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
  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 static bool do_group_checks(const char **name, const char **pattern)
  31 {
  32         if ((*name)[0] == '@') {
  33                 *pattern = "&+";
  34                 *name += 1;
  35                 return True;
  36         }
  37
  38         if (((*name)[0] == '+') && ((*name)[1] == '&')) {
  39                 *pattern = "+&";
  40                 *name += 2;
  41                 return True;
  42         }
  43
  44         if ((*name)[0] == '+') {
  45                 *pattern = "+";
  46                 *name += 1;
  47                 return True;
  48         }
  49
  50         if (((*name)[0] == '&') && ((*name)[1] == '+')) {
  51                 *pattern = "&+";
  52                 *name += 2;
  53                 return True;
  54         }
  55
  56         if ((*name)[0] == '&') {
  57                 *pattern = "&";
  58                 *name += 1;
  59                 return True;
  60         }
  61
  62         return False;
  63 }
  64
  65 static bool token_contains_name(TALLOC_CTX *mem_ctx,
  66                                 const char *username,
  67                                 const char *domain,
  68                                 const char *sharename,
  69                                 const struct nt_user_token *token,
  70                                 const char *name)
  71 {
  72         const char *prefix;
  73         DOM_SID sid;
  74         enum lsa_SidType type;
  75
  76         if (username != NULL) {
  77                 name = talloc_sub_basic(mem_ctx, username, domain, name);
  78         }
  79         if (sharename != NULL) {
  80                 name = talloc_string_sub(mem_ctx, name, "%S", sharename);
  81         }
  82
  83         if (name == NULL) {
  84                 /* This is too security sensitive, better panic than return a
  85                  * result that might be interpreted in a wrong way. */
  86                 smb_panic("substitutions failed");
  87         }
  88
  89         /* check to see is we already have a SID */
  90
  91         if ( string_to_sid( &sid, name ) ) {
  92                 DEBUG(5,("token_contains_name: Checking for SID [%s] in token\n", name));
  93                 return nt_token_check_sid( &sid, token );
  94         }
  95
  96         if (!do_group_checks(&name, &prefix)) {
  97                 if (!lookup_name_smbconf(mem_ctx, name, LOOKUP_NAME_ALL,
  98                                  NULL, NULL, &sid, &type)) {
  99                         DEBUG(5, ("lookup_name %s failed\n", name));
 100                         return False;
 101                 }
 102                 if (type != SID_NAME_USER) {
 103                         DEBUG(5, ("%s is a %s, expected a user\n",
 104                                   name, sid_type_lookup(type)));
 105                         return False;
 106                 }
 107                 return nt_token_check_sid(&sid, token);
 108         }
 109
 110         for (/* initialized above */ ; *prefix != '\0'; prefix++) {
 111                 if (*prefix == '+') {
 112                         if (!lookup_name_smbconf(mem_ctx, name,
 113                                          LOOKUP_NAME_ALL|LOOKUP_NAME_GROUP,
 114                                          NULL, NULL, &sid, &type)) {
 115                                 DEBUG(5, ("lookup_name %s failed\n", name));
 116                                 return False;
 117                         }
 118                         if ((type != SID_NAME_DOM_GRP) &&
 119                             (type != SID_NAME_ALIAS) &&
 120                             (type != SID_NAME_WKN_GRP)) {
 121                                 DEBUG(5, ("%s is a %s, expected a group\n",
 122                                           name, sid_type_lookup(type)));
 123                                 return False;
 124                         }
 125                         if (nt_token_check_sid(&sid, token)) {
 126                                 return True;
 127                         }
 128                         continue;
 129                 }
 130                 if (*prefix == '&') {
 131                         if (user_in_netgroup(username, name)) {
 132                                 return True;
 133                         }
 134                         continue;
 135                 }
 136                 smb_panic("got invalid prefix from do_groups_check");
 137         }
 138         return False;
 139 }
 140
 141 /*
 142  * Check whether a user is contained in the list provided.
