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

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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>
This commit is contained in:
Christian Brauner
2026-04-01 12:15:58 +02:00
parent 07712db808
commit e3b2cf6e5d
30 changed files with 175 additions and 148 deletions
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13
lib/kobject_uevent.c
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@@ -238,7 +238,7 @@ static int kobj_usermode_filter(struct kobject *kobj)
ops = kobj_ns_ops(kobj);
if (ops) {
const void *init_ns, *ns;
const struct ns_common *init_ns, *ns;
ns = kobj->ktype->namespace(kobj);
init_ns = ops->initial_ns();
@@ -388,7 +388,7 @@ static int kobject_uevent_net_broadcast(struct kobject *kobj,
#ifdef CONFIG_NET
const struct kobj_ns_type_operations *ops;
const struct net *net = NULL;
const struct ns_common *ns = NULL;
ops = kobj_ns_ops(kobj);
if (!ops && kobj->kset) {
@@ -404,14 +404,17 @@ static int kobject_uevent_net_broadcast(struct kobject *kobj,
*/
if (ops && ops->netlink_ns && kobj->ktype->namespace)
if (ops->type == KOBJ_NS_TYPE_NET)
net = kobj->ktype->namespace(kobj);
ns = kobj->ktype->namespace(kobj);
if (!net)
if (!ns)
ret = uevent_net_broadcast_untagged(env, action_string,
devpath);
else
else {
const struct net *net = container_of(ns, struct net, ns);
ret = uevent_net_broadcast_tagged(net->uevent_sock->sk, env,
action_string, devpath);
}
#endif
return ret;