l2tp: take PMTU from tunnel UDP socket

When l2tp driver tries to get PMTU for the tunnel destination, it uses
the pointer to struct sock that represents PPPoX socket, while it
should use the pointer that represents UDP socket of the tunnel.

Signed-off-by: Dmitry Petukhov <dmgenp@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: core: don't account for udp header size when computing seglen

In case of tcp, gso_size contains the tcpmss.

For UFO (udp fragmentation offloading) skbs, gso_size is the fragment
payload size, i.e. we must not account for udp header size.

Otherwise, when using virtio drivers, a to-be-forwarded UFO GSO packet
will be needlessly fragmented in the forward path, because we think its
individual segments are too large for the outgoing link.

Fixes: fe6cc55f3a9a053 ("net: ip, ipv6: handle gso skbs in forwarding path")
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv6: Limit mtu to 65575 bytes

Francois reported that setting big mtu on loopback device could prevent
tcp sessions making progress.

We do not support (yet ?) IPv6 Jumbograms and cook corrupted packets.

We must limit the IPv6 MTU to (65535 + 40) bytes in theory.

Tested:

ifconfig lo mtu 70000
netperf -H ::1

Before patch : Throughput :   0.05 Mbits

After patch : Throughput : 35484 Mbits

Reported-by: Francois WELLENREITER <f.wellenreiter@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
filter: prevent nla extensions to peek beyond the end
 of the message
rtnetlink: Only supply IFLA_VF_PORTS information when RTEXT_FILTER_VF is set

Since 115c9b81928360d769a76c632bae62d15206a94a (rtnetlink: Fix problem with
buffer allocation), RTM_NEWLINK messages only contain the IFLA_VFINFO_LIST
attribute if they were solicited by a GETLINK message containing an
IFLA_EXT_MASK attribute with the RTEXT_FILTER_VF flag.

That was done because some user programs broke when they received more data
than expected - because IFLA_VFINFO_LIST contains information for each VF
it can become large if there are many VFs.

However, the IFLA_VF_PORTS attribute, supplied for devices which implement
ndo_get_vf_port (currently the 'enic' driver only), has the same problem.
It supplies per-VF information and can therefore become large, but it is
not currently conditional on the IFLA_EXT_MASK value.

Worse, it interacts badly with the existing EXT_MASK handling.  When
IFLA_EXT_MASK is not supplied, the buffer for netlink replies is fixed at
NLMSG_GOODSIZE.  If the information for IFLA_VF_PORTS exceeds this, then
rtnl_fill_ifinfo() returns -EMSGSIZE on the first message in a packet.
netlink_dump() will misinterpret this as having finished the listing and
omit data for this interface and all subsequent ones.  That can cause
getifaddrs(3) to enter an infinite loop.

This patch addresses the problem by only supplying IFLA_VF_PORTS when
IFLA_EXT_MASK is supplied with the RTEXT_FILTER_VF flag set.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp_cubic: fix the range of delayed_ack

commit b9f47a3aaeab (tcp_cubic: limit delayed_ack ratio to prevent
divide error) try to prevent divide error, but there is still a little
chance that delayed_ack can reach zero. In case the param cnt get
negative value, then ratio+cnt would overflow and may happen to be zero.
As a result, min(ratio, ACK_RATIO_LIMIT) will calculate to be zero.

In some old kernels, such as 2.6.32, there is a bug that would
pass negative param, which then ultimately leads to this divide error.

commit 5b35e1e6e9c (tcp: fix tcp_trim_head() to adjust segment count
with skb MSS) fixed the negative param issue. However,
it's safe that we fix the range of delayed_ack as well,
to make sure we do not hit a divide by zero.

CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Liu Yu <allanyuliu@tencent.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: ipv4: ip_forward: fix inverted local_df test

local_df means 'ignore DF bit if set', so if its set we're
allowed to perform ip fragmentation.

This wasn't noticed earlier because the output path also drops such skbs
(and emits needed icmp error) and because netfilter ip defrag did not
set local_df until couple of days ago.

Only difference is that DF-packets-larger-than MTU now discarded
earlier (f.e. we avoid pointless netfilter postrouting trip).

While at it, drop the repeated test ip_exceeds_mtu, checking it once
is enough...

Fixes: fe6cc55f3a9 ("net: ip, ipv6: handle gso skbs in forwarding path")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: fib_semantics: increment fib_info_cnt after fib_info allocation

Increment fib_info_cnt in fib_create_info() right after successfuly
alllocating fib_info structure, overwise fib_metrics allocation failure
leads to fib_info_cnt incorrectly decremented in free_fib_info(), called
on error path from fib_create_info().

Signed-off-by: Sergey Popovich <popovich_sergei@mail.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
act_mirred: do not drop packets when fails to mirror it

We drop packet unconditionally when we fail to mirror it. This is not intended
in some cases. Consdier for kvm guest, we may mirror the traffic of the bridge
to a tap device used by a VM. When kernel fails to mirror the packet in
conditions such as when qemu crashes or stop polling the tap, it's hard for the
management software to detect such condition and clean the the mirroring
before. This would lead all packets to the bridge to be dropped and break the
netowrk of other virtual machines.

To solve the issue, the patch does not drop packets when kernel fails to mirror
it, and only drop the redirected packets.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ipv4: initialise the itag variable in __mkroute_input
 skb: Add inline helper for getting the skb end offset
 from head
net-gro: reset skb->truesize in napi_reuse_skb()

Recycling skb always had been very tough...

This time it appears GRO layer can accumulate skb->truesize
adjustments made by drivers when they attach a fragment to skb.

skb_gro_receive() can only subtract from skb->truesize the used part
of a fragment.

I spotted this problem seeing TcpExtPruneCalled and
TcpExtTCPRcvCollapsed that were unexpected with a recent kernel, where
TCP receive window should be sized properly to accept traffic coming
from a driver not overshooting skb->truesize.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>