root/net/ipv4/ip_tunnel_core.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2013 Nicira, Inc.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/in.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/in6.h>
#include <linux/inetdevice.h>
#include <linux/netfilter_ipv4.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/static_key.h>

#include <net/ip.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <net/ip_tunnels.h>
#include <net/ip6_tunnel.h>
#include <net/ip6_checksum.h>
#include <net/arp.h>
#include <net/checksum.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/rtnetlink.h>
#include <net/dst_metadata.h>
#include <net/geneve.h>
#include <net/vxlan.h>
#include <net/erspan.h>

const struct ip_tunnel_encap_ops __rcu *
                iptun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;
EXPORT_SYMBOL(iptun_encaps);

const struct ip6_tnl_encap_ops __rcu *
                ip6tun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;
EXPORT_SYMBOL(ip6tun_encaps);

void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
                   __be32 src, __be32 dst, __u8 proto,
                   __u8 tos, __u8 ttl, __be16 df, bool xnet,
                   u16 ipcb_flags)
{
        int pkt_len = skb->len - skb_inner_network_offset(skb);
        struct net *net = dev_net(rt->dst.dev);
        struct net_device *dev = skb->dev;
        struct iphdr *iph;
        int err;

        if (unlikely(dev_recursion_level() > IP_TUNNEL_RECURSION_LIMIT)) {
                if (dev) {
                        net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n",
                                             dev->name);
                        DEV_STATS_INC(dev, tx_errors);
                }
                ip_rt_put(rt);
                kfree_skb(skb);
                return;
        }

        dev_xmit_recursion_inc();

        skb_scrub_packet(skb, xnet);

        skb_clear_hash_if_not_l4(skb);
        skb_dst_set(skb, &rt->dst);
        memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
        IPCB(skb)->flags = ipcb_flags;

        /* Push down and install the IP header. */
        skb_push(skb, sizeof(struct iphdr));
        skb_reset_network_header(skb);

        iph = ip_hdr(skb);

        iph->version    =       4;
        iph->ihl        =       sizeof(struct iphdr) >> 2;
        iph->frag_off   =       ip_mtu_locked(&rt->dst) ? 0 : df;
        iph->protocol   =       proto;
        iph->tos        =       tos;
        iph->daddr      =       dst;
        iph->saddr      =       src;
        iph->ttl        =       ttl;
        __ip_select_ident(net, iph, skb_shinfo(skb)->gso_segs ?: 1);

        err = ip_local_out(net, sk, skb);

        if (dev) {
                if (unlikely(net_xmit_eval(err)))
                        pkt_len = 0;
                iptunnel_xmit_stats(dev, pkt_len);
        }

        dev_xmit_recursion_dec();
}
EXPORT_SYMBOL_GPL(iptunnel_xmit);

int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len,
                           __be16 inner_proto, bool raw_proto, bool xnet)
{
        if (unlikely(!pskb_may_pull(skb, hdr_len)))
                return -ENOMEM;

        skb_pull_rcsum(skb, hdr_len);

        if (!raw_proto && inner_proto == htons(ETH_P_TEB)) {
                struct ethhdr *eh;

                if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
                        return -ENOMEM;

                eh = (struct ethhdr *)skb->data;
                if (likely(eth_proto_is_802_3(eh->h_proto)))
                        skb->protocol = eh->h_proto;
                else
                        skb->protocol = htons(ETH_P_802_2);

        } else {
                skb->protocol = inner_proto;
        }

        skb_clear_hash_if_not_l4(skb);
        __vlan_hwaccel_clear_tag(skb);
        skb_set_queue_mapping(skb, 0);
        skb_scrub_packet(skb, xnet);

        return iptunnel_pull_offloads(skb);
}
EXPORT_SYMBOL_GPL(__iptunnel_pull_header);

struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md,
                                             gfp_t flags)
{
        IP_TUNNEL_DECLARE_FLAGS(tun_flags) = { };
        struct metadata_dst *res;
        struct ip_tunnel_info *dst, *src;

        if (!md || md->type != METADATA_IP_TUNNEL ||
            md->u.tun_info.mode & IP_TUNNEL_INFO_TX)
                return NULL;

        src = &md->u.tun_info;
        res = metadata_dst_alloc(src->options_len, METADATA_IP_TUNNEL, flags);
        if (!res)
                return NULL;

        dst = &res->u.tun_info;
        dst->key.tun_id = src->key.tun_id;
        if (src->mode & IP_TUNNEL_INFO_IPV6)
                memcpy(&dst->key.u.ipv6.dst, &src->key.u.ipv6.src,
                       sizeof(struct in6_addr));
        else
                dst->key.u.ipv4.dst = src->key.u.ipv4.src;
        ip_tunnel_flags_copy(dst->key.tun_flags, src->key.tun_flags);
        dst->mode = src->mode | IP_TUNNEL_INFO_TX;
        ip_tunnel_info_opts_set(dst, ip_tunnel_info_opts(src),
                                src->options_len, tun_flags);

        return res;
}
EXPORT_SYMBOL_GPL(iptunnel_metadata_reply);

int iptunnel_handle_offloads(struct sk_buff *skb,
                             int gso_type_mask)
{
        int err;

        if (likely(!skb->encapsulation)) {
                skb_reset_inner_headers(skb);
                skb->encapsulation = 1;
        }

        if (skb_is_gso(skb)) {
                err = skb_header_unclone(skb, GFP_ATOMIC);
                if (unlikely(err))
                        return err;
                skb_shinfo(skb)->gso_type |= gso_type_mask;
                return 0;
        }

        if (skb->ip_summed != CHECKSUM_PARTIAL) {
                skb->ip_summed = CHECKSUM_NONE;
                /* We clear encapsulation here to prevent badly-written
                 * drivers potentially deciding to offload an inner checksum
                 * if we set CHECKSUM_PARTIAL on the outer header.
                 * This should go away when the drivers are all fixed.
                 */
                skb->encapsulation = 0;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(iptunnel_handle_offloads);

/**
 * iptunnel_pmtud_build_icmp() - Build ICMP error message for PMTUD
 * @skb:        Original packet with L2 header
 * @mtu:        MTU value for ICMP error
 *
 * Return: length on success, negative error code if message couldn't be built.
 */
static int iptunnel_pmtud_build_icmp(struct sk_buff *skb, int mtu)
{
        const struct iphdr *iph = ip_hdr(skb);
        struct icmphdr *icmph;
        struct iphdr *niph;
        struct ethhdr eh;
        int len, err;

        if (!pskb_may_pull(skb, ETH_HLEN + sizeof(struct iphdr)))
                return -EINVAL;

        if (skb_is_gso(skb))
                skb_gso_reset(skb);

        skb_copy_bits(skb, skb_mac_offset(skb), &eh, ETH_HLEN);
        pskb_pull(skb, ETH_HLEN);
        skb_reset_network_header(skb);

        err = pskb_trim(skb, 576 - sizeof(*niph) - sizeof(*icmph));
        if (err)
                return err;

        len = skb->len + sizeof(*icmph);
        err = skb_cow(skb, sizeof(*niph) + sizeof(*icmph) + ETH_HLEN);
        if (err)
                return err;

        icmph = skb_push(skb, sizeof(*icmph));
        *icmph = (struct icmphdr) {
                .type                   = ICMP_DEST_UNREACH,
                .code                   = ICMP_FRAG_NEEDED,
                .checksum               = 0,
                .un.frag.__unused       = 0,
                .un.frag.mtu            = htons(mtu),
        };
        icmph->checksum = csum_fold(skb_checksum(skb, 0, len, 0));
        skb_reset_transport_header(skb);

        niph = skb_push(skb, sizeof(*niph));
        *niph = (struct iphdr) {
                .ihl                    = sizeof(*niph) / 4u,
                .version                = 4,
                .tos                    = 0,
                .tot_len                = htons(len + sizeof(*niph)),
                .id                     = 0,
                .frag_off               = htons(IP_DF),
                .ttl                    = iph->ttl,
                .protocol               = IPPROTO_ICMP,
                .saddr                  = iph->daddr,
                .daddr                  = iph->saddr,
        };
        ip_send_check(niph);
        skb_reset_network_header(skb);

        skb->ip_summed = CHECKSUM_NONE;

        eth_header(skb, skb->dev, ntohs(eh.h_proto), eh.h_source, eh.h_dest, 0);
        skb_reset_mac_header(skb);

        return skb->len;
}

/**
 * iptunnel_pmtud_check_icmp() - Trigger ICMP reply if needed and allowed
 * @skb:        Buffer being sent by encapsulation, L2 headers expected
 * @mtu:        Network MTU for path
 *
 * Return: 0 for no ICMP reply, length if built, negative value on error.
 */
static int iptunnel_pmtud_check_icmp(struct sk_buff *skb, int mtu)
{
        const struct icmphdr *icmph = icmp_hdr(skb);
        const struct iphdr *iph = ip_hdr(skb);

        if (mtu < 576 || iph->frag_off != htons(IP_DF))
                return 0;

        if (ipv4_is_lbcast(iph->daddr)  || ipv4_is_multicast(iph->daddr) ||
            ipv4_is_zeronet(iph->saddr) || ipv4_is_loopback(iph->saddr)  ||
            ipv4_is_lbcast(iph->saddr)  || ipv4_is_multicast(iph->saddr))
                return 0;

        if (iph->protocol == IPPROTO_ICMP && icmp_is_err(icmph->type))
                return 0;

        return iptunnel_pmtud_build_icmp(skb, mtu);
}

#if IS_ENABLED(CONFIG_IPV6)
/**
 * iptunnel_pmtud_build_icmpv6() - Build ICMPv6 error message for PMTUD
 * @skb:        Original packet with L2 header
 * @mtu:        MTU value for ICMPv6 error
 *
 * Return: length on success, negative error code if message couldn't be built.
 */
static int iptunnel_pmtud_build_icmpv6(struct sk_buff *skb, int mtu)
{
        const struct ipv6hdr *ip6h = ipv6_hdr(skb);
        struct icmp6hdr *icmp6h;
        struct ipv6hdr *nip6h;
        struct ethhdr eh;
        int len, err;
        __wsum csum;

        if (!pskb_may_pull(skb, ETH_HLEN + sizeof(struct ipv6hdr)))
                return -EINVAL;

        if (skb_is_gso(skb))
                skb_gso_reset(skb);

        skb_copy_bits(skb, skb_mac_offset(skb), &eh, ETH_HLEN);
        pskb_pull(skb, ETH_HLEN);
        skb_reset_network_header(skb);

        err = pskb_trim(skb, IPV6_MIN_MTU - sizeof(*nip6h) - sizeof(*icmp6h));
        if (err)
                return err;

        len = skb->len + sizeof(*icmp6h);
        err = skb_cow(skb, sizeof(*nip6h) + sizeof(*icmp6h) + ETH_HLEN);
        if (err)
                return err;

        icmp6h = skb_push(skb, sizeof(*icmp6h));
        *icmp6h = (struct icmp6hdr) {
                .icmp6_type             = ICMPV6_PKT_TOOBIG,
                .icmp6_code             = 0,
                .icmp6_cksum            = 0,
                .icmp6_mtu              = htonl(mtu),
        };
        skb_reset_transport_header(skb);

        nip6h = skb_push(skb, sizeof(*nip6h));
        *nip6h = (struct ipv6hdr) {
                .priority               = 0,
                .version                = 6,
                .flow_lbl               = { 0 },
                .payload_len            = htons(len),
                .nexthdr                = IPPROTO_ICMPV6,
                .hop_limit              = ip6h->hop_limit,
                .saddr                  = ip6h->daddr,
                .daddr                  = ip6h->saddr,
        };
        skb_reset_network_header(skb);

