Re: [PATCH] seccomp: add ptrace commands for suspend/resume

From	Oleg Nesterov <oleg@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] seccomp: add ptrace commands for suspend/resume
Date	2015-06-03 19:00 +0200
Message-ID	<pxkbi-71b-37@gated-at.bofh.it> (permalink)
References	<pwDJ0-2Pa-1@gated-at.bofh.it> <pwQPU-5ud-21@gated-at.bofh.it> <pwU78-23B-21@gated-at.bofh.it> <pwZqa-1kB-1@gated-at.bofh.it> <pxjyy-6gc-13@gated-at.bofh.it>
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On 06/03, Tycho Andersen wrote:
>
> On Tue, Jun 02, 2015 at 08:48:48PM +0200, Oleg Nesterov wrote:
>
> > Otherwise, if we use PTRACE_O_ instead, it goes away automatically if
> > the tracer dies or does PTRACE_DETACH.
>
> IIRC the flag goes away, but we still have to do something in
> __ptrace_unlink to clear the seccomp suspended, so I'm not sure if the
> automatic-ness helps us.

But we do not need seccomp->suspended at all?

Unless I missed something PTRACE_O_ needs a one-liner patch (ignoring
the defines in include files),

--- x/kernel/seccomp.c
+++ x/kernel/seccomp.c
@@ -692,6 +692,9 @@ u32 seccomp_phase1(struct seccomp_data *
 	int this_syscall = sd ? sd->nr :
 		syscall_get_nr(current, task_pt_regs(current));
 
+	if (unlikely(current->ptrace & PT_NAME_OF_THIS_OPTION))
+		return OK;
+
 	switch (mode) {
 	case SECCOMP_MODE_STRICT:
 		__secure_computing_strict(this_syscall);  /* may call do_exit */
	

OK, and the same check in secure_computing_strict().

No?

Oleg.

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Re: [PATCH] seccomp: add ptrace commands for suspend/resume Tycho Andersen <tycho.andersen@canonical.com> - 2015-06-03 18:20 +0200
  Re: [PATCH] seccomp: add ptrace commands for suspend/resume Tycho Andersen <tycho.andersen@canonical.com> - 2015-06-03 19:00 +0200
  Re: [PATCH] seccomp: add ptrace commands for suspend/resume Oleg Nesterov <oleg@redhat.com> - 2015-06-03 19:00 +0200

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