grp/initgroups.c

   1 /* Copyright (C) 1989,91,93,1996-2003, 2004  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 <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/param.h>
  27 #include <sys/types.h>
  28 #include <nsswitch.h>
  29
  30 #include "../nscd/nscd-client.h"
  31 #include "../nscd/nscd_proto.h"
  32
  33
  34 /* Type of the lookup function.  */
  35 typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
  36                                                     long int *, long int *,
  37                                                     gid_t **, long int, int *);
  38
  39 /* The lookup function for the first entry of this service.  */
  40 extern int __nss_group_lookup (service_user **nip, const char *name,
  41                                    void **fctp);
  42 extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
  43
  44 extern service_user *__nss_group_database attribute_hidden;
  45
  46
  47 #include "compat-initgroups.c"
  48
  49
  50 static int
  51 internal_getgrouplist (const char *user, gid_t group, long int *size,
  52                        gid_t **groupsp, long int limit)
  53 {
  54 #ifdef USE_NSCD
  55   if (__nss_not_use_nscd_group > 0
  56       && ++__nss_not_use_nscd_group > NSS_NSCD_RETRY)
  57     __nss_not_use_nscd_group = 0;
  58   if (!__nss_not_use_nscd_group)
  59     {
  60       int n = __nscd_getgrouplist (user, group, size, groupsp, limit);
  61       if (n >= 0)
  62         return n;
  63
  64       /* nscd is not usable.  */
  65       __nss_not_use_nscd_group = 1;
  66     }
  67 #endif
  68
  69   service_user *nip = NULL;
  70   initgroups_dyn_function fct;
  71   enum nss_status status = NSS_STATUS_UNAVAIL;
  72   int no_more;
  73   /* Start is one, because we have the first group as parameter.  */
  74   long int start = 1;
  75
  76   *groupsp[0] = group;
  77
  78   if (__nss_group_database != NULL)
  79     {
  80       no_more = 0;
  81       nip = __nss_group_database;
  82     }
  83   else
  84     no_more = __nss_database_lookup ("group", NULL,
  85                                      "compat [NOTFOUND=return] files", &nip);
  86
  87   while (! no_more)
  88     {
  89       fct = __nss_lookup_function (nip, "initgroups_dyn");
  90
  91       if (fct == NULL)
  92         {
  93           status = compat_call (nip, user, group, &start, size, groupsp,
  94                                 limit, &errno);
  95
  96           if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
  97             break;
  98         }
  99       else
 100         status = DL_CALL_FCT (fct, (user, group, &start, size, groupsp,
 101                                     limit, &errno));
 102
 103       /* This is really only for debugging.  */
 104       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 105         __libc_fatal ("illegal status in internal_getgrouplist");
 106
 107       if (status != NSS_STATUS_SUCCESS
 108           && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 109          break;
 110
 111       if (nip->next == NULL)
 112         no_more = -1;
 113       else
 114         nip = nip->next;
 115     }
 116
 117   return start;
 118 }
 119
 120 /* Store at most *NGROUPS members of the group set for USER into
 121    *GROUPS.  Also include GROUP.  The actual number of groups found is
 122    returned in *NGROUPS.  Return -1 if the if *NGROUPS is too small.  */
 123 int
 124 getgrouplist (const char *user, gid_t group, gid_t *groups, int *ngroups)
 125 {
 126   gid_t *newgroups;
 127   long int size = *ngroups;
 128   int result;
 129
 130   newgroups = (gid_t *) malloc (size * sizeof (gid_t));
 131   if (__builtin_expect (newgroups == NULL, 0))
 132     /* No more memory.  */
 133     // XXX This is wrong.  The user provided memory, we have to use
 134     // XXX it.  The internal functions must be called with the user
 135     // XXX provided buffer and not try to increase the size if it is
 136     // XXX too small.  For initgroups a flag could say: increase size.
 137     return -1;
 138
 139   result = internal_getgrouplist (user, group, &size, &newgroups, -1);
 140
 141   memcpy (groups, newgroups, MIN (*ngroups, result) * sizeof (gid_t));
 142
 143   if (result > *ngroups)
 144     {
 145       *ngroups = result;
 146       result = -1;
 147     }
 148   else
 149     *ngroups = result;
 150
 151   free (newgroups);
 152   return result;
 153 }
 154
 155 static_link_warning (getgrouplist)
 156
 157 /* Initialize the group set for the current user
 158    by reading the group database and using all groups
 159    of which USER is a member.  Also include GROUP.  */
 160 int
 161 initgroups (const char *user, gid_t group)
 162 {
 163 #if defined NGROUPS_MAX && NGROUPS_MAX == 0
 164
 165   /* No extra groups allowed.  */
 166   return 0;
 167
 168 #else
 169
 170   long int size;
 171   gid_t *groups;
 172   int ngroups;
 173   int result;
 174
 175  /* We always use sysconf even if NGROUPS_MAX is defined.  That way, the
 176      limit can be raised in the kernel configuration without having to
 177      recompile libc.  */
 178   long int limit = __sysconf (_SC_NGROUPS_MAX);
 179
 180   if (limit > 0)
 181     /* We limit the size of the intially allocated array.  */
 182     size = MIN (limit, 64);
 183   else
 184     /* No fixed limit on groups.  Pick a starting buffer size.  */
 185     size = 16;
 186
 187   groups = (gid_t *) malloc (size * sizeof (gid_t));
 188   if (__builtin_expect (groups == NULL, 0))
 189     /* No more memory.  */
 190     return -1;
 191
 192   ngroups = internal_getgrouplist (user, group, &size, &groups, limit);
 193
 194   /* Try to set the maximum number of groups the kernel can handle.  */
 195   do
 196     result = setgroups (ngroups, groups);
 197   while (result == -1 && errno == EINVAL && --ngroups > 0);
 198
 199   free (groups);
 200
 201   return result;
 202 #endif
 203 }
 204
 205 static_link_warning (initgroups)