ip_vs_conn.c

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/*
 * IPVS         An implementation of the IP virtual server support for the
 *              LINUX operating system.  IPVS is now implemented as a module
 *              over the Netfilter framework. IPVS can be used to build a
 *              high-performance and highly available server based on a
 *              cluster of servers.
 *
 * Authors:     Wensong Zhang <[email protected]>
 *              Peter Kese <[email protected]>
 *              Julian Anastasov <[email protected]>
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 *
 * The IPVS code for kernel 2.2 was done by Wensong Zhang and Peter Kese,
 * with changes/fixes from Julian Anastasov, Lars Marowsky-Bree, Horms
 * and others. Many code here is taken from IP MASQ code of kernel 2.2.
 *
 * Changes:
 *
 */

#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/net.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/proc_fs.h>      /* for proc_net_* */
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/jhash.h>
#include <linux/random.h>

#include <net/net_namespace.h>
#include <net/ip_vs.h>


#ifndef CONFIG_IP_VS_TAB_BITS
#define CONFIG_IP_VS_TAB_BITS   12
#endif

/*
 * Connection hash size. Default is what was selected at compile time.
*/
static int ip_vs_conn_tab_bits = CONFIG_IP_VS_TAB_BITS;
module_param_named(conn_tab_bits, ip_vs_conn_tab_bits, int, 0444);
MODULE_PARM_DESC(conn_tab_bits, "Set connections' hash size");

/* size and mask values */
int ip_vs_conn_tab_size __read_mostly;
static int ip_vs_conn_tab_mask __read_mostly;

/*
 *  Connection hash table: for input and output packets lookups of IPVS
 */
static struct hlist_head *ip_vs_conn_tab __read_mostly;

/*  SLAB cache for IPVS connections */
static struct kmem_cache *ip_vs_conn_cachep __read_mostly;

/*  counter for no client port connections */
static atomic_t ip_vs_conn_no_cport_cnt = ATOMIC_INIT(0);

/* random value for IPVS connection hash */
static unsigned int ip_vs_conn_rnd __read_mostly;

/*
 *  Fine locking granularity for big connection hash table
 */
#define CT_LOCKARRAY_BITS  5
#define CT_LOCKARRAY_SIZE  (1<<CT_LOCKARRAY_BITS)
#define CT_LOCKARRAY_MASK  (CT_LOCKARRAY_SIZE-1)

struct ip_vs_aligned_lock
{
    rwlock_t    l;
} __attribute__((__aligned__(SMP_CACHE_BYTES)));

/* lock array for conn table */
static struct ip_vs_aligned_lock
__ip_vs_conntbl_lock_array[CT_LOCKARRAY_SIZE] __cacheline_aligned;

static inline void ct_read_lock(unsigned int key)
{
    read_lock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_read_unlock(unsigned int key)
{
    read_unlock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_write_lock(unsigned int key)
{
    write_lock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_write_unlock(unsigned int key)
{
    write_unlock(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_read_lock_bh(unsigned int key)
{
    read_lock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_read_unlock_bh(unsigned int key)
{
    read_unlock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_write_lock_bh(unsigned int key)
{
    write_lock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_write_unlock_bh(unsigned int key)
{
    write_unlock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}


/*
 *  Returns hash value for IPVS connection entry
 */
static unsigned int ip_vs_conn_hashkey(struct net *net, int af, unsigned int proto,
                       const union nf_inet_addr *addr,
                       __be16 port)
{
#ifdef CONFIG_IP_VS_IPV6
    if (af == AF_INET6)
        return (jhash_3words(jhash(addr, 16, ip_vs_conn_rnd),
                    (__force u32)port, proto, ip_vs_conn_rnd) ^
            ((size_t)net>>8)) & ip_vs_conn_tab_mask;
#endif
    return (jhash_3words((__force u32)addr->ip, (__force u32)port, proto,
                ip_vs_conn_rnd) ^
        ((size_t)net>>8)) & ip_vs_conn_tab_mask;
}

