1 /*
2 * Copyright (c) 2010, Oracle America, Inc.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following
12 * disclaimer in the documentation and/or other materials
13 * provided with the distribution.
14 * * Neither the name of the "Oracle America, Inc." nor the names of its
15 * contributors may be used to endorse or promote products derived
16 * from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
22 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
23 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
25 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 * svcauth_des.c, server-side des authentication
32 *
33 * We insure for the service the following:
34 * (1) The timestamp microseconds do not exceed 1 million.
35 * (2) The timestamp plus the window is less than the current time.
36 * (3) The timestamp is not less than the one previously
37 * seen in the current session.
38 *
39 * It is up to the server to determine if the window size is
40 * too small .
41 *
42 */
43
44 #include <limits.h>
45 #include <string.h>
46 #include <stdint.h>
47 #include <time.h>
48 #include <sys/param.h>
49 #include <netinet/in.h>
50 #include <rpc/rpc.h>
51 #include <rpc/xdr.h>
52 #include <rpc/auth.h>
53 #include <rpc/auth_des.h>
54 #include <rpc/svc_auth.h>
55 #include <rpc/svc.h>
56 #include <rpc/des_crypt.h>
57 #include <shlib-compat.h>
58
59 #define debug(msg) /*printf("svcauth_des: %s\n", msg) */
60
61 #define BEFORE(t1, t2) timercmp(t1, t2, <)
62
63 /*
64 * LRU cache of conversation keys and some other useful items.
65 */
66 #define AUTHDES_CACHESZ 64
67 struct cache_entry
68 {
69 des_block key; /* conversation key */
70 char *rname; /* client's name */
71 u_int window; /* credential lifetime window */
72 struct rpc_timeval laststamp; /* detect replays of creds */
73 char *localcred; /* generic local credential */
74 };
75 #define authdes_cache RPC_THREAD_VARIABLE(authdes_cache_s)
76 #define authdes_lru RPC_THREAD_VARIABLE(authdes_lru_s)
77
78 static void cache_init (void); /* initialize the cache */
79 static short cache_spot (des_block *, char *, struct rpc_timeval *);
80 /* find an entry in the cache */
81 static void cache_ref (uint32_t sid); /* note that sid was ref'd */
82
83 static void invalidate (char *cred); /* invalidate entry in cache */
84
85 /* Cache statistics. Accidental historic export without a matching
86 declaration in any header file. */
87 #ifndef SHARED
88 static
89 #endif
90 struct
91 {
92 u_long ncachehits; /* times cache hit, and is not replay */
93 u_long ncachereplays; /* times cache hit, and is replay */
94 u_long ncachemisses; /* times cache missed */
95 }
96 svcauthdes_stats;
97 #ifdef SHARED
98 compat_symbol (libc, svcauthdes_stats, svcauthdes_stats, GLIBC_2_0);
99 #endif
100
101 /*
102 * Service side authenticator for AUTH_DES
103 */
104 enum auth_stat
105 _svcauth_des (register struct svc_req *rqst, register struct rpc_msg *msg)
106 {
107 register uint32_t *ixdr;
108 des_block cryptbuf[2];
109 register struct authdes_cred *cred;
110 struct authdes_verf verf;
111 int status;
112 register struct cache_entry *entry;
113 uint32_t sid = 0;
114 des_block *sessionkey;
115 des_block ivec;
116 u_int window;
117 struct rpc_timeval timestamp;
118 uint32_t namelen;
119 struct area
120 {
121 struct authdes_cred area_cred;
122 char area_netname[MAXNETNAMELEN + 1];
123 }
124 *area;
125
126 if (authdes_cache == NULL)
127 cache_init ();
128 if (authdes_cache == NULL) /* No free memory */
129 return AUTH_FAILED;
130
131 area = (struct area *) rqst->rq_clntcred;
132 cred = (struct authdes_cred *) &area->area_cred;
133
134 /*
135 * Get the credential
136 */
137 if (msg->rm_call.cb_cred.oa_length <= 0 ||
138 msg->rm_call.cb_cred.oa_length > MAX_AUTH_BYTES)
139 return AUTH_BADCRED;
140
141 ixdr = (uint32_t *) msg->rm_call.cb_cred.oa_base;
142 cred->adc_namekind = IXDR_GET_ENUM (ixdr, enum authdes_namekind);
143 switch (cred->adc_namekind)
144 {
145 case ADN_FULLNAME:
146 namelen = IXDR_GET_U_INT32 (ixdr);
147 if (namelen > MAXNETNAMELEN)
148 {
149 return AUTH_BADCRED;
150 }
151 cred->adc_fullname.name = area->area_netname;
152 memcpy (cred->adc_fullname.name, (char *) ixdr, namelen);
153 cred->adc_fullname.name[namelen] = 0;
154 ixdr += (RNDUP (namelen) / BYTES_PER_XDR_UNIT);
155 cred->adc_fullname.key.key.high = *ixdr++;
156 cred->adc_fullname.key.key.low = *ixdr++;
157 cred->adc_fullname.window = *ixdr++;
158 break;
159 case ADN_NICKNAME:
160 cred->adc_nickname = *ixdr++;
161 break;
162 default:
163 return AUTH_BADCRED;
164 }
165
166 /*
167 * Get the verifier
168 */
169 if (msg->rm_call.cb_verf.oa_length <= 0 ||
170 msg->rm_call.cb_verf.oa_length > MAX_AUTH_BYTES)
171 return AUTH_BADCRED;
172
173 ixdr = (uint32_t *) msg->rm_call.cb_verf.oa_base;
174 verf.adv_xtimestamp.key.high = *ixdr++;
175 verf.adv_xtimestamp.key.low = *ixdr++;
176 verf.adv_int_u = *ixdr++;
177
178 /*
179 * Get the conversation key
180 */
181 if (cred->adc_namekind == ADN_FULLNAME)
182 {
183 netobj pkey;
184 char pkey_data[1024];
185
186 sessionkey = &cred->adc_fullname.key;
187 if (!getpublickey (cred->adc_fullname.name, pkey_data))
188 {
189 debug("getpublickey");
190 return AUTH_BADCRED;
191 }
192 pkey.n_bytes = pkey_data;
193 pkey.n_len = strlen (pkey_data) + 1;
194 if (key_decryptsession_pk (cred->adc_fullname.name, &pkey,
195 sessionkey) < 0)
196 {
197 debug ("decryptsessionkey");
198 return AUTH_BADCRED; /* key not found */
199 }
200 }
201 else
202 { /* ADN_NICKNAME */
203 if (cred->adc_nickname >= AUTHDES_CACHESZ)
204 {
205 debug ("bad nickname");
206 return AUTH_BADCRED; /* garbled credential */
207 }
208 else
209 sid = cred->adc_nickname;
210
211 /* XXX This could be wrong, but else we have a
212 security problem */
213 if (authdes_cache[sid].rname == NULL)
214 return AUTH_BADCRED;
215 sessionkey = &authdes_cache[sid].key;
216 }
217
218
219 /*
220 * Decrypt the timestamp
221 */
222 cryptbuf[0] = verf.adv_xtimestamp;
223 if (cred->adc_namekind == ADN_FULLNAME)
224 {
225 cryptbuf[1].key.high = cred->adc_fullname.window;
226 cryptbuf[1].key.low = verf.adv_winverf;
227 ivec.key.high = ivec.key.low = 0;
228 status = cbc_crypt ((char *) sessionkey, (char *) cryptbuf,
229 2 * sizeof (des_block), DES_DECRYPT | DES_HW,
230 (char *) &ivec);
231 }
232 else
233 status = ecb_crypt ((char *) sessionkey, (char *) cryptbuf,
234 sizeof (des_block), DES_DECRYPT | DES_HW);
235
236 if (DES_FAILED (status))
237 {
238 debug ("decryption failure");
239 return AUTH_FAILED; /* system error */
240 }
241
242 /*
243 * XDR the decrypted timestamp
244 */
245 ixdr = (uint32_t *) cryptbuf;
246 timestamp.tv_sec = IXDR_GET_INT32 (ixdr);
247 timestamp.tv_usec = IXDR_GET_INT32 (ixdr);
248
249 /*
250 * Check for valid credentials and verifiers.
