* ipv4: Constrain UFO fragment sizes to multiples of 8 bytes
@ 2016-06-06 20:24 Steven Caron
2016-06-09 4:59 ` Cong Wang
0 siblings, 1 reply; 3+ messages in thread
From: Steven Caron @ 2016-06-06 20:24 UTC (permalink / raw)
To: linux-kernel; +Cc: Steven Caron
Back in 2011, Bill Sommerfeld submitted an update to prevent ip_append_data to create malformed packets:
Commit: d9be4f7a6f5a8da3133b832eca41c3591420b1ca
Now we're finding that we need to apply the same logic to ip_append_page to get nfs to work with udp when UFO is enabled:
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 124bf0a..21ec54e 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1239,7 +1239,7 @@ ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
if (skb->ip_summed != CHECKSUM_PARTIAL)
return -EOPNOTSUPP;
- skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
+ skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
}
cork->length += size;
We're wondering if this is something that was missed by that initial update of if there is a reason for ip_append_page to behave differently.
We realize that there might not be a lot of people who care about running NFS over UDP, but the issue is still reproducible in the latest kernel.
I include some additional info in case anyone is interested in reproducing with their own setup.
Using two VMs connected with a bridge, one using e1000, the other virtio.
Test done using FInnix 111 (kernel 4.0) as the guest.
# On each VM export which allows NFSv3
mount -t tmpfs tmps /export
vi /etc/exports
/export *(rw,no_subtree_check,fsid=0,insecure) # insecure to allow NFSv3
/etc/init.d/rpcbind start
/etc/init.d/nfs-kernel-server start
# On each VM mount each other exported as UDP
mkdir /mnt/import
mount 169.254.208.5:/export /mnt/import -o vers=3,udp,rsize=16394,wsize=16384,soft,nolock # soft to avoid permanent hang
# Using common MTU of 1500 on both VMs
ifconfig eth0 mtu 1500
# On the one with UFO=on (virtio):
dd if=/dev/zero count=1 bs=16384 of=/mnt/import/test
# Work as expected
# On the one with UFO=on (virtio)
dd if=/dev/zero count=1 bs=16384 of=/export/test
# On the one with UFO=off (e1000)
dd if=/mnt/import/test count=1 bs=16384 of=/dev/null
# Work as expected
# Using non-standard MTU of 1496 of both VMs
ifconfig eth0 mtu 1496
# On the one with UFO=on (virtio)
dd if=/dev/zero count=1 bs=16384 of=/mnt/import/test
# get Input/output error
# On the one with UFO=on (virtio)
dd if=/dev/zero count=1 bs=16384 of=/export/test
# On the one with UFO=off (e1000)
dd if=/mnt/import/test count=1 bs=1496 of=/dev/null
# get Input/output error
Regards,
Steven Caron
Designer, GENWare
500 Palladium Dr. Suite 2100| Ottawa ON, K2V 1C2
office: +1.343.883.2345 | steven.caron.genband.com
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: ipv4: Constrain UFO fragment sizes to multiples of 8 bytes
2016-06-06 20:24 ipv4: Constrain UFO fragment sizes to multiples of 8 bytes Steven Caron
@ 2016-06-09 4:59 ` Cong Wang
2016-06-09 22:39 ` Hannes Frederic Sowa
0 siblings, 1 reply; 3+ messages in thread
From: Cong Wang @ 2016-06-09 4:59 UTC (permalink / raw)
To: Steven Caron; +Cc: linux-kernel, Linux Kernel Network Developers
(Cc'ing netdev...)
