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540d72c3 | 1 | /* $OpenBSD: gss-serv.c,v 1.5 2003/11/17 11:06:07 markus Exp $ */ |
7cac2b65 | 2 | |
5598e598 | 3 | /* |
23987cb8 | 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" | |
e5affddc | 38 | #include "channels.h" |
5598e598 | 39 | #include "session.h" |
5598e598 | 40 | #include "servconf.h" |
b59afbfe | 41 | #include "monitor_wrap.h" |
7cac2b65 | 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 | ||
23987cb8 | 51 | static ssh_gssapi_client gssapi_client = |
7cac2b65 | 52 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
53 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
5598e598 | 54 | |
7cac2b65 | 55 | ssh_gssapi_mech gssapi_null_mech = |
56 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
44a053a3 | 57 | |
5598e598 | 58 | #ifdef KRB5 |
23987cb8 | 59 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
54425c7a | 60 | #endif |
5598e598 | 61 | #ifdef GSI |
23987cb8 | 62 | extern ssh_gssapi_mech gssapi_gsi_mech; |
b311f64e | 63 | #endif |
64 | ||
23987cb8 | 65 | ssh_gssapi_mech* supported_mechs[]= { |
5598e598 | 66 | #ifdef KRB5 |
7cac2b65 | 67 | &gssapi_kerberos_mech, |
5598e598 | 68 | #endif |
69 | #ifdef GSI | |
7cac2b65 | 70 | &gssapi_gsi_mech, |
7b5a625b | 71 | #endif |
7cac2b65 | 72 | &gssapi_null_mech, |
23987cb8 | 73 | }; |
5598e598 | 74 | |
b4cfa386 | 75 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
76 | static int limited = 0; | |
77 | #endif | |
78 | ||
7cac2b65 | 79 | /* Unpriviledged */ |
80 | void | |
81 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
82 | { | |
83 | int i = 0; | |
84 | OM_uint32 min_status; | |
85 | int present; | |
86 | gss_OID_set supported; | |
87 | ||
88 | gss_create_empty_oid_set(&min_status, oidset); | |
186e1568 | 89 | /* Ask priviledged process what mechanisms it supports. */ |
90 | PRIVSEP(gss_indicate_mechs(&min_status, &supported)); | |
7cac2b65 | 91 | |
92 | while (supported_mechs[i]->name != NULL) { | |
93 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, | |
94 | &supported_mechs[i]->oid, supported, &present))) | |
95 | present = 0; | |
96 | if (present) | |
97 | gss_add_oid_set_member(&min_status, | |
98 | &supported_mechs[i]->oid, oidset); | |
99 | i++; | |
100 | } | |
101 | } | |
102 | ||
103 | ||
104 | /* Wrapper around accept_sec_context | |
105 | * Requires that the context contains: | |
106 | * oid | |
107 | * credentials (from ssh_gssapi_acquire_cred) | |
108 | */ | |
109 | /* Priviledged */ | |
110 | OM_uint32 | |
111 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
112 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
113 | { | |
114 | OM_uint32 status; | |
115 | gss_OID mech; | |
116 | ||
117 | ctx->major = gss_accept_sec_context(&ctx->minor, | |
118 | &ctx->context, ctx->creds, recv_tok, | |
119 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, | |
120 | send_tok, flags, NULL, &ctx->client_creds); | |
121 | ||
122 | if (GSS_ERROR(ctx->major)) | |
123 | ssh_gssapi_error(ctx); | |
124 | ||
125 | if (ctx->client_creds) | |
126 | debug("Received some client credentials"); | |
127 | else | |
128 | debug("Got no client credentials"); | |
129 | ||
130 | status = ctx->major; | |
131 | ||
132 | /* Now, if we're complete and we have the right flags, then | |
133 | * we flag the user as also having been authenticated | |
134 | */ | |
135 | ||
136 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && | |
137 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { | |
138 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) | |
139 | fatal("Couldn't convert client name"); | |
b4cfa386 | 140 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
141 | if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG)) | |
