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Darren Tucker8f6d0ed2007-06-12 23:40:39 +10001/* $OpenBSD: gss-serv.c,v 1.21 2007/06/12 08:20:00 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 Millerd7834352006-08-05 12:39:39 +100038#include "xmalloc.h"
39#include "buffer.h"
40#include "key.h"
41#include "hostfile.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100042#include "auth.h"
43#include "log.h"
44#include "channels.h"
45#include "session.h"
Damien Miller3f941882006-03-31 23:13:02 +110046#include "misc.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100047
48#include "ssh-gss.h"
49
Darren Tucker0efd1552003-08-26 11:49:55 +100050static ssh_gssapi_client gssapi_client =
51 { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER,
52 GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}};
53
54ssh_gssapi_mech gssapi_null_mech =
55 { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL};
56
57#ifdef KRB5
58extern ssh_gssapi_mech gssapi_kerberos_mech;
59#endif
60
61ssh_gssapi_mech* supported_mechs[]= {
62#ifdef KRB5
63 &gssapi_kerberos_mech,
64#endif
65 &gssapi_null_mech,
66};
67
Darren Tucker8f6d0ed2007-06-12 23:40:39 +100068
69/*
70 * Acquire credentials for a server running on the current host.
71 * Requires that the context structure contains a valid OID
72 */
73
74/* Returns a GSSAPI error code */
75/* Privileged (called from ssh_gssapi_server_ctx) */
76static OM_uint32
77ssh_gssapi_acquire_cred(Gssctxt *ctx)
78{
79 OM_uint32 status;
80 char lname[MAXHOSTNAMELEN];
81 gss_OID_set oidset;
82
83 gss_create_empty_oid_set(&status, &oidset);
84 gss_add_oid_set_member(&status, ctx->oid, &oidset);
85
86 if (gethostname(lname, MAXHOSTNAMELEN)) {
87 gss_release_oid_set(&status, &oidset);
88 return (-1);
89 }
90
91 if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
92 gss_release_oid_set(&status, &oidset);
93 return (ctx->major);
94 }
95
96 if ((ctx->major = gss_acquire_cred(&ctx->minor,
97 ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL)))
98 ssh_gssapi_error(ctx);
99
100 gss_release_oid_set(&status, &oidset);
101 return (ctx->major);
102}
103
104/* Privileged */
105OM_uint32
106ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
107{
108 if (*ctx)
109 ssh_gssapi_delete_ctx(ctx);
110 ssh_gssapi_build_ctx(ctx);
111 ssh_gssapi_set_oid(*ctx, oid);
112 return (ssh_gssapi_acquire_cred(*ctx));
113}
114
Damien Miller9fac2632005-11-05 15:03:48 +1100115/* Unprivileged */
Darren Tucker0efd1552003-08-26 11:49:55 +1000116void
117ssh_gssapi_supported_oids(gss_OID_set *oidset)
118{
119 int i = 0;
120 OM_uint32 min_status;
121 int present;
122 gss_OID_set supported;
123
124 gss_create_empty_oid_set(&min_status, oidset);
125 gss_indicate_mechs(&min_status, &supported);
126
127 while (supported_mechs[i]->name != NULL) {
128 if (GSS_ERROR(gss_test_oid_set_member(&min_status,
129 &supported_mechs[i]->oid, supported, &present)))
130 present = 0;
131 if (present)
132 gss_add_oid_set_member(&min_status,
133 &supported_mechs[i]->oid, oidset);
134 i++;
135 }
Damien Miller91a2d972006-03-26 00:05:44 +1100136
137 gss_release_oid_set(&min_status, &supported);
Darren Tucker0efd1552003-08-26 11:49:55 +1000138}
139
140
141/* Wrapper around accept_sec_context
142 * Requires that the context contains:
143 * oid
144 * credentials (from ssh_gssapi_acquire_cred)
145 */
Damien Miller9fac2632005-11-05 15:03:48 +1100146/* Privileged */
Darren Tucker0efd1552003-08-26 11:49:55 +1000147OM_uint32
148ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok,
149 gss_buffer_desc *send_tok, OM_uint32 *flags)
150{
151 OM_uint32 status;
152 gss_OID mech;
153
154 ctx->major = gss_accept_sec_context(&ctx->minor,
155 &ctx->context, ctx->creds, recv_tok,
156 GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech,
157 send_tok, flags, NULL, &ctx->client_creds);
158
159 if (GSS_ERROR(ctx->major))
160 ssh_gssapi_error(ctx);
161
162 if (ctx->client_creds)
163 debug("Received some client credentials");
164 else
165 debug("Got no client credentials");
166
167 status = ctx->major;
168
169 /* Now, if we're complete and we have the right flags, then
170 * we flag the user as also having been authenticated
171 */
172
173 if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
174 (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) {
175 if (ssh_gssapi_getclient(ctx, &gssapi_client))
176 fatal("Couldn't convert client name");
177 }
178
179 return (status);
180}
181
182/*
183 * This parses an exported name, extracting the mechanism specific portion
184 * to use for ACL checking. It verifies that the name belongs the mechanism
185 * originally selected.
