2005-04-16 22:20:36 +00:00
|
|
|
/*
|
|
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|
|
* INET An implementation of the TCP/IP protocol suite for the LINUX
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|
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* The IP forwarding functionality.
|
2007-02-09 14:24:47 +00:00
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*
|
2005-04-16 22:20:36 +00:00
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* Authors: see ip.c
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*
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|
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* Fixes:
|
2007-02-09 14:24:47 +00:00
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* Many : Split from ip.c , see ip_input.c for
|
2005-04-16 22:20:36 +00:00
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* history.
|
2007-02-09 14:24:47 +00:00
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* Dave Gregorich : NULL ip_rt_put fix for multicast
|
2005-04-16 22:20:36 +00:00
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* routing.
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* Jos Vos : Add call_out_firewall before sending,
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* use output device for accounting.
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* Jos Vos : Call forward firewall after routing
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* (always use output device).
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* Mike McLagan : Routing by source
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*/
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#include <linux/types.h>
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#include <linux/mm.h>
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|
#include <linux/skbuff.h>
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|
|
|
#include <linux/ip.h>
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#include <linux/icmp.h>
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|
|
|
|
#include <linux/netdevice.h>
|
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
|
|
|
#include <linux/slab.h>
|
2005-04-16 22:20:36 +00:00
|
|
|
#include <net/sock.h>
|
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|
|
#include <net/ip.h>
|
|
|
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|
#include <net/tcp.h>
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|
#include <net/udp.h>
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|
#include <net/icmp.h>
|
|
|
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|
#include <linux/tcp.h>
|
|
|
|
|
#include <linux/udp.h>
|
|
|
|
|
#include <linux/netfilter_ipv4.h>
|
|
|
|
|
#include <net/checksum.h>
|
|
|
|
|
#include <linux/route.h>
|
|
|
|
|
#include <net/route.h>
|
|
|
|
|
#include <net/xfrm.h>
|
|
|
|
|
|
net: ip, ipv6: handle gso skbs in forwarding path
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 <mtu1500> R1 <mtu1200> 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 <herbert@gondor.apana.org.au>
Reported-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-02-13 22:09:12 +00:00
|
|
|
static bool ip_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
|
|
|
|
|
{
|
2014-05-04 21:24:31 +00:00
|
|
|
if (skb->len <= mtu)
|
net: ip, ipv6: handle gso skbs in forwarding path
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 <mtu1500> R1 <mtu1200> 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 <herbert@gondor.apana.org.au>
Reported-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-02-13 22:09:12 +00:00
|
|
|
return false;
|
|
|
|
|
|
2015-05-21 22:06:40 +00:00
|
|
|
if (unlikely((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0))
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
/* original fragment exceeds mtu and DF is set */
|
|
|
|
|
if (unlikely(IPCB(skb)->frag_max_size > mtu))
|
|
|
|
|
return true;
|
|
|
|
|
|
|
|
|
|
if (skb->ignore_df)
|
|
|
|
|
return false;
|
|
|
|
|
|
net: ip, ipv6: handle gso skbs in forwarding path
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 <mtu1500> R1 <mtu1200> 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 <herbert@gondor.apana.org.au>
Reported-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-02-13 22:09:12 +00:00
|
|
|
if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
|
|
|
|
|
return false;
|
|
|
|
|
|
|
|
|
|
return true;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
2015-09-16 01:04:18 +00:00
|
|
|
static int ip_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
2012-04-15 01:34:41 +00:00
|
|
|
struct ip_options *opt = &(IPCB(skb)->opt);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2015-09-16 01:03:55 +00:00
|
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_OUTFORWDATAGRAMS);
|
|
|
|
|
IP_ADD_STATS_BH(net, IPSTATS_MIB_OUTOCTETS, skb->len);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
if (unlikely(opt->optlen))
|
|
|
|
|
ip_forward_options(skb);
|
|
|
|
|
|
2015-03-12 01:42:02 +00:00
|
|
|
skb_sender_cpu_clear(skb);
|
2015-09-16 01:03:53 +00:00
|
|
|
return dst_output(sk, skb);
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
int ip_forward(struct sk_buff *skb)
|
|
|
|
|
{
|
2014-01-09 09:01:15 +00:00
|
|
|
u32 mtu;
|
2005-04-16 22:20:36 +00:00
|
|
|
struct iphdr *iph; /* Our header */
|
|
|
|
|
struct rtable *rt; /* Route we use */
|
2012-04-15 01:34:41 +00:00
|
|
|
struct ip_options *opt = &(IPCB(skb)->opt);
|
2015-09-16 01:03:54 +00:00
|
|
|
struct net *net;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2014-02-13 04:58:56 +00:00
|
|
|
/* that should never happen */
|
|
|
|
|
if (skb->pkt_type != PACKET_HOST)
|
|
|
|
|
goto drop;
|
|
|
|
|
|
2015-04-20 07:19:20 +00:00
|
|
|
if (unlikely(skb->sk))
|
|
|
|
|
goto drop;
|
|
|
|
|
|
2008-06-19 23:22:28 +00:00
|
|
|
if (skb_warn_if_lro(skb))
|
|
|
|
|
goto drop;
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb))
|
|
|
|
|
goto drop;
|
|
|
|
|
|
|
|
|
|
if (IPCB(skb)->opt.router_alert && ip_call_ra_chain(skb))
|
|
|
|
|
return NET_RX_SUCCESS;
|
|
|
|
|
|
2007-03-27 06:22:20 +00:00
|
|
|
skb_forward_csum(skb);
|
2015-09-16 01:03:54 +00:00
|
|
|
net = dev_net(skb->dev);
|
2007-02-09 14:24:47 +00:00
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/*
|
|
|
|
|
* According to the RFC, we must first decrease the TTL field. If
|
|
|
|
|
* that reaches zero, we must reply an ICMP control message telling
|
|
|
|
|
* that the packet's lifetime expired.
