def check_daemon(pidfile):
global _pidname
_pidname = os.path.abspath(pidfile)
try:
oldpid = open(_pidname).read(1024)
except IOError as e:
if e.errno == errno.ENOENT:
return # no pidfile, ok
else:
raise Fatal("can't read %s: %s" % (_pidname, e))
if not oldpid:
os.unlink(_pidname)
return # invalid pidfile, ok
oldpid = int(oldpid.strip() or 0)
if oldpid <= 0:
os.unlink(_pidname)
return # invalid pidfile, ok
try:
os.kill(oldpid, 0)
except OSError as e:
if e.errno == errno.ESRCH:
os.unlink(_pidname)
return # outdated pidfile, ok
elif e.errno == errno.EPERM:
pass
else:
raise
raise Fatal("%s: tshuttle is already running (pid=%d)" %
(_pidname, oldpid))
def recv_udp(listener, bufsize):
debug3('Accept UDP using socket_ext recvmsg.')
srcip, data, adata, _ = listener.recvmsg((bufsize, ),
socket.CMSG_SPACE(24))
dstip = None
family = None
for a in adata:
if a.cmsg_level == socket.SOL_IP and a.cmsg_type == IP_ORIGDSTADDR:
family, port = struct.unpack('=HH', a.cmsg_data[0:4])
port = socket.htons(port)
if family == socket.AF_INET:
start = 4
length = 4
else:
raise Fatal("Unsupported socket type '%s'" % family)
ip = socket.inet_ntop(family,
a.cmsg_data[start:start + length])
dstip = (ip, port)
break
elif a.cmsg_level == SOL_IPV6 and a.cmsg_type == IPV6_ORIGDSTADDR:
family, port = struct.unpack('=HH', a.cmsg_data[0:4])
port = socket.htons(port)
if family == socket.AF_INET6:
start = 8
length = 16
else:
raise Fatal("Unsupported socket type '%s'" % family)
ip = socket.inet_ntop(family,
a.cmsg_data[start:start + length])
dstip = (ip, port)
break
return (srcip, dstip, data[0])
def __init__(self, method_name, sudo_pythonpath):
self.auto_nets = []
python_path = os.path.dirname(os.path.dirname(__file__))
argvbase = ([sys.executable, sys.argv[0]] + ['-v'] *
(helpers.verbose or 0) + ['--method', method_name] +
['--firewall'])
if ssyslog._p:
argvbase += ['--syslog']
# Determine how to prefix the command in order to elevate privileges.
if platform.platform().startswith('OpenBSD'):
elev_prefix = ['doas'] # OpenBSD uses built in `doas`
else:
elev_prefix = ['sudo', '-p', '[local sudo] Password: '******'/usr/bin/env', 'PYTHONPATH=%s' % python_path]
argv_tries = [elev_prefix + argvbase, argvbase]
# we can't use stdin/stdout=subprocess.PIPE here, as we normally would,
# because stupid Linux 'su' requires that stdin be attached to a tty.
# Instead, attach a *bidirectional* socket to its stdout, and use
# that for talking in both directions.
(s1, s2) = socket.socketpair()
def setup():
# run in the child process
s2.close()
if os.getuid() == 0:
argv_tries = argv_tries[-1:] # last entry only
for argv in argv_tries:
try:
if argv[0] == 'su':
sys.stderr.write('[local su] ')
self.p = ssubprocess.Popen(argv, stdout=s1, preexec_fn=setup)
# No env: Talking to `FirewallClient.start`, which has no i18n.
break
except OSError as e:
log('Spawning firewall manager: %r' % argv)
raise Fatal(e)
self.argv = argv
s1.close()
self.pfile = s2.makefile('rwb')
line = self.pfile.readline()
self.check()
if line[0:5] != b'READY':
raise Fatal('%r expected READY, got %r' % (self.argv, line))
method_name = line[6:-1]
self.method = get_method(method_name.decode("ASCII"))
self.method.set_firewall(self)
def _fill_oldctls(prefix):
argv = ['sysctl', prefix]
p = ssubprocess.Popen(argv, stdout=ssubprocess.PIPE, env=get_env())
for line in p.stdout:
line = line.decode()
assert (line[-1] == '\n')
(k, v) = line[:-1].split(': ', 1)
_oldctls[k] = v.strip()
rv = p.wait()
if rv:
raise Fatal('%r returned %d' % (argv, rv))
if not line:
raise Fatal('%r returned no data' % (argv, ))
def check_ssh_alive():
if daemon:
# poll() won't tell us when process exited since the
# process is no longer our child (it returns 0 all the
# time).
if not psutil.pid_exists(serverproc.pid):
raise Fatal('ssh connection to server (pid %d) exited.' %
serverproc.pid)
else:
rv = serverproc.poll()
