bpf: Add source ip in "struct bpf_tunnel_key"

Add tunnel source ip field in "struct bpf_tunnel_key". Add related code
to set and get tunnel source field.

Signed-off-by: Kaixi Fan <fankaixi.li@bytedance.com>
Link: https://lore.kernel.org/r/20220430074844.69214-2-fankaixi.li@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: Kaixi Fan

include/uapi/linux/bpf.h

@@ -5604,6 +5604,10 @@ struct bpf_tunnel_key {
 	__u8 tunnel_ttl;
 	__u16 tunnel_ext;	/* Padding, future use. */
 	__u32 tunnel_label;
+	union {
+		__u32 local_ipv4;
+		__u32 local_ipv6[4];
+	};
 };
 
 /* user accessible mirror of in-kernel xfrm_state.

net/core/filter.c

@@ -4498,6 +4498,7 @@ BPF_CALL_4(bpf_skb_get_tunnel_key, struct sk_buff *, skb, struct bpf_tunnel_key
 	if (unlikely(size != sizeof(struct bpf_tunnel_key))) {
 		err = -EINVAL;
 		switch (size) {
+		case offsetof(struct bpf_tunnel_key, local_ipv6[0]):
 		case offsetof(struct bpf_tunnel_key, tunnel_label):
 		case offsetof(struct bpf_tunnel_key, tunnel_ext):
 			goto set_compat;
@@ -4523,10 +4524,14 @@ BPF_CALL_4(bpf_skb_get_tunnel_key, struct sk_buff *, skb, struct bpf_tunnel_key
 	if (flags & BPF_F_TUNINFO_IPV6) {
 		memcpy(to->remote_ipv6, &info->key.u.ipv6.src,
 		       sizeof(to->remote_ipv6));
+		memcpy(to->local_ipv6, &info->key.u.ipv6.dst,
+		       sizeof(to->local_ipv6));
 		to->tunnel_label = be32_to_cpu(info->key.label);
 	} else {
 		to->remote_ipv4 = be32_to_cpu(info->key.u.ipv4.src);
 		memset(&to->remote_ipv6[1], 0, sizeof(__u32) * 3);
+		to->local_ipv4 = be32_to_cpu(info->key.u.ipv4.dst);
+		memset(&to->local_ipv6[1], 0, sizeof(__u32) * 3);
 		to->tunnel_label = 0;
 	}
 
@@ -4597,6 +4602,7 @@ BPF_CALL_4(bpf_skb_set_tunnel_key, struct sk_buff *, skb,
 		return -EINVAL;
 	if (unlikely(size != sizeof(struct bpf_tunnel_key))) {
 		switch (size) {
+		case offsetof(struct bpf_tunnel_key, local_ipv6[0]):
 		case offsetof(struct bpf_tunnel_key, tunnel_label):
 		case offsetof(struct bpf_tunnel_key, tunnel_ext):
 		case offsetof(struct bpf_tunnel_key, remote_ipv6[1]):
@@ -4639,10 +4645,13 @@ BPF_CALL_4(bpf_skb_set_tunnel_key, struct sk_buff *, skb,
 		info->mode |= IP_TUNNEL_INFO_IPV6;
 		memcpy(&info->key.u.ipv6.dst, from->remote_ipv6,
 		       sizeof(from->remote_ipv6));
+		memcpy(&info->key.u.ipv6.src, from->local_ipv6,
+		       sizeof(from->local_ipv6));
 		info->key.label = cpu_to_be32(from->tunnel_label) &
 				  IPV6_FLOWLABEL_MASK;
 	} else {
 		info->key.u.ipv4.dst = cpu_to_be32(from->remote_ipv4);
+		info->key.u.ipv4.src = cpu_to_be32(from->local_ipv4);
 	}
 
 	return 0;

tools/include/uapi/linux/bpf.h

@@ -5604,6 +5604,10 @@ struct bpf_tunnel_key {
 	__u8 tunnel_ttl;
 	__u16 tunnel_ext;	/* Padding, future use. */
 	__u32 tunnel_label;
+	union {
+		__u32 local_ipv4;
+		__u32 local_ipv6[4];
+	};
 };
 
 /* user accessible mirror of in-kernel xfrm_state.