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#!/usr/local/bin/python3
print("ping fragment at index boundary that cannot be requeued")
# index boundary 4096 |
# |--------------|
# ....
# |--------------|
# |--------------|
# ....----|
# |XXXX-----|
# |--------------|
# this should trigger "fragment requeue limit exceeded" log in kernel
import os
from itertools import chain
from addr import *
from scapy.all import *
pid=os.getpid()
eid=pid & 0xffff
payload=b"ABCDEFGHIJKLMNOP"
dummy=b"01234567"
fragsize=64
boundary=4096
fragnum=int(boundary/fragsize)
packet=IP(src=LOCAL_ADDR, dst=REMOTE_ADDR)/ \
ICMP(type='echo-request', id=eid)/ \
(int((boundary+boundary)/len(payload)) * payload)
frag=[]
fid=pid & 0xffff
for i in chain(range(fragnum-1), range(fragnum, fragnum+fragnum-1)):
frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=1, id=fid,
frag=(i*fragsize)>>3, flags='MF')/
bytes(packet)[20+i*fragsize:20+(i+1)*fragsize])
frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=1, id=fid,
frag=(boundary+boundary-fragsize)>>3)/
bytes(packet)[20+boundary+boundary-fragsize:])
frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=1, id=fid,
frag=(boundary-8)>>3, flags='MF')/
(dummy+bytes(packet)[20+boundary:20+boundary+8]))
frag.append(IP(src=LOCAL_ADDR, dst=REMOTE_ADDR, proto=1, id=fid,
frag=(boundary-fragsize)>>3, flags='MF')/
bytes(packet)[20+boundary-fragsize:20+boundary])
eth=[]
for f in frag:
eth.append(Ether(src=LOCAL_MAC, dst=REMOTE_MAC)/f)
if os.fork() == 0:
time.sleep(1)
for e in eth:
sendp(e, iface=LOCAL_IF)
time.sleep(0.001)
os._exit(0)
ans=sniff(iface=LOCAL_IF, timeout=10, filter=
"ip and src "+REMOTE_ADDR+" and dst "+LOCAL_ADDR+" and icmp")
for a in ans:
if a and a.type == ETH_P_IP and \
a.payload.proto == 1 and \
a.payload.frag == 0 and \
icmptypes[a.payload.payload.type] == 'echo-reply':
id=a.payload.payload.id
print("id=%#x" % (id))
if id != eid:
print("WRONG ECHO REPLY ID")
exit(2)
print("ECHO REPLY")
exit(1)
print("no echo reply")
exit(0)
|
