linux/net/mpls/mpls_iptunnel.c
David Ahern 48d2ab609b net: mpls: Fixups for GSO
As reported by Lennert the MPLS GSO code is failing to properly segment
large packets. There are a couple of problems:

1. the inner protocol is not set so the gso segment functions for inner
   protocol layers are not getting run, and

2  MPLS labels for packets that use the "native" (non-OVS) MPLS code
   are not properly accounted for in mpls_gso_segment.

The MPLS GSO code was added for OVS. It is re-using skb_mac_gso_segment
to call the gso segment functions for the higher layer protocols. That
means skb_mac_gso_segment is called twice -- once with the network
protocol set to MPLS and again with the network protocol set to the
inner protocol.

This patch sets the inner skb protocol addressing item 1 above and sets
the network_header and inner_network_header to mark where the MPLS labels
start and end. The MPLS code in OVS is also updated to set the two
network markers.

>From there the MPLS GSO code uses the difference between the network
header and the inner network header to know the size of the MPLS header
that was pushed. It then pulls the MPLS header, resets the mac_len and
protocol for the inner protocol and then calls skb_mac_gso_segment
to segment the skb.

Afterward the inner protocol segmentation is done the skb protocol
is set to mpls for each segment and the network and mac headers
restored.

Reported-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-30 22:27:18 -07:00

