// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * xfrm_device.c - IPsec device offloading code.
 *
 * Copyright (c) 2015 secunet Security Networks AG
 *
 * Author:
 * Steffen Klassert <steffen.klassert@secunet.com>
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <net/dst.h>
#include <net/gso.h>
#include <net/xfrm.h>
#include <linux/notifier.h>

#ifdef CONFIG_XFRM_OFFLOAD
static void __xfrm_transport_prep(struct xfrm_state *x, struct sk_buff *skb,
                                  unsigned int hsize)
{
        struct xfrm_offload *xo = xfrm_offload(skb);

        skb_reset_mac_len(skb);
        if (xo->flags & XFRM_GSO_SEGMENT)
                skb->transport_header -= x->props.header_len;

        pskb_pull(skb, skb_transport_offset(skb) + x->props.header_len);
}

static void __xfrm_mode_tunnel_prep(struct xfrm_state *x, struct sk_buff *skb,
                                    unsigned int hsize)

{
        struct xfrm_offload *xo = xfrm_offload(skb);

        if (xo->flags & XFRM_GSO_SEGMENT)
                skb->transport_header = skb->network_header + hsize;

        skb_reset_mac_len(skb);
        pskb_pull(skb,
                  skb->mac_len + x->props.header_len - x->props.enc_hdr_len);
}

static void __xfrm_mode_beet_prep(struct xfrm_state *x, struct sk_buff *skb,
                                  unsigned int hsize)
{
        struct xfrm_offload *xo = xfrm_offload(skb);
        int phlen = 0;

        if (xo->flags & XFRM_GSO_SEGMENT)
                skb->transport_header = skb->network_header + hsize;

        skb_reset_mac_len(skb);
        if (x->sel.family != AF_INET6) {
                phlen = IPV4_BEET_PHMAXLEN;
                if (x->outer_mode.family == AF_INET6)
                        phlen += sizeof(struct ipv6hdr) - sizeof(struct iphdr);
        }

        pskb_pull(skb, skb->mac_len + hsize + (x->props.header_len - phlen));
}

/* Adjust pointers into the packet when IPsec is done at layer2 */
static void xfrm_outer_mode_prep(struct xfrm_state *x, struct sk_buff *skb)
{
        switch (x->outer_mode.encap) {
        case XFRM_MODE_IPTFS:
        case XFRM_MODE_TUNNEL:
                if (x->outer_mode.family == AF_INET)
                        return __xfrm_mode_tunnel_prep(x, skb,
                                                       sizeof(struct iphdr));
                if (x->outer_mode.family == AF_INET6)
                        return __xfrm_mode_tunnel_prep(x, skb,
                                                       sizeof(struct ipv6hdr));
                break;
        case XFRM_MODE_TRANSPORT:
                if (x->outer_mode.family == AF_INET)
                        return __xfrm_transport_prep(x, skb,
                                                     sizeof(struct iphdr));
                if (x->outer_mode.family == AF_INET6)
                        return __xfrm_transport_prep(x, skb,
                                                     sizeof(struct ipv6hdr));
                break;
        case XFRM_MODE_BEET:
                if (x->outer_mode.family == AF_INET)
                        return __xfrm_mode_beet_prep(x, skb,
                                                     sizeof(struct iphdr));
                if (x->outer_mode.family == AF_INET6)
                        return __xfrm_mode_beet_prep(x, skb,
                                                     sizeof(struct ipv6hdr));
                break;
        case XFRM_MODE_ROUTEOPTIMIZATION:
        case XFRM_MODE_IN_TRIGGER:
                break;
        }
}

static inline bool xmit_xfrm_check_overflow(struct sk_buff *skb)
{
        struct xfrm_offload *xo = xfrm_offload(skb);
        __u32 seq = xo->seq.low;

        seq += skb_shinfo(skb)->gso_segs;
        if (unlikely(seq < xo->seq.low))
                return true;

        return false;
}

struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t features, bool *again)
{
        int err;
        unsigned long flags;
        struct xfrm_state *x;
        struct softnet_data *sd;
        struct sk_buff *skb2, *nskb, *pskb = NULL;
        netdev_features_t esp_features = features;
        struct xfrm_offload *xo = xfrm_offload(skb);
        struct net_device *dev = skb->dev;
        struct sec_path *sp;

        if (!xo || (xo->flags & XFRM_XMIT))
                return skb;

        if (!(features & NETIF_F_HW_ESP))
                esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);

        sp = skb_sec_path(skb);
        x = sp->xvec[sp->len - 1];
        if (xo->flags & XFRM_GRO || x->xso.dir == XFRM_DEV_OFFLOAD_IN)
                return skb;

        /* The packet was sent to HW IPsec packet offload engine,
         * but to wrong device. Drop the packet, so it won't skip
         * XFRM stack.
         */
        if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET && x->xso.dev != dev) {
                kfree_skb(skb);
                dev_core_stats_tx_dropped_inc(dev);
                return NULL;
        }

        local_irq_save(flags);
        sd = this_cpu_ptr(&softnet_data);
        err = !skb_queue_empty(&sd->xfrm_backlog);
        local_irq_restore(flags);

        if (err) {
                *again = true;
                return skb;
        }

        if (skb_is_gso(skb) && (unlikely(x->xso.dev != dev) ||
                                unlikely(xmit_xfrm_check_overflow(skb)))) {
                struct sk_buff *segs;

                /* Packet got rerouted, fixup features and segment it. */
                esp_features = esp_features & ~(NETIF_F_HW_ESP | NETIF_F_GSO_ESP);

                segs = skb_gso_segment(skb, esp_features);
                if (IS_ERR(segs)) {
                        kfree_skb(skb);
                        dev_core_stats_tx_dropped_inc(dev);
                        return NULL;
                } else {
                        consume_skb(skb);
                        skb = segs;
                }
        }

        if (!skb->next) {
                esp_features |= skb->dev->gso_partial_features;
                xfrm_outer_mode_prep(x, skb);

                xo->flags |= XFRM_DEV_RESUME;

                err = x->type_offload->xmit(x, skb, esp_features);
                if (err) {
                        if (err == -EINPROGRESS)
                                return NULL;

                        XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
                        kfree_skb(skb);
                        return NULL;
                }

                skb_push(skb, skb->data - skb_mac_header(skb));

                return skb;
        }

        skb_list_walk_safe(skb, skb2, nskb) {
                esp_features |= skb->dev->gso_partial_features;
                skb_mark_not_on_list(skb2);

                xo = xfrm_offload(skb2);
                xo->flags |= XFRM_DEV_RESUME;

                xfrm_outer_mode_prep(x, skb2);

                err = x->type_offload->xmit(x, skb2, esp_features);
                if (!err) {
                        skb2->next = nskb;
                } else if (err != -EINPROGRESS) {
                        XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
                        skb2->next = nskb;
                        kfree_skb_list(skb2);
                        return NULL;
                } else {
                        if (skb == skb2)
                                skb = nskb;
                        else
                                pskb->next = nskb;

                        continue;
                }

                skb_push(skb2, skb2->data - skb_mac_header(skb2));
                pskb = skb2;
        }

        return skb;
}
EXPORT_SYMBOL_GPL(validate_xmit_xfrm);

int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
                       struct xfrm_user_offload *xuo,
                       struct netlink_ext_ack *extack)
{
        int err;
        struct dst_entry *dst;
        struct net_device *dev;
        struct xfrm_dev_offload *xso = &x->xso;
        xfrm_address_t *saddr;
        xfrm_address_t *daddr;
        bool is_packet_offload;

