tls: replace poll implementation with read hook

Instead of re-implementing poll routine use the poll callback to
trigger read from kTLS, we reuse the stream_memory_read callback
which is simpler and achieves the same. This helps to align sockmap
and kTLS so we can more easily embed BPF in kTLS.

Joint work with Daniel.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/net/tls.h

@@ -142,8 +142,7 @@ struct tls_sw_context_rx {
 
 	struct strparser strp;
 	void (*saved_data_ready)(struct sock *sk);
-	unsigned int (*sk_poll)(struct file *file, struct socket *sock,
-				struct poll_table_struct *wait);
+
 	struct sk_buff *recv_pkt;
 	u8 control;
 	bool decrypted;
@@ -272,8 +271,7 @@ void tls_sw_free_resources_rx(struct sock *sk);
 void tls_sw_release_resources_rx(struct sock *sk);
 int tls_sw_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 		   int nonblock, int flags, int *addr_len);
-unsigned int tls_sw_poll(struct file *file, struct socket *sock,
-			 struct poll_table_struct *wait);
+bool tls_sw_stream_read(const struct sock *sk);
 ssize_t tls_sw_splice_read(struct socket *sock, loff_t *ppos,
 			   struct pipe_inode_info *pipe,
 			   size_t len, unsigned int flags);

net/tls/tls_main.c

@@ -620,12 +620,14 @@ static void build_protos(struct proto prot[TLS_NUM_CONFIG][TLS_NUM_CONFIG],
 	prot[TLS_SW][TLS_BASE].sendpage		= tls_sw_sendpage;
 
 	prot[TLS_BASE][TLS_SW] = prot[TLS_BASE][TLS_BASE];
-	prot[TLS_BASE][TLS_SW].recvmsg		= tls_sw_recvmsg;
-	prot[TLS_BASE][TLS_SW].close		= tls_sk_proto_close;
+	prot[TLS_BASE][TLS_SW].recvmsg		  = tls_sw_recvmsg;
+	prot[TLS_BASE][TLS_SW].stream_memory_read = tls_sw_stream_read;
+	prot[TLS_BASE][TLS_SW].close		  = tls_sk_proto_close;
 
 	prot[TLS_SW][TLS_SW] = prot[TLS_SW][TLS_BASE];
-	prot[TLS_SW][TLS_SW].recvmsg	= tls_sw_recvmsg;
-	prot[TLS_SW][TLS_SW].close	= tls_sk_proto_close;
+	prot[TLS_SW][TLS_SW].recvmsg		= tls_sw_recvmsg;
+	prot[TLS_SW][TLS_SW].stream_memory_read	= tls_sw_stream_read;
+	prot[TLS_SW][TLS_SW].close		= tls_sk_proto_close;
 
 #ifdef CONFIG_TLS_DEVICE
 	prot[TLS_HW][TLS_BASE] = prot[TLS_BASE][TLS_BASE];
@@ -724,7 +726,6 @@ static int __init tls_register(void)
 	build_protos(tls_prots[TLSV4], &tcp_prot);
 
 	tls_sw_proto_ops = inet_stream_ops;
-	tls_sw_proto_ops.poll = tls_sw_poll;
 	tls_sw_proto_ops.splice_read = tls_sw_splice_read;
 
 #ifdef CONFIG_TLS_DEVICE

net/tls/tls_sw.c

@@ -1352,23 +1352,15 @@ ssize_t tls_sw_splice_read(struct socket *sock,  loff_t *ppos,
 	return copied ? : err;
 }
 
-unsigned int tls_sw_poll(struct file *file, struct socket *sock,
-			 struct poll_table_struct *wait)
+bool tls_sw_stream_read(const struct sock *sk)
 {
-	unsigned int ret;
-	struct sock *sk = sock->sk;
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
 
-	/* Grab POLLOUT and POLLHUP from the underlying socket */
-	ret = ctx->sk_poll(file, sock, wait);
-
-	/* Clear POLLIN bits, and set based on recv_pkt */
-	ret &= ~(POLLIN | POLLRDNORM);
 	if (ctx->recv_pkt)
-		ret |= POLLIN | POLLRDNORM;
+		return true;
 
-	return ret;
+	return false;
 }
 
 static int tls_read_size(struct strparser *strp, struct sk_buff *skb)
@@ -1686,8 +1678,6 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
 		sk->sk_data_ready = tls_data_ready;
 		write_unlock_bh(&sk->sk_callback_lock);
 
-		sw_ctx_rx->sk_poll = sk->sk_socket->ops->poll;
-
 		strp_check_rcv(&sw_ctx_rx->strp);
 	}