sunrpc/svcauth_des.c

   1 #if defined(LIBC_SCCS) && !defined(lint)
   2 static char sccsid[] = "@(#)svcauth_des.c       2.3 89/07/11 4.0 RPCSRC; from 1.15 88/02/08 SMI";
   3 #endif
   4
   5 /*
   6  * Copyright (c) 1988 by Sun Microsystems, Inc.
   7  */
   8
   9 /*
  10  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
  11  * unrestricted use provided that this legend is included on all tape
  12  * media and as a part of the software program in whole or part.  Users
  13  * may copy or modify Sun RPC without charge, but are not authorized
  14  * to license or distribute it to anyone else except as part of a product or
  15  * program developed by the user.
  16  *
  17  * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
  18  * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
  19  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
  20  *
  21  * Sun RPC is provided with no support and without any obligation on the
  22  * part of Sun Microsystems, Inc. to assist in its use, correction,
  23  * modification or enhancement.
  24  *
  25  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
  26  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
  27  * OR ANY PART THEREOF.
  28  *
  29  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
  30  * or profits or other special, indirect and consequential damages, even if
  31  * Sun has been advised of the possibility of such damages.
  32  *
  33  * Sun Microsystems, Inc.
  34  * 2550 Garcia Avenue
  35  * Mountain View, California  94043
  36  */
  37
  38 /*
  39  * svcauth_des.c, server-side des authentication
  40  *
  41  * We insure for the service the following:
  42  * (1) The timestamp microseconds do not exceed 1 million.
  43  * (2) The timestamp plus the window is less than the current time.
  44  * (3) The timestamp is not less than the one previously
  45  *     seen in the current session.
  46  *
  47  * It is up to the server to determine if the window size is
  48  * too small .
  49  *
  50  */
  51
  52 #include <string.h>
  53 #include <sys/param.h>
  54 #include <netinet/in.h>
  55 #include <rpc/types.h>
  56 #include <rpc/xdr.h>
  57 #include <rpc/auth.h>
  58 #include <rpc/auth_des.h>
  59 #include <rpc/svc_auth.h>
  60 #include <rpc/svc.h>
  61 #include <rpc/des_crypt.h>
  62
  63 #define debug(msg)              /*printf("svcauth_des: %s\n", msg) */
  64
  65 #define USEC_PER_SEC ((u_long) 1000000L)
  66 #define BEFORE(t1, t2) timercmp(t1, t2, <)
  67
  68 /*
  69  * LRU cache of conversation keys and some other useful items.
  70  */
  71 #define AUTHDES_CACHESZ 64
  72 struct cache_entry
  73   {
  74     des_block key;              /* conversation key */
  75     char *rname;                /* client's name */
  76     u_int window;               /* credential lifetime window */
  77     struct timeval laststamp;   /* detect replays of creds */
  78     char *localcred;            /* generic local credential */
  79   };
  80 static struct cache_entry *authdes_cache /* [AUTHDES_CACHESZ] */ ;
  81 static short *authdes_lru /* [AUTHDES_CACHESZ] */ ;
  82
  83 static void cache_init (void) internal_function; /* initialize the cache */
  84 static short cache_spot (des_block *, char *, struct timeval *)
  85      internal_function;         /* find an entry in the cache */
  86 static void cache_ref (short sid) internal_function;
  87                                 /* note that sid was ref'd */
  88
  89 static void invalidate (char *cred) internal_function;
  90                                 /* invalidate entry in cache */
  91
  92 /*
  93  * cache statistics
  94  */
  95 struct
  96   {
  97     u_long ncachehits;          /* times cache hit, and is not replay */
  98     u_long ncachereplays;       /* times cache hit, and is replay */
  99     u_long ncachemisses;        /* times cache missed */
 100   }
 101 svcauthdes_stats;
 102
 103 /*
 104  * Service side authenticator for AUTH_DES
