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From:   Roman Gushchin <guro@fb.com>
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To:     Daniel Borkmann <daniel@iogearbox.net>, <bpf@vger.kernel.org>
CC:     Alexei Starovoitov <ast@kernel.org>, <kernel-team@fb.com>,
        <linux-kernel@vger.kernel.org>, Roman Gushchin <guro@fb.com>,
        Yonghong Song <yhs@fb.com>
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Subject: [PATCH bpf-next] bpf: allow CGROUP_SKB programs to use bpf_skb_cgroup_id() helper
Date:   Thu, 6 Jun 2019 13:30:12 -0700
Message-ID: <20190606203012.130071-1-guro@fb.com>
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Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Currently bpf_skb_cgroup_id() is not supported for CGROUP_SKB
programs. An attempt to load such a program generates an error
like this:

    libbpf:
    0: (b7) r6 = 0
    ...
    9: (85) call bpf_skb_cgroup_id#79
    unknown func bpf_skb_cgroup_id#79

There are no particular reasons for denying it, and we have some
use cases where it might be useful.

So let's add it to the list of allowed helpers.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
 net/core/filter.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 55bfc941d17a..f2777dc0b624 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5919,6 +5919,10 @@ cg_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_storage_get_proto;
 	case BPF_FUNC_sk_storage_delete:
 		return &bpf_sk_storage_delete_proto;
+#ifdef CONFIG_SOCK_CGROUP_DATA
+	case BPF_FUNC_skb_cgroup_id:
+		return &bpf_skb_cgroup_id_proto;
+#endif
 #ifdef CONFIG_INET
 	case BPF_FUNC_tcp_sock:
 		return &bpf_tcp_sock_proto;
-- 
2.20.1