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([2404:4404:133a:4500:138:8204:e16a:7a26]) by smtp.gmail.com with ESMTPSA id v190sm1341964pfv.26.2018.12.06.11.03.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Dec 2018 11:03:52 -0800 (PST) Date: Fri, 07 Dec 2018 08:03:45 +1300 User-Agent: K-9 Mail for Android In-Reply-To: <87y392h4b7.fsf@oldenburg2.str.redhat.com> References: <20181120105124.14733-1-christian@brauner.io> <87in0g5aqo.fsf@oldenburg.str.redhat.com> <746B7C49-CC7B-4040-A7EF-82491796D360@brauner.io> <20181202100304.labt63mzrlr5utdl@brauner.io> <8736rebl9s.fsf@oldenburg.str.redhat.com> <20181203180224.fkvw4kajtbvru2ku@brauner.io> <874lbtjvtd.fsf@oldenburg2.str.redhat.com> <87y392h4b7.fsf@oldenburg2.str.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v2] signal: add procfd_signal() syscall To: Florian Weimer , Andy Lutomirski CC: "Eric W. Biederman" , LKML , "Serge E. Hallyn" , Jann Horn , Andrew Morton , Oleg Nesterov , Aleksa Sarai , Al Viro , Linux FS Devel , Linux API , Daniel Colascione , Tim Murray , linux-man , Kees Cook From: Christian Brauner Message-ID: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On December 7, 2018 7:56:44 AM GMT+13:00, Florian Weimer wrote: >* Andy Lutomirski: > >>> I suppose that's fine=2E Or alternatively, when thread group support >is >>> added, introduce a flag that applications have to use to enable it, >so >>> that they can probe for support by checking support for the flag=2E >>> >>> I wouldn't be opposed to a new system call like this either: >>> >>> int procfd_open (pid_t thread_group, pid_t thread_id, unsigned >flags); >>> >>> But I think this is frowned upon on the kernel side=2E >> >> I have no problem with it, except that I think it shouldn=E2=80=99t ret= urn an >> fd that can be used for proc filesystem access=2E > >Oh no, my intention was that it would just be used with *_send_signal >and related functions=2E Let's postpone that discussion a little=2E I think we don't need a syscall to base this off of pids=2E As I said I rather send my revived version of CLONE_NEWFD that would serve= the same task=2E The same way we could also just add a new open() flag that blocks fs acces= s completely=2E I just pitched that idea to Serge a few days back: O_NOCHDIR or similar=2E That could even be part of Aleksa's path resolution patchset=2E > >Thanks, >Florian