From: Prankur Gupta <prankgup@fb.com>
Date: Tue, 17 Aug 2021 15:42:20 -0700
Subject: bpf: Add support for {set|get} socket options from setsockopt BPF
Patch-mainline: v5.15-rc1
Git-commit: 2c531639deb5e3ddfd6e8123b82052b2d9fbc6e5
References: jsc#PED-1377

Add logic to call bpf_setsockopt() and bpf_getsockopt() from setsockopt BPF
programs. An example use case is when the user sets the IPV6_TCLASS socket
option, we would also like to change the tcp-cc for that socket.

We don't have any use case for calling bpf_setsockopt() from supposedly read-
only sys_getsockopt(), so it is made available to BPF_CGROUP_SETSOCKOPT only
at this point.

Signed-off-by: Prankur Gupta <prankgup@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210817224221.3257826-2-prankgup@fb.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 kernel/bpf/cgroup.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1873,6 +1873,14 @@ cg_sockopt_func_proto(enum bpf_func_id f
 		return &bpf_sk_storage_get_proto;
 	case BPF_FUNC_sk_storage_delete:
 		return &bpf_sk_storage_delete_proto;
+	case BPF_FUNC_setsockopt:
+		if (prog->expected_attach_type == BPF_CGROUP_SETSOCKOPT)
+			return &bpf_sk_setsockopt_proto;
+		return NULL;
+	case BPF_FUNC_getsockopt:
+		if (prog->expected_attach_type == BPF_CGROUP_SETSOCKOPT)
+			return &bpf_sk_getsockopt_proto;
+		return NULL;
 #endif
 #ifdef CONFIG_INET
 	case BPF_FUNC_tcp_sock: