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linux/net/mpls/af_mpls.c

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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>
2015-03-04 09:10:47 +08:00
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
mpls: Add a sysctl to control the size of the mpls label table 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>
2015-03-04 09:11:20 +08:00
#include <linux/sysctl.h>
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>
2015-03-04 09:10:47 +08:00
#include <linux/net.h>
#include <linux/module.h>
#include <linux/if_arp.h>
#include <linux/ipv6.h>
#include <linux/mpls.h>
#include <net/ip.h>
#include <net/dst.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/ip_fib.h>
#include <net/netevent.h>
#include <net/netns/generic.h>
#include "internal.h"
mpls: Basic support for adding and removing routes 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>
2015-03-04 09:12:40 +08:00
#define LABEL_NOT_SPECIFIED (1<<20)
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>
2015-03-04 09:10:47 +08:00
#define MAX_NEW_LABELS 2
/* This maximum ha length copied from the definition of struct neighbour */
#define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, sizeof(unsigned long)))
struct mpls_route { /* next hop label forwarding entry */
struct net_device *rt_dev;
struct rcu_head rt_rcu;
u32 rt_label[MAX_NEW_LABELS];
u8 rt_protocol; /* routing protocol that set this entry */
u8 rt_labels:2,
rt_via_alen:6;
unsigned short rt_via_family;
u8 rt_via[0];
};
mpls: Add a sysctl to control the size of the mpls label table 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>
2015-03-04 09:11:20 +08:00
static int zero = 0;
static int label_limit = (1 << 20) - 1;
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>
2015-03-04 09:10:47 +08:00
static struct mpls_route *mpls_route_input_rcu(struct net *net, unsigned index)
{
struct mpls_route *rt = NULL;
if (index < net->mpls.platform_labels) {
struct mpls_route __rcu **platform_label =
rcu_dereference(net->mpls.platform_label);
rt = rcu_dereference(platform_label[index]);
}
return rt;
}
static bool mpls_output_possible(const struct net_device *dev)
{
return dev && (dev->flags & IFF_UP) && netif_carrier_ok(dev);
}
static unsigned int mpls_rt_header_size(const struct mpls_route *rt)
{
/* The size of the layer 2.5 labels to be added for this route */
return rt->rt_labels * sizeof(struct mpls_shim_hdr);
}
static unsigned int mpls_dev_mtu(const struct net_device *dev)
{
/* The amount of data the layer 2 frame can hold */
return dev->mtu;
}
static bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
{
if (skb->len <= mtu)
return false;
if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
return false;
return true;
}
static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
struct mpls_entry_decoded dec)
{
/* RFC4385 and RFC5586 encode other packets in mpls such that
* they don't conflict with the ip version number, making
* decoding by examining the ip version correct in everything
* except for the strangest cases.
*
* The strange cases if we choose to support them will require
* manual configuration.
*/
struct iphdr *hdr4 = ip_hdr(skb);
bool success = true;
if (hdr4->version == 4) {
skb->protocol = htons(ETH_P_IP);
csum_replace2(&hdr4->check,
htons(hdr4->ttl << 8),
htons(dec.ttl << 8));
hdr4->ttl = dec.ttl;
}
else if (hdr4->version == 6) {
struct ipv6hdr *hdr6 = ipv6_hdr(skb);
skb->protocol = htons(ETH_P_IPV6);
hdr6->hop_limit = dec.ttl;
}
else
/* version 0 and version 1 are used by pseudo wires */
success = false;
return success;
}
static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
struct packet_type *pt, struct net_device *orig_dev)
{
struct net *net = dev_net(dev);
struct mpls_shim_hdr *hdr;
struct mpls_route *rt;
struct mpls_entry_decoded dec;
struct net_device *out_dev;
unsigned int hh_len;
unsigned int new_header_size;
unsigned int mtu;
int err;
/* Careful this entire function runs inside of an rcu critical section */