static unsigned int ip_vs_conn_hashkey_param(const struct ip_vs_conn_param *p,
                         bool inverse)
{
    const union nf_inet_addr *addr;
    __be16 port;

    if (p->pe_data && p->pe->hashkey_raw)
        return p->pe->hashkey_raw(p, ip_vs_conn_rnd, inverse) &
            ip_vs_conn_tab_mask;

    if (likely(!inverse)) {
        addr = p->caddr;
        port = p->cport;
    } else {
        addr = p->vaddr;
        port = p->vport;
    }

    return ip_vs_conn_hashkey(p->net, p->af, p->protocol, addr, port);
}

static unsigned int ip_vs_conn_hashkey_conn(const struct ip_vs_conn *cp)
{
    struct ip_vs_conn_param p;

    ip_vs_conn_fill_param(ip_vs_conn_net(cp), cp->af, cp->protocol,
                  &cp->caddr, cp->cport, NULL, 0, &p);

    if (cp->pe) {
        p.pe = cp->pe;
        p.pe_data = cp->pe_data;
        p.pe_data_len = cp->pe_data_len;
    }

    return ip_vs_conn_hashkey_param(&p, false);
}

/*
 *  Hashes ip_vs_conn in ip_vs_conn_tab by netns,proto,addr,port.
 *  returns bool success.
 */
static inline int ip_vs_conn_hash(struct ip_vs_conn *cp)
{
    unsigned int hash;
    int ret;

    if (cp->flags & IP_VS_CONN_F_ONE_PACKET)
        return 0;

    /* Hash by protocol, client address and port */
    hash = ip_vs_conn_hashkey_conn(cp);

    ct_write_lock(hash);
    spin_lock(&cp->lock);

    if (!(cp->flags & IP_VS_CONN_F_HASHED)) {
        hlist_add_head(&cp->c_list, &ip_vs_conn_tab[hash]);
        cp->flags |= IP_VS_CONN_F_HASHED;
        atomic_inc(&cp->refcnt);
        ret = 1;
    } else {
        pr_err("%s(): request for already hashed, called from %pF\n",
               __func__, __builtin_return_address(0));
        ret = 0;
    }

    spin_unlock(&cp->lock);
    ct_write_unlock(hash);

    return ret;
}


/*
 *  UNhashes ip_vs_conn from ip_vs_conn_tab.
 *  returns bool success.
 */
static inline int ip_vs_conn_unhash(struct ip_vs_conn *cp)
{
    unsigned int hash;
    int ret;

    /* unhash it and decrease its reference counter */
    hash = ip_vs_conn_hashkey_conn(cp);

    ct_write_lock(hash);
    spin_lock(&cp->lock);

    if (cp->flags & IP_VS_CONN_F_HASHED) {
        hlist_del(&cp->c_list);
        cp->flags &= ~IP_VS_CONN_F_HASHED;
        atomic_dec(&cp->refcnt);
        ret = 1;
    } else
        ret = 0;

    spin_unlock(&cp->lock);
    ct_write_unlock(hash);

    return ret;
}


/*
 *  Gets ip_vs_conn associated with supplied parameters in the ip_vs_conn_tab.
 *  Called for pkts coming from OUTside-to-INside.
 *  p->caddr, p->cport: pkt source address (foreign host)
 *  p->vaddr, p->vport: pkt dest address (load balancer)
 */
static inline struct ip_vs_conn *
__ip_vs_conn_in_get(const struct ip_vs_conn_param *p)
{
    unsigned int hash;
    struct ip_vs_conn *cp;
    struct hlist_node *n;

    hash = ip_vs_conn_hashkey_param(p, false);

    ct_read_lock(hash);

