lib/libc/gen/getnetgrent.c

   1 /*
   2  * Copyright (c) 1992, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Rick Macklem at The University of Guelph.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * @(#)getnetgrent.c    8.2 (Berkeley) 4/27/95
  33  * $FreeBSD: src/lib/libc/gen/getnetgrent.c,v 1.35 2007/01/09 00:27:54 imp Exp $
  34  */
  35
  36 #include <ctype.h>
  37 #include <netdb.h>
  38 #include <stdio.h>
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42
  43 #ifdef YP
  44 /*
  45  * Notes:
  46  * We want to be able to use NIS netgroups properly while retaining
  47  * the ability to use a local /etc/netgroup file. Unfortunately, you
  48  * can't really do both at the same time - at least, not efficiently.
  49  * NetBSD deals with this problem by creating a netgroup database
  50  * using Berkeley DB (just like the password database) that allows
  51  * for lookups using netgroup, netgroup.byuser or netgroup.byhost
  52  * searches. This is a neat idea, but I don't have time to implement
  53  * something like that now. (I think ultimately it would be nice
  54  * if we DB-fied the group and netgroup stuff all in one shot, but
  55  * for now I'm satisfied just to have something that works well
  56  * without requiring massive code changes.)
  57  *
  58  * Therefore, to still permit the use of the local file and maintain
  59  * optimum NIS performance, we allow for the following conditions:
  60  *
  61  * - If /etc/netgroup does not exist and NIS is turned on, we use
  62  *   NIS netgroups only.
  63  *
  64  * - If /etc/netgroup exists but is empty, we use NIS netgroups
  65  *   only.
  66  *
  67  * - If /etc/netgroup exists and contains _only_ a '+', we use
  68  *   NIS netgroups only.
  69  *
  70  * - If /etc/netgroup exists, contains locally defined netgroups
  71  *   and a '+', we use a mixture of NIS and the local entries.
  72  *   This method should return the same NIS data as just using
  73  *   NIS alone, but it will be slower if the NIS netgroup database
  74  *   is large (innetgr() in particular will suffer since extra
  75  *   processing has to be done in order to determine memberships
  76  *   using just the raw netgroup data).
  77  *
  78  * - If /etc/netgroup exists and contains only locally defined
  79  *   netgroup entries, we use just those local entries and ignore
  80  *   NIS (this is the original, pre-NIS behavior).
  81  */
  82
  83 #include <rpc/rpc.h>
  84 #include <rpcsvc/yp_prot.h>
  85 #include <rpcsvc/ypclnt.h>
  86 #include <sys/types.h>
  87 #include <sys/stat.h>
  88 #include <sys/param.h>
  89 #include <sys/errno.h>
  90 static char *_netgr_yp_domain;
  91 int _use_only_yp;
  92 static int _netgr_yp_enabled;
  93 static int _yp_innetgr;
  94 #endif
  95
  96 #ifndef _PATH_NETGROUP
  97 #define _PATH_NETGROUP "/etc/netgroup"
  98 #endif
  99
 100 /*
 101  * Static Variables and functions used by setnetgrent(), getnetgrent() and
 102  * endnetgrent().
 103  * There are two linked lists:
 104  * - linelist is just used by setnetgrent() to parse the net group file via.
 105  *   parse_netgrp()
 106  * - netgrp is the list of entries for the current netgroup
 107  */
 108 struct linelist {
 109         struct linelist *l_next;        /* Chain ptr. */
 110         int             l_parsed;       /* Flag for cycles */
 111         char            *l_groupname;   /* Name of netgroup */
 112         char            *l_line;        /* Netgroup entrie(s) to be parsed */
 113 };
 114
 115 struct netgrp {
 116         struct netgrp   *ng_next;       /* Chain ptr */
 117         char            *ng_str[3];     /* Field pointers, see below */
 118 };
 119 #define NG_HOST         0       /* Host name */
 120 #define NG_USER         1       /* User name */
 121 #define NG_DOM          2       /* and Domain name */
 122
 123 static struct linelist  *linehead = NULL;
 124 static struct netgrp    *nextgrp = NULL;
 125 static struct {
 126         struct netgrp   *gr;
 127         char            *grname;
 128 } grouphead = {
 129         NULL,
 130         NULL,
 131 };
 132 static FILE *netf = NULL;
 133
 134 static int parse_netgrp(const char *);
 135 static struct linelist *read_for_group(const char *);
 136
 137 #define LINSIZ  1024    /* Length of netgroup file line */
 138
 139 /*
 140  * setnetgrent()
 141  * Parse the netgroup file looking for the netgroup and build the list
 142  * of netgrp structures. Let parse_netgrp() and read_for_group() do
 143  * most of the work.
