linux-toradex.git/net/ipv4/icmp.c, branch v3.10.52

ipv4: icmp: Fix pMTU handling for rare case

2014-07-28T15:00:04+00:00

[ Upstream commit 68b7107b62983f2cff0948292429d5f5999df096 ]

Some older router implementations still send Fragmentation Needed
errors with the Next-Hop MTU field set to zero. This is explicitly
described as an eventuality that hosts must deal with by the
standard (RFC 1191) since older standards specified that those
bits must be zero.

Linux had a generic (for all of IPv4) implementation of the algorithm
described in the RFC for searching a list of MTU plateaus for a good
value. Commit 46517008e116 ("ipv4: Kill ip_rt_frag_needed().")
removed this as part of the changes to remove the routing cache.
Subsequently any Fragmentation Needed packet with a zero Next-Hop
MTU has been discarded without being passed to the per-protocol
handlers or notifying userspace for raw sockets.

When there is a router which does not implement RFC 1191 on an
MTU limited path then this results in stalled connections since
large packets are discarded and the local protocols are not
notified so they never attempt to lower the pMTU.

One example I have seen is an OpenBSD router terminating IPSec
tunnels. It's worth pointing out that this case is distinct from
the BSD 4.2 bug which incorrectly calculated the Next-Hop MTU
since the commit in question dismissed that as a valid concern.

All of the per-protocols handlers implement the simple approach from
RFC 1191 of immediately falling back to the minimum value. Although
this is sub-optimal it is vastly preferable to connections hanging
indefinitely.

Remove the Next-Hop MTU != 0 check and allow such packets
to follow the normal path.

Fixes: 46517008e116 ("ipv4: Kill ip_rt_frag_needed().")
Signed-off-by: Edward Allcutt 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: Add MIB counters for checksum errors

2013-04-29T19:14:03+00:00

Add MIB counters for checksum errors in IP layer,
and TCP/UDP/ICMP layers, to help diagnose problems.

$ nstat -a | grep  Csum
IcmpInCsumErrors                72                 0.0
TcpInCsumErrors                 382                0.0
UdpInCsumErrors                 463221             0.0
Icmp6InCsumErrors               75                 0.0
Udp6InCsumErrors                173442             0.0
IpExtInCsumErrors               10884              0.0

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

ipv4: fix error handling in icmp_protocol.

2013-02-22T20:10:18+00:00

Now we handle icmp errors in each transport protocol's err_handler,
for icmp protocols, that is ping_err. Since this handler only care
of those icmp errors triggered by echo request, errors triggered
by echo reply(which sent by kernel) are sliently ignored.

So wrap ping_err() with icmp_err() to deal with those icmp errors.

Signed-off-by: Li Wei 
Signed-off-by: David S. Miller

ipv4: avoid passing NULL to inet_putpeer() in icmpv4_xrlim_allow()

2012-11-26T22:24:41+00:00

inet_getpeer_v4() can return NULL under OOM conditions, and while
inet_peer_xrlim_allow() is OK with a NULL peer, inet_putpeer() will
crash.

This code path now uses the same idiom as the others from:
1d861aa4b3fb08822055345f480850205ffe6170 ("inet: Minimize use of
cached route inetpeer.").

Signed-off-by: Neal Cardwell 
Signed-off-by: David S. Miller

ipv4: Prepare for change of rt->rt_iif encoding.

2012-07-23T23:36:26+00:00

Use inet_iif() consistently, and for TCP record the input interface of
cached RX dst in inet sock.

rt->rt_iif is going to be encoded differently, so that we can
legitimately cache input routes in the FIB info more aggressively.

When the input interface is "use SKB device index" the rt->rt_iif will
be set to zero.

This forces us to move the TCP RX dst cache installation into the ipv4
specific code, and as well it should since doing the route caching for
ipv6 is pointless at the moment since it is not inspected in the ipv6
input paths yet.

Also, remove the unlikely on dst->obsolete, all ipv4 dsts have
obsolete set to a non-zero value to force invocation of the check
callback.

Signed-off-by: David S. Miller

ipv4: Really ignore ICMP address requests/replies.

2012-07-23T20:20:26+00:00

Alexey removed kernel side support for requests, and the
only thing we do for replies is log a message if something
doesn't look right.

As Alexey's comment indicates, this belongs in userspace (if
anywhere), and thus we can safely just get rid of this code.

Signed-off-by: David S. Miller

ipv4: Put proper checks into icmp_socket_deliver().

2012-07-12T15:06:04+00:00

All handler->err() routines expect that we've done a pskb_may_pull()
test to make sure that IP header length + 8 bytes can be safely
pulled.

Reported-by: Hiroaki SHIMODA 
Signed-off-by: David S. Miller

ipv4: Kill ip_rt_redirect().

2012-07-12T04:30:08+00:00

No longer needed, as the protocol handlers now all properly
propagate the redirect back into the routing code.

Signed-off-by: David S. Miller

ipv4: Rearrange arguments to ip_rt_redirect()

2012-07-12T03:38:08+00:00

Pass in the SKB rather than just the IP addresses, so that policy
and other aspects can reside in ip_rt_redirect() rather then
icmp_redirect().

Signed-off-by: David S. Miller

ipv4: Deliver ICMP redirects to sockets too.

2012-07-12T01:35:12+00:00

And thus, we can remove the ping_err() hack.

Signed-off-by: David S. Miller