1 // SPDX-License-Identifier: GPL-2.0-only
3 * (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5 * (C) 2011 Patrick McHardy <kaber@trash.net>
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 #include <linux/module.h>
11 #include <linux/types.h>
12 #include <linux/timer.h>
13 #include <linux/skbuff.h>
14 #include <linux/gfp.h>
16 #include <linux/siphash.h>
17 #include <linux/rtnetlink.h>
19 #include <net/netfilter/nf_conntrack_bpf.h>
20 #include <net/netfilter/nf_conntrack_core.h>
21 #include <net/netfilter/nf_conntrack_helper.h>
22 #include <net/netfilter/nf_conntrack_seqadj.h>
23 #include <net/netfilter/nf_conntrack_zones.h>
24 #include <net/netfilter/nf_nat.h>
25 #include <net/netfilter/nf_nat_helper.h>
26 #include <uapi/linux/netfilter/nf_nat.h>
28 #include "nf_internals.h"
30 #define NF_NAT_MAX_ATTEMPTS 128
31 #define NF_NAT_HARDER_THRESH (NF_NAT_MAX_ATTEMPTS / 4)
33 static spinlock_t nf_nat_locks[CONNTRACK_LOCKS];
35 static DEFINE_MUTEX(nf_nat_proto_mutex);
36 static unsigned int nat_net_id __read_mostly;
38 static struct hlist_head *nf_nat_bysource __read_mostly;
39 static unsigned int nf_nat_htable_size __read_mostly;
40 static siphash_aligned_key_t nf_nat_hash_rnd;
42 struct nf_nat_lookup_hook_priv {
43 struct nf_hook_entries __rcu *entries;
45 struct rcu_head rcu_head;
48 struct nf_nat_hooks_net {
49 struct nf_hook_ops *nat_hook_ops;
54 struct nf_nat_hooks_net nat_proto_net[NFPROTO_NUMPROTO];
58 static void nf_nat_ipv4_decode_session(struct sk_buff *skb,
59 const struct nf_conn *ct,
60 enum ip_conntrack_dir dir,
61 unsigned long statusbit,
64 const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
65 struct flowi4 *fl4 = &fl->u.ip4;
67 if (ct->status & statusbit) {
68 fl4->daddr = t->dst.u3.ip;
69 if (t->dst.protonum == IPPROTO_TCP ||
70 t->dst.protonum == IPPROTO_UDP ||
71 t->dst.protonum == IPPROTO_UDPLITE ||
72 t->dst.protonum == IPPROTO_DCCP ||
73 t->dst.protonum == IPPROTO_SCTP)
74 fl4->fl4_dport = t->dst.u.all;
77 statusbit ^= IPS_NAT_MASK;
79 if (ct->status & statusbit) {
80 fl4->saddr = t->src.u3.ip;
81 if (t->dst.protonum == IPPROTO_TCP ||
82 t->dst.protonum == IPPROTO_UDP ||
83 t->dst.protonum == IPPROTO_UDPLITE ||
84 t->dst.protonum == IPPROTO_DCCP ||
85 t->dst.protonum == IPPROTO_SCTP)
86 fl4->fl4_sport = t->src.u.all;
90 static void nf_nat_ipv6_decode_session(struct sk_buff *skb,
91 const struct nf_conn *ct,
92 enum ip_conntrack_dir dir,
93 unsigned long statusbit,
96 #if IS_ENABLED(CONFIG_IPV6)
97 const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
98 struct flowi6 *fl6 = &fl->u.ip6;
100 if (ct->status & statusbit) {
101 fl6->daddr = t->dst.u3.in6;
102 if (t->dst.protonum == IPPROTO_TCP ||
103 t->dst.protonum == IPPROTO_UDP ||
104 t->dst.protonum == IPPROTO_UDPLITE ||
105 t->dst.protonum == IPPROTO_DCCP ||
106 t->dst.protonum == IPPROTO_SCTP)
107 fl6->fl6_dport = t->dst.u.all;
110 statusbit ^= IPS_NAT_MASK;
112 if (ct->status & statusbit) {
113 fl6->saddr = t->src.u3.in6;
114 if (t->dst.protonum == IPPROTO_TCP ||
115 t->dst.protonum == IPPROTO_UDP ||
116 t->dst.protonum == IPPROTO_UDPLITE ||
117 t->dst.protonum == IPPROTO_DCCP ||
118 t->dst.protonum == IPPROTO_SCTP)
119 fl6->fl6_sport = t->src.u.all;
124 static void __nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl)
126 const struct nf_conn *ct;
127 enum ip_conntrack_info ctinfo;
128 enum ip_conntrack_dir dir;
129 unsigned long statusbit;
132 ct = nf_ct_get(skb, &ctinfo);
136 family = nf_ct_l3num(ct);
137 dir = CTINFO2DIR(ctinfo);
138 if (dir == IP_CT_DIR_ORIGINAL)
139 statusbit = IPS_DST_NAT;
141 statusbit = IPS_SRC_NAT;
145 nf_nat_ipv4_decode_session(skb, ct, dir, statusbit, fl);
148 nf_nat_ipv6_decode_session(skb, ct, dir, statusbit, fl);
152 #endif /* CONFIG_XFRM */
154 /* We keep an extra hash for each conntrack, for fast searching. */