# poll returns None if process hasn't exited.
if rv is not None:
raise Fatal('ssh connection to server (pid %d) exited '
'with returncode %d' % (serverproc.pid, rv))
def ipfw_rule_exists(n):
argv = ['ipfw', 'list']
p = ssubprocess.Popen(argv, stdout=ssubprocess.PIPE, env=get_env())
found = False
for line in p.stdout:
if line.startswith(b'%05d ' % n):
if not ('ipttl 63' in line or 'check-state' in line):
log('non-tshuttle ipfw rule: %r' % line.strip())
raise Fatal('non-tshuttle ipfw rule #%d already exists!' % n)
found = True
rv = p.wait()
if rv:
raise Fatal('%r returned %d' % (argv, rv))
return found
def start(self):
self.pfile.write(b'ROUTES\n')
for (family, ip, width, fport, lport) \
in self.subnets_include + self.auto_nets:
self.pfile.write(b'%d,%d,0,%s,%d,%d\n' %
(family, width, ip.encode("ASCII"), fport, lport))
for (family, ip, width, fport, lport) in self.subnets_exclude:
self.pfile.write(b'%d,%d,1,%s,%d,%d\n' %
(family, width, ip.encode("ASCII"), fport, lport))
self.pfile.write(b'NSLIST\n')
for (family, ip) in self.nslist:
self.pfile.write(b'%d,%s\n' % (family, ip.encode("ASCII")))
self.pfile.write(b'PORTS %d,%d,%d,%d\n' %
(self.redirectport_v6, self.redirectport_v4,
self.dnsport_v6, self.dnsport_v4))
udp = 0
if self.udp:
udp = 1
if self.user is None:
user = b'-'
elif isinstance(self.user, str):
user = bytes(self.user, 'utf-8')
else:
user = b'%d' % self.user
self.pfile.write(b'GO %d %s\n' % (udp, user))
self.pfile.flush()
line = self.pfile.readline()
self.check()
if line != b'STARTED\n':
raise Fatal('%r expected STARTED, got %r' % (self.argv, line))
def assert_features(self, features):
avail = self.get_supported_features()
for key in ["udp", "dns", "ipv6", "ipv4", "user"]:
if getattr(features, key) and not getattr(avail, key):
raise Fatal(
"Feature %s not supported with method %s." %
(key, self.name))
def runonce(handlers, mux):
r = []
w = []
x = []
to_remove = [s for s in handlers if not s.ok]
for h in to_remove:
handlers.remove(h)
for s in handlers:
s.pre_select(r, w, x)
debug2(
'Waiting: %d r=%r w=%r x=%r (fullness=%d/%d)' %
(len(handlers), _fds(r), _fds(w), _fds(x), mux.fullness, mux.too_full))
(r, w, x) = select.select(r, w, x)
debug2(' Ready: %d r=%r w=%r x=%r' %
(len(handlers), _fds(r), _fds(w), _fds(x)))
ready = r + w + x
did = {}
for h in handlers:
for s in h.socks:
if s in ready:
h.callback(s)
did[s] = 1
for s in ready:
if s not in did:
raise Fatal('socket %r was not used by any handler' % s)
def ipfw(*args):
argv = ['ipfw', '-q'] + list(args)
debug1('>> %s' % ' '.join(argv))
rv = ssubprocess.call(argv, env=get_env())
# No env: No output. (Or error that won't be parsed.)
if rv:
raise Fatal('%r returned %d' % (argv, rv))
def nft(family, table, action, *args):
if family in (socket.AF_INET, socket.AF_INET6):
argv = ['nft', action, 'inet', table] + list(args)
else:
raise Exception('Unsupported family "%s"' % family_to_string(family))
debug1('%s' % ' '.join(argv))
rv = ssubprocess.call(argv, env=get_env())
if rv:
raise Fatal('%r returned %d' % (argv, rv))
def ipt(family, table, *args):
if family == socket.AF_INET6:
argv = ['ip6tables', '-t', table] + list(args)
elif family == socket.AF_INET:
argv = ['iptables', '-t', table] + list(args)
else:
raise Exception('Unsupported family "%s"' % family_to_string(family))
debug1('%s' % ' '.join(argv))
rv = ssubprocess.call(argv, env=get_env())
if rv:
raise Fatal('%r returned %d' % (argv, rv))
def udp_open(channel, data):
debug2('Incoming UDP open.')
family = int(data)
mux.channels[channel] = lambda cmd, data: udp_req(channel, cmd,
data)
if channel in udphandlers:
raise Fatal('UDP connection channel %d already open' %
channel)
else:
h = UdpProxy(mux, channel, family)
handlers.append(h)
udphandlers[channel] = h
def pfctl(args, stdin=None):
argv = ['pfctl'] + shlex.split(args)
debug1('>> %s' % ' '.join(argv))
p = ssubprocess.Popen(argv,
stdin=ssubprocess.PIPE,
stdout=ssubprocess.PIPE,
stderr=ssubprocess.PIPE,
env=get_env())
o = p.communicate(stdin)
if p.returncode:
raise Fatal('%r returned %d' % (argv, p.returncode))
return o
def get_auto_method():
debug3("Selecting a method automatically...")
# Try these methods, in order:
methods_to_try = ["nat", "nft", "pf", "ipfw"]
for m in methods_to_try:
method = get_method(m)
if method.is_supported():
debug3("Method '%s' was automatically selected." % m)
return method
raise Fatal("Unable to automatically find a supported method. Check that "
"the appropriate programs are in your PATH. We tried "
"methods: %s" % str(methods_to_try))
def hostwatch_ready(sock):
assert(hw.pid)
content = hw.sock.recv(4096)
if content:
lines = (hw.leftover + content).split(b('\n'))
if lines[-1]:
# no terminating newline: entry isn't complete yet!
hw.leftover = lines.pop()
lines.append(b(''))
else:
hw.leftover = b('')
mux.send(0, ssnet.CMD_HOST_LIST, b('\n').join(lines))
else:
raise Fatal('hostwatch process died')
def ipt_chain_exists(family, table, name):
if family == socket.AF_INET6:
cmd = 'ip6tables'
elif family == socket.AF_INET:
cmd = 'iptables'
else:
raise Exception('Unsupported family "%s"' % family_to_string(family))
argv = [cmd, '-t', table, '-nL']
try:
output = ssubprocess.check_output(argv, env=get_env())
for line in output.decode('ASCII').split('\n'):
if line.startswith('Chain %s ' % name):
return True
except ssubprocess.CalledProcessError as e:
raise Fatal('%r returned %d' % (argv, e.returncode))
def fill(self):
try:
os.set_blocking(self.rfile.fileno(), False)
except AttributeError:
# python < 3.5
flags = fcntl.fcntl(self.rfile.fileno(), fcntl.F_GETFL)
flags |= os.O_NONBLOCK
flags = fcntl.fcntl(self.rfile.fileno(), fcntl.F_SETFL, flags)
try:
