linux-stable.git/net/core/skbuff.c, branch v3.13

net: clear local_df when passing skb between namespaces

2013-12-06T04:42:38+00:00

We must clear local_df when passing the skb between namespaces as the
packet is not local to the new namespace any more and thus may not get
fragmented by local rules. Fred Templin noticed that other namespaces
do fragment IPv6 packets while forwarding. Instead they should have send
back a PTB.

The same problem should be present when forwarding DF-IPv4 packets
between namespaces.

Reported-by: Templin, Fred L 
Signed-off-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller

gso: handle new frag_list of frags GRO packets

2013-11-21T19:11:50+00:00

Recently GRO started generating packets with frag_lists of frags.
This was not handled by GSO, thus leading to a crash.

Thankfully these packets are of a regular form and are easy to
handle.  This patch handles them in two ways.  For completely
non-linear frag_list entries, we simply continue to iterate over
the frag_list frags once we exhaust the normal frags.  For frag_list
entries with linear parts, we call pskb_trim on the first part
of the frag_list skb, and then process the rest of the frags in
the usual way.

This patch also kills a chunk of dead frag_list code that has
obviously never ever been run since it ends up generating a bogus
GSO-segmented packet with a frag_list entry.

Future work is planned to split super big packets into TSO
ones.

Fixes: 8a29111c7ca6 ("net: gro: allow to build full sized skb")
Reported-by: Christoph Paasch 
Reported-by: Jerry Chu 
Reported-by: Sander Eikelenboom 
Signed-off-by: Herbert Xu 
Signed-off-by: Eric Dumazet 
Tested-by: Sander Eikelenboom 
Tested-by: Eric Dumazet 
Signed-off-by: David S. Miller

netfilter: push reasm skb through instead of original frag skbs

2013-11-11T05:19:35+00:00

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

net: skbuff - kernel-doc fixes

2013-11-08T00:28:59+00:00

Use "@" to refer to parameters in the kernel-doc description. According
to Documentation/kernel-doc-nano-HOWTO.txt "&" shall be used to refer to
structures only.

Signed-off-by: Mathias Krause 
Cc: "David S. Miller" 
Signed-off-by: David S. Miller

net: move pskb_put() to core code

2013-11-08T00:28:58+00:00

This function has usage beside IPsec so move it to the core skbuff code.
While doing so, give it some documentation and change its return type to
'unsigned char *' to be in line with skb_put().

Signed-off-by: Mathias Krause 
Cc: Steffen Klassert 
Cc: "David S. Miller" 
Cc: Herbert Xu 
Signed-off-by: David S. Miller

net: introduce skb_coalesce_rx_frag()

2013-11-05T01:03:52+00:00

Sometimes we need to coalesce the rx frags to avoid frag list. One example is
virtio-net driver which tries to use small frags for both MTU sized packet and
GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this.

Cc: Rusty Russell 
Cc: Michael S. Tsirkin 
Cc: Michael Dalton 
Cc: Eric Dumazet 
Acked-by: Michael S. Tsirkin 
Signed-off-by: Jason Wang 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: checksum: fix warning in skb_checksum

2013-11-04T20:27:08+00:00

This patch fixes a build warning in skb_checksum() by wrapping the
csum_partial() usage in skb_checksum(). The problem is that on a few
architectures, csum_partial is used with prefix asmlinkage whereas
on most architectures it's not. So fix this up generically as we did
with csum_block_add_ext() to match the signature. Introduced by
2817a336d4d ("net: skb_checksum: allow custom update/combine for
walking skb").

Reported-by: Fengguang Wu 
Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller

net: skb_checksum: allow custom update/combine for walking skb

2013-11-04T04:04:57+00:00

Currently, skb_checksum walks over 1) linearized, 2) frags[], and
3) frag_list data and calculats the one's complement, a 32 bit
result suitable for feeding into itself or csum_tcpudp_magic(),
but unsuitable for SCTP as we're calculating CRC32c there.

Hence, in order to not re-implement the very same function in
SCTP (and maybe other protocols) over and over again, use an
update() + combine() callback internally to allow for walking
over the skb with different algorithms.

Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller

net: generalize skb_segment()

2013-10-19T23:36:18+00:00

While implementing GSO/TSO support for IPIP, I found skb_segment()
was assuming network header was immediately following mac header.

Its not really true in the case inet_gso_segment() is stacked :
By the time tcp_gso_segment() is called, network header points
to the inner IP header.

Let's instead assume nothing and pick the current offsets found in
original skb, we have skb_headers_offset_update() helper for that.

Also move the csum_start update inside skb_headers_offset_update()

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: gro: allow to build full sized skb

2013-10-10T04:08:07+00:00

skb_gro_receive() is currently limited to 16 or 17 MSS per GRO skb,
typically 24616 bytes, because it fills up to MAX_SKB_FRAGS frags.

It's relatively easy to extend the skb using frag_list to allow
more frags to be appended into the last sk_buff.

This still builds very efficient skbs, and allows reaching 45 MSS per
skb.

(45 MSS GRO packet uses one skb plus a frag_list containing 2 additional
sk_buff)

High speed TCP flows benefit from this extension by lowering TCP stack
cpu usage (less packets stored in receive queue, less ACK packets
processed)

Forwarding setups could be hurt, as such skbs will need to be
linearized, although its not a new problem, as GRO could already
provide skbs with a frag_list.

We could make the 65536 bytes threshold a tunable to mitigate this.

(First time we need to linearize skb in skb_needs_linearize(), we could
lower the tunable to ~16*1460 so that following skb_gro_receive() calls
build smaller skbs)

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller