From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1EF21250E9; Thu, 4 Jan 2024 16:26:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B34AC433C7; Thu, 4 Jan 2024 16:26:47 +0000 (UTC) Date: Thu, 4 Jan 2024 11:27:52 -0500 From: Steven Rostedt To: Petr Mladek Cc: Greg KH , =?UTF-8?B?5a2f5pWs5ae/?= , john.ogness@linutronix.de, senozhatsky@chromium.org, keescook@chromium.org, tony.luck@intel.com, gpiccoli@igalia.com, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: Suggestion for Capability Check Refinement in check_syslog_permissions() Message-ID: <20240104112752.120cb566@gandalf.local.home> In-Reply-To: References: <1ee10aa6.d064.18ccdb23971.Coremail.mengjingzi@iie.ac.cn> <2024010306-tweezers-skinhead-083e@gregkh> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@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 Thu, 4 Jan 2024 10:43:53 +0100 Petr Mladek wrote: > And CAP_SYS_ADMIN has really been deprecated last 13 years, see the > commit ee24aebffb75a7f940cf ("cap_syslog: accept CAP_SYS_ADMIN for now"). > > Maybe, it is really time to remove it. Perhaps what we should do is to remove it in a simple change that can be easily reverted if someone complains. The point is, Linus always says "Don't break user space", but he has even said that we have broken user API before, but as long as no user space breaks, it's OK. It's the "tree falls in the forest" analogy. If we break user space API, but no user space application uses it, did it really break? If nothing is using CAP_SYS_ADMIN why keep it? If we remove it, and nobody complains, it means that nothing broke. If we remove it and someone complains, then we know it's still needed and we revert the removal just like Linus would do with any other commit that broke user space. -- Steve