| Message ID | 1293284490-17114-1-git-send-email-xiaosuo@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Changli Gao <xiaosuo@gmail.com> Date: Sat, 25 Dec 2010 21:41:30 +0800 > Since nf_bridge_maybe_copy_header() may change the length of skb, > we should check the length of skb after it to handle the ppoe skbs. > > Signed-off-by: Changli Gao <xiaosuo@gmail.com> This is really strange. packet_length() subtracts VLAN_HLEN from the value it returns, so the correct fix seems to be to make this function handle the PPPOE case too. Otherwise I suspect you have many other functions to fix as well. I'm not applying this patch. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, Jan 1, 2011 at 3:10 AM, David Miller <davem@davemloft.net> wrote: > From: Changli Gao <xiaosuo@gmail.com> > Date: Sat, 25 Dec 2010 21:41:30 +0800 > >> Since nf_bridge_maybe_copy_header() may change the length of skb, >> we should check the length of skb after it to handle the ppoe skbs. >> >> Signed-off-by: Changli Gao <xiaosuo@gmail.com> > > This is really strange. > > packet_length() subtracts VLAN_HLEN from the value it returns, so the > correct fix seems to be to make this function handle the PPPOE case > too. > It is correct. The actual MTU of 802.1q frame is 4 bytes larger. For example, the MTU of ethernet is normally 1500, however the actual MTU of the 802.1Q is 1504. Please see this patch: http://git.kernel.org/?p=linux/kernel/git/davem/net-next-2.6.git;a=commitdiff;h=c893b8066c7bf6156e4d760e5acaf4c148e37190;hp=3c0fef0b7d36e5f8d3ea3731a8228102274e3c23 > Otherwise I suspect you have many other functions to fix as well. > > I'm not applying this patch. >
From: Changli Gao <xiaosuo@gmail.com> Date: Mon, 3 Jan 2011 18:44:59 +0800 > On Sat, Jan 1, 2011 at 3:10 AM, David Miller <davem@davemloft.net> wrote: >> From: Changli Gao <xiaosuo@gmail.com> >> Date: Sat, 25 Dec 2010 21:41:30 +0800 >> >>> Since nf_bridge_maybe_copy_header() may change the length of skb, >>> we should check the length of skb after it to handle the ppoe skbs. >>> >>> Signed-off-by: Changli Gao <xiaosuo@gmail.com> >> >> This is really strange. >> >> packet_length() subtracts VLAN_HLEN from the value it returns, so the >> correct fix seems to be to make this function handle the PPPOE case >> too. >> > > It is correct. The actual MTU of 802.1q frame is 4 bytes larger. For > example, the MTU of ethernet is normally 1500, however the actual MTU > of the 802.1Q is 1504. Yes, I understand this, but I don't see why packet_length() cannot simply account for PPPOE's encapsulation overhead just as it does for VLAN's special MTU considerations. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 03 Jan 2011 09:22:14 -0800 (PST) David Miller <davem@davemloft.net> wrote: > From: Changli Gao <xiaosuo@gmail.com> > Date: Mon, 3 Jan 2011 18:44:59 +0800 > > > On Sat, Jan 1, 2011 at 3:10 AM, David Miller <davem@davemloft.net> wrote: > >> From: Changli Gao <xiaosuo@gmail.com> > >> Date: Sat, 25 Dec 2010 21:41:30 +0800 > >> > >>> Since nf_bridge_maybe_copy_header() may change the length of skb, > >>> we should check the length of skb after it to handle the ppoe skbs. > >>> > >>> Signed-off-by: Changli Gao <xiaosuo@gmail.com> > >> > >> This is really strange. > >> > >> packet_length() subtracts VLAN_HLEN from the value it returns, so the > >> correct fix seems to be to make this function handle the PPPOE case > >> too. > >> > > > > It is correct. The actual MTU of 802.1q frame is 4 bytes larger. For > > example, the MTU of ethernet is normally 1500, however the actual MTU > > of the 802.1Q is 1504. > > Yes, I understand this, but I don't see why packet_length() cannot > simply account for PPPOE's encapsulation overhead just as it does for > VLAN's special MTU considerations. Because PPPOE happens afterwards and is not part the calculation. The check should be moved until after skb has reached final form.