# If LATENCY_BUFFER_SIZE is inappropriately large, we will
# get a MemoryError here. Read no more than 1MiB.
read = _nb_clean(os.read, self.rfile.fileno(),
min(1048576, LATENCY_BUFFER_SIZE))
except OSError:
_, e = sys.exc_info()[:2]
raise Fatal('other end: %r' % e)
# log('<<< %r' % b)
if read == b(''): # EOF
self.ok = False
if read:
self.inbuf += read
def setup_daemon():
if os.getuid() != 0:
raise Fatal('You must be root (or enable su/sudo) to set the firewall')
# don't disappear if our controlling terminal or stdout/stderr
# disappears; we still have to clean up.
signal.signal(signal.SIGHUP, signal.SIG_IGN)
signal.signal(signal.SIGPIPE, signal.SIG_IGN)
signal.signal(signal.SIGTERM, signal.SIG_IGN)
signal.signal(signal.SIGINT, signal.SIG_IGN)
# ctrl-c shouldn't be passed along to me. When the main tshuttle dies,
# I'll die automatically.
os.setsid()
# because of limitations of the 'su' command, the *real* stdin/stdout
# are both attached to stdout initially. Clone stdout into stdin so we
# can read from it.
os.dup2(1, 0)
return sys.stdin, sys.stdout
def original_dst(sock):
ip = "0.0.0.0"
port = -1
try:
family = sock.family
SO_ORIGINAL_DST = 80
if family == socket.AF_INET:
SOCKADDR_MIN = 16
sockaddr_in = sock.getsockopt(socket.SOL_IP,
SO_ORIGINAL_DST, SOCKADDR_MIN)
port, raw_ip = struct.unpack_from('!2xH4s', sockaddr_in[:8])
ip = str(ipaddress.IPv4Address(raw_ip))
elif family == socket.AF_INET6:
sockaddr_in = sock.getsockopt(41, SO_ORIGINAL_DST, 64)
port, raw_ip = struct.unpack_from("!2xH4x16s", sockaddr_in)
ip = str(ipaddress.IPv6Address(raw_ip))
else:
raise Fatal("fw: Unknown family type.")
except socket.error as e:
if e.args[0] == errno.ENOPROTOOPT:
return sock.getsockname()
raise
return (ip, port)
def main(latency_control, latency_buffer_size, auto_hosts, to_nameserver,
auto_nets):
try:
helpers.logprefix = ' s: '
debug1('Starting server with Python version %s'
% platform.python_version())
debug1('latency control setting = %r' % latency_control)
if latency_buffer_size:
import tshuttle.ssnet as ssnet
ssnet.LATENCY_BUFFER_SIZE = latency_buffer_size
# synchronization header
sys.stdout.write('\0\0SSHUTTLE0001')
sys.stdout.flush()
handlers = []
mux = Mux(sys.stdin, sys.stdout)
handlers.append(mux)
debug1('auto-nets:' + str(auto_nets))
if auto_nets:
routes = list(list_routes())
debug1('available routes:')
for r in routes:
debug1(' %d/%s/%d' % r)
else:
routes = []
routepkt = ''
for r in routes:
routepkt += '%d,%s,%d\n' % r
mux.send(0, ssnet.CMD_ROUTES, b(routepkt))
hw = Hostwatch()
hw.leftover = b('')
def hostwatch_ready(sock):
assert(hw.pid)
content = hw.sock.recv(4096)
if content:
lines = (hw.leftover + content).split(b('\n'))
if lines[-1]:
# no terminating newline: entry isn't complete yet!
hw.leftover = lines.pop()
lines.append(b(''))
else:
hw.leftover = b('')
mux.send(0, ssnet.CMD_HOST_LIST, b('\n').join(lines))
else:
raise Fatal('hostwatch process died')
def got_host_req(data):
if not hw.pid:
(hw.pid, hw.sock) = start_hostwatch(
data.decode("ASCII").strip().split(), auto_hosts)
handlers.append(Handler(socks=[hw.sock],
callback=hostwatch_ready))
mux.got_host_req = got_host_req
def new_channel(channel, data):
(family, dstip, dstport) = data.decode("ASCII").split(',', 2)
family = int(family)
# AF_INET is the same constant on Linux and BSD but AF_INET6
# is different. As the client and server can be running on
# different platforms we can not just set the socket family
# to what comes in the wire.
if family != socket.AF_INET:
family = socket.AF_INET6
dstport = int(dstport)
outwrap = ssnet.connect_dst(family, dstip, dstport)
handlers.append(Proxy(MuxWrapper(mux, channel), outwrap))
mux.new_channel = new_channel
dnshandlers = {}
def dns_req(channel, data):
debug2('Incoming DNS request channel=%d.' % channel)
h = DnsProxy(mux, channel, data, to_nameserver)
handlers.append(h)
dnshandlers[channel] = h
mux.got_dns_req = dns_req
udphandlers = {}
def udp_req(channel, cmd, data):
debug2('Incoming UDP request channel=%d, cmd=%d' %
(channel, cmd))
if cmd == ssnet.CMD_UDP_DATA:
(dstip, dstport, data) = data.split(b(','), 2)
dstport = int(dstport)
debug2('is incoming UDP data. %r %d.' % (dstip, dstport))
h = udphandlers[channel]
h.send((dstip, dstport), data)
elif cmd == ssnet.CMD_UDP_CLOSE:
debug2('is incoming UDP close')
h = udphandlers[channel]
h.ok = False
del mux.channels[channel]
def udp_open(channel, data):
debug2('Incoming UDP open.')
