classic BPF already exposes skb->dev->ifindex via SKF_AD_IFINDEX extension.
Allow eBPF program to access it as well. Note that classic aborts execution
of the program if 'skb->dev == NULL' (which is inconvenient for program
writers), whereas eBPF returns zero in such case.
Also expose the 'skb_iif' field, since programs triggered by redirected
packet need to known the original interface index.
Summary:
__skb->ifindex -> skb->dev->ifindex
__skb->ingress_ifindex -> skb->skb_iif
Signed-off-by: Alexei Starovoitov <a...@plumgrid.com>
---
include/uapi/linux/bpf.h | 2 ++
net/core/filter.c | 18 ++++++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f0a9af8b4dae..72f3080afa1e 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -236,6 +236,8 @@ struct __sk_buff {
__u32 vlan_tci;
__u32 vlan_proto;
__u32 priority;
+ __u32 ingress_ifindex;
+ __u32 ifindex;
};
#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/net/core/filter.c b/net/core/filter.c
index 3adcca6f17a4..2c30d6632d66 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1499,6 +1499,24 @@ static u32 sk_filter_convert_ctx_access(int dst_reg, int
src_reg, int ctx_off,
offsetof(struct sk_buff, priority));
break;
+ case offsetof(struct __sk_buff, ingress_ifindex):
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, skb_iif) != 4);
+
+ *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg,
+ offsetof(struct sk_buff, skb_iif));
+ break;
+
+ case offsetof(struct __sk_buff, ifindex):
+ BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
+
+ *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct
sk_buff, dev)),
+ dst_reg, src_reg,
+ offsetof(struct sk_buff, dev));
+ *insn++ = BPF_JMP_IMM(BPF_JEQ, dst_reg, 0, 1);
+ *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, dst_reg,
+ offsetof(struct net_device, ifindex));
+ break;
+
case offsetof(struct __sk_buff, mark):
return convert_skb_access(SKF_AD_MARK, dst_reg, src_reg, insn);
--
1.7.9.5
--
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