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Tue, 17 Mar 2026 05:19:29 -0400 (EDT) Date: Tue, 17 Mar 2026 10:19:27 +0100 From: Sabrina Dubroca To: Jakub Kicinski Cc: Wilfred Mallawa , "corbet@lwn.net" , "dlemoal@kernel.org" , "davem@davemloft.net" , "linux-doc@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "john.fastabend@gmail.com" , "linux-kernel@vger.kernel.org" , Alistair Francis , "pabeni@redhat.com" , "skhan@linuxfoundation.org" , "horms@kernel.org" , "edumazet@google.com" , Daiki Ueno , Simo Sorce , "netdev@vger.kernel.org" Subject: Re: [RFC net-next 1/3] net/tls_sw: support randomized zero padding Message-ID: References: <20260309054837.2299732-2-wilfred.opensource@gmail.com> <20260309054837.2299732-3-wilfred.opensource@gmail.com> <20260314073919.2f92b966@kernel.org> <9e9f6eb89ba95e9fbb764e2807420e98b566bf37.camel@wdc.com> <20260316180355.37d45785@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260316180355.37d45785@kernel.org> 2026-03-16, 18:03:55 -0700, Jakub Kicinski wrote: > On Tue, 17 Mar 2026 00:53:07 +0000 Wilfred Mallawa wrote: > > > Or maybe you could refer to existing implementations of this feature > > > in user space libs? The padding feature seems slightly nebulous, > > > I wasn't aware of anyone actually using it. Maybe I should ask... > > > are you actually planning to use it, or are you checking a box? > > > > For upcoming WD hardware, we were planning on informing users to use > > this feature if an extra layer of security can benefit their particular > > configuration. But to answer your question, I think this falls more > > into the "checking a box"... > > > > I'm happy to drop this series if there's not much added value from > > having this as an available option for users. > > I'm not much of a security person, and maybe Sabrina will disagree > but I feel like it's going to be hard for us to design this feature > in a sensible way if we don't know at least one potential attack :S No, same here, that's why I tried to CC some userspace developers on the cover (as well as for awareness of what's going on in the kernel and the API being discussed -- adding them here again). My understanding is that attacks of this type are mainly "observers will figure out what type of traffic I'm doing based on message length", and I feel all those "traffic pattern masking" features are only interesting for very paranoid users. The RFC links to some research, and maybe the kind of statistics/machine learning that those attacks require has improved since, which could make such attacks more realistic? No idea. -- Sabrina