if (skb->pkt_type != PACKET_HOST)
goto drop;
if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
goto drop;
if (!pskb_may_pull(skb, sizeof(*hdr)))
goto drop;
/* Read and decode the label */
hdr = mpls_hdr(skb);
dec = mpls_entry_decode(hdr);
/* Pop the label */
skb_pull(skb, sizeof(*hdr));
skb_reset_network_header(skb);
skb_orphan(skb);
rt = mpls_route_input_rcu(net, dec.label);
if (!rt)
goto drop;
/* Find the output device */
out_dev = rt->rt_dev;
if (!mpls_output_possible(out_dev))
goto drop;
if (skb_warn_if_lro(skb))
goto drop;
skb_forward_csum(skb);
/* Verify ttl is valid */
if (dec.ttl <= 2)
goto drop;
dec.ttl -= 1;
/* Verify the destination can hold the packet */
new_header_size = mpls_rt_header_size(rt);
mtu = mpls_dev_mtu(out_dev);
if (mpls_pkt_too_big(skb, mtu - new_header_size))
goto drop;
hh_len = LL_RESERVED_SPACE(out_dev);
if (!out_dev->header_ops)
hh_len = 0;
/* Ensure there is enough space for the headers in the skb */
if (skb_cow(skb, hh_len + new_header_size))
goto drop;
skb->dev = out_dev;
skb->protocol = htons(ETH_P_MPLS_UC);
if (unlikely(!new_header_size && dec.bos)) {
/* Penultimate hop popping */
if (!mpls_egress(rt, skb, dec))
goto drop;
} else {
bool bos;
int i;
skb_push(skb, new_header_size);
skb_reset_network_header(skb);
/* Push the new labels */
hdr = mpls_hdr(skb);
bos = dec.bos;
for (i = rt->rt_labels - 1; i >= 0; i--) {
hdr[i] = mpls_entry_encode(rt->rt_label[i], dec.ttl, 0, bos);
bos = false;
}
}
err = neigh_xmit(rt->rt_via_family, out_dev, rt->rt_via, skb);
if (err)
net_dbg_ratelimited("%s: packet transmission failed: %d\n",
__func__, err);
return 0;
drop:
kfree_skb(skb);
return NET_RX_DROP;
}
static struct packet_type mpls_packet_type __read_mostly = {
.type = cpu_to_be16(ETH_P_MPLS_UC),
.func = mpls_forward,
};
mpls: Netlink commands to add, remove, and dump routes 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>
2015-03-04 09:13:56 +08:00
const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {
[RTA_DST] = { .type = NLA_U32 },
[RTA_OIF] = { .type = NLA_U32 },
};
mpls: Basic support for adding and removing routes 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>
2015-03-04 09:12:40 +08:00
struct mpls_route_config {
u32 rc_protocol;
u32 rc_ifindex;
u16 rc_via_family;
u16 rc_via_alen;
u8 rc_via[MAX_VIA_ALEN];
u32 rc_label;
u32 rc_output_labels;
u32 rc_output_label[MAX_NEW_LABELS];
u32 rc_nlflags;
struct nl_info rc_nlinfo;
};
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>
2015-03-04 09:10:47 +08:00
static struct mpls_route *mpls_rt_alloc(size_t alen)
{
struct mpls_route *rt;
rt = kzalloc(GFP_KERNEL, sizeof(*rt) + alen);
if (rt)
rt->rt_via_alen = alen;
return rt;
}
static void mpls_rt_free(struct mpls_route *rt)
{
if (rt)
kfree_rcu(rt, rt_rcu);
}
static void mpls_route_update(struct net *net, unsigned index,
struct net_device *dev, struct mpls_route *new,
const struct nl_info *info)
{
struct mpls_route *rt, *old = NULL;
ASSERT_RTNL();
rt = net->mpls.platform_label[index];
if (!dev || (rt && (rt->rt_dev == dev))) {
rcu_assign_pointer(net->mpls.platform_label[index], new);
old = rt;
}
/* If we removed a route free it now */
mpls_rt_free(old);
}
mpls: Basic support for adding and removing routes 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>
2015-03-04 09:12:40 +08:00
static unsigned find_free_label(struct net *net)
{
unsigned index;
for (index = 16; index < net->mpls.platform_labels; index++) {
if (!net->mpls.platform_label[index])
return index;
}
return LABEL_NOT_SPECIFIED;
}
static int mpls_route_add(struct mpls_route_config *cfg)
{
struct net *net = cfg->rc_nlinfo.nl_net;
struct net_device *dev = NULL;
struct mpls_route *rt, *old;
unsigned index;
int i;
int err = -EINVAL;
index = cfg->rc_label;
/* If a label was not specified during insert pick one */
if ((index == LABEL_NOT_SPECIFIED) &&
(cfg->rc_nlflags & NLM_F_CREATE)) {
index = find_free_label(net);
}
/* The first 16 labels are reserved, and may not be set */
if (index < 16)
goto errout;
