From: Yonghong Song <yhs@fb.com>
Date: Mon, 4 Jun 2018 08:53:41 -0700
Subject: bpf: guard bpf_get_current_cgroup_id() with CONFIG_CGROUPS
Patch-mainline: v4.18-rc1
Git-commit: 34ea38ca27991466a8fff849514b4181b42ae2eb
References: bsc#1109837

Commit bf6fa2c893c5 ("bpf: implement bpf_get_current_cgroup_id()
helper") introduced a new helper bpf_get_current_cgroup_id().
The helper has a dependency on CONFIG_CGROUPS.

When CONFIG_CGROUPS is not defined, using the helper will result
the following verifier error:
  kernel subsystem misconfigured func bpf_get_current_cgroup_id#80
which is hard for users to interpret.
Guarding the reference to bpf_get_current_cgroup_id_proto with
CONFIG_CGROUPS will result in below better message:
  unknown func bpf_get_current_cgroup_id#80

Fixes: bf6fa2c893c5 ("bpf: implement bpf_get_current_cgroup_id() helper")
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/trace/bpf_trace.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -542,8 +542,10 @@ tracing_func_proto(enum bpf_func_id func
 		return &bpf_get_prandom_u32_proto;
 	case BPF_FUNC_probe_read_str:
 		return &bpf_probe_read_str_proto;
+#ifdef CONFIG_CGROUPS
 	case BPF_FUNC_get_current_cgroup_id:
 		return &bpf_get_current_cgroup_id_proto;
+#endif
 	default:
 		return NULL;
 	}