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sit.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* IPv6 over IPv4 tunnel device - Simple Internet Transition (SIT)
* Linux INET6 implementation
*
* Authors:
* Pedro Roque <roque@di.fc.ul.pt>
* Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
*
* Changes:
* Roger Venning <r.venning@telstra.com>: 6to4 support
* Nate Thompson <nate@thebog.net>: 6to4 support
* Fred Templin <fred.l.templin@boeing.com>: isatap support
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/icmp.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/init.h>
#include <linux/netfilter_ipv4.h>
#include <linux/if_ether.h>
#include <net/sock.h>
#include <net/snmp.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/ip6_fib.h>
#include <net/ip6_route.h>
#include <net/ndisc.h>
#include <net/addrconf.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <net/ip_tunnels.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>
#include <net/dsfield.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
/*
This version of net/ipv6/sit.c is cloned of net/ipv4/ip_gre.c
For comments look at net/ipv4/ip_gre.c --ANK
*/
#define IP6_SIT_HASH_SIZE 16
#define HASH(addr) (((__force u32)addr^((__force u32)addr>>4))&0xF)
static bool log_ecn_error = true;
module_param(log_ecn_error, bool, 0644);
MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
static int ipip6_tunnel_init(struct net_device *dev);
static void ipip6_tunnel_setup(struct net_device *dev);
static void ipip6_dev_free(struct net_device *dev);
static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
__be32 *v4dst);
static struct rtnl_link_ops sit_link_ops __read_mostly;
static unsigned int sit_net_id __read_mostly;
struct sit_net {
struct ip_tunnel __rcu *tunnels_r_l[IP6_SIT_HASH_SIZE];
struct ip_tunnel __rcu *tunnels_r[IP6_SIT_HASH_SIZE];
struct ip_tunnel __rcu *tunnels_l[IP6_SIT_HASH_SIZE];
struct ip_tunnel __rcu *tunnels_wc[1];
struct ip_tunnel __rcu **tunnels[4];
struct net_device *fb_tunnel_dev;
};
static inline struct sit_net *dev_to_sit_net(struct net_device *dev)
{
struct ip_tunnel *t = netdev_priv(dev);
return net_generic(t->net, sit_net_id);
}
/*
* Must be invoked with rcu_read_lock
*/
static struct ip_tunnel *ipip6_tunnel_lookup(struct net *net,
struct net_device *dev,
__be32 remote, __be32 local,
int sifindex)
{
unsigned int h0 = HASH(remote);
unsigned int h1 = HASH(local);
struct ip_tunnel *t;
struct sit_net *sitn = net_generic(net, sit_net_id);
int ifindex = dev ? dev->ifindex : 0;
for_each_ip_tunnel_rcu(t, sitn->tunnels_r_l[h0 ^ h1]) {
if (local == t->parms.iph.saddr &&
remote == t->parms.iph.daddr &&
(!dev || !t->parms.link || ifindex == t->parms.link ||
sifindex == t->parms.link) &&
(t->dev->flags & IFF_UP))
return t;
}
for_each_ip_tunnel_rcu(t, sitn->tunnels_r[h0]) {
if (remote == t->parms.iph.daddr &&
(!dev || !t->parms.link || ifindex == t->parms.link ||
sifindex == t->parms.link) &&
(t->dev->flags & IFF_UP))
return t;
}
for_each_ip_tunnel_rcu(t, sitn->tunnels_l[h1]) {
if (local == t->parms.iph.saddr &&
(!dev || !t->parms.link || ifindex == t->parms.link ||
sifindex == t->parms.link) &&
(t->dev->flags & IFF_UP))
return t;
}
t = rcu_dereference(sitn->tunnels_wc[0]);
if (t && (t->dev->flags & IFF_UP))
return t;
return NULL;
}
static struct ip_tunnel __rcu **__ipip6_bucket(struct sit_net *sitn,
struct ip_tunnel_parm *parms)
{
__be32 remote = parms->iph.daddr;
__be32 local = parms->iph.saddr;
unsigned int h = 0;
int prio = 0;
if (remote) {
prio |= 2;
h ^= HASH(remote);
}
if (local) {
prio |= 1;
h ^= HASH(local);
}
