Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next

Pablo Neira Ayuso says:

====================
Netfilter/IPVS/OVS updates for net-next

The following patchset contains Netfilter/IPVS fixes and OVS NAT
support, more specifically this batch is composed of:

1) Fix a crash in ipset when performing a parallel flush/dump with
   set:list type, from Jozsef Kadlecsik.

2) Make sure NFACCT_FILTER_* netlink attributes are in place before
   accessing them, from Phil Turnbull.

3) Check return error code from ip_vs_fill_iph_skb_off() in IPVS SIP
   helper, from Arnd Bergmann.

4) Add workaround to IPVS to reschedule existing connections to new
   destination server by dropping the packet and wait for retransmission
   of TCP syn packet, from Julian Anastasov.

5) Allow connection rescheduling in IPVS when in CLOSE state, also
   from Julian.

6) Fix wrong offset of SIP Call-ID in IPVS helper, from Marco Angaroni.

7) Validate IPSET_ATTR_ETHER netlink attribute length, from Jozsef.

8) Check match/targetinfo netlink attribute size in nft_compat,
   patch from Florian Westphal.

9) Check for integer overflow on 32-bit systems in x_tables, from
   Florian Westphal.

Several patches from Jarno Rajahalme to prepare the introduction of
NAT support to OVS based on the Netfilter infrastructure:

10) Schedule IP_CT_NEW_REPLY definition for removal in
    nf_conntrack_common.h.

11) Simplify checksumming recalculation in nf_nat.

12) Add comments to the openvswitch conntrack code, from Jarno.

13) Update the CT state key only after successful nf_conntrack_in()
    invocation.

14) Find existing conntrack entry after upcall.

15) Handle NF_REPEAT case due to templates in nf_conntrack_in().

16) Call the conntrack helper functions once the conntrack has been
    confirmed.

17) And finally, add the NAT interface to OVS.

The batch closes with:

18) Cleanup to use spin_unlock_wait() instead of
    spin_lock()/spin_unlock(), from Nicholas Mc Guire.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 626 insertions, 40 deletions

diff --git a/net/openvswitch/Kconfig b/net/openvswitch/Kconfig
index cd5fd9d728a7..234a73344c6e 100644
--- a/net/openvswitch/Kconfig
+++ b/net/openvswitch/Kconfig
@@ -6,7 +6,8 @@ config OPENVSWITCH
 	tristate "Open vSwitch"
 	depends on INET
 	depends on !NF_CONNTRACK || \
-		   (NF_CONNTRACK && (!NF_DEFRAG_IPV6 || NF_DEFRAG_IPV6))
+		   (NF_CONNTRACK && ((!NF_DEFRAG_IPV6 || NF_DEFRAG_IPV6) && \
+				     (!NF_NAT || NF_NAT)))
 	select LIBCRC32C
 	select MPLS
 	select NET_MPLS_GSO
diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index ee6ff8ffc12d..dc5eb29fe7d6 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -13,21 +13,31 @@
 
 #include <linux/module.h>
 #include <linux/openvswitch.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/sctp.h>
 #include <net/ip.h>
 #include <net/netfilter/nf_conntrack_core.h>
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_labels.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
 #include <net/netfilter/nf_conntrack_zones.h>
 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
 
+#ifdef CONFIG_NF_NAT_NEEDED
+#include <linux/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_l3proto.h>
+#endif
+
 #include "datapath.h"
 #include "conntrack.h"
 #include "flow.h"
 #include "flow_netlink.h"
 
 struct ovs_ct_len_tbl {
-	size_t maxlen;
-	size_t minlen;
+	int maxlen;
+	int minlen;
 };
 
 /* Metadata mark for masked write to conntrack mark */
@@ -42,15 +52,25 @@ struct md_labels {
 	struct ovs_key_ct_labels mask;
 };
 
+enum ovs_ct_nat {
+	OVS_CT_NAT = 1 << 0,     /* NAT for committed connections only. */
+	OVS_CT_SRC_NAT = 1 << 1, /* Source NAT for NEW connections. */
+	OVS_CT_DST_NAT = 1 << 2, /* Destination NAT for NEW connections. */
+};
+
 /* Conntrack action context for execution. */
 struct ovs_conntrack_info {
 	struct nf_conntrack_helper *helper;
 	struct nf_conntrack_zone zone;
 	struct nf_conn *ct;
 	u8 commit : 1;
+	u8 nat : 3;                 /* enum ovs_ct_nat */
 	u16 family;
 	struct md_mark mark;
 	struct md_labels labels;
+#ifdef CONFIG_NF_NAT_NEEDED
+	struct nf_nat_range range;  /* Only present for SRC NAT and DST NAT. */
+#endif
 };
 
