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b9a54c29 1/*
ff2d7a98 2 * Copyright (c) 2001,2002 Simon Wilkinson. All rights reserved. *
b9a54c29 3 * Redistribution and use in source and binary forms, with or without
4 * modification, are permitted provided that the following conditions
5 * are met:
6 * 1. Redistributions of source code must retain the above copyright
7 * notice, this list of conditions and the following disclaimer.
8 * 2. Redistributions in binary form must reproduce the above copyright
9 * notice, this list of conditions and the following disclaimer in the
10 * documentation and/or other materials provided with the distribution.
11 *
12 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
13 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
14 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
15 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
16 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
17 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
18 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
19 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
20 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
21 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
22 */
23
24#include "includes.h"
25
26#ifdef GSSAPI
27
28#include "ssh.h"
29#include "ssh2.h"
30#include "xmalloc.h"
31#include "buffer.h"
32#include "bufaux.h"
33#include "packet.h"
34#include "compat.h"
35#include <openssl/evp.h>
36#include "cipher.h"
37#include "kex.h"
38#include "log.h"
39#include "compat.h"
ff2d7a98 40#include "monitor_wrap.h"
c2397a66 41#include "canohost.h"
b9a54c29 42
43#include <netdb.h>
44
45#include "ssh-gss.h"
46
47/* Assorted globals for tracking the clients identity once they've
48 * authenticated */
49
50gss_buffer_desc gssapi_client_name = {0,NULL}; /* Name of our client */
51gss_cred_id_t gssapi_client_creds = GSS_C_NO_CREDENTIAL; /* Their credentials */
52enum ssh_gss_id gssapi_client_type = GSS_LAST_ENTRY;
53
ff2d7a98 54unsigned char ssh1_key_digest[16]; /* used for ssh1 gssapi */
55
b9a54c29 56/* The mechanism name used in the list below is defined in the internet
57 * draft as the Base 64 encoding of the MD5 hash of the ASN.1 DER encoding
58 * of the underlying GSSAPI mechanism's OID.
59 *
60 * Also from the draft, before considering adding SPNEGO, bear in mind that
61 * "mechanisms ... MUST NOT use SPNEGO as the underlying GSSAPI mechanism"
62 */
63
64/* These must be in the same order as ssh_gss_id, in ssh-gss.h */
65
66ssh_gssapi_mech supported_mechs[]= {
67#ifdef KRB5
68 /* Official OID - 1.2.850.113554.1.2.2 */
69 {"Se3H81ismmOC3OE+FwYCiQ==","Kerberos",
70 {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}},
71#endif
72#ifdef GSI
73 /* gssapi_ssleay 1.3.6.1.4.1.3536.1.1 */
74 {"N3+k7/4wGxHyuP8Yxi4RhA==",
75 "GSI",
76 {9, "\x2B\x06\x01\x04\x01\x9B\x50\x01\x01"}
77 },
78#endif /* GSI */
79 {NULL,NULL,{0,0}}
80};
81
82char gssprefix[]=KEX_GSS_SHA1;
83
84/* Return a list of the gss-group1-sha1-x mechanisms supported by this
85 * program.
86 *
87 * We only support the mechanisms that we've indicated in the list above,
88 * but we check that they're supported by the GSSAPI mechanism on the
89 * machine. We also check, before including them in the list, that
90 * we have the necesary information in order to carry out the key exchange
91 * (that is, that the user has credentials, the server's creds are accessible,
92 * etc)
93 *
94 * The way that this is done is fairly nasty, as we do a lot of work that
95 * is then thrown away. This should possibly be implemented with a cache
96 * that stores the results (in an expanded Gssctxt structure), which are
97 * then used by the first calls if that key exchange mechanism is chosen.
