#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/tc_act/tc_nat.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/netlink.h>
#include <net/tc_act/tc_nat.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/tc_wrapper.h>
static struct tc_action_ops act_nat_ops;
static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
[TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
};
static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
struct tc_action **a, struct tcf_proto *tp,
u32 flags, struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
bool bind = flags & TCA_ACT_FLAGS_BIND;
struct tcf_nat_parms *nparm, *oparm;
struct nlattr *tb[TCA_NAT_MAX + 1];
struct tcf_chain *goto_ch = NULL;
struct tc_nat *parm;
int ret = 0, err;
struct tcf_nat *p;
u32 index;
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
NULL);
if (err < 0)
return err;
if (tb[TCA_NAT_PARMS] == NULL)
return -EINVAL;
parm = nla_data(tb[TCA_NAT_PARMS]);
index = parm->index;
err = tcf_idr_check_alloc(tn, &index, a, bind);
if (!err) {
ret = tcf_idr_create_from_flags(tn, index, est, a, &act_nat_ops,
bind, flags);
if (ret) {
tcf_idr_cleanup(tn, index);
return ret;
}
ret = ACT_P_CREATED;
} else if (err > 0) {
if (bind)
return ACT_P_BOUND;
if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
tcf_idr_release(*a, bind);
return -EEXIST;
}
} else {
return err;
}
err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
if (err < 0)
goto release_idr;
nparm = kzalloc_obj(*nparm);
if (!nparm) {
err = -ENOMEM;
goto release_idr;
}
nparm->old_addr = parm->old_addr;
nparm->new_addr = parm->new_addr;
nparm->mask = parm->mask;
nparm->flags = parm->flags;
nparm->action = parm->action;
p = to_tcf_nat(*a);
spin_lock_bh(&p->tcf_lock);
goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
oparm = rcu_replace_pointer(p->parms, nparm, lockdep_is_held(&p->tcf_lock));
spin_unlock_bh(&p->tcf_lock);
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
if (oparm)
kfree_rcu(oparm, rcu);
return ret;
release_idr:
tcf_idr_release(*a, bind);
return err;
}
TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb,
const struct tc_action *a,
struct tcf_result *res)
{
struct tcf_nat *p = to_tcf_nat(a);
struct tcf_nat_parms *parms;
struct iphdr *iph;
__be32 old_addr;
__be32 new_addr;
__be32 mask;
__be32 addr;
int egress;
int action;
int ihl;
int noff;
tcf_lastuse_update(&p->tcf_tm);
tcf_action_update_bstats(&p->common, skb);
parms = rcu_dereference_bh(p->parms);
action = parms->action;
if (unlikely(action == TC_ACT_SHOT))
goto drop;
old_addr = parms->old_addr;
new_addr = parms->new_addr;
mask = parms->mask;
egress = parms->flags & TCA_NAT_FLAG_EGRESS;
noff = skb_network_offset(skb);
if (!pskb_may_pull(skb, sizeof(*iph) + noff))
goto drop;
iph = ip_hdr(skb);
if (egress)
addr = iph->saddr;
else
addr = iph->daddr;
if (!((old_addr ^ addr) & mask)) {
if (skb_try_make_writable(skb, sizeof(*iph) + noff))
goto drop;
new_addr &= mask;
new_addr |= addr & ~mask;
iph = ip_hdr(skb);
if (egress)
iph->saddr = new_addr;
else
iph->daddr = new_addr;
csum_replace4(&iph->check, addr, new_addr);
} else if ((iph->frag_off & htons(IP_OFFSET)) ||
iph->protocol != IPPROTO_ICMP) {
goto out;
}
ihl = iph->ihl * 4;
switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
case IPPROTO_TCP:
{
struct tcphdr *tcph;
if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
goto drop;
tcph = (void *)(skb_network_header(skb) + ihl);
inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
true);
break;
}
case IPPROTO_UDP:
{
struct udphdr *udph;
if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
goto drop;
udph = (void *)(skb_network_header(skb) + ihl);
if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
inet_proto_csum_replace4(&udph->check, skb, addr,
new_addr, true);
if (!udph->check)
udph->check = CSUM_MANGLED_0;
}
break;
}
case IPPROTO_ICMP:
{
struct icmphdr *icmph;
if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
goto drop;
icmph = (void *)(skb_network_header(skb) + ihl);
if (!icmp_is_err(icmph->type))
break;
if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
noff))
goto drop;
icmph = (void *)(skb_network_header(skb) + ihl);
iph = (void *)(icmph + 1);
if (egress)
addr = iph->daddr;
else
addr = iph->saddr;
if ((old_addr ^ addr) & mask)
break;
if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
sizeof(*iph) + noff))
goto drop;
icmph = (void *)(skb_network_header(skb) + ihl);
iph = (void *)(icmph + 1);
new_addr &= mask;
new_addr |= addr & ~mask;
if (egress)
iph->daddr = new_addr;
else
iph->saddr = new_addr;
inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
false);
break;
}
default:
break;
}
out:
return action;
drop:
tcf_action_inc_drop_qstats(&p->common);
return TC_ACT_SHOT;
}
static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
int bind, int ref)
{
unsigned char *b = skb_tail_pointer(skb);
const struct tcf_nat *p = to_tcf_nat(a);
const struct tcf_nat_parms *parms;
struct tc_nat opt = {
.index = p->tcf_index,
.refcnt = refcount_read(&p->tcf_refcnt) - ref,
.bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
};
struct tcf_t t;
rcu_read_lock();
parms = rcu_dereference(p->parms);
opt.action = parms->action;
opt.old_addr = parms->old_addr;
opt.new_addr = parms->new_addr;
opt.mask = parms->mask;
opt.flags = parms->flags;
if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
goto nla_put_failure;
tcf_tm_dump(&t, &p->tcf_tm);
if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
goto nla_put_failure;
rcu_read_unlock();
return skb->len;
nla_put_failure:
rcu_read_unlock();
nlmsg_trim(skb, b);
return -1;
}
static void tcf_nat_cleanup(struct tc_action *a)
{
struct tcf_nat *p = to_tcf_nat(a);
struct tcf_nat_parms *parms;
parms = rcu_dereference_protected(p->parms, 1);
if (parms)
kfree_rcu(parms, rcu);
}
static struct tc_action_ops act_nat_ops = {
.kind = "nat",
.id = TCA_ID_NAT,
.owner = THIS_MODULE,
.act = tcf_nat_act,
.dump = tcf_nat_dump,
.init = tcf_nat_init,
.cleanup = tcf_nat_cleanup,
.size = sizeof(struct tcf_nat),
};
MODULE_ALIAS_NET_ACT("nat");
static __net_init int nat_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
return tc_action_net_init(net, tn, &act_nat_ops);
}
static void __net_exit nat_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, act_nat_ops.net_id);
}
static struct pernet_operations nat_net_ops = {
.init = nat_init_net,
.exit_batch = nat_exit_net,
.id = &act_nat_ops.net_id,
.size = sizeof(struct tc_action_net),
};
MODULE_DESCRIPTION("Stateless NAT actions");
MODULE_LICENSE("GPL");
static int __init nat_init_module(void)
{
return tcf_register_action(&act_nat_ops, &nat_net_ops);
}
static void __exit nat_cleanup_module(void)
{
tcf_unregister_action(&act_nat_ops, &nat_net_ops);
}
module_init(nat_init_module);
module_exit(nat_cleanup_module);