 static void __ovs_ct_free_action(struct ovs_conntrack_info *ct_info);
@@ -75,7 +95,6 @@ static u8 ovs_ct_get_state(enum ip_conntrack_info ctinfo)
 	switch (ctinfo) {
 	case IP_CT_ESTABLISHED_REPLY:
 	case IP_CT_RELATED_REPLY:
-	case IP_CT_NEW_REPLY:
 		ct_state |= OVS_CS_F_REPLY_DIR;
 		break;
 	default:
@@ -92,7 +111,6 @@ static u8 ovs_ct_get_state(enum ip_conntrack_info ctinfo)
 		ct_state |= OVS_CS_F_RELATED;
 		break;
 	case IP_CT_NEW:
-	case IP_CT_NEW_REPLY:
 		ct_state |= OVS_CS_F_NEW;
 		break;
 	default:
@@ -139,12 +157,15 @@ static void __ovs_ct_update_key(struct sw_flow_key *key, u8 state,
 	ovs_ct_get_labels(ct, &key->ct.labels);
 }
 
-/* Update 'key' based on skb->nfct. If 'post_ct' is true, then OVS has
- * previously sent the packet to conntrack via the ct action.
+/* Update 'key' based on skb->nfct.  If 'post_ct' is true, then OVS has
+ * previously sent the packet to conntrack via the ct action.  If
+ * 'keep_nat_flags' is true, the existing NAT flags retained, else they are
+ * initialized from the connection status.
  */
 static void ovs_ct_update_key(const struct sk_buff *skb,
 			      const struct ovs_conntrack_info *info,
-			      struct sw_flow_key *key, bool post_ct)
+			      struct sw_flow_key *key, bool post_ct,
+			      bool keep_nat_flags)
 {
 	const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
 	enum ip_conntrack_info ctinfo;
@@ -154,10 +175,22 @@ static void ovs_ct_update_key(const struct sk_buff *skb,
 	ct = nf_ct_get(skb, &ctinfo);
 	if (ct) {
 		state = ovs_ct_get_state(ctinfo);
+		/* All unconfirmed entries are NEW connections. */
 		if (!nf_ct_is_confirmed(ct))
 			state |= OVS_CS_F_NEW;
+		/* OVS persists the related flag for the duration of the
+		 * connection.
+		 */
 		if (ct->master)
 			state |= OVS_CS_F_RELATED;
+		if (keep_nat_flags) {
+			state |= key->ct.state & OVS_CS_F_NAT_MASK;
+		} else {
+			if (ct->status & IPS_SRC_NAT)
+				state |= OVS_CS_F_SRC_NAT;
+			if (ct->status & IPS_DST_NAT)
+				state |= OVS_CS_F_DST_NAT;
+		}
 		zone = nf_ct_zone(ct);
 	} else if (post_ct) {
 		state = OVS_CS_F_TRACKED | OVS_CS_F_INVALID;
@@ -167,9 +200,12 @@ static void ovs_ct_update_key(const struct sk_buff *skb,
 	__ovs_ct_update_key(key, state, zone, ct);
 }
 
+/* This is called to initialize CT key fields possibly coming in from the local
+ * stack.
+ */
 void ovs_ct_fill_key(const struct sk_buff *skb, struct sw_flow_key *key)
 {
-	ovs_ct_update_key(skb, NULL, key, false);
+	ovs_ct_update_key(skb, NULL, key, false, false);
 }
 
 int ovs_ct_put_key(const struct sw_flow_key *key, struct sk_buff *skb)
@@ -201,7 +237,6 @@ static int ovs_ct_set_mark(struct sk_buff *skb, struct sw_flow_key *key,
 	struct nf_conn *ct;
 	u32 new_mark;
 
-
 	/* The connection could be invalid, in which case set_mark is no-op. */
 	ct = nf_ct_get(skb, &ctinfo);
 	if (!ct)
@@ -259,6 +294,7 @@ static int ovs_ct_helper(struct sk_buff *skb, u16 proto)
 	enum ip_conntrack_info ctinfo;
 	unsigned int protoff;
 	struct nf_conn *ct;
+	int err;
 
 	ct = nf_ct_get(skb, &ctinfo);
 	if (!ct || ctinfo == IP_CT_RELATED_REPLY)
@@ -295,7 +331,18 @@ static int ovs_ct_helper(struct sk_buff *skb, u16 proto)
 		return NF_DROP;
 	}
 
-	return helper->help(skb, protoff, ct, ctinfo);
+	err = helper->help(skb, protoff, ct, ctinfo);
+	if (err != NF_ACCEPT)
+		return err;
+
+	/* Adjust seqs after helper.  This is needed due to some helpers (e.g.,
+	 * FTP with NAT) adusting the TCP payload size when mangling IP
+	 * addresses and/or port numbers in the text-based control connection.
+	 */
+	if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
+	    !nf_ct_seq_adjust(skb, ct, ctinfo, protoff))
+		return NF_DROP;
+	return NF_ACCEPT;
 }
 
