From patchwork Thu Nov 8 15:11:37 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Dichtel X-Patchwork-Id: 994954 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=6wind.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 42rRbW4rvwz9sBN for ; Fri, 9 Nov 2018 02:12:23 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727231AbeKIAsS (ORCPT ); Thu, 8 Nov 2018 19:48:18 -0500 Received: from host.76.145.23.62.rev.coltfrance.com ([62.23.145.76]:43674 "EHLO proxy.6wind.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726421AbeKIAsS (ORCPT ); Thu, 8 Nov 2018 19:48:18 -0500 Received: from bretzel.dev.6wind.com (unknown [10.16.0.19]) by proxy.6wind.com (Postfix) with ESMTPS id 3C77A21656A; Thu, 8 Nov 2018 16:10:35 +0100 (CET) Received: from dichtel by bretzel.dev.6wind.com with local (Exim 4.89) (envelope-from ) id 1gKlyT-0002Jf-5c; Thu, 08 Nov 2018 16:12:01 +0100 From: Nicolas Dichtel To: ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net Cc: netdev@vger.kernel.org, Nicolas Dichtel Subject: [PATCH bpf-next] filter: add BPF_ADJ_ROOM_DATA mode to bpf_skb_adjust_room() Date: Thu, 8 Nov 2018 16:11:37 +0100 Message-Id: <20181108151137.3975-1-nicolas.dichtel@6wind.com> X-Mailer: git-send-email 2.18.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This new mode enables to add or remove an l2 header in a programmatic way with cls_bpf. For example, it enables to play with mpls headers. Signed-off-by: Nicolas Dichtel Acked-by: Martin KaFai Lau --- include/uapi/linux/bpf.h | 3 ++ net/core/filter.c | 54 ++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 3 ++ 3 files changed, 60 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 852dc17ab47a..47407fd5162b 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1467,6 +1467,8 @@ union bpf_attr { * * * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer * (room space is added or removed below the layer 3 header). + * * **BPF_ADJ_ROOM_DATA**: Adjust room at the beginning of the + * packet (room space is added or removed below skb->data). * * All values for *flags* are reserved for future usage, and must * be left at zero. @@ -2408,6 +2410,7 @@ enum bpf_func_id { /* Mode for BPF_FUNC_skb_adjust_room helper. */ enum bpf_adj_room_mode { BPF_ADJ_ROOM_NET, + BPF_ADJ_ROOM_DATA, }; /* Mode for BPF_FUNC_skb_load_bytes_relative helper. */ diff --git a/net/core/filter.c b/net/core/filter.c index e521c5ebc7d1..e699849b269d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2884,6 +2884,58 @@ static int bpf_skb_adjust_net(struct sk_buff *skb, s32 len_diff) return ret; } +static int bpf_skb_data_shrink(struct sk_buff *skb, u32 len) +{ + unsigned short hhlen = skb->dev->header_ops ? + skb->dev->hard_header_len : 0; + int ret; + + ret = skb_unclone(skb, GFP_ATOMIC); + if (unlikely(ret < 0)) + return ret; + + __skb_pull(skb, len); + skb_reset_mac_header(skb); + skb_reset_network_header(skb); + skb->network_header += hhlen; + skb_reset_transport_header(skb); + return 0; +} + +static int bpf_skb_data_grow(struct sk_buff *skb, u32 len) +{ + unsigned short hhlen = skb->dev->header_ops ? + skb->dev->hard_header_len : 0; + int ret; + + ret = skb_cow(skb, len); + if (unlikely(ret < 0)) + return ret; + + skb_push(skb, len); + skb_reset_mac_header(skb); + return 0; +} + +static int bpf_skb_adjust_data(struct sk_buff *skb, s32 len_diff) +{ + u32 len_diff_abs = abs(len_diff); + bool shrink = len_diff < 0; + int ret; + + if (unlikely(len_diff_abs > 0xfffU)) + return -EFAULT; + + if (shrink && len_diff_abs >= skb_headlen(skb)) + return -EFAULT; + + ret = shrink ? bpf_skb_data_shrink(skb, len_diff_abs) : + bpf_skb_data_grow(skb, len_diff_abs); + + bpf_compute_data_pointers(skb); + return ret; +} + BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, u32, mode, u64, flags) { @@ -2891,6 +2943,8 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, return -EINVAL; if (likely(mode == BPF_ADJ_ROOM_NET)) return bpf_skb_adjust_net(skb, len_diff); + if (likely(mode == BPF_ADJ_ROOM_DATA)) + return bpf_skb_adjust_data(skb, len_diff); return -ENOTSUPP; } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 852dc17ab47a..47407fd5162b 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1467,6 +1467,8 @@ union bpf_attr { * * * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer * (room space is added or removed below the layer 3 header). + * * **BPF_ADJ_ROOM_DATA**: Adjust room at the beginning of the + * packet (room space is added or removed below skb->data). * * All values for *flags* are reserved for future usage, and must * be left at zero. @@ -2408,6 +2410,7 @@ enum bpf_func_id { /* Mode for BPF_FUNC_skb_adjust_room helper. */ enum bpf_adj_room_mode { BPF_ADJ_ROOM_NET, + BPF_ADJ_ROOM_DATA, }; /* Mode for BPF_FUNC_skb_load_bytes_relative helper. */