net/tls: Add asynchronous resync

This patch adds support for asynchronous resynchronization in tls_device.
Async resync follows two distinct stages:

1. The NIC driver indicates that it would like to resync on some TLS
record within the received packet (P), but the driver does not
know (yet) which of the TLS records within the packet.
At this stage, the NIC driver will query the device to find the exact
TCP sequence for resync (tcpsn), however, the driver does not wait
for the device to provide the response.

2. Eventually, the device responds, and the driver provides the tcpsn
within the resync packet to KTLS. Now, KTLS can check the tcpsn against
any processed TLS records within packet P, and also against any record
that is processed in the future within packet P.

The asynchronous resync path simplifies the device driver, as it can
save bits on the packet completion (32-bit TCP sequence), and pass this
information on an asynchronous command instead.

Signed-off-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index a562ebaaa33c..18fa6067bb7f 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -690,6 +690,47 @@ static void tls_device_resync_rx(struct tls_context *tls_ctx,
 	TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXDEVICERESYNC);
 }
 
+static bool
+tls_device_rx_resync_async(struct tls_offload_resync_async *resync_async,
+			   s64 resync_req, u32 *seq)
+{
+	u32 is_async = resync_req & RESYNC_REQ_ASYNC;
+	u32 req_seq = resync_req >> 32;
+	u32 req_end = req_seq + ((resync_req >> 16) & 0xffff);
+
+	if (is_async) {
+		/* asynchronous stage: log all headers seq such that
+		 * req_seq <= seq <= end_seq, and wait for real resync request
+		 */
+		if (between(*seq, req_seq, req_end) &&
+		    resync_async->loglen < TLS_DEVICE_RESYNC_ASYNC_LOGMAX)
+			resync_async->log[resync_async->loglen++] = *seq;
+
+		return false;
+	}
+
+	/* synchronous stage: check against the logged entries and
+	 * proceed to check the next entries if no match was found
+	 */
+	while (resync_async->loglen) {
+		if (req_seq == resync_async->log[resync_async->loglen - 1] &&
+		    atomic64_try_cmpxchg(&resync_async->req,
+					 &resync_req, 0)) {
+			resync_async->loglen = 0;
+			*seq = req_seq;
+			return true;
+		}
+		resync_async->loglen--;
+	}
+
+	if (req_seq == *seq &&
+	    atomic64_try_cmpxchg(&resync_async->req,
+				 &resync_req, 0))
+		return true;
+
+	return false;
+}
+
 void tls_device_rx_resync_new_rec(struct sock *sk, u32 rcd_len, u32 seq)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
@@ -736,6 +777,16 @@ void tls_device_rx_resync_new_rec(struct sock *sk, u32 rcd_len, u32 seq)
 		seq += rcd_len;
 		tls_bigint_increment(rcd_sn, prot->rec_seq_size);
 		break;
+	case TLS_OFFLOAD_SYNC_TYPE_DRIVER_REQ_ASYNC:
+		resync_req = atomic64_read(&rx_ctx->resync_async->req);
+		is_req_pending = resync_req;
+		if (likely(!is_req_pending))
+			return;
+
+		if (!tls_device_rx_resync_async(rx_ctx->resync_async,
+						resync_req, &seq))
+			return;
+		break;
 	}
 
 	tls_device_resync_rx(tls_ctx, sk, seq, rcd_sn);