root/net/xfrm/xfrm_interface_core.c
// SPDX-License-Identifier: GPL-2.0
/*
 *      XFRM virtual interface
 *
 *      Copyright (C) 2018 secunet Security Networks AG
 *
 *      Author:
 *      Steffen Klassert <steffen.klassert@secunet.com>
 */

#include <linux/module.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/sockios.h>
#include <linux/icmp.h>
#include <linux/if.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/if_link.h>
#include <linux/if_arp.h>
#include <linux/icmpv6.h>
#include <linux/init.h>
#include <linux/route.h>
#include <linux/rtnetlink.h>
#include <linux/netfilter_ipv6.h>
#include <linux/slab.h>
#include <linux/hash.h>

#include <linux/uaccess.h>
#include <linux/atomic.h>

#include <net/gso.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <net/ip_tunnels.h>
#include <net/addrconf.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/dst_metadata.h>
#include <net/netns/generic.h>
#include <linux/etherdevice.h>

static int xfrmi_dev_init(struct net_device *dev);
static void xfrmi_dev_setup(struct net_device *dev);
static struct rtnl_link_ops xfrmi_link_ops __read_mostly;
static unsigned int xfrmi_net_id __read_mostly;
static const struct net_device_ops xfrmi_netdev_ops;

#define XFRMI_HASH_BITS 8
#define XFRMI_HASH_SIZE BIT(XFRMI_HASH_BITS)

struct xfrmi_net {
        /* lists for storing interfaces in use */
        struct xfrm_if __rcu *xfrmi[XFRMI_HASH_SIZE];
        struct xfrm_if __rcu *collect_md_xfrmi;
};

static const struct nla_policy xfrm_lwt_policy[LWT_XFRM_MAX + 1] = {
        [LWT_XFRM_IF_ID]        = NLA_POLICY_MIN(NLA_U32, 1),
        [LWT_XFRM_LINK]         = NLA_POLICY_MIN(NLA_U32, 1),
};

static void xfrmi_destroy_state(struct lwtunnel_state *lwt)
{
}

static int xfrmi_build_state(struct net *net, struct nlattr *nla,
                             unsigned int family, const void *cfg,
                             struct lwtunnel_state **ts,
                             struct netlink_ext_ack *extack)
{
        struct nlattr *tb[LWT_XFRM_MAX + 1];
        struct lwtunnel_state *new_state;
        struct xfrm_md_info *info;
        int ret;

        ret = nla_parse_nested(tb, LWT_XFRM_MAX, nla, xfrm_lwt_policy, extack);
        if (ret < 0)
                return ret;

        if (!tb[LWT_XFRM_IF_ID]) {
                NL_SET_ERR_MSG(extack, "if_id must be set");
                return -EINVAL;
        }

        new_state = lwtunnel_state_alloc(sizeof(*info));
        if (!new_state) {
                NL_SET_ERR_MSG(extack, "failed to create encap info");
                return -ENOMEM;
        }

        new_state->type = LWTUNNEL_ENCAP_XFRM;

        info = lwt_xfrm_info(new_state);

        info->if_id = nla_get_u32(tb[LWT_XFRM_IF_ID]);

        if (tb[LWT_XFRM_LINK])
                info->link = nla_get_u32(tb[LWT_XFRM_LINK]);

        *ts = new_state;
        return 0;
}

static int xfrmi_fill_encap_info(struct sk_buff *skb,
                                 struct lwtunnel_state *lwt)
{
        struct xfrm_md_info *info = lwt_xfrm_info(lwt);

        if (nla_put_u32(skb, LWT_XFRM_IF_ID, info->if_id) ||
            (info->link && nla_put_u32(skb, LWT_XFRM_LINK, info->link)))
                return -EMSGSIZE;

        return 0;
}

static int xfrmi_encap_nlsize(struct lwtunnel_state *lwtstate)
{
        return nla_total_size(sizeof(u32)) + /* LWT_XFRM_IF_ID */
                nla_total_size(sizeof(u32)); /* LWT_XFRM_LINK */
}

static int xfrmi_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
        struct xfrm_md_info *a_info = lwt_xfrm_info(a);
        struct xfrm_md_info *b_info = lwt_xfrm_info(b);

        return memcmp(a_info, b_info, sizeof(*a_info));
}

static const struct lwtunnel_encap_ops xfrmi_encap_ops = {
        .build_state    = xfrmi_build_state,
        .destroy_state  = xfrmi_destroy_state,
        .fill_encap     = xfrmi_fill_encap_info,
        .get_encap_size = xfrmi_encap_nlsize,
        .cmp_encap      = xfrmi_encap_cmp,
        .owner          = THIS_MODULE,
};