251 * They could be invalid because the key was flushed
252 * out of the cache, and so a new session should begin.
253 * Be sure and send AUTH_REJECTED{CRED, VERF} if this is the case.
254 */
255 {
256 struct timeval current;
257 int nick;
258 u_int winverf;
259
260 if (cred->adc_namekind == ADN_FULLNAME)
261 {
262 short tmp_spot;
263
264 window = IXDR_GET_U_INT32 (ixdr);
265 winverf = IXDR_GET_U_INT32 (ixdr);
266 if (winverf != window - 1)
267 {
268 debug ("window verifier mismatch");
269 return AUTH_BADCRED; /* garbled credential */
270 }
271 tmp_spot = cache_spot (sessionkey, cred->adc_fullname.name,
272 ×tamp);
273 if (tmp_spot < 0 || tmp_spot > AUTHDES_CACHESZ)
274 {
275 debug ("replayed credential");
276 return AUTH_REJECTEDCRED; /* replay */
277 }
278 sid = tmp_spot;
279 nick = 0;
280 }
281 else
282 { /* ADN_NICKNAME */
283 window = authdes_cache[sid].window;
284 nick = 1;
285 }
286
287 if (timestamp.tv_usec >= USEC_PER_SEC)
288 {
289 debug ("invalid usecs");
290 /* cached out (bad key), or garbled verifier */
291 return nick ? AUTH_REJECTEDVERF : AUTH_BADVERF;
292 }
293 if (nick && BEFORE (×tamp, &authdes_cache[sid].laststamp))
294 {
295 debug ("timestamp before last seen");
296 return AUTH_REJECTEDVERF; /* replay */
297 }
298 {
299 struct timespec now;
300 __clock_gettime (CLOCK_REALTIME, &now);
301 TIMESPEC_TO_TIMEVAL (¤t, &now);
302 }
303 current.tv_sec -= window; /* allow for expiration */
304 if (!BEFORE (¤t, ×tamp))
305 {
306 debug ("timestamp expired");
307 /* replay, or garbled credential */
308 return nick ? AUTH_REJECTEDVERF : AUTH_BADCRED;
309 }
310 }
311
312 /*
313 * Set up the reply verifier
314 */
315 verf.adv_nickname = sid;
316
317 /*
318 * xdr the timestamp before encrypting
319 */
320 ixdr = (uint32_t *) cryptbuf;
321 IXDR_PUT_INT32 (ixdr, timestamp.tv_sec - 1);
322 IXDR_PUT_INT32 (ixdr, timestamp.tv_usec);
323
324 /*
325 * encrypt the timestamp
326 */
327 status = ecb_crypt ((char *) sessionkey, (char *) cryptbuf,
328 sizeof (des_block), DES_ENCRYPT | DES_HW);
329 if (DES_FAILED (status))
330 {
331 debug ("encryption failure");
332 return AUTH_FAILED; /* system error */
333 }
334 verf.adv_xtimestamp = cryptbuf[0];
335
336 /*
337 * Serialize the reply verifier, and update rqst
338 */
339 ixdr = (uint32_t *) msg->rm_call.cb_verf.oa_base;
340 *ixdr++ = verf.adv_xtimestamp.key.high;
341 *ixdr++ = verf.adv_xtimestamp.key.low;
342 *ixdr++ = verf.adv_int_u;
343
344 rqst->rq_xprt->xp_verf.oa_flavor = AUTH_DES;
345 rqst->rq_xprt->xp_verf.oa_base = msg->rm_call.cb_verf.oa_base;
346 rqst->rq_xprt->xp_verf.oa_length =
347 (char *) ixdr - msg->rm_call.cb_verf.oa_base;
348
349 /*
350 * We succeeded, commit the data to the cache now and
351 * finish cooking the credential.
