/*
 * Copyright (c) 2007-2017 Nicira, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/openvswitch.h>
#include <linux/netfilter_ipv6.h>
#include <linux/sctp.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/in6.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>

#include <net/dst.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ip6_fib.h>
#include <net/checksum.h>
#include <net/dsfield.h>
#include <net/mpls.h>
#include <net/sctp/checksum.h>

#include "datapath.h"
#include "flow.h"
#include "conntrack.h"
#include "vport.h"

struct deferred_action {
        struct sk_buff *skb;
        const struct nlattr *actions;
        int actions_len;

        /* Store pkt_key clone when creating deferred action. */
        struct sw_flow_key pkt_key;
};

#define MAX_L2_LEN      (VLAN_ETH_HLEN + 3 * MPLS_HLEN)
struct ovs_frag_data {
        unsigned long dst;
        struct vport *vport;
        struct ovs_skb_cb cb;
        __be16 inner_protocol;
        u16 network_offset;     /* valid only for MPLS */
        u16 vlan_tci;
        __be16 vlan_proto;
        unsigned int l2_len;
        u8 mac_proto;
        u8 l2_data[MAX_L2_LEN];
};

static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage);

#define DEFERRED_ACTION_FIFO_SIZE 10
#define OVS_RECURSION_LIMIT 5
#define OVS_DEFERRED_ACTION_THRESHOLD (OVS_RECURSION_LIMIT - 2)
struct action_fifo {
        int head;
        int tail;
        /* Deferred action fifo queue storage. */
        struct deferred_action fifo[DEFERRED_ACTION_FIFO_SIZE];
};

struct action_flow_keys {
        struct sw_flow_key key[OVS_DEFERRED_ACTION_THRESHOLD];
};

static struct action_fifo __percpu *action_fifos;
static struct action_flow_keys __percpu *flow_keys;
static DEFINE_PER_CPU(int, exec_actions_level);

/* Make a clone of the 'key', using the pre-allocated percpu 'flow_keys'
 * space. Return NULL if out of key spaces.
 */
static struct sw_flow_key *clone_key(const struct sw_flow_key *key_)
{
        struct action_flow_keys *keys = this_cpu_ptr(flow_keys);
        int level = this_cpu_read(exec_actions_level);
        struct sw_flow_key *key = NULL;

        if (level <= OVS_DEFERRED_ACTION_THRESHOLD) {
                key = &keys->key[level - 1];
                *key = *key_;
        }

        return key;
}

static void action_fifo_init(struct action_fifo *fifo)
{
        fifo->head = 0;
        fifo->tail = 0;
}

static bool action_fifo_is_empty(const struct action_fifo *fifo)
{
        return (fifo->head == fifo->tail);
}

static struct deferred_action *action_fifo_get(struct action_fifo *fifo)
{
        if (action_fifo_is_empty(fifo))
                return NULL;

        return &fifo->fifo[fifo->tail++];
}

static struct deferred_action *action_fifo_put(struct action_fifo *fifo)
{
        if (fifo->head >= DEFERRED_ACTION_FIFO_SIZE - 1)
                return NULL;

        return &fifo->fifo[fifo->head++];
}

/* Return true if fifo is not full */
static struct deferred_action *add_deferred_actions(struct sk_buff *skb,
                                    const struct sw_flow_key *key,
                                    const struct nlattr *actions,
                                    const int actions_len)
{
        struct action_fifo *fifo;
        struct deferred_action *da;

        fifo = this_cpu_ptr(action_fifos);
        da = action_fifo_put(fifo);
        if (da) {
                da->skb = skb;
                da->actions = actions;
                da->actions_len = actions_len;
                da->pkt_key = *key;
        }

        return da;
}

static void invalidate_flow_key(struct sw_flow_key *key)
{
        key->mac_proto |= SW_FLOW_KEY_INVALID;
}

static bool is_flow_key_valid(const struct sw_flow_key *key)
{
        return !(key->mac_proto & SW_FLOW_KEY_INVALID);
}

static int clone_execute(struct datapath *dp, struct sk_buff *skb,
                         struct sw_flow_key *key,
                         u32 recirc_id,
                         const struct nlattr *actions, int len,
                         bool last, bool clone_flow_key);

static void update_ethertype(struct sk_buff *skb, struct ethhdr *hdr,
                             __be16 ethertype)
{
        if (skb->ip_summed == CHECKSUM_COMPLETE) {
                __be16 diff[] = { ~(hdr->h_proto), ethertype };

                skb->csum = ~csum_partial((char *)diff, sizeof(diff),
                                        ~skb->csum);
        }

        hdr->h_proto = ethertype;
}

static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
                     const struct ovs_action_push_mpls *mpls)
{
        struct mpls_shim_hdr *new_mpls_lse;

        /* Networking stack do not allow simultaneous Tunnel and MPLS GSO. */
        if (skb->encapsulation)
                return -ENOTSUPP;

        if (skb_cow_head(skb, MPLS_HLEN) < 0)
                return -ENOMEM;

        if (!skb->inner_protocol) {
                skb_set_inner_network_header(skb, skb->mac_len);
                skb_set_inner_protocol(skb, skb->protocol);
        }

        skb_push(skb, MPLS_HLEN);
        memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
                skb->mac_len);
        skb_reset_mac_header(skb);
        skb_set_network_header(skb, skb->mac_len);

        new_mpls_lse = mpls_hdr(skb);
        new_mpls_lse->label_stack_entry = mpls->mpls_lse;

        skb_postpush_rcsum(skb, new_mpls_lse, MPLS_HLEN);

        if (ovs_key_mac_proto(key) == MAC_PROTO_ETHERNET)
                update_ethertype(skb, eth_hdr(skb), mpls->mpls_ethertype);
        skb->protocol = mpls->mpls_ethertype;

        invalidate_flow_key(key);
        return 0;
}

static int pop_mpls(struct sk_buff *skb, struct sw_flow_key *key,
                    const __be16 ethertype)
{
        int err;

        err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
        if (unlikely(err))
                return err;

        skb_postpull_rcsum(skb, mpls_hdr(skb), MPLS_HLEN);

        memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
                skb->mac_len);

