linux-kernel - [PATCH 2/2] tracefs/eventfs: Add missing lockdown checks

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Date:   Tue, 05 Sep 2023 14:26:09 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ajay Kaher <akaher@...are.com>,
        kernel test robot <oliver.sang@...el.com>,
        Ching-lin Yu <chinglinyu@...gle.com>
Subject: [PATCH 2/2] tracefs/eventfs: Add missing lockdown checks

From: "Steven Rostedt (Google)" <rostedt@...dmis.org>

All the eventfs external functions do not check if TRACEFS_LOCKDOWN was
set or not. This can caused some functions to return success while others
fail, which can trigger unexpected errors.

Add the missing lockdown checks.

Link: https://lore.kernel.org/all/202309050916.58201dc6-oliver.sang@intel.com/

Reported-by: kernel test robot <oliver.sang@...el.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 fs/tracefs/event_inode.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 237c6f370ad9..fa1a1679a886 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -491,6 +491,9 @@ struct dentry *eventfs_create_events_dir(const char *name,
 	struct tracefs_inode *ti;
 	struct inode *inode;
 
+	if (security_locked_down(LOCKDOWN_TRACEFS))
+		return NULL;
+
 	if (IS_ERR(dentry))
 		return dentry;
 
@@ -538,6 +541,9 @@ struct eventfs_file *eventfs_add_subsystem_dir(const char *name,
 	struct eventfs_inode *ei_parent;
 	struct eventfs_file *ef;
 
+	if (security_locked_down(LOCKDOWN_TRACEFS))
+		return NULL;
+
 	if (!parent)
 		return ERR_PTR(-EINVAL);
 
@@ -569,6 +575,9 @@ struct eventfs_file *eventfs_add_dir(const char *name,
 {
 	struct eventfs_file *ef;
 
+	if (security_locked_down(LOCKDOWN_TRACEFS))
+		return NULL;
+
 	if (!ef_parent)
 		return ERR_PTR(-EINVAL);
 
@@ -606,6 +615,9 @@ int eventfs_add_events_file(const char *name, umode_t mode,
 	struct eventfs_inode *ei;
 	struct eventfs_file *ef;
 
+	if (security_locked_down(LOCKDOWN_TRACEFS))
+		return -ENODEV;
+
 	if (!parent)
 		return -EINVAL;
 
@@ -654,6 +666,9 @@ int eventfs_add_file(const char *name, umode_t mode,
 {
 	struct eventfs_file *ef;
 
+	if (security_locked_down(LOCKDOWN_TRACEFS))
+		return -ENODEV;
+
 	if (!ef_parent)
 		return -EINVAL;
 
-- 
2.40.1