family = int(data)
mux.channels[channel] = lambda cmd, data: udp_req(channel, cmd,
data)
if channel in udphandlers:
raise Fatal('UDP connection channel %d already open' %
channel)
else:
h = UdpProxy(mux, channel, family)
handlers.append(h)
udphandlers[channel] = h
mux.got_udp_open = udp_open
while mux.ok:
if hw.pid:
assert(hw.pid > 0)
(rpid, rv) = os.waitpid(hw.pid, os.WNOHANG)
if rpid:
raise Fatal(
'hostwatch exited unexpectedly: code 0x%04x' % rv)
ssnet.runonce(handlers, mux)
if latency_control:
mux.check_fullness()
if dnshandlers:
now = time.time()
remove = []
for channel, h in dnshandlers.items():
if h.timeout < now or not h.ok:
debug3('expiring dnsreqs channel=%d' % channel)
remove.append(channel)
h.ok = False
for channel in remove:
del dnshandlers[channel]
if udphandlers:
remove = []
for channel, h in udphandlers.items():
if not h.ok:
debug3('expiring UDP channel=%d' % channel)
remove.append(channel)
h.ok = False
for channel in remove:
del udphandlers[channel]
except Fatal as e:
log('fatal: %s' % e)
sys.exit(99)
def main(method_name, syslog):
helpers.logprefix = 'fw: '
stdin, stdout = setup_daemon()
hostmap = {}
debug1('Starting firewall with Python version %s' %
platform.python_version())
if method_name == "auto":
method = get_auto_method()
else:
method = get_method(method_name)
if syslog:
ssyslog.start_syslog()
ssyslog.stderr_to_syslog()
if not method.is_supported():
raise Fatal("The %s method is not supported on this machine. "
"Check that the appropriate programs are in your "
"PATH." % method_name)
debug1('ready method name %s.' % method.name)
stdout.write('READY %s\n' % method.name)
stdout.flush()
# we wait until we get some input before creating the rules. That way,
# tshuttle can launch us as early as possible (and get sudo password
# authentication as early in the startup process as possible).
line = stdin.readline(128)
if not line:
return # parent died; nothing to do
subnets = []
if line != 'ROUTES\n':
raise Fatal('expected ROUTES but got %r' % line)
while 1:
line = stdin.readline(128)
if not line:
raise Fatal('expected route but got %r' % line)
elif line.startswith("NSLIST\n"):
break
try:
(family, width, exclude, ip, fport, lport) = \
line.strip().split(',', 5)
except BaseException:
raise Fatal('expected route or NSLIST but got %r' % line)
subnets.append((int(family), int(width), bool(int(exclude)), ip,
int(fport), int(lport)))
debug2('Got subnets: %r' % subnets)
nslist = []
if line != 'NSLIST\n':
raise Fatal('expected NSLIST but got %r' % line)
while 1:
line = stdin.readline(128)
if not line:
raise Fatal('expected nslist but got %r' % line)
elif line.startswith("PORTS "):
break
try:
(family, ip) = line.strip().split(',', 1)
except BaseException:
raise Fatal('expected nslist or PORTS but got %r' % line)
nslist.append((int(family), ip))
debug2('Got partial nslist: %r' % nslist)
debug2('Got nslist: %r' % nslist)
if not line.startswith('PORTS '):
raise Fatal('expected PORTS but got %r' % line)
_, _, ports = line.partition(" ")
ports = ports.split(",")
if len(ports) != 4:
raise Fatal('expected 4 ports but got %d' % len(ports))
port_v6 = int(ports[0])
port_v4 = int(ports[1])
dnsport_v6 = int(ports[2])
dnsport_v4 = int(ports[3])
assert (port_v6 >= 0)
assert (port_v6 <= 65535)
assert (port_v4 >= 0)
assert (port_v4 <= 65535)
assert (dnsport_v6 >= 0)
assert (dnsport_v6 <= 65535)
assert (dnsport_v4 >= 0)
assert (dnsport_v4 <= 65535)
debug2('Got ports: %d,%d,%d,%d' %
(port_v6, port_v4, dnsport_v6, dnsport_v4))
line = stdin.readline(128)
if not line:
raise Fatal('expected GO but got %r' % line)
elif not line.startswith("GO "):
raise Fatal('expected GO but got %r' % line)
_, _, args = line.partition(" ")
udp, user = args.strip().split(" ", 1)
udp = bool(int(udp))
if user == '-':
user = None
debug2('Got udp: %r, user: %r' % (udp, user))
subnets_v6 = [i for i in subnets if i[0] == socket.AF_INET6]
nslist_v6 = [i for i in nslist if i[0] == socket.AF_INET6]
subnets_v4 = [i for i in subnets if i[0] == socket.AF_INET]
nslist_v4 = [i for i in nslist if i[0] == socket.AF_INET]
try:
debug1('setting up.')
if subnets_v6 or nslist_v6:
debug2('setting up IPv6.')
method.setup_firewall(port_v6, dnsport_v6, nslist_v6,
socket.AF_INET6, subnets_v6, udp, user)
if subnets_v4 or nslist_v4:
debug2('setting up IPv4.')
method.setup_firewall(port_v4, dnsport_v4, nslist_v4,
socket.AF_INET, subnets_v4, udp, user)
stdout.write('STARTED\n')
try:
stdout.flush()
except IOError:
# the parent process died for some reason; he's surely been loud
# enough, so no reason to report another error
return
# Now we wait until EOF or any other kind of exception. We need
# to stay running so that we don't need a *second* password
# authentication at shutdown time - that cleanup is important!
while 1:
line = stdin.readline(128)
if line.startswith('HOST '):
(name, ip) = line[5:].strip().split(',', 1)
hostmap[name] = ip
debug2('setting up /etc/hosts.')
rewrite_etc_hosts(hostmap, port_v6 or port_v4)
elif line:
if not method.firewall_command(line):
raise Fatal('expected command, got %r' % line)
else:
break
finally:
try:
debug1('undoing changes.')
except BaseException:
debug2('An error occurred, ignoring it.')
try:
if subnets_v6 or nslist_v6:
debug2('undoing IPv6 changes.')
method.restore_firewall(port_v6, socket.AF_INET6, udp, user)
except BaseException:
try:
debug1("Error trying to undo IPv6 firewall.")
debug1(traceback.format_exc())
except BaseException:
debug2('An error occurred, ignoring it.')
try:
if subnets_v4 or nslist_v4:
debug2('undoing IPv4 changes.')
method.restore_firewall(port_v4, socket.AF_INET, udp, user)
except BaseException:
try:
debug1("Error trying to undo IPv4 firewall.")
