grp/initgroups.c

   1 /* Copyright (C) 1989,91,93,1996-2006,2008,2010 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <alloca.h>
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <grp.h>
  23 #include <limits.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <sys/param.h>
  28 #include <sys/types.h>
  29 #include <nsswitch.h>
  30
  31 #include "../nscd/nscd-client.h"
  32 #include "../nscd/nscd_proto.h"
  33
  34
  35 /* Type of the lookup function.  */
  36 typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
  37                                                     long int *, long int *,
  38                                                     gid_t **, long int, int *);
  39
  40 /* The lookup function for the first entry of this service.  */
  41 extern int __nss_group_lookup (service_user **nip, const char *name,
  42                                    void **fctp);
  43 extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
  44
  45 extern service_user *__nss_group_database attribute_hidden;
  46
  47
  48 #include "compat-initgroups.c"
  49
  50
  51 static int
  52 internal_getgrouplist (const char *user, gid_t group, long int *size,
  53                        gid_t **groupsp, long int limit)
  54 {
  55 #ifdef USE_NSCD
  56   if (__nss_not_use_nscd_group > 0
  57       && ++__nss_not_use_nscd_group > NSS_NSCD_RETRY)
  58     __nss_not_use_nscd_group = 0;
  59   if (!__nss_not_use_nscd_group
  60       && !__nss_database_custom[NSS_DBSIDX_group])
  61     {
  62       int n = __nscd_getgrouplist (user, group, size, groupsp, limit);
  63       if (n >= 0)
  64         return n;
  65
  66       /* nscd is not usable.  */
  67       __nss_not_use_nscd_group = 1;
  68     }
  69 #endif
  70
  71   service_user *nip = NULL;
  72   initgroups_dyn_function fct;
  73   enum nss_status status = NSS_STATUS_UNAVAIL;
  74   int no_more;
  75   /* Start is one, because we have the first group as parameter.  */
  76   long int start = 1;
  77
  78   /* Never store more than the starting *SIZE number of elements.  */
  79   assert (*size > 0);
  80   (*groupsp)[0] = group;
  81
  82   if (__nss_group_database != NULL)
  83     {
  84       no_more = 0;
  85       nip = __nss_group_database;
  86     }
  87   else
  88     no_more = __nss_database_lookup ("group", NULL,
  89                                      "compat [NOTFOUND=return] files", &nip);
  90
  91   while (! no_more)
  92     {
  93       long int prev_start = start;
  94
  95       fct = __nss_lookup_function (nip, "initgroups_dyn");
  96
  97       if (fct == NULL)
  98         status = compat_call (nip, user, group, &start, size, groupsp,
  99                               limit, &errno);
 100       else
 101         status = DL_CALL_FCT (fct, (user, group, &start, size, groupsp,
 102                                     limit, &errno));
 103
 104       /* Remove duplicates.  */
 105       long int cnt = prev_start;
 106       while (cnt < start)
 107         {
 108           long int inner;
 109           for (inner = 0; inner < prev_start; ++inner)
 110             if ((*groupsp)[inner] == (*groupsp)[cnt])
 111               break;
 112
 113           if (inner < prev_start)
 114             (*groupsp)[cnt] = (*groupsp)[--start];
 115           else
 116             ++cnt;
 117         }
 118
 119       /* This is really only for debugging.  */
 120       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 121         __libc_fatal ("illegal status in internal_getgrouplist");
 122
 123       if (status != NSS_STATUS_SUCCESS
 124           && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 125          break;
 126
 127       if (nip->next == NULL)
 128         no_more = -1;
 129       else
 130         nip = nip->next;
 131     }
 132
 133   return start;
 134 }
 135
 136 /* Store at most *NGROUPS members of the group set for USER into
 137    *GROUPS.  Also include GROUP.  The actual number of groups found is
 138    returned in *NGROUPS.  Return -1 if the if *NGROUPS is too small.  */
 139 int
 140 getgrouplist (const char *user, gid_t group, gid_t *groups, int *ngroups)
 141 {
 142   long int size = MAX (1, *ngroups);
 143
 144   gid_t *newgroups = (gid_t *) malloc (size * sizeof (gid_t));
 145   if (__builtin_expect (newgroups == NULL, 0))
 146     /* No more memory.  */
 147     // XXX This is wrong.  The user provided memory, we have to use
 148     // XXX it.  The internal functions must be called with the user
 149     // XXX provided buffer and not try to increase the size if it is
 150     // XXX too small.  For initgroups a flag could say: increase size.
 151     return -1;
 152
 153   int total = internal_getgrouplist (user, group, &size, &newgroups, -1);
 154
 155   memcpy (groups, newgroups, MIN (*ngroups, total) * sizeof (gid_t));
 156
 157   free (newgroups);
 158
 159   int retval = total > *ngroups ? -1 : total;
 160   *ngroups = total;
 161
 162   return retval;
 163 }
 164
 165 static_link_warning (getgrouplist)
 166
 167 /* Initialize the group set for the current user
 168    by reading the group database and using all groups
 169    of which USER is a member.  Also include GROUP.  */
 170 int
 171 initgroups (const char *user, gid_t group)
 172 {
 173 #if defined NGROUPS_MAX && NGROUPS_MAX == 0
 174
 175   /* No extra groups allowed.  */
 176   return 0;
 177
 178 #else
 179
 180   long int size;
 181   gid_t *groups;
 182   int ngroups;
 183   int result;
 184
 185  /* We always use sysconf even if NGROUPS_MAX is defined.  That way, the
 186      limit can be raised in the kernel configuration without having to
 187      recompile libc.  */
 188   long int limit = __sysconf (_SC_NGROUPS_MAX);
 189
 190   if (limit > 0)
 191     /* We limit the size of the intially allocated array.  */
 192     size = MIN (limit, 64);
 193   else
 194     /* No fixed limit on groups.  Pick a starting buffer size.  */
 195     size = 16;
 196
 197   groups = (gid_t *) malloc (size * sizeof (gid_t));
 198   if (__builtin_expect (groups == NULL, 0))
 199     /* No more memory.  */
 200     return -1;
 201
 202   ngroups = internal_getgrouplist (user, group, &size, &groups, limit);
 203
 204   /* Try to set the maximum number of groups the kernel can handle.  */
 205   do
 206     result = setgroups (ngroups, groups);
 207   while (result == -1 && errno == EINVAL && --ngroups > 0);
 208
 209   free (groups);
 210
 211   return result;
 212 #endif
 213 }
 214
 215 static_link_warning (initgroups)