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authorEric W. Biederman <ebiederm@xmission.com>2015-03-03 19:10:47 -0600
committerDavid S. Miller <davem@davemloft.net>2015-03-04 00:26:06 -0500
commit0189197f441602acdca3f97750d392a895b778fd (patch)
tree42ea0d4f05baaaabe7e15b153ce002d0aaaac1a4 /include
parentcec9166ca4e586de389b0f3c43a8103e728d92ec (diff)
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" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/socket.h2
-rw-r--r--include/net/net_namespace.h4
-rw-r--r--include/net/netns/mpls.h15
3 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 5c19cba34dce..fab4d0ddf4ed 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -181,6 +181,7 @@ struct ucred {
#define AF_WANPIPE 25 /* Wanpipe API Sockets */
#define AF_LLC 26 /* Linux LLC */
#define AF_IB 27 /* Native InfiniBand address */
+#define AF_MPLS 28 /* MPLS */
#define AF_CAN 29 /* Controller Area Network */
#define AF_TIPC 30 /* TIPC sockets */
#define AF_BLUETOOTH 31 /* Bluetooth sockets */
@@ -226,6 +227,7 @@ struct ucred {
#define PF_WANPIPE AF_WANPIPE
#define PF_LLC AF_LLC
#define PF_IB AF_IB
+#define PF_MPLS AF_MPLS
#define PF_CAN AF_CAN
#define PF_TIPC AF_TIPC
#define PF_BLUETOOTH AF_BLUETOOTH
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 36faf4990c4b..2cb9acb618e9 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -26,6 +26,7 @@
#endif
#include <net/netns/nftables.h>
#include <net/netns/xfrm.h>
+#include <net/netns/mpls.h>
#include <linux/ns_common.h>
struct user_namespace;
@@ -130,6 +131,9 @@ struct net {
#if IS_ENABLED(CONFIG_IP_VS)
struct netns_ipvs *ipvs;
#endif
+#if IS_ENABLED(CONFIG_MPLS)
+ struct netns_mpls mpls;
+#endif
struct sock *diag_nlsk;
atomic_t fnhe_genid;
};
diff --git a/include/net/netns/mpls.h b/include/net/netns/mpls.h
new file mode 100644
index 000000000000..f90aaf8d4f89
--- /dev/null
+++ b/include/net/netns/mpls.h
@@ -0,0 +1,15 @@
+/*
+ * mpls in net namespaces
+ */
+
+#ifndef __NETNS_MPLS_H__
+#define __NETNS_MPLS_H__
+
+struct mpls_route;
+
+struct netns_mpls {
+ size_t platform_labels;
+ struct mpls_route __rcu * __rcu *platform_label;
+};
+
+#endif /* __NETNS_MPLS_H__ */