Re: [PATCH v3 2/5] seccomp: add the concept of a seccomp filter FD

From	Tycho Andersen <tycho.andersen@canonical.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 2/5] seccomp: add the concept of a seccomp filter FD
Date	2015-09-30 20:40 +0200
Message-ID	<qeush-4KD-13@gated-at.bofh.it> (permalink)
References	<qeu8V-4ns-9@gated-at.bofh.it> <qeu8W-4ns-29@gated-at.bofh.it> <qeuiC-4z9-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Sep 30, 2015 at 11:27:34AM -0700, Andy Lutomirski wrote:
> On Wed, Sep 30, 2015 at 11:13 AM, Tycho Andersen
> <tycho.andersen@canonical.com> wrote:
> > This patch introduces the concept of a seccomp fd, with a similar interface
> > and usage to ebpf fds. Initially, one is allowed to create, install, and
> > dump these fds. Any manipulation of seccomp fds requires users to be root
> > in their own user namespace, matching the checks done for
> > SECCOMP_SET_MODE_FILTER.
> >
> > Installing a filterfd has some gotchas, though. Andy mentioned previously
> > that we should restrict installation to filter fds whose parent is already
> > in the filter tree. This doesn't quite work in the case of created seccomp
> > fds, since once you install a filter fd, you can't install any other filter
> > fd since it has no parent and there is no way to "pre-chain" filters before
> > installing them.
> 
> ISTM, if we like the seccomp fd approach, we should have them be
> created with a parent already set.  IOW the default should be that
> their parent is the creator's seccomp fd and, if needed, creators
> could specify a different parent.

Allowing people doing SECCOMP_FD_NEW to specify a parent fd would
work. Then we can disallow installing a seccomp fd if its parent is
not the current filter, and get rid of the whole mess with prev
locking and all that.

Tycho
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Thread

checkpoint/restore of seccomp filters v3 Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:20 +0200
  [PATCH v3 3/5] seccomp: add a ptrace command to get seccomp filter fds Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:20 +0200
  [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:20 +0200
    Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Andy Lutomirski <luto@amacapital.net> - 2015-09-30 20:30 +0200
      Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Andy Lutomirski <luto@amacapital.net> - 2015-09-30 20:50 +0200
        Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Andy Lutomirski <luto@amacapital.net> - 2015-09-30 21:00 +0200
          Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 23:40 +0200
            Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Andy Lutomirski <luto@amacapital.net> - 2015-09-30 23:50 +0200
              Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Tycho Andersen <tycho.andersen@canonical.com> - 2015-10-01 00:20 +0200
              Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Tycho Andersen <tycho.andersen@canonical.com> - 2015-10-01 18:50 +0200
        Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 21:00 +0200
      Re: [PATCH v3 4/5] kcmp: add KCMP_FILE_PRIVATE_DATA Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:50 +0200
  [PATCH v3 5/5] bpf: save the program the user actually supplied Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:20 +0200
  [PATCH v3 1/5] seccomp: save the original filter Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:20 +0200
  [PATCH v3 2/5] seccomp: add the concept of a seccomp filter FD Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:20 +0200
    Re: [PATCH v3 2/5] seccomp: add the concept of a seccomp filter FD Andy Lutomirski <luto@amacapital.net> - 2015-09-30 20:30 +0200
      Re: [PATCH v3 2/5] seccomp: add the concept of a seccomp filter FD Tycho Andersen <tycho.andersen@canonical.com> - 2015-09-30 20:40 +0200
        Re: [PATCH v3 2/5] seccomp: add the concept of a seccomp filter FD Andy Lutomirski <luto@amacapital.net> - 2015-09-30 20:50 +0200
    Re: [PATCH v3 2/5] seccomp: add the concept of a seccomp filter FD kbuild test robot <lkp@intel.com> - 2015-09-30 20:30 +0200

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