debug1(traceback.format_exc())
except BaseException:
debug2('An error occurred, ignoring it.')
try:
# debug2() message printed in restore_etc_hosts() function.
restore_etc_hosts(hostmap, port_v6 or port_v4)
except BaseException:
try:
debug1("Error trying to undo /etc/hosts changes.")
debug1(traceback.format_exc())
except BaseException:
debug2('An error occurred, ignoring it.')
def send_udp(self, sock, srcip, dstip, data):
if srcip is not None:
Fatal("Method %s send_udp does not support setting srcip to %r"
% (self.name, srcip))
sock.sendto(data, dstip)
def check(self):
rv = self.p.poll()
if rv:
raise Fatal('%r returned %d' % (self.argv, rv))
def done(self):
self.pfile.close()
rv = self.p.wait()
if rv:
raise Fatal('cleanup: %r returned %d' % (self.argv, rv))
def _main(tcp_listener, udp_listener, fw, ssh_cmd, remotename, python,
latency_control, latency_buffer_size, dns_listener, seed_hosts,
auto_hosts, auto_nets, daemon, to_nameserver):
helpers.logprefix = 'c : '
debug1('Starting client with Python version %s' %
platform.python_version())
method = fw.method
handlers = []
debug1('Connecting to server...')
try:
(serverproc, serversock) = ssh.connect(
ssh_cmd,
remotename,
python,
stderr=ssyslog._p and ssyslog._p.stdin,
options=dict(latency_control=latency_control,
latency_buffer_size=latency_buffer_size,
auto_hosts=auto_hosts,
to_nameserver=to_nameserver,
auto_nets=auto_nets))
except socket.error as e:
if e.args[0] == errno.EPIPE:
raise Fatal("failed to establish ssh session (1)")
else:
raise
mux = Mux(serversock.makefile("rb"), serversock.makefile("wb"))
handlers.append(mux)
expected = b'SSHUTTLE0001'
try:
v = 'x'
while v and v != b'\0':
v = serversock.recv(1)
v = 'x'
while v and v != b'\0':
v = serversock.recv(1)
initstring = serversock.recv(len(expected))
except socket.error as e:
if e.args[0] == errno.ECONNRESET:
raise Fatal("failed to establish ssh session (2)")
else:
raise
# Returns None if process is still running (or returns exit code)
rv = serverproc.poll()
if rv is not None:
errmsg = "server died with error code %d\n" % rv
# Our fatal exceptions return exit code 99
if rv == 99:
errmsg += "This error code likely means that python started and " \
"the tshuttle server started. However, the tshuttle server " \
"may have raised a 'Fatal' exception after it started."
elif rv == 98:
errmsg += "This error code likely means that we were able to " \
"run python on the server, but that the program continued " \
"to the line after we call python's exec() to execute " \
"tshuttle's server code. Try specifying the python " \
"executable to user on the server by passing --python " \
"to tshuttle."
# This error should only be possible when --python is not specified.
elif rv == 97 and not python:
errmsg += "This error code likely means that either we " \
"couldn't find python3 or python in the PATH on the " \
"server or that we do not have permission to run 'exec' in " \
"the /bin/sh shell on the server. Try specifying the " \
"python executable to use on the server by passing " \
"--python to tshuttle."
# POSIX sh standards says error code 127 is used when you try
# to execute a program that does not exist. See section 2.8.2
# of
# https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_08
elif rv == 127:
if python:
errmsg += "This error code likely means that we were not " \
"able to execute the python executable that specified " \
"with --python. You specified '%s'.\n" % python
if python.startswith("/"):
errmsg += "\nTip for users in a restricted shell on the " \
"server: The server may refuse to run programs " \
"specified with an absolute path. Try specifying " \
"just the name of the python executable. However, " \
"if python is not in your PATH and you cannot " \
"run programs specified with an absolute path, " \
"it is possible that tshuttle will not work."
else:
errmsg += "This error code likely means that we were unable " \
"to execute /bin/sh on the remote server. This can " \
"happen if /bin/sh does not exist on the server or if " \
"you are in a restricted shell that does not allow you " \
"to run programs specified with an absolute path. " \
"Try rerunning tshuttle with the --python parameter."
# When the redirected subnet includes the remote ssh host, the
# firewall rules can interrupt the ssh connection to the
# remote machine. This issue impacts some Linux machines. The
# user sees that the server dies with a broken pipe error and
# code 255.
#
# The solution to this problem is to exclude the remote
# server.
#
# There are many github issues from users encountering this
# problem. Most of the discussion on the topic is here:
# https://github.com/tshuttle/tshuttle/issues/191
elif rv == 255:
errmsg += "It might be possible to resolve this error by " \
"excluding the server that you are ssh'ing to. For example, " \
"if you are running 'tshuttle -v -r example.com 0/0' to " \
"redirect all traffic through example.com, then try " \
"'tshuttle -v -r example.com -x example.com 0/0' to " \
"exclude redirecting the connection to example.com itself " \
"(i.e., tshuttle's firewall rules may be breaking the " \
"ssh connection that it previously established). " \
"Alternatively, you may be able to use 'tshuttle -v -r " \
"example.com -x example.com:22 0/0' to redirect " \
"everything except ssh connections between your machine " \
"and example.com."
raise Fatal(errmsg)
if initstring != expected:
raise Fatal('expected server init string %r; got %r' %
(expected, initstring))
log('Connected to server.')