        __skb_pull(skb, MPLS_HLEN);
        skb_reset_mac_header(skb);
        skb_set_network_header(skb, skb->mac_len);

        if (ovs_key_mac_proto(key) == MAC_PROTO_ETHERNET) {
                struct ethhdr *hdr;

                /* mpls_hdr() is used to locate the ethertype field correctly in the
                 * presence of VLAN tags.
                 */
                hdr = (struct ethhdr *)((void *)mpls_hdr(skb) - ETH_HLEN);
                update_ethertype(skb, hdr, ethertype);
        }
        if (eth_p_mpls(skb->protocol))
                skb->protocol = ethertype;

        invalidate_flow_key(key);
        return 0;
}

static int set_mpls(struct sk_buff *skb, struct sw_flow_key *flow_key,
                    const __be32 *mpls_lse, const __be32 *mask)
{
        struct mpls_shim_hdr *stack;
        __be32 lse;
        int err;

        err = skb_ensure_writable(skb, skb->mac_len + MPLS_HLEN);
        if (unlikely(err))
                return err;

        stack = mpls_hdr(skb);
        lse = OVS_MASKED(stack->label_stack_entry, *mpls_lse, *mask);
        if (skb->ip_summed == CHECKSUM_COMPLETE) {
                __be32 diff[] = { ~(stack->label_stack_entry), lse };

                skb->csum = ~csum_partial((char *)diff, sizeof(diff),
                                          ~skb->csum);
        }

        stack->label_stack_entry = lse;
        flow_key->mpls.top_lse = lse;
        return 0;
}

static int pop_vlan(struct sk_buff *skb, struct sw_flow_key *key)
{
        int err;

        err = skb_vlan_pop(skb);
        if (skb_vlan_tag_present(skb)) {
                invalidate_flow_key(key);
        } else {
                key->eth.vlan.tci = 0;
                key->eth.vlan.tpid = 0;
        }
        return err;
}

static int push_vlan(struct sk_buff *skb, struct sw_flow_key *key,
                     const struct ovs_action_push_vlan *vlan)
{
        if (skb_vlan_tag_present(skb)) {
                invalidate_flow_key(key);
        } else {
                key->eth.vlan.tci = vlan->vlan_tci;
                key->eth.vlan.tpid = vlan->vlan_tpid;
        }
        return skb_vlan_push(skb, vlan->vlan_tpid,
                             ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
}

/* 'src' is already properly masked. */
static void ether_addr_copy_masked(u8 *dst_, const u8 *src_, const u8 *mask_)
{
        u16 *dst = (u16 *)dst_;
        const u16 *src = (const u16 *)src_;
        const u16 *mask = (const u16 *)mask_;

        OVS_SET_MASKED(dst[0], src[0], mask[0]);
        OVS_SET_MASKED(dst[1], src[1], mask[1]);
        OVS_SET_MASKED(dst[2], src[2], mask[2]);
}

static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *flow_key,
                        const struct ovs_key_ethernet *key,
                        const struct ovs_key_ethernet *mask)
{
        int err;

        err = skb_ensure_writable(skb, ETH_HLEN);
        if (unlikely(err))
                return err;

        skb_postpull_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);

        ether_addr_copy_masked(eth_hdr(skb)->h_source, key->eth_src,
                               mask->eth_src);
        ether_addr_copy_masked(eth_hdr(skb)->h_dest, key->eth_dst,
                               mask->eth_dst);

        skb_postpush_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);

        ether_addr_copy(flow_key->eth.src, eth_hdr(skb)->h_source);
        ether_addr_copy(flow_key->eth.dst, eth_hdr(skb)->h_dest);
        return 0;
}

/* pop_eth does not support VLAN packets as this action is never called
 * for them.
 */
static int pop_eth(struct sk_buff *skb, struct sw_flow_key *key)
{
        skb_pull_rcsum(skb, ETH_HLEN);
        skb_reset_mac_header(skb);
        skb_reset_mac_len(skb);

        /* safe right before invalidate_flow_key */
        key->mac_proto = MAC_PROTO_NONE;
        invalidate_flow_key(key);
        return 0;
}

static int push_eth(struct sk_buff *skb, struct sw_flow_key *key,
                    const struct ovs_action_push_eth *ethh)
{
        struct ethhdr *hdr;

        /* Add the new Ethernet header */
        if (skb_cow_head(skb, ETH_HLEN) < 0)
                return -ENOMEM;

        skb_push(skb, ETH_HLEN);
        skb_reset_mac_header(skb);
        skb_reset_mac_len(skb);

        hdr = eth_hdr(skb);
        ether_addr_copy(hdr->h_source, ethh->addresses.eth_src);
        ether_addr_copy(hdr->h_dest, ethh->addresses.eth_dst);
        hdr->h_proto = skb->protocol;

        skb_postpush_rcsum(skb, hdr, ETH_HLEN);