#define for_each_xfrmi_rcu(start, xi) \
        for (xi = rcu_dereference(start); xi; xi = rcu_dereference(xi->next))

static u32 xfrmi_hash(u32 if_id)
{
        return hash_32(if_id, XFRMI_HASH_BITS);
}

static struct xfrm_if *xfrmi_lookup(struct net *net, struct xfrm_state *x)
{
        struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);
        struct xfrm_if *xi;

        for_each_xfrmi_rcu(xfrmn->xfrmi[xfrmi_hash(x->if_id)], xi) {
                if (x->if_id == xi->p.if_id &&
                    (xi->dev->flags & IFF_UP))
                        return xi;
        }

        xi = rcu_dereference(xfrmn->collect_md_xfrmi);
        if (xi && (xi->dev->flags & IFF_UP))
                return xi;

        return NULL;
}

static bool xfrmi_decode_session(struct sk_buff *skb,
                                 unsigned short family,
                                 struct xfrm_if_decode_session_result *res)
{
        struct net_device *dev;
        struct xfrm_if *xi;
        int ifindex = 0;

        if (!secpath_exists(skb) || !skb->dev)
                return false;

        switch (family) {
        case AF_INET6:
                ifindex = inet6_sdif(skb);
                break;
        case AF_INET:
                ifindex = inet_sdif(skb);
                break;
        }

        if (ifindex) {
                struct net *net = xs_net(xfrm_input_state(skb));

                dev = dev_get_by_index_rcu(net, ifindex);
        } else {
                dev = skb->dev;
        }

        if (!dev || !(dev->flags & IFF_UP))
                return false;
        if (dev->netdev_ops != &xfrmi_netdev_ops)
                return false;

        xi = netdev_priv(dev);
        res->net = xi->net;

        if (xi->p.collect_md)
                res->if_id = xfrm_input_state(skb)->if_id;
        else
                res->if_id = xi->p.if_id;
        return true;
}

static void xfrmi_link(struct xfrmi_net *xfrmn, struct xfrm_if *xi)
{
        struct xfrm_if __rcu **xip = &xfrmn->xfrmi[xfrmi_hash(xi->p.if_id)];

        rcu_assign_pointer(xi->next , rtnl_dereference(*xip));
        rcu_assign_pointer(*xip, xi);
}

static void xfrmi_unlink(struct xfrmi_net *xfrmn, struct xfrm_if *xi)
{
        struct xfrm_if __rcu **xip;
        struct xfrm_if *iter;

        for (xip = &xfrmn->xfrmi[xfrmi_hash(xi->p.if_id)];
             (iter = rtnl_dereference(*xip)) != NULL;
             xip = &iter->next) {
                if (xi == iter) {
                        rcu_assign_pointer(*xip, xi->next);
                        break;
                }
        }
}

static void xfrmi_dev_free(struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);

        gro_cells_destroy(&xi->gro_cells);
}

static int xfrmi_create(struct net *net, struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);
        struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);
        int err;

        dev->rtnl_link_ops = &xfrmi_link_ops;
        err = register_netdevice(dev);
        if (err < 0)
                goto out;

        if (xi->p.collect_md)
                rcu_assign_pointer(xfrmn->collect_md_xfrmi, xi);
        else
                xfrmi_link(xfrmn, xi);

        return 0;

out:
        return err;
}

static struct xfrm_if *xfrmi_locate(struct net *net, struct xfrm_if_parms *p)
{
        struct xfrm_if __rcu **xip;
        struct xfrm_if *xi;
        struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);

        for (xip = &xfrmn->xfrmi[xfrmi_hash(p->if_id)];
             (xi = rtnl_dereference(*xip)) != NULL;
             xip = &xi->next)
                if (xi->p.if_id == p->if_id)
                        return xi;

        return NULL;
}

static void xfrmi_dev_uninit(struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);
        struct xfrmi_net *xfrmn = net_generic(xi->net, xfrmi_net_id);

        if (xi->p.collect_md)
                RCU_INIT_POINTER(xfrmn->collect_md_xfrmi, NULL);
        else
                xfrmi_unlink(xfrmn, xi);
}

static void xfrmi_scrub_packet(struct sk_buff *skb, bool xnet)
{
        skb_clear_tstamp(skb);
        skb->pkt_type = PACKET_HOST;
        skb->skb_iif = 0;
        skb->ignore_df = 0;
        skb_dst_drop(skb);
        nf_reset_ct(skb);
        nf_reset_trace(skb);

        if (!xnet)
                return;

        ipvs_reset(skb);
        secpath_reset(skb);
        skb_orphan(skb);
        skb->mark = 0;
}

static int xfrmi_input(struct sk_buff *skb, int nexthdr, __be32 spi,
                       int encap_type, unsigned short family)
{
        struct sec_path *sp;

        sp = skb_sec_path(skb);
        if (sp && (sp->len || sp->olen) &&
            !xfrm_policy_check(NULL, XFRM_POLICY_IN, skb, family))
                goto discard;