142 | limited=1; | |
143 | #endif | |
7cac2b65 | 144 | } |
145 | ||
146 | return (status); | |
147 | } | |
148 | ||
149 | /* | |
150 | * This parses an exported name, extracting the mechanism specific portion | |
151 | * to use for ACL checking. It verifies that the name belongs the mechanism | |
152 | * originally selected. | |
153 | */ | |
154 | static OM_uint32 | |
155 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
156 | { | |
157 | char *tok; | |
158 | OM_uint32 offset; | |
159 | OM_uint32 oidl; | |
160 | ||
161 | tok=ename->value; | |
162 | ||
163 | #ifdef GSI /* GSI gss_export_name() is broken. */ | |
164 | if ((ctx->oid->length == gssapi_gsi_mech.oid.length) && | |
165 | (memcmp(ctx->oid->elements, gssapi_gsi_mech.oid.elements, | |
166 | gssapi_gsi_mech.oid.length) == 0)) { | |
167 | name->length = ename->length; | |
168 | name->value = xmalloc(ename->length+1); | |
169 | memcpy(name->value, ename->value, ename->length); | |
170 | return GSS_S_COMPLETE; | |
171 | } | |
172 | #endif | |
173 | ||
174 | /* | |
175 | * Check that ename is long enough for all of the fixed length | |
176 | * header, and that the initial ID bytes are correct | |
177 | */ | |
178 | ||
179 | if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0) | |
180 | return GSS_S_FAILURE; | |
181 | ||
182 | /* | |
183 | * Extract the OID, and check it. Here GSSAPI breaks with tradition | |
184 | * and does use the OID type and length bytes. To confuse things | |
185 | * there are two lengths - the first including these, and the | |
186 | * second without. | |
187 | */ | |
188 | ||
189 | oidl = GET_16BIT(tok+2); /* length including next two bytes */ | |
190 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ | |
191 | ||
192 | /* | |
193 | * Check the BER encoding for correct type and length, that the | |
194 | * string is long enough and that the OID matches that in our context | |
195 | */ | |
196 | if (tok[4] != 0x06 || tok[5] != oidl || | |
197 | ename->length < oidl+6 || | |
198 | !ssh_gssapi_check_oid(ctx,tok+6,oidl)) | |
199 | return GSS_S_FAILURE; | |
200 | ||
201 | offset = oidl+6; | |
202 | ||
203 | if (ename->length < offset+4) | |
204 | return GSS_S_FAILURE; | |
205 | ||
206 | name->length = GET_32BIT(tok+offset); | |
207 | offset += 4; | |
208 | ||
209 | if (ename->length < offset+name->length) | |
210 | return GSS_S_FAILURE; | |
211 | ||
212 | name->value = xmalloc(name->length+1); | |
213 | memcpy(name->value,tok+offset,name->length); | |
214 | ((char *)name->value)[name->length] = 0; | |
215 | ||
216 | return GSS_S_COMPLETE; | |
217 | } | |
218 | ||
219 | /* Extract the client details from a given context. This can only reliably | |
220 | * be called once for a context */ | |
221 | ||
222 | /* Priviledged (called from accept_secure_ctx) */ | |
223 | OM_uint32 | |
224 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
225 | { | |
226 | int i = 0; | |
227 | ||
228 | gss_buffer_desc ename; | |
229 | ||
230 | client->mech = NULL; | |
231 | ||
232 | while (supported_mechs[i]->name != NULL) { | |
233 | if (supported_mechs[i]->oid.length == ctx->oid->length && | |
234 | (memcmp(supported_mechs[i]->oid.elements, | |
235 | ctx->oid->elements, ctx->oid->length) == 0)) | |
236 | client->mech = supported_mechs[i]; | |
237 | i++; | |
238 | } | |
239 | ||
240 | if (client->mech == NULL) | |
241 | return GSS_S_FAILURE; | |
242 | ||
243 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
244 | &client->displayname, NULL))) { | |
245 | ssh_gssapi_error(ctx); | |
246 | return (ctx->major); | |
247 | } | |
248 | ||
249 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
250 | &ename))) { | |
251 | ssh_gssapi_error(ctx); | |
252 | return (ctx->major); | |
253 | } | |
254 | ||
