sunrpc/svcauth_des.c

   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 USEC_PER_SEC ((uint32_t) 1000000L)
  62 #define BEFORE(t1, t2) timercmp(t1, t2, <)
  63
  64 /*
  65  * LRU cache of conversation keys and some other useful items.
  66  */
  67 #define AUTHDES_CACHESZ 64
  68 struct cache_entry
  69   {
  70     des_block key;              /* conversation key */
  71     char *rname;                /* client's name */
  72     u_int window;               /* credential lifetime window */
  73     struct rpc_timeval laststamp;       /* detect replays of creds */
  74     char *localcred;            /* generic local credential */
  75   };
  76 #define authdes_cache RPC_THREAD_VARIABLE(authdes_cache_s)
  77 #define authdes_lru RPC_THREAD_VARIABLE(authdes_lru_s)
  78
  79 static void cache_init (void); /* initialize the cache */
  80 static short cache_spot (des_block *, char *, struct rpc_timeval *);
  81   /* find an entry in the cache */
  82 static void cache_ref (uint32_t sid); /* note that sid was ref'd */
  83
  84 static void invalidate (char *cred); /* invalidate entry in cache */
  85
  86 /* Cache statistics.  Accidental historic export without a matching
  87    declaration in any header file.  */
  88 #ifndef SHARED
  89 static
  90 #endif
  91 struct
  92   {
  93     u_long ncachehits;          /* times cache hit, and is not replay */
  94     u_long ncachereplays;       /* times cache hit, and is replay */
  95     u_long ncachemisses;        /* times cache missed */
  96   }
  97 svcauthdes_stats __attribute__ ((nocommon));
  98 #ifdef SHARED
  99 compat_symbol (libc, svcauthdes_stats, svcauthdes_stats, GLIBC_2_0);
 100 #endif
 101
 102 /*
 103  * Service side authenticator for AUTH_DES
 104  */
 105 enum auth_stat
 106 _svcauth_des (register struct svc_req *rqst, register struct rpc_msg *msg)
 107 {
 108   register uint32_t *ixdr;
 109   des_block cryptbuf[2];
 110   register struct authdes_cred *cred;
 111   struct authdes_verf verf;
 112   int status;
 113   register struct cache_entry *entry;
 114   uint32_t sid = 0;
 115   des_block *sessionkey;
 116   des_block ivec;
 117   u_int window;
 118   struct rpc_timeval timestamp;
 119   uint32_t namelen;
 120   struct area
 121     {
 122       struct authdes_cred area_cred;
 123       char area_netname[MAXNETNAMELEN + 1];
 124     }
 125    *area;
 126
 127   if (authdes_cache == NULL)
 128     cache_init ();
 129   if (authdes_cache == NULL) /* No free memory */
 130     return AUTH_FAILED;
 131
 132   area = (struct area *) rqst->rq_clntcred;
 133   cred = (struct authdes_cred *) &area->area_cred;
 134
 135   /*
 136    * Get the credential
 137    */
 138   if (msg->rm_call.cb_cred.oa_length <= 0 ||
 139       msg->rm_call.cb_cred.oa_length > MAX_AUTH_BYTES)
 140     return AUTH_BADCRED;
 141
 142   ixdr = (uint32_t *) msg->rm_call.cb_cred.oa_base;
 143   cred->adc_namekind = IXDR_GET_ENUM (ixdr, enum authdes_namekind);
 144   switch (cred->adc_namekind)
 145     {
 146     case ADN_FULLNAME:
 147       namelen = IXDR_GET_U_INT32 (ixdr);
 148       if (namelen > MAXNETNAMELEN)
 149         {
 150           return AUTH_BADCRED;
 151         }
 152       cred->adc_fullname.name = area->area_netname;
 153       memcpy (cred->adc_fullname.name, (char *) ixdr, namelen);
 154       cred->adc_fullname.name[namelen] = 0;