        XFRM_SPI_SKB_CB(skb)->family = family;
        if (family == AF_INET) {
                XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
                XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL;
        } else {
                XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
                XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
        }

        return xfrm_input(skb, nexthdr, spi, encap_type);
discard:
        kfree_skb(skb);
        return 0;
}

static int xfrmi4_rcv(struct sk_buff *skb)
{
        return xfrmi_input(skb, ip_hdr(skb)->protocol, 0, 0, AF_INET);
}

static int xfrmi6_rcv(struct sk_buff *skb)
{
        return xfrmi_input(skb, skb_network_header(skb)[IP6CB(skb)->nhoff],
                           0, 0, AF_INET6);
}

static int xfrmi4_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
{
        return xfrmi_input(skb, nexthdr, spi, encap_type, AF_INET);
}

static int xfrmi6_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
{
        return xfrmi_input(skb, nexthdr, spi, encap_type, AF_INET6);
}

static int xfrmi_rcv_cb(struct sk_buff *skb, int err)
{
        const struct xfrm_mode *inner_mode;
        struct net_device *dev;
        struct xfrm_state *x;
        struct xfrm_if *xi;
        bool xnet;
        int link;

        if (err && !secpath_exists(skb))
                return 0;

        x = xfrm_input_state(skb);

        xi = xfrmi_lookup(xs_net(x), x);
        if (!xi)
                return 1;

        link = skb->dev->ifindex;
        dev = xi->dev;
        skb->dev = dev;

        if (err) {
                DEV_STATS_INC(dev, rx_errors);
                DEV_STATS_INC(dev, rx_dropped);

                return 0;
        }

        xnet = !net_eq(xi->net, dev_net(skb->dev));

        if (xnet) {
                inner_mode = &x->inner_mode;

                if (x->sel.family == AF_UNSPEC) {
                        inner_mode = xfrm_ip2inner_mode(x, XFRM_MODE_SKB_CB(skb)->protocol);
                        if (inner_mode == NULL) {
                                XFRM_INC_STATS(dev_net(skb->dev),
                                               LINUX_MIB_XFRMINSTATEMODEERROR);
                                return -EINVAL;
                        }
                }

                if (!xfrm_policy_check(NULL, XFRM_POLICY_IN, skb,
                                       inner_mode->family))
                        return -EPERM;
        }

        xfrmi_scrub_packet(skb, xnet);
        if (xi->p.collect_md) {
                struct metadata_dst *md_dst;

                md_dst = metadata_dst_alloc(0, METADATA_XFRM, GFP_ATOMIC);
                if (!md_dst)
                        return -ENOMEM;

                md_dst->u.xfrm_info.if_id = x->if_id;
                md_dst->u.xfrm_info.link = link;
                skb_dst_set(skb, (struct dst_entry *)md_dst);
        }
        dev_sw_netstats_rx_add(dev, skb->len);

        return 0;
}

static int
xfrmi_xmit2(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
{
        struct xfrm_if *xi = netdev_priv(dev);
        struct dst_entry *dst = skb_dst(skb);
        unsigned int length = skb->len;
        struct net_device *tdev;
        struct xfrm_state *x;
        int err = -1;
        u32 if_id;
        int mtu;

        if (xi->p.collect_md) {
                struct xfrm_md_info *md_info = skb_xfrm_md_info(skb);

                if (unlikely(!md_info))
                        return -EINVAL;

                if_id = md_info->if_id;
                fl->flowi_oif = md_info->link;
                if (md_info->dst_orig) {
                        struct dst_entry *tmp_dst = dst;

                        dst = md_info->dst_orig;
                        skb_dst_set(skb, dst);
                        md_info->dst_orig = NULL;
                        dst_release(tmp_dst);
                }
        } else {
                if_id = xi->p.if_id;
        }

        dst_hold(dst);
        dst = xfrm_lookup_with_ifid(xi->net, dst, fl, NULL, 0, if_id);
        if (IS_ERR(dst)) {
                err = PTR_ERR(dst);
                dst = NULL;
                goto tx_err_link_failure;
        }

        x = dst->xfrm;
        if (!x)
                goto tx_err_link_failure;

        if (x->if_id != if_id)
                goto tx_err_link_failure;

        tdev = dst->dev;

        if (tdev == dev) {
                DEV_STATS_INC(dev, collisions);
                net_warn_ratelimited("%s: Local routing loop detected!\n",
                                     dev->name);
                goto tx_err_dst_release;
        }

        mtu = dst_mtu(dst);
        if ((!skb_is_gso(skb) && skb->len > mtu) ||
            (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu))) {
                skb_dst_update_pmtu_no_confirm(skb, mtu);

                if (skb->protocol == htons(ETH_P_IPV6)) {
                        if (mtu < IPV6_MIN_MTU)
                                mtu = IPV6_MIN_MTU;

