From: "Nikita V. Shirokov" <tehnerd@tehnerd.com>
To: David Ahern <dsahern@gmail.com>
Cc: Jason Wang <jasowang@redhat.com>,
daniel@iogearbox.net,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: XDP breakage with virtio due to 6870de435b90c083ae0f3f7f341287976ef56f03
Date: Sun, 22 Apr 2018 17:55:03 -0700 [thread overview]
Message-ID: <20180423005503.GA8140@maindev> (raw)
In-Reply-To: <f50aa641-09a7-4a08-498c-e7aa6ac50cc6@gmail.com>
On Sun, Apr 22, 2018 at 04:47:48PM -0600, David Ahern wrote:
> This commit breaks my FIB forwarding program:
>
> commit 6870de435b90c083ae0f3f7f341287976ef56f03
> Author: Nikita V. Shirokov <tehnerd@tehnerd.com>
> Date: Tue Apr 17 21:42:20 2018 -0700
>
> bpf: make virtio compatible w/ bpf_xdp_adjust_tail
>
> 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 virtio driver we need to adjust XDP_PASS handling by recalculating
> length of the packet if it was passed to the TCP/IP stack
>
> Reviewed-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
>
> ###
>
> Some of the packets (e.g., ARP or those without a resolved neighbor) are
> passed to the networking stack. What shows up are clearly broken packets:
>
> # tcpdump -n -i eth1
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on eth1, link-type EN10MB (Ethernet), capture size 262144 bytes
> 15:45:29.693238 [|ARP]
> 0x0000: 0001 0800 0604 0001 42c0 ce2f 3fa9 0a64 ........B../?..d
> 15:45:30.710327 [|ARP]
> 0x0000: 0001 0800 0604 0001 42c0 ce2f 3fa9 0a64 ........B../?..d
> 15:45:31.734296 [|ARP]
> 0x0000: 0001 0800 0604 0001 42c0 ce2f 3fa9 0a64 ........B../?..d
> 15:45:32.908720 IP6 truncated-ip6 - 12 bytes
> missing!fe80::40c0:ceff:fe2f:3fa9 > ff02::1:ff00:2: ICMP6, neighbor
> solicitation[|icmp6]
> 15:45:33.910530 IP6 truncated-ip6 - 12 bytes missing!2001:db8:1::64 >
> ff02::1:ff00:2: ICMP6, neighbor solicitation[|icmp6]
> 15:45:34.934437 IP6 truncated-ip6 - 12 bytes missing!2001:db8:1::64 >
> ff02::1:ff00:2: ICMP6, neighbor solicitation[|icmp6]
> 15:45:35.958394 IP6 truncated-ip6 - 12 bytes missing!2001:db8:1::64 >
> ff02::1:ff00:2: ICMP6, neighbor solicitation[|icmp6]
>
> Reverting the mentioned patch fixes the problem.
Hi, David.
thanks for reporting this. looks like in my calculation i've missed
vi->hdr_len during new lengths calculation (it was len = xdp->data_end -
xdp->data; but also shouldbe +vi->hdr_len). will run few more tests
before sending a fix.
prev parent reply other threads:[~2018-04-23 0:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-22 22:47 XDP breakage with virtio due to 6870de435b90c083ae0f3f7f341287976ef56f03 David Ahern
2018-04-23 0:55 ` Nikita V. Shirokov [this message]
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