[ipxe-devel] [PATCH] [netdevice] Strip 802.1Q VLAN 0 priority tags

[Ladi Prosek]

iPXE was unable to receive priority tagged packets specified in
the 802.1Q standard and supported by all major networking stacks.

This commit adds a new function net_pull_tags which is called by
all consumers of incoming packets after stripping their link-layer
headers.

Signed-off-by: Ladi Prosek <lprosek at redhat.com>
---

This is another attempt at implementing the VLAN 0 feature. It is
always enabled and independent of the true VLAN_CMD support, as
discussed before. All code paths that process incoming packets now
strip VLAN 0 headers.

If VLAN 0 was Ethernet only, it would conceptually belong in eth_pull.
Since it's "link-layer-independent", I took the liberty to create
a new function to be called between handling the link layer and
network layer headers. Thanks!

 src/arch/x86/interface/pxe/pxe_undi.c |  6 +++++
 src/include/ipxe/netdevice.h          |  2 ++
 src/interface/efi/efi_snp.c           |  7 ++++++
 src/net/netdevice.c                   | 44 +++++++++++++++++++++++++++++++++++
 4 files changed, 59 insertions(+)

diff --git a/src/arch/x86/interface/pxe/pxe_undi.c b/src/arch/x86/interface/pxe/pxe_undi.c
index 2eb6817..2ea1451 100644
--- a/src/arch/x86/interface/pxe/pxe_undi.c
+++ b/src/arch/x86/interface/pxe/pxe_undi.c
@@ -976,6 +976,12 @@ static PXENV_EXIT_t pxenv_undi_isr ( struct s_PXENV_UNDI_ISR *undi_isr ) {
 		}
 		ll_hlen = ( len - iob_len ( iobuf ) );
 
+		/* Strip link-layer-independent headers */
+		if ( ( rc = net_pull_tags ( iobuf, pxe_netdev, &net_proto ) ) != 0 ) {
+			/* Assume unknown net_proto */
+			net_proto = 0;
+		}
+
 		/* Determine network-layer protocol */
 		switch ( net_proto ) {
 		case htons ( ETH_P_IP ):
diff --git a/src/include/ipxe/netdevice.h b/src/include/ipxe/netdevice.h
index a1d207f..cea87f7 100644
--- a/src/include/ipxe/netdevice.h
+++ b/src/include/ipxe/netdevice.h
@@ -719,6 +719,8 @@ extern int net_tx ( struct io_buffer *iobuf, struct net_device *netdev,
 extern int net_rx ( struct io_buffer *iobuf, struct net_device *netdev,
 		    uint16_t net_proto, const void *ll_dest,
 		    const void *ll_source, unsigned int flags );
+extern int net_pull_tags ( struct io_buffer *iobuf, struct net_device *netdev,
+			   uint16_t *net_proto );
 extern void net_poll ( void );
 extern struct net_device_configurator *
 find_netdev_configurator ( const char *name );
diff --git a/src/interface/efi/efi_snp.c b/src/interface/efi/efi_snp.c
index e6388bf..d1a1a44 100644
--- a/src/interface/efi/efi_snp.c
+++ b/src/interface/efi/efi_snp.c
@@ -745,6 +745,13 @@ efi_snp_receive ( EFI_SIMPLE_NETWORK_PROTOCOL *snp,
 		goto out_bad_ll_header;
 	}
 
+	/* Strip link-layer-independent headers */
+	if ( ( rc = net_pull_tags ( iobuf, snpdev->netdev, &iob_net_proto ) ) ) {
+		DBGC ( snpdev, "SNPDEV %p could not parse tags: %s\n",
+		       snpdev, strerror ( rc ) );
+		goto out_bad_ll_header;
+	}
+
 	/* Return link-layer header parameters to caller, if required */
 	if ( ll_header_len )
 		*ll_header_len = ll_protocol->ll_header_len;
diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index 9df2119..c53d5e3 100644
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -1028,6 +1028,44 @@ int net_rx ( struct io_buffer *iobuf, struct net_device *netdev,
 }
 
 /**
+ * Strip extra link-layer-independent tags from a received packet
+ *
+ * @v iobuf		I/O buffer
+ * @v netdev		Network device
+ * @v net_proto		Network-layer protocol, in network-byte order
+ * @ret rc		Return status code
+ *
+ * This function should be called after stripping link-layer headers but
+ * before inspecting the network-layer protocol.
+ */
+int net_pull_tags ( struct io_buffer *iobuf, struct net_device *netdev,
+		    uint16_t *net_proto ) {
+	struct vlan_header *vlanhdr;
+	uint16_t tag;
+
+	/* Strip 802.1Q VLAN 0 priority tags if present */
+	while ( *net_proto == htons ( ETH_P_8021Q ) ) {
+		if ( iob_len ( iobuf ) < sizeof ( *vlanhdr ) ) {
+			DBG ( "VLAN header too short at %zd bytes (min %zd bytes)\n",
+			      iob_len ( iobuf ), sizeof ( *vlanhdr ) );
+			return -EINVAL;
+		}
+		vlanhdr = ( struct vlan_header * ) iobuf->data;
+		tag = VLAN_TAG ( ntohs ( vlanhdr->tci ) );
+
+		if ( tag == 0 && ! vlan_find ( netdev, tag ) ) {
+			/* VLAN 0, strip and continue */
+			*net_proto = vlanhdr->net_proto;
+			iob_pull ( iobuf, sizeof ( *vlanhdr ) );
+		} else {
+			/* Real VLAN tag, leave it alone */
+			break;
+		}
+	}
+	return 0;
+}
+
+/**
  * Poll the network stack
  *
  * This polls all interfaces for received packets, and processes
@@ -1078,6 +1116,12 @@ void net_poll ( void ) {
 				continue;
 			}
 
+			/* Remove link-layer-independent headers */
+			if ( ( rc = net_pull_tags ( iobuf, netdev, &net_proto ) ) ) {
+				free_iob ( iobuf );
+				continue;
+			}
+
 			/* Hand packet to network layer */
 			if ( ( rc = net_rx ( iob_disown ( iobuf ), netdev,
 					     net_proto, ll_dest,
-- 
2.5.5