Pablo Neira Ayuso says:
====================
Netfilter fixes for net
1) Fix bogus compilter warning in nfnetlink_queue, from Florian Westphal.
2) Don't run conntrack on vrf with !dflt qdisc, from Nicolas Dichtel.
3) Fix nft_pipapo bucket load in AVX2 lookup routine for six 8-bit
groups, from Stefano Brivio.
4) Break rule evaluation on malformed TCP options.
5) Use socat instead of nc in selftests/netfilter/nft_zones_many.sh,
also from Florian
6) Fix KCSAN data-race in conntrack timeout updates, from Eric Dumazet.
* git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf:
netfilter: conntrack: annotate data-races around ct->timeout
selftests: netfilter: switch zone stress to socat
netfilter: nft_exthdr: break evaluation if setting TCP option fails
selftests: netfilter: Add correctness test for mac,net set type
nft_set_pipapo: Fix bucket load in AVX2 lookup routine for six 8-bit groups
vrf: don't run conntrack on vrf with !dflt qdisc
netfilter: nfnetlink_queue: silence bogus compiler warning
====================
Link: https://lore.kernel.org/r/20211209000847.102598-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
After the below patch, the conntrack attached to skb is set to "notrack" in
the context of vrf device, for locally generated packets.
But this is true only when the default qdisc is set to the vrf device. When
changing the qdisc, notrack is not set anymore.
In fact, there is a shortcut in the vrf driver, when the default qdisc is
set, see commit dcdd43c41e ("net: vrf: performance improvements for
IPv4") for more details.
This patch ensures that the behavior is always the same, whatever the qdisc
is.
To demonstrate the difference, a new test is added in conntrack_vrf.sh.
Fixes: 8c9c296adf ("vrf: run conntrack only in context of lower/physdev for locally generated packets")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Florian Westphal <fw@strlen.de>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
IPCB/IP6CB need to be initialized when processing outbound v4 or v6 pkts
in the codepath of vrf device xmit function so that leftover garbage
doesn't cause futher code that uses the CB to incorrectly process the
pkt.
One occasion of the issue might occur when MPLS route uses the vrf
device as the outgoing device such as when the route is added using "ip
-f mpls route add <label> dev <vrf>" command.
The problems seems to exist since day one. Hence I put the day one
commits on the Fixes tags.
Fixes: 193125dbd8 ("net: Introduce VRF device driver")
Fixes: 35402e3136 ("net: Add IPv6 support to VRF device")
Cc: stable@vger.kernel.org
Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20211130162637.3249-1-ssuryaextr@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The VRF driver invokes netfilter for output+postrouting hooks so that users
can create rules that check for 'oif $vrf' rather than lower device name.
This is a problem when NAT rules are configured.
To avoid any conntrack involvement in round 1, tag skbs as 'untracked'
to prevent conntrack from picking them up.
This gets cleared before the packet gets handed to the ip stack so
conntrack will be active on the second iteration.
One remaining issue is that a rule like
output ... oif $vrfname notrack
won't propagate to the second round because we can't tell
'notrack set via ruleset' and 'notrack set by vrf driver' apart.
However, this isn't a regression: the 'notrack' removal happens
instead of unconditional nf_reset_ct().
I'd also like to avoid leaking more vrf specific conditionals into the
netfilter infra.
For ingress, conntrack has already been done before the packet makes it
to the vrf driver, with this patch egress does connection tracking with
lower/physical device as well.
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commit 09e856d54b.
When an interface is enslaved in a VRF, prerouting conntrack hook is
called twice: once in the context of the original input interface, and
once in the context of the VRF interface. If no special precausions are
taken, this leads to creation of two conntrack entries instead of one,
and breaks SNAT.
Commit above was intended to avoid creation of extra conntrack entries
when input interface is enslaved in a VRF. It did so by resetting
conntrack related data associated with the skb when it enters VRF context.
However it breaks netfilter operation. Imagine a use case when conntrack
zone must be assigned based on the original input interface, rather than
VRF interface (that would make original interfaces indistinguishable). One
could create netfilter rules similar to these:
chain rawprerouting {
type filter hook prerouting priority raw;
iif realiface1 ct zone set 1 return
iif realiface2 ct zone set 2 return
}
This works before the mentioned commit, but not after: zone assignment
is "forgotten", and any subsequent NAT or filtering that is dependent
on the conntrack zone does not work.
Here is a reproducer script that demonstrates the difference in behaviour.