/* The full 20 bit range may not be supported. */
if (index >= net->mpls.platform_labels)
goto errout;
/* Ensure only a supported number of labels are present */
if (cfg->rc_output_labels > MAX_NEW_LABELS)
goto errout;
err = -ENODEV;
dev = dev_get_by_index(net, cfg->rc_ifindex);
if (!dev)
goto errout;
/* For now just support ethernet devices */
err = -EINVAL;
if ((dev->type != ARPHRD_ETHER) && (dev->type != ARPHRD_LOOPBACK))
goto errout;
err = -EINVAL;
if ((cfg->rc_via_family == AF_PACKET) &&
(dev->addr_len != cfg->rc_via_alen))
goto errout;
/* Append makes no sense with mpls */
err = -EINVAL;
if (cfg->rc_nlflags & NLM_F_APPEND)
goto errout;
err = -EEXIST;
old = net->mpls.platform_label[index];
if ((cfg->rc_nlflags & NLM_F_EXCL) && old)
goto errout;
err = -EEXIST;
if (!(cfg->rc_nlflags & NLM_F_REPLACE) && old)
goto errout;
err = -ENOENT;
if (!(cfg->rc_nlflags & NLM_F_CREATE) && !old)
goto errout;
err = -ENOMEM;
rt = mpls_rt_alloc(cfg->rc_via_alen);
if (!rt)
goto errout;
rt->rt_labels = cfg->rc_output_labels;
for (i = 0; i < rt->rt_labels; i++)
rt->rt_label[i] = cfg->rc_output_label[i];
rt->rt_protocol = cfg->rc_protocol;
rt->rt_dev = dev;
rt->rt_via_family = cfg->rc_via_family;
memcpy(rt->rt_via, cfg->rc_via, cfg->rc_via_alen);
mpls_route_update(net, index, NULL, rt, &cfg->rc_nlinfo);
dev_put(dev);
return 0;
errout:
if (dev)
dev_put(dev);
return err;
}
static int mpls_route_del(struct mpls_route_config *cfg)
{
struct net *net = cfg->rc_nlinfo.nl_net;
unsigned index;
int err = -EINVAL;
index = cfg->rc_label;
/* The first 16 labels are reserved, and may not be removed */
if (index < 16)
goto errout;
/* The full 20 bit range may not be supported */
if (index >= net->mpls.platform_labels)
goto errout;
mpls_route_update(net, index, NULL, NULL, &cfg->rc_nlinfo);
err = 0;
errout:
return err;
}
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>
2015-03-04 09:10:47 +08:00
static void mpls_ifdown(struct net_device *dev)
{
struct net *net = dev_net(dev);
unsigned index;
for (index = 0; index < net->mpls.platform_labels; index++) {
struct mpls_route *rt = net->mpls.platform_label[index];
if (!rt)
continue;
if (rt->rt_dev != dev)
continue;
rt->rt_dev = NULL;
}
}
static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
switch(event) {
case NETDEV_UNREGISTER:
mpls_ifdown(dev);
break;
}
return NOTIFY_OK;
}
static struct notifier_block mpls_dev_notifier = {
.notifier_call = mpls_dev_notify,
};
mpls: Netlink commands to add, remove, and dump routes 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>
2015-03-04 09:13:56 +08:00
static int nla_put_via(struct sk_buff *skb,
u16 family, const void *addr, int alen)
{
struct nlattr *nla;
struct rtvia *via;
nla = nla_reserve(skb, RTA_VIA, alen + 2);
if (!nla)
return -EMSGSIZE;
via = nla_data(nla);
via->rtvia_family = family;
memcpy(via->rtvia_addr, addr, alen);
return 0;
}
mpls: Functions for reading and wrinting mpls labels over netlink 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>
2015-03-04 09:13:19 +08:00
int nla_put_labels(struct sk_buff *skb, int attrtype,
u8 labels, const u32 label[])
{
struct nlattr *nla;
struct mpls_shim_hdr *nla_label;
bool bos;
int i;
nla = nla_reserve(skb, attrtype, labels*4);
if (!nla)
return -EMSGSIZE;
nla_label = nla_data(nla);
bos = true;
for (i = labels - 1; i >= 0; i--) {
nla_label[i] = mpls_entry_encode(label[i], 0, 0, bos);
bos = false;
}
return 0;
}
int nla_get_labels(const struct nlattr *nla,
u32 max_labels, u32 *labels, u32 label[])
{
unsigned len = nla_len(nla);
unsigned nla_labels;
struct mpls_shim_hdr *nla_label;
bool bos;
int i;
/* len needs to be an even multiple of 4 (the label size) */
if (len & 3)
return -EINVAL;
/* Limit the number of new labels allowed */
nla_labels = len/4;
if (nla_labels > max_labels)
return -EINVAL;
nla_label = nla_data(nla);
bos = true;
for (i = nla_labels - 1; i >= 0; i--, bos = false) {
struct mpls_entry_decoded dec;
dec = mpls_entry_decode(nla_label + i);
/* Ensure the bottom of stack flag is properly set
* and ttl and tc are both clear.
