net: libwx: fix Tx descriptor content for some tunnel packets

The length of skb header was incorrectly calculated when transmit a tunnel
packet with outer IPv6 extension header, or a IP over IP packet which has
inner IPv6 header. Thus the correct Tx context descriptor cannot be
composed, resulting in Tx ring hang.

Fixes: 3403960 ("net: wangxun: libwx add tx offload functions")
Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Link: https://patch.msgid.link/20250324103235.823096-1-jiawenwu@trustnetic.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Jiawen Wu

drivers/net/ethernet/wangxun/libwx/wx_lib.c

@@ -1082,26 +1082,6 @@ static void wx_tx_ctxtdesc(struct wx_ring *tx_ring, u32 vlan_macip_lens,
 	context_desc->mss_l4len_idx     = cpu_to_le32(mss_l4len_idx);
 }
 
-static void wx_get_ipv6_proto(struct sk_buff *skb, int offset, u8 *nexthdr)
-{
-	struct ipv6hdr *hdr = (struct ipv6hdr *)(skb->data + offset);
-
-	*nexthdr = hdr->nexthdr;
-	offset += sizeof(struct ipv6hdr);
-	while (ipv6_ext_hdr(*nexthdr)) {
-		struct ipv6_opt_hdr _hdr, *hp;
-
-		if (*nexthdr == NEXTHDR_NONE)
-			return;
-		hp = skb_header_pointer(skb, offset, sizeof(_hdr), &_hdr);
-		if (!hp)
-			return;
-		if (*nexthdr == NEXTHDR_FRAGMENT)
-			break;
-		*nexthdr = hp->nexthdr;
-	}
-}
-
 union network_header {
 	struct iphdr *ipv4;
 	struct ipv6hdr *ipv6;
@@ -1112,6 +1092,8 @@ static u8 wx_encode_tx_desc_ptype(const struct wx_tx_buffer *first)
 {
 	u8 tun_prot = 0, l4_prot = 0, ptype = 0;
 	struct sk_buff *skb = first->skb;
+	unsigned char *exthdr, *l4_hdr;
+	__be16 frag_off;
 
 	if (skb->encapsulation) {
 		union network_header hdr;
@@ -1122,14 +1104,18 @@ static u8 wx_encode_tx_desc_ptype(const struct wx_tx_buffer *first)
 			ptype = WX_PTYPE_TUN_IPV4;
 			break;
 		case htons(ETH_P_IPV6):
-			wx_get_ipv6_proto(skb, skb_network_offset(skb), &tun_prot);
+			l4_hdr = skb_transport_header(skb);
+			exthdr = skb_network_header(skb) + sizeof(struct ipv6hdr);
+			tun_prot = ipv6_hdr(skb)->nexthdr;
+			if (l4_hdr != exthdr)
+				ipv6_skip_exthdr(skb, exthdr - skb->data, &tun_prot, &frag_off);
 			ptype = WX_PTYPE_TUN_IPV6;
 			break;
 		default:
 			return ptype;
 		}
 
-		if (tun_prot == IPPROTO_IPIP) {
+		if (tun_prot == IPPROTO_IPIP || tun_prot == IPPROTO_IPV6) {
 			hdr.raw = (void *)inner_ip_hdr(skb);
 			ptype |= WX_PTYPE_PKT_IPIP;
 		} else if (tun_prot == IPPROTO_UDP) {
@@ -1166,7 +1152,11 @@ static u8 wx_encode_tx_desc_ptype(const struct wx_tx_buffer *first)
 			l4_prot = hdr.ipv4->protocol;
 			break;
 		case 6:
-			wx_get_ipv6_proto(skb, skb_inner_network_offset(skb), &l4_prot);
+			l4_hdr = skb_inner_transport_header(skb);
+			exthdr = skb_inner_network_header(skb) + sizeof(struct ipv6hdr);
+			l4_prot = inner_ipv6_hdr(skb)->nexthdr;
+			if (l4_hdr != exthdr)
+				ipv6_skip_exthdr(skb, exthdr - skb->data, &l4_prot, &frag_off);
 			ptype |= WX_PTYPE_PKT_IPV6;
 			break;
 		default:
@@ -1179,7 +1169,11 @@ static u8 wx_encode_tx_desc_ptype(const struct wx_tx_buffer *first)
 			ptype = WX_PTYPE_PKT_IP;
 			break;
 		case htons(ETH_P_IPV6):
-			wx_get_ipv6_proto(skb, skb_network_offset(skb), &l4_prot);
+			l4_hdr = skb_transport_header(skb);
+			exthdr = skb_network_header(skb) + sizeof(struct ipv6hdr);
+			l4_prot = ipv6_hdr(skb)->nexthdr;
+			if (l4_hdr != exthdr)
+				ipv6_skip_exthdr(skb, exthdr - skb->data, &l4_prot, &frag_off);
 			ptype = WX_PTYPE_PKT_IP | WX_PTYPE_PKT_IPV6;
 			break;
 		default:
@@ -1269,13 +1263,20 @@ static int wx_tso(struct wx_ring *tx_ring, struct wx_tx_buffer *first,
 
