4 files changed, 201 insertions, 6 deletions

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
index 8f8c4f205166..340945857d23 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
@@ -66,8 +66,8 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 			    struct rmnet_port *port)
 {
 	struct rmnet_endpoint *ep;
+	u16 len, pad;
 	u8 mux_id;
-	u16 len;
 
 	if (RMNET_MAP_GET_CD_BIT(skb)) {
 		if (port->data_format & RMNET_INGRESS_FORMAT_MAP_COMMANDS)
@@ -77,7 +77,8 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 	}
 
 	mux_id = RMNET_MAP_GET_MUX_ID(skb);
-	len = RMNET_MAP_GET_LENGTH(skb) - RMNET_MAP_GET_PAD(skb);
+	pad = RMNET_MAP_GET_PAD(skb);
+	len = RMNET_MAP_GET_LENGTH(skb) - pad;
 
 	if (mux_id >= RMNET_MAX_LOGICAL_EP)
 		goto free_skb;
@@ -90,8 +91,14 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 
 	/* Subtract MAP header */
 	skb_pull(skb, sizeof(struct rmnet_map_header));
-	skb_trim(skb, len);
 	rmnet_set_skb_proto(skb);
+
+	if (port->data_format & RMNET_INGRESS_FORMAT_MAP_CKSUMV4) {
+		if (!rmnet_map_checksum_downlink_packet(skb, len + pad))
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
+	}
+
+	skb_trim(skb, len);
 	rmnet_deliver_skb(skb);
 	return;
 
@@ -115,7 +122,7 @@ rmnet_map_ingress_handler(struct sk_buff *skb,
 	}
 
 	if (port->data_format & RMNET_INGRESS_FORMAT_DEAGGREGATION) {
-		while ((skbn = rmnet_map_deaggregate(skb)) != NULL)
+		while ((skbn = rmnet_map_deaggregate(skb, port)) != NULL)
 			__rmnet_map_ingress_handler(skbn, port);
 
 		consume_skb(skb);
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
index 50c50cdc3e22..ca9f4731f53c 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
@@ -83,9 +83,11 @@ struct rmnet_map_ul_csum_header {
 #define RMNET_MAP_NO_PAD_BYTES        0
 #define RMNET_MAP_ADD_PAD_BYTES       1
 
-struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb);
+struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
+				      struct rmnet_port *port);
 struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb,
 						  int hdrlen, int pad);
 void rmnet_map_command(struct sk_buff *skb, struct rmnet_port *port);
+int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len);
 
 #endif /* _RMNET_MAP_H_ */
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 978ce2679b23..881c1dc9d7ae 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -14,6 +14,9 @@
  */
 
 #include <linux/netdevice.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <net/ip6_checksum.h>
 #include "rmnet_config.h"
 #include "rmnet_map.h"
 #include "rmnet_private.h"
@@ -21,6 +24,153 @@
 #define RMNET_MAP_DEAGGR_SPACING  64
 #define RMNET_MAP_DEAGGR_HEADROOM (RMNET_MAP_DEAGGR_SPACING / 2)
 