 155       ixdr += (RNDUP (namelen) / BYTES_PER_XDR_UNIT);
 156       cred->adc_fullname.key.key.high = *ixdr++;
 157       cred->adc_fullname.key.key.low = *ixdr++;
 158       cred->adc_fullname.window = *ixdr++;
 159       break;
 160     case ADN_NICKNAME:
 161       cred->adc_nickname = *ixdr++;
 162       break;
 163     default:
 164       return AUTH_BADCRED;
 165     }
 166
 167   /*
 168    * Get the verifier
 169    */
 170   if (msg->rm_call.cb_verf.oa_length <= 0 ||
 171       msg->rm_call.cb_verf.oa_length > MAX_AUTH_BYTES)
 172     return AUTH_BADCRED;
 173
 174   ixdr = (uint32_t *) msg->rm_call.cb_verf.oa_base;
 175   verf.adv_xtimestamp.key.high = *ixdr++;
 176   verf.adv_xtimestamp.key.low = *ixdr++;
 177   verf.adv_int_u = *ixdr++;
 178
 179   /*
 180    * Get the conversation key
 181    */
 182   if (cred->adc_namekind == ADN_FULLNAME)
 183     {
 184       netobj pkey;
 185       char pkey_data[1024];
 186
 187       sessionkey = &cred->adc_fullname.key;
 188       if (!getpublickey (cred->adc_fullname.name, pkey_data))
 189         {
 190           debug("getpublickey");
 191           return AUTH_BADCRED;
 192         }
 193       pkey.n_bytes = pkey_data;
 194       pkey.n_len = strlen (pkey_data) + 1;
 195       if (key_decryptsession_pk (cred->adc_fullname.name, &pkey,
 196                                  sessionkey) < 0)
 197         {
 198           debug ("decryptsessionkey");
 199           return AUTH_BADCRED;  /* key not found */
 200         }
 201     }
 202   else
 203     {                           /* ADN_NICKNAME */
 204       if (cred->adc_nickname >= AUTHDES_CACHESZ)
 205         {
 206           debug ("bad nickname");
 207           return AUTH_BADCRED;  /* garbled credential */
 208         }
 209       else
 210         sid = cred->adc_nickname;
 211
 212       /* XXX This could be wrong, but else we have a
 213          security problem */
 214       if (authdes_cache[sid].rname == NULL)
 215         return AUTH_BADCRED;
 216       sessionkey = &authdes_cache[sid].key;
 217     }
 218
 219
 220   /*
 221    * Decrypt the timestamp
 222    */
 223   cryptbuf[0] = verf.adv_xtimestamp;
 224   if (cred->adc_namekind == ADN_FULLNAME)
 225     {
 226       cryptbuf[1].key.high = cred->adc_fullname.window;
 227       cryptbuf[1].key.low = verf.adv_winverf;
 228       ivec.key.high = ivec.key.low = 0;
 229       status = cbc_crypt ((char *) sessionkey, (char *) cryptbuf,
 230                           2 * sizeof (des_block), DES_DECRYPT | DES_HW,
 231                           (char *) &ivec);
 232     }
 233   else
 234     status = ecb_crypt ((char *) sessionkey, (char *) cryptbuf,
 235                         sizeof (des_block), DES_DECRYPT | DES_HW);
 236
 237   if (DES_FAILED (status))
 238     {
 239       debug ("decryption failure");
 240       return AUTH_FAILED;       /* system error */
 241     }
 242
 243   /*
 244    * XDR the decrypted timestamp
 245    */
 246   ixdr = (uint32_t *) cryptbuf;
 247   timestamp.tv_sec = IXDR_GET_INT32 (ixdr);
 248   timestamp.tv_usec = IXDR_GET_INT32 (ixdr);
 249
 250   /*
 251    * Check for valid credentials and verifiers.
 252    * They could be invalid because the key was flushed
 253    * out of the cache, and so a new session should begin.
 254    * Be sure and send AUTH_REJECTED{CRED, VERF} if this is the case.
