mechs[i]->oid, oidset);
166 gss_release_oid_set(&min_status, &supported);
170 /* Wrapper around accept_sec_context
171 * Requires that the context contains:
173 * credentials (from ssh_gssapi_acquire_cred)
177 ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
178 gss_buffer_desc *send_tok, OM_uint32 *flags)
183 ctx->major = gss_accept_sec_context(&ctx->minor,
184 &ctx->context, ctx->creds, recv_tok,
185 GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
186 send_tok, flags, NULL, &ctx->client_creds);
188 if (GSS_ERROR(ctx->major))
189 ssh_gssapi_error(ctx);
191 if (ctx->client_creds)
192 debug("Received some client credentials");
194 debug("Got no client credentials");
198 /* Now, if we're complete and we have the right flags, then
199 * we flag the user as also having been authenticated
202 if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
203 (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
204 if (ssh_gssapi_getclient(ctx, &gssapi_client))
205 fatal("Couldn't convert client name");
212 * This parses an exported name, extracting the mechanism specific portion
213 * to use for ACL checking. It verifies that the name belongs the mechanism
214 * originally selected.
217 ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
226 * Check that ename is long enough for all of the fixed length
227 * header, and that the initial ID bytes are correct
230 if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
231 return GSS_S_FAILURE;
234 * Extract the OID, and check it. Here GSSAPI breaks with tradition
235 * and does use the OID type and length bytes. To confuse things
236 * there are two lengths - the first including these, and the
240 oidl = get_u16(tok+2); /* length including next two bytes */
241 oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
244 * Check the BER encoding for correct type and length, that the
245 * string is long enough and that the OID matches that in our context
247 if (tok[4] != 0x06 || tok[5] != oidl ||
248 ename->length < oidl+6 ||
249 !ssh_gssapi_check_oid(ctx, tok+6, oidl))
250 return GSS_S_FAILURE;
254 if (ename->length < offset+4)
255 return GSS_S_FAILURE;
257 name->length = get_u32(tok+offset);
260 if (UINT_MAX - offset < name->length)
261 return GSS_S_FAILURE;
262 if (ename->length < offset+name->length)
263 return GSS_S_FAILURE;
265 name->value = xmalloc(name->length+1);
266 memcpy(name->value, tok+offset, name->length);
267 ((char *)name->value)[name->length] = 0;
269 return GSS_S_COMPLETE;
272 /* Extract the client details from a given context. This can only reliably
273 * be called once for a context */
275 /* Privileged (called from accept_secure_ctx) */
277 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
281 gss_buffer_desc ename;
285 while (supported_mechs[i]->name != NULL) {
286 if (supported_mechs[i]->oid.length == ctx->oid->length &&
287 (memcmp(supported_mechs[i]->oid.elements,
288 ctx->oid->elements, ctx->oid->length) == 0))
289 client->mech = supported_mechs[i];
293 if (client->mech == NULL)
294 return GSS_S_FAILURE;
296 if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
297 &client->displayname, NULL))) {
298 ssh_gssapi_error(ctx);
302 if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
304 ssh_gssapi_error(ctx);
308 if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
309 &client->exportedname))) {
313 /* We can't copy this structure, so we just move the pointer to it */
314 client->creds = ctx->client_creds;
315 ctx->client_creds = GSS_C_NO_CREDENTIAL;
319 /* As user - called on fatal/exit */
321 ssh_gssapi_cleanup_creds(void)
323 if (gssapi_client.store.filename != NULL) {
324 /* Unlink probably isn't sufficient */
325 debug("removing gssapi cred file\"%s\"",
326 gssapi_client.store.filename);
327 unlink(gssapi_client.store.filename);
333 ssh_gssapi_storecreds(void)
335 if (gssapi_client.mech && gssapi_client.mech->storecreds) {
336 (*gssapi_client.mech->storecreds)(&gssapi_client);
338 debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
341 /* This allows GSSAPI methods to do things to the childs environment based
342 * on the passed authentication process and credentials.
346 ssh_gssapi_do_child(char ***envp, u_int *envsizep)
349 if (gssapi_client.store.envvar != NULL &&
350 gssapi_client.store.envval != NULL) {
351 debug("Setting %s to %s", gssapi_client.store.envvar,
352 gssapi_client.store.envval);
353 child_set_env(envp, envsizep, gssapi_client.store.envvar,
354 gssapi_client.store.envval);
360 ssh_gssapi_userok(char *user)
364 if (gssapi_client.exportedname.length == 0 ||
365 gssapi_client.exportedname.value == NULL) {
366 debug("No suitable client data");
369 if (gssapi_client.mech && gssapi_client.mech->userok)
370 if ((*gssapi_client.mech->userok)(&gssapi_client, user))
373 /* Destroy delegated credentials if userok fails */
374 gss_release_buffer(&lmin, &gssapi_client.displayname);
375 gss_release_buffer(&lmin, &gssapi_client.exportedname);
376 gss_release_cred(&lmin, &gssapi_client.creds);
377 explicit_bzero(&gssapi_client,
378 sizeof(ssh_gssapi_client));
382 debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
388 ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
390 ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
391 gssbuf, gssmic, NULL);
397 const char *ssh_gssapi_displayname(void)
399 if (gssapi_client.displayname.length == 0 ||
400 gssapi_client.displayname.value == NULL)
402 return (char *)gssapi_client.displayname.value;