    hlist_for_each_entry(cp, n, &ip_vs_conn_tab[hash], c_list) {
        if (cp->af == p->af &&
            p->cport == cp->cport && p->vport == cp->vport &&
            ip_vs_addr_equal(p->af, p->caddr, &cp->caddr) &&
            ip_vs_addr_equal(p->af, p->vaddr, &cp->vaddr) &&
            ((!p->cport) ^ (!(cp->flags & IP_VS_CONN_F_NO_CPORT))) &&
            p->protocol == cp->protocol &&
            ip_vs_conn_net_eq(cp, p->net)) {
            /* HIT */
            atomic_inc(&cp->refcnt);
            ct_read_unlock(hash);
            return cp;
        }
    }

    ct_read_unlock(hash);

    return NULL;
}

struct ip_vs_conn *ip_vs_conn_in_get(const struct ip_vs_conn_param *p)
{
    struct ip_vs_conn *cp;

    cp = __ip_vs_conn_in_get(p);
    if (!cp && atomic_read(&ip_vs_conn_no_cport_cnt)) {
        struct ip_vs_conn_param cport_zero_p = *p;
        cport_zero_p.cport = 0;
        cp = __ip_vs_conn_in_get(&cport_zero_p);
    }

    IP_VS_DBG_BUF(9, "lookup/in %s %s:%d->%s:%d %s\n",
              ip_vs_proto_name(p->protocol),
              IP_VS_DBG_ADDR(p->af, p->caddr), ntohs(p->cport),
              IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
              cp ? "hit" : "not hit");

    return cp;
}

static int
ip_vs_conn_fill_param_proto(int af, const struct sk_buff *skb,
                const struct ip_vs_iphdr *iph,
                unsigned int proto_off, int inverse,
                struct ip_vs_conn_param *p)
{
    __be16 _ports[2], *pptr;
    struct net *net = skb_net(skb);

    pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
    if (pptr == NULL)
        return 1;

    if (likely(!inverse))
        ip_vs_conn_fill_param(net, af, iph->protocol, &iph->saddr,
                      pptr[0], &iph->daddr, pptr[1], p);
    else
        ip_vs_conn_fill_param(net, af, iph->protocol, &iph->daddr,
                      pptr[1], &iph->saddr, pptr[0], p);
    return 0;
}

struct ip_vs_conn *
ip_vs_conn_in_get_proto(int af, const struct sk_buff *skb,
            const struct ip_vs_iphdr *iph,
            unsigned int proto_off, int inverse)
{
    struct ip_vs_conn_param p;

    if (ip_vs_conn_fill_param_proto(af, skb, iph, proto_off, inverse, &p))
        return NULL;

    return ip_vs_conn_in_get(&p);
}
EXPORT_SYMBOL_GPL(ip_vs_conn_in_get_proto);

/* Get reference to connection template */
struct ip_vs_conn *ip_vs_ct_in_get(const struct ip_vs_conn_param *p)
{
    unsigned int hash;
    struct ip_vs_conn *cp;
    struct hlist_node *n;

    hash = ip_vs_conn_hashkey_param(p, false);

    ct_read_lock(hash);

    hlist_for_each_entry(cp, n, &ip_vs_conn_tab[hash], c_list) {
        if (!ip_vs_conn_net_eq(cp, p->net))
            continue;
        if (p->pe_data && p->pe->ct_match) {
            if (p->pe == cp->pe && p->pe->ct_match(p, cp))
                goto out;
            continue;
        }

        if (cp->af == p->af &&
            ip_vs_addr_equal(p->af, p->caddr, &cp->caddr) &&
            /* protocol should only be IPPROTO_IP if
             * p->vaddr is a fwmark */
            ip_vs_addr_equal(p->protocol == IPPROTO_IP ? AF_UNSPEC :
                     p->af, p->vaddr, &cp->vaddr) &&
            p->cport == cp->cport && p->vport == cp->vport &&
            cp->flags & IP_VS_CONN_F_TEMPLATE &&
            p->protocol == cp->protocol)
            goto out;
    }
    cp = NULL;

  out:
    if (cp)
        atomic_inc(&cp->refcnt);
    ct_read_unlock(hash);

    IP_VS_DBG_BUF(9, "template lookup/in %s %s:%d->%s:%d %s\n",
              ip_vs_proto_name(p->protocol),
              IP_VS_DBG_ADDR(p->af, p->caddr), ntohs(p->cport),
              IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
              cp ? "hit" : "not hit");

    return cp;
}

/* Gets ip_vs_conn associated with supplied parameters in the ip_vs_conn_tab.
 * Called for pkts coming from inside-to-OUTside.
 *  p->caddr, p->cport: pkt source address (inside host)
 *  p->vaddr, p->vport: pkt dest address (foreign host) */
struct ip_vs_conn *ip_vs_conn_out_get(const struct ip_vs_conn_param *p)
{
    unsigned int hash;
    struct ip_vs_conn *cp, *ret=NULL;
    struct hlist_node *n;

    /*
     *  Check for "full" addressed entries
     */
    hash = ip_vs_conn_hashkey_param(p, true);

    ct_read_lock(hash);

    hlist_for_each_entry(cp, n, &ip_vs_conn_tab[hash], c_list) {
        if (cp->af == p->af &&
            p->vport == cp->cport && p->cport == cp->dport &&
            ip_vs_addr_equal(p->af, p->vaddr, &cp->caddr) &&
            ip_vs_addr_equal(p->af, p->caddr, &cp->daddr) &&
            p->protocol == cp->protocol &&
            ip_vs_conn_net_eq(cp, p->net)) {
            /* HIT */
            atomic_inc(&cp->refcnt);
            ret = cp;
            break;
        }
    }

    ct_read_unlock(hash);

    IP_VS_DBG_BUF(9, "lookup/out %s %s:%d->%s:%d %s\n",
              ip_vs_proto_name(p->protocol),
              IP_VS_DBG_ADDR(p->af, p->caddr), ntohs(p->cport),
              IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
              ret ? "hit" : "not hit");

    return ret;
}

struct ip_vs_conn *
ip_vs_conn_out_get_proto(int af, const struct sk_buff *skb,
             const struct ip_vs_iphdr *iph,
             unsigned int proto_off, int inverse)
{
    struct ip_vs_conn_param p;

    if (ip_vs_conn_fill_param_proto(af, skb, iph, proto_off, inverse, &p))
        return NULL;

    return ip_vs_conn_out_get(&p);
}
EXPORT_SYMBOL_GPL(ip_vs_conn_out_get_proto);

/*
 *      Put back the conn and restart its timer with its timeout
 */
void ip_vs_conn_put(struct ip_vs_conn *cp)
{
    unsigned long t = (cp->flags & IP_VS_CONN_F_ONE_PACKET) ?
        0 : cp->timeout;
    mod_timer(&cp->timer, jiffies+t);

    __ip_vs_conn_put(cp);
}


/*
 *  Fill a no_client_port connection with a client port number
 */
void ip_vs_conn_fill_cport(struct ip_vs_conn *cp, __be16 cport)
{
    if (ip_vs_conn_unhash(cp)) {
        spin_lock(&cp->lock);
        if (cp->flags & IP_VS_CONN_F_NO_CPORT) {
            atomic_dec(&ip_vs_conn_no_cport_cnt);
            cp->flags &= ~IP_VS_CONN_F_NO_CPORT;
            cp->cport = cport;
        }
        spin_unlock(&cp->lock);

        /* hash on new dport */
        ip_vs_conn_hash(cp);
    }
}


/*
 *  Bind a connection entry with the corresponding packet_xmit.
 *  Called by ip_vs_conn_new.
 */
static inline void ip_vs_bind_xmit(struct ip_vs_conn *cp)
{
    switch (IP_VS_FWD_METHOD(cp)) {
    case IP_VS_CONN_F_MASQ:
        cp->packet_xmit = ip_vs_nat_xmit;
        break;

    case IP_VS_CONN_F_TUNNEL:
        cp->packet_xmit = ip_vs_tunnel_xmit;
        break;

    case IP_VS_CONN_F_DROUTE:
        cp->packet_xmit = ip_vs_dr_xmit;
        break;

    case IP_VS_CONN_F_LOCALNODE:
        cp->packet_xmit = ip_vs_null_xmit;
        break;

    case IP_VS_CONN_F_BYPASS:
        cp->packet_xmit = ip_vs_bypass_xmit;
        break;
    }
}

