net/tls: add helper for testing if socket is RX offloaded

There is currently no way for driver to reliably check that
the socket it has looked up is in fact RX offloaded. Add
a helper. This allows drivers to catch misbehaving firmware.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tls.h

@@ -641,6 +641,7 @@ int tls_sw_fallback_init(struct sock *sk,
 #ifdef CONFIG_TLS_DEVICE
 void tls_device_init(void);
 void tls_device_cleanup(void);
+void tls_device_sk_destruct(struct sock *sk);
 int tls_set_device_offload(struct sock *sk, struct tls_context *ctx);
 void tls_device_free_resources_tx(struct sock *sk);
 int tls_set_device_offload_rx(struct sock *sk, struct tls_context *ctx);
@@ -649,6 +650,14 @@ void tls_device_rx_resync_new_rec(struct sock *sk, u32 rcd_len, u32 seq);
 void tls_offload_tx_resync_request(struct sock *sk, u32 got_seq, u32 exp_seq);
 int tls_device_decrypted(struct sock *sk, struct tls_context *tls_ctx,
 			 struct sk_buff *skb, struct strp_msg *rxm);
+
+static inline bool tls_is_sk_rx_device_offloaded(struct sock *sk)
+{
+	if (!sk_fullsock(sk) ||
+	    smp_load_acquire(&sk->sk_destruct) != tls_device_sk_destruct)
+		return false;
+	return tls_get_ctx(sk)->rx_conf == TLS_HW;
+}
 #else
 static inline void tls_device_init(void) {}
 static inline void tls_device_cleanup(void) {}

net/tls/tls_device.c

@@ -178,7 +178,7 @@ static void tls_icsk_clean_acked(struct sock *sk, u32 acked_seq)
  * socket and no in-flight SKBs associated with this
  * socket, so it is safe to free all the resources.
  */
-static void tls_device_sk_destruct(struct sock *sk)
+void tls_device_sk_destruct(struct sock *sk)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
@@ -196,6 +196,7 @@ static void tls_device_sk_destruct(struct sock *sk)
 	if (refcount_dec_and_test(&tls_ctx->refcount))
 		tls_device_queue_ctx_destruction(tls_ctx);
 }
+EXPORT_SYMBOL_GPL(tls_device_sk_destruct);
 
 void tls_device_free_resources_tx(struct sock *sk)
 {
@@ -903,7 +904,7 @@ static void tls_device_attach(struct tls_context *ctx, struct sock *sk,
 		spin_unlock_irq(&tls_device_lock);
 
 		ctx->sk_destruct = sk->sk_destruct;
-		sk->sk_destruct = tls_device_sk_destruct;
+		smp_store_release(&sk->sk_destruct, tls_device_sk_destruct);
 	}
 }