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([2a01:e0a:b41:c160:6a1d:efff:fe52:1959]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4854b5f6c24sm182910485e9.5.2026.03.13.03.59.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Mar 2026 03:59:44 -0700 (PDT) Message-ID: <3d9d384f-d001-4293-b7d5-7a88596ffc1d@6wind.com> Date: Fri, 13 Mar 2026 11:59:43 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: nicolas.dichtel@6wind.com Subject: Re: [PATCH net-next v2] seg6: add per-route tunnel source address To: Justin Iurman Cc: Andrea Mayer , netdev@vger.kernel.org, davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, justin.iurman@gmail.com, stefano.salsano@uniroma2.it References: <20260311152845.278354-1-justin.iurman@6wind.com> <20260313030220.af70f3b5f2c5d2cb7b4a840e@uniroma2.it> <43e16e45-5fb1-4413-bbd1-4752bbcdec7d@6wind.com> From: Nicolas Dichtel Content-Language: en-US Organization: 6WIND In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Le 13/03/2026 à 11:20, Justin Iurman a écrit : > On Fri, Mar 13, 2026 at 9:47 AM Nicolas Dichtel > wrote: >> >> Le 13/03/2026 à 09:44, Justin Iurman a écrit : >>> On Fri, Mar 13, 2026 at 2:02 AM Andrea Mayer wrote: >>>> >>>> On Wed, 11 Mar 2026 16:28:45 +0100 >>>> Justin Iurman wrote: >> > > [snip] > >>>> Whether to also reject link-local is debatable: ip6_forward() does >>>> drop it, but is there a legitimate use case where a link-local tunnel >>>> source would actually be needed?! >>>> I'd argue we should reject link-local addresses as well. >>>> For instance, using them as a tunnel source violates scope boundaries and >>>> breaks ICMPv6 error reporting. >>> >>> IMHO, I also think we could reasonably forbid LLs. >> >> Why rejecting LL? It's legal to use LL as a source address of a tunnel (and >> forwarding packets in this tunnel). Is this forbidden with srv6? > > Well, this is indeed legal (at least nothing prevents it), but they're > not routable. So question is does it make sense at all? We're talking > about two nodes on the same layer-2 link as the only valid use-case > here. I'm not sure it makes sense, especially in the context of SRv6. Yes, you're probably right. I'm usually uncomfortable with a configuration being forbidden without any real problem/reason.