From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757338Ab1FGRWc (ORCPT ); Tue, 7 Jun 2011 13:22:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53299 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753895Ab1FGRWa (ORCPT ); Tue, 7 Jun 2011 13:22:30 -0400 Date: Tue, 7 Jun 2011 19:19:52 +0200 From: Oleg Nesterov To: Eric Paris Cc: linux-kernel@vger.kernel.org, tony.luck@intel.com, fenghua.yu@intel.com, monstr@monstr.eu, ralf@linux-mips.org, benh@kernel.crashing.org, paulus@samba.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, linux390@de.ibm.com, lethal@linux-sh.org, davem@davemloft.net, jdike@addtoit.com, richard@nod.at, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, linux-ia64@vger.kernel.org, microblaze-uclinux@itee.uq.edu.au, linux-mips@linux-mips.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net Subject: Re: [PATCH -v2] Audit: push audit success and retcode into arch ptrace.h Message-ID: <20110607171952.GA25729@redhat.com> References: <20110603220451.23134.47368.stgit@paris.rdu.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110603220451.23134.47368.stgit@paris.rdu.redhat.com> 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 On 06/03, Eric Paris wrote: > > The audit system previously expected arches calling to audit_syscall_exit to > supply as arguments if the syscall was a success and what the return code was. > Audit also provides a helper AUDITSC_RESULT which was supposed to simplify things > by converting from negative retcodes to an audit internal magic value stating > success or failure. This helper was wrong and could indicate that a valid > pointer returned to userspace was a failed syscall. The fix is to fix the > layering foolishness. We now pass audit_syscall_exit a struct pt_reg and it > in turns calls back into arch code to collect the return value and to > determine if the syscall was a success or failure. We also define a generic > is_syscall_success() macro which determines success/failure based on if the > value is < -MAX_ERRNO. This works for arches like x86 which do not use a > separate mechanism to indicate syscall failure. I know nothing about audit, but the patch looks fine to me. But I have a bit off-topic question, > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S > index 8a445a0..b7b1f88 100644 > --- a/arch/x86/kernel/entry_64.S > +++ b/arch/x86/kernel/entry_64.S > @@ -53,6 +53,7 @@ > #include > #include > #include > +#include > > /* Avoid __ASSEMBLER__'ifying just for this. */ > #include > @@ -564,17 +565,16 @@ auditsys: > jmp system_call_fastpath > > /* > - * Return fast path for syscall audit. Call audit_syscall_exit() > + * Return fast path for syscall audit. Call __audit_syscall_exit() > * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT > * masked off. > */ > sysret_audit: > movq RAX-ARGOFFSET(%rsp),%rsi /* second arg, syscall return value */ > - cmpq $0,%rsi /* is it < 0? */ > - setl %al /* 1 if so, 0 if not */ > + cmpq $-MAX_ERRNO,%rsi /* is it < -MAX_ERRNO? */ > + setbe %al /* 1 if so, 0 if not */ > movzbl %al,%edi /* zero-extend that into %edi */ > - inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */ > - call audit_syscall_exit > + call __audit_syscall_exit With or without this patch, can't we call audit_syscall_exit() twice if there is something else in _TIF_WORK_SYSCALL_EXIT mask apart from SYSCALL_AUDIT ? First time it is called from asm, then from syscall_trace_leave(), no? For example. The task has TIF_SYSCALL_AUDIT and nothing else, it does system_call->auditsys->system_call_fastpath. What if it gets, say, TIF_SYSCALL_TRACE before ret_from_sys_call? Oleg.