return &sitn->tunnels[prio][h];
}
static inline struct ip_tunnel __rcu **ipip6_bucket(struct sit_net *sitn,
struct ip_tunnel *t)
{
return __ipip6_bucket(sitn, &t->parms);
}
static void ipip6_tunnel_unlink(struct sit_net *sitn, struct ip_tunnel *t)
{
struct ip_tunnel __rcu **tp;
struct ip_tunnel *iter;
for (tp = ipip6_bucket(sitn, t);
(iter = rtnl_dereference(*tp)) != NULL;
tp = &iter->next) {
if (t == iter) {
rcu_assign_pointer(*tp, t->next);
break;
}
}
}
static void ipip6_tunnel_link(struct sit_net *sitn, struct ip_tunnel *t)
{
struct ip_tunnel __rcu **tp = ipip6_bucket(sitn, t);
rcu_assign_pointer(t->next, rtnl_dereference(*tp));
rcu_assign_pointer(*tp, t);
}
static void ipip6_tunnel_clone_6rd(struct net_device *dev, struct sit_net *sitn)
{
#ifdef CONFIG_IPV6_SIT_6RD
struct ip_tunnel *t = netdev_priv(dev);
if (dev == sitn->fb_tunnel_dev || !sitn->fb_tunnel_dev) {
ipv6_addr_set(&t->ip6rd.prefix, htonl(0x20020000), 0, 0, 0);
t->ip6rd.relay_prefix = 0;
t->ip6rd.prefixlen = 16;
t->ip6rd.relay_prefixlen = 0;
} else {
struct ip_tunnel *t0 = netdev_priv(sitn->fb_tunnel_dev);
memcpy(&t->ip6rd, &t0->ip6rd, sizeof(t->ip6rd));
}
#endif
}
static int ipip6_tunnel_create(struct net_device *dev)
{
struct ip_tunnel *t = netdev_priv(dev);
struct net *net = dev_net(dev);
struct sit_net *sitn = net_generic(net, sit_net_id);
int err;
__dev_addr_set(dev, &t->parms.iph.saddr, 4);
memcpy(dev->broadcast, &t->parms.iph.daddr, 4);
if ((__force u16)t->parms.i_flags & SIT_ISATAP)
dev->priv_flags |= IFF_ISATAP;
dev->rtnl_link_ops = &sit_link_ops;
err = register_netdevice(dev);
if (err < 0)
goto out;
ipip6_tunnel_clone_6rd(dev, sitn);
ipip6_tunnel_link(sitn, t);
return 0;
out:
return err;
}
static struct ip_tunnel *ipip6_tunnel_locate(struct net *net,
struct ip_tunnel_parm *parms, int create)
{
__be32 remote = parms->iph.daddr;
__be32 local = parms->iph.saddr;
struct ip_tunnel *t, *nt;
struct ip_tunnel __rcu **tp;
struct net_device *dev;
char name[IFNAMSIZ];
struct sit_net *sitn = net_generic(net, sit_net_id);
for (tp = __ipip6_bucket(sitn, parms);
(t = rtnl_dereference(*tp)) != NULL;
tp = &t->next) {
if (local == t->parms.iph.saddr &&
remote == t->parms.iph.daddr &&
parms->link == t->parms.link) {
if (create)
return NULL;
else
return t;
}
}
if (!create)
goto failed;
if (parms->name[0]) {
if (!dev_valid_name(parms->name))
goto failed;
strscpy(name, parms->name, IFNAMSIZ);
} else {
strcpy(name, "sit%d");
}
dev = alloc_netdev(sizeof(*t), name, NET_NAME_UNKNOWN,
ipip6_tunnel_setup);
if (!dev)
return NULL;
dev_net_set(dev, net);
nt = netdev_priv(dev);
nt->parms = *parms;
if (ipip6_tunnel_create(dev) < 0)
goto failed_free;
if (!parms->name[0])
strcpy(parms->name, dev->name);
return nt;
failed_free:
free_netdev(dev);
failed:
return NULL;
}
#define for_each_prl_rcu(start) \
for (prl = rcu_dereference(start); \
prl; \
prl = rcu_dereference(prl->next))
static struct ip_tunnel_prl_entry *
__ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr)
{
struct ip_tunnel_prl_entry *prl;
for_each_prl_rcu(t->prl)
if (prl->addr == addr)
break;
return prl;
}
static int ipip6_tunnel_get_prl(struct net_device *dev, struct ip_tunnel_prl __user *a)
{
struct ip_tunnel *t = netdev_priv(dev);
struct ip_tunnel_prl kprl, *kp;
struct ip_tunnel_prl_entry *prl;
unsigned int cmax, c = 0, ca, len;
int ret = 0;
if (dev == dev_to_sit_net(dev)->fb_tunnel_dev)
return -EINVAL;
if (copy_from_user(&kprl, a, sizeof(kprl)))
return -EFAULT;
cmax = kprl.datalen / sizeof(kprl);
if (cmax > 1 && kprl.addr != htonl(INADDR_ANY))
cmax = 1;
/* For simple GET or for root users,
* we try harder to allocate.