186 */
187static OM_uint32
188ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name)
189{
Damien Millereccb9de2005-06-17 12:59:34 +1000190 u_char *tok;
Darren Tucker0efd1552003-08-26 11:49:55 +1000191 OM_uint32 offset;
192 OM_uint32 oidl;
Damien Miller134350c2003-09-02 22:56:42 +1000193
Damien Miller6fd6def2005-11-05 15:07:05 +1100194 tok = ename->value;
Damien Miller134350c2003-09-02 22:56:42 +1000195
196 /*
197 * Check that ename is long enough for all of the fixed length
Darren Tucker0efd1552003-08-26 11:49:55 +1000198 * header, and that the initial ID bytes are correct
199 */
200
Damien Miller6fd6def2005-11-05 15:07:05 +1100201 if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0)
Darren Tucker0efd1552003-08-26 11:49:55 +1000202 return GSS_S_FAILURE;
203
204 /*
205 * Extract the OID, and check it. Here GSSAPI breaks with tradition
206 * and does use the OID type and length bytes. To confuse things
207 * there are two lengths - the first including these, and the
208 * second without.
209 */
210
Damien Miller3f941882006-03-31 23:13:02 +1100211 oidl = get_u16(tok+2); /* length including next two bytes */
Darren Tucker0efd1552003-08-26 11:49:55 +1000212 oidl = oidl-2; /* turn it into the _real_ length of the variable OID */
213
214 /*
215 * Check the BER encoding for correct type and length, that the
216 * string is long enough and that the OID matches that in our context
217 */
218 if (tok[4] != 0x06 || tok[5] != oidl ||
Damien Miller134350c2003-09-02 22:56:42 +1000219 ename->length < oidl+6 ||
Damien Miller6fd6def2005-11-05 15:07:05 +1100220 !ssh_gssapi_check_oid(ctx, tok+6, oidl))
Darren Tucker0efd1552003-08-26 11:49:55 +1000221 return GSS_S_FAILURE;
222
223 offset = oidl+6;
Damien Miller134350c2003-09-02 22:56:42 +1000224
Darren Tucker0efd1552003-08-26 11:49:55 +1000225 if (ename->length < offset+4)
226 return GSS_S_FAILURE;
Damien Miller134350c2003-09-02 22:56:42 +1000227
Damien Miller3f941882006-03-31 23:13:02 +1100228 name->length = get_u32(tok+offset);
Darren Tucker0efd1552003-08-26 11:49:55 +1000229 offset += 4;
Damien Miller134350c2003-09-02 22:56:42 +1000230
Darren Tucker0efd1552003-08-26 11:49:55 +1000231 if (ename->length < offset+name->length)
Damien Miller134350c2003-09-02 22:56:42 +1000232 return GSS_S_FAILURE;
233
Damien Millera0c4ad22003-09-02 22:56:18 +1000234 name->value = xmalloc(name->length+1);
Damien Miller0b70b542006-03-15 11:20:03 +1100235 memcpy(name->value, tok+offset, name->length);
Damien Millera0c4ad22003-09-02 22:56:18 +1000236 ((char *)name->value)[name->length] = 0;
237
Darren Tucker0efd1552003-08-26 11:49:55 +1000238 return GSS_S_COMPLETE;
Damien Miller134350c2003-09-02 22:56:42 +1000239}
Darren Tucker0efd1552003-08-26 11:49:55 +1000240
241/* Extract the client details from a given context. This can only reliably
242 * be called once for a context */
243
Damien Miller9fac2632005-11-05 15:03:48 +1100244/* Privileged (called from accept_secure_ctx) */
Darren Tucker0efd1552003-08-26 11:49:55 +1000245OM_uint32
246ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client)
247{
248 int i = 0;
249
250 gss_buffer_desc ename;
Damien Miller134350c2003-09-02 22:56:42 +1000251
Darren Tucker0efd1552003-08-26 11:49:55 +1000252 client->mech = NULL;
253
254 while (supported_mechs[i]->name != NULL) {
255 if (supported_mechs[i]->oid.length == ctx->oid->length &&
256 (memcmp(supported_mechs[i]->oid.elements,
257 ctx->oid->elements, ctx->oid->length) == 0))
258 client->mech = supported_mechs[i];
259 i++;
260 }
261
Damien Miller134350c2003-09-02 22:56:42 +1000262 if (client->mech == NULL)
Darren Tucker0efd1552003-08-26 11:49:55 +1000263 return GSS_S_FAILURE;
Damien Miller134350c2003-09-02 22:56:42 +1000264
265 if ((ctx->major = gss_display_name(&ctx->minor, ctx->client,
Darren Tucker0efd1552003-08-26 11:49:55 +1000266 &client->displayname, NULL))) {
Damien Miller134350c2003-09-02 22:56:42 +1000267 ssh_gssapi_error(ctx);
268 return (ctx->major);
Darren Tucker0efd1552003-08-26 11:49:55 +1000269 }
Damien Miller134350c2003-09-02 22:56:42 +1000270
271 if ((ctx->major = gss_export_name(&ctx->minor, ctx->client,
Darren Tucker0efd1552003-08-26 11:49:55 +1000272 &ename))) {
273 ssh_gssapi_error(ctx);
274 return (ctx->major);
275 }
Damien Miller134350c2003-09-02 22:56:42 +1000276
Darren Tucker0efd1552003-08-26 11:49:55 +1000277 if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename,
278 &client->exportedname))) {
279 return (ctx->major);
280 }
281
282 /* We can't copy this structure, so we just move the pointer to it */
283 client->creds = ctx->client_creds;
284 ctx->client_creds = GSS_C_NO_CREDENTIAL;
285 return (ctx->major);
286}
287
Darren Tucker3e33cec2003-10-02 16:12:36 +1000288/* As user - called on fatal/exit */
Darren Tucker0efd1552003-08-26 11:49:55 +1000289void
Darren Tucker3e33cec2003-10-02 16:12:36 +1000290ssh_gssapi_cleanup_creds(void)
Darren Tucker0efd1552003-08-26 11:49:55 +1000291{
292 if (gssapi_client.store.filename != NULL) {
293 /* Unlink probably isn't sufficient */
Damien Miller0b70b542006-03-15 11:20:03 +1100294 debug("removing gssapi cred file\"%s\"",
295 gssapi_client.store.filename);
Darren Tucker0efd1552003-08-26 11:49:55 +1000296 unlink(gssapi_client.store.filename);
297 }
298}
299
300/* As user */
301void
302ssh_gssapi_storecreds(void)
303{
304 if (gssapi_client.mech && gssapi_client.mech->storecreds) {
305 (*gssapi_client.mech->storecreds)(&gssapi_client);
Darren Tucker0efd1552003-08-26 11:49:55 +1000306 } else
307 debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism");
308}
309
310/* This allows GSSAPI methods to do things to the childs environment based
311 * on the passed authentication process and credentials.
312 */
313/* As user */
314void
315ssh_gssapi_do_child(char ***envp, u_int *envsizep)
316{
317
318 if (gssapi_client.store.envvar != NULL &&
319 gssapi_client.store.envval != NULL) {
Darren Tucker0efd1552003-08-26 11:49:55 +1000320 debug("Setting %s to %s", gssapi_client.store.envvar,
Damien Miller6fd6def2005-11-05 15:07:05 +1100321 gssapi_client.store.envval);
Darren Tucker0efd1552003-08-26 11:49:55 +1000322 child_set_env(envp, envsizep, gssapi_client.store.envvar,
Damien Miller0dc1bef2005-07-17 17:22:45 +1000323 gssapi_client.store.envval);
Darren Tucker0efd1552003-08-26 11:49:55 +1000324 }
325}
326
Darren Tucker8813bbb2005-10-03 18:17:02 +1000327/* Privileged */
Darren Tucker0efd1552003-08-26 11:49:55 +1000328int
329ssh_gssapi_userok(char *user)
330{
Damien Millerda9984f2005-08-31 19:46:26 +1000331 OM_uint32 lmin;
332
Darren Tucker0efd1552003-08-26 11:49:55 +1000333 if (gssapi_client.exportedname.length == 0 ||
334 gssapi_client.exportedname.value == NULL) {
335 debug("No suitable client data");
336 return 0;
337 }
338 if (gssapi_client.mech && gssapi_client.mech->userok)
Damien Millerda9984f2005-08-31 19:46:26 +1000339 if ((*gssapi_client.mech->userok)(&gssapi_client, user))
340 return 1;
341 else {
342 /* Destroy delegated credentials if userok fails */
343 gss_release_buffer(&lmin, &gssapi_client.displayname);
344 gss_release_buffer(&lmin, &gssapi_client.exportedname);
345 gss_release_cred(&lmin, &gssapi_client.creds);
346 memset(&gssapi_client, 0, sizeof(ssh_gssapi_client));
347 return 0;
348 }
Darren Tucker0efd1552003-08-26 11:49:55 +1000349 else
350 debug("ssh_gssapi_userok: Unknown GSSAPI mechanism");
351 return (0);
352}
353
Damien Miller9fac2632005-11-05 15:03:48 +1100354/* Privileged */
Damien Miller0425d402003-11-17 22:18:21 +1100355OM_uint32
356ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
357{
358 ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
359 gssbuf, gssmic, NULL);
360
361 return (ctx->major);
362}
363
Darren Tucker0efd1552003-08-26 11:49:55 +1000364#endif