 255    */
 256   {
 257     struct timeval current;
 258     int nick;
 259     u_int winverf;
 260
 261     if (cred->adc_namekind == ADN_FULLNAME)
 262       {
 263         short tmp_spot;
 264
 265         window = IXDR_GET_U_INT32 (ixdr);
 266         winverf = IXDR_GET_U_INT32 (ixdr);
 267         if (winverf != window - 1)
 268           {
 269             debug ("window verifier mismatch");
 270             return AUTH_BADCRED;        /* garbled credential */
 271           }
 272         tmp_spot = cache_spot (sessionkey, cred->adc_fullname.name,
 273                                &timestamp);
 274         if (tmp_spot < 0 || tmp_spot > AUTHDES_CACHESZ)
 275           {
 276             debug ("replayed credential");
 277             return AUTH_REJECTEDCRED;           /* replay */
 278           }
 279         sid = tmp_spot;
 280         nick = 0;
 281       }
 282     else
 283       {                         /* ADN_NICKNAME */
 284         window = authdes_cache[sid].window;
 285         nick = 1;
 286       }
 287
 288     if (timestamp.tv_usec >= USEC_PER_SEC)
 289       {
 290         debug ("invalid usecs");
 291         /* cached out (bad key), or garbled verifier */
 292         return nick ? AUTH_REJECTEDVERF : AUTH_BADVERF;
 293       }
 294     if (nick && BEFORE (&timestamp, &authdes_cache[sid].laststamp))
 295       {
 296         debug ("timestamp before last seen");
 297         return AUTH_REJECTEDVERF;       /* replay */
 298       }
 299     {
 300       struct timespec now;
 301       __clock_gettime (CLOCK_REALTIME, &now);
 302       TIMESPEC_TO_TIMEVAL (&current, &now);
 303     }
 304     current.tv_sec -= window;   /* allow for expiration */
 305     if (!BEFORE (&current, &timestamp))
 306       {
 307         debug ("timestamp expired");
 308         /* replay, or garbled credential */
 309         return nick ? AUTH_REJECTEDVERF : AUTH_BADCRED;
 310       }
 311   }
 312
 313   /*
 314    * Set up the reply verifier
 315    */
 316   verf.adv_nickname = sid;
 317
 318   /*
 319    * xdr the timestamp before encrypting
 320    */
 321   ixdr = (uint32_t *) cryptbuf;
 322   IXDR_PUT_INT32 (ixdr, timestamp.tv_sec - 1);
 323   IXDR_PUT_INT32 (ixdr, timestamp.tv_usec);
 324
 325   /*
 326    * encrypt the timestamp
 327    */
 328   status = ecb_crypt ((char *) sessionkey, (char *) cryptbuf,
 329                       sizeof (des_block), DES_ENCRYPT | DES_HW);
 330   if (DES_FAILED (status))
 331     {
 332       debug ("encryption failure");
 333       return AUTH_FAILED;       /* system error */
 334     }
 335   verf.adv_xtimestamp = cryptbuf[0];
 336
 337   /*
 338    * Serialize the reply verifier, and update rqst
 339    */
 340   ixdr = (uint32_t *) msg->rm_call.cb_verf.oa_base;
 341   *ixdr++ = verf.adv_xtimestamp.key.high;
 342   *ixdr++ = verf.adv_xtimestamp.key.low;
 343   *ixdr++ = verf.adv_int_u;
 344
 345   rqst->rq_xprt->xp_verf.oa_flavor = AUTH_DES;
 346   rqst->rq_xprt->xp_verf.oa_base = msg->rm_call.cb_verf.oa_base;
 347   rqst->rq_xprt->xp_verf.oa_length =
 348     (char *) ixdr - msg->rm_call.cb_verf.oa_base;
 349
 350   /*
 351    * We succeeded, commit the data to the cache now and
 352    * finish cooking the credential.
