1 files changed, 38 insertions, 3 deletions

diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 9e41eff4a685..0dcee9df1326 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -10,6 +10,9 @@
 #include <net/tcp.h>
 #include <net/bpf_sk_storage.h>
 
+/* "extern" is to avoid sparse warning.  It is only used in bpf_struct_ops.c. */
+extern struct bpf_struct_ops bpf_tcp_congestion_ops;
+
 static u32 optional_ops[] = {
 	offsetof(struct tcp_congestion_ops, init),
 	offsetof(struct tcp_congestion_ops, release),
@@ -163,6 +166,19 @@ static const struct bpf_func_proto bpf_tcp_send_ack_proto = {
 	.arg2_type	= ARG_ANYTHING,
 };
 
+static u32 prog_ops_moff(const struct bpf_prog *prog)
+{
+	const struct btf_member *m;
+	const struct btf_type *t;
+	u32 midx;
+
+	midx = prog->expected_attach_type;
+	t = bpf_tcp_congestion_ops.type;
+	m = &btf_type_member(t)[midx];
+
+	return btf_member_bit_offset(t, m) / 8;
+}
+
 static const struct bpf_func_proto *
 bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
 			  const struct bpf_prog *prog)
@@ -174,6 +190,28 @@ bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
 		return &bpf_sk_storage_get_proto;
 	case BPF_FUNC_sk_storage_delete:
 		return &bpf_sk_storage_delete_proto;
+	case BPF_FUNC_setsockopt:
+		/* Does not allow release() to call setsockopt.
+		 * release() is called when the current bpf-tcp-cc
+		 * is retiring.  It is not allowed to call
+		 * setsockopt() to make further changes which
+		 * may potentially allocate new resources.
+		 */
+		if (prog_ops_moff(prog) !=
+		    offsetof(struct tcp_congestion_ops, release))
+			return &bpf_sk_setsockopt_proto;
+		return NULL;
+	case BPF_FUNC_getsockopt:
+		/* Since get/setsockopt is usually expected to
+		 * be available together, disable getsockopt for
+		 * release also to avoid usage surprise.
+		 * The bpf-tcp-cc already has a more powerful way
+		 * to read tcp_sock from the PTR_TO_BTF_ID.
+		 */
+		if (prog_ops_moff(prog) !=
+		    offsetof(struct tcp_congestion_ops, release))
+			return &bpf_sk_getsockopt_proto;
+		return NULL;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -286,9 +324,6 @@ static void bpf_tcp_ca_unreg(void *kdata)
 	tcp_unregister_congestion_control(kdata);
 }
 
-/* Avoid sparse warning.  It is only used in bpf_struct_ops.c. */
-extern struct bpf_struct_ops bpf_tcp_congestion_ops;
-
 struct bpf_struct_ops bpf_tcp_congestion_ops = {
 	.verifier_ops = &bpf_tcp_ca_verifier_ops,
 	.reg = bpf_tcp_ca_reg,