[1/2] xdp: i40e: ixgbe: ixgbevf: not flip rx buffer for copy mode xdp

i40e/ixgbe/ixgbevf_rx_buffer_flip in copy mode xdp can lead to
data corruption, like the following flow:

   1. first skb is not for xsk, and forwarded to another device
      or socket queue
   2. seconds skb is for xsk, copy data to xsk memory, and page
      of skb->data is released
   3. rx_buff is reusable since only first skb is in it, but
      *_rx_buffer_flip will make that page_offset is set to
      first skb data
   4. then reuse rx buffer, first skb which still is living
      will be corrupted.

so add flags in xdp struct, to report xdp's data status, then
driver has knowledge whether to flip rx buffer

Fixes: c497176cb2e4 ("xsk: add Rx receive functions and poll support")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Dongsheng Rong <rongdongsheng@baidu.com>
---
 drivers/net/ethernet/intel/i40e/i40e_txrx.c       | 5 ++++-
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c     | 5 ++++-
 drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 5 ++++-
 include/net/xdp.h                                 | 3 +++
 net/xdp/xsk.c                                     | 4 +++-
 5 files changed, 18 insertions(+), 4 deletions(-)

On Fri, Jul 17, 2020 at 8:24 AM Li RongQing <lirongqing@baidu.com> wrote:
>
> i40e/ixgbe/ixgbevf_rx_buffer_flip in copy mode xdp can lead to
> data corruption, like the following flow:
>
>    1. first skb is not for xsk, and forwarded to another device
>       or socket queue
>    2. seconds skb is for xsk, copy data to xsk memory, and page
>       of skb->data is released
>    3. rx_buff is reusable since only first skb is in it, but
>       *_rx_buffer_flip will make that page_offset is set to
>       first skb data
>    4. then reuse rx buffer, first skb which still is living
>       will be corrupted.
>
> so add flags in xdp struct, to report xdp's data status, then
> driver has knowledge whether to flip rx buffer
>
> Fixes: c497176cb2e4 ("xsk: add Rx receive functions and poll support")
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> Signed-off-by: Dongsheng Rong <rongdongsheng@baidu.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_txrx.c       | 5 ++++-
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c     | 5 ++++-
>  drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 5 ++++-
>  include/net/xdp.h                                 | 3 +++
>  net/xdp/xsk.c                                     | 4 +++-
>  5 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> index b3836092c327..51fa6f86f917 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> @@ -2376,6 +2376,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
>
>                 /* retrieve a buffer from the ring */
>                 if (!skb) {
> +                       xdp.flags = 0;
>                         xdp.data = page_address(rx_buffer->page) +
>                                    rx_buffer->page_offset;
>                         xdp.data_meta = xdp.data;
> @@ -2394,7 +2395,9 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget)
>
>                         if (xdp_res & (I40E_XDP_TX | I40E_XDP_REDIR)) {
>                                 xdp_xmit |= xdp_res;
> -                               i40e_rx_buffer_flip(rx_ring, rx_buffer, size);
> +
> +                               if (!(xdp.flags & XDP_DATA_RELEASED))
> +                                       i40e_rx_buffer_flip(rx_ring, rx_buffer, size);
>                         } else {
>                                 rx_buffer->pagecnt_bias++;
>                         }
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index a8bf941c5c29..9e44a7e1d91c 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -2333,6 +2333,7 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
>
>                 /* retrieve a buffer from the ring */
>                 if (!skb) {
> +                       xdp.flags = 0;
>                         xdp.data = page_address(rx_buffer->page) +
>                                    rx_buffer->page_offset;
>                         xdp.data_meta = xdp.data;
> @@ -2351,7 +2352,9 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,
>
>                         if (xdp_res & (IXGBE_XDP_TX | IXGBE_XDP_REDIR)) {
>                                 xdp_xmit |= xdp_res;
> -                               ixgbe_rx_buffer_flip(rx_ring, rx_buffer, size);
> +
> +                               if (!(xdp.flags & XDP_DATA_RELEASED))
> +                                       ixgbe_rx_buffer_flip(rx_ring, rx_buffer, size);
>                         } else {
>                                 rx_buffer->pagecnt_bias++;
>                         }
> diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> index a39e2cb384dd..1c1a8b6a5dcf 100644
> --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> @@ -1168,6 +1168,7 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector,
>
>                 /* retrieve a buffer from the ring */
>                 if (!skb) {
> +                       xdp.flags = 0;
>                         xdp.data = page_address(rx_buffer->page) +
>                                    rx_buffer->page_offset;
>                         xdp.data_meta = xdp.data;
> @@ -1184,7 +1185,9 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector *q_vector,
>                 if (IS_ERR(skb)) {
>                         if (PTR_ERR(skb) == -IXGBEVF_XDP_TX) {
>                                 xdp_xmit = true;
> -                               ixgbevf_rx_buffer_flip(rx_ring, rx_buffer,
> +
> +                               if (!(xdp.flags & XDP_DATA_RELEASED))
> +                                       ixgbevf_rx_buffer_flip(rx_ring, rx_buffer,
>                                                        size);
>                         } else {
>                                 rx_buffer->pagecnt_bias++;
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index 609f819ed08b..6b32a01ade19 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -47,6 +47,8 @@ enum xdp_mem_type {
>  #define XDP_XMIT_FLUSH         (1U << 0)       /* doorbell signal consumer */
>  #define XDP_XMIT_FLAGS_MASK    XDP_XMIT_FLUSH
>
> +#define XDP_DATA_RELEASED (1U << 0)
> +
>  struct xdp_mem_info {
>         u32 type; /* enum xdp_mem_type, but known size type */
>         u32 id;
> @@ -73,6 +75,7 @@ struct xdp_buff {
>         struct xdp_rxq_info *rxq;
>         struct xdp_txq_info *txq;
>         u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
> +       u32 flags;

