This patch adds a new option CONFIG_IPV6_SEG6_LWTUNNEL to enable/disable
support of encapsulation with the lightweight tunnels. When this option
is enabled, CONFIG_LWTUNNEL is automatically selected.
Fix commit 6c8702c60b ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels")
Without a proper option to control lwtunnel support for SR-IPv6, if
CONFIG_LWTUNNEL=n then the IPv6 initialization fails as a consequence
of seg6_iptunnel_init() failure with EOPNOTSUPP:
NET: Registered protocol family 10
IPv6: Attempt to unregister permanent protocol 6
IPv6: Attempt to unregister permanent protocol 136
IPv6: Attempt to unregister permanent protocol 17
NET: Unregistered protocol family 10
Tested (compiling, booting, and loading ipv6 module when relevant)
with possible combinations of CONFIG_IPV6={y,m,n},
CONFIG_IPV6_SEG6_LWTUNNEL={y,n} and CONFIG_LWTUNNEL={y,n}.
Reported-by: Lorenzo Colitti <lorenzo@google.com>
Suggested-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary functions to compute and check the HMAC signature
of an SR-enabled packet. Two HMAC algorithms are supported: hmac(sha1) and
hmac(sha256).
In order to avoid dynamic memory allocation for each HMAC computation,
a per-cpu ring buffer is allocated for this purpose.
A new per-interface sysctl called seg6_require_hmac is added, allowing a
user-defined policy for processing HMAC-signed SR-enabled packets.
A value of -1 means that the HMAC field will always be ignored.
A value of 0 means that if an HMAC field is present, its validity will
be enforced (the packet is dropped is the signature is incorrect).
Finally, a value of 1 means that any SR-enabled packet that does not
contain an HMAC signature or whose signature is incorrect will be dropped.
Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch creates a new type of interfaceless lightweight tunnel (SEG6),
enabling the encapsulation and injection of SRH within locally emitted
packets and forwarded packets.
>From a configuration viewpoint, a seg6 tunnel would be configured as follows:
ip -6 ro ad fc00::1/128 encap seg6 mode encap segs fc42::1,fc42::2,fc42::3 dev eth0
Any packet whose destination address is fc00::1 would thus be encapsulated
within an outer IPv6 header containing the SRH with three segments, and would
actually be routed to the first segment of the list. If `mode inline' was
specified instead of `mode encap', then the SRH would be directly inserted
after the IPv6 header without outer encapsulation.
The inline mode is only available if CONFIG_IPV6_SEG6_INLINE is enabled. This
feature was made configurable because direct header insertion may break
several mechanisms such as PMTUD or IPSec AH.
Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the necessary hooks and structures to provide support
for SR-IPv6 control plane, essentially the Generic Netlink commands
that will be used for userspace control over the Segment Routing
kernel structures.
The genetlink commands provide control over two different structures:
tunnel source and HMAC data. The tunnel source is the source address
that will be used by default when encapsulating packets into an
outer IPv6 header + SRH. If the tunnel source is set to :: then an
address of the outgoing interface will be selected as the source.
The HMAC commands currently just return ENOTSUPP and will be implemented
in a future patch.
Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
CALIPSO is a packet labelling protocol for IPv6 which is very similar
to CIPSO. It is specified in RFC 5570. Much of the code is based on
the current CIPSO code.
This adds support for adding passthrough-type CALIPSO DOIs through the
NLBL_CALIPSO_C_ADD command. It requires attributes:
NLBL_CALIPSO_A_TYPE which must be CALIPSO_MAP_PASS.
NLBL_CALIPSO_A_DOI.
In passthrough mode the CALIPSO engine will map MLS secattr levels
and categories directly to the packet label.
At this stage, the major difference between this and the CIPSO
code is that IPv6 may be compiled as a module. To allow for
this the CALIPSO functions are registered at module init time.
Signed-off-by: Huw Davies <huw@codeweavers.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
The Kconfig options I added to work around broken compilation ended
up screwing up things more, as I used the wrong symbol to control
compilation of the file, resulting in IPv6 fou support to never be built
into the kernel.
Changing CONFIG_NET_FOU_IPV6_TUNNELS to CONFIG_IPV6_FOU fixes that
problem, I had renamed the symbol in one location but not the other,
and as the file is never being used by other kernel code, this did not
lead to a build failure that I would have caught.
After that fix, another issue with the same patch becomes obvious, as we
'select INET6_TUNNEL', which is related to IPV6_TUNNEL, but not the same,
and this can still cause the original build failure when IPV6_TUNNEL is
not built-in but IPV6_FOU is. The fix is equally trivial, we just need
to select the right symbol.
I have successfully build 350 randconfig kernels with this patch
and verified that the driver is now being built.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Valentin Rothberg <valentinrothberg@gmail.com>
Fixes: fabb13db44 ("fou: add Kconfig options for IPv6 support")
Signed-off-by: David S. Miller <davem@davemloft.net>
A previous patch added the fou6.ko module, but that failed to link
in a couple of configurations:
net/built-in.o: In function `ip6_tnl_encap_add_fou_ops':
net/ipv6/fou6.c:88: undefined reference to `ip6_tnl_encap_add_ops'
net/ipv6/fou6.c:94: undefined reference to `ip6_tnl_encap_add_ops'
net/ipv6/fou6.c:97: undefined reference to `ip6_tnl_encap_del_ops'
net/built-in.o: In function `ip6_tnl_encap_del_fou_ops':
net/ipv6/fou6.c:106: undefined reference to `ip6_tnl_encap_del_ops'
net/ipv6/fou6.c:107: undefined reference to `ip6_tnl_encap_del_ops'
If CONFIG_IPV6=m, ip6_tnl_encap_add_ops/ip6_tnl_encap_del_ops
are in a module, but fou6.c can still be built-in, and that
obviously fails to link.
Also, if CONFIG_IPV6=y, but CONFIG_IPV6_TUNNEL=m or
CONFIG_IPV6_TUNNEL=n, the same problem happens for a different
reason.
This adds two new silent Kconfig symbols to work around both
problems:
- CONFIG_IPV6_FOU is now always set to 'm' if either CONFIG_NET_FOU=m
or CONFIG_IPV6=m
- CONFIG_IPV6_FOU_TUNNEL is set implicitly when IPV6_FOU is enabled
and NET_FOU_IP_TUNNELS is also turned out, and it will ensure
that CONFIG_IPV6_TUNNEL is also available.
The options could be made user-visible as well, to give additional
room for configuration, but it seems easier not to bother users
with more choice here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: aa3463d65e ("fou: Add encap ops for IPv6 tunnels")
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch add a new fou6 module that provides encapsulation
operations for IPv6.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds GRO functions (gro_receive and gro_complete) to UDP
sockets. udp_gro_receive is changed to perform socket lookup on a
packet. If a socket is found the related GRO functions are called.
This features obsoletes using UDP offload infrastructure for GRO
(udp_offload). This has the advantage of not being limited to provide
offload on a per port basis, GRO is now applied to whatever individual
UDP sockets are bound to. This also allows the possbility of
"application defined GRO"-- that is we can attach something like
a BPF program to a UDP socket to perfrom GRO on an application
layer protocol.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Create ila directory in preparation for supporting other hooks in the
kernel than LWT for doing ILA. This includes:
- Moving ila.c to ila/ila_lwt.c
- Splitting out some common functions into ila_common.c
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Adding new module name ila. This implements ILA translation. Light
weight tunnel redirection is used to perform the translation in
the data path. This is configured by the "ip -6 route" command
using the "encap ila <locator>" option, where <locator> is the
value to set in destination locator of the packet. e.g.
ip -6 route add 3333:0:0:1:5555:0:1:0/128 \
encap ila 2001:0:0:1 via 2401:db00:20:911a:face:0:25:0
Sets a route where 3333:0:0:1 will be overwritten by
2001:0:0:1 on output.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
With this patch, the IGMP and MLD message validation functions are moved
from the bridge code to IPv4/IPv6 multicast files. Some small
refactoring was done to enhance readibility and to iron out some
differences in behaviour between the IGMP and MLD parsing code (e.g. the
skb-cloning of MLD messages is now only done if necessary, just like the
IGMP part always did).
