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[37.48.53.4]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c260d4a98efsm452196766b.14.2026.09.07.02.57.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Sep 2026 02:57:33 -0700 (PDT) Message-ID: <0956bec0-163f-480d-ad31-5e547fbe0bab@ovn.org> Date: Mon, 7 Sep 2026 11:57:31 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH nf-next] netfilter: conntrack: make filtering by zone discoverable To: Ilya Maximets , netfilter-devel@vger.kernel.org Cc: netdev@vger.kernel.org, Donald Hunter , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Pablo Neira Ayuso , Florian Westphal , Phil Sutter , Shuah Khan , =?UTF-8?Q?Asbj=C3=B8rn_Sloth_T=C3=B8nnesen?= , "Matthieu Baerts (NGI0)" , "Remy D. Farley" , linux-kernel@vger.kernel.org, coreteam@netfilter.org, linux-kselftest@vger.kernel.org References: <20260904174452.1913072-1-i.maximets@ovn.org> Content-Language: en-US From: Ilya Maximets Autocrypt: addr=i.maximets@ovn.org; keydata= xsFNBF77bOMBEADVZQ4iajIECGfH3hpQMQjhIQlyKX4hIB3OccKl5XvB/JqVPJWuZQRuqNQG /B70MP6km95KnWLZ4H1/5YOJK2l7VN7nO+tyF+I+srcKq8Ai6S3vyiP9zPCrZkYvhqChNOCF pNqdWBEmTvLZeVPmfdrjmzCLXVLi5De9HpIZQFg/Ztgj1AZENNQjYjtDdObMHuJQNJ6ubPIW cvOOn4WBr8NsP4a2OuHSTdVyAJwcDhu+WrS/Bj3KlQXIdPv3Zm5x9u/56NmCn1tSkLrEgi0i /nJNeH5QhPdYGtNzPixKgPmCKz54/LDxU61AmBvyRve+U80ukS+5vWk8zvnCGvL0ms7kx5sA tETpbKEV3d7CB3sQEym8B8gl0Ux9KzGp5lbhxxO995KWzZWWokVUcevGBKsAx4a/C0wTVOpP FbQsq6xEpTKBZwlCpxyJi3/PbZQJ95T8Uw6tlJkPmNx8CasiqNy2872gD1nN/WOP8m+cIQNu o6NOiz6VzNcowhEihE8Nkw9V+zfCxC8SzSBuYCiVX6FpgKzY/Tx+v2uO4f/8FoZj2trzXdLk BaIiyqnE0mtmTQE8jRa29qdh+s5DNArYAchJdeKuLQYnxy+9U1SMMzJoNUX5uRy6/3KrMoC/ 7zhn44x77gSoe7XVM6mr/mK+ViVB7v9JfqlZuiHDkJnS3yxKPwARAQABzSJJbHlhIE1heGlt ZXRzIDxpLm1heGltZXRzQG92bi5vcmc+wsGUBBMBCAA+AhsDBQsJCAcCBhUKCQgLAgQWAgMB Ah4BAheAFiEEh+ma1RKWrHCY821auffsd8gpv5YFAmfB9JAFCQyI7q0ACgkQuffsd8gpv5YQ og/8DXt1UOznvjdXRHVydbU6Ws+1iUrxlwnFH4WckoFgH4jAabt25yTa1Z4YX8Vz0mbRhTPX M/j1uORyObLem3of4YCd4ymh7nSu++KdKnNsZVHxMcoiic9ILPIaWYa8kTvyIDT2AEVfn9M+ vskM0yDbKa6TAHgr/0jCxbS+mvN0ZzDuR/LHTgy3e58097SWJohj0h3Dpu+XfuNiZCLCZ1/G AbBCPMw+r7baH/0evkX33RCBZwvh6tKu+rCatVGk72qRYNLCwF0YcGuNBsJiN9Aa/7ipkrA7 Xp7YvY3Y1OrKnQfdjp3mSXmknqPtwqnWzXvdfkWkZKShu0xSk+AjdFWCV3NOzQaH3CJ67NXm aPjJCIykoTOoQ7eEP6+m3WcgpRVkn9bGK9ng03MLSymTPmdINhC5pjOqBP7hLqYi89GN0MIT Ly2zD4m/8T8wPV9yo7GRk4kkwD0yN05PV2IzJECdOXSSStsf5JWObTwzhKyXJxQE+Kb67Wwa LYJgltFjpByF5GEO4Xe7iYTjwEoSSOfaR0kokUVM9pxIkZlzG1mwiytPadBt+VcmPQWcO5pi WxUI7biRYt4aLriuKeRpk94ai9+52KAk7Lz3KUWoyRwdZINqkI/aDZL6meWmcrOJWCUMW73e 4cMqK5XFnGqolhK4RQu+8IHkSXtmWui7LUeEvO/OwU0EXvts4wEQANCXyDOic0j2QKeyj/ga