 /* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
@@ -352,14 +399,101 @@ ovs_ct_expect_find(struct net *net, const struct nf_conntrack_zone *zone,
 	return __nf_ct_expect_find(net, zone, &tuple);
 }
 
+/* This replicates logic from nf_conntrack_core.c that is not exported. */
+static enum ip_conntrack_info
+ovs_ct_get_info(const struct nf_conntrack_tuple_hash *h)
+{
+	const struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
+
+	if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
+		return IP_CT_ESTABLISHED_REPLY;
+	/* Once we've had two way comms, always ESTABLISHED. */
+	if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status))
+		return IP_CT_ESTABLISHED;
+	if (test_bit(IPS_EXPECTED_BIT, &ct->status))
+		return IP_CT_RELATED;
+	return IP_CT_NEW;
+}
+
+/* Find an existing connection which this packet belongs to without
+ * re-attributing statistics or modifying the connection state.  This allows an
+ * skb->nfct lost due to an upcall to be recovered during actions execution.
+ *
+ * Must be called with rcu_read_lock.
+ *
+ * On success, populates skb->nfct and skb->nfctinfo, and returns the
+ * connection.  Returns NULL if there is no existing entry.
+ */
+static struct nf_conn *
+ovs_ct_find_existing(struct net *net, const struct nf_conntrack_zone *zone,
+		     u8 l3num, struct sk_buff *skb)
+{
+	struct nf_conntrack_l3proto *l3proto;
+	struct nf_conntrack_l4proto *l4proto;
+	struct nf_conntrack_tuple tuple;
+	struct nf_conntrack_tuple_hash *h;
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct;
+	unsigned int dataoff;
+	u8 protonum;
+
+	l3proto = __nf_ct_l3proto_find(l3num);
+	if (!l3proto) {
+		pr_debug("ovs_ct_find_existing: Can't get l3proto\n");
+		return NULL;
+	}
+	if (l3proto->get_l4proto(skb, skb_network_offset(skb), &dataoff,
+				 &protonum) <= 0) {
+		pr_debug("ovs_ct_find_existing: Can't get protonum\n");
+		return NULL;
+	}
+	l4proto = __nf_ct_l4proto_find(l3num, protonum);
+	if (!l4proto) {
+		pr_debug("ovs_ct_find_existing: Can't get l4proto\n");
+		return NULL;
+	}
+	if (!nf_ct_get_tuple(skb, skb_network_offset(skb), dataoff, l3num,
+			     protonum, net, &tuple, l3proto, l4proto)) {
+		pr_debug("ovs_ct_find_existing: Can't get tuple\n");
+		return NULL;
+	}
+
+	/* look for tuple match */
+	h = nf_conntrack_find_get(net, zone, &tuple);
+	if (!h)
+		return NULL;   /* Not found. */
+
+	ct = nf_ct_tuplehash_to_ctrack(h);
+
+	ctinfo = ovs_ct_get_info(h);
+	if (ctinfo == IP_CT_NEW) {
+		/* This should not happen. */
+		WARN_ONCE(1, "ovs_ct_find_existing: new packet for %p\n", ct);
+	}
+	skb->nfct = &ct->ct_general;
+	skb->nfctinfo = ctinfo;
+	return ct;
+}
+
 /* Determine whether skb->nfct is equal to the result of conntrack lookup. */
-static bool skb_nfct_cached(const struct net *net, const struct sk_buff *skb,
-			    const struct ovs_conntrack_info *info)
+static bool skb_nfct_cached(struct net *net,
+			    const struct sw_flow_key *key,
+			    const struct ovs_conntrack_info *info,
+			    struct sk_buff *skb)
 {
 	enum ip_conntrack_info ctinfo;
 	struct nf_conn *ct;
 
 	ct = nf_ct_get(skb, &ctinfo);
+	/* If no ct, check if we have evidence that an existing conntrack entry
+	 * might be found for this skb.  This happens when we lose a skb->nfct
+	 * due to an upcall.  If the connection was not confirmed, it is not
+	 * cached and needs to be run through conntrack again.
+	 */
+	if (!ct && key->ct.state & OVS_CS_F_TRACKED &&
+	    !(key->ct.state & OVS_CS_F_INVALID) &&
+	    key->ct.zone == info->zone.id)
+		ct = ovs_ct_find_existing(net, &info->zone, info->family, skb);
 	if (!ct)
 		return false;
 	if (!net_eq(net, read_pnet(&ct->ct_net)))
@@ -377,6 +511,206 @@ static bool skb_nfct_cached(const struct net *net, const struct sk_buff *skb,
 	return true;
 }
 