Finally, these IGMP and MLD message validation functions are exported so
that not only the bridge can use it but batman-adv later, too.
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: David S. Miller <davem@davemloft.net>
Functions supplied in ip6_udp_tunnel.c are only needed when IPV6 is
selected. When IPV6 is not selected, those functions are stubbed out
in udp_tunnel.h.
==================================================================
net/ipv6/ip6_udp_tunnel.c:15:5: error: redefinition of 'udp_sock_create6'
int udp_sock_create6(struct net *net, struct udp_port_cfg *cfg,
In file included from net/ipv6/ip6_udp_tunnel.c:9:0:
include/net/udp_tunnel.h:36:19: note: previous definition of 'udp_sock_create6' was here
static inline int udp_sock_create6(struct net *net, struct udp_port_cfg *cfg,
==================================================================
Fixes: fd384412e udp_tunnel: Seperate ipv6 functions into its own file
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add ip6_udp_tunnel.c for ipv6 UDP tunnel functions to avoid ifdefs
in udp_tunnel.c
Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds an IPsec protocol multiplexer for ipv6. With
this it is possible to add alternative protocol handlers, as
needed for IPsec virtual tunnel interfaces.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This patch adds IPv6 support for IPsec virtual tunnel interfaces
(vti). IPsec virtual tunnel interfaces provide a routable interface
for IPsec tunnel endpoints.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This adds the ability to send ICMPv6 echo requests without a
raw socket. The equivalent ability for ICMPv4 was added in
2011.
Instead of having separate code paths for IPv4 and IPv6, make
most of the code in net/ipv4/ping.c dual-stack and only add a
few IPv6-specific bits (like the protocol definition) to a new
net/ipv6/ping.c. Hopefully this will reduce divergence and/or
duplication of bugs in the future.
Caveats:
- Setting options via ancillary data (e.g., using IPV6_PKTINFO
to specify the outgoing interface) is not yet supported.
- There are no separate security settings for IPv4 and IPv6;
everything is controlled by /proc/net/ipv4/ping_group_range.
- The proc interface does not yet display IPv6 ping sockets
properly.
Tested with a patched copy of ping6 and using raw socket calls.
Compiles and works with all of CONFIG_IPV6={n,m,y}.
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Following patch adds icmp-registration module for ipv6. It allows
ipv6 protocol to register icmp_sender which is used for sending
ipv6 icmp msgs. This extra layer allows us to kill ipv6 dependency
for sending icmp packets.
This patch also fixes ip_tunnel compilation problem when ip_tunnel
is statically compiled in kernel but ipv6 is module
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As suggested by David, udp6_csum_init() is too big to be inlined,
move it to ipv6 static library, net/ipv6/ip6_checksum.c.
And the generic csum_ipv6_magic() too.
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The following commit breaks IPv6 TCP transmission for me:
Commit 75fe83c322
Author: Vlad Yasevich <vyasevic@redhat.com>
Date: Fri Nov 16 09:41:21 2012 +0000
ipv6: Preserve ipv6 functionality needed by NET
This patch fixes the typo "ipv6_offload" which should be
"ipv6-offload".
I don't know why not including the offload modules should
break TCP. Disabling all offload options on the NIC didn't
help. Outgoing pulseaudio traffic kept stalling.
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Some pieces of network use core pieces of IPv6 stack. Keep
them available while letting new GSO offload pieces depend
on CONFIG_INET.
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sing GSO support is now separate, pull it out of the module
and make it its own init call.
Remove the cleanup functions as they are no longer called.
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
UDP offload needs some additional functions to be in the static kernel
for it work correclty. Move those functions into the core.
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move the exthdr offload functionality into a separeate
file in preparate for moving it out of the module
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull UDP GSO code into a separate file in preparation for moving
the code out of the module.