                        if (skb->len > 1280)
                                icmpv6_ndo_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
                        else
                                goto xmit;
                } else {
                        if (!(ip_hdr(skb)->frag_off & htons(IP_DF)))
                                goto xmit;
                        icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
                                      htonl(mtu));
                }

                dst_release(dst);
                return -EMSGSIZE;
        }

xmit:
        xfrmi_scrub_packet(skb, !net_eq(xi->net, dev_net(dev)));
        skb_dst_set(skb, dst);
        skb->dev = tdev;

        err = dst_output(xi->net, skb_to_full_sk(skb), skb);
        if (net_xmit_eval(err) == 0) {
                dev_sw_netstats_tx_add(dev, 1, length);
        } else {
                DEV_STATS_INC(dev, tx_errors);
                DEV_STATS_INC(dev, tx_aborted_errors);
        }

        return 0;
tx_err_link_failure:
        DEV_STATS_INC(dev, tx_carrier_errors);
        dst_link_failure(skb);
tx_err_dst_release:
        dst_release(dst);
        return err;
}

static netdev_tx_t xfrmi_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);
        struct dst_entry *dst = skb_dst(skb);
        struct flowi fl;
        int ret;

        memset(&fl, 0, sizeof(fl));

        switch (skb->protocol) {
        case htons(ETH_P_IPV6):
                memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
                xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET6);
                if (!dst) {
                        fl.u.ip6.flowi6_oif = dev->ifindex;
                        fl.u.ip6.flowi6_flags |= FLOWI_FLAG_ANYSRC;
                        dst = ip6_route_output(dev_net(dev), NULL, &fl.u.ip6);
                        if (dst->error) {
                                dst_release(dst);
                                DEV_STATS_INC(dev, tx_carrier_errors);
                                goto tx_err;
                        }
                        skb_dst_set(skb, dst);
                }
                break;
        case htons(ETH_P_IP):
                memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
                xfrm_decode_session(dev_net(dev), skb, &fl, AF_INET);
                if (!dst) {
                        struct rtable *rt;

                        fl.u.ip4.flowi4_oif = dev->ifindex;
                        fl.u.ip4.flowi4_flags |= FLOWI_FLAG_ANYSRC;
                        rt = __ip_route_output_key(dev_net(dev), &fl.u.ip4);
                        if (IS_ERR(rt)) {
                                DEV_STATS_INC(dev, tx_carrier_errors);
                                goto tx_err;
                        }
                        skb_dst_set(skb, &rt->dst);
                }
                break;
        default:
                goto tx_err;
        }

        fl.flowi_oif = xi->p.link;

        ret = xfrmi_xmit2(skb, dev, &fl);
        if (ret < 0)
                goto tx_err;

        return NETDEV_TX_OK;

tx_err:
        DEV_STATS_INC(dev, tx_errors);
        DEV_STATS_INC(dev, tx_dropped);
        kfree_skb(skb);
        return NETDEV_TX_OK;
}

static int xfrmi4_err(struct sk_buff *skb, u32 info)
{
        const struct iphdr *iph = (const struct iphdr *)skb->data;
        struct net *net = dev_net(skb->dev);
        int protocol = iph->protocol;
        struct ip_comp_hdr *ipch;
        struct ip_esp_hdr *esph;
        struct ip_auth_hdr *ah ;
        struct xfrm_state *x;
        struct xfrm_if *xi;
        __be32 spi;

        switch (protocol) {
        case IPPROTO_ESP:
                esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
                spi = esph->spi;
                break;
        case IPPROTO_AH:
                ah = (struct ip_auth_hdr *)(skb->data+(iph->ihl<<2));
                spi = ah->spi;
                break;
        case IPPROTO_COMP:
                ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
                spi = htonl(ntohs(ipch->cpi));
                break;
        default:
                return 0;
        }

        switch (icmp_hdr(skb)->type) {
        case ICMP_DEST_UNREACH:
                if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
                        return 0;
                break;
        case ICMP_REDIRECT:
                break;
        default:
                return 0;
        }

        x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
                              spi, protocol, AF_INET);
        if (!x)
                return 0;

        xi = xfrmi_lookup(net, x);
        if (!xi) {
                xfrm_state_put(x);
                return -1;
        }

        if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
                ipv4_update_pmtu(skb, net, info, 0, protocol);
        else
                ipv4_redirect(skb, net, 0, protocol);
        xfrm_state_put(x);

        return 0;
}

static int xfrmi6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                    u8 type, u8 code, int offset, __be32 info)
{
        const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
        struct net *net = dev_net(skb->dev);
        int protocol = iph->nexthdr;
        struct ip_comp_hdr *ipch;
        struct ip_esp_hdr *esph;
        struct ip_auth_hdr *ah;
        struct xfrm_state *x;
        struct xfrm_if *xi;
        __be32 spi;

        switch (protocol) {
        case IPPROTO_ESP:
                esph = (struct ip_esp_hdr *)(skb->data + offset);
                spi = esph->spi;
                break;
        case IPPROTO_AH:
                ah = (struct ip_auth_hdr *)(skb->data + offset);
                spi = ah->spi;
                break;
        case IPPROTO_COMP:
                ipch = (struct ip_comp_hdr *)(skb->data + offset);
                spi = htonl(ntohs(ipch->cpi));
                break;
        default:
                return 0;
        }