        csum = skb_checksum(skb, skb_transport_offset(skb), len, 0);
        icmp6h->icmp6_cksum = csum_ipv6_magic(&nip6h->saddr, &nip6h->daddr, len,
                                              IPPROTO_ICMPV6, csum);

        skb->ip_summed = CHECKSUM_NONE;

        eth_header(skb, skb->dev, ntohs(eh.h_proto), eh.h_source, eh.h_dest, 0);
        skb_reset_mac_header(skb);

        return skb->len;
}

/**
 * iptunnel_pmtud_check_icmpv6() - Trigger ICMPv6 reply if needed and allowed
 * @skb:        Buffer being sent by encapsulation, L2 headers expected
 * @mtu:        Network MTU for path
 *
 * Return: 0 for no ICMPv6 reply, length if built, negative value on error.
 */
static int iptunnel_pmtud_check_icmpv6(struct sk_buff *skb, int mtu)
{
        const struct ipv6hdr *ip6h = ipv6_hdr(skb);
        int stype = ipv6_addr_type(&ip6h->saddr);
        u8 proto = ip6h->nexthdr;
        __be16 frag_off;
        int offset;

        if (mtu < IPV6_MIN_MTU)
                return 0;

        if (stype == IPV6_ADDR_ANY || stype == IPV6_ADDR_MULTICAST ||
            stype == IPV6_ADDR_LOOPBACK)
                return 0;

        offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &proto,
                                  &frag_off);
        if (offset < 0 || (frag_off & htons(~0x7)))
                return 0;

        if (proto == IPPROTO_ICMPV6) {
                struct icmp6hdr *icmp6h;

                if (!pskb_may_pull(skb, skb_network_header(skb) +
                                        offset + 1 - skb->data))
                        return 0;

                icmp6h = (struct icmp6hdr *)(skb_network_header(skb) + offset);
                if (icmpv6_is_err(icmp6h->icmp6_type) ||
                    icmp6h->icmp6_type == NDISC_REDIRECT)
                        return 0;
        }

        return iptunnel_pmtud_build_icmpv6(skb, mtu);
}
#endif /* IS_ENABLED(CONFIG_IPV6) */

/**
 * skb_tunnel_check_pmtu() - Check, update PMTU and trigger ICMP reply as needed
 * @skb:        Buffer being sent by encapsulation, L2 headers expected
 * @encap_dst:  Destination for tunnel encapsulation (outer IP)
 * @headroom:   Encapsulation header size, bytes
 * @reply:      Build matching ICMP or ICMPv6 message as a result
 *
 * L2 tunnel implementations that can carry IP and can be directly bridged
 * (currently UDP tunnels) can't always rely on IP forwarding paths to handle
 * PMTU discovery. In the bridged case, ICMP or ICMPv6 messages need to be built
 * based on payload and sent back by the encapsulation itself.
 *
 * For routable interfaces, we just need to update the PMTU for the destination.
 *
 * Return: 0 if ICMP error not needed, length if built, negative value on error
 */
int skb_tunnel_check_pmtu(struct sk_buff *skb, struct dst_entry *encap_dst,
                          int headroom, bool reply)
{
        u32 mtu = dst_mtu(encap_dst) - headroom;

        if ((skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu)) ||
            (!skb_is_gso(skb) && (skb->len - skb_network_offset(skb)) <= mtu))
                return 0;

        skb_dst_update_pmtu_no_confirm(skb, mtu);

        if (!reply)
                return 0;

        if (skb->protocol == htons(ETH_P_IP))
                return iptunnel_pmtud_check_icmp(skb, mtu);

#if IS_ENABLED(CONFIG_IPV6)
        if (skb->protocol == htons(ETH_P_IPV6))
                return iptunnel_pmtud_check_icmpv6(skb, mtu);
#endif
        return 0;
}
EXPORT_SYMBOL(skb_tunnel_check_pmtu);

static const struct nla_policy ip_tun_policy[LWTUNNEL_IP_MAX + 1] = {
        [LWTUNNEL_IP_UNSPEC]    = { .strict_start_type = LWTUNNEL_IP_OPTS },
        [LWTUNNEL_IP_ID]        = { .type = NLA_U64 },
        [LWTUNNEL_IP_DST]       = { .type = NLA_U32 },
        [LWTUNNEL_IP_SRC]       = { .type = NLA_U32 },
        [LWTUNNEL_IP_TTL]       = { .type = NLA_U8 },
        [LWTUNNEL_IP_TOS]       = { .type = NLA_U8 },
        [LWTUNNEL_IP_FLAGS]     = { .type = NLA_U16 },
        [LWTUNNEL_IP_OPTS]      = { .type = NLA_NESTED },
};

static const struct nla_policy ip_opts_policy[LWTUNNEL_IP_OPTS_MAX + 1] = {
        [LWTUNNEL_IP_OPTS_GENEVE]       = { .type = NLA_NESTED },
        [LWTUNNEL_IP_OPTS_VXLAN]        = { .type = NLA_NESTED },
        [LWTUNNEL_IP_OPTS_ERSPAN]       = { .type = NLA_NESTED },
};

static const struct nla_policy
geneve_opt_policy[LWTUNNEL_IP_OPT_GENEVE_MAX + 1] = {
        [LWTUNNEL_IP_OPT_GENEVE_CLASS]  = { .type = NLA_U16 },
        [LWTUNNEL_IP_OPT_GENEVE_TYPE]   = { .type = NLA_U8 },
        [LWTUNNEL_IP_OPT_GENEVE_DATA]   = { .type = NLA_BINARY, .len = 127 },
};

static const struct nla_policy
vxlan_opt_policy[LWTUNNEL_IP_OPT_VXLAN_MAX + 1] = {
        [LWTUNNEL_IP_OPT_VXLAN_GBP]     = { .type = NLA_U32 },
};

static const struct nla_policy
erspan_opt_policy[LWTUNNEL_IP_OPT_ERSPAN_MAX + 1] = {
        [LWTUNNEL_IP_OPT_ERSPAN_VER]    = { .type = NLA_U8 },
        [LWTUNNEL_IP_OPT_ERSPAN_INDEX]  = { .type = NLA_U32 },
        [LWTUNNEL_IP_OPT_ERSPAN_DIR]    = { .type = NLA_U8 },
        [LWTUNNEL_IP_OPT_ERSPAN_HWID]   = { .type = NLA_U8 },
};

static int ip_tun_parse_opts_geneve(struct nlattr *attr,
                                    struct ip_tunnel_info *info, int opts_len,
                                    struct netlink_ext_ack *extack)
{
        struct nlattr *tb[LWTUNNEL_IP_OPT_GENEVE_MAX + 1];
        int data_len, err;

        err = nla_parse_nested(tb, LWTUNNEL_IP_OPT_GENEVE_MAX, attr,
                               geneve_opt_policy, extack);
        if (err)
                return err;

        if (!tb[LWTUNNEL_IP_OPT_GENEVE_CLASS] ||
            !tb[LWTUNNEL_IP_OPT_GENEVE_TYPE] ||
            !tb[LWTUNNEL_IP_OPT_GENEVE_DATA])
                return -EINVAL;

        attr = tb[LWTUNNEL_IP_OPT_GENEVE_DATA];
        data_len = nla_len(attr);
        if (data_len % 4)
                return -EINVAL;

        if (info) {
                struct geneve_opt *opt = ip_tunnel_info_opts(info) + opts_len;

                memcpy(opt->opt_data, nla_data(attr), data_len);
                opt->length = data_len / 4;
                attr = tb[LWTUNNEL_IP_OPT_GENEVE_CLASS];
                opt->opt_class = nla_get_be16(attr);
                attr = tb[LWTUNNEL_IP_OPT_GENEVE_TYPE];
                opt->type = nla_get_u8(attr);
                __set_bit(IP_TUNNEL_GENEVE_OPT_BIT, info->key.tun_flags);
        }

        return sizeof(struct geneve_opt) + data_len;
}

static int ip_tun_parse_opts_vxlan(struct nlattr *attr,
                                   struct ip_tunnel_info *info, int opts_len,
                                   struct netlink_ext_ack *extack)
{
        struct nlattr *tb[LWTUNNEL_IP_OPT_VXLAN_MAX + 1];
        int err;

        err = nla_parse_nested(tb, LWTUNNEL_IP_OPT_VXLAN_MAX, attr,
                               vxlan_opt_policy, extack);
        if (err)
                return err;

        if (!tb[LWTUNNEL_IP_OPT_VXLAN_GBP])
                return -EINVAL;

        if (info) {
                struct vxlan_metadata *md =
                        ip_tunnel_info_opts(info) + opts_len;

                attr = tb[LWTUNNEL_IP_OPT_VXLAN_GBP];
                md->gbp = nla_get_u32(attr);
                md->gbp &= VXLAN_GBP_MASK;
                __set_bit(IP_TUNNEL_VXLAN_OPT_BIT, info->key.tun_flags);
        }

        return sizeof(struct vxlan_metadata);
}

static int ip_tun_parse_opts_erspan(struct nlattr *attr,
                                    struct ip_tunnel_info *info, int opts_len,
                                    struct netlink_ext_ack *extack)
{
        struct nlattr *tb[LWTUNNEL_IP_OPT_ERSPAN_MAX + 1];
        int err;
        u8 ver;

        err = nla_parse_nested(tb, LWTUNNEL_IP_OPT_ERSPAN_MAX, attr,
                               erspan_opt_policy, extack);
        if (err)
                return err;

        if (!tb[LWTUNNEL_IP_OPT_ERSPAN_VER])
                return -EINVAL;

        ver = nla_get_u8(tb[LWTUNNEL_IP_OPT_ERSPAN_VER]);
        if (ver == 1) {
                if (!tb[LWTUNNEL_IP_OPT_ERSPAN_INDEX])
                        return -EINVAL;
        } else if (ver == 2) {
                if (!tb[LWTUNNEL_IP_OPT_ERSPAN_DIR] ||
                    !tb[LWTUNNEL_IP_OPT_ERSPAN_HWID])
                        return -EINVAL;
        } else {
                return -EINVAL;
        }

        if (info) {
                struct erspan_metadata *md =
                        ip_tunnel_info_opts(info) + opts_len;

                md->version = ver;
                if (ver == 1) {
                        attr = tb[LWTUNNEL_IP_OPT_ERSPAN_INDEX];
                        md->u.index = nla_get_be32(attr);
                } else {
                        attr = tb[LWTUNNEL_IP_OPT_ERSPAN_DIR];
                        md->u.md2.dir = nla_get_u8(attr);
                        attr = tb[LWTUNNEL_IP_OPT_ERSPAN_HWID];
                        set_hwid(&md->u.md2, nla_get_u8(attr));
                }

                __set_bit(IP_TUNNEL_ERSPAN_OPT_BIT, info->key.tun_flags);
        }

        return sizeof(struct erspan_metadata);
}

static int ip_tun_parse_opts(struct nlattr *attr, struct ip_tunnel_info *info,
                             struct netlink_ext_ack *extack)
{
        int err, rem, opt_len, opts_len = 0;
        struct nlattr *nla;
        u32 type = 0;

        if (!attr)
                return 0;

        err = nla_validate(nla_data(attr), nla_len(attr), LWTUNNEL_IP_OPTS_MAX,
                           ip_opts_policy, extack);
        if (err)
                return err;