sys.stdout.flush()
if daemon:
daemonize()
log('daemonizing (%s).' % _pidname)
def onroutes(routestr):
if auto_nets:
for line in routestr.strip().split(b'\n'):
if not line:
continue
(family, ip, width) = line.split(b',', 2)
family = int(family)
width = int(width)
ip = ip.decode("ASCII")
if family == socket.AF_INET6 and tcp_listener.v6 is None:
debug2("Ignored auto net %d/%s/%d" % (family, ip, width))
if family == socket.AF_INET and tcp_listener.v4 is None:
debug2("Ignored auto net %d/%s/%d" % (family, ip, width))
else:
debug2("Adding auto net %d/%s/%d" % (family, ip, width))
fw.auto_nets.append((family, ip, width, 0, 0))
# we definitely want to do this *after* starting ssh, or we might end
# up intercepting the ssh connection!
#
# Moreover, now that we have the --auto-nets option, we have to wait
# for the server to send us that message anyway. Even if we haven't
# set --auto-nets, we might as well wait for the message first, then
# ignore its contents.
mux.got_routes = None
serverready()
mux.got_routes = onroutes
def serverready():
fw.start()
sdnotify.send(sdnotify.ready(), sdnotify.status('Connected'))
def onhostlist(hostlist):
debug2('got host list: %r' % hostlist)
for line in hostlist.strip().split():
if line:
name, ip = line.split(b',', 1)
fw.sethostip(name, ip)
mux.got_host_list = onhostlist
tcp_listener.add_handler(handlers, onaccept_tcp, method, mux)
if udp_listener:
udp_listener.add_handler(handlers, onaccept_udp, method, mux)
if dns_listener:
dns_listener.add_handler(handlers, ondns, method, mux)
if seed_hosts is not None:
debug1('seed_hosts: %r' % seed_hosts)
mux.send(0, ssnet.CMD_HOST_REQ, str.encode('\n'.join(seed_hosts)))
def check_ssh_alive():
if daemon:
# poll() won't tell us when process exited since the
# process is no longer our child (it returns 0 all the
# time).
if not psutil.pid_exists(serverproc.pid):
raise Fatal('ssh connection to server (pid %d) exited.' %
serverproc.pid)
else:
rv = serverproc.poll()
# poll returns None if process hasn't exited.
if rv is not None:
raise Fatal('ssh connection to server (pid %d) exited '
'with returncode %d' % (serverproc.pid, rv))
while 1:
check_ssh_alive()
ssnet.runonce(handlers, mux)
if latency_control:
mux.check_fullness()
def main(listenip_v6, listenip_v4, ssh_cmd, remotename, python,
latency_control, latency_buffer_size, dns, nslist, method_name,
seed_hosts, auto_hosts, auto_nets, subnets_include, subnets_exclude,
daemon, to_nameserver, pidfile, user, sudo_pythonpath, tmark):
if not remotename:
print("WARNING: You must specify -r/--remote to securely route "
"traffic to a remote machine. Running without -r/--remote "
"is only recommended for testing.")
if daemon:
try:
check_daemon(pidfile)
except Fatal as e:
log("%s" % e)
return 5
debug1('Starting tshuttle proxy (version %s).' % __version__)
helpers.logprefix = 'c : '
fw = FirewallClient(method_name, sudo_pythonpath)
# If --dns is used, store the IP addresses that the client
# normally uses for DNS lookups in nslist. The firewall needs to
# redirect packets outgoing to this server to the remote host
# instead.
if dns:
nslist += resolvconf_nameservers(True)
if to_nameserver is not None:
to_nameserver = "%s@%s" % tuple(to_nameserver[1:])
else:
# option doesn't make sense if we aren't proxying dns
if to_nameserver and len(to_nameserver) > 0:
print("WARNING: --to-ns option is ignored because --dns was not "
"used.")
to_nameserver = None
# Get family specific subnet lists. Also, the user may not specify
# any subnets if they use --auto-nets. In this case, our subnets
# list will be empty and the forwarded subnets will be determined
# later by the server.
subnets_v4 = [i for i in subnets_include if i[0] == socket.AF_INET]
subnets_v6 = [i for i in subnets_include if i[0] == socket.AF_INET6]
nslist_v4 = [i for i in nslist if i[0] == socket.AF_INET]
nslist_v6 = [i for i in nslist if i[0] == socket.AF_INET6]
# Get available features from the firewall method
avail = fw.method.get_supported_features()
# A feature is "required" if the user supplies us parameters which
# implies that the feature is needed.
required = Features()
# Select the default addresses to bind to / listen to.
# Assume IPv4 is always available and should always be enabled. If
# a method doesn't provide IPv4 support or if we wish to run
# ipv6-only, changes to this code are required.
assert avail.ipv4
required.ipv4 = True
# listenip_v4 contains user specified value or it is set to "auto".
if listenip_v4 == "auto":
listenip_v4 = ('127.0.0.1', 0)
# listenip_v6 is...
# None when IPv6 is disabled.
# "auto" when listen address is unspecified.
# The user specified address if provided by user
if listenip_v6 is None:
debug1("IPv6 disabled by --disable-ipv6")
if listenip_v6 == "auto":
if avail.ipv6:
debug1("IPv6 enabled: Using default IPv6 listen address ::1")
listenip_v6 = ('::1', 0)
else:
debug1("IPv6 disabled since it isn't supported by method "
"%s." % fw.method.name)
listenip_v6 = None
# Make final decision about enabling IPv6:
required.ipv6 = False
if listenip_v6:
required.ipv6 = True
# If we get here, it is possible that listenip_v6 was user
# specified but not supported by the current method.
if required.ipv6 and not avail.ipv6:
raise Fatal("An IPv6 listen address was supplied, but IPv6 is "
"disabled at your request or is unsupported by the %s "
"method." % fw.method.name)
if user is not None:
if getpwnam is None:
raise Fatal("Routing by user not available on this system.")
try:
user = getpwnam(user).pw_uid
except KeyError:
raise Fatal("User %s does not exist." % user)
required.user = False if user is None else True
if not required.ipv6 and len(subnets_v6) > 0:
print("WARNING: IPv6 subnets were ignored because IPv6 is disabled "
"in tshuttle.")
subnets_v6 = []
subnets_include = subnets_v4
required.udp = avail.udp # automatically enable UDP if it is available
required.dns = len(nslist) > 0
# Remove DNS servers using IPv6.
if required.dns:
if not required.ipv6 and len(nslist_v6) > 0:
print("WARNING: Your system is configured to use an IPv6 DNS "
"server but tshuttle is not using IPv6. Therefore DNS "
"traffic your system sends to the IPv6 DNS server won't "
"be redirected via tshuttle to the remote machine.")
nslist_v6 = []
nslist = nslist_v4
if len(nslist) == 0:
raise Fatal("Can't redirect DNS traffic since IPv6 is not "
"enabled in tshuttle and all of the system DNS "
"servers are IPv6.")