 105  */
 106 enum auth_stat
 107 _svcauth_des (register struct svc_req *rqst, register struct rpc_msg *msg)
 108 {
 109   register long *ixdr;
 110   des_block cryptbuf[2];
 111   register struct authdes_cred *cred;
 112   struct authdes_verf verf;
 113   int status;
 114   register struct cache_entry *entry;
 115   short sid = 0;
 116   des_block *sessionkey;
 117   des_block ivec;
 118   u_int window;
 119   struct timeval timestamp;
 120   u_long namelen;
 121   struct area
 122     {
 123       struct authdes_cred area_cred;
 124       char area_netname[MAXNETNAMELEN + 1];
 125     }
 126    *area;
 127
 128   if (authdes_cache == NULL)
 129     cache_init ();
 130
 131   area = (struct area *) rqst->rq_clntcred;
 132   cred = (struct authdes_cred *) &area->area_cred;
 133
 134   /*
 135    * Get the credential
 136    */
 137   ixdr = (long *) msg->rm_call.cb_cred.oa_base;
 138   cred->adc_namekind = IXDR_GET_ENUM (ixdr, enum authdes_namekind);
 139   switch (cred->adc_namekind)
 140     {
 141     case ADN_FULLNAME:
 142       namelen = IXDR_GET_U_LONG (ixdr);
 143       if (namelen > MAXNETNAMELEN)
 144         {
 145           return AUTH_BADCRED;
 146         }
 147       cred->adc_fullname.name = area->area_netname;
 148       bcopy ((char *) ixdr, cred->adc_fullname.name,
 149              (u_int) namelen);
 150       cred->adc_fullname.name[namelen] = 0;
 151       ixdr += (RNDUP (namelen) / BYTES_PER_XDR_UNIT);
 152       cred->adc_fullname.key.key.high = (u_long) * ixdr++;
 153       cred->adc_fullname.key.key.low = (u_long) * ixdr++;
 154       cred->adc_fullname.window = (u_long) * ixdr++;
 155       break;
 156     case ADN_NICKNAME:
 157       cred->adc_nickname = (u_long) * ixdr++;
 158       break;
 159     default:
 160       return AUTH_BADCRED;
 161     }
 162
 163   /*
 164    * Get the verifier
 165    */
 166   ixdr = (long *) msg->rm_call.cb_verf.oa_base;
 167   verf.adv_xtimestamp.key.high = (u_long) * ixdr++;
 168   verf.adv_xtimestamp.key.low = (u_long) * ixdr++;
 169   verf.adv_int_u = (u_long) * ixdr++;
 170
 171
 172   /*
 173    * Get the conversation key
 174    */
 175   if (cred->adc_namekind == ADN_FULLNAME)
 176     {
 177       sessionkey = &cred->adc_fullname.key;
 178       if (key_decryptsession (cred->adc_fullname.name,
 179                               sessionkey) < 0)
 180         {
 181           debug ("decryptsessionkey");
 182           return AUTH_BADCRED;  /* key not found */
 183         }
 184     }
 185   else
 186     {                           /* ADN_NICKNAME */
 187       sid = (short) cred->adc_nickname;
 188       if (sid >= AUTHDES_CACHESZ)
 189         {
 190           debug ("bad nickname");
 191           return AUTH_BADCRED;  /* garbled credential */
 192         }
 193       sessionkey = &authdes_cache[sid].key;
 194     }
 195
 196
 197   /*
 198    * Decrypt the timestamp
 199    */
 200   cryptbuf[0] = verf.adv_xtimestamp;
 201   if (cred->adc_namekind == ADN_FULLNAME)
 202     {
 203       cryptbuf[1].key.high = cred->adc_fullname.window;
 204       cryptbuf[1].key.low = verf.adv_winverf;
 205       ivec.key.high = ivec.key.low = 0;
 206       status = cbc_crypt ((char *) sessionkey, (char *) cryptbuf,
 207                           2 * sizeof (des_block), DES_DECRYPT | DES_HW,
 208                           (char *) &ivec);
 209     }
 210   else
 211     {
 212       status = ecb_crypt ((char *) sessionkey, (char *) cryptbuf,
 213                           sizeof (des_block), DES_DECRYPT | DES_HW);
 214     }
 215   if (DES_FAILED (status))
 216     {
 217       debug ("decryption failure");
 218       return AUTH_FAILED;       /* system error */
 219     }
 220
 221   /*
 222    * XDR the decrypted timestamp
 223    */
 224   ixdr = (long *) cryptbuf;
 225   timestamp.tv_sec = IXDR_GET_LONG (ixdr);
 226   timestamp.tv_usec = IXDR_GET_LONG (ixdr);
 227
 228   /*
 229    * Check for valid credentials and verifiers.