==========
#!/bin/sh
# This script demonstrates unexpected change of nftables behaviour
# caused by commit 09e856d54b ""vrf: Reset skb conntrack
# connection on VRF rcv"
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=09e856d54bda5f288ef8437a90ab2b9b3eab83d1
#
# Before the commit, it was possible to assign conntrack zone to a
# packet (or mark it for `notracking`) in the prerouting chanin, raw
# priority, based on the `iif` (interface from which the packet
# arrived).
# After the change, # if the interface is enslaved in a VRF, such
# assignment is lost. Instead, assignment based on the `iif` matching
# the VRF master interface is honored. Thus it is impossible to
# distinguish packets based on the original interface.
#
# This script demonstrates this change of behaviour: conntrack zone 1
# or 2 is assigned depending on the match with the original interface
# or the vrf master interface. It can be observed that conntrack entry
# appears in different zone in the kernel versions before and after
# the commit.
IPIN=172.30.30.1
IPOUT=172.30.30.2
PFXL=30
ip li sh vein >/dev/null 2>&1 && ip li del vein
ip li sh tvrf >/dev/null 2>&1 && ip li del tvrf
nft list table testct >/dev/null 2>&1 && nft delete table testct
ip li add vein type veth peer veout
ip li add tvrf type vrf table 9876
ip li set veout master tvrf
ip li set vein up
ip li set veout up
ip li set tvrf up
/sbin/sysctl -w net.ipv4.conf.veout.accept_local=1
/sbin/sysctl -w net.ipv4.conf.veout.rp_filter=0
ip addr add $IPIN/$PFXL dev vein
ip addr add $IPOUT/$PFXL dev veout
nft -f - <<__END__
table testct {
chain rawpre {
type filter hook prerouting priority raw;
iif { veout, tvrf } meta nftrace set 1
iif veout ct zone set 1 return
iif tvrf ct zone set 2 return
notrack
}
chain rawout {
type filter hook output priority raw;
notrack
}
}
__END__
uname -rv
conntrack -F
ping -W 1 -c 1 -I vein $IPOUT
conntrack -L
Signed-off-by: Eugene Crosser <crosser@average.org>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
To fix the "reverse-NAT" for replies.
When a packet is sent over a VRF, the POST_ROUTING hooks are called
twice: Once from the VRF interface, and once from the "actual"
interface the packet will be sent from:
1) First SNAT: l3mdev_l3_out() -> vrf_l3_out() -> .. -> vrf_output_direct()
This causes the POST_ROUTING hooks to run.
2) Second SNAT: 'ip_output()' calls POST_ROUTING hooks again.
Similarly for replies, first ip_rcv() calls PRE_ROUTING hooks, and
second vrf_l3_rcv() calls them again.
As an example, consider the following SNAT rule:
> iptables -t nat -A POSTROUTING -p udp -m udp --dport 53 -j SNAT --to-source 2.2.2.2 -o vrf_1
In this case sending over a VRF will create 2 conntrack entries.
The first is from the VRF interface, which performs the IP SNAT.
The second will run the SNAT, but since the "expected reply" will remain
the same, conntrack randomizes the source port of the packet:
e..g With a socket bound to 1.1.1.1:10000, sending to 3.3.3.3:53, the conntrack
rules are:
udp 17 29 src=2.2.2.2 dst=3.3.3.3 sport=10000 dport=53 packets=1 bytes=68 [UNREPLIED] src=3.3.3.3 dst=2.2.2.2 sport=53 dport=61033 packets=0 bytes=0 mark=0 use=1
udp 17 29 src=1.1.1.1 dst=3.3.3.3 sport=10000 dport=53 packets=1 bytes=68 [UNREPLIED] src=3.3.3.3 dst=2.2.2.2 sport=53 dport=10000 packets=0 bytes=0 mark=0 use=1
i.e. First SNAT IP from 1.1.1.1 --> 2.2.2.2, and second the src port is
SNAT-ed from 10000 --> 61033.
But when a reply is sent (3.3.3.3:53 -> 2.2.2.2:61033) only the later
conntrack entry is matched:
udp 17 29 src=2.2.2.2 dst=3.3.3.3 sport=10000 dport=53 packets=1 bytes=68 src=3.3.3.3 dst=2.2.2.2 sport=53 dport=61033 packets=1 bytes=49 mark=0 use=1
udp 17 28 src=1.1.1.1 dst=3.3.3.3 sport=10000 dport=53 packets=1 bytes=68 [UNREPLIED] src=3.3.3.3 dst=2.2.2.2 sport=53 dport=10000 packets=0 bytes=0 mark=0 use=1
And a "port 61033 unreachable" ICMP packet is sent back.
