RFC 4182 s2 states that if an IPv4 Explicit NULL label is the only
label on the stack, then after popping the resulting packet must be
treated as a IPv4 packet and forwarded based on the IPv4 header. The
same is true for IPv6 Explicit NULL with an IPv6 packet following.
Therefore, when installing the IPv4/IPv6 Explicit NULL label routes,
add an attribute that specifies the expected payload type for use at
forwarding time for determining the type of the encapsulated packet
instead of inspecting the first nibble of the packet.
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds null dev check for the 'cfg->rc_via_table ==
NEIGH_LINK_TABLE or dev_get_by_index() failed' case
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We recently changed this code from returning NULL to returning ERR_PTR.
There are some left over NULL assignments which we can remove. We can
preserve the error code from ip_route_output() instead of always
returning -ENODEV. Also these functions use a mix of gotos and direct
returns. There is no cleanup necessary so I changed the gotos to
direct returns.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Acked-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In multiple locations there are checks for whether the label in hand
is a reserved label or not using the arbritray value of 16. Factor
this out into a #define for better maintainability and for
documentation.
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Undefined reference to ip6_route_output and ip_route_output
was reported with CONFIG_INET=n and CONFIG_IPV6=n.
This patch uses ipv6_stub_impl.ipv6_dst_lookup instead of
ip6_route_output. And wraps affected code under
IS_ENABLED(CONFIG_INET) and IS_ENABLED(CONFIG_IPV6).
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reported-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
fix for:
net/mpls/mpls_iptunnel.c:73:19: sparse: incompatible types in comparison
expression (different address spaces)
remove incorrect rcu_dereference possibly left over from
earlier revisions of the code.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If user did not specify an oif, try and get it from the via address.
If failed to get device, return with -ENODEV.
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This implementation uses lwtunnel infrastructure to register
hooks for mpls tunnel encaps.
It picks cues from iptunnel_encaps infrastructure and previous
mpls iptunnel RFC patches from Eric W. Biederman and Robert Shearman
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If a device is renamed and the original name is subsequently reused
for a new device, the following warning is generated:
sysctl duplicate entry: /net/mpls/conf/veth0//input
CPU: 3 PID: 1379 Comm: ip Not tainted 4.1.0-rc4+ #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
0000000000000000 0000000000000000 ffffffff81566aaf 0000000000000000
ffffffff81236279 ffff88002f7d7f00 0000000000000000 ffff88000db336d8
ffff88000db33698 0000000000000005 ffff88002e046000 ffff8800168c9280
Call Trace:
[<ffffffff81566aaf>] ? dump_stack+0x40/0x50
[<ffffffff81236279>] ? __register_sysctl_table+0x289/0x5a0
[<ffffffffa051a24f>] ? mpls_dev_notify+0x1ff/0x300 [mpls_router]
[<ffffffff8108db7f>] ? notifier_call_chain+0x4f/0x70
[<ffffffff81470e72>] ? register_netdevice+0x2b2/0x480
[<ffffffffa0524748>] ? veth_newlink+0x178/0x2d3 [veth]
[<ffffffff8147f84c>] ? rtnl_newlink+0x73c/0x8e0
[<ffffffff8147f27a>] ? rtnl_newlink+0x16a/0x8e0
[<ffffffff81459ff2>] ? __kmalloc_reserve.isra.30+0x32/0x90
[<ffffffff8147ccfd>] ? rtnetlink_rcv_msg+0x8d/0x250
[<ffffffff8145b027>] ? __alloc_skb+0x47/0x1f0
[<ffffffff8149badb>] ? __netlink_lookup+0xab/0xe0
[<ffffffff8147cc70>] ? rtnetlink_rcv+0x30/0x30
[<ffffffff8149e7a0>] ? netlink_rcv_skb+0xb0/0xd0
[<ffffffff8147cc64>] ? rtnetlink_rcv+0x24/0x30
[<ffffffff8149df17>] ? netlink_unicast+0x107/0x1a0
[<ffffffff8149e4be>] ? netlink_sendmsg+0x50e/0x630
[<ffffffff8145209c>] ? sock_sendmsg+0x3c/0x50
[<ffffffff81452beb>] ? ___sys_sendmsg+0x27b/0x290
[<ffffffff811bd258>] ? mem_cgroup_try_charge+0x88/0x110
[<ffffffff811bd5b6>] ? mem_cgroup_commit_charge+0x56/0xa0
[<ffffffff811d7700>] ? do_filp_open+0x30/0xa0
[<ffffffff8145336e>] ? __sys_sendmsg+0x3e/0x80
[<ffffffff8156c3f2>] ? system_call_fastpath+0x16/0x75
Fix this by unregistering the previous sysctl table (registered for
the path containing the original device name) and re-registering the
table for the path containing the new device name.