On Mon, Jun 6, 2016 at 1:24 PM, Steven Caron <steven.caron@genband.com> wrote:
> Back in 2011, Bill Sommerfeld submitted an update to prevent ip_append_data to create malformed packets:
> Commit: d9be4f7a6f5a8da3133b832eca41c3591420b1ca
>
> Now we're finding that we need to apply the same logic to ip_append_page to get nfs to work with udp when UFO is enabled:
>
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 124bf0a..21ec54e 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -1239,7 +1239,7 @@ ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
> if (skb->ip_summed != CHECKSUM_PARTIAL)
> return -EOPNOTSUPP;
>
> - skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
> + skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
> skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
> }
> cork->length += size;
>
> We're wondering if this is something that was missed by that initial update of if there is a reason for ip_append_page to behave differently.
>
> We realize that there might not be a lot of people who care about running NFS over UDP, but the issue is still reproducible in the latest kernel.
>
> I include some additional info in case anyone is interested in reproducing with their own setup.
>
> Using two VMs connected with a bridge, one using e1000, the other virtio.
> Test done using FInnix 111 (kernel 4.0) as the guest.
>
> # On each VM export which allows NFSv3
> mount -t tmpfs tmps /export
> vi /etc/exports
> /export *(rw,no_subtree_check,fsid=0,insecure) # insecure to allow NFSv3
> /etc/init.d/rpcbind start
> /etc/init.d/nfs-kernel-server start
>
> # On each VM mount each other exported as UDP
> mkdir /mnt/import
> mount 169.254.208.5:/export /mnt/import -o vers=3,udp,rsize=16394,wsize=16384,soft,nolock # soft to avoid permanent hang
>
> # Using common MTU of 1500 on both VMs
> ifconfig eth0 mtu 1500
>
> # On the one with UFO=on (virtio):
> dd if=/dev/zero count=1 bs=16384 of=/mnt/import/test
> # Work as expected
>
> # On the one with UFO=on (virtio)
> dd if=/dev/zero count=1 bs=16384 of=/export/test
> # On the one with UFO=off (e1000)
> dd if=/mnt/import/test count=1 bs=16384 of=/dev/null
> # Work as expected
>
>
> # Using non-standard MTU of 1496 of both VMs
> ifconfig eth0 mtu 1496
>
> # On the one with UFO=on (virtio)
> dd if=/dev/zero count=1 bs=16384 of=/mnt/import/test
> # get Input/output error
>
> # On the one with UFO=on (virtio)
> dd if=/dev/zero count=1 bs=16384 of=/export/test
> # On the one with UFO=off (e1000)
> dd if=/mnt/import/test count=1 bs=1496 of=/dev/null
> # get Input/output error
>
> Regards,
>
> Steven Caron
> Designer, GENWare
> 500 Palladium Dr. Suite 2100| Ottawa ON, K2V 1C2
> office: +1.343.883.2345 | steven.caron.genband.com
>
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: ipv4: Constrain UFO fragment sizes to multiples of 8 bytes
2016-06-09 4:59 ` Cong Wang
@ 2016-06-09 22:39 ` Hannes Frederic Sowa
0 siblings, 0 replies; 3+ messages in thread
From: Hannes Frederic Sowa @ 2016-06-09 22:39 UTC (permalink / raw)
To: Cong Wang, Steven Caron; +Cc: linux-kernel, Linux Kernel Network Developers
On 09.06.2016 06:59, Cong Wang wrote:
> (Cc'ing netdev...)
>
> On Mon, Jun 6, 2016 at 1:24 PM, Steven Caron <steven.caron@genband.com> wrote:
>> Back in 2011, Bill Sommerfeld submitted an update to prevent ip_append_data to create malformed packets:
>> Commit: d9be4f7a6f5a8da3133b832eca41c3591420b1ca
>>
>> Now we're finding that we need to apply the same logic to ip_append_page to get nfs to work with udp when UFO is enabled:
Uhh, absolutely for the same reason as described in the referred commit.
Can you send a patch?
Thanks,
Hannes
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-06-09 22:39 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2016-06-06 20:24 ipv4: Constrain UFO fragment sizes to multiples of 8 bytes Steven Caron
2016-06-09 4:59 ` Cong Wang
2016-06-09 22:39 ` Hannes Frederic Sowa
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