IPV6, unlike IPV4, doesn't have a routing cache.

Routing table entries, as well as clones made in response
to route lookup requests, all live in the same table.  And
all of these things are together collected in the destination
cache table for ipv6.

This means that routing table entries count against the garbage
collection limits, even though such entries cannot ever be reclaimed
and are added explicitly by the administrator (rather than being
created in response to lookups).

Therefore it makes no sense to count ipv6 routing table entries
against the GC limits.

Add a DST_NOCOUNT destination cache entry flag, and skip the counting
if it is set.  Use this flag bit in ipv6 when adding routing table
entries.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This blows away any flags already set in the entry.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit c3968a85
('ipv6: RTA_PREFSRC support for ipv6 route source address selection')
added support for ipv6 prefsrc as an alternative to ipv6 addrlabels,
but it did not work because the prefsrc entry was not copied.

Cc: Daniel Walter <sahne@0x90.at>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make dst_alloc() and it's users explicitly initialize the entire
entry.

The zero'ing done by kmem_cache_zalloc() was almost entirely
redundant.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now the dst->dev, dev->obsolete, and dst->flags values can
be specified as well.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since commit 62fa8a84 (net: Implement read-only protection and COW'ing
of metrics.) the kernel throws an oops.

[  101.620985] BUG: unable to handle kernel NULL pointer dereference at
           (null)
[  101.621050] IP: [<          (null)>]           (null)
[  101.621084] PGD 6e53c067 PUD 3dd6a067 PMD 0
[  101.621122] Oops: 0010 [#1] SMP
[  101.621153] last sysfs file: /sys/devices/virtual/ppp/ppp/uevent
[  101.621192] CPU 2
[  101.621206] Modules linked in: l2tp_ppp pppox ppp_generic slhc
l2tp_netlink l2tp_core deflate zlib_deflate twofish_x86_64
twofish_common des_generic cbc ecb sha1_generic hmac af_key
iptable_filter snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device loop
snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec
snd_pcm snd_timer snd i2c_i801 iTCO_wdt psmouse soundcore snd_page_alloc
evdev uhci_hcd ehci_hcd thermal
[  101.621552]
[  101.621567] Pid: 5129, comm: openl2tpd Not tainted 2.6.39-rc4-Quad #3
Gigabyte Technology Co., Ltd. G33-DS3R/G33-DS3R
[  101.621637] RIP: 0010:[<0000000000000000>]  [<          (null)>]   (null)
[  101.621684] RSP: 0018:ffff88003ddeba60  EFLAGS: 00010202
[  101.621716] RAX: ffff88003ddb5600 RBX: ffff88003ddb5600 RCX:
0000000000000020
[  101.621758] RDX: ffffffff81a69a00 RSI: ffffffff81b7ee61 RDI:
ffff88003ddb5600
[  101.621800] RBP: ffff8800537cd900 R08: 0000000000000000 R09:
ffff88003ddb5600
[  101.621840] R10: 0000000000000005 R11: 0000000000014b38 R12:
ffff88003ddb5600
[  101.621881] R13: ffffffff81b7e480 R14: ffffffff81b7e8b8 R15:
ffff88003ddebad8
[  101.621924] FS:  00007f06e4182700(0000) GS:ffff88007fd00000(0000)
knlGS:0000000000000000
[  101.621971] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  101.622005] CR2: 0000000000000000 CR3: 0000000045274000 CR4:
00000000000006e0
[  101.622046] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[  101.622087] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
0000000000000400
[  101.622129] Process openl2tpd (pid: 5129, threadinfo
ffff88003ddea000, task ffff88003de9a280)
[  101.622177] Stack:
[  101.622191]  ffffffff81447efa ffff88007d3ded80 ffff88003de9a280
ffff88007d3ded80
[  101.622245]  0000000000000001 ffff88003ddebbb8 ffffffff8148d5a7
0000000000000212
[  101.622299]  ffff88003dcea000 ffff88003dcea188 ffffffff00000001
ffffffff81b7e480
[  101.622353] Call Trace:
[  101.622374]  [<ffffffff81447efa>] ? ipv4_blackhole_route+0x1ba/0x210
[  101.622415]  [<ffffffff8148d5a7>] ? xfrm_lookup+0x417/0x510
[  101.622450]  [<ffffffff8127672a>] ? extract_buf+0x9a/0x140
[  101.622485]  [<ffffffff8144c6a0>] ? __ip_flush_pending_frames+0x70/0x70
[  101.622526]  [<ffffffff8146fbbf>] ? udp_sendmsg+0x62f/0x810
[  101.622562]  [<ffffffff813f98a6>] ? sock_sendmsg+0x116/0x130
[  101.622599]  [<ffffffff8109df58>] ? find_get_page+0x18/0x90
[  101.622633]  [<ffffffff8109fd6a>] ? filemap_fault+0x12a/0x4b0
[  101.622668]  [<ffffffff813fb5c4>] ? move_addr_to_kernel+0x64/0x90
[  101.622706]  [<ffffffff81405d5a>] ? verify_iovec+0x7a/0xf0
[  101.622739]  [<ffffffff813fc772>] ? sys_sendmsg+0x292/0x420
[  101.622774]  [<ffffffff810b994a>] ? handle_pte_fault+0x8a/0x7c0
[  101.622810]  [<ffffffff810b76fe>] ? __pte_alloc+0xae/0x130
[  101.622844]  [<ffffffff810ba2f8>] ? handle_mm_fault+0x138/0x380
[  101.622880]  [<ffffffff81024af9>] ? do_page_fault+0x189/0x410
[  101.622915]  [<ffffffff813fbe03>] ? sys_getsockname+0xf3/0x110
[  101.622952]  [<ffffffff81450c4d>] ? ip_setsockopt+0x4d/0xa0
[  101.622986]  [<ffffffff813f9932>] ? sockfd_lookup_light+0x22/0x90
[  101.623024]  [<ffffffff814b61fb>] ? system_call_fastpath+0x16/0x1b
[  101.623060] Code:  Bad RIP value.
[  101.623090] RIP  [<          (null)>]           (null)
[  101.623125]  RSP <ffff88003ddeba60>
[  101.623146] CR2: 0000000000000000
[  101.650871] ---[ end trace ca3856a7d8e8dad4 ]---
[  101.651011] __sk_free: optmem leakage (160 bytes) detected.

The oops happens in dst_metrics_write_ptr()
include/net/dst.h:124: return dst->ops->cow_metrics(dst, p);

dst->ops->cow_metrics is NULL and causes the oops.

Provide cow_metrics() methods, like we did in commit 214f45c9
(net: provide default_advmss() methods to blackhole dst_ops)
Signed-off-by: NHeld Bernhard <berny156@gmx.de>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add const qualifiers to structs iphdr, ipv6hdr and in6_addr pointers
where possible, to make code intention more obvious.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The changes introduced with git-commit a02e4b7d ("ipv6: Demark default
hoplimit as zero.") missed to remove the hoplimit initialization. As a
result, ipv6_get_mtu interprets the return value of dst_metric_raw
(-1) as 255 and answers ping6 with this hoplimit.  This patche removes
the line such that ping6 is answered with the hoplimit value
configured via sysctl.
Signed-off-by: NThomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

[ipv6] Add support for RTA_PREFSRC

This patch allows a user to select the preferred source address
for a specific IPv6-Route. It can be set via a netlink message
setting RTA_PREFSRC to a valid IPv6 address which must be
up on the device the route will be bound to.
Signed-off-by: NDaniel Walter <dwalter@barracuda.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This avoids explicit cast to avoid 'discards qualifiers'
compiler warning in a netfilter patch that i've been working on.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

I intend to turn struct flowi into a union of AF specific flowi
structs.  There will be a common structure that each variant includes
first, much like struct sock_common.

This is the first step to move in that direction.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Addresses https://bugzilla.kernel.org/show_bug.cgi?id=29252
Addresses https://bugzilla.kernel.org/show_bug.cgi?id=30462

In commit d80bc0fd ("ipv6: Always
clone offlink routes.") we forced the kernel to always clone offlink
routes.

The reason we do that is to make sure we never bind an inetpeer to a
prefixed route.

The logic turned on here has existed in the tree for many years,
but was always off due to a protecting CPP define.  So perhaps
it's no surprise that there is a logic bug here.

The problem is that we canot clone a route that is already a
host route (ie. has DST_HOST set).  Because if we do, an identical
entry already exists in the routing tree and therefore the
ip6_rt_ins() call is going to fail.

This sets off a series of failures and high cpu usage, because when
ip6_rt_ins() fails we loop retrying this operation a few times in
order to handle a race between two threads trying to clone and insert
the same host route at the same time.

Fix this by simply using the route as-is when DST_HOST is set.

Reported-by: slash@ac.auone-net.jp
Reported-by: NErnst Sjöstrand <ernstp@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

That way we don't have to potentially do this in every xfrm_lookup()
caller.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Return a dst pointer which is potentitally error encoded.

Don't pass original dst pointer by reference, pass a struct net
instead of a socket, and elide the flow argument since it is
unnecessary.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NHagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Before this patch issuing these commands:

  fd = open("/proc/sys/net/ipv6/route/flush")
  unshare(CLONE_NEWNET)
  write(fd, "stuff")

would flush the newly created net, not the original one.

The equivalent ipv4 code is correct (stores the net inside ->extra1).
Acked-by: NDaniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 0dbaee3b (net: Abstract default ADVMSS behind an
accessor.) introduced a possible crash in tcp_connect_init(), when
dst->default_advmss() is called from dst_metric_advmss()
Reported-by: NGeorge Spelvin <linux@horizon.com>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This allows avoiding multiple writes to the initial __refcnt.

The most simplest cases of wanting an initial reference of "1"
in ipv4 and ipv6 have been converted, the rest have been left
along and kept at the existing "0".
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If we didn't have a routing cache, we would not be able to properly
propagate certain kinds of dynamic path attributes, for example
PMTU information and redirects.

The reason is that if we didn't have a routing cache, then there would
be no way to lookup all of the active cached routes hanging off of
sockets, tunnels, IPSEC bundles, etc.

Consider the case where we created a cached route, but no inetpeer
entry existed and also we were not asked to pre-COW the route metrics
and therefore did not force the creation a new inetpeer entry.

If we later get a PMTU message, or a redirect, and store this
information in a new inetpeer entry, there is no way to teach that
cached route about the newly existing inetpeer entry.

The facilities implemented here handle this problem.

First we create a generation ID.  When we create a cached route of any
kind, we remember the generation ID at the time of attachment.  Any
time we force-create an inetpeer entry in response to new path
information, we bump that generation ID.

The dst_ops->check() callback is where the knowledge of this event
is propagated.  If the global generation ID does not equal the one
stored in the cached route, and the cached route has not attached
to an inetpeer yet, we look it up and attach if one is found.  Now
that we've updated the cached route's information, we update the
route's generation ID too.

This clears the way for implementing PMTU and redirects directly in
the inetpeer cache.  There is absolutely no need to consult cached
route information in order to maintain this information.

At this point nothing bumps the inetpeer genids, that comes in the
later changes which handle PMTUs and redirects using inetpeers.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Nobody actually does anything in response to the event,
so just kill it off.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When an IPSEC SA is still being set up, __xfrm_lookup() will return
-EREMOTE and so ip_route_output_flow() will return a blackhole route.
This can happen in a sndmsg call, and after d33e4553 ("net: Abstract
default MTU metric calculation behind an accessor.") this leads to a
crash in ip_append_data() because the blackhole dst_ops have no
default_mtu() method and so dst_mtu() calls a NULL pointer.

Fix this by adding default_mtu() methods (that simply return 0, matching
the old behavior) to the blackhole dst_ops.

The IPv4 part of this patch fixes a crash that I saw when using an IPSEC
VPN; the IPv6 part is untested because I don't have an IPv6 VPN, but it
looks to be needed as well.
Signed-off-by: NRoland Dreier <roland@purestorage.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Please note that the IPSEC dst entry metrics keep using
the generic metrics COW'ing mechanism using kmalloc/kfree.

This gives the IPSEC routes an opportunity to use metrics
which are unique to their encapsulated paths.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

They are bogus.  The basic idea is that I wanted to make sure
that prefixed routes never bind to peers.

The test I used was whether RTF_CACHE was set.

But first of all, the RTF_CACHE flag is set at different spots
depending upon which ip6_rt_copy() caller you're talking about.

I've validated all of the code paths, and even in the future
where we bind peers more aggressively (for route metric COW'ing)
we never bind to prefix'd routes, only fully specified ones.
This even applies when addrconf or icmp6 routes are allocated.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Routing metrics are now copy-on-write.

Initially a route entry points it's metrics at a read-only location.
If a routing table entry exists, it will point there.  Else it will
point at the all zero metric place-holder called 'dst_default_metrics'.

The writeability state of the metrics is stored in the low bits of the
metrics pointer, we have two bits left to spare if we want to store
more states.

For the initial implementation, COW is implemented simply via kmalloc.
However future enhancements will change this to place the writable
metrics somewhere else, in order to increase sharing.  Very likely
this "somewhere else" will be the inetpeer cache.

Note also that this means that metrics updates may transiently fail
if we cannot COW the metrics successfully.

But even by itself, this patch should decrease memory usage and
increase cache locality especially for routing workloads.  In those
cases the read-only metric copies stay in place and never get written
to.

