[PATCH v6 bpf-next 08/11] bpf: Support BPF_FUNC_get_socket_cookie() for BPF_PROG_TYPE_SK_REUSEPORT.

From: Kuniyuki Iwashima
Date: Sun May 16 2021 - 20:25:37 EST


We will call sock_reuseport.prog for socket migration in the next commit,
so the eBPF program has to know which listener is closing to select a new
listener.

We can currently get a unique ID of each listener in the userspace by
calling bpf_map_lookup_elem() for BPF_MAP_TYPE_REUSEPORT_SOCKARRAY map.

This patch makes the pointer of sk available in sk_reuseport_md so that we
can get the ID by BPF_FUNC_get_socket_cookie() in the eBPF program.

Link: https://lore.kernel.org/netdev/20201119001154.kapwihc2plp4f7zc@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
Suggested-by: Martin KaFai Lau <kafai@xxxxxx>
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx>
---
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 10 ++++++++++
tools/include/uapi/linux/bpf.h | 1 +
3 files changed, 12 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index ec6d85a81744..d2e6bf2d464b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5364,6 +5364,7 @@ struct sk_reuseport_md {
__u32 ip_protocol; /* IP protocol. e.g. IPPROTO_TCP, IPPROTO_UDP */
__u32 bind_inany; /* Is sock bound to an INANY address? */
__u32 hash; /* A hash of the packet 4 tuples */
+ __bpf_md_ptr(struct bpf_sock *, sk);
};

#define BPF_TAG_SIZE 8
diff --git a/net/core/filter.c b/net/core/filter.c
index cae56d08a670..5e971c701f34 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -10135,6 +10135,8 @@ sk_reuseport_func_proto(enum bpf_func_id func_id,
return &sk_reuseport_load_bytes_proto;
case BPF_FUNC_skb_load_bytes_relative:
return &sk_reuseport_load_bytes_relative_proto;
+ case BPF_FUNC_get_socket_cookie:
+ return &bpf_get_socket_ptr_cookie_proto;
default:
return bpf_base_func_proto(func_id);
}
@@ -10164,6 +10166,10 @@ sk_reuseport_is_valid_access(int off, int size,
case offsetof(struct sk_reuseport_md, hash):
return size == size_default;

+ case offsetof(struct sk_reuseport_md, sk):
+ info->reg_type = PTR_TO_SOCKET;
+ return size == sizeof(__u64);
+
/* Fields that allow narrowing */
case bpf_ctx_range(struct sk_reuseport_md, eth_protocol):
if (size < sizeof_field(struct sk_buff, protocol))
@@ -10236,6 +10242,10 @@ static u32 sk_reuseport_convert_ctx_access(enum bpf_access_type type,
case offsetof(struct sk_reuseport_md, bind_inany):
SK_REUSEPORT_LOAD_FIELD(bind_inany);
break;
+
+ case offsetof(struct sk_reuseport_md, sk):
+ SK_REUSEPORT_LOAD_FIELD(sk);
+ break;
}

return insn - insn_buf;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index ec6d85a81744..d2e6bf2d464b 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5364,6 +5364,7 @@ struct sk_reuseport_md {
__u32 ip_protocol; /* IP protocol. e.g. IPPROTO_TCP, IPPROTO_UDP */
__u32 bind_inany; /* Is sock bound to an INANY address? */
__u32 hash; /* A hash of the packet 4 tuples */
+ __bpf_md_ptr(struct bpf_sock *, sk);
};

#define BPF_TAG_SIZE 8
--
2.30.2