linux-kernel - [PATCH ALT1] audit: ignore tracefs and debugfs on inode child

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Message-Id: <64858354c15e95b4c0465fa29e3d4f0160a49a86.1488338538.git.rgb@redhat.com>
Date:   Tue, 28 Feb 2017 22:24:48 -0500
From:   Richard Guy Briggs <rgb@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-audit@...hat.com
Cc:     Richard Guy Briggs <rgb@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Eric Paris <eparis@...hat.com>, Paul Moore <pmoore@...hat.com>,
        Steve Grubb <sgrubb@...hat.com>
Subject: [PATCH ALT1] audit: ignore tracefs and debugfs on inode child

Tracefs or debugfs were causing hundreds to thousands of null PATH records to
be associated with the init_module and finit_module SYSCALL records on a few
modules when the following rule was in place for startup:
	-a always,exit -F arch=x86_64 -S init_module -F key=mod-load

In __audit_inode_child, return immedialy upon detecting TRACEFS and DEBUGFS
(and potentially other filesystems identified, via dentry->d_sb->s_magic).

See https://github.com/linux-audit/audit-kernel/issues/8
Test case: https://github.com/linux-audit/audit-testsuite/issues/42

Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
---
 kernel/auditsc.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4db32e8..6050441 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1868,6 +1868,11 @@ void __audit_inode_child(struct inode *parent,
 
 	if (!context->in_syscall)
 		return;
+	switch (parent->i_sb->s_magic) {
+	case TRACEFS_MAGIC:
+	case DEBUGFS_MAGIC:
+		return;
+	}
 
 	if (inode)
 		handle_one(inode);
-- 
1.7.1