netdev - [PATCH bpf-next 1/2] bpf: Add sock ops get netns helpers

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Date:   Thu,  6 Feb 2020 16:35:14 +0800
From:   Lingpeng Chen <forrest0579@...il.com>
To:     bpf <bpf@...r.kernel.org>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Lingpeng Chen <forrest0579@...il.com>
Subject: [PATCH bpf-next 1/2] bpf: Add sock ops get netns helpers

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 <forrest0579@...il.com>
---
 include/uapi/linux/bpf.h |  8 +++++++-
 net/core/filter.c        | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f1d74a2bd234..b15a55051232 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
+ * u32 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 792e3744b915..b7f33f20e8fb 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4421,6 +4421,22 @@ 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)
+{
+	struct sock *sk = bpf_sock->sk;
+
+	if (!IS_ENABLED(CONFIG_NET_NS))
+		return 0;
+	return sk->sk_net.net->ns.inum;
+}
+
+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 +6234,8 @@ 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);
 	}
-- 
2.17.1