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416fd2a8 | 1 | /* $OpenBSD: gss-serv.c,v 1.5 2003/11/17 11:06:07 markus Exp $ */ |
70791e56 | 2 | |
5598e598 | 3 | /* |
88928908 | 4 | * Copyright (c) 2001-2003 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 | ||
5598e598 | 31 | #include "buffer.h" |
32 | #include "bufaux.h" | |
5598e598 | 33 | #include "compat.h" |
34 | #include <openssl/evp.h> | |
5598e598 | 35 | #include "kex.h" |
36 | #include "auth.h" | |
37 | #include "log.h" | |
1e608e42 | 38 | #include "channels.h" |
5598e598 | 39 | #include "session.h" |
5598e598 | 40 | #include "servconf.h" |
ff2d7a98 | 41 | #include "monitor_wrap.h" |
70791e56 | 42 | #include "xmalloc.h" |
43 | #include "getput.h" | |
5598e598 | 44 | |
45 | #include "ssh-gss.h" | |
46 | ||
47 | extern ServerOptions options; | |
48 | extern u_char *session_id2; | |
49 | extern int session_id2_len; | |
50 | ||
88928908 | 51 | static ssh_gssapi_client gssapi_client = |
70791e56 | 52 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
53 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
5598e598 | 54 | |
70791e56 | 55 | ssh_gssapi_mech gssapi_null_mech = |
56 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
ff2d7a98 | 57 | |
5598e598 | 58 | #ifdef KRB5 |
88928908 | 59 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
60 | extern ssh_gssapi_mech gssapi_kerberos_mech_old; | |
c2397a66 | 61 | #endif |
5598e598 | 62 | #ifdef GSI |
88928908 | 63 | extern ssh_gssapi_mech gssapi_gsi_mech; |
64 | extern ssh_gssapi_mech gssapi_gsi_mech_old; | |
f2fd21a2 | 65 | #endif |
66 | ||
88928908 | 67 | ssh_gssapi_mech* supported_mechs[]= { |
5598e598 | 68 | #ifdef KRB5 |
70791e56 | 69 | &gssapi_kerberos_mech, |
70 | &gssapi_kerberos_mech_old, /* Support for legacy clients */ | |
5598e598 | 71 | #endif |
72 | #ifdef GSI | |
70791e56 | 73 | &gssapi_gsi_mech, |
74 | &gssapi_gsi_mech_old, /* Support for legacy clients */ | |
67e2750c | 75 | #endif |
70791e56 | 76 | &gssapi_null_mech, |
88928908 | 77 | }; |
5598e598 | 78 | |
2a304a95 | 79 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
80 | static int limited = 0; | |
81 | #endif | |
82 | ||
70791e56 | 83 | /* Unpriviledged */ |
84 | void | |
85 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
86 | { | |
87 | int i = 0; | |
88 | OM_uint32 min_status; | |
89 | int present; | |
90 | gss_OID_set supported; | |
91 | ||
92 | gss_create_empty_oid_set(&min_status, oidset); | |
2a304a95 | 93 | /* Ask priviledged process what mechanisms it supports. */ |
94 | PRIVSEP(gss_indicate_mechs(&min_status, &supported)); | |
70791e56 | 95 | |
96 | while (supported_mechs[i]->name != NULL) { | |
97 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, | |
98 | &supported_mechs[i]->oid, supported, &present))) | |
99 | present = 0; | |
100 | if (present) | |
101 | gss_add_oid_set_member(&min_status, | |
102 | &supported_mechs[i]->oid, oidset); | |
103 | i++; | |
104 | } | |
105 | } | |
106 | ||
107 | ||
108 | /* Wrapper around accept_sec_context | |
109 | * Requires that the context contains: | |
110 | * oid | |
111 | * credentials (from ssh_gssapi_acquire_cred) | |
112 | */ | |
113 | /* Priviledged */ | |
114 | OM_uint32 | |
115 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
116 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
117 | { | |
118 | OM_uint32 status; | |
119 | gss_OID mech; | |
120 | ||
121 | ctx->major = gss_accept_sec_context(&ctx->minor, | |
122 | &ctx->context, ctx->creds, recv_tok, | |
123 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, | |
124 | send_tok, flags, NULL, &ctx->client_creds); | |
125 | ||
126 | if (GSS_ERROR(ctx->major)) | |
127 | ssh_gssapi_error(ctx); | |
128 | ||
129 | if (ctx->client_creds) | |
130 | debug("Received some client credentials"); | |
131 | else | |
132 | debug("Got no client credentials"); | |
133 | ||
134 | status = ctx->major; | |
135 | ||
136 | /* Now, if we're complete and we have the right flags, then | |
137 | * we flag the user as also having been authenticated | |
138 | */ | |
139 | ||
140 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && | |
141 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { | |
142 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) | |
143 | fatal("Couldn't convert client name"); | |
2a304a95 | 144 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
145 | if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG)) | |
146 | limited=1; | |
147 | #endif | |
70791e56 | 148 | } |
149 | ||
150 | return (status); | |
151 | } | |
152 | ||
153 | /* | |
154 | * This parses an exported name, extracting the mechanism specific portion | |
155 | * to use for ACL checking. It verifies that the name belongs the mechanism | |
156 | * originally selected. | |
157 | */ | |
158 | static OM_uint32 | |
159 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
160 | { | |
161 | char *tok; | |
162 | OM_uint32 offset; | |
163 | OM_uint32 oidl; | |
164 | ||
165 | tok=ename->value; | |
166 | ||
167 | #ifdef GSI /* GSI gss_export_name() is broken. */ | |
168 | if ((ctx->oid->length == gssapi_gsi_mech.oid.length) && | |
169 | (memcmp(ctx->oid->elements, gssapi_gsi_mech.oid.elements, | |
170 | gssapi_gsi_mech.oid.length) == 0)) { | |
171 | name->length = ename->length; | |
172 | name->value = xmalloc(ename->length+1); | |
173 | memcpy(name->value, ename->value, ename->length); | |
174 | return GSS_S_COMPLETE; | |
175 | } | |
176 | #endif | |
177 | ||
178 | /* | |
179 | * Check that ename is long enough for all of the fixed length | |
180 | * header, and that the initial ID bytes are correct | |
181 | */ | |
182 | ||
183 | if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0) | |
184 | return GSS_S_FAILURE; | |
185 | ||
186 | /* | |
187 | * Extract the OID, and check it. Here GSSAPI breaks with tradition | |
188 | * and does use the OID type and length bytes. To confuse things | |
189 | * there are two lengths - the first including these, and the | |
190 | * second without. | |
191 | */ | |
192 | ||
193 | oidl = GET_16BIT(tok+2); /* length including next two bytes */ | |
194 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ | |
195 | ||
196 | /* | |
197 | * Check the BER encoding for correct type and length, that the | |
198 | * string is long enough and that the OID matches that in our context | |
199 | */ | |
200 | if (tok[4] != 0x06 || tok[5] != oidl || | |
201 | ename->length < oidl+6 || | |
202 | !ssh_gssapi_check_oid(ctx,tok+6,oidl)) | |
203 | return GSS_S_FAILURE; | |
204 | ||
205 | offset = oidl+6; | |
206 | ||
207 | if (ename->length < offset+4) | |
208 | return GSS_S_FAILURE; | |
209 | ||
210 | name->length = GET_32BIT(tok+offset); | |
211 | offset += 4; | |
212 | ||
213 | if (ename->length < offset+name->length) | |
214 | return GSS_S_FAILURE; | |
215 | ||
216 | name->value = xmalloc(name->length+1); | |
217 | memcpy(name->value,tok+offset,name->length); | |
218 | ((char *)name->value)[name->length] = 0; | |
219 | ||
220 | return GSS_S_COMPLETE; | |
221 | } | |
222 | ||
223 | /* Extract the client details from a given context. This can only reliably | |
224 | * be called once for a context */ | |
225 | ||
226 | /* Priviledged (called from accept_secure_ctx) */ | |
227 | OM_uint32 | |
228 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
229 | { | |
230 | int i = 0; | |
231 | ||
232 | gss_buffer_desc ename; | |
233 | ||
234 | client->mech = NULL; | |
235 | ||
236 | while (supported_mechs[i]->name != NULL) { | |
237 | if (supported_mechs[i]->oid.length == ctx->oid->length && | |
238 | (memcmp(supported_mechs[i]->oid.elements, | |
239 | ctx->oid->elements, ctx->oid->length) == 0)) | |
240 | client->mech = supported_mechs[i]; | |
241 | i++; | |
242 | } | |
243 | ||
244 | if (client->mech == NULL) | |
245 | return GSS_S_FAILURE; | |
246 | ||
