Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
635 lines
18 KiB
C
635 lines
18 KiB
C
/* NAT for netfilter; shared with compatibility layer. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/timer.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/vmalloc.h>
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#include <net/checksum.h>
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#include <net/icmp.h>
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#include <net/ip.h>
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#include <net/tcp.h> /* For tcp_prot in getorigdst */
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#include <linux/icmp.h>
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#include <linux/udp.h>
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#include <linux/jhash.h>
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#include <linux/netfilter_ipv4/ip_conntrack.h>
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#include <linux/netfilter_ipv4/ip_conntrack_core.h>
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#include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
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#include <linux/netfilter_ipv4/ip_nat.h>
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#include <linux/netfilter_ipv4/ip_nat_protocol.h>
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#include <linux/netfilter_ipv4/ip_nat_core.h>
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#include <linux/netfilter_ipv4/ip_nat_helper.h>
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#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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DEFINE_RWLOCK(ip_nat_lock);
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/* Calculated at init based on memory size */
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static unsigned int ip_nat_htable_size;
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static struct list_head *bysource;
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#define MAX_IP_NAT_PROTO 256
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static struct ip_nat_protocol *ip_nat_protos[MAX_IP_NAT_PROTO];
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static inline struct ip_nat_protocol *
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__ip_nat_proto_find(u_int8_t protonum)
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{
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return rcu_dereference(ip_nat_protos[protonum]);
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}
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struct ip_nat_protocol *
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ip_nat_proto_find_get(u_int8_t protonum)
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{
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struct ip_nat_protocol *p;
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rcu_read_lock();
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p = __ip_nat_proto_find(protonum);
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if (!try_module_get(p->me))
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p = &ip_nat_unknown_protocol;
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rcu_read_unlock();
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return p;
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}
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EXPORT_SYMBOL_GPL(ip_nat_proto_find_get);
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void
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ip_nat_proto_put(struct ip_nat_protocol *p)
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{
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module_put(p->me);
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}
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EXPORT_SYMBOL_GPL(ip_nat_proto_put);
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/* We keep an extra hash for each conntrack, for fast searching. */
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static inline unsigned int
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hash_by_src(const struct ip_conntrack_tuple *tuple)
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{
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/* Original src, to ensure we map it consistently if poss. */
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return jhash_3words((__force u32)tuple->src.ip, tuple->src.u.all,
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tuple->dst.protonum, 0) % ip_nat_htable_size;
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}
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/* Noone using conntrack by the time this called. */
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static void ip_nat_cleanup_conntrack(struct ip_conntrack *conn)
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{
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if (!(conn->status & IPS_NAT_DONE_MASK))
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return;
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write_lock_bh(&ip_nat_lock);
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list_del(&conn->nat.info.bysource);
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write_unlock_bh(&ip_nat_lock);
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}
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/* Is this tuple already taken? (not by us) */
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int
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ip_nat_used_tuple(const struct ip_conntrack_tuple *tuple,
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const struct ip_conntrack *ignored_conntrack)
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{
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/* Conntrack tracking doesn't keep track of outgoing tuples; only
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incoming ones. NAT means they don't have a fixed mapping,
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so we invert the tuple and look for the incoming reply.
