[PATCH 7/7 v2] tracing: Do not create tracefs files if tracefs lockdown is in effect

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

If on boot up, lockdown is activated for tracefs, don't even bother creating
the files. This can also prevent instances from being created if lockdown is
in effect.

Link: http://lkml.kernel.org/r/CAHk-=whC6Ji=fWnjh2+eS4b15TnbsS4VPVtvBOwCy1jjEG_JHQ@xxxxxxxxxxxxxx

Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 fs/tracefs/inode.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index eeeae0475da9..0caa151cae4e 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -16,6 +16,7 @@
 #include <linux/namei.h>
 #include <linux/tracefs.h>
 #include <linux/fsnotify.h>
+#include <linux/security.h>
 #include <linux/seq_file.h>
 #include <linux/parser.h>
 #include <linux/magic.h>
@@ -390,6 +391,9 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
 	struct dentry *dentry;
 	struct inode *inode;
 
+	if (security_locked_down(LOCKDOWN_TRACEFS))
+		return NULL;
+
 	if (!(mode & S_IFMT))
 		mode |= S_IFREG;
 	BUG_ON(!S_ISREG(mode));
-- 
2.23.0