 230    * They could be invalid because the key was flushed
 231    * out of the cache, and so a new session should begin.
 232    * Be sure and send AUTH_REJECTED{CRED, VERF} if this is the case.
 233    */
 234   {
 235     struct timeval current;
 236     int nick;
 237     u_int winverf;
 238
 239     if (cred->adc_namekind == ADN_FULLNAME)
 240       {
 241         window = IXDR_GET_U_LONG (ixdr);
 242         winverf = IXDR_GET_U_LONG (ixdr);
 243         if (winverf != window - 1)
 244           {
 245             debug ("window verifier mismatch");
 246             return AUTH_BADCRED;        /* garbled credential */
 247           }
 248         sid = cache_spot (sessionkey, cred->adc_fullname.name,
 249                           &timestamp);
 250         if (sid < 0)
 251           {
 252             debug ("replayed credential");
 253             return AUTH_REJECTEDCRED;           /* replay */
 254           }
 255         nick = 0;
 256       }
 257     else
 258       {                         /* ADN_NICKNAME */
 259         window = authdes_cache[sid].window;
 260         nick = 1;
 261       }
 262
 263     if ((u_long) timestamp.tv_usec >= USEC_PER_SEC)
 264       {
 265         debug ("invalid usecs");
 266         /* cached out (bad key), or garbled verifier */
 267         return nick ? AUTH_REJECTEDVERF : AUTH_BADVERF;
 268       }
 269     if (nick && BEFORE (&timestamp,
 270                         &authdes_cache[sid].laststamp))
 271       {
 272         debug ("timestamp before last seen");
 273         return (AUTH_REJECTEDVERF);     /* replay */
 274       }
 275     gettimeofday (&current, (struct timezone *) NULL);
 276     current.tv_sec -= window;   /* allow for expiration */
 277     if (!BEFORE (&current, &timestamp))
 278       {
 279         debug ("timestamp expired");
 280         /* replay, or garbled credential */
 281         return nick ? AUTH_REJECTEDVERF : AUTH_BADCRED;
 282       }
 283   }
 284
 285   /*
 286    * Set up the reply verifier
 287    */
 288   verf.adv_nickname = (u_long) sid;
 289
 290   /*
 291    * xdr the timestamp before encrypting
 292    */
 293   ixdr = (long *) cryptbuf;
 294   IXDR_PUT_LONG (ixdr, timestamp.tv_sec - 1);
 295   IXDR_PUT_LONG (ixdr, timestamp.tv_usec);
 296
 297   /*
 298    * encrypt the timestamp
 299    */
 300   status = ecb_crypt ((char *) sessionkey, (char *) cryptbuf,
 301                       sizeof (des_block), DES_ENCRYPT | DES_HW);
 302   if (DES_FAILED (status))
 303     {
 304       debug ("encryption failure");
 305       return AUTH_FAILED;       /* system error */
 306     }
 307   verf.adv_xtimestamp = cryptbuf[0];
 308
 309   /*
 310    * Serialize the reply verifier, and update rqst
 311    */
 312   ixdr = (long *) msg->rm_call.cb_verf.oa_base;
 313   *ixdr++ = (long) verf.adv_xtimestamp.key.high;
 314   *ixdr++ = (long) verf.adv_xtimestamp.key.low;
 315   *ixdr++ = (long) verf.adv_int_u;
 316
 317   rqst->rq_xprt->xp_verf.oa_flavor = AUTH_DES;
 318   rqst->rq_xprt->xp_verf.oa_base = msg->rm_call.cb_verf.oa_base;
 319   rqst->rq_xprt->xp_verf.oa_length =
 320     (char *) ixdr - msg->rm_call.cb_verf.oa_base;
 321
 322   /*
 323    * We succeeded, commit the data to the cache now and
 324    * finish cooking the credential.
