grp/initgroups.c

   1 /* Copyright (C) 1989,91,93,1996-2005,2006 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   /* Never store more than the starting *SIZE number of elements.  */
  77   assert (*size > 0);
  78   (*groupsp)[0] = group;
  79
  80   if (__nss_group_database != NULL)
  81     {
  82       no_more = 0;
  83       nip = __nss_group_database;
  84     }
  85   else
  86     no_more = __nss_database_lookup ("group", NULL,
  87                                      "compat [NOTFOUND=return] files", &nip);
  88
  89   while (! no_more)
  90     {
  91       long int prev_start = start;
  92
  93       fct = __nss_lookup_function (nip, "initgroups_dyn");
  94
  95       if (fct == NULL)
  96         {
  97           status = compat_call (nip, user, group, &start, size, groupsp,
  98                                 limit, &errno);
  99
 100           if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
 101             break;
 102         }
 103       else
 104         status = DL_CALL_FCT (fct, (user, group, &start, size, groupsp,
 105                                     limit, &errno));
 106
 107       /* Remove duplicates.  */
 108       long int cnt = prev_start;
 109       while (cnt < start)
 110         {
 111           long int inner;
 112           for (inner = 0; inner < prev_start; ++inner)
 113             if ((*groupsp)[inner] == (*groupsp)[cnt])
 114               break;
 115
 116           if (inner < prev_start)
 117             (*groupsp)[cnt] = (*groupsp)[--start];
 118           else
 119             ++cnt;
 120         }
 121
 122       /* This is really only for debugging.  */
 123       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 124         __libc_fatal ("illegal status in internal_getgrouplist");
 125
 126       if (status != NSS_STATUS_SUCCESS
 127           && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 128          break;
 129
 130       if (nip->next == NULL)
 131         no_more = -1;
 132       else
 133         nip = nip->next;
 134     }
 135
 136   return start;
 137 }
 138
 139 /* Store at most *NGROUPS members of the group set for USER into
 140    *GROUPS.  Also include GROUP.  The actual number of groups found is
 141    returned in *NGROUPS.  Return -1 if the if *NGROUPS is too small.  */
 142 int
 143 getgrouplist (const char *user, gid_t group, gid_t *groups, int *ngroups)
 144 {
 145   long int size = MAX (1, *ngroups);
 146
 147   gid_t *newgroups = (gid_t *) malloc ((size + 1) * sizeof (gid_t));
 148   if (__builtin_expect (newgroups == NULL, 0))
 149     /* No more memory.  */
 150     // XXX This is wrong.  The user provided memory, we have to use
 151     // XXX it.  The internal functions must be called with the user
 152     // XXX provided buffer and not try to increase the size if it is
 153     // XXX too small.  For initgroups a flag could say: increase size.
 154     return -1;
 155
 156   int total = internal_getgrouplist (user, group, &size, &newgroups, -1);
 157
 158   memcpy (groups, newgroups, MIN (*ngroups, total) * sizeof (gid_t));
 159
 160   free (newgroups);
 161
 162   int retval = total > *ngroups ? -1 : total;
 163   *ngroups = total;
 164
 165   return retval;
 166 }
 167
 168 static_link_warning (getgrouplist)
 169
 170 /* Initialize the group set for the current user
 171    by reading the group database and using all groups
 172    of which USER is a member.  Also include GROUP.  */
 173 int
 174 initgroups (const char *user, gid_t group)
 175 {
 176 #if defined NGROUPS_MAX && NGROUPS_MAX == 0
 177
 178   /* No extra groups allowed.  */
 179   return 0;
 180
 181 #else
 182
 183   long int size;
 184   gid_t *groups;
 185   int ngroups;
 186   int result;
 187
 188  /* We always use sysconf even if NGROUPS_MAX is defined.  That way, the
 189      limit can be raised in the kernel configuration without having to
 190      recompile libc.  */
 191   long int limit = __sysconf (_SC_NGROUPS_MAX);
 192
 193   if (limit > 0)
 194     /* We limit the size of the intially allocated array.  */
 195     size = MIN (limit, 64);
 196   else
 197     /* No fixed limit on groups.  Pick a starting buffer size.  */
 198     size = 16;
 199
 200   groups = (gid_t *) malloc (size * sizeof (gid_t));
 201   if (__builtin_expect (groups == NULL, 0))
 202     /* No more memory.  */
 203     return -1;
 204
 205   ngroups = internal_getgrouplist (user, group, &size, &groups, limit);
 206
 207   /* Try to set the maximum number of groups the kernel can handle.  */
 208   do
 209     result = setgroups (ngroups, groups);
 210   while (result == -1 && errno == EINVAL && --ngroups > 0);
 211
 212   free (groups);
 213
 214   return result;
 215 #endif
 216 }
 217
 218 static_link_warning (initgroups)