156 hash_by_src(const struct net *net,
157 const struct nf_conntrack_zone *zone,
158 const struct nf_conntrack_tuple *tuple)
162 struct nf_conntrack_man src;
166 } __aligned(SIPHASH_ALIGNMENT) combined;
168 get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
170 memset(&combined, 0, sizeof(combined));
172 /* Original src, to ensure we map it consistently if poss. */
173 combined.src = tuple->src;
174 combined.net_mix = net_hash_mix(net);
175 combined.protonum = tuple->dst.protonum;
177 /* Zone ID can be used provided its valid for both directions */
178 if (zone->dir == NF_CT_DEFAULT_ZONE_DIR)
179 combined.zone = zone->id;
181 hash = siphash(&combined, sizeof(combined), &nf_nat_hash_rnd);
183 return reciprocal_scale(hash, nf_nat_htable_size);
186 /* Is this tuple already taken? (not by us) */
188 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
189 const struct nf_conn *ignored_conntrack)
191 /* Conntrack tracking doesn't keep track of outgoing tuples; only
192 * incoming ones. NAT means they don't have a fixed mapping,
193 * so we invert the tuple and look for the incoming reply.
195 * We could keep a separate hash if this proves too slow.
197 struct nf_conntrack_tuple reply;
199 nf_ct_invert_tuple(&reply, tuple);
200 return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
203 static bool nf_nat_may_kill(struct nf_conn *ct, unsigned long flags)
205 static const unsigned long flags_refuse = IPS_FIXED_TIMEOUT |
207 static const unsigned long flags_needed = IPS_SRC_NAT;
208 enum tcp_conntrack old_state;
210 old_state = READ_ONCE(ct->proto.tcp.state);
211 if (old_state < TCP_CONNTRACK_TIME_WAIT)
214 if (flags & flags_refuse)
217 return (flags & flags_needed) == flags_needed;
220 /* reverse direction will send packets to new source, so
221 * make sure such packets are invalid.
223 static bool nf_seq_has_advanced(const struct nf_conn *old, const struct nf_conn *new)
225 return (__s32)(new->proto.tcp.seen[0].td_end -
226 old->proto.tcp.seen[0].td_end) > 0;
230 nf_nat_used_tuple_harder(const struct nf_conntrack_tuple *tuple,
231 const struct nf_conn *ignored_conntrack,
232 unsigned int attempts_left)
234 static const unsigned long flags_offload = IPS_OFFLOAD | IPS_HW_OFFLOAD;
235 struct nf_conntrack_tuple_hash *thash;
236 const struct nf_conntrack_zone *zone;
237 struct nf_conntrack_tuple reply;
243 nf_ct_invert_tuple(&reply, tuple);
245 if (attempts_left > NF_NAT_HARDER_THRESH ||
246 tuple->dst.protonum != IPPROTO_TCP ||
247 ignored_conntrack->proto.tcp.state != TCP_CONNTRACK_SYN_SENT)
248 return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
250 /* :ast few attempts to find a free tcp port. Destructive
251 * action: evict colliding if its in timewait state and the
252 * tcp sequence number has advanced past the one used by the
255 net = nf_ct_net(ignored_conntrack);
256 zone = nf_ct_zone(ignored_conntrack);
258 thash = nf_conntrack_find_get(net, zone, &reply);
262 ct = nf_ct_tuplehash_to_ctrack(thash);
264 if (thash->tuple.dst.dir == IP_CT_DIR_ORIGINAL)
267 if (WARN_ON_ONCE(ct == ignored_conntrack))
270 flags = READ_ONCE(ct->status);
271 if (!nf_nat_may_kill(ct, flags))
274 if (!nf_seq_has_advanced(ct, ignored_conntrack))
277 /* Even if we can evict do not reuse if entry is offloaded. */
279 taken = flags & flags_offload;
285 static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
286 const struct nf_nat_range2 *range)
288 if (t->src.l3num == NFPROTO_IPV4)
289 return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
290 ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
292 return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
293 ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
296 /* Is the manipable part of the tuple between min and max incl? */