The issue is that when PRE_ROUTING hooks are called from vrf_l3_rcv(),
the skb already has a conntrack flow attached to it, which means
nf_conntrack_in() will not resolve the flow again.
This means only the dest port is "reverse-NATed" (61033 -> 10000) but
the dest IP remains 2.2.2.2, and since the socket is bound to 1.1.1.1 it's
not received.
This can be verified by logging the 4-tuple of the packet in '__udp4_lib_rcv()'.
The fix is then to reset the flow when skb is received on a VRF, to let
conntrack resolve the flow again (which now will hit the earlier flow).
To reproduce: (Without the fix "Got pkt_to_nat_port" will not be printed by
running 'bash ./repro'):
$ cat run_in_A1.py
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
from scapy.all import *
import argparse
def get_packet_to_send(udp_dst_port, msg_name):
return Ether(src='11:22:33:44:55:66', dst=iface_mac)/ \
IP(src='3.3.3.3', dst='2.2.2.2')/ \
UDP(sport=53, dport=udp_dst_port)/ \
Raw(f'{msg_name}\x0012345678901234567890')
parser = argparse.ArgumentParser()
parser.add_argument('-iface_mac', dest="iface_mac", type=str, required=True,
help="From run_in_A3.py")
parser.add_argument('-socket_port', dest="socket_port", type=str,
required=True, help="From run_in_A3.py")
parser.add_argument('-v1_mac', dest="v1_mac", type=str, required=True,
help="From script")
args, _ = parser.parse_known_args()
iface_mac = args.iface_mac
socket_port = int(args.socket_port)
v1_mac = args.v1_mac
print(f'Source port before NAT: {socket_port}')
while True:
pkts = sniff(iface='_v0', store=True, count=1, timeout=10)
if 0 == len(pkts):
print('Something failed, rerun the script :(', flush=True)
break
pkt = pkts[0]
if not pkt.haslayer('UDP'):
continue
pkt_sport = pkt.getlayer('UDP').sport
print(f'Source port after NAT: {pkt_sport}', flush=True)
pkt_to_send = get_packet_to_send(pkt_sport, 'pkt_to_nat_port')
sendp(pkt_to_send, '_v0', verbose=False) # Will not be received
pkt_to_send = get_packet_to_send(socket_port, 'pkt_to_socket_port')
sendp(pkt_to_send, '_v0', verbose=False)
break
$ cat run_in_A2.py
import socket
import netifaces
print(f"{netifaces.ifaddresses('e00000')[netifaces.AF_LINK][0]['addr']}",
flush=True)
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_BINDTODEVICE,
str('vrf_1' + '\0').encode('utf-8'))
s.connect(('3.3.3.3', 53))
print(f'{s. getsockname()[1]}', flush=True)
s.settimeout(5)
while True:
try:
# Periodically send in order to keep the conntrack entry alive.
s.send(b'a'*40)
resp = s.recvfrom(1024)
msg_name = resp[0].decode('utf-8').split('\0')[0]
print(f"Got {msg_name}", flush=True)
except Exception as e:
pass
$ cat repro.sh
ip netns del A1 2> /dev/null
ip netns del A2 2> /dev/null
ip netns add A1
ip netns add A2
ip -n A1 link add _v0 type veth peer name _v1 netns A2
ip -n A1 link set _v0 up
ip -n A2 link add e00000 type bond
ip -n A2 link add lo0 type dummy
ip -n A2 link add vrf_1 type vrf table 10001
ip -n A2 link set vrf_1 up
ip -n A2 link set e00000 master vrf_1
ip -n A2 addr add 1.1.1.1/24 dev e00000
ip -n A2 link set e00000 up
ip -n A2 link set _v1 master e00000
ip -n A2 link set _v1 up
ip -n A2 link set lo0 up
ip -n A2 addr add 2.2.2.2/32 dev lo0
ip -n A2 neigh add 1.1.1.10 lladdr 77:77:77:77:77:77 dev e00000
ip -n A2 route add 3.3.3.3/32 via 1.1.1.10 dev e00000 table 10001
ip netns exec A2 iptables -t nat -A POSTROUTING -p udp -m udp --dport 53 -j \
SNAT --to-source 2.2.2.2 -o vrf_1
sleep 5
ip netns exec A2 python3 run_in_A2.py > x &
XPID=$!