        if (type != ICMPV6_PKT_TOOBIG &&
            type != NDISC_REDIRECT)
                return 0;

        x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
                              spi, protocol, AF_INET6);
        if (!x)
                return 0;

        xi = xfrmi_lookup(net, x);
        if (!xi) {
                xfrm_state_put(x);
                return -1;
        }

        if (type == NDISC_REDIRECT)
                ip6_redirect(skb, net, skb->dev->ifindex, 0,
                             sock_net_uid(net, NULL));
        else
                ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
        xfrm_state_put(x);

        return 0;
}

static int xfrmi_change(struct xfrm_if *xi, const struct xfrm_if_parms *p)
{
        if (xi->p.link != p->link)
                return -EINVAL;

        xi->p.if_id = p->if_id;

        return 0;
}

static int xfrmi_update(struct xfrm_if *xi, struct xfrm_if_parms *p)
{
        struct net *net = xi->net;
        struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);
        int err;

        xfrmi_unlink(xfrmn, xi);
        synchronize_net();
        err = xfrmi_change(xi, p);
        xfrmi_link(xfrmn, xi);
        netdev_state_change(xi->dev);
        return err;
}

static int xfrmi_get_iflink(const struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);

        return READ_ONCE(xi->p.link);
}

static const struct net_device_ops xfrmi_netdev_ops = {
        .ndo_init       = xfrmi_dev_init,
        .ndo_uninit     = xfrmi_dev_uninit,
        .ndo_start_xmit = xfrmi_xmit,
        .ndo_get_stats64 = dev_get_tstats64,
        .ndo_get_iflink = xfrmi_get_iflink,
};

static void xfrmi_dev_setup(struct net_device *dev)
{
        dev->netdev_ops         = &xfrmi_netdev_ops;
        dev->header_ops         = &ip_tunnel_header_ops;
        dev->type               = ARPHRD_NONE;
        dev->mtu                = ETH_DATA_LEN;
        dev->min_mtu            = ETH_MIN_MTU;
        dev->max_mtu            = IP_MAX_MTU;
        dev->flags              = IFF_NOARP;
        dev->needs_free_netdev  = true;
        dev->priv_destructor    = xfrmi_dev_free;
        dev->pcpu_stat_type     = NETDEV_PCPU_STAT_TSTATS;
        netif_keep_dst(dev);

        eth_broadcast_addr(dev->broadcast);
}

#define XFRMI_FEATURES (NETIF_F_SG |            \
                        NETIF_F_FRAGLIST |      \
                        NETIF_F_GSO_SOFTWARE |  \
                        NETIF_F_HW_CSUM)

static int xfrmi_dev_init(struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);
        struct net_device *phydev = __dev_get_by_index(xi->net, xi->p.link);
        int err;

        err = gro_cells_init(&xi->gro_cells, dev);
        if (err)
                return err;

        dev->lltx = true;
        dev->features |= XFRMI_FEATURES;
        dev->hw_features |= XFRMI_FEATURES;

        if (phydev) {
                dev->needed_headroom = phydev->needed_headroom;
                dev->needed_tailroom = phydev->needed_tailroom;

                if (is_zero_ether_addr(dev->dev_addr))
                        eth_hw_addr_inherit(dev, phydev);
                if (is_zero_ether_addr(dev->broadcast))
                        memcpy(dev->broadcast, phydev->broadcast,
                               dev->addr_len);
        } else {
                eth_hw_addr_random(dev);
                eth_broadcast_addr(dev->broadcast);
        }

        return 0;
}

static int xfrmi_validate(struct nlattr *tb[], struct nlattr *data[],
                         struct netlink_ext_ack *extack)
{
        return 0;
}

static void xfrmi_netlink_parms(struct nlattr *data[],
                               struct xfrm_if_parms *parms)
{
        memset(parms, 0, sizeof(*parms));

        if (!data)
                return;

        if (data[IFLA_XFRM_LINK])
                parms->link = nla_get_u32(data[IFLA_XFRM_LINK]);

        if (data[IFLA_XFRM_IF_ID])
                parms->if_id = nla_get_u32(data[IFLA_XFRM_IF_ID]);

        if (data[IFLA_XFRM_COLLECT_METADATA])
                parms->collect_md = true;
}

static int xfrmi_newlink(struct net_device *dev,
                         struct rtnl_newlink_params *params,
                         struct netlink_ext_ack *extack)
{
        struct nlattr **data = params->data;
        struct xfrm_if_parms p = {};
        struct xfrm_if *xi;
        struct net *net;
        int err;

        net = params->link_net ? : dev_net(dev);
        xfrmi_netlink_parms(data, &p);
        if (p.collect_md) {
                struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);

                if (p.link || p.if_id) {
                        NL_SET_ERR_MSG(extack, "link and if_id must be zero");
                        return -EINVAL;
                }

                if (rtnl_dereference(xfrmn->collect_md_xfrmi))
                        return -EEXIST;