*/
if ((dec.bos != bos) || dec.ttl || dec.tc)
return -EINVAL;
label[i] = dec.label;
}
*labels = nla_labels;
return 0;
}
mpls: Netlink commands to add, remove, and dump routes 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>
2015-03-04 09:13:56 +08:00
static int rtm_to_route_config(struct sk_buff *skb, struct nlmsghdr *nlh,
struct mpls_route_config *cfg)
{
struct rtmsg *rtm;
struct nlattr *tb[RTA_MAX+1];
int index;
int err;
err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_mpls_policy);
if (err < 0)
goto errout;
err = -EINVAL;
rtm = nlmsg_data(nlh);
memset(cfg, 0, sizeof(*cfg));
if (rtm->rtm_family != AF_MPLS)
goto errout;
if (rtm->rtm_dst_len != 20)
goto errout;
if (rtm->rtm_src_len != 0)
goto errout;
if (rtm->rtm_tos != 0)
goto errout;
if (rtm->rtm_table != RT_TABLE_MAIN)
goto errout;
/* Any value is acceptable for rtm_protocol */
/* As mpls uses destination specific addresses
* (or source specific address in the case of multicast)
* all addresses have universal scope.
*/
if (rtm->rtm_scope != RT_SCOPE_UNIVERSE)
goto errout;
if (rtm->rtm_type != RTN_UNICAST)
goto errout;
if (rtm->rtm_flags != 0)
goto errout;
cfg->rc_label = LABEL_NOT_SPECIFIED;
cfg->rc_protocol = rtm->rtm_protocol;
cfg->rc_nlflags = nlh->nlmsg_flags;
cfg->rc_nlinfo.portid = NETLINK_CB(skb).portid;
cfg->rc_nlinfo.nlh = nlh;
cfg->rc_nlinfo.nl_net = sock_net(skb->sk);
for (index = 0; index <= RTA_MAX; index++) {
struct nlattr *nla = tb[index];
if (!nla)
continue;
switch(index) {
case RTA_OIF:
cfg->rc_ifindex = nla_get_u32(nla);
break;
case RTA_NEWDST:
if (nla_get_labels(nla, MAX_NEW_LABELS,
&cfg->rc_output_labels,
cfg->rc_output_label))
goto errout;
break;
case RTA_DST:
{
u32 label_count;
if (nla_get_labels(nla, 1, &label_count,
&cfg->rc_label))
goto errout;
/* The first 16 labels are reserved, and may not be set */
if (cfg->rc_label < 16)
goto errout;
break;
}
case RTA_VIA:
{
struct rtvia *via = nla_data(nla);
cfg->rc_via_family = via->rtvia_family;
cfg->rc_via_alen = nla_len(nla) - 2;
if (cfg->rc_via_alen > MAX_VIA_ALEN)
goto errout;
/* Validate the address family */
switch(cfg->rc_via_family) {
case AF_PACKET:
break;
case AF_INET:
if (cfg->rc_via_alen != 4)
goto errout;
break;
case AF_INET6:
if (cfg->rc_via_alen != 16)
goto errout;
break;
default:
/* Unsupported address family */
goto errout;
}
memcpy(cfg->rc_via, via->rtvia_addr, cfg->rc_via_alen);
break;
}
default:
/* Unsupported attribute */
goto errout;
}
}
err = 0;
errout:
return err;
}
static int mpls_rtm_delroute(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct mpls_route_config cfg;
int err;
err = rtm_to_route_config(skb, nlh, &cfg);
if (err < 0)
return err;
return mpls_route_del(&cfg);
}
static int mpls_rtm_newroute(struct sk_buff *skb, struct nlmsghdr *nlh)
{
struct mpls_route_config cfg;
int err;
err = rtm_to_route_config(skb, nlh, &cfg);
if (err < 0)
return err;
return mpls_route_add(&cfg);
}
static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
u32 label, struct mpls_route *rt, int flags)
{
struct nlmsghdr *nlh;
struct rtmsg *rtm;
nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
if (nlh == NULL)
return -EMSGSIZE;
rtm = nlmsg_data(nlh);
rtm->rtm_family = AF_MPLS;
rtm->rtm_dst_len = 20;
rtm->rtm_src_len = 0;
rtm->rtm_tos = 0;
rtm->rtm_table = RT_TABLE_MAIN;
rtm->rtm_protocol = rt->rt_protocol;
rtm->rtm_scope = RT_SCOPE_UNIVERSE;
rtm->rtm_type = RTN_UNICAST;
rtm->rtm_flags = 0;
if (rt->rt_labels &&
nla_put_labels(skb, RTA_NEWDST, rt->rt_labels, rt->rt_label))
goto nla_put_failure;
if (nla_put_via(skb, rt->rt_via_family, rt->rt_via, rt->rt_via_alen))
goto nla_put_failure;
