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/smbd.h"
  22 #include "smbd/globals.h"
  23 #include "../libcli/security/security.h"
  24 #include "passdb/lookup_sid.h"
  25 #include "auth.h"
  26
  27 /*
  28  * No prefix means direct username
  29  * @name means netgroup first, then unix group
  30  * &name means netgroup
  31  * +name means unix group
  32  * + and & may be combined
  33  */
  34
  35 static bool do_group_checks(const char **name, const char **pattern)
  36 {
  37         if ((*name)[0] == '@') {
  38                 *pattern = "&+";
  39                 *name += 1;
  40                 return True;
  41         }
  42
  43         if (((*name)[0] == '+') && ((*name)[1] == '&')) {
  44                 *pattern = "+&";
  45                 *name += 2;
  46                 return True;
  47         }
  48
  49         if ((*name)[0] == '+') {
  50                 *pattern = "+";
  51                 *name += 1;
  52                 return True;
  53         }
  54
  55         if (((*name)[0] == '&') && ((*name)[1] == '+')) {
  56                 *pattern = "&+";
  57                 *name += 2;
  58                 return True;
  59         }
  60
  61         if ((*name)[0] == '&') {
  62                 *pattern = "&";
  63                 *name += 1;
  64                 return True;
  65         }
  66
  67         return False;
  68 }
  69
  70 static bool token_contains_name(TALLOC_CTX *mem_ctx,
  71                                 const char *username,
  72                                 const char *domain,
  73                                 const char *sharename,
  74                                 const struct security_token *token,
  75                                 const char *name)
  76 {
  77         const char *prefix;
  78         struct dom_sid sid;
  79         enum lsa_SidType type;
  80
  81         if (username != NULL) {
  82                 name = talloc_sub_basic(mem_ctx, username, domain, name);
  83         }
  84         if (sharename != NULL) {
  85                 name = talloc_string_sub(mem_ctx, name, "%S", sharename);
  86         }
  87
  88         if (name == NULL) {
  89                 /* This is too security sensitive, better panic than return a
  90                  * result that might be interpreted in a wrong way. */
  91                 smb_panic("substitutions failed");
  92         }
  93
  94         if ( string_to_sid( &sid, name ) ) {
  95                 DEBUG(5,("token_contains_name: Checking for SID [%s] in token\n", name));
  96                 return nt_token_check_sid( &sid, token );
  97         }
  98
  99         if (!do_group_checks(&name, &prefix)) {
 100                 if (!lookup_name_smbconf(mem_ctx, name, LOOKUP_NAME_ALL,
 101                                  NULL, NULL, &sid, &type)) {
 102                         DEBUG(5, ("lookup_name %s failed\n", name));
 103                         return False;
 104                 }
 105                 if (type != SID_NAME_USER) {
 106                         DEBUG(5, ("%s is a %s, expected a user\n",
 107                                   name, sid_type_lookup(type)));
 108                         return False;
 109                 }
 110                 return nt_token_check_sid(&sid, token);
 111         }
 112
 113         for (/* initialized above */ ; *prefix != '\0'; prefix++) {
 114                 if (*prefix == '+') {
 115                         if (!lookup_name_smbconf(mem_ctx, name,
 116                                          LOOKUP_NAME_ALL|LOOKUP_NAME_GROUP,
 117                                          NULL, NULL, &sid, &type)) {
 118                                 DEBUG(5, ("lookup_name %s failed\n", name));
 119                                 return False;
 120                         }
 121                         if ((type != SID_NAME_DOM_GRP) &&
 122                             (type != SID_NAME_ALIAS) &&
 123                             (type != SID_NAME_WKN_GRP)) {
 124                                 DEBUG(5, ("%s is a %s, expected a group\n",
 125                                           name, sid_type_lookup(type)));
 126                                 return False;
 127                         }
 128                         if (nt_token_check_sid(&sid, token)) {
 129                                 return True;
 130                         }
 131                         continue;
 132                 }
 133                 if (*prefix == '&') {
 134                         if (username) {
 135                                 if (user_in_netgroup(mem_ctx, username, name)) {
 136                                         return True;
 137                                 }
 138                         }
 139                         continue;
 140                 }
 141                 smb_panic("got invalid prefix from do_groups_check");
 142         }
 143         return False;
 144 }
 145
 146 /*
 147  * Check whether a user is contained in the list provided.
 148  *
 149  * Please note that the user name and share names passed in here mainly for
 150  * the substitution routines that expand the parameter values, the decision
 151  * whether a user is in the list is done after a lookup_name on the expanded
 152  * parameter value, solely based on comparing the SIDs in token.
 153  *
 154  * The other use is the netgroup check when using @group or &group.
 155  */
 156
 157 bool token_contains_name_in_list(const char *username,
 158                                  const char *domain,
 159                                  const char *sharename,
 160                                  const struct security_token *token,
 161                                  const char **list)
 162 {
 163         if (list == NULL) {
 164                 return False;
 165         }
 166         while (*list != NULL) {
 167                 TALLOC_CTX *frame = talloc_stackframe();
 168                 bool ret;
 169
 170                 ret = token_contains_name(frame, username, domain, sharename,
 171                                           token, *list);
 172                 TALLOC_FREE(frame);
 173                 if (ret) {
 174                         return true;
 175                 }
 176                 list += 1;
 177         }
 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" and "valid users".
 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 security_token *token, int snum)
 196 {
 197         if (lp_invalid_users(snum) != NULL) {
 198                 if (token_contains_name_in_list(username, domain,
 199                                                 lp_servicename(talloc_tos(), 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(talloc_tos(), snum),
 210                                                  token,
 211                                                  lp_valid_users(snum))) {
 212                         DEBUG(10, ("User %s not in 'valid users'\n",
 213                                    username));
 214                         return False;
 215                 }
 216         }
 217
 218         DEBUG(10, ("user_ok_token: share %s is ok for unix user %s\n",
 219                    lp_servicename(talloc_tos(), snum), username));
 220
 221         return True;
 222 }
 223
 224 /*
 225  * Check whether the user described by "token" is restricted to read-only
 226  * access on share snum.
 227  *
 228  * This looks at "read list", "write list" and "read only".
 229  *
 230  * Please note that the user name and share names passed in here mainly for
 231  * the substitution routines that expand the parameter values, the decision
 232  * whether a user is in the list is done after a lookup_name on the expanded
 233  * parameter value, solely based on comparing the SIDs in token.
 234  *
 235  * The other use is the netgroup check when using @group or &group.
 236  */
 237
 238 bool is_share_read_only_for_token(const char *username,
 239                                   const char *domain,
 240                                   const struct security_token *token,
 241                                   connection_struct *conn)
 242 {
 243         int snum = SNUM(conn);
 244         bool result = conn->read_only;
 245
 246         if (lp_read_list(snum) != NULL) {
 247                 if (token_contains_name_in_list(username, domain,
 248                                                 lp_servicename(talloc_tos(), snum),
 249                                                 token,
 250                                                 lp_read_list(snum))) {
 251                         result = True;
 252                 }
 253         }
 254
 255         if (lp_write_list(snum) != NULL) {
 256                 if (token_contains_name_in_list(username, domain,
 257                                                 lp_servicename(talloc_tos(), snum),
 258                                                 token,
 259                                                 lp_write_list(snum))) {
 260                         result = False;
 261                 }
 262         }
 263
 264         DEBUG(10,("is_share_read_only_for_user: share %s is %s for unix user "
 265                   "%s\n", lp_servicename(talloc_tos(), snum),
 266                   result ? "read-only" : "read-write", username));
 267
 268         return result;
 269 }