 353    */
 354   entry = &authdes_cache[sid];
 355   entry->laststamp = timestamp;
 356   cache_ref (sid);
 357   if (cred->adc_namekind == ADN_FULLNAME)
 358     {
 359       size_t full_len;
 360
 361       cred->adc_fullname.window = window;
 362       cred->adc_nickname = sid; /* save nickname */
 363       if (entry->rname != NULL)
 364         mem_free (entry->rname, strlen (entry->rname) + 1);
 365       full_len = strlen (cred->adc_fullname.name) + 1;
 366       entry->rname = mem_alloc ((u_int) full_len);
 367       if (entry->rname != NULL)
 368         memcpy (entry->rname, cred->adc_fullname.name, full_len);
 369       else
 370         {
 371           debug ("out of memory");
 372           return AUTH_FAILED; /* out of memory is bad */
 373         }
 374       entry->key = *sessionkey;
 375       entry->window = window;
 376       invalidate (entry->localcred);    /* mark any cached cred invalid */
 377     }
 378   else
 379     {                           /* ADN_NICKNAME */
 380       /*
 381        * nicknames are cooked into fullnames
 382        */
 383       cred->adc_namekind = ADN_FULLNAME;
 384       cred->adc_fullname.name = entry->rname;
 385       cred->adc_fullname.key = entry->key;
 386       cred->adc_fullname.window = entry->window;
 387     }
 388   return AUTH_OK;               /* we made it! */
 389 }
 390
 391
 392 /*
 393  * Initialize the cache
 394  */
 395 static void
 396 cache_init (void)
 397 {
 398   register int i;
 399
 400   authdes_cache = (struct cache_entry *)
 401     calloc (sizeof (struct cache_entry) * AUTHDES_CACHESZ, 1);
 402   if (authdes_cache == NULL)
 403     return;
 404
 405   authdes_lru = (int *) mem_alloc (sizeof (int) * AUTHDES_CACHESZ);
 406   /*
 407    * Initialize the lru list
 408    */
 409   for (i = 0; i < AUTHDES_CACHESZ; ++i)
 410     authdes_lru[i] = i;
 411 }
 412
 413
 414 /*
 415  * Find the lru victim
 416  */
 417 static short
 418 cache_victim (void)
 419 {
 420   return authdes_lru[AUTHDES_CACHESZ - 1];
 421 }
 422
 423 /*
 424  * Note that sid was referenced
 425  */
 426 static void
 427 cache_ref (register uint32_t sid)
 428 {
 429   register int i;
 430   register int curr;
 431   register int prev;
 432
 433   prev = authdes_lru[0];
 434   authdes_lru[0] = sid;
 435   for (i = 1; prev != sid; ++i)
 436     {
 437       curr = authdes_lru[i];
 438       authdes_lru[i] = prev;
 439       prev = curr;
 440     }
 441 }
 442
 443 /*
 444  * Find a spot in the cache for a credential containing
 445  * the items given.  Return -1 if a replay is detected, otherwise
 446  * return the spot in the cache.
 447  */
 448 static short
 449 cache_spot (register des_block *key, char *name,
 450             struct rpc_timeval *timestamp)
 451 {
 452   register struct cache_entry *cp;
 453   register int i;
 454   register uint32_t hi;
 455
 456   hi = key->key.high;
 457   for (cp = authdes_cache, i = 0; i < AUTHDES_CACHESZ; ++i, ++cp)
 458     {
 459       if (cp->key.key.high == hi &&
 460           cp->key.key.low == key->key.low &&
 461           cp->rname != NULL &&
 462           memcmp (cp->rname, name, strlen (name) + 1) == 0)
 463         {
 464           if (BEFORE (timestamp, &cp->laststamp))
 465             {
 466               ++svcauthdes_stats.ncachereplays;
 467               return -1;        /* replay */
 468             }
 469           ++svcauthdes_stats.ncachehits;
 470           return i;             /* refresh */
 471         }
 472     }
 473   ++svcauthdes_stats.ncachemisses;
 474   return cache_victim ();       /* new credential */
 475 }
 476
 477 /*
 478  * Local credential handling stuff.
 479  * NOTE: bsd unix dependent.
 480  * Other operating systems should put something else here.