if (rt->rt_dev && nla_put_u32(skb, RTA_OIF, rt->rt_dev->ifindex))
goto nla_put_failure;
if (nla_put_labels(skb, RTA_DST, 1, &label))
goto nla_put_failure;
nlmsg_end(skb, nlh);
return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
{
struct net *net = sock_net(skb->sk);
unsigned int index;
ASSERT_RTNL();
index = cb->args[0];
if (index < 16)
index = 16;
for (; index < net->mpls.platform_labels; index++) {
struct mpls_route *rt;
rt = net->mpls.platform_label[index];
if (!rt)
continue;
if (mpls_dump_route(skb, NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, RTM_NEWROUTE,
index, rt, NLM_F_MULTI) < 0)
break;
}
cb->args[0] = index;
return skb->len;
}
mpls: Add a sysctl to control the size of the mpls label table 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>
2015-03-04 09:11:20 +08:00
static int resize_platform_label_table(struct net *net, size_t limit)
{
size_t size = sizeof(struct mpls_route *) * limit;
size_t old_limit;
size_t cp_size;
struct mpls_route __rcu **labels = NULL, **old;
struct mpls_route *rt0 = NULL, *rt2 = NULL;
unsigned index;
if (size) {
labels = kzalloc(size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
if (!labels)
labels = vzalloc(size);
if (!labels)
goto nolabels;
}
/* In case the predefined labels need to be populated */
if (limit > LABEL_IPV4_EXPLICIT_NULL) {
struct net_device *lo = net->loopback_dev;
rt0 = mpls_rt_alloc(lo->addr_len);
if (!rt0)
goto nort0;
rt0->rt_dev = lo;
rt0->rt_protocol = RTPROT_KERNEL;
rt0->rt_via_family = AF_PACKET;
memcpy(rt0->rt_via, lo->dev_addr, lo->addr_len);
}
if (limit > LABEL_IPV6_EXPLICIT_NULL) {
struct net_device *lo = net->loopback_dev;
rt2 = mpls_rt_alloc(lo->addr_len);
if (!rt2)
goto nort2;
rt2->rt_dev = lo;
rt2->rt_protocol = RTPROT_KERNEL;
rt2->rt_via_family = AF_PACKET;
memcpy(rt2->rt_via, lo->dev_addr, lo->addr_len);
}
rtnl_lock();
/* Remember the original table */
old = net->mpls.platform_label;
old_limit = net->mpls.platform_labels;
/* Free any labels beyond the new table */
for (index = limit; index < old_limit; index++)
mpls_route_update(net, index, NULL, NULL, NULL);
/* Copy over the old labels */
cp_size = size;
if (old_limit < limit)
cp_size = old_limit * sizeof(struct mpls_route *);
memcpy(labels, old, cp_size);
/* If needed set the predefined labels */
if ((old_limit <= LABEL_IPV6_EXPLICIT_NULL) &&
(limit > LABEL_IPV6_EXPLICIT_NULL)) {
labels[LABEL_IPV6_EXPLICIT_NULL] = rt2;
rt2 = NULL;
}
if ((old_limit <= LABEL_IPV4_EXPLICIT_NULL) &&
(limit > LABEL_IPV4_EXPLICIT_NULL)) {
labels[LABEL_IPV4_EXPLICIT_NULL] = rt0;
rt0 = NULL;
}
/* Update the global pointers */
net->mpls.platform_labels = limit;
net->mpls.platform_label = labels;
rtnl_unlock();
mpls_rt_free(rt2);
mpls_rt_free(rt0);
if (old) {
synchronize_rcu();
kvfree(old);
}
return 0;
nort2:
mpls_rt_free(rt0);
nort0:
kvfree(labels);
nolabels:
return -ENOMEM;
}
static int mpls_platform_labels(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
struct net *net = table->data;
int platform_labels = net->mpls.platform_labels;
int ret;
struct ctl_table tmp = {
.procname = table->procname,
.data = &platform_labels,
.maxlen = sizeof(int),
.mode = table->mode,
.extra1 = &zero,
.extra2 = &label_limit,
};
ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
if (write && ret == 0)
ret = resize_platform_label_table(net, platform_labels);
return ret;
}
static struct ctl_table mpls_table[] = {
{
.procname = "platform_labels",
.data = NULL,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = mpls_platform_labels,
},
{ }
};
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>
2015-03-04 09:10:47 +08:00
static int mpls_net_init(struct net *net)
{