        } else {
                if (!p.if_id) {
                        NL_SET_ERR_MSG(extack, "if_id must be non zero");
                        return -EINVAL;
                }

                xi = xfrmi_locate(net, &p);
                if (xi)
                        return -EEXIST;
        }

        xi = netdev_priv(dev);
        xi->p = p;
        xi->net = net;
        xi->dev = dev;

        err = xfrmi_create(net, dev);
        return err;
}

static void xfrmi_dellink(struct net_device *dev, struct list_head *head)
{
        unregister_netdevice_queue(dev, head);
}

static int xfrmi_changelink(struct net_device *dev, struct nlattr *tb[],
                           struct nlattr *data[],
                           struct netlink_ext_ack *extack)
{
        struct xfrm_if *xi = netdev_priv(dev);
        struct net *net = xi->net;
        struct xfrm_if_parms p = {};

        xfrmi_netlink_parms(data, &p);
        if (!p.if_id) {
                NL_SET_ERR_MSG(extack, "if_id must be non zero");
                return -EINVAL;
        }

        if (p.collect_md || xi->p.collect_md) {
                NL_SET_ERR_MSG(extack, "collect_md can't be changed");
                return -EINVAL;
        }

        xi = xfrmi_locate(net, &p);
        if (!xi) {
                xi = netdev_priv(dev);
        } else {
                if (xi->dev != dev)
                        return -EEXIST;
        }

        return xfrmi_update(xi, &p);
}

static size_t xfrmi_get_size(const struct net_device *dev)
{
        return
                /* IFLA_XFRM_LINK */
                nla_total_size(4) +
                /* IFLA_XFRM_IF_ID */
                nla_total_size(4) +
                /* IFLA_XFRM_COLLECT_METADATA */
                nla_total_size(0) +
                0;
}

static int xfrmi_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);
        struct xfrm_if_parms *parm = &xi->p;

        if (nla_put_u32(skb, IFLA_XFRM_LINK, parm->link) ||
            nla_put_u32(skb, IFLA_XFRM_IF_ID, parm->if_id) ||
            (xi->p.collect_md && nla_put_flag(skb, IFLA_XFRM_COLLECT_METADATA)))
                goto nla_put_failure;
        return 0;

nla_put_failure:
        return -EMSGSIZE;
}

static struct net *xfrmi_get_link_net(const struct net_device *dev)
{
        struct xfrm_if *xi = netdev_priv(dev);

        return READ_ONCE(xi->net);
}

static const struct nla_policy xfrmi_policy[IFLA_XFRM_MAX + 1] = {
        [IFLA_XFRM_UNSPEC]              = { .strict_start_type = IFLA_XFRM_COLLECT_METADATA },
        [IFLA_XFRM_LINK]                = { .type = NLA_U32 },
        [IFLA_XFRM_IF_ID]               = { .type = NLA_U32 },
        [IFLA_XFRM_COLLECT_METADATA]    = { .type = NLA_FLAG },
};

static struct rtnl_link_ops xfrmi_link_ops __read_mostly = {
        .kind           = "xfrm",
        .maxtype        = IFLA_XFRM_MAX,
        .policy         = xfrmi_policy,
        .priv_size      = sizeof(struct xfrm_if),
        .setup          = xfrmi_dev_setup,
        .validate       = xfrmi_validate,
        .newlink        = xfrmi_newlink,
        .dellink        = xfrmi_dellink,
        .changelink     = xfrmi_changelink,
        .get_size       = xfrmi_get_size,
        .fill_info      = xfrmi_fill_info,
        .get_link_net   = xfrmi_get_link_net,
};

static void __net_exit xfrmi_exit_rtnl(struct net *net,
                                       struct list_head *dev_to_kill)
{
        struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);
        struct xfrm_if __rcu **xip;
        struct xfrm_if *xi;
        int i;

        for (i = 0; i < XFRMI_HASH_SIZE; i++) {
                for (xip = &xfrmn->xfrmi[i];
                     (xi = rtnl_net_dereference(net, *xip)) != NULL;
                     xip = &xi->next)
                        unregister_netdevice_queue(xi->dev, dev_to_kill);
        }

        xi = rtnl_net_dereference(net, xfrmn->collect_md_xfrmi);
        if (xi)
                unregister_netdevice_queue(xi->dev, dev_to_kill);
}

static struct pernet_operations xfrmi_net_ops = {
        .exit_rtnl = xfrmi_exit_rtnl,
        .id   = &xfrmi_net_id,
        .size = sizeof(struct xfrmi_net),
};

static struct xfrm6_protocol xfrmi_esp6_protocol __read_mostly = {
        .handler        =       xfrmi6_rcv,
        .input_handler  =       xfrmi6_input,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi6_err,
        .priority       =       10,
};

static struct xfrm6_protocol xfrmi_ah6_protocol __read_mostly = {
        .handler        =       xfrm6_rcv,
        .input_handler  =       xfrm_input,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi6_err,
        .priority       =       10,
};

static struct xfrm6_protocol xfrmi_ipcomp6_protocol __read_mostly = {
        .handler        =       xfrm6_rcv,
        .input_handler  =       xfrm_input,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi6_err,
        .priority       =       10,
};

