[PATCH v1 bpf-next/net 5/8] bpf: Support bpf_setsockopt() for BPF_CGROUP_INET_SOCK_(CREATE|ACCEPT).

[Kuniyuki Iwashima <kuniyu@google.com>]

We will store a flag in sk->sk_memcg by bpf_setsockopt() during
socket() and accept().

BPF_CGROUP_INET_SOCK_CREATE and BPF_CGROUP_INET_SOCK_ACCEPT are
invoked by __cgroup_bpf_run_filter_sk() that passes a pointer to
struct sock to the bpf prog as void *ctx.

But there are no bpf_func_proto for bpf_setsockopt() that receives
the ctx as a pointer to struct sock.

Let's add new bpf_setsockopt() variants and support them in two
attach types.

Note that __inet_accept() is under lock_sock() but inet_create()
is not.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 net/core/filter.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 63f3baee2daf..aa17c7ed5aed 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5743,6 +5743,40 @@ static const struct bpf_func_proto bpf_sock_ops_setsockopt_proto = {
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
+BPF_CALL_5(bpf_sock_setsockopt, struct sock *, sk, int, level,
+	   int, optname, char *, optval, int, optlen)
+{
+	return __bpf_setsockopt(sk, level, optname, optval, optlen);
+}
+
+const struct bpf_func_proto bpf_sock_setsockopt_proto = {
+	.func		= bpf_sock_setsockopt,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
+	.arg5_type	= ARG_CONST_SIZE,
+};
+
+BPF_CALL_5(bpf_unlocked_sock_setsockopt, struct sock *, sk, int, level,
+	   int, optname, char *, optval, int, optlen)
+{
+	return _bpf_setsockopt(sk, level, optname, optval, optlen);
+}
+
+const struct bpf_func_proto bpf_unlocked_sock_setsockopt_proto = {
+	.func		= bpf_unlocked_sock_setsockopt,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
+	.arg5_type	= ARG_CONST_SIZE,
+};
+
 static int bpf_sock_ops_get_syn(struct bpf_sock_ops_kern *bpf_sock,
 				int optname, const u8 **start)
 {
@@ -8051,6 +8085,15 @@ sock_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_storage_get_cg_sock_proto;
 	case BPF_FUNC_ktime_get_coarse_ns:
 		return &bpf_ktime_get_coarse_ns_proto;
+	case BPF_FUNC_setsockopt:
+		switch (prog->expected_attach_type) {
+		case BPF_CGROUP_INET_SOCK_CREATE:
+			return &bpf_unlocked_sock_setsockopt_proto;
+		case BPF_CGROUP_INET_SOCK_ACCEPT:
+			return &bpf_sock_setsockopt_proto;
+		default:
+			return NULL;
+		}
 	default:
 		return bpf_base_func_proto(func_id, prog);
 	}
-- 
2.51.0.rc2.233.g662b1ed5c5-goog