nis/nss_nis/nis-initgroups.c

   1 /* Copyright (C) 1998-2020 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Thorsten Kukuk <kukuk@suse.de>, 1998.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <ctype.h>
  20 #include <errno.h>
  21 #include <grp.h>
  22 #include <nss.h>
  23 #include <pwd.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <rpcsvc/yp.h>
  27 #include <rpcsvc/ypclnt.h>
  28 #include <sys/param.h>
  29 #include <scratch_buffer.h>
  30
  31 #include "nss-nis.h"
  32 #include <libnsl.h>
  33
  34 /* Get the declaration of the parser function.  */
  35 #define ENTNAME grent
  36 #define STRUCTURE group
  37 #define EXTERN_PARSER
  38 #include <nss/nss_files/files-parse.c>
  39
  40
  41 static enum nss_status
  42 internal_setgrent (char *domainname, intern_t *intern)
  43 {
  44   struct ypall_callback ypcb;
  45   enum nss_status status;
  46
  47   ypcb.foreach = _nis_saveit;
  48   ypcb.data = (char *) intern;
  49   status = yperr2nss (yp_all (domainname, "group.byname", &ypcb));
  50
  51   /* Mark the last buffer as full.  */
  52   if (intern->next != NULL)
  53     intern->next->size = intern->offset;
  54
  55   intern->next = intern->start;
  56   intern->offset = 0;
  57
  58   return status;
  59 }
  60
  61
  62 static enum nss_status
  63 internal_getgrent_r (struct group *grp, char *buffer, size_t buflen,
  64                      int *errnop, intern_t *intern)
  65 {
  66   if (intern->start == NULL)
  67     return NSS_STATUS_NOTFOUND;
  68
  69   /* Get the next entry until we found a correct one. */
  70   int parse_res;
  71   do
  72     {
  73       struct response_t *bucket = intern->next;
  74
  75       if (__glibc_unlikely (intern->offset >= bucket->size))
  76         {
  77           if (bucket->next == NULL)
  78             return NSS_STATUS_NOTFOUND;
  79
  80           /* We look at all the content in the current bucket.  Go on
  81              to the next.  */
  82           bucket = intern->next = bucket->next;
  83           intern->offset = 0;
  84         }
  85
  86       char *p;
  87       for (p = &bucket->mem[intern->offset]; isspace (*p); ++p)
  88         ++intern->offset;
  89
  90       size_t len = strlen (p) + 1;
  91       if (__glibc_unlikely (len > buflen))
  92         {
  93           *errnop = ERANGE;
  94           return NSS_STATUS_TRYAGAIN;
  95         }
  96
  97       /* We unfortunately have to copy the data in the user-provided
  98          buffer because that buffer might be around for a very long
  99          time and the servent structure must remain valid.  If we would
 100          rely on the BUCKET memory the next 'setservent' or 'endservent'
 101          call would destroy it.
 102
 103          The important thing is that it is a single NUL-terminated
 104          string.  This is what the parsing routine expects.  */
 105       p = memcpy (buffer, &bucket->mem[intern->offset], len);
 106
 107       parse_res = _nss_files_parse_grent (p, grp, (void *) buffer, buflen,
 108                                           errnop);
 109       if (__glibc_unlikely (parse_res == -1))
 110         return NSS_STATUS_TRYAGAIN;
 111
 112       intern->offset += len;
 113     }
 114   while (!parse_res);
 115
 116   return NSS_STATUS_SUCCESS;
 117 }
 118
 119
 120 static int
 121 get_uid (const char *user, uid_t *uidp)
 122 {
 123   struct scratch_buffer tmpbuf;
 124   scratch_buffer_init (&tmpbuf);
 125
 126   while (1)
 127     {
 128       struct passwd result;
 129       struct passwd *resp;
 130
 131       int r = getpwnam_r (user, &result, tmpbuf.data, tmpbuf.length, &resp);
 132       if (r == 0 && resp != NULL)
 133         {
 134           *uidp = resp->pw_uid;
 135           scratch_buffer_free (&tmpbuf);
 136           return 0;
 137         }
 138
 139       if (r != ERANGE)
 140         break;
 141
 142       if (!scratch_buffer_grow (&tmpbuf))
 143         return 1;
 144     }
 145
 146   scratch_buffer_free (&tmpbuf);
 147   return 1;
 148 }
 149
 150
 151 static enum nss_status
 152 initgroups_netid (uid_t uid, gid_t group, long int *start, long int *size,
 153                   gid_t **groupsp, long int limit, int *errnop,
 154                   const char *domainname)
 155 {
 156   /* Limit domainname length to the maximum size of an RPC packet.  */
 157   if (strlen (domainname) > UDPMSGSIZE)
 158     {
 159       *errnop = ERANGE;
 160       return NSS_STATUS_UNAVAIL;
 161     }
 162
 163   /* Prepare the key.  The form is "unix.UID@DOMAIN" with the UID and
 164      DOMAIN field filled in appropriately.  */
 165   char key[sizeof ("unix.@") + sizeof (uid_t) * 3 + strlen (domainname)];
 166   ssize_t keylen = snprintf (key, sizeof (key), "unix.%lu@%s",
 167                              (unsigned long int) uid, domainname);
 168
 169   char *result;
 170   int reslen;
 171   int yperr = yp_match (domainname, "netid.byname", key, keylen, &result,
 172                         &reslen);
 173   if (__glibc_unlikely (yperr != YPERR_SUCCESS))
 174     return yperr2nss (yperr);
 175
 176   /* Parse the result: following the colon is a comma separated list of
