--- /dev/null
+/*
+ * Stateless NAT actions
+ *
+ * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * 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/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/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>
+
+
+#define NAT_TAB_MASK 15
+
+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, int ovr, int bind)
+{
+ struct nlattr *tb[TCA_NAT_MAX + 1];
+ struct tc_nat *parm;
+ int ret = 0, err;
+ struct tcf_nat *p;
+
+ if (nla == NULL)
+ return -EINVAL;
+
+ err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
+ if (err < 0)
+ return err;
+
+ if (tb[TCA_NAT_PARMS] == NULL)
+ return -EINVAL;
+ parm = nla_data(tb[TCA_NAT_PARMS]);
+
+ if (!tcf_hash_check(parm->index, a, bind)) {
+ ret = tcf_hash_create(parm->index, est, a, sizeof(*p), bind);
+ if (ret)
+ return ret;
+ ret = ACT_P_CREATED;
+ } else {
+ if (bind)
+ return 0;
+ tcf_hash_release(a, bind);
+ if (!ovr)
+ return -EEXIST;
+ }
+ p = to_tcf_nat(a);
+
+ spin_lock_bh(&p->tcf_lock);
+ p->old_addr = parm->old_addr;
+ p->new_addr = parm->new_addr;
+ p->mask = parm->mask;
+ p->flags = parm->flags;
+
+ p->tcf_action = parm->action;
+ spin_unlock_bh(&p->tcf_lock);
+
+ if (ret == ACT_P_CREATED)
+ tcf_hash_insert(a);
+
+ return ret;
+}
+
+static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
+ struct tcf_result *res)
+{
+ struct tcf_nat *p = a->priv;
+ struct iphdr *iph;
+ __be32 old_addr;
+ __be32 new_addr;
+ __be32 mask;
+ __be32 addr;
+ int egress;
+ int action;
+ int ihl;
+ int noff;
+
+ spin_lock(&p->tcf_lock);
+
+ p->tcf_tm.lastuse = jiffies;
+ old_addr = p->old_addr;
+ new_addr = p->new_addr;
+ mask = p->mask;
+ egress = p->flags & TCA_NAT_FLAG_EGRESS;
+ action = p->tcf_action;
+
+ bstats_update(&p->tcf_bstats, skb);
+
+ spin_unlock(&p->tcf_lock);
+
+ if (unlikely(action == TC_ACT_SHOT))
+ goto drop;
+
+ 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_cloned(skb) &&
+ !skb_clone_writable(skb, sizeof(*iph) + noff) &&
+ pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+ goto drop;
+
+ new_addr &= mask;
+ new_addr |= addr & ~mask;
+
+ /* Rewrite IP header */
+ 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;
+
+ /* It would be nice to share code with stateful NAT. */
+ 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_cloned(skb) &&
+ !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
+ pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+ goto drop;
+
+ tcph = (void *)(skb_network_header(skb) + ihl);
+ inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1);
+ break;
+ }
+ case IPPROTO_UDP:
+ {
+ struct udphdr *udph;
+
+ if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
+ (skb_cloned(skb) &&
+ !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
+ pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+ 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, 1);
+ 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 ((icmph->type != ICMP_DEST_UNREACH) &&
+ (icmph->type != ICMP_TIME_EXCEEDED) &&
+ (icmph->type != ICMP_PARAMETERPROB))
+ 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_cloned(skb) &&
+ !skb_clone_writable(skb, ihl + sizeof(*icmph) +
+ sizeof(*iph) + noff) &&
+ pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+ goto drop;
+
+ icmph = (void *)(skb_network_header(skb) + ihl);
+ iph = (void *)(icmph + 1);
+
+ new_addr &= mask;
+ new_addr |= addr & ~mask;
+
+ /* XXX Fix up the inner checksums. */
+ if (egress)
+ iph->daddr = new_addr;
+ else
+ iph->saddr = new_addr;
+
+ inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
+ 0);
+ break;
+ }
+ default:
+ break;
+ }
+
+out:
+ return action;
+
+drop:
+ spin_lock(&p->tcf_lock);
+ p->tcf_qstats.drops++;
+ spin_unlock(&p->tcf_lock);
+ 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);
+ struct tcf_nat *p = a->priv;
+ struct tc_nat opt = {
+ .old_addr = p->old_addr,
+ .new_addr = p->new_addr,
+ .mask = p->mask,
+ .flags = p->flags,
+
+ .index = p->tcf_index,
+ .action = p->tcf_action,
+ .refcnt = p->tcf_refcnt - ref,
+ .bindcnt = p->tcf_bindcnt - bind,
+ };
+ struct tcf_t t;
+
+ if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
+ goto nla_put_failure;
+ t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
+ t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
+ t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
+ if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t))
+ goto nla_put_failure;
+
+ return skb->len;
+
+nla_put_failure:
+ nlmsg_trim(skb, b);
+ return -1;
+}
+
+static struct tc_action_ops act_nat_ops = {
+ .kind = "nat",
+ .type = TCA_ACT_NAT,
+ .owner = THIS_MODULE,
+ .act = tcf_nat,
+ .dump = tcf_nat_dump,
+ .init = tcf_nat_init,
+};
+
+MODULE_DESCRIPTION("Stateless NAT actions");
+MODULE_LICENSE("GPL");
+
+static int __init nat_init_module(void)
+{
+ return tcf_register_action(&act_nat_ops, NAT_TAB_MASK);
+}
+
+static void __exit nat_cleanup_module(void)
+{
+ tcf_unregister_action(&act_nat_ops);
+}
+
+module_init(nat_init_module);
+module_exit(nat_cleanup_module);
Code Review / kvmfornfv.git / blobdiff