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

This adds the ability to read out the skb->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 <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 74aab6e0d96436b5d24e19c18e9c8d81dc14eee9..0db8580f3ccae8156cdd398b3947b44e920b5563 100644 (file)
--- 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
index 444a07e4f68d7eca3e1c324ae91991d32779ae4d..955a7d77decdbfa19c08a908514bc2334e1cc049 100644 (file)
--- 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);