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30460aeb | 1 | /* $OpenBSD: gss-serv.c,v 1.20 2006/08/03 03:34:42 deraadt Exp $ */ |
7cac2b65 | 2 | |
5598e598 | 3 | /* |
f713db99 | 4 | * Copyright (c) 2001-2006 Simon Wilkinson. All rights reserved. |
5598e598 | 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 | ||
30460aeb | 31 | #include <sys/types.h> |
32 | ||
33 | #include <stdarg.h> | |
34 | #include <string.h> | |
35 | #include <unistd.h> | |
36 | ||
37 | #include "xmalloc.h" | |
38 | #include "buffer.h" | |
39 | #include "key.h" | |
40 | #include "hostfile.h" | |
5598e598 | 41 | #include "auth.h" |
42 | #include "log.h" | |
e5affddc | 43 | #include "channels.h" |
5598e598 | 44 | #include "session.h" |
f713db99 | 45 | #include "misc.h" |
5598e598 | 46 | #include "servconf.h" |
f713db99 | 47 | |
7cac2b65 | 48 | #include "xmalloc.h" |
5598e598 | 49 | #include "ssh-gss.h" |
30460aeb | 50 | #include "monitor_wrap.h" |
5598e598 | 51 | |
bd3336ab | 52 | extern ServerOptions options; |
53 | ||
23987cb8 | 54 | static ssh_gssapi_client gssapi_client = |
7cac2b65 | 55 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
56 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
5598e598 | 57 | |
7cac2b65 | 58 | ssh_gssapi_mech gssapi_null_mech = |
59 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
44a053a3 | 60 | |
5598e598 | 61 | #ifdef KRB5 |
23987cb8 | 62 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
54425c7a | 63 | #endif |
5598e598 | 64 | #ifdef GSI |
23987cb8 | 65 | extern ssh_gssapi_mech gssapi_gsi_mech; |
b311f64e | 66 | #endif |
67 | ||
23987cb8 | 68 | ssh_gssapi_mech* supported_mechs[]= { |
5598e598 | 69 | #ifdef KRB5 |
7cac2b65 | 70 | &gssapi_kerberos_mech, |
5598e598 | 71 | #endif |
72 | #ifdef GSI | |
7cac2b65 | 73 | &gssapi_gsi_mech, |
7b5a625b | 74 | #endif |
7cac2b65 | 75 | &gssapi_null_mech, |
23987cb8 | 76 | }; |
5598e598 | 77 | |
b4cfa386 | 78 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
79 | static int limited = 0; | |
80 | #endif | |
81 | ||
c06c9ae8 | 82 | /* Unprivileged */ |
fe4ad273 | 83 | char * |
84 | ssh_gssapi_server_mechanisms() { | |
85 | gss_OID_set supported; | |
86 | ||
87 | ssh_gssapi_supported_oids(&supported); | |
88 | return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech, | |
89 | NULL)); | |
90 | } | |
91 | ||
c06c9ae8 | 92 | /* Unprivileged */ |
fe4ad273 | 93 | int |
f713db99 | 94 | ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data) { |
95 | Gssctxt *ctx = NULL; | |
fe4ad273 | 96 | int res; |
c06c9ae8 | 97 | |
f713db99 | 98 | res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid))); |
99 | ssh_gssapi_delete_ctx(&ctx); | |
fe4ad273 | 100 | |
101 | return (res); | |
102 | } | |
103 | ||
c06c9ae8 | 104 | /* Unprivileged */ |
7cac2b65 | 105 | void |
106 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
107 | { | |
108 | int i = 0; | |
109 | OM_uint32 min_status; | |
110 | int present; | |
111 | gss_OID_set supported; | |
112 | ||
113 | gss_create_empty_oid_set(&min_status, oidset); | |
186e1568 | 114 | /* Ask priviledged process what mechanisms it supports. */ |
115 | PRIVSEP(gss_indicate_mechs(&min_status, &supported)); | |
7cac2b65 | 116 | |
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))) | |
120 | present = 0; | |
121 | if (present) | |
122 | gss_add_oid_set_member(&min_status, | |
123 | &supported_mechs[i]->oid, oidset); | |
124 | i++; | |
125 | } | |
30460aeb | 126 | |
127 | gss_release_oid_set(&min_status, &supported); | |
7cac2b65 | 128 | } |
129 | ||
f713db99 | 130 | OM_uint32 |
131 | ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) | |
132 | { | |
133 | if (*ctx) | |
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)); | |
138 | } | |
139 | ||
140 | /* Acquire credentials for a server running on the current host. | |
141 | * Requires that the context structure contains a valid OID | |
142 | */ | |
143 | ||
144 | /* Returns a GSSAPI error code */ | |
145 | OM_uint32 | |
146 | ssh_gssapi_acquire_cred(Gssctxt *ctx) | |
147 | { | |
148 | OM_uint32 status; | |
149 | char lname[MAXHOSTNAMELEN]; | |
150 | gss_OID_set oidset; | |
151 | ||
152 | if (options.gss_strict_acceptor) { | |