297 static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
298 enum nf_nat_manip_type maniptype,
299 const union nf_conntrack_man_proto *min,
300 const union nf_conntrack_man_proto *max)
304 switch (tuple->dst.protonum) {
307 return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
308 ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
309 case IPPROTO_GRE: /* all fall though */
312 case IPPROTO_UDPLITE:
315 if (maniptype == NF_NAT_MANIP_SRC)
316 port = tuple->src.u.all;
318 port = tuple->dst.u.all;
320 return ntohs(port) >= ntohs(min->all) &&
321 ntohs(port) <= ntohs(max->all);
327 /* If we source map this tuple so reply looks like reply_tuple, will
328 * that meet the constraints of range.
330 static int nf_in_range(const struct nf_conntrack_tuple *tuple,
331 const struct nf_nat_range2 *range)
333 /* If we are supposed to map IPs, then we must be in the
334 * range specified, otherwise let this drag us onto a new src IP.
336 if (range->flags & NF_NAT_RANGE_MAP_IPS &&
337 !nf_nat_inet_in_range(tuple, range))
340 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
343 return l4proto_in_range(tuple, NF_NAT_MANIP_SRC,
344 &range->min_proto, &range->max_proto);
348 same_src(const struct nf_conn *ct,
349 const struct nf_conntrack_tuple *tuple)
351 const struct nf_conntrack_tuple *t;
353 t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
354 return (t->dst.protonum == tuple->dst.protonum &&
355 nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
356 t->src.u.all == tuple->src.u.all);
359 /* Only called for SRC manip */
361 find_appropriate_src(struct net *net,
362 const struct nf_conntrack_zone *zone,
363 const struct nf_conntrack_tuple *tuple,
364 struct nf_conntrack_tuple *result,
365 const struct nf_nat_range2 *range)
367 unsigned int h = hash_by_src(net, zone, tuple);
368 const struct nf_conn *ct;
370 hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
371 if (same_src(ct, tuple) &&
372 net_eq(net, nf_ct_net(ct)) &&
373 nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
374 /* Copy source part from reply tuple. */
375 nf_ct_invert_tuple(result,
376 &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
377 result->dst = tuple->dst;
379 if (nf_in_range(result, range))
386 /* For [FUTURE] fragmentation handling, we want the least-used
387 * src-ip/dst-ip/proto triple. Fairness doesn't come into it. Thus
388 * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
389 * 1-65535, we don't do pro-rata allocation based on ports; we choose
390 * the ip with the lowest src-ip/dst-ip/proto usage.
393 find_best_ips_proto(const struct nf_conntrack_zone *zone,
394 struct nf_conntrack_tuple *tuple,
395 const struct nf_nat_range2 *range,
396 const struct nf_conn *ct,
397 enum nf_nat_manip_type maniptype)
399 union nf_inet_addr *var_ipp;
402 u32 minip, maxip, j, dist;
405 /* No IP mapping? Do nothing. */
406 if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
409 if (maniptype == NF_NAT_MANIP_SRC)
410 var_ipp = &tuple->src.u3;
412 var_ipp = &tuple->dst.u3;
414 /* Fast path: only one choice. */
415 if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
416 *var_ipp = range->min_addr;
420 if (nf_ct_l3num(ct) == NFPROTO_IPV4)
421 max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
423 max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
425 /* Hashing source and destination IPs gives a fairly even
426 * spread in practice (if there are a small number of IPs
427 * involved, there usually aren't that many connections
428 * anyway). The consistency means that servers see the same
429 * client coming from the same IP (some Internet Banking sites
430 * like this), even across reboots.
432 j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
433 range->flags & NF_NAT_RANGE_PERSISTENT ?
