1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991001011021031041051061071081091101111121131141151161171181191201211221231241251261271281291301311321331341351361371381391401411421431441451461471481491501511521531541551561571581591601611621631641651661671681691701711721731741751761771781791801811821831841851861871881891901911921931941951961971981992002012022032042052062072082092102112122132142152162172182192202212222232242252262272282292302312322332342352362372382392402412422432442452462472482492502512522532542552562572582592602612622632642652662672682692702712722732742752762772782792802812822832842852862872882892902912922932942952962972982993003013023033043053063073083093103113123133143153163173183193203213223233243253263273283293303313323333343353363373383393403413423433443453463473483493503513523533543553563573583593603613623633643653663673683693703713723733743753763773783793803813823833843853863873883893903913923933943953963973983994004014024034044054064074084094104114124134144154164174184194204214224234244254264274284294304314324334344354364374384394404414424434444454464474484494504514524534544554564574584594604614624634644654664674684694704714724734744754764774784794804814824834844854864874884894904914924934944954964974984995005015025035045055065075085095105115125135145155165175185195205215225235245255265275285295305315325335345355365375385395405415425435445455465475485495505515525535545555565575585595605615625635645655665675685695705715725735745755765775785795805815825835845855865875885895905915925935945955965975985996006016026036046056066076086096106116126136146156166176186196206216226236246256266276286296306316326336346356366376386396406416426436446456466476486496506516526536546556566576586596606616626636646656666676686696706716726736746756766776786796806816826836846856866876886896906916926936946956966976986997007017027037047057067077087097107117127137147157167177187197207217227237247257267277287297307317327337347357367377387397407417427437447457467477487497507517527537547557567577587597607617627637647657667677687697707717727737747757767777787797807817827837847857867877887897907917927937947957967977987998008018028038048058068078088098108118128138148158168178188198208218228238248258268278288298308318328338348358368378388398408418428438448458468478488498508518528538548558568578588598608618628638648658668678688698708718728738748758768778788798808818828838848858868878888898908918928938948958968978988999009019029039049059069079089099109119129139149159169179189199209219229239249259269279289299309319329339349359369379389399409419429439449459469479489499509519529539549559569579589599609619629639649659669679689699709719729739749759769779789799809819829839849859869879889899909919929939949959969979989991000100110021003100410051006100710081009101010111012101310141015101610171018101910201021102210231024102510261027102810291030103110321033103410351036103710381039104010411042104310441045104610471048104910501051105210531054105510561057105810591060106110621063106410651066106710681069107010711072107310741075107610771078107910801081108210831084108510861087108810891090109110921093109410951096109710981099110011011102110311041105110611071108110911101111111211131114111511161117111811191120112111221123112411251126112711281129113011311132113311341135113611371138113911401141114211431144114511461147114811491150115111521153115411551156115711581159116011611162116311641165116611671168116911701171117211731174117511761177117811791180118111821183118411851186118711881189119011911192119311941195119611971198119912001201120212031204120512061207 |
- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * (C) 1999-2001 Paul `Rusty' Russell
- * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
- * (C) 2011 Patrick McHardy <kaber@trash.net>
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/module.h>
- #include <linux/types.h>
- #include <linux/timer.h>
- #include <linux/skbuff.h>
- #include <linux/gfp.h>
- #include <net/xfrm.h>
- #include <linux/jhash.h>
- #include <linux/rtnetlink.h>
- #include <net/netfilter/nf_conntrack.h>
- #include <net/netfilter/nf_conntrack_core.h>
- #include <net/netfilter/nf_conntrack_helper.h>
- #include <net/netfilter/nf_conntrack_seqadj.h>
- #include <net/netfilter/nf_conntrack_zones.h>
- #include <net/netfilter/nf_nat.h>
- #include <net/netfilter/nf_nat_helper.h>
- #include <uapi/linux/netfilter/nf_nat.h>
- #include "nf_internals.h"
- static spinlock_t nf_nat_locks[CONNTRACK_LOCKS];
- static DEFINE_MUTEX(nf_nat_proto_mutex);
- static unsigned int nat_net_id __read_mostly;
