linux-kernel - [PATCH v2 1/1] audit_alloc: clear TIF_SYSCALL_AUDIT if !audit

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Message-ID: <20130915171109.GA15418@redhat.com>
Date:	Sun, 15 Sep 2013 19:11:09 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Eric Paris <eparis@...hat.com>, Kees Cook <keescook@...omium.org>,
	Richard Guy Briggs <rgb@...hat.com>,
	Steve Grubb <sgrubb@...hat.com>,
	Zach Levis <zml@...ux.vnet.ibm.com>, linux-audit@...hat.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/1] audit_alloc: clear TIF_SYSCALL_AUDIT if
	!audit_context

If audit_filter_task() nacks the new thread it makes sense
to clear TIF_SYSCALL_AUDIT which can be copied from parent
by dup_task_struct().

A wrong TIF_SYSCALL_AUDIT is not really bad but it triggers
the "slow" audit paths in entry.S to ensure the task can not
miss audit_syscall_*() calls, this is pointless if the task
has no ->audit_context.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Acked-by: Steve Grubb <sgrubb@...hat.com>
---
 kernel/auditsc.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 9845cb3..95293ab 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -943,8 +943,10 @@ int audit_alloc(struct task_struct *tsk)
 		return 0; /* Return if not auditing. */
 
 	state = audit_filter_task(tsk, &key);
-	if (state == AUDIT_DISABLED)
+	if (state == AUDIT_DISABLED) {
+		clear_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
 		return 0;
+	}
 
 	if (!(context = audit_alloc_context(state))) {
 		kfree(key);
-- 
1.5.5.1


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