blob: e61b37becc768b3fa080875f58f302f881a9f45d [file] [log] [blame]
Damien Millere6a74ae2014-02-27 10:17:49 +11001/* $OpenBSD: gss-serv.c,v 1.26 2014/02/26 20:28:44 djm Exp $ */
Darren Tucker0efd1552003-08-26 11:49:55 +10002
3/*
4 * Copyright (c) 2001-2003 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
Damien Millerd7834352006-08-05 12:39:39 +100031#include <sys/types.h>
Darren Tucker8f6d0ed2007-06-12 23:40:39 +100032#include <sys/param.h>
Damien Millerd7834352006-08-05 12:39:39 +100033
Damien Millerded319c2006-09-01 15:38:36 +100034#include <stdarg.h>
Damien Millere3476ed2006-07-24 14:13:33 +100035#include <string.h>
Damien Millerb8fe89c2006-07-24 14:51:00 +100036#include <unistd.h>
Damien Millere3476ed2006-07-24 14:13:33 +100037
Damien Millerb84886b2008-05-19 15:05:07 +100038#include "openbsd-compat/sys-queue.h"
Damien Millerd7834352006-08-05 12:39:39 +100039#include "xmalloc.h"
40#include "buffer.h"
41#include "key.h"
42#include "hostfile.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100043#include "auth.h"
44#include "log.h"
45#include "channels.h"
46#include "session.h"
Damien Miller3f941882006-03-31 23:13:02 +110047#include "misc.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100048
49#include "ssh-gss.h"
50
Darren Tucker0efd1552003-08-26 11:49:55 +100051static ssh_gssapi_client gssapi_client =
52 { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
Damien Miller63ddc892013-07-20 13:35:45 +100053 GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL, NULL}};
Darren Tucker0efd1552003-08-26 11:49:55 +100054
55ssh_gssapi_mech gssapi_null_mech =
56 { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
57
58#ifdef KRB5
59extern ssh_gssapi_mech gssapi_kerberos_mech;
60#endif
61
62ssh_gssapi_mech* supported_mechs[]= {
63#ifdef KRB5
64 &gssapi_kerberos_mech,
65#endif
66 &gssapi_null_mech,
67};
68
Damien Millere6a74ae2014-02-27 10:17:49 +110069/*
70 * ssh_gssapi_supported_oids() can cause sandbox violations, so prepare the
71 * list of supported mechanisms before privsep is set up.
72 */
73static gss_OID_set supported_oids;
74
75void
76ssh_gssapi_prepare_supported_oids(void)
77{
78 ssh_gssapi_supported_oids(&supported_oids);
79}
80
81OM_uint32
82ssh_gssapi_test_oid_supported(OM_uint32 *ms, gss_OID member, int *present)
83{
84 if (supported_oids == NULL)
85 ssh_gssapi_prepare_supported_oids();
86 return gss_test_oid_set_member(ms, member, supported_oids, present);
87}
Darren Tucker8f6d0ed2007-06-12 23:40:39 +100088
89/*
90 * Acquire credentials for a server running on the current host.