OD1oKl44JQfOgcyLVDZGYyEnyl6b/tV1mNb57y/YQYr33fwMS1hMj9eqY6tlMTNz+ciGZZWV YkPNHA+aFuPTzCLrapLiz829M5LctB2448bsgxFq0TPrr5KYx6AkuWzOVq/X5wYEM6djbWLc VWgJ3o0QBOI4/uB89xTf7mgcIcbwEf6yb/86Cs+jaHcUtJcLsVuzW5RVMVf9F+Sf/b98Lzrr 2/mIB7clOXZJSgtV79Alxym4H0cEZabwiXnigjjsLsp4ojhGgakgCwftLkhAnQT3oBLH/6ix 87ahawG3qlyIB8ZZKHsvTxbWte6c6xE5dmmLIDN44SajAdmjt1i7SbAwFIFjuFJGpsnfdQv1 OiIVzJ44kdRJG8kQWPPua/k+AtwJt/gjCxv5p8sKVXTNtIP/sd3EMs2xwbF8McebLE9JCDQ1 RXVHceAmPWVCq3WrFuX9dSlgf3RWTqNiWZC0a8Hn6fNDp26TzLbdo9mnxbU4I/3BbcAJZI9p 9ELaE9rw3LU8esKqRIfaZqPtrdm1C+e5gZa2gkmEzG+WEsS0MKtJyOFnuglGl1ZBxR1uFvbU VXhewCNoviXxkkPk/DanIgYB1nUtkPC+BHkJJYCyf9Kfl33s/bai34aaxkGXqpKv+CInARg3 fCikcHzYYWKaXS6HABEBAAHCwXwEGAEIACYCGwwWIQSH6ZrVEpascJjzbVq59+x3yCm/lgUC Z8H0qQUJDIjuxgAKCRC59+x3yCm/loAdD/wJCOhPp9711J18B9c4f+eNAk5vrC9Cj3RyOusH Hebb9HtSFm155Zz3xiizw70MSyOVikjbTocFAJo5VhkyuN0QJIP678SWzriwym+EG0B5P97h FSLBlRsTi4KD8f1Ll3OT03lD3o/5Qt37zFgD4mCD6OxAShPxhI3gkVHBuA0GxF01MadJEjMu jWgZoj75rCLG9sC6L4r28GEGqUFlTKjseYehLw0s3iR53LxS7HfJVHcFBX3rUcKFJBhuO6Ha /GggRvTbn3PXxR5UIgiBMjUlqxzYH4fe7pYR7z1m4nQcaFWW+JhY/BYHJyMGLfnqTn1FsIwP dbhEjYbFnJE9Vzvf+RJcRQVyLDn/TfWbETf0bLGHeF2GUPvNXYEu7oKddvnUvJK5U/BuwQXy TRFbae4Ie96QMcPBL9ZLX8M2K4XUydZBeHw+9lP1J6NJrQiX7MzexpkKNy4ukDzPrRE/ruui yWOKeCw9bCZX4a/uFw77TZMEq3upjeq21oi6NMTwvvWWMYuEKNi0340yZRrBdcDhbXkl9x/o skB2IbnvSB8iikbPng1ihCTXpA2yxioUQ96Akb+WEGopPWzlxTTK+T03G2ljOtspjZXKuywV Wu/eHyqHMyTu8UVcMRR44ki8wam0LMs+fH4dRxw5ck69AkV+JsYQVfI7tdOu7+r465LUfg== In-Reply-To: <20260904174452.1913072-1-i.maximets@ovn.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/4/26 7:44 PM, Ilya Maximets wrote: > Conntrack flush supports filtering by zone using CTA_ZONE, but this > attribute is really hard to use from user space applications. The > reason is that it is not possible to tell if it's supported or not. > > Older kernels silently ignore CTA_ZONE. And in that case they just > happily flush all the entries from all zones breaking all the existing > connections. So, applications have to infer support from the kernel > version. While it works in most cases, it's not a particularly > reliable or desired way to check kernel capabilities from applications > that aim to be portable. There should be a better way to probe or > discover features in the kernel. > > The CTA_FILTER interface on the other hand is simple enough to probe. > We can check for NLM_F_DUMP_FILTERED in the dump to see if filtering > is supported. And unknown sub-attributes in CTA_FILTER are rejected > explicitly since strict validation is in use there. > > Let's add