434 0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id);
437 for (i = 0; i <= max; i++) {
438 /* If first bytes of the address are at the maximum, use the
439 * distance. Otherwise use the full range.
442 minip = ntohl((__force __be32)range->min_addr.all[i]);
443 maxip = ntohl((__force __be32)range->max_addr.all[i]);
444 dist = maxip - minip + 1;
450 var_ipp->all[i] = (__force __u32)
451 htonl(minip + reciprocal_scale(j, dist));
452 if (var_ipp->all[i] != range->max_addr.all[i])
455 if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
456 j ^= (__force u32)tuple->dst.u3.all[i];
460 /* Alter the per-proto part of the tuple (depending on maniptype), to
461 * give a unique tuple in the given range if possible.
463 * Per-protocol part of tuple is initialized to the incoming packet.
465 static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
466 const struct nf_nat_range2 *range,
467 enum nf_nat_manip_type maniptype,
468 const struct nf_conn *ct)
470 unsigned int range_size, min, max, i, attempts;
474 switch (tuple->dst.protonum) {
477 /* id is same for either direction... */
478 keyptr = &tuple->src.u.icmp.id;
479 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
483 min = ntohs(range->min_proto.icmp.id);
484 range_size = ntohs(range->max_proto.icmp.id) -
485 ntohs(range->min_proto.icmp.id) + 1;
488 #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
490 /* If there is no master conntrack we are not PPTP,
491 do not change tuples */
495 if (maniptype == NF_NAT_MANIP_SRC)
496 keyptr = &tuple->src.u.gre.key;
498 keyptr = &tuple->dst.u.gre.key;
500 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
504 min = ntohs(range->min_proto.gre.key);
505 range_size = ntohs(range->max_proto.gre.key) - min + 1;
510 case IPPROTO_UDPLITE:
514 if (maniptype == NF_NAT_MANIP_SRC)
515 keyptr = &tuple->src.u.all;
517 keyptr = &tuple->dst.u.all;
524 /* If no range specified... */
525 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
526 /* If it's dst rewrite, can't change port */
527 if (maniptype == NF_NAT_MANIP_DST)
530 if (ntohs(*keyptr) < 1024) {
531 /* Loose convention: >> 512 is credential passing */
532 if (ntohs(*keyptr) < 512) {
534 range_size = 511 - min + 1;
537 range_size = 1023 - min + 1;
541 range_size = 65535 - 1024 + 1;
544 min = ntohs(range->min_proto.all);
545 max = ntohs(range->max_proto.all);
546 if (unlikely(max < min))
548 range_size = max - min + 1;
552 if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
553 off = (ntohs(*keyptr) - ntohs(range->base_proto.all));
554 else if ((range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL) ||
555 maniptype != NF_NAT_MANIP_DST)
556 off = get_random_u16();
560 attempts = range_size;
561 if (attempts > NF_NAT_MAX_ATTEMPTS)
562 attempts = NF_NAT_MAX_ATTEMPTS;
564 /* We are in softirq; doing a search of the entire range risks
565 * soft lockup when all tuples are already used.
567 * If we can't find any free port from first offset, pick a new
568 * one and try again, with ever smaller search window.
571 for (i = 0; i < attempts; i++, off++) {
572 *keyptr = htons(min + off % range_size);
573 if (!nf_nat_used_tuple_harder(tuple, ct, attempts - i))
577 if (attempts >= range_size || attempts < 16)
580 off = get_random_u16();
584 /* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
585 * we change the source to map into the range. For NF_INET_PRE_ROUTING
586 * and NF_INET_LOCAL_OUT, we change the destination to map into the
587 * range. It might not be possible to get a unique tuple, but we try.
588 * At worst (or if we race), we will end up with a final duplicate in
589 * __nf_conntrack_confirm and drop the packet. */
591 get_unique_tuple(struct nf_conntrack_tuple *tuple,
592 const struct nf_conntrack_tuple *orig_tuple,
593 const struct nf_nat_range2 *range,
595 enum nf_nat_manip_type maniptype)
597 const struct nf_conntrack_zone *zone;
598 struct net *net = nf_ct_net(ct);
600 zone = nf_ct_zone(ct);
602 /* 1) If this srcip/proto/src-proto-part is currently mapped,
603 * and that same mapping gives a unique tuple within the given
606 * This is only required for source (ie. NAT/masq) mappings.
607 * So far, we don't do local source mappings, so multiple
608 * manips not an issue.
