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 #include "passdb/lookup_sid.h"
  24
  25 /*
  26  * No prefix means direct username
  27  * @name means netgroup first, then unix group
  28  * &name means netgroup
  29  * +name means unix group
  30  * + and & may be combined
  31  */
  32
  33 static bool do_group_checks(const char **name, const char **pattern)
  34 {
  35         if ((*name)[0] == '@') {
  36                 *pattern = "&+";
  37                 *name += 1;
  38                 return True;
  39         }
  40
  41         if (((*name)[0] == '+') && ((*name)[1] == '&')) {
  42                 *pattern = "+&";
  43                 *name += 2;
  44                 return True;
  45         }
  46
  47         if ((*name)[0] == '+') {
  48                 *pattern = "+";
  49                 *name += 1;
  50                 return True;
  51         }
  52
  53         if (((*name)[0] == '&') && ((*name)[1] == '+')) {
  54                 *pattern = "&+";
  55                 *name += 2;
  56                 return True;
  57         }
  58
  59         if ((*name)[0] == '&') {
  60                 *pattern = "&";
  61                 *name += 1;
  62                 return True;
  63         }
  64
  65         return False;
  66 }
  67
  68 static bool token_contains_name(TALLOC_CTX *mem_ctx,
  69                                 const char *username,
  70                                 const char *domain,
  71                                 const char *sharename,
  72                                 const struct security_token *token,
  73                                 const char *name)
  74 {
  75         const char *prefix;
  76         struct dom_sid sid;
  77         enum lsa_SidType type;
  78
  79         if (username != NULL) {
  80                 name = talloc_sub_basic(mem_ctx, username, domain, name);
  81         }
  82         if (sharename != NULL) {
  83                 name = talloc_string_sub(mem_ctx, name, "%S", sharename);
  84         }
  85
  86         if (name == NULL) {
  87                 /* This is too security sensitive, better panic than return a
  88                  * result that might be interpreted in a wrong way. */
  89                 smb_panic("substitutions failed");
  90         }
  91
  92         /* check to see is we already have a SID */
  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         TALLOC_CTX *mem_ctx;
 164
 165         if (list == NULL) {
 166                 return False;
 167         }
 168
 169         if ( (mem_ctx = talloc_new(NULL)) == NULL ) {
 170                 smb_panic("talloc_new failed");
 171         }
 172
 173         while (*list != NULL) {
 174                 if (token_contains_name(mem_ctx, username, domain, sharename,
 175                                         token, *list)) {
 176                         TALLOC_FREE(mem_ctx);
 177                         return True;
 178                 }
 179                 list += 1;
 180         }
 181
 182         TALLOC_FREE(mem_ctx);
 183         return False;
 184 }
 185
 186 /*
 187  * Check whether the user described by "token" has access to share snum.
 188  *
 189  * This looks at "invalid users", "valid users" and "only user/username"
 190  *
 191  * Please note that the user name and share names passed in here mainly for
 192  * the substitution routines that expand the parameter values, the decision
 193  * whether a user is in the list is done after a lookup_name on the expanded
 194  * parameter value, solely based on comparing the SIDs in token.
 195  *
 196  * The other use is the netgroup check when using @group or &group.
 197  */
 198
 199 bool user_ok_token(const char *username, const char *domain,
 200                    const struct security_token *token, int snum)
 201 {
 202         if (lp_invalid_users(snum) != NULL) {
 203                 if (token_contains_name_in_list(username, domain,
 204                                                 lp_servicename(snum),
 205                                                 token,
 206                                                 lp_invalid_users(snum))) {
 207                         DEBUG(10, ("User %s in 'invalid users'\n", username));
 208                         return False;
 209                 }
 210         }
 211
 212         if (lp_valid_users(snum) != NULL) {
 213                 if (!token_contains_name_in_list(username, domain,
 214                                                  lp_servicename(snum), token,
 215                                                  lp_valid_users(snum))) {
 216                         DEBUG(10, ("User %s not in 'valid users'\n",
 217                                    username));
 218                         return False;
 219                 }
 220         }
 221
 222         if (lp_onlyuser(snum)) {
 223                 const char *list[2];
 224                 list[0] = lp_username(snum);
 225                 list[1] = NULL;
 226                 if ((list[0] == NULL) || (*list[0] == '\0')) {
 227                         DEBUG(0, ("'only user = yes' and no 'username ='\n"));
 228                         return False;
 229                 }
 230                 if (!token_contains_name_in_list(NULL, domain,
 231                                                  lp_servicename(snum),
 232                                                  token, list)) {
 233                         DEBUG(10, ("%s != 'username'\n", username));
 234                         return False;
 235                 }
 236         }
 237
 238         DEBUG(10, ("user_ok_token: share %s is ok for unix user %s\n",
 239                    lp_servicename(snum), username));
 240
 241         return True;
 242 }
 243
 244 /*
 245  * Check whether the user described by "token" is restricted to read-only
 246  * access on share snum.
 247  *
 248  * This looks at "invalid users", "valid users" and "only user/username"
 249  *
 250  * Please note that the user name and share names passed in here mainly for
 251  * the substitution routines that expand the parameter values, the decision
 252  * whether a user is in the list is done after a lookup_name on the expanded
 253  * parameter value, solely based on comparing the SIDs in token.
 254  *
 255  * The other use is the netgroup check when using @group or &group.
 256  */
 257
 258 bool is_share_read_only_for_token(const char *username,
 259                                   const char *domain,
 260                                   const struct security_token *token,
 261                                   connection_struct *conn)
 262 {
 263         int snum = SNUM(conn);
 264         bool result = conn->read_only;
 265
 266         if (lp_readlist(snum) != NULL) {
 267                 if (token_contains_name_in_list(username, domain,
 268                                                 lp_servicename(snum), token,
 269                                                 lp_readlist(snum))) {
 270                         result = True;
 271                 }
 272         }
 273
 274         if (lp_writelist(snum) != NULL) {
 275                 if (token_contains_name_in_list(username, domain,
 276                                                 lp_servicename(snum), token,
 277                                                 lp_writelist(snum))) {
 278                         result = False;
 279                 }
 280         }
 281
 282         DEBUG(10,("is_share_read_only_for_user: share %s is %s for unix user "
 283                   "%s\n", lp_servicename(snum),
 284                   result ? "read-only" : "read-write", username));
 285
 286         return result;
 287 }