Fixes: 37bde79979 ("mpls: Per-device enabling of packet input")
Reported-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The mpls device is used in an RCU read context without a lock being
held. As the memory is freed without waiting for the RCU grace period
to elapse, the freed memory could still be in use.
Address this by using kfree_rcu to free the memory for the mpls device
after the RCU grace period has elapsed.
Fixes: 03c57747a7 ("mpls: Per-device MPLS state")
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When we scan a packet for GRO processing, we want to see the most
common packet types in the front of the offload_base list.
So add a priority field so we can handle this properly.
IPv4/IPv6 get the highest priority with the implicit zero priority
field.
Next comes ethernet with a priority of 10, and then we have the MPLS
types with a priority of 15.
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since these are now visible to userspace it is nice to be consistent
with BSD (sys/netmpls/mpls.h in netBSD).
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Move to include/uapi/linux/mpls.h to be externally visibile.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The reserved implicit-NULL label isn't allowed to appear in the label
stack for packets, so make it an error for the control plane to
specify it as an outgoing label.
Suggested-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
An MPLS network is a single trust domain where the edges must be in
control of what labels make their way into the core. The simplest way
of ensuring this is for the edge device to always impose the labels,
and not allow forward labeled traffic from untrusted neighbours. This
is achieved by allowing a per-device configuration of whether MPLS
traffic input from that interface should be processed or not.
To be secure by default, the default state is changed to MPLS being
disabled on all interfaces unless explicitly enabled and no global
option is provided to change the default. Whilst this differs from
other protocols (e.g. IPv6), network operators are used to explicitly
enabling MPLS forwarding on interfaces, and with the number of links
to the MPLS core typically fairly low this doesn't present too much of
a burden on operators.
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add per-device MPLS state to supported interfaces. Use the presence of
this state in mpls_route_add to determine that this is a supported
interface.
Use the presence of mpls_dev to drop packets that arrived on an
unsupported interface - previously they were allowed through.
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reobert Shearman noticed that mpls_egress is failing to verify that
the bytes to be examined are in fact present in the packet before
mpls_egress reads those bytes.
As suggested by David Miller reduce this to a single pskb_may_pull
call so that we don't do unnecessary work in the fast path.
Reported-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CONFIG_MPLS=m doesn't result in a kernel module being built because it
applies to the net/mpls directory, rather than to .o files.
So revert the MPLS menuitem to being a boolean and make MPLS_GSO and
MPLS_ROUTING tristates to allow mpls_gso and mpls_router modules to be
produced as desired.
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove a little bit of unnecessary work when transmitting a packet with
neigh_packet_xmit. Use the neighbour table index not the address family
as a parameter.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
According to RFC3032 section 2.4.2 packets with an outgoing
ttl of 0 MUST NOT be forwarded. According to section 2.4.1
an outgoing TTL of 0 comes from an incomming TTL <= 1.
Therefore any packets that is received with a ttl <= 1 should
not have it's ttl decremented and forwarded.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Sparse was generating a lot of warnings mostly from missing annotations
in the code. Add missing annotations and in a few cases tweak the code
for performance by moving work before loops.
