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2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-05-30net: mpls: Make nla_get_via in af_mpls.cDavid Ahern1-2/+0
nla_get_via is only used in af_mpls.c. Remove declaration from internal.h and move up in af_mpls.c before first use. Code move only; no functional change intended. Signed-off-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-30net: mpls: Add extack messages for route add and delete failuresDavid Ahern1-1/+1
Add error messages for failures in adding and deleting mpls routes. This covers most of the annoying EINVAL errors. Signed-off-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-30net: Fill in extack for mpls lwt encapDavid Ahern1-1/+1
Fill in extack for errors in build_state for mpls lwt encap including passing extack to nla_get_labels and adding error messages for failures in it. Signed-off-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-01net: mpls: Increase max number of labels for lwt encapDavid Ahern1-0/+5
Alow users to push down more labels per MPLS encap. Similar to LSR case, move label array to the end of mpls_iptunnel_encap and allocate based on the number of labels for the route. For consistency with the LSR case, re-use the same maximum number of labels. Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-01net: mpls: bump maximum number of labelsDavid Ahern1-1/+1
Allow users to push down more labels per MPLS route. With the previous patches, no memory allocations are based on MAX_NEW_LABELS; the limit is only used to keep userspace in check. At this point MAX_NEW_LABELS is only used for mpls_route_config (copying route data from userspace) and processing nexthops looking for the max number of labels across the route spec. Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-01net: mpls: change mpls_route layoutDavid Ahern1-15/+30
Move labels to the end of mpls_nh as a 0-sized array and within mpls_route move the via for a nexthop after the mpls_nh. The new layout becomes: +----------------------+ | mpls_route | +----------------------+ | mpls_nh 0 | +----------------------+ | alignment padding | 4 bytes for odd number of labels; 0 for even +----------------------+ | via[rt_max_alen] 0 | +----------------------+ | alignment padding | via's aligned on sizeof(unsigned long) +----------------------+ | ... | +----------------------+ | mpls_nh n-1 | +----------------------+ | via[rt_max_alen] n-1 | +----------------------+ Memory allocated for nexthop + via is constant across all nexthops and their via. It is based on the maximum number of labels across all nexthops and the maximum via length. The size is saved in the mpls_route as rt_nh_size. Accessing a nexthop becomes rt->rt_nh + index * rt->rt_nh_size. The offset of the via address from a nexthop is saved as rt_via_offset so that given an mpls_nh pointer the via for that hop is simply nh + rt->rt_via_offset. With prior code, memory allocated per mpls_route with 1 nexthop: via is an ethernet address - 64 bytes via is an ipv4 address - 64 via is an ipv6 address - 72 With this patch set, memory allocated per mpls_route with 1 nexthop and 1 or 2 labels: via is an ethernet address - 56 bytes via is an ipv4 address - 56 via is an ipv6 address - 64 The 8-byte reduction is due to the previous patch; the change introduced by this patch has no impact on the size of allocations for 1 or 2 labels. Performance impact of this change was examined using network namespaces with veth pairs connecting namespaces. ns0 inserts the packet to the label-switched path using an lwt route with encap mpls. ns1 adds 1 or 2 labels depending on test, ns2 (and ns3 for 2-label test) pops the label and forwards. ns3 (or ns4) for a 2-label is the destination. Similar series of namespaces used for 2-nexthop test. Intent is to measure changes to latency (overhead in manipulating the packet) in the forwarding path. Tests used netperf with UDP_RR. IPv4: current patches 1 label, 1 nexthop 29908 30115 2 label, 1 nexthop 29071 29612 1 label, 2 nexthop 29582 29776 2 label, 2 nexthop 29086 29149 IPv6: current patches 1 label, 1 nexthop 24502 24960 2 label, 1 nexthop 24041 24407 1 label, 2 nexthop 23795 23899 2 label, 2 nexthop 23074 22959 In short, the change has no effect to a modest increase in performance. This is expected since this patch does not really have an impact on routes with 1 or 2 labels (the current limit) and 1 or 2 nexthops. Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-01net: mpls: Convert number of nexthops to u8David Ahern1-2/+3
