ebpf: add skb->priority to offset map for usage in {cls, act}_bpf

borkmann · davem330 · commit bcad57182425 · 2015-04-03T14:59:15.000-04:00
This adds the ability to read out the skb-&gt;priority from an eBPF
program, so that it can be taken into account from a tc filter
or action for the use-case where the priority is not being used
to directly override the filter classification in a qdisc, but
to tag traffic otherwise for the classifier; the priority can be
assigned from various places incl. user space, in future we may
also mangle it from an eBPF program.

Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Cc: Alexei Starovoitov &lt;ast@plumgrid.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
@@ -184,6 +184,7 @@ struct __sk_buff {
 	__u32 vlan_present;
 	__u32 vlan_tci;
 	__u32 vlan_proto;
+	__u32 priority;
 };
 
 #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/net/core/filter.c b/net/core/filter.c
@@ -1304,6 +1304,13 @@ static u32 sk_filter_convert_ctx_access(int dst_reg, int src_reg, int ctx_off,
 				      offsetof(struct sk_buff, vlan_proto));
 		break;
 
+	case offsetof(struct __sk_buff, priority):
+		BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, priority) != 4);
+
+		*insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg,
+				      offsetof(struct sk_buff, priority));
+		break;
+
 	case offsetof(struct __sk_buff, mark):
 		return convert_skb_access(SKF_AD_MARK, dst_reg, src_reg, insn);
 
