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![Kristof Provost](/assets/img/avatar_default.png)
Send an ICMPv6 echo request packet with multiple IPv6 fragment headers. Set rules to pass all packets, except for ICMPv6 echo requests. pf ought to drop the echo request, but doesn't because it reassembles the packet, and then doesn't handle the second fragment header. In other words: it fails to detect the ICMPv6 echo header. Reported by: Enrico Bassetti bassetti@di.uniroma1.it (NetSecurityLab @ Sapienza University of Rome) MFC after: instant Sponsored by: Rubicon Communications, LLC ("Netgate")
61 lines
1.8 KiB
Python
61 lines
1.8 KiB
Python
import pytest
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import logging
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import threading
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import time
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logging.getLogger("scapy").setLevel(logging.CRITICAL)
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from atf_python.sys.net.tools import ToolsHelper
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from atf_python.sys.net.vnet import VnetTestTemplate
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class DelayedSend(threading.Thread):
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def __init__(self, packet):
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threading.Thread.__init__(self)
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self._packet = packet
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self.start()
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def run(self):
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import scapy.all as sp
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time.sleep(1)
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sp.send(self._packet)
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class TestFrag6(VnetTestTemplate):
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REQUIRED_MODULES = ["pf"]
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TOPOLOGY = {
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"vnet1": {"ifaces": ["if1"]},
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"vnet2": {"ifaces": ["if1"]},
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"if1": {"prefixes6": [("2001:db8::1/64", "2001:db8::2/64")]},
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}
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def vnet2_handler(self, vnet):
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ToolsHelper.print_output("/sbin/pfctl -e")
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ToolsHelper.pf_rules([
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"scrub fragment reassemble",
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"pass",
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"block in inet6 proto icmp6 icmp6-type echoreq",
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])
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def check_ping_reply(self, packet):
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print(packet)
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return False
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@pytest.mark.require_user("root")
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def test_dup_frag_hdr(self):
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"Test packets with duplicate fragment headers"
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srv_vnet = self.vnet_map["vnet2"]
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# Import in the correct vnet, so at to not confuse Scapy
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import scapy.all as sp
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packet = sp.IPv6(src="2001:db8::1", dst="2001:db8::2") \
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/ sp.IPv6ExtHdrFragment(offset = 0, m = 0) \
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/ sp.IPv6ExtHdrFragment(offset = 0, m = 0) \
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/ sp.ICMPv6EchoRequest(data=sp.raw(bytes.fromhex('f00f') * 128))
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# Delay the send so the sniffer is running when we transmit.
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s = DelayedSend(packet)
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packets = sp.sniff(iface=self.vnet.iface_alias_map["if1"].name,
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timeout=3)
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for p in packets:
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assert not p.getlayer(sp.ICMPv6EchoReply)
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