From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Nikita V. Shirokov" Subject: [PATCH bpf-next v2 02/11] bpf: make generic xdp compatible w/ bpf_xdp_adjust_tail Date: Tue, 17 Apr 2018 21:29:42 -0700 Message-ID: <20180418042951.17183-3-tehnerd@tehnerd.com> References: <20180418042951.17183-1-tehnerd@tehnerd.com> Cc: netdev@vger.kernel.org, "Nikita V. Shirokov" To: Alexei Starovoitov , Daniel Borkmann , "David S. Miller " Return-path: Received: from mail-pg0-f51.google.com ([74.125.83.51]:33379 "EHLO mail-pg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751836AbeDRGFv (ORCPT ); Wed, 18 Apr 2018 02:05:51 -0400 Received: by mail-pg0-f51.google.com with SMTP id i194so355827pgd.0 for ; Tue, 17 Apr 2018 23:05:51 -0700 (PDT) In-Reply-To: <20180418042951.17183-1-tehnerd@tehnerd.com> Sender: netdev-owner@vger.kernel.org List-ID: w/ bpf_xdp_adjust_tail helper xdp's data_end pointer could be changed as well (only "decrease" of pointer's location is going to be supported). changing of this pointer will change packet's size. for generic XDP we need to reflect this packet's length change by adjusting skb's tail pointer Acked-by: Alexei Starovoitov --- net/core/dev.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index 969462ebb296..11c789231a03 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3996,9 +3996,9 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, struct bpf_prog *xdp_prog) { struct netdev_rx_queue *rxqueue; + void *orig_data, *orig_data_end; u32 metalen, act = XDP_DROP; struct xdp_buff xdp; - void *orig_data; int hlen, off; u32 mac_len; @@ -4037,6 +4037,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, xdp.data_meta = xdp.data; xdp.data_end = xdp.data + hlen; xdp.data_hard_start = skb->data - skb_headroom(skb); + orig_data_end = xdp.data_end; orig_data = xdp.data; rxqueue = netif_get_rxqueue(skb); @@ -4051,6 +4052,13 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, __skb_push(skb, -off); skb->mac_header += off; + /* check if bpf_xdp_adjust_tail was used. it can only "shrink" + * pckt. + */ + off = orig_data_end - xdp.data_end; + if (off != 0) + skb_set_tail_pointer(skb, xdp.data_end - xdp.data); + switch (act) { case XDP_REDIRECT: case XDP_TX: -- 2.15.1