unsigned int
nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum,
const struct nf_nat_range2 *range,
const struct net_device *out)
{
struct nf_conn *ct;
struct nf_conn_nat *nat;
enum ip_conntrack_info ctinfo;
struct nf_nat_range2 newrange;
const struct rtable *rt;
__be32 newsrc, nh;
WARN_ON(hooknum != NF_INET_POST_ROUTING);
ct = nf_ct_get(skb, &ctinfo);
WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
ctinfo == IP_CT_RELATED_REPLY)));
/* Source address is 0.0.0.0 - locally generated packet that is
* probably not supposed to be masqueraded.
*/
if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
return NF_ACCEPT;
rt = skb_rtable(skb);
nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE);
if (!newsrc) {
pr_info("%s ate my IP address\n", out->name);
return NF_DROP;
}
nat = nf_ct_nat_ext_add(ct);
if (nat)
nat->masq_index = out->ifindex;
/* Transfer from original range. */
memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
newrange.min_addr.ip = newsrc;
newrange.max_addr.ip = newsrc;
newrange.min_proto = range->min_proto;
newrange.max_proto = range->max_proto;
/* Hand modified range to generic setup. */
return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
}
unsigned int
nf_nat_setup_info(struct nf_conn *ct,
const struct nf_nat_range *range,
enum nf_nat_manip_type maniptype)
{
struct nf_conntrack_tuple curr_tuple, new_tuple;
struct nf_conn_nat *nat;
/* nat helper or nfctnetlink also setup binding */
nat = nf_ct_nat_ext_add(ct);
if (nat == NULL)
return NF_ACCEPT;
NF_CT_ASSERT(maniptype == NF_NAT_MANIP_SRC ||
maniptype == NF_NAT_MANIP_DST);
BUG_ON(nf_nat_initialized(ct, maniptype));
/* 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_tuplepr(&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_tuplepr(&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))
if (!nfct_seqadj_ext_add(ct))
return NF_DROP;
}
if (maniptype == NF_NAT_MANIP_SRC) {
int err;
err = rhashtable_insert_fast(&nf_nat_bysource_table,
&ct->nat_bysource,
nf_nat_bysource_params);
if (err)
return NF_DROP;
}
/* 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;
}
unsigned int
nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state,
unsigned int (*do_chain)(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state,
struct nf_conn *ct))
{
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);
/* We never see fragments: conntrack defrags on pre-routing
* and local-out, and nf_nat_out protects post-routing.
*/
NF_CT_ASSERT(!ip_is_fragment(ip_hdr(skb)));
ct = nf_ct_get(skb, &ctinfo);
/* Can't track? It's not due to stress, or conntrack would
* have dropped it. Hence it's the user's responsibilty to
* packet filter it out, or implement conntrack/NAT for that
* protocol. 8) --RR
*/
if (!ct)
return NF_ACCEPT;
/* Don't try to NAT if this packet is not conntracked */
if (nf_ct_is_untracked(ct))
return NF_ACCEPT;
nat = nf_ct_nat_ext_add(ct);
if (nat == NULL)
return NF_ACCEPT;
switch (ctinfo) {
case IP_CT_RELATED:
case IP_CT_RELATED_REPLY:
if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
state->hook))
return NF_DROP;
else
return NF_ACCEPT;
}
/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
case IP_CT_NEW:
/* Seen it before? This can happen for loopback, retrans,
* or local packets.
*/
if (!nf_nat_initialized(ct, maniptype)) {
unsigned int ret;
ret = do_chain(priv, skb, state, ct);
if (ret != NF_ACCEPT)
return ret;
if (nf_nat_initialized(ct, HOOK2MANIP(state->hook)))
break;
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\n",
maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
ct);
if (nf_nat_oif_changed(state->hook, ctinfo, nat,
state->out))
goto oif_changed;
}
break;
default:
/* ESTABLISHED */
NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
ctinfo == IP_CT_ESTABLISHED_REPLY);
if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
goto oif_changed;
}
return nf_nat_packet(ct, ctinfo, state->hook, skb);
oif_changed:
nf_ct_kill_acct(ct, ctinfo, skb);
return NF_DROP;
}
unsigned int
nf_nat_ipv6_fn(const struct nf_hook_ops *ops, struct sk_buff *skb,
const struct net_device *in, const struct net_device *out,
unsigned int (*do_chain)(const struct nf_hook_ops *ops,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
struct nf_conn *ct))
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
struct nf_conn_nat *nat;
enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum);
__be16 frag_off;
int hdrlen;
u8 nexthdr;
ct = nf_ct_get(skb, &ctinfo);
/* Can't track? It's not due to stress, or conntrack would
* have dropped it. Hence it's the user's responsibilty to
* packet filter it out, or implement conntrack/NAT for that
* protocol. 8) --RR
*/
if (!ct)
return NF_ACCEPT;
/* Don't try to NAT if this packet is not conntracked */
if (nf_ct_is_untracked(ct))
return NF_ACCEPT;
nat = nf_ct_nat_ext_add(ct);
if (nat == NULL)
return NF_ACCEPT;
switch (ctinfo) {
case IP_CT_RELATED:
case IP_CT_RELATED_REPLY:
nexthdr = ipv6_hdr(skb)->nexthdr;
hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
&nexthdr, &frag_off);
if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
ops->hooknum,
hdrlen))
return NF_DROP;
else
return NF_ACCEPT;
}
/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
case IP_CT_NEW:
/* Seen it before? This can happen for loopback, retrans,
* or local packets.