Number of nexthops and number of alive nexthops are tracked using an unsigned int. A route should never have more than 255 nexthops so convert both to u8. Update all references and intermediate variables to consistently use u8 as well. Shrinks the size of mpls_route from 32 bytes to 24 bytes with a 2-byte hole before the nexthops. Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-01net: mpls: rt_nhn_alive and nh_flags should be accessed using READ_ONCEDavid Ahern1-0/+8
The number of alive nexthops for a route (rt->rt_nhn_alive) and the flags for a next hop (nh->nh_flags) are modified by netdev event handlers. The event handlers run with rtnl_lock held so updates are always done with the lock held. The packet path accesses the fields under the rcu lock. Since those fields can change at any moment in the packet path, both fields should be accessed using READ_ONCE. Updates to both fields should use WRITE_ONCE. Update mpls_select_multipath (packet path) and mpls_ifdown and mpls_ifup (event handlers) accordingly. Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-13mpls: allow TTL propagation to IP packets to be configuredRobert Shearman1-0/+7
Provide the ability to control on a per-route basis whether the TTL value from an MPLS packet is propagated to an IPv4/IPv6 packet when the last label is popped as per the theoretical model in RFC 3443 through a new route attribute, RTA_TTL_PROPAGATE which can be 0 to mean disable propagation and 1 to mean enable propagation. In order to provide the ability to change the behaviour for packets arriving with IPv4/IPv6 Explicit Null labels and to provide an easy way for a user to change the behaviour for all existing routes without having to reprogram them, a global knob is provided. This is done through the addition of a new per-namespace sysctl, "net.mpls.ip_ttl_propagate", which defaults to enabled. If the per-route attribute is set (either enabled or disabled) then it overrides the global configuration. Signed-off-by: Robert Shearman <rshearma@brocade.com> Acked-by: David Ahern <dsa@cumulusnetworks.com> Tested-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-20net: mpls: Add support for netconfDavid Ahern1-1/+1
Add netconf support to MPLS. Allows userpsace to learn and be notified of changes to 'input' enable setting per interface. Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David Ahern <dsa@cumulusnetworks.com> Acked-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-01-17mpls: Packet statsRobert Shearman1-3/+55
Having MPLS packet stats is useful for observing network operation and for diagnosing network problems. In the absence of anything better, RFC2863 and RFC3813 are used for guidance for which stats to expose and the semantics of them. In particular rx_noroutes maps to in unknown protos in RFC2863. The stats are exposed to userspace via AF_MPLS attributes embedded in the IFLA_STATS_AF_SPEC attribute of RTM_GETSTATS messages. All the introduced fields are 64-bit, even error ones, to ensure no overflow with long uptimes. Per-CPU counters are used to avoid cache-line contention on the commonly used fields. The other fields have also been made per-CPU for code to avoid performance problems in error conditions on the assumption that on some platforms the cost of atomic operations could be more expensive than sending the packet (which is what would be done in the success case). If that's not the case, we could instead not use per-CPU counters for these fields. Only unicast and non-fragment are exposed at the moment, but other counters can be exposed in the future either by adding to the end of struct mpls_link_stats or by additional netlink attributes in the AF_MPLS IFLA_STATS_AF_SPEC nested attribute. Signed-off-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-10-03mpls: move mpls_hdr to a common locationJiri Benc1-9/+1
This will be also used by openvswitch. Signed-off-by: Jiri Benc <jbenc@redhat.com> Acked-by: David Ahern <dsa@cumulusnetworks.com> Acked-by: Pravin B Shelar <pshelar@ovn.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03mpls: support for dead routesRoopa Prabhu1-0/+2
Adds support for RTNH_F_DEAD and RTNH_F_LINKDOWN flags on mpls routes due to link events. Also adds code to ignore dead routes during route selection. Unlike ip routes, mpls routes are not deleted when the route goes dead. This is current mpls behaviour and this patch does not change that. With this patch however, routes will be marked dead. dead routes are not notified to userspace (this is consistent with ipv4 routes). dead routes: ----------- $ip -f mpls route show 100 nexthop as to 200 via inet 10.1.1.2 dev swp1 nexthop as to 700 via inet 10.1.1.6 dev swp2 $ip link set dev swp1 down $ip link show dev swp1 4: swp1: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000 link/ether 00:02:00:00:00:01 brd ff:ff:ff:ff:ff:ff $ip -f mpls route show 100 nexthop as to 200 via inet 10.1.1.2 dev swp1 dead linkdown nexthop as to 700 