source/smbd/share_access.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Check access based on valid users, read list and friends
   4    Copyright (C) Volker Lendecke 2005
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21
  22 /*
  23  * No prefix means direct username
  24  * @name means netgroup first, then unix group
  25  * &name means netgroup
  26  * +name means unix group
  27  * + and & may be combined
  28  */
  29
  30 extern userdom_struct current_user_info;
  31
  32 static bool do_group_checks(const char **name, const char **pattern)
  33 {
  34         if ((*name)[0] == '@') {
  35                 *pattern = "&+";
  36                 *name += 1;
  37                 return True;
  38         }
  39
  40         if (((*name)[0] == '+') && ((*name)[1] == '&')) {
  41                 *pattern = "+&";
  42                 *name += 2;
  43                 return True;
  44         }
  45
  46         if ((*name)[0] == '+') {
  47                 *pattern = "+";
  48                 *name += 1;
  49                 return True;
  50         }
  51
  52         if (((*name)[0] == '&') && ((*name)[1] == '+')) {
  53                 *pattern = "&+";
  54                 *name += 2;
  55                 return True;
  56         }
  57
  58         if ((*name)[0] == '&') {
  59                 *pattern = "&";
  60                 *name += 1;
  61                 return True;
  62         }
  63
  64         return False;
  65 }
  66
  67 static bool token_contains_name(TALLOC_CTX *mem_ctx,
  68                                 const char *username,
  69                                 const char *sharename,
  70                                 const struct nt_user_token *token,
  71                                 const char *name)
  72 {
  73         const char *prefix;
  74         DOM_SID sid;
  75         enum lsa_SidType type;
  76
  77         if (username != NULL) {
  78                 name = talloc_sub_basic(mem_ctx, username,
  79                                         current_user_info.domain, name);
  80         }
  81         if (sharename != NULL) {
  82                 name = talloc_string_sub(mem_ctx, name, "%S", sharename);
  83         }
  84
  85         if (name == NULL) {
  86                 /* This is too security sensitive, better panic than return a
  87                  * result that might be interpreted in a wrong way. */
  88                 smb_panic("substitutions failed");
  89         }
  90
  91         /* check to see is we already have a SID */
  92
  93         if ( string_to_sid( &sid, name ) ) {
  94                 DEBUG(5,("token_contains_name: Checking for SID [%s] in token\n", name));
  95                 return nt_token_check_sid( &sid, token );
  96         }
  97
  98         if (!do_group_checks(&name, &prefix)) {
  99                 if (!lookup_name_smbconf(mem_ctx, name, LOOKUP_NAME_ALL,
 100                                  NULL, NULL, &sid, &type)) {
 101                         DEBUG(5, ("lookup_name %s failed\n", name));
 102                         return False;
 103                 }
 104                 if (type != SID_NAME_USER) {
 105                         DEBUG(5, ("%s is a %s, expected a user\n",
 106                                   name, sid_type_lookup(type)));
 107                         return False;
 108                 }
 109                 return nt_token_check_sid(&sid, token);
 110         }
 111
 112         for (/* initialized above */ ; *prefix != '\0'; prefix++) {
 113                 if (*prefix == '+') {
 114                         if (!lookup_name_smbconf(mem_ctx, name,
 115                                          LOOKUP_NAME_ALL|LOOKUP_NAME_GROUP,
 116                                          NULL, NULL, &sid, &type)) {
 117                                 DEBUG(5, ("lookup_name %s failed\n", name));
 118                                 return False;
 119                         }
 120                         if ((type != SID_NAME_DOM_GRP) &&
 121                             (type != SID_NAME_ALIAS) &&
 122                             (type != SID_NAME_WKN_GRP)) {
 123                                 DEBUG(5, ("%s is a %s, expected a group\n",
 124                                           name, sid_type_lookup(type)));
 125                                 return False;
 126                         }
 127                         if (nt_token_check_sid(&sid, token)) {
 128                                 return True;
 129                         }
 130                         continue;
 131                 }
 132                 if (*prefix == '&') {
 133                         if (user_in_netgroup(username, name)) {
 134                                 return True;
 135                         }
 136                         continue;
 137                 }
 138                 smb_panic("got invalid prefix from do_groups_check");
 139         }
 140         return False;
 141 }
 142
 143 /*
 144  * Check whether a user is contained in the list provided.
 145  *
 146  * Please note that the user name and share names passed in here mainly for
 147  * the substitution routines that expand the parameter values, the decision
 148  * whether a user is in the list is done after a lookup_name on the expanded
 149  * parameter value, solely based on comparing the SIDs in token.
