diff options
Diffstat (limited to 'net/netfilter/nf_nat_core.c')
| -rw-r--r-- | net/netfilter/nf_nat_core.c | 1184 |
1 files changed, 1184 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c new file mode 100644 index 000000000..e29e4ccb5 --- /dev/null +++ b/net/netfilter/nf_nat_core.c @@ -0,0 +1,1184 @@ +// 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/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" + +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 = get_random_u16(); + + 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 = 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 (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; +} + +#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 const 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, + .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_init(nf_nat_init); +module_exit(nf_nat_cleanup); |