From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aleksa Sarai Subject: Re: [PATCH v4 2/2] tty: add TIOCGPTPEER ioctl Date: Fri, 9 Jun 2017 20:24:30 +1000 Message-ID: References: <20170603141515.9529-1-asarai@suse.de> <20170603141515.9529-3-asarai@suse.de> <20170609092659.GA26933@kroah.com> <44c2b6c7-63ee-5c7f-cc77-5e1bcd69eea4@suse.de> <20170609100442.GA1405@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Cc: Jiri Slaby , Arnd Bergmann , linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-mips@linux-mips.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, Christian Brauner , Valentin Rothberg To: Greg Kroah-Hartman Return-path: In-Reply-To: <20170609100442.GA1405@kroah.com> List-ID: List-Id: linux-parisc.vger.kernel.org >>>> When opening the slave end of a PTY, it is not possible for userspace to >>>> safely ensure that /dev/pts/$num is actually a slave (in cases where the >>>> mount namespace in which devpts was mounted is controlled by an >>>> untrusted process). In addition, there are several unresolvable >>>> race conditions if userspace were to attempt to detect attacks through >>>> stat(2) and other similar methods [in addition it is not clear how >>>> userspace could detect attacks involving FUSE]. >>>> >>>> Resolve this by providing an interface for userpace to safely open the >>>> "peer" end of a PTY file descriptor by using the dentry cached by >>>> devpts. Since it is not possible to have an open master PTY without >>>> having its slave exposed in /dev/pts this interface is safe. This >>>> interface currently does not provide a way to get the master pty (since >>>> it is not clear whether such an interface is safe or even useful). >>>> >>>> Cc: Christian Brauner >>>> Cc: Valentin Rothberg >>>> Signed-off-by: Aleksa Sarai >>> >>> Is this going to be documented anywhere? Is there a man page update >>> that also goes along with this? >> >> I will add one, I didn't know where the man-pages project is hosted / where >> patches get pushed? What is the ML? > > From the MAINTAINERS file: > MAN-PAGES: MANUAL PAGES FOR LINUX -- Sections 2, 3, 4, 5, and 7 > M: Michael Kerrisk > W: http://www.kernel.org/doc/man-pages > L: linux-man@vger.kernel.org > S: Maintained Ah, should've looked there first! Thanks Greg, I'll send it over the weekend. -- Aleksa Sarai Software Engineer (Containers) SUSE Linux GmbH https://www.cyphar.com/