*/
kp = (cmax <= 1 || capable(CAP_NET_ADMIN)) ?
kcalloc(cmax, sizeof(*kp), GFP_KERNEL_ACCOUNT | __GFP_NOWARN) :
NULL;
ca = min(t->prl_count, cmax);
if (!kp) {
/* We don't try hard to allocate much memory for
* non-root users.
* For root users, retry allocating enough memory for
* the answer.
*/
kp = kcalloc(ca, sizeof(*kp), GFP_ATOMIC | __GFP_ACCOUNT |
__GFP_NOWARN);
if (!kp) {
ret = -ENOMEM;
goto out;
}
}
rcu_read_lock();
for_each_prl_rcu(t->prl) {
if (c >= cmax)
break;
if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr)
continue;
kp[c].addr = prl->addr;
kp[c].flags = prl->flags;
c++;
if (kprl.addr != htonl(INADDR_ANY))
break;
}
rcu_read_unlock();
len = sizeof(*kp) * c;
ret = 0;
if ((len && copy_to_user(a + 1, kp, len)) || put_user(len, &a->datalen))
ret = -EFAULT;
kfree(kp);
out:
return ret;
}
static int
ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg)
{
struct ip_tunnel_prl_entry *p;
int err = 0;
if (a->addr == htonl(INADDR_ANY))
return -EINVAL;
ASSERT_RTNL();
for (p = rtnl_dereference(t->prl); p; p = rtnl_dereference(p->next)) {
if (p->addr == a->addr) {
if (chg) {
p->flags = a->flags;
goto out;
}
err = -EEXIST;
goto out;
}
}
if (chg) {
err = -ENXIO;
goto out;
}
p = kzalloc(sizeof(struct ip_tunnel_prl_entry), GFP_KERNEL);
if (!p) {
err = -ENOBUFS;
goto out;
}
p->next = t->prl;
p->addr = a->addr;
p->flags = a->flags;
t->prl_count++;
rcu_assign_pointer(t->prl, p);
out:
return err;
}
static void prl_list_destroy_rcu(struct rcu_head *head)
{
struct ip_tunnel_prl_entry *p, *n;
p = container_of(head, struct ip_tunnel_prl_entry, rcu_head);
do {
n = rcu_dereference_protected(p->next, 1);
kfree(p);
p = n;
} while (p);
}
static int
ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a)
{
struct ip_tunnel_prl_entry *x;
struct ip_tunnel_prl_entry __rcu **p;
int err = 0;
ASSERT_RTNL();
if (a && a->addr != htonl(INADDR_ANY)) {
for (p = &t->prl;
(x = rtnl_dereference(*p)) != NULL;
p = &x->next) {
if (x->addr == a->addr) {
*p = x->next;
kfree_rcu(x, rcu_head);
t->prl_count--;
goto out;
}
}
err = -ENXIO;
} else {
x = rtnl_dereference(t->prl);
if (x) {
t->prl_count = 0;
call_rcu(&x->rcu_head, prl_list_destroy_rcu);
t->prl = NULL;
}
}
out:
return err;
}
static int ipip6_tunnel_prl_ctl(struct net_device *dev,
struct ip_tunnel_prl __user *data, int cmd)
{
struct ip_tunnel *t = netdev_priv(dev);
struct ip_tunnel_prl prl;
int err;
if (!ns_capable(t->net->user_ns, CAP_NET_ADMIN))
return -EPERM;
if (dev == dev_to_sit_net(dev)->fb_tunnel_dev)
return -EINVAL;
if (copy_from_user(&prl, data, sizeof(prl)))
return -EFAULT;
switch (cmd) {
case SIOCDELPRL:
err = ipip6_tunnel_del_prl(t, &prl);
break;
case SIOCADDPRL:
case SIOCCHGPRL:
err = ipip6_tunnel_add_prl(t, &prl, cmd == SIOCCHGPRL);
break;
}
dst_cache_reset(&t->dst_cache);
netdev_state_change(dev);
return err;
}
static int