sleep 5
IFACE_MAC=`sed -n 1p x`
SOCKET_PORT=`sed -n 2p x`
V1_MAC=`ip -n A2 link show _v1 | sed -n 2p | awk '{print $2'}`
ip netns exec A1 python3 run_in_A1.py -iface_mac ${IFACE_MAC} -socket_port \
${SOCKET_PORT} -v1_mac ${SOCKET_PORT}
sleep 5
kill -9 $XPID
wait $XPID 2> /dev/null
ip netns del A1
ip netns del A2
tail x -n 2
rm x
set +x
Fixes: 73e20b761a ("net: vrf: Add support for PREROUTING rules on vrf device")
Signed-off-by: Lahav Schlesinger <lschlesinger@drivenets.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20210815120002.2787653-1-lschlesinger@drivenets.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Unlike skb_realloc_headroom, new helper skb_expand_head
does not allocate a new skb if possible.
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Trivial conflict in net/netfilter/nf_tables_api.c.
Duplicate fix in tools/testing/selftests/net/devlink_port_split.py
- take the net-next version.
skmsg, and L4 bpf - keep the bpf code but remove the flags
and err params.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Non-ND strict packets with a source LLA go through the packet taps
again, while non-ND strict packets with other source addresses do not,
and we can see a clone of those packets on the vrf interface (we should
not). This is due to a series of changes:
Commit 6f12fa775530[1] made non-ND strict packets not being pushed again
in the packet taps. This changed with commit 205704c618af[2] for those
packets having a source LLA, as they need a lookup with the orig_iif.
The issue now is those packets do not skip the 'vrf_ip6_rcv' function to
the end (as the ones without a source LLA) and go through the check to
call packet taps again. This check was changed by commit 6f12fa775530[1]
and do not exclude non-strict packets anymore. Packets matching
'need_strict && !is_ndisc && is_ll_src' are now being sent through the
packet taps again. This can be seen by dumping packets on the vrf
interface.
Fix this by having the same code path for all non-ND strict packets and
selectively lookup with the orig_iif for those with a source LLA. This
has the effect to revert to the pre-205704c618af[2] condition, which
should also be easier to maintain.
[1] 6f12fa7755 ("vrf: mark skb for multicast or link-local as enslaved to VRF")
[2] 205704c618 ("vrf: packets with lladdr src needs dst at input with orig_iif when needs strict")
Fixes: 205704c618 ("vrf: packets with lladdr src needs dst at input with orig_iif when needs strict")
Cc: Stephen Suryaputra <ssuryaextr@gmail.com>
Reported-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Trivial conflicts in net/can/isotp.c and
tools/testing/selftests/net/mptcp/mptcp_connect.sh
scaled_ppm_to_ppb() was moved from drivers/ptp/ptp_clock.c
to include/linux/ptp_clock_kernel.h in -next so re-apply
the fix there.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
My initial goal was to fix the default MTU, which is set to 65536, ie above
the maximum defined in the driver: 65535 (ETH_MAX_MTU).
In fact, it's seems more consistent, wrt min_mtu, to set the max_mtu to
IP6_MAX_MTU (65535 + sizeof(struct ipv6hdr)) and use it by default.
Let's also, for consistency, set the mtu in vrf_setup(). This function
calls ether_setup(), which set the mtu to 1500. Thus, the whole mtu config
is done in the same function.
Before the patch:
$ ip link add blue type vrf table 1234
$ ip link list blue
9: blue: <NOARP,MASTER> mtu 65536 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/ether fa:f5:27:70:24:2a brd ff:ff:ff:ff:ff:ff
$ ip link set dev blue mtu 65535
$ ip link set dev blue mtu 65536
Error: mtu greater than device maximum.
Fixes: 5055376a3b ("net: vrf: Fix ping failed when vrf mtu is set to 0")
CC: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
xdp_return_frame_bulk() needs to pass a xdp_buff
to __xdp_return().
strlcpy got converted to strscpy but here it makes no
functional difference, so just keep the right code.
Conflicts:
net/netfilter/nf_tables_api.c
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The vrf_add_mac_header_if_unset() is defined within a conditional
compilation block which depends on the CONFIG_IPV6 macro.
