linux-kernel - [PATCH ALT5] audit: ignore module syscalls on inode child

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Date:   Fri,  3 Mar 2017 18:09:08 -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>, Jessica Yu <jeyu@...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 ALT5] audit: ignore module syscalls 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 module-related
syscalls.

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 |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4db32e8..d7fe943 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1868,6 +1868,12 @@ void __audit_inode_child(struct inode *parent,
 
 	if (!context->in_syscall)
 		return;
+	switch (context->major) {
+	case __NR_init_module:
+	case __NR_delete_module:
+	case __NR_finit_module:
+		return;
+	}
 
 	if (inode)
 		handle_one(inode);
-- 
1.7.1