        /* safe right before invalidate_flow_key */
        key->mac_proto = MAC_PROTO_ETHERNET;
        invalidate_flow_key(key);
        return 0;
}

static void update_ip_l4_checksum(struct sk_buff *skb, struct iphdr *nh,
                                  __be32 addr, __be32 new_addr)
{
        int transport_len = skb->len - skb_transport_offset(skb);

        if (nh->frag_off & htons(IP_OFFSET))
                return;

        if (nh->protocol == IPPROTO_TCP) {
                if (likely(transport_len >= sizeof(struct tcphdr)))
                        inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
                                                 addr, new_addr, true);
        } else if (nh->protocol == IPPROTO_UDP) {
                if (likely(transport_len >= sizeof(struct udphdr))) {
                        struct udphdr *uh = udp_hdr(skb);

                        if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
                                inet_proto_csum_replace4(&uh->check, skb,
                                                         addr, new_addr, true);
                                if (!uh->check)
                                        uh->check = CSUM_MANGLED_0;
                        }
                }
        }
}

static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
                        __be32 *addr, __be32 new_addr)
{
        update_ip_l4_checksum(skb, nh, *addr, new_addr);
        csum_replace4(&nh->check, *addr, new_addr);
        skb_clear_hash(skb);
        *addr = new_addr;
}

static void update_ipv6_checksum(struct sk_buff *skb, u8 l4_proto,
                                 __be32 addr[4], const __be32 new_addr[4])
{
        int transport_len = skb->len - skb_transport_offset(skb);

        if (l4_proto == NEXTHDR_TCP) {
                if (likely(transport_len >= sizeof(struct tcphdr)))
                        inet_proto_csum_replace16(&tcp_hdr(skb)->check, skb,
                                                  addr, new_addr, true);
        } else if (l4_proto == NEXTHDR_UDP) {
                if (likely(transport_len >= sizeof(struct udphdr))) {
                        struct udphdr *uh = udp_hdr(skb);

                        if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
                                inet_proto_csum_replace16(&uh->check, skb,
                                                          addr, new_addr, true);
                                if (!uh->check)
                                        uh->check = CSUM_MANGLED_0;
                        }
                }
        } else if (l4_proto == NEXTHDR_ICMP) {
                if (likely(transport_len >= sizeof(struct icmp6hdr)))
                        inet_proto_csum_replace16(&icmp6_hdr(skb)->icmp6_cksum,
                                                  skb, addr, new_addr, true);
        }
}

static void mask_ipv6_addr(const __be32 old[4], const __be32 addr[4],
                           const __be32 mask[4], __be32 masked[4])
{
        masked[0] = OVS_MASKED(old[0], addr[0], mask[0]);
        masked[1] = OVS_MASKED(old[1], addr[1], mask[1]);
        masked[2] = OVS_MASKED(old[2], addr[2], mask[2]);
        masked[3] = OVS_MASKED(old[3], addr[3], mask[3]);
}

static void set_ipv6_addr(struct sk_buff *skb, u8 l4_proto,
                          __be32 addr[4], const __be32 new_addr[4],
                          bool recalculate_csum)
{
        if (recalculate_csum)
                update_ipv6_checksum(skb, l4_proto, addr, new_addr);

        skb_clear_hash(skb);
        memcpy(addr, new_addr, sizeof(__be32[4]));
}

static void set_ipv6_fl(struct ipv6hdr *nh, u32 fl, u32 mask)
{
        /* Bits 21-24 are always unmasked, so this retains their values. */
        OVS_SET_MASKED(nh->flow_lbl[0], (u8)(fl >> 16), (u8)(mask >> 16));
        OVS_SET_MASKED(nh->flow_lbl[1], (u8)(fl >> 8), (u8)(mask >> 8));
        OVS_SET_MASKED(nh->flow_lbl[2], (u8)fl, (u8)mask);
}

static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl,
                       u8 mask)
{
        new_ttl = OVS_MASKED(nh->ttl, new_ttl, mask);

        csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
        nh->ttl = new_ttl;
}

static int set_ipv4(struct sk_buff *skb, struct sw_flow_key *flow_key,
                    const struct ovs_key_ipv4 *key,
                    const struct ovs_key_ipv4 *mask)
{
        struct iphdr *nh;
        __be32 new_addr;
        int err;

        err = skb_ensure_writable(skb, skb_network_offset(skb) +
                                  sizeof(struct iphdr));
        if (unlikely(err))
                return err;

        nh = ip_hdr(skb);

        /* Setting an IP addresses is typically only a side effect of
         * matching on them in the current userspace implementation, so it
         * makes sense to check if the value actually changed.
         */
        if (mask->ipv4_src) {
                new_addr = OVS_MASKED(nh->saddr, key->ipv4_src, mask->ipv4_src);

                if (unlikely(new_addr != nh->saddr)) {
                        set_ip_addr(skb, nh, &nh->saddr, new_addr);
                        flow_key->ipv4.addr.src = new_addr;
                }
        }
        if (mask->ipv4_dst) {
                new_addr = OVS_MASKED(nh->daddr, key->ipv4_dst, mask->ipv4_dst);

                if (unlikely(new_addr != nh->daddr)) {
                        set_ip_addr(skb, nh, &nh->daddr, new_addr);
                        flow_key->ipv4.addr.dst = new_addr;
                }
        }
        if (mask->ipv4_tos) {
                ipv4_change_dsfield(nh, ~mask->ipv4_tos, key->ipv4_tos);
                flow_key->ip.tos = nh->tos;
        }
        if (mask->ipv4_ttl) {
                set_ip_ttl(skb, nh, key->ipv4_ttl, mask->ipv4_ttl);
                flow_key->ip.ttl = nh->ttl;
        }

        return 0;
}

static bool is_ipv6_mask_nonzero(const __be32 addr[4])
{
        return !!(addr[0] | addr[1] | addr[2] | addr[3]);
}

static int set_ipv6(struct sk_buff *skb, struct sw_flow_key *flow_key,
                    const struct ovs_key_ipv6 *key,
                    const struct ovs_key_ipv6 *mask)
{
        struct ipv6hdr *nh;
        int err;

        err = skb_ensure_writable(skb, skb_network_offset(skb) +
                                  sizeof(struct ipv6hdr));
        if (unlikely(err))
                return err;

        nh = ipv6_hdr(skb);

