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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435e10e48a6sm29620829f8f.8.2026.01.31.07.37.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 31 Jan 2026 07:37:37 -0800 (PST) Date: Sat, 31 Jan 2026 15:37:35 +0000 From: David Laight To: Linus Torvalds Cc: Breno Leitao , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Kuniyuki Iwashima , Willem de Bruijn , metze@samba.org, axboe@kernel.dk, Stanislav Fomichev , io-uring@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH net-next RFC 0/3] net: move .getsockopt away from __user buffers Message-ID: <20260131153735.3c9273a8@pumpkin> In-Reply-To: References: <20260130-getsockopt-v1-0-9154fcff6f95@debian.org> <20260130205227.6fb1d9ad@pumpkin> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 30 Jan 2026 17:19:55 -0800 Linus Torvalds wrote: > On Fri, 30 Jan 2026 at 14:40, David Laight wrote: > > > > There is not much point making the 'optval' parameter more than > > a structure of a user and kernel address - one of which will be NULL. > > That's exactly what we do *NOT* want. Because people will get it > wrong, and then we're back to the bad old days where trivial bugs > result in security issues. It can still be a (semi-)transparent structure that code isn't allowed to change. That is no different from using iov_iter. > Can you point to an actual case where setsockopt / getsockopt would be > performance-critical? Typically you do it once or twice. IIRC a really horrid one - I think for async io. That is also one of the few where the supplied length is a lie. David > > Linus >