+static __sum16 *rmnet_map_get_csum_field(unsigned char protocol,
+					 const void *txporthdr)
+{
+	__sum16 *check = NULL;
+
+	switch (protocol) {
+	case IPPROTO_TCP:
+		check = &(((struct tcphdr *)txporthdr)->check);
+		break;
+
+	case IPPROTO_UDP:
+		check = &(((struct udphdr *)txporthdr)->check);
+		break;
+
+	default:
+		check = NULL;
+		break;
+	}
+
+	return check;
+}
+
+static int
+rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
+			       struct rmnet_map_dl_csum_trailer *csum_trailer)
+{
+	__sum16 *csum_field, csum_temp, pseudo_csum, hdr_csum, ip_payload_csum;
+	u16 csum_value, csum_value_final;
+	struct iphdr *ip4h;
+	void *txporthdr;
+	__be16 addend;
+
+	ip4h = (struct iphdr *)(skb->data);
+	if ((ntohs(ip4h->frag_off) & IP_MF) ||
+	    ((ntohs(ip4h->frag_off) & IP_OFFSET) > 0))
+		return -EOPNOTSUPP;
+
+	txporthdr = skb->data + ip4h->ihl * 4;
+
+	csum_field = rmnet_map_get_csum_field(ip4h->protocol, txporthdr);
+
+	if (!csum_field)
+		return -EPROTONOSUPPORT;
+
+	/* RFC 768 - Skip IPv4 UDP packets where sender checksum field is 0 */
+	if (*csum_field == 0 && ip4h->protocol == IPPROTO_UDP)
+		return 0;
+
+	csum_value = ~ntohs(csum_trailer->csum_value);
+	hdr_csum = ~ip_fast_csum(ip4h, (int)ip4h->ihl);
+	ip_payload_csum = csum16_sub((__force __sum16)csum_value,
+				     (__force __be16)hdr_csum);
+
+	pseudo_csum = ~csum_tcpudp_magic(ip4h->saddr, ip4h->daddr,
+					 ntohs(ip4h->tot_len) - ip4h->ihl * 4,
+					 ip4h->protocol, 0);
+	addend = (__force __be16)ntohs((__force __be16)pseudo_csum);
+	pseudo_csum = csum16_add(ip_payload_csum, addend);
+
+	addend = (__force __be16)ntohs((__force __be16)*csum_field);
+	csum_temp = ~csum16_sub(pseudo_csum, addend);
+	csum_value_final = (__force u16)csum_temp;
+
+	if (unlikely(csum_value_final == 0)) {
+		switch (ip4h->protocol) {
+		case IPPROTO_UDP:
+			/* RFC 768 - DL4 1's complement rule for UDP csum 0 */
+			csum_value_final = ~csum_value_final;
+			break;
+
+		case IPPROTO_TCP:
+			/* DL4 Non-RFC compliant TCP checksum found */
+			if (*csum_field == (__force __sum16)0xFFFF)
+				csum_value_final = ~csum_value_final;
+			break;
+		}
+	}
+
+	if (csum_value_final == ntohs((__force __be16)*csum_field))
+		return 0;
+	else
+		return -EINVAL;
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static int
+rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
+			       struct rmnet_map_dl_csum_trailer *csum_trailer)
+{
+	__sum16 *csum_field, ip6_payload_csum, pseudo_csum, csum_temp;
+	u16 csum_value, csum_value_final;
+	__be16 ip6_hdr_csum, addend;
+	struct ipv6hdr *ip6h;
+	void *txporthdr;
+	u32 length;
+
+	ip6h = (struct ipv6hdr *)(skb->data);
+
+	txporthdr = skb->data + sizeof(struct ipv6hdr);
+	csum_field = rmnet_map_get_csum_field(ip6h->nexthdr, txporthdr);
+
+	if (!csum_field)
+		return -EPROTONOSUPPORT;
+
+	csum_value = ~ntohs(csum_trailer->csum_value);
+	ip6_hdr_csum = (__force __be16)
+			~ntohs((__force __be16)ip_compute_csum(ip6h,
+			       (int)(txporthdr - (void *)(skb->data))));
+	ip6_payload_csum = csum16_sub((__force __sum16)csum_value,
+				      ip6_hdr_csum);
+
+	length = (ip6h->nexthdr == IPPROTO_UDP) ?
+		 ntohs(((struct udphdr *)txporthdr)->len) :
+		 ntohs(ip6h->payload_len);
+	pseudo_csum = ~(csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
+			     length, ip6h->nexthdr, 0));
+	addend = (__force __be16)ntohs((__force __be16)pseudo_csum);
+	pseudo_csum = csum16_add(ip6_payload_csum, addend);
+
+	addend = (__force __be16)ntohs((__force __be16)*csum_field);
+	csum_temp = ~csum16_sub(pseudo_csum, addend);
+	csum_value_final = (__force u16)csum_temp;
+
+	if (unlikely(csum_value_final == 0)) {
+		switch (ip6h->nexthdr) {
+		case IPPROTO_UDP:
+			/* RFC 2460 section 8.1
+			 * DL6 One's complement rule for UDP checksum 0
+			 */
+			csum_value_final = ~csum_value_final;
+			break;
+
+		case IPPROTO_TCP:
+			/* DL6 Non-RFC compliant TCP checksum found */
+			if (*csum_field == (__force __sum16)0xFFFF)
+				csum_value_final = ~csum_value_final;
+			break;
+		}
+	}
+
+	if (csum_value_final == ntohs((__force __be16)*csum_field))
+		return 0;
+	else
+		return -EINVAL;
+}
+#endif
+
 /* Adds MAP header to front of skb->data
  * Padding is calculated and set appropriately in MAP header. Mux ID is
  * initialized to 0.
@@ -66,7 +216,8 @@ done:
  * returned, indicating that there are no more packets to deaggregate. Caller
  * is responsible for freeing the original skb.
  */
-struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb)
+struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb,
+				      struct rmnet_port *port)
 {
 	struct rmnet_map_header *maph;
 	struct sk_buff *skbn;
@@ -78,6 +229,9 @@ struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb)
 	maph = (struct rmnet_map_header *)skb->data;
 	packet_len = ntohs(maph->pkt_len) + sizeof(struct rmnet_map_header);
 
+	if (port->data_format & RMNET_INGRESS_FORMAT_MAP_CKSUMV4)
+		packet_len += sizeof(struct rmnet_map_dl_csum_trailer);
+
 	if (((int)skb->len - (int)packet_len) < 0)
 		return NULL;
 
@@ -97,3 +251,33 @@ struct sk_buff *rmnet_map_deaggregate(struct sk_buff *skb)
 
 	return skbn;
 }
+
+/* Validates packet checksums. Function takes a pointer to
+ * the beginning of a buffer which contains the IP payload +
+ * padding + checksum trailer.
+ * Only IPv4 and IPv6 are supported along with TCP & UDP.
+ * Fragmented or tunneled packets are not supported.
+ */
+int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
+{
+	struct rmnet_map_dl_csum_trailer *csum_trailer;
+
+	if (unlikely(!(skb->dev->features & NETIF_F_RXCSUM)))
+		return -EOPNOTSUPP;
+
+	csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len);
+
+	if (!csum_trailer->valid)
+		return -EINVAL;
+
+	if (skb->protocol == htons(ETH_P_IP))
+		return rmnet_map_ipv4_dl_csum_trailer(skb, csum_trailer);
+	else if (skb->protocol == htons(ETH_P_IPV6))
+#if IS_ENABLED(CONFIG_IPV6)
+		return rmnet_map_ipv6_dl_csum_trailer(skb, csum_trailer);
+#else
+		return -EPROTONOSUPPORT;
+#endif
+
+	return 0;
+}
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c
index 5bb29f44d114..879a2e01acdb 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c
@@ -188,6 +188,8 @@ int rmnet_vnd_newlink(u8 id, struct net_device *rmnet_dev,
 	if (rmnet_get_endpoint(port, id))
 		return -EBUSY;
 
+	rmnet_dev->hw_features = NETIF_F_RXCSUM;
+
 	rc = register_netdevice(rmnet_dev);
 	if (!rc) {
 		ep->egress_dev = rmnet_dev;