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bpf: make generic xdp 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 generic XDP we need to reflect this packet's length change by
adjusting skb's tail pointer

Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Nikita V. Shirokov 2018-04-17 21:42:14 -07:00 committed by Daniel Borkmann
parent b32cc5b9a3
commit 198d83bb3b
1 changed files with 9 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

10
net/core/dev.c
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@ -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: