kprobes: Make list and blacklist root user read only

commit f2a3ab3 upstream.

Since the blacklist and list files on debugfs indicates
a sensitive address information to reader, it should be
restricted to the root user.

Suggested-by: Thomas Richter <[email protected]>
Suggested-by: Ingo Molnar <[email protected]>
Signed-off-by: Masami Hiramatsu <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: Anil S Keshavamurthy <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: David Howells <[email protected]>
Cc: David S . Miller <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Jon Medhurst <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tobin C . Harding <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/lkml/152491890171.9916.5183693615601334087.stgit@devbox
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: mhiramat

kernel/kprobes.c

@@ -2441,7 +2441,7 @@ static int __init debugfs_kprobe_init(void)
 	if (!dir)
 		return -ENOMEM;
 
-	file = debugfs_create_file("list", 0444, dir, NULL,
+	file = debugfs_create_file("list", 0400, dir, NULL,
 				&debugfs_kprobes_operations);
 	if (!file)
 		goto error;
@@ -2451,7 +2451,7 @@ static int __init debugfs_kprobe_init(void)
 	if (!file)
 		goto error;
 
-	file = debugfs_create_file("blacklist", 0444, dir, NULL,
+	file = debugfs_create_file("blacklist", 0400, dir, NULL,
 				&debugfs_kprobe_blacklist_ops);
 	if (!file)
 		goto error;