        /* Setting an IP addresses is typically only a side effect of
         * matching on them in the current userspace implementation, so it
         * makes sense to check if the value actually changed.
         */
        if (is_ipv6_mask_nonzero(mask->ipv6_src)) {
                __be32 *saddr = (__be32 *)&nh->saddr;
                __be32 masked[4];

                mask_ipv6_addr(saddr, key->ipv6_src, mask->ipv6_src, masked);

                if (unlikely(memcmp(saddr, masked, sizeof(masked)))) {
                        set_ipv6_addr(skb, flow_key->ip.proto, saddr, masked,
                                      true);
                        memcpy(&flow_key->ipv6.addr.src, masked,
                               sizeof(flow_key->ipv6.addr.src));
                }
        }
        if (is_ipv6_mask_nonzero(mask->ipv6_dst)) {
                unsigned int offset = 0;
                int flags = IP6_FH_F_SKIP_RH;
                bool recalc_csum = true;
                __be32 *daddr = (__be32 *)&nh->daddr;
                __be32 masked[4];

                mask_ipv6_addr(daddr, key->ipv6_dst, mask->ipv6_dst, masked);

                if (unlikely(memcmp(daddr, masked, sizeof(masked)))) {
                        if (ipv6_ext_hdr(nh->nexthdr))
                                recalc_csum = (ipv6_find_hdr(skb, &offset,
                                                             NEXTHDR_ROUTING,
                                                             NULL, &flags)
                                               != NEXTHDR_ROUTING);

                        set_ipv6_addr(skb, flow_key->ip.proto, daddr, masked,
                                      recalc_csum);
                        memcpy(&flow_key->ipv6.addr.dst, masked,
                               sizeof(flow_key->ipv6.addr.dst));
                }
        }
        if (mask->ipv6_tclass) {
                ipv6_change_dsfield(nh, ~mask->ipv6_tclass, key->ipv6_tclass);
                flow_key->ip.tos = ipv6_get_dsfield(nh);
        }
        if (mask->ipv6_label) {
                set_ipv6_fl(nh, ntohl(key->ipv6_label),
                            ntohl(mask->ipv6_label));
                flow_key->ipv6.label =
                    *(__be32 *)nh & htonl(IPV6_FLOWINFO_FLOWLABEL);
        }
        if (mask->ipv6_hlimit) {
                OVS_SET_MASKED(nh->hop_limit, key->ipv6_hlimit,
                               mask->ipv6_hlimit);
                flow_key->ip.ttl = nh->hop_limit;
        }
        return 0;
}

/* Must follow skb_ensure_writable() since that can move the skb data. */
static void set_tp_port(struct sk_buff *skb, __be16 *port,
                        __be16 new_port, __sum16 *check)
{
        inet_proto_csum_replace2(check, skb, *port, new_port, false);
        *port = new_port;
}

static int set_udp(struct sk_buff *skb, struct sw_flow_key *flow_key,
                   const struct ovs_key_udp *key,
                   const struct ovs_key_udp *mask)
{
        struct udphdr *uh;
        __be16 src, dst;
        int err;

        err = skb_ensure_writable(skb, skb_transport_offset(skb) +
                                  sizeof(struct udphdr));
        if (unlikely(err))
                return err;

        uh = udp_hdr(skb);
        /* Either of the masks is non-zero, so do not bother checking them. */
        src = OVS_MASKED(uh->source, key->udp_src, mask->udp_src);
        dst = OVS_MASKED(uh->dest, key->udp_dst, mask->udp_dst);

        if (uh->check && skb->ip_summed != CHECKSUM_PARTIAL) {
                if (likely(src != uh->source)) {
                        set_tp_port(skb, &uh->source, src, &uh->check);
                        flow_key->tp.src = src;
                }
                if (likely(dst != uh->dest)) {
                        set_tp_port(skb, &uh->dest, dst, &uh->check);
                        flow_key->tp.dst = dst;
                }

                if (unlikely(!uh->check))
                        uh->check = CSUM_MANGLED_0;
        } else {
                uh->source = src;
                uh->dest = dst;
                flow_key->tp.src = src;
                flow_key->tp.dst = dst;
        }

        skb_clear_hash(skb);

        return 0;
}

static int set_tcp(struct sk_buff *skb, struct sw_flow_key *flow_key,
                   const struct ovs_key_tcp *key,
                   const struct ovs_key_tcp *mask)
{
        struct tcphdr *th;
        __be16 src, dst;
        int err;

        err = skb_ensure_writable(skb, skb_transport_offset(skb) +
                                  sizeof(struct tcphdr));
        if (unlikely(err))
                return err;