# If we aren't using IPv6, we can safely ignore excluded IPv6 subnets.
if not required.ipv6:
orig_len = len(subnets_exclude)
subnets_exclude = [
i for i in subnets_exclude if i[0] == socket.AF_INET
]
if len(subnets_exclude) < orig_len:
print("WARNING: Ignoring one or more excluded IPv6 subnets "
"because IPv6 is not enabled.")
# This will print error messages if we required a feature that
# isn't available by the current method.
fw.method.assert_features(required)
# display features enabled
def feature_status(label, enabled, available):
msg = label + ": "
if enabled:
msg += "on"
else:
msg += "off "
if available:
msg += "(available)"
else:
msg += "(not available with %s method)" % fw.method.name
debug1(msg)
debug1("Method: %s" % fw.method.name)
feature_status("IPv4", required.ipv4, avail.ipv4)
feature_status("IPv6", required.ipv6, avail.ipv6)
feature_status("UDP ", required.udp, avail.udp)
feature_status("DNS ", required.dns, avail.dns)
feature_status("User", required.user, avail.user)
# Exclude traffic destined to our listen addresses.
if required.ipv4 and \
not any(listenip_v4[0] == sex[1] for sex in subnets_v4):
subnets_exclude.append((socket.AF_INET, listenip_v4[0], 32, 0, 0))
if required.ipv6 and \
not any(listenip_v6[0] == sex[1] for sex in subnets_v6):
subnets_exclude.append((socket.AF_INET6, listenip_v6[0], 128, 0, 0))
# We don't print the IP+port of where we are listening here
# because we do that below when we have identified the ports to
# listen on.
debug1("Subnets to forward through remote host (type, IP, cidr mask "
"width, startPort, endPort):")
for i in subnets_include:
debug1(" " + str(i))
if auto_nets:
debug1("NOTE: Additional subnets to forward may be added below by "
"--auto-nets.")
debug1("Subnets to exclude from forwarding:")
for i in subnets_exclude:
debug1(" " + str(i))
if required.dns:
debug1("DNS requests normally directed at these servers will be "
"redirected to remote:")
for i in nslist:
debug1(" " + str(i))
if listenip_v6 and listenip_v6[1] and listenip_v4 and listenip_v4[1]:
# if both ports given, no need to search for a spare port
ports = [
0,
]
else:
# if at least one port missing, we have to search
ports = range(12300, 9000, -1)
# keep track of failed bindings and used ports to avoid trying to
# bind to the same socket address twice in different listeners
used_ports = []
# search for free ports and try to bind
last_e = None
redirectport_v6 = 0
redirectport_v4 = 0
bound = False
for port in ports:
debug2('Trying to bind redirector on port %d' % port)
tcp_listener = MultiListener()
if required.udp:
udp_listener = MultiListener(socket.SOCK_DGRAM)
else:
udp_listener = None
if listenip_v6 and listenip_v6[1]:
lv6 = listenip_v6
redirectport_v6 = lv6[1]
elif listenip_v6:
lv6 = (listenip_v6[0], port)
redirectport_v6 = port
else:
lv6 = None
redirectport_v6 = 0
if listenip_v4 and listenip_v4[1]:
lv4 = listenip_v4
redirectport_v4 = lv4[1]
elif listenip_v4:
lv4 = (listenip_v4[0], port)
redirectport_v4 = port
else:
lv4 = None
redirectport_v4 = 0
try:
tcp_listener.bind(lv6, lv4)
if udp_listener:
udp_listener.bind(lv6, lv4)
bound = True
used_ports.append(port)
break
except socket.error as e:
if e.errno == errno.EADDRINUSE:
last_e = e
used_ports.append(port)
else:
raise e
if not bound:
assert (last_e)
raise last_e
tcp_listener.listen(10)
tcp_listener.print_listening("TCP redirector")
if udp_listener:
udp_listener.print_listening("UDP redirector")
bound = False
if required.dns:
# search for spare port for DNS
ports = range(12300, 9000, -1)
for port in ports:
debug2('Trying to bind DNS redirector on port %d' % port)
if port in used_ports:
continue
dns_listener = MultiListener(socket.SOCK_DGRAM)
if listenip_v6:
lv6 = (listenip_v6[0], port)
dnsport_v6 = port
else:
lv6 = None
dnsport_v6 = 0
if listenip_v4:
lv4 = (listenip_v4[0], port)
dnsport_v4 = port
else:
lv4 = None
dnsport_v4 = 0
try:
dns_listener.bind(lv6, lv4)
bound = True
used_ports.append(port)
break
except socket.error as e:
if e.errno == errno.EADDRINUSE:
last_e = e
used_ports.append(port)
else:
raise e
dns_listener.print_listening("DNS")
if not bound:
assert (last_e)
raise last_e
else:
