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 "../librpc/gen_ndr/ndr_netlogon.h"
  23 #include "smbd/globals.h"
  24
  25 #undef DBGC_CLASS
  26 #define DBGC_CLASS DBGC_VFS
  27
  28 /**********************************************************
  29   Under mapfile we expect a table of the following format:
  30
  31   IP-Prefix whitespace expansion
  32
  33   For example:
  34   192.168.234 local.samba.org
  35   192.168     remote.samba.org
  36               default.samba.org
  37
  38   This is to redirect a DFS client to a host close to it.
  39 ***********************************************************/
  40
  41 static char *read_target_host(TALLOC_CTX *ctx, const char *mapfile,
  42                               const char *clientaddr)
  43 {
  44         XFILE *f;
  45         char buf[1024];
  46         char *space = buf;
  47         bool found = false;
  48
  49         f = x_fopen(mapfile, O_RDONLY, 0);
  50
  51         if (f == NULL) {
  52                 DEBUG(0,("can't open IP map %s. Error %s\n",
  53                          mapfile, strerror(errno) ));
  54                 return NULL;
  55         }
  56
  57         DEBUG(10, ("Scanning mapfile [%s]\n", mapfile));
  58
  59         while (x_fgets(buf, sizeof(buf), f) != NULL) {
  60
  61                 if ((strlen(buf) > 0) && (buf[strlen(buf)-1] == '\n'))
  62                         buf[strlen(buf)-1] = '\0';
  63
  64                 DEBUG(10, ("Scanning line [%s]\n", buf));
  65
  66                 space = strchr_m(buf, ' ');
  67
  68                 if (space == NULL) {
  69                         DEBUG(0, ("Ignoring invalid line %s\n", buf));
  70                         continue;
  71                 }
  72
  73                 *space = '\0';
  74
  75                 if (strncmp(clientaddr, buf, strlen(buf)) == 0) {
  76                         found = true;
  77                         break;
  78                 }
  79         }
  80
  81         x_fclose(f);
  82
  83         if (!found) {
  84                 return NULL;
  85         }
  86
  87         space += 1;
  88
  89         while (isspace(*space))
  90                 space += 1;
  91
  92         return talloc_strdup(ctx, space);
  93 }
  94
  95 /**********************************************************
  96
  97   Expand the msdfs target host using read_target_host
  98   explained above. The syntax used in the msdfs link is
  99
 100   msdfs:@table-filename@/share
 101
 102   Everything between and including the two @-signs is
 103   replaced by the substitution string found in the table
 104   described above.
 105
 106 ***********************************************************/
 107
 108 static char *expand_msdfs_target(TALLOC_CTX *ctx,
 109                                 connection_struct *conn,
 110                                 char *target)
 111 {
 112         char *mapfilename = NULL;
 113         char *filename_start = strchr_m(target, '@');
 114         char *filename_end = NULL;
 115         int filename_len = 0;
 116         char *targethost = NULL;
 117         char *new_target = NULL;
 118
 119         if (filename_start == NULL) {
 120                 DEBUG(10, ("No filename start in %s\n", target));
 121                 return NULL;
 122         }
 123
 124         filename_end = strchr_m(filename_start+1, '@');
 125
 126         if (filename_end == NULL) {
 127                 DEBUG(10, ("No filename end in %s\n", target));
 128                 return NULL;
 129         }
 130
 131         filename_len = PTR_DIFF(filename_end, filename_start+1);
 132         mapfilename = talloc_strdup(ctx, filename_start+1);
 133         if (!mapfilename) {
 134                 return NULL;
 135         }
 136         mapfilename[filename_len] = '\0';
 137
 138         DEBUG(10, ("Expanding from table [%s]\n", mapfilename));
 139
 140         targethost = read_target_host(
 141                 ctx, conn->sconn->client_id.addr, mapfilename);
 142         if (targethost == NULL) {
 143                 DEBUG(1, ("Could not expand target host from file %s\n",
 144                           mapfilename));
 145                 return NULL;
 146         }
 147
 148         targethost = talloc_sub_advanced(ctx,
 149                                 lp_servicename(SNUM(conn)),
 150                                 conn->session_info->unix_name,
 151                                 conn->connectpath,
 152                                 conn->session_info->utok.gid,
 153                                 conn->session_info->sanitized_username,
 154                                 conn->session_info->info3->base.domain.string,
 155                                 targethost);
 156
 157         DEBUG(10, ("Expanded targethost to %s\n", targethost));
 158
 159         /* Replace the part between '@...@' */
 160         *filename_start = '\0';
 161         new_target = talloc_asprintf(ctx,
 162                                 "%s%s%s",
 163                                 target,
 164                                 targethost,
 165                                 filename_end+1);
 166         if (!new_target) {
 167                 return NULL;
 168         }
 169
 170         DEBUG(10, ("New DFS target: %s\n", new_target));
 171         return new_target;
 172 }
 173
 174 static int expand_msdfs_readlink(struct vfs_handle_struct *handle,
 175                                  const char *path, char *buf, size_t bufsiz)
 176 {
 177         TALLOC_CTX *ctx = talloc_tos();
 178         int result;
 179         char *target = TALLOC_ARRAY(ctx, char, PATH_MAX+1);
 180         size_t len;
 181
 182         if (!target) {
 183                 errno = ENOMEM;
 184                 return -1;
 185         }
 186         if (bufsiz == 0) {
 187                 errno = EINVAL;
 188                 return -1;
 189         }
 190
 191         result = SMB_VFS_NEXT_READLINK(handle, path, target,
 192                                        PATH_MAX);
 193
 194         if (result <= 0)
 195                 return result;
 196
 197         target[result] = '\0';
 198
 199         if ((strncmp(target, "msdfs:", 6) == 0) &&
 200             (strchr_m(target, '@') != NULL)) {
 201                 target = expand_msdfs_target(ctx, handle->conn, target);
 202                 if (!target) {
 203                         errno = ENOENT;
 204                         return -1;
 205                 }
 206         }
 207
 208         len = MIN(bufsiz, strlen(target));
 209
 210         memcpy(buf, target, len);
 211
 212         TALLOC_FREE(target);
 213         return len;
 214 }
 215
 216 static struct vfs_fn_pointers vfs_expand_msdfs_fns = {
 217         .vfs_readlink = expand_msdfs_readlink
 218 };
 219
 220 NTSTATUS vfs_expand_msdfs_init(void);
 221 NTSTATUS vfs_expand_msdfs_init(void)
 222 {
 223         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "expand_msdfs",
 224                                 &vfs_expand_msdfs_fns);
 225 }