source3/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 #include "smbd/globals.h"
  22 #include "../libcli/security/security.h"
  23
  24 /*
  25  * No prefix means direct username
  26  * @name means netgroup first, then unix group
  27  * &name means netgroup
  28  * +name means unix group
  29  * + and & may be combined
  30  */
  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 *domain,
  70                                 const char *sharename,
  71                                 const struct security_token *token,
  72                                 const char *name)
  73 {
  74         const char *prefix;
  75         struct dom_sid sid;
  76         enum lsa_SidType type;
  77
  78         if (username != NULL) {
  79                 name = talloc_sub_basic(mem_ctx, username, 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 (username) {
 134                                 if (user_in_netgroup(username, name)) {
 135                                         return True;
 136                                 }
 137                         }
 138                         continue;
 139                 }
 140                 smb_panic("got invalid prefix from do_groups_check");
 141         }
 142         return False;
 143 }
 144
 145 /*
 146  * Check whether a user is contained in the list provided.
 147  *
 148  * Please note that the user name and share names passed in here mainly for
 149  * the substitution routines that expand the parameter values, the decision
 150  * whether a user is in the list is done after a lookup_name on the expanded
 151  * parameter value, solely based on comparing the SIDs in token.
 152  *
 153  * The other use is the netgroup check when using @group or &group.
 154  */
 155
 156 bool token_contains_name_in_list(const char *username,
 157                                  const char *domain,
 158                                  const char *sharename,
 159                                  const struct security_token *token,
 160                                  const char **list)
 161 {
 162         TALLOC_CTX *mem_ctx;
 163
 164         if (list == NULL) {
 165                 return False;
 166         }
 167
 168         if ( (mem_ctx = talloc_new(NULL)) == NULL ) {
 169                 smb_panic("talloc_new failed");
 170         }
 171
 172         while (*list != NULL) {
 173                 if (token_contains_name(mem_ctx, username, domain, sharename,
 174                                         token, *list)) {
 175                         TALLOC_FREE(mem_ctx);
 176                         return True;
 177                 }
 178                 list += 1;
 179         }
 180
 181         TALLOC_FREE(mem_ctx);
 182         return False;
 183 }
 184
 185 /*
 186  * Check whether the user described by "token" has access to share snum.
 187  *
 188  * This looks at "invalid users", "valid users" and "only user/username"
 189  *
 190  * Please note that the user name and share names passed in here mainly for
 191  * the substitution routines that expand the parameter values, the decision
 192  * whether a user is in the list is done after a lookup_name on the expanded
 193  * parameter value, solely based on comparing the SIDs in token.
 194  *
 195  * The other use is the netgroup check when using @group or &group.
 196  */
 197
 198 bool user_ok_token(const char *username, const char *domain,
 199                    const struct security_token *token, int snum)
 200 {
 201         if (lp_invalid_users(snum) != NULL) {
 202                 if (token_contains_name_in_list(username, domain,
 203                                                 lp_servicename(snum),
 204                                                 token,
 205                                                 lp_invalid_users(snum))) {
 206                         DEBUG(10, ("User %s in 'invalid users'\n", username));
 207                         return False;
 208                 }
 209         }
 210
 211         if (lp_valid_users(snum) != NULL) {
 212                 if (!token_contains_name_in_list(username, domain,
 213                                                  lp_servicename(snum), token,
 214                                                  lp_valid_users(snum))) {
 215                         DEBUG(10, ("User %s not in 'valid users'\n",
 216                                    username));
 217                         return False;
 218                 }
 219         }
 220
 221         if (lp_onlyuser(snum)) {
 222                 const char *list[2];
 223                 list[0] = lp_username(snum);
 224                 list[1] = NULL;
 225                 if ((list[0] == NULL) || (*list[0] == '\0')) {
 226                         DEBUG(0, ("'only user = yes' and no 'username ='\n"));
 227                         return False;
 228                 }
 229                 if (!token_contains_name_in_list(NULL, domain,
 230                                                  lp_servicename(snum),
 231                                                  token, list)) {
 232                         DEBUG(10, ("%s != 'username'\n", username));
 233                         return False;
 234                 }
 235         }
 236
 237         DEBUG(10, ("user_ok_token: share %s is ok for unix user %s\n",
 238                    lp_servicename(snum), username));
 239
 240         return True;
 241 }
 242
 243 /*
 244  * Check whether the user described by "token" is restricted to read-only
 245  * access on share snum.
 246  *
 247  * This looks at "invalid users", "valid users" and "only user/username"
 248  *
 249  * Please note that the user name and share names passed in here mainly for
 250  * the substitution routines that expand the parameter values, the decision
 251  * whether a user is in the list is done after a lookup_name on the expanded
 252  * parameter value, solely based on comparing the SIDs in token.
 253  *
 254  * The other use is the netgroup check when using @group or &group.
 255  */
 256
 257 bool is_share_read_only_for_token(const char *username,
 258                                   const char *domain,
 259                                   const struct security_token *token,
 260                                   connection_struct *conn)
 261 {
 262         int snum = SNUM(conn);
 263         bool result = conn->read_only;
 264
 265         if (lp_readlist(snum) != NULL) {
 266                 if (token_contains_name_in_list(username, domain,
 267                                                 lp_servicename(snum), token,
 268                                                 lp_readlist(snum))) {
 269                         result = True;
 270                 }
 271         }
 272
 273         if (lp_writelist(snum) != NULL) {
 274                 if (token_contains_name_in_list(username, domain,
 275                                                 lp_servicename(snum), token,
 276                                                 lp_writelist(snum))) {
 277                         result = False;
 278                 }
 279         }
 280
 281         DEBUG(10,("is_share_read_only_for_user: share %s is %s for unix user "
 282                   "%s\n", lp_servicename(snum),
 283                   result ? "read-only" : "read-write", username));
 284
 285         return result;
 286 }