[PATCH] net: fix parsing of frames with arbitrary VLAN stacks

[Gregory Etelson <getelson@nvidia.com>]

The rte_net_get_ptype() supported only 2 types of VLAN headers frames
that are defined in the IEEE standards 802.1Q and 802.1ad:

frames with a single 0x8100 VLAN header:
  eth type VLAN / vlan / [IPv4 | IPv6 ]

frames with 0x88A8 QinQ header followed by 0x8100 VLAN:
 eth type QinQ / vlan type VLAN / vlan / [IPv4 | IPv6 ]

The function did not parse frames where VLAN headers were stacked in
different configurations.
Such frames should also be allowed to provide HW vendor flexibility.
As a result, ptype bitmask and header length returned from
rte_net_get_ptype() for a custom VLAN frame were wrong.

For example, the parser result for the frame
  eth type QinQ / vlan type QinQ / vlan type VLAN / vlan / ipv4
was:
pkt_type:=0x120007
   RTE_PTYPE_L2_ETHER_QINQ         0x00000007 OK
   RTE_PTYPE_INNER_L2_ETHER_VLAN   0x00020000 wrong
   RTE_PTYPE_INNER_L3_IPV4         0x00100000 wrong

hdr_lens:={
  l2_len       = 22 wrong
  inner_l2_len =  4 wrong
  l3_len       =  0 wrong
  inner_l3_len = 20 wrong
}

The patch changes:
1. Allow frames with an arbitrary number of VLAN headers.

2. Set each parsed VLAN type in the returned ptype bitmask.
   Multiple VLAN headers are referenced by a single
   RTE_PTYPE_L2_ETHER_VLAN bit.
   Multiple QinQ headers are references by a single
   RTE_PTYPE_L2_ETHER_QINQ bit.

3. Preserve RTE_PTYPE_L2_ETHER bit if VLAN or QinQ type was detected.

Fixes: eb173c8def0a ("net: support VLAN in software packet type parser")
Fixes: 218a163efd67 ("net: support QinQ in software packet type parser")

Cc: stable@dpdk.org

Signed-off-by: Gregory Etelson <getelson@nvidia.com>
---
 lib/net/rte_net.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/lib/net/rte_net.c b/lib/net/rte_net.c
index 44fb6c0f51..96fb054f55 100644
--- a/lib/net/rte_net.c
+++ b/lib/net/rte_net.c
@@ -349,30 +349,24 @@ uint32_t rte_net_get_ptype(const struct rte_mbuf *m,
 	if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_IPV4))
 		goto l3; /* fast path if packet is IPv4 */
 
-	if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN)) {
+	while (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN) ||
+	       proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_QINQ)) {
 		const struct rte_vlan_hdr *vh;
 		struct rte_vlan_hdr vh_copy;
 
-		pkt_type = RTE_PTYPE_L2_ETHER_VLAN;
+		pkt_type |=
+			proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_VLAN) ?
+				 RTE_PTYPE_L2_ETHER_VLAN :
+				 RTE_PTYPE_L2_ETHER_QINQ;
 		vh = rte_pktmbuf_read(m, off, sizeof(*vh), &vh_copy);
 		if (unlikely(vh == NULL))
 			return pkt_type;
 		off += sizeof(*vh);
 		hdr_lens->l2_len += sizeof(*vh);
 		proto = vh->eth_proto;
-	} else if (proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_QINQ)) {
-		const struct rte_vlan_hdr *vh;
-		struct rte_vlan_hdr vh_copy;
+	}
 
-		pkt_type = RTE_PTYPE_L2_ETHER_QINQ;
-		vh = rte_pktmbuf_read(m, off + sizeof(*vh), sizeof(*vh),
-			&vh_copy);
-		if (unlikely(vh == NULL))
-			return pkt_type;
-		off += 2 * sizeof(*vh);
-		hdr_lens->l2_len += 2 * sizeof(*vh);
-		proto = vh->eth_proto;
-	} else if ((proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_MPLS)) ||
+	if ((proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_MPLS)) ||
 		(proto == rte_cpu_to_be_16(RTE_ETHER_TYPE_MPLSM))) {
 		unsigned int i;
 		const struct rte_mpls_hdr *mh;
-- 
2.51.0