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5156b1a1 | 1 | /* $OpenBSD: gss-serv.c,v 1.22 2008/05/08 12:02:23 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 | ||
5156b1a1 | 38 | #include "openbsd-compat/sys-queue.h" |
30460aeb | 39 | #include "xmalloc.h" |
40 | #include "buffer.h" | |
41 | #include "key.h" | |
42 | #include "hostfile.h" | |
5598e598 | 43 | #include "auth.h" |
44 | #include "log.h" | |
e5affddc | 45 | #include "channels.h" |
5598e598 | 46 | #include "session.h" |
f713db99 | 47 | #include "misc.h" |
5598e598 | 48 | #include "servconf.h" |
f713db99 | 49 | |
7cac2b65 | 50 | #include "xmalloc.h" |
5598e598 | 51 | #include "ssh-gss.h" |
30460aeb | 52 | #include "monitor_wrap.h" |
5598e598 | 53 | |
bd3336ab | 54 | extern ServerOptions options; |
ae82558b | 55 | extern Authctxt *the_authctxt; |
bd3336ab | 56 | |
23987cb8 | 57 | static ssh_gssapi_client gssapi_client = |
7cac2b65 | 58 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
59 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
5598e598 | 60 | |
7cac2b65 | 61 | ssh_gssapi_mech gssapi_null_mech = |
62 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
44a053a3 | 63 | |
5598e598 | 64 | #ifdef KRB5 |
23987cb8 | 65 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
54425c7a | 66 | #endif |
5598e598 | 67 | #ifdef GSI |
23987cb8 | 68 | extern ssh_gssapi_mech gssapi_gsi_mech; |
b311f64e | 69 | #endif |
70 | ||
23987cb8 | 71 | ssh_gssapi_mech* supported_mechs[]= { |
5598e598 | 72 | #ifdef KRB5 |
7cac2b65 | 73 | &gssapi_kerberos_mech, |
5598e598 | 74 | #endif |
75 | #ifdef GSI | |
7cac2b65 | 76 | &gssapi_gsi_mech, |
7b5a625b | 77 | #endif |
7cac2b65 | 78 | &gssapi_null_mech, |
23987cb8 | 79 | }; |
5598e598 | 80 | |
b4cfa386 | 81 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
82 | static int limited = 0; | |
83 | #endif | |
84 | ||
c06c9ae8 | 85 | /* Unprivileged */ |
fe4ad273 | 86 | char * |
87 | ssh_gssapi_server_mechanisms() { | |
88 | gss_OID_set supported; | |
89 | ||
90 | ssh_gssapi_supported_oids(&supported); | |
91 | return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech, | |
92 | NULL)); | |
93 | } | |
94 | ||
c06c9ae8 | 95 | /* Unprivileged */ |
fe4ad273 | 96 | int |
f713db99 | 97 | ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data) { |
98 | Gssctxt *ctx = NULL; | |
fe4ad273 | 99 | int res; |
c06c9ae8 | 100 | |
f713db99 | 101 | res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid))); |
102 | ssh_gssapi_delete_ctx(&ctx); | |
fe4ad273 | 103 | |
104 | return (res); | |
105 | } | |
106 | ||
fa0f0f45 | 107 | /* |
108 | * Acquire credentials for a server running on the current host. | |
f713db99 | 109 | * Requires that the context structure contains a valid OID |
110 | */ | |
111 | ||
112 | /* Returns a GSSAPI error code */ | |
fa0f0f45 | 113 | /* Privileged (called from ssh_gssapi_server_ctx) */ |
114 | static OM_uint32 | |
f713db99 | 115 | ssh_gssapi_acquire_cred(Gssctxt *ctx) |
116 | { | |
117 | OM_uint32 status; | |
118 | char lname[MAXHOSTNAMELEN]; | |
119 | gss_OID_set oidset; | |
120 | ||
121 | if (options.gss_strict_acceptor) { | |
122 | gss_create_empty_oid_set(&status, &oidset); | |
123 | gss_add_oid_set_member(&status, ctx->oid, &oidset); | |
124 | ||
125 | if (gethostname(lname, MAXHOSTNAMELEN)) { | |
126 | gss_release_oid_set(&status, &oidset); | |
127 | return (-1); | |
128 | } | |
129 | ||
130 | if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) { | |
131 | gss_release_oid_set(&status, &oidset); | |
132 | return (ctx->major); | |
133 | } | |
134 | ||
135 | if ((ctx->major = gss_acquire_cred(&ctx->minor, | |
136 | ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, | |
137 | NULL, NULL))) | |