610 if (maniptype == NF_NAT_MANIP_SRC &&
611 !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
612 /* try the original tuple first */
613 if (nf_in_range(orig_tuple, range)) {
614 if (!nf_nat_used_tuple(orig_tuple, ct)) {
615 *tuple = *orig_tuple;
618 } else if (find_appropriate_src(net, zone,
619 orig_tuple, tuple, range)) {
620 pr_debug("get_unique_tuple: Found current src map\n");
621 if (!nf_nat_used_tuple(tuple, ct))
626 /* 2) Select the least-used IP/proto combination in the given range */
627 *tuple = *orig_tuple;
628 find_best_ips_proto(zone, tuple, range, ct, maniptype);
630 /* 3) The per-protocol part of the manip is made to map into
631 * the range to make a unique tuple.
634 /* Only bother mapping if it's not already in range and unique */
635 if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
636 if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
637 if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
638 l4proto_in_range(tuple, maniptype,
640 &range->max_proto) &&
641 (range->min_proto.all == range->max_proto.all ||
642 !nf_nat_used_tuple(tuple, ct)))
644 } else if (!nf_nat_used_tuple(tuple, ct)) {
649 /* Last chance: get protocol to try to obtain unique tuple. */
650 nf_nat_l4proto_unique_tuple(tuple, range, maniptype, ct);
653 struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct)
655 struct nf_conn_nat *nat = nfct_nat(ct);
659 if (!nf_ct_is_confirmed(ct))
660 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
664 EXPORT_SYMBOL_GPL(nf_ct_nat_ext_add);
667 nf_nat_setup_info(struct nf_conn *ct,
668 const struct nf_nat_range2 *range,
669 enum nf_nat_manip_type maniptype)
671 struct net *net = nf_ct_net(ct);
672 struct nf_conntrack_tuple curr_tuple, new_tuple;
674 /* Can't setup nat info for confirmed ct. */
675 if (nf_ct_is_confirmed(ct))
678 WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
679 maniptype != NF_NAT_MANIP_DST);
681 if (WARN_ON(nf_nat_initialized(ct, maniptype)))
684 /* What we've got will look like inverse of reply. Normally
685 * this is what is in the conntrack, except for prior
686 * manipulations (future optimization: if num_manips == 0,
687 * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)
689 nf_ct_invert_tuple(&curr_tuple,
690 &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
692 get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
694 if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
695 struct nf_conntrack_tuple reply;
697 /* Alter conntrack table so will recognize replies. */
698 nf_ct_invert_tuple(&reply, &new_tuple);
699 nf_conntrack_alter_reply(ct, &reply);
701 /* Non-atomic: we own this at the moment. */
702 if (maniptype == NF_NAT_MANIP_SRC)
703 ct->status |= IPS_SRC_NAT;
705 ct->status |= IPS_DST_NAT;
707 if (nfct_help(ct) && !nfct_seqadj(ct))
708 if (!nfct_seqadj_ext_add(ct))
712 if (maniptype == NF_NAT_MANIP_SRC) {
713 unsigned int srchash;
716 srchash = hash_by_src(net, nf_ct_zone(ct),
717 &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
718 lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS];
720 hlist_add_head_rcu(&ct->nat_bysource,
721 &nf_nat_bysource[srchash]);
722 spin_unlock_bh(lock);
726 if (maniptype == NF_NAT_MANIP_DST)
727 ct->status |= IPS_DST_NAT_DONE;
729 ct->status |= IPS_SRC_NAT_DONE;
733 EXPORT_SYMBOL(nf_nat_setup_info);
736 __nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip)
738 /* Force range to this IP; let proto decide mapping for
739 * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
740 * Use reply in case it's already been mangled (eg local packet).
742 union nf_inet_addr ip =
743 (manip == NF_NAT_MANIP_SRC ?
