1 files changed, 334 insertions, 0 deletions
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
new file mode 100644
index 000000000..9265145f1
--- /dev/null
+++ b/net/sched/act_nat.c
@@ -0,0 +1,334 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Stateless NAT actions
+ *
+ * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/rtnetlink.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/tc_act/tc_nat.h>
+#include <net/act_api.h>
+#include <net/pkt_cls.h>
+#include <net/icmp.h>
+#include <net/ip.h>
+#include <net/netlink.h>
+#include <net/tc_act/tc_nat.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+
+
+static struct tc_action_ops act_nat_ops;
+
+static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
+	[TCA_NAT_PARMS]	= { .len = sizeof(struct tc_nat) },
+};
+
+static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
+			struct tc_action **a, struct tcf_proto *tp,
+			u32 flags, struct netlink_ext_ack *extack)
+{
+	struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
+	bool bind = flags & TCA_ACT_FLAGS_BIND;
+	struct nlattr *tb[TCA_NAT_MAX + 1];
+	struct tcf_chain *goto_ch = NULL;
+	struct tc_nat *parm;
+	int ret = 0, err;
+	struct tcf_nat *p;
+	u32 index;
+
+	if (nla == NULL)
+		return -EINVAL;
+
+	err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
+					  NULL);
+	if (err < 0)
+		return err;
+
+	if (tb[TCA_NAT_PARMS] == NULL)
+		return -EINVAL;
+	parm = nla_data(tb[TCA_NAT_PARMS]);
+	index = parm->index;
+	err = tcf_idr_check_alloc(tn, &index, a, bind);
+	if (!err) {
+		ret = tcf_idr_create(tn, index, est, a,
+				     &act_nat_ops, bind, false, flags);
+		if (ret) {
+			tcf_idr_cleanup(tn, index);
+			return ret;
+		}
+		ret = ACT_P_CREATED;
+	} else if (err > 0) {
+		if (bind)
+			return 0;
+		if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
+			tcf_idr_release(*a, bind);
+			return -EEXIST;
+		}
+	} else {
+		return err;
+	}
+	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
+	if (err < 0)
+		goto release_idr;
+	p = to_tcf_nat(*a);
+
+	spin_lock_bh(&p->tcf_lock);
+	p->old_addr = parm->old_addr;
+	p->new_addr = parm->new_addr;
+	p->mask = parm->mask;
+	p->flags = parm->flags;
+
+	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
+	spin_unlock_bh(&p->tcf_lock);
+	if (goto_ch)
+		tcf_chain_put_by_act(goto_ch);
+
+	return ret;
+release_idr:
+	tcf_idr_release(*a, bind);
+	return err;
+}
+
+static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
+		       struct tcf_result *res)
+{
+	struct tcf_nat *p = to_tcf_nat(a);
+	struct iphdr *iph;
+	__be32 old_addr;
+	__be32 new_addr;
+	__be32 mask;
+	__be32 addr;
+	int egress;
+	int action;
+	int ihl;
+	int noff;
+
+	spin_lock(&p->tcf_lock);
+
+	tcf_lastuse_update(&p->tcf_tm);
+	old_addr = p->old_addr;
+	new_addr = p->new_addr;
+	mask = p->mask;
+	egress = p->flags & TCA_NAT_FLAG_EGRESS;
+	action = p->tcf_action;
+
+	bstats_update(&p->tcf_bstats, skb);
+
+	spin_unlock(&p->tcf_lock);
+
+	if (unlikely(action == TC_ACT_SHOT))
+		goto drop;
+
+	noff = skb_network_offset(skb);
+	if (!pskb_may_pull(skb, sizeof(*iph) + noff))
+		goto drop;
+
+	iph = ip_hdr(skb);
+
+	if (egress)
+		addr = iph->saddr;
+	else
+		addr = iph->daddr;
+
+	if (!((old_addr ^ addr) & mask)) {
+		if (skb_try_make_writable(skb, sizeof(*iph) + noff))
+			goto drop;
+
+		new_addr &= mask;
+		new_addr |= addr & ~mask;
+
+		/* Rewrite IP header */
+		iph = ip_hdr(skb);
+		if (egress)
+			iph->saddr = new_addr;
+		else
+			iph->daddr = new_addr;
+
+		csum_replace4(&iph->check, addr, new_addr);
+	} else if ((iph->frag_off & htons(IP_OFFSET)) ||
+		   iph->protocol != IPPROTO_ICMP) {
+		goto out;
+	}
+
+	ihl = iph->ihl * 4;
+
+	/* It would be nice to share code with stateful NAT. */
+	switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
+	case IPPROTO_TCP:
+	{
+		struct tcphdr *tcph;
+
+		if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
+		    skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
+			goto drop;
+
+		tcph = (void *)(skb_network_header(skb) + ihl);
+		inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
+					 true);
+		break;
+	}
+	case IPPROTO_UDP:
+	{
+		struct udphdr *udph;
+
+		if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
+		    skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
+			goto drop;
+
+		udph = (void *)(skb_network_header(skb) + ihl);
+		if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
+			inet_proto_csum_replace4(&udph->check, skb, addr,
+						 new_addr, true);
+			if (!udph->check)
+				udph->check = CSUM_MANGLED_0;
+		}
+		break;
+	}
+	case IPPROTO_ICMP:
+	{
+		struct icmphdr *icmph;
+
+		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
+			goto drop;
+
+		icmph = (void *)(skb_network_header(skb) + ihl);
+
+		if (!icmp_is_err(icmph->type))
+			break;
+
+		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
+					noff))
+			goto drop;
+
+		icmph = (void *)(skb_network_header(skb) + ihl);
+		iph = (void *)(icmph + 1);
+		if (egress)
+			addr = iph->daddr;
+		else
+			addr = iph->saddr;
+
+		if ((old_addr ^ addr) & mask)
+			break;
+
+		if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
+					  sizeof(*iph) + noff))
+			goto drop;
+
+		icmph = (void *)(skb_network_header(skb) + ihl);
+		iph = (void *)(icmph + 1);
+
+		new_addr &= mask;
+		new_addr |= addr & ~mask;
+
+		/* XXX Fix up the inner checksums. */
+		if (egress)
+			iph->daddr = new_addr;
+		else
+			iph->saddr = new_addr;
+
+		inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
+					 false);
+		break;
+	}
+	default:
+		break;
+	}
+
+out:
+	return action;
+
+drop:
+	spin_lock(&p->tcf_lock);
+	p->tcf_qstats.drops++;
+	spin_unlock(&p->tcf_lock);
+	return TC_ACT_SHOT;
+}
+
+static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
+			int bind, int ref)
+{
+	unsigned char *b = skb_tail_pointer(skb);
+	struct tcf_nat *p = to_tcf_nat(a);
+	struct tc_nat opt = {
+		.index    = p->tcf_index,
+		.refcnt   = refcount_read(&p->tcf_refcnt) - ref,
+		.bindcnt  = atomic_read(&p->tcf_bindcnt) - bind,
+	};
+	struct tcf_t t;
+
+	spin_lock_bh(&p->tcf_lock);
+	opt.old_addr = p->old_addr;
+	opt.new_addr = p->new_addr;
+	opt.mask = p->mask;
+	opt.flags = p->flags;
+	opt.action = p->tcf_action;
+
+	if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
+		goto nla_put_failure;
+
+	tcf_tm_dump(&t, &p->tcf_tm);
+	if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
+		goto nla_put_failure;
+	spin_unlock_bh(&p->tcf_lock);
+
+	return skb->len;
+
+nla_put_failure:
+	spin_unlock_bh(&p->tcf_lock);
+	nlmsg_trim(skb, b);
+	return -1;
+}
+
+static struct tc_action_ops act_nat_ops = {
+	.kind		=	"nat",
+	.id		=	TCA_ID_NAT,
+	.owner		=	THIS_MODULE,
+	.act		=	tcf_nat_act,
+	.dump		=	tcf_nat_dump,
+	.init		=	tcf_nat_init,
+	.size		=	sizeof(struct tcf_nat),
+};
+
+static __net_init int nat_init_net(struct net *net)
+{
+	struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
+
+	return tc_action_net_init(net, tn, &act_nat_ops);
+}
+
+static void __net_exit nat_exit_net(struct list_head *net_list)
+{
+	tc_action_net_exit(net_list, act_nat_ops.net_id);
+}
+
+static struct pernet_operations nat_net_ops = {
+	.init = nat_init_net,
+	.exit_batch = nat_exit_net,
+	.id   = &act_nat_ops.net_id,
+	.size = sizeof(struct tc_action_net),
+};
+
+MODULE_DESCRIPTION("Stateless NAT actions");
+MODULE_LICENSE("GPL");
+
+static int __init nat_init_module(void)
+{
+	return tcf_register_action(&act_nat_ops, &nat_net_ops);
+}
+
+static void __exit nat_cleanup_module(void)
+{
+	tcf_unregister_action(&act_nat_ops, &nat_net_ops);
+}
+
+module_init(nat_init_module);
+module_exit(nat_cleanup_module);