98 */
99
100char *
101ssh_gssapi_mechanisms(int server,char *host) {
102 gss_OID_set supported;
103 OM_uint32 maj_status, min_status;
104 Buffer buf;
105 int i = 0;
106 int present;
c2397a66 107 int mech_count=0;
b9a54c29 108 char * mechs;
ff2d7a98 109 Gssctxt * ctx = NULL;
b9a54c29 110
111 if (datafellows & SSH_OLD_GSSAPI) return NULL;
112
98f19977 113 PRIVSEP(gss_indicate_mechs(&min_status, &supported));
b9a54c29 114
115 buffer_init(&buf);
116
117 do {
118 if ((maj_status=gss_test_oid_set_member(&min_status,
119 &supported_mechs[i].oid,
120 supported,
121 &present))) {
122 present=0;
123 }
124 if (present) {
ff2d7a98 125 if ((server &&
126 !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx,
127 &supported_mechs[i].oid))))
128 || (!server &&
129 !GSS_ERROR(ssh_gssapi_client_ctx(&ctx,
130 &supported_mechs[i].oid,
131 host)))) {
132 /* Append gss_group1_sha1_x to our list */
c2397a66 133 if (++mech_count > 1) {
134 buffer_append(&buf, ",", 1);
135 }
ff2d7a98 136 buffer_append(&buf, gssprefix,
137 strlen(gssprefix));
138 buffer_append(&buf,
139 supported_mechs[i].enc_name,
140 strlen(supported_mechs[i].enc_name));
c2397a66 141 debug("GSSAPI mechanism %s (%s%s) supported",
142 supported_mechs[i].name, gssprefix,
143 supported_mechs[i].enc_name);
144 } else {
145 debug("no credentials for GSSAPI mechanism %s",
146 supported_mechs[i].name);
147 }
148 } else {
149 debug("GSSAPI mechanism %s not supported",
150 supported_mechs[i].name);
151 }
b9a54c29 152 } while (supported_mechs[++i].name != NULL);
153
154 buffer_put_char(&buf,'\0');
155
156 mechs=xmalloc(buffer_len(&buf));
157 buffer_get(&buf,mechs,buffer_len(&buf));
158 buffer_free(&buf);
159 if (strlen(mechs)==0)
160 return(NULL);
161 else
162 return(mechs);
163}
164
165void ssh_gssapi_supported_oids(gss_OID_set *oidset) {
166 enum ssh_gss_id i =0;
167 OM_uint32 maj_status,min_status;
168 int present;
169 gss_OID_set supported;
170
171 gss_create_empty_oid_set(&min_status,oidset);
98f19977 172 PRIVSEP(gss_indicate_mechs(&min_status, &supported));
b9a54c29 173
174 while (supported_mechs[i].name!=NULL) {
175 if ((maj_status=gss_test_oid_set_member(&min_status,
176 &supported_mechs[i].oid,
177 supported,
178 &present))) {
179 present=0;
180 }
181 if (present) {
182 gss_add_oid_set_member(&min_status,
183 &supported_mechs[i].oid,
184 oidset);
185 }
186 i++;
187 }
188}
189
190/* Set the contexts OID from a data stream */
191void ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) {
192 if (ctx->oid != GSS_C_NO_OID) {
193 xfree(ctx->oid->elements);
194 xfree(ctx->oid);
195 }
196 ctx->oid=xmalloc(sizeof(gss_OID_desc));
197 ctx->oid->length=len;
198 ctx->oid->elements=xmalloc(len);
199 memcpy(ctx->oid->elements,data,len);
200}
201
202/* Set the contexts OID */
203void ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) {
204 ssh_gssapi_set_oid_data(ctx,oid->elements,oid->length);
205}
206
207/* Find out which GSS type (out of the list we define in ssh-gss.h) a
208 * particular connection is using
209 */
210enum ssh_gss_id ssh_gssapi_get_ctype(Gssctxt *ctxt) {
211 enum ssh_gss_id i=0;
212
c2397a66 213 while(supported_mechs[i].name!=NULL) {
214 if (supported_mechs[i].oid.length == ctxt->oid->length &&
215 (memcmp(supported_mechs[i].oid.elements,
216 ctxt->oid->elements,ctxt->oid->length) == 0))
217 return i;
b9a54c29 218 i++;
219 }
c2397a66 220 return(GSS_LAST_ENTRY);
b9a54c29 221}
222
223/* Set the GSS context's OID to the oid indicated by the given key exchange
224 * name. */
ff2d7a98 225gss_OID ssh_gssapi_id_kex(Gssctxt *ctx, char *name) {
b9a54c29 226 enum ssh_gss_id i=0;
227
228 if (strncmp(name, gssprefix, strlen(gssprefix)-1) !=0) {
ff2d7a98 229 return(NULL);
b9a54c29 230 }
231
