[PATCH v4 3/3] tracefs: make root directory world-traversable

[Anubhav Shelat]

Change the default tracefs mount mode from 0700 to 0755. This allows
unprivileged users to access the eventfs directories underneath which
already use 0755.

Tracing data files use mode 0440 and 0640 so they are not exposed by
this change. Only the format and id files, which have been marked as
work-readable, become accessible.

Directory listings of kprobes and uprobes, which contain functions or
binaries, become visible to unprivileged users but do not contain kernel
addresses. Admins using probes can restore the previous behavior with
chmod or mount -o mode=700.

Signed-off-by: Anubhav Shelat <ashelat@xxxxxxxxxx>
---
 fs/tracefs/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index f3d6188a3b7b..3a6a0c800a8b 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -23,7 +23,7 @@
 #include <linux/slab.h>
 #include "internal.h"
 
-#define TRACEFS_DEFAULT_MODE	0700
+#define TRACEFS_DEFAULT_MODE	0755
 static struct kmem_cache *tracefs_inode_cachep __ro_after_init;
 
 static struct vfsmount *tracefs_mount;
-- 
2.54.0