source3/lib/system_smbd.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    system call wrapper interface.
   4    Copyright (C) Andrew Tridgell 2002
   5    Copyright (C) Andrew Barteltt 2002
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 /*
  22    This file may assume linkage with smbd - for things like become_root()
  23    etc.
  24 */
  25
  26 #include "includes.h"
  27 #include "system/passwd.h"
  28 #include "nsswitch/winbind_client.h"
  29 #include "../lib/util/setid.h"
  30
  31 #ifndef HAVE_GETGROUPLIST
  32
  33 #ifdef HAVE_GETGRSET
  34 static int getgrouplist_getgrset(const char *user, gid_t gid, gid_t *groups,
  35                                  int *grpcnt)
  36 {
  37         char *grplist;
  38         char *grp;
  39         gid_t temp_gid;
  40         int num_gids = 1;
  41         int ret = 0;
  42         long l;
  43
  44         grplist = getgrset(user);
  45
  46         DEBUG(10, ("getgrset returned %s\n", grplist));
  47
  48         if (grplist == NULL) {
  49                 return -1;
  50         }
  51
  52         if (*grpcnt > 0) {
  53                 groups[0] = gid;
  54         }
  55
  56         while ((grp = strsep(&grplist, ",")) != NULL) {
  57                 l = strtol(grp, NULL, 10);
  58                 temp_gid = (gid_t) l;
  59                 if (temp_gid == gid) {
  60                         continue;
  61                 }
  62
  63                 if (num_gids + 1 > *grpcnt) {
  64                         num_gids++;
  65                         continue;
  66                 }
  67                 groups[num_gids++] = temp_gid;
  68         }
  69         free(grplist);
  70
  71         if (num_gids > *grpcnt) {
  72                 ret = -1;
  73         }
  74         *grpcnt = num_gids;
  75
  76         DEBUG(10, ("Found %d groups for user %s\n", *grpcnt, user));
  77
  78         return ret;
  79 }
  80
  81 #else /* HAVE_GETGRSET */
  82
  83 /*
  84   This is a *much* faster way of getting the list of groups for a user
  85   without changing the current supplementary group list. The old
  86   method used getgrent() which could take 20 minutes on a really big
  87   network with hundeds of thousands of groups and users. The new method
  88   takes a couple of seconds.
  89
  90   NOTE!! this function only works if it is called as root!
  91   */
  92
  93 static int getgrouplist_internals(const char *user, gid_t gid, gid_t *groups,
  94                                   int *grpcnt)
  95 {
  96         gid_t *gids_saved;
  97         int ret, ngrp_saved, num_gids;
  98
  99         if (non_root_mode()) {
 100                 *grpcnt = 0;
 101                 return 0;
 102         }
 103
 104         /* work out how many groups we need to save */
 105         ngrp_saved = getgroups(0, NULL);
 106         if (ngrp_saved == -1) {
 107                 /* this shouldn't happen */
 108                 return -1;
 109         }
 110
 111         gids_saved = SMB_MALLOC_ARRAY(gid_t, ngrp_saved+1);
 112         if (!gids_saved) {
 113                 errno = ENOMEM;
 114                 return -1;
 115         }
 116
 117         ngrp_saved = getgroups(ngrp_saved, gids_saved);
 118         if (ngrp_saved == -1) {
 119                 SAFE_FREE(gids_saved);
 120                 /* very strange! */
 121                 return -1;
 122         }
 123
 124         if (initgroups(user, gid) == -1) {
 125                 DEBUG(0, ("getgrouplist_internals: initgroups() failed!\n"));
 126                 SAFE_FREE(gids_saved);
 127                 return -1;
 128         }
 129
 130         /* this must be done to cope with systems that put the current egid in the
 131            return from getgroups() */
 132         save_re_gid();
 133         set_effective_gid(gid);
 134         samba_setgid(gid);
 135
 136         num_gids = getgroups(0, NULL);
 137         if (num_gids == -1) {
 138                 SAFE_FREE(gids_saved);
 139                 /* very strange! */
