It's currently possible to bridge Ethernet tunnels carrying IP
packets directly to external interfaces without assigning them
addresses and routes on the bridged network itself: this is the case
for UDP tunnels bridged with a standard bridge or by Open vSwitch.
PMTU discovery is currently broken with those configurations, because
the encapsulation effectively decreases the MTU of the link, and
while we are able to account for this using PMTU discovery on the
lower layer, we don't have a way to relay ICMP or ICMPv6 messages
needed by the sender, because we don't have valid routes to it.
On the other hand, as a tunnel endpoint, we can't fragment packets
as a general approach: this is for instance clearly forbidden for
VXLAN by RFC 7348, section 4.3:
VTEPs MUST NOT fragment VXLAN packets. Intermediate routers may
fragment encapsulated VXLAN packets due to the larger frame size.
The destination VTEP MAY silently discard such VXLAN fragments.
The same paragraph recommends that the MTU over the physical network
accomodates for encapsulations, but this isn't a practical option for
complex topologies, especially for typical Open vSwitch use cases.
Further, it states that:
Other techniques like Path MTU discovery (see [RFC1191] and
[RFC1981]) MAY be used to address this requirement as well.
Now, PMTU discovery already works for routed interfaces, we get
route exceptions created by the encapsulation device as they receive
ICMP Fragmentation Needed and ICMPv6 Packet Too Big messages, and
we already rebuild those messages with the appropriate MTU and route
them back to the sender.
Add the missing bits for bridged cases:
- checks in skb_tunnel_check_pmtu() to understand if it's appropriate
to trigger a reply according to RFC 1122 section 3.2.2 for ICMP and
RFC 4443 section 2.4 for ICMPv6. This function is already called by
UDP tunnels
- a new function generating those ICMP or ICMPv6 replies. We can't
reuse icmp_send() and icmp6_send() as we don't see the sender as a
valid destination. This doesn't need to be generic, as we don't
cover any other type of ICMP errors given that we only provide an
encapsulation function to the sender
While at it, make the MTU check in skb_tunnel_check_pmtu() accurate:
we might receive GSO buffers here, and the passed headroom already
includes the inner MAC length, so we don't have to account for it
a second time (that would imply three MAC headers on the wire, but
there are just two).
This issue became visible while bridging IPv6 packets with 4500 bytes
of payload over GENEVE using IPv4 with a PMTU of 4000. Given the 50
bytes of encapsulation headroom, we would advertise MTU as 3950, and
we would reject fragmented IPv6 datagrams of 3958 bytes size on the
wire. We're exclusively dealing with network MTU here, though, so we
could get Ethernet frames up to 3964 octets in that case.
v2:
- moved skb_tunnel_check_pmtu() to ip_tunnel_core.c (David Ahern)
- split IPv4/IPv6 functions (David Ahern)
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In multiproto mode, bareudp_xmit() accepts sending multicast MPLS and
IPv6 packets regardless of the bareudp ethertype. In practice, this
let an IP tunnel send multicast MPLS packets, or an MPLS tunnel send
IPv6 packets.
We need to restrict the test further, so that the multiproto mode only
enables
* IPv6 for IPv4 tunnels,
* or multicast MPLS for unicast MPLS tunnels.
To improve clarity, the protocol validation is moved to its own
function, where each logical test has its own condition.
v2: s/ntohs/htons/
Fixes: 4b5f67232d ("net: Special handling for IP & MPLS.")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The commit fe80536acf ("bareudp: Added attribute to enable & disable
rx metadata collection") breaks the the original(5.7) default behavior of
bareudp module to collect RX metadadata at the receive. It was added to
avoid the crash at the kernel neighbour subsytem when packet with metadata
from bareudp is processed. But it is no more needed as the
commit 394de110a7 ("net: Added pointer check for
dst->ops->neigh_lookup in dst_neigh_lookup_skb") solves this crash.
Fixes: fe80536acf ("bareudp: Added attribute to enable & disable rx metadata collection")
Signed-off-by: Martin Varghese <martin.varghese@nokia.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Metadata need not be collected in receive if the packet from bareudp
device is not targeted to openvswitch.