isatap_chksrc(struct sk_buff *skb, const struct iphdr *iph, struct ip_tunnel *t)
{
struct ip_tunnel_prl_entry *p;
int ok = 1;
rcu_read_lock();
p = __ipip6_tunnel_locate_prl(t, iph->saddr);
if (p) {
if (p->flags & PRL_DEFAULT)
skb->ndisc_nodetype = NDISC_NODETYPE_DEFAULT;
else
skb->ndisc_nodetype = NDISC_NODETYPE_NODEFAULT;
} else {
const struct in6_addr *addr6 = &ipv6_hdr(skb)->saddr;
if (ipv6_addr_is_isatap(addr6) &&
(addr6->s6_addr32[3] == iph->saddr) &&
ipv6_chk_prefix(addr6, t->dev))
skb->ndisc_nodetype = NDISC_NODETYPE_HOST;
else
ok = 0;
}
rcu_read_unlock();
return ok;
}
static void ipip6_tunnel_uninit(struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct sit_net *sitn = net_generic(tunnel->net, sit_net_id);
if (dev == sitn->fb_tunnel_dev) {
RCU_INIT_POINTER(sitn->tunnels_wc[0], NULL);
} else {
ipip6_tunnel_unlink(sitn, tunnel);
ipip6_tunnel_del_prl(tunnel, NULL);
}
dst_cache_reset(&tunnel->dst_cache);
netdev_put(dev, &tunnel->dev_tracker);
}
static int ipip6_err(struct sk_buff *skb, u32 info)
{
const struct iphdr *iph = (const struct iphdr *)skb->data;
const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
unsigned int data_len = 0;
struct ip_tunnel *t;
int sifindex;
int err;
switch (type) {
default:
case ICMP_PARAMETERPROB:
return 0;
case ICMP_DEST_UNREACH:
switch (code) {
case ICMP_SR_FAILED:
/* Impossible event. */
return 0;
default:
/* All others are translated to HOST_UNREACH.
rfc2003 contains "deep thoughts" about NET_UNREACH,
I believe they are just ether pollution. --ANK
*/
break;
}
break;
case ICMP_TIME_EXCEEDED:
if (code != ICMP_EXC_TTL)
return 0;
data_len = icmp_hdr(skb)->un.reserved[1] * 4; /* RFC 4884 4.1 */
break;
case ICMP_REDIRECT:
break;
}
err = -ENOENT;
sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
t = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
iph->daddr, iph->saddr, sifindex);
if (!t)
goto out;
if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
ipv4_update_pmtu(skb, dev_net(skb->dev), info,
t->parms.link, iph->protocol);
err = 0;
goto out;
}
if (type == ICMP_REDIRECT) {
ipv4_redirect(skb, dev_net(skb->dev), t->parms.link,
iph->protocol);
err = 0;
goto out;
}
err = 0;
if (__in6_dev_get(skb->dev) &&
!ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4, type, data_len))
goto out;
if (t->parms.iph.daddr == 0)
goto out;
if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
goto out;
if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
t->err_count++;
else
t->err_count = 1;
t->err_time = jiffies;
out:
return err;
}
static inline bool is_spoofed_6rd(struct ip_tunnel *tunnel, const __be32 v4addr,
const struct in6_addr *v6addr)
{
__be32 v4embed = 0;
if (check_6rd(tunnel, v6addr, &v4embed) && v4addr != v4embed)
return true;
return false;
}
/* Checks if an address matches an address on the tunnel interface.