        th = tcp_hdr(skb);
        src = OVS_MASKED(th->source, key->tcp_src, mask->tcp_src);
        if (likely(src != th->source)) {
                set_tp_port(skb, &th->source, src, &th->check);
                flow_key->tp.src = src;
        }
        dst = OVS_MASKED(th->dest, key->tcp_dst, mask->tcp_dst);
        if (likely(dst != th->dest)) {
                set_tp_port(skb, &th->dest, dst, &th->check);
                flow_key->tp.dst = dst;
        }
        skb_clear_hash(skb);

        return 0;
}

static int set_sctp(struct sk_buff *skb, struct sw_flow_key *flow_key,
                    const struct ovs_key_sctp *key,
                    const struct ovs_key_sctp *mask)
{
        unsigned int sctphoff = skb_transport_offset(skb);
        struct sctphdr *sh;
        __le32 old_correct_csum, new_csum, old_csum;
        int err;

        err = skb_ensure_writable(skb, sctphoff + sizeof(struct sctphdr));
        if (unlikely(err))
                return err;

        sh = sctp_hdr(skb);
        old_csum = sh->checksum;
        old_correct_csum = sctp_compute_cksum(skb, sctphoff);

        sh->source = OVS_MASKED(sh->source, key->sctp_src, mask->sctp_src);
        sh->dest = OVS_MASKED(sh->dest, key->sctp_dst, mask->sctp_dst);

        new_csum = sctp_compute_cksum(skb, sctphoff);

        /* Carry any checksum errors through. */
        sh->checksum = old_csum ^ old_correct_csum ^ new_csum;

        skb_clear_hash(skb);
        flow_key->tp.src = sh->source;
        flow_key->tp.dst = sh->dest;

        return 0;
}

static int ovs_vport_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
        struct ovs_frag_data *data = this_cpu_ptr(&ovs_frag_data_storage);
        struct vport *vport = data->vport;

        if (skb_cow_head(skb, data->l2_len) < 0) {
                kfree_skb(skb);
                return -ENOMEM;
        }

        __skb_dst_copy(skb, data->dst);
        *OVS_CB(skb) = data->cb;
        skb->inner_protocol = data->inner_protocol;
        skb->vlan_tci = data->vlan_tci;
        skb->vlan_proto = data->vlan_proto;

        /* Reconstruct the MAC header.  */
        skb_push(skb, data->l2_len);
        memcpy(skb->data, &data->l2_data, data->l2_len);
        skb_postpush_rcsum(skb, skb->data, data->l2_len);
        skb_reset_mac_header(skb);

        if (eth_p_mpls(skb->protocol)) {
                skb->inner_network_header = skb->network_header;
                skb_set_network_header(skb, data->network_offset);
                skb_reset_mac_len(skb);
        }

        ovs_vport_send(vport, skb, data->mac_proto);
        return 0;
}

static unsigned int
ovs_dst_get_mtu(const struct dst_entry *dst)
{
        return dst->dev->mtu;
}

static struct dst_ops ovs_dst_ops = {
        .family = AF_UNSPEC,
        .mtu = ovs_dst_get_mtu,
};

/* prepare_frag() is called once per (larger-than-MTU) frame; its inverse is
 * ovs_vport_output(), which is called once per fragmented packet.
 */
static void prepare_frag(struct vport *vport, struct sk_buff *skb,
                         u16 orig_network_offset, u8 mac_proto)
{
        unsigned int hlen = skb_network_offset(skb);
        struct ovs_frag_data *data;

        data = this_cpu_ptr(&ovs_frag_data_storage);
        data->dst = skb->_skb_refdst;
        data->vport = vport;
        data->cb = *OVS_CB(skb);
        data->inner_protocol = skb->inner_protocol;
        data->network_offset = orig_network_offset;
        data->vlan_tci = skb->vlan_tci;
        data->vlan_proto = skb->vlan_proto;
        data->mac_proto = mac_proto;
        data->l2_len = hlen;
        memcpy(&data->l2_data, skb->data, hlen);

        memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
        skb_pull(skb, hlen);
}

static void ovs_fragment(struct net *net, struct vport *vport,
                         struct sk_buff *skb, u16 mru,
                         struct sw_flow_key *key)
{
        u16 orig_network_offset = 0;

        if (eth_p_mpls(skb->protocol)) {
                orig_network_offset = skb_network_offset(skb);
                skb->network_header = skb->inner_network_header;
        }

        if (skb_network_offset(skb) > MAX_L2_LEN) {
                OVS_NLERR(1, "L2 header too long to fragment");
                goto err;
        }

        if (key->eth.type == htons(ETH_P_IP)) {
                struct dst_entry ovs_dst;
                unsigned long orig_dst;

                prepare_frag(vport, skb, orig_network_offset,
                             ovs_key_mac_proto(key));
                dst_init(&ovs_dst, &ovs_dst_ops, NULL, 1,
                         DST_OBSOLETE_NONE, DST_NOCOUNT);
                ovs_dst.dev = vport->dev;

                orig_dst = skb->_skb_refdst;
                skb_dst_set_noref(skb, &ovs_dst);
                IPCB(skb)->frag_max_size = mru;

                ip_do_fragment(net, skb->sk, skb, ovs_vport_output);
                refdst_drop(orig_dst);
        } else if (key->eth.type == htons(ETH_P_IPV6)) {
                const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
                unsigned long orig_dst;
                struct rt6_info ovs_rt;

                if (!v6ops)
                        goto err;

                prepare_frag(vport, skb, orig_network_offset,
                             ovs_key_mac_proto(key));
                memset(&ovs_rt, 0, sizeof(ovs_rt));
                dst_init(&ovs_rt.dst, &ovs_dst_ops, NULL, 1,
                         DST_OBSOLETE_NONE, DST_NOCOUNT);
                ovs_rt.dst.dev = vport->dev;