138 | ssh_gssapi_error(ctx); | |
139 | ||
140 | gss_release_oid_set(&status, &oidset); | |
141 | return (ctx->major); | |
142 | } else { | |
143 | ctx->name = GSS_C_NO_NAME; | |
144 | ctx->creds = GSS_C_NO_CREDENTIAL; | |
145 | } | |
146 | return GSS_S_COMPLETE; | |
147 | } | |
148 | ||
7cac2b65 | 149 | |
fa0f0f45 | 150 | /* Privileged */ |
151 | OM_uint32 | |
152 | ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) | |
153 | { | |
154 | if (*ctx) | |
155 | ssh_gssapi_delete_ctx(ctx); | |
156 | ssh_gssapi_build_ctx(ctx); | |
157 | ssh_gssapi_set_oid(*ctx, oid); | |
158 | return (ssh_gssapi_acquire_cred(*ctx)); | |
159 | } | |
160 | ||
c5b7701b | 161 | /* Unprivileged */ |
162 | void | |
163 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
164 | { | |
165 | int i = 0; | |
166 | OM_uint32 min_status; | |
167 | int present; | |
168 | gss_OID_set supported; | |
169 | ||
170 | gss_create_empty_oid_set(&min_status, oidset); | |
171 | /* Ask priviledged process what mechanisms it supports. */ | |
172 | PRIVSEP(gss_indicate_mechs(&min_status, &supported)); | |
173 | ||
174 | while (supported_mechs[i]->name != NULL) { | |
175 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, | |
176 | &supported_mechs[i]->oid, supported, &present))) | |
177 | present = 0; | |
178 | if (present) | |
179 | gss_add_oid_set_member(&min_status, | |
180 | &supported_mechs[i]->oid, oidset); | |
181 | i++; | |
182 | } | |
183 | ||
184 | gss_release_oid_set(&min_status, &supported); | |
185 | } | |
186 | ||
187 | ||
7cac2b65 | 188 | /* Wrapper around accept_sec_context |
189 | * Requires that the context contains: | |
190 | * oid | |
191 | * credentials (from ssh_gssapi_acquire_cred) | |
192 | */ | |
08822d99 | 193 | /* Privileged */ |
7cac2b65 | 194 | OM_uint32 |
195 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
196 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
197 | { | |
198 | OM_uint32 status; | |
199 | gss_OID mech; | |
200 | ||
201 | ctx->major = gss_accept_sec_context(&ctx->minor, | |
202 | &ctx->context, ctx->creds, recv_tok, | |
203 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, | |
204 | send_tok, flags, NULL, &ctx->client_creds); | |
205 | ||
206 | if (GSS_ERROR(ctx->major)) | |
207 | ssh_gssapi_error(ctx); | |
208 | ||
209 | if (ctx->client_creds) | |
210 | debug("Received some client credentials"); | |
211 | else | |
212 | debug("Got no client credentials"); | |
213 | ||
214 | status = ctx->major; | |
215 | ||
216 | /* Now, if we're complete and we have the right flags, then | |
217 | * we flag the user as also having been authenticated | |
218 | */ | |
219 | ||
220 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && | |
221 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { | |
222 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) | |
223 | fatal("Couldn't convert client name"); | |
b4cfa386 | 224 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
225 | if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG)) | |
226 | limited=1; | |
227 | #endif | |
7cac2b65 | 228 | } |
229 | ||
230 | return (status); | |
231 | } | |
232 | ||
233 | /* | |
234 | * This parses an exported name, extracting the mechanism specific portion | |
235 | * to use for ACL checking. It verifies that the name belongs the mechanism | |
236 | * originally selected. | |
237 | */ | |
238 | static OM_uint32 | |
239 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
240 | { | |
2ce0bfe4 | 241 | u_char *tok; |
7cac2b65 | 242 | OM_uint32 offset; |
243 | OM_uint32 oidl; | |
244 | ||
08822d99 | 245 | tok = ename->value; |
7cac2b65 | 246 | |
247 | #ifdef GSI /* GSI gss_export_name() is broken. */ | |
