source3/modules/vfs_expand_msdfs.c

   1 /*
   2  * Expand msdfs targets based on client IP
   3  *
   4  * Copyright (C) Volker Lendecke, 2004
   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 "system/filesys.h"
  22 #include "smbd/smbd.h"
  23 #include "../librpc/gen_ndr/ndr_netlogon.h"
  24 #include "smbd/globals.h"
  25 #include "auth.h"
  26 #include "../lib/tsocket/tsocket.h"
  27
  28 #undef DBGC_CLASS
  29 #define DBGC_CLASS DBGC_VFS
  30
  31 /**********************************************************
  32   Under mapfile we expect a table of the following format:
  33
  34   IP-Prefix whitespace expansion
  35
  36   For example:
  37   192.168.234 local.samba.org
  38   192.168     remote.samba.org
  39               default.samba.org
  40
  41   This is to redirect a DFS client to a host close to it.
  42 ***********************************************************/
  43
  44 static char *read_target_host(TALLOC_CTX *ctx, const char *mapfile,
  45                               const char *clientaddr)
  46 {
  47         FILE *f;
  48         char buf[1024];
  49         char *space = buf;
  50         bool found = false;
  51
  52         f = fopen(mapfile, "r");
  53
  54         if (f == NULL) {
  55                 DEBUG(0,("can't open IP map %s. Error %s\n",
  56                          mapfile, strerror(errno) ));
  57                 return NULL;
  58         }
  59
  60         DEBUG(10, ("Scanning mapfile [%s]\n", mapfile));
  61
  62         while (fgets(buf, sizeof(buf), f) != NULL) {
  63
  64                 if ((strlen(buf) > 0) && (buf[strlen(buf)-1] == '\n'))
  65                         buf[strlen(buf)-1] = '\0';
  66
  67                 DEBUG(10, ("Scanning line [%s]\n", buf));
  68
  69                 space = strchr_m(buf, ' ');
  70
  71                 if (space == NULL) {
  72                         DEBUG(0, ("Ignoring invalid line %s\n", buf));
  73                         continue;
  74                 }
  75
  76                 *space = '\0';
  77
  78                 if (strncmp(clientaddr, buf, strlen(buf)) == 0) {
  79                         found = true;
  80                         break;
  81                 }
  82         }
  83
  84         fclose(f);
  85
  86         if (!found) {
  87                 return NULL;
  88         }
  89
  90         space += 1;
  91
  92         while (isspace(*space))
  93                 space += 1;
  94
  95         return talloc_strdup(ctx, space);
  96 }
  97
  98 /**********************************************************
  99
 100   Expand the msdfs target host using read_target_host
 101   explained above. The syntax used in the msdfs link is
 102
 103   msdfs:@table-filename@/share
 104
 105   Everything between and including the two @-signs is
 106   replaced by the substitution string found in the table
 107   described above.
 108
 109 ***********************************************************/
 110
 111 static char *expand_msdfs_target(TALLOC_CTX *ctx,
 112                                 connection_struct *conn,
 113                                 char *target)
 114 {
 115         char *mapfilename = NULL;
 116         char *filename_start = strchr_m(target, '@');
 117         char *filename_end = NULL;
 118         int filename_len = 0;
 119         char *targethost = NULL;
 120         char *new_target = NULL;
 121         char *raddr;
 122
 123         if (filename_start == NULL) {
 124                 DEBUG(10, ("No filename start in %s\n", target));
 125                 return NULL;
 126         }
 127
 128         filename_end = strchr_m(filename_start+1, '@');
 129
 130         if (filename_end == NULL) {
 131                 DEBUG(10, ("No filename end in %s\n", target));
 132                 return NULL;
 133         }
 134
 135         filename_len = PTR_DIFF(filename_end, filename_start+1);
 136         mapfilename = talloc_strdup(ctx, filename_start+1);
 137         if (!mapfilename) {
 138                 return NULL;
 139         }
 140         mapfilename[filename_len] = '\0';
 141
 142         DEBUG(10, ("Expanding from table [%s]\n", mapfilename));
 143
 144         raddr = tsocket_address_inet_addr_string(conn->sconn->remote_address,
 145                                                  ctx);
 146         if (raddr == NULL) {
 147                 return NULL;
 148         }
 149
 150         targethost = read_target_host(ctx, mapfilename, raddr);
 151         if (targethost == NULL) {
 152                 DEBUG(1, ("Could not expand target host from file %s\n",
 153                           mapfilename));
 154                 return NULL;
 155         }
 156
 157         targethost = talloc_sub_advanced(ctx,
 158                                 lp_servicename(talloc_tos(), SNUM(conn)),
 159                                 conn->session_info->unix_info->unix_name,
 160                                 conn->connectpath,
 161                                 conn->session_info->unix_token->gid,
 162                                 conn->session_info->unix_info->sanitized_username,
 163                                 conn->session_info->info->domain_name,
 164                                 targethost);
 165
 166         DEBUG(10, ("Expanded targethost to %s\n", targethost));
 167
 168         /* Replace the part between '@...@' */
 169         *filename_start = '\0';
 170         new_target = talloc_asprintf(ctx,
 171                                 "%s%s%s",
 172                                 target,
 173                                 targethost,
 174                                 filename_end+1);
 175         if (!new_target) {
 176                 return NULL;
 177         }
 178
 179         DEBUG(10, ("New DFS target: %s\n", new_target));
 180         return new_target;
 181 }
 182
 183 static int expand_msdfs_readlink(struct vfs_handle_struct *handle,
 184                                 const struct smb_filename *smb_fname,
 185                                 char *buf,
 186                                 size_t bufsiz)
 187 {
 188         TALLOC_CTX *ctx = talloc_tos();
 189         int result;
 190         char *target = talloc_array(ctx, char, PATH_MAX+1);
 191         size_t len;
 192
 193         if (!target) {
 194                 errno = ENOMEM;
 195                 return -1;
 196         }
 197         if (bufsiz == 0) {
 198                 errno = EINVAL;
 199                 return -1;
 200         }
 201
 202         result = SMB_VFS_NEXT_READLINK(handle, smb_fname, target,
 203                                        PATH_MAX);
 204
 205         if (result <= 0)
 206                 return result;
 207
 208         target[result] = '\0';
 209
 210         if ((strncmp(target, "msdfs:", 6) == 0) &&
 211             (strchr_m(target, '@') != NULL)) {
 212                 target = expand_msdfs_target(ctx, handle->conn, target);
 213                 if (!target) {
 214                         errno = ENOENT;
 215                         return -1;
 216                 }
 217         }
 218
 219         len = MIN(bufsiz, strlen(target));
 220
 221         memcpy(buf, target, len);
 222
 223         TALLOC_FREE(target);
 224         return len;
 225 }
 226
 227 static struct vfs_fn_pointers vfs_expand_msdfs_fns = {
 228         .readlink_fn = expand_msdfs_readlink
 229 };
 230
 231 static_decl_vfs;
 232 NTSTATUS vfs_expand_msdfs_init(TALLOC_CTX *ctx)
 233 {
 234         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "expand_msdfs",
 235                                 &vfs_expand_msdfs_fns);
 236 }