From 8c59bae0e4bdc0e3456d1802b391370bdf9975f3 Mon Sep 17 00:00:00 2001
From: mancha <mancha1 AT zoho DOT com>
Date: Mon, 6 Oct 2014
Subject: Re-introduce TCP Wrappers support

Support for TCP Wrappers was dropped as of OpenSSH 6.7. This patch
resurrects the feature.

Relevant upstream commits:

  https://anongit.mindrot.org/openssh.git/commit/?id=f2719b7c2b8a
  https://anongit.mindrot.org/openssh.git/commit/?id=f9696566fb41

---
 configure.ac |   57 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 sshd.8       |    7 +++++++
 sshd.c       |   25 +++++++++++++++++++++++
 3 files changed, 89 insertions(+)

--- a/configure.ac
+++ b/configure.ac
@@ -1380,6 +1380,62 @@ AC_ARG_WITH([skey],
 	]
 )
 
+# Check whether user wants TCP wrappers support
+TCPW_MSG="no"
+AC_ARG_WITH([tcp-wrappers],
+	[  --with-tcp-wrappers[[=PATH]] Enable tcpwrappers support (optionally in PATH)],
+	[
+		if test "x$withval" != "xno" ; then
+			saved_LIBS="$LIBS"
+			saved_LDFLAGS="$LDFLAGS"
+			saved_CPPFLAGS="$CPPFLAGS"
+			if test -n "${withval}" && \
+			    test "x${withval}" != "xyes"; then
+				if test -d "${withval}/lib"; then
+					if test -n "${need_dash_r}"; then
+						LDFLAGS="-L${withval}/lib -R${withval}/lib ${LDFLAGS}"
+					else
+						LDFLAGS="-L${withval}/lib ${LDFLAGS}"
+					fi
+				else
+					if test -n "${need_dash_r}"; then
+						LDFLAGS="-L${withval} -R${withval} ${LDFLAGS}"
+					else
+						LDFLAGS="-L${withval} ${LDFLAGS}"
+					fi
+				fi
+				if test -d "${withval}/include"; then
+					CPPFLAGS="-I${withval}/include ${CPPFLAGS}"
+				else
+					CPPFLAGS="-I${withval} ${CPPFLAGS}"
+				fi
+			fi
+			LIBS="-lwrap $LIBS"
+			AC_MSG_CHECKING([for libwrap])
+			AC_LINK_IFELSE([AC_LANG_PROGRAM([[
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <tcpd.h>
+int deny_severity = 0, allow_severity = 0;
+				]], [[
+	hosts_access(0);
+				]])], [
+					AC_MSG_RESULT([yes])
+					AC_DEFINE([LIBWRAP], [1],
+						[Define if you want
+						TCP Wrappers support])
+					SSHDLIBS="$SSHDLIBS -lwrap"
+					TCPW_MSG="yes"
+				], [
+					AC_MSG_ERROR([*** libwrap missing])
+				
+			])
+			LIBS="$saved_LIBS"
+		fi
+	]
+)
+
 # Check whether user wants to use ldns
 LDNS_MSG="no"
 AC_ARG_WITH(ldns,
@@ -4829,6 +4885,7 @@ echo "                 KerberosV support
 echo "                   SELinux support: $SELINUX_MSG"
 echo "                 Smartcard support: $SCARD_MSG"
 echo "                     S/KEY support: $SKEY_MSG"
+echo "              TCP Wrappers support: $TCPW_MSG"
 echo "              MD5 password support: $MD5_MSG"
 echo "                   libedit support: $LIBEDIT_MSG"
 echo "  Solaris process contract support: $SPC_MSG"
--- a/sshd.8
+++ b/sshd.8
@@ -851,6 +851,12 @@ the user's home directory becomes access
 This file should be writable only by the user, and need not be
 readable by anyone else.
 .Pp
+.It Pa /etc/hosts.allow
+.It Pa /etc/hosts.deny
+Access controls that should be enforced by tcp-wrappers are defined here.
+Further details are described in
+.Xr hosts_access 5 .
+.Pp
 .It Pa /etc/hosts.equiv
 This file is for host-based authentication (see
 .Xr ssh 1 ) .
@@ -954,6 +960,7 @@ The content of this file is not sensitiv
 .Xr ssh-keygen 1 ,
 .Xr ssh-keyscan 1 ,
 .Xr chroot 2 ,
+.Xr hosts_access 5 ,
 .Xr login.conf 5 ,
 .Xr moduli 5 ,
 .Xr sshd_config 5 ,
--- a/sshd.c
+++ b/sshd.c
@@ -123,6 +123,13 @@
 #include "ssh-sandbox.h"
 #include "version.h"
 
+#ifdef LIBWRAP
+#include <tcpd.h>
+#include <syslog.h>
+int allow_severity;
+int deny_severity;
+#endif /* LIBWRAP */
+
 #ifndef O_NOCTTY
 #define O_NOCTTY	0
 #endif
@@ -2054,6 +2061,24 @@ main(int ac, char **av)
 #ifdef SSH_AUDIT_EVENTS
 	audit_connection_from(remote_ip, remote_port);
 #endif
+#ifdef LIBWRAP
+	allow_severity = options.log_facility|LOG_INFO;
+	deny_severity = options.log_facility|LOG_WARNING;
+	/* Check whether logins are denied from this host. */
+	if (packet_connection_is_on_socket()) {
+		struct request_info req;
+
+		request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
+		fromhost(&req);
+
+		if (!hosts_access(&req)) {
+			debug("Connection refused by tcp wrapper");
+			refuse(&req);
+			/* NOTREACHED */
+			fatal("libwrap refuse returns");
+		}
+	}
+#endif /* LIBWRAP */
 
 	/* Log the connection. */
 	verbose("Connection from %s port %d on %s port %d",