mtd: nand: atmel: Relax tADL_min constraint

[mirror_ubuntu-artful-kernel.git] / net / openvswitch / conntrack.c

/*
 * Copyright (c) 2015 Nicira, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */

#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 {
        int maxlen;
        int minlen;
};

/* Metadata mark for masked write to conntrack mark */
struct md_mark {
        u32 value;
        u32 mask;
};

/* Metadata label for masked write to conntrack label. */
struct md_labels {
        struct ovs_key_ct_labels value;
        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 */
        u8 force : 1;
        u8 have_eventmask : 1;
        u16 family;
        u32 eventmask;              /* Mask of 1 << IPCT_*. */
        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 bool labels_nonzero(const struct ovs_key_ct_labels *labels);

static void __ovs_ct_free_action(struct ovs_conntrack_info *ct_info);

static u16 key_to_nfproto(const struct sw_flow_key *key)
{
        switch (ntohs(key->eth.type)) {
        case ETH_P_IP:
                return NFPROTO_IPV4;
        case ETH_P_IPV6:
                return NFPROTO_IPV6;
        default:
                return NFPROTO_UNSPEC;
        }
}

/* Map SKB connection state into the values used by flow definition. */
static u8 ovs_ct_get_state(enum ip_conntrack_info ctinfo)
{
        u8 ct_state = OVS_CS_F_TRACKED;

        switch (ctinfo) {
        case IP_CT_ESTABLISHED_REPLY:
        case IP_CT_RELATED_REPLY:
                ct_state |= OVS_CS_F_REPLY_DIR;
                break;
        default:
                break;
        }

        switch (ctinfo) {
        case IP_CT_ESTABLISHED:
        case IP_CT_ESTABLISHED_REPLY:
                ct_state |= OVS_CS_F_ESTABLISHED;
                break;
        case IP_CT_RELATED:
        case IP_CT_RELATED_REPLY:
                ct_state |= OVS_CS_F_RELATED;
                break;
        case IP_CT_NEW:
                ct_state |= OVS_CS_F_NEW;
                break;
        default:
                break;
        }

        return ct_state;
}

static u32 ovs_ct_get_mark(const struct nf_conn *ct)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
        return ct ? ct->mark : 0;
#else
        return 0;
#endif
}

/* Guard against conntrack labels max size shrinking below 128 bits. */
#if NF_CT_LABELS_MAX_SIZE < 16
#error NF_CT_LABELS_MAX_SIZE must be at least 16 bytes
#endif

static void ovs_ct_get_labels(const struct nf_conn *ct,
                              struct ovs_key_ct_labels *labels)
{
        struct nf_conn_labels *cl = ct ? nf_ct_labels_find(ct) : NULL;

        if (cl)
                memcpy(labels, cl->bits, OVS_CT_LABELS_LEN);
        else
                memset(labels, 0, OVS_CT_LABELS_LEN);
}

static void __ovs_ct_update_key_orig_tp(struct sw_flow_key *key,
                                        const struct nf_conntrack_tuple *orig,
                                        u8 icmp_proto)
{
        key->ct_orig_proto = orig->dst.protonum;
        if (orig->dst.protonum == icmp_proto) {
                key->ct.orig_tp.src = htons(orig->dst.u.icmp.type);
                key->ct.orig_tp.dst = htons(orig->dst.u.icmp.code);
        } else {
                key->ct.orig_tp.src = orig->src.u.all;
                key->ct.orig_tp.dst = orig->dst.u.all;
        }
}

static void __ovs_ct_update_key(struct sw_flow_key *key, u8 state,
                                const struct nf_conntrack_zone *zone,
                                const struct nf_conn *ct)
{
        key->ct_state = state;
        key->ct_zone = zone->id;
        key->ct.mark = ovs_ct_get_mark(ct);
        ovs_ct_get_labels(ct, &key->ct.labels);

        if (ct) {
                const struct nf_conntrack_tuple *orig;

