Commit 03c05665 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by David S. Miller
Browse files

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: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 966bae33

include/uapi/linux/rtnetlink.h

+8 −0
Original line number Diff line number Diff line
@@ -303,6 +303,8 @@ enum rtattr_type_t { 
	RTA_TABLE,

	RTA_MARK,

	RTA_MFC_STATS,

	RTA_VIA,

	RTA_NEWDST,

	__RTA_MAX

};
@@ -344,6 +346,12 @@ struct rtnexthop { 
#define RTNH_SPACE(len)	RTNH_ALIGN(RTNH_LENGTH(len))

#define RTNH_DATA(rtnh)   ((struct rtattr*)(((char*)(rtnh)) + RTNH_LENGTH(0)))



/* RTA_VIA */

struct rtvia {

	__kernel_sa_family_t	rtvia_family;

	__u8			rtvia_addr[0];

};



/* RTM_CACHEINFO */



struct rta_cacheinfo {

net/mpls/af_mpls.c

+229 −0
Original line number Diff line number Diff line
@@ -212,6 +212,11 @@ static struct packet_type mpls_packet_type __read_mostly = { 
	.func = mpls_forward,

};



const struct nla_policy rtm_mpls_policy[RTA_MAX+1] = {

	[RTA_DST]		= { .type = NLA_U32 },

	[RTA_OIF]		= { .type = NLA_U32 },

};



struct mpls_route_config {

	u32		rc_protocol;

	u32		rc_ifindex;
@@ -410,6 +415,22 @@ static struct notifier_block mpls_dev_notifier = { 
	.notifier_call = mpls_dev_notify,

};



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;

}



int nla_put_labels(struct sk_buff *skb, int attrtype,

		   u8 labels, const u32 label[])

{
@@ -467,6 +488,210 @@ int nla_get_labels(const struct nlattr *nla, 
	return 0;

}



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;

}



static int resize_platform_label_table(struct net *net, size_t limit)

{

	size_t size = sizeof(struct mpls_route *) * limit;
@@ -662,6 +887,9 @@ static int __init mpls_init(void) 


	dev_add_pack(&mpls_packet_type);



	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);

	err = 0;

out:

	return err;
@@ -674,6 +902,7 @@ module_init(mpls_init); 


static void __exit mpls_exit(void)

{

	rtnl_unregister_all(PF_MPLS);

	dev_remove_pack(&mpls_packet_type);

	unregister_netdevice_notifier(&mpls_dev_notifier);

	unregister_pernet_subsys(&mpls_net_ops);

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