Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756649Ab2B1REI (ORCPT ); Tue, 28 Feb 2012 12:04:08 -0500 Received: from mail-lpp01m010-f46.google.com ([209.85.215.46]:47777 "EHLO mail-lpp01m010-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754972Ab2B1REG convert rfc822-to-8bit (ORCPT ); Tue, 28 Feb 2012 12:04:06 -0500 Authentication-Results: mr.google.com; spf=pass (google.com: domain of wad@chromium.org designates 10.152.115.38 as permitted sender) smtp.mail=wad@chromium.org; dkim=pass header.i=wad@chromium.org MIME-Version: 1.0 In-Reply-To: <20120228164335.GC3664@redhat.com> References: <1330140111-17201-1-git-send-email-wad@chromium.org> <1330140111-17201-10-git-send-email-wad@chromium.org> <20120227175407.GD10608@redhat.com> <20120228164335.GC3664@redhat.com> Date: Tue, 28 Feb 2012 11:04:01 -0600 Message-ID: Subject: Re: [PATCH v11 10/12] ptrace,seccomp: Add PTRACE_SECCOMP support From: Will Drewry To: Oleg Nesterov Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com, netdev@vger.kernel.org, x86@kernel.org, arnd@arndb.de, davem@davemloft.net, hpa@zytor.com, mingo@redhat.com, peterz@infradead.org, rdunlap@xenotime.net, mcgrathr@chromium.org, tglx@linutronix.de, luto@mit.edu, eparis@redhat.com, serge.hallyn@canonical.com, djm@mindrot.org, scarybeasts@gmail.com, indan@nul.nu, pmoore@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, eric.dumazet@gmail.com, markus@chromium.org, coreyb@linux.vnet.ibm.com, keescook@chromium.org, Denys Vlasenko Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3937 Lines: 91 On Tue, Feb 28, 2012 at 10:43 AM, Oleg Nesterov wrote: > On 02/27, Will Drewry wrote: >> On Mon, Feb 27, 2012 at 11:54 AM, Oleg Nesterov wrote: >> > On 02/24, Will Drewry wrote: >> >> >> >> ?arch/Kconfig ? ? ? ? ? ? ?| ? ?1 + >> >> ?include/linux/ptrace.h ? ?| ? ?7 +++++-- >> >> ?include/linux/seccomp.h ? | ? ?4 +++- >> >> ?include/linux/tracehook.h | ? ?6 ++++++ >> >> ?kernel/ptrace.c ? ? ? ? ? | ? ?4 ++++ >> >> ?kernel/seccomp.c ? ? ? ? ?| ? 18 ++++++++++++++++++ >> > >> > FYI, this conflicts with the changes -mm tree. >> > >> > The changes in ptrace.* confict with Denys's >> > "ptrace: simplify PTRACE_foo constants and PTRACE_SETOPTIONS code" >> > >> > The change in tracehook.h conflicts with >> > "ptrace: the killed tracee should not enter the syscall" >> >> What's the best way to reconcile this in this day and age? > > Of course I'd prefer if you make this change on top of Denys's patch ;) > > Besides, if you agree with PTRACE_EVENT_SECCOMP/PTRACE_O_SECCOMP you > need only one trivial change in ptrace.h. I think that works quite well :) >> I don't see >> these in kernel-next yet and I can't tell if there is a public -mm >> anywhere anymore. > > Strange... I didn't check, but every patch in > http://marc.info/?l=linux-mm-commits has this note: > > ? ? ? ?The -mm tree is included into linux-next and is updated > ? ? ? ?there every 3-4 working days It appears to have been pulled in ~8 hours ago. I'm rebasing to next now. >> >> --- a/kernel/seccomp.c >> >> +++ b/kernel/seccomp.c >> >> @@ -354,6 +354,24 @@ int __secure_computing_int(int this_syscall) >> >> ? ? ? ? ? ? ? ? ? ? ? seccomp_send_sigsys(this_syscall, reason_code); >> >> ? ? ? ? ? ? ? ? ? ? ? return -1; >> >> ? ? ? ? ? ? ? } >> >> + ? ? ? ? ? ? case SECCOMP_RET_TRACE: { >> >> + ? ? ? ? ? ? ? ? ? ? int ret; >> >> + ? ? ? ? ? ? ? ? ? ? struct pt_regs *regs = task_pt_regs(current); >> >> + ? ? ? ? ? ? ? ? ? ? if (!(test_tsk_thread_flag(current, TIF_SYSCALL_TRACE)) || >> >> + ? ? ? ? ? ? ? ? ? ? ? ? !(current->ptrace & PT_TRACE_SECCOMP)) >> >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? return -1; >> >> + ? ? ? ? ? ? ? ? ? ? /* >> >> + ? ? ? ? ? ? ? ? ? ? ?* PT_TRACE_SECCOMP and seccomp.trace indicate whether >> >> + ? ? ? ? ? ? ? ? ? ? ?* tracehook_report_syscall_entry needs to signal the >> >> + ? ? ? ? ? ? ? ? ? ? ?* tracer. ?This avoids race conditions in hand off and >> >> + ? ? ? ? ? ? ? ? ? ? ?* the requirement for TIF_SYSCALL_TRACE ensures that >> >> + ? ? ? ? ? ? ? ? ? ? ?* we are in the syscall slow path. >> >> + ? ? ? ? ? ? ? ? ? ? ?*/ >> >> + ? ? ? ? ? ? ? ? ? ? current->seccomp.trace = 1; >> >> + ? ? ? ? ? ? ? ? ? ? ret = tracehook_report_syscall_entry(regs); >> >> + ? ? ? ? ? ? ? ? ? ? current->seccomp.trace = 0; >> >> + ? ? ? ? ? ? ? ? ? ? return ret; >> > >> > To be honest, this interface looks a bit strange to me... >> > >> > Once again, sorry if this was already discussed. But perhaps it would >> > be better to introduce PTRACE_EVENT_SECCOMP/PTRACE_O_SECCOMP instead? >> > >> > SECCOMP_RET_TRACE: could simply do ptrace_event(PTRACE_EVENT_SECCOMP) >> > unconditionaly. The tracer can set the option and do PTRACE_CONT if it >> > doesn't want the system call notifications. >> >> Works for me - this also gets rid of the extra int for brief state >> tracking. I'll switch over to that in the next rev. > > Great. In this case this patch becomes really trivial. Just 2 defines > in ptrace.h and the unconditional ptrace_event() under SECCOMP_RET_TRACE. > > But probably you should check fatal_signal_pending(current) after > ptrace_event() returns, ptrace_event() returns void. Ah yeah - I don't want to reintroduce that issue :) Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/