new CTA_FILTER_ZONE that signals that CTA_ZONE should be > filtered on. It is a flag, since everything in the CTA_FILTER is a > bit mask, i.e., a form of a flag. If set, it means that CTA_ZONE must > be present and be used for filtering. If the flag is not set however, > the filtering on CTA_ZONE will still take place to ensure backwards > compatibility. So, the flag doesn't really change the filtering > behavior, but it allows user space applications to properly discover > support for CTA_ZONE filtering without need to rely on kernel version > parsing or risk accidental flushes of the entire conntrack table, > and also without modifying the kernel state. > > A new test variant is added to test with and without the new flag. > Since the setup code is moved into a shared function, expectations > replaced with assertions to bail early if the base setup fails to > avoid the cascade of secondary failures that can be misleading. > Error return is only for the SKIP cases. > > Signed-off-by: Ilya Maximets > --- > > One other alternative is to make CTA_FILTER_ZONE a U16 sub-attribute > instead of a FLAG and prioritize it over the CTA_ZONE. But it feels > like a FLAG is better suited for the CTA_FILTER, even if it takes a > bit of extra space in the request. Though I'm OK with reworking this > into U16 or some other mechanism that would make the feature > discoverable, if there are better ideas. > > Documentation/netlink/specs/conntrack.yaml | 5 + > .../linux/netfilter/nfnetlink_conntrack.h | 1 + > net/netfilter/nf_conntrack_netlink.c | 11 ++ > .../net/netfilter/conntrack_dump_flush.c | 143 ++++++++++++------ > 4 files changed, 115 insertions(+), 45 deletions(-) [...] > -FIXTURE_SETUP(conntrack_dump_flush) > +static int conntrack_zone_setup(struct __test_metadata *_metadata, > + struct mnl_socket **sock) > { > struct in6_addr src, dst; > int ret; > > - self->sock = mnl_socket_open(NETLINK_NETFILTER); > - if (!self->sock) { > + *sock = mnl_socket_open(NETLINK_NETFILTER); > + if (!*sock) { > perror("mnl_socket_open"); > - SKIP(return, "cannot open netlink_netfilter socket"); > + SKIP(return -1, "cannot open netlink_netfilter socket"); > } > > - ret = mnl_socket_bind(self->sock, 0, MNL_SOCKET_AUTOPID); > + ret = mnl_socket_bind(*sock, 0, MNL_SOCKET_AUTOPID); > EXPECT_EQ(ret, 0); Sashiko-gemini (sashiko-nipa didn't run, probably because the patch was moved to changes-requested due to the CI issue) pointed out that I missed converting this expectation into an assert. I can do that in v2 once the CI is working again. Best regards, Ilya Maximets.