// SPDX-License-Identifier: GPL-2.0-only
/*
* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <[email protected]>
* (C) 2011 Patrick McHardy <[email protected]>
*/
#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/siphash.h>
#include <linux/rtnetlink.h>
#include <net/netfilter/nf_conntrack_bpf.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"
#define NF_NAT_MAX_ATTEMPTS 128
#define NF_NAT_HARDER_THRESH (NF_NAT_MAX_ATTEMPTS / 4)
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 siphash_aligned_key_t nf_nat_hash_rnd;
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;
}
}
#endif /* CONFIG_XFRM */
/* We keep an extra hash for each conntrack, for fast searching. */
static unsigned int
hash_by_src(const struct net *net,
const struct nf_conntrack_zone *zone,
const struct nf_conntrack_tuple *tuple)
{
unsigned int hash;
struct {
struct nf_conntrack_man src;
u32 net_mix;
u32 protonum;
u32 zone;
} __aligned(SIPHASH_ALIGNMENT) combined;
get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
memset(&combined, 0, sizeof(combined));
/* Original src, to ensure we map it consistently if poss. */
combined.src = tuple->src;
combined.net_mix = net_hash_mix(net);
combined.protonum = tuple->dst.protonum;
/* Zone ID can be used provided its valid for both directions */
if (zone->dir == NF_CT_DEFAULT_ZONE_DIR)
combined.zone = zone->id;
hash = siphash(&combined, sizeof(combined), &nf_nat_hash_rnd);
return reciprocal_scale(hash, nf_nat_htable_size);
}
/**
* nf_nat_used_tuple - check if proposed nat tuple clashes with existing entry
* @tuple: proposed NAT binding
* @ignored_conntrack: our (unconfirmed) conntrack entry
*
* A conntrack entry can be inserted to the connection tracking table
* if there is no existing entry with an identical tuple in either direction.
*
* Example:
* INITIATOR -> NAT/PAT -> RESPONDER
*
* INITIATOR passes through NAT/PAT ("us") and SNAT is done (saddr rewrite).
* Then, later, NAT/PAT itself also connects to RESPONDER.
*
* This will not work if the SNAT done earlier has same IP:PORT source pair.
*
* Conntrack table has:
* ORIGINAL: $IP_INITIATOR:$SPORT -> $IP_RESPONDER:$DPORT
* REPLY: $IP_RESPONDER:$DPORT -> $IP_NAT:$SPORT
*
* and new locally originating connection wants:
* ORIGINAL: $IP_NAT:$SPORT -> $IP_RESPONDER:$DPORT
* REPLY: $IP_RESPONDER:$DPORT -> $IP_NAT:$SPORT
*
* ... which would mean incoming packets cannot be distinguished between
* the existing and the newly added entry (identical IP_CT_DIR_REPLY tuple).
*
* @return: true if the proposed NAT mapping collides with an existing entry.
*/
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_allow_clash(const struct nf_conn *ct)
{
return nf_ct_l4proto_find(nf_ct_protonum(ct))->allow_clash;
}
/**
* nf_nat_used_tuple_new - check if to-be-inserted conntrack collides with existing entry
* @tuple: proposed NAT binding
* @ignored_ct: our (unconfirmed) conntrack entry
*
* Same as nf_nat_used_tuple, but also check for rare clash in reverse
* direction. Should be called only when @tuple has not been altered, i.e.
* @ignored_conntrack will not be subject to NAT.
*
* @return: true if the proposed NAT mapping collides with existing entry.
*/
static noinline bool
nf_nat_used_tuple_new(const struct nf_conntrack_tuple *tuple,
const struct nf_conn *ignored_ct)
{
static const unsigned long uses_nat = IPS_NAT_MASK | IPS_SEQ_ADJUST_BIT;
const struct nf_conntrack_tuple_hash *thash;
const struct nf_conntrack_zone *zone;
struct nf_conn *ct;
bool taken = true;
struct net *net;
if (!nf_nat_used_tuple(tuple, ignored_ct))
return false;
if (!nf_nat_allow_clash(ignored_ct))
return true;
/* Initial choice clashes with existing conntrack.
* Check for (rare) reverse collision.
*
* This can happen when new packets are received in both directions
* at the exact same time on different CPUs.
*
* Without SMP, first packet creates new conntrack entry and second
* packet is resolved as established reply packet.
*
* With parallel processing, both packets could be picked up as
* new and both get their own ct entry allocated.
*
* If ignored_conntrack and colliding ct are not subject to NAT then
* pretend the tuple is available and let later clash resolution
* handle this at insertion time.
*
* Without it, the 'reply' packet has its source port rewritten
* by nat engine.
*/
if (READ_ONCE(ignored_ct->status) & uses_nat)
return true;
net = nf_ct_net(ignored_ct);
zone = nf_ct_zone(ignored_ct);
thash = nf_conntrack_find_get(net, zone, tuple);
if (unlikely(!thash)) /* clashing entry went away */
return false;
ct = nf_ct_tuplehash_to_ctrack(thash);
/* NB: IP_CT_DIR_ORIGINAL should be impossible because
* nf_nat_used_tuple() handles origin collisions.
*
* Handle remote chance other CPU confirmed its ct right after.