dnsport_v6 = 0
dnsport_v4 = 0
dns_listener = None
# Last minute sanity checks.
# These should never fail.
# If these do fail, something is broken above.
if subnets_v6:
assert required.ipv6
if redirectport_v6 == 0:
raise Fatal("IPv6 subnets defined but not listening")
if nslist_v6:
assert required.dns
assert required.ipv6
if dnsport_v6 == 0:
raise Fatal("IPv6 ns servers defined but not listening")
if subnets_v4:
if redirectport_v4 == 0:
raise Fatal("IPv4 subnets defined but not listening")
if nslist_v4:
if dnsport_v4 == 0:
raise Fatal("IPv4 ns servers defined but not listening")
# setup method specific stuff on listeners
fw.method.setup_tcp_listener(tcp_listener)
if udp_listener:
fw.method.setup_udp_listener(udp_listener)
if dns_listener:
fw.method.setup_udp_listener(dns_listener)
# start the firewall
fw.setup(subnets_include, subnets_exclude, nslist, redirectport_v6,
redirectport_v4, dnsport_v6, dnsport_v4, required.udp, user,
tmark)
# Add routes to avoid Cico VPN issue
for subnet_info in subnets_include:
cidr = subnet_info[1] + "/" + str(subnet_info[2])
try:
ssubprocess.run('sudo route -n add -net ' + cidr +
' -interface en0',
check=True,
shell=True)
except ssubprocess.CalledProcessError:
print('Failed to add ' + cidr)
# start the client process
try:
return _main(tcp_listener, udp_listener, fw, ssh_cmd, remotename,
python, latency_control, latency_buffer_size,
dns_listener, seed_hosts, auto_hosts, auto_nets, daemon,
to_nameserver)
finally:
try:
if daemon:
# it's not our child anymore; can't waitpid
fw.p.returncode = 0
fw.done()
sdnotify.send(sdnotify.stop())
finally:
if daemon:
daemon_cleanup()
def connect(ssh_cmd, rhostport, python, stderr, options):
username, password, port, host = parse_hostport(rhostport)
if username:
rhost = "{}@{}".format(username, host)
else:
rhost = host
z = zlib.compressobj(1)
content = get_module_source('tshuttle.assembler')
optdata = ''.join("%s=%r\n" % (k, v) for (k, v) in list(options.items()))
optdata = optdata.encode("UTF8")
content2 = (empackage(z, 'tshuttle') +
empackage(z, 'tshuttle.cmdline_options', optdata) +
empackage(z, 'tshuttle.helpers') +
empackage(z, 'tshuttle.ssnet') +
empackage(z, 'tshuttle.hostwatch') +
empackage(z, 'tshuttle.server') +
b"\n")
# If the exec() program calls sys.exit(), it should exit python
# and the sys.exit(98) call won't be reached (so we try to only
# exit that way in the server). However, if the code that we
# exec() simply returns from main, then we will return from
# exec(). If the server's python process dies, it should stop
# executing and also won't reach sys.exit(98).
#
# So, we shouldn't reach sys.exit(98) and we certainly shouldn't
# reach it immediately after trying to start the server.
pyscript = r"""
import sys, os;
verbosity=%d;
sys.stdin = os.fdopen(0, "rb");
exec(compile(sys.stdin.read(%d), "assembler.py", "exec"));
sys.exit(98);
""" % (helpers.verbose or 0, len(content))
pyscript = re.sub(r'\s+', ' ', pyscript.strip())
if not rhost:
# ignore the --python argument when running locally; we already know
# which python version works.
argv = [sys.executable, '-c', pyscript]
else:
if ssh_cmd:
sshl = shlex.split(ssh_cmd)
else:
sshl = ['ssh']
if port is not None:
portl = ["-p", str(port)]
else:
portl = []
if python:
pycmd = "'%s' -c '%s'" % (python, pyscript)
else:
# By default, we run the following code in a shell.
# However, with restricted shells and other unusual
# situations, there can be trouble. See the RESTRICTED
# SHELL section in "man bash" for more information. The
# code makes many assumptions:
#
# (1) That /bin/sh exists and that we can call it.
# Restricted shells often do *not* allow you to run
# programs specified with an absolute path like /bin/sh.
# Either way, if there is trouble with this, it should
# return error code 127.
#
# (2) python3 or python exists in the PATH and is
# executable. If they aren't, then exec wont work (see (4)
# below).
#
# (3) In /bin/sh, that we can redirect stderr in order to
# hide the version that "python3 -V" might print (some
# restricted shells don't allow redirection, see
# RESTRICTED SHELL section in 'man bash'). However, if we
# are in a restricted shell, we'd likely have trouble with
# assumption (1) above.
#
# (4) The 'exec' command should work except if we failed
# to exec python because it doesn't exist or isn't
# executable OR if exec isn't allowed (some restricted
# shells don't allow exec). If the exec succeeded, it will
# not return and not get to the "exit 97" command. If exec
# does return, we exit with code 97.
#
# Specifying the exact python program to run with --python
# avoids many of the issues above. However, if
# you have a restricted shell on remote, you may only be
# able to run python if it is in your PATH (and you can't
# run programs specified with an absolute path). In that
# case, tshuttle might not work at all since it is not
# possible to run python on the remote machine---even if
# it is present.
pycmd = ("P=python3; $P -V 2>%s || P=python; "
"exec \"$P\" -c %s; exit 97") % \
(os.devnull, quote(pyscript))
pycmd = ("/bin/sh -c {}".format(quote(pycmd)))
if password is not None:
os.environ['SSHPASS'] = str(password)
argv = (["sshpass", "-e"] + sshl +
portl +
[rhost, pycmd])
else:
argv = (sshl +
portl +
[rhost, pycmd])
# Our which() function searches for programs in get_path()
# directories (which include PATH). This step isn't strictly
# necessary if ssh is already in the user's PATH, but it makes the
# error message friendlier if the user incorrectly passes in a
# custom ssh command that we cannot find.
abs_path = which(argv[0])
if abs_path is None:
raise Fatal("Failed to find '%s' in path %s" % (argv[0], get_path()))
argv[0] = abs_path
(s1, s2) = socket.socketpair()
def setup():
# runs in the child process
s2.close()
s1a, s1b = os.dup(s1.fileno()), os.dup(s1.fileno())
s1.close()
debug2('executing: %r' % argv)
p = ssubprocess.Popen(argv, stdin=s1a, stdout=s1b, preexec_fn=setup,
close_fds=True, stderr=stderr)
os.close(s1a)
os.close(s1b)
s2.sendall(content)
s2.sendall(content2)
return p, s2