744 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 :
745 ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3);
746 struct nf_nat_range2 range = {
747 .flags = NF_NAT_RANGE_MAP_IPS,
751 return nf_nat_setup_info(ct, &range, manip);
755 nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
757 return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum));
759 EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding);
761 /* Do packet manipulations according to nf_nat_setup_info. */
762 unsigned int nf_nat_packet(struct nf_conn *ct,
763 enum ip_conntrack_info ctinfo,
764 unsigned int hooknum,
767 enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
768 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
769 unsigned int verdict = NF_ACCEPT;
770 unsigned long statusbit;
772 if (mtype == NF_NAT_MANIP_SRC)
773 statusbit = IPS_SRC_NAT;
775 statusbit = IPS_DST_NAT;
777 /* Invert if this is reply dir. */
778 if (dir == IP_CT_DIR_REPLY)
779 statusbit ^= IPS_NAT_MASK;
781 /* Non-atomic: these bits don't change. */
782 if (ct->status & statusbit)
783 verdict = nf_nat_manip_pkt(skb, ct, mtype, dir);
787 EXPORT_SYMBOL_GPL(nf_nat_packet);
789 static bool in_vrf_postrouting(const struct nf_hook_state *state)
791 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
792 if (state->hook == NF_INET_POST_ROUTING &&
793 netif_is_l3_master(state->out))
800 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
801 const struct nf_hook_state *state)
804 enum ip_conntrack_info ctinfo;
805 struct nf_conn_nat *nat;
806 /* maniptype == SRC for postrouting. */
807 enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
809 ct = nf_ct_get(skb, &ctinfo);
810 /* Can't track? It's not due to stress, or conntrack would
811 * have dropped it. Hence it's the user's responsibilty to
812 * packet filter it out, or implement conntrack/NAT for that
815 if (!ct || in_vrf_postrouting(state))
822 case IP_CT_RELATED_REPLY:
823 /* Only ICMPs can be IP_CT_IS_REPLY. Fallthrough */
825 /* Seen it before? This can happen for loopback, retrans,
828 if (!nf_nat_initialized(ct, maniptype)) {
829 struct nf_nat_lookup_hook_priv *lpriv = priv;
830 struct nf_hook_entries *e = rcu_dereference(lpriv->entries);
837 for (i = 0; i < e->num_hook_entries; i++) {
838 ret = e->hooks[i].hook(e->hooks[i].priv, skb,
840 if (ret != NF_ACCEPT)
842 if (nf_nat_initialized(ct, maniptype))
846 ret = nf_nat_alloc_null_binding(ct, state->hook);
847 if (ret != NF_ACCEPT)
850 pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n",
851 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
853 if (nf_nat_oif_changed(state->hook, ctinfo, nat,
860 WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
861 ctinfo != IP_CT_ESTABLISHED_REPLY);
862 if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
866 return nf_nat_packet(ct, ctinfo, state->hook, skb);
869 nf_ct_kill_acct(ct, ctinfo, skb);
872 EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
874 struct nf_nat_proto_clean {
879 /* kill conntracks with affected NAT section */
880 static int nf_nat_proto_remove(struct nf_conn *i, void *data)
882 const struct nf_nat_proto_clean *clean = data;
884 if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
885 (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
888 return i->status & IPS_NAT_MASK ? 1 : 0;
891 static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
895 h = hash_by_src(nf_ct_net(ct), nf_ct_zone(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
896 spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
897 hlist_del_rcu(&ct->nat_bysource);
898 spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
901 static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
903 if (nf_nat_proto_remove(ct, data))
906 /* This module is being removed and conntrack has nat null binding.
907 * Remove it from bysource hash, as the table will be freed soon.
909 * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack()
910 * will delete entry from already-freed table.
912 if (test_and_clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status))
913 nf_nat_cleanup_conntrack(ct);
915 /* don't delete conntrack. Although that would make things a lot
916 * simpler, we'd end up flushing all conntracks on nat rmmod.