255 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
256 | &client->exportedname))) { | |
257 | return (ctx->major); | |
258 | } | |
259 | ||
260 | /* We can't copy this structure, so we just move the pointer to it */ | |
261 | client->creds = ctx->client_creds; | |
262 | ctx->client_creds = GSS_C_NO_CREDENTIAL; | |
263 | return (ctx->major); | |
264 | } | |
265 | ||
540d72c3 | 266 | /* As user - called on fatal/exit */ |
7cac2b65 | 267 | void |
540d72c3 | 268 | ssh_gssapi_cleanup_creds(void) |
7cac2b65 | 269 | { |
270 | if (gssapi_client.store.filename != NULL) { | |
271 | /* Unlink probably isn't sufficient */ | |
272 | debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename); | |
273 | unlink(gssapi_client.store.filename); | |
274 | } | |
275 | } | |
276 | ||
277 | /* As user */ | |
278 | void | |
279 | ssh_gssapi_storecreds(void) | |
280 | { | |
281 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
282 | (*gssapi_client.mech->storecreds)(&gssapi_client); | |
7cac2b65 | 283 | } else |
284 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
285 | } | |
286 | ||
287 | /* This allows GSSAPI methods to do things to the childs environment based | |
288 | * on the passed authentication process and credentials. | |
289 | */ | |
290 | /* As user */ | |
291 | void | |
292 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
293 | { | |
294 | ||
295 | if (gssapi_client.store.envvar != NULL && | |
296 | gssapi_client.store.envval != NULL) { | |
297 | ||
298 | debug("Setting %s to %s", gssapi_client.store.envvar, | |
299 | gssapi_client.store.envval); | |
300 | child_set_env(envp, envsizep, gssapi_client.store.envvar, | |
301 | gssapi_client.store.envval); | |
302 | } | |
303 | } | |
304 | ||
305 | /* Priviledged */ | |
306 | int | |
307 | ssh_gssapi_userok(char *user) | |
308 | { | |
309 | if (gssapi_client.exportedname.length == 0 || | |
310 | gssapi_client.exportedname.value == NULL) { | |
311 | debug("No suitable client data"); | |
312 | return 0; | |
313 | } | |
b4cfa386 | 314 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
315 | if (limited) { | |
316 | debug("limited proxy not acceptable for remote login"); | |
317 | return 0; | |
318 | } | |
319 | #endif | |
7cac2b65 | 320 | if (gssapi_client.mech && gssapi_client.mech->userok) |
321 | return ((*gssapi_client.mech->userok)(&gssapi_client, user)); | |
322 | else | |
323 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
324 | return (0); | |
325 | } | |
326 | ||
23987cb8 | 327 | /* Return a list of the gss-group1-sha1-x mechanisms supported by this |
328 | * program. | |
5598e598 | 329 | * |
23987cb8 | 330 | * We only support the mechanisms that we've indicated in the list above, |
331 | * but we check that they're supported by the GSSAPI mechanism on the | |
332 | * machine. We also check, before including them in the list, that | |
333 | * we have the necesary information in order to carry out the key exchange | |
334 | * (that is, that the user has credentials, the server's creds are accessible, | |
335 | * etc) | |
336 | * | |
337 | * The way that this is done is fairly nasty, as we do a lot of work that | |
338 | * is then thrown away. This should possibly be implemented with a cache | |
339 | * that stores the results (in an expanded Gssctxt structure), which are | |
340 | * then used by the first calls if that key exchange mechanism is chosen. | |
6a8bca29 | 341 | */ |
e23e524c | 342 | |
343 | /* Unpriviledged */ | |
f001f132 | 344 | char * |
23987cb8 | 345 | ssh_gssapi_server_mechanisms() { |
f001f132 | 346 | gss_OID_set supported; |
23987cb8 | 347 | Gssctxt *ctx = NULL; |
f001f132 | 348 | OM_uint32 maj_status, min_status; |
349 | Buffer buf; | |
350 | int i = 0; | |
23987cb8 | 351 | int first = 0; |
