grp/initgroups.c

   1 /* Copyright (C) 1989, 91, 93, 96, 97, 98, 99 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <alloca.h>
  20 #include <errno.h>
  21 #include <grp.h>
  22 #include <limits.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <sys/types.h>
  27 #include <nsswitch.h>
  28
  29
  30 /* Type of the lookup function.  */
  31 typedef enum nss_status (*initgroups_function) (const char *, gid_t,
  32                                                 long int *, long int *,
  33                                                 gid_t *, long int, int *);
  34 /* Prototype for the setgrent functions we use here.  */
  35 typedef enum nss_status (*set_function) (void);
  36
  37 /* Prototype for the endgrent functions we use here.  */
  38 typedef enum nss_status (*end_function) (void);
  39
  40 /* Prototype for the setgrent functions we use here.  */
  41 typedef enum nss_status (*get_function) (struct group *, char *,
  42                                          size_t, int *);
  43
  44 /* The lookup function for the first entry of this service.  */
  45 extern int __nss_group_lookup (service_user **nip, const char *name,
  46                                    void **fctp);
  47 extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
  48
  49 extern service_user *__nss_group_database;
  50
  51 static enum nss_status
  52 compat_call (service_user *nip, const char *user, gid_t group, long int *start,
  53              long int *size, gid_t *groups, long int limit, int *errnop)
  54 {
  55   struct group grpbuf;
  56   size_t buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
  57   char *tmpbuf;
  58   enum nss_status status;
  59   set_function setgrent_fct;
  60   get_function getgrent_fct;
  61   end_function endgrent_fct;
  62
  63   getgrent_fct = __nss_lookup_function (nip, "getgrent_r");
  64   if (getgrent_fct == NULL)
  65     return NSS_STATUS_UNAVAIL;
  66
  67   setgrent_fct = __nss_lookup_function (nip, "setgrent");
  68   if (setgrent_fct)
  69     {
  70       status = _CALL_DL_FCT (setgrent_fct, ());
  71       if (status != NSS_STATUS_SUCCESS)
  72         return status;
  73     }
  74
  75   endgrent_fct = __nss_lookup_function (nip, "endgrent");
  76
  77   tmpbuf = __alloca (buflen);
  78
  79   do
  80     {
  81       while ((status = _CALL_DL_FCT (getgrent_fct,
  82                                      (&grpbuf, tmpbuf, buflen, errnop)),
  83               status == NSS_STATUS_TRYAGAIN)
  84              && *errnop == ERANGE)
  85         {
  86           buflen *= 2;
  87           tmpbuf = __alloca (buflen);
  88         }
  89
  90       if (status != NSS_STATUS_SUCCESS)
  91         goto done;
  92
  93       if (grpbuf.gr_gid != group)
  94         {
  95           char **m;
  96
  97           for (m = grpbuf.gr_mem; *m != NULL; ++m)
  98             if (strcmp (*m, user) == 0)
  99               {
 100                 /* Matches user.  Insert this group.  */
 101                 if (*start == *size && limit <= 0)
 102                   {
 103                     /* Need a bigger buffer.  */
 104                     groups = realloc (groups, 2 * *size * sizeof (*groups));
 105                     if (groups == NULL)
 106                       goto done;
 107                     *size *= 2;
 108                   }
 109
 110                 groups[*start] = grpbuf.gr_gid;
 111                 *start += 1;
 112
 113                 if (*start == limit)
 114                   /* Can't take any more groups; stop searching.  */
 115                   goto done;
 116
 117                 break;
 118               }
 119         }
 120     }
 121   while (status == NSS_STATUS_SUCCESS);
 122
 123  done:
 124   if (endgrent_fct)
 125     _CALL_DL_FCT (endgrent_fct, ());
 126
 127   return NSS_STATUS_SUCCESS;
 128 }
 129
 130 /* Initialize the group set for the current user
 131    by reading the group database and using all groups
 132    of which USER is a member.  Also include GROUP.  */
 133 int
 134 initgroups (user, group)
 135      const char *user;
 136      gid_t group;
 137 {
 138 #if defined NGROUPS_MAX && NGROUPS_MAX == 0
 139
 140   /* No extra groups allowed.  */
 141   return 0;
 142
 143 #else
 144
 145   service_user *nip = NULL;
 146   initgroups_function fct;
 147   enum nss_status status = NSS_STATUS_UNAVAIL;
 148   int no_more;
 149   /* Start is one, because we have the first group as parameter.  */
 150   long int start = 1;
 151   long int size;
 152   gid_t *groups;
 153 #ifdef NGROUPS_MAX
 154 # define limit NGROUPS_MAX
 155
 156   size = limit;
 157 #else
 158   long int limit = __sysconf (_SC_NGROUPS_MAX);
 159
 160   if (limit > 0)
 161     size = limit;
 162   else
 163     /* No fixed limit on groups.  Pick a starting buffer size.  */
 164     size = 16;
 165 #endif
 166
 167   groups = malloc (size * sizeof (gid_t *));
 168
 169   groups[0] = group;
 170
 171   if (__nss_group_database != NULL)
 172     {
 173       no_more = 0;
 174       nip = __nss_group_database;
 175     }
 176   else
 177     no_more = __nss_database_lookup ("group", NULL,
 178                                      "compat [NOTFOUND=return] files", &nip);
 179
 180   while (! no_more)
 181     {
 182       fct = __nss_lookup_function (nip, "initgroups");
 183
 184       if (fct == NULL)
 185         {
 186           status = compat_call (nip, user, group, &start, &size, groups,
 187                                 limit, &errno);
 188
 189           if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
 190             break;
 191         }
 192       else
 193         status = _CALL_DL_FCT (fct, (user, group, &start, &size, groups, limit,
 194                                      &errno));
 195
 196       /* This is really only for debugging.  */
 197       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 198         __libc_fatal ("illegal status in " __FUNCTION__);
 199
 200       if (status != NSS_STATUS_SUCCESS
 201           && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 202          break;
 203
 204       if (nip->next == NULL)
 205         no_more = -1;
 206       else
 207         nip = nip->next;
 208     }
 209
 210   return setgroups (start, groups);
 211 #endif
 212 }