|
|
|
|
|
*/
|
2007-04-21 05:47:35 +00:00
|
|
|
if (ip_hdr(skb)->ttl <= 1)
|
2007-02-09 14:24:47 +00:00
|
|
|
goto too_many_hops;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
if (!xfrm4_route_forward(skb))
|
|
|
|
|
goto drop;
|
|
|
|
|
|
2009-06-02 05:14:27 +00:00
|
|
|
rt = skb_rtable(skb);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2012-10-08 11:41:18 +00:00
|
|
|
if (opt->is_strictroute && rt->rt_uses_gateway)
|
2005-04-16 22:20:36 +00:00
|
|
|
goto sr_failed;
|
|
|
|
|
|
2014-01-09 09:01:15 +00:00
|
|
|
IPCB(skb)->flags |= IPSKB_FORWARDED;
|
|
|
|
|
mtu = ip_dst_mtu_maybe_forward(&rt->dst, true);
|
2015-05-21 22:06:40 +00:00
|
|
|
if (ip_exceeds_mtu(skb, mtu)) {
|
2015-09-16 01:03:54 +00:00
|
|
|
IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
|
2007-03-26 06:32:29 +00:00
|
|
|
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
|
2014-01-09 09:01:15 +00:00
|
|
|
htonl(mtu));
|
2007-03-26 06:32:29 +00:00
|
|
|
goto drop;
|
|
|
|
|
}
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/* We are about to mangle packet. Copy it! */
|
2010-06-11 06:31:35 +00:00
|
|
|
if (skb_cow(skb, LL_RESERVED_SPACE(rt->dst.dev)+rt->dst.header_len))
|
2005-04-16 22:20:36 +00:00
|
|
|
goto drop;
|
2007-04-21 05:47:35 +00:00
|
|
|
iph = ip_hdr(skb);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
/* Decrease ttl after skb cow done */
|
|
|
|
|
ip_decrease_ttl(iph);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* We now generate an ICMP HOST REDIRECT giving the route
|
|
|
|
|
* we calculated.
|
|
|
|
|
*/
|
2015-01-23 11:01:26 +00:00
|
|
|
if (IPCB(skb)->flags & IPSKB_DOREDIRECT && !opt->srr &&
|
|
|
|
|
!skb_sec_path(skb))
|
2005-04-16 22:20:36 +00:00
|
|
|
ip_rt_send_redirect(skb);
|
|
|
|
|
|
|
|
|
|
skb->priority = rt_tos2priority(iph->tos);
|
|
|
|
|
|
2015-09-16 01:04:16 +00:00
|
|
|
return NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD,
|
|
|
|
|
net, NULL, skb, skb->dev, rt->dst.dev,
|
|
|
|
|
ip_forward_finish);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
sr_failed:
|
2007-02-09 14:24:47 +00:00
|
|
|
/*
|
2005-04-16 22:20:36 +00:00
|
|
|
* Strict routing permits no gatewaying
|
|
|
|
|
*/
|
2007-02-09 14:24:47 +00:00
|
|
|
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_SR_FAILED, 0);
|
|
|
|
|
goto drop;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
too_many_hops:
|
2007-02-09 14:24:47 +00:00
|
|
|
/* Tell the sender its packet died... */
|
2015-09-16 01:03:54 +00:00
|
|
|
IP_INC_STATS_BH(net, IPSTATS_MIB_INHDRERRORS);
|
2007-02-09 14:24:47 +00:00
|
|
|
icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
|
2005-04-16 22:20:36 +00:00
|
|
|
drop:
|
|
|
|
|
kfree_skb(skb);
|
|
|
|
|
return NET_RX_DROP;
|
|
|
|
|
}
|