mpls: Add a sysctl to control the size of the mpls label table 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>
2015-03-04 09:11:20 +08:00
struct ctl_table *table;
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>
2015-03-04 09:10:47 +08:00
net->mpls.platform_labels = 0;
net->mpls.platform_label = NULL;
mpls: Add a sysctl to control the size of the mpls label table 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>
2015-03-04 09:11:20 +08:00
table = kmemdup(mpls_table, sizeof(mpls_table), GFP_KERNEL);
if (table == NULL)
return -ENOMEM;
table[0].data = net;
net->mpls.ctl = register_net_sysctl(net, "net/mpls", table);
if (net->mpls.ctl == NULL)
return -ENOMEM;
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>
2015-03-04 09:10:47 +08:00
return 0;
}
static void mpls_net_exit(struct net *net)
{
mpls: Add a sysctl to control the size of the mpls label table 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>
2015-03-04 09:11:20 +08:00
struct ctl_table *table;
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>
2015-03-04 09:10:47 +08:00
unsigned int index;
mpls: Add a sysctl to control the size of the mpls label table 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>
2015-03-04 09:11:20 +08:00
table = net->mpls.ctl->ctl_table_arg;
unregister_net_sysctl_table(net->mpls.ctl);
kfree(table);
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>
2015-03-04 09:10:47 +08:00
/* An rcu grace period haselapsed since there was a device in
* the network namespace (and thus the last in fqlight packet)
* left this network namespace. This is because
* unregister_netdevice_many and netdev_run_todo has completed
* for each network device that was in this network namespace.
*
* As such no additional rcu synchronization is necessary when
* freeing the platform_label table.
*/
rtnl_lock();
for (index = 0; index < net->mpls.platform_labels; index++) {
struct mpls_route *rt = net->mpls.platform_label[index];
rcu_assign_pointer(net->mpls.platform_label[index], NULL);
mpls_rt_free(rt);
}
rtnl_unlock();
kvfree(net->mpls.platform_label);
}
static struct pernet_operations mpls_net_ops = {
.init = mpls_net_init,
.exit = mpls_net_exit,
};
static int __init mpls_init(void)
{
int err;
BUILD_BUG_ON(sizeof(struct mpls_shim_hdr) != 4);
err = register_pernet_subsys(&mpls_net_ops);
if (err)
goto out;
err = register_netdevice_notifier(&mpls_dev_notifier);
if (err)
goto out_unregister_pernet;
dev_add_pack(&mpls_packet_type);
mpls: Netlink commands to add, remove, and dump routes 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>
2015-03-04 09:13:56 +08:00
rtnl_register(PF_MPLS, RTM_NEWROUTE, mpls_rtm_newroute, NULL, NULL);
rtnl_register(PF_MPLS, RTM_DELROUTE, mpls_rtm_delroute, NULL, NULL);
rtnl_register(PF_MPLS, RTM_GETROUTE, NULL, mpls_dump_routes, NULL);
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>
2015-03-04 09:10:47 +08:00
err = 0;
out:
return err;
out_unregister_pernet:
unregister_pernet_subsys(&mpls_net_ops);
goto out;
}
module_init(mpls_init);
static void __exit mpls_exit(void)
{
mpls: Netlink commands to add, remove, and dump routes 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>
2015-03-04 09:13:56 +08:00
rtnl_unregister_all(PF_MPLS);
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>
2015-03-04 09:10:47 +08:00
dev_remove_pack(&mpls_packet_type);
unregister_netdevice_notifier(&mpls_dev_notifier);
unregister_pernet_subsys(&mpls_net_ops);
}
module_exit(mpls_exit);
MODULE_DESCRIPTION("MultiProtocol Label Switching");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_NETPROTO(PF_MPLS);
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