Strip 802.1Q VLAN 0 priority tags 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.

Origin: vendor, https://git.centos.org/blob/rpms!ipxe.git/c7/SOURCES!0009-Strip-802.1Q-VLAN-0-priority-tags.patch
Bug-Ubuntu: https://bugs.launchpad.net/bugs/1805920


Gbp-Pq: Name 0005-strip-802.1Q-VLAN-0-priority-tags.patch

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 ):

src/include/ipxe/netdevice.h

@@ -726,6 +726,8 @@ 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 );

src/interface/efi/efi_snp.c

@@ -813,6 +813,13 @@ 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;

src/net/netdevice.c

@@ -1043,6 +1043,44 @@ int net_rx ( struct io_buffer *iobuf, struct net_device *netdev,
 	return -ENOTSUP;
 }
 
+/**
+ * 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
  *
@@ -1094,6 +1132,12 @@ 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,