/*
 * Copyright (c) 2007-2014 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
 */

#include <linux/etherdevice.h>
#include <linux/if.h>
#include <linux/if_vlan.h>
#include <linux/jhash.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/percpu.h>
#include <linux/rcupdate.h>
#include <linux/rtnetlink.h>
#include <linux/compat.h>
#include <net/net_namespace.h>
#include <linux/module.h>

#include "datapath.h"
#include "vport.h"
#include "vport-internal_dev.h"

static LIST_HEAD(vport_ops_list);

/* Protected by RCU read lock for reading, ovs_mutex for writing. */
static struct hlist_head *dev_table;
#define VPORT_HASH_BUCKETS 1024

/**
 *      ovs_vport_init - initialize vport subsystem
 *
 * Called at module load time to initialize the vport subsystem.
 */
int ovs_vport_init(void)
{
        dev_table = kzalloc(VPORT_HASH_BUCKETS * sizeof(struct hlist_head),
                            GFP_KERNEL);
        if (!dev_table)
                return -ENOMEM;

        return 0;
}

/**
 *      ovs_vport_exit - shutdown vport subsystem
 *
 * Called at module exit time to shutdown the vport subsystem.
 */
void ovs_vport_exit(void)
{
        kfree(dev_table);
}

static struct hlist_head *hash_bucket(const struct net *net, const char *name)
{
        unsigned int hash = jhash(name, strlen(name), (unsigned long) net);
        return &dev_table[hash & (VPORT_HASH_BUCKETS - 1)];
}

int __ovs_vport_ops_register(struct vport_ops *ops)
{
        int err = -EEXIST;
        struct vport_ops *o;

        ovs_lock();
        list_for_each_entry(o, &vport_ops_list, list)
                if (ops->type == o->type)
                        goto errout;

        list_add_tail(&ops->list, &vport_ops_list);
        err = 0;
errout:
        ovs_unlock();
        return err;
}
EXPORT_SYMBOL_GPL(__ovs_vport_ops_register);

void ovs_vport_ops_unregister(struct vport_ops *ops)
{
        ovs_lock();
        list_del(&ops->list);
        ovs_unlock();
}
EXPORT_SYMBOL_GPL(ovs_vport_ops_unregister);

/**
 *      ovs_vport_locate - find a port that has already been created
 *
 * @name: name of port to find
 *
 * Must be called with ovs or RCU read lock.
 */
struct vport *ovs_vport_locate(const struct net *net, const char *name)
{
        struct hlist_head *bucket = hash_bucket(net, name);
        struct vport *vport;

        hlist_for_each_entry_rcu(vport, bucket, hash_node)
                if (!strcmp(name, ovs_vport_name(vport)) &&
                    net_eq(ovs_dp_get_net(vport->dp), net))
                        return vport;

        return NULL;
}

/**
 *      ovs_vport_alloc - allocate and initialize new vport
 *
 * @priv_size: Size of private data area to allocate.
 * @ops: vport device ops
 *
 * Allocate and initialize a new vport defined by @ops.  The vport will contain
 * a private data area of size @priv_size that can be accessed using
 * vport_priv().  vports that are no longer needed should be released with
 * vport_free().
 */
struct vport *ovs_vport_alloc(int priv_size, const struct vport_ops *ops,
                          const struct vport_parms *parms)
{
        struct vport *vport;
        size_t alloc_size;

        alloc_size = sizeof(struct vport);
        if (priv_size) {
                alloc_size = ALIGN(alloc_size, VPORT_ALIGN);
                alloc_size += priv_size;
        }

        vport = kzalloc(alloc_size, GFP_KERNEL);
        if (!vport)
                return ERR_PTR(-ENOMEM);

        vport->dp = parms->dp;
        vport->port_no = parms->port_no;
        vport->ops = ops;
        INIT_HLIST_NODE(&vport->dp_hash_node);

        if (ovs_vport_set_upcall_portids(vport, parms->upcall_portids)) {
                kfree(vport);
                return ERR_PTR(-EINVAL);
        }

        return vport;
}
EXPORT_SYMBOL_GPL(ovs_vport_alloc);

/**
 *      ovs_vport_free - uninitialize and free vport
 *
 * @vport: vport to free
 *
 * Frees a vport allocated with vport_alloc() when it is no longer needed.
 *
 * The caller must ensure that an RCU grace period has passed since the last
 * time @vport was in a datapath.
 */
void ovs_vport_free(struct vport *vport)
{
        /* vport is freed from RCU callback or error path, Therefore
         * it is safe to use raw dereference.
         */
        kfree(rcu_dereference_raw(vport->upcall_portids));
        kfree(vport);
}
EXPORT_SYMBOL_GPL(ovs_vport_free);

static struct vport_ops *ovs_vport_lookup(const struct vport_parms *parms)
{
        struct vport_ops *ops;

        list_for_each_entry(ops, &vport_ops_list, list)
                if (ops->type == parms->type)
                        return ops;

        return NULL;
}

/**
 *      ovs_vport_add - add vport device (for kernel callers)
 *
 * @parms: Information about new vport.
 *
 * Creates a new vport with the specified configuration (which is dependent on
 * device type).  ovs_mutex must be held.
 */
struct vport *ovs_vport_add(const struct vport_parms *parms)
{
        struct vport_ops *ops;
        struct vport *vport;

        ops = ovs_vport_lookup(parms);
        if (ops) {
                struct hlist_head *bucket;

                if (!try_module_get(ops->owner))
                        return ERR_PTR(-EAFNOSUPPORT);

                vport = ops->create(parms);
                if (IS_ERR(vport)) {
                        module_put(ops->owner);
                        return vport;
                }

                bucket = hash_bucket(ovs_dp_get_net(vport->dp),
                                     ovs_vport_name(vport));
                hlist_add_head_rcu(&vport->hash_node, bucket);
                return vport;
        }

        /* Unlock to attempt module load and return -EAGAIN if load
         * was successful as we need to restart the port addition
         * workflow.
         */
        ovs_unlock();
        request_module("vport-type-%d", parms->type);
        ovs_lock();

        if (!ovs_vport_lookup(parms))
                return ERR_PTR(-EAFNOSUPPORT);
        else
                return ERR_PTR(-EAGAIN);
}

/**
 *      ovs_vport_set_options - modify existing vport device (for kernel callers)
 *
 * @vport: vport to modify.
 * @options: New configuration.
 *
 * Modifies an existing device with the specified configuration (which is
 * dependent on device type).  ovs_mutex must be held.
 */
int ovs_vport_set_options(struct vport *vport, struct nlattr *options)
{
        if (!vport->ops->set_options)
                return -EOPNOTSUPP;
        return vport->ops->set_options(vport, options);
}

/**
 *      ovs_vport_del - delete existing vport device
 *
 * @vport: vport to delete.
 *
 * Detaches @vport from its datapath and destroys it.  ovs_mutex must
 * be held.
 */
void ovs_vport_del(struct vport *vport)
{
        ASSERT_OVSL();

        hlist_del_rcu(&vport->hash_node);
        module_put(vport->ops->owner);
        vport->ops->destroy(vport);
}

/**
 *      ovs_vport_get_stats - retrieve device stats
 *
 * @vport: vport from which to retrieve the stats
 * @stats: location to store stats
 *
 * Retrieves transmit, receive, and error stats for the given device.
 *
 * Must be called with ovs_mutex or rcu_read_lock.
 */
void ovs_vport_get_stats(struct vport *vport, struct ovs_vport_stats *stats)
{
        const struct rtnl_link_stats64 *dev_stats;
        struct rtnl_link_stats64 temp;

        dev_stats = dev_get_stats(vport->dev, &temp);
        stats->rx_errors  = dev_stats->rx_errors;
        stats->tx_errors  = dev_stats->tx_errors;
        stats->tx_dropped = dev_stats->tx_dropped;
        stats->rx_dropped = dev_stats->rx_dropped;

        stats->rx_bytes   = dev_stats->rx_bytes;
        stats->rx_packets = dev_stats->rx_packets;
        stats->tx_bytes   = dev_stats->tx_bytes;
        stats->tx_packets = dev_stats->tx_packets;
}