        if (xuo->flags &
            ~(XFRM_OFFLOAD_IPV6 | XFRM_OFFLOAD_INBOUND | XFRM_OFFLOAD_PACKET)) {
                NL_SET_ERR_MSG(extack, "Unrecognized flags in offload request");
                return -EINVAL;
        }

        if ((xuo->flags & XFRM_OFFLOAD_INBOUND && x->dir == XFRM_SA_DIR_OUT) ||
            (!(xuo->flags & XFRM_OFFLOAD_INBOUND) && x->dir == XFRM_SA_DIR_IN)) {
                NL_SET_ERR_MSG(extack, "Mismatched SA and offload direction");
                return -EINVAL;
        }

        if (xuo->flags & XFRM_OFFLOAD_INBOUND && x->if_id) {
                NL_SET_ERR_MSG(extack, "XFRM if_id is not supported in RX path");
                return -EINVAL;
        }

        is_packet_offload = xuo->flags & XFRM_OFFLOAD_PACKET;

        /* We don't yet support TFC padding. */
        if (x->tfcpad) {
                NL_SET_ERR_MSG(extack, "TFC padding can't be offloaded");
                return -EINVAL;
        }

        dev = dev_get_by_index(net, xuo->ifindex);
        if (!dev) {
                struct xfrm_dst_lookup_params params;

                if (!(xuo->flags & XFRM_OFFLOAD_INBOUND)) {
                        saddr = &x->props.saddr;
                        daddr = &x->id.daddr;
                } else {
                        saddr = &x->id.daddr;
                        daddr = &x->props.saddr;
                }

                memset(&params, 0, sizeof(params));
                params.net = net;
                params.saddr = saddr;
                params.daddr = daddr;
                params.mark = xfrm_smark_get(0, x);
                dst = __xfrm_dst_lookup(x->props.family, &params);
                if (IS_ERR(dst))
                        return (is_packet_offload) ? -EINVAL : 0;

                dev = dst->dev;

                dev_hold(dev);
                dst_release(dst);
        }

        if (!dev->xfrmdev_ops || !dev->xfrmdev_ops->xdo_dev_state_add) {
                xso->dev = NULL;
                dev_put(dev);
                return (is_packet_offload) ? -EINVAL : 0;
        }

        if (!is_packet_offload && x->props.flags & XFRM_STATE_ESN &&
            !dev->xfrmdev_ops->xdo_dev_state_advance_esn) {
                NL_SET_ERR_MSG(extack, "Device doesn't support offload with ESN");
                xso->dev = NULL;
                dev_put(dev);
                return -EINVAL;
        }

        if (!x->type_offload) {
                NL_SET_ERR_MSG(extack, "Type doesn't support offload");
                dev_put(dev);
                return -EINVAL;
        }

        xso->dev = dev;
        netdev_tracker_alloc(dev, &xso->dev_tracker, GFP_ATOMIC);

        if (xuo->flags & XFRM_OFFLOAD_INBOUND)
                xso->dir = XFRM_DEV_OFFLOAD_IN;
        else
                xso->dir = XFRM_DEV_OFFLOAD_OUT;

        if (is_packet_offload)
                xso->type = XFRM_DEV_OFFLOAD_PACKET;
        else
                xso->type = XFRM_DEV_OFFLOAD_CRYPTO;

        err = dev->xfrmdev_ops->xdo_dev_state_add(dev, x, extack);
        if (err) {
                xso->dev = NULL;
                xso->dir = 0;
                netdev_put(dev, &xso->dev_tracker);
                xso->type = XFRM_DEV_OFFLOAD_UNSPECIFIED;

                xfrm_unset_type_offload(x);
                /* User explicitly requested packet offload mode and configured
                 * policy in addition to the XFRM state. So be civil to users,
                 * and return an error instead of taking fallback path.
                 */
                if ((err != -EOPNOTSUPP && !is_packet_offload) || is_packet_offload) {
                        NL_SET_ERR_MSG_WEAK(extack, "Device failed to offload this state");
                        return err;
                }
        }

