lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <aPDU6i1HKhy5v-nh@strlen.de>
Date: Thu, 16 Oct 2025 13:20:10 +0200
From: Florian Westphal <fw@...len.de>
To: Andrii Melnychenko <a.melnychenko@...s.io>
Cc: pablo@...filter.org, kadlec@...filter.org, phil@....cc,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, horms@...nel.org,
	netfilter-devel@...r.kernel.org, coreteam@...filter.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/1] nf_conntrack_ftp: Added nfct_seqadj_ext_add() for
 ftp's conntrack.

Andrii Melnychenko <a.melnychenko@...s.io> wrote:
> There was an issue with NAT'ed ftp and replaced messages
> for PASV/EPSV mode. "New" IP in the message may have a
> different length that would require sequence adjustment.
> 
> Signed-off-by: Andrii Melnychenko <a.melnychenko@...s.io>
> ---
>  net/netfilter/nf_conntrack_ftp.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
> index 617f744a2..0216bc099 100644
> --- a/net/netfilter/nf_conntrack_ftp.c
> +++ b/net/netfilter/nf_conntrack_ftp.c
> @@ -25,6 +25,7 @@
>  #include <net/netfilter/nf_conntrack_ecache.h>
>  #include <net/netfilter/nf_conntrack_helper.h>
>  #include <linux/netfilter/nf_conntrack_ftp.h>
> +#include <net/netfilter/nf_conntrack_seqadj.h>
>  
>  #define HELPER_NAME "ftp"
>  
> @@ -390,6 +391,8 @@ static int help(struct sk_buff *skb,
>  	/* Until there's been traffic both ways, don't look in packets. */
>  	if (ctinfo != IP_CT_ESTABLISHED &&
>  	    ctinfo != IP_CT_ESTABLISHED_REPLY) {
> +		if (!nf_ct_is_confirmed(ct))
> +			nfct_seqadj_ext_add(ct);

Still not convinced this is the correct place.

In nf_nat_setup_info we have:

                if (nfct_help(ct) && !nfct_seqadj(ct))
                        if (!nfct_seqadj_ext_add(ct))
                                return NF_DROP;

Looking at your cover letter (some of that info should be in
patch changelog, it provides essential context), I would say
that dnat rule is evaluated before the helper gets attached.

If so, the bug is in nft_ct_helper_obj_eval, and the Fixes
tag should be set to

Fixes: 1a64edf54f55 ("netfilter: nft_ct: add helper set support")

Probably something like:

if ((ct->status & IPS_NAT_MASK) && !!nfct_seqadj(ct))
	if (!nfct_seqadj_ext_add(ct)) ...

Could you please investigate a bit futher? To me it looks
like all other helpers have the same issue, a generic fix would
be better.

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