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([2a02:a03f:a75e:9a00:5273:4380:96ab:9087]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488fc0f82bbsm203612145e9.3.2026.04.18.05.50.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 18 Apr 2026 05:50:11 -0700 (PDT) Message-ID: Date: Sat, 18 Apr 2026 14:50:11 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] ipv6: Implement limits on extension header parsing To: Daniel Borkmann , kuba@kernel.org Cc: edumazet@google.com, dsahern@kernel.org, tom@herbertland.com, willemdebruijn.kernel@gmail.com, idosch@nvidia.com, pabeni@redhat.com, netdev@vger.kernel.org References: <20260417171831.687053-1-daniel@iogearbox.net> <60b47924-dae4-4a10-b977-75b92e1094c0@gmail.com> Content-Language: en-US From: Justin Iurman In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 4/18/26 14:26, Daniel Borkmann wrote: > Hi Justin, > > On 4/18/26 1:45 PM, Justin Iurman wrote: >> On 4/17/26 19:18, Daniel Borkmann wrote: > [...] >>> diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c >>> index d2cd33e2698d..93f865545a7c 100644 >>> --- a/net/ipv6/sysctl_net_ipv6.c >>> +++ b/net/ipv6/sysctl_net_ipv6.c >>> @@ -135,6 +135,14 @@ static struct ctl_table ipv6_table_template[] = { >>>           .extra1        = SYSCTL_ZERO, >>>           .extra2        = &flowlabel_reflect_max, >>>       }, >>> +    { >>> +        .procname    = "max_ext_hdrs_number", >>> +        .data        = &init_net.ipv6.sysctl.max_ext_hdrs_cnt, >>> +        .maxlen        = sizeof(int), >>> +        .mode        = 0644, >>> +        .proc_handler    = proc_dointvec_minmax, >>> +        .extra1        = SYSCTL_ONE, >>> +    }, >>>       { >>>           .procname    = "max_dst_opts_number", >>>           .data        = &init_net.ipv6.sysctl.max_dst_opts_cnt, >> >> NACKed-by: Justin Iurman >> >> +1000 on the need, but NAK on the way it is done. IMO, we don't want >> yet-another-sysctl for that. Instead, we have (well, not yet, but it's >> about time) this series [1] to enforce ordering and occurrences of >> Extension Headers, which is based on an IETF draft [2] (FYI, draft- >> ietf-6man-eh-limits is dead). I think we should enforce ordering and >> occurrences in this code path too, instead of relying on a sysctl. >> Let's keep both code paths consistent. Hi Daniel, > Hm, that series [1] should probably go to net instead of net-next, but atm +1, would make sense. > hasn't moved since a month. I'd still think max_ext_hdrs_number would be > useful given it has less complexity also for stable, but I guess ultimately > up to maintainers.. In the short term, I agree. What worries me is that we end up with a redundant, or even useless, sysctl once the other series is applied, which will only increase user confusion. Cheers, Justin > Thanks, > Daniel > >>   [1] https://lore.kernel.org/netdev/20260314175124.47010-1- >> tom@herbertland.com/#t >>   [2] https://datatracker.ietf.org/doc/draft-iurman-6man-eh-occurrences/ >