        return 0;
}
EXPORT_SYMBOL_GPL(xfrm_dev_state_add);

int xfrm_dev_policy_add(struct net *net, struct xfrm_policy *xp,
                        struct xfrm_user_offload *xuo, u8 dir,
                        struct netlink_ext_ack *extack)
{
        struct xfrm_dev_offload *xdo = &xp->xdo;
        struct net_device *dev;
        int err;

        if (!xuo->flags || xuo->flags & ~XFRM_OFFLOAD_PACKET) {
                /* We support only packet offload mode and it means
                 * that user must set XFRM_OFFLOAD_PACKET bit.
                 */
                NL_SET_ERR_MSG(extack, "Unrecognized flags in offload request");
                return -EINVAL;
        }

        dev = dev_get_by_index(net, xuo->ifindex);
        if (!dev)
                return -EINVAL;

        if (!dev->xfrmdev_ops || !dev->xfrmdev_ops->xdo_dev_policy_add) {
                xdo->dev = NULL;
                dev_put(dev);
                NL_SET_ERR_MSG(extack, "Policy offload is not supported");
                return -EINVAL;
        }

        xdo->dev = dev;
        netdev_tracker_alloc(dev, &xdo->dev_tracker, GFP_ATOMIC);
        xdo->type = XFRM_DEV_OFFLOAD_PACKET;
        switch (dir) {
        case XFRM_POLICY_IN:
                xdo->dir = XFRM_DEV_OFFLOAD_IN;
                break;
        case XFRM_POLICY_OUT:
                xdo->dir = XFRM_DEV_OFFLOAD_OUT;
                break;
        case XFRM_POLICY_FWD:
                xdo->dir = XFRM_DEV_OFFLOAD_FWD;
                break;
        default:
                xdo->dev = NULL;
                netdev_put(dev, &xdo->dev_tracker);
                NL_SET_ERR_MSG(extack, "Unrecognized offload direction");
                return -EINVAL;
        }

        err = dev->xfrmdev_ops->xdo_dev_policy_add(xp, extack);
        if (err) {
                xdo->dev = NULL;
                xdo->type = XFRM_DEV_OFFLOAD_UNSPECIFIED;
                xdo->dir = 0;
                netdev_put(dev, &xdo->dev_tracker);
                NL_SET_ERR_MSG_WEAK(extack, "Device failed to offload this policy");
                return err;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(xfrm_dev_policy_add);

bool xfrm_dev_offload_ok(struct sk_buff *skb, struct xfrm_state *x)
{
        int mtu;
        struct dst_entry *dst = skb_dst(skb);
        struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
        struct net_device *dev = x->xso.dev;
        bool check_tunnel_size;

        if (!x->type_offload ||
            (x->xso.type == XFRM_DEV_OFFLOAD_UNSPECIFIED && x->encap))
                return false;

        if ((!dev || dev == xfrm_dst_path(dst)->dev) &&
            !xdst->child->xfrm) {
                mtu = xfrm_state_mtu(x, xdst->child_mtu_cached);
                if (skb->len <= mtu)
                        goto ok;

                if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
                        goto ok;
        }

        return false;

ok:
        if (!dev)
                return true;

        check_tunnel_size = x->xso.type == XFRM_DEV_OFFLOAD_PACKET &&
                            x->props.mode == XFRM_MODE_TUNNEL;
        switch (skb_dst(skb)->ops->family) {
        case AF_INET:
                /* Check for IPv4 options */
                if (ip_hdr(skb)->ihl != 5)
                        return false;
                if (check_tunnel_size && xfrm4_tunnel_check_size(skb))
                        return false;
                break;
        case AF_INET6:
                /* Check for IPv6 extensions */
                if (ipv6_ext_hdr(ipv6_hdr(skb)->nexthdr))
                        return false;
                if (check_tunnel_size && xfrm6_tunnel_check_size(skb))
                        return false;
                break;
        default:
                break;
        }