 	/* vlan_macip_lens: HEADLEN, MACLEN, VLAN tag */
 	if (enc) {
+		unsigned char *exthdr, *l4_hdr;
+		__be16 frag_off;
+
 		switch (first->protocol) {
 		case htons(ETH_P_IP):
 			tun_prot = ip_hdr(skb)->protocol;
 			first->tx_flags |= WX_TX_FLAGS_OUTER_IPV4;
 			break;
 		case htons(ETH_P_IPV6):
+			l4_hdr = skb_transport_header(skb);
+			exthdr = skb_network_header(skb) + sizeof(struct ipv6hdr);
 			tun_prot = ipv6_hdr(skb)->nexthdr;
+			if (l4_hdr != exthdr)
+				ipv6_skip_exthdr(skb, exthdr - skb->data, &tun_prot, &frag_off);
 			break;
 		default:
 			break;
@@ -1298,6 +1299,7 @@ static int wx_tso(struct wx_ring *tx_ring, struct wx_tx_buffer *first,
 						WX_TXD_TUNNEL_LEN_SHIFT);
 			break;
 		case IPPROTO_IPIP:
+		case IPPROTO_IPV6:
 			tunhdr_eiplen_tunlen = (((char *)inner_ip_hdr(skb) -
 						(char *)ip_hdr(skb)) >> 2) <<
 						WX_TXD_OUTER_IPLEN_SHIFT;
@@ -1341,6 +1343,8 @@ static void wx_tx_csum(struct wx_ring *tx_ring, struct wx_tx_buffer *first,
 		vlan_macip_lens = skb_network_offset(skb) <<
 				  WX_TXD_MACLEN_SHIFT;
 	} else {
+		unsigned char *exthdr, *l4_hdr;
+		__be16 frag_off;
 		u8 l4_prot = 0;
 		union {
 			struct iphdr *ipv4;
@@ -1362,7 +1366,12 @@ static void wx_tx_csum(struct wx_ring *tx_ring, struct wx_tx_buffer *first,
 				tun_prot = ip_hdr(skb)->protocol;
 				break;
 			case htons(ETH_P_IPV6):
+				l4_hdr = skb_transport_header(skb);
+				exthdr = skb_network_header(skb) + sizeof(struct ipv6hdr);
 				tun_prot = ipv6_hdr(skb)->nexthdr;
+				if (l4_hdr != exthdr)
+					ipv6_skip_exthdr(skb, exthdr - skb->data,
+							 &tun_prot, &frag_off);
 				break;
 			default:
 				return;
@@ -1386,6 +1395,7 @@ static void wx_tx_csum(struct wx_ring *tx_ring, struct wx_tx_buffer *first,
 							  WX_TXD_TUNNEL_LEN_SHIFT);
 				break;
 			case IPPROTO_IPIP:
+			case IPPROTO_IPV6:
 				tunhdr_eiplen_tunlen = (((char *)inner_ip_hdr(skb) -
 							(char *)ip_hdr(skb)) >> 2) <<
 							WX_TXD_OUTER_IPLEN_SHIFT;
@@ -1408,7 +1418,10 @@ static void wx_tx_csum(struct wx_ring *tx_ring, struct wx_tx_buffer *first,
 			break;
 		case 6:
 			vlan_macip_lens |= (transport_hdr.raw - network_hdr.raw) >> 1;
+			exthdr = network_hdr.raw + sizeof(struct ipv6hdr);
 			l4_prot = network_hdr.ipv6->nexthdr;
+			if (transport_hdr.raw != exthdr)
+				ipv6_skip_exthdr(skb, exthdr - skb->data, &l4_prot, &frag_off);
 			break;
 		default:
 			break;