Signed-off-by: Martin <martin.varghese@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Code to handle multiproto configuration is missing.
Fixes: 4b5f67232d ("net: Special handling for IP & MPLS")
Signed-off-by: Martin <martin.varghese@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Code to initialize the conf structure while gathering the configuration
of the device was missing.
Fixes: 571912c69f ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Signed-off-by: Martin <martin.varghese@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
clang points out that building without IPv6 would lead to returning
an uninitialized variable if a packet with family!=AF_INET is
passed into bareudp_udp_encap_recv():
drivers/net/bareudp.c:139:6: error: variable 'err' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
if (family == AF_INET)
^~~~~~~~~~~~~~~~~
drivers/net/bareudp.c:146:15: note: uninitialized use occurs here
if (unlikely(err)) {
^~~
include/linux/compiler.h:78:42: note: expanded from macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
drivers/net/bareudp.c:139:2: note: remove the 'if' if its condition is always true
if (family == AF_INET)
^~~~~~~~~~~~~~~~~~~~~~
This cannot happen in practice, so change the condition in a way that
gcc sees the IPv4 case as unconditionally true here.
For consistency, change all the similar constructs in this file the
same way, using "if(IS_ENABLED())" instead of #if IS_ENABLED()".
Fixes: 571912c69f ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reverted commit "2baecda bareudp: remove unnecessary udp_encap_enable() in
bareudp_socket_create()"
An explicit call to udp_encap_enable is needed as the setup_udp_tunnel_sock
does not call udp_encap_enable if the if the socket is of type v6.
Bareudp device uses v6 socket to receive v4 & v6 traffic
CC: Taehee Yoo <ap420073@gmail.com>
Fixes: 2baecda37f ("bareudp: remove unnecessary udp_encap_enable() in bareudp_socket_create()")
Signed-off-by: Martin Varghese <martin.varghese@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the current code, udp_encap_enable() is called in
bareudp_socket_create().
But, setup_udp_tunnel_sock() internally calls udp_encap_enable().
So, udp_encap_enable() is unnecessary.
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When bareudp netlink command fails, it doesn't print any error message.
So, users couldn't know the exact reason.
In order to tell the exact reason to the user, the extack error message
is used in this patch.
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the current bareudp code, there is no module alias.
So, RTNL couldn't load bareudp module automatically.
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/bareudp.c: In function 'bareudp_xmit_skb':
drivers/net/bareudp.c:346:9: warning: 'err' may be used uninitialized in this function [-Wmaybe-uninitialized]
346 | return err;
| ^~~
drivers/net/bareudp.c: In function 'bareudp6_xmit_skb':
drivers/net/bareudp.c:407:9: warning: 'err' may be used uninitialized in this function [-Wmaybe-uninitialized]
407 | return err;
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Special handling is needed in bareudp module for IP & MPLS as they
support more than one ethertypes.
MPLS has 2 ethertypes. 0x8847 for MPLS unicast and 0x8848 for MPLS multicast.
While decapsulating MPLS packet from UDP packet the tunnel destination IP
address is checked to determine the ethertype. The ethertype of the packet
will be set to 0x8848 if the tunnel destination IP address is a multicast
IP address. The ethertype of the packet will be set to 0x8847 if the
tunnel destination IP address is a unicast IP address.
IP has 2 ethertypes.0x0800 for IPV4 and 0x86dd for IPv6. The version
field of the IP header tunnelled will be checked to determine the ethertype.
This special handling to tunnel additional ethertypes will be disabled
by default and can be enabled using a flag called multiproto. This flag can
be used only with ethertypes 0x8847 and 0x0800.
Signed-off-by: Martin Varghese <martin.varghese@nokia.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The Bareudp tunnel module provides a generic L3 encapsulation
tunnelling module for tunnelling different protocols like MPLS,
IP,NSH etc inside a UDP tunnel.
Signed-off-by: Martin Varghese <martin.varghese@nokia.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