        if (dev->xfrmdev_ops->xdo_dev_offload_ok)
                return dev->xfrmdev_ops->xdo_dev_offload_ok(skb, x);

        return true;
}
EXPORT_SYMBOL_GPL(xfrm_dev_offload_ok);

void xfrm_dev_resume(struct sk_buff *skb)
{
        struct net_device *dev = skb->dev;
        int ret = NETDEV_TX_BUSY;
        struct netdev_queue *txq;
        struct softnet_data *sd;
        unsigned long flags;

        rcu_read_lock();
        txq = netdev_core_pick_tx(dev, skb, NULL);

        HARD_TX_LOCK(dev, txq, smp_processor_id());
        if (!netif_xmit_frozen_or_stopped(txq))
                skb = dev_hard_start_xmit(skb, dev, txq, &ret);
        HARD_TX_UNLOCK(dev, txq);

        if (!dev_xmit_complete(ret)) {
                local_irq_save(flags);
                sd = this_cpu_ptr(&softnet_data);
                skb_queue_tail(&sd->xfrm_backlog, skb);
                raise_softirq_irqoff(NET_TX_SOFTIRQ);
                local_irq_restore(flags);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(xfrm_dev_resume);

void xfrm_dev_backlog(struct softnet_data *sd)
{
        struct sk_buff_head *xfrm_backlog = &sd->xfrm_backlog;
        struct sk_buff_head list;
        struct sk_buff *skb;

        if (skb_queue_empty(xfrm_backlog))
                return;

        __skb_queue_head_init(&list);

        spin_lock(&xfrm_backlog->lock);
        skb_queue_splice_init(xfrm_backlog, &list);
        spin_unlock(&xfrm_backlog->lock);

        while (!skb_queue_empty(&list)) {
                skb = __skb_dequeue(&list);
                xfrm_dev_resume(skb);
        }

}
#endif

static int xfrm_api_check(struct net_device *dev)
{
#ifdef CONFIG_XFRM_OFFLOAD
        if ((dev->features & NETIF_F_HW_ESP_TX_CSUM) &&
            !(dev->features & NETIF_F_HW_ESP))
                return NOTIFY_BAD;

        if ((dev->features & NETIF_F_HW_ESP) &&
            (!(dev->xfrmdev_ops &&
               dev->xfrmdev_ops->xdo_dev_state_add &&
               dev->xfrmdev_ops->xdo_dev_state_delete)))
                return NOTIFY_BAD;
#else
        if (dev->features & (NETIF_F_HW_ESP | NETIF_F_HW_ESP_TX_CSUM))
                return NOTIFY_BAD;
#endif

        return NOTIFY_DONE;
}

static int xfrm_dev_down(struct net_device *dev)
{
        if (dev->features & NETIF_F_HW_ESP) {
                xfrm_dev_state_flush(dev_net(dev), dev, true);
                xfrm_dev_policy_flush(dev_net(dev), dev, true);
        }

        return NOTIFY_DONE;
}

static int xfrm_dev_unregister(struct net_device *dev)
{
        xfrm_dev_state_flush(dev_net(dev), dev, true);
        xfrm_dev_policy_flush(dev_net(dev), dev, true);

        return NOTIFY_DONE;
}

static int xfrm_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);

        switch (event) {
        case NETDEV_REGISTER:
                return xfrm_api_check(dev);

        case NETDEV_FEAT_CHANGE:
                return xfrm_api_check(dev);

        case NETDEV_DOWN:
                return xfrm_dev_down(dev);

        case NETDEV_UNREGISTER:
                return xfrm_dev_unregister(dev);
        }
        return NOTIFY_DONE;
}

static struct notifier_block xfrm_dev_notifier = {
        .notifier_call  = xfrm_dev_event,
};

void __init xfrm_dev_init(void)
{
        register_netdevice_notifier(&xfrm_dev_notifier);
}