nss/nss_db/db-initgroups.c

   1 /* Initgroups handling in nss_db module.
   2    Copyright (C) 2011-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <ctype.h>
  20 #include <errno.h>
  21 #include <grp.h>
  22 #include <limits.h>
  23 #include <paths.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <stdint.h>
  27 #include <sys/param.h>
  28
  29 #include "nss_db.h"
  30
  31 /* The hashing function we use.  */
  32 #include "../intl/hash-string.h"
  33
  34 enum nss_status
  35 _nss_db_initgroups_dyn (const char *user, gid_t group, long int *start,
  36                         long int *size, gid_t **groupsp, long int limit,
  37                         int *errnop)
  38 {
  39   struct nss_db_map state = { NULL, 0 };
  40   enum nss_status status = internal_setent (_PATH_VARDB "group.db", &state);
  41   if (status != NSS_STATUS_SUCCESS)
  42     {
  43       *errnop = errno;
  44       return status;
  45     }
  46
  47   const struct nss_db_header *header = state.header;
  48   int i;
  49   for (i = 0; i < header->ndbs; ++i)
  50     if (header->dbs[i].id == ':')
  51       break;
  52   if (i == header->ndbs)
  53     {
  54       status = NSS_STATUS_UNAVAIL;
  55       goto out;
  56     }
  57
  58   const stridx_t *hashtable
  59     = (const stridx_t *) ((const char *) header
  60                           + header->dbs[i].hashoffset);
  61   const char *valstrtab = (const char *) header + header->valstroffset;
  62   size_t userlen = strlen (user);
  63   uint32_t hashval = __hash_string (user);
  64   size_t hidx = hashval % header->dbs[i].hashsize;
  65   size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2);
  66
  67   gid_t *groups = *groupsp;
  68
  69   status = NSS_STATUS_NOTFOUND;
  70   while (hashtable[hidx] != ~((stridx_t) 0))
  71     {
  72       const char *valstr = valstrtab + hashtable[hidx];
  73       while (isblank (*valstr))
  74         ++valstr;
  75
  76       if (strncmp (valstr, user, userlen) == 0 && isblank (valstr[userlen]))
  77         {
  78           valstr += userlen + 1;
  79           while (isblank (*valstr))
  80             ++valstr;
  81
  82           while (*valstr != '\0')
  83             {
  84               errno = 0;
  85               char *endp;
  86               unsigned long int n = strtoul (valstr, &endp, 10);
  87               if (*endp != ',' && *endp != '\0')
  88                 break;
  89               valstr = *endp == '\0' ? endp : endp + 1;
  90
  91               if (n != ULONG_MAX || errno != ERANGE)
  92                 {
  93                   /* Insert the group.  */
  94                   if (*start == *size)
  95                     {
  96                       /* Need a bigger buffer.  */
  97                       if (limit > 0 && *size == limit)
  98                         {
  99                           /* We reached the maximum.  */
 100                           status = NSS_STATUS_SUCCESS;
 101                           goto out;
 102                         }
 103
 104                       long int newsize;
 105                       if (limit <= 0)
 106                         newsize = 2 * *size;
 107                       else
 108                         newsize = MIN (limit, 2 * *size);
 109
 110                       gid_t *newgroups = realloc (groups,
 111                                                   newsize * sizeof (*groups));
 112                       if (newgroups == NULL)
 113                         {
 114                           *errnop = ENOMEM;
 115                           status = NSS_STATUS_TRYAGAIN;
 116                           goto out;
 117                         }
 118
 119                       *groupsp = groups = newgroups;
 120                       *size = newsize;
 121                     }
 122
 123                   groups[*start] = n;
 124                   *start += 1;
 125                 }
 126             }
 127
 128           status = NSS_STATUS_SUCCESS;
 129           break;
 130         }
 131
 132       if ((hidx += hval2) >= header->dbs[i].hashsize)
 133         hidx -= header->dbs[i].hashsize;
 134     }
 135
 136  out:
 137   internal_endent (&state);
 138
 139   return status;
 140 }