                orig_dst = skb->_skb_refdst;
                skb_dst_set_noref(skb, &ovs_rt.dst);
                IP6CB(skb)->frag_max_size = mru;

                v6ops->fragment(net, skb->sk, skb, ovs_vport_output);
                refdst_drop(orig_dst);
        } else {
                WARN_ONCE(1, "Failed fragment ->%s: eth=%04x, MRU=%d, MTU=%d.",
                          ovs_vport_name(vport), ntohs(key->eth.type), mru,
                          vport->dev->mtu);
                goto err;
        }

        return;
err:
        kfree_skb(skb);
}

static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
                      struct sw_flow_key *key)
{
        struct vport *vport = ovs_vport_rcu(dp, out_port);

        if (likely(vport)) {
                u16 mru = OVS_CB(skb)->mru;
                u32 cutlen = OVS_CB(skb)->cutlen;

                if (unlikely(cutlen > 0)) {
                        if (skb->len - cutlen > ovs_mac_header_len(key))
                                pskb_trim(skb, skb->len - cutlen);
                        else
                                pskb_trim(skb, ovs_mac_header_len(key));
                }

                if (likely(!mru ||
                           (skb->len <= mru + vport->dev->hard_header_len))) {
                        ovs_vport_send(vport, skb, ovs_key_mac_proto(key));
                } else if (mru <= vport->dev->mtu) {
                        struct net *net = read_pnet(&dp->net);

                        ovs_fragment(net, vport, skb, mru, key);
                } else {
                        kfree_skb(skb);
                }
        } else {
                kfree_skb(skb);
        }
}

static int output_userspace(struct datapath *dp, struct sk_buff *skb,
                            struct sw_flow_key *key, const struct nlattr *attr,
                            const struct nlattr *actions, int actions_len,
                            uint32_t cutlen)
{
        struct dp_upcall_info upcall;
        const struct nlattr *a;
        int rem;

        memset(&upcall, 0, sizeof(upcall));
        upcall.cmd = OVS_PACKET_CMD_ACTION;
        upcall.mru = OVS_CB(skb)->mru;

        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
                 a = nla_next(a, &rem)) {
                switch (nla_type(a)) {
                case OVS_USERSPACE_ATTR_USERDATA:
                        upcall.userdata = a;
                        break;

                case OVS_USERSPACE_ATTR_PID:
                        upcall.portid = nla_get_u32(a);
                        break;

                case OVS_USERSPACE_ATTR_EGRESS_TUN_PORT: {
                        /* Get out tunnel info. */
                        struct vport *vport;

                        vport = ovs_vport_rcu(dp, nla_get_u32(a));
                        if (vport) {
                                int err;

                                err = dev_fill_metadata_dst(vport->dev, skb);
                                if (!err)
                                        upcall.egress_tun_info = skb_tunnel_info(skb);
                        }

                        break;
                }

                case OVS_USERSPACE_ATTR_ACTIONS: {
                        /* Include actions. */
                        upcall.actions = actions;
                        upcall.actions_len = actions_len;
                        break;
                }

                } /* End of switch. */
        }

        return ovs_dp_upcall(dp, skb, key, &upcall, cutlen);
}

/* When 'last' is true, sample() should always consume the 'skb'.
 * Otherwise, sample() should keep 'skb' intact regardless what
 * actions are executed within sample().
 */
static int sample(struct datapath *dp, struct sk_buff *skb,
                  struct sw_flow_key *key, const struct nlattr *attr,
                  bool last)
{
        struct nlattr *actions;
        struct nlattr *sample_arg;
        int rem = nla_len(attr);
        const struct sample_arg *arg;
        bool clone_flow_key;

        /* The first action is always 'OVS_SAMPLE_ATTR_ARG'. */
        sample_arg = nla_data(attr);
        arg = nla_data(sample_arg);
        actions = nla_next(sample_arg, &rem);

        if ((arg->probability != U32_MAX) &&
            (!arg->probability || prandom_u32() > arg->probability)) {
                if (last)
                        consume_skb(skb);
                return 0;
        }

        clone_flow_key = !arg->exec;
        return clone_execute(dp, skb, key, 0, actions, rem, last,
                             clone_flow_key);
}

static void execute_hash(struct sk_buff *skb, struct sw_flow_key *key,
                         const struct nlattr *attr)
{
        struct ovs_action_hash *hash_act = nla_data(attr);
        u32 hash = 0;

        /* OVS_HASH_ALG_L4 is the only possible hash algorithm.  */
        hash = skb_get_hash(skb);
        hash = jhash_1word(hash, hash_act->hash_basis);
        if (!hash)
                hash = 0x1;

        key->ovs_flow_hash = hash;
}

static int execute_set_action(struct sk_buff *skb,
                              struct sw_flow_key *flow_key,
                              const struct nlattr *a)
{
        /* Only tunnel set execution is supported without a mask. */
        if (nla_type(a) == OVS_KEY_ATTR_TUNNEL_INFO) {
                struct ovs_tunnel_info *tun = nla_data(a);

                skb_dst_drop(skb);
                dst_hold((struct dst_entry *)tun->tun_dst);
                skb_dst_set(skb, (struct dst_entry *)tun->tun_dst);
                return 0;
        }

        return -EINVAL;
}

/* Mask is at the midpoint of the data. */
#define get_mask(a, type) ((const type)nla_data(a) + 1)

static int execute_masked_set_action(struct sk_buff *skb,
                                     struct sw_flow_key *flow_key,

