From: Oleg Nesterov <oleg@redhat.com>
To: Eric Paris <eparis@redhat.com>
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
Date: Tue, 7 Jun 2011 19:19:52 +0200 [thread overview]
Message-ID: <20110607171952.GA25729@redhat.com> (raw)
In-Reply-To: <20110603220451.23134.47368.stgit@paris.rdu.redhat.com>
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 <asm/paravirt.h>
> #include <asm/ftrace.h>
> #include <asm/percpu.h>
> +#include <linux/err.h>
>
> /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
> #include <linux/elf-em.h>
> @@ -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.
next prev parent reply other threads:[~2011-06-07 17:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-03 22:04 [PATCH -v2] Audit: push audit success and retcode into arch ptrace.h Eric Paris
2011-06-03 22:52 ` Tony Luck
2011-06-04 22:36 ` Richard Weinberger
2011-06-06 20:17 ` David Miller
2011-06-07 17:19 ` Oleg Nesterov [this message]
2011-06-07 18:53 ` Eric Paris
2011-06-08 16:36 ` Oleg Nesterov
2011-06-08 18:13 ` Eric Paris
2011-06-08 18:37 ` Oleg Nesterov
2011-06-08 19:19 ` Oleg Nesterov
2011-06-08 14:04 ` Ralf Baechle
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