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                 size_t domain_len = strlen(domain);
  83
  84                 /* Check if username starts with domain name */
  85                 if (domain_len > 0) {
  86                         const char *sep = lp_winbind_separator();
  87                         int cmp = strncasecmp_m(username, domain, domain_len);
  88                         if (cmp == 0 && sep[0] == username[domain_len]) {
  89                                 /* Move after the winbind separator */
  90                                 domain_len += 1;
  91                         } else {
  92                                 domain_len = 0;
  93                         }
  94                 }
  95                 name = talloc_sub_basic(mem_ctx,
  96                                         username + domain_len,
  97                                         domain,
  98                                         name);
  99         }
 100         if (sharename != NULL) {
 101                 name = talloc_string_sub(mem_ctx, name, "%S", sharename);
 102         }
 103
 104         if (name == NULL) {
 105                 /* This is too security sensitive, better panic than return a
 106                  * result that might be interpreted in a wrong way. */
 107                 smb_panic("substitutions failed");
 108         }
 109
 110         if ( string_to_sid( &sid, name ) ) {
 111                 DEBUG(5,("token_contains_name: Checking for SID [%s] in token\n", name));
 112                 return nt_token_check_sid( &sid, token );
 113         }
 114
 115         if (!do_group_checks(&name, &prefix)) {
 116                 if (!lookup_name_smbconf(mem_ctx, name, LOOKUP_NAME_ALL,
 117                                  NULL, NULL, &sid, &type)) {
 118                         DEBUG(5, ("lookup_name %s failed\n", name));
 119                         return False;
 120                 }
 121                 if (type != SID_NAME_USER) {
 122                         DEBUG(5, ("%s is a %s, expected a user\n",
 123                                   name, sid_type_lookup(type)));
 124                         return False;
 125                 }
 126                 return nt_token_check_sid(&sid, token);
 127         }
 128
 129         for (/* initialized above */ ; *prefix != '\0'; prefix++) {
 130                 if (*prefix == '+') {
 131                         if (!lookup_name_smbconf(mem_ctx, name,
 132                                          LOOKUP_NAME_ALL|LOOKUP_NAME_GROUP,
 133                                          NULL, NULL, &sid, &type)) {
 134                                 DEBUG(5, ("lookup_name %s failed\n", name));
 135                                 return False;
 136                         }
 137                         if ((type != SID_NAME_DOM_GRP) &&
 138                             (type != SID_NAME_ALIAS) &&
 139                             (type != SID_NAME_WKN_GRP)) {
 140                                 DEBUG(5, ("%s is a %s, expected a group\n",
 141                                           name, sid_type_lookup(type)));
 142                                 return False;
 143                         }
 144                         if (nt_token_check_sid(&sid, token)) {
 145                                 return True;
 146                         }
 147                         continue;
 148                 }
 149                 if (*prefix == '&') {
 150                         if (username) {
 151                                 if (user_in_netgroup(mem_ctx, username, name)) {
 152                                         return True;
 153                                 }
 154                         }
 155                         continue;
 156                 }
 157                 smb_panic("got invalid prefix from do_groups_check");
 158         }
 159         return False;
 160 }
 161
 162 /*
 163  * Check whether a user is contained in the list provided.
 164  *
 165  * Please note that the user name and share names passed in here mainly for
 166  * the substitution routines that expand the parameter values, the decision
 167  * whether a user is in the list is done after a lookup_name on the expanded
 168  * parameter value, solely based on comparing the SIDs in token.
 169  *
 170  * The other use is the netgroup check when using @group or &group.
 171  */
 172
 173 bool token_contains_name_in_list(const char *username,
 174                                  const char *domain,
 175                                  const char *sharename,
 176                                  const struct security_token *token,
 177                                  const char **list)
 178 {
 179         if (list == NULL) {
 180                 return False;
 181         }
 182         while (*list != NULL) {
 183                 TALLOC_CTX *frame = talloc_stackframe();
 184                 bool ret;
 185
 186                 ret = token_contains_name(frame, username, domain, sharename,
 187                                           token, *list);
 188                 TALLOC_FREE(frame);
 189                 if (ret) {
 190                         return true;
 191                 }
 192                 list += 1;
 193         }
 194         return False;
 195 }
 196
 197 /*
 198  * Check whether the user described by "token" has access to share snum.
 199  *
 200  * This looks at "invalid users" and "valid users".
 201  *
 202  * Please note that the user name and share names passed in here mainly for
 203  * the substitution routines that expand the parameter values, the decision
 204  * whether a user is in the list is done after a lookup_name on the expanded
 205  * parameter value, solely based on comparing the SIDs in token.
 206  *
 207  * The other use is the netgroup check when using @group or &group.
 208  */
 209
 210 bool user_ok_token(const char *username, const char *domain,
 211                    const struct security_token *token, int snum)
 212 {
 213         const struct loadparm_substitution *lp_sub =
 214                 loadparm_s3_global_substitution();
 215
 216         if (lp_invalid_users(snum) != NULL) {
 217                 if (token_contains_name_in_list(username, domain,
 218                                                 lp_servicename(talloc_tos(), lp_sub, snum),
 219                                                 token,
 220                                                 lp_invalid_users(snum))) {
 221                         DEBUG(10, ("User %s in 'invalid users'\n", username));
 222                         return False;
 223                 }
 224         }
 225
 226         if (lp_valid_users(snum) != NULL) {
 227                 if (!token_contains_name_in_list(username, domain,
 228                                                  lp_servicename(talloc_tos(), lp_sub, snum),
 229                                                  token,
 230                                                  lp_valid_users(snum))) {
 231                         DEBUG(10, ("User %s not in 'valid users'\n",
 232                                    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(talloc_tos(), lp_sub, 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 "read list", "write list" and "read only".
 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         const struct loadparm_substitution *lp_sub =
 263                 loadparm_s3_global_substitution();
 264         int snum = SNUM(conn);
 265         bool result = conn->read_only;
 266
 267         if (lp_read_list(snum) != NULL) {
 268                 if (token_contains_name_in_list(username, domain,
 269                                                 lp_servicename(talloc_tos(), lp_sub, snum),
 270                                                 token,
 271                                                 lp_read_list(snum))) {
 272                         result = True;
 273                 }
 274         }
 275
 276         if (lp_write_list(snum) != NULL) {
 277                 if (token_contains_name_in_list(username, domain,
 278                                                 lp_servicename(talloc_tos(), lp_sub, snum),
 279                                                 token,
 280                                                 lp_write_list(snum))) {
 281                         result = False;
 282                 }
 283         }
 284
 285         DEBUG(10,("is_share_read_only_for_user: share %s is %s for unix user "
 286                   "%s\n", lp_servicename(talloc_tos(), lp_sub, snum),
 287                   result ? "read-only" : "read-write", username));
 288
 289         return result;
 290 }