net: ethernet: rmnet: Support for ingress MAPv5 checksum offload

Adding support for processing of MAPv5 downlink packets.
It involves parsing the Mapv5 packet and checking the csum header
to know whether the hardware has validated the checksum and is
valid or not.

Based on the checksum valid bit the corresponding stats are
incremented and skb->ip_summed is marked either CHECKSUM_UNNECESSARY
or left as CHEKSUM_NONE to let network stack revalidate the checksum
and update the respective snmp stats.

Current MAPV1 header has been modified, the reserved field in the
Mapv1 header is now used for next header indication.

Signed-off-by: Sharath Chandra Vurukala <sharathv@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 55 insertions, 2 deletions

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 0ac2ff828320..5c018bd64689 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
-/* Copyright (c) 2013-2018, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2013-2018, 2021, The Linux Foundation. All rights reserved.
  *
  * RMNET Data MAP protocol
  */
@@ -8,6 +8,7 @@
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <net/ip6_checksum.h>
+#include <linux/bitfield.h>
 #include "rmnet_config.h"
 #include "rmnet_map.h"
 #include "rmnet_private.h"
@@ -300,8 +301,11 @@ done:
 struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
 				      struct rmnet_port *port)
 {
+	struct rmnet_map_v5_csum_header *next_hdr = NULL;
 	struct rmnet_map_header *maph;
+	void *data = skb->data;
 	struct sk_buff *skbn;
+	u8 nexthdr_type;
 	u32 packet_len;
 
 	if (skb->len == 0)
@@ -310,8 +314,18 @@ struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
 	maph = (struct rmnet_map_header *)skb->data;
 	packet_len = ntohs(maph->pkt_len) + sizeof(*maph);
 
-	if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4)
+	if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV4) {
 		packet_len += sizeof(struct rmnet_map_dl_csum_trailer);
+	} else if (port->data_format & RMNET_FLAGS_INGRESS_MAP_CKSUMV5) {
+		if (!(maph->flags & MAP_CMD_FLAG)) {
+			packet_len += sizeof(*next_hdr);
+			if (maph->flags & MAP_NEXT_HEADER_FLAG)
+				next_hdr = data + sizeof(*maph);
+			else
+				/* Mapv5 data pkt without csum hdr is invalid */
+				return NULL;
+		}
+	}
 
 	if (((int)skb->len - (int)packet_len) < 0)
 		return NULL;
@@ -320,6 +334,13 @@ struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
 	if (!maph->pkt_len)
 		return NULL;
 
+	if (next_hdr) {
+		nexthdr_type = u8_get_bits(next_hdr->header_info,
+					   MAPV5_HDRINFO_HDR_TYPE_FMASK);
+		if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
+			return NULL;
+	}
+
 	skbn = alloc_skb(packet_len + RMNET_MAP_DEAGGR_SPACING, GFP_ATOMIC);
 	if (!skbn)
 		return NULL;
@@ -414,3 +435,35 @@ sw_csum:
 
 	priv->stats.csum_sw++;
 }
+
+/* Process a MAPv5 packet header */
+int rmnet_map_process_next_hdr_packet(struct sk_buff *skb,
+				      u16 len)
+{
+	struct rmnet_priv *priv = netdev_priv(skb->dev);
+	struct rmnet_map_v5_csum_header *next_hdr;
+	u8 nexthdr_type;
+
+	next_hdr = (struct rmnet_map_v5_csum_header *)(skb->data +
+			sizeof(struct rmnet_map_header));
+
+	nexthdr_type = u8_get_bits(next_hdr->header_info,
+				   MAPV5_HDRINFO_HDR_TYPE_FMASK);
+
+	if (nexthdr_type != RMNET_MAP_HEADER_TYPE_CSUM_OFFLOAD)
+		return -EINVAL;
+
+	if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM))) {
+		priv->stats.csum_sw++;
+	} else if (next_hdr->csum_info & MAPV5_CSUMINFO_VALID_FLAG) {
+		priv->stats.csum_ok++;
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+	} else {
+		priv->stats.csum_valid_unset++;
+	}
+
+	/* Pull csum v5 header */
+	skb_pull(skb, sizeof(*next_hdr));
+
+	return 0;
+}