#ifdef CONFIG_IP_VS_IPV6
static inline void ip_vs_bind_xmit_v6(struct ip_vs_conn *cp)
{
    switch (IP_VS_FWD_METHOD(cp)) {
    case IP_VS_CONN_F_MASQ:
        cp->packet_xmit = ip_vs_nat_xmit_v6;
        break;

    case IP_VS_CONN_F_TUNNEL:
        cp->packet_xmit = ip_vs_tunnel_xmit_v6;
        break;

    case IP_VS_CONN_F_DROUTE:
        cp->packet_xmit = ip_vs_dr_xmit_v6;
        break;

    case IP_VS_CONN_F_LOCALNODE:
        cp->packet_xmit = ip_vs_null_xmit;
        break;

    case IP_VS_CONN_F_BYPASS:
        cp->packet_xmit = ip_vs_bypass_xmit_v6;
        break;
    }
}
#endif


static inline int ip_vs_dest_totalconns(struct ip_vs_dest *dest)
{
    return atomic_read(&dest->activeconns)
        + atomic_read(&dest->inactconns);
}

/*
 *  Bind a connection entry with a virtual service destination
 *  Called just after a new connection entry is created.
 */
static inline void
ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest *dest)
{
    unsigned int conn_flags;
    __u32 flags;

    /* if dest is NULL, then return directly */
    if (!dest)
        return;

    /* Increase the refcnt counter of the dest */
    atomic_inc(&dest->refcnt);

    conn_flags = atomic_read(&dest->conn_flags);
    if (cp->protocol != IPPROTO_UDP)
        conn_flags &= ~IP_VS_CONN_F_ONE_PACKET;
    flags = cp->flags;
    /* Bind with the destination and its corresponding transmitter */
    if (flags & IP_VS_CONN_F_SYNC) {
        /* if the connection is not template and is created
         * by sync, preserve the activity flag.
         */
        if (!(flags & IP_VS_CONN_F_TEMPLATE))
            conn_flags &= ~IP_VS_CONN_F_INACTIVE;
        /* connections inherit forwarding method from dest */
        flags &= ~(IP_VS_CONN_F_FWD_MASK | IP_VS_CONN_F_NOOUTPUT);
    }
    flags |= conn_flags;
    cp->flags = flags;
    cp->dest = dest;

    IP_VS_DBG_BUF(7, "Bind-dest %s c:%s:%d v:%s:%d "
              "d:%s:%d fwd:%c s:%u conn->flags:%X conn->refcnt:%d "
              "dest->refcnt:%d\n",
              ip_vs_proto_name(cp->protocol),
              IP_VS_DBG_ADDR(cp->af, &cp->caddr), ntohs(cp->cport),
              IP_VS_DBG_ADDR(cp->af, &cp->vaddr), ntohs(cp->vport),
              IP_VS_DBG_ADDR(cp->af, &cp->daddr), ntohs(cp->dport),
              ip_vs_fwd_tag(cp), cp->state,
              cp->flags, atomic_read(&cp->refcnt),
              atomic_read(&dest->refcnt));

    /* Update the connection counters */
    if (!(flags & IP_VS_CONN_F_TEMPLATE)) {
        /* It is a normal connection, so modify the counters
         * according to the flags, later the protocol can
         * update them on state change
         */
        if (!(flags & IP_VS_CONN_F_INACTIVE))
            atomic_inc(&dest->activeconns);
        else
            atomic_inc(&dest->inactconns);
    } else {
        /* It is a persistent connection/template, so increase
           the persistent connection counter */
        atomic_inc(&dest->persistconns);
    }

    if (dest->u_threshold != 0 &&
        ip_vs_dest_totalconns(dest) >= dest->u_threshold)
        dest->flags |= IP_VS_DEST_F_OVERLOAD;
}