#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
static int xfrmi6_rcv_tunnel(struct sk_buff *skb)
{
        const xfrm_address_t *saddr;
        __be32 spi;

        saddr = (const xfrm_address_t *)&ipv6_hdr(skb)->saddr;
        spi = xfrm6_tunnel_spi_lookup(dev_net(skb->dev), saddr);

        return xfrm6_rcv_spi(skb, IPPROTO_IPV6, spi, NULL);
}

static struct xfrm6_tunnel xfrmi_ipv6_handler __read_mostly = {
        .handler        =       xfrmi6_rcv_tunnel,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi6_err,
        .priority       =       2,
};

static struct xfrm6_tunnel xfrmi_ip6ip_handler __read_mostly = {
        .handler        =       xfrmi6_rcv_tunnel,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi6_err,
        .priority       =       2,
};
#endif

static struct xfrm4_protocol xfrmi_esp4_protocol __read_mostly = {
        .handler        =       xfrmi4_rcv,
        .input_handler  =       xfrmi4_input,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi4_err,
        .priority       =       10,
};

static struct xfrm4_protocol xfrmi_ah4_protocol __read_mostly = {
        .handler        =       xfrm4_rcv,
        .input_handler  =       xfrm_input,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi4_err,
        .priority       =       10,
};

static struct xfrm4_protocol xfrmi_ipcomp4_protocol __read_mostly = {
        .handler        =       xfrm4_rcv,
        .input_handler  =       xfrm_input,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi4_err,
        .priority       =       10,
};

#if IS_REACHABLE(CONFIG_INET_XFRM_TUNNEL)
static int xfrmi4_rcv_tunnel(struct sk_buff *skb)
{
        return xfrm4_rcv_spi(skb, IPPROTO_IPIP, ip_hdr(skb)->saddr);
}

static struct xfrm_tunnel xfrmi_ipip_handler __read_mostly = {
        .handler        =       xfrmi4_rcv_tunnel,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi4_err,
        .priority       =       3,
};

static struct xfrm_tunnel xfrmi_ipip6_handler __read_mostly = {
        .handler        =       xfrmi4_rcv_tunnel,
        .cb_handler     =       xfrmi_rcv_cb,
        .err_handler    =       xfrmi4_err,
        .priority       =       2,
};
#endif

static int __init xfrmi4_init(void)
{
        int err;

        err = xfrm4_protocol_register(&xfrmi_esp4_protocol, IPPROTO_ESP);
        if (err < 0)
                goto xfrm_proto_esp_failed;
        err = xfrm4_protocol_register(&xfrmi_ah4_protocol, IPPROTO_AH);
        if (err < 0)
                goto xfrm_proto_ah_failed;
        err = xfrm4_protocol_register(&xfrmi_ipcomp4_protocol, IPPROTO_COMP);
        if (err < 0)
                goto xfrm_proto_comp_failed;
#if IS_REACHABLE(CONFIG_INET_XFRM_TUNNEL)
        err = xfrm4_tunnel_register(&xfrmi_ipip_handler, AF_INET);
        if (err < 0)
                goto xfrm_tunnel_ipip_failed;
        err = xfrm4_tunnel_register(&xfrmi_ipip6_handler, AF_INET6);
        if (err < 0)
                goto xfrm_tunnel_ipip6_failed;
#endif

        return 0;

#if IS_REACHABLE(CONFIG_INET_XFRM_TUNNEL)
xfrm_tunnel_ipip6_failed:
        xfrm4_tunnel_deregister(&xfrmi_ipip_handler, AF_INET);
xfrm_tunnel_ipip_failed:
        xfrm4_protocol_deregister(&xfrmi_ipcomp4_protocol, IPPROTO_COMP);
#endif
xfrm_proto_comp_failed:
        xfrm4_protocol_deregister(&xfrmi_ah4_protocol, IPPROTO_AH);
xfrm_proto_ah_failed:
        xfrm4_protocol_deregister(&xfrmi_esp4_protocol, IPPROTO_ESP);
xfrm_proto_esp_failed:
        return err;
}

static void xfrmi4_fini(void)
{
#if IS_REACHABLE(CONFIG_INET_XFRM_TUNNEL)
        xfrm4_tunnel_deregister(&xfrmi_ipip6_handler, AF_INET6);
        xfrm4_tunnel_deregister(&xfrmi_ipip_handler, AF_INET);
#endif
        xfrm4_protocol_deregister(&xfrmi_ipcomp4_protocol, IPPROTO_COMP);
        xfrm4_protocol_deregister(&xfrmi_ah4_protocol, IPPROTO_AH);
        xfrm4_protocol_deregister(&xfrmi_esp4_protocol, IPPROTO_ESP);
}

static int __init xfrmi6_init(void)
{
        int err;

        err = xfrm6_protocol_register(&xfrmi_esp6_protocol, IPPROTO_ESP);
        if (err < 0)
                goto xfrm_proto_esp_failed;
        err = xfrm6_protocol_register(&xfrmi_ah6_protocol, IPPROTO_AH);
        if (err < 0)
                goto xfrm_proto_ah_failed;
        err = xfrm6_protocol_register(&xfrmi_ipcomp6_protocol, IPPROTO_COMP);
        if (err < 0)
                goto xfrm_proto_comp_failed;
#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
        err = xfrm6_tunnel_register(&xfrmi_ipv6_handler, AF_INET6);
        if (err < 0)
                goto xfrm_tunnel_ipv6_failed;
        err = xfrm6_tunnel_register(&xfrmi_ip6ip_handler, AF_INET);
        if (err < 0)
                goto xfrm_tunnel_ip6ip_failed;
#endif

        return 0;

#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
xfrm_tunnel_ip6ip_failed:
        xfrm6_tunnel_deregister(&xfrmi_ipv6_handler, AF_INET6);
xfrm_tunnel_ipv6_failed:
        xfrm6_protocol_deregister(&xfrmi_ipcomp6_protocol, IPPROTO_COMP);
#endif
xfrm_proto_comp_failed:
        xfrm6_protocol_deregister(&xfrmi_ah6_protocol, IPPROTO_AH);
xfrm_proto_ah_failed:
        xfrm6_protocol_deregister(&xfrmi_esp6_protocol, IPPROTO_ESP);
xfrm_proto_esp_failed:
        return err;
}

static void xfrmi6_fini(void)
{
#if IS_REACHABLE(CONFIG_INET6_XFRM_TUNNEL)
        xfrm6_tunnel_deregister(&xfrmi_ip6ip_handler, AF_INET);
        xfrm6_tunnel_deregister(&xfrmi_ipv6_handler, AF_INET6);
#endif
        xfrm6_protocol_deregister(&xfrmi_ipcomp6_protocol, IPPROTO_COMP);
        xfrm6_protocol_deregister(&xfrmi_ah6_protocol, IPPROTO_AH);
        xfrm6_protocol_deregister(&xfrmi_esp6_protocol, IPPROTO_ESP);
}

static const struct xfrm_if_cb xfrm_if_cb = {
        .decode_session =       xfrmi_decode_session,
};

static int __init xfrmi_init(void)
{
        const char *msg;
        int err;

        pr_info("IPsec XFRM device driver\n");

        msg = "tunnel device";
        err = register_pernet_device(&xfrmi_net_ops);
        if (err < 0)
                goto pernet_dev_failed;

        msg = "xfrm4 protocols";
        err = xfrmi4_init();
        if (err < 0)
                goto xfrmi4_failed;

        msg = "xfrm6 protocols";
        err = xfrmi6_init();
        if (err < 0)
                goto xfrmi6_failed;


        msg = "netlink interface";
        err = rtnl_link_register(&xfrmi_link_ops);
        if (err < 0)
                goto rtnl_link_failed;

        err = register_xfrm_interface_bpf();
        if (err < 0)
                goto kfunc_failed;

        lwtunnel_encap_add_ops(&xfrmi_encap_ops, LWTUNNEL_ENCAP_XFRM);

        xfrm_if_register_cb(&xfrm_if_cb);

        return err;

kfunc_failed:
        rtnl_link_unregister(&xfrmi_link_ops);
rtnl_link_failed:
        xfrmi6_fini();
xfrmi6_failed:
        xfrmi4_fini();
xfrmi4_failed:
        unregister_pernet_device(&xfrmi_net_ops);
pernet_dev_failed:
        pr_err("xfrmi init: failed to register %s\n", msg);
        return err;
}

static void __exit xfrmi_fini(void)
{
        xfrm_if_unregister_cb();
        lwtunnel_encap_del_ops(&xfrmi_encap_ops, LWTUNNEL_ENCAP_XFRM);
        rtnl_link_unregister(&xfrmi_link_ops);
        xfrmi4_fini();
        xfrmi6_fini();
        unregister_pernet_device(&xfrmi_net_ops);
}

module_init(xfrmi_init);
module_exit(xfrmi_fini);
MODULE_LICENSE("GPL");
MODULE_ALIAS_RTNL_LINK("xfrm");
MODULE_ALIAS_NETDEV("xfrm0");
MODULE_AUTHOR("Steffen Klassert");
MODULE_DESCRIPTION("XFRM virtual interface");