*/
if (thash->tuple.dst.dir != IP_CT_DIR_REPLY)
goto out;
/* clashing connection subject to NAT? Retry with new tuple. */
if (READ_ONCE(ct->status) & uses_nat)
goto out;
if (nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
&ignored_ct->tuplehash[IP_CT_DIR_REPLY].tuple) &&
nf_ct_tuple_equal(&ct->tuplehash[IP_CT_DIR_REPLY].tuple,
&ignored_ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)) {
taken = false;
goto out;
}
out:
nf_ct_put(ct);
return taken;
}
static bool nf_nat_may_kill(struct nf_conn *ct, unsigned long flags)
{
static const unsigned long flags_refuse = IPS_FIXED_TIMEOUT |
IPS_DYING;
static const unsigned long flags_needed = IPS_SRC_NAT;
enum tcp_conntrack old_state;
old_state = READ_ONCE(ct->proto.tcp.state);
if (old_state < TCP_CONNTRACK_TIME_WAIT)
return false;
if (flags & flags_refuse)
return false;
return (flags & flags_needed) == flags_needed;
}
/* reverse direction will send packets to new source, so
* make sure such packets are invalid.
*/
static bool nf_seq_has_advanced(const struct nf_conn *old, const struct nf_conn *new)
{
return (__s32)(new->proto.tcp.seen[0].td_end -
old->proto.tcp.seen[0].td_end) > 0;
}
static int
nf_nat_used_tuple_harder(const struct nf_conntrack_tuple *tuple,
const struct nf_conn *ignored_conntrack,
unsigned int attempts_left)
{
static const unsigned long flags_offload = IPS_OFFLOAD | IPS_HW_OFFLOAD;
struct nf_conntrack_tuple_hash *thash;
const struct nf_conntrack_zone *zone;
struct nf_conntrack_tuple reply;
unsigned long flags;
struct nf_conn *ct;
bool taken = true;
struct net *net;
nf_ct_invert_tuple(&reply, tuple);
if (attempts_left > NF_NAT_HARDER_THRESH ||
tuple->dst.protonum != IPPROTO_TCP ||
ignored_conntrack->proto.tcp.state != TCP_CONNTRACK_SYN_SENT)
return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
/* :ast few attempts to find a free tcp port. Destructive
* action: evict colliding if its in timewait state and the
* tcp sequence number has advanced past the one used by the
* old entry.
*/
net = nf_ct_net(ignored_conntrack);
zone = nf_ct_zone(ignored_conntrack);
thash = nf_conntrack_find_get(net, zone, &reply);
if (!thash)
return false;
ct = nf_ct_tuplehash_to_ctrack(thash);
if (thash->tuple.dst.dir == IP_CT_DIR_ORIGINAL)
goto out;
if (WARN_ON_ONCE(ct == ignored_conntrack))
goto out;
flags = READ_ONCE(ct->status);
if (!nf_nat_may_kill(ct, flags))
goto out;
if (!nf_seq_has_advanced(ct, ignored_conntrack))
goto out;
/* Even if we can evict do not reuse if entry is offloaded. */
if (nf_ct_kill(ct))
taken = flags & flags_offload;
out:
nf_ct_put(ct);
return taken;
}
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 nf_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, zone, 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 (nf_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;
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 if ((range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL) ||
maniptype != NF_NAT_MANIP_DST)
off = get_random_u16();
else
off = 0;
attempts = range_size;
if (attempts > NF_NAT_MAX_ATTEMPTS)
attempts = NF_NAT_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_harder(tuple, ct, attempts - i))
return;
}
if (attempts >= range_size || attempts < 16)
return;
attempts /= 2;
off = get_random_u16();
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 (nf_in_range(orig_tuple, range)) {
if (!nf_nat_used_tuple_new(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, nf_ct_zone(ct),
&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);
static bool in_vrf_postrouting(const struct nf_hook_state *state)
{
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
if (state->hook == NF_INET_POST_ROUTING &&
netif_is_l3_master(state->out))
return true;
#endif
return false;
}
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 || in_vrf_postrouting(state))
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), nf_ct_zone(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;
}
#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_array(orig_nat_ops, ops_count, sizeof(*orig_nat_ops), 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 const struct nf_nat_hook nat_hook = {
.parse_nat_setup = nfnetlink_parse_nat_setup,
#ifdef CONFIG_XFRM
.decode_session = __nf_nat_decode_session,
#endif
.remove_nat_bysrc = nf_nat_cleanup_conntrack,
};
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;
for (i = 0; i < CONNTRACK_LOCKS; i++)
spin_lock_init(&nf_nat_locks[i]);
ret = register_pernet_subsys(&nat_net_ops);
if (ret < 0) {
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);
ret = register_nf_nat_bpf();
if (ret < 0) {
RCU_INIT_POINTER(nf_nat_hook, NULL);
nf_ct_helper_expectfn_unregister(&follow_master_nat);
synchronize_net();
unregister_pernet_subsys(&nat_net_ops);
kvfree(nf_nat_bysource);
}
return ret;
}
static void __exit nf_nat_cleanup(void)
{
struct nf_nat_proto_clean clean = {};
nf_ct_iterate_destroy(nf_nat_proto_clean, &clean);
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_DESCRIPTION("Network address translation core");
module_init(nf_nat_init);
module_exit(nf_nat_cleanup);
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