        nla_for_each_attr(nla, nla_data(attr), nla_len(attr), rem) {
                switch (nla_type(nla)) {
                case LWTUNNEL_IP_OPTS_GENEVE:
                        if (type && type != IP_TUNNEL_GENEVE_OPT_BIT)
                                return -EINVAL;
                        opt_len = ip_tun_parse_opts_geneve(nla, info, opts_len,
                                                           extack);
                        if (opt_len < 0)
                                return opt_len;
                        opts_len += opt_len;
                        if (opts_len > IP_TUNNEL_OPTS_MAX)
                                return -EINVAL;
                        type = IP_TUNNEL_GENEVE_OPT_BIT;
                        break;
                case LWTUNNEL_IP_OPTS_VXLAN:
                        if (type)
                                return -EINVAL;
                        opt_len = ip_tun_parse_opts_vxlan(nla, info, opts_len,
                                                          extack);
                        if (opt_len < 0)
                                return opt_len;
                        opts_len += opt_len;
                        type = IP_TUNNEL_VXLAN_OPT_BIT;
                        break;
                case LWTUNNEL_IP_OPTS_ERSPAN:
                        if (type)
                                return -EINVAL;
                        opt_len = ip_tun_parse_opts_erspan(nla, info, opts_len,
                                                           extack);
                        if (opt_len < 0)
                                return opt_len;
                        opts_len += opt_len;
                        type = IP_TUNNEL_ERSPAN_OPT_BIT;
                        break;
                default:
                        return -EINVAL;
                }
        }

        return opts_len;
}

static int ip_tun_get_optlen(struct nlattr *attr,
                             struct netlink_ext_ack *extack)
{
        return ip_tun_parse_opts(attr, NULL, extack);
}

static int ip_tun_set_opts(struct nlattr *attr, struct ip_tunnel_info *info,
                           struct netlink_ext_ack *extack)
{
        return ip_tun_parse_opts(attr, info, extack);
}

static int ip_tun_build_state(struct net *net, struct nlattr *attr,
                              unsigned int family, const void *cfg,
                              struct lwtunnel_state **ts,
                              struct netlink_ext_ack *extack)
{
        struct nlattr *tb[LWTUNNEL_IP_MAX + 1];
        struct lwtunnel_state *new_state;
        struct ip_tunnel_info *tun_info;
        int err, opt_len;

        err = nla_parse_nested_deprecated(tb, LWTUNNEL_IP_MAX, attr,
                                          ip_tun_policy, extack);
        if (err < 0)
                return err;

        opt_len = ip_tun_get_optlen(tb[LWTUNNEL_IP_OPTS], extack);
        if (opt_len < 0)
                return opt_len;

        new_state = lwtunnel_state_alloc(sizeof(*tun_info) + opt_len);
        if (!new_state)
                return -ENOMEM;

        new_state->type = LWTUNNEL_ENCAP_IP;

        tun_info = lwt_tun_info(new_state);

        err = ip_tun_set_opts(tb[LWTUNNEL_IP_OPTS], tun_info, extack);
        if (err < 0) {
                lwtstate_free(new_state);
                return err;
        }

#ifdef CONFIG_DST_CACHE
        err = dst_cache_init(&tun_info->dst_cache, GFP_KERNEL);
        if (err) {
                lwtstate_free(new_state);
                return err;
        }
#endif

        if (tb[LWTUNNEL_IP_ID])
                tun_info->key.tun_id = nla_get_be64(tb[LWTUNNEL_IP_ID]);

        if (tb[LWTUNNEL_IP_DST])
                tun_info->key.u.ipv4.dst = nla_get_in_addr(tb[LWTUNNEL_IP_DST]);

        if (tb[LWTUNNEL_IP_SRC])
                tun_info->key.u.ipv4.src = nla_get_in_addr(tb[LWTUNNEL_IP_SRC]);

        if (tb[LWTUNNEL_IP_TTL])
                tun_info->key.ttl = nla_get_u8(tb[LWTUNNEL_IP_TTL]);

        if (tb[LWTUNNEL_IP_TOS])
                tun_info->key.tos = nla_get_u8(tb[LWTUNNEL_IP_TOS]);

        if (tb[LWTUNNEL_IP_FLAGS]) {
                IP_TUNNEL_DECLARE_FLAGS(flags);

                ip_tunnel_flags_from_be16(flags,
                                          nla_get_be16(tb[LWTUNNEL_IP_FLAGS]));
                ip_tunnel_clear_options_present(flags);

                ip_tunnel_flags_or(tun_info->key.tun_flags,
                                   tun_info->key.tun_flags, flags);
        }

        tun_info->mode = IP_TUNNEL_INFO_TX;
        tun_info->options_len = opt_len;

        *ts = new_state;

        return 0;
}

static void ip_tun_destroy_state(struct lwtunnel_state *lwtstate)
{
#ifdef CONFIG_DST_CACHE
        struct ip_tunnel_info *tun_info = lwt_tun_info(lwtstate);

        dst_cache_destroy(&tun_info->dst_cache);
#endif
}

static int ip_tun_fill_encap_opts_geneve(struct sk_buff *skb,
                                         struct ip_tunnel_info *tun_info)
{
        struct geneve_opt *opt;
        struct nlattr *nest;
        int offset = 0;

        nest = nla_nest_start_noflag(skb, LWTUNNEL_IP_OPTS_GENEVE);
        if (!nest)
                return -ENOMEM;

        while (tun_info->options_len > offset) {
                opt = ip_tunnel_info_opts(tun_info) + offset;
                if (nla_put_be16(skb, LWTUNNEL_IP_OPT_GENEVE_CLASS,
                                 opt->opt_class) ||
                    nla_put_u8(skb, LWTUNNEL_IP_OPT_GENEVE_TYPE, opt->type) ||
                    nla_put(skb, LWTUNNEL_IP_OPT_GENEVE_DATA, opt->length * 4,
                            opt->opt_data)) {
                        nla_nest_cancel(skb, nest);
                        return -ENOMEM;
                }
                offset += sizeof(*opt) + opt->length * 4;
        }

        nla_nest_end(skb, nest);
        return 0;
}

static int ip_tun_fill_encap_opts_vxlan(struct sk_buff *skb,
                                        struct ip_tunnel_info *tun_info)
{
        struct vxlan_metadata *md;
        struct nlattr *nest;

