From: Christian Brauner <christian@brauner.io> To: Aleksa Sarai <cyphar@cyphar.com> Cc: ebiederm@xmission.com, linux-kernel@vger.kernel.org, serge@hallyn.com, jannh@google.com, luto@kernel.org, akpm@linux-foundation.org, oleg@redhat.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, dancol@google.com, timmurray@google.com, linux-man@vger.kernel.org, Kees Cook <keescook@chromium.org> Subject: Re: [PATCH v1 2/2] signal: add procfd_signal() syscall Date: Mon, 19 Nov 2018 22:13:43 +0100 [thread overview] Message-ID: <20181119211335.tmoycnu4r2ob6cda@brauner.io> (raw) In-Reply-To: <20181119205518.btew3vxwgva4w3zh@brauner.io> On Mon, Nov 19, 2018 at 09:55:18PM +0100, Christian Brauner wrote: > On Tue, Nov 20, 2018 at 07:28:57AM +1100, Aleksa Sarai wrote: > > On 2018-11-19, Christian Brauner <christian@brauner.io> wrote: > > > + if (info) { > > > + ret = __copy_siginfo_from_user(sig, &kinfo, info); > > > + if (unlikely(ret)) > > > + goto err; > > > + /* > > > + * Not even root can pretend to send signals from the kernel. > > > + * Nor can they impersonate a kill()/tgkill(), which adds > > > + * source info. > > > + */ > > > + ret = -EPERM; > > > + if ((kinfo.si_code >= 0 || kinfo.si_code == SI_TKILL) && > > > + (task_pid(current) != pid)) > > > + goto err; > > > + } else { > > > + prepare_kill_siginfo(sig, &kinfo); > > > + } > > > > I wonder whether we should also have a pidns restriction here, since > > currently it isn't possible for a container process using a pidns to > > signal processes outside its pidns. AFAICS, this isn't done through an > > explicit check -- it's a side-effect of processes in a pidns not being > > able to address non-descendant-pidns processes. > > > > But maybe it's reasonable to allow sending a procfd to a different pidns > > and the same operations working on it? If we extend the procfd API to > > No, I don't think so. I really don't want any fancy semantics in here. > Fancy doesn't get merged and fancy is hard to maintain. So we should do > something like: > > if (proc_pid_ns() != current_pid_ns) > return EINVAL To be more precise, we need to detect if fd refers to an ancestor pidns and if so return EINVAL. > > > allow process creation this would allow a container to create a process > > outside its pidns. > > > > -- > > Aleksa Sarai > > Senior Software Engineer (Containers) > > SUSE Linux GmbH > > <https://www.cyphar.com/> > >
next prev parent reply other threads:[~2018-11-19 21:13 UTC|newest] Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-19 10:32 [PATCH v1 0/2] proc: allow signaling processes via file descriptors Christian Brauner 2018-11-19 10:32 ` [PATCH v1 1/2] proc: get process file descriptor from /proc/<pid> Christian Brauner 2018-11-19 15:32 ` Andy Lutomirski 2018-11-19 18:20 ` Christian Brauner 2018-11-19 10:32 ` [PATCH v1 2/2] signal: add procfd_signal() syscall Christian Brauner 2018-11-19 15:45 ` Andy Lutomirski 2018-11-19 15:57 ` Daniel Colascione 2018-11-19 18:39 ` Christian Brauner 2018-11-19 15:59 ` Daniel Colascione 2018-11-19 18:29 ` Christian Brauner 2018-11-19 19:02 ` Eric W. Biederman 2018-11-19 19:31 ` Christian Brauner 2018-11-19 19:39 ` Daniel Colascione 2018-11-19 17:10 ` Eugene Syromiatnikov 2018-11-19 18:23 ` Christian Brauner 2018-11-19 17:14 ` Eugene Syromiatnikov 2018-11-19 20:28 ` Aleksa Sarai 2018-11-19 20:55 ` Christian Brauner 2018-11-19 21:13 ` Christian Brauner [this message] 2018-11-19 21:18 ` Aleksa Sarai 2018-11-19 21:20 ` Christian Brauner 2018-11-19 21:21 ` Christian Brauner 2018-11-19 21:25 ` Aleksa Sarai 2018-11-19 21:26 ` Daniel Colascione 2018-11-19 21:36 ` Aleksa Sarai 2018-11-19 21:37 ` Christian Brauner 2018-11-19 21:41 ` Daniel Colascione 2018-11-20 4:59 ` Eric W. Biederman 2018-11-20 10:31 ` Christian Brauner 2018-11-21 21:39 ` Serge E. Hallyn 2018-11-19 21:23 ` Aleksa Sarai 2018-11-22 7:41 ` Serge E. Hallyn 2018-11-19 22:39 ` Tycho Andersen 2018-11-19 22:49 ` Daniel Colascione 2018-11-19 23:07 ` Tycho Andersen 2018-11-20 0:27 ` Andy Lutomirski 2018-11-20 0:32 ` Christian Brauner 2018-11-20 0:34 ` Andy Lutomirski 2018-11-20 0:49 ` Daniel Colascione 2018-11-22 7:48 ` Serge E. Hallyn 2018-11-19 23:35 ` kbuild test robot 2018-11-19 23:37 ` kbuild test robot 2018-11-19 23:45 ` Christian Brauner 2018-11-28 21:45 ` Joey Pabalinas 2018-11-28 22:05 ` Christian Brauner 2018-11-28 23:02 ` Joey Pabalinas 2018-11-19 10:32 ` [PATCH] procfd_signal.2: document procfd_signal syscall Christian Brauner 2018-11-20 13:29 ` Michael Kerrisk (man-pages) 2018-11-28 20:59 ` Florian Weimer 2018-11-28 21:12 ` Christian Brauner
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