Commit a59166e4 authored by Robert Shearman's avatar Robert Shearman Committed by David S. Miller
Browse files

mpls: allow TTL propagation from IP packets to be configured 



Allow TTL propagation from IP packets to MPLS packets to be
configured. Add a new optional LWT attribute, MPLS_IPTUNNEL_TTL, which
allows the TTL to be set in the resulting MPLS packet, with the value
of 0 having the semantics of enabling propagation of the TTL from the
IP header (i.e. non-zero values disable propagation).

Also allow the configuration to be overridden globally by reusing the
same sysctl to control whether the TTL is propagated from IP packets
into the MPLS header. If the per-LWT attribute is set then it
overrides the global configuration. If the TTL isn't propagated then a
default TTL value is used which can be configured via a new sysctl,
"net.mpls.default_ttl". This is kept separate from the configuration
of whether IP TTL propagation is enabled as it can be used in the
future when non-IP payloads are supported (i.e. where there is no
payload TTL that can be propagated).

Signed-off-by: default avatarRobert Shearman <rshearma@brocade.com>
Acked-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Tested-by: default avatarDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5b441ac8

Documentation/networking/mpls-sysctl.txt

+8 −0
Original line number Diff line number Diff line
@@ -30,6 +30,14 @@ ip_ttl_propagate - BOOL 
	0 - disabled / RFC 3443 [Short] Pipe Model

	1 - enabled / RFC 3443 Uniform Model (default)



default_ttl - BOOL

	Default TTL value to use for MPLS packets where it cannot be

	propagated from an IP header, either because one isn't present

	or ip_ttl_propagate has been disabled.



	Possible values: 1 - 255

	Default: 255



conf/<interface>/input - BOOL

	Control whether packets can be input on this interface.

include/net/mpls_iptunnel.h

+2 −0
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
struct mpls_iptunnel_encap {

	u32	label[MAX_NEW_LABELS];

	u8	labels;

	u8	ttl_propagate;

	u8	default_ttl;

};



static inline struct mpls_iptunnel_encap *mpls_lwtunnel_encap(struct lwtunnel_state *lwtstate)

include/net/netns/mpls.h

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ struct ctl_table_header; 


struct netns_mpls {

	int ip_ttl_propagate;

	int default_ttl;

	size_t platform_labels;

	struct mpls_route __rcu * __rcu *platform_label;

include/uapi/linux/mpls_iptunnel.h

+2 −0
Original line number Diff line number Diff line
@@ -16,11 +16,13 @@ 
/* MPLS tunnel attributes

 * [RTA_ENCAP] = {

 *     [MPLS_IPTUNNEL_DST]

 *     [MPLS_IPTUNNEL_TTL]

 * }

 */

enum {

	MPLS_IPTUNNEL_UNSPEC,

	MPLS_IPTUNNEL_DST,

	MPLS_IPTUNNEL_TTL,

	__MPLS_IPTUNNEL_MAX,

};

#define MPLS_IPTUNNEL_MAX (__MPLS_IPTUNNEL_MAX - 1)

net/mpls/af_mpls.c

+11 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
static int zero = 0;

static int one = 1;

static int label_limit = (1 << 20) - 1;

static int ttl_max = 255;



static void rtmsg_lfib(int event, u32 label, struct mpls_route *rt,

		       struct nlmsghdr *nlh, struct net *net, u32 portid,
@@ -2042,6 +2043,15 @@ static const struct ctl_table mpls_table[] = { 
		.extra1		= &zero,

		.extra2		= &one,

	},

	{

		.procname	= "default_ttl",

		.data		= MPLS_NS_SYSCTL_OFFSET(mpls.default_ttl),

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec_minmax,

		.extra1		= &one,

		.extra2		= &ttl_max,

	},

	{ }

};
@@ -2053,6 +2063,7 @@ static int mpls_net_init(struct net *net) 
	net->mpls.platform_labels = 0;

	net->mpls.platform_label = NULL;

	net->mpls.ip_ttl_propagate = 1;

	net->mpls.default_ttl = 255;



	table = kmemdup(mpls_table, sizeof(mpls_table), GFP_KERNEL);

	if (table == NULL)

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