netdev - Re: [PATCH net-next] sfc: trace_xdp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 11 Nov 2019 17:38:29 +0000
From:   Arthur Fabre <afabre@...udflare.com>
To:     Edward Cree <ecree@...arflare.com>
Cc:     Solarflare linux maintainers <linux-net-drivers@...arflare.com>,
        Charles McLachlan <cmclachlan@...arflare.com>,
        Martin Habets <mhabets@...arflare.com>,
        David Miller <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        netdev <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        kernel-team <kernel-team@...udflare.com>
Subject: Re: [PATCH net-next] sfc: trace_xdp_exception on XDP failure

On Mon, Nov 11, 2019 at 5:27 PM Edward Cree <ecree@...arflare.com> wrote:
>
> On 11/11/2019 10:51, Arthur Fabre wrote:
> > diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
> > index a7d9841105d8..5bfe1f6112a1 100644
> > --- a/drivers/net/ethernet/sfc/rx.c
> > +++ b/drivers/net/ethernet/sfc/rx.c
> > @@ -678,6 +678,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
> >                                 "XDP is not possible with multiple receive fragments (%d)\n",
> >                                 channel->rx_pkt_n_frags);
> >               channel->n_rx_xdp_bad_drops++;
> > +             trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
> >               return false;
> >       }
> AIUI trace_xdp_exception() is improper here as we have not run
>  the XDP program (and xdp_act is thus uninitialised).
>
> The other three, below, appear to be correct.
> -Ed
>

Good point. Do you know under what conditions we'd end up with
"fragmented" packets? As far as I can tell this isn't IP
fragmentation?

On Mon, Nov 11, 2019 at 5:27 PM Edward Cree <ecree@...arflare.com> wrote:
>
> On 11/11/2019 10:51, Arthur Fabre wrote:
> > The sfc driver can drop packets processed with XDP, notably when running
> > out of buffer space on XDP_TX, or returning an unknown XDP action.
> > This increments the rx_xdp_bad_drops ethtool counter.
> >
> > Call trace_xdp_exception everywhere rx_xdp_bad_drops is incremented to
> > easily monitor this from userspace.
> >
> > This mirrors the behavior of other drivers.
> >
> > Signed-off-by: Arthur Fabre <afabre@...udflare.com>
> > ---
> >  drivers/net/ethernet/sfc/rx.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
> > index a7d9841105d8..5bfe1f6112a1 100644
> > --- a/drivers/net/ethernet/sfc/rx.c
> > +++ b/drivers/net/ethernet/sfc/rx.c
> > @@ -678,6 +678,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
> >                                 "XDP is not possible with multiple receive fragments (%d)\n",
> >                                 channel->rx_pkt_n_frags);
> >               channel->n_rx_xdp_bad_drops++;
> > +             trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
> >               return false;
> >       }
> AIUI trace_xdp_exception() is improper here as we have not run
>  the XDP program (and xdp_act is thus uninitialised).
>
> The other three, below, appear to be correct.
> -Ed
>
> >
> > @@ -724,6 +725,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
> >                               netif_err(efx, rx_err, efx->net_dev,
> >                                         "XDP TX failed (%d)\n", err);
> >                       channel->n_rx_xdp_bad_drops++;
> > +                     trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
> >               } else {
> >                       channel->n_rx_xdp_tx++;
> >               }
> > @@ -737,6 +739,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
> >                               netif_err(efx, rx_err, efx->net_dev,
> >                                         "XDP redirect failed (%d)\n", err);
> >                       channel->n_rx_xdp_bad_drops++;
> > +                     trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
> >               } else {
> >                       channel->n_rx_xdp_redirect++;
> >               }
> > @@ -746,6 +749,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
> >               bpf_warn_invalid_xdp_action(xdp_act);
> >               efx_free_rx_buffers(rx_queue, rx_buf, 1);
> >               channel->n_rx_xdp_bad_drops++;
> > +             trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
> >               break;
> >
> >       case XDP_ABORTED:
>