From: Stanislav Fomichev <sdf@google.com>
Date: Fri, 13 Aug 2021 16:05:29 -0700
Subject: bpf: Allow bpf_get_netns_cookie in BPF_PROG_TYPE_CGROUP_SOCKOPT
Patch-mainline: v5.15-rc1
Git-commit: f1248dee954c2ddb0ece47a13591e5d55d422d22
References: jsc#PED-1377

This is similar to existing BPF_PROG_TYPE_CGROUP_SOCK
and BPF_PROG_TYPE_CGROUP_SOCK_ADDR.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210813230530.333779-2-sdf@google.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 kernel/bpf/cgroup.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1846,11 +1846,29 @@ const struct bpf_verifier_ops cg_sysctl_
 const struct bpf_prog_ops cg_sysctl_prog_ops = {
 };
 
+#ifdef CONFIG_NET
+BPF_CALL_1(bpf_get_netns_cookie_sockopt, struct bpf_sockopt_kern *, ctx)
+{
+	const struct net *net = ctx ? sock_net(ctx->sk) : &init_net;
+
+	return net->net_cookie;
+}
+
+static const struct bpf_func_proto bpf_get_netns_cookie_sockopt_proto = {
+	.func		= bpf_get_netns_cookie_sockopt,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX_OR_NULL,
+};
+#endif
+
 static const struct bpf_func_proto *
 cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
 	switch (func_id) {
 #ifdef CONFIG_NET
+	case BPF_FUNC_get_netns_cookie:
+		return &bpf_get_netns_cookie_sockopt_proto;
 	case BPF_FUNC_sk_storage_get:
 		return &bpf_sk_storage_get_proto;
 	case BPF_FUNC_sk_storage_delete: