Currently 5-tuple(sip+dip+sport+dport+proto) can't identify a
uniq connection because there may be multi net namespace.
For example, there may be a chance that netns a and netns b all
listen on 127.0.0.1:8080 and the client with same port 40782
connect to them. Without netns number, sock ops program
can't distinguish them.
Using bpf_sock_ops_get_netns helpers to get current connection
netns number to distinguish connections.

Signed-off-by: Lingpeng Chen <redacted>
---
  include/uapi/linux/bpf.h |  8 +++++++-
  net/core/filter.c        | 19 +++++++++++++++++++
  2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f1d74a2bd234..3573907d15e0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h

@@ -2892,6 +2892,11 @@ union bpf_attr {
   *		Obtain the 64bit jiffies
   *	Return
   *		The 64 bit jiffies
+ * u64 bpf_sock_ops_get_netns(struct bpf_sock_ops *bpf_socket)

+ *  Description
+ *      Obtain netns id of sock
+ * Return
+ *      The current netns inum
   */
  #define __BPF_FUNC_MAPPER(FN)		\
  	FN(unspec),			\

@@ -3012,7 +3017,8 @@ union bpf_attr {
  	FN(probe_read_kernel_str),	\
  	FN(tcp_send_ack),		\
  	FN(send_signal_thread),		\
-	FN(jiffies64),
+	FN(jiffies64),			\
+	FN(sock_ops_get_netns),

  
  /* integer value in 'imm' field of BPF_CALL instruction selects which helper
   * function eBPF program intends to call

diff --git a/net/core/filter.c b/net/core/filter.c
index c180871e606d..f8e946aa46fc 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c

@@ -4421,6 +4421,23 @@ static const struct bpf_func_proto bpf_sock_ops_cb_flags_set_proto = {
  	.arg2_type	= ARG_ANYTHING,
  };
  
+BPF_CALL_1(bpf_sock_ops_get_netns, struct bpf_sock_ops_kern *, bpf_sock)
+{
+#ifdef CONFIG_NET_NS
+	struct sock *sk = bpf_sock->sk;
+
+	return (u64)sk->sk_net.net->ns.inum;
+#endif
+	return 0;
+}
+
+static const struct bpf_func_proto bpf_sock_ops_get_netns_proto = {
+	.func		= bpf_sock_ops_get_netns,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+};
+
  const struct ipv6_bpf_stub *ipv6_bpf_stub __read_mostly;
  EXPORT_SYMBOL_GPL(ipv6_bpf_stub);
  

@@ -6218,6 +6235,8 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
  	case BPF_FUNC_tcp_sock:
  		return &bpf_tcp_sock_proto;
  #endif /* CONFIG_INET */
+	case BPF_FUNC_sock_ops_get_netns:
+		return &bpf_sock_ops_get_netns_proto;
  	default:
  		return bpf_base_func_proto(func_id);
  	}