/**
 *      ovs_vport_get_options - retrieve device options
 *
 * @vport: vport from which to retrieve the options.
 * @skb: sk_buff where options should be appended.
 *
 * Retrieves the configuration of the given device, appending an
 * %OVS_VPORT_ATTR_OPTIONS attribute that in turn contains nested
 * vport-specific attributes to @skb.
 *
 * Returns 0 if successful, -EMSGSIZE if @skb has insufficient room, or another
 * negative error code if a real error occurred.  If an error occurs, @skb is
 * left unmodified.
 *
 * Must be called with ovs_mutex or rcu_read_lock.
 */
int ovs_vport_get_options(const struct vport *vport, struct sk_buff *skb)
{
        struct nlattr *nla;
        int err;

        if (!vport->ops->get_options)
                return 0;

        nla = nla_nest_start(skb, OVS_VPORT_ATTR_OPTIONS);
        if (!nla)
                return -EMSGSIZE;

        err = vport->ops->get_options(vport, skb);
        if (err) {
                nla_nest_cancel(skb, nla);
                return err;
        }

        nla_nest_end(skb, nla);
        return 0;
}

/**
 *      ovs_vport_set_upcall_portids - set upcall portids of @vport.
 *
 * @vport: vport to modify.
 * @ids: new configuration, an array of port ids.
 *
 * Sets the vport's upcall_portids to @ids.
 *
 * Returns 0 if successful, -EINVAL if @ids is zero length or cannot be parsed
 * as an array of U32.
 *
 * Must be called with ovs_mutex.
 */
int ovs_vport_set_upcall_portids(struct vport *vport, const struct nlattr *ids)
{
        struct vport_portids *old, *vport_portids;

        if (!nla_len(ids) || nla_len(ids) % sizeof(u32))
                return -EINVAL;

        old = ovsl_dereference(vport->upcall_portids);

        vport_portids = kmalloc(sizeof(*vport_portids) + nla_len(ids),
                                GFP_KERNEL);
        if (!vport_portids)
                return -ENOMEM;

        vport_portids->n_ids = nla_len(ids) / sizeof(u32);
        vport_portids->rn_ids = reciprocal_value(vport_portids->n_ids);
        nla_memcpy(vport_portids->ids, ids, nla_len(ids));

        rcu_assign_pointer(vport->upcall_portids, vport_portids);

        if (old)
                kfree_rcu(old, rcu);
        return 0;
}

/**
 *      ovs_vport_get_upcall_portids - get the upcall_portids of @vport.
 *
 * @vport: vport from which to retrieve the portids.
 * @skb: sk_buff where portids should be appended.
 *
 * Retrieves the configuration of the given vport, appending the
 * %OVS_VPORT_ATTR_UPCALL_PID attribute which is the array of upcall
 * portids to @skb.
 *
 * Returns 0 if successful, -EMSGSIZE if @skb has insufficient room.
 * If an error occurs, @skb is left unmodified.  Must be called with
 * ovs_mutex or rcu_read_lock.
 */
int ovs_vport_get_upcall_portids(const struct vport *vport,
                                 struct sk_buff *skb)
{
        struct vport_portids *ids;

        ids = rcu_dereference_ovsl(vport->upcall_portids);

        if (vport->dp->user_features & OVS_DP_F_VPORT_PIDS)
                return nla_put(skb, OVS_VPORT_ATTR_UPCALL_PID,
                               ids->n_ids * sizeof(u32), (void *)ids->ids);
        else
                return nla_put_u32(skb, OVS_VPORT_ATTR_UPCALL_PID, ids->ids[0]);
}