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull TCPv6 offload functionality into its won file in preparation
for moving it out of the module.
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Separate IPv6 offload functionality into its own file
in preparation for the move out of the module
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commit db1ed684f6 ("[IPV6]
UDP: Rename IPv6 UDP files."), commit
8be8af8fa4 ("[IPV4] UDP: Move
IPv4-specific bits to other file.") and commit
e898d4db27 ("[UDP]: Allow users to
configure UDP-Lite.").
First, udplite is of such small cost, and it is a core protocol just
like TCP and normal UDP are.
We spent enormous amounts of effort to make udplite share as much code
with core UDP as possible. All of that work is less valuable if we're
just going to slap a config option on udplite support.
It is also causing build failures, as reported on linux-next, showing
that the changeset was not tested very well. In fact, this is the
second build failure resulting from the udplite change.
Finally, the config options provided was a bool, instead of a modular
option. Meaning the udplite code does not even get build tested
by allmodconfig builds, and furthermore the user is not presented
with a reasonable modular build option which is particularly needed
by distribution vendors.
Signed-off-by: David S. Miller <davem@davemloft.net>
Updated to incorporate Eric's suggestion of using a per cpu buffer
rather than allocating on the stack. Just a two line change, but will
resend in it's entirety.
Signed-off-by: Glenn Griffin <ggriffin.kernel@gmail.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Since this file is entirely enclosed with the
#ifdef CONFIG_SYSCTL/#endif pair, it's OK to move this
CONFIG_ into a Makefile.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Policy table is implemented as an RCU linear list since we do not expect
large list nor frequent updates.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch makes MIPv6 loadable module named "mip6".
Here is a modprobe.conf(5) example to load it automatically
when user application uses XFRM state for MIPv6:
alias xfrm-type-10-43 mip6
alias xfrm-type-10-60 mip6
Some MIPv6 feature is not included by this modular, however,
it should not be affected to other features like either IPsec
or IPv6 with and without the patch.
We may discuss XFRM, MH (RAW socket) and ancillary data/sockopt
separately for future work.
Loadable features:
* MH receiving check (to send ICMP error back)
* RO header parsing and building (i.e. RH2 and HAO in DSTOPTS)
* XFRM policy/state database handling for RO
These are NOT covered as loadable:
* Home Address flags and its rule on source address selection
* XFRM sub policy (depends on its own kernel option)
* XFRM functions to receive RO as IPv6 extension header
* MH sending/receiving through raw socket if user application
opens it (since raw socket allows to do so)
* RH2 sending as ancillary data
* RH2 operation with setsockopt(2)
Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch moves the non-proc SNMP code into addrconf.c and reuses
IPv4 SNMP code where applicable.
As a result we can skip proc.o if /proc is disabled.
Note that I've made a number of functions static since they're only
used by addrconf.c for now. If they ever get used elsewhere we can
always remove the static.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is a revision of the previously submitted patch, which alters
the way files are organized and compiled in the following manner:
* UDP and UDP-Lite now use separate object files
* source file dependencies resolved via header files
net/ipv{4,6}/udp_impl.h
* order of inclusion files in udp.c/udplite.c adapted
accordingly
[NET/IPv4]: Support for the UDP-Lite protocol (RFC 3828)
This patch adds support for UDP-Lite to the IPv4 stack, provided as an
extension to the existing UDPv4 code:
* generic routines are all located in net/ipv4/udp.c
* UDP-Lite specific routines are in net/ipv4/udplite.c
* MIB/statistics support in /proc/net/snmp and /proc/net/udplite
* shared API with extensions for partial checksum coverage
[NET/IPv6]: Extension for UDP-Lite over IPv6
It extends the existing UDPv6 code base with support for UDP-Lite
in the same manner as per UDPv4. In particular,
* UDPv6 generic and shared code is in net/ipv6/udp.c
* UDP-Litev6 specific extensions are in net/ipv6/udplite.c
* MIB/statistics support in /proc/net/snmp6 and /proc/net/udplite6
* support for IPV6_ADDRFORM
* aligned the coding style of protocol initialisation with af_inet6.c
* made the error handling in udpv6_queue_rcv_skb consistent;
to return `-1' on error on all error cases
* consolidation of shared code
[NET]: UDP-Lite Documentation and basic XFRM/Netfilter support
The UDP-Lite patch further provides
* API documentation for UDP-Lite
* basic xfrm support
* basic netfilter support for IPv4 and IPv6 (LOG target)
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch removes the driver of the IPv6-in-IPv4 tunnel driver (sit)
from the IPv6 module. It adds an option to Kconfig which makes it
possible to compile it as a seperate module.