 140                 return -1;
 141         }
 142
 143         if (num_gids + 1 > *grpcnt) {
 144                 *grpcnt = num_gids + 1;
 145                 ret = -1;
 146         } else {
 147                 ret = getgroups(*grpcnt - 1, &groups[1]);
 148                 if (ret < 0) {
 149                         SAFE_FREE(gids_saved);
 150                         /* very strange! */
 151                         return -1;
 152                 }
 153                 groups[0] = gid;
 154                 *grpcnt = ret + 1;
 155         }
 156
 157         restore_re_gid();
 158
 159         if (sys_setgroups(gid, ngrp_saved, gids_saved) != 0) {
 160                 /* yikes! */
 161                 DEBUG(0,("ERROR: getgrouplist: failed to reset group list!\n"));
 162                 smb_panic("getgrouplist: failed to reset group list!");
 163         }
 164
 165         free(gids_saved);
 166         return ret;
 167 }
 168 #endif /* HAVE_GETGRSET */
 169 #endif /* HAVE_GETGROUPLIST */
 170
 171 static int sys_getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
 172 {
 173         int retval;
 174         bool winbind_env;
 175
 176         DEBUG(10,("sys_getgrouplist: user [%s]\n", user));
 177
 178         /* This is only ever called for Unix users, remote memberships are
 179          * always determined by the info3 coming back from auth3 or the
 180          * PAC. */
 181         winbind_env = winbind_env_set();
 182         (void)winbind_off();
 183
 184 #ifdef HAVE_GETGROUPLIST
 185         retval = getgrouplist(user, gid, groups, grpcnt);
 186 #else
 187 #ifdef HAVE_GETGRSET
 188         retval = getgrouplist_getgrset(user, gid, groups, grpcnt);
 189 #else
 190         become_root();
 191         retval = getgrouplist_internals(user, gid, groups, grpcnt);
 192         unbecome_root();
 193 #endif /* HAVE_GETGRSET */
 194 #endif /* HAVE_GETGROUPLIST */
 195
 196         /* allow winbindd lookups, but only if they were not already disabled */
 197         if (!winbind_env) {
 198                 (void)winbind_on();
 199         }
 200
 201         return retval;
 202 }
 203
 204 bool getgroups_unix_user(TALLOC_CTX *mem_ctx, const char *user,
 205                          gid_t primary_gid,
 206                          gid_t **ret_groups, uint32_t *p_ngroups)
 207 {
 208         int max_grp = MIN(128, groups_max());
 209         gid_t stack_groups[max_grp];
 210         uint32_t ngrp;
 211         gid_t *temp_groups = stack_groups;
 212         gid_t *to_free = NULL;
 213         gid_t *groups;
 214         int i;
 215
 216         if (sys_getgrouplist(user, primary_gid, temp_groups, &max_grp) == -1) {
 217                 to_free = talloc_array(mem_ctx, gid_t, max_grp);
 218                 if (!to_free) {
 219                         return False;
 220                 }
 221                 temp_groups = to_free;
 222
 223                 if (sys_getgrouplist(user, primary_gid,
 224                                      temp_groups, &max_grp) == -1) {
 225                         DEBUG(0, ("get_user_groups: failed to get the unix "
 226                                   "group list\n"));
 227                         TALLOC_FREE(to_free);
 228                         return False;
 229                 }
 230         }
 231
 232         ngrp = 0;
 233         groups = NULL;
 234
 235         /* Add in primary group first */
 236         if (!add_gid_to_array_unique(mem_ctx, primary_gid, &groups, &ngrp)) {
 237                 TALLOC_FREE(to_free);
 238                 return False;
 239         }
 240
 241         for (i=0; i<max_grp; i++) {
 242                 if (!add_gid_to_array_unique(mem_ctx, temp_groups[i],
 243                                         &groups, &ngrp)) {
 244                         TALLOC_FREE(to_free);
 245                         return False;
 246                 }
 247         }
 248
 249         *p_ngroups = ngrp;
 250         *ret_groups = groups;
 251         TALLOC_FREE(to_free);
 252         return True;
 253 }