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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id g24sm16750072pfi.81.2019.10.01.11.46.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Oct 2019 11:46:46 -0700 (PDT) Date: Tue, 1 Oct 2019 11:46:45 -0700 From: Kees Cook To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Linus Torvalds , Andi Kleen , Andi Kleen , Cong Wang , Luis Chamberlain , Alex Smith , Anders Berg , Apelete Seketeli , Arnd Bergmann , Chee Nouk Phoon , Chris Zankel , Christian Ruppert , Greg Ungerer , Harvey Hunt , Helge Deller , Hongliang Tao , Hua Yan , Huacai Chen , John Crispin , Jonas Jensen , Josh Boyer , Jun Nie , Kevin Hilman , Kevin Wells , Kumar Gala , Lars-Peter Clausen , Ley Foon Tan , Linus Walleij , Markos Chandras , Max Filippov , Noam Camus , Olof Johansson , Paul Burton , Paul Mundt , Phil Edworthy , Pierrick Hascoet , Ralf Baechle , Roland Stigge , Santosh Shilimkar , Scott Telford , Stephen Boyd , "Steven J. Hill" , Tanmay Inamdar , Vineet Gupta Subject: Re: [RFC][PATCH] sysctl: Remove the sysctl system call Message-ID: <201910011140.EA0181F13@keescook> References: <8736gcjosv.fsf@x220.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8736gcjosv.fsf@x220.int.ebiederm.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 01, 2019 at 01:36:32PM -0500, Eric W. Biederman wrote: > > This system call has been deprecated almost since it was introduced, and > in a survey of the linux distributions I can no longer find any of them > that enable CONFIG_SYSCTL_SYSCALL. The only indication that I can find > that anyone might care is that a few of the defconfigs in the kernel > enable CONFIG_SYSCTL_SYSCALL. However this appears in only 31 of 414 > defconfigs in the kernel, so I suspect this symbols presence is simply > because it is harmless to include rather than because it is necessary. > > As there appear to be no users of the sysctl system call, remove the > code. As this removes one of the few uses of the internal kernel mount > of proc I hope this allows for even more simplifications of the proc > filesystem. I'm for it. :) I tripped over this being deprecated over a decade ago. :P I think you can actually take this further and remove (or at least empty) the uapi/linux/sysctl.h file too. -- Kees Cook