+#ifdef CONFIG_NF_NAT_NEEDED
+/* Modelled after nf_nat_ipv[46]_fn().
+ * range is only used for new, uninitialized NAT state.
+ * Returns either NF_ACCEPT or NF_DROP.
+ */
+static int ovs_ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct,
+			      enum ip_conntrack_info ctinfo,
+			      const struct nf_nat_range *range,
+			      enum nf_nat_manip_type maniptype)
+{
+	int hooknum, nh_off, err = NF_ACCEPT;
+
+	nh_off = skb_network_offset(skb);
+	skb_pull(skb, nh_off);
+
+	/* See HOOK2MANIP(). */
+	if (maniptype == NF_NAT_MANIP_SRC)
+		hooknum = NF_INET_LOCAL_IN; /* Source NAT */
+	else
+		hooknum = NF_INET_LOCAL_OUT; /* Destination NAT */
+
+	switch (ctinfo) {
+	case IP_CT_RELATED:
+	case IP_CT_RELATED_REPLY:
+		if (skb->protocol == htons(ETH_P_IP) &&
+		    ip_hdr(skb)->protocol == IPPROTO_ICMP) {
+			if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
+							   hooknum))
+				err = NF_DROP;
+			goto push;
+#if IS_ENABLED(CONFIG_NF_NAT_IPV6)
+		} else if (skb->protocol == htons(ETH_P_IPV6)) {
+			__be16 frag_off;
+			u8 nexthdr = ipv6_hdr(skb)->nexthdr;
+			int 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,
+								     hooknum,
+								     hdrlen))
+					err = NF_DROP;
+				goto push;
+			}
+#endif
+		}
+		/* Non-ICMP, fall thru to initialize if needed. */
+	case IP_CT_NEW:
+		/* Seen it before?  This can happen for loopback, retrans,
+		 * or local packets.
+		 */
+		if (!nf_nat_initialized(ct, maniptype)) {
+			/* Initialize according to the NAT action. */
+			err = (range && range->flags & NF_NAT_RANGE_MAP_IPS)
+				/* Action is set up to establish a new
+				 * mapping.
+				 */
+				? nf_nat_setup_info(ct, range, maniptype)
+				: nf_nat_alloc_null_binding(ct, hooknum);
+			if (err != NF_ACCEPT)
+				goto push;
+		}
+		break;
+
+	case IP_CT_ESTABLISHED:
+	case IP_CT_ESTABLISHED_REPLY:
+		break;
+
+	default:
+		err = NF_DROP;
+		goto push;
+	}
+
+	err = nf_nat_packet(ct, ctinfo, hooknum, skb);
+push:
+	skb_push(skb, nh_off);
+
+	return err;
+}
+
+static void ovs_nat_update_key(struct sw_flow_key *key,
+			       const struct sk_buff *skb,
+			       enum nf_nat_manip_type maniptype)
+{
+	if (maniptype == NF_NAT_MANIP_SRC) {
+		__be16 src;
+
+		key->ct.state |= OVS_CS_F_SRC_NAT;
+		if (key->eth.type == htons(ETH_P_IP))
+			key->ipv4.addr.src = ip_hdr(skb)->saddr;
+		else if (key->eth.type == htons(ETH_P_IPV6))
+			memcpy(&key->ipv6.addr.src, &ipv6_hdr(skb)->saddr,
+			       sizeof(key->ipv6.addr.src));
+		else
+			return;
+
+		if (key->ip.proto == IPPROTO_UDP)
+			src = udp_hdr(skb)->source;
+		else if (key->ip.proto == IPPROTO_TCP)
+			src = tcp_hdr(skb)->source;
+		else if (key->ip.proto == IPPROTO_SCTP)
+			src = sctp_hdr(skb)->source;
+		else
+			return;
+
+		key->tp.src = src;
+	} else {
+		__be16 dst;
+
+		key->ct.state |= OVS_CS_F_DST_NAT;
+		if (key->eth.type == htons(ETH_P_IP))
+			key->ipv4.addr.dst = ip_hdr(skb)->daddr;
+		else if (key->eth.type == htons(ETH_P_IPV6))
+			memcpy(&key->ipv6.addr.dst, &ipv6_hdr(skb)->daddr,
+			       sizeof(key->ipv6.addr.dst));
+		else
+			return;
+
+		if (key->ip.proto == IPPROTO_UDP)
+			dst = udp_hdr(skb)->dest;
+		else if (key->ip.proto == IPPROTO_TCP)
+			dst = tcp_hdr(skb)->dest;
+		else if (key->ip.proto == IPPROTO_SCTP)
+			dst = sctp_hdr(skb)->dest;
+		else
+			return;
+
+		key->tp.dst = dst;
+	}
+}
+
+/* Returns NF_DROP if the packet should be dropped, NF_ACCEPT otherwise. */
+static int ovs_ct_nat(struct net *net, struct sw_flow_key *key,
+		      const struct ovs_conntrack_info *info,
+		      struct sk_buff *skb, struct nf_conn *ct,
+		      enum ip_conntrack_info ctinfo)
+{
+	enum nf_nat_manip_type maniptype;
+	int err;
+
+	if (nf_ct_is_untracked(ct)) {
+		/* A NAT action may only be performed on tracked packets. */
+		return NF_ACCEPT;
+	}
+
+	/* Add NAT extension if not confirmed yet. */
+	if (!nf_ct_is_confirmed(ct) && !nf_ct_nat_ext_add(ct))
+		return NF_ACCEPT;   /* Can't NAT. */
+
+	/* Determine NAT type.
+	 * Check if the NAT type can be deduced from the tracked connection.
+	 * Make sure expected traffic is NATted only when committing.
+	 */
+	if (info->nat & OVS_CT_NAT && ctinfo != IP_CT_NEW &&
+	    ct->status & IPS_NAT_MASK &&
+	    (!(ct->status & IPS_EXPECTED_BIT) || info->commit)) {
+		/* NAT an established or related connection like before. */
+		if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY)
+			/* This is the REPLY direction for a connection
+			 * for which NAT was applied in the forward
+			 * direction.  Do the reverse NAT.
+			 */
+			maniptype = ct->status & IPS_SRC_NAT
+				? NF_NAT_MANIP_DST : NF_NAT_MANIP_SRC;
+		else
+			maniptype = ct->status & IPS_SRC_NAT
+				? NF_NAT_MANIP_SRC : NF_NAT_MANIP_DST;
+	} else if (info->nat & OVS_CT_SRC_NAT) {
+		maniptype = NF_NAT_MANIP_SRC;
+	} else if (info->nat & OVS_CT_DST_NAT) {
+		maniptype = NF_NAT_MANIP_DST;
+	} else {
+		return NF_ACCEPT; /* Connection is not NATed. */
+	}
+	err = ovs_ct_nat_execute(skb, ct, ctinfo, &info->range, maniptype);
+
+	/* Mark NAT done if successful and update the flow key. */
+	if (err == NF_ACCEPT)
+		ovs_nat_update_key(key, skb, maniptype);
+
+	return err;
+}
+#else /* !CONFIG_NF_NAT_NEEDED */
+static int ovs_ct_nat(struct net *net, struct sw_flow_key *key,
+		      const struct ovs_conntrack_info *info,
+		      struct sk_buff *skb, struct nf_conn *ct,
+		      enum ip_conntrack_info ctinfo)
+{
+	return NF_ACCEPT;
+}
+#endif
+
+/* Pass 'skb' through conntrack in 'net', using zone configured in 'info', if
+ * not done already.  Update key with new CT state after passing the packet
+ * through conntrack.
+ * Note that if the packet is deemed invalid by conntrack, skb->nfct will be
+ * set to NULL and 0 will be returned.
+ */
 static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
 			   const struct ovs_conntrack_info *info,
 			   struct sk_buff *skb)
@@ -386,8 +720,13 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
 	 * actually run the packet through conntrack twice unless it's for a
 	 * different zone.
 	 */
-	if (!skb_nfct_cached(net, skb, info)) {
+	bool cached = skb_nfct_cached(net, key, info, skb);
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct;
+
+	if (!cached) {
 		struct nf_conn *tmpl = info->ct;
+		int err;
 