232 name+=strlen(gssprefix); /* Move to the start of the MIME string */
233
234 while (supported_mechs[i].name!=NULL &&
235 strcmp(name,supported_mechs[i].enc_name)!=0) {
236 i++;
237 }
238
239 if (supported_mechs[i].name==NULL)
ff2d7a98 240 return (NULL);
b9a54c29 241
ff2d7a98 242 if (ctx) ssh_gssapi_set_oid(ctx,&supported_mechs[i].oid);
b9a54c29 243
c2397a66 244 debug("using GSSAPI mechanism %s (%s%s)", supported_mechs[i].name,
245 gssprefix, supported_mechs[i].enc_name);
246
ff2d7a98 247 return &supported_mechs[i].oid;
b9a54c29 248}
249
250
251/* All this effort to report an error ... */
078f71c2 252static void
67e2750c 253ssh_gssapi_error_ex(gss_OID mech, OM_uint32 major_status,
254 OM_uint32 minor_status,
078f71c2 255 int send_packet) {
b9a54c29 256 OM_uint32 lmaj, lmin;
c2397a66 257 gss_buffer_desc msg = {0,NULL};
b9a54c29 258 OM_uint32 ctx;
259
260 ctx = 0;
261 /* The GSSAPI error */
262 do {
98f19977 263 lmaj = PRIVSEP(gss_display_status(&lmin, major_status,
264 GSS_C_GSS_CODE,
265 mech,
266 &ctx, &msg));
b9a54c29 267 if (lmaj == GSS_S_COMPLETE) {
268 debug((char *)msg.value);
078f71c2 269 if (send_packet) packet_send_debug((char *)msg.value);
b9a54c29 270 (void) gss_release_buffer(&lmin, &msg);
271 }
272 } while (ctx!=0);
273
274 /* The mechanism specific error */
275 do {
98f19977 276 lmaj = PRIVSEP(gss_display_status(&lmin, minor_status,
277 GSS_C_MECH_CODE,
278 mech,
279 &ctx, &msg));
b9a54c29 280 if (lmaj == GSS_S_COMPLETE) {
281 debug((char *)msg.value);
078f71c2 282 if (send_packet) packet_send_debug((char *)msg.value);
b9a54c29 283 (void) gss_release_buffer(&lmin, &msg);
284 }
285 } while (ctx!=0);
286}
287
078f71c2 288void
67e2750c 289ssh_gssapi_error(gss_OID mech,OM_uint32 major_status,OM_uint32 minor_status) {
290 ssh_gssapi_error_ex(mech, major_status, minor_status, 0);
078f71c2 291}
292
293void
67e2750c 294ssh_gssapi_send_error(gss_OID mech,
295 OM_uint32 major_status,OM_uint32 minor_status) {
296 ssh_gssapi_error_ex(mech, major_status, minor_status, 1);
078f71c2 297}
298
299
300
301
b9a54c29 302/* Initialise our GSSAPI context. We use this opaque structure to contain all
303 * of the data which both the client and server need to persist across
304 * {accept,init}_sec_context calls, so that when we do it from the userauth
305 * stuff life is a little easier
306 */
307void
ff2d7a98 308ssh_gssapi_build_ctx(Gssctxt **ctx)
b9a54c29 309{
ff2d7a98 310 *ctx=xmalloc(sizeof (Gssctxt));
311 (*ctx)->context=GSS_C_NO_CONTEXT;
312 (*ctx)->name=GSS_C_NO_NAME;
313 (*ctx)->oid=GSS_C_NO_OID;
314 (*ctx)->creds=GSS_C_NO_CREDENTIAL;
315 (*ctx)->client=GSS_C_NO_NAME;
316 (*ctx)->client_creds=GSS_C_NO_CREDENTIAL;
b9a54c29 317}
318
319/* Delete our context, providing it has been built correctly */
320void
ff2d7a98 321ssh_gssapi_delete_ctx(Gssctxt **ctx)
b9a54c29 322{
98f19977 323#if !defined(MECHGLUE)
b9a54c29 324 OM_uint32 ms;
98f19977 325#endif
b9a54c29 326
ff2d7a98 327 /* Return if there's no context */
328 if ((*ctx)==NULL)
329 return;
330
c2397a66 331#if !defined(MECHGLUE) /* mechglue has some memory management issues */
ff2d7a98 332 if ((*ctx)->context != GSS_C_NO_CONTEXT)
333 gss_delete_sec_context(&ms,&(*ctx)->context,GSS_C_NO_BUFFER);
334 if ((*ctx)->name != GSS_C_NO_NAME)
335 gss_release_name(&ms,&(*ctx)->name);
336 if ((*ctx)->oid != GSS_C_NO_OID) {
337 xfree((*ctx)->oid->elements);
338 xfree((*ctx)->oid);
339 (*ctx)->oid = GSS_C_NO_OID;
b9a54c29 340 }
ff2d7a98 341 if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
342 gss_release_cred(&ms,&(*ctx)->creds);
343 if ((*ctx)->client != GSS_C_NO_NAME)
344 gss_release_name(&ms,&(*ctx)->client);
345 if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
346 gss_release_cred(&ms,&(*ctx)->client_creds);
c2397a66 347#endif
ff2d7a98 348