247 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
248 | &client->displayname, NULL))) { | |
249 | ssh_gssapi_error(ctx); | |
250 | return (ctx->major); | |
251 | } | |
252 | ||
253 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
254 | &ename))) { | |
255 | ssh_gssapi_error(ctx); | |
256 | return (ctx->major); | |
257 | } | |
258 | ||
259 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
260 | &client->exportedname))) { | |
261 | return (ctx->major); | |
262 | } | |
263 | ||
264 | /* We can't copy this structure, so we just move the pointer to it */ | |
265 | client->creds = ctx->client_creds; | |
266 | ctx->client_creds = GSS_C_NO_CREDENTIAL; | |
267 | return (ctx->major); | |
268 | } | |
269 | ||
416fd2a8 | 270 | /* As user - called on fatal/exit */ |
70791e56 | 271 | void |
416fd2a8 | 272 | ssh_gssapi_cleanup_creds(void) |
70791e56 | 273 | { |
274 | if (gssapi_client.store.filename != NULL) { | |
275 | /* Unlink probably isn't sufficient */ | |
276 | debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename); | |
277 | unlink(gssapi_client.store.filename); | |
278 | } | |
279 | } | |
280 | ||
281 | /* As user */ | |
282 | void | |
283 | ssh_gssapi_storecreds(void) | |
284 | { | |
285 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
286 | (*gssapi_client.mech->storecreds)(&gssapi_client); | |
70791e56 | 287 | } else |
288 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
289 | } | |
290 | ||
291 | /* This allows GSSAPI methods to do things to the childs environment based | |
292 | * on the passed authentication process and credentials. | |
293 | */ | |
294 | /* As user */ | |
295 | void | |
296 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
297 | { | |
298 | ||
299 | if (gssapi_client.store.envvar != NULL && | |
300 | gssapi_client.store.envval != NULL) { | |
301 | ||
302 | debug("Setting %s to %s", gssapi_client.store.envvar, | |
303 | gssapi_client.store.envval); | |
304 | child_set_env(envp, envsizep, gssapi_client.store.envvar, | |
305 | gssapi_client.store.envval); | |
306 | } | |
307 | } | |
308 | ||
309 | /* Priviledged */ | |
310 | int | |
311 | ssh_gssapi_userok(char *user) | |
312 | { | |
313 | if (gssapi_client.exportedname.length == 0 || | |
314 | gssapi_client.exportedname.value == NULL) { | |
315 | debug("No suitable client data"); | |
316 | return 0; | |
317 | } | |
2a304a95 | 318 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
319 | if (limited) { | |
320 | debug("limited proxy not acceptable for remote login"); | |
321 | return 0; | |
322 | } | |
323 | #endif | |
70791e56 | 324 | if (gssapi_client.mech && gssapi_client.mech->userok) |
325 | return ((*gssapi_client.mech->userok)(&gssapi_client, user)); | |
326 | else | |
327 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
328 | return (0); | |
329 | } | |
330 | ||
88928908 | 331 | /* Return a list of the gss-group1-sha1-x mechanisms supported by this |
332 | * program. | |
5598e598 | 333 | * |
88928908 | 334 | * We only support the mechanisms that we've indicated in the list above, |
335 | * but we check that they're supported by the GSSAPI mechanism on the | |
336 | * machine. We also check, before including them in the list, that | |
337 | * we have the necesary information in order to carry out the key exchange | |
338 | * (that is, that the user has credentials, the server's creds are accessible, | |
339 | * etc) | |
340 | * | |
341 | * The way that this is done is fairly nasty, as we do a lot of work that | |
342 | * is then thrown away. This should possibly be implemented with a cache | |
343 | * that stores the results (in an expanded Gssctxt structure), which are | |
344 | * then used by the first calls if that key exchange mechanism is chosen. | |
6a8bca29 | 345 | */ |
6a8bca29 | 346 | |
88928908 | 347 | /* Unpriviledged */ |
1c14df9e | 348 | char * |
88928908 | 349 | ssh_gssapi_server_mechanisms() { |
1c14df9e | 350 | gss_OID_set supported; |
