bpf: Allow bpf_get_netns_cookie in BPF_PROG_TYPE_CGROUP_SOCKOPT

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

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index b567ca4..9f60703 100644 (file)
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1846,11 +1846,29 @@ const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
 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: