OpenSSH (GNU/Linux) chroot patch for openssh-5.2p1

To chroot a SSH session into ~/ by using /./ in homedir path

example:
    ~# useradd -d /home/sn00p/./ sn00p
    ~# cat /etc/passwd | grep sn00p
    sn00p:x:10000:10000::/home/sn00p/./:/bin/bash


download & unpack the source:
    ~# cd /usr/src
    ~# wget ftp://mirror.switch.ch/pub/OpenBSD/OpenSSH/portable/openssh-5.2p1.tar.gz
    ~# tar zxf openssh-5.2p1.tar.gz

download patch & apply to source:
    ~# cd /usr/src/openssh-5.2p1
    ~# wget http://www.cybnet.ch/misc/openssh-5.2p1-chroot.patch
    ~# patch -p0 < openssh-5.2p1-chroot.patch

configure & compile:
    ~# ./configure --your-options
    ~# make 


Original patch by Ricardo Cerqueira <rmcc@clix.pt>
Updated for OpenSSH 5 by Mike Mueller <mike@cybnet.ch>

====================================================================================
diff -u openssh-5.2p1/session.c.orig openssh-5.2p1/session.c
--- session.c.orig	2009-22-01 09:46:01.000000000 +0100
+++ session.c	2009-03-02 13:34:59.000000000 +0100
@@ -1,4 +1,4 @@
-/* $OpenBSD: session.c,v 1.245 2009/01/22 09:46:01 djm Exp $ */
+/* $OpenBSD: session.c,v 1.245-sn0 2009/03/02 13:33:00 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -91,6 +91,8 @@
 #include "monitor_wrap.h"
 #include "sftp.h"
 
+#define CHROOT
+
 #if defined(KRB5) && defined(USE_AFS)
 #include <kafs.h>
 #endif
@@ -1459,6 +1461,12 @@
 {
 	char *chroot_path, *tmp;
 
+#ifdef CHROOT
+	char *user_dir;
+	char *new_root;
+#endif
+
+
 #ifdef WITH_SELINUX
 	/* Cache selinux status for later use */
 	(void)ssh_selinux_enabled();
@@ -1506,6 +1514,27 @@
 			exit(1);
 		}
 		endgrent();
+
+#ifdef CHROOT
+                user_dir = xstrdup(pw->pw_dir);
+                new_root = user_dir + 1;
+
+                while((new_root = strchr(new_root, '.')) != NULL) {
+                        new_root--;
+                        if(strncmp(new_root, "/./", 3) == 0) {
+                                *new_root = '\0';
+                                new_root += 2;
+
+                                if(chroot(user_dir) != 0)
+                                        fatal("Couldn't chroot to user directory %s", user_dir);
+
+                                pw->pw_dir = new_root;
+                                break;
+                        }
+                        new_root += 2;
+                }
+#endif 
+
 # ifdef USE_PAM
 		/*
 		 * PAM credentials may take the form of supplementary groups.