921 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
923 #include <linux/netfilter/nfnetlink.h>
924 #include <linux/netfilter/nfnetlink_conntrack.h>
926 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
927 [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
928 [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
931 static int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
932 struct nf_nat_range2 *range)
934 if (tb[CTA_PROTONAT_PORT_MIN]) {
935 range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
936 range->max_proto.all = range->min_proto.all;
937 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
939 if (tb[CTA_PROTONAT_PORT_MAX]) {
940 range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
941 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
946 static int nfnetlink_parse_nat_proto(struct nlattr *attr,
947 const struct nf_conn *ct,
948 struct nf_nat_range2 *range)
950 struct nlattr *tb[CTA_PROTONAT_MAX+1];
953 err = nla_parse_nested_deprecated(tb, CTA_PROTONAT_MAX, attr,
954 protonat_nla_policy, NULL);
958 return nf_nat_l4proto_nlattr_to_range(tb, range);
961 static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
962 [CTA_NAT_V4_MINIP] = { .type = NLA_U32 },
963 [CTA_NAT_V4_MAXIP] = { .type = NLA_U32 },
964 [CTA_NAT_V6_MINIP] = { .len = sizeof(struct in6_addr) },
965 [CTA_NAT_V6_MAXIP] = { .len = sizeof(struct in6_addr) },
966 [CTA_NAT_PROTO] = { .type = NLA_NESTED },
969 static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[],
970 struct nf_nat_range2 *range)
972 if (tb[CTA_NAT_V4_MINIP]) {
973 range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
974 range->flags |= NF_NAT_RANGE_MAP_IPS;
977 if (tb[CTA_NAT_V4_MAXIP])
978 range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
980 range->max_addr.ip = range->min_addr.ip;
985 static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
986 struct nf_nat_range2 *range)
988 if (tb[CTA_NAT_V6_MINIP]) {
989 nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
990 sizeof(struct in6_addr));
991 range->flags |= NF_NAT_RANGE_MAP_IPS;
994 if (tb[CTA_NAT_V6_MAXIP])
995 nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
996 sizeof(struct in6_addr));
998 range->max_addr = range->min_addr;
1004 nfnetlink_parse_nat(const struct nlattr *nat,
1005 const struct nf_conn *ct, struct nf_nat_range2 *range)
1007 struct nlattr *tb[CTA_NAT_MAX+1];
1010 memset(range, 0, sizeof(*range));
1012 err = nla_parse_nested_deprecated(tb, CTA_NAT_MAX, nat,
1013 nat_nla_policy, NULL);
1017 switch (nf_ct_l3num(ct)) {
1019 err = nf_nat_ipv4_nlattr_to_range(tb, range);
1022 err = nf_nat_ipv6_nlattr_to_range(tb, range);
1025 err = -EPROTONOSUPPORT;
1032 if (!tb[CTA_NAT_PROTO])
1035 return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
1038 /* This function is called under rcu_read_lock() */
1040 nfnetlink_parse_nat_setup(struct nf_conn *ct,
1041 enum nf_nat_manip_type manip,
1042 const struct nlattr *attr)
1044 struct nf_nat_range2 range;
1047 /* Should not happen, restricted to creating new conntracks
1050 if (WARN_ON_ONCE(nf_nat_initialized(ct, manip)))
1053 /* No NAT information has been passed, allocate the null-binding */
1055 return __nf_nat_alloc_null_binding(ct, manip) == NF_DROP ? -ENOMEM : 0;
1057 err = nfnetlink_parse_nat(attr, ct, &range);
1061 return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
1065 nfnetlink_parse_nat_setup(struct nf_conn *ct,
1066 enum nf_nat_manip_type manip,
1067 const struct nlattr *attr)
1073 static struct nf_ct_helper_expectfn follow_master_nat = {
1074 .name = "nat-follow-master",
1075 .expectfn = nf_nat_follow_master,
1078 int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
1079 const struct nf_hook_ops *orig_nat_ops, unsigned int ops_count)
1081 struct nat_net *nat_net = net_generic(net, nat_net_id);
1082 struct nf_nat_hooks_net *nat_proto_net;
1083 struct nf_nat_lookup_hook_priv *priv;
