# $OpenBSD: forward-control.sh,v 1.4 2017/04/30 23:34:55 djm Exp $ # Placed in the Public Domain. tid="sshd control of local and remote forwarding" LFWD_PORT=3320 RFWD_PORT=3321 CTL=$OBJ/ctl-sock READY=$OBJ/ready wait_for_file_to_appear() { _path=$1 _n=0 while test ! -f $_path ; do test $_n -eq 1 && trace "waiting for $_path to appear" _n=`expr $_n + 1` test $_n -ge 20 && return 1 sleep 1 done return 0 } wait_for_process_to_exit() { _pid=$1 _n=0 while kill -0 $_pid 2>/dev/null ; do test $_n -eq 1 && trace "waiting for $_pid to exit" _n=`expr $_n + 1` test $_n -ge 20 && return 1 sleep 1 done return 0 } # usage: check_lfwd Y|N message check_lfwd() { _expected=$1 _message=$2 rm -f $READY ${SSH} -F $OBJ/ssh_proxy \ -L$LFWD_PORT:127.0.0.1:$PORT \ -o ExitOnForwardFailure=yes \ -n host exec sh -c \'"sleep 60 & echo \$! > $READY ; wait "\' \ >/dev/null 2>&1 & _sshpid=$! wait_for_file_to_appear $READY || \ fatal "check_lfwd ssh fail: $_message" ${SSH} -F $OBJ/ssh_config -p $LFWD_PORT \ -oConnectionAttempts=4 host true >/dev/null 2>&1 _result=$? kill $_sshpid `cat $READY` 2>/dev/null wait_for_process_to_exit $_sshpid if test "x$_expected" = "xY" -a $_result -ne 0 ; then fail "check_lfwd failed (expecting success): $_message" elif test "x$_expected" = "xN" -a $_result -eq 0 ; then fail "check_lfwd succeeded (expecting failure): $_message" elif test "x$_expected" != "xY" -a "x$_expected" != "xN" ; then fatal "check_lfwd invalid argument \"$_expected\"" else verbose "check_lfwd done (expecting $_expected): $_message" fi } # usage: check_rfwd Y|N message check_rfwd() { _expected=$1 _message=$2 rm -f $READY ${SSH} -F $OBJ/ssh_proxy \ -R$RFWD_PORT:127.0.0.1:$PORT \ -o ExitOnForwardFailure=yes \ -n host exec sh -c \'"sleep 60 & echo \$! > $READY ; wait "\' \ >/dev/null 2>&1 & _sshpid=$! wait_for_file_to_appear $READY _result=$? if test $_result -eq 0 ; then ${SSH} -F $OBJ/ssh_config -p $RFWD_PORT \ -oConnectionAttempts=4 host true >/dev/null 2>&1 _result=$? kill $_sshpid `cat $READY` 2>/dev/null wait_for_process_to_exit $_sshpid fi if test "x$_expected" = "xY" -a $_result -ne 0 ; then fail "check_rfwd failed (expecting success): $_message" elif test "x$_expected" = "xN" -a $_result -eq 0 ; then fail "check_rfwd succeeded (expecting failure): $_message" elif test "x$_expected" != "xY" -a "x$_expected" != "xN" ; then fatal "check_rfwd invalid argument \"$_expected\"" else verbose "check_rfwd done (expecting $_expected): $_message" fi } start_sshd cp ${OBJ}/sshd_proxy ${OBJ}/sshd_proxy.bak cp ${OBJ}/authorized_keys_${USER} ${OBJ}/authorized_keys_${USER}.bak # Sanity check: ensure the default config allows forwarding check_lfwd Y "default configuration" check_rfwd Y "default configuration" # Usage: all_tests yes|local|remote|no Y|N Y|N Y|N Y|N Y|N Y|N all_tests() { _tcpfwd=$1 _plain_lfwd=$2 _plain_rfwd=$3 _nopermit_lfwd=$4 _nopermit_rfwd=$5 _permit_lfwd=$6 _permit_rfwd=$7 _badfwd=127.0.0.1:22 _goodfwd=127.0.0.1:${PORT} cp ${OBJ}/authorized_keys_${USER}.bak ${OBJ}/authorized_keys_${USER} _prefix="AllowTcpForwarding=$_tcpfwd" # No PermitOpen ( cat ${OBJ}/sshd_proxy.bak ; echo "AllowTcpForwarding $_tcpfwd" ) \ > ${OBJ}/sshd_proxy check_lfwd $_plain_lfwd "$_prefix" check_rfwd $_plain_rfwd "$_prefix" # PermitOpen via sshd_config that doesn't match ( cat ${OBJ}/sshd_proxy.bak ; echo "AllowTcpForwarding $_tcpfwd" ; echo "PermitOpen $_badfwd" ) \ > ${OBJ}/sshd_proxy check_lfwd $_nopermit_lfwd "$_prefix, !PermitOpen" check_rfwd $_nopermit_rfwd "$_prefix, !PermitOpen" # PermitOpen via sshd_config that does match ( cat ${OBJ}/sshd_proxy.bak ; echo "AllowTcpForwarding $_tcpfwd" ; echo "PermitOpen $_badfwd $_goodfwd" ) \ > ${OBJ}/sshd_proxy # NB. permitopen via authorized_keys should have same # success/fail as via sshd_config # permitopen via authorized_keys that doesn't match sed "s/^/permitopen=\"$_badfwd\" /" \ < ${OBJ}/authorized_keys_${USER}.bak \ > ${OBJ}/authorized_keys_${USER} || fatal "sed 1 fail" ( cat ${OBJ}/sshd_proxy.bak ; echo "AllowTcpForwarding $_tcpfwd" ) \ > ${OBJ}/sshd_proxy check_lfwd $_nopermit_lfwd "$_prefix, !permitopen" check_rfwd $_nopermit_rfwd "$_prefix, !permitopen" # permitopen via authorized_keys that does match sed "s/^/permitopen=\"$_badfwd\",permitopen=\"$_goodfwd\" /" \ < ${OBJ}/authorized_keys_${USER}.bak \ > ${OBJ}/authorized_keys_${USER} || fatal "sed 2 fail" ( cat ${OBJ}/sshd_proxy.bak ; echo "AllowTcpForwarding $_tcpfwd" ) \ > ${OBJ}/sshd_proxy check_lfwd $_permit_lfwd "$_prefix, permitopen" check_rfwd $_permit_rfwd "$_prefix, permitopen" } # no-permitopen mismatch-permitopen match-permitopen # AllowTcpForwarding local remote local remote local remote all_tests yes Y Y N Y Y Y all_tests local Y N N N Y N all_tests remote N Y N Y N Y all_tests no N N N N N N