Signed-off-by: Joerg Roedel <joro-lkml@zlug.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch introduces the BEET mode (Bound End-to-End Tunnel) with as
specified by the ietf draft at the following link:
http://www.ietf.org/internet-drafts/draft-nikander-esp-beet-mode-06.txt
The patch provides only single family support (i.e. inner family =
outer family).
Signed-off-by: Diego Beltrami <diego.beltrami@gmail.com>
Signed-off-by: Miika Komu <miika@iki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Abhinav Pathak <abhinav.pathak@hiit.fi>
Signed-off-by: Jeff Ahrenholz <ahrenholz@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add routing header type 2 transformation for Mobile IPv6.
Based on MIPL2 kernel patch.
Signed-off-by: Noriaki TAKAMIYA <takamiya@po.ntts.co.jp>
Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Route optimization is used with routing header and destination options
header for Mobile IPv6.
At outbound it makes header space like IPsec transport. At inbound it
does nothing because exhdrs.c functions have responsibility to update
skbuff information for these headers.
Signed-off-by: Masahide NAKAMURA <nakam@linux-ipv6.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Adds support for policy routing rules including a new
local table for routes with a local destination.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds the structure xfrm_mode. It is meant to represent
the operations carried out by transport/tunnel modes.
By doing this we allow additional encapsulation modes to be added
without clogging up the xfrm_input/xfrm_output paths.
Candidate modes include 4-to-6 tunnel mode, 6-to-4 tunnel mode, and
BEET modes.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Basically this patch moves the generic tunnel protocol stuff out of
xfrm4_tunnel/xfrm6_tunnel and moves it into the new files of tunnel4.c
and tunnel6 respectively.
The reason for this is that the problem that Hugo uncovered is only
the tip of the iceberg. The real problem is that when we removed the
dependency of ipip on xfrm4_tunnel we didn't really consider the module
case at all.
For instance, as it is it's possible to build both ipip and xfrm4_tunnel
as modules and if the latter is loaded then ipip simply won't load.
After considering the alternatives I've decided that the best way out of
this is to restore the dependency of ipip on the non-xfrm-specific part
of xfrm4_tunnel. This is acceptable IMHO because the intention of the
removal was really to be able to use ipip without the xfrm subsystem.
This is still preserved by this patch.
So now both ipip/xfrm4_tunnel depend on the new tunnel4.c which handles
the arbitration between the two. The order of processing is determined
by a simple integer which ensures that ipip gets processed before
xfrm4_tunnel.
The situation for ICMP handling is a little bit more complicated since
we may not have enough information to determine who it's for. It's not
a big deal at the moment since the xfrm ICMP handlers are basically
no-ops. In future we can deal with this when we look at ICMP caching
in general.
The user-visible change to this is the removal of the TUNNEL Kconfig
prompts. This makes sense because it can only be used through IPCOMP
as it stands.
The addition of the new modules shouldn't introduce any problems since
module dependency will cause them to be loaded.
Oh and I also turned some unnecessary pskb's in IPv6 related to this
patch to skb's.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Also, drop __exit marker from ipv6_netfilter_fini() as this
can be invoked from inet6_init() error handling paths.
Based upon a report from Stephen Hemminger.
Signed-off-by: David S. Miller <davem@davemloft.net>
David Lebrun