would you like that I check *net for NULL as is done for *ct, *help,
and *helper?
On Sun, Dec 4, 2011 at 2:49 PM, Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
> Hi Peter,
>
> On Fri, Dec 02, 2011 at 09:37:04AM -0800, Pete Holland wrote:
>> From: Peter Holland <pholland27@xxxxxxxxx>
>>
>> Make the logging of dropped packets due to ct helper rejection
>> conditional on LOG_INVALID.
>> This is consistent with the other uses of nf_log_packet.
>> Use protocol from conntrack tuple (original direction).
>> Without this check, there is a possible DoS based on traffic induced
>> log generation.
>> (specifically this was noted in the wild by an attacker against the SIP helper)
>>
>> Signed-off-by: Peter Holland <pholland27@xxxxxxxxx>
>> ---
>> --- net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c.orig 2011-11-29
>> 11:34:36.683717278 -0800
>> +++ net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c 2011-12-02
>> 09:32:00.727064563 -0800
>> @@ -116,8 +116,10 @@ static unsigned int ipv4_confirm(unsigne
>> ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
>> ct, ctinfo);
>> if (ret != NF_ACCEPT) {
>> - nf_log_packet(NFPROTO_IPV4, hooknum, skb, in, out, NULL,
>> - "nf_ct_%s: dropping packet", helper->name);
>> + if (LOG_INVALID(nf_ct_net(ct),
>> + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum))
>
> You can use nf_ct_protonum here.
>
>> + nf_log_packet(NFPROTO_IPV4, hooknum, skb, in, out, NULL,
>> + "nf_ct_%s: dropping packet", helper->name);
>> return ret;
>> }
>
> Below you can find:
>
> /* adjust seqs for loopback traffic only in outgoing direction */
> if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
> !nf_is_loopback_packet(skb)) {
> typeof(nf_nat_seq_adjust_hook) seq_adjust;
>
> seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook);
> if (!seq_adjust || !seq_adjust(skb, ct, ctinfo)) {
> NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
> ^^^^^^^^^^^^
>
> Please, declare in ipv4_confirm:
>
> struct net *net = nf_ct_net(ct);
>
> And use the net pointer in that function.
>
> Same thing for the IPv6 side.
>
> Thank you.
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