153 | gss_create_empty_oid_set(&status, &oidset); | |
154 | gss_add_oid_set_member(&status, ctx->oid, &oidset); | |
155 | ||
156 | if (gethostname(lname, MAXHOSTNAMELEN)) { | |
157 | gss_release_oid_set(&status, &oidset); | |
158 | return (-1); | |
159 | } | |
160 | ||
161 | if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) { | |
162 | gss_release_oid_set(&status, &oidset); | |
163 | return (ctx->major); | |
164 | } | |
165 | ||
166 | if ((ctx->major = gss_acquire_cred(&ctx->minor, | |
167 | ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, | |
168 | NULL, NULL))) | |
169 | ssh_gssapi_error(ctx); | |
170 | ||
171 | gss_release_oid_set(&status, &oidset); | |
172 | return (ctx->major); | |
173 | } else { | |
174 | ctx->name = GSS_C_NO_NAME; | |
175 | ctx->creds = GSS_C_NO_CREDENTIAL; | |
176 | } | |
177 | return GSS_S_COMPLETE; | |
178 | } | |
179 | ||
7cac2b65 | 180 | |
181 | /* Wrapper around accept_sec_context | |
182 | * Requires that the context contains: | |
183 | * oid | |
184 | * credentials (from ssh_gssapi_acquire_cred) | |
185 | */ | |
08822d99 | 186 | /* Privileged */ |
7cac2b65 | 187 | OM_uint32 |
188 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
189 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
190 | { | |
191 | OM_uint32 status; | |
192 | gss_OID mech; | |
193 | ||
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); | |
198 | ||
199 | if (GSS_ERROR(ctx->major)) | |
200 | ssh_gssapi_error(ctx); | |
201 | ||
202 | if (ctx->client_creds) | |
203 | debug("Received some client credentials"); | |
204 | else | |
205 | debug("Got no client credentials"); | |
206 | ||
207 | status = ctx->major; | |
208 | ||
209 | /* Now, if we're complete and we have the right flags, then | |
210 | * we flag the user as also having been authenticated | |
211 | */ | |
212 | ||
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"); | |
b4cfa386 | 217 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
218 | if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG)) | |
219 | limited=1; | |
220 | #endif | |
7cac2b65 | 221 | } |
222 | ||
223 | return (status); | |
224 | } | |
225 | ||
226 | /* | |
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. | |
230 | */ | |
231 | static OM_uint32 | |
232 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
233 | { | |
2ce0bfe4 | 234 | u_char *tok; |
7cac2b65 | 235 | OM_uint32 offset; |
236 | OM_uint32 oidl; | |
237 | ||
08822d99 | 238 | tok = ename->value; |
7cac2b65 | 239 | |
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; | |
248 | } | |
249 | #endif | |
250 | ||
251 | /* | |
252 | * Check that ename is long enough for all of the fixed length | |
253 | * header, and that the initial ID bytes are correct | |
254 | */ | |
255 | ||
08822d99 | 256 | if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0) |
7cac2b65 | 257 | return GSS_S_FAILURE; |
258 | ||
259 | /* | |
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 | |
263 | * second without. | |
264 | */ | |
265 | ||
30460aeb | 266 | oidl = get_u16(tok+2); /* length including next two bytes */ |
7cac2b65 | 267 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ |
268 | ||
269 | /* | |
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 | |
272 | */ | |
273 | if (tok[4] != 0x06 || tok[5] != oidl || | |
274 | ename->length < oidl+6 || | |
08822d99 | 275 | !ssh_gssapi_check_oid(ctx, tok+6, oidl)) |
7cac2b65 | 276 | return GSS_S_FAILURE; |
277 | ||
278 | offset = oidl+6; | |
279 | ||
280 | if (ename->length < offset+4) | |
281 | return GSS_S_FAILURE; | |
282 | ||
30460aeb | 283 | name->length = get_u32(tok+offset); |
7cac2b65 | 284 | offset += 4; |
285 | ||
286 | if (ename->length < offset+name->length) | |
287 | return GSS_S_FAILURE; | |
288 | ||
289 | name->value = xmalloc(name->length+1); | |
30460aeb | 290 | memcpy(name->value, tok+offset, name->length); |
7cac2b65 | 291 | ((char *)name->value)[name->length] = 0; |
292 | ||
293 | return GSS_S_COMPLETE; | |
294 | } | |
295 | ||
296 | /* Extract the client details from a given context. This can only reliably | |
297 | * be called once for a context */ | |
298 | ||
08822d99 | 299 | /* Privileged (called from accept_secure_ctx) */ |
7cac2b65 | 300 | OM_uint32 |