This also fixes a problematic ommision of rcu_assign_pointer and
rcu_dereference.
Hopefully with complete rcu annotations any new rcu errors will stick
out like a sore thumb.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
*Blink* I got the argument order wrong to kzalloc and the
code was working properly when tested. *Blink*
Fix that.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If the nla length is less than 2 then the nla data could be accessed
beyond the accessible bounds. So ensure that the nla is big enough to
at least read the via_family before doing so. Replace magic value of
2.
Fixes: 03c0566542 ("mpls: Basic support for adding and removing routes")
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fixes this build error:
net/mpls/af_mpls.c: In function 'resize_platform_label_table':
net/mpls/af_mpls.c:767:4: error: implicit declaration of function 'vzalloc' [-Werror=implicit-function-declaration]
labels = vzalloc(size);
^
Fixes: 7720c01f3f ("mpls: Add a sysctl to control the size of the mpls label table")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Unlike IPv4 this code notifies on all cases where mpls routes
are added or removed and it never automatically removes routes.
Avoiding both the userspace confusion that is caused by omitting
route updates and the possibility of a flood of netlink traffic
when an interface goes doew.
For now reserved labels are handled automatically and userspace
is not notified.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds two new netlink routing attributes:
RTA_VIA and RTA_NEWDST.
RTA_VIA specifies the specifies the next machine to send a packet to
like RTA_GATEWAY. RTA_VIA differs from RTA_GATEWAY in that it
includes the address family of the address of the next machine to send
a packet to. Currently the MPLS code supports addresses in AF_INET,
AF_INET6 and AF_PACKET. For AF_INET and AF_INET6 the destination mac
address is acquired from the neighbour table. For AF_PACKET the
destination mac_address is specified in the netlink configuration.
I think raw destination mac address support with the family AF_PACKET
will prove useful. There is MPLS-TP which is defined to operate
on machines that do not support internet packets of any flavor. Further
seem to be corner cases where it can be useful. At this point
I don't care much either way.
RTA_NEWDST specifies the destination address to forward the packet
with. MPLS typically changes it's destination address at every hop.
For a swap operation RTA_NEWDST is specified with a length of one label.
For a push operation RTA_NEWDST is specified with two or more labels.
For a pop operation RTA_NEWDST is not specified or equivalently an emtpy
RTAN_NEWDST is specified.
Those new netlink attributes are used to implement handling of rt-netlink
RTM_NEWROUTE, RTM_DELROUTE, and RTM_GETROUTE messages, to maintain the
MPLS label table.
rtm_to_route_config parses a netlink RTM_NEWROUTE or RTM_DELROUTE message,
verify no unhandled attributes or unhandled values are present and sets
up the data structures for mpls_route_add and mpls_route_del.
I did my best to match up with the existing conventions with the caveats
that MPLS addresses are all destination-specific-addresses, and so
don't properly have a scope.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reading and writing addresses in network byte order in netlink is
traditional and I see no reason to change that. MPLS is interesting
as effectively it has variabely length addresses (the MPLS label
stack). To represent these variable length addresses in netlink
I use a valid MPLS label stack (complete with stop bit).
This achieves two things: a well defined existing format is used,
and the data can be interpreted without looking at it's length.
Not needed to look at the length to decode the variable length
network representation allows existing userspace functions
such as inet_ntop to be used without needed to change their
prototype.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
mpls_route_add and mpls_route_del implement the basic logic for adding
and removing Next Hop Label Forwarding Entries from the MPLS input
label map. The addition and subtraction is done in a way that is
consistent with how the existing routing table in Linux are
maintained. Thus all of the work to deal with NLM_F_APPEND,
NLM_F_EXCL, NLM_F_REPLACE, and NLM_F_CREATE.
Cases that are not clearly defined such as changing the interpretation
of the mpls reserved labels is not allowed.
Because it seems like the right thing to do adding an MPLS route without
specifying an input label and allowing the kernel to pick a free label
table entry is supported. The implementation is currently less than optimal
but that can be changed.
As I don't have anything else to test with only ethernet and the loopback
device are the only two device types currently supported for forwarding
MPLS over.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This sysctl gives two benefits. By defaulting the table size to 0
mpls even when compiled in and enabled defaults to not forwarding
any packets. This prevents unpleasant surprises for users.
The other benefit is that as mpls labels are allocated locally a dense
table a small dense label table may be used which saves memory and
is extremely simple and efficient to implement.
This sysctl allows userspace to choose the restrictions on the label
table size userspace applications need to cope with.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds a new Kconfig option MPLS_ROUTING.
The core of this change is the code to look at an mpls packet received
from another machine. Look that packet up in a routing table and
forward the packet on.
Support of MPLS over ATM is not considered or attempted here. This
implemntation follows RFC3032 and implements the MPLS shim header that
can pass over essentially any network.
What RFC3021 refers to as the as the Incoming Label Map (ILM) I call
net->mpls.platform_label[]. What RFC3031 refers to as the Next Label
Hop Forwarding Entry (NHLFE) I call mpls_route. Though calling it the
label fordwarding information base (lfib) might also be valid.
Further the implemntation forwards packets as described in RFC3032.
There is no need and given the original motivation for MPLS a strong
discincentive to have a flexible label forwarding path. In essence
the logic is the topmost label is read, looked up, removed, and
replaced by 0 or more new lables and the sent out the specified
interface to it's next hop.
Quite a few optional features are not implemented here. Among them
are generation of ICMP errors when the TTL is exceeded or the packet
is larger than the next hop MTU (those conditions are detected and the
packets are dropped instead of generating an icmp error). The traffic
class field is always set to 0. The implementation focuses on IP over
MPLS and does not handle egress of other kinds of protocols.
Instead of implementing coordination with the neighbour table and
sorting out how to input next hops in a different address family (for
which there is value). I was lazy and implemented a next hop mac
address instead. The code is simpler and there are flavor of MPLS
such as MPLS-TP where neither an IPv4 nor an IPv6 next hop is
appropriate so a next hop by mac address would need to be implemented
at some point.
Two new definitions AF_MPLS and PF_MPLS are exposed to userspace.
Decoding the mpls header must be done by first byeswapping a 32bit bit
endian word into the local cpu endian and then bit shifting to extract
the pieces. There is no C bit-field that can represent a wire format
mpls header on a little endian machine as the low bits of the 20bit
label wind up in the wrong half of third byte. Therefore internally
everything is deal with in cpu native byte order except when writing
to and reading from a packet.
For management simplicity if a label is configured to forward out
an interface that is down the packet is dropped early. Similarly
if an network interface is removed rt_dev is updated to NULL
(so no reference is preserved) and any packets for that label
are dropped. Keeping the label entries in the kernel allows
the kernel label table to function as the definitive source
of which labels are allocated and which are not.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This refactoring is needed to allow more than just mpls gso
support to be built into the mpls moddule.
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
They are all either written once or extremly rarely (e.g. from init
code), so we can move them to the .data..read_mostly section.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
MPLS and Tunnel GSO does not work together. Reject packet which
request such GSO.
Fixes: 0d89d2035f ("MPLS: Add limited GSO support").
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Device can export MPLS GSO support in dev->mpls_features same way
it export vlan features in dev->vlan_features. So it is safe to
remove NETIF_F_GSO_MPLS redundant flag.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Kconfig already allows mpls to be built as module. Following patch
fixes Makefile to do same.
CC: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
mpls gso handler needs to pull skb after segmenting skb.
CC: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
skb_gso_segment() has a 'features' argument representing offload features
available to the output path.
A few handlers, e.g. GRE, instead re-fetch the features of skb->dev and use
those instead of the provided ones when handing encapsulation/tunnels.
