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bpf: make tun compatible w/ bpf_xdp_adjust_tail

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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 tun driver we need to adjust XDP_PASS handling by recalculating
length of the packet if it was passed to the TCP/IP stack
(in case if after xdp's prog run data_end pointer was adjusted)

Reviewed-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Nikita V. Shirokov 2018-04-17 21:42:19 -07:00 committed by Daniel Borkmann
parent 5a6a22e378
commit 8fb58f1ecf
1 changed files with 2 additions and 1 deletions
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3
drivers/net/tun.c
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@ -1696,6 +1696,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
return NULL;
case XDP_PASS:
delta = orig_data - xdp.data;
len = xdp.data_end - xdp.data;
break;
default:
bpf_warn_invalid_xdp_action(act);
@ -1716,7 +1717,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
}
skb_reserve(skb, pad - delta);
skb_put(skb, len + delta);
skb_put(skb, len);
get_page(alloc_frag->page);
alloc_frag->offset += buflen;