linux.git/net/core/skbuff.c, branch v3.10.76

net: Correctly set segment mac_len in skb_segment().

2014-08-14T01:24:15+00:00

[ Upstream commit fcdfe3a7fa4cb74391d42b6a26dc07c20dab1d82 ]

When performing segmentation, the mac_len value is copied right
out of the original skb.  However, this value is not always set correctly
(like when the packet is VLAN-tagged) and we'll end up copying a bad
value.

One way to demonstrate this is to configure a VM which tags
packets internally and turn off VLAN acceleration on the forwarding
bridge port.  The packets show up corrupt like this:
16:18:24.985548 52:54:00:ab:be:25 > 52:54:00:26:ce:a3, ethertype 802.1Q
(0x8100), length 1518: vlan 100, p 0, ethertype 0x05e0,
        0x0000:  8cdb 1c7c 8cdb 0064 4006 b59d 0a00 6402 ...|...d@.....d.
        0x0010:  0a00 6401 9e0d b441 0a5e 64ec 0330 14fa ..d....A.^d..0..
        0x0020:  29e3 01c9 f871 0000 0101 080a 000a e833)....q.........3
        0x0030:  000f 8c75 6e65 7470 6572 6600 6e65 7470 ...unetperf.netp
        0x0040:  6572 6600 6e65 7470 6572 6600 6e65 7470 erf.netperf.netp
        0x0050:  6572 6600 6e65 7470 6572 6600 6e65 7470 erf.netperf.netp
        0x0060:  6572 6600 6e65 7470 6572 6600 6e65 7470 erf.netperf.netp
        ...

This also leads to awful throughput as GSO packets are dropped and
cause retransmissions.

The solution is to set the mac_len using the values already available
in then new skb.  We've already adjusted all of the header offset, so we
might as well correctly figure out the mac_len using skb_reset_mac_len().
After this change, packets are segmented correctly and performance
is restored.

CC: Eric Dumazet 
Signed-off-by: Vlad Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

skbuff: skb_segment: orphan frags before copying

2014-07-01T03:09:45+00:00

commit 1fd819ecb90cc9b822cd84d3056ddba315d3340f upstream.

skb_segment copies frags around, so we need
to copy them carefully to avoid accessing
user memory after reporting completion to userspace
through a callback.

skb_segment doesn't normally happen on datapath:
TSO needs to be disabled - so disabling zero copy
in this case does not look like a big deal.

Signed-off-by: Michael S. Tsirkin 
Acked-by: Herbert Xu 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2.  As skb_segment() only supports page-frags *or* a
  frag list, there is no need for the additional frag_skb pointer or the
  preparatory renaming.]
Signed-off-by: Ben Hutchings 
Cc: Eddie Chapman  # backported to 3.10
Signed-off-by: Greg Kroah-Hartman

net: core: don't account for udp header size when computing seglen

2014-05-31T04:52:14+00:00

[ Upstream commit 6d39d589bb76ee8a1c6cde6822006ae0053decff ]

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 
Reported-by: Tobias Brunner 
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: add and use skb_gso_transport_seglen()

2014-03-07T05:30:05+00:00

commit de960aa9ab4decc3304959f69533eef64d05d8e8 upstream.

[ no skb_gso_seglen helper in 3.10, leave tbf alone ]

This moves part of Eric Dumazets skb_gso_seglen helper from tbf sched to
skbuff core so it may be reused by upcoming ip forwarding path patch.

Signed-off-by: Florian Westphal 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

fuse: fix pipe_buf_operations

2014-02-13T21:47:59+00:00

commit 28a625cbc2a14f17b83e47ef907b2658576a32aa upstream.

Having this struct in module memory could Oops when if the module is
unloaded while the buffer still persists in a pipe.

Since sock_pipe_buf_ops is essentially the same as fuse_dev_pipe_buf_steal
merge them into nosteal_pipe_buf_ops (this is the same as
default_pipe_buf_ops except stealing the page from the buffer is not
allowed).

