From: Ricardo Cerqueira <rmcc@clix.pt>

A patch to cause sshd to chroot when it encounters the magic token
'/./' in a users home directory. The directory portion before the
token is the directory to chroot() to, the portion after the
token is the user's home directory relative to the new root.



diff -ruN openssh-1.2.3pre2-orig/acconfig.h openssh-1.2.3pre2/acconfig.h
--- openssh-1.2.3pre2-orig/acconfig.h	Sat Mar 11 20:45:40 2000
+++ openssh-1.2.3pre2/acconfig.h	Wed Mar 15 11:44:33 2000
@@ -159,6 +159,9 @@
 /* Detect IPv4 in IPv6 mapped addresses and treat as IPv4 */
 #undef IPV4_IN_IPV6
 
+/* Define if you want to enable chrooted users */
+#undef CHROOT
+
 @BOTTOM@
 
 /* ******************* Shouldn't need to edit below this line ************** */
diff -ruN openssh-1.2.3pre2-orig/config.h.in openssh-1.2.3pre2/config.h.in
--- openssh-1.2.3pre2-orig/config.h.in	Wed Mar 15 11:51:02 2000
+++ openssh-1.2.3pre2/config.h.in	Wed Mar 15 11:46:33 2000
@@ -140,6 +140,9 @@
 /* Detect IPv4 in IPv6 mapped addresses and treat as IPv4 */
 #undef IPV4_IN_IPV6
 
+/* Define if you want to enable chrooted users */
+#undef CHROOT
+
 /* The number of bytes in a char.  */
 #undef SIZEOF_CHAR
 
diff -ruN openssh-1.2.3pre2-orig/configure openssh-1.2.3pre2/configure
--- openssh-1.2.3pre2-orig/configure	Wed Mar 15 11:51:03 2000
+++ openssh-1.2.3pre2/configure	Wed Mar 15 11:46:34 2000
@@ -52,6 +52,8 @@
 ac_help="$ac_help
   --with-4in6             Check for and convert IPv4 in IPv6 mapped addresses"
 ac_help="$ac_help
+  --with-chroot           Enable chroot using /./ directory token"
+ac_help="$ac_help
   --with-pid-dir=PATH     Specify location of ssh.pid file"
 
 # Initialize some variables set by options.
@@ -3605,6 +3607,22 @@
 
 		else
 			echo "$ac_t""no (default)" 1>&6
+		fi
+	
+
+fi
+
+
+# Whether to enable the magic chroot token
+# Check whether --with-chroot or --without-chroot was given.
+if test "${with_chroot+set}" = set; then
+  withval="$with_chroot"
+  
+		if test "x$withval" != "xno" ; then	
+			cat >> confdefs.h <<\EOF
+#define CHROOT 1
+EOF
+
 		fi
 	
 
diff -ruN openssh-1.2.3pre2-orig/configure.in openssh-1.2.3pre2/configure.in
--- openssh-1.2.3pre2-orig/configure.in	Sat Mar 11 20:45:41 2000
+++ openssh-1.2.3pre2/configure.in	Wed Mar 15 11:46:04 2000
@@ -810,6 +810,16 @@
 	]
 )
 
+# Whether to enable the magic chroot token
+AC_ARG_WITH(chroot,
+	[  --with-chroot           Enable chroot using /./ directory token],
+	[
+		if test "x$withval" != "xno" ; then	
+			AC_DEFINE(CHROOT)
+		fi
+	]
+)
+
 # Where to place sshd.pid
 piddir=/var/run
 AC_ARG_WITH(pid-dir,
diff -ruN openssh-1.2.3pre2-orig/sshd.c openssh-1.2.3pre2/sshd.c
--- openssh-1.2.3pre2-orig/sshd.c	Sat Mar 11 11:58:29 2000
+++ openssh-1.2.3pre2/sshd.c	Wed Mar 15 11:43:38 2000
@@ -2365,6 +2365,10 @@
 	extern char **environ;
 	struct stat st;
 	char *argv[10];
+#ifdef CHROOT /* patch by rmcc */
+        char *user_dir;
+        char *new_root;
+#endif /* CHROOT */
 
 #ifndef USE_PAM /* pam_nologin handles this */
 	/* Check /etc/nologin. */
@@ -2422,6 +2426,29 @@
 		krb_afslog(0, 0);
 	}
 #endif /* AFS */
+
+#ifdef CHROOT /* patch by rmcc */
+
+        user_dir = xstrdup(pw->pw_dir);
+        new_root = user_dir;                                  
+
+        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){
+              printf("Couldn't chroot!\n");
+              exit(1);
+            }
+            pw->pw_dir = new_root;
+            break;
+          }
+          new_root +=2;
+        }
+
+
+#endif /* CHROOT */
 
 	/* Initialize the environment. */
 	envsize = 100;