TCP workloads where metrics get updated, and those rare cases where
PMTU triggers occur, will take a very slight performance hit.  But
that hit will be alleviated when the long-term writable metrics
move to a more sharable location.

Since the metrics storage went from a u32 array of RTAX_MAX entries to
what is essentially a pointer, some retooling of the dst_entry layout
was necessary.

Most importantly, we need to preserve the alignment of the reference
count so that it doesn't share cache lines with the read-mostly state,
as per Eric Dumazet's alignment assertion checks.

The only non-trivial bit here is the move of the 'flags' member into
the writeable cacheline.  This is OK since we are always accessing the
flags around the same moment when we made a modification to the
reference count.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Do not handle PMTU vs. route lookup creation any differently
wrt. offlink routes, always clone them.
Reported-by: NPK <runningdoglackey@yahoo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove (unnecessary) casts to make code cleaner.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The first big packets sent to a "low-MTU" client correctly
triggers the creation of a temporary route containing the reduced MTU.

But after the temporary route has expired, new ICMP6 "packet too big"
will be sent, rt6_pmtu_discovery will find the previous EXPIRED route
check that its mtu isn't bigger then in icmp packet and do nothing
before the temporary route will not deleted by gc.

I make the simple experiment:
while :; do
    time ( dd if=/dev/zero bs=10K count=1 | ssh hostname dd of=/dev/null ) || break;
done

The "time" reports real 0m0.197s if a temporary route isn't expired, but
it reports real 0m52.837s (!!!!) immediately after a temporare route has
expired.
Signed-off-by: NAndrey Vagin <avagin@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Like RTAX_ADVMSS, make the default calculation go through a dst_ops
method rather than caching the computation in the routing cache
entries.

Now dst metrics are pretty much left as-is when new entries are
created, thus optimizing metric sharing becomes a real possibility.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make all RTAX_ADVMSS metric accesses go through a new helper function,
dst_metric_advmss().

Leave the actual default metric as "zero" in the real metric slot,
and compute the actual default value dynamically via a new dst_ops
AF specific callback.

For stacked IPSEC routes, we use the advmss of the path which
preserves existing behavior.

Unlike ipv4/ipv6, DecNET ties the advmss to the mtu and thus updates
advmss on pmtu updates.  This inconsistency in advmss handling
results in more raw metric accesses than I wish we ended up with.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is for consistency with ipv4.  Using "-1" makes
no sense.

It was made this way a long time ago merely to be consistent
with how the ipv6 socket hoplimit "default" is stored.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use helper functions to hide all direct accesses, especially writes,
to dst_entry metrics values.

This will allow us to:

1) More easily change how the metrics are stored.

2) Implement COW for metrics.

In particular this will help us put metrics into the inetpeer
cache if that is what we end up doing.  We can make the _metrics
member a pointer instead of an array, initially have it point
at the read-only metrics in the FIB, and then on the first set
grab an inetpeer entry and point the _metrics member there.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>

They are only allowed on cached ipv6 routes.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1. IPV6_TLV_TEL_DST_SIZE
This has not been using for several years since created.

2. RT6_INFO_LEN
commit 33120b30 kill all RT6_INFO_LEN's references, but only this definition remained.

commit 33120b30
Author: Alexey Dobriyan <adobriyan@sw.ru>
Date:   Tue Nov 6 05:27:11 2007 -0800

    [IPV6]: Convert /proc/net/ipv6_route to seq_file interface
Signed-off-by: NShan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the macros defined for the members of flowi to clean the code up.
Signed-off-by: NChangli Gao <xiaosuo@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This gives users at least some clue as to what the problem
might be and how to go about fixing it.
Signed-off-by: NBen Greear <greearb@candelatech.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There're some percpu_counter list corruption and poison overwritten warnings
in recent kernel, which is resulted by fc66f95c.

commit fc66f95c switches to use percpu_counter, in ip6_route_net_init, kernel
init the percpu_counter for dst entries, but, the percpu_counter is never destroyed
in ip6_route_net_exit. So if the related data is freed by kernel, the freed percpu_counter
is still on the list, then if we insert/remove other percpu_counter, list corruption
resulted. Also, if the insert/remove option modifies the ->prev,->next pointer of
the freed value, the poison overwritten is resulted then.

With the following patch, the percpu_counter list corruption and poison overwritten
warnings disappeared.
Signed-off-by: NXiaotian Feng <dfeng@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: "Pekka Savola (ipv6)" <pekkas@netcore.fi>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>