 		/* Associate skb with specified zone. */
 		if (tmpl) {
@@ -398,17 +737,53 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
 			skb->nfctinfo = IP_CT_NEW;
 		}
 
-		if (nf_conntrack_in(net, info->family, NF_INET_PRE_ROUTING,
-				    skb) != NF_ACCEPT)
+		/* Repeat if requested, see nf_iterate(). */
+		do {
+			err = nf_conntrack_in(net, info->family,
+					      NF_INET_PRE_ROUTING, skb);
+		} while (err == NF_REPEAT);
+
+		if (err != NF_ACCEPT)
 			return -ENOENT;
 
-		if (ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
-			WARN_ONCE(1, "helper rejected packet");
+		/* Clear CT state NAT flags to mark that we have not yet done
+		 * NAT after the nf_conntrack_in() call.  We can actually clear
+		 * the whole state, as it will be re-initialized below.
+		 */
+		key->ct.state = 0;
+
+		/* Update the key, but keep the NAT flags. */
+		ovs_ct_update_key(skb, info, key, true, true);
+	}
+
+	ct = nf_ct_get(skb, &ctinfo);
+	if (ct) {
+		/* Packets starting a new connection must be NATted before the
+		 * helper, so that the helper knows about the NAT.  We enforce
+		 * this by delaying both NAT and helper calls for unconfirmed
+		 * connections until the committing CT action.  For later
+		 * packets NAT and Helper may be called in either order.
+		 *
+		 * NAT will be done only if the CT action has NAT, and only
+		 * once per packet (per zone), as guarded by the NAT bits in
+		 * the key->ct.state.
+		 */
+		if (info->nat && !(key->ct.state & OVS_CS_F_NAT_MASK) &&
+		    (nf_ct_is_confirmed(ct) || info->commit) &&
+		    ovs_ct_nat(net, key, info, skb, ct, ctinfo) != NF_ACCEPT) {
 			return -EINVAL;
 		}
-	}
 
-	ovs_ct_update_key(skb, info, key, true);
+		/* Call the helper only if:
+		 * - nf_conntrack_in() was executed above ("!cached") for a
+		 *   confirmed connection, or
+		 * - When committing an unconfirmed connection.
+		 */
+		if ((nf_ct_is_confirmed(ct) ? !cached : info->commit) &&
+		    ovs_ct_helper(skb, info->family) != NF_ACCEPT) {
+			return -EINVAL;
+		}
+	}
 
 	return 0;
 }
@@ -420,19 +795,24 @@ static int ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
 {
 	struct nf_conntrack_expect *exp;
 
+	/* If we pass an expected packet through nf_conntrack_in() the
+	 * expectation is typically removed, but the packet could still be
+	 * lost in upcall processing.  To prevent this from happening we
+	 * perform an explicit expectation lookup.  Expected connections are
+	 * always new, and will be passed through conntrack only when they are
+	 * committed, as it is OK to remove the expectation at that time.
+	 */
 	exp = ovs_ct_expect_find(net, &info->zone, info->family, skb);
 	if (exp) {
 		u8 state;
 
+		/* NOTE: New connections are NATted and Helped only when
+		 * committed, so we are not calling into NAT here.
+		 */
 		state = OVS_CS_F_TRACKED | OVS_CS_F_NEW | OVS_CS_F_RELATED;
 		__ovs_ct_update_key(key, state, &info->zone, exp->master);
-	} else {
-		int err;
-
-		err = __ovs_ct_lookup(net, key, info, skb);
-		if (err)
-			return err;
-	}
+	} else
+		return __ovs_ct_lookup(net, key, info, skb);
 
 	return 0;
 }
@@ -442,21 +822,12 @@ static int ovs_ct_commit(struct net *net, struct sw_flow_key *key,
 			 const struct ovs_conntrack_info *info,
 			 struct sk_buff *skb)
 {
-	u8 state;
 	int err;
 
-	state = key->ct.state;
-	if (key->ct.zone == info->zone.id &&
-	    ((state & OVS_CS_F_TRACKED) && !(state & OVS_CS_F_NEW))) {
-		/* Previous lookup has shown that this connection is already
-		 * tracked and committed. Skip committing.
-		 */
-		return 0;
-	}
-
 	err = __ovs_ct_lookup(net, key, info, skb);
 	if (err)
 		return err;
+	/* This is a no-op if the connection has already been confirmed. */
 	if (nf_conntrack_confirm(skb) != NF_ACCEPT)
 		return -EINVAL;
 
@@ -541,6 +912,135 @@ static int ovs_ct_add_helper(struct ovs_conntrack_info *info, const char *name,
 	return 0;
 }
 
