From: Yonghong Song <yhs@fb.com>
Date: Thu, 27 Sep 2018 14:37:30 -0700
Subject: bpf: permit CGROUP_DEVICE programs accessing helper
 bpf_get_current_cgroup_id()
Patch-mainline: v4.20-rc1
Git-commit: 5bf7a60b8e70969f65c961d7e2c4eb40eb2c664d
References: bsc#1109837

Currently, helper bpf_get_current_cgroup_id() is not permitted
for CGROUP_DEVICE type of programs. If the helper is used
in such cases, the verifier will log the following error:

  0: (bf) r6 = r1
  1: (69) r7 = *(u16 *)(r6 +0)
  2: (85) call bpf_get_current_cgroup_id#80
  unknown func bpf_get_current_cgroup_id#80

The bpf_get_current_cgroup_id() is useful for CGROUP_DEVICE
type of programs in order to customize action based on cgroup id.
This patch added such a support.

Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/bpf/cgroup.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -623,6 +623,8 @@ cgroup_dev_func_proto(enum bpf_func_id f
 		return &bpf_get_current_uid_gid_proto;
 	case BPF_FUNC_get_local_storage:
 		return &bpf_get_local_storage_proto;
+	case BPF_FUNC_get_current_cgroup_id:
+		return &bpf_get_current_cgroup_id_proto;
 	case BPF_FUNC_trace_printk:
 		if (capable(CAP_SYS_ADMIN))
 			return bpf_get_trace_printk_proto();