91 * Requires that the context structure contains a valid OID
92 */
93
94/* Returns a GSSAPI error code */
95/* Privileged (called from ssh_gssapi_server_ctx) */
96static OM_uint32
97ssh_gssapi_acquire_cred(Gssctxt *ctx)
98{
99 OM_uint32 status;
100 char lname[MAXHOSTNAMELEN];
101 gss_OID_set oidset;
102
103 gss_create_empty_oid_set(&status, &oidset);
104 gss_add_oid_set_member(&status, ctx->oid, &oidset);
105
106 if (gethostname(lname, MAXHOSTNAMELEN)) {
107 gss_release_oid_set(&status, &oidset);
108 return (-1);
109 }
110
111 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
112 gss_release_oid_set(&status, &oidset);
113 return (ctx->major);
114 }
115
116 if ((ctx->major = gss_acquire_cred(&ctx->minor,
117 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL)))
118 ssh_gssapi_error(ctx);
119
120 gss_release_oid_set(&status, &oidset);
121 return (ctx->major);
122}
123
124/* Privileged */
125OM_uint32
126ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
127{
128 if (*ctx)
129 ssh_gssapi_delete_ctx(ctx);
130 ssh_gssapi_build_ctx(ctx);
131 ssh_gssapi_set_oid(*ctx, oid);
132 return (ssh_gssapi_acquire_cred(*ctx));
133}
134
Damien Miller9fac2632005-11-05 15:03:48 +1100135/* Unprivileged */
Darren Tucker0efd1552003-08-26 11:49:55 +1000136void
137ssh_gssapi_supported_oids(gss_OID_set *oidset)
138{
139 int i = 0;
140 OM_uint32 min_status;
141 int present;
142 gss_OID_set supported;
143
144 gss_create_empty_oid_set(&min_status, oidset);
145 gss_indicate_mechs(&min_status, &supported);
146
147 while (supported_mechs[i]->name != NULL) {
148 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
149 &supported_mechs[i]->oid, supported, &present)))
150 present = 0;
151 if (present)
152 gss_add_oid_set_member(&min_status,
153 &supported_mechs[i]->oid, oidset);
154 i++;
155 }
Damien Miller91a2d972006-03-26 00:05:44 +1100156
157 gss_release_oid_set(&min_status, &supported);
Darren Tucker0efd1552003-08-26 11:49:55 +1000158}
159
160
161/* Wrapper around accept_sec_context
162 * Requires that the context contains:
163 * oid
164 * credentials (from ssh_gssapi_acquire_cred)
165 */
Damien Miller9fac2632005-11-05 15:03:48 +1100166/* Privileged */
Darren Tucker0efd1552003-08-26 11:49:55 +1000167OM_uint32
168ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
169 gss_buffer_desc *send_tok, OM_uint32 *flags)
170{
171 OM_uint32 status;
172 gss_OID mech;
173
174 ctx->major = gss_accept_sec_context(&ctx->minor,
175 &ctx->context, ctx->creds, recv_tok,
176 GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
177 send_tok, flags, NULL, &ctx->client_creds);
178
179 if (GSS_ERROR(ctx->major))
180 ssh_gssapi_error(ctx);
181
182 if (ctx->client_creds)
183 debug("Received some client credentials");
184 else
185 debug("Got no client credentials");
186
187 status = ctx->major;
188
189 /* Now, if we're complete and we have the right flags, then
190 * we flag the user as also having been authenticated
191 */
192
193 if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
194 (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
195 if (ssh_gssapi_getclient(ctx, &gssapi_client))
196 fatal("Couldn't convert client name");
197 }
198
199 return (status);
200}
201
202/*
203 * This parses an exported name, extracting the mechanism specific portion
204 * to use for ACL checking. It verifies that the name belongs the mechanism
205 * originally selected.
206 */
207static OM_uint32
208ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
209{
Damien Millereccb9de2005-06-17 12:59:34 +1000210 u_char *tok;
Darren Tucker0efd1552003-08-26 11:49:55 +1000211 OM_uint32 offset;
212 OM_uint32 oidl;
Damien Miller134350c2003-09-02 22:56:42 +1000213
Damien Miller6fd6def2005-11-05 15:07:05 +1100214 tok = ename->value;
Damien Miller134350c2003-09-02 22:56:42 +1000215
216 /*
217 * Check that ename is long enough for all of the fixed length
Darren Tucker0efd1552003-08-26 11:49:55 +1000218 * header, and that the initial ID bytes are correct
219 */
220
Damien Miller6fd6def2005-11-05 15:07:05 +1100221 if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
Darren Tucker0efd1552003-08-26 11:49:55 +1000222 return GSS_S_FAILURE;
223
224 /*
225 * Extract the OID, and check it. Here GSSAPI breaks with tradition
226 * and does use the OID type and length bytes. To confuse things
227 * there are two lengths - the first including these, and the
228 * second without.