248 | if ((ctx->oid->length == gssapi_gsi_mech.oid.length) && | |
249 | (memcmp(ctx->oid->elements, gssapi_gsi_mech.oid.elements, | |
250 | gssapi_gsi_mech.oid.length) == 0)) { | |
251 | name->length = ename->length; | |
252 | name->value = xmalloc(ename->length+1); | |
253 | memcpy(name->value, ename->value, ename->length); | |
254 | return GSS_S_COMPLETE; | |
255 | } | |
256 | #endif | |
257 | ||
258 | /* | |
259 | * Check that ename is long enough for all of the fixed length | |
260 | * header, and that the initial ID bytes are correct | |
261 | */ | |
262 | ||
08822d99 | 263 | if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0) |
7cac2b65 | 264 | return GSS_S_FAILURE; |
265 | ||
266 | /* | |
267 | * Extract the OID, and check it. Here GSSAPI breaks with tradition | |
268 | * and does use the OID type and length bytes. To confuse things | |
269 | * there are two lengths - the first including these, and the | |
270 | * second without. | |
271 | */ | |
272 | ||
30460aeb | 273 | oidl = get_u16(tok+2); /* length including next two bytes */ |
7cac2b65 | 274 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ |
275 | ||
276 | /* | |
277 | * Check the BER encoding for correct type and length, that the | |
278 | * string is long enough and that the OID matches that in our context | |
279 | */ | |
280 | if (tok[4] != 0x06 || tok[5] != oidl || | |
281 | ename->length < oidl+6 || | |
08822d99 | 282 | !ssh_gssapi_check_oid(ctx, tok+6, oidl)) |
7cac2b65 | 283 | return GSS_S_FAILURE; |
284 | ||
285 | offset = oidl+6; | |
286 | ||
287 | if (ename->length < offset+4) | |
288 | return GSS_S_FAILURE; | |
289 | ||
30460aeb | 290 | name->length = get_u32(tok+offset); |
7cac2b65 | 291 | offset += 4; |
292 | ||
293 | if (ename->length < offset+name->length) | |
294 | return GSS_S_FAILURE; | |
295 | ||
296 | name->value = xmalloc(name->length+1); | |
30460aeb | 297 | memcpy(name->value, tok+offset, name->length); |
7cac2b65 | 298 | ((char *)name->value)[name->length] = 0; |
299 | ||
300 | return GSS_S_COMPLETE; | |
301 | } | |
302 | ||
303 | /* Extract the client details from a given context. This can only reliably | |
304 | * be called once for a context */ | |
305 | ||
08822d99 | 306 | /* Privileged (called from accept_secure_ctx) */ |
7cac2b65 | 307 | OM_uint32 |
308 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
309 | { | |
310 | int i = 0; | |
311 | ||
312 | gss_buffer_desc ename; | |
313 | ||
314 | client->mech = NULL; | |
315 | ||
316 | while (supported_mechs[i]->name != NULL) { | |
317 | if (supported_mechs[i]->oid.length == ctx->oid->length && | |
318 | (memcmp(supported_mechs[i]->oid.elements, | |
319 | ctx->oid->elements, ctx->oid->length) == 0)) | |
320 | client->mech = supported_mechs[i]; | |
321 | i++; | |
322 | } | |
323 | ||
324 | if (client->mech == NULL) | |
325 | return GSS_S_FAILURE; | |
326 | ||
327 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
328 | &client->displayname, NULL))) { | |
329 | ssh_gssapi_error(ctx); | |
330 | return (ctx->major); | |
331 | } | |
332 | ||
333 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
334 | &ename))) { | |
335 | ssh_gssapi_error(ctx); | |
336 | return (ctx->major); | |
337 | } | |
338 | ||
339 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
340 | &client->exportedname))) { | |
341 | return (ctx->major); | |
342 | } | |
343 | ||
344 | /* We can't copy this structure, so we just move the pointer to it */ | |
345 | client->creds = ctx->client_creds; | |
346 | ctx->client_creds = GSS_C_NO_CREDENTIAL; | |
682b256d | 347 | |
348 | /* needed for globus_gss_assist_map_and_authorize() */ | |
349 | client->context = ctx->context; | |
350 | ||
7cac2b65 | 351 | return (ctx->major); |
