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fa0f0f45 | 1 | /* $OpenBSD: gss-serv.c,v 1.21 2007/06/12 08:20:00 djm 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> |
fa0f0f45 | 32 | #include <sys/param.h> |
30460aeb | 33 | |
34 | #include <stdarg.h> | |
35 | #include <string.h> | |
36 | #include <unistd.h> | |
37 | ||
38 | #include "xmalloc.h" | |
39 | #include "buffer.h" | |
40 | #include "key.h" | |
41 | #include "hostfile.h" | |
5598e598 | 42 | #include "auth.h" |
43 | #include "log.h" | |
e5affddc | 44 | #include "channels.h" |
5598e598 | 45 | #include "session.h" |
f713db99 | 46 | #include "misc.h" |
5598e598 | 47 | #include "servconf.h" |
f713db99 | 48 | |
7cac2b65 | 49 | #include "xmalloc.h" |
5598e598 | 50 | #include "ssh-gss.h" |
30460aeb | 51 | #include "monitor_wrap.h" |
5598e598 | 52 | |
bd3336ab | 53 | extern ServerOptions options; |
ae82558b | 54 | extern Authctxt *the_authctxt; |
bd3336ab | 55 | |
23987cb8 | 56 | static ssh_gssapi_client gssapi_client = |
7cac2b65 | 57 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
58 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
5598e598 | 59 | |
7cac2b65 | 60 | ssh_gssapi_mech gssapi_null_mech = |
61 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
44a053a3 | 62 | |
5598e598 | 63 | #ifdef KRB5 |
23987cb8 | 64 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
54425c7a | 65 | #endif |
5598e598 | 66 | #ifdef GSI |
23987cb8 | 67 | extern ssh_gssapi_mech gssapi_gsi_mech; |
b311f64e | 68 | #endif |
69 | ||
23987cb8 | 70 | ssh_gssapi_mech* supported_mechs[]= { |
5598e598 | 71 | #ifdef KRB5 |
7cac2b65 | 72 | &gssapi_kerberos_mech, |
5598e598 | 73 | #endif |
74 | #ifdef GSI | |
7cac2b65 | 75 | &gssapi_gsi_mech, |
7b5a625b | 76 | #endif |
7cac2b65 | 77 | &gssapi_null_mech, |
23987cb8 | 78 | }; |
5598e598 | 79 | |
b4cfa386 | 80 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
81 | static int limited = 0; | |
82 | #endif | |
83 | ||
c06c9ae8 | 84 | /* Unprivileged */ |
fe4ad273 | 85 | char * |
86 | ssh_gssapi_server_mechanisms() { | |
87 | gss_OID_set supported; | |
88 | ||
89 | ssh_gssapi_supported_oids(&supported); | |
90 | return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech, | |
91 | NULL)); | |
92 | } | |
93 | ||
c06c9ae8 | 94 | /* Unprivileged */ |
fe4ad273 | 95 | int |
f713db99 | 96 | ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data) { |
97 | Gssctxt *ctx = NULL; | |
fe4ad273 | 98 | int res; |
c06c9ae8 | 99 | |
f713db99 | 100 | res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid))); |
101 | ssh_gssapi_delete_ctx(&ctx); | |
fe4ad273 | 102 | |
103 | return (res); | |
104 | } | |
105 | ||
c06c9ae8 | 106 | /* Unprivileged */ |
7cac2b65 | 107 | void |
108 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
109 | { | |
110 | int i = 0; | |
111 | OM_uint32 min_status; | |
112 | int present; | |
113 | gss_OID_set supported; | |
114 | ||
115 | gss_create_empty_oid_set(&min_status, oidset); | |
186e1568 | 116 | /* Ask priviledged process what mechanisms it supports. */ |
117 | PRIVSEP(gss_indicate_mechs(&min_status, &supported)); | |
7cac2b65 | 118 | |
119 | while (supported_mechs[i]->name != NULL) { | |
120 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, | |
121 | &supported_mechs[i]->oid, supported, &present))) | |
122 | present = 0; | |
123 | if (present) | |
124 | gss_add_oid_set_member(&min_status, | |
125 | &supported_mechs[i]->oid, oidset); | |
126 | i++; | |
127 | } | |
30460aeb | 128 | |
129 | gss_release_oid_set(&min_status, &supported); | |
7cac2b65 | 130 | } |
131 | ||
fa0f0f45 | 132 | /* |
133 | * Acquire credentials for a server running on the current host. | |
f713db99 | 134 | * Requires that the context structure contains a valid OID |
135 | */ | |
136 | ||
137 | /* Returns a GSSAPI error code */ | |
fa0f0f45 | 138 | /* Privileged (called from ssh_gssapi_server_ctx) */ |
139 | static OM_uint32 | |
f713db99 | 140 | ssh_gssapi_acquire_cred(Gssctxt *ctx) |
141 | { | |
142 | OM_uint32 status; | |
143 | char lname[MAXHOSTNAMELEN]; | |
144 | gss_OID_set oidset; | |
145 | ||
146 | if (options.gss_strict_acceptor) { | |
147 | gss_create_empty_oid_set(&status, &oidset); | |
148 | gss_add_oid_set_member(&status, ctx->oid, &oidset); | |
149 | ||
150 | if (gethostname(lname, MAXHOSTNAMELEN)) { | |
151 | gss_release_oid_set(&status, &oidset); | |
152 | return (-1); | |
153 | } | |
154 | ||
155 | if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) { | |
156 | gss_release_oid_set(&status, &oidset); | |
157 | return (ctx->major); | |
158 | } | |
159 | ||
160 | if ((ctx->major = gss_acquire_cred(&ctx->minor, | |
161 | ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, | |
162 | NULL, NULL))) | |
163 | ssh_gssapi_error(ctx); | |
164 | ||
165 | gss_release_oid_set(&status, &oidset); | |
166 | return (ctx->major); | |
167 | } else { | |
168 | ctx->name = GSS_C_NO_NAME; | |
169 | ctx->creds = GSS_C_NO_CREDENTIAL; | |
170 | } | |
171 | return GSS_S_COMPLETE; | |
172 | } | |
173 | ||
7cac2b65 | 174 | |
fa0f0f45 | 175 | /* Privileged */ |
176 | OM_uint32 | |
177 | ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) | |
178 | { | |
179 | if (*ctx) | |
180 | ssh_gssapi_delete_ctx(ctx); | |
181 | ssh_gssapi_build_ctx(ctx); | |
182 | ssh_gssapi_set_oid(*ctx, oid); | |
183 | return (ssh_gssapi_acquire_cred(*ctx)); | |
184 | } | |
185 | ||
7cac2b65 | 186 | /* Wrapper around accept_sec_context |
187 | * Requires that the context contains: | |
188 | * oid | |
189 | * credentials (from ssh_gssapi_acquire_cred) | |
190 | */ | |
08822d99 | 191 | /* Privileged */ |
7cac2b65 | 192 | OM_uint32 |
193 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
194 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
195 | { | |
196 | OM_uint32 status; | |
197 | gss_OID mech; | |
198 | ||
199 | ctx->major = gss_accept_sec_context(&ctx->minor, | |
200 | &ctx->context, ctx->creds, recv_tok, | |
201 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, | |
202 | send_tok, flags, NULL, &ctx->client_creds); | |
203 | ||
204 | if (GSS_ERROR(ctx->major)) | |
205 | ssh_gssapi_error(ctx); | |
206 | ||
207 | if (ctx->client_creds) | |
208 | debug("Received some client credentials"); | |
209 | else | |
210 | debug("Got no client credentials"); | |
211 | ||
212 | status = ctx->major; | |
213 | ||
214 | /* Now, if we're complete and we have the right flags, then | |
215 | * we flag the user as also having been authenticated | |
216 | */ | |
217 | ||
218 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && | |
219 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { | |
220 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) | |
221 | fatal("Couldn't convert client name"); | |
b4cfa386 | 222 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
223 | if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG)) | |
224 | limited=1; | |
225 | #endif | |
7cac2b65 | 226 | } |
227 | ||
228 | return (status); | |
229 | } | |
230 | ||
231 | /* | |
232 | * This parses an exported name, extracting the mechanism specific portion | |
233 | * to use for ACL checking. It verifies that the name belongs the mechanism | |
234 | * originally selected. | |
235 | */ | |
236 | static OM_uint32 | |
237 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
238 | { | |
2ce0bfe4 | 239 | u_char *tok; |
7cac2b65 | 240 | OM_uint32 offset; |
241 | OM_uint32 oidl; | |
242 | ||
