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|
#!/usr/bin/env python3
# 20180114
# Jan Mojzis
# Public domain.
import logging
import socket
import sys
import os
import time
import struct
import subprocess
import atexit
class SSH:
"""
"""
SSH_MSG_KEXINIT = b'\x14'
SSH_MSG_KEXDH_INIT = b'\x1e'
def __init__(self, host = "127.0.0.1", port = 2222):
"""
"""
self.timeout = 60
try:
socket.setdefaulttimeout(self.timeout)
self.s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.s.connect((host, port))
except Exception as e:
logging.fatal("unable to connect to host='%s', port=%d: %s", host, port, e)
raise
else:
logging.debug("connected to host='%s', port=%d", host, port)
def close(self):
"""
"""
self.s.close()
def recv(self, l):
"""
"""
r = self.s.recv(l)
if len(r) == 0:
raise Exception("no data received")
return r
def packet_hello_receive(self):
"""
"""
ret = b''
try:
while True:
ch = self.recv(1)
ret += ch
if ch == b'\n':
break
except Exception as e:
logging.fatal("unable to receive server hello message: %s", e)
raise
else:
logging.debug("server hello message received: %s", [ret])
return ret
def packet_hello_send(self, msg = b'SSH-2.0-autopkgtest\r\n'):
"""
"""
try:
self.s.send(msg)
except Exception as e:
logging.fatal("unable to send client hello message: %s", e)
raise
else:
logging.debug("client hello message send: %s", [msg])
def _parseuint32(self, x = b'', pos = 0):
"""
"""
return struct.unpack_from('>I', x, pos)[0]
def _sshstring(self, x = b'', pos = 0):
"""
"""
ret = struct.pack('>I', len(x))
return ret + x
def packet_send(self, packet = b''):
#padding
paddinglen = 2 * 8 - ((len(packet) + 5) % 8)
packet = struct.pack('B', paddinglen) + packet + paddinglen * b'\x00'
#add length
packet = self._sshstring(packet)
try:
self.s.send(packet)
except Exception as e:
logging.fatal("unable to send SSH packet: %s", e)
raise
def packet_kex_receive(self):
"""
"""
pos = 0
ret = []
try:
packet = self.recv(65536)
except Exception as e:
logging.fatal("unable to receive server kex message: %s", e)
raise
else:
pass
try:
#packet length
l = self._parseuint32(packet, pos)
logging.debug("server kex: length = %d", l)
pos += 4
#padding length (skipping)
pos += 1
#packet type
if packet[pos] != self.SSH_MSG_KEXINIT[0]:
raise Exception("bad bad server kex message: not SSH_MSG_KEXINIT")
pos += 1
#cookie
cookie = packet[pos:pos+16]
logging.debug("server kex: cookie = %s", [cookie])
pos += 16
for text in [ 'kex algorithms',
'server host key algorithms',
'encryption algorithms client to server',
'encryption algorithms server to client',
'mac algorithms client to server',
'mac algorithms server to client',
'compress algorithms client to server',
'compress algorithms server to client',
'languages client to server',
'languages server to client' ]:
l = self._parseuint32(packet, pos)
pos += 4
data = packet[pos:pos+l]
pos += l
logging.debug("server kex: %s = %s", text, [data])
ret.append(data)
#XXX skipping the rest
except Exception as e:
logging.fatal("unable to parse server kex message: %s", e)
raise
return ret
def packet_kex_send(self):
"""
"""
#packet type
packet = self.SSH_MSG_KEXINIT
#cookie
cookie = os.urandom(16)
logging.debug("client kex: cookie = %s", [cookie])
packet += cookie
for text,data in [ ('kex algorithms',b'curve25519-sha256@libssh.org'),
('server host key algorithms',b'ssh-ed25519',),
('encryption algorithms client to server',b'chacha20-poly1305@openssh.com'),
('encryption algorithms server to client',b'chacha20-poly1305@openssh.com'),
('mac algorithms client to server',b'hmac-sha2-256'),
('mac algorithms server to client',b'hmac-sha2-256'),
('compress algorithms client to server',b'none'),
('compress algorithms server to client',b'none'),
('languages client to server',b''),
('languages server to client',b'') ]:
packet += self._sshstring(data)
logging.debug("client kex: %s = %s", text, [data])
#kex first packet follows
packet += b'\x00'
#reserved
packet += b'\x00\x00\x00\x00'
self.packet_send(packet)
def packet_kexdh_send(self, pk):
"""
"""
#packet type
packet = self.SSH_MSG_KEXDH_INIT
#pk
logging.debug("client kexdh: pk = %s", [pk])
packet += self._sshstring(pk)
self.packet_send(packet)
def packet_kexdh_receive(self):
"""
"""
pos = 0
try:
packet = self.recv(65536)
except Exception as e:
#logging.fatal("unable to receive server kexdh message: %s", e)
raise Exception("unable to receive server kexdh message: %s" % e)
else:
#logging.info("server kexdh message received: %s", [packet])
pass
def test_chacha20(ip = "127.0.0.1", port = 2222):
"""
Tests if TinySSH has chacha20-poly1305@openssh.com.
