--- rxvt-unicode/src/ptytty.C	2006/01/22 01:00:46	1.55
+++ rxvt-unicode/src/ptytty.C	2006/01/22 12:21:47	1.57
@@ -8,6 +8,7 @@
  * All portions of code are copyright by their respective author/s.
  * Copyright (c) 1999-2001 Geoff Wing <gcw@pobox.com>
  * Copyright (c) 2004-2006 Marc Lehmann <pcg@goof.com>
+ * Copyright (c) 2006 Emanuele Giaquinta <e.giaquinta@glauco.it>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -26,7 +27,6 @@
 
 #include "../config.h"
 
-#include "fdpass.h"
 #include "ptytty.h"
 
 #include <cstdlib>
@@ -237,7 +237,7 @@
 
   int fd = open ("/dev/tty", O_WRONLY);
   if (fd < 0)
-    return -1;		/* fatal */
+    return -1; /* fatal */
 
   close (fd);
 
@@ -375,8 +375,8 @@
 
 #if PTYTTY_HELPER
 
-static int sock_fd;
-static int pid;
+static int sock_fd = -1;
+static int helper_pid, owner_pid;
 
 struct command
 {
@@ -414,14 +414,14 @@
   write (sock_fd, &cmd, sizeof (cmd));
 
   if (read (sock_fd, &id, sizeof (id)) != sizeof (id))
-    fatal ("protocol error while creating pty using helper process, aborting.\n");
+    ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n");
 
   if (!id)
     return false;
 
-  if ((pty = ptytty_recv_fd (sock_fd)) < 0
-      || (tty = ptytty_recv_fd (sock_fd)) < 0)
-    fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n");
+  if ((pty = recv_fd (sock_fd)) < 0
+      || (tty = recv_fd (sock_fd)) < 0)
+    ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n");
 
   return true;
 }
@@ -471,8 +471,8 @@
               write (sock_fd, &cmd.id, sizeof (cmd.id));
               ptys.push_back (cmd.id);
 
-              ptytty_send_fd (sock_fd, cmd.id->pty);
-              ptytty_send_fd (sock_fd, cmd.id->tty);
+              ptytty::send_fd (sock_fd, cmd.id->pty);
+              ptytty::send_fd (sock_fd, cmd.id->tty);
             }
           else
             {
@@ -493,9 +493,9 @@
         }
       else if (cmd.type == command::destroy)
         {
-          ptytty **pty = find (ptys.begin (), ptys.end (), cmd.id);
+          vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id);
 
-          if (pty)
+          if (pty != ptys.end ())
             {
               delete *pty;
               ptys.erase (pty);
@@ -506,23 +506,31 @@
     }
 
   // destroy all ptys
-  for (ptytty **i = ptys.end (); i-- > ptys.begin (); )
+  for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); )
     delete *i;
 }
 
-void ptytty_server ()
+void
+ptytty::use_helper ()
 {
+  int pid = getpid ();
+
+  if (sock_fd >= 0 && pid == owner_pid)
+    return;
+
+  owner_pid = pid;
+
   int sv[2];
 
   if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv))
-    fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");
+    ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");
 
-  pid = fork ();
+  helper_pid = fork ();
 
-  if (pid < 0)
-    fatal ("could not create pty/sessiondb helper process, aborting.\n");
+  if (helper_pid < 0)
+    ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n");
 
-  if (pid)
+  if (helper_pid)
     {
       // client, process
       sock_fd = sv[0];
@@ -534,6 +542,8 @@
       // server, pty-helper
       sock_fd = sv[1];
 
+      chdir ("/");
+
       for (int fd = 0; fd < 1023; fd++)
         if (fd != sock_fd)
           close (fd);
@@ -545,12 +555,11 @@
 
 #endif
 
-// a "factory" *g*
 ptytty *
-new_ptytty ()
+ptytty::create ()
 {
 #if PTYTTY_HELPER
-  if (pid > 0)
+  if (helper_pid && getpid () == owner_pid)
     // use helper process
     return new ptytty_proxy;
   else
@@ -558,5 +567,47 @@
     return new ptytty_unix;
 }
 
-/*----------------------- end-of-file (C source) -----------------------*/
+void
+ptytty::init ()
+{
+  uid_t uid = getuid ();
+  gid_t gid = getgid ();
+      
+  // before doing anything else, check for setuid/setgid operation,
+  // start the helper process and drop privileges
+  if (uid != geteuid ()
+      || gid != getegid ())
+    {
+#if PTYTTY_HELPER
+      use_helper ();
+#else
+      ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n");
+#endif
+
+      drop_privileges ();
+    }
+}
+
+void
+ptytty::drop_privileges ()
+{
+  uid_t uid = getuid ();
+  gid_t gid = getgid ();
+
+  // drop privileges
+#if HAVE_SETRESUID
+  setresgid (gid, gid, gid);
+  setresuid (uid, uid, uid);
+#elif HAVE_SETREUID
+  setregid (gid, gid);
+  setreuid (uid, uid);
+#elif HAVE_SETUID
+  setgid (gid);
+  setuid (uid);
+#endif
+
+  if (uid != geteuid ()
+      || gid != getegid ())
+    ptytty_fatal ("unable to drop privileges, aborting.\n");
+}