        nest = nla_nest_start_noflag(skb, LWTUNNEL_IP_OPTS_VXLAN);
        if (!nest)
                return -ENOMEM;

        md = ip_tunnel_info_opts(tun_info);
        if (nla_put_u32(skb, LWTUNNEL_IP_OPT_VXLAN_GBP, md->gbp)) {
                nla_nest_cancel(skb, nest);
                return -ENOMEM;
        }

        nla_nest_end(skb, nest);
        return 0;
}

static int ip_tun_fill_encap_opts_erspan(struct sk_buff *skb,
                                         struct ip_tunnel_info *tun_info)
{
        struct erspan_metadata *md;
        struct nlattr *nest;

        nest = nla_nest_start_noflag(skb, LWTUNNEL_IP_OPTS_ERSPAN);
        if (!nest)
                return -ENOMEM;

        md = ip_tunnel_info_opts(tun_info);
        if (nla_put_u8(skb, LWTUNNEL_IP_OPT_ERSPAN_VER, md->version))
                goto err;

        if (md->version == 1 &&
            nla_put_be32(skb, LWTUNNEL_IP_OPT_ERSPAN_INDEX, md->u.index))
                goto err;

        if (md->version == 2 &&
            (nla_put_u8(skb, LWTUNNEL_IP_OPT_ERSPAN_DIR, md->u.md2.dir) ||
             nla_put_u8(skb, LWTUNNEL_IP_OPT_ERSPAN_HWID,
                        get_hwid(&md->u.md2))))
                goto err;

        nla_nest_end(skb, nest);
        return 0;
err:
        nla_nest_cancel(skb, nest);
        return -ENOMEM;
}

static int ip_tun_fill_encap_opts(struct sk_buff *skb, int type,
                                  struct ip_tunnel_info *tun_info)
{
        struct nlattr *nest;
        int err = 0;

        if (!ip_tunnel_is_options_present(tun_info->key.tun_flags))
                return 0;

        nest = nla_nest_start_noflag(skb, type);
        if (!nest)
                return -ENOMEM;

        if (test_bit(IP_TUNNEL_GENEVE_OPT_BIT, tun_info->key.tun_flags))
                err = ip_tun_fill_encap_opts_geneve(skb, tun_info);
        else if (test_bit(IP_TUNNEL_VXLAN_OPT_BIT, tun_info->key.tun_flags))
                err = ip_tun_fill_encap_opts_vxlan(skb, tun_info);
        else if (test_bit(IP_TUNNEL_ERSPAN_OPT_BIT, tun_info->key.tun_flags))
                err = ip_tun_fill_encap_opts_erspan(skb, tun_info);

        if (err) {
                nla_nest_cancel(skb, nest);
                return err;
        }

        nla_nest_end(skb, nest);
        return 0;
}

static int ip_tun_fill_encap_info(struct sk_buff *skb,
                                  struct lwtunnel_state *lwtstate)
{
        struct ip_tunnel_info *tun_info = lwt_tun_info(lwtstate);

        if (nla_put_be64(skb, LWTUNNEL_IP_ID, tun_info->key.tun_id,
                         LWTUNNEL_IP_PAD) ||
            nla_put_in_addr(skb, LWTUNNEL_IP_DST, tun_info->key.u.ipv4.dst) ||
            nla_put_in_addr(skb, LWTUNNEL_IP_SRC, tun_info->key.u.ipv4.src) ||
            nla_put_u8(skb, LWTUNNEL_IP_TOS, tun_info->key.tos) ||
            nla_put_u8(skb, LWTUNNEL_IP_TTL, tun_info->key.ttl) ||
            nla_put_be16(skb, LWTUNNEL_IP_FLAGS,
                         ip_tunnel_flags_to_be16(tun_info->key.tun_flags)) ||
            ip_tun_fill_encap_opts(skb, LWTUNNEL_IP_OPTS, tun_info))
                return -ENOMEM;

        return 0;
}

static int ip_tun_opts_nlsize(struct ip_tunnel_info *info)
{
        int opt_len;

        if (!ip_tunnel_is_options_present(info->key.tun_flags))
                return 0;

        opt_len = nla_total_size(0);            /* LWTUNNEL_IP_OPTS */
        if (test_bit(IP_TUNNEL_GENEVE_OPT_BIT, info->key.tun_flags)) {
                struct geneve_opt *opt;
                int offset = 0;

                opt_len += nla_total_size(0);   /* LWTUNNEL_IP_OPTS_GENEVE */
                while (info->options_len > offset) {
                        opt = ip_tunnel_info_opts(info) + offset;
                        opt_len += nla_total_size(2)    /* OPT_GENEVE_CLASS */
                                   + nla_total_size(1)  /* OPT_GENEVE_TYPE */
                                   + nla_total_size(opt->length * 4);
                                                        /* OPT_GENEVE_DATA */
                        offset += sizeof(*opt) + opt->length * 4;
                }
        } else if (test_bit(IP_TUNNEL_VXLAN_OPT_BIT, info->key.tun_flags)) {
                opt_len += nla_total_size(0)    /* LWTUNNEL_IP_OPTS_VXLAN */
                           + nla_total_size(4); /* OPT_VXLAN_GBP */
        } else if (test_bit(IP_TUNNEL_ERSPAN_OPT_BIT, info->key.tun_flags)) {
                struct erspan_metadata *md = ip_tunnel_info_opts(info);

                opt_len += nla_total_size(0)    /* LWTUNNEL_IP_OPTS_ERSPAN */
                           + nla_total_size(1)  /* OPT_ERSPAN_VER */
                           + (md->version == 1 ? nla_total_size(4)
                                                /* OPT_ERSPAN_INDEX (v1) */
                                               : nla_total_size(1) +
                                                 nla_total_size(1));
                                                /* OPT_ERSPAN_DIR + HWID (v2) */
        }

