From: Oleg Nesterov <oleg@redhat.com>
To: Amnon Shiloh <u3557@miso.sublimeip.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Pedro Alves <palves@redhat.com>,
Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>,
Pavel Emelyanov <xemul@parallels.com>,
Steven Rostedt <rostedt@goodmis.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org
Subject: PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace: fix the range check)
Date: Sun, 2 Dec 2012 20:30:58 +0100 [thread overview]
Message-ID: <20121202193058.GA4264@redhat.com> (raw)
In-Reply-To: <20121125234834.DAC34592076@miso.sublimeip.com>
Amnon, sorry for delay...
On 11/26, Amnon Shiloh wrote:
>
> > Why do you need to _prevent_, say, sys_gettimeofday()? Why we can't
> > change emulate_vsyscall() to respect PTRACE_SYSCALL and report
> > TRAP_VSYSCALL or PTRACE_EVENT_VSYSCALL as I tried to suggest in
> > http://marc.info/?l=linux-kernel&m=135343635523715 ?
> >
> > Oleg.
> >
>
> For my own application, I would be happy with this.
OK, good.
> But I suspect it might break current versions of "strace",
> ...
> I think it COULD work, but not based on PTRACE_SYSCALL
> (or PTRACE_SYSEMU) alone. A new ptrace option will be needed, saying:
> "Yes, I am aware of TRAP_VSYSCALL and I know how to handle it."
Yes, that is why I said this needs the new option.
However. Of course it would be nice to avoid the new option. IMO it
would be better to do nothing ;) vsyscall is deprecated, and EMULATE
is x86-specific.
May be we could simply do something like the patch below? (Just in
case, this hack is only for illustration, it is not complete).
If the tracer does PTRACE_SYSCALL the tracee reports syscall exit
_after_ gettimeofday/etc. The tracer can look at regs->orig_ax == -1
and detect that this is not syscall but vsyscall, it can look at
regs->ip then (not with the patch below).
Denys, Jan, Pedro. Do you think this change can break/confuse
gdb/strace ?
> While for my own application, just fixing the range-check in
> arch_check_bp_in_kernelspace will do,
You forgot again that EMULATE does not execute the code in the
vsyscall page.
Oleg.
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -186,6 +186,8 @@ static bool write_ok_or_segv(unsigned long ptr, size_t size)
}
}
+#include <linux/tracehook.h>
+
bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
{
struct task_struct *tsk;
@@ -312,6 +314,8 @@ do_ret:
regs->ip = caller;
regs->sp += 8;
done:
+ if (test_thread_flag(TIF_SYSCALL_TRACE))
+ ptrace_report_syscall(regs);
return true;
sigsegv:
next prev parent reply other threads:[~2012-12-02 19:31 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-09 18:29 [PATCH] arch_check_bp_in_kernelspace: fix the range check Oleg Nesterov
2012-11-09 18:30 ` Oleg Nesterov
2012-11-19 17:47 ` Oleg Nesterov
2012-11-19 18:25 ` Steven Rostedt
2012-11-20 10:33 ` u3557
2012-11-20 15:48 ` Oleg Nesterov
2012-11-20 15:55 ` Steven Rostedt
2012-11-20 18:32 ` Oleg Nesterov
2012-11-20 23:16 ` u3557
2012-11-21 14:16 ` Oleg Nesterov
2012-11-21 17:30 ` Amnon Shiloh
2012-11-22 16:12 ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range check) Oleg Nesterov
2012-11-22 20:57 ` Pavel Emelyanov
2012-11-23 0:20 ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range Amnon Shiloh
2012-11-23 17:45 ` Oleg Nesterov
2012-11-24 12:47 ` Amnon Shiloh
2012-11-23 17:42 ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range check) Oleg Nesterov
2012-11-23 9:14 ` arch_check_bp_in_kernelspace: fix the range check Amnon Shiloh
2012-11-23 16:33 ` Oleg Nesterov
2012-11-23 17:05 ` Oleg Nesterov
2012-11-24 14:14 ` Amnon Shiloh
2012-11-24 13:45 ` Amnon Shiloh
2012-11-25 22:55 ` Oleg Nesterov
2012-11-25 23:48 ` Amnon Shiloh
2012-12-02 19:30 ` Oleg Nesterov [this message]
2012-12-02 23:54 ` PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace: fix the range check) u3557
2012-12-04 17:59 ` Oleg Nesterov
2012-12-04 22:44 ` u3557
2013-01-08 17:08 ` Pedro Alves
2013-01-09 17:52 ` Oleg Nesterov
2013-01-10 6:54 ` u3557
2013-01-12 18:12 ` Oleg Nesterov
2013-01-14 2:31 ` u3557
2013-01-14 16:01 ` Oleg Nesterov
2013-02-18 1:39 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-18 5:44 ` prctl(PR_SET_MM) Randy Dunlap
2013-02-18 15:21 ` prctl(PR_SET_MM) Steven Rostedt
2013-02-18 16:33 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-18 19:49 ` prctl(PR_SET_MM) Steven Rostedt
2013-02-19 6:25 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-20 8:39 ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-20 9:38 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-20 10:51 ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-20 11:16 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-21 7:46 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-21 8:00 ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-21 8:03 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-21 8:09 ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-21 22:18 ` prctl(PR_SET_MM) Andrew Morton
2013-02-21 22:42 ` prctl(PR_SET_MM) Cyrill Gorcunov
2013-02-22 1:18 ` prctl(PR_SET_MM) Amnon Shiloh
2013-02-22 14:23 ` prctl(PR_SET_MM) Denys Vlasenko
2012-12-05 9:29 ` PTRACE_SYSCALL && vsyscall (Was: arch_check_bp_in_kernelspace: fix the range check) Jan Kratochvil
2012-12-05 13:14 ` u3557
2012-11-26 9:44 ` vdso && cr " Cyrill Gorcunov
2012-11-26 12:27 ` Andrey Wagin
2012-11-26 12:55 ` Amnon Shiloh
2012-11-26 14:18 ` Cyrill Gorcunov
2012-11-26 14:26 ` vdso && cr (Was: arch_check_bp_in_kernelspace: fix the range Amnon Shiloh
2012-11-26 14:41 ` vdso && cr Cyrill Gorcunov
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