Prevent hardlink attack on mbox sticky mail directory. fixes: bug #988

[exim.git] / src / src / transports / appendfile.c

diff --git a/src/src/transports/appendfile.c b/src/src/transports/appendfile.c
index d7f2705448b17501046bbd45f135c5b12e5e4082..984f2d7d64f7c25d63e2db4783c6cdd44e4e1eac 100644 (file)
--- a/src/src/transports/appendfile.c
+++ b/src/src/transports/appendfile.c
@@ -1,10 +1,10 @@
-/* $Cambridge: exim/src/src/transports/appendfile.c,v 1.17 2006/04/25 14:02:30 ph10 Exp $ */
+/* $Cambridge: exim/src/src/transports/appendfile.c,v 1.25 2010/05/26 12:26:01 nm4 Exp $ */
 
 /*************************************************
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2006 */
+/* Copyright (c) University of Cambridge 1995 - 2009 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 
@@ -107,6 +107,8 @@ optionlist appendfile_transport_options[] = {
       (void *)offsetof(appendfile_transport_options_block, maildir_tag) },
   { "maildir_use_size_file", opt_bool,
       (void *)offsetof(appendfile_transport_options_block, maildir_use_size_file ) } ,
+  { "maildirfolder_create_regex", opt_stringptr,
+      (void *)offsetof(appendfile_transport_options_block, maildirfolder_create_regex ) },
 #endif  /* SUPPORT_MAILDIR */
 #ifdef SUPPORT_MAILSTORE
   { "mailstore_format",  opt_bool,
@@ -184,6 +186,7 @@ appendfile_transport_options_block appendfile_transport_option_defaults = {
   NULL,           /* mailbox_filecount_string */
   US"^(?:cur|new|\\..*)$",  /* maildir_dir_regex */
   NULL,           /* maildir_tag */
+  NULL,           /* maildirfolder_create_regex */
   NULL,           /* mailstore_prefix */
   NULL,           /* mailstore_suffix */
   NULL,           /* check_string (default changed for non-bsmtp file)*/
@@ -596,10 +599,10 @@ host.next = NULL;
 until one succeeds. However, it appears that at least on some systems, comsat
 doesn't listen on the ::1 address. So for the moment, just force the address to
 be 127.0.0.1. At some future stage, when IPv6 really is superseding IPv4, this
-can be changed. */
+can be changed. (But actually, comsat is probably dying out anyway.) */
 
 /******
-if (host_find_byname(&host, NULL, NULL, FALSE) == HOST_FIND_FAILED)
+if (host_find_byname(&host, NULL, 0, NULL, FALSE) == HOST_FIND_FAILED)
   {
   DEBUG(D_transport) debug_printf("\"localhost\" unknown\n");
   return;
@@ -1803,6 +1806,18 @@ if (!isdirectory)
         goto RETURN;
         }
 
+      /* Just in case this is a sticky-bit mail directory, we don't want
+      users to be able to create hard links to other users' files. */
+
+      if (statbuf.st_nlink != 1)
+        {
+        addr->basic_errno = ERRNO_NOTREGULAR;
+        addr->message = string_sprintf("mailbox %s%s has too many links (%d)",
+          filename, islink? " (symlink)" : "", statbuf.st_nlink);
+        goto RETURN;
+
+        }
+
       /* If symlinks are permitted (not recommended), the lstat() above will
       have found the symlink. Its ownership has just been checked; go round
       the loop again, using stat() instead of lstat(). That will never yield a
@@ -2152,10 +2167,11 @@ else
     }
 
   #ifdef SUPPORT_MAILDIR
-  /* For a maildir delivery, ensure that all the relevant directories exist */
+  /* For a maildir delivery, ensure that all the relevant directories exist,
+  and a maildirfolder file if necessary. */
 
   if (mbformat == mbf_maildir && !maildir_ensure_directories(path, addr,
-    ob->create_directory, ob->dirmode))
+    ob->create_directory, ob->dirmode, ob->maildirfolder_create_regex))
       return FALSE;
   #endif  /* SUPPORT_MAILDIR */
 
@@ -2236,6 +2252,8 @@ else
             {
             *slash = 0;
             check_path = new_check_path;
+            DEBUG(D_transport) debug_printf("maildirfolder file exists: "
+              "quota check directory changed to %s\n", check_path);
             }
           }
         }
@@ -2445,6 +2463,8 @@ else
         addr->message = string_sprintf ("failed to open %s (%d tr%s)",
           filename, i, (i == 1)? "y" : "ies");
         addr->basic_errno = errno;
+        if (errno == errno_quota || errno == ENOSPC)
+          addr->user_message = US"mailbox is full";
         return FALSE;
         }
 
@@ -2785,7 +2805,7 @@ if (temp_file != NULL && ob->mbx_format)
 /* Force out the remaining data to check for any errors; some OS don't allow
 fsync() to be called for a FIFO. */
 
-if (yield == OK && !isfifo && fsync(fd) < 0) yield = DEFER;
+if (yield == OK && !isfifo && EXIMfsync(fd) < 0) yield = DEFER;
 
 /* Update message_size to the accurate count of bytes written, including
 added headers. */
@@ -2897,6 +2917,7 @@ if (yield != OK)
     #else
     addr->message = string_sprintf("mailbox is full");
     #endif  /* EDQUOT */
+    addr->user_message = US"mailbox is full";
     DEBUG(D_transport) debug_printf("System quota exceeded for %s%s%s\n",
       dataname,
       isdirectory? US"" : US": time since file read = ",