tracefs/eventfs: Add missing lockdown checks

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://lkml.kernel.org/r/20230905182711.899724045@goodmis.org
Link: https://lore.kernel.org/all/202309050916.58201dc6-oliver.sang@intel.com/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ajay Kaher <akaher@vmware.com>
Cc: Ching-lin Yu <chinglinyu@google.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 237c6f3..fa1a167 100644 (file)
--- 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;