/**
 *      ovs_vport_find_upcall_portid - find the upcall portid to send upcall.
 *
 * @vport: vport from which the missed packet is received.
 * @skb: skb that the missed packet was received.
 *
 * Uses the skb_get_hash() to select the upcall portid to send the
 * upcall.
 *
 * Returns the portid of the target socket.  Must be called with rcu_read_lock.
 */
u32 ovs_vport_find_upcall_portid(const struct vport *vport, struct sk_buff *skb)
{
        struct vport_portids *ids;
        u32 ids_index;
        u32 hash;

        ids = rcu_dereference(vport->upcall_portids);

        if (ids->n_ids == 1 && ids->ids[0] == 0)
                return 0;

        hash = skb_get_hash(skb);
        ids_index = hash - ids->n_ids * reciprocal_divide(hash, ids->rn_ids);
        return ids->ids[ids_index];
}

/**
 *      ovs_vport_receive - pass up received packet to the datapath for processing
 *
 * @vport: vport that received the packet
 * @skb: skb that was received
 * @tun_key: tunnel (if any) that carried packet
 *
 * Must be called with rcu_read_lock.  The packet cannot be shared and
 * skb->data should point to the Ethernet header.
 */
int ovs_vport_receive(struct vport *vport, struct sk_buff *skb,
                      const struct ip_tunnel_info *tun_info)
{
        struct sw_flow_key key;
        int error;

        OVS_CB(skb)->input_vport = vport;
        OVS_CB(skb)->mru = 0;
        OVS_CB(skb)->cutlen = 0;
        if (unlikely(dev_net(skb->dev) != ovs_dp_get_net(vport->dp))) {
                u32 mark;

                mark = skb->mark;
                skb_scrub_packet(skb, true);
                skb->mark = mark;
                tun_info = NULL;
        }

        /* Extract flow from 'skb' into 'key'. */
        error = ovs_flow_key_extract(tun_info, skb, &key);
        if (unlikely(error)) {
                kfree_skb(skb);
                return error;
        }
        ovs_dp_process_packet(skb, &key);
        return 0;
}

static unsigned int packet_length(const struct sk_buff *skb,
                                  struct net_device *dev)
{
        unsigned int length = skb->len - dev->hard_header_len;

        if (!skb_vlan_tag_present(skb) &&
            eth_type_vlan(skb->protocol))
                length -= VLAN_HLEN;

        /* Don't subtract for multiple VLAN tags. Most (all?) drivers allow
         * (ETH_LEN + VLAN_HLEN) in addition to the mtu value, but almost none
         * account for 802.1ad. e.g. is_skb_forwardable().
         */

        return length;
}

void ovs_vport_send(struct vport *vport, struct sk_buff *skb, u8 mac_proto)
{
        int mtu = vport->dev->mtu;

        switch (vport->dev->type) {
        case ARPHRD_NONE:
                if (mac_proto == MAC_PROTO_ETHERNET) {
                        skb_reset_network_header(skb);
                        skb_reset_mac_len(skb);
                        skb->protocol = htons(ETH_P_TEB);
                } else if (mac_proto != MAC_PROTO_NONE) {
                        WARN_ON_ONCE(1);
                        goto drop;
                }
                break;
        case ARPHRD_ETHER:
                if (mac_proto != MAC_PROTO_ETHERNET)
                        goto drop;
                break;
        default:
                goto drop;
        }

        if (unlikely(packet_length(skb, vport->dev) > mtu &&
                     !skb_is_gso(skb))) {
                net_warn_ratelimited("%s: dropped over-mtu packet: %d > %d\n",
                                     vport->dev->name,
                                     packet_length(skb, vport->dev), mtu);
                vport->dev->stats.tx_errors++;
                goto drop;
        }

        skb->dev = vport->dev;
        vport->ops->send(skb);
        return;

drop:
        kfree_skb(skb);
}