 143  *
 144  * Please note that the user name and share names passed in here mainly for
 145  * the substitution routines that expand the parameter values, the decision
 146  * whether a user is in the list is done after a lookup_name on the expanded
 147  * parameter value, solely based on comparing the SIDs in token.
 148  *
 149  * The other use is the netgroup check when using @group or &group.
 150  */
 151
 152 bool token_contains_name_in_list(const char *username,
 153                                  const char *domain,
 154                                  const char *sharename,
 155                                  const struct nt_user_token *token,
 156                                  const char **list)
 157 {
 158         TALLOC_CTX *mem_ctx;
 159
 160         if (list == NULL) {
 161                 return False;
 162         }
 163
 164         if ( (mem_ctx = talloc_new(NULL)) == NULL ) {
 165                 smb_panic("talloc_new failed");
 166         }
 167
 168         while (*list != NULL) {
 169                 if (token_contains_name(mem_ctx, username, domain, sharename,
 170                                         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, const char *domain,
 195                    const struct nt_user_token *token, int snum)
 196 {
 197         if (lp_invalid_users(snum) != NULL) {
 198                 if (token_contains_name_in_list(username, domain,
 199                                                 lp_servicename(snum),
 200                                                 token,
 201                                                 lp_invalid_users(snum))) {
 202                         DEBUG(10, ("User %s in 'invalid users'\n", username));
 203                         return False;
 204                 }
 205         }
 206
 207         if (lp_valid_users(snum) != NULL) {
 208                 if (!token_contains_name_in_list(username, domain,
 209                                                  lp_servicename(snum), token,
 210                                                  lp_valid_users(snum))) {
 211                         DEBUG(10, ("User %s not in 'valid users'\n",
 212                                    username));
 213                         return False;
 214                 }
 215         }
 216
 217         if (lp_onlyuser(snum)) {
 218                 const char *list[2];
 219                 list[0] = lp_username(snum);
 220                 list[1] = NULL;
 221                 if ((list[0] == NULL) || (*list[0] == '\0')) {
 222                         DEBUG(0, ("'only user = yes' and no 'username ='\n"));
 223                         return False;
 224                 }
 225                 if (!token_contains_name_in_list(NULL, domain,
 226                                                  lp_servicename(snum),
 227                                                  token, list)) {
 228                         DEBUG(10, ("%s != 'username'\n", username));
 229                         return False;
 230                 }
 231         }
 232
 233         DEBUG(10, ("user_ok_token: share %s is ok for unix user %s\n",
 234                    lp_servicename(snum), username));
 235
 236         return True;
 237 }
 238
 239 /*
 240  * Check whether the user described by "token" is restricted to read-only
 241  * access on share snum.
 242  *
 243  * This looks at "invalid users", "valid users" and "only user/username"
 244  *
 245  * Please note that the user name and share names passed in here mainly for
 246  * the substitution routines that expand the parameter values, the decision
 247  * whether a user is in the list is done after a lookup_name on the expanded
 248  * parameter value, solely based on comparing the SIDs in token.
 249  *
 250  * The other use is the netgroup check when using @group or &group.
 251  */
 252
 253 bool is_share_read_only_for_token(const char *username,
 254                                   const char *domain,
 255                                   const struct nt_user_token *token,
 256                                   connection_struct *conn)
 257 {
 258         int snum = SNUM(conn);
 259         bool result = conn->read_only;
 260
 261         if (lp_readlist(snum) != NULL) {
 262                 if (token_contains_name_in_list(username, domain,
 263                                                 lp_servicename(snum), token,
 264                                                 lp_readlist(snum))) {
 265                         result = True;
 266                 }
 267         }
 268
 269         if (lp_writelist(snum) != NULL) {
 270                 if (token_contains_name_in_list(username, domain,
 271                                                 lp_servicename(snum), token,
 272                                                 lp_writelist(snum))) {
 273                         result = False;
 274                 }
 275         }
 276
 277         DEBUG(10,("is_share_read_only_for_user: share %s is %s for unix user "
 278                   "%s\n", lp_servicename(snum),
 279                   result ? "read-only" : "read-write", username));
 280
 281         return result;
 282 }