352 */
353 entry = &authdes_cache[sid];
354 entry->laststamp = timestamp;
355 cache_ref (sid);
356 if (cred->adc_namekind == ADN_FULLNAME)
357 {
358 size_t full_len;
359
360 cred->adc_fullname.window = window;
361 cred->adc_nickname = sid; /* save nickname */
362 if (entry->rname != NULL)
363 mem_free (entry->rname, strlen (entry->rname) + 1);
364 full_len = strlen (cred->adc_fullname.name) + 1;
365 entry->rname = mem_alloc ((u_int) full_len);
366 if (entry->rname != NULL)
367 memcpy (entry->rname, cred->adc_fullname.name, full_len);
368 else
369 {
370 debug ("out of memory");
371 return AUTH_FAILED; /* out of memory is bad */
372 }
373 entry->key = *sessionkey;
374 entry->window = window;
375 invalidate (entry->localcred); /* mark any cached cred invalid */
376 }
377 else
378 { /* ADN_NICKNAME */
379 /*
380 * nicknames are cooked into fullnames
381 */
382 cred->adc_namekind = ADN_FULLNAME;
383 cred->adc_fullname.name = entry->rname;
384 cred->adc_fullname.key = entry->key;
385 cred->adc_fullname.window = entry->window;
386 }
387 return AUTH_OK; /* we made it! */
388 }
389
390
391 /*
392 * Initialize the cache
393 */
394 static void
395 cache_init (void)
396 {
397 register int i;
398
399 authdes_cache = (struct cache_entry *)
400 calloc (sizeof (struct cache_entry) * AUTHDES_CACHESZ, 1);
401 if (authdes_cache == NULL)
402 return;
403
404 authdes_lru = (int *) mem_alloc (sizeof (int) * AUTHDES_CACHESZ);
405 /*
406 * Initialize the lru list
407 */
408 for (i = 0; i < AUTHDES_CACHESZ; ++i)
409 authdes_lru[i] = i;
410 }
411
412
413 /*
414 * Find the lru victim
415 */
416 static short
417 cache_victim (void)
418 {
419 return authdes_lru[AUTHDES_CACHESZ - 1];
420 }
421
422 /*
423 * Note that sid was referenced
424 */
425 static void
426 cache_ref (register uint32_t sid)
427 {
428 register int i;
429 register int curr;
430 register int prev;
431
432 prev = authdes_lru[0];
433 authdes_lru[0] = sid;
434 for (i = 1; prev != sid; ++i)
435 {
436 curr = authdes_lru[i];
437 authdes_lru[i] = prev;
438 prev = curr;
439 }
440 }
441
442 /*
443 * Find a spot in the cache for a credential containing
444 * the items given. Return -1 if a replay is detected, otherwise
445 * return the spot in the cache.
446 */
447 static short
448 cache_spot (register des_block *key, char *name,
449 struct rpc_timeval *timestamp)
450 {
451 register struct cache_entry *cp;
452 register int i;
453 register uint32_t hi;
454
455 hi = key->key.high;
456 for (cp = authdes_cache, i = 0; i < AUTHDES_CACHESZ; ++i, ++cp)
457 {
458 if (cp->key.key.high == hi &&
459 cp->key.key.low == key->key.low &&
460 cp->rname != NULL &&
461 memcmp (cp->rname, name, strlen (name) + 1) == 0)
462 {
463 if (BEFORE (timestamp, &cp->laststamp))
464 {
465 ++svcauthdes_stats.ncachereplays;
466 return -1; /* replay */
467 }
468 ++svcauthdes_stats.ncachehits;
469 return i; /* refresh */
470 }
471 }
472 ++svcauthdes_stats.ncachemisses;
473 return cache_victim (); /* new credential */
474 }
475
476 /*
477 * Local credential handling stuff.