/*
 * Check if there is a destination for the connection, if so
 * bind the connection to the destination.
 */
struct ip_vs_dest *ip_vs_try_bind_dest(struct ip_vs_conn *cp)
{
    struct ip_vs_dest *dest;

    dest = ip_vs_find_dest(ip_vs_conn_net(cp), cp->af, &cp->daddr,
                   cp->dport, &cp->vaddr, cp->vport,
                   cp->protocol, cp->fwmark, cp->flags);
    if (dest) {
        struct ip_vs_proto_data *pd;

        spin_lock(&cp->lock);
        if (cp->dest) {
            spin_unlock(&cp->lock);
            return dest;
        }

        /* Applications work depending on the forwarding method
         * but better to reassign them always when binding dest */
        if (cp->app)
            ip_vs_unbind_app(cp);

        ip_vs_bind_dest(cp, dest);
        spin_unlock(&cp->lock);

        /* Update its packet transmitter */
        cp->packet_xmit = NULL;
#ifdef CONFIG_IP_VS_IPV6
        if (cp->af == AF_INET6)
            ip_vs_bind_xmit_v6(cp);
        else
#endif
            ip_vs_bind_xmit(cp);

        pd = ip_vs_proto_data_get(ip_vs_conn_net(cp), cp->protocol);
        if (pd && atomic_read(&pd->appcnt))
            ip_vs_bind_app(cp, pd->pp);
    }
    return dest;
}


/*
 *  Unbind a connection entry with its VS destination
 *  Called by the ip_vs_conn_expire function.
 */
static inline void ip_vs_unbind_dest(struct ip_vs_conn *cp)
{
    struct ip_vs_dest *dest = cp->dest;

    if (!dest)
        return;

    IP_VS_DBG_BUF(7, "Unbind-dest %s c:%s:%d v:%s:%d "
              "d:%s:%d fwd:%c s:%u conn->flags:%X conn->refcnt:%d "
              "dest->refcnt:%d\n",
              ip_vs_proto_name(cp->protocol),
              IP_VS_DBG_ADDR(cp->af, &cp->caddr), ntohs(cp->cport),
              IP_VS_DBG_ADDR(cp->af, &cp->vaddr), ntohs(cp->vport),
              IP_VS_DBG_ADDR(cp->af, &cp->daddr), ntohs(cp->dport),
              ip_vs_fwd_tag(cp), cp->state,
              cp->flags, atomic_read(&cp->refcnt),
              atomic_read(&dest->refcnt));

    /* Update the connection counters */
    if (!(cp->flags & IP_VS_CONN_F_TEMPLATE)) {
        /* It is a normal connection, so decrease the inactconns
           or activeconns counter */
        if (cp->flags & IP_VS_CONN_F_INACTIVE) {
            atomic_dec(&dest->inactconns);
        } else {
            atomic_dec(&dest->activeconns);
        }
    } else {
        /* It is a persistent connection/template, so decrease
           the persistent connection counter */
        atomic_dec(&dest->persistconns);
    }

    if (dest->l_threshold != 0) {
        if (ip_vs_dest_totalconns(dest) < dest->l_threshold)
            dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
    } else if (dest->u_threshold != 0) {
        if (ip_vs_dest_totalconns(dest) * 4 < dest->u_threshold * 3)
            dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
    } else {
        if (dest->flags & IP_VS_DEST_F_OVERLOAD)
            dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
    }

    /*
     * Simply decrease the refcnt of the dest, because the
     * dest will be either in service's destination list
     * or in the trash.
     */
    atomic_dec(&dest->refcnt);
}

static int expire_quiescent_template(struct netns_ipvs *ipvs,
                     struct ip_vs_dest *dest)
{
#ifdef CONFIG_SYSCTL
    return ipvs->sysctl_expire_quiescent_template &&