                                     const struct nlattr *a)
{
        int err = 0;

        switch (nla_type(a)) {
        case OVS_KEY_ATTR_PRIORITY:
                OVS_SET_MASKED(skb->priority, nla_get_u32(a),
                               *get_mask(a, u32 *));
                flow_key->phy.priority = skb->priority;
                break;

        case OVS_KEY_ATTR_SKB_MARK:
                OVS_SET_MASKED(skb->mark, nla_get_u32(a), *get_mask(a, u32 *));
                flow_key->phy.skb_mark = skb->mark;
                break;

        case OVS_KEY_ATTR_TUNNEL_INFO:
                /* Masked data not supported for tunnel. */
                err = -EINVAL;
                break;

        case OVS_KEY_ATTR_ETHERNET:
                err = set_eth_addr(skb, flow_key, nla_data(a),
                                   get_mask(a, struct ovs_key_ethernet *));
                break;

        case OVS_KEY_ATTR_IPV4:
                err = set_ipv4(skb, flow_key, nla_data(a),
                               get_mask(a, struct ovs_key_ipv4 *));
                break;

        case OVS_KEY_ATTR_IPV6:
                err = set_ipv6(skb, flow_key, nla_data(a),
                               get_mask(a, struct ovs_key_ipv6 *));
                break;

        case OVS_KEY_ATTR_TCP:
                err = set_tcp(skb, flow_key, nla_data(a),
                              get_mask(a, struct ovs_key_tcp *));
                break;

        case OVS_KEY_ATTR_UDP:
                err = set_udp(skb, flow_key, nla_data(a),
                              get_mask(a, struct ovs_key_udp *));
                break;

        case OVS_KEY_ATTR_SCTP:
                err = set_sctp(skb, flow_key, nla_data(a),
                               get_mask(a, struct ovs_key_sctp *));
                break;

        case OVS_KEY_ATTR_MPLS:
                err = set_mpls(skb, flow_key, nla_data(a), get_mask(a,
                                                                    __be32 *));
                break;

        case OVS_KEY_ATTR_CT_STATE:
        case OVS_KEY_ATTR_CT_ZONE:
        case OVS_KEY_ATTR_CT_MARK:
        case OVS_KEY_ATTR_CT_LABELS:
        case OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV4:
        case OVS_KEY_ATTR_CT_ORIG_TUPLE_IPV6:
                err = -EINVAL;
                break;
        }

        return err;
}

static int execute_recirc(struct datapath *dp, struct sk_buff *skb,
                          struct sw_flow_key *key,
                          const struct nlattr *a, bool last)
{
        u32 recirc_id;

        if (!is_flow_key_valid(key)) {
                int err;

                err = ovs_flow_key_update(skb, key);
                if (err)
                        return err;
        }
        BUG_ON(!is_flow_key_valid(key));

        recirc_id = nla_get_u32(a);
        return clone_execute(dp, skb, key, recirc_id, NULL, 0, last, true);
}

/* Execute a list of actions against 'skb'. */
static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
                              struct sw_flow_key *key,
                              const struct nlattr *attr, int len)
{
        const struct nlattr *a;
        int rem;

        for (a = attr, rem = len; rem > 0;
             a = nla_next(a, &rem)) {
                int err = 0;

                switch (nla_type(a)) {
                case OVS_ACTION_ATTR_OUTPUT: {
                        int port = nla_get_u32(a);
                        struct sk_buff *clone;

                        /* Every output action needs a separate clone
                         * of 'skb', In case the output action is the
                         * last action, cloning can be avoided.
                         */
                        if (nla_is_last(a, rem)) {
                                do_output(dp, skb, port, key);
                                /* 'skb' has been used for output.
                                 */
                                return 0;
                        }

                        clone = skb_clone(skb, GFP_ATOMIC);
                        if (clone)
                                do_output(dp, clone, port, key);
                        OVS_CB(skb)->cutlen = 0;
                        break;
                }

                case OVS_ACTION_ATTR_TRUNC: {
                        struct ovs_action_trunc *trunc = nla_data(a);

                        if (skb->len > trunc->max_len)
                                OVS_CB(skb)->cutlen = skb->len - trunc->max_len;
                        break;
                }

                case OVS_ACTION_ATTR_USERSPACE:
                        output_userspace(dp, skb, key, a, attr,
                                                     len, OVS_CB(skb)->cutlen);
                        OVS_CB(skb)->cutlen = 0;
                        break;

                case OVS_ACTION_ATTR_HASH:
                        execute_hash(skb, key, a);
                        break;

                case OVS_ACTION_ATTR_PUSH_MPLS:
                        err = push_mpls(skb, key, nla_data(a));
                        break;

                case OVS_ACTION_ATTR_POP_MPLS:
                        err = pop_mpls(skb, key, nla_get_be16(a));
                        break;

                case OVS_ACTION_ATTR_PUSH_VLAN:
                        err = push_vlan(skb, key, nla_data(a));
                        break;

                case OVS_ACTION_ATTR_POP_VLAN:
                        err = pop_vlan(skb, key);
                        break;

                case OVS_ACTION_ATTR_RECIRC: {
                        bool last = nla_is_last(a, rem);

                        err = execute_recirc(dp, skb, key, a, last);
                        if (last) {
                                /* If this is the last action, the skb has
                                 * been consumed or freed.
                                 * Return immediately.
                                 */
                                return err;
                        }
                        break;
                }

                case OVS_ACTION_ATTR_SET:
                        err = execute_set_action(skb, key, nla_data(a));
                        break;

                case OVS_ACTION_ATTR_SET_MASKED:
                case OVS_ACTION_ATTR_SET_TO_MASKED:
                        err = execute_masked_set_action(skb, key, nla_data(a));
                        break;

                case OVS_ACTION_ATTR_SAMPLE: {
                        bool last = nla_is_last(a, rem);

