Re: [PATCH] ipvs: avoid oops in nf_ct_seqadj_set when called from ip_vs_ftp helper

[Julian Anastasov <ja@xxxxxx>]

        Hello,

On Fri, 13 Dec 2013, Jesper Dangaard Brouer wrote:

> The IPVS FTP helper ip_vs_ftp can trigger an OOPS in nf_ct_seqadj_set,
> after commit 41d73ec053d2 (netfilter: nf_conntrack: make sequence
> number adjustments usuable without NAT).
> 
> We can avoid the oops in nf_ct_seqadj_set() by in ip_vs_ftp_out()
> instead of calling nf_nat_mangle_tcp_packet() we simply call
> __nf_nat_mangle_tcp_packet() with a "false" last parameter, which
> indicate not invoking the seqadj code.
> 
> After this fix, I've tested that FTP over IPVS, with module ip_vs_ftp
> loaded, works for both passive and active FTP.

        There is still a problem when RIP and VIP differ in
text length because now ack_seq sent to RIP is not
adjusted after receiving the the 227 Entering Passive Mode
reply. I tried also to set *diff, ack_seq was corrected
but the result was bad checksum.

> Fixes: 41d73ec053d2 (netfilter: nf_conntrack: make sequence number 
> adjustments usuable without NAT)
> Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
> 
> ---
> I'm uncertain if this is the correct fix.  Perhaps the ip_vs_ftp
> helper need to allocate/init the seqadj extension instead?

        Agreed, lets try nfct_seqadj_ext_add() + nf_ct_seqadj_init()
if nfct_seqadj(ct) is NULL.

Regards

--
Julian Anastasov <ja@xxxxxx>
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