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 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 __attribute__ ((nocommon));
  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                                &timestamp);
 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 (&timestamp, &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 (&current, &now);
 302     }
 303     current.tv_sec -= window;   /* allow for expiration */
 304     if (!BEFORE (&current, &timestamp))
 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 }