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 #include "msdfs.h"
  28
  29 #undef DBGC_CLASS
  30 #define DBGC_CLASS DBGC_VFS
  31
  32 /**********************************************************
  33   Under mapfile we expect a table of the following format:
  34
  35   IP-Prefix whitespace expansion
  36
  37   For example:
  38   192.168.234 local.samba.org
  39   192.168     remote.samba.org
  40               default.samba.org
  41
  42   This is to redirect a DFS client to a host close to it.
  43 ***********************************************************/
  44
  45 static char *read_target_host(TALLOC_CTX *ctx, const char *mapfile,
  46                               const char *clientaddr)
  47 {
  48         FILE *f;
  49         char buf[1024];
  50         char *space = buf;
  51         bool found = false;
  52
  53         f = fopen(mapfile, "r");
  54
  55         if (f == NULL) {
  56                 DEBUG(0,("can't open IP map %s. Error %s\n",
  57                          mapfile, strerror(errno) ));
  58                 return NULL;
  59         }
  60
  61         DEBUG(10, ("Scanning mapfile [%s]\n", mapfile));
  62
  63         while (fgets(buf, sizeof(buf), f) != NULL) {
  64
  65                 if ((strlen(buf) > 0) && (buf[strlen(buf)-1] == '\n'))
  66                         buf[strlen(buf)-1] = '\0';
  67
  68                 DEBUG(10, ("Scanning line [%s]\n", buf));
  69
  70                 space = strchr_m(buf, ' ');
  71
  72                 if (space == NULL) {
  73                         DEBUG(0, ("Ignoring invalid line %s\n", buf));
  74                         continue;
  75                 }
  76
  77                 *space = '\0';
  78
  79                 if (strncmp(clientaddr, buf, strlen(buf)) == 0) {
  80                         found = true;
  81                         break;
  82                 }
  83         }
  84
  85         fclose(f);
  86
  87         if (!found) {
  88                 return NULL;
  89         }
  90
  91         space += 1;
  92
  93         while (isspace(*space))
  94                 space += 1;
  95
  96         return talloc_strdup(ctx, space);
  97 }
  98
  99 /**********************************************************
 100
 101   Expand the msdfs target host using read_target_host
 102   explained above. The syntax used in the msdfs link is
 103
 104   msdfs:@table-filename@/share
 105
 106   Everything between and including the two @-signs is
 107   replaced by the substitution string found in the table
 108   described above.
 109
 110 ***********************************************************/
 111
 112 static char *expand_msdfs_target(TALLOC_CTX *ctx,
 113                                 connection_struct *conn,
 114                                 char *target)
 115 {
 116         const struct loadparm_substitution *lp_sub =
 117                 loadparm_s3_global_substitution();
 118         char *mapfilename = NULL;
 119         char *filename_start = strchr_m(target, '@');
 120         char *filename_end = NULL;
 121         int filename_len = 0;
 122         char *targethost = NULL;
 123         char *new_target = NULL;
 124         char *raddr;
 125
 126         if (filename_start == NULL) {
 127                 DEBUG(10, ("No filename start in %s\n", target));
 128                 return NULL;
 129         }
 130
 131         filename_end = strchr_m(filename_start+1, '@');
 132
 133         if (filename_end == NULL) {
 134                 DEBUG(10, ("No filename end in %s\n", target));
 135                 return NULL;
 136         }
 137
 138         filename_len = PTR_DIFF(filename_end, filename_start+1);
 139         mapfilename = talloc_strdup(ctx, filename_start+1);
 140         if (!mapfilename) {
 141                 return NULL;
 142         }
 143         mapfilename[filename_len] = '\0';
 144
 145         /*
 146          * dfs links returned have had '/' characters replaced with '\'.
 147          * Return them to '/' so we can have absoute path mapfilenames.