From: Stephen Hemminger <shemminger@linux-foundation.org> Date: Mon, 3 Jan 2011 10:15:33 -0800 > On Mon, 03 Jan 2011 09:22:14 -0800 (PST) > David Miller <davem@davemloft.net> wrote: > >> From: Changli Gao <xiaosuo@gmail.com> >> Date: Mon, 3 Jan 2011 18:44:59 +0800 >> >> > On Sat, Jan 1, 2011 at 3:10 AM, David Miller <davem@davemloft.net> wrote: >> >> From: Changli Gao <xiaosuo@gmail.com> >> >> Date: Sat, 25 Dec 2010 21:41:30 +0800 >> >> >> >>> Since nf_bridge_maybe_copy_header() may change the length of skb, >> >>> we should check the length of skb after it to handle the ppoe skbs. >> >>> >> >>> Signed-off-by: Changli Gao <xiaosuo@gmail.com> >> >> >> >> This is really strange. >> >> >> >> packet_length() subtracts VLAN_HLEN from the value it returns, so the >> >> correct fix seems to be to make this function handle the PPPOE case >> >> too. >> >> >> > >> > It is correct. The actual MTU of 802.1q frame is 4 bytes larger. For >> > example, the MTU of ethernet is normally 1500, however the actual MTU >> > of the 802.1Q is 1504. >> >> Yes, I understand this, but I don't see why packet_length() cannot >> simply account for PPPOE's encapsulation overhead just as it does for >> VLAN's special MTU considerations. > > Because PPPOE happens afterwards and is not part the calculation. > The check should be moved until after skb has reached final form. That works for me. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jan 4, 2011 at 4:13 AM, David Miller <davem@davemloft.net> wrote: > From: Stephen Hemminger <shemminger@linux-foundation.org> >> >> Because PPPOE happens afterwards and is not part the calculation. >> The check should be moved until after skb has reached final form. > > That works for me. > So, is my patch acceptable?
From: Changli Gao <xiaosuo@gmail.com> Date: Wed, 5 Jan 2011 21:37:28 +0800 > On Tue, Jan 4, 2011 at 4:13 AM, David Miller <davem@davemloft.net> wrote: >> From: Stephen Hemminger <shemminger@linux-foundation.org> >>> >>> Because PPPOE happens afterwards and is not part the calculation. >>> The check should be moved until after skb has reached final form. >> >> That works for me. >> > > So, is my patch acceptable? Yes, I've applied it, thank you. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c index 2bd11ec..ee64287 100644 --- a/net/bridge/br_forward.c +++ b/net/bridge/br_forward.c @@ -41,17 +41,13 @@ static inline unsigned packet_length(const struct sk_buff *skb) int br_dev_queue_push_xmit(struct sk_buff *skb) { - /* drop mtu oversized packets except gso */ - if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) + /* ip_fragment doesn't copy the MAC header */ + if (nf_bridge_maybe_copy_header(skb) || + (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))) { kfree_skb(skb); - else { - /* ip_fragment doesn't copy the MAC header */ - if (nf_bridge_maybe_copy_header(skb)) - kfree_skb(skb); - else { - skb_push(skb, ETH_HLEN); - dev_queue_xmit(skb); - } + } else { + skb_push(skb, ETH_HLEN); + dev_queue_xmit(skb); } return 0;
Since nf_bridge_maybe_copy_header() may change the length of skb, we should check the length of skb after it to handle the ppoe skbs. Signed-off-by: Changli Gao <xiaosuo@gmail.com> --- net/bridge/br_forward.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html