                        err = sample(dp, skb, key, a, last);
                        if (last)
                                return err;

                        break;
                }

                case OVS_ACTION_ATTR_CT:
                        if (!is_flow_key_valid(key)) {
                                err = ovs_flow_key_update(skb, key);
                                if (err)
                                        return err;
                        }

                        err = ovs_ct_execute(ovs_dp_get_net(dp), skb, key,
                                             nla_data(a));

                        /* Hide stolen IP fragments from user space. */
                        if (err)
                                return err == -EINPROGRESS ? 0 : err;
                        break;

                case OVS_ACTION_ATTR_PUSH_ETH:
                        err = push_eth(skb, key, nla_data(a));
                        break;

                case OVS_ACTION_ATTR_POP_ETH:
                        err = pop_eth(skb, key);
                        break;
                }

                if (unlikely(err)) {
                        kfree_skb(skb);
                        return err;
                }
        }

        consume_skb(skb);
        return 0;
}

/* Execute the actions on the clone of the packet. The effect of the
 * execution does not affect the original 'skb' nor the original 'key'.
 *
 * The execution may be deferred in case the actions can not be executed
 * immediately.
 */
static int clone_execute(struct datapath *dp, struct sk_buff *skb,
                         struct sw_flow_key *key, u32 recirc_id,
                         const struct nlattr *actions, int len,
                         bool last, bool clone_flow_key)
{
        struct deferred_action *da;
        struct sw_flow_key *clone;

        skb = last ? skb : skb_clone(skb, GFP_ATOMIC);
        if (!skb) {
                /* Out of memory, skip this action.
                 */
                return 0;
        }

        /* When clone_flow_key is false, the 'key' will not be change
         * by the actions, then the 'key' can be used directly.
         * Otherwise, try to clone key from the next recursion level of
         * 'flow_keys'. If clone is successful, execute the actions
         * without deferring.
         */
        clone = clone_flow_key ? clone_key(key) : key;
        if (clone) {
                int err = 0;

                if (actions) { /* Sample action */
                        if (clone_flow_key)
                                __this_cpu_inc(exec_actions_level);

                        err = do_execute_actions(dp, skb, clone,
                                                 actions, len);

                        if (clone_flow_key)
                                __this_cpu_dec(exec_actions_level);
                } else { /* Recirc action */
                        clone->recirc_id = recirc_id;
                        ovs_dp_process_packet(skb, clone);
                }
                return err;
        }

        /* Out of 'flow_keys' space. Defer actions */
        da = add_deferred_actions(skb, key, actions, len);
        if (da) {
                if (!actions) { /* Recirc action */
                        key = &da->pkt_key;
                        key->recirc_id = recirc_id;
                }
        } else {
                /* Out of per CPU action FIFO space. Drop the 'skb' and
                 * log an error.
                 */
                kfree_skb(skb);

                if (net_ratelimit()) {
                        if (actions) { /* Sample action */
                                pr_warn("%s: deferred action limit reached, drop sample action\n",
                                        ovs_dp_name(dp));
                        } else {  /* Recirc action */
                                pr_warn("%s: deferred action limit reached, drop recirc action\n",
                                        ovs_dp_name(dp));
                        }
                }
        }
        return 0;
}

static void process_deferred_actions(struct datapath *dp)
{
        struct action_fifo *fifo = this_cpu_ptr(action_fifos);

        /* Do not touch the FIFO in case there is no deferred actions. */
        if (action_fifo_is_empty(fifo))
                return;

        /* Finishing executing all deferred actions. */
        do {
                struct deferred_action *da = action_fifo_get(fifo);
                struct sk_buff *skb = da->skb;
                struct sw_flow_key *key = &da->pkt_key;
                const struct nlattr *actions = da->actions;
                int actions_len = da->actions_len;

                if (actions)
                        do_execute_actions(dp, skb, key, actions, actions_len);
                else
                        ovs_dp_process_packet(skb, key);
        } while (!action_fifo_is_empty(fifo));

        /* Reset FIFO for the next packet.  */
        action_fifo_init(fifo);
}

/* Execute a list of actions against 'skb'. */
int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
                        const struct sw_flow_actions *acts,
                        struct sw_flow_key *key)
{
        int err, level;

        level = __this_cpu_inc_return(exec_actions_level);
        if (unlikely(level > OVS_RECURSION_LIMIT)) {
                net_crit_ratelimited("ovs: recursion limit reached on datapath %s, probable configuration error\n",
                                     ovs_dp_name(dp));
                kfree_skb(skb);
                err = -ENETDOWN;
                goto out;
        }

        err = do_execute_actions(dp, skb, key,
                                 acts->actions, acts->actions_len);

        if (level == 1)
                process_deferred_actions(dp);

out:
        __this_cpu_dec(exec_actions_level);
        return err;
}

int action_fifos_init(void)
{
        action_fifos = alloc_percpu(struct action_fifo);
        if (!action_fifos)
                return -ENOMEM;

        flow_keys = alloc_percpu(struct action_flow_keys);
        if (!flow_keys) {
                free_percpu(action_fifos);
                return -ENOMEM;
        }

        return 0;
}

void action_fifos_exit(void)
{
        free_percpu(action_fifos);
        free_percpu(flow_keys);
}