1084 unsigned int hooknum = ops->hooknum;
1085 struct nf_hook_ops *nat_ops;
1088 if (WARN_ON_ONCE(pf >= ARRAY_SIZE(nat_net->nat_proto_net)))
1091 nat_proto_net = &nat_net->nat_proto_net[pf];
1093 for (i = 0; i < ops_count; i++) {
1094 if (orig_nat_ops[i].hooknum == hooknum) {
1100 if (WARN_ON_ONCE(i == ops_count))
1103 mutex_lock(&nf_nat_proto_mutex);
1104 if (!nat_proto_net->nat_hook_ops) {
1105 WARN_ON(nat_proto_net->users != 0);
1107 nat_ops = kmemdup(orig_nat_ops, sizeof(*orig_nat_ops) * ops_count, GFP_KERNEL);
1109 mutex_unlock(&nf_nat_proto_mutex);
1113 for (i = 0; i < ops_count; i++) {
1114 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1116 nat_ops[i].priv = priv;
1119 mutex_unlock(&nf_nat_proto_mutex);
1121 kfree(nat_ops[--i].priv);
1126 ret = nf_register_net_hooks(net, nat_ops, ops_count);
1128 mutex_unlock(&nf_nat_proto_mutex);
1129 for (i = 0; i < ops_count; i++)
1130 kfree(nat_ops[i].priv);
1135 nat_proto_net->nat_hook_ops = nat_ops;
1138 nat_ops = nat_proto_net->nat_hook_ops;
1139 priv = nat_ops[hooknum].priv;
1140 if (WARN_ON_ONCE(!priv)) {
1141 mutex_unlock(&nf_nat_proto_mutex);
1145 ret = nf_hook_entries_insert_raw(&priv->entries, ops);
1147 nat_proto_net->users++;
1149 mutex_unlock(&nf_nat_proto_mutex);
1153 void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
1154 unsigned int ops_count)
1156 struct nat_net *nat_net = net_generic(net, nat_net_id);
1157 struct nf_nat_hooks_net *nat_proto_net;
1158 struct nf_nat_lookup_hook_priv *priv;
1159 struct nf_hook_ops *nat_ops;
1160 int hooknum = ops->hooknum;
1163 if (pf >= ARRAY_SIZE(nat_net->nat_proto_net))
1166 nat_proto_net = &nat_net->nat_proto_net[pf];
1168 mutex_lock(&nf_nat_proto_mutex);
1169 if (WARN_ON(nat_proto_net->users == 0))
1172 nat_proto_net->users--;
1174 nat_ops = nat_proto_net->nat_hook_ops;
1175 for (i = 0; i < ops_count; i++) {
1176 if (nat_ops[i].hooknum == hooknum) {
1181 if (WARN_ON_ONCE(i == ops_count))
1183 priv = nat_ops[hooknum].priv;
1184 nf_hook_entries_delete_raw(&priv->entries, ops);
1186 if (nat_proto_net->users == 0) {
1187 nf_unregister_net_hooks(net, nat_ops, ops_count);
1189 for (i = 0; i < ops_count; i++) {
1190 priv = nat_ops[i].priv;
1191 kfree_rcu(priv, rcu_head);
1194 nat_proto_net->nat_hook_ops = NULL;
1198 mutex_unlock(&nf_nat_proto_mutex);
1201 static struct pernet_operations nat_net_ops = {
1203 .size = sizeof(struct nat_net),
1206 static const struct nf_nat_hook nat_hook = {
1207 .parse_nat_setup = nfnetlink_parse_nat_setup,
1209 .decode_session = __nf_nat_decode_session,
1211 .manip_pkt = nf_nat_manip_pkt,
1212 .remove_nat_bysrc = nf_nat_cleanup_conntrack,
1215 static int __init nf_nat_init(void)
1219 /* Leave them the same for the moment. */
1220 nf_nat_htable_size = nf_conntrack_htable_size;
1221 if (nf_nat_htable_size < CONNTRACK_LOCKS)
1222 nf_nat_htable_size = CONNTRACK_LOCKS;
1224 nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
1225 if (!nf_nat_bysource)
1228 for (i = 0; i < CONNTRACK_LOCKS; i++)
1229 spin_lock_init(&nf_nat_locks[i]);
1231 ret = register_pernet_subsys(&nat_net_ops);
1233 kvfree(nf_nat_bysource);
1237 nf_ct_helper_expectfn_register(&follow_master_nat);
1239 WARN_ON(nf_nat_hook != NULL);
1240 RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
1242 ret = register_nf_nat_bpf();
1244 RCU_INIT_POINTER(nf_nat_hook, NULL);
1245 nf_ct_helper_expectfn_unregister(&follow_master_nat);
1247 unregister_pernet_subsys(&nat_net_ops);
1248 kvfree(nf_nat_bysource);
1254 static void __exit nf_nat_cleanup(void)
1256 struct nf_nat_proto_clean clean = {};
1258 nf_ct_iterate_destroy(nf_nat_proto_clean, &clean);
1260 nf_ct_helper_expectfn_unregister(&follow_master_nat);
1261 RCU_INIT_POINTER(nf_nat_hook, NULL);
1264 kvfree(nf_nat_bysource);
1265 unregister_pernet_subsys(&nat_net_ops);
1268 MODULE_LICENSE("GPL");
1269 MODULE_DESCRIPTION("Network address translation core");
1271 module_init(nf_nat_init);
1272 module_exit(nf_nat_cleanup);