88928908 | 351 | Gssctxt *ctx = NULL; |
1c14df9e | 352 | OM_uint32 maj_status, min_status; |
353 | Buffer buf; | |
354 | int i = 0; | |
88928908 | 355 | int first = 0; |
1c14df9e | 356 | int present; |
1c14df9e | 357 | char * mechs; |
1c14df9e | 358 | |
359 | if (datafellows & SSH_OLD_GSSAPI) return NULL; | |
360 | ||
88928908 | 361 | ssh_gssapi_supported_oids(&supported); |
1c14df9e | 362 | |
88928908 | 363 | buffer_init(&buf); |
1c14df9e | 364 | |
88928908 | 365 | while(supported_mechs[i]->name != NULL) { |
1c14df9e | 366 | if ((maj_status=gss_test_oid_set_member(&min_status, |
88928908 | 367 | &supported_mechs[i]->oid, |
1c14df9e | 368 | supported, |
369 | &present))) { | |
370 | present=0; | |
371 | } | |
88928908 | 372 | |
1c14df9e | 373 | if (present) { |
88928908 | 374 | if (!GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, |
375 | &supported_mechs[i]->oid)))) { | |
376 | /* Append gss_group1_sha1_x to our list */ | |
377 | if (first++!=0) | |
378 | buffer_put_char(&buf,','); | |
379 | buffer_append(&buf, KEX_GSS_SHA1, | |
380 | sizeof(KEX_GSS_SHA1)-1); | |
381 | buffer_append(&buf, | |
382 | supported_mechs[i]->enc_name, | |
383 | strlen(supported_mechs[i]->enc_name)); | |
384 | debug("GSSAPI mechanism %s (%s%s) supported", | |
385 | supported_mechs[i]->name, KEX_GSS_SHA1, | |
386 | supported_mechs[i]->enc_name); | |
387 | } else { | |
388 | debug("no credentials for GSSAPI mechanism %s", | |
389 | supported_mechs[i]->name); | |
390 | } | |
391 | } else { | |
1c14df9e | 392 | debug("GSSAPI mechanism %s not supported", |
88928908 | 393 | supported_mechs[i]->name); |
1c14df9e | 394 | } |
88928908 | 395 | ssh_gssapi_delete_ctx(&ctx); |
396 | i++; | |
397 | } | |
1c14df9e | 398 | |
399 | buffer_put_char(&buf,'\0'); | |
400 | ||
401 | mechs=xmalloc(buffer_len(&buf)); | |
402 | buffer_get(&buf,mechs,buffer_len(&buf)); | |
403 | buffer_free(&buf); | |
1b56ff3d | 404 | if (strlen(mechs)==0) { |
405 | options.gss_authentication = 0; /* no mechs. skip gss auth. */ | |
406 | return(NULL); | |
407 | } else { | |
408 | return(mechs); | |
409 | } | |
1c14df9e | 410 | } |
411 | ||
88928908 | 412 | /* Return the OID that corresponds to the given context name */ |
413 | ||
414 | /* Unpriviledged */ | |
415 | gss_OID | |
416 | ssh_gssapi_server_id_kex(char *name) { | |
417 | int i=0; | |
418 | ||
419 | if (strncmp(name, KEX_GSS_SHA1, sizeof(KEX_GSS_SHA1)-1) !=0) { | |
420 | return(NULL); | |
421 | } | |
422 | ||
423 | name+=sizeof(KEX_GSS_SHA1)-1; /* Move to the start of the MIME string */ | |
424 | ||
425 | while (supported_mechs[i]->name!=NULL && | |
426 | strcmp(name,supported_mechs[i]->enc_name)!=0) { | |
427 | i++; | |
428 | } | |
429 | ||
430 | if (supported_mechs[i]->name==NULL) | |
431 | return (NULL); | |
432 | ||
433 | debug("using GSSAPI mechanism %s (%s%s)", supported_mechs[i]->name, | |
434 | KEX_GSS_SHA1, supported_mechs[i]->enc_name); | |
435 | ||
436 | return &supported_mechs[i]->oid; | |
437 | } | |
438 | ||
88928908 | 439 | /* Priviledged */ |
440 | int | |
441 | ssh_gssapi_localname(char **user) | |
442 | { | |
443 | *user = NULL; | |
70791e56 | 444 | if (gssapi_client.displayname.length==0 || |
445 | gssapi_client.displayname.value==NULL) { | |
88928908 | 446 | debug("No suitable client data"); |
447 | return(0);; | |
448 | } | |
449 | if (gssapi_client.mech && gssapi_client.mech->localname) { | |
450 | return((*gssapi_client.mech->localname)(&gssapi_client,user)); | |
451 | } else { | |
452 | debug("Unknown client authentication type"); | |
453 | } | |
454 | return(0); | |
455 | } | |
416fd2a8 | 456 | |
457 | /* Priviledged */ | |
458 | OM_uint32 | |
459 | ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) | |
460 | { | |
461 | ctx->major = gss_verify_mic(&ctx->minor, ctx->context, | |
462 | gssbuf, gssmic, NULL); | |
463 | ||
464 | return (ctx->major); | |
465 | } | |
466 | ||
88928908 | 467 | #endif |