From: Florian Westphal <fw@strlen.de>
To: Nikolaos Gkarlis <nickgarlis@gmail.com>
Cc: netfilter-devel@vger.kernel.org, pablo@netfilter.org
Subject: Re: [PATCH] netfilter: nft_ct: reject ambiguous conntrack expressions in inet tables
Date: Fri, 29 Aug 2025 17:08:43 +0200 [thread overview]
Message-ID: <aLHCe9QAViNEtwPi@strlen.de> (raw)
In-Reply-To: <20250829065011.12936-1-nickgarlis@gmail.com>
Nikolaos Gkarlis <nickgarlis@gmail.com> wrote:
> The kernel accepts netlink messages using the legacy NFT_CT_SRC,
> NFT_CT_DST keys in inet tables, creating ambiguous conntrack expressions
> that cannot be properly evaluated during packet processing.
>
> When NFPROTO_INET is used with NFT_CT_SRC, NFT_CT_DST the register size
> calculation defaults to IPv6 (16 bytes) regardless of the actual packet
> family.
>
> This causes two issues:
> 1. For IPv4 packets, only 4 bytes contain valid address data while 12
> bytes contain uninitialized memory during comparison.
> 2. nft userspace cannot properly display these rules ([invalid type]).
>
> The bug is not reproducible through standard nft commands, which
> properly use NFT_CT_SRC_IP(6), NFT_CT_DST_IP(6) keys instead.
It breaks nftables .py tests:
tests/py/nft-test.py
inet/rt.t: OK
inet/ct.t: ERROR: line 7: add rule inet test-inet input meta nfproto ipv4 ct original saddr 1.2.3.4: This rule should not have failed.
inet/ct.t: OK
next prev parent reply other threads:[~2025-08-29 15:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-29 6:50 [PATCH] netfilter: nft_ct: reject ambiguous conntrack expressions in inet tables Nikolaos Gkarlis
2025-08-29 15:08 ` Florian Westphal [this message]
2025-08-29 21:59 ` Nick Garlis
2025-09-02 21:54 ` [PATCH v2] " Nikolaos Gkarlis
2025-09-02 22:21 ` Florian Westphal
2025-09-03 9:12 ` Nick Garlis
2025-09-03 10:13 ` Florian Westphal
2025-09-03 10:34 ` Pablo Neira Ayuso
2025-09-03 11:51 ` Nikolaos Gkarlis
2025-09-03 10:31 ` Pablo Neira Ayuso
2025-09-03 13:18 ` kernel test robot
2025-09-03 17:47 ` [syzbot ci] " syzbot ci
2025-09-03 17:56 ` [PATCH v2] " kernel test robot
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