[Intel-wired-lan] [PATCH net/jkirsher] bpf, xdp, i40e: fix i40e_build_skb skb reserve and truesize
Daniel Borkmann
daniel at iogearbox.net
Wed Jun 13 09:04:36 UTC 2018
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 cc5b114dcf98 ("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 924708081629 ("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: cc5b114dcf98 ("bpf, i40e: add meta data support")
Fixes: 0c8493d90b6b ("i40e: add XDP support for pass and drop actions")
Reported-by: Keith Busch <keith.busch at linux.intel.com>
Reported-by: Toshiaki Makita <makita.toshiaki at lab.ntt.co.jp>
Signed-off-by: Daniel Borkmann <daniel at iogearbox.net>
Cc: Björn Töpel <bjorn.topel at intel.com>
Cc: John Fastabend <john.fastabend at gmail.com>
---
drivers/net/ethernet/intel/i40e/i40e_txrx.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 8ffb745..ed6dbcf 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -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);
--
2.9.5
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