// SPDX-License-Identifier: GPL-2.0-only /* * (C) 1999-2001 Paul `Rusty' Russell * (C) 2002-2006 Netfilter Core Team * (C) 2011 Patrick McHardy */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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 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); } /* 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, 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 (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, 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; } /* 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 #include 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);