* [PATCH] Constrain UFO fragment sizes to multiples of 8 bytes
@ 2011-07-20 1:22 Bill Sommerfeld
2011-07-20 1:30 ` Maciej Żenczykowski
0 siblings, 1 reply; 3+ messages in thread
From: Bill Sommerfeld @ 2011-07-20 1:22 UTC (permalink / raw)
To: David S. Miller
Cc: netdev, Tom Herbert, Maciej Żenczykowski, Bill Sommerfeld
Because the ip fragment offset field counts 8-byte chunks, ip
fragments other than the last must contain a multiple of 8 bytes of
payload. ip_ufo_append_data wasn't respecting this constraint and,
depending on the MTU and ip option sizes, could create malformed
non-final fragments.
Google-Bug-Id: 5009328
Signed-off-by: Bill Sommerfeld <wsommerfeld@google.com>
---
Note to reviewers: The first two hunks simply rename the "mtu"
parameter to "maxfraglen"; the real change is in the third hunk.
maxfraglen (the size of the largest non-final fragment which fits
inside mtu) is already computed for the non-UFO fragmentation path.
We saw this problem in a 2.6.34-based kernel with a bond device that
had UFO enabled (as a result of changeset d9f5950f90292f7c);
1742f183fc218798 rewrote netdev_increment_features to no longer force
on UFO. The MTU on this bond device was set to 1470; fragmented
datagrams were mangled, causing the receiver to get errors of the
form:
[506259.362640] UDP: short packet: From x.x.x.x:nnnn 1471/1469 to y.y.y.y:nnnn
net/ipv4/ip_output.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index be27e60..ccaaa85 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -734,7 +734,7 @@ static inline int ip_ufo_append_data(struct sock *sk,
int getfrag(void *from, char *to, int offset, int len,
int odd, struct sk_buff *skb),
void *from, int length, int hh_len, int fragheaderlen,
- int transhdrlen, int mtu, unsigned int flags)
+ int transhdrlen, int maxfraglen, unsigned int flags)
{
struct sk_buff *skb;
int err;
@@ -767,7 +767,7 @@ static inline int ip_ufo_append_data(struct sock *sk,
skb->csum = 0;
/* specify the length of each IP datagram fragment */
- skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
+ skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
__skb_queue_tail(queue, skb);
}
@@ -831,7 +831,7 @@ static int __ip_append_data(struct sock *sk,
(rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
err = ip_ufo_append_data(sk, queue, getfrag, from, length,
hh_len, fragheaderlen, transhdrlen,
- mtu, flags);
+ maxfraglen, flags);
if (err)
goto error;
return 0;
--
1.7.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] Constrain UFO fragment sizes to multiples of 8 bytes
2011-07-20 1:22 [PATCH] Constrain UFO fragment sizes to multiples of 8 bytes Bill Sommerfeld
@ 2011-07-20 1:30 ` Maciej Żenczykowski
2011-07-22 4:32 ` David Miller
0 siblings, 1 reply; 3+ messages in thread
From: Maciej Żenczykowski @ 2011-07-20 1:30 UTC (permalink / raw)
To: Bill Sommerfeld; +Cc: David S. Miller, netdev, Tom Herbert
Ack.
This should probably make it into all manner of stable branches.
On Tue, Jul 19, 2011 at 6:22 PM, Bill Sommerfeld <wsommerfeld@google.com> wrote:
> Because the ip fragment offset field counts 8-byte chunks, ip
> fragments other than the last must contain a multiple of 8 bytes of
> payload. ip_ufo_append_data wasn't respecting this constraint and,
> depending on the MTU and ip option sizes, could create malformed
> non-final fragments.
>
> Google-Bug-Id: 5009328
> Signed-off-by: Bill Sommerfeld <wsommerfeld@google.com>
> ---
>
> Note to reviewers: The first two hunks simply rename the "mtu"
> parameter to "maxfraglen"; the real change is in the third hunk.
> maxfraglen (the size of the largest non-final fragment which fits
> inside mtu) is already computed for the non-UFO fragmentation path.
>
> We saw this problem in a 2.6.34-based kernel with a bond device that
> had UFO enabled (as a result of changeset d9f5950f90292f7c);
> 1742f183fc218798 rewrote netdev_increment_features to no longer force
> on UFO. The MTU on this bond device was set to 1470; fragmented
> datagrams were mangled, causing the receiver to get errors of the
> form:
>
> [506259.362640] UDP: short packet: From x.x.x.x:nnnn 1471/1469 to y.y.y.y:nnnn
>
> net/ipv4/ip_output.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index be27e60..ccaaa85 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -734,7 +734,7 @@ static inline int ip_ufo_append_data(struct sock *sk,
> int getfrag(void *from, char *to, int offset, int len,
> int odd, struct sk_buff *skb),
> void *from, int length, int hh_len, int fragheaderlen,
> - int transhdrlen, int mtu, unsigned int flags)
> + int transhdrlen, int maxfraglen, unsigned int flags)
> {
> struct sk_buff *skb;
> int err;
> @@ -767,7 +767,7 @@ static inline int ip_ufo_append_data(struct sock *sk,
> skb->csum = 0;
>
> /* specify the length of each IP datagram fragment */
> - skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
> + skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
> skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
> __skb_queue_tail(queue, skb);
> }
> @@ -831,7 +831,7 @@ static int __ip_append_data(struct sock *sk,
> (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
> err = ip_ufo_append_data(sk, queue, getfrag, from, length,
> hh_len, fragheaderlen, transhdrlen,
> - mtu, flags);
> + maxfraglen, flags);
> if (err)
> goto error;
> return 0;
> --
> 1.7.3.1
>
>
--
Maciej A. Żenczykowski
Kernel Networking Developer @ Google
1600 Amphitheatre Parkway, Mountain View, CA 94043
tel: +1 (650) 253-0062
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Constrain UFO fragment sizes to multiples of 8 bytes
2011-07-20 1:30 ` Maciej Żenczykowski
@ 2011-07-22 4:32 ` David Miller
0 siblings, 0 replies; 3+ messages in thread
From: David Miller @ 2011-07-22 4:32 UTC (permalink / raw)
To: maze; +Cc: wsommerfeld, netdev, therbert
From: Maciej Żenczykowski <maze@google.com>
Date: Tue, 19 Jul 2011 18:30:22 -0700
> Ack.
> This should probably make it into all manner of stable branches.
Applied and queued up for -stable.
^ permalink raw reply [flat|nested] 3+ messages in thread
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