 325    */
 326   entry = &authdes_cache[sid];
 327   entry->laststamp = timestamp;
 328   cache_ref (sid);
 329   if (cred->adc_namekind == ADN_FULLNAME)
 330     {
 331       cred->adc_fullname.window = window;
 332       cred->adc_nickname = (u_long) sid;        /* save nickname */
 333       if (entry->rname != NULL)
 334         {
 335           mem_free (entry->rname, strlen (entry->rname) + 1);
 336         }
 337       entry->rname = mem_alloc ((u_int) strlen (cred->adc_fullname.name)
 338                                 + 1);
 339       if (entry->rname != NULL)
 340         {
 341           strcpy (entry->rname, cred->adc_fullname.name);
 342         }
 343       else
 344         {
 345           debug ("out of memory");
 346         }
 347       entry->key = *sessionkey;
 348       entry->window = window;
 349       invalidate (entry->localcred);    /* mark any cached cred invalid */
 350     }
 351   else
 352     {                           /* ADN_NICKNAME */
 353       /*
 354        * nicknames are cooked into fullnames
 355        */
 356       cred->adc_namekind = ADN_FULLNAME;
 357       cred->adc_fullname.name = entry->rname;
 358       cred->adc_fullname.key = entry->key;
 359       cred->adc_fullname.window = entry->window;
 360     }
 361   return AUTH_OK;               /* we made it! */
 362 }
 363
 364
 365 /*
 366  * Initialize the cache
 367  */
 368 static void
 369 internal_function
 370 cache_init (void)
 371 {
 372   register int i;
 373
 374   authdes_cache = (struct cache_entry *)
 375     mem_alloc (sizeof (struct cache_entry) * AUTHDES_CACHESZ);
 376   bzero ((char *) authdes_cache,
 377          sizeof (struct cache_entry) * AUTHDES_CACHESZ);
 378
 379   authdes_lru = (short *) mem_alloc (sizeof (short) * AUTHDES_CACHESZ);
 380   /*
 381    * Initialize the lru list
 382    */
 383   for (i = 0; i < AUTHDES_CACHESZ; i++)
 384     {
 385       authdes_lru[i] = i;
 386     }
 387 }
 388
 389
 390 /*
 391  * Find the lru victim
 392  */
 393 static short
 394 cache_victim (void)
 395 {
 396   return (authdes_lru[AUTHDES_CACHESZ - 1]);
 397 }
 398
 399 /*
 400  * Note that sid was referenced
 401  */
 402 static void
 403 internal_function
 404 cache_ref (register short sid)
 405 {
 406   register int i;
 407   register short curr;
 408   register short prev;
 409
 410   prev = authdes_lru[0];
 411   authdes_lru[0] = sid;
 412   for (i = 1; prev != sid; i++)
 413     {
 414       curr = authdes_lru[i];
 415       authdes_lru[i] = prev;
 416       prev = curr;
 417     }
 418 }
 419
 420
 421 /*
 422  * Find a spot in the cache for a credential containing
 423  * the items given.  Return -1 if a replay is detected, otherwise
 424  * return the spot in the cache.
