| /* |
| * 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 struct tcf_common *tcf_nat_ht[NAT_TAB_MASK + 1]; |
| static u32 nat_idx_gen; |
| static DEFINE_RWLOCK(nat_lock); |
| |
| static struct tcf_hashinfo nat_hash_info = { |
| .htab = tcf_nat_ht, |
| .hmask = NAT_TAB_MASK, |
| .lock = &nat_lock, |
| }; |
| |
| static int tcf_nat_init(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; |
| struct tcf_common *pc; |
| |
| if (nla == NULL) |
| return -EINVAL; |
| |
| err = nla_parse_nested(tb, TCA_NAT_MAX, nla, NULL); |
| if (err < 0) |
| return err; |
| |
| if (tb[TCA_NAT_PARMS] == NULL || |
| nla_len(tb[TCA_NAT_PARMS]) < sizeof(*parm)) |
| return -EINVAL; |
| parm = nla_data(tb[TCA_NAT_PARMS]); |
| |
| pc = tcf_hash_check(parm->index, a, bind, &nat_hash_info); |
| if (!pc) { |
| pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind, |
| &nat_idx_gen, &nat_hash_info); |
| if (unlikely(!pc)) |
| return -ENOMEM; |
| p = to_tcf_nat(pc); |
| ret = ACT_P_CREATED; |
| } else { |
| p = to_tcf_nat(pc); |
| if (!ovr) { |
| tcf_hash_release(pc, bind, &nat_hash_info); |
| return -EEXIST; |
| } |
| } |
| |
| 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(pc, &nat_hash_info); |
| |
| return ret; |
| } |
| |
| static int tcf_nat_cleanup(struct tc_action *a, int bind) |
| { |
| struct tcf_nat *p = a->priv; |
| |
| return tcf_hash_release(&p->common, bind, &nat_hash_info); |
| } |
| |
| static int tcf_nat(struct sk_buff *skb, 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; |
| |
| 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; |
| |
| p->tcf_bstats.bytes += skb->len; |
| p->tcf_bstats.packets++; |
| |
| spin_unlock(&p->tcf_lock); |
| |
| if (unlikely(action == TC_ACT_SHOT)) |
| goto drop; |
| |
| if (!pskb_may_pull(skb, sizeof(*iph))) |
| 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)) && |
| 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); |
| } |
| |
| 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)) || |
| (skb_cloned(skb) && |
| !skb_clone_writable(skb, ihl + sizeof(*tcph)) && |
| 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)) || |
| (skb_cloned(skb) && |
| !skb_clone_writable(skb, ihl + sizeof(*udph)) && |
| 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) + sizeof(*iph))) |
| 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; |
| |
| 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)) && |
| 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, |
| 1); |
| break; |
| } |
| default: |
| break; |
| } |
| |
| 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; |
| struct tcf_t t; |
| int s; |
| |
| s = sizeof(*opt); |
| |
| /* netlink spinlocks held above us - must use ATOMIC */ |
| opt = kzalloc(s, GFP_ATOMIC); |
| if (unlikely(!opt)) |
| return -ENOBUFS; |
| |
| opt->old_addr = p->old_addr; |
| opt->new_addr = p->new_addr; |
| opt->mask = p->mask; |
| opt->flags = p->flags; |
| |
| opt->index = p->tcf_index; |
| opt->action = p->tcf_action; |
| opt->refcnt = p->tcf_refcnt - ref; |
| opt->bindcnt = p->tcf_bindcnt - bind; |
| |
| NLA_PUT(skb, TCA_NAT_PARMS, s, opt); |
| 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); |
| NLA_PUT(skb, TCA_NAT_TM, sizeof(t), &t); |
| |
| kfree(opt); |
| |
| return skb->len; |
| |
| nla_put_failure: |
| nlmsg_trim(skb, b); |
| kfree(opt); |
| return -1; |
| } |
| |
| static struct tc_action_ops act_nat_ops = { |
| .kind = "nat", |
| .hinfo = &nat_hash_info, |
| .type = TCA_ACT_NAT, |
| .capab = TCA_CAP_NONE, |
| .owner = THIS_MODULE, |
| .act = tcf_nat, |
| .dump = tcf_nat_dump, |
| .cleanup = tcf_nat_cleanup, |
| .lookup = tcf_hash_search, |
| .init = tcf_nat_init, |
| .walk = tcf_generic_walker |
| }; |
| |
| MODULE_DESCRIPTION("Stateless NAT actions"); |
| MODULE_LICENSE("GPL"); |
| |
| static int __init nat_init_module(void) |
| { |
| return tcf_register_action(&act_nat_ops); |
| } |
| |
| static void __exit nat_cleanup_module(void) |
| { |
| tcf_unregister_action(&act_nat_ops); |
| } |
| |
| module_init(nat_init_module); |
| module_exit(nat_cleanup_module); |