+#ifdef CONFIG_NF_NAT_NEEDED
+static int parse_nat(const struct nlattr *attr,
+		     struct ovs_conntrack_info *info, bool log)
+{
+	struct nlattr *a;
+	int rem;
+	bool have_ip_max = false;
+	bool have_proto_max = false;
+	bool ip_vers = (info->family == NFPROTO_IPV6);
+
+	nla_for_each_nested(a, attr, rem) {
+		static const int ovs_nat_attr_lens[OVS_NAT_ATTR_MAX + 1][2] = {
+			[OVS_NAT_ATTR_SRC] = {0, 0},
+			[OVS_NAT_ATTR_DST] = {0, 0},
+			[OVS_NAT_ATTR_IP_MIN] = {sizeof(struct in_addr),
+						 sizeof(struct in6_addr)},
+			[OVS_NAT_ATTR_IP_MAX] = {sizeof(struct in_addr),
+						 sizeof(struct in6_addr)},
+			[OVS_NAT_ATTR_PROTO_MIN] = {sizeof(u16), sizeof(u16)},
+			[OVS_NAT_ATTR_PROTO_MAX] = {sizeof(u16), sizeof(u16)},
+			[OVS_NAT_ATTR_PERSISTENT] = {0, 0},
+			[OVS_NAT_ATTR_PROTO_HASH] = {0, 0},
+			[OVS_NAT_ATTR_PROTO_RANDOM] = {0, 0},
+		};
+		int type = nla_type(a);
+
+		if (type > OVS_NAT_ATTR_MAX) {
+			OVS_NLERR(log,
+				  "Unknown NAT attribute (type=%d, max=%d).\n",
+				  type, OVS_NAT_ATTR_MAX);
+			return -EINVAL;
+		}
+
+		if (nla_len(a) != ovs_nat_attr_lens[type][ip_vers]) {
+			OVS_NLERR(log,
+				  "NAT attribute type %d has unexpected length (%d != %d).\n",
+				  type, nla_len(a),
+				  ovs_nat_attr_lens[type][ip_vers]);
+			return -EINVAL;
+		}
+
+		switch (type) {
+		case OVS_NAT_ATTR_SRC:
+		case OVS_NAT_ATTR_DST:
+			if (info->nat) {
+				OVS_NLERR(log,
+					  "Only one type of NAT may be specified.\n"
+					  );
+				return -ERANGE;
+			}
+			info->nat |= OVS_CT_NAT;
+			info->nat |= ((type == OVS_NAT_ATTR_SRC)
+					? OVS_CT_SRC_NAT : OVS_CT_DST_NAT);
+			break;
+
+		case OVS_NAT_ATTR_IP_MIN:
+			nla_memcpy(&info->range.min_addr, a, nla_len(a));
+			info->range.flags |= NF_NAT_RANGE_MAP_IPS;
+			break;
+
+		case OVS_NAT_ATTR_IP_MAX:
+			have_ip_max = true;
+			nla_memcpy(&info->range.max_addr, a,
+				   sizeof(info->range.max_addr));
+			info->range.flags |= NF_NAT_RANGE_MAP_IPS;
+			break;
+
+		case OVS_NAT_ATTR_PROTO_MIN:
+			info->range.min_proto.all = htons(nla_get_u16(a));
+			info->range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+			break;
+
+		case OVS_NAT_ATTR_PROTO_MAX:
+			have_proto_max = true;
+			info->range.max_proto.all = htons(nla_get_u16(a));
+			info->range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+			break;
+
+		case OVS_NAT_ATTR_PERSISTENT:
+			info->range.flags |= NF_NAT_RANGE_PERSISTENT;
+			break;
+
+		case OVS_NAT_ATTR_PROTO_HASH:
+			info->range.flags |= NF_NAT_RANGE_PROTO_RANDOM;
+			break;
+
+		case OVS_NAT_ATTR_PROTO_RANDOM:
+			info->range.flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY;
+			break;
+
+		default:
+			OVS_NLERR(log, "Unknown nat attribute (%d).\n", type);
+			return -EINVAL;
+		}
+	}
+
+	if (rem > 0) {
+		OVS_NLERR(log, "NAT attribute has %d unknown bytes.\n", rem);
+		return -EINVAL;
+	}
+	if (!info->nat) {
+		/* Do not allow flags if no type is given. */
+		if (info->range.flags) {
+			OVS_NLERR(log,
+				  "NAT flags may be given only when NAT range (SRC or DST) is also specified.\n"
+				  );
+			return -EINVAL;
+		}
+		info->nat = OVS_CT_NAT;   /* NAT existing connections. */
+	} else if (!info->commit) {
+		OVS_NLERR(log,
+			  "NAT attributes may be specified only when CT COMMIT flag is also specified.\n"
+			  );
+		return -EINVAL;
+	}
+	/* Allow missing IP_MAX. */
+	if (info->range.flags & NF_NAT_RANGE_MAP_IPS && !have_ip_max) {
+		memcpy(&info->range.max_addr, &info->range.min_addr,
+		       sizeof(info->range.max_addr));
+	}
+	/* Allow missing PROTO_MAX. */
+	if (info->range.flags & NF_NAT_RANGE_PROTO_SPECIFIED &&
+	    !have_proto_max) {
+		info->range.max_proto.all = info->range.min_proto.all;
+	}
+	return 0;
+}
+#endif
+
 static const struct ovs_ct_len_tbl ovs_ct_attr_lens[OVS_CT_ATTR_MAX + 1] = {
 	[OVS_CT_ATTR_COMMIT]	= { .minlen = 0, .maxlen = 0 },
 	[OVS_CT_ATTR_ZONE]	= { .minlen = sizeof(u16),
@@ -550,7 +1050,11 @@ static const struct ovs_ct_len_tbl ovs_ct_attr_lens[OVS_CT_ATTR_MAX + 1] = {
 	[OVS_CT_ATTR_LABELS]	= { .minlen = sizeof(struct md_labels),
 				    .maxlen = sizeof(struct md_labels) },
 	[OVS_CT_ATTR_HELPER]	= { .minlen = 1,
-				    .maxlen = NF_CT_HELPER_NAME_LEN }
+				    .maxlen = NF_CT_HELPER_NAME_LEN },
+#ifdef CONFIG_NF_NAT_NEEDED
+	/* NAT length is checked when parsing the nested attributes. */
+	[OVS_CT_ATTR_NAT]	= { .minlen = 0, .maxlen = INT_MAX },
+#endif
 };
 
 static int parse_ct(const struct nlattr *attr, struct ovs_conntrack_info *info,
@@ -617,6 +1121,15 @@ static int parse_ct(const struct nlattr *attr, struct ovs_conntrack_info *info,
 				return -EINVAL;
 			}
 			break;
+#ifdef CONFIG_NF_NAT_NEEDED
+		case OVS_CT_ATTR_NAT: {
+			int err = parse_nat(a, info, log);
+
+			if (err)
+				return err;
+			break;
+		}
+#endif
 		default:
 			OVS_NLERR(log, "Unknown conntrack attr (%d)",
 				  type);
@@ -704,6 +1217,74 @@ err_free_ct:
 	return err;
 }
 