 425  */
 426 static short
 427 internal_function
 428 cache_spot (register des_block * key, char *name, struct timeval *timestamp)
 429 {
 430   register struct cache_entry *cp;
 431   register int i;
 432   register u_long hi;
 433
 434   hi = key->key.high;
 435   for (cp = authdes_cache, i = 0; i < AUTHDES_CACHESZ; i++, cp++)
 436     {
 437       if (cp->key.key.high == hi &&
 438           cp->key.key.low == key->key.low &&
 439           cp->rname != NULL &&
 440           bcmp (cp->rname, name, strlen (name) + 1) == 0)
 441         {
 442           if (BEFORE (timestamp, &cp->laststamp))
 443             {
 444               svcauthdes_stats.ncachereplays++;
 445               return -1;        /* replay */
 446             }
 447           svcauthdes_stats.ncachehits++;
 448           return i;             /* refresh */
 449         }
 450     }
 451   svcauthdes_stats.ncachemisses++;
 452   return cache_victim ();       /* new credential */
 453 }
 454
 455
 456 /*
 457  * Local credential handling stuff.
 458  * NOTE: bsd unix dependent.
 459  * Other operating systems should put something else here.
 460  */
 461 #define UNKNOWN         -2      /* grouplen, if cached cred is unknown user */
 462 #define INVALID         -1      /* grouplen, if cache entry is invalid */
 463
 464 struct bsdcred
 465 {
 466   uid_t uid;                    /* cached uid */
 467   gid_t gid;                    /* cached gid */
 468   short grouplen;               /* length of cached groups */
 469   gid_t groups[NGROUPS];        /* cached groups */
 470 };
 471
 472 /*
 473  * Map a des credential into a unix cred.
 474  * We cache the credential here so the application does
 475  * not have to make an rpc call every time to interpret
 476  * the credential.
 477  */
 478 int
 479 authdes_getucred (const struct authdes_cred *adc, uid_t * uid, gid_t * gid,
 480                   short *grouplen, gid_t * groups)
 481 {
 482   unsigned sid;
 483   register int i;
 484   uid_t i_uid;
 485   gid_t i_gid;
 486   int i_grouplen;
 487   struct bsdcred *cred;
 488
 489   sid = adc->adc_nickname;
 490   if (sid >= AUTHDES_CACHESZ)
 491     {
 492       debug ("invalid nickname");
 493       return 0;
 494     }
 495   cred = (struct bsdcred *) authdes_cache[sid].localcred;
 496   if (cred == NULL)
 497     {
 498       cred = (struct bsdcred *) mem_alloc (sizeof (struct bsdcred));
 499       authdes_cache[sid].localcred = (char *) cred;
 500       cred->grouplen = INVALID;
 501     }
 502   if (cred->grouplen == INVALID)
 503     {
 504       /*
 505        * not in cache: lookup
 506        */
 507       if (!netname2user (adc->adc_fullname.name, &i_uid, &i_gid,
 508                          &i_grouplen, groups))
 509         {
 510           debug ("unknown netname");
 511           cred->grouplen = UNKNOWN;     /* mark as lookup up, but not found */
 512           return 0;
 513         }
 514       debug ("missed ucred cache");
 515       *uid = cred->uid = i_uid;
 516       *gid = cred->gid = i_gid;
 517       *grouplen = cred->grouplen = i_grouplen;
 518       for (i = i_grouplen - 1; i >= 0; i--)
 519         {
 520           cred->groups[i] = groups[i];  /* int to short */
 521         }
 522       return 1;
 523     }
 524   else if (cred->grouplen == UNKNOWN)
 525     {
 526       /*
 527        * Already lookup up, but no match found
 528        */
 529       return 0;
 530     }
 531
 532   /*
 533    * cached credentials
 534    */
 535   *uid = cred->uid;
 536   *gid = cred->gid;
 537   *grouplen = cred->grouplen;
 538   for (i = cred->grouplen - 1; i >= 0; i--)
 539     {
 540       groups[i] = cred->groups[i];      /* short to int */
 541     }
 542   return 1;
 543 }
 544
 545 static void
 546 internal_function
 547 invalidate (char *cred)
 548 {
 549   if (cred == NULL)
 550     {
 551       return;
 552     }
 553   ((struct bsdcred *) cred)->grouplen = INVALID;
 554 }