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[PATCH 00/14] run seccomp after ptrace

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There has been a long-standing (and documented) issue with seccomp
where ptrace can be used to change a syscall out from under seccomp.
This is a problem for containers and other wider seccomp filtered
environments where ptrace needs to remain available, as it allows
for an escape of the seccomp filter.

Since the ptrace attack surface is available for any allowed syscall,
moving seccomp after ptrace doesn't increase the actually available
attack surface. And this actually improves tracing since, for
example, tracers will be notified of syscall entry before seccomp
sends a SIGSYS, which makes debugging filters much easier.

The per-architecture changes do make one (hopefully small)
semantic change, which is that since ptrace comes first, it may
request a syscall be skipped. Running seccomp after this doesn't
make sense, so if ptrace wants to skip a syscall, it will bail
out early similarly to how seccomp was. This means that skipped
syscalls will not be fed through audit, though that likely means
we're actually avoiding noise this way.

This series first cleans up seccomp to remove the now unneeded
two-phase entry, fixes the SECCOMP_RET_TRACE hole (same as the
ptrace hole above), and then reorders seccomp after ptrace on
each architecture.

Thanks,

-Kees

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[PATCH 00/14] run seccomp after ptrace Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200
  [PATCH 10/14] parisc/ptrace: run seccomp after ptrace Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200
  [PATCH 11/14] s390/ptrace: run seccomp after ptrace Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200
    Re: [PATCH 11/14] s390/ptrace: run seccomp after ptrace Martin Schwidefsky <schwidefsky@de.ibm.com> - 2016-06-10 13:00 +0200
  [PATCH 01/14] seccomp: add tests for ptrace hole Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200
  [PATCH 05/14] seccomp: recheck the syscall after RET_TRACE Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200
    Re: [PATCH 05/14] seccomp: recheck the syscall after RET_TRACE Andy Lutomirski <luto@amacapital.net> - 2016-06-10 00:50 +0200
  [PATCH 06/14] x86/ptrace: run seccomp after ptrace Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200
    Re: [PATCH 06/14] x86/ptrace: run seccomp after ptrace Andy Lutomirski <luto@amacapital.net> - 2016-06-10 01:00 +0200
      Re: [PATCH 06/14] x86/ptrace: run seccomp after ptrace Kees Cook <keescook@chromium.org> - 2016-06-10 04:10 +0200
  [PATCH 07/14] arm/ptrace: run seccomp after ptrace Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200
  [PATCH 03/14] x86/entry: Get rid of two-phase syscall entry work Kees Cook <keescook@chromium.org> - 2016-06-09 23:10 +0200

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