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 "../librpc/gen_ndr/ndr_netlogon.h"
  22 #include "smbd/globals.h"
  23
  24 #undef DBGC_CLASS
  25 #define DBGC_CLASS DBGC_VFS
  26
  27 /**********************************************************
  28   Under mapfile we expect a table of the following format:
  29
  30   IP-Prefix whitespace expansion
  31
  32   For example:
  33   192.168.234 local.samba.org
  34   192.168     remote.samba.org
  35               default.samba.org
  36
  37   This is to redirect a DFS client to a host close to it.
  38 ***********************************************************/
  39
  40 static char *read_target_host(TALLOC_CTX *ctx, const char *mapfile,
  41                               const char *clientaddr)
  42 {
  43         XFILE *f;
  44         char buf[1024];
  45         char *space = buf;
  46         bool found = false;
  47
  48         f = x_fopen(mapfile, O_RDONLY, 0);
  49
  50         if (f == NULL) {
  51                 DEBUG(0,("can't open IP map %s. Error %s\n",
  52                          mapfile, strerror(errno) ));
  53                 return NULL;
  54         }
  55
  56         DEBUG(10, ("Scanning mapfile [%s]\n", mapfile));
  57
  58         while (x_fgets(buf, sizeof(buf), f) != NULL) {
  59
  60                 if ((strlen(buf) > 0) && (buf[strlen(buf)-1] == '\n'))
  61                         buf[strlen(buf)-1] = '\0';
  62
  63                 DEBUG(10, ("Scanning line [%s]\n", buf));
  64
  65                 space = strchr_m(buf, ' ');
  66
  67                 if (space == NULL) {
  68                         DEBUG(0, ("Ignoring invalid line %s\n", buf));
  69                         continue;
  70                 }
  71
  72                 *space = '\0';
  73
  74                 if (strncmp(clientaddr, buf, strlen(buf)) == 0) {
  75                         found = true;
  76                         break;
  77                 }
  78         }
  79
  80         x_fclose(f);
  81
  82         if (!found) {
  83                 return NULL;
  84         }
  85
  86         space += 1;
  87
  88         while (isspace(*space))
  89                 space += 1;
  90
  91         return talloc_strdup(ctx, space);
  92 }
  93
  94 /**********************************************************
  95
  96   Expand the msdfs target host using read_target_host
  97   explained above. The syntax used in the msdfs link is
  98
  99   msdfs:@table-filename@/share
 100
 101   Everything between and including the two @-signs is
 102   replaced by the substitution string found in the table
 103   described above.
 104
 105 ***********************************************************/
 106
 107 static char *expand_msdfs_target(TALLOC_CTX *ctx,
 108                                 connection_struct *conn,
 109                                 char *target)
 110 {
 111         char *mapfilename = NULL;
 112         char *filename_start = strchr_m(target, '@');
 113         char *filename_end = NULL;
 114         int filename_len = 0;
 115         char *targethost = NULL;
 116         char *new_target = NULL;
 117
 118         if (filename_start == NULL) {
 119                 DEBUG(10, ("No filename start in %s\n", target));
 120                 return NULL;
 121         }
 122
 123         filename_end = strchr_m(filename_start+1, '@');
 124
 125         if (filename_end == NULL) {
 126                 DEBUG(10, ("No filename end in %s\n", target));
 127                 return NULL;
 128         }
 129
 130         filename_len = PTR_DIFF(filename_end, filename_start+1);
 131         mapfilename = talloc_strdup(ctx, filename_start+1);
 132         if (!mapfilename) {
 133                 return NULL;
 134         }
 135         mapfilename[filename_len] = '\0';
 136
 137         DEBUG(10, ("Expanding from table [%s]\n", mapfilename));
 138
 139         targethost = read_target_host(
 140                 ctx, conn->sconn->client_id.addr, mapfilename);
 141         if (targethost == NULL) {
 142                 DEBUG(1, ("Could not expand target host from file %s\n",
 143                           mapfilename));
 144                 return NULL;
 145         }
 146
 147         targethost = talloc_sub_advanced(ctx,
 148                                 lp_servicename(SNUM(conn)),
 149                                 conn->server_info->unix_name,
 150                                 conn->connectpath,
 151                                 conn->server_info->utok.gid,
 152                                 conn->server_info->sanitized_username,
 153                                 conn->server_info->info3->base.domain.string,
 154                                 targethost);
 155
 156         DEBUG(10, ("Expanded targethost to %s\n", targethost));
 157
 158         /* Replace the part between '@...@' */
 159         *filename_start = '\0';
 160         new_target = talloc_asprintf(ctx,
 161                                 "%s%s%s",
 162                                 target,
 163                                 targethost,
 164                                 filename_end+1);
 165         if (!new_target) {
 166                 return NULL;
 167         }
 168
 169         DEBUG(10, ("New DFS target: %s\n", new_target));
 170         return new_target;
 171 }
 172
 173 static int expand_msdfs_readlink(struct vfs_handle_struct *handle,
 174                                  const char *path, char *buf, size_t bufsiz)
 175 {
 176         TALLOC_CTX *ctx = talloc_tos();
 177         int result;
 178         char *target = TALLOC_ARRAY(ctx, char, PATH_MAX+1);
 179         size_t len;
 180
 181         if (!target) {
 182                 errno = ENOMEM;
 183                 return -1;
 184         }
 185         if (bufsiz == 0) {
 186                 errno = EINVAL;
 187                 return -1;
 188         }
 189
 190         result = SMB_VFS_NEXT_READLINK(handle, path, target,
 191                                        PATH_MAX);
 192
 193         if (result <= 0)
 194                 return result;
 195
 196         target[result] = '\0';
 197
 198         if ((strncmp(target, "msdfs:", 6) == 0) &&
 199             (strchr_m(target, '@') != NULL)) {
 200                 target = expand_msdfs_target(ctx, handle->conn, target);
 201                 if (!target) {
 202                         errno = ENOENT;
 203                         return -1;
 204                 }
 205         }
 206
 207         len = MIN(bufsiz, strlen(target));
 208
 209         memcpy(buf, target, len);
 210
 211         TALLOC_FREE(target);
 212         return len;
 213 }
 214
 215 static struct vfs_fn_pointers vfs_expand_msdfs_fns = {
 216         .vfs_readlink = expand_msdfs_readlink
 217 };
 218
 219 NTSTATUS vfs_expand_msdfs_init(void);
 220 NTSTATUS vfs_expand_msdfs_init(void)
 221 {
 222         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "expand_msdfs",
 223                                 &vfs_expand_msdfs_fns);
 224 }