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_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;
struct mpls_dev *mdev;
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 */
mdev = mpls_dev_get(dev);
if (!mdev || !mdev->input_enabled)
goto drop;
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 = rcu_dereference(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 <= 1)
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_table, 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;
}
