net/tls: simplify driver context retrieval

Currently drivers have to ensure the alignment of their tls state
structure, which leads to unnecessary layers of getters and
encapsulated structures in each driver.

Simplify all this by marking the driver state as aligned (driver_state
members are currently aligned, so no hole is added, besides ALIGN in
TLS_OFFLOAD_CONTEXT_SIZE_RX/TX would reserve this extra space, anyway.)
With that we can add a common accessor to the core.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tls.h

@@ -40,6 +40,7 @@
 #include <linux/socket.h>
 #include <linux/tcp.h>
 #include <linux/skmsg.h>
+#include <linux/netdevice.h>
 
 #include <net/tcp.h>
 #include <net/strparser.h>
@@ -197,7 +198,7 @@ struct tls_offload_context_tx {
 
 	struct scatterlist sg_tx_data[MAX_SKB_FRAGS];
 	void (*sk_destruct)(struct sock *sk);
-	u8 driver_state[];
+	u8 driver_state[] __aligned(8);
 	/* The TLS layer reserves room for driver specific state
 	 * Currently the belief is that there is not enough
 	 * driver specific state to justify another layer of indirection
@@ -206,8 +207,7 @@ struct tls_offload_context_tx {
 };
 
 #define TLS_OFFLOAD_CONTEXT_SIZE_TX                                            \
-	(ALIGN(sizeof(struct tls_offload_context_tx), sizeof(void *)) +        \
-	 TLS_DRIVER_STATE_SIZE_TX)
+	(sizeof(struct tls_offload_context_tx) + TLS_DRIVER_STATE_SIZE_TX)
 
 struct cipher_context {
 	char *iv;
@@ -302,7 +302,7 @@ struct tls_offload_context_rx {
 	/* sw must be the first member of tls_offload_context_rx */
 	struct tls_sw_context_rx sw;
 	atomic64_t resync_req;
-	u8 driver_state[];
+	u8 driver_state[] __aligned(8);
 	/* The TLS layer reserves room for driver specific state
 	 * Currently the belief is that there is not enough
 	 * driver specific state to justify another layer of indirection
@@ -311,8 +311,7 @@ struct tls_offload_context_rx {
 };
 
 #define TLS_OFFLOAD_CONTEXT_SIZE_RX					\
-	(ALIGN(sizeof(struct tls_offload_context_rx), sizeof(void *)) + \
-	 TLS_DRIVER_STATE_SIZE_RX)
+	(sizeof(struct tls_offload_context_rx) + TLS_DRIVER_STATE_SIZE_RX)
 
 int wait_on_pending_writer(struct sock *sk, long *timeo);
 int tls_sk_query(struct sock *sk, int optname, char __user *optval,
@@ -557,6 +556,23 @@ tls_offload_ctx_rx(const struct tls_context *tls_ctx)
 	return (struct tls_offload_context_rx *)tls_ctx->priv_ctx_rx;
 }
 
+#if IS_ENABLED(CONFIG_TLS_DEVICE)
+static inline void *__tls_driver_ctx(struct tls_context *tls_ctx,
+				     enum tls_offload_ctx_dir direction)
+{
+	if (direction == TLS_OFFLOAD_CTX_DIR_TX)
+		return tls_offload_ctx_tx(tls_ctx)->driver_state;
+	else
+		return tls_offload_ctx_rx(tls_ctx)->driver_state;
+}
+
+static inline void *
+tls_driver_ctx(const struct sock *sk, enum tls_offload_ctx_dir direction)
+{
+	return __tls_driver_ctx(tls_get_ctx(sk), direction);
+}
+#endif
+
 /* The TLS context is valid until sk_destruct is called */
 static inline void tls_offload_rx_resync_request(struct sock *sk, __be32 seq)
 {