kernfs: pass struct ns_common instead of const void * for namespace tags

kernfs has historically used const void * to pass around namespace tags
used for directory-level namespace filtering. The only current user of
this is sysfs network namespace tagging where struct net pointers are
cast to void *.

Replace all const void * namespace parameters with const struct
ns_common * throughout the kernfs, sysfs, and kobject namespace layers.
This includes the kobj_ns_type_operations callbacks, kobject_namespace(),
and all sysfs/kernfs APIs that accept or return namespace tags.

Passing struct ns_common is needed because various codepaths require
access to the underlying namespace. A struct ns_common can always be
converted back to the concrete namespace type (e.g., struct net) via
container_of() or to_ns_common() in the reverse direction.

This is a preparatory change for switching to ns_id-based directory
iteration to prevent a KASLR pointer leak through the current use of
raw namespace pointers as hash seeds and comparison keys.

Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 12 insertions, 12 deletions

diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 99b775f3ff46..468259fb6049 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -396,13 +396,13 @@ struct sysfs_ops {
 
 #ifdef CONFIG_SYSFS
 
-int __must_check sysfs_create_dir_ns(struct kobject *kobj, const void *ns);
+int __must_check sysfs_create_dir_ns(struct kobject *kobj, const struct ns_common *ns);
 void sysfs_remove_dir(struct kobject *kobj);
 int __must_check sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
-				     const void *new_ns);
+				     const struct ns_common *new_ns);
 int __must_check sysfs_move_dir_ns(struct kobject *kobj,
 				   struct kobject *new_parent_kobj,
-				   const void *new_ns);
+				   const struct ns_common *new_ns);
 int __must_check sysfs_create_mount_point(struct kobject *parent_kobj,
 					  const char *name);
 void sysfs_remove_mount_point(struct kobject *parent_kobj,
@@ -410,7 +410,7 @@ void sysfs_remove_mount_point(struct kobject *parent_kobj,
 
 int __must_check sysfs_create_file_ns(struct kobject *kobj,
 				      const struct attribute *attr,
-				      const void *ns);
+				      const struct ns_common *ns);
 int __must_check sysfs_create_files(struct kobject *kobj,
 				   const struct attribute * const *attr);
 int __must_check sysfs_chmod_file(struct kobject *kobj,
@@ -419,7 +419,7 @@ struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
 						  const struct attribute *attr);
 void sysfs_unbreak_active_protection(struct kernfs_node *kn);
 void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
-			  const void *ns);
+			  const struct ns_common *ns);
 bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr);
 void sysfs_remove_files(struct kobject *kobj, const struct attribute * const *attr);
 
@@ -437,7 +437,7 @@ void sysfs_remove_link(struct kobject *kobj, const char *name);
 
 int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *target,
 			 const char *old_name, const char *new_name,
-			 const void *new_ns);
+			 const struct ns_common *new_ns);
 
 void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
 			const char *name);
@@ -502,7 +502,7 @@ ssize_t sysfs_bin_attr_simple_read(struct file *file, struct kobject *kobj,
 
 #else /* CONFIG_SYSFS */
 
-static inline int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
+static inline int sysfs_create_dir_ns(struct kobject *kobj, const struct ns_common *ns)
 {
 	return 0;
 }
@@ -512,14 +512,14 @@ static inline void sysfs_remove_dir(struct kobject *kobj)
 }
 
 static inline int sysfs_rename_dir_ns(struct kobject *kobj,
-				      const char *new_name, const void *new_ns)
+				      const char *new_name, const struct ns_common *new_ns)
 {
 	return 0;
 }
 
 static inline int sysfs_move_dir_ns(struct kobject *kobj,
 				    struct kobject *new_parent_kobj,
-				    const void *new_ns)
+				    const struct ns_common *new_ns)
 {
 	return 0;
 }
@@ -537,7 +537,7 @@ static inline void sysfs_remove_mount_point(struct kobject *parent_kobj,
 
 static inline int sysfs_create_file_ns(struct kobject *kobj,
 				       const struct attribute *attr,
-				       const void *ns)
+				       const struct ns_common *ns)
 {
 	return 0;
 }
@@ -567,7 +567,7 @@ static inline void sysfs_unbreak_active_protection(struct kernfs_node *kn)
 
 static inline void sysfs_remove_file_ns(struct kobject *kobj,
 					const struct attribute *attr,
-					const void *ns)
+					const struct ns_common *ns)
 {
 }
 
@@ -612,7 +612,7 @@ static inline void sysfs_remove_link(struct kobject *kobj, const char *name)
 
 static inline int sysfs_rename_link_ns(struct kobject *k, struct kobject *t,
 				       const char *old_name,
-				       const char *new_name, const void *ns)
+				       const char *new_name, const struct ns_common *ns)
 {
 	return 0;
 }