From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752284AbeDLByn (ORCPT ); Wed, 11 Apr 2018 21:54:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:48352 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751734AbeDLBym (ORCPT ); Wed, 11 Apr 2018 21:54:42 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AF707217A6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Message-Id: <20180412015440.633150795@goodmis.org> User-Agent: quilt/0.63-1 Date: Wed, 11 Apr 2018 21:54:01 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Linus Torvalds , Ingo Molnar , Andrew Morton , Josef Bacik , Masami Hiramatsu , Srikar Dronamraju , Howard McLauchlan Subject: [PATCH 2/5] tracing/uprobe: Add support for overlayfs References: <20180412015359.244491749@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=0002-tracing-uprobe-Add-support-for-overlayfs.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Howard McLauchlan 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. Link: http://lkml.kernel.org/r/20180410231030.2720-1-hmclauchlan@fb.com Reviewed-by: Josef Bacik Reviewed-by: Masami Hiramatsu Reviewed-by: Srikar Dronamraju Signed-off-by: Howard McLauchlan Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_uprobe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 268029ae1be6..8b86d76c55ee 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -446,7 +446,7 @@ static int create_trace_uprobe(int argc, char **argv) if (ret) goto fail_address_parse; - inode = igrab(d_inode(path.dentry)); + inode = igrab(d_real_inode(path.dentry)); path_put(&path); if (!inode || !S_ISREG(inode->i_mode)) { -- 2.16.3