From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [RFC PATCH v1 0/5] Add support for O_MAYEXEC From: Mimi Zohar Date: Thu, 13 Dec 2018 06:04:20 -0500 In-Reply-To: <20181213030228.GM6830@bombadil.infradead.org> References: <20181212081712.32347-1-mic@digikod.net> <20181213030228.GM6830@bombadil.infradead.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <1544699060.6703.11.camel@linux.ibm.com> To: Matthew Wilcox , =?ISO-8859-1?Q?Micka=EBl_Sala=FCn?= Cc: linux-kernel@vger.kernel.org, Al Viro , James Morris , Jonathan Corbet , Kees Cook , Matthew Garrett , Michael Kerrisk , =?ISO-8859-1?Q?Micka=EBl_Sala=FCn?= , Philippe =?ISO-8859-1?Q?Tr=E9buchet?= , Shuah Khan , Thibaut Sautereau , Vincent Strubel , Yves-Alexis Perez , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org List-ID: On Wed, 2018-12-12 at 19:02 -0800, Matthew Wilcox wrote: > On Wed, Dec 12, 2018 at 09:17:07AM +0100, Mickaël Salaün wrote: > > The goal of this patch series is to control script interpretation. A > > new O_MAYEXEC flag used by sys_open() is added to enable userland script > > interpreter to delegate to the kernel (and thus the system security > > policy) the permission to interpret scripts or other files containing > > what can be seen as commands. > > I don't have a problem with the concept, but we're running low on O_ bits. > Does this have to be done before the process gets a file descriptor, > or could we have a new syscall? Since we're going to be changing the > interpreters anyway, it doesn't seem like too much of an imposition to > ask them to use: > > int verify_for_exec(int fd) > > instead of adding an O_MAYEXEC. The indication needs to be set during file open, before the open returns to the caller.  This is the point where ima_file_check() verifies the file's signature.  On failure, access to the file is denied. Mimi