chacha20-poly1305@openssh.com is state-off-the-art ciphersuite,
encrypts and authenticates data using 256bit secret-key.
This cipher is safe against quantum computers.
TinySSH must support chacha20-poly1305@openssh.com
"""
logging.info("test_chacha20: %s", test_chacha20.__doc__)
s = SSH(ip, port)
s.packet_hello_receive()
s.packet_hello_send(b'SSH-2.0-autopkgtest-test-chacha20\r\n')
data = s.packet_kex_receive()
if data[2].find(b'chacha20-poly1305@openssh.com') == -1:
raise Exception("TinySSH doesn't have chacha20-poly1305@openssh.com")
if data[3].find(b'chacha20-poly1305@openssh.com') == -1:
raise Exception("TinySSH doesn't have chacha20-poly1305@openssh.com")
s.close()
logging.info("test_chacha20: OK\n")
def test_invalid_pk(ip = "127.0.0.1", port = 2222):
"""
Tests if TinySSH accepts bad public-key.
Client tries to send zero public-key.
It's dangerous, because computed shared secret-key is also zero.
TinySSH must immediately drop the connection.
"""
logging.info("test_invalid_pk: %s", test_invalid_pk.__doc__)
s = SSH(ip, port)
s.packet_hello_receive()
s.packet_hello_send(b'SSH-2.0-autopkgtest-invalid-pk\r\n')
s.packet_kex_receive()
s.packet_kex_send()
# pk modulo p is zero
pk = b'\xed' + 30*b'\xff' + b'\x7f'
s.packet_kexdh_send(pk)
try:
s.packet_kexdh_receive()
except Exception as e:
logging.debug(e)
pass
else:
raise Exception("TinySSH accepts bad public-key")
s.close()
logging.info("test_invalid_pk: OK\n")
def is_docker():
"""
Detect docker
"""
if os.path.exists('/.dockerenv'):
return True
else:
return False
def run_systemd_2222():
"""
Run TinySSH on port 2222 using systemd.
Default port 22 is used by OpenSSH server.
"""
r = os.system("sed -i 's/^ListenStream=.*/ListenStream=2222/' /lib/systemd/system/tinysshd.socket")
os.system("systemctl daemon-reload && systemctl restart tinysshd.socket")
server = None
def cleanup():
if server != None:
server.kill()
def run_tcpserver_2222(ip = "127.0.0.1", port = 2222):
"""
Run TinySSH on port 2222 using tcpserver.
Default port 22 is used by OpenSSH server.
"""
os.system('tinysshd-makekey sshkeydir')
server = subprocess.Popen(["tcpserver", "-HRDl0", ip, str(port), "tinysshd", "--", "sshkeydir"])
time.sleep(1)
if __name__ == '__main__':
try:
ip = sys.argv[1]
except IndexError:
ip = "127.0.0.1"
try:
port = int(sys.argv[2])
except IndexError:
port = 2222
logging.basicConfig(level=logging.DEBUG)
os.environ["PATH"] += os.pathsep + "/usr/sbin"
tmp = os.getenv("AUTOPKGTEST_TMP")
if not tmp:
tmp = '/tmp'
os.chdir(tmp)
#XXX
if port == 2222:
if is_docker():
run_tcpserver_2222()
else:
run_systemd_2222()
atexit.register(cleanup)
test_chacha20(ip, port)
test_invalid_pk(ip, port)
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