*/
if (!nf_nat_initialized(ct, maniptype)) {
unsigned int ret;
ret = do_chain(ops, skb, in, out, ct);
if (ret != NF_ACCEPT)
return ret;
if (nf_nat_initialized(ct, HOOK2MANIP(ops->hooknum)))
break;
ret = nf_nat_alloc_null_binding(ct, ops->hooknum);
if (ret != NF_ACCEPT)
return ret;
} else {
pr_debug("Already setup manip %s for ct %p\n",
maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
ct);
if (nf_nat_oif_changed(ops->hooknum, ctinfo, nat, out))
goto oif_changed;
}
break;
default:
/* ESTABLISHED */
NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
ctinfo == IP_CT_ESTABLISHED_REPLY);
if (nf_nat_oif_changed(ops->hooknum, ctinfo, nat, out))
goto oif_changed;
}
return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
oif_changed:
nf_ct_kill_acct(ct, ctinfo, skb);
return NF_DROP;
}
static void pptp_nat_expected(struct nf_conn *ct,
struct nf_conntrack_expect *exp)
{
struct net *net = nf_ct_net(ct);
const struct nf_conn *master = ct->master;
struct nf_conntrack_expect *other_exp;
struct nf_conntrack_tuple t = {};
const struct nf_ct_pptp_master *ct_pptp_info;
const struct nf_nat_pptp *nat_pptp_info;
struct nf_nat_range2 range;
struct nf_conn_nat *nat;
nat = nf_ct_nat_ext_add(ct);
if (WARN_ON_ONCE(!nat))
return;
nat_pptp_info = &nat->help.nat_pptp_info;
ct_pptp_info = nfct_help_data(master);
/* And here goes the grand finale of corrosion... */
if (exp->dir == IP_CT_DIR_ORIGINAL) {
pr_debug("we are PNS->PAC\n");
/* therefore, build tuple for PAC->PNS */
t.src.l3num = AF_INET;
t.src.u3.ip = master->tuplehash[!exp->dir].tuple.src.u3.ip;
t.src.u.gre.key = ct_pptp_info->pac_call_id;
t.dst.u3.ip = master->tuplehash[!exp->dir].tuple.dst.u3.ip;
t.dst.u.gre.key = ct_pptp_info->pns_call_id;
t.dst.protonum = IPPROTO_GRE;
} else {
pr_debug("we are PAC->PNS\n");
/* build tuple for PNS->PAC */
t.src.l3num = AF_INET;
t.src.u3.ip = master->tuplehash[!exp->dir].tuple.src.u3.ip;
t.src.u.gre.key = nat_pptp_info->pns_call_id;
t.dst.u3.ip = master->tuplehash[!exp->dir].tuple.dst.u3.ip;
t.dst.u.gre.key = nat_pptp_info->pac_call_id;
t.dst.protonum = IPPROTO_GRE;
}
pr_debug("trying to unexpect other dir: ");
nf_ct_dump_tuple_ip(&t);
other_exp = nf_ct_expect_find_get(net, nf_ct_zone(ct), &t);
if (other_exp) {
nf_ct_unexpect_related(other_exp);
nf_ct_expect_put(other_exp);
pr_debug("success\n");
} else {
pr_debug("not found!\n");
}
/* This must be a fresh one. */
BUG_ON(ct->status & IPS_NAT_DONE_MASK);
/* Change src to where master sends to */
range.flags = NF_NAT_RANGE_MAP_IPS;
range.min_addr = range.max_addr
= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
if (exp->dir == IP_CT_DIR_ORIGINAL) {
range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
range.min_proto = range.max_proto = exp->saved_proto;
}
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
/* For DST manip, map port here to where it's expected. */
range.flags = NF_NAT_RANGE_MAP_IPS;
range.min_addr = range.max_addr
= ct->master->tuplehash[!exp->dir].tuple.src.u3;
if (exp->dir == IP_CT_DIR_REPLY) {
range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
range.min_proto = range.max_proto = exp->saved_proto;
}
nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
}