 148          */
 149         string_replace(mapfilename, '\\', '/');
 150
 151         DEBUG(10, ("Expanding from table [%s]\n", mapfilename));
 152
 153         raddr = tsocket_address_inet_addr_string(conn->sconn->remote_address,
 154                                                  ctx);
 155         if (raddr == NULL) {
 156                 return NULL;
 157         }
 158
 159         targethost = read_target_host(ctx, mapfilename, raddr);
 160         if (targethost == NULL) {
 161                 DEBUG(1, ("Could not expand target host from file %s\n",
 162                           mapfilename));
 163                 return NULL;
 164         }
 165
 166         targethost = talloc_sub_full(ctx,
 167                                 lp_servicename(talloc_tos(), lp_sub, SNUM(conn)),
 168                                 conn->session_info->unix_info->unix_name,
 169                                 conn->connectpath,
 170                                 conn->session_info->unix_token->gid,
 171                                 conn->session_info->unix_info->sanitized_username,
 172                                 conn->session_info->info->domain_name,
 173                                 targethost);
 174
 175         DEBUG(10, ("Expanded targethost to %s\n", targethost));
 176
 177         /* Replace the part between '@...@' */
 178         *filename_start = '\0';
 179         new_target = talloc_asprintf(ctx,
 180                                 "%s%s%s",
 181                                 target,
 182                                 targethost,
 183                                 filename_end+1);
 184         if (!new_target) {
 185                 return NULL;
 186         }
 187
 188         DEBUG(10, ("New DFS target: %s\n", new_target));
 189         return new_target;
 190 }
 191
 192 static NTSTATUS expand_read_dfs_pathat(struct vfs_handle_struct *handle,
 193                                 TALLOC_CTX *mem_ctx,
 194                                 struct files_struct *dirfsp,
 195                                 struct smb_filename *smb_fname,
 196                                 struct referral **ppreflist,
 197                                 size_t *preferral_count)
 198 {
 199         NTSTATUS status;
 200         size_t i;
 201         struct referral *reflist = NULL;
 202         size_t count = 0;
 203         TALLOC_CTX *frame = talloc_stackframe();
 204
 205         /*
 206          * Always call the NEXT function first, then
 207          * modify the return if needed.
 208          */
 209         status = SMB_VFS_NEXT_READ_DFS_PATHAT(handle,
 210                                 mem_ctx,
 211                                 dirfsp,
 212                                 smb_fname,
 213                                 ppreflist,
 214                                 preferral_count);
 215
 216         if (!NT_STATUS_IS_OK(status)) {
 217                 TALLOC_FREE(frame);
 218                 return status;
 219         }
 220
 221         /*
 222          * This function can be called to check if a pathname
 223          * is an MSDFS link, but not return the values of it.
 224          * In this case ppreflist and preferral_count are NULL,
 225          * so don't bother trying to look at any returns.
 226          */
 227         if (ppreflist == NULL || preferral_count == NULL) {
 228                 TALLOC_FREE(frame);
 229                 return status;
 230         }
 231
 232         /*
 233          * We are always returning the values returned
 234          * returned by the NEXT call, but we might mess
 235          * with the reflist[i].alternate_path values,
 236          * so use local pointers to minimise indirections.
 237          */
 238         count = *preferral_count;
 239         reflist = *ppreflist;
 240
 241         for (i = 0; i < count; i++) {
 242                 if (strchr_m(reflist[i].alternate_path, '@') != NULL) {
 243                         char *new_altpath = expand_msdfs_target(frame,
 244                                                 handle->conn,
 245                                                 reflist[i].alternate_path);
 246                         if (new_altpath == NULL) {
 247                                 TALLOC_FREE(*ppreflist);
 248                                 *preferral_count = 0;
 249                                 TALLOC_FREE(frame);
 250                                 return NT_STATUS_NO_MEMORY;
 251                         }
 252                         reflist[i].alternate_path = talloc_move(reflist,
 253                                                         &new_altpath);
 254                 }
 255         }
 256         TALLOC_FREE(frame);
 257         return status;
 258 }
 259
 260 static struct vfs_fn_pointers vfs_expand_msdfs_fns = {
 261         .read_dfs_pathat_fn = expand_read_dfs_pathat,
 262 };
 263
 264 static_decl_vfs;
 265 NTSTATUS vfs_expand_msdfs_init(TALLOC_CTX *ctx)
 266 {
 267         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "expand_msdfs",
 268                                 &vfs_expand_msdfs_fns);
 269 }