linux-kernel - [PATCH] net: bpf: Allow TC programs to call BPF_FUNC_skb_change

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Date:   Mon, 20 Apr 2020 11:34:08 -0700
From:   Maciej Żenczykowski <zenczykowski@...il.com>
To:     Maciej Żenczykowski <maze@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Cc:     Linux Network Development Mailing List <netdev@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Lorenzo Colitti <lorenzo@...gle.com>
Subject: [PATCH] net: bpf: Allow TC programs to call BPF_FUNC_skb_change_head

From: Lorenzo Colitti <lorenzo@...gle.com>

This allows TC eBPF programs to modify and forward (redirect) packets
from interfaces without ethernet headers (for example cellular)
to interfaces with (for example ethernet/wifi).

The lack of this appears to simply be an oversight.

Tested:
  in active use in Android R on 4.14+ devices for ipv6
  cellular to wifi tethering offload.

Signed-off-by: Lorenzo Colitti <lorenzo@...gle.com>
Signed-off-by: Maciej Żenczykowski <maze@...gle.com>
---
 net/core/filter.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 7d6ceaa54d21..755867867e57 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6213,6 +6213,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_skb_adjust_room_proto;
 	case BPF_FUNC_skb_change_tail:
 		return &bpf_skb_change_tail_proto;
+	case BPF_FUNC_skb_change_head:
+		return &bpf_skb_change_head_proto;
 	case BPF_FUNC_skb_get_tunnel_key:
 		return &bpf_skb_get_tunnel_key_proto;
 	case BPF_FUNC_skb_set_tunnel_key:
-- 
2.26.1.301.g55bc3eb7cb9-goog