via inet 10.1.1.6 dev swp2 linkdown routes: ---------------- $ip -f mpls route show 100 nexthop as to 200 via inet 10.1.1.2 dev swp1 nexthop as to 700 via inet 10.1.1.6 dev swp2 $ip link show dev swp1 4: swp1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000 link/ether 00:02:00:00:00:01 brd ff:ff:ff:ff:ff:ff /* carrier goes down */ $ip link show dev swp1 4: swp1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000 link/ether 00:02:00:00:00:01 brd ff:ff:ff:ff:ff:ff $ip -f mpls route show 100 nexthop as to 200 via inet 10.1.1.2 dev swp1 linkdown nexthop as to 700 via inet 10.1.1.6 dev swp2 Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com> Acked-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-27mpls: reduce memory usage of routesRobert Shearman1-3/+25
Nexthops for MPLS routes have a via address field sized for the largest via address that is expected, which is 32 bytes. This means that in the most common case of having ipv4 via addresses, 28 bytes of memory more than required are used per nexthop. In the other common case of an ipv6 nexthop then 16 bytes more than required are used. With large numbers of MPLS routes this extra memory usage could start to become significant. To avoid allocating memory for a maximum length via address when not all of it is required and to allow for ease of iterating over nexthops, then the via addresses are changed to be stored in the same memory block as the route and nexthops, but in an array after the end of the array of nexthops. New accessors are provided to retrieve a pointer to the via address. To allow for O(1) access without having to store a pointer or offset per nh, the via address for each nexthop is sized according to the maximum via address for any nexthop in the route, which is stored in a new route field, rt_max_alen, but this is in an existing hole in struct mpls_route so it doesn't increase the size of the structure. Each via address is ensured to be aligned to VIA_ALEN_ALIGN to account for architectures that don't allow unaligned accesses. Signed-off-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-23mpls: multipath route supportRoopa Prabhu1-1/+51
This patch adds support for MPLS multipath routes. Includes following changes to support multipath: - splits struct mpls_route into 'struct mpls_route + struct mpls_nh' - 'struct mpls_nh' represents a mpls nexthop label forwarding entry - moves mpls route and nexthop structures into internal.h - A mpls_route can point to multiple mpls_nh structs - the nexthops are maintained as a array (similar to ipv4 fib) - In the process of restructuring, this patch also consistently changes all labels to u8 - Adds support to parse/fill RTA_MULTIPATH netlink attribute for multipath routes similar to ipv4/v6 fib - In this patch, the multipath route nexthop selection algorithm simply returns the first nexthop. It is replaced by a hash based algorithm from Robert Shearman in the next patch - mpls_route_update cleanup: remove 'dev' handling in mpls_route_update. mpls_route_update though implemented to update based on dev, it was never used that way. And the dev handling gets tricky with multiple nexthops. Cannot match against any single nexthops dev. So, this patch removes the unused 'dev' handling in mpls_route_update. - dead route/path handling will be implemented in a subsequent patch Example: $ip -f mpls route add 100 nexthop as 200 via inet 10.1.1.2 dev swp1 \ nexthop as 700 via inet 10.1.1.6 dev swp2 \ nexthop as 800 via inet 40.1.1.2 dev swp3 $ip -f mpls route show 100 nexthop as to 200 via inet 10.1.1.2 dev swp1 nexthop as to 700 via inet 10.1.1.6 dev swp2 nexthop as to 800 via inet 40.1.1.2 dev swp3 Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com> Acked-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-07-21mpls: export mpls functions for use by mpls iptunnelsRoopa Prabhu1-2/+7
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-06-07mpls: fix possible use after free of deviceRobert Shearman1-0/+1
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: 03c57747a702 ("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>
2015-05-05mpls: Move reserved label definitionsTom Herbert1-10/+0
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>
2015-04-22mpls: Per-device enabling of packet inputRobert Shearman1-0/+3
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>
2015-04-22mpls: Per-device MPLS stateRobert Shearman1-0/+3
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>
2015-03-04mpls: Functions for reading and wrinting mpls labels over netlinkEric W. Biederman1-0/+3
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>
2015-03-04mpls: Basic routing supportEric W. Biederman1-0/+56
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>