- static struct hlist_head *nf_nat_bysource __read_mostly;
- static unsigned int nf_nat_htable_size __read_mostly;
- static unsigned int nf_nat_hash_rnd __read_mostly;
- struct nf_nat_lookup_hook_priv {
- struct nf_hook_entries __rcu *entries;
- struct rcu_head rcu_head;
- };
- struct nf_nat_hooks_net {
- struct nf_hook_ops *nat_hook_ops;
- unsigned int users;
- };
- struct nat_net {
- struct nf_nat_hooks_net nat_proto_net[NFPROTO_NUMPROTO];
- };
- #ifdef CONFIG_XFRM
- static void nf_nat_ipv4_decode_session(struct sk_buff *skb,
- const struct nf_conn *ct,
- enum ip_conntrack_dir dir,
- unsigned long statusbit,
- struct flowi *fl)
- {
- const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
- struct flowi4 *fl4 = &fl->u.ip4;
- if (ct->status & statusbit) {
- fl4->daddr = t->dst.u3.ip;
- if (t->dst.protonum == IPPROTO_TCP ||
- t->dst.protonum == IPPROTO_UDP ||
- t->dst.protonum == IPPROTO_UDPLITE ||
- t->dst.protonum == IPPROTO_DCCP ||
- t->dst.protonum == IPPROTO_SCTP)
- fl4->fl4_dport = t->dst.u.all;
- }
- statusbit ^= IPS_NAT_MASK;
- if (ct->status & statusbit) {
- fl4->saddr = t->src.u3.ip;
- if (t->dst.protonum == IPPROTO_TCP ||
- t->dst.protonum == IPPROTO_UDP ||
- t->dst.protonum == IPPROTO_UDPLITE ||
- t->dst.protonum == IPPROTO_DCCP ||
- t->dst.protonum == IPPROTO_SCTP)
- fl4->fl4_sport = t->src.u.all;
- }
- }
- static void nf_nat_ipv6_decode_session(struct sk_buff *skb,
- const struct nf_conn *ct,
- enum ip_conntrack_dir dir,
- unsigned long statusbit,
- struct flowi *fl)
- {
- #if IS_ENABLED(CONFIG_IPV6)
- const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
- struct flowi6 *fl6 = &fl->u.ip6;
- if (ct->status & statusbit) {
- fl6->daddr = t->dst.u3.in6;
- if (t->dst.protonum == IPPROTO_TCP ||
- t->dst.protonum == IPPROTO_UDP ||
- t->dst.protonum == IPPROTO_UDPLITE ||
- t->dst.protonum == IPPROTO_DCCP ||
- t->dst.protonum == IPPROTO_SCTP)
- fl6->fl6_dport = t->dst.u.all;
- }
- statusbit ^= IPS_NAT_MASK;
- if (ct->status & statusbit) {
- fl6->saddr = t->src.u3.in6;
- if (t->dst.protonum == IPPROTO_TCP ||
- t->dst.protonum == IPPROTO_UDP ||
- t->dst.protonum == IPPROTO_UDPLITE ||
- t->dst.protonum == IPPROTO_DCCP ||
- t->dst.protonum == IPPROTO_SCTP)
- fl6->fl6_sport = t->src.u.all;
- }
- #endif
- }
- static void __nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl)
- {
- const struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
- enum ip_conntrack_dir dir;
- unsigned long statusbit;
- u8 family;
- ct = nf_ct_get(skb, &ctinfo);
- if (ct == NULL)
- return;
- family = nf_ct_l3num(ct);
- dir = CTINFO2DIR(ctinfo);
- if (dir == IP_CT_DIR_ORIGINAL)
- statusbit = IPS_DST_NAT;
- else
- statusbit = IPS_SRC_NAT;
- switch (family) {
- case NFPROTO_IPV4:
- nf_nat_ipv4_decode_session(skb, ct, dir, statusbit, fl);
- return;
- case NFPROTO_IPV6:
- nf_nat_ipv6_decode_session(skb, ct, dir, statusbit, fl);
- return;
- }
- }
- int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family)
- {
- struct flowi fl;
- unsigned int hh_len;
- struct dst_entry *dst;
- struct sock *sk = skb->sk;
- int err;
- err = xfrm_decode_session(skb, &fl, family);
- if (err < 0)
- return err;
- dst = skb_dst(skb);
- if (dst->xfrm)
- dst = ((struct xfrm_dst *)dst)->route;
- if (!dst_hold_safe(dst))
- return -EHOSTUNREACH;
- if (sk && !net_eq(net, sock_net(sk)))
- sk = NULL;
- dst = xfrm_lookup(net, dst, &fl, sk, 0);
- if (IS_ERR(dst))
- return PTR_ERR(dst);
- skb_dst_drop(skb);
- skb_dst_set(skb, dst);
- /* Change in oif may mean change in hh_len. */
- hh_len = skb_dst(skb)->dev->hard_header_len;
- if (skb_headroom(skb) < hh_len &&
- pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
- return -ENOMEM;
- return 0;
- }
- EXPORT_SYMBOL(nf_xfrm_me_harder);
- #endif /* CONFIG_XFRM */
- /* We keep an extra hash for each conntrack, for fast searching. */
- static unsigned int
- hash_by_src(const struct net *n, const struct nf_conntrack_tuple *tuple)
- {
- unsigned int hash;
- get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
- /* Original src, to ensure we map it consistently if poss. */
- hash = jhash2((u32 *)&tuple->src, sizeof(tuple->src) / sizeof(u32),
- tuple->dst.protonum ^ nf_nat_hash_rnd ^ net_hash_mix(n));
- return reciprocal_scale(hash, nf_nat_htable_size);
- }
- /* Is this tuple already taken? (not by us) */
- static int
- nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
- const struct nf_conn *ignored_conntrack)
- {
- /* Conntrack tracking doesn't keep track of outgoing tuples; only
- * incoming ones. NAT means they don't have a fixed mapping,
- * so we invert the tuple and look for the incoming reply.
