From: Tycho Andersen <tycho@tycho.ws>
To: Jann Horn <jannh@google.com>
Cc: Kees Cook <keescook@chromium.org>,
kernel list <linux-kernel@vger.kernel.org>,
containers@lists.linux-foundation.org,
Linux API <linux-api@vger.kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Oleg Nesterov <oleg@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Serge E. Hallyn" <serge@hallyn.com>,
Christian Brauner <christian.brauner@ubuntu.com>,
Tyler Hicks <tyhicks@canonical.com>,
suda.akihiro@lab.ntt.co.jp
Subject: Re: [PATCH v6 3/5] seccomp: add a way to get a listener fd from ptrace
Date: Thu, 6 Sep 2018 09:50:08 -0600 [thread overview]
Message-ID: <20180906155008.GA3326@cisco.cisco.com> (raw)
In-Reply-To: <CAG48ez3gRpGZT4Vk7ZZXk5dkYeVfnGsaqeFZeOio0GpqFd=Vow@mail.gmail.com>
On Thu, Sep 06, 2018 at 05:45:25PM +0200, Jann Horn wrote:
> On Thu, Sep 6, 2018 at 5:29 PM Tycho Andersen <tycho@tycho.ws> wrote:
> >
> > As an alternative to SECCOMP_FILTER_FLAG_GET_LISTENER, perhaps a ptrace()
> > version which can acquire filters is useful. There are at least two reasons
> > this is preferable, even though it uses ptrace:
> >
> > 1. You can control tasks that aren't cooperating with you
> > 2. You can control tasks whose filters block sendmsg() and socket(); if the
> > task installs a filter which blocks these calls, there's no way with
> > SECCOMP_FILTER_FLAG_GET_LISTENER to get the fd out to the privileged task.
> [...]
> > +long seccomp_new_listener(struct task_struct *task,
> > + unsigned long filter_off)
> > +{
> > + struct seccomp_filter *filter;
> > + struct file *listener;
> > + int fd;
> > +
> > + if (!capable(CAP_SYS_ADMIN))
> > + return -EACCES;
> > +
> > + filter = get_nth_filter(task, filter_off);
> > + if (IS_ERR(filter))
> > + return PTR_ERR(filter);
> > +
> > + fd = get_unused_fd_flags(0);
> > + if (fd < 0) {
> > + __put_seccomp_filter(filter);
> > + return fd;
> > + }
> > +
> > + listener = init_listener(task, task->seccomp.filter);
>
> Did you mean to write something like `init_listener(task, filter)` here?
Yes, yes I did. Thanks, Jann.
Tycho
next prev parent reply other threads:[~2018-09-06 15:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 15:28 [PATCH v6 0/5] seccomp trap to userspace Tycho Andersen
2018-09-06 15:28 ` [PATCH v6 1/5] seccomp: add a return code to " Tycho Andersen
2018-09-06 22:15 ` Tyler Hicks
2018-09-07 15:45 ` Tycho Andersen
2018-09-08 20:35 ` Tycho Andersen
2018-09-06 15:28 ` [PATCH v6 2/5] seccomp: make get_nth_filter available outside of CHECKPOINT_RESTORE Tycho Andersen
2018-09-11 10:25 ` kbuild test robot
2018-09-06 15:28 ` [PATCH v6 3/5] seccomp: add a way to get a listener fd from ptrace Tycho Andersen
2018-09-06 15:45 ` Jann Horn
2018-09-06 15:50 ` Tycho Andersen [this message]
2018-09-13 0:00 ` Andy Lutomirski
2018-09-13 9:24 ` Tycho Andersen
2018-10-17 7:25 ` Michael Tirado
2018-10-17 15:00 ` Tycho Andersen
[not found] ` <CAMkWEXM1c7AGTH=tpgoHtPnFFY-V+05nGOU90Sa1E3EPY9OhKQ@mail.gmail.com>
2018-10-17 18:15 ` Michael Tirado
2018-10-21 16:00 ` Tycho Andersen
2018-10-17 18:31 ` Kees Cook
2018-09-06 15:28 ` [PATCH v6 4/5] seccomp: add support for passing fds via USER_NOTIF Tycho Andersen
2018-09-06 16:15 ` Jann Horn
2018-09-06 16:22 ` Tycho Andersen
2018-09-06 18:30 ` Tycho Andersen
2018-09-10 17:00 ` Jann Horn
2018-09-11 20:29 ` Tycho Andersen
2018-09-12 23:52 ` Andy Lutomirski
2018-09-13 9:25 ` Tycho Andersen
2018-09-13 9:42 ` Aleksa Sarai
2018-09-19 9:55 ` Tycho Andersen
2018-09-19 14:19 ` Andy Lutomirski
2018-09-19 14:38 ` Tycho Andersen
2018-09-19 19:58 ` Andy Lutomirski
2018-09-20 23:42 ` Tycho Andersen
2018-09-21 2:18 ` Andy Lutomirski
2018-09-21 13:39 ` Tycho Andersen
2018-09-21 18:27 ` Andy Lutomirski
2018-09-21 22:03 ` Tycho Andersen
2018-09-21 20:46 ` Jann Horn
2018-09-25 12:53 ` Tycho Andersen
2018-09-06 15:28 ` [PATCH v6 5/5] samples: add an example of seccomp user trap Tycho Andersen
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