RongQing,

Sorry that I was not clear enough. Could you please submit the simple
patch you had, the one that only tests for the memory type.

if (xdp->rxq->mem.type != MEM_TYPE_XSK_BUFF_POOL)
      i40e_rx_buffer_flip(rx_ring, rx_buffer, size);

I do not think that adding a flags field in the xdp_mem_info to fix an
Intel driver problem will be hugely popular. The struct is also meant
to contain long lived information, not things that will frequently
change.

Thank you: Magnus

>  };
>
>  /* Reserve memory area at end-of data area.
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index b6c0f08bd80d..2c4c5c16660b 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -172,8 +172,10 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len,
>                 xsk_buff_free(xsk_xdp);
>                 return err;
>         }
> -       if (explicit_free)
> +       if (explicit_free) {
>                 xdp_return_buff(xdp);
> +               xdp->flags |= XDP_DATA_RELEASED;
> +       }
>         return 0;
>  }
>
> --
> 2.16.2
>
> _______________________________________________
> Intel-wired-lan mailing list
> Intel-wired-lan@osuosl.org
> https://lists.osuosl.org/mailman/listinfo/intel-wired-lan

> -----邮件原件-----
> 发件人: Magnus Karlsson [mailto:magnus.karlsson@gmail.com]
> 发送时间: 2020年7月20日 15:21
> 收件人: Li,Rongqing <lirongqing@baidu.com>
> 抄送: Network Development <netdev@vger.kernel.org>; intel-wired-lan
> <intel-wired-lan@lists.osuosl.org>; Karlsson, Magnus
> <magnus.karlsson@intel.com>; Björn Töpel <bjorn.topel@intel.com>
> 主题: Re: [Intel-wired-lan] [PATCH 1/2] xdp: i40e: ixgbe: ixgbevf: not flip rx
> buffer for copy mode xdp
> 
> On Fri, Jul 17, 2020 at 8:24 AM Li RongQing <lirongqing@baidu.com> wrote:
> >
> > i40e/ixgbe/ixgbevf_rx_buffer_flip in copy mode xdp can lead to data
> > corruption, like the following flow:
> >
> >    1. first skb is not for xsk, and forwarded to another device
> >       or socket queue
> >    2. seconds skb is for xsk, copy data to xsk memory, and page
> >       of skb->data is released
> >    3. rx_buff is reusable since only first skb is in it, but
> >       *_rx_buffer_flip will make that page_offset is set to
> >       first skb data
> >    4. then reuse rx buffer, first skb which still is living
> >       will be corrupted.
e, but known size type */
> >         u32 id;
> > @@ -73,6 +75,7 @@ struct xdp_buff {
> >         struct xdp_rxq_info *rxq;
> >         struct xdp_txq_info *txq;
> >         u32 frame_sz; /* frame size to deduce data_hard_end/reserved
> > tailroom*/
> > +       u32 flags;
> 
> RongQing,
> 
> Sorry that I was not clear enough. Could you please submit the simple patch
> you had, the one that only tests for the memory type.
> 
> if (xdp->rxq->mem.type != MEM_TYPE_XSK_BUFF_POOL)
>       i40e_rx_buffer_flip(rx_ring, rx_buffer, size);
> 
> I do not think that adding a flags field in the xdp_mem_info to fix an Intel driver
> problem will be hugely popular. The struct is also meant to contain long lived
> information, not things that will frequently change.
> 


Thank you Magnus

My original suggestion is wrong , it should be following

if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
       i40e_rx_buffer_flip(rx_ring, rx_buffer, size);


but I feel it is not enough to only check mem.type, it must ensure that map_type is BPF_MAP_TYPE_XSKMAP ? but it is not expose. 

other maptype, like BPF_MAP_TYPE_DEVMAP,  and if mem.type is MEM_TYPE_PAGE_SHARED, not flip the rx buffer, will cause data corruption.


-Li