 144  */
 145 void
 146 setnetgrent(const char *group)
 147 {
 148 #ifdef YP
 149         struct stat _yp_statp;
 150         char _yp_plus;
 151 #endif
 152
 153         /* Sanity check */
 154
 155         if (group == NULL || !strlen(group))
 156                 return;
 157
 158         if (grouphead.gr == NULL ||
 159                 strcmp(group, grouphead.grname)) {
 160                 endnetgrent();
 161 #ifdef YP
 162                 /* Presumed guilty until proven innocent. */
 163                 _use_only_yp = 0;
 164                 /*
 165                  * If /etc/netgroup doesn't exist or is empty,
 166                  * use NIS exclusively.
 167                  */
 168                 if (((stat(_PATH_NETGROUP, &_yp_statp) < 0) &&
 169                         errno == ENOENT) || _yp_statp.st_size == 0)
 170                         _use_only_yp = _netgr_yp_enabled = 1;
 171                 if ((netf = fopen(_PATH_NETGROUP,"r")) != NULL ||_use_only_yp){
 172                 /*
 173                  * Icky: grab the first character of the netgroup file
 174                  * and turn on NIS if it's a '+'. rewind the stream
 175                  * afterwards so we don't goof up read_for_group() later.
 176                  */
 177                         if (netf) {
 178                                 fscanf(netf, "%c", &_yp_plus);
 179                                 rewind(netf);
 180                                 if (_yp_plus == '+')
 181                                         _use_only_yp = _netgr_yp_enabled = 1;
 182                         }
 183                 /*
 184                  * If we were called specifically for an innetgr()
 185                  * lookup and we're in NIS-only mode, short-circuit
 186                  * parse_netgroup() and cut directly to the chase.
 187                  */
 188                         if (_use_only_yp && _yp_innetgr) {
 189                                 /* dohw! */
 190                                 if (netf != NULL)
 191                                         fclose(netf);
 192                                 return;
 193                         }
 194 #else
 195                 if ((netf = fopen(_PATH_NETGROUP, "r"))) {
 196 #endif
 197                         if (parse_netgrp(group))
 198                                 endnetgrent();
 199                         else {
 200                                 grouphead.grname = (char *)
 201                                         malloc(strlen(group) + 1);
 202                                 strcpy(grouphead.grname, group);
 203                         }
 204                         if (netf)
 205                                 fclose(netf);
 206                 }
 207         }
 208         nextgrp = grouphead.gr;
 209 }
 210
 211 /*
 212  * Get the next netgroup off the list.
 213  */
 214 int
 215 getnetgrent(char **hostp, char **userp, char **domp)
 216 {
 217 #ifdef YP
 218         _yp_innetgr = 0;
 219 #endif
 220
 221         if (nextgrp) {
 222                 *hostp = nextgrp->ng_str[NG_HOST];
 223                 *userp = nextgrp->ng_str[NG_USER];
 224                 *domp = nextgrp->ng_str[NG_DOM];
 225                 nextgrp = nextgrp->ng_next;
 226                 return (1);
 227         }
 228         return (0);
 229 }
 230
 231 /*
 232  * endnetgrent() - cleanup
 233  */
 234 void
 235 endnetgrent(void)
 236 {
 237         struct linelist *lp, *olp;
 238         struct netgrp *gp, *ogp;
 239
 240         lp = linehead;
 241         while (lp) {
 242                 olp = lp;
 243                 lp = lp->l_next;
 244                 free(olp->l_groupname);
 245                 free(olp->l_line);
 246                 free((char *)olp);
 247         }
 248         linehead = NULL;
 249         if (grouphead.grname) {
 250                 free(grouphead.grname);
 251                 grouphead.grname = NULL;
 252         }
 253         gp = grouphead.gr;
 254         while (gp) {
 255                 ogp = gp;
 256                 gp = gp->ng_next;
 257                 if (ogp->ng_str[NG_HOST])
 258                         free(ogp->ng_str[NG_HOST]);
 259                 if (ogp->ng_str[NG_USER])
 260                         free(ogp->ng_str[NG_USER]);
 261                 if (ogp->ng_str[NG_DOM])
 262                         free(ogp->ng_str[NG_DOM]);
 263                 free((char *)ogp);
 264         }