 481  */
 482 #define UNKNOWN         -2      /* grouplen, if cached cred is unknown user */
 483 #define INVALID         -1      /* grouplen, if cache entry is invalid */
 484
 485 struct bsdcred
 486 {
 487   uid_t uid;                    /* cached uid */
 488   gid_t gid;                    /* cached gid */
 489   int grouplen;                 /* length of cached groups */
 490   int grouplen_max;             /* length of allocated cached groups */
 491   gid_t groups[0];              /* cached groups */
 492 };
 493
 494 /*
 495  * Map a des credential into a unix cred.
 496  * We cache the credential here so the application does
 497  * not have to make an rpc call every time to interpret
 498  * the credential.
 499  */
 500 int
 501 authdes_getucred (const struct authdes_cred *adc, uid_t * uid, gid_t * gid,
 502                   short *grouplen, gid_t * groups)
 503 {
 504   unsigned sid;
 505   register int i;
 506   uid_t i_uid;
 507   gid_t i_gid;
 508   int i_grouplen;
 509   struct bsdcred *cred;
 510
 511   sid = adc->adc_nickname;
 512   if (sid >= AUTHDES_CACHESZ)
 513     {
 514       debug ("invalid nickname");
 515       return 0;
 516     }
 517   cred = (struct bsdcred *) authdes_cache[sid].localcred;
 518   if (cred == NULL || cred->grouplen == INVALID)
 519     {
 520       /*
 521        * not in cache: lookup
 522        */
 523       if (!netname2user (adc->adc_fullname.name, &i_uid, &i_gid,
 524                          &i_grouplen, groups))
 525         {
 526           debug ("unknown netname");
 527           if (cred != NULL)
 528             cred->grouplen = UNKNOWN;   /* mark as lookup up, but not found */
 529           return 0;
 530         }
 531
 532       if (cred != NULL && cred->grouplen_max < i_grouplen)
 533         {
 534           /* We already have an allocated data structure.  But it is
 535              too small.  */
 536           free (cred);
 537           authdes_cache[sid].localcred = NULL;
 538           cred = NULL;
 539         }
 540
 541       if (cred == NULL)
 542         {
 543           /* We should allocate room for at least NGROUPS groups.  */
 544           int ngroups_max = MAX (i_grouplen, NGROUPS);
 545
 546           cred = (struct bsdcred *) mem_alloc (sizeof (struct bsdcred)
 547                                                + ngroups_max * sizeof (gid_t));
 548           if (cred == NULL)
 549             return 0;
 550
 551           authdes_cache[sid].localcred = (char *) cred;
 552           cred->grouplen = INVALID;
 553           cred->grouplen_max = ngroups_max;
 554         }
 555
 556       debug ("missed ucred cache");
 557       *uid = cred->uid = i_uid;
 558       *gid = cred->gid = i_gid;
 559       cred->grouplen = i_grouplen;
 560       for (i = i_grouplen - 1; i >= 0; --i)
 561         cred->groups[i] = groups[i];
 562       /* Make sure no too large values are reported.  */
 563       *grouplen = MIN (SHRT_MAX, i_grouplen);
 564       return 1;
 565     }
 566   else if (cred->grouplen == UNKNOWN)
 567     {
 568       /*
 569        * Already lookup up, but no match found
 570        */
 571       return 0;
 572     }
 573
 574   /*
 575    * cached credentials
 576    */
 577   *uid = cred->uid;
 578   *gid = cred->gid;
 579
 580   /* Another stupidity in the interface: *grouplen is of type short.
 581      So we might have to cut the information passed up short.  */
 582   int grouplen_copy = MIN (SHRT_MAX, cred->grouplen);
 583   *grouplen = grouplen_copy;
 584   for (i = grouplen_copy - 1; i >= 0; --i)
 585     groups[i] = cred->groups[i];
 586   return 1;
 587 }
 588 libc_hidden_nolink_sunrpc (authdes_getucred, GLIBC_2_1)
 589
 590 static void
 591 invalidate (char *cred)
 592 {
 593   if (cred == NULL)
 594     return;
 595   ((struct bsdcred *) cred)->grouplen = INVALID;
 596 }