349 xfree(*ctx);
350 *ctx=NULL;
b9a54c29 351}
352
353/* Wrapper to init_sec_context
354 * Requires that the context contains:
355 * oid
356 * server name (from ssh_gssapi_import_name)
357 */
358OM_uint32
359ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
360 gss_buffer_desc* send_tok, OM_uint32 *flags)
361{
362 OM_uint32 maj_status, min_status;
363 int deleg_flag = 0;
364
365 if (deleg_creds) {
366 deleg_flag=GSS_C_DELEG_FLAG;
367 debug("Delegating credentials");
368 }
369
370 maj_status=gss_init_sec_context(&min_status,
371 GSS_C_NO_CREDENTIAL, /* def. cred */
372 &ctx->context,
373 ctx->name,
374 ctx->oid,
375 GSS_C_MUTUAL_FLAG |
376 GSS_C_INTEG_FLAG |
377 deleg_flag,
378 0, /* default lifetime */
379 NULL, /* no channel bindings */
380 recv_tok,
381 NULL,
382 send_tok,
383 flags,
384 NULL);
385 ctx->status=maj_status;
386 if (GSS_ERROR(maj_status)) {
67e2750c 387 ssh_gssapi_error(ctx->oid,maj_status,min_status);
b9a54c29 388 }
389 return(maj_status);
390}
391
392/* Wrapper arround accept_sec_context
393 * Requires that the context contains:
394 * oid
395 * credentials (from ssh_gssapi_acquire_cred)
396 */
397OM_uint32 ssh_gssapi_accept_ctx(Gssctxt *ctx,gss_buffer_desc *recv_tok,
398 gss_buffer_desc *send_tok, OM_uint32 *flags)
399{
400 OM_uint32 maj_status, min_status;
98f19977 401 gss_OID mech;
b9a54c29 402
403 maj_status=gss_accept_sec_context(&min_status,
404 &ctx->context,
405 ctx->creds,
406 recv_tok,
407 GSS_C_NO_CHANNEL_BINDINGS,
408 &ctx->client,
98f19977 409 &mech, /* read-only pointer */
b9a54c29 410 send_tok,
411 flags,
412 NULL,
413 &ctx->client_creds);
414 if (GSS_ERROR(maj_status)) {
67e2750c 415 ssh_gssapi_send_error(ctx->oid,maj_status,min_status);
b9a54c29 416 }
417
418 if (ctx->client_creds) {
419 debug("Received some client credentials");
420 } else {
421 debug("Got no client credentials");
422 }
423
ff2d7a98 424 /* FIXME: We should check that the me
b9a54c29 425 * the one that we asked for (in ctx->oid) */
426
427 ctx->status=maj_status;
428
ff2d7a98 429 /* Now, if we're complete and we have the right flags, then
430 * we flag the user as also having been authenticated
431 */
432
433 if (((flags==NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
434 (*flags & GSS_C_INTEG_FLAG))) &&
435 (maj_status == GSS_S_COMPLETE)) {
436 if (ssh_gssapi_getclient(ctx,&gssapi_client_type,
437 &gssapi_client_name,
438 &gssapi_client_creds))
439 fatal("Couldn't convert client name");
440 }
441
b9a54c29 442 return(maj_status);
443}
444
445/* Create a service name for the given host */
446OM_uint32
447ssh_gssapi_import_name(Gssctxt *ctx, const char *host) {
c2397a66 448 gss_buffer_desc gssbuf = {0,NULL};
b9a54c29 449 OM_uint32 maj_status, min_status;
b9a54c29 450 char *xhost;
451
452 /* Make a copy of the host name, in case it was returned by a
453 * previous call to gethostbyname(). */
454 xhost = xstrdup(host);
455
c2397a66 456 /* If xhost is the loopback interface, switch it to our
457 true local hostname. */
458 resolve_localhost(&xhost);
459
460 /* Make sure we have the FQHN. Some GSSAPI implementations don't do
b9a54c29 461 * this for us themselves */
c2397a66 462 make_fqhn(&xhost);
463
b9a54c29 464 gssbuf.length = sizeof("host@")+strlen(xhost);
465
466 gssbuf.value = xmalloc(gssbuf.length);
467 if (gssbuf.value == NULL) {
468 xfree(xhost);
469 return(-1);
470 }
471 snprintf(gssbuf.value,gssbuf.length,"host@%s",xhost);
472 if ((maj_status=gss_import_name(&min_status,
473 &gssbuf,
474 GSS_C_NT_HOSTBASED_SERVICE,
475 &ctx->name))) {
67e2750c 476 ssh_gssapi_error(ctx->oid, maj_status,min_status);
b9a54c29 477 }
478
479 xfree(xhost);
480 xfree(gssbuf.value);
481 return(maj_status);
482}
483
484/* Acquire credentials for a server running on the current host.
