From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932251AbeCET7J (ORCPT ); Mon, 5 Mar 2018 14:59:09 -0500 Received: from mail-qk0-f196.google.com ([209.85.220.196]:34973 "EHLO mail-qk0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751779AbeCET7H (ORCPT ); Mon, 5 Mar 2018 14:59:07 -0500 X-Google-Smtp-Source: AG47ELt9PndWTf2owNBC28bZ7OlLlhEFg7eLMaGQ09unUeqNndHObqAAFfffY59fAWmY0mij8GZPxg== Date: Mon, 5 Mar 2018 14:59:05 -0500 From: Josef Bacik To: Howard McLauchlan Cc: linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , kernel-team@fb.com, Yonghong Song , Josef Bacik , Omar Sandoval Subject: Re: [PATCH] uprobe: add support for overlayfs Message-ID: <20180305195904.sliaqqv4dzuebque@destiny> References: <20180228004014.445-1-hmclauchlan@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180228004014.445-1-hmclauchlan@fb.com> User-Agent: NeoMutt/20170714 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 27, 2018 at 04:40:14PM -0800, Howard McLauchlan wrote: > uprobes cannot successfully attach to binaries located in a directory > mounted with overlayfs. > > To verify, create directories for mounting overlayfs > (upper,lower,work,merge), move some binary into merge/ and use readelf > to obtain some known instruction of the binary. I used /bin/true and the > entry instruction(0x13b0): > > $ mount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work merge > $ cd /sys/kernel/debug/tracing > $ echo 'p:true_entry PATH_TO_MERGE/merge/true:0x13b0' > uprobe_events > $ echo 1 > events/uprobes/true_entry/enable > > This returns 'bash: echo: write error: Input/output error' and dmesg > tells us 'event trace: Could not enable event true_entry' > > This change makes create_trace_uprobe() look for the real inode of a > dentry. In the case of normal filesystems, this simplifies to just > returning the inode. In the case of overlayfs(and similar fs) we will > obtain the underlying dentry and corresponding inode, upon which uprobes > can successfully register. > > Running the example above with the patch applied, we can see that the > uprobe is enabled and will output to trace as expected. > > Signed-off-by: Howard McLauchlan Reviewed-by: Josef Bacik Thanks, Josef