229 */
230
Damien Miller3f941882006-03-31 23:13:02 +1100231 oidl = get_u16(tok+2); /* length including next two bytes */
Darren Tucker0efd1552003-08-26 11:49:55 +1000232 oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
233
234 /*
235 * Check the BER encoding for correct type and length, that the
236 * string is long enough and that the OID matches that in our context
237 */
238 if (tok[4] != 0x06 || tok[5] != oidl ||
Damien Miller134350c2003-09-02 22:56:42 +1000239 ename->length < oidl+6 ||
Damien Miller6fd6def2005-11-05 15:07:05 +1100240 !ssh_gssapi_check_oid(ctx, tok+6, oidl))
Darren Tucker0efd1552003-08-26 11:49:55 +1000241 return GSS_S_FAILURE;
242
243 offset = oidl+6;
Damien Miller134350c2003-09-02 22:56:42 +1000244
Darren Tucker0efd1552003-08-26 11:49:55 +1000245 if (ename->length < offset+4)
246 return GSS_S_FAILURE;
Damien Miller134350c2003-09-02 22:56:42 +1000247
Damien Miller3f941882006-03-31 23:13:02 +1100248 name->length = get_u32(tok+offset);
Darren Tucker0efd1552003-08-26 11:49:55 +1000249 offset += 4;
Damien Miller134350c2003-09-02 22:56:42 +1000250
Damien Milleradb467f2011-08-06 06:16:46 +1000251 if (UINT_MAX - offset < name->length)
252 return GSS_S_FAILURE;
Darren Tucker0efd1552003-08-26 11:49:55 +1000253 if (ename->length < offset+name->length)
Damien Miller134350c2003-09-02 22:56:42 +1000254 return GSS_S_FAILURE;
255
Damien Millera0c4ad22003-09-02 22:56:18 +1000256 name->value = xmalloc(name->length+1);
Damien Miller0b70b542006-03-15 11:20:03 +1100257 memcpy(name->value, tok+offset, name->length);
Damien Millera0c4ad22003-09-02 22:56:18 +1000258 ((char *)name->value)[name->length] = 0;
259
Darren Tucker0efd1552003-08-26 11:49:55 +1000260 return GSS_S_COMPLETE;
Damien Miller134350c2003-09-02 22:56:42 +1000261}
Darren Tucker0efd1552003-08-26 11:49:55 +1000262
263/* Extract the client details from a given context. This can only reliably
264 * be called once for a context */
265
Damien Miller9fac2632005-11-05 15:03:48 +1100266/* Privileged (called from accept_secure_ctx) */
Darren Tucker0efd1552003-08-26 11:49:55 +1000267OM_uint32
268ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
269{
270 int i = 0;
271
272 gss_buffer_desc ename;
Damien Miller134350c2003-09-02 22:56:42 +1000273
Darren Tucker0efd1552003-08-26 11:49:55 +1000274 client->mech = NULL;
275
276 while (supported_mechs[i]->name != NULL) {
277 if (supported_mechs[i]->oid.length == ctx->oid->length &&
278 (memcmp(supported_mechs[i]->oid.elements,
279 ctx->oid->elements, ctx->oid->length) == 0))
280 client->mech = supported_mechs[i];
281 i++;
282 }
283
Damien Miller134350c2003-09-02 22:56:42 +1000284 if (client->mech == NULL)
Darren Tucker0efd1552003-08-26 11:49:55 +1000285 return GSS_S_FAILURE;
Damien Miller134350c2003-09-02 22:56:42 +1000286
287 if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
Darren Tucker0efd1552003-08-26 11:49:55 +1000288 &client->displayname, NULL))) {
Damien Miller134350c2003-09-02 22:56:42 +1000289 ssh_gssapi_error(ctx);
290 return (ctx->major);
Darren Tucker0efd1552003-08-26 11:49:55 +1000291 }
Damien Miller134350c2003-09-02 22:56:42 +1000292
293 if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
Darren Tucker0efd1552003-08-26 11:49:55 +1000294 &ename))) {
295 ssh_gssapi_error(ctx);
296 return (ctx->major);
297 }
Damien Miller134350c2003-09-02 22:56:42 +1000298
Darren Tucker0efd1552003-08-26 11:49:55 +1000299 if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