                /* Use the master if we have one. */
                if (ct->master)
                        ct = ct->master;
                orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;

                /* IP version must match with the master connection. */
                if (key->eth.type == htons(ETH_P_IP) &&
                    nf_ct_l3num(ct) == NFPROTO_IPV4) {
                        key->ipv4.ct_orig.src = orig->src.u3.ip;
                        key->ipv4.ct_orig.dst = orig->dst.u3.ip;
                        __ovs_ct_update_key_orig_tp(key, orig, IPPROTO_ICMP);
                        return;
                } else if (key->eth.type == htons(ETH_P_IPV6) &&
                           !sw_flow_key_is_nd(key) &&
                           nf_ct_l3num(ct) == NFPROTO_IPV6) {
                        key->ipv6.ct_orig.src = orig->src.u3.in6;
                        key->ipv6.ct_orig.dst = orig->dst.u3.in6;
                        __ovs_ct_update_key_orig_tp(key, orig, NEXTHDR_ICMP);
                        return;
                }
        }
        /* Clear 'ct_orig_proto' to mark the non-existence of conntrack
         * original direction key fields.
         */
        key->ct_orig_proto = 0;
}

/* 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,
                              bool keep_nat_flags)
{
        const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
        enum ip_conntrack_info ctinfo;
        struct nf_conn *ct;
        u8 state = 0;

        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;
                if (info)
                        zone = &info->zone;
        }
        __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, false);
}

#define IN6_ADDR_INITIALIZER(ADDR) \
        { (ADDR).s6_addr32[0], (ADDR).s6_addr32[1], \
          (ADDR).s6_addr32[2], (ADDR).s6_addr32[3] }

int ovs_ct_put_key(const struct sw_flow_key *swkey,
                   const struct sw_flow_key *output, struct sk_buff *skb)
{
        if (nla_put_u32(skb, OVS_KEY_ATTR_CT_STATE, output->ct_state))
                return -EMSGSIZE;

        if (IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) &&
            nla_put_u16(skb, OVS_KEY_ATTR_CT_ZONE, output->ct_zone))
                return -EMSGSIZE;

        if (IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) &&
            nla_put_u32(skb, OVS_KEY_ATTR_CT_MARK, output->ct.mark))
                return -EMSGSIZE;

        if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) &&
            nla_put(skb, OVS_KEY_ATTR_CT_LABELS, sizeof(output->ct.labels),
                    &output->ct.labels))
                return -EMSGSIZE;

        if (swkey->ct_orig_proto) {
                if (swkey->eth.type == htons(ETH_P_IP)) {
                        struct ovs_key_ct_tuple_ipv4 orig = {
                                output->ipv4.ct_orig.src,
                                output->ipv4.ct_orig.dst,
                                output->ct.orig_tp.src,
                                output->ct.orig_tp.dst,
                                output->ct_orig_proto,
                        };
                        if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV4,
                                    sizeof(orig), &orig))
                                return -EMSGSIZE;
                } else if (swkey->eth.type == htons(ETH_P_IPV6)) {
                        struct ovs_key_ct_tuple_ipv6 orig = {
                                IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.src),
                                IN6_ADDR_INITIALIZER(output->ipv6.ct_orig.dst),
                                output->ct.orig_tp.src,
                                output->ct.orig_tp.dst,
                                output->ct_orig_proto,
                        };
                        if (nla_put(skb, OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV6,
                                    sizeof(orig), &orig))
                                return -EMSGSIZE;
                }
        }

        return 0;
}

static int ovs_ct_set_mark(struct nf_conn *ct, struct sw_flow_key *key,
                           u32 ct_mark, u32 mask)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
        u32 new_mark;

        new_mark = ct_mark | (ct->mark & ~(mask));
        if (ct->mark != new_mark) {
                ct->mark = new_mark;
                if (nf_ct_is_confirmed(ct))
                        nf_conntrack_event_cache(IPCT_MARK, ct);
                key->ct.mark = new_mark;
        }

        return 0;
#else
        return -ENOTSUPP;
#endif
}

static struct nf_conn_labels *ovs_ct_get_conn_labels(struct nf_conn *ct)
{
        struct nf_conn_labels *cl;

        cl = nf_ct_labels_find(ct);
        if (!cl) {
                nf_ct_labels_ext_add(ct);
                cl = nf_ct_labels_find(ct);
        }

        return cl;
}

/* Initialize labels for a new, yet to be committed conntrack entry.  Note that
 * since the new connection is not yet confirmed, and thus no-one else has
 * access to it's labels, we simply write them over.
 */
static int ovs_ct_init_labels(struct nf_conn *ct, struct sw_flow_key *key,
                              const struct ovs_key_ct_labels *labels,
                              const struct ovs_key_ct_labels *mask)
{
        struct nf_conn_labels *cl, *master_cl;
        bool have_mask = labels_nonzero(mask);

        /* Inherit master's labels to the related connection? */
        master_cl = ct->master ? nf_ct_labels_find(ct->master) : NULL;

        if (!master_cl && !have_mask)
                return 0;   /* Nothing to do. */

        cl = ovs_ct_get_conn_labels(ct);
        if (!cl)
                return -ENOSPC;

        /* Inherit the master's labels, if any. */
        if (master_cl)
                *cl = *master_cl;

        if (have_mask) {
                u32 *dst = (u32 *)cl->bits;
                int i;

                for (i = 0; i < OVS_CT_LABELS_LEN_32; i++)
                        dst[i] = (dst[i] & ~mask->ct_labels_32[i]) |
                                (labels->ct_labels_32[i]
                                 & mask->ct_labels_32[i]);
        }

        /* Labels are included in the IPCTNL_MSG_CT_NEW event only if the
         * IPCT_LABEL bit is set in the event cache.
         */
        nf_conntrack_event_cache(IPCT_LABEL, ct);

        memcpy(&key->ct.labels, cl->bits, OVS_CT_LABELS_LEN);

        return 0;
}

static int ovs_ct_set_labels(struct nf_conn *ct, struct sw_flow_key *key,
                             const struct ovs_key_ct_labels *labels,
                             const struct ovs_key_ct_labels *mask)
{
        struct nf_conn_labels *cl;
        int err;

        cl = ovs_ct_get_conn_labels(ct);
        if (!cl)
                return -ENOSPC;

        err = nf_connlabels_replace(ct, labels->ct_labels_32,
                                    mask->ct_labels_32,
                                    OVS_CT_LABELS_LEN_32);
        if (err)
                return err;

        memcpy(&key->ct.labels, cl->bits, OVS_CT_LABELS_LEN);

        return 0;
}

/* 'skb' should already be pulled to nh_ofs. */
static int ovs_ct_helper(struct sk_buff *skb, u16 proto)
{
        const struct nf_conntrack_helper *helper;
        const struct nf_conn_help *help;
        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)
                return NF_ACCEPT;

        help = nfct_help(ct);
        if (!help)
                return NF_ACCEPT;

        helper = rcu_dereference(help->helper);
        if (!helper)
                return NF_ACCEPT;

        switch (proto) {
        case NFPROTO_IPV4:
                protoff = ip_hdrlen(skb);
                break;
        case NFPROTO_IPV6: {
                u8 nexthdr = ipv6_hdr(skb)->nexthdr;
                __be16 frag_off;
                int ofs;

                ofs = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
                                       &frag_off);
                if (ofs < 0 || (frag_off & htons(~0x7)) != 0) {
                        pr_debug("proto header not found\n");
                        return NF_ACCEPT;
                }
                protoff = ofs;
                break;
        }
        default:
                WARN_ONCE(1, "helper invoked on non-IP family!");
                return NF_DROP;
        }

        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
 * value if 'skb' is freed.
 */
static int handle_fragments(struct net *net, struct sw_flow_key *key,
                            u16 zone, struct sk_buff *skb)
{
        struct ovs_skb_cb ovs_cb = *OVS_CB(skb);
        int err;

        if (key->eth.type == htons(ETH_P_IP)) {
                enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone;

                memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
                err = ip_defrag(net, skb, user);
                if (err)
                        return err;

                ovs_cb.mru = IPCB(skb)->frag_max_size;
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
        } else if (key->eth.type == htons(ETH_P_IPV6)) {
                enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;

                memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
                err = nf_ct_frag6_gather(net, skb, user);
                if (err) {
                        if (err != -EINPROGRESS)
                                kfree_skb(skb);
                        return err;
                }

                key->ip.proto = ipv6_hdr(skb)->nexthdr;
                ovs_cb.mru = IP6CB(skb)->frag_max_size;
#endif
        } else {
                kfree_skb(skb);
                return -EPFNOSUPPORT;
        }

        key->ip.frag = OVS_FRAG_TYPE_NONE;
        skb_clear_hash(skb);
        skb->ignore_df = 1;
        *OVS_CB(skb) = ovs_cb;

        return 0;
}

static struct nf_conntrack_expect *
ovs_ct_expect_find(struct net *net, const struct nf_conntrack_zone *zone,
                   u16 proto, const struct sk_buff *skb)
{
        struct nf_conntrack_tuple tuple;
        struct nf_conntrack_expect *exp;

        if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), proto, net, &tuple))
                return NULL;

        exp = __nf_ct_expect_find(net, zone, &tuple);
        if (exp) {
                struct nf_conntrack_tuple_hash *h;

                /* Delete existing conntrack entry, if it clashes with the
                 * expectation.  This can happen since conntrack ALGs do not
                 * check for clashes between (new) expectations and existing
                 * conntrack entries.  nf_conntrack_in() will check the
                 * expectations only if a conntrack entry can not be found,
                 * which can lead to OVS finding the expectation (here) in the
                 * init direction, but which will not be removed by the
                 * nf_conntrack_in() call, if a matching conntrack entry is
                 * found instead.  In this case all init direction packets
                 * would be reported as new related packets, while reply
                 * direction packets would be reported as un-related
                 * established packets.
                 */
                h = nf_conntrack_find_get(net, zone, &tuple);
                if (h) {
                        struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);

                        nf_ct_delete(ct, 0, 0);
                        nf_conntrack_put(&ct->ct_general);
                }
        }

        return exp;
}

/* 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 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, bool natted)
{
        struct nf_conntrack_l3proto *l3proto;
        struct nf_conntrack_l4proto *l4proto;
        struct nf_conntrack_tuple tuple;
        struct nf_conntrack_tuple_hash *h;
        struct nf_conn *ct;
        unsigned int dataoff;
        u8 protonum;

        l3proto = __nf_ct_l3proto_find(l3num);
        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 (!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;
        }

        /* Must invert the tuple if skb has been transformed by NAT. */
        if (natted) {
                struct nf_conntrack_tuple inverse;

                if (!nf_ct_invert_tuple(&inverse, &tuple, l3proto, l4proto)) {
                        pr_debug("ovs_ct_find_existing: Inversion failed!\n");
                        return NULL;
                }
                tuple = inverse;
        }

        /* 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);

        /* Inverted packet tuple matches the reverse direction conntrack tuple,
         * select the other tuplehash to get the right 'ctinfo' bits for this
         * packet.
         */
        if (natted)
                h = &ct->tuplehash[!h->tuple.dst.dir];

        nf_ct_set(skb, ct, ovs_ct_get_info(h));
        return ct;
}

/* Determine whether skb->_nfct is equal to the result of conntrack lookup. */
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,
                                          !!(key->ct_state
                                             & OVS_CS_F_NAT_MASK));
                if (ct)
                        nf_ct_get(skb, &ctinfo);
        }
        if (!ct)
                return false;
        if (!net_eq(net, read_pnet(&ct->ct_net)))
                return false;
        if (!nf_ct_zone_equal_any(info->ct, nf_ct_zone(ct)))
                return false;
        if (info->helper) {
                struct nf_conn_help *help;

                help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
                if (help && rcu_access_pointer(help->helper) != info->helper)
                        return false;
        }
        /* Force conntrack entry direction to the current packet? */
        if (info->force && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
                /* Delete the conntrack entry if confirmed, else just release
                 * the reference.
                 */
                if (nf_ct_is_confirmed(ct))
                        nf_ct_delete(ct, 0, 0);

                nf_conntrack_put(&ct->ct_general);
                nf_ct_set(skb, NULL, 0);
                return false;
        }

        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_rcsum(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 (IS_ENABLED(CONFIG_NF_NAT_IPV4) &&
                    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;
                } else if (IS_ENABLED(CONFIG_NF_NAT_IPV6) &&
                           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;
                        }
                }
                /* 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);
        skb_postpush_rcsum(skb, skb->data, 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;

        /* 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 new expected connections (IP_CT_RELATED) are NATted only
         * when committing.
         */
        if (info->nat & OVS_CT_NAT && ctinfo != IP_CT_NEW &&
            ct->status & IPS_NAT_MASK &&
            (ctinfo != IP_CT_RELATED || 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)
{
        /* If we are recirculating packets to match on conntrack fields and
         * committing with a separate conntrack action,  then we don't need to
         * actually run the packet through conntrack twice unless it's for a
         * different zone.
         */
        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) {
                        if (skb_nfct(skb))
                                nf_conntrack_put(skb_nfct(skb));
                        nf_conntrack_get(&tmpl->ct_general);
                        nf_ct_set(skb, tmpl, IP_CT_NEW);
                }

                err = nf_conntrack_in(net, info->family,
                                      NF_INET_PRE_ROUTING, skb);
                if (err != NF_ACCEPT)
                        return -ENOENT;

                /* 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;
                }

                /* Userspace may decide to perform a ct lookup without a helper
                 * specified followed by a (recirculate and) commit with one.
                 * Therefore, for unconfirmed connections which we will commit,
                 * we need to attach the helper here.
                 */
                if (!nf_ct_is_confirmed(ct) && info->commit &&
                    info->helper && !nfct_help(ct)) {
                        int err = __nf_ct_try_assign_helper(ct, info->ct,
                                                            GFP_ATOMIC);
                        if (err)
                                return err;
                }

                /* 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;
}

/* Lookup connection and read fields into key. */
static int ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
                         const struct ovs_conntrack_info *info,
                         struct sk_buff *skb)
{
        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 {
                struct nf_conn *ct;
                int err;

                err = __ovs_ct_lookup(net, key, info, skb);
                if (err)
                        return err;

                ct = (struct nf_conn *)skb_nfct(skb);
                if (ct)
                        nf_ct_deliver_cached_events(ct);
        }

        return 0;
}

static bool labels_nonzero(const struct ovs_key_ct_labels *labels)
{
        size_t i;

        for (i = 0; i < OVS_CT_LABELS_LEN_32; i++)
                if (labels->ct_labels_32[i])
                        return true;

        return false;
}

/* Lookup connection and confirm if unconfirmed. */
static int ovs_ct_commit(struct net *net, struct sw_flow_key *key,
                         const struct ovs_conntrack_info *info,
                         struct sk_buff *skb)
{
        enum ip_conntrack_info ctinfo;
        struct nf_conn *ct;
        int err;

        err = __ovs_ct_lookup(net, key, info, skb);
        if (err)
                return err;

        /* The connection could be invalid, in which case this is a no-op.*/
        ct = nf_ct_get(skb, &ctinfo);
        if (!ct)
                return 0;

        /* Set the conntrack event mask if given.  NEW and DELETE events have
         * their own groups, but the NFNLGRP_CONNTRACK_UPDATE group listener
         * typically would receive many kinds of updates.  Setting the event
         * mask allows those events to be filtered.  The set event mask will
         * remain in effect for the lifetime of the connection unless changed
         * by a further CT action with both the commit flag and the eventmask
         * option. */
        if (info->have_eventmask) {
                struct nf_conntrack_ecache *cache = nf_ct_ecache_find(ct);

                if (cache)
                        cache->ctmask = info->eventmask;
        }

        /* Apply changes before confirming the connection so that the initial
         * conntrack NEW netlink event carries the values given in the CT
         * action.
         */
        if (info->mark.mask) {
                err = ovs_ct_set_mark(ct, key, info->mark.value,
                                      info->mark.mask);
                if (err)
                        return err;
        }
        if (!nf_ct_is_confirmed(ct)) {
                err = ovs_ct_init_labels(ct, key, &info->labels.value,
                                         &info->labels.mask);
                if (err)
                        return err;
        } else if (labels_nonzero(&info->labels.mask)) {
                err = ovs_ct_set_labels(ct, key, &info->labels.value,
                                        &info->labels.mask);
                if (err)
                        return err;
        }
        /* This will take care of sending queued events even if the connection
         * is already confirmed.
         */
        if (nf_conntrack_confirm(skb) != NF_ACCEPT)
                return -EINVAL;

        return 0;
}

/* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero
 * value if 'skb' is freed.
 */
int ovs_ct_execute(struct net *net, struct sk_buff *skb,
                   struct sw_flow_key *key,
                   const struct ovs_conntrack_info *info)
{
        int nh_ofs;
        int err;

        /* The conntrack module expects to be working at L3. */
        nh_ofs = skb_network_offset(skb);
        skb_pull_rcsum(skb, nh_ofs);

        if (key->ip.frag != OVS_FRAG_TYPE_NONE) {
                err = handle_fragments(net, key, info->zone.id, skb);
                if (err)
                        return err;
        }

        if (info->commit)
                err = ovs_ct_commit(net, key, info, skb);
        else
                err = ovs_ct_lookup(net, key, info, skb);

        skb_push(skb, nh_ofs);
        skb_postpush_rcsum(skb, skb->data, nh_ofs);
        if (err)
                kfree_skb(skb);
        return err;
}

static int ovs_ct_add_helper(struct ovs_conntrack_info *info, const char *name,
                             const struct sw_flow_key *key, bool log)
{
        struct nf_conntrack_helper *helper;
        struct nf_conn_help *help;

        helper = nf_conntrack_helper_try_module_get(name, info->family,
                                                    key->ip.proto);
        if (!helper) {
                OVS_NLERR(log, "Unknown helper \"%s\"", name);
                return -EINVAL;
        }

        help = nf_ct_helper_ext_add(info->ct, helper, GFP_KERNEL);
        if (!help) {
                nf_conntrack_helper_put(helper);
                return -ENOMEM;
        }

        rcu_assign_pointer(help->helper, helper);
        info->helper = helper;
        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,
                                   sizeof(info->range.min_addr));
                        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_FORCE_COMMIT]      = { .minlen = 0, .maxlen = 0 },
        [OVS_CT_ATTR_ZONE]      = { .minlen = sizeof(u16),
                                    .maxlen = sizeof(u16) },
        [OVS_CT_ATTR_MARK]      = { .minlen = sizeof(struct md_mark),
                                    .maxlen = sizeof(struct md_mark) },
        [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 },
#ifdef CONFIG_NF_NAT_NEEDED
        /* NAT length is checked when parsing the nested attributes. */
        [OVS_CT_ATTR_NAT]       = { .minlen = 0, .maxlen = INT_MAX },
#endif
        [OVS_CT_ATTR_EVENTMASK] = { .minlen = sizeof(u32),
                                    .maxlen = sizeof(u32) },
};

static int parse_ct(const struct nlattr *attr, struct ovs_conntrack_info *info,
                    const char **helper, bool log)
{
        struct nlattr *a;
        int rem;

        nla_for_each_nested(a, attr, rem) {
                int type = nla_type(a);
                int maxlen = ovs_ct_attr_lens[type].maxlen;
                int minlen = ovs_ct_attr_lens[type].minlen;

                if (type > OVS_CT_ATTR_MAX) {
                        OVS_NLERR(log,
                                  "Unknown conntrack attr (type=%d, max=%d)",
                                  type, OVS_CT_ATTR_MAX);
                        return -EINVAL;
                }
                if (nla_len(a) < minlen || nla_len(a) > maxlen) {
                        OVS_NLERR(log,
                                  "Conntrack attr type has unexpected length (type=%d, length=%d, expected=%d)",
                                  type, nla_len(a), maxlen);
                        return -EINVAL;
                }

                switch (type) {
                case OVS_CT_ATTR_FORCE_COMMIT:
                        info->force = true;
                        /* fall through. */
                case OVS_CT_ATTR_COMMIT:
                        info->commit = true;
                        break;
#ifdef CONFIG_NF_CONNTRACK_ZONES
                case OVS_CT_ATTR_ZONE:
                        info->zone.id = nla_get_u16(a);
                        break;
#endif
#ifdef CONFIG_NF_CONNTRACK_MARK
                case OVS_CT_ATTR_MARK: {
                        struct md_mark *mark = nla_data(a);

                        if (!mark->mask) {
                                OVS_NLERR(log, "ct_mark mask cannot be 0");
                                return -EINVAL;
                        }
                        info->mark = *mark;
                        break;
                }
#endif
#ifdef CONFIG_NF_CONNTRACK_LABELS
                case OVS_CT_ATTR_LABELS: {
                        struct md_labels *labels = nla_data(a);

                        if (!labels_nonzero(&labels->mask)) {
                                OVS_NLERR(log, "ct_labels mask cannot be 0");
                                return -EINVAL;
                        }
                        info->labels = *labels;
                        break;
                }
#endif
                case OVS_CT_ATTR_HELPER:
                        *helper = nla_data(a);
                        if (!memchr(*helper, '\0', nla_len(a))) {
                                OVS_NLERR(log, "Invalid conntrack helper");
                                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
                case OVS_CT_ATTR_EVENTMASK:
                        info->have_eventmask = true;
                        info->eventmask = nla_get_u32(a);
                        break;

                default:
                        OVS_NLERR(log, "Unknown conntrack attr (%d)",
                                  type);
                        return -EINVAL;
                }
        }

#ifdef CONFIG_NF_CONNTRACK_MARK
        if (!info->commit && info->mark.mask) {
                OVS_NLERR(log,
                          "Setting conntrack mark requires 'commit' flag.");
                return -EINVAL;
        }
#endif
#ifdef CONFIG_NF_CONNTRACK_LABELS
        if (!info->commit && labels_nonzero(&info->labels.mask)) {
                OVS_NLERR(log,
                          "Setting conntrack labels requires 'commit' flag.");
                return -EINVAL;
        }
#endif
        if (rem > 0) {
                OVS_NLERR(log, "Conntrack attr has %d unknown bytes", rem);
                return -EINVAL;
        }

        return 0;
}

bool ovs_ct_verify(struct net *net, enum ovs_key_attr attr)
{
        if (attr == OVS_KEY_ATTR_CT_STATE)
                return true;
        if (IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) &&
            attr == OVS_KEY_ATTR_CT_ZONE)
                return true;
        if (IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) &&
            attr == OVS_KEY_ATTR_CT_MARK)
                return true;
        if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) &&
            attr == OVS_KEY_ATTR_CT_LABELS) {
                struct ovs_net *ovs_net = net_generic(net, ovs_net_id);

                return ovs_net->xt_label;
        }

        return false;
}

int ovs_ct_copy_action(struct net *net, const struct nlattr *attr,
                       const struct sw_flow_key *key,
                       struct sw_flow_actions **sfa,  bool log)
{
        struct ovs_conntrack_info ct_info;
        const char *helper = NULL;
        u16 family;
        int err;

        family = key_to_nfproto(key);
        if (family == NFPROTO_UNSPEC) {
                OVS_NLERR(log, "ct family unspecified");
                return -EINVAL;
        }

        memset(&ct_info, 0, sizeof(ct_info));
        ct_info.family = family;

        nf_ct_zone_init(&ct_info.zone, NF_CT_DEFAULT_ZONE_ID,
                        NF_CT_DEFAULT_ZONE_DIR, 0);

        err = parse_ct(attr, &ct_info, &helper, log);
        if (err)
                return err;

        /* Set up template for tracking connections in specific zones. */
        ct_info.ct = nf_ct_tmpl_alloc(net, &ct_info.zone, GFP_KERNEL);
        if (!ct_info.ct) {
                OVS_NLERR(log, "Failed to allocate conntrack template");
                return -ENOMEM;
        }

        __set_bit(IPS_CONFIRMED_BIT, &ct_info.ct->status);
        nf_conntrack_get(&ct_info.ct->ct_general);

        if (helper) {
                err = ovs_ct_add_helper(&ct_info, helper, key, log);
                if (err)
                        goto err_free_ct;
        }

        err = ovs_nla_add_action(sfa, OVS_ACTION_ATTR_CT, &ct_info,
                                 sizeof(ct_info), log);
        if (err)
                goto err_free_ct;

        return 0;
err_free_ct:
        __ovs_ct_free_action(&ct_info);
        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 (IS_ENABLED(CONFIG_NF_NAT_IPV4) &&
                    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;
                } else if (IS_ENABLED(CONFIG_NF_NAT_IPV6) &&
                           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;
                } 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)
{
        struct nlattr *start;

        start = nla_nest_start(skb, OVS_ACTION_ATTR_CT);
        if (!start)
                return -EMSGSIZE;

        if (ct_info->commit && nla_put_flag(skb, ct_info->force
                                            ? OVS_CT_ATTR_FORCE_COMMIT
                                            : OVS_CT_ATTR_COMMIT))
                return -EMSGSIZE;
        if (IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) &&
            nla_put_u16(skb, OVS_CT_ATTR_ZONE, ct_info->zone.id))
                return -EMSGSIZE;
        if (IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) && ct_info->mark.mask &&
            nla_put(skb, OVS_CT_ATTR_MARK, sizeof(ct_info->mark),
                    &ct_info->mark))
                return -EMSGSIZE;
        if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) &&
            labels_nonzero(&ct_info->labels.mask) &&
            nla_put(skb, OVS_CT_ATTR_LABELS, sizeof(ct_info->labels),
                    &ct_info->labels))
                return -EMSGSIZE;
        if (ct_info->helper) {
                if (nla_put_string(skb, OVS_CT_ATTR_HELPER,
                                   ct_info->helper->name))
                        return -EMSGSIZE;
        }
        if (ct_info->have_eventmask &&
            nla_put_u32(skb, OVS_CT_ATTR_EVENTMASK, ct_info->eventmask))
                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;
}

void ovs_ct_free_action(const struct nlattr *a)
{
        struct ovs_conntrack_info *ct_info = nla_data(a);

        __ovs_ct_free_action(ct_info);
}

static void __ovs_ct_free_action(struct ovs_conntrack_info *ct_info)
{
        if (ct_info->helper)
                nf_conntrack_helper_put(ct_info->helper);
        if (ct_info->ct)
                nf_ct_tmpl_free(ct_info->ct);
}

void ovs_ct_init(struct net *net)
{
        unsigned int n_bits = sizeof(struct ovs_key_ct_labels) * BITS_PER_BYTE;
        struct ovs_net *ovs_net = net_generic(net, ovs_net_id);

        if (nf_connlabels_get(net, n_bits - 1)) {
                ovs_net->xt_label = false;
                OVS_NLERR(true, "Failed to set connlabel length");
        } else {
                ovs_net->xt_label = true;
        }
}

void ovs_ct_exit(struct net *net)
{
        struct ovs_net *ovs_net = net_generic(net, ovs_net_id);

        if (ovs_net->xt_label)
                nf_connlabels_put(net);
}