* Used to detect the NAT of proto 41 packets and let them pass spoofing test.
* Long story:
* This function is called after we considered the packet as spoofed
* in is_spoofed_6rd.
* We may have a router that is doing NAT for proto 41 packets
* for an internal station. Destination a.a.a.a/PREFIX:bbbb:bbbb
* will be translated to n.n.n.n/PREFIX:bbbb:bbbb. And is_spoofed_6rd
* function will return true, dropping the packet.
* But, we can still check if is spoofed against the IP
* addresses associated with the interface.
*/
static bool only_dnatted(const struct ip_tunnel *tunnel,
const struct in6_addr *v6dst)
{
int prefix_len;
#ifdef CONFIG_IPV6_SIT_6RD
prefix_len = tunnel->ip6rd.prefixlen + 32
- tunnel->ip6rd.relay_prefixlen;
#else
prefix_len = 48;
#endif
return ipv6_chk_custom_prefix(v6dst, prefix_len, tunnel->dev);
}
/* Returns true if a packet is spoofed */
static bool packet_is_spoofed(struct sk_buff *skb,
const struct iphdr *iph,
struct ip_tunnel *tunnel)
{
const struct ipv6hdr *ipv6h;
if (tunnel->dev->priv_flags & IFF_ISATAP) {
if (!isatap_chksrc(skb, iph, tunnel))
return true;
return false;
}
if (tunnel->dev->flags & IFF_POINTOPOINT)
return false;
ipv6h = ipv6_hdr(skb);
if (unlikely(is_spoofed_6rd(tunnel, iph->saddr, &ipv6h->saddr))) {
net_warn_ratelimited("Src spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
&iph->saddr, &ipv6h->saddr,
&iph->daddr, &ipv6h->daddr);
return true;
}
if (likely(!is_spoofed_6rd(tunnel, iph->daddr, &ipv6h->daddr)))
return false;
if (only_dnatted(tunnel, &ipv6h->daddr))
return false;
net_warn_ratelimited("Dst spoofed %pI4/%pI6c -> %pI4/%pI6c\n",
&iph->saddr, &ipv6h->saddr,
&iph->daddr, &ipv6h->daddr);
return true;
}
static int ipip6_rcv(struct sk_buff *skb)
{
const struct iphdr *iph = ip_hdr(skb);
struct ip_tunnel *tunnel;
int sifindex;
int err;
sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
iph->saddr, iph->daddr, sifindex);
if (tunnel) {
if (tunnel->parms.iph.protocol != IPPROTO_IPV6 &&
tunnel->parms.iph.protocol != 0)
goto out;
skb->mac_header = skb->network_header;
skb_reset_network_header(skb);
IPCB(skb)->flags = 0;
skb->dev = tunnel->dev;
if (packet_is_spoofed(skb, iph, tunnel)) {
DEV_STATS_INC(tunnel->dev, rx_errors);
goto out;
}
if (iptunnel_pull_header(skb, 0, htons(ETH_P_IPV6),
!net_eq(tunnel->net, dev_net(tunnel->dev))))
goto out;
/* skb can be uncloned in iptunnel_pull_header, so
* old iph is no longer valid
*/
iph = (const struct iphdr *)skb_mac_header(skb);
skb_reset_mac_header(skb);
err = IP_ECN_decapsulate(iph, skb);
if (unlikely(err)) {
if (log_ecn_error)
net_info_ratelimited("non-ECT from %pI4 with TOS=%#x\n",
&iph->saddr, iph->tos);
if (err > 1) {
DEV_STATS_INC(tunnel->dev, rx_frame_errors);
DEV_STATS_INC(tunnel->dev, rx_errors);