However, the vrf_add_mac_header_if_unset() needs to be called also by IPv4
related code and when the CONFIG_IPV6 is not set, this function is missing.
As a consequence, the build process stops reporting the error:
ERROR: implicit declaration of function 'vrf_add_mac_header_if_unset'
The problem is solved by *only* moving functions
vrf_add_mac_header_if_unset() and vrf_prepare_mac_header() out of the
conditional block.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 0489390882 ("vrf: add mac header for tunneled packets when sniffer is attached")
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20201208175210.8906-1-andrea.mayer@uniroma2.it
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Depending on the order of the routes to fe80::/64 are installed on the
VRF table, the NS for the source link-local address of the originator
might be sent to the wrong interface.
This patch ensures that packets with link-local addr source is doing a
lookup with the orig_iif when the destination addr indicates that it
is strict.
Add the reproducer as a use case in self test script fcnal-test.sh.
Fixes: b4869aa2f8 ("net: vrf: ipv6 support for local traffic to local addresses")
Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20201204030604.18828-1-ssuryaextr@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Before this patch, a sniffer attached to a VRF used as the receiving
interface of L3 tunneled packets detects them as malformed packets and
it complains about that (i.e.: tcpdump shows bogus packets).
The reason is that a tunneled L3 packet does not carry any L2
information and when the VRF is set as the receiving interface of a
decapsulated L3 packet, no mac header is currently set or valid.
Therefore, the purpose of this patch consists of adding a MAC header to
any packet which is directly received on the VRF interface ONLY IF:
i) a sniffer is attached on the VRF and ii) the mac header is not set.
In this case, the mac address of the VRF is copied in both the
destination and the source address of the ethernet header. The protocol
type is set either to IPv4 or IPv6, depending on which L3 packet is
received.
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
VRF devices use an optimized direct path on output if a default qdisc
is involved, calling Netfilter hooks directly. This path, however, does
not consider Netfilter rules completing asynchronously, such as with
NFQUEUE. The Netfilter okfn() is called for asynchronously accepted
packets, but the VRF never passes that packet down the stack to send
it out over the slave device. Using the slower redirect path for this
seems not feasible, as we do not know beforehand if a Netfilter hook
has asynchronously completing rules.
Fix the use of asynchronously completing Netfilter rules in OUTPUT and
POSTROUTING by using a special completion function that additionally
calls dst_output() to pass the packet down the stack. Also, slightly
adjust the use of nf_reset_ct() so that is called in the asynchronous
case, too.
Fixes: dcdd43c41e ("net: vrf: performance improvements for IPv4")
Fixes: a9ec54d1b0 ("net: vrf: performance improvements for IPv6")
Signed-off-by: Martin Willi <martin@strongswan.org>
Link: https://lore.kernel.org/r/20201106073030.3974927-1-martin@strongswan.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Randy reported compile failure when CONFIG_SYSCTL is not set/enabled:
ERROR: modpost: "sysctl_vals" [drivers/net/vrf.ko] undefined!
Fix by splitting out the sysctl init and cleanup into helpers that
can be set to do nothing when CONFIG_SYSCTL is disabled. In addition,
move vrf_strict_mode and vrf_strict_mode_change to above
vrf_shared_table_handler (code move only) and wrap all of it
in the ifdef CONFIG_SYSCTL.
Update the strict mode tests to check for the existence of the
/proc/sys entry.
Fixes: 33306f1aaf ("vrf: add sysctl parameter for strict mode")
Cc: Andrea Mayer <andrea.mayer@uniroma2.it>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David Ahern <dsahern@kernel.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: David S. Miller <davem@davemloft.net>
During the initialization phase of the VRF module, the callback for table
to VRF device lookup is registered in l3mdev.
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add net.vrf.strict_mode sysctl parameter.
When net.vrf.strict_mode=0 (default) it is possible to associate multiple
VRF devices to the same table. Conversely, when net.vrf.strict_mode=1 a
table can be associated to a single VRF device.
When switching from net.vrf.strict_mode=0 to net.vrf.strict_mode=1, a check
is performed to verify that all tables have at most one VRF associated,
otherwise the switch is not allowed.
The net.vrf.strict_mode parameter is per network namespace.
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add the data structures and the processing logic to keep track of the
associations between VRF devices and routing tables.
When a VRF is instantiated, it needs to refer to a given routing table.
For each table, we explicitly keep track of the existing VRFs that refer to
the table.
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>
