linux-stable.git/include/linux/skbuff.h, branch v3.13.6

net: ip, ipv6: handle gso skbs in forwarding path

2014-03-07T06:06:14+00:00

commit fe6cc55f3a9a053482a76f5a6b2257cee51b4663 upstream.

Marcelo Ricardo Leitner reported problems when the forwarding link path
has a lower mtu than the incoming one if the inbound interface supports GRO.

Given:
Host  R1  R2

Host sends tcp stream which is routed via R1 and R2.  R1 performs GRO.

In this case, the kernel will fail to send ICMP fragmentation needed
messages (or pkt too big for ipv6), as GSO packets currently bypass dstmtu
checks in forward path. Instead, Linux tries to send out packets exceeding
the mtu.

When locking route MTU on Host (i.e., no ipv4 DF bit set), R1 does
not fragment the packets when forwarding, and again tries to send out
packets exceeding R1-R2 link mtu.

This alters the forwarding dstmtu checks to take the individual gso
segment lengths into account.

For ipv6, we send out pkt too big error for gso if the individual
segments are too big.

For ipv4, we either send icmp fragmentation needed, or, if the DF bit
is not set, perform software segmentation and let the output path
create fragments when the packet is leaving the machine.
It is not 100% correct as the error message will contain the headers of
the GRO skb instead of the original/segmented one, but it seems to
work fine in my (limited) tests.

Eric Dumazet suggested to simply shrink mss via ->gso_size to avoid
sofware segmentation.

However it turns out that skb_segment() assumes skb nr_frags is related
to mss size so we would BUG there.  I don't want to mess with it considering
Herbert and Eric disagree on what the correct behavior should be.

Hannes Frederic Sowa notes that when we would shrink gso_size
skb_segment would then also need to deal with the case where
SKB_MAX_FRAGS would be exceeded.

This uses sofware segmentation in the forward path when we hit ipv4
non-DF packets and the outgoing link mtu is too small.  Its not perfect,
but given the lack of bug reports wrt. GRO fwd being broken this is a
rare case anyway.  Also its not like this could not be improved later
once the dust settles.

Acked-by: Herbert Xu 
Reported-by: Marcelo Ricardo Leitner 
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()

2014-03-07T06:06:14+00:00

commit de960aa9ab4decc3304959f69533eef64d05d8e8 upstream.

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

net: Add some clarification to skb_tx_timestamp() comment.

2013-12-27T18:04:33+00:00

We've seen so many instances of people invoking skb_tx_timestamp()
after the device already has been given the packet, that it's worth
being a little bit more verbose and explicit in this comment.

Signed-off-by: David S. Miller

ip_gre: fix msg_name parsing for recvfrom/recvmsg

2013-12-18T22:44:33+00:00

ipgre_header_parse() needs to parse the tunnel's ip header and it
uses mac_header to locate the iphdr. This got broken when gre tunneling
was refactored as mac_header is no longer updated to point to iphdr.
Introduce skb_pop_mac_header() helper to do the mac_header assignment
and use it in ipgre_rcv() to fix msg_name parsing.

Bug introduced in commit c54419321455 (GRE: Refactor GRE tunneling code.)

Cc: Pravin B Shelar 
Signed-off-by: Timo Teräs 
Signed-off-by: David S. Miller

Revert "net: Handle CHECKSUM_COMPLETE more adequately in pskb_trim_rcsum()."

2013-12-02T22:26:05+00:00

This reverts commit 018c5bba052b3a383d83cf0c756da0e7bc748397.

It causes regressions for people using chips driven by the sungem
driver.  Suspicion is that the skb->csum value isn't being adjusted
properly.

The change also has a bug in that if __pskb_trim() fails, we'll leave
a corruped skb->csum value in there.  We would really need to revert
it to it's original value in that case.

Signed-off-by: David S. Miller

net: Handle CHECKSUM_COMPLETE more adequately in pskb_trim_rcsum().

2013-11-16T02:11:16+00:00

Currently pskb_trim_rcsum() just balks on CHECKSUM_COMPLETE packets
and remarks them as CHECKSUM_NONE, forcing a software checksum
validation later.

We have all of the mechanics available to fixup the skb->csum value,
even for complicated fragmented packets, via the helpers
skb_checksum() and csum_sub().

So just use them.

Based upon a suggestion by Herbert Xu.

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