        return opt_len;
}

static int ip_tun_encap_nlsize(struct lwtunnel_state *lwtstate)
{
        return nla_total_size_64bit(8)  /* LWTUNNEL_IP_ID */
                + nla_total_size(4)     /* LWTUNNEL_IP_DST */
                + nla_total_size(4)     /* LWTUNNEL_IP_SRC */
                + nla_total_size(1)     /* LWTUNNEL_IP_TOS */
                + nla_total_size(1)     /* LWTUNNEL_IP_TTL */
                + nla_total_size(2)     /* LWTUNNEL_IP_FLAGS */
                + ip_tun_opts_nlsize(lwt_tun_info(lwtstate));
                                        /* LWTUNNEL_IP_OPTS */
}

static int ip_tun_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
        struct ip_tunnel_info *info_a = lwt_tun_info(a);
        struct ip_tunnel_info *info_b = lwt_tun_info(b);

        return memcmp(info_a, info_b, sizeof(info_a->key)) ||
               info_a->mode != info_b->mode ||
               info_a->options_len != info_b->options_len ||
               memcmp(ip_tunnel_info_opts(info_a),
                      ip_tunnel_info_opts(info_b), info_a->options_len);
}

static const struct lwtunnel_encap_ops ip_tun_lwt_ops = {
        .build_state = ip_tun_build_state,
        .destroy_state = ip_tun_destroy_state,
        .fill_encap = ip_tun_fill_encap_info,
        .get_encap_size = ip_tun_encap_nlsize,
        .cmp_encap = ip_tun_cmp_encap,
        .owner = THIS_MODULE,
};

static const struct nla_policy ip6_tun_policy[LWTUNNEL_IP6_MAX + 1] = {
        [LWTUNNEL_IP6_UNSPEC]   = { .strict_start_type = LWTUNNEL_IP6_OPTS },
        [LWTUNNEL_IP6_ID]               = { .type = NLA_U64 },
        [LWTUNNEL_IP6_DST]              = { .len = sizeof(struct in6_addr) },
        [LWTUNNEL_IP6_SRC]              = { .len = sizeof(struct in6_addr) },
        [LWTUNNEL_IP6_HOPLIMIT]         = { .type = NLA_U8 },
        [LWTUNNEL_IP6_TC]               = { .type = NLA_U8 },
        [LWTUNNEL_IP6_FLAGS]            = { .type = NLA_U16 },
        [LWTUNNEL_IP6_OPTS]             = { .type = NLA_NESTED },
};

static int ip6_tun_build_state(struct net *net, struct nlattr *attr,
                               unsigned int family, const void *cfg,
                               struct lwtunnel_state **ts,
                               struct netlink_ext_ack *extack)
{
        struct nlattr *tb[LWTUNNEL_IP6_MAX + 1];
        struct lwtunnel_state *new_state;
        struct ip_tunnel_info *tun_info;
        int err, opt_len;

        err = nla_parse_nested_deprecated(tb, LWTUNNEL_IP6_MAX, attr,
                                          ip6_tun_policy, extack);
        if (err < 0)
                return err;

        opt_len = ip_tun_get_optlen(tb[LWTUNNEL_IP6_OPTS], extack);
        if (opt_len < 0)
                return opt_len;

        new_state = lwtunnel_state_alloc(sizeof(*tun_info) + opt_len);
        if (!new_state)
                return -ENOMEM;

        new_state->type = LWTUNNEL_ENCAP_IP6;

        tun_info = lwt_tun_info(new_state);

        err = ip_tun_set_opts(tb[LWTUNNEL_IP6_OPTS], tun_info, extack);
        if (err < 0) {
                lwtstate_free(new_state);
                return err;
        }

        if (tb[LWTUNNEL_IP6_ID])
                tun_info->key.tun_id = nla_get_be64(tb[LWTUNNEL_IP6_ID]);

        if (tb[LWTUNNEL_IP6_DST])
                tun_info->key.u.ipv6.dst = nla_get_in6_addr(tb[LWTUNNEL_IP6_DST]);

        if (tb[LWTUNNEL_IP6_SRC])
                tun_info->key.u.ipv6.src = nla_get_in6_addr(tb[LWTUNNEL_IP6_SRC]);

        if (tb[LWTUNNEL_IP6_HOPLIMIT])
                tun_info->key.ttl = nla_get_u8(tb[LWTUNNEL_IP6_HOPLIMIT]);

        if (tb[LWTUNNEL_IP6_TC])
                tun_info->key.tos = nla_get_u8(tb[LWTUNNEL_IP6_TC]);

        if (tb[LWTUNNEL_IP6_FLAGS]) {
                IP_TUNNEL_DECLARE_FLAGS(flags);
                __be16 data;

                data = nla_get_be16(tb[LWTUNNEL_IP6_FLAGS]);
                ip_tunnel_flags_from_be16(flags, data);
                ip_tunnel_clear_options_present(flags);

                ip_tunnel_flags_or(tun_info->key.tun_flags,
                                   tun_info->key.tun_flags, flags);
        }

        tun_info->mode = IP_TUNNEL_INFO_TX | IP_TUNNEL_INFO_IPV6;
        tun_info->options_len = opt_len;

        *ts = new_state;

        return 0;
}

static int ip6_tun_fill_encap_info(struct sk_buff *skb,
                                   struct lwtunnel_state *lwtstate)
{
        struct ip_tunnel_info *tun_info = lwt_tun_info(lwtstate);

        if (nla_put_be64(skb, LWTUNNEL_IP6_ID, tun_info->key.tun_id,
                         LWTUNNEL_IP6_PAD) ||
            nla_put_in6_addr(skb, LWTUNNEL_IP6_DST, &tun_info->key.u.ipv6.dst) ||
            nla_put_in6_addr(skb, LWTUNNEL_IP6_SRC, &tun_info->key.u.ipv6.src) ||
            nla_put_u8(skb, LWTUNNEL_IP6_TC, tun_info->key.tos) ||
            nla_put_u8(skb, LWTUNNEL_IP6_HOPLIMIT, tun_info->key.ttl) ||
            nla_put_be16(skb, LWTUNNEL_IP6_FLAGS,
                         ip_tunnel_flags_to_be16(tun_info->key.tun_flags)) ||
            ip_tun_fill_encap_opts(skb, LWTUNNEL_IP6_OPTS, tun_info))
                return -ENOMEM;

        return 0;
}

static int ip6_tun_encap_nlsize(struct lwtunnel_state *lwtstate)
{
        return nla_total_size_64bit(8)  /* LWTUNNEL_IP6_ID */
                + nla_total_size(16)    /* LWTUNNEL_IP6_DST */
                + nla_total_size(16)    /* LWTUNNEL_IP6_SRC */
                + nla_total_size(1)     /* LWTUNNEL_IP6_HOPLIMIT */
                + nla_total_size(1)     /* LWTUNNEL_IP6_TC */
                + nla_total_size(2)     /* LWTUNNEL_IP6_FLAGS */
                + ip_tun_opts_nlsize(lwt_tun_info(lwtstate));
                                        /* LWTUNNEL_IP6_OPTS */
}

static const struct lwtunnel_encap_ops ip6_tun_lwt_ops = {
        .build_state = ip6_tun_build_state,
        .fill_encap = ip6_tun_fill_encap_info,
        .get_encap_size = ip6_tun_encap_nlsize,
        .cmp_encap = ip_tun_cmp_encap,
        .owner = THIS_MODULE,
};

void __init ip_tunnel_core_init(void)
{
        /* If you land here, make sure whether increasing ip_tunnel_info's
         * options_len is a reasonable choice with its usage in front ends
         * (f.e., it's part of flow keys, etc).
         */
        BUILD_BUG_ON(IP_TUNNEL_OPTS_MAX != 255);

        lwtunnel_encap_add_ops(&ip_tun_lwt_ops, LWTUNNEL_ENCAP_IP);
        lwtunnel_encap_add_ops(&ip6_tun_lwt_ops, LWTUNNEL_ENCAP_IP6);
}

DEFINE_STATIC_KEY_FALSE(ip_tunnel_metadata_cnt);
EXPORT_SYMBOL(ip_tunnel_metadata_cnt);

void ip_tunnel_need_metadata(void)
{
        static_branch_inc(&ip_tunnel_metadata_cnt);
}
EXPORT_SYMBOL_GPL(ip_tunnel_need_metadata);

void ip_tunnel_unneed_metadata(void)
{
        static_branch_dec(&ip_tunnel_metadata_cnt);
}
EXPORT_SYMBOL_GPL(ip_tunnel_unneed_metadata);

/* Returns either the correct skb->protocol value, or 0 if invalid. */
__be16 ip_tunnel_parse_protocol(const struct sk_buff *skb)
{
        if (skb_network_header(skb) >= skb->head &&
            (skb_network_header(skb) + sizeof(struct iphdr)) <= skb_tail_pointer(skb) &&
            ip_hdr(skb)->version == 4)
                return htons(ETH_P_IP);
        if (skb_network_header(skb) >= skb->head &&
            (skb_network_header(skb) + sizeof(struct ipv6hdr)) <= skb_tail_pointer(skb) &&
            ipv6_hdr(skb)->version == 6)
                return htons(ETH_P_IPV6);
        return 0;
}
EXPORT_SYMBOL(ip_tunnel_parse_protocol);

const struct header_ops ip_tunnel_header_ops = { .parse_protocol = ip_tunnel_parse_protocol };
EXPORT_SYMBOL(ip_tunnel_header_ops);

/* This function returns true when ENCAP attributes are present in the nl msg */
bool ip_tunnel_netlink_encap_parms(struct nlattr *data[],
                                   struct ip_tunnel_encap *encap)
{
        bool ret = false;

        memset(encap, 0, sizeof(*encap));

        if (!data)
                return ret;

        if (data[IFLA_IPTUN_ENCAP_TYPE]) {
                ret = true;
                encap->type = nla_get_u16(data[IFLA_IPTUN_ENCAP_TYPE]);
        }

        if (data[IFLA_IPTUN_ENCAP_FLAGS]) {
                ret = true;
                encap->flags = nla_get_u16(data[IFLA_IPTUN_ENCAP_FLAGS]);
        }

        if (data[IFLA_IPTUN_ENCAP_SPORT]) {
                ret = true;
                encap->sport = nla_get_be16(data[IFLA_IPTUN_ENCAP_SPORT]);
        }

        if (data[IFLA_IPTUN_ENCAP_DPORT]) {
                ret = true;
                encap->dport = nla_get_be16(data[IFLA_IPTUN_ENCAP_DPORT]);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(ip_tunnel_netlink_encap_parms);

void ip_tunnel_netlink_parms(struct nlattr *data[],
                             struct ip_tunnel_parm_kern *parms)
{
        if (data[IFLA_IPTUN_LINK])
                parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]);

        if (data[IFLA_IPTUN_LOCAL])
                parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]);

        if (data[IFLA_IPTUN_REMOTE])
                parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]);

        if (data[IFLA_IPTUN_TTL]) {
                parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]);
                if (parms->iph.ttl)
                        parms->iph.frag_off = htons(IP_DF);
        }

        if (data[IFLA_IPTUN_TOS])
                parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]);

        if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC]))
                parms->iph.frag_off = htons(IP_DF);

        if (data[IFLA_IPTUN_FLAGS]) {
                __be16 flags;

                flags = nla_get_be16(data[IFLA_IPTUN_FLAGS]);
                ip_tunnel_flags_from_be16(parms->i_flags, flags);
        }

        if (data[IFLA_IPTUN_PROTO])
                parms->iph.protocol = nla_get_u8(data[IFLA_IPTUN_PROTO]);
}
EXPORT_SYMBOL_GPL(ip_tunnel_netlink_parms);