Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932793Ab2B2QX1 (ORCPT ); Wed, 29 Feb 2012 11:23:27 -0500 Received: from mx1.redhat.com ([209.132.183.28]:25063 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932746Ab2B2QXY (ORCPT ); Wed, 29 Feb 2012 11:23:24 -0500 Date: Wed, 29 Feb 2012 17:14:37 +0100 From: Oleg Nesterov To: Will Drewry 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 Subject: Re: [PATCH v11 10/12] ptrace,seccomp: Add PTRACE_SECCOMP support Message-ID: <20120229161437.GA3078@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1547 Lines: 35 On 02/28, Will Drewry wrote: > > On Tue, Feb 28, 2012 at 11:04 AM, Will Drewry wrote: > > On Tue, Feb 28, 2012 at 10:43 AM, Oleg Nesterov wrote: > >> > >> Great. In this case this patch becomes really trivial. Just 2 defines > >> in ptrace.h and the unconditional ptrace_event() under SECCOMP_RET_TRACE. > > hrm the only snag is that I can't then rely on TIF_SYSCALL_TRACE to > ensure seccomp is in the slow-path. Right now, on x86, seccomp is > slow-path, but it doesn't have to be to have the syscall and args. > However, for ptrace to behavior properly, I believed it did need to be > in the slow path. If SECCOMP_RET_TRACE doesn't rely on > PTRACE_SYSCALL, then it introduces a need for seccomp to always be in > the slow path or to flag (somehow) when it needs slow path. My understanding of this magic is very limited, and I'm afraid I misunderstood... So please correct me. But what is the problem? system_call checks _TIF_WORK_SYSCALL_ENTRY which includes _TIF_SECCOMP | _TIF_SYSCALL_TRACE, and jumps to tracesys which does SAVE_REST. Anyway. secure_computing() is called by syscall_trace_enter() which also calls tracehook_report_syscall_entry(). If SECCOMP_RET_TRACE can't do ptrace_event() then why tracehook_report_syscall_entry() is fine? Oleg. -- 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/