300 &client->exportedname))) {
301 return (ctx->major);
302 }
303
304 /* We can't copy this structure, so we just move the pointer to it */
305 client->creds = ctx->client_creds;
306 ctx->client_creds = GSS_C_NO_CREDENTIAL;
307 return (ctx->major);
308}
309
Darren Tucker3e33cec2003-10-02 16:12:36 +1000310/* As user - called on fatal/exit */
Darren Tucker0efd1552003-08-26 11:49:55 +1000311void
Darren Tucker3e33cec2003-10-02 16:12:36 +1000312ssh_gssapi_cleanup_creds(void)
Darren Tucker0efd1552003-08-26 11:49:55 +1000313{
314 if (gssapi_client.store.filename != NULL) {
315 /* Unlink probably isn't sufficient */
Damien Miller0b70b542006-03-15 11:20:03 +1100316 debug("removing gssapi cred file\"%s\"",
317 gssapi_client.store.filename);
Darren Tucker0efd1552003-08-26 11:49:55 +1000318 unlink(gssapi_client.store.filename);
319 }
320}
321
322/* As user */
323void
324ssh_gssapi_storecreds(void)
325{
326 if (gssapi_client.mech && gssapi_client.mech->storecreds) {
327 (*gssapi_client.mech->storecreds)(&gssapi_client);
Darren Tucker0efd1552003-08-26 11:49:55 +1000328 } else
329 debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
330}
331
332/* This allows GSSAPI methods to do things to the childs environment based
333 * on the passed authentication process and credentials.
334 */
335/* As user */
336void
337ssh_gssapi_do_child(char ***envp, u_int *envsizep)
338{
339
340 if (gssapi_client.store.envvar != NULL &&
341 gssapi_client.store.envval != NULL) {
Darren Tucker0efd1552003-08-26 11:49:55 +1000342 debug("Setting %s to %s", gssapi_client.store.envvar,
Damien Miller6fd6def2005-11-05 15:07:05 +1100343 gssapi_client.store.envval);
Darren Tucker0efd1552003-08-26 11:49:55 +1000344 child_set_env(envp, envsizep, gssapi_client.store.envvar,
Damien Miller0dc1bef2005-07-17 17:22:45 +1000345 gssapi_client.store.envval);
Darren Tucker0efd1552003-08-26 11:49:55 +1000346 }
347}
348
Darren Tucker8813bbb2005-10-03 18:17:02 +1000349/* Privileged */
Darren Tucker0efd1552003-08-26 11:49:55 +1000350int
351ssh_gssapi_userok(char *user)
352{
Damien Millerda9984f2005-08-31 19:46:26 +1000353 OM_uint32 lmin;
354
Darren Tucker0efd1552003-08-26 11:49:55 +1000355 if (gssapi_client.exportedname.length == 0 ||
356 gssapi_client.exportedname.value == NULL) {
357 debug("No suitable client data");
358 return 0;
359 }
360 if (gssapi_client.mech && gssapi_client.mech->userok)
Damien Millerda9984f2005-08-31 19:46:26 +1000361 if ((*gssapi_client.mech->userok)(&gssapi_client, user))
362 return 1;
363 else {
364 /* Destroy delegated credentials if userok fails */
365 gss_release_buffer(&lmin, &gssapi_client.displayname);
366 gss_release_buffer(&lmin, &gssapi_client.exportedname);
367 gss_release_cred(&lmin, &gssapi_client.creds);
Damien Millera5103f42014-02-04 11:20:14 +1100368 explicit_bzero(&gssapi_client,
369 sizeof(ssh_gssapi_client));
Damien Millerda9984f2005-08-31 19:46:26 +1000370 return 0;
371 }
Darren Tucker0efd1552003-08-26 11:49:55 +1000372 else
373 debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
374 return (0);
375}
376
Damien Miller9fac2632005-11-05 15:03:48 +1100377/* Privileged */
Damien Miller0425d402003-11-17 22:18:21 +1100378OM_uint32
379ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
380{
381 ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
382 gssbuf, gssmic, NULL);
383
384 return (ctx->major);
385}
386
Darren Tucker0efd1552003-08-26 11:49:55 +1000387#endif