From 0189197f441602acdca3f97750d392a895b778fd Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 3 Mar 2015 19:10:47 -0600 Subject: mpls: Basic routing support 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" Signed-off-by: David S. Miller --- net/mpls/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'net/mpls/Makefile') diff --git a/net/mpls/Makefile b/net/mpls/Makefile index 6dec088c2d0f..60af15f1960e 100644 --- a/net/mpls/Makefile +++ b/net/mpls/Makefile @@ -2,3 +2,4 @@ # Makefile for MPLS. # obj-$(CONFIG_NET_MPLS_GSO) += mpls_gso.o +obj-$(CONFIG_MPLS_ROUTING) += af_mpls.o -- cgit v1.2.3 From 8a08919f43d9955d5afc5d6b416964401e3c58d8 Mon Sep 17 00:00:00 2001 From: Robert Shearman Date: Tue, 10 Mar 2015 16:37:59 +0000 Subject: mpls: Allow mpls_gso and mpls_router to be built as modules 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" Signed-off-by: Robert Shearman Signed-off-by: David S. Miller --- net/mpls/Kconfig | 6 +++--- net/mpls/Makefile | 4 +++- 2 files changed, 6 insertions(+), 4 deletions(-) (limited to 'net/mpls/Makefile') diff --git a/net/mpls/Kconfig b/net/mpls/Kconfig index dfca485863e9..17bde799c854 100644 --- a/net/mpls/Kconfig +++ b/net/mpls/Kconfig @@ -3,7 +3,7 @@ # menuconfig MPLS - tristate "MultiProtocol Label Switching" + bool "MultiProtocol Label Switching" default n ---help--- MultiProtocol Label Switching routes packets through logical @@ -16,14 +16,14 @@ menuconfig MPLS if MPLS config NET_MPLS_GSO - bool "MPLS: GSO support" + tristate "MPLS: GSO support" help This is helper module to allow segmentation of non-MPLS GSO packets that have had MPLS stack entries pushed onto them and thus become MPLS GSO packets. config MPLS_ROUTING - bool "MPLS: routing support" + tristate "MPLS: routing support" help Add support for forwarding of mpls packets. diff --git a/net/mpls/Makefile b/net/mpls/Makefile index 60af15f1960e..65bbe68c72e6 100644 --- a/net/mpls/Makefile +++ b/net/mpls/Makefile @@ -2,4 +2,6 @@ # Makefile for MPLS. # obj-$(CONFIG_NET_MPLS_GSO) += mpls_gso.o -obj-$(CONFIG_MPLS_ROUTING) += af_mpls.o +obj-$(CONFIG_MPLS_ROUTING) += mpls_router.o + +mpls_router-y := af_mpls.o -- cgit v1.2.3