xfrm: Provide API to register translator module
Add a skeleton for xfrm_compat module and provide API to register it in
xfrm_state.ko. struct xfrm_translator will have function pointers to
translate messages received from 32-bit userspace or to be sent to it
from 64-bit kernel.
module_get()/module_put() are used instead of rcu_read_lock() as the
module will vmalloc() memory for translation.
The new API is registered with xfrm_state module, not with xfrm_user as
the former needs translator for user_policy set by setsockopt() and
xfrm_user already uses functions from xfrm_state.
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 69520ad..cc206ca 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2264,6 +2264,66 @@ static bool km_is_alive(const struct km_event *c)
return is_alive;
}
+#if IS_ENABLED(CONFIG_XFRM_USER_COMPAT)
+static DEFINE_SPINLOCK(xfrm_translator_lock);
+static struct xfrm_translator __rcu *xfrm_translator;
+
+struct xfrm_translator *xfrm_get_translator(void)
+{
+ struct xfrm_translator *xtr;
+
+ rcu_read_lock();
+ xtr = rcu_dereference(xfrm_translator);
+ if (unlikely(!xtr))
+ goto out;
+ if (!try_module_get(xtr->owner))
+ xtr = NULL;
+out:
+ rcu_read_unlock();
+ return xtr;
+}
+EXPORT_SYMBOL_GPL(xfrm_get_translator);
+
+void xfrm_put_translator(struct xfrm_translator *xtr)
+{
+ module_put(xtr->owner);
+}
+EXPORT_SYMBOL_GPL(xfrm_put_translator);
+
+int xfrm_register_translator(struct xfrm_translator *xtr)
+{
+ int err = 0;
+
+ spin_lock_bh(&xfrm_translator_lock);
+ if (unlikely(xfrm_translator != NULL))
+ err = -EEXIST;
+ else
+ rcu_assign_pointer(xfrm_translator, xtr);
+ spin_unlock_bh(&xfrm_translator_lock);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(xfrm_register_translator);
+
+int xfrm_unregister_translator(struct xfrm_translator *xtr)
+{
+ int err = 0;
+
+ spin_lock_bh(&xfrm_translator_lock);
+ if (likely(xfrm_translator != NULL)) {
+ if (rcu_access_pointer(xfrm_translator) != xtr)
+ err = -EINVAL;
+ else
+ RCU_INIT_POINTER(xfrm_translator, NULL);
+ }
+ spin_unlock_bh(&xfrm_translator_lock);
+ synchronize_rcu();
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(xfrm_unregister_translator);
+#endif
+
int xfrm_user_policy(struct sock *sk, int optname, sockptr_t optval, int optlen)
{
int err;