- *
- * We could keep a separate hash if this proves too slow.
- */
- struct nf_conntrack_tuple reply;
- nf_ct_invert_tuple(&reply, tuple);
- return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
- }
- static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
- const struct nf_nat_range2 *range)
- {
- if (t->src.l3num == NFPROTO_IPV4)
- return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
- ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
- return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
- ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
- }
- /* Is the manipable part of the tuple between min and max incl? */
- static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
- enum nf_nat_manip_type maniptype,
- const union nf_conntrack_man_proto *min,
- const union nf_conntrack_man_proto *max)
- {
- __be16 port;
- switch (tuple->dst.protonum) {
- case IPPROTO_ICMP:
- case IPPROTO_ICMPV6:
- return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
- ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
- case IPPROTO_GRE: /* all fall though */
- case IPPROTO_TCP:
- case IPPROTO_UDP:
- case IPPROTO_UDPLITE:
- case IPPROTO_DCCP:
- case IPPROTO_SCTP:
- if (maniptype == NF_NAT_MANIP_SRC)
- port = tuple->src.u.all;
- else
- port = tuple->dst.u.all;
- return ntohs(port) >= ntohs(min->all) &&
- ntohs(port) <= ntohs(max->all);
- default:
- return true;
- }
- }
- /* If we source map this tuple so reply looks like reply_tuple, will
- * that meet the constraints of range.
- */
- static int in_range(const struct nf_conntrack_tuple *tuple,
- const struct nf_nat_range2 *range)
- {
- /* If we are supposed to map IPs, then we must be in the
- * range specified, otherwise let this drag us onto a new src IP.
- */
- if (range->flags & NF_NAT_RANGE_MAP_IPS &&
- !nf_nat_inet_in_range(tuple, range))
- return 0;
- if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
- return 1;
- return l4proto_in_range(tuple, NF_NAT_MANIP_SRC,
- &range->min_proto, &range->max_proto);
- }
- static inline int
- same_src(const struct nf_conn *ct,
- const struct nf_conntrack_tuple *tuple)
- {
- const struct nf_conntrack_tuple *t;
- t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
- return (t->dst.protonum == tuple->dst.protonum &&
- nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
- t->src.u.all == tuple->src.u.all);
- }
- /* Only called for SRC manip */
- static int
- find_appropriate_src(struct net *net,
- const struct nf_conntrack_zone *zone,
- const struct nf_conntrack_tuple *tuple,
- struct nf_conntrack_tuple *result,
- const struct nf_nat_range2 *range)
- {
- unsigned int h = hash_by_src(net, tuple);
- const struct nf_conn *ct;
- hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
- if (same_src(ct, tuple) &&
- net_eq(net, nf_ct_net(ct)) &&
- nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
- /* Copy source part from reply tuple. */
- nf_ct_invert_tuple(result,
- &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
- result->dst = tuple->dst;
- if (in_range(result, range))
- return 1;
- }
- }
- return 0;
- }
- /* For [FUTURE] fragmentation handling, we want the least-used
- * src-ip/dst-ip/proto triple. Fairness doesn't come into it. Thus
- * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
- * 1-65535, we don't do pro-rata allocation based on ports; we choose
- * the ip with the lowest src-ip/dst-ip/proto usage.
- */
- static void
- find_best_ips_proto(const struct nf_conntrack_zone *zone,
- struct nf_conntrack_tuple *tuple,
- const struct nf_nat_range2 *range,
- const struct nf_conn *ct,
- enum nf_nat_manip_type maniptype)
- {
- union nf_inet_addr *var_ipp;
- unsigned int i, max;
- /* Host order */
- u32 minip, maxip, j, dist;
- bool full_range;
- /* No IP mapping? Do nothing. */
- if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
- return;
- if (maniptype == NF_NAT_MANIP_SRC)
- var_ipp = &tuple->src.u3;
- else
- var_ipp = &tuple->dst.u3;
- /* Fast path: only one choice. */
- if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
- *var_ipp = range->min_addr;
- return;
- }
- if (nf_ct_l3num(ct) == NFPROTO_IPV4)
- max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
- else
- max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
- /* Hashing source and destination IPs gives a fairly even
- * spread in practice (if there are a small number of IPs
- * involved, there usually aren't that many connections
- * anyway). The consistency means that servers see the same
- * client coming from the same IP (some Internet Banking sites
- * like this), even across reboots.
- */
- j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
- range->flags & NF_NAT_RANGE_PERSISTENT ?
- 0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id);
- full_range = false;
- for (i = 0; i <= max; i++) {
- /* If first bytes of the address are at the maximum, use the
- * distance. Otherwise use the full range.
- */
- if (!full_range) {
- minip = ntohl((__force __be32)range->min_addr.all[i]);
- maxip = ntohl((__force __be32)range->max_addr.all[i]);
- dist = maxip - minip + 1;
- } else {
- minip = 0;
- dist = ~0;
- }
- var_ipp->all[i] = (__force __u32)
- htonl(minip + reciprocal_scale(j, dist));
- if (var_ipp->all[i] != range->max_addr.all[i])
- full_range = true;
- if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
- j ^= (__force u32)tuple->dst.u3.all[i];
- }
- }
- /* Alter the per-proto part of the tuple (depending on maniptype), to
- * give a unique tuple in the given range if possible.
- *
- * Per-protocol part of tuple is initialized to the incoming packet.
- */
- static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
- const struct nf_nat_range2 *range,
- enum nf_nat_manip_type maniptype,
- const struct nf_conn *ct)
- {
- unsigned int range_size, min, max, i, attempts;
- __be16 *keyptr;
- u16 off;
- static const unsigned int max_attempts = 128;
- switch (tuple->dst.protonum) {
- case IPPROTO_ICMP:
- case IPPROTO_ICMPV6:
- /* id is same for either direction... */
- keyptr = &tuple->src.u.icmp.id;
- if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
- min = 0;
- range_size = 65536;
- } else {
- min = ntohs(range->min_proto.icmp.id);
- range_size = ntohs(range->max_proto.icmp.id) -
- ntohs(range->min_proto.icmp.id) + 1;
- }
- goto find_free_id;
- #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
- case IPPROTO_GRE:
- /* If there is no master conntrack we are not PPTP,
- do not change tuples */
- if (!ct->master)
- return;
- if (maniptype == NF_NAT_MANIP_SRC)
- keyptr = &tuple->src.u.gre.key;
- else
- keyptr = &tuple->dst.u.gre.key;
- if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
- min = 1;
- range_size = 65535;
- } else {
- min = ntohs(range->min_proto.gre.key);
- range_size = ntohs(range->max_proto.gre.key) - min + 1;
- }
- goto find_free_id;
- #endif
- case IPPROTO_UDP:
- case IPPROTO_UDPLITE:
- case IPPROTO_TCP:
- case IPPROTO_SCTP:
- case IPPROTO_DCCP:
- if (maniptype == NF_NAT_MANIP_SRC)
- keyptr = &tuple->src.u.all;
- else
- keyptr = &tuple->dst.u.all;
- break;
- default:
- return;
- }
- /* If no range specified... */
- if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
- /* If it's dst rewrite, can't change port */
- if (maniptype == NF_NAT_MANIP_DST)
- return;
- if (ntohs(*keyptr) < 1024) {
- /* Loose convention: >> 512 is credential passing */
- if (ntohs(*keyptr) < 512) {
- min = 1;
- range_size = 511 - min + 1;
- } else {
- min = 600;
- range_size = 1023 - min + 1;
- }
- } else {
- min = 1024;
- range_size = 65535 - 1024 + 1;
- }
- } else {
- min = ntohs(range->min_proto.all);
- max = ntohs(range->max_proto.all);
- if (unlikely(max < min))
- swap(max, min);
- range_size = max - min + 1;
- }
- find_free_id:
- if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
- off = (ntohs(*keyptr) - ntohs(range->base_proto.all));
- else
- off = prandom_u32();
- attempts = range_size;
- if (attempts > max_attempts)
- attempts = max_attempts;
- /* We are in softirq; doing a search of the entire range risks
- * soft lockup when all tuples are already used.
- *
- * If we can't find any free port from first offset, pick a new
- * one and try again, with ever smaller search window.
- */
- another_round:
- for (i = 0; i < attempts; i++, off++) {
- *keyptr = htons(min + off % range_size);
- if (!nf_nat_used_tuple(tuple, ct))
- return;
- }
- if (attempts >= range_size || attempts < 16)
- return;
- attempts /= 2;
- off = prandom_u32();
- goto another_round;
- }
- /* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
- * we change the source to map into the range. For NF_INET_PRE_ROUTING
- * and NF_INET_LOCAL_OUT, we change the destination to map into the
- * range. It might not be possible to get a unique tuple, but we try.
- * At worst (or if we race), we will end up with a final duplicate in
- * __nf_conntrack_confirm and drop the packet. */
- static void
- get_unique_tuple(struct nf_conntrack_tuple *tuple,
- const struct nf_conntrack_tuple *orig_tuple,
- const struct nf_nat_range2 *range,
- struct nf_conn *ct,
- enum nf_nat_manip_type maniptype)
- {
- const struct nf_conntrack_zone *zone;
- struct net *net = nf_ct_net(ct);
- zone = nf_ct_zone(ct);
- /* 1) If this srcip/proto/src-proto-part is currently mapped,
- * and that same mapping gives a unique tuple within the given
- * range, use that.