 265         grouphead.gr = NULL;
 266         nextgrp = NULL;
 267 #ifdef YP
 268         _netgr_yp_enabled = 0;
 269 #endif
 270 }
 271
 272 #ifdef YP
 273 static int
 274 _listmatch(const char *list, const char *group, int len)
 275 {
 276         const char *ptr = list;
 277         const char *cptr;
 278         int glen = strlen(group);
 279
 280         /* skip possible leading whitespace */
 281         while(isspace((unsigned char)*ptr))
 282                 ptr++;
 283
 284         while (ptr < list + len) {
 285                 cptr = ptr;
 286                 while(*ptr != ','  && *ptr != '\0' && !isspace((unsigned char)*ptr))
 287                         ptr++;
 288                 if (strncmp(cptr, group, glen) == 0 && glen == (ptr - cptr))
 289                         return(1);
 290                 while(*ptr == ','  || isspace((unsigned char)*ptr))
 291                         ptr++;
 292         }
 293
 294         return(0);
 295 }
 296
 297 static int
 298 _revnetgr_lookup(char *lookupdom, char *map, const char *str,
 299                  const char *dom, const char *group)
 300 {
 301         int y, rv, rot;
 302         char key[MAXHOSTNAMELEN];
 303         char *result;
 304         int resultlen;
 305
 306         for (rot = 0; ; rot++) {
 307                 switch (rot) {
 308                         case(0): snprintf(key, MAXHOSTNAMELEN, "%s.%s",
 309                                           str, dom?dom:lookupdom);
 310                                  break;
 311                         case(1): snprintf(key, MAXHOSTNAMELEN, "%s.*",
 312                                           str);
 313                                  break;
 314                         case(2): snprintf(key, MAXHOSTNAMELEN, "*.%s",
 315                                           dom?dom:lookupdom);
 316                                  break;
 317                         case(3): snprintf(key, MAXHOSTNAMELEN, "*.*");
 318                                  break;
 319                         default: return(0);
 320                 }
 321                 y = yp_match(lookupdom, map, key, strlen(key), &result,
 322                              &resultlen);
 323                 if (y == 0) {
 324                         rv = _listmatch(result, group, resultlen);
 325                         free(result);
 326                         if (rv) return(1);
 327                 } else if (y != YPERR_KEY) {
 328                         /*
 329                          * If we get an error other than 'no
 330                          * such key in map' then something is
 331                          * wrong and we should stop the search.
 332                          */
 333                         return(-1);
 334                 }
 335         }
 336 }
 337 #endif
 338
 339 /*
 340  * Search for a match in a netgroup.
 341  */
 342 int
 343 innetgr(const char *group, const char *host, const char *user, const char *dom)
 344 {
 345         char *hst, *usr, *dm;
 346         /* Sanity check */
 347
 348         if (group == NULL || !strlen(group))
 349                 return (0);
 350
 351 #ifdef YP
 352         _yp_innetgr = 1;
 353 #endif
 354         setnetgrent(group);
 355 #ifdef YP
 356         _yp_innetgr = 0;
 357         /*
 358          * If we're in NIS-only mode, do the search using
 359          * NIS 'reverse netgroup' lookups.
 360          *
 361          * What happens with 'reverse netgroup' lookups:
 362          *
 363          * 1) try 'reverse netgroup' lookup
 364          *    1.a) if host is specified and user is null:
 365          *         look in netgroup.byhost
 366          *         (try host.domain, host.*, *.domain or *.*)
 367          *         if found, return yes
 368          *    1.b) if user is specified and host is null:
 369          *         look in netgroup.byuser
 370          *         (try host.domain, host.*, *.domain or *.*)
 371          *         if found, return yes
 372          *    1.c) if both host and user are specified,
 373          *         don't do 'reverse netgroup' lookup.  It won't work.
 374          *    1.d) if neither host ane user are specified (why?!?)
 375          *         don't do 'reverse netgroup' lookup either.
 376          * 2) if domain is specified and 'reverse lookup' is done:
 377          *    'reverse lookup' was authoritative.  bye bye.
 378          * 3) otherwise, too bad, try it the slow way.
 379          */
 380         if (_use_only_yp && (host == NULL) != (user == NULL)) {
 381                 int ret;
 382                 if(yp_get_default_domain(&_netgr_yp_domain))
 383                         return(0);
 384                 ret = _revnetgr_lookup(_netgr_yp_domain,
 385                                       host?"netgroup.byhost":"netgroup.byuser",
 386                                       host?host:user, dom, group);
 387                 if (ret == 1)
 388                         return(1);
 389                 else if (ret == 0 && dom != NULL)
 390                         return(0);
 391         }
 392
 393         setnetgrent(group);
 394 #endif /* YP */
 395
 396         while (getnetgrent(&hst, &usr, &dm))
 397                 if ((host == NULL || hst == NULL || !strcmp(host, hst)) &&
 398                     (user == NULL || usr == NULL || !strcmp(user, usr)) &&
 399                     ( dom == NULL ||  dm == NULL || !strcmp(dom, dm))) {
 400                         endnetgrent();
 401                         return (1);
 402                 }
 403         endnetgrent();
 404         return (0);
 405 }
 406
 407 /*
 408  * Parse the netgroup file setting up the linked lists.
 409  */
 410 static int
 411 parse_netgrp(const char *group)
 412 {
 413         char *spos, *epos;
 414         int len, strpos;
 415 #ifdef DEBUG
 416         int fields;
 417 #endif
 418         char *pos, *gpos;
 419         struct netgrp *grp;
 420         struct linelist *lp = linehead;
 421
 422         /*
 423          * First, see if the line has already been read in.
 424          */
 425         while (lp) {
 426                 if (!strcmp(group, lp->l_groupname))
 427                         break;
 428                 lp = lp->l_next;
 429         }
 430         if (lp == NULL &&
 431             (lp = read_for_group(group)) == NULL)
 432                 return (1);
 433         if (lp->l_parsed) {
 434 #ifdef DEBUG
 435                 /*
 436                  * This error message is largely superflous since the
 437                  * code handles the error condition successfully, and
 438                  * spewing it out from inside libc can actually hose
 439                  * certain programs.
 440                  */
 441                 fprintf(stderr, "Cycle in netgroup %s\n", lp->l_groupname);
 442 #endif
 443                 return (1);
 444         } else
 445                 lp->l_parsed = 1;
 446         pos = lp->l_line;
 447         /* Watch for null pointer dereferences, dammit! */
 448         while (pos != NULL && *pos != '\0') {
 449                 if (*pos == '(') {
 450                         grp = (struct netgrp *)malloc(sizeof (struct netgrp));
 451                         bzero((char *)grp, sizeof (struct netgrp));
 452                         grp->ng_next = grouphead.gr;
 453                         grouphead.gr = grp;
 454                         pos++;
 455                         gpos = strsep(&pos, ")");
 456 #ifdef DEBUG
 457                         fields = 0;
 458 #endif
 459                         for (strpos = 0; strpos < 3; strpos++) {
 460                                 if ((spos = strsep(&gpos, ","))) {
 461 #ifdef DEBUG
 462                                         fields++;
 463 #endif
 464                                         while (*spos == ' ' || *spos == '\t')
 465                                                 spos++;
 466                                         if ((epos = strpbrk(spos, " \t"))) {
 467                                                 *epos = '\0';
 468                                                 len = epos - spos;
 469                                         } else
 470                                                 len = strlen(spos);
 471                                         if (len > 0) {
 472                                                 grp->ng_str[strpos] =  (char *)
 473                                                         malloc(len + 1);
 474                                                 bcopy(spos, grp->ng_str[strpos],
 475                                                         len + 1);
 476                                         }
 477                                 } else {
 478                                         /*
 479                                          * All other systems I've tested
 480                                          * return NULL for empty netgroup
 481                                          * fields. It's up to user programs
 482                                          * to handle the NULLs appropriately.
 483                                          */
 484                                         grp->ng_str[strpos] = NULL;
 485                                 }
 486                         }
 487 #ifdef DEBUG
 488                         /*
 489                          * Note: on other platforms, malformed netgroup
 490                          * entries are not normally flagged. While we
 491                          * can catch bad entries and report them, we should
 492                          * stay silent by default for compatibility's sake.
 493                          */
 494                         if (fields < 3)
 495                                         fprintf(stderr, "Bad entry (%s%s%s%s%s) in netgroup \"%s\"\n",
 496                                                 grp->ng_str[NG_HOST] == NULL ? "" : grp->ng_str[NG_HOST],
 497                                                 grp->ng_str[NG_USER] == NULL ? "" : ",",
 498                                                 grp->ng_str[NG_USER] == NULL ? "" : grp->ng_str[NG_USER],
 499                                                 grp->ng_str[NG_DOM] == NULL ? "" : ",",
 500                                                 grp->ng_str[NG_DOM] == NULL ? "" : grp->ng_str[NG_DOM],
 501                                                 lp->l_groupname);
 502 #endif
 503                 } else {
 504                         spos = strsep(&pos, ", \t");
 505                         if (parse_netgrp(spos))
 506                                 continue;
 507                 }
 508                 if (pos == NULL)
 509                         break;
 510                 while (*pos == ' ' || *pos == ',' || *pos == '\t')
 511                         pos++;
 512         }
 513         return (0);
 514 }
 515
 516 /*
 517  * Read the netgroup file and save lines until the line for the netgroup
 518  * is found. Return 1 if eof is encountered.
 519  */
 520 static struct linelist *
 521 read_for_group(const char *group)
 522 {
 523         char *pos, *spos, *linep = NULL, *olinep = NULL;
 524         int len, olen;
 525         int cont;
 526         struct linelist *lp;
 527         char line[LINSIZ + 2];
 528 #ifdef YP
 529         char *result;
 530         int resultlen;
 531
 532         while (_netgr_yp_enabled || fgets(line, LINSIZ, netf) != NULL) {
 533                 if (_netgr_yp_enabled) {
 534                         if(!_netgr_yp_domain)
 535                                 if(yp_get_default_domain(&_netgr_yp_domain))
 536                                         continue;
 537                         if (yp_match(_netgr_yp_domain, "netgroup", group,
 538                                         strlen(group), &result, &resultlen)) {
 539                                 free(result);
 540                                 if (_use_only_yp)
 541                                         return (NULL);
 542                                 else {
 543                                         _netgr_yp_enabled = 0;
 544                                         continue;
 545                                 }
 546                         }
 547                         snprintf(line, LINSIZ, "%s %s", group, result);
 548                         free(result);
 549                 }
 550 #else
 551         while (fgets(line, LINSIZ, netf) != NULL) {
 552 #endif
 553                 pos = (char *)&line;
 554 #ifdef YP
 555                 if (*pos == '+') {
 556                         _netgr_yp_enabled = 1;
 557                         continue;
 558                 }
 559 #endif
 560                 if (*pos == '#')
 561                         continue;
 562                 while (*pos == ' ' || *pos == '\t')
 563                         pos++;
 564                 spos = pos;
 565                 while (*pos != ' ' && *pos != '\t' && *pos != '\n' &&
 566                         *pos != '\0')
 567                         pos++;
 568                 len = pos - spos;
 569                 while (*pos == ' ' || *pos == '\t')
 570                         pos++;
 571                 if (*pos != '\n' && *pos != '\0') {
 572                         lp = (struct linelist *)malloc(sizeof (*lp));
 573                         lp->l_parsed = 0;
 574                         lp->l_groupname = (char *)malloc(len + 1);
 575                         bcopy(spos, lp->l_groupname, len);
 576                         *(lp->l_groupname + len) = '\0';
 577                         len = strlen(pos);
 578                         olen = 0;
 579
 580                         /*
 581                          * Loop around handling line continuations.
 582                          */
 583                         do {
 584                                 if (*(pos + len - 1) == '\n')
 585                                         len--;
 586                                 if (*(pos + len - 1) == '\\') {
 587                                         len--;
 588                                         cont = 1;
 589                                 } else
 590                                         cont = 0;
 591                                 if (len > 0) {
 592                                         linep = (char *)malloc(olen + len + 1);
 593                                         if (olen > 0) {
 594                                                 bcopy(olinep, linep, olen);
 595                                                 free(olinep);
 596                                         }
 597                                         bcopy(pos, linep + olen, len);
 598                                         olen += len;
 599                                         *(linep + olen) = '\0';
 600                                         olinep = linep;
 601                                 }
 602                                 if (cont) {
 603                                         if (fgets(line, LINSIZ, netf)) {
 604                                                 pos = line;
 605                                                 len = strlen(pos);
 606                                         } else
 607                                                 cont = 0;
 608                                 }
 609                         } while (cont);
 610                         lp->l_line = linep;
 611                         lp->l_next = linehead;
 612                         linehead = lp;
 613
 614                         /*
 615                          * If this is the one we wanted, we are done.
 616                          */
 617                         if (!strcmp(lp->l_groupname, group))
 618                                 return (lp);
 619                 }
 620         }
 621 #ifdef YP
 622         /*
 623          * Yucky. The recursive nature of this whole mess might require
 624          * us to make more than one pass through the netgroup file.
 625          * This might be best left outside the #ifdef YP, but YP is
 626          * defined by default anyway, so I'll leave it like this
 627          * until I know better.
 628          */
 629         rewind(netf);
 630 #endif
 631         return (NULL);
 632 }