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We could keep a separate hash if this proves too slow. */
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struct ip_conntrack_tuple reply;
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invert_tuplepr(&reply, tuple);
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return ip_conntrack_tuple_taken(&reply, ignored_conntrack);
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}
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EXPORT_SYMBOL(ip_nat_used_tuple);
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/* If we source map this tuple so reply looks like reply_tuple, will
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* that meet the constraints of range. */
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static int
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in_range(const struct ip_conntrack_tuple *tuple,
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const struct ip_nat_range *range)
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{
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struct ip_nat_protocol *proto;
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int ret = 0;
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/* If we are supposed to map IPs, then we must be in the
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range specified, otherwise let this drag us onto a new src IP. */
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if (range->flags & IP_NAT_RANGE_MAP_IPS) {
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if (ntohl(tuple->src.ip) < ntohl(range->min_ip)
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|| ntohl(tuple->src.ip) > ntohl(range->max_ip))
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return 0;
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}
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rcu_read_lock();
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proto = __ip_nat_proto_find(tuple->dst.protonum);
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if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)
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|| proto->in_range(tuple, IP_NAT_MANIP_SRC,
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&range->min, &range->max))
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ret = 1;
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rcu_read_unlock();
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return ret;
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}
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static inline int
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same_src(const struct ip_conntrack *ct,
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const struct ip_conntrack_tuple *tuple)
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{
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return (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum
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== tuple->dst.protonum
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&& ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip
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== tuple->src.ip
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&& ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.all
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== tuple->src.u.all);
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}
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/* Only called for SRC manip */
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static int
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find_appropriate_src(const struct ip_conntrack_tuple *tuple,
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struct ip_conntrack_tuple *result,
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const struct ip_nat_range *range)
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{
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unsigned int h = hash_by_src(tuple);
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struct ip_conntrack *ct;
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read_lock_bh(&ip_nat_lock);
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list_for_each_entry(ct, &bysource[h], nat.info.bysource) {
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if (same_src(ct, tuple)) {
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/* Copy source part from reply tuple. */
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invert_tuplepr(result,
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&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
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result->dst = tuple->dst;
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if (in_range(result, range)) {
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read_unlock_bh(&ip_nat_lock);
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return 1;
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}
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}
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}
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read_unlock_bh(&ip_nat_lock);
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return 0;
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}
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/* For [FUTURE] fragmentation handling, we want the least-used
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src-ip/dst-ip/proto triple. Fairness doesn't come into it. Thus
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if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
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1-65535, we don't do pro-rata allocation based on ports; we choose
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the ip with the lowest src-ip/dst-ip/proto usage.
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*/
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static void
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find_best_ips_proto(struct ip_conntrack_tuple *tuple,
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const struct ip_nat_range *range,
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const struct ip_conntrack *conntrack,
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enum ip_nat_manip_type maniptype)
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{
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__be32 *var_ipp;
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/* Host order */
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u_int32_t minip, maxip, j;
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/* No IP mapping? Do nothing. */
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if (!(range->flags & IP_NAT_RANGE_MAP_IPS))
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return;
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if (maniptype == IP_NAT_MANIP_SRC)
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var_ipp = &tuple->src.ip;
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else
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var_ipp = &tuple->dst.ip;
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/* Fast path: only one choice. */
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if (range->min_ip == range->max_ip) {
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*var_ipp = range->min_ip;
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return;
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}
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/* Hashing source and destination IPs gives a fairly even
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* spread in practice (if there are a small number of IPs
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* involved, there usually aren't that many connections
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* anyway). The consistency means that servers see the same
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* client coming from the same IP (some Internet Banking sites
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* like this), even across reboots. */
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minip = ntohl(range->min_ip);
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maxip = ntohl(range->max_ip);
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j = jhash_2words((__force u32)tuple->src.ip, (__force u32)tuple->dst.ip, 0);
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*var_ipp = htonl(minip + j % (maxip - minip + 1));
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}
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/* Manipulate the tuple into the range given. For NF_IP_POST_ROUTING,
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* we change the source to map into the range. For NF_IP_PRE_ROUTING
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* and NF_IP_LOCAL_OUT, we change the destination to map into the
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* range. It might not be possible to get a unique tuple, but we try.
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* At worst (or if we race), we will end up with a final duplicate in
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* __ip_conntrack_confirm and drop the packet. */
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static void
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get_unique_tuple(struct ip_conntrack_tuple *tuple,
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const struct ip_conntrack_tuple *orig_tuple,
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const struct ip_nat_range *range,
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struct ip_conntrack *conntrack,
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enum ip_nat_manip_type maniptype)
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{
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struct ip_nat_protocol *proto;
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/* 1) If this srcip/proto/src-proto-part is currently mapped,
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and that same mapping gives a unique tuple within the given
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range, use that.