goto out;
}
}
dev_sw_netstats_rx_add(tunnel->dev, skb->len);
netif_rx(skb);
return 0;
}
/* no tunnel matched, let upstream know, ipsec may handle it */
return 1;
out:
kfree_skb(skb);
return 0;
}
static const struct tnl_ptk_info ipip_tpi = {
/* no tunnel info required for ipip. */
.proto = htons(ETH_P_IP),
};
#if IS_ENABLED(CONFIG_MPLS)
static const struct tnl_ptk_info mplsip_tpi = {
/* no tunnel info required for mplsip. */
.proto = htons(ETH_P_MPLS_UC),
};
#endif
static int sit_tunnel_rcv(struct sk_buff *skb, u8 ipproto)
{
const struct iphdr *iph;
struct ip_tunnel *tunnel;
int sifindex;
sifindex = netif_is_l3_master(skb->dev) ? IPCB(skb)->iif : 0;
iph = ip_hdr(skb);
tunnel = ipip6_tunnel_lookup(dev_net(skb->dev), skb->dev,
iph->saddr, iph->daddr, sifindex);
if (tunnel) {
const struct tnl_ptk_info *tpi;
if (tunnel->parms.iph.protocol != ipproto &&
tunnel->parms.iph.protocol != 0)
goto drop;
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
goto drop;
#if IS_ENABLED(CONFIG_MPLS)
if (ipproto == IPPROTO_MPLS)
tpi = &mplsip_tpi;
else
#endif
tpi = &ipip_tpi;
if (iptunnel_pull_header(skb, 0, tpi->proto, false))
goto drop;
skb_reset_mac_header(skb);
return ip_tunnel_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
}
return 1;
drop:
kfree_skb(skb);
return 0;
}
static int ipip_rcv(struct sk_buff *skb)
{
return sit_tunnel_rcv(skb, IPPROTO_IPIP);
}
#if IS_ENABLED(CONFIG_MPLS)
static int mplsip_rcv(struct sk_buff *skb)
{
return sit_tunnel_rcv(skb, IPPROTO_MPLS);
}
#endif
/*
* If the IPv6 address comes from 6rd / 6to4 (RFC 3056) addr space this function
* stores the embedded IPv4 address in v4dst and returns true.
*/
static bool check_6rd(struct ip_tunnel *tunnel, const struct in6_addr *v6dst,
__be32 *v4dst)
{
#ifdef CONFIG_IPV6_SIT_6RD
if (ipv6_prefix_equal(v6dst, &tunnel->ip6rd.prefix,
tunnel->ip6rd.prefixlen)) {
unsigned int pbw0, pbi0;
int pbi1;
u32 d;
pbw0 = tunnel->ip6rd.prefixlen >> 5;
pbi0 = tunnel->ip6rd.prefixlen & 0x1f;
d = tunnel->ip6rd.relay_prefixlen < 32 ?
(ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >>
tunnel->ip6rd.relay_prefixlen : 0;
pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen;
if (pbi1 > 0)
d |= ntohl(v6dst->s6_addr32[pbw0 + 1]) >>
(32 - pbi1);
*v4dst = tunnel->ip6rd.relay_prefix | htonl(d);
return true;
}
#else
if (v6dst->s6_addr16[0] == htons(0x2002)) {
/* 6to4 v6 addr has 16 bits prefix, 32 v4addr, 16 SLA, ... */
memcpy(v4dst, &v6dst->s6_addr16[1], 4);
return true;
}
#endif
return false;
}
static inline __be32 try_6rd(struct ip_tunnel *tunnel,
const struct in6_addr *v6dst)
{
__be32 dst = 0;
check_6rd(tunnel, v6dst, &dst);
return dst;
}
/*
* This function assumes it is being called from dev_queue_xmit()
* and that skb is filled properly by that function.