Depending on dev->hw_enc_features of the output device skb_gso_segment() can
then return NULL even when the caller has disabled all GSO feature bits,
as segmentation of inner header thinks device will take care of segmentation.
This e.g. affects the tbf scheduler, which will silently drop GRE-encap GSO skbs
that did not fit the remaining token quota as the segmentation does not work
when device supports corresponding hw offload capabilities.
Cc: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
The send_check logic was only interesting in cases of TCP offload and
UDP UFO where the checksum needed to be initialized to the pseudo
header checksum. Now we've moved that logic into the related
gso_segment functions so gso_send_check is no longer needed.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Call gso_make_checksum. This should have the benefit of using a
checksum that may have been previously computed for the packet.
This also adds NETIF_F_GSO_GRE_CSUM to differentiate devices that
offload GRE GSO with and without the GRE checksum offloaed.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now inet_gso_segment() is stackable, its relatively easy to
implement GSO/TSO support for IPIP
Performance results, when segmentation is done after tunnel
device (as no NIC is yet enabled for TSO IPIP support) :
Before patch :
lpq83:~# ./netperf -H 7.7.9.84 -Cc
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 7.7.9.84 () port 0 AF_INET
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB
87380 16384 16384 10.00 3357.88 5.09 3.70 2.983 2.167
After patch :
lpq83:~# ./netperf -H 7.7.9.84 -Cc
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 7.7.9.84 () port 0 AF_INET
Recv Send Send Utilization Service Demand
Socket Socket Message Elapsed Send Recv Send Recv
Size Size Size Time Throughput local remote local remote
bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB
87380 16384 16384 10.00 7710.19 4.52 6.62 1.152 1.687
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the case where a non-MPLS packet is received and an MPLS stack is
added it may well be the case that the original skb is GSO but the
NIC used for transmit does not support GSO of MPLS packets.
The aim of this code is to provide GSO in software for MPLS packets
whose skbs are GSO.
SKB Usage:
When an implementation adds an MPLS stack to a non-MPLS packet it should do
the following to skb metadata:
* Set skb->inner_protocol to the old non-MPLS ethertype of the packet.
skb->inner_protocol is added by this patch.
* Set skb->protocol to the new MPLS ethertype of the packet.
* Set skb->network_header to correspond to the
end of the L3 header, including the MPLS label stack.
I have posted a patch, "[PATCH v3.29] datapath: Add basic MPLS support to
kernel" which adds MPLS support to the kernel datapath of Open vSwtich.
That patch sets the above requirements in datapath/actions.c:push_mpls()
and was used to exercise this code. The datapath patch is against the Open
vSwtich tree but it is intended that it be added to the Open vSwtich code
present in the mainline Linux kernel at some point.
Features:
I believe that the approach that I have taken is at least partially
consistent with the handling of other protocols. Jesse, I understand that
you have some ideas here. I am more than happy to change my implementation.
This patch adds dev->mpls_features which may be used by devices
to advertise features supported for MPLS packets.
A new NETIF_F_MPLS_GSO feature is added for devices which support
hardware MPLS GSO offload. Currently no devices support this
and MPLS GSO always falls back to software.
Alternate Implementation:
One possible alternate implementation is to teach netif_skb_features()
and skb_network_protocol() about MPLS, in a similar way to their
understanding of VLANs. I believe this would avoid the need
for net/mpls/mpls_gso.c and in particular the calls to
__skb_push() and __skb_push() in mpls_gso_segment().
I have decided on the implementation in this patch as it should
not introduce any overhead in the case where mpls_gso is not compiled
into the kernel or inserted as a module.
MPLS GSO suggested by Jesse Gross.
Based in part on "v4 GRE: Add TCP segmentation offload for GRE"
by Pravin B Shelar.
Cc: Jesse Gross <jesse@nicira.com>
Cc: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Robert Shearman