238 lines
5.7 KiB
C

/*
* mpls tunnels An implementation mpls tunnels using the light weight tunnel
* infrastructure
*
* Authors: Roopa Prabhu, <roopa@cumulusnetworks.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/net.h>
#include <linux/module.h>
#include <linux/mpls.h>
#include <linux/vmalloc.h>
#include <net/ip.h>
#include <net/dst.h>
#include <net/lwtunnel.h>
#include <net/netevent.h>
#include <net/netns/generic.h>
#include <net/ip6_fib.h>
#include <net/route.h>
#include <net/mpls_iptunnel.h>
#include <linux/mpls_iptunnel.h>
#include "internal.h"
static const struct nla_policy mpls_iptunnel_policy[MPLS_IPTUNNEL_MAX + 1] = {
[MPLS_IPTUNNEL_DST] = { .type = NLA_U32 },
};
static unsigned int mpls_encap_size(struct mpls_iptunnel_encap *en)
{
/* The size of the layer 2.5 labels to be added for this route */
return en->labels * sizeof(struct mpls_shim_hdr);
}
static int mpls_xmit(struct sk_buff *skb)
{
struct mpls_iptunnel_encap *tun_encap_info;
struct mpls_shim_hdr *hdr;
struct net_device *out_dev;
unsigned int hh_len;
unsigned int new_header_size;
unsigned int mtu;
struct dst_entry *dst = skb_dst(skb);
struct rtable *rt = NULL;
struct rt6_info *rt6 = NULL;
int err = 0;
bool bos;
int i;
unsigned int ttl;
/* Obtain the ttl */
if (dst->ops->family == AF_INET) {
ttl = ip_hdr(skb)->ttl;
rt = (struct rtable *)dst;
} else if (dst->ops->family == AF_INET6) {
ttl = ipv6_hdr(skb)->hop_limit;
rt6 = (struct rt6_info *)dst;
} else {
goto drop;
}
skb_orphan(skb);
/* Find the output device */
out_dev = dst->dev;
if (!mpls_output_possible(out_dev) ||
!dst->lwtstate || skb_warn_if_lro(skb))
goto drop;
skb_forward_csum(skb);
tun_encap_info = mpls_lwtunnel_encap(dst->lwtstate);
/* Verify the destination can hold the packet */
new_header_size = mpls_encap_size(tun_encap_info);
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_set_inner_protocol(skb, skb->protocol);
skb_reset_inner_network_header(skb);
skb_push(skb, new_header_size);
skb_reset_network_header(skb);
skb->dev = out_dev;
skb->protocol = htons(ETH_P_MPLS_UC);
/* Push the new labels */
hdr = mpls_hdr(skb);
bos = true;
for (i = tun_encap_info->labels - 1; i >= 0; i--) {
hdr[i] = mpls_entry_encode(tun_encap_info->label[i],
ttl, 0, bos);
bos = false;
}
if (rt)
err = neigh_xmit(NEIGH_ARP_TABLE, out_dev, &rt->rt_gateway,
skb);
else if (rt6)
err = neigh_xmit(NEIGH_ND_TABLE, out_dev, &rt6->rt6i_gateway,
skb);
if (err)
net_dbg_ratelimited("%s: packet transmission failed: %d\n",
__func__, err);
return LWTUNNEL_XMIT_DONE;
drop:
kfree_skb(skb);
return -EINVAL;
}
static int mpls_build_state(struct net_device *dev, struct nlattr *nla,
unsigned int family, const void *cfg,
struct lwtunnel_state **ts)
{
struct mpls_iptunnel_encap *tun_encap_info;
struct nlattr *tb[MPLS_IPTUNNEL_MAX + 1];
struct lwtunnel_state *newts;
int tun_encap_info_len;
int ret;
ret = nla_parse_nested(tb, MPLS_IPTUNNEL_MAX, nla,
mpls_iptunnel_policy);
if (ret < 0)
return ret;
if (!tb[MPLS_IPTUNNEL_DST])
return -EINVAL;
tun_encap_info_len = sizeof(*tun_encap_info);
newts = lwtunnel_state_alloc(tun_encap_info_len);
if (!newts)
return -ENOMEM;
newts->len = tun_encap_info_len;
tun_encap_info = mpls_lwtunnel_encap(newts);
ret = nla_get_labels(tb[MPLS_IPTUNNEL_DST], MAX_NEW_LABELS,
&tun_encap_info->labels, tun_encap_info->label);
if (ret)
goto errout;
newts->type = LWTUNNEL_ENCAP_MPLS;
newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
newts->headroom = mpls_encap_size(tun_encap_info);
*ts = newts;
return 0;
errout:
kfree(newts);
*ts = NULL;
return ret;
}
static int mpls_fill_encap_info(struct sk_buff *skb,
struct lwtunnel_state *lwtstate)
{
struct mpls_iptunnel_encap *tun_encap_info;
tun_encap_info = mpls_lwtunnel_encap(lwtstate);
if (nla_put_labels(skb, MPLS_IPTUNNEL_DST, tun_encap_info->labels,
tun_encap_info->label))
goto nla_put_failure;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
static int mpls_encap_nlsize(struct lwtunnel_state *lwtstate)
{
struct mpls_iptunnel_encap *tun_encap_info;
tun_encap_info = mpls_lwtunnel_encap(lwtstate);
return nla_total_size(tun_encap_info->labels * 4);
}
static int mpls_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
struct mpls_iptunnel_encap *a_hdr = mpls_lwtunnel_encap(a);
struct mpls_iptunnel_encap *b_hdr = mpls_lwtunnel_encap(b);
int l;
if (a_hdr->labels != b_hdr->labels)
return 1;
for (l = 0; l < MAX_NEW_LABELS; l++)
if (a_hdr->label[l] != b_hdr->label[l])
return 1;
return 0;
}
static const struct lwtunnel_encap_ops mpls_iptun_ops = {
.build_state = mpls_build_state,
.xmit = mpls_xmit,
.fill_encap = mpls_fill_encap_info,
.get_encap_size = mpls_encap_nlsize,
.cmp_encap = mpls_encap_cmp,
};
static int __init mpls_iptunnel_init(void)
{
return lwtunnel_encap_add_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
}
module_init(mpls_iptunnel_init);
static void __exit mpls_iptunnel_exit(void)
{
lwtunnel_encap_del_ops(&mpls_iptun_ops, LWTUNNEL_ENCAP_MPLS);
}
module_exit(mpls_iptunnel_exit);
MODULE_ALIAS_RTNL_LWT(MPLS);
MODULE_DESCRIPTION("MultiProtocol Label Switching IP Tunnels");
MODULE_LICENSE("GPL v2");