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This is only required for source (ie. NAT/masq) mappings.
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So far, we don't do local source mappings, so multiple
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manips not an issue. */
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if (maniptype == IP_NAT_MANIP_SRC) {
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if (find_appropriate_src(orig_tuple, tuple, range)) {
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DEBUGP("get_unique_tuple: Found current src map\n");
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if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
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if (!ip_nat_used_tuple(tuple, conntrack))
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return;
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}
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}
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/* 2) Select the least-used IP/proto combination in the given
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range. */
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*tuple = *orig_tuple;
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find_best_ips_proto(tuple, range, conntrack, maniptype);
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/* 3) The per-protocol part of the manip is made to map into
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the range to make a unique tuple. */
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rcu_read_lock();
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proto = __ip_nat_proto_find(orig_tuple->dst.protonum);
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/* Change protocol info to have some randomization */
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if (range->flags & IP_NAT_RANGE_PROTO_RANDOM) {
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proto->unique_tuple(tuple, range, maniptype, conntrack);
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goto out;
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}
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/* Only bother mapping if it's not already in range and unique */
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if ((!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)
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|| proto->in_range(tuple, maniptype, &range->min, &range->max))
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&& !ip_nat_used_tuple(tuple, conntrack))
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goto out;
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/* Last change: get protocol to try to obtain unique tuple. */
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proto->unique_tuple(tuple, range, maniptype, conntrack);
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out:
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rcu_read_unlock();
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}
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unsigned int
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ip_nat_setup_info(struct ip_conntrack *conntrack,
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const struct ip_nat_range *range,
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unsigned int hooknum)
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{
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struct ip_conntrack_tuple curr_tuple, new_tuple;
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struct ip_nat_info *info = &conntrack->nat.info;
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int have_to_hash = !(conntrack->status & IPS_NAT_DONE_MASK);
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enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);
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IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
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|| hooknum == NF_IP_POST_ROUTING
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|| hooknum == NF_IP_LOCAL_IN
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|| hooknum == NF_IP_LOCAL_OUT);
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BUG_ON(ip_nat_initialized(conntrack, maniptype));
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/* What we've got will look like inverse of reply. Normally
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this is what is in the conntrack, except for prior
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manipulations (future optimization: if num_manips == 0,
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orig_tp =
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conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple) */
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invert_tuplepr(&curr_tuple,
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&conntrack->tuplehash[IP_CT_DIR_REPLY].tuple);
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get_unique_tuple(&new_tuple, &curr_tuple, range, conntrack, maniptype);
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if (!ip_ct_tuple_equal(&new_tuple, &curr_tuple)) {
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struct ip_conntrack_tuple reply;