- *
- * This is only required for source (ie. NAT/masq) mappings.
- * So far, we don't do local source mappings, so multiple
- * manips not an issue.
- */
- if (maniptype == NF_NAT_MANIP_SRC &&
- !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
- /* try the original tuple first */
- if (in_range(orig_tuple, range)) {
- if (!nf_nat_used_tuple(orig_tuple, ct)) {
- *tuple = *orig_tuple;
- return;
- }
- } else if (find_appropriate_src(net, zone,
- orig_tuple, tuple, range)) {
- pr_debug("get_unique_tuple: Found current src map\n");
- if (!nf_nat_used_tuple(tuple, ct))
- return;
- }
- }
- /* 2) Select the least-used IP/proto combination in the given range */
- *tuple = *orig_tuple;
- find_best_ips_proto(zone, tuple, range, ct, maniptype);
- /* 3) The per-protocol part of the manip is made to map into
- * the range to make a unique tuple.
- */
- /* Only bother mapping if it's not already in range and unique */
- if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
- if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
- if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
- l4proto_in_range(tuple, maniptype,
- &range->min_proto,
- &range->max_proto) &&
- (range->min_proto.all == range->max_proto.all ||
- !nf_nat_used_tuple(tuple, ct)))
- return;
- } else if (!nf_nat_used_tuple(tuple, ct)) {
- return;
- }
- }
- /* Last chance: get protocol to try to obtain unique tuple. */
- nf_nat_l4proto_unique_tuple(tuple, range, maniptype, ct);
- }
- struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct)
- {
- struct nf_conn_nat *nat = nfct_nat(ct);
- if (nat)
- return nat;
- if (!nf_ct_is_confirmed(ct))
- nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
- return nat;
- }
- EXPORT_SYMBOL_GPL(nf_ct_nat_ext_add);
- unsigned int
- nf_nat_setup_info(struct nf_conn *ct,
- const struct nf_nat_range2 *range,
- enum nf_nat_manip_type maniptype)
- {
- struct net *net = nf_ct_net(ct);
- struct nf_conntrack_tuple curr_tuple, new_tuple;
- /* Can't setup nat info for confirmed ct. */
- if (nf_ct_is_confirmed(ct))
- return NF_ACCEPT;
- WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
- maniptype != NF_NAT_MANIP_DST);
- if (WARN_ON(nf_nat_initialized(ct, maniptype)))
- return NF_DROP;
- /* What we've got will look like inverse of reply. Normally
- * this is what is in the conntrack, except for prior
- * manipulations (future optimization: if num_manips == 0,
- * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)
- */
- nf_ct_invert_tuple(&curr_tuple,
- &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
- get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
- if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
- struct nf_conntrack_tuple reply;
- /* Alter conntrack table so will recognize replies. */
- nf_ct_invert_tuple(&reply, &new_tuple);
- nf_conntrack_alter_reply(ct, &reply);
- /* Non-atomic: we own this at the moment. */
- if (maniptype == NF_NAT_MANIP_SRC)
- ct->status |= IPS_SRC_NAT;
- else
- ct->status |= IPS_DST_NAT;
- if (nfct_help(ct) && !nfct_seqadj(ct))
- if (!nfct_seqadj_ext_add(ct))
- return NF_DROP;
- }
- if (maniptype == NF_NAT_MANIP_SRC) {
- unsigned int srchash;
- spinlock_t *lock;
- srchash = hash_by_src(net,
- &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
- lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS];
- spin_lock_bh(lock);
- hlist_add_head_rcu(&ct->nat_bysource,
- &nf_nat_bysource[srchash]);
- spin_unlock_bh(lock);
- }
- /* It's done. */
- if (maniptype == NF_NAT_MANIP_DST)
- ct->status |= IPS_DST_NAT_DONE;
- else
- ct->status |= IPS_SRC_NAT_DONE;
- return NF_ACCEPT;
- }
- EXPORT_SYMBOL(nf_nat_setup_info);
- static unsigned int
- __nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip)
- {
- /* Force range to this IP; let proto decide mapping for
- * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
- * Use reply in case it's already been mangled (eg local packet).
- */
- union nf_inet_addr ip =
- (manip == NF_NAT_MANIP_SRC ?
- ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 :
- ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3);
- struct nf_nat_range2 range = {
- .flags = NF_NAT_RANGE_MAP_IPS,
- .min_addr = ip,
- .max_addr = ip,
- };
- return nf_nat_setup_info(ct, &range, manip);
- }
- unsigned int
- nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
- {
- return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum));
- }
- EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding);
- /* Do packet manipulations according to nf_nat_setup_info. */
- unsigned int nf_nat_packet(struct nf_conn *ct,
- enum ip_conntrack_info ctinfo,
- unsigned int hooknum,
- struct sk_buff *skb)
- {
- enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
- enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
- unsigned int verdict = NF_ACCEPT;
- unsigned long statusbit;
- if (mtype == NF_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;
- /* Non-atomic: these bits don't change. */
- if (ct->status & statusbit)
- verdict = nf_nat_manip_pkt(skb, ct, mtype, dir);
- return verdict;
- }
- EXPORT_SYMBOL_GPL(nf_nat_packet);
- unsigned int
- nf_nat_inet_fn(void *priv, struct sk_buff *skb,
- const struct nf_hook_state *state)
- {
- struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
- struct nf_conn_nat *nat;
- /* maniptype == SRC for postrouting. */
- enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
- ct = nf_ct_get(skb, &ctinfo);
- /* Can't track? It's not due to stress, or conntrack would
- * have dropped it. Hence it's the user's responsibilty to
- * packet filter it out, or implement conntrack/NAT for that
- * protocol. 8) --RR
- */
- if (!ct)
- return NF_ACCEPT;
- nat = nfct_nat(ct);
- switch (ctinfo) {
- case IP_CT_RELATED:
- case IP_CT_RELATED_REPLY:
- /* Only ICMPs can be IP_CT_IS_REPLY. Fallthrough */
- case IP_CT_NEW:
- /* Seen it before? This can happen for loopback, retrans,
- * or local packets.
- */
- if (!nf_nat_initialized(ct, maniptype)) {
- struct nf_nat_lookup_hook_priv *lpriv = priv;
- struct nf_hook_entries *e = rcu_dereference(lpriv->entries);
- unsigned int ret;
- int i;
- if (!e)
- goto null_bind;
- for (i = 0; i < e->num_hook_entries; i++) {
- ret = e->hooks[i].hook(e->hooks[i].priv, skb,
- state);
- if (ret != NF_ACCEPT)
- return ret;
- if (nf_nat_initialized(ct, maniptype))
- goto do_nat;
- }
- null_bind:
- ret = nf_nat_alloc_null_binding(ct, state->hook);
- if (ret != NF_ACCEPT)
- return ret;
- } else {
- pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n",
- maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
- ct, ct->status);
- if (nf_nat_oif_changed(state->hook, ctinfo, nat,
- state->out))
- goto oif_changed;
- }
- break;
- default:
- /* ESTABLISHED */
- WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
- ctinfo != IP_CT_ESTABLISHED_REPLY);
- if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
- goto oif_changed;
- }
- do_nat:
- return nf_nat_packet(ct, ctinfo, state->hook, skb);
- oif_changed:
- nf_ct_kill_acct(ct, ctinfo, skb);
- return NF_DROP;
- }
- EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
- struct nf_nat_proto_clean {
- u8 l3proto;
- u8 l4proto;
- };
- /* kill conntracks with affected NAT section */
- static int nf_nat_proto_remove(struct nf_conn *i, void *data)
- {
- const struct nf_nat_proto_clean *clean = data;
- if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
- (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
- return 0;
- return i->status & IPS_NAT_MASK ? 1 : 0;
- }
- static void __nf_nat_cleanup_conntrack(struct nf_conn *ct)
- {
- unsigned int h;
- h = hash_by_src(nf_ct_net(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
- spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
- hlist_del_rcu(&ct->nat_bysource);
- spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
- }
- static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
- {
- if (nf_nat_proto_remove(ct, data))
- return 1;
- /* This module is being removed and conntrack has nat null binding.
- * Remove it from bysource hash, as the table will be freed soon.
- *
- * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack()
- * will delete entry from already-freed table.
- */
- if (test_and_clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status))
- __nf_nat_cleanup_conntrack(ct);
- /* don't delete conntrack. Although that would make things a lot
- * simpler, we'd end up flushing all conntracks on nat rmmod.