f001f132 | 352 | int present; |
f001f132 | 353 | char * mechs; |
f001f132 | 354 | |
23987cb8 | 355 | ssh_gssapi_supported_oids(&supported); |
f001f132 | 356 | |
23987cb8 | 357 | buffer_init(&buf); |
f001f132 | 358 | |
23987cb8 | 359 | while(supported_mechs[i]->name != NULL) { |
f001f132 | 360 | if ((maj_status=gss_test_oid_set_member(&min_status, |
23987cb8 | 361 | &supported_mechs[i]->oid, |
f001f132 | 362 | supported, |
363 | &present))) { | |
364 | present=0; | |
365 | } | |
23987cb8 | 366 | |
f001f132 | 367 | if (present) { |
23987cb8 | 368 | if (!GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, |
369 | &supported_mechs[i]->oid)))) { | |
370 | /* Append gss_group1_sha1_x to our list */ | |
371 | if (first++!=0) | |
372 | buffer_put_char(&buf,','); | |
373 | buffer_append(&buf, KEX_GSS_SHA1, | |
374 | sizeof(KEX_GSS_SHA1)-1); | |
375 | buffer_append(&buf, | |
376 | supported_mechs[i]->enc_name, | |
377 | strlen(supported_mechs[i]->enc_name)); | |
378 | debug("GSSAPI mechanism %s (%s%s) supported", | |
379 | supported_mechs[i]->name, KEX_GSS_SHA1, | |
380 | supported_mechs[i]->enc_name); | |
381 | } else { | |
382 | debug("no credentials for GSSAPI mechanism %s", | |
383 | supported_mechs[i]->name); | |
384 | } | |
385 | } else { | |
f001f132 | 386 | debug("GSSAPI mechanism %s not supported", |
23987cb8 | 387 | supported_mechs[i]->name); |
f001f132 | 388 | } |
23987cb8 | 389 | ssh_gssapi_delete_ctx(&ctx); |
390 | i++; | |
391 | } | |
f001f132 | 392 | |
393 | buffer_put_char(&buf,'\0'); | |
394 | ||
395 | mechs=xmalloc(buffer_len(&buf)); | |
396 | buffer_get(&buf,mechs,buffer_len(&buf)); | |
397 | buffer_free(&buf); | |
f6c8c2f9 | 398 | if (strlen(mechs)==0) { |
399 | options.gss_authentication = 0; /* no mechs. skip gss auth. */ | |
400 | return(NULL); | |
401 | } else { | |
402 | return(mechs); | |
403 | } | |
f001f132 | 404 | } |
405 | ||
e23e524c | 406 | /* Return the OID that corresponds to the given context name */ |
23987cb8 | 407 | |
e23e524c | 408 | /* Unpriviledged */ |
23987cb8 | 409 | gss_OID |
e23e524c | 410 | ssh_gssapi_server_id_kex(char *name) { |
23987cb8 | 411 | int i=0; |
412 | ||
413 | if (strncmp(name, KEX_GSS_SHA1, sizeof(KEX_GSS_SHA1)-1) !=0) { | |
414 | return(NULL); | |
415 | } | |
416 | ||
417 | name+=sizeof(KEX_GSS_SHA1)-1; /* Move to the start of the MIME string */ | |
418 | ||
419 | while (supported_mechs[i]->name!=NULL && | |
e23e524c | 420 | strcmp(name,supported_mechs[i]->enc_name)!=0) { |
23987cb8 | 421 | i++; |
422 | } | |
423 | ||
424 | if (supported_mechs[i]->name==NULL) | |
425 | return (NULL); | |
426 | ||
23987cb8 | 427 | debug("using GSSAPI mechanism %s (%s%s)", supported_mechs[i]->name, |
428 | KEX_GSS_SHA1, supported_mechs[i]->enc_name); | |
429 | ||
430 | return &supported_mechs[i]->oid; | |
431 | } | |
432 | ||
e23e524c | 433 | /* Priviledged */ |
23987cb8 | 434 | int |
435 | ssh_gssapi_localname(char **user) | |
436 | { | |
437 | *user = NULL; | |
7cac2b65 | 438 | if (gssapi_client.displayname.length==0 || |
439 | gssapi_client.displayname.value==NULL) { | |
23987cb8 | 440 | debug("No suitable client data"); |
441 | return(0);; | |
442 | } | |
443 | if (gssapi_client.mech && gssapi_client.mech->localname) { | |
444 | return((*gssapi_client.mech->localname)(&gssapi_client,user)); | |
445 | } else { | |
446 | debug("Unknown client authentication type"); | |
447 | } | |
448 | return(0); | |
449 | } | |
540d72c3 | 450 | |
451 | /* Priviledged */ | |
452 | OM_uint32 | |
453 | ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) | |
454 | { | |
455 | ctx->major = gss_verify_mic(&ctx->minor, ctx->context, | |
456 | gssbuf, gssmic, NULL); | |
457 | ||
458 | return (ctx->major); | |
459 | } | |
460 | ||
23987cb8 | 461 | #endif |