Reported-by: Al Viro 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

net: Loosen constraints for recalculating checksum in skb_segment()

2014-01-15T23:28:50+00:00

[ Upstream commit 1cdbcb7957cf9e5f841dbcde9b38fd18a804208b ]

This is a generic solution to resolve a specific problem that I have observed.

If the encapsulation of an skb changes then ability to offload checksums
may also change. In particular it may be necessary to perform checksumming
in software.

An example of such a case is where a non-GRE packet is received but
is to be encapsulated and transmitted as GRE.

Another example relates to my proposed support for for packets
that are non-MPLS when received but MPLS when transmitted.

The cost of this change is that the value of the csum variable may be
checked when it previously was not. In the case where the csum variable is
true this is pure overhead. In the case where the csum variable is false it
leads to software checksumming, which I believe also leads to correct
checksums in transmitted packets for the cases described above.

Further analysis:

This patch relies on the return value of can_checksum_protocol()
being correct and in turn the return value of skb_network_protocol(),
used to provide the protocol parameter of can_checksum_protocol(),
being correct. It also relies on the features passed to skb_segment()
and in turn to can_checksum_protocol() being correct.

I believe that this problem has not been observed for VLANs because it
appears that almost all drivers, the exception being xgbe, set
vlan_features such that that the checksum offload support for VLAN packets
is greater than or equal to that of non-VLAN packets.

I wonder if the code in xgbe may be an oversight and the hardware does
support checksumming of VLAN packets.  If so it may be worth updating the
vlan_features of the driver as this patch will force such checksums to be
performed in software rather than hardware.

Signed-off-by: Simon Horman 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

netfilter: push reasm skb through instead of original frag skbs

2013-12-08T15:29:25+00:00

[ Upstream commit 6aafeef03b9d9ecf255f3a80ed85ee070260e1ae ]

Pushing original fragments through causes several problems. For example
for matching, frags may not be matched correctly. Take following
example:


On HOSTA do:
ip6tables -I INPUT -p icmpv6 -j DROP
ip6tables -I INPUT -p icmpv6 -m icmp6 --icmpv6-type 128 -j ACCEPT

and on HOSTB you do:
ping6 HOSTA -s2000    (MTU is 1500)

Incoming echo requests will be filtered out on HOSTA. This issue does
not occur with smaller packets than MTU (where fragmentation does not happen)


As was discussed previously, the only correct solution seems to be to use
reassembled skb instead of separete frags. Doing this has positive side
effects in reducing sk_buff by one pointer (nfct_reasm) and also the reams
dances in ipvs and conntrack can be removed.

Future plan is to remove net/ipv6/netfilter/nf_conntrack_reasm.c
entirely and use code in net/ipv6/reassembly.c instead.

Signed-off-by: Jiri Pirko 
Acked-by: Julian Anastasov 
Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

gre: fix a possible skb leak

2013-06-25T23:07:44+00:00

commit 68c331631143 ("v4 GRE: Add TCP segmentation offload for GRE")
added a possible skb leak, because it frees only the head of segment
list, in case a skb_linearize() call fails.

This patch adds a kfree_skb_list() helper to fix the bug.

Signed-off-by: Eric Dumazet 
Cc: Pravin B Shelar 
Cc: Daniel Borkmann 
Signed-off-by: David S. Miller

net: fix sk_buff head without data area

2013-06-05T00:26:49+00:00

Eric Dumazet spotted that we have to check skb->head instead
of skb->data as skb->head points to the beginning of the
data area of the skbuff. Similarly, we have to initialize the
skb->head pointer, not skb->data in __alloc_skb_head.

After this fix, netlink crashes in the release path of the
sk_buff, so let's fix that as well.

This bug was introduced in (0ebd0ac net: add function to
allocate sk_buff head without data area).

Reported-by: Eric Dumazet 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: David S. Miller

packet: tx timestamping on tpacket ring

2013-04-25T05:22:22+00:00

When transmit timestamping is enabled at the socket level, record a
timestamp on packets written to a PACKET_TX_RING. Tx timestamps are
always looped to the application over the socket error queue. Software
timestamps are also written back into the packet frame header in the
packet ring.

Reported-by: Paul Chavent 
Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller