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SubjectRe: [PATCH] tproxy: nf_tproxy_assign_sock() can handle tw sockets
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Hi Mr. Dumazet,

2010/7/9 Eric Dumazet <eric.dumazet@gmail.com>:
> Reviewing tproxy stuff I spotted a problem in nf_tproxy_assign_sock()
> but I could not see how it could explain your crash.
>
> We can read uninitialized memory and trigger a fault in
> nf_tproxy_assign_sock(), not later in tcp_recvmsg()...
>
> David, Patrick, what do you think ?

But do you think that the bug that squid triggered was caused by the
TProxy code?

Or is related to the network-stack in some other point.

I don't know if this helps, but I'm using ebtables to remove the
packets from the bridge, and iptables to redirect the traffic to
squid.

ebtables rules are:

-p IPv4 -i eth0 --ip-proto tcp --ip-dport 80 -j redirect --redirect-target DROP
-p IPv4 -i eth1 --ip-proto tcp --ip-sport 80 -j redirect --redirect-target DROP


iptables -t mangle -L -n is:

iptables -t mangle -L -n
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
DIVERT tcp -- 0.0.0.0/0 0.0.0.0/0 socket
extrachain tcp -- 0.0.0.0/0 0.0.0.0/0 tcp
dpt:80 ctstate NEW
TPROXY tcp -- 0.0.0.0/0 !201.40.162.5 tcp
dpt:80 connmark match 0x0 TPROXY redirect 127.0.0.1:3127 mark 0x1/0x1
TPROXY tcp -- 0.0.0.0/0 !201.40.162.5 tcp
dpt:80 connmark match 0x1 TPROXY redirect 127.0.0.1:3128 mark 0x1/0x1
TPROXY tcp -- 0.0.0.0/0 !201.40.162.5 tcp
dpt:80 connmark match 0x2 TPROXY redirect 127.0.0.1:3129 mark 0x1/0x1

Chain DIVERT (1 references)
target prot opt source destination
MARK all -- 0.0.0.0/0 0.0.0.0/0 MARK xset
0x1/0xffffffff
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0

Chain extrachain (1 references)
target prot opt source destination
CONNMARK all -- 0.0.0.0/0 0.0.0.0/0 statistic
mode nth every 35 CONNMARK and 0x0
CONNMARK all -- 0.0.0.0/0 0.0.0.0/0 statistic
mode nth every 35 packet 1 CONNMARK xset 0x1/0xffffffff
CONNMARK all -- 0.0.0.0/0 0.0.0.0/0 statistic
mode nth every 35 packet 2 CONNMARK xset 0x2/0xffffffff

Don't know if the code on these can be traced back to tcp_recvmsg()
accessing some wrong memory address...

Cheers,

Felipe Damasio


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