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/* Alter conntrack table so will recognize replies. */
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invert_tuplepr(&reply, &new_tuple);
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ip_conntrack_alter_reply(conntrack, &reply);
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/* Non-atomic: we own this at the moment. */
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if (maniptype == IP_NAT_MANIP_SRC)
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conntrack->status |= IPS_SRC_NAT;
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else
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conntrack->status |= IPS_DST_NAT;
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}
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/* Place in source hash if this is the first time. */
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if (have_to_hash) {
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unsigned int srchash
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= hash_by_src(&conntrack->tuplehash[IP_CT_DIR_ORIGINAL]
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.tuple);
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write_lock_bh(&ip_nat_lock);
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list_add(&info->bysource, &bysource[srchash]);
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write_unlock_bh(&ip_nat_lock);
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}
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/* It's done. */
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if (maniptype == IP_NAT_MANIP_DST)
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set_bit(IPS_DST_NAT_DONE_BIT, &conntrack->status);
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else
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set_bit(IPS_SRC_NAT_DONE_BIT, &conntrack->status);
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return NF_ACCEPT;
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}
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EXPORT_SYMBOL(ip_nat_setup_info);
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/* Returns true if succeeded. */
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static int
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manip_pkt(u_int16_t proto,
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struct sk_buff **pskb,
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unsigned int iphdroff,
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const struct ip_conntrack_tuple *target,
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enum ip_nat_manip_type maniptype)
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{
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struct iphdr *iph;
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struct ip_nat_protocol *p;
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if (!skb_make_writable(pskb, iphdroff + sizeof(*iph)))
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return 0;
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iph = (void *)(*pskb)->data + iphdroff;
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/* Manipulate protcol part. */
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/* rcu_read_lock()ed by nf_hook_slow */
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p = __ip_nat_proto_find(proto);
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if (!p->manip_pkt(pskb, iphdroff, target, maniptype))
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return 0;
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iph = (void *)(*pskb)->data + iphdroff;
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if (maniptype == IP_NAT_MANIP_SRC) {
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nf_csum_replace4(&iph->check, iph->saddr, target->src.ip);
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iph->saddr = target->src.ip;
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} else {
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nf_csum_replace4(&iph->check, iph->daddr, target->dst.ip);
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iph->daddr = target->dst.ip;
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}
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return 1;
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}
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/* Do packet manipulations according to ip_nat_setup_info. */
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unsigned int ip_nat_packet(struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned int hooknum,
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struct sk_buff **pskb)
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{
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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unsigned long statusbit;
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enum ip_nat_manip_type mtype = HOOK2MANIP(hooknum);
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if (mtype == IP_NAT_MANIP_SRC)
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statusbit = IPS_SRC_NAT;
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else
