filter: introduce SKF_AD_VLAN_TPID BPF extension

If vlan offloading takes place then vlan header is removed from frame
and its contents, both vlan_tci and vlan_proto, is available to user
space via TPACKET interface. However, only vlan_tci can be used in BPF
filters.

This commit introduces a new BPF extension. It makes possible to load
the value of vlan_proto (vlan TPID) to register A. Support for classic
BPF and eBPF is being added, analogous to skb->protocol.

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Jiri Pirko <jpirko@redhat.com>

Signed-off-by: Michal Sekletar <msekleta@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 3 insertions, 1 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3dd314a45d0d..27dc4ec58840 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -182,6 +182,7 @@ struct __sk_buff {
         __u32 protocol;
         __u32 vlan_present;
         __u32 vlan_tci;
+        __u32 vlan_proto;
 };
 
 #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/include/uapi/linux/filter.h b/include/uapi/linux/filter.h
index 47785d5ecf17..34c7936ca114 100644
--- a/include/uapi/linux/filter.h
+++ b/include/uapi/linux/filter.h
@@ -77,7 +77,8 @@ struct sock_fprog {	/* Required for SO_ATTACH_FILTER. */
 #define SKF_AD_VLAN_TAG_PRESENT 48
 #define SKF_AD_PAY_OFFSET       52
 #define SKF_AD_RANDOM   56
-#define SKF_AD_MAX      60
+#define SKF_AD_VLAN_TPID        60
+#define SKF_AD_MAX      64
 #define SKF_NET_OFF   (-0x100000)
 #define SKF_LL_OFF    (-0x200000)