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bpf, xdp, i40e: fix i40e_build_skb skb reserve and truesize

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Using skb_reserve(skb, I40E_SKB_PAD + (xdp->data - xdp->data_hard_start))
is clearly wrong since I40E_SKB_PAD already points to the offset where
the original xdp->data was sitting since xdp->data_hard_start is defined
as xdp->data - i40e_rx_offset(rx_ring) where latter offsets to I40E_SKB_PAD
when build skb is used.

However, also before cc5b114dcf ("bpf, i40e: add meta data support")
this seems broken since bpf_xdp_adjust_head() helper could have been used
to alter headroom and enlarge / shrink the frame and with that the assumption
that the xdp->data remains unchanged does not hold and would push a bogus
packet to upper stack.

ixgbe got this right in 9247080816 ("ixgbe: add XDP support for pass and
drop actions"). In any case, fix it by removing the I40E_SKB_PAD from both
skb_reserve() and truesize calculation.

Fixes: cc5b114dcf ("bpf, i40e: add meta data support")
Fixes: 0c8493d90b ("i40e: add XDP support for pass and drop actions")
Reported-by: Keith Busch <keith.busch@linux.intel.com>
Reported-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Björn Töpel <bjorn.topel@intel.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Tested-by: Keith Busch <keith.busch@linux.intel.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2018-06-19 14:33:54 -07:00 committed by David S. Miller
parent d563e7a2ff
commit c51818d5b7
1 changed files with 3 additions and 4 deletions
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7
drivers/net/ethernet/intel/i40e/i40e_txrx.c
View File

@ -2103,9 +2103,8 @@ static struct sk_buff *i40e_build_skb(struct i40e_ring *rx_ring,
unsigned int truesize = i40e_rx_pg_size(rx_ring) / 2;
#else
unsigned int truesize = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) +
SKB_DATA_ALIGN(I40E_SKB_PAD +
(xdp->data_end -
xdp->data_hard_start));
SKB_DATA_ALIGN(xdp->data_end -
xdp->data_hard_start);
#endif
struct sk_buff *skb;
@ -2124,7 +2123,7 @@ static struct sk_buff *i40e_build_skb(struct i40e_ring *rx_ring,
return NULL;
/* update pointers within the skb to store the data */
skb_reserve(skb, I40E_SKB_PAD + (xdp->data - xdp->data_hard_start));
skb_reserve(skb, xdp->data - xdp->data_hard_start);
__skb_put(skb, xdp->data_end - xdp->data);
if (metasize)
skb_metadata_set(skb, metasize);