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statusbit = IPS_DST_NAT;
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/* Invert if this is reply dir. */
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if (dir == IP_CT_DIR_REPLY)
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statusbit ^= IPS_NAT_MASK;
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/* Non-atomic: these bits don't change. */
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if (ct->status & statusbit) {
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struct ip_conntrack_tuple target;
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/* We are aiming to look like inverse of other direction. */
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invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
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if (!manip_pkt(target.dst.protonum, pskb, 0, &target, mtype))
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return NF_DROP;
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}
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return NF_ACCEPT;
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}
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EXPORT_SYMBOL_GPL(ip_nat_packet);
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/* Dir is direction ICMP is coming from (opposite to packet it contains) */
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int ip_nat_icmp_reply_translation(struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned int hooknum,
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struct sk_buff **pskb)
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{
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struct {
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struct icmphdr icmp;
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struct iphdr ip;
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} *inside;
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struct ip_conntrack_protocol *proto;
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struct ip_conntrack_tuple inner, target;
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int hdrlen = (*pskb)->nh.iph->ihl * 4;
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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unsigned long statusbit;
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enum ip_nat_manip_type manip = HOOK2MANIP(hooknum);
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if (!skb_make_writable(pskb, hdrlen + sizeof(*inside)))
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return 0;
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inside = (void *)(*pskb)->data + (*pskb)->nh.iph->ihl*4;
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/* We're actually going to mangle it beyond trivial checksum
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adjustment, so make sure the current checksum is correct. */
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if (nf_ip_checksum(*pskb, hooknum, hdrlen, 0))
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return 0;
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/* Must be RELATED */
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IP_NF_ASSERT((*pskb)->nfctinfo == IP_CT_RELATED ||
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(*pskb)->nfctinfo == IP_CT_RELATED+IP_CT_IS_REPLY);
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/* Redirects on non-null nats must be dropped, else they'll
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start talking to each other without our translation, and be
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confused... --RR */
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if (inside->icmp.type == ICMP_REDIRECT) {
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/* If NAT isn't finished, assume it and drop. */
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if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
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return 0;
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if (ct->status & IPS_NAT_MASK)
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return 0;
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}
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DEBUGP("icmp_reply_translation: translating error %p manp %u dir %s\n",
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*pskb, manip, dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY");
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/* rcu_read_lock()ed by nf_hook_slow */
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proto = __ip_conntrack_proto_find(inside->ip.protocol);
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if (!ip_ct_get_tuple(&inside->ip, *pskb, (*pskb)->nh.iph->ihl*4 +
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sizeof(struct icmphdr) + inside->ip.ihl*4,
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&inner, proto))
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return 0;
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/* Change inner back to look like incoming packet. We do the
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opposite manip on this hook to normal, because it might not