478 * NOTE: bsd unix dependent.
479 * Other operating systems should put something else here.
480 */
481 #define UNKNOWN -2 /* grouplen, if cached cred is unknown user */
482 #define INVALID -1 /* grouplen, if cache entry is invalid */
483
484 struct bsdcred
485 {
486 uid_t uid; /* cached uid */
487 gid_t gid; /* cached gid */
488 int grouplen; /* length of cached groups */
489 int grouplen_max; /* length of allocated cached groups */
490 gid_t groups[0]; /* cached groups */
491 };
492
493 /*
494 * Map a des credential into a unix cred.
495 * We cache the credential here so the application does
496 * not have to make an rpc call every time to interpret
497 * the credential.
498 */
499 int
500 authdes_getucred (const struct authdes_cred *adc, uid_t * uid, gid_t * gid,
501 short *grouplen, gid_t * groups)
502 {
503 unsigned sid;
504 register int i;
505 uid_t i_uid;
506 gid_t i_gid;
507 int i_grouplen;
508 struct bsdcred *cred;
509
510 sid = adc->adc_nickname;
511 if (sid >= AUTHDES_CACHESZ)
512 {
513 debug ("invalid nickname");
514 return 0;
515 }
516 cred = (struct bsdcred *) authdes_cache[sid].localcred;
517 if (cred == NULL || cred->grouplen == INVALID)
518 {
519 /*
520 * not in cache: lookup
521 */
522 if (!netname2user (adc->adc_fullname.name, &i_uid, &i_gid,
523 &i_grouplen, groups))
524 {
525 debug ("unknown netname");
526 if (cred != NULL)
527 cred->grouplen = UNKNOWN; /* mark as lookup up, but not found */
528 return 0;
529 }
530
531 if (cred != NULL && cred->grouplen_max < i_grouplen)
532 {
533 /* We already have an allocated data structure. But it is
534 too small. */
535 free (cred);
536 authdes_cache[sid].localcred = NULL;
537 cred = NULL;
538 }
539
540 if (cred == NULL)
541 {
542 /* We should allocate room for at least NGROUPS groups. */
543 int ngroups_max = MAX (i_grouplen, NGROUPS);
544
545 cred = (struct bsdcred *) mem_alloc (sizeof (struct bsdcred)
546 + ngroups_max * sizeof (gid_t));
547 if (cred == NULL)
548 return 0;
549
550 authdes_cache[sid].localcred = (char *) cred;
551 cred->grouplen = INVALID;
552 cred->grouplen_max = ngroups_max;
553 }
554
555 debug ("missed ucred cache");
556 *uid = cred->uid = i_uid;
557 *gid = cred->gid = i_gid;
558 cred->grouplen = i_grouplen;
559 for (i = i_grouplen - 1; i >= 0; --i)
560 cred->groups[i] = groups[i];
561 /* Make sure no too large values are reported. */
562 *grouplen = MIN (SHRT_MAX, i_grouplen);
563 return 1;
564 }
565 else if (cred->grouplen == UNKNOWN)
566 {
567 /*
568 * Already lookup up, but no match found
569 */
570 return 0;
571 }
572
573 /*
574 * cached credentials
575 */
576 *uid = cred->uid;
577 *gid = cred->gid;
578
579 /* Another stupidity in the interface: *grouplen is of type short.
580 So we might have to cut the information passed up short. */
581 int grouplen_copy = MIN (SHRT_MAX, cred->grouplen);
582 *grouplen = grouplen_copy;
583 for (i = grouplen_copy - 1; i >= 0; --i)
584 groups[i] = cred->groups[i];
585 return 1;
586 }
587 libc_hidden_nolink_sunrpc (authdes_getucred, GLIBC_2_1)
588
589 static void
590 invalidate (char *cred)
591 {
592 if (cred == NULL)
593 return;
594 ((struct bsdcred *) cred)->grouplen = INVALID;
595 }