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pf tests: Verify (tcp) checksum modification on unaligned options

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It turns out pf incorrectly updates the TCP checksum if the TCP option
we're modifying is not 2-byte algined with respect to the start of the
packet.

Create a TCP packet with such an option and throw it through a scrub
rule, which will update timestamps and modify the packet.

PR:		240416
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D27688
This commit is contained in:
Kristof Provost 2020-12-19 16:06:03 +01:00
parent e1f6571a12
commit 2d3fda5fa1
3 changed files with 151 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

69
tests/sys/netpfil/common/pft_ping.py
View File

@ -28,6 +28,7 @@
import argparse
import scapy.all as sp
import socket
import sys
from sniffer import Sniffer
@ -113,6 +114,53 @@ def ping6(send_if, dst_ip, args):
req = ether / ip6 / icmp
sp.sendp(req, iface=send_if, verbose=False)
def check_tcpsyn(args, packet):
dst_ip = args.to[0]
ip = packet.getlayer(sp.IP)
if not ip:
return False
if ip.dst != dst_ip:
return False
tcp = packet.getlayer(sp.TCP)
if not tcp:
return False
# Verify IP checksum
chksum = ip.chksum
ip.chksum = None
new_chksum = sp.IP(sp.raw(ip)).chksum
if chksum != new_chksum:
print("Expected IP checksum %x but found %x\n" % (new_cshkum, chksum))
return False
# Verify TCP checksum
chksum = tcp.chksum
packet_raw = sp.raw(packet)
tcp.chksum = None
newpacket = sp.Ether(sp.raw(packet[sp.Ether]))
new_chksum = newpacket[sp.TCP].chksum
if chksum != new_chksum:
print("Expected TCP checksum %x but found %x\n" % (new_chksum, chksum))
return False
return True
def tcpsyn(send_if, dst_ip, args):
opts=[('Timestamp', (1, 1)), ('MSS', 1280)]
if args.tcpopt_unaligned:
opts = [('NOP', 0 )] + opts
ether = sp.Ether()
ip = sp.IP(dst=dst_ip)
tcp = sp.TCP(dport=666, flags='S', options=opts)
req = ether / ip / tcp
sp.sendp(req, iface=send_if, verbose=False)
def main():
parser = argparse.ArgumentParser("pft_ping.py",
description="Ping test tool")
@ -127,6 +175,12 @@ def main():
required=True,
help='The destination IP address for the ICMP echo request')
# TCP options
parser.add_argument('--tcpsyn', action='store_true',
help='Send a TCP SYN packet')
parser.add_argument('--tcpopt_unaligned', action='store_true',
help='Include unaligned TCP options')
# Packet settings
parser.add_argument('--send-tos', nargs=1,
help='Set the ToS value for the transmitted packet')
@ -142,12 +196,19 @@ def main():
sniffer = None
if not args.recvif is None:
sniffer = Sniffer(args, check_ping_request)
checkfn=check_ping_request
if args.tcpsyn:
checkfn=check_tcpsyn
if args.ip6:
ping6(args.sendif[0], args.to[0], args)
sniffer = Sniffer(args, checkfn)
if args.tcpsyn:
tcpsyn(args.sendif[0], args.to[0], args)
else:
ping(args.sendif[0], args.to[0], args)
if args.ip6:
ping6(args.sendif[0], args.to[0], args)
else:
ping(args.sendif[0], args.to[0], args)
if sniffer:
sniffer.join()

1
tests/sys/netpfil/pf/Makefile
View File

@ -6,6 +6,7 @@ TESTSDIR= ${TESTSBASE}/sys/netpfil/pf
TESTS_SUBDIRS+= ioctl
ATF_TESTS_SH+= anchor \
checksum \
forward \
fragmentation \
icmp \

85
tests/sys/netpfil/pf/checksum.sh Normal file
View File

@ -0,0 +1,85 @@
# SPDX-License-Identifier: BSD-2-Clause-FreeBSD
#
# Copyright (c) 2020 Kristof Provost <kp@FreeBSD.org>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
. $(atf_get_srcdir)/utils.subr
common_dir=$(atf_get_srcdir)/../common
atf_test_case "unaligned" "cleanup"
unaligned_head()
{
atf_set descr 'Test unaligned checksum updates'
atf_set require.user root
}
unaligned_body()
{
pft_init
epair_in=$(vnet_mkepair)
epair_out=$(vnet_mkepair)
vnet_mkjail alcatraz ${epair_in}b ${epair_out}a
ifconfig ${epair_in}a 192.0.2.2/24 up
route add -net 198.51.100.0/24 192.0.2.1
jexec alcatraz ifconfig ${epair_in}b 192.0.2.1/24 up
jexec alcatraz sysctl net.inet.ip.forwarding=1
jexec alcatraz ifconfig ${epair_out}a 198.51.100.1/24 up
jexec alcatraz arp -s 198.51.100.2 00:01:02:03:04:05
ifconfig ${epair_out}b up
jexec alcatraz pfctl -e
pft_set_rules alcatraz \
"scrub on ${epair_in}b reassemble tcp max-mss 1200"
# Check aligned
atf_check -s exit:0 ${common_dir}/pft_ping.py \
--sendif ${epair_in}a \
--to 198.51.100.2 \
--recvif ${epair_out}b \
--tcpsyn
# And unaligned
atf_check -s exit:0 ${common_dir}/pft_ping.py \
--sendif ${epair_in}a \
--to 198.51.100.2 \
--recvif ${epair_out}b \
--tcpsyn \
--tcpopt_unaligned
}
unaligned_cleanup()
{
pft_cleanup
}
atf_init_test_cases()
{
atf_add_test_case "unaligned"
}