*/
static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
const struct iphdr *tiph = &tunnel->parms.iph;
const struct ipv6hdr *iph6 = ipv6_hdr(skb);
u8 tos = tunnel->parms.iph.tos;
__be16 df = tiph->frag_off;
struct rtable *rt; /* Route to the other host */
struct net_device *tdev; /* Device to other host */
unsigned int max_headroom; /* The extra header space needed */
__be32 dst = tiph->daddr;
struct flowi4 fl4;
int mtu;
const struct in6_addr *addr6;
int addr_type;
u8 ttl;
u8 protocol = IPPROTO_IPV6;
int t_hlen = tunnel->hlen + sizeof(struct iphdr);
if (tos == 1)
tos = ipv6_get_dsfield(iph6);
/* ISATAP (RFC4214) - must come before 6to4 */
if (dev->priv_flags & IFF_ISATAP) {
struct neighbour *neigh = NULL;
bool do_tx_error = false;
if (skb_dst(skb))
neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
if (!neigh) {
net_dbg_ratelimited("nexthop == NULL\n");
goto tx_error;
}
addr6 = (const struct in6_addr *)&neigh->primary_key;
addr_type = ipv6_addr_type(addr6);
if ((addr_type & IPV6_ADDR_UNICAST) &&
ipv6_addr_is_isatap(addr6))
dst = addr6->s6_addr32[3];
else
do_tx_error = true;
neigh_release(neigh);
if (do_tx_error)
goto tx_error;
}
if (!dst)
dst = try_6rd(tunnel, &iph6->daddr);
if (!dst) {
struct neighbour *neigh = NULL;
bool do_tx_error = false;
if (skb_dst(skb))
neigh = dst_neigh_lookup(skb_dst(skb), &iph6->daddr);
if (!neigh) {
net_dbg_ratelimited("nexthop == NULL\n");
goto tx_error;
}
addr6 = (const struct in6_addr *)&neigh->primary_key;
addr_type = ipv6_addr_type(addr6);
if (addr_type == IPV6_ADDR_ANY) {
addr6 = &ipv6_hdr(skb)->daddr;
addr_type = ipv6_addr_type(addr6);
}
if ((addr_type & IPV6_ADDR_COMPATv4) != 0)
dst = addr6->s6_addr32[3];
else
do_tx_error = true;
neigh_release(neigh);
if (do_tx_error)
goto tx_error;
}
flowi4_init_output(&fl4, tunnel->parms.link, tunnel->fwmark,
RT_TOS(tos), RT_SCOPE_UNIVERSE, IPPROTO_IPV6,
0, dst, tiph->saddr, 0, 0,
sock_net_uid(tunnel->net, NULL));
rt = dst_cache_get_ip4(&tunnel->dst_cache, &fl4.saddr);
if (!rt) {
rt = ip_route_output_flow(tunnel->net, &fl4, NULL);
if (IS_ERR(rt)) {
DEV_STATS_INC(dev, tx_carrier_errors);
goto tx_error_icmp;
}
dst_cache_set_ip4(&tunnel->dst_cache, &rt->dst, fl4.saddr);
}
if (rt->rt_type != RTN_UNICAST && rt->rt_type != RTN_LOCAL) {
ip_rt_put(rt);
DEV_STATS_INC(dev, tx_carrier_errors);
goto tx_error_icmp;
}
tdev = rt->dst.dev;
if (tdev == dev) {
ip_rt_put(rt);
DEV_STATS_INC(dev, collisions);
goto tx_error;
}
if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP4)) {
ip_rt_put(rt);
goto tx_error;
}
if (df) {
mtu = dst_mtu(&rt->dst) - t_hlen;
if (mtu < IPV4_MIN_MTU) {
DEV_STATS_INC(dev, collisions);
ip_rt_put(rt);
goto tx_error;
}
if (mtu < IPV6_MIN_MTU) {
mtu = IPV6_MIN_MTU;
df = 0;
}
if (tunnel->parms.iph.daddr)
skb_dst_update_pmtu_no_confirm(skb, mtu);
if (skb->len > mtu && !skb_is_gso(skb)) {
icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
ip_rt_put(rt);
goto tx_error;
}
}
if (tunnel->err_count > 0) {
if (time_before(jiffies,
tunnel->err_time + IPTUNNEL_ERR_TIMEO)) {
tunnel->err_count--;
dst_link_failure(skb);
} else
tunnel->err_count = 0;
}