- */
- return 0;
- }
- /* No one using conntrack by the time this called. */
- static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
- {
- if (ct->status & IPS_SRC_NAT_DONE)
- __nf_nat_cleanup_conntrack(ct);
- }
- static struct nf_ct_ext_type nat_extend __read_mostly = {
- .len = sizeof(struct nf_conn_nat),
- .align = __alignof__(struct nf_conn_nat),
- .destroy = nf_nat_cleanup_conntrack,
- .id = NF_CT_EXT_NAT,
- };
- #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
- #include <linux/netfilter/nfnetlink.h>
- #include <linux/netfilter/nfnetlink_conntrack.h>
- static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
- [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
- [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
- };
- static int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
- struct nf_nat_range2 *range)
- {
- if (tb[CTA_PROTONAT_PORT_MIN]) {
- range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
- range->max_proto.all = range->min_proto.all;
- range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
- }
- if (tb[CTA_PROTONAT_PORT_MAX]) {
- range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
- range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
- }
- return 0;
- }
- static int nfnetlink_parse_nat_proto(struct nlattr *attr,
- const struct nf_conn *ct,
- struct nf_nat_range2 *range)
- {
- struct nlattr *tb[CTA_PROTONAT_MAX+1];
- int err;
- err = nla_parse_nested_deprecated(tb, CTA_PROTONAT_MAX, attr,
- protonat_nla_policy, NULL);
- if (err < 0)
- return err;
- return nf_nat_l4proto_nlattr_to_range(tb, range);
- }
- static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
- [CTA_NAT_V4_MINIP] = { .type = NLA_U32 },
- [CTA_NAT_V4_MAXIP] = { .type = NLA_U32 },
- [CTA_NAT_V6_MINIP] = { .len = sizeof(struct in6_addr) },
- [CTA_NAT_V6_MAXIP] = { .len = sizeof(struct in6_addr) },
- [CTA_NAT_PROTO] = { .type = NLA_NESTED },
- };
- static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[],
- struct nf_nat_range2 *range)
- {
- if (tb[CTA_NAT_V4_MINIP]) {
- range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
- range->flags |= NF_NAT_RANGE_MAP_IPS;
- }
- if (tb[CTA_NAT_V4_MAXIP])
- range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
- else
- range->max_addr.ip = range->min_addr.ip;
- return 0;
- }
- static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
- struct nf_nat_range2 *range)
- {
- if (tb[CTA_NAT_V6_MINIP]) {
- nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
- sizeof(struct in6_addr));
- range->flags |= NF_NAT_RANGE_MAP_IPS;
- }
- if (tb[CTA_NAT_V6_MAXIP])
- nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
- sizeof(struct in6_addr));
- else
- range->max_addr = range->min_addr;
- return 0;
- }
- static int
- nfnetlink_parse_nat(const struct nlattr *nat,
- const struct nf_conn *ct, struct nf_nat_range2 *range)
- {
- struct nlattr *tb[CTA_NAT_MAX+1];
- int err;
- memset(range, 0, sizeof(*range));
- err = nla_parse_nested_deprecated(tb, CTA_NAT_MAX, nat,
- nat_nla_policy, NULL);
- if (err < 0)
- return err;
- switch (nf_ct_l3num(ct)) {
- case NFPROTO_IPV4:
- err = nf_nat_ipv4_nlattr_to_range(tb, range);
- break;
- case NFPROTO_IPV6:
- err = nf_nat_ipv6_nlattr_to_range(tb, range);
- break;
- default:
- err = -EPROTONOSUPPORT;
- break;
- }
- if (err)
- return err;
- if (!tb[CTA_NAT_PROTO])
- return 0;
- return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
- }
- /* This function is called under rcu_read_lock() */
- static int
- nfnetlink_parse_nat_setup(struct nf_conn *ct,
- enum nf_nat_manip_type manip,
- const struct nlattr *attr)
- {
- struct nf_nat_range2 range;
- int err;
- /* Should not happen, restricted to creating new conntracks
- * via ctnetlink.
- */
- if (WARN_ON_ONCE(nf_nat_initialized(ct, manip)))
- return -EEXIST;
- /* No NAT information has been passed, allocate the null-binding */
- if (attr == NULL)
- return __nf_nat_alloc_null_binding(ct, manip) == NF_DROP ? -ENOMEM : 0;
- err = nfnetlink_parse_nat(attr, ct, &range);
- if (err < 0)
- return err;
- return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
- }
- #else
- static int
- nfnetlink_parse_nat_setup(struct nf_conn *ct,
- enum nf_nat_manip_type manip,
- const struct nlattr *attr)
- {
- return -EOPNOTSUPP;
- }
- #endif
- static struct nf_ct_helper_expectfn follow_master_nat = {
- .name = "nat-follow-master",
- .expectfn = nf_nat_follow_master,
- };
- int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
- const struct nf_hook_ops *orig_nat_ops, unsigned int ops_count)
- {
- struct nat_net *nat_net = net_generic(net, nat_net_id);
- struct nf_nat_hooks_net *nat_proto_net;
- struct nf_nat_lookup_hook_priv *priv;
- unsigned int hooknum = ops->hooknum;
- struct nf_hook_ops *nat_ops;
- int i, ret;
- if (WARN_ON_ONCE(pf >= ARRAY_SIZE(nat_net->nat_proto_net)))
- return -EINVAL;
- nat_proto_net = &nat_net->nat_proto_net[pf];
- for (i = 0; i < ops_count; i++) {
- if (orig_nat_ops[i].hooknum == hooknum) {
- hooknum = i;
- break;
- }
- }
- if (WARN_ON_ONCE(i == ops_count))
- return -EINVAL;
- mutex_lock(&nf_nat_proto_mutex);
- if (!nat_proto_net->nat_hook_ops) {
- WARN_ON(nat_proto_net->users != 0);
- nat_ops = kmemdup(orig_nat_ops, sizeof(*orig_nat_ops) * ops_count, GFP_KERNEL);
- if (!nat_ops) {
- mutex_unlock(&nf_nat_proto_mutex);
- return -ENOMEM;
- }
- for (i = 0; i < ops_count; i++) {
- priv = kzalloc(sizeof(*priv), GFP_KERNEL);
- if (priv) {
- nat_ops[i].priv = priv;
- continue;
- }
- mutex_unlock(&nf_nat_proto_mutex);
- while (i)
- kfree(nat_ops[--i].priv);
- kfree(nat_ops);
- return -ENOMEM;
- }
- ret = nf_register_net_hooks(net, nat_ops, ops_count);
- if (ret < 0) {
- mutex_unlock(&nf_nat_proto_mutex);
- for (i = 0; i < ops_count; i++)
- kfree(nat_ops[i].priv);
- kfree(nat_ops);
- return ret;
- }
- nat_proto_net->nat_hook_ops = nat_ops;
- }
- nat_ops = nat_proto_net->nat_hook_ops;
- priv = nat_ops[hooknum].priv;
- if (WARN_ON_ONCE(!priv)) {
- mutex_unlock(&nf_nat_proto_mutex);
- return -EOPNOTSUPP;
- }
- ret = nf_hook_entries_insert_raw(&priv->entries, ops);
- if (ret == 0)
- nat_proto_net->users++;
- mutex_unlock(&nf_nat_proto_mutex);
- return ret;
- }
- void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
- unsigned int ops_count)
- {
- struct nat_net *nat_net = net_generic(net, nat_net_id);
- struct nf_nat_hooks_net *nat_proto_net;
- struct nf_nat_lookup_hook_priv *priv;
- struct nf_hook_ops *nat_ops;
- int hooknum = ops->hooknum;
- int i;
- if (pf >= ARRAY_SIZE(nat_net->nat_proto_net))
- return;
- nat_proto_net = &nat_net->nat_proto_net[pf];
- mutex_lock(&nf_nat_proto_mutex);
- if (WARN_ON(nat_proto_net->users == 0))
- goto unlock;
- nat_proto_net->users--;
- nat_ops = nat_proto_net->nat_hook_ops;
- for (i = 0; i < ops_count; i++) {
- if (nat_ops[i].hooknum == hooknum) {
- hooknum = i;
- break;
- }
- }
- if (WARN_ON_ONCE(i == ops_count))
- goto unlock;
- priv = nat_ops[hooknum].priv;
- nf_hook_entries_delete_raw(&priv->entries, ops);
- if (nat_proto_net->users == 0) {
- nf_unregister_net_hooks(net, nat_ops, ops_count);
- for (i = 0; i < ops_count; i++) {
- priv = nat_ops[i].priv;
- kfree_rcu(priv, rcu_head);
- }
- nat_proto_net->nat_hook_ops = NULL;
- kfree(nat_ops);
- }
- unlock:
- mutex_unlock(&nf_nat_proto_mutex);
- }
- static struct pernet_operations nat_net_ops = {
- .id = &nat_net_id,
- .size = sizeof(struct nat_net),
- };
- static struct nf_nat_hook nat_hook = {
- .parse_nat_setup = nfnetlink_parse_nat_setup,
- #ifdef CONFIG_XFRM
- .decode_session = __nf_nat_decode_session,
- #endif
- .manip_pkt = nf_nat_manip_pkt,
- };
- static int __init nf_nat_init(void)
- {
- int ret, i;
- /* Leave them the same for the moment. */
- nf_nat_htable_size = nf_conntrack_htable_size;
- if (nf_nat_htable_size < CONNTRACK_LOCKS)
- nf_nat_htable_size = CONNTRACK_LOCKS;
- nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
- if (!nf_nat_bysource)
- return -ENOMEM;
- ret = nf_ct_extend_register(&nat_extend);
- if (ret < 0) {
- kvfree(nf_nat_bysource);
- pr_err("Unable to register extension\n");
- return ret;
- }
- for (i = 0; i < CONNTRACK_LOCKS; i++)
- spin_lock_init(&nf_nat_locks[i]);
- ret = register_pernet_subsys(&nat_net_ops);
- if (ret < 0) {
- nf_ct_extend_unregister(&nat_extend);
- kvfree(nf_nat_bysource);
- return ret;
- }
- nf_ct_helper_expectfn_register(&follow_master_nat);
- WARN_ON(nf_nat_hook != NULL);
- RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
- return 0;
- }
- static void __exit nf_nat_cleanup(void)
- {
- struct nf_nat_proto_clean clean = {};
- nf_ct_iterate_destroy(nf_nat_proto_clean, &clean);
- nf_ct_extend_unregister(&nat_extend);
- nf_ct_helper_expectfn_unregister(&follow_master_nat);
- RCU_INIT_POINTER(nf_nat_hook, NULL);
- synchronize_net();
- kvfree(nf_nat_bysource);
- unregister_pernet_subsys(&nat_net_ops);
- }
- MODULE_LICENSE("GPL");
- module_init(nf_nat_init);
- module_exit(nf_nat_cleanup);
|