485 * Requires that the context structure contains a valid OID
ff2d7a98 486 */
487
488/* Returns a GSSAPI error code */
b9a54c29 489OM_uint32
490ssh_gssapi_acquire_cred(Gssctxt *ctx) {
491 OM_uint32 maj_status, min_status;
492 char lname[MAXHOSTNAMELEN];
493 gss_OID_set oidset;
494
495 gss_create_empty_oid_set(&min_status,&oidset);
496 gss_add_oid_set_member(&min_status,ctx->oid,&oidset);
497
498 if (gethostname(lname, MAXHOSTNAMELEN)) {
499 return(-1);
500 }
501
502 if ((maj_status=ssh_gssapi_import_name(ctx,lname))) {
503 return(maj_status);
504 }
505 if ((maj_status=gss_acquire_cred(&min_status,
506 ctx->name,
507 0,
508 oidset,
509 GSS_C_ACCEPT,
510 &ctx->creds,
511 NULL,
512 NULL))) {
98f19977 513 ssh_gssapi_error(ctx->oid,maj_status,min_status);
b9a54c29 514 }
515
516 gss_release_oid_set(&min_status, &oidset);
517 return(maj_status);
518}
519
520/* Extract the client details from a given context. This can only reliably
521 * be called once for a context */
522
523OM_uint32
524ssh_gssapi_getclient(Gssctxt *ctx, enum ssh_gss_id *type,
525 gss_buffer_desc *name, gss_cred_id_t *creds) {
526
527 OM_uint32 maj_status,min_status;
528
529 *type=ssh_gssapi_get_ctype(ctx);
530 if ((maj_status=gss_display_name(&min_status,ctx->client,name,NULL))) {
98f19977 531 ssh_gssapi_error(ctx->oid,maj_status,min_status);
b9a54c29 532 }
533
534 /* This is icky. There appears to be no way to copy this structure,
535 * rather than the pointer to it, so we simply copy the pointer and
536 * mark the originator as empty so we don't destroy it.
537 */
538 *creds=ctx->client_creds;
539 ctx->client_creds=GSS_C_NO_CREDENTIAL;
540 return(maj_status);
541}
ff2d7a98 542
543OM_uint32
544ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_desc *buffer, gss_buffer_desc *hash) {
545 OM_uint32 maj_status,min_status;
b9a54c29 546
ff2d7a98 547 /* ssh1 needs to exchange the hash of the keys */
548 /* will us this hash to return it */
549 if (!compat20) {
550 if ((maj_status=gss_wrap(&min_status,ctx->context,
551 0,
552 GSS_C_QOP_DEFAULT,
553 buffer,
554 NULL,
555 hash)))
67e2750c 556 ssh_gssapi_error(ctx->oid,maj_status,min_status);
ff2d7a98 557 }
558 else
559
560 if ((maj_status=gss_get_mic(&min_status,ctx->context,
561 GSS_C_QOP_DEFAULT, buffer, hash))) {
67e2750c 562 ssh_gssapi_error(ctx->oid,maj_status,min_status);
ff2d7a98 563 }
564
565 return(maj_status);
566}
567
568OM_uint32
569ssh_gssapi_server_ctx(Gssctxt **ctx,gss_OID oid) {
570 if (*ctx) ssh_gssapi_delete_ctx(ctx);
571 ssh_gssapi_build_ctx(ctx);
572 ssh_gssapi_set_oid(*ctx,oid);
573 return(ssh_gssapi_acquire_cred(*ctx));
574}
575
576OM_uint32
577ssh_gssapi_client_ctx(Gssctxt **ctx,gss_OID oid, char *host) {
c2397a66 578 gss_buffer_desc token = {0,NULL};
ff2d7a98 579 OM_uint32 major,minor;
580
581 if (*ctx) ssh_gssapi_delete_ctx(ctx);
582 ssh_gssapi_build_ctx(ctx);
583 ssh_gssapi_set_oid(*ctx,oid);
584 ssh_gssapi_import_name(*ctx,host);
585 major=ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, NULL);
586 gss_release_buffer(&minor,&token);
587 return(major);
588}
589
b9a54c29 590#endif /* GSSAPI */
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