+#ifdef CONFIG_NF_NAT_NEEDED
+static bool ovs_ct_nat_to_attr(const struct ovs_conntrack_info *info,
+			       struct sk_buff *skb)
+{
+	struct nlattr *start;
+
+	start = nla_nest_start(skb, OVS_CT_ATTR_NAT);
+	if (!start)
+		return false;
+
+	if (info->nat & OVS_CT_SRC_NAT) {
+		if (nla_put_flag(skb, OVS_NAT_ATTR_SRC))
+			return false;
+	} else if (info->nat & OVS_CT_DST_NAT) {
+		if (nla_put_flag(skb, OVS_NAT_ATTR_DST))
+			return false;
+	} else {
+		goto out;
+	}
+
+	if (info->range.flags & NF_NAT_RANGE_MAP_IPS) {
+		if (info->family == NFPROTO_IPV4) {
+			if (nla_put_in_addr(skb, OVS_NAT_ATTR_IP_MIN,
+					    info->range.min_addr.ip) ||
+			    (info->range.max_addr.ip
+			     != info->range.min_addr.ip &&
+			     (nla_put_in_addr(skb, OVS_NAT_ATTR_IP_MAX,
+					      info->range.max_addr.ip))))
+				return false;
+#if IS_ENABLED(CONFIG_NF_NAT_IPV6)
+		} else if (info->family == NFPROTO_IPV6) {
+			if (nla_put_in6_addr(skb, OVS_NAT_ATTR_IP_MIN,
+					     &info->range.min_addr.in6) ||
+			    (memcmp(&info->range.max_addr.in6,
+				    &info->range.min_addr.in6,
+				    sizeof(info->range.max_addr.in6)) &&
+			     (nla_put_in6_addr(skb, OVS_NAT_ATTR_IP_MAX,
+					       &info->range.max_addr.in6))))
+				return false;
+#endif
+		} else {
+			return false;
+		}
+	}
+	if (info->range.flags & NF_NAT_RANGE_PROTO_SPECIFIED &&
+	    (nla_put_u16(skb, OVS_NAT_ATTR_PROTO_MIN,
+			 ntohs(info->range.min_proto.all)) ||
+	     (info->range.max_proto.all != info->range.min_proto.all &&
+	      nla_put_u16(skb, OVS_NAT_ATTR_PROTO_MAX,
+			  ntohs(info->range.max_proto.all)))))
+		return false;
+
+	if (info->range.flags & NF_NAT_RANGE_PERSISTENT &&
+	    nla_put_flag(skb, OVS_NAT_ATTR_PERSISTENT))
+		return false;
+	if (info->range.flags & NF_NAT_RANGE_PROTO_RANDOM &&
+	    nla_put_flag(skb, OVS_NAT_ATTR_PROTO_HASH))
+		return false;
+	if (info->range.flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY &&
+	    nla_put_flag(skb, OVS_NAT_ATTR_PROTO_RANDOM))
+		return false;
+out:
+	nla_nest_end(skb, start);
+
+	return true;
+}
+#endif
+
 int ovs_ct_action_to_attr(const struct ovs_conntrack_info *ct_info,
 			  struct sk_buff *skb)
 {
@@ -732,7 +1313,10 @@ int ovs_ct_action_to_attr(const struct ovs_conntrack_info *ct_info,
 				   ct_info->helper->name))
 			return -EMSGSIZE;
 	}
-
+#ifdef CONFIG_NF_NAT_NEEDED
+	if (ct_info->nat && !ovs_ct_nat_to_attr(ct_info, skb))
+		return -EMSGSIZE;
+#endif
 	nla_nest_end(skb, start);
 
 	return 0;
diff --git a/net/openvswitch/conntrack.h b/net/openvswitch/conntrack.h
index a7544f405c16..8f6230bd6183 100644
--- a/net/openvswitch/conntrack.h
+++ b/net/openvswitch/conntrack.h
@@ -37,7 +37,8 @@ void ovs_ct_free_action(const struct nlattr *a);
 
 #define CT_SUPPORTED_MASK (OVS_CS_F_NEW | OVS_CS_F_ESTABLISHED | \
 			   OVS_CS_F_RELATED | OVS_CS_F_REPLY_DIR | \
-			   OVS_CS_F_INVALID | OVS_CS_F_TRACKED)
+			   OVS_CS_F_INVALID | OVS_CS_F_TRACKED | \
+			   OVS_CS_F_SRC_NAT | OVS_CS_F_DST_NAT)
 #else
 #include <linux/errno.h>