352 | } | |
353 | ||
540d72c3 | 354 | /* As user - called on fatal/exit */ |
7cac2b65 | 355 | void |
540d72c3 | 356 | ssh_gssapi_cleanup_creds(void) |
7cac2b65 | 357 | { |
358 | if (gssapi_client.store.filename != NULL) { | |
359 | /* Unlink probably isn't sufficient */ | |
30460aeb | 360 | debug("removing gssapi cred file\"%s\"", |
361 | gssapi_client.store.filename); | |
7cac2b65 | 362 | unlink(gssapi_client.store.filename); |
363 | } | |
364 | } | |
365 | ||
366 | /* As user */ | |
367 | void | |
368 | ssh_gssapi_storecreds(void) | |
369 | { | |
370 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
ae82558b | 371 | if (options.gss_creds_path) { |
372 | gssapi_client.store.filename = | |
373 | expand_authorized_keys(options.gss_creds_path, | |
374 | the_authctxt->pw); | |
375 | } | |
7cac2b65 | 376 | (*gssapi_client.mech->storecreds)(&gssapi_client); |
7cac2b65 | 377 | } else |
378 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
379 | } | |
380 | ||
381 | /* This allows GSSAPI methods to do things to the childs environment based | |
382 | * on the passed authentication process and credentials. | |
383 | */ | |
384 | /* As user */ | |
385 | void | |
386 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
387 | { | |
388 | ||
389 | if (gssapi_client.store.envvar != NULL && | |
390 | gssapi_client.store.envval != NULL) { | |
7cac2b65 | 391 | debug("Setting %s to %s", gssapi_client.store.envvar, |
08822d99 | 392 | gssapi_client.store.envval); |
7cac2b65 | 393 | child_set_env(envp, envsizep, gssapi_client.store.envvar, |
2ce0bfe4 | 394 | gssapi_client.store.envval); |
7cac2b65 | 395 | } |
396 | } | |
397 | ||
08822d99 | 398 | /* Privileged */ |
7cac2b65 | 399 | int |
400 | ssh_gssapi_userok(char *user) | |
401 | { | |
2ce0bfe4 | 402 | OM_uint32 lmin; |
403 | ||
7cac2b65 | 404 | if (gssapi_client.exportedname.length == 0 || |
405 | gssapi_client.exportedname.value == NULL) { | |
406 | debug("No suitable client data"); | |
407 | return 0; | |
408 | } | |
b4cfa386 | 409 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
826a9049 | 410 | if (limited && options.gsi_allow_limited_proxy != 1) { |
b4cfa386 | 411 | debug("limited proxy not acceptable for remote login"); |
412 | return 0; | |
413 | } | |
414 | #endif | |
7cac2b65 | 415 | if (gssapi_client.mech && gssapi_client.mech->userok) |
2ce0bfe4 | 416 | if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
417 | return 1; | |
418 | else { | |
419 | /* Destroy delegated credentials if userok fails */ | |
420 | gss_release_buffer(&lmin, &gssapi_client.displayname); | |
421 | gss_release_buffer(&lmin, &gssapi_client.exportedname); | |
422 | gss_release_cred(&lmin, &gssapi_client.creds); | |
423 | memset(&gssapi_client, 0, sizeof(ssh_gssapi_client)); | |
424 | return 0; | |
425 | } | |
7cac2b65 | 426 | else |
427 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
428 | return (0); | |
429 | } | |
430 | ||
c5b7701b | 431 | /* ssh_gssapi_checkmic() moved to gss-genr.c so it can be called by |
432 | kexgss_client(). */ | |
433 | ||
e23e524c | 434 | /* Priviledged */ |
23987cb8 | 435 | int |
436 | ssh_gssapi_localname(char **user) | |
437 | { | |
438 | *user = NULL; | |
7cac2b65 | 439 | if (gssapi_client.displayname.length==0 || |
440 | gssapi_client.displayname.value==NULL) { | |
23987cb8 | 441 | debug("No suitable client data"); |
442 | return(0);; | |
443 | } | |
444 | if (gssapi_client.mech && gssapi_client.mech->localname) { | |
445 | return((*gssapi_client.mech->localname)(&gssapi_client,user)); | |
446 | } else { | |
447 | debug("Unknown client authentication type"); | |
448 | } | |
449 | return(0); | |
450 | } | |
540d72c3 | 451 | |
23987cb8 | 452 | #endif |