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pass all hooks (locally-generated ICMP). Consider incoming
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packet: PREROUTING (DST manip), routing produces ICMP, goes
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through POSTROUTING (which must correct the DST manip). */
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if (!manip_pkt(inside->ip.protocol, pskb,
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(*pskb)->nh.iph->ihl*4
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|
+ sizeof(inside->icmp),
|
|
&ct->tuplehash[!dir].tuple,
|
|
!manip))
|
|
return 0;
|
|
|
|
if ((*pskb)->ip_summed != CHECKSUM_PARTIAL) {
|
|
/* Reloading "inside" here since manip_pkt inner. */
|
|
inside = (void *)(*pskb)->data + (*pskb)->nh.iph->ihl*4;
|
|
inside->icmp.checksum = 0;
|
|
inside->icmp.checksum = csum_fold(skb_checksum(*pskb, hdrlen,
|
|
(*pskb)->len - hdrlen,
|
|
0));
|
|
}
|
|
|
|
/* Change outer to look the reply to an incoming packet
|
|
* (proto 0 means don't invert per-proto part). */
|
|
if (manip == IP_NAT_MANIP_SRC)
|
|
statusbit = IPS_SRC_NAT;
|
|
else
|
|
statusbit = IPS_DST_NAT;
|
|
|
|
/* Invert if this is reply dir. */
|
|
if (dir == IP_CT_DIR_REPLY)
|
|
statusbit ^= IPS_NAT_MASK;
|
|
|
|
if (ct->status & statusbit) {
|
|
invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
|
|
if (!manip_pkt(0, pskb, 0, &target, manip))
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(ip_nat_icmp_reply_translation);
|
|
|
|
/* Protocol registration. */
|
|
int ip_nat_protocol_register(struct ip_nat_protocol *proto)
|
|
{
|
|
int ret = 0;
|
|
|
|
write_lock_bh(&ip_nat_lock);
|
|
if (ip_nat_protos[proto->protonum] != &ip_nat_unknown_protocol) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
rcu_assign_pointer(ip_nat_protos[proto->protonum], proto);
|
|
out:
|
|
write_unlock_bh(&ip_nat_lock);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(ip_nat_protocol_register);
|
|
|
|
/* Noone stores the protocol anywhere; simply delete it. */
|
|
void ip_nat_protocol_unregister(struct ip_nat_protocol *proto)
|
|
{
|
|
write_lock_bh(&ip_nat_lock);
|
|
rcu_assign_pointer(ip_nat_protos[proto->protonum],
|
|
&ip_nat_unknown_protocol);
|
|
write_unlock_bh(&ip_nat_lock);
|
|
synchronize_rcu();
|
|
}
|
|
EXPORT_SYMBOL(ip_nat_protocol_unregister);
|
|
|
|
#if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \
|
|
defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE)
|
|
int
|
|
ip_nat_port_range_to_nfattr(struct sk_buff *skb,
|
|
const struct ip_nat_range *range)
|
|
{
|
|
NFA_PUT(skb, CTA_PROTONAT_PORT_MIN, sizeof(__be16),
|
|
&range->min.tcp.port);
|
|
NFA_PUT(skb, CTA_PROTONAT_PORT_MAX, sizeof(__be16),
|
|
&range->max.tcp.port);
|
|
|
|
return 0;
|
|
|
|
nfattr_failure:
|
|
return -1;
|
|
}
|
|
|
|
int
|
|
ip_nat_port_nfattr_to_range(struct nfattr *tb[], struct ip_nat_range *range)
|
|
{
|
|
int ret = 0;
|
|
|
|
/* we have to return whether we actually parsed something or not */
|
|
|
|
if (tb[CTA_PROTONAT_PORT_MIN-1]) {
|
|
ret = 1;
|
|
range->min.tcp.port =
|
|
*(__be16 *)NFA_DATA(tb[CTA_PROTONAT_PORT_MIN-1]);
|
|
}
|
|
|
|
if (!tb[CTA_PROTONAT_PORT_MAX-1]) {
|
|
if (ret)
|
|
range->max.tcp.port = range->min.tcp.port;
|
|
} else {
|
|
ret = 1;
|
|
range->max.tcp.port =
|
|
*(__be16 *)NFA_DATA(tb[CTA_PROTONAT_PORT_MAX-1]);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(ip_nat_port_nfattr_to_range);
|
|
EXPORT_SYMBOL_GPL(ip_nat_port_range_to_nfattr);
|
|
#endif
|
|
|
|
static int __init ip_nat_init(void)
|
|
{
|
|
size_t i;
|
|
|
|
/* Leave them the same for the moment. */
|
|
ip_nat_htable_size = ip_conntrack_htable_size;
|
|
|
|
/* One vmalloc for both hash tables */
|
|
bysource = vmalloc(sizeof(struct list_head) * ip_nat_htable_size);
|
|
if (!bysource)
|
|
return -ENOMEM;
|
|
|
|
/* Sew in builtin protocols. */
|
|
write_lock_bh(&ip_nat_lock);
|
|
for (i = 0; i < MAX_IP_NAT_PROTO; i++)
|
|
rcu_assign_pointer(ip_nat_protos[i], &ip_nat_unknown_protocol);
|
|
rcu_assign_pointer(ip_nat_protos[IPPROTO_TCP], &ip_nat_protocol_tcp);
|
|
rcu_assign_pointer(ip_nat_protos[IPPROTO_UDP], &ip_nat_protocol_udp);
|
|
rcu_assign_pointer(ip_nat_protos[IPPROTO_ICMP], &ip_nat_protocol_icmp);
|
|
write_unlock_bh(&ip_nat_lock);
|
|
|
|
for (i = 0; i < ip_nat_htable_size; i++) {
|
|
INIT_LIST_HEAD(&bysource[i]);
|
|
}
|
|
|
|
/* FIXME: Man, this is a hack. <SIGH> */
|
|
IP_NF_ASSERT(rcu_dereference(ip_conntrack_destroyed) == NULL);
|
|
rcu_assign_pointer(ip_conntrack_destroyed, ip_nat_cleanup_conntrack);
|
|
|
|
/* Initialize fake conntrack so that NAT will skip it */
|
|
ip_conntrack_untracked.status |= IPS_NAT_DONE_MASK;
|
|
return 0;
|
|
}
|
|
|
|
/* Clear NAT section of all conntracks, in case we're loaded again. */
|
|
static int clean_nat(struct ip_conntrack *i, void *data)
|
|
{
|
|
memset(&i->nat, 0, sizeof(i->nat));
|
|
i->status &= ~(IPS_NAT_MASK | IPS_NAT_DONE_MASK | IPS_SEQ_ADJUST);
|
|
return 0;
|
|
}
|
|
|
|
static void __exit ip_nat_cleanup(void)
|
|
{
|
|
ip_ct_iterate_cleanup(&clean_nat, NULL);
|
|
rcu_assign_pointer(ip_conntrack_destroyed, NULL);
|
|
synchronize_rcu();
|
|
vfree(bysource);
|
|
}
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|
|
module_init(ip_nat_init);
|
|
module_exit(ip_nat_cleanup);
|