From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f41.google.com (mail-qg0-f41.google.com [209.85.192.41]) by kanga.kvack.org (Postfix) with ESMTP id 2D2ED6B006C for ; Mon, 23 Feb 2015 16:59:22 -0500 (EST) Received: by mail-qg0-f41.google.com with SMTP id i50so26910790qgf.0 for ; Mon, 23 Feb 2015 13:59:22 -0800 (PST) Received: from mail-qg0-f53.google.com (mail-qg0-f53.google.com. [209.85.192.53]) by mx.google.com with ESMTPS id x2si13129205qas.42.2015.02.23.13.59.21 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 23 Feb 2015 13:59:21 -0800 (PST) Received: by mail-qg0-f53.google.com with SMTP id f51so26982699qge.12 for ; Mon, 23 Feb 2015 13:59:21 -0800 (PST) From: Paul Moore Subject: Re: [PATCH v2 2/3] kernel/audit: reduce mmap_sem hold for mm->exe_file Date: Mon, 23 Feb 2015 16:59:19 -0500 Message-ID: <5919995.Ma7fOL8jhY@sifl> In-Reply-To: <1424658009.6539.15.camel@stgolabs.net> References: <1424304641-28965-1-git-send-email-dbueso@suse.de> <1424304641-28965-3-git-send-email-dbueso@suse.de> <1424658009.6539.15.camel@stgolabs.net> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: owner-linux-mm@kvack.org List-ID: To: Davidlohr Bueso Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, eparis@redhat.com, linux-audit@redhat.com On Sunday, February 22, 2015 06:20:09 PM Davidlohr Bueso wrote: > The mm->exe_file is currently serialized with mmap_sem (shared) > in order to both safely (1) read the file and (2) audit it via > audit_log_d_path(). Good users will, on the other hand, make use > of the more standard get_mm_exe_file(), requiring only holding > the mmap_sem to read the value, and relying on reference counting > to make sure that the exe file won't dissapear underneath us. > > Additionally, upon NULL return of get_mm_exe_file, we also call > audit_log_format(ab, " exe=(null)"). > > Signed-off-by: Davidlohr Bueso > --- > > changes from v1: rebased on top of 1/1. > > kernel/audit.c | 22 ++++++++++++++-------- > 1 file changed, 14 insertions(+), 8 deletions(-) Merged into audit#next. > diff --git a/kernel/audit.c b/kernel/audit.c > index a71cbfe..b446d54 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -43,6 +43,7 @@ > > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > +#include > #include > #include > #include > @@ -1841,15 +1842,20 @@ EXPORT_SYMBOL(audit_log_task_context); > void audit_log_d_path_exe(struct audit_buffer *ab, > struct mm_struct *mm) > { > - if (!mm) { > - audit_log_format(ab, " exe=(null)"); > - return; > - } > + struct file *exe_file; > + > + if (!mm) > + goto out_null; > > - down_read(&mm->mmap_sem); > - if (mm->exe_file) > - audit_log_d_path(ab, " exe=", &mm->exe_file->f_path); > - up_read(&mm->mmap_sem); > + exe_file = get_mm_exe_file(mm); > + if (!exe_file) > + goto out_null; > + > + audit_log_d_path(ab, " exe=", &exe_file->f_path); > + fput(exe_file); > + return; > +out_null: > + audit_log_format(ab, " exe=(null)"); > } > > void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk) -- paul moore www.paul-moore.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org