08822d99 | 243 | tok = ename->value; |
7cac2b65 | 244 | |
245 | #ifdef GSI /* GSI gss_export_name() is broken. */ | |
246 | if ((ctx->oid->length == gssapi_gsi_mech.oid.length) && | |
247 | (memcmp(ctx->oid->elements, gssapi_gsi_mech.oid.elements, | |
248 | gssapi_gsi_mech.oid.length) == 0)) { | |
249 | name->length = ename->length; | |
250 | name->value = xmalloc(ename->length+1); | |
251 | memcpy(name->value, ename->value, ename->length); | |
252 | return GSS_S_COMPLETE; | |
253 | } | |
254 | #endif | |
255 | ||
256 | /* | |
257 | * Check that ename is long enough for all of the fixed length | |
258 | * header, and that the initial ID bytes are correct | |
259 | */ | |
260 | ||
08822d99 | 261 | if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0) |
7cac2b65 | 262 | return GSS_S_FAILURE; |
263 | ||
264 | /* | |
265 | * Extract the OID, and check it. Here GSSAPI breaks with tradition | |
266 | * and does use the OID type and length bytes. To confuse things | |
267 | * there are two lengths - the first including these, and the | |
268 | * second without. | |
269 | */ | |
270 | ||
30460aeb | 271 | oidl = get_u16(tok+2); /* length including next two bytes */ |
7cac2b65 | 272 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ |
273 | ||
274 | /* | |
275 | * Check the BER encoding for correct type and length, that the | |
276 | * string is long enough and that the OID matches that in our context | |
277 | */ | |
278 | if (tok[4] != 0x06 || tok[5] != oidl || | |
279 | ename->length < oidl+6 || | |
08822d99 | 280 | !ssh_gssapi_check_oid(ctx, tok+6, oidl)) |
7cac2b65 | 281 | return GSS_S_FAILURE; |
282 | ||
283 | offset = oidl+6; | |
284 | ||
285 | if (ename->length < offset+4) | |
286 | return GSS_S_FAILURE; | |
287 | ||
30460aeb | 288 | name->length = get_u32(tok+offset); |
7cac2b65 | 289 | offset += 4; |
290 | ||
291 | if (ename->length < offset+name->length) | |
292 | return GSS_S_FAILURE; | |
293 | ||
294 | name->value = xmalloc(name->length+1); | |
30460aeb | 295 | memcpy(name->value, tok+offset, name->length); |
7cac2b65 | 296 | ((char *)name->value)[name->length] = 0; |
297 | ||
298 | return GSS_S_COMPLETE; | |
299 | } | |
300 | ||
301 | /* Extract the client details from a given context. This can only reliably | |
302 | * be called once for a context */ | |
303 | ||
08822d99 | 304 | /* Privileged (called from accept_secure_ctx) */ |
7cac2b65 | 305 | OM_uint32 |
306 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
307 | { | |
308 | int i = 0; | |
309 | ||
310 | gss_buffer_desc ename; | |
311 | ||
312 | client->mech = NULL; | |
313 | ||
314 | while (supported_mechs[i]->name != NULL) { | |
315 | if (supported_mechs[i]->oid.length == ctx->oid->length && | |
316 | (memcmp(supported_mechs[i]->oid.elements, | |
317 | ctx->oid->elements, ctx->oid->length) == 0)) | |
318 | client->mech = supported_mechs[i]; | |
319 | i++; | |
320 | } | |
321 | ||
322 | if (client->mech == NULL) | |
323 | return GSS_S_FAILURE; | |
324 | ||
325 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
326 | &client->displayname, NULL))) { | |
327 | ssh_gssapi_error(ctx); | |
328 | return (ctx->major); | |
329 | } | |
330 | ||
331 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
332 | &ename))) { | |
333 | ssh_gssapi_error(ctx); | |
334 | return (ctx->major); | |
335 | } | |
336 | ||
337 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
338 | &client->exportedname))) { | |
339 | return (ctx->major); | |
340 | } | |
341 | ||
342 | /* We can't copy this structure, so we just move the pointer to it */ | |
343 | client->creds = ctx->client_creds; | |
344 | ctx->client_creds = GSS_C_NO_CREDENTIAL; | |
682b256d | 345 | |
