bpf: permit CGROUP_DEVICE programs accessing helper bpf_get_current_cgroup_id()

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>

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 6a7d931bbc55ff5c02f85bb437b93ba5237167db..549f6fbcc4612c58ce773c53d183fea5a8219883 100644 (file)
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -677,6 +677,8 @@ cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
                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();