 177      group IDs.  */
 178   char *cp = strchr (result, ':');
 179   if (cp == NULL)
 180     {
 181     errout:
 182       free (result);
 183       return NSS_STATUS_NOTFOUND;
 184     }
 185   /* Skip the colon.  */
 186   ++cp;
 187
 188   gid_t *groups = *groupsp;
 189   while (*cp != '\0')
 190     {
 191       char *endp;
 192       unsigned long int gid = strtoul (cp, &endp, 0);
 193       if (cp == endp)
 194         goto errout;
 195       if (*endp == ',')
 196         ++endp;
 197       else if (*endp != '\0')
 198         goto errout;
 199       cp = endp;
 200
 201       if (gid == group)
 202         /* We do not need this group again.  */
 203         continue;
 204
 205       /* Insert this group.  */
 206       if (*start == *size)
 207         {
 208           /* Need a bigger buffer.  */
 209           long int newsize;
 210
 211           if (limit > 0 && *size == limit)
 212             /* We reached the maximum.  */
 213             break;
 214
 215           if (limit <= 0)
 216             newsize = 2 * *size;
 217           else
 218             newsize = MIN (limit, 2 * *size);
 219
 220           gid_t *newgroups = realloc (groups, newsize * sizeof (*groups));
 221           if (newgroups == NULL)
 222             goto errout;
 223           *groupsp = groups = newgroups;
 224           *size = newsize;
 225         }
 226
 227       groups[*start] = gid;
 228       *start += 1;
 229     }
 230
 231   free (result);
 232
 233   return NSS_STATUS_SUCCESS;
 234 }
 235
 236
 237 enum nss_status
 238 _nss_nis_initgroups_dyn (const char *user, gid_t group, long int *start,
 239                          long int *size, gid_t **groupsp, long int limit,
 240                          int *errnop)
 241 {
 242   /* We always need the domain name.  */
 243   char *domainname;
 244   if (yp_get_default_domain (&domainname))
 245     return NSS_STATUS_UNAVAIL;
 246
 247   /* Check whether we are supposed to use the netid.byname map.  */
 248   if (_nsl_default_nss () & NSS_FLAG_NETID_AUTHORITATIVE)
 249     {
 250       /* We need the user ID.  */
 251       uid_t uid;
 252
 253       if (get_uid (user, &uid) == 0
 254           && initgroups_netid (uid, group, start, size, groupsp, limit,
 255                                errnop, domainname) == NSS_STATUS_SUCCESS)
 256         return NSS_STATUS_SUCCESS;
 257     }
 258
 259   struct group grpbuf, *g;
 260   enum nss_status status;
 261   intern_t intern = { NULL, NULL, 0 };
 262   gid_t *groups = *groupsp;
 263
 264   status = internal_setgrent (domainname, &intern);
 265   if (status != NSS_STATUS_SUCCESS)
 266     return status;
 267
 268   struct scratch_buffer tmpbuf;
 269   scratch_buffer_init (&tmpbuf);
 270
 271   while (1)
 272     {
 273       while ((status =
 274               internal_getgrent_r (&grpbuf, tmpbuf.data, tmpbuf.length, errnop,
 275                                    &intern)) == NSS_STATUS_TRYAGAIN
 276              && *errnop == ERANGE)
 277         if (!scratch_buffer_grow (&tmpbuf))
 278           {
 279             status = NSS_STATUS_TRYAGAIN;
 280             goto done;
 281           }
 282
 283       if (status != NSS_STATUS_SUCCESS)
 284         {
 285           if (status == NSS_STATUS_NOTFOUND)
 286             status = NSS_STATUS_SUCCESS;
 287           goto done;
 288         }
 289
 290       g = &grpbuf;
 291       if (g->gr_gid != group)
 292         {
 293           char **m;
 294
 295           for (m = g->gr_mem; *m != NULL; ++m)
 296             if (strcmp (*m, user) == 0)
 297               {
 298                 /* Matches user.  Insert this group.  */
 299                 if (*start == *size)
 300                   {
 301                     /* Need a bigger buffer.  */
 302                     gid_t *newgroups;
 303                     long int newsize;
 304
 305                     if (limit > 0 && *size == limit)
 306                       /* We reached the maximum.  */
 307                       goto done;
 308
 309                     if (limit <= 0)
 310                       newsize = 2 * *size;
 311                     else
 312                       newsize = MIN (limit, 2 * *size);
 313
 314                     newgroups = realloc (groups, newsize * sizeof (*groups));
 315                     if (newgroups == NULL)
 316                       {
 317                         status = NSS_STATUS_TRYAGAIN;
 318                         *errnop = errno;
 319                         goto done;
 320                       }
 321                     *groupsp = groups = newgroups;
 322                     *size = newsize;
 323                   }
 324
 325                 groups[*start] = g->gr_gid;
 326                 *start += 1;
 327
 328                 break;
 329               }
 330         }
 331     }
 332
 333 done:
 334   while (intern.start != NULL)
 335     {
 336       intern.next = intern.start;
 337       intern.start = intern.start->next;
 338       free (intern.next);
 339     }
 340   scratch_buffer_free (&tmpbuf);
 341
 342   return status;
 343 }