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
  27 #undef DBGC_CLASS
  28 #define DBGC_CLASS DBGC_VFS
  29
  30 /**********************************************************
  31   Under mapfile we expect a table of the following format:
  32
  33   IP-Prefix whitespace expansion
  34
  35   For example:
  36   192.168.234 local.samba.org
  37   192.168     remote.samba.org
  38               default.samba.org
  39
  40   This is to redirect a DFS client to a host close to it.
  41 ***********************************************************/
  42
  43 static char *read_target_host(TALLOC_CTX *ctx, const char *mapfile,
  44                               const char *clientaddr)
  45 {
  46         XFILE *f;
  47         char buf[1024];
  48         char *space = buf;
  49         bool found = false;
  50
  51         f = x_fopen(mapfile, O_RDONLY, 0);
  52
  53         if (f == NULL) {
  54                 DEBUG(0,("can't open IP map %s. Error %s\n",
  55                          mapfile, strerror(errno) ));
  56                 return NULL;
  57         }
  58
  59         DEBUG(10, ("Scanning mapfile [%s]\n", mapfile));
  60
  61         while (x_fgets(buf, sizeof(buf), f) != NULL) {
  62
  63                 if ((strlen(buf) > 0) && (buf[strlen(buf)-1] == '\n'))
  64                         buf[strlen(buf)-1] = '\0';
  65
  66                 DEBUG(10, ("Scanning line [%s]\n", buf));
  67
  68                 space = strchr_m(buf, ' ');
  69
  70                 if (space == NULL) {
  71                         DEBUG(0, ("Ignoring invalid line %s\n", buf));
  72                         continue;
  73                 }
  74
  75                 *space = '\0';
  76
  77                 if (strncmp(clientaddr, buf, strlen(buf)) == 0) {
  78                         found = true;
  79                         break;
  80                 }
  81         }
  82
  83         x_fclose(f);
  84
  85         if (!found) {
  86                 return NULL;
  87         }
  88
  89         space += 1;
  90
  91         while (isspace(*space))
  92                 space += 1;
  93
  94         return talloc_strdup(ctx, space);
  95 }
  96
  97 /**********************************************************
  98
  99   Expand the msdfs target host using read_target_host
 100   explained above. The syntax used in the msdfs link is
 101
 102   msdfs:@table-filename@/share
 103
 104   Everything between and including the two @-signs is
 105   replaced by the substitution string found in the table
 106   described above.
 107
 108 ***********************************************************/
 109
 110 static char *expand_msdfs_target(TALLOC_CTX *ctx,
 111                                 connection_struct *conn,
 112                                 char *target)
 113 {
 114         char *mapfilename = NULL;
 115         char *filename_start = strchr_m(target, '@');
 116         char *filename_end = NULL;
 117         int filename_len = 0;
 118         char *targethost = NULL;
 119         char *new_target = NULL;
 120
 121         if (filename_start == NULL) {
 122                 DEBUG(10, ("No filename start in %s\n", target));
 123                 return NULL;
 124         }
 125
 126         filename_end = strchr_m(filename_start+1, '@');
 127
 128         if (filename_end == NULL) {
 129                 DEBUG(10, ("No filename end in %s\n", target));
 130                 return NULL;
 131         }
 132
 133         filename_len = PTR_DIFF(filename_end, filename_start+1);
 134         mapfilename = talloc_strdup(ctx, filename_start+1);
 135         if (!mapfilename) {
 136                 return NULL;
 137         }
 138         mapfilename[filename_len] = '\0';
 139
 140         DEBUG(10, ("Expanding from table [%s]\n", mapfilename));
 141
 142         targethost = read_target_host(
 143                 ctx, conn->sconn->client_id.addr, mapfilename);
 144         if (targethost == NULL) {
 145                 DEBUG(1, ("Could not expand target host from file %s\n",
 146                           mapfilename));
 147                 return NULL;
 148         }
 149
 150         targethost = talloc_sub_advanced(ctx,
 151                                 lp_servicename(SNUM(conn)),
 152                                 conn->session_info->unix_name,
 153                                 conn->connectpath,
 154                                 conn->session_info->utok.gid,
 155                                 conn->session_info->sanitized_username,
 156                                 conn->session_info->info3->base.domain.string,
 157                                 targethost);
 158
 159         DEBUG(10, ("Expanded targethost to %s\n", targethost));
 160
 161         /* Replace the part between '@...@' */
 162         *filename_start = '\0';
 163         new_target = talloc_asprintf(ctx,
 164                                 "%s%s%s",
 165                                 target,
 166                                 targethost,
 167                                 filename_end+1);
 168         if (!new_target) {
 169                 return NULL;
 170         }
 171
 172         DEBUG(10, ("New DFS target: %s\n", new_target));
 173         return new_target;
 174 }
 175
 176 static int expand_msdfs_readlink(struct vfs_handle_struct *handle,
 177                                  const char *path, char *buf, size_t bufsiz)
 178 {
 179         TALLOC_CTX *ctx = talloc_tos();
 180         int result;
 181         char *target = TALLOC_ARRAY(ctx, char, PATH_MAX+1);
 182         size_t len;
 183
 184         if (!target) {
 185                 errno = ENOMEM;
 186                 return -1;
 187         }
 188         if (bufsiz == 0) {
 189                 errno = EINVAL;
 190                 return -1;
 191         }
 192
 193         result = SMB_VFS_NEXT_READLINK(handle, path, target,
 194                                        PATH_MAX);
 195
 196         if (result <= 0)
 197                 return result;
 198
 199         target[result] = '\0';
 200
 201         if ((strncmp(target, "msdfs:", 6) == 0) &&
 202             (strchr_m(target, '@') != NULL)) {
 203                 target = expand_msdfs_target(ctx, handle->conn, target);
 204                 if (!target) {
 205                         errno = ENOENT;
 206                         return -1;
 207                 }
 208         }
 209
 210         len = MIN(bufsiz, strlen(target));
 211
 212         memcpy(buf, target, len);
 213
 214         TALLOC_FREE(target);
 215         return len;
 216 }
 217
 218 static struct vfs_fn_pointers vfs_expand_msdfs_fns = {
 219         .vfs_readlink = expand_msdfs_readlink
 220 };
 221
 222 NTSTATUS vfs_expand_msdfs_init(void);
 223 NTSTATUS vfs_expand_msdfs_init(void)
 224 {
 225         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "expand_msdfs",
 226                                 &vfs_expand_msdfs_fns);
 227 }