346 | /* needed for globus_gss_assist_map_and_authorize() */ | |
347 | client->context = ctx->context; | |
348 | ||
7cac2b65 | 349 | return (ctx->major); |
350 | } | |
351 | ||
540d72c3 | 352 | /* As user - called on fatal/exit */ |
7cac2b65 | 353 | void |
540d72c3 | 354 | ssh_gssapi_cleanup_creds(void) |
7cac2b65 | 355 | { |
356 | if (gssapi_client.store.filename != NULL) { | |
357 | /* Unlink probably isn't sufficient */ | |
30460aeb | 358 | debug("removing gssapi cred file\"%s\"", |
359 | gssapi_client.store.filename); | |
7cac2b65 | 360 | unlink(gssapi_client.store.filename); |
361 | } | |
362 | } | |
363 | ||
364 | /* As user */ | |
365 | void | |
366 | ssh_gssapi_storecreds(void) | |
367 | { | |
368 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
ae82558b | 369 | if (options.gss_creds_path) { |
370 | gssapi_client.store.filename = | |
371 | expand_authorized_keys(options.gss_creds_path, | |
372 | the_authctxt->pw); | |
373 | } | |
7cac2b65 | 374 | (*gssapi_client.mech->storecreds)(&gssapi_client); |
7cac2b65 | 375 | } else |
376 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
377 | } | |
378 | ||
379 | /* This allows GSSAPI methods to do things to the childs environment based | |
380 | * on the passed authentication process and credentials. | |
381 | */ | |
382 | /* As user */ | |
383 | void | |
384 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
385 | { | |
386 | ||
387 | if (gssapi_client.store.envvar != NULL && | |
388 | gssapi_client.store.envval != NULL) { | |
7cac2b65 | 389 | debug("Setting %s to %s", gssapi_client.store.envvar, |
08822d99 | 390 | gssapi_client.store.envval); |
7cac2b65 | 391 | child_set_env(envp, envsizep, gssapi_client.store.envvar, |
2ce0bfe4 | 392 | gssapi_client.store.envval); |
7cac2b65 | 393 | } |
394 | } | |
395 | ||
08822d99 | 396 | /* Privileged */ |
7cac2b65 | 397 | int |
398 | ssh_gssapi_userok(char *user) | |
399 | { | |
2ce0bfe4 | 400 | OM_uint32 lmin; |
401 | ||
7cac2b65 | 402 | if (gssapi_client.exportedname.length == 0 || |
403 | gssapi_client.exportedname.value == NULL) { | |
404 | debug("No suitable client data"); | |
405 | return 0; | |
406 | } | |
b4cfa386 | 407 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
826a9049 | 408 | if (limited && options.gsi_allow_limited_proxy != 1) { |
b4cfa386 | 409 | debug("limited proxy not acceptable for remote login"); |
410 | return 0; | |
411 | } | |
412 | #endif | |
7cac2b65 | 413 | if (gssapi_client.mech && gssapi_client.mech->userok) |
2ce0bfe4 | 414 | if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
415 | return 1; | |
416 | else { | |
417 | /* Destroy delegated credentials if userok fails */ | |
418 | gss_release_buffer(&lmin, &gssapi_client.displayname); | |
419 | gss_release_buffer(&lmin, &gssapi_client.exportedname); | |
420 | gss_release_cred(&lmin, &gssapi_client.creds); | |
421 | memset(&gssapi_client, 0, sizeof(ssh_gssapi_client)); | |
422 | return 0; | |
423 | } | |
7cac2b65 | 424 | else |
425 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
426 | return (0); | |
427 | } | |
428 | ||
e23e524c | 429 | /* Priviledged */ |
23987cb8 | 430 | int |
431 | ssh_gssapi_localname(char **user) | |
432 | { | |
433 | *user = NULL; | |
7cac2b65 | 434 | if (gssapi_client.displayname.length==0 || |
435 | gssapi_client.displayname.value==NULL) { | |
23987cb8 | 436 | debug("No suitable client data"); |
437 | return(0);; | |
438 | } | |
439 | if (gssapi_client.mech && gssapi_client.mech->localname) { | |
440 | return((*gssapi_client.mech->localname)(&gssapi_client,user)); | |
441 | } else { | |
442 | debug("Unknown client authentication type"); | |
443 | } | |
444 | return(0); | |
445 | } | |
540d72c3 | 446 | |
23987cb8 | 447 | #endif |