301 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
302 | { | |
303 | int i = 0; | |
304 | ||
305 | gss_buffer_desc ename; | |
306 | ||
307 | client->mech = NULL; | |
308 | ||
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]; | |
314 | i++; | |
315 | } | |
316 | ||
317 | if (client->mech == NULL) | |
318 | return GSS_S_FAILURE; | |
319 | ||
320 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
321 | &client->displayname, NULL))) { | |
322 | ssh_gssapi_error(ctx); | |
323 | return (ctx->major); | |
324 | } | |
325 | ||
326 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
327 | &ename))) { | |
328 | ssh_gssapi_error(ctx); | |
329 | return (ctx->major); | |
330 | } | |
331 | ||
332 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
333 | &client->exportedname))) { | |
334 | return (ctx->major); | |
335 | } | |
336 | ||
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; | |
682b256d | 340 | |
341 | /* needed for globus_gss_assist_map_and_authorize() */ | |
342 | client->context = ctx->context; | |
343 | ||
7cac2b65 | 344 | return (ctx->major); |
345 | } | |
346 | ||
540d72c3 | 347 | /* As user - called on fatal/exit */ |
7cac2b65 | 348 | void |
540d72c3 | 349 | ssh_gssapi_cleanup_creds(void) |
7cac2b65 | 350 | { |
351 | if (gssapi_client.store.filename != NULL) { | |
352 | /* Unlink probably isn't sufficient */ | |
30460aeb | 353 | debug("removing gssapi cred file\"%s\"", |
354 | gssapi_client.store.filename); | |
7cac2b65 | 355 | unlink(gssapi_client.store.filename); |
356 | } | |
357 | } | |
358 | ||
359 | /* As user */ | |
360 | void | |
361 | ssh_gssapi_storecreds(void) | |
362 | { | |
363 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
364 | (*gssapi_client.mech->storecreds)(&gssapi_client); | |
7cac2b65 | 365 | } else |
366 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
367 | } | |
368 | ||
369 | /* This allows GSSAPI methods to do things to the childs environment based | |
370 | * on the passed authentication process and credentials. | |
371 | */ | |
372 | /* As user */ | |
373 | void | |
374 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
375 | { | |
376 | ||
377 | if (gssapi_client.store.envvar != NULL && | |
378 | gssapi_client.store.envval != NULL) { | |
7cac2b65 | 379 | debug("Setting %s to %s", gssapi_client.store.envvar, |
08822d99 | 380 | gssapi_client.store.envval); |
7cac2b65 | 381 | child_set_env(envp, envsizep, gssapi_client.store.envvar, |
2ce0bfe4 | 382 | gssapi_client.store.envval); |
7cac2b65 | 383 | } |
384 | } | |
385 | ||
08822d99 | 386 | /* Privileged */ |
7cac2b65 | 387 | int |
388 | ssh_gssapi_userok(char *user) | |
389 | { | |
2ce0bfe4 | 390 | OM_uint32 lmin; |
391 | ||
7cac2b65 | 392 | if (gssapi_client.exportedname.length == 0 || |
393 | gssapi_client.exportedname.value == NULL) { | |
394 | debug("No suitable client data"); | |
395 | return 0; | |
396 | } | |
b4cfa386 | 397 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
826a9049 | 398 | if (limited && options.gsi_allow_limited_proxy != 1) { |
b4cfa386 | 399 | debug("limited proxy not acceptable for remote login"); |
400 | return 0; | |
401 | } | |
402 | #endif | |
7cac2b65 | 403 | if (gssapi_client.mech && gssapi_client.mech->userok) |
2ce0bfe4 | 404 | if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
405 | return 1; | |
406 | else { | |
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)); | |
412 | return 0; | |
413 | } | |
7cac2b65 | 414 | else |
415 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
416 | return (0); | |
417 | } | |
418 | ||
e23e524c | 419 | /* Priviledged */ |
23987cb8 | 420 | int |
421 | ssh_gssapi_localname(char **user) | |
422 | { | |
423 | *user = NULL; | |
7cac2b65 | 424 | if (gssapi_client.displayname.length==0 || |
425 | gssapi_client.displayname.value==NULL) { | |
23987cb8 | 426 | debug("No suitable client data"); |
427 | return(0);; | |
428 | } | |
429 | if (gssapi_client.mech && gssapi_client.mech->localname) { | |
430 | return((*gssapi_client.mech->localname)(&gssapi_client,user)); | |
431 | } else { | |
432 | debug("Unknown client authentication type"); | |
433 | } | |
434 | return(0); | |
435 | } | |
540d72c3 | 436 | |
23987cb8 | 437 | #endif |