 150  *
 151  * The other use is the netgroup check when using @group or &group.
 152  */
 153
 154 bool token_contains_name_in_list(const char *username,
 155                                  const char *sharename,
 156                                  const struct nt_user_token *token,
 157                                  const char **list)
 158 {
 159         TALLOC_CTX *mem_ctx;
 160
 161         if (list == NULL) {
 162                 return False;
 163         }
 164
 165         if ( (mem_ctx = talloc_new(NULL)) == NULL ) {
 166                 smb_panic("talloc_new failed");
 167         }
 168
 169         while (*list != NULL) {
 170                 if (token_contains_name(mem_ctx, username, sharename,token, *list)) {
 171                         TALLOC_FREE(mem_ctx);
 172                         return True;
 173                 }
 174                 list += 1;
 175         }
 176
 177         TALLOC_FREE(mem_ctx);
 178         return False;
 179 }
 180
 181 /*
 182  * Check whether the user described by "token" has access to share snum.
 183  *
 184  * This looks at "invalid users", "valid users" and "only user/username"
 185  *
 186  * Please note that the user name and share names passed in here mainly for
 187  * the substitution routines that expand the parameter values, the decision
 188  * whether a user is in the list is done after a lookup_name on the expanded
 189  * parameter value, solely based on comparing the SIDs in token.
 190  *
 191  * The other use is the netgroup check when using @group or &group.
 192  */
 193
 194 bool user_ok_token(const char *username, struct nt_user_token *token, int snum)
 195 {
 196         if (lp_invalid_users(snum) != NULL) {
 197                 if (token_contains_name_in_list(username, lp_servicename(snum),
 198                                                 token,
 199                                                 lp_invalid_users(snum))) {
 200                         DEBUG(10, ("User %s in 'invalid users'\n", username));
 201                         return False;
 202                 }
 203         }
 204
 205         if (lp_valid_users(snum) != NULL) {
 206                 if (!token_contains_name_in_list(username,
 207                                                  lp_servicename(snum), token,
 208                                                  lp_valid_users(snum))) {
 209                         DEBUG(10, ("User %s not in 'valid users'\n",
 210                                    username));
 211                         return False;
 212                 }
 213         }
 214
 215         if (lp_onlyuser(snum)) {
 216                 const char *list[2];
 217                 list[0] = lp_username(snum);
 218                 list[1] = NULL;
 219                 if ((list[0] == NULL) || (*list[0] == '\0')) {
 220                         DEBUG(0, ("'only user = yes' and no 'username ='\n"));
 221                         return False;
 222                 }
 223                 if (!token_contains_name_in_list(NULL, lp_servicename(snum),
 224                                                  token, list)) {
 225                         DEBUG(10, ("%s != 'username'\n", username));
 226                         return False;
 227                 }
 228         }
 229
 230         DEBUG(10, ("user_ok_token: share %s is ok for unix user %s\n",
 231                    lp_servicename(snum), username));
 232
 233         return True;
 234 }
 235
 236 /*
 237  * Check whether the user described by "token" is restricted to read-only
 238  * access on share snum.
 239  *
 240  * This looks at "invalid users", "valid users" and "only user/username"
 241  *
 242  * Please note that the user name and share names passed in here mainly for
 243  * the substitution routines that expand the parameter values, the decision
 244  * whether a user is in the list is done after a lookup_name on the expanded
 245  * parameter value, solely based on comparing the SIDs in token.
 246  *
 247  * The other use is the netgroup check when using @group or &group.
 248  */
 249
 250 bool is_share_read_only_for_token(const char *username,
 251                                   struct nt_user_token *token, int snum)
 252 {
 253         bool result = lp_readonly(snum);
 254
 255         if (lp_readlist(snum) != NULL) {
 256                 if (token_contains_name_in_list(username,
 257                                                 lp_servicename(snum), token,
 258                                                 lp_readlist(snum))) {
 259                         result = True;
 260                 }
 261         }
 262
 263         if (lp_writelist(snum) != NULL) {
 264                 if (token_contains_name_in_list(username,
 265                                                 lp_servicename(snum), token,
 266                                                 lp_writelist(snum))) {
 267                         result = False;
 268                 }
 269         }
 270
 271         DEBUG(10,("is_share_read_only_for_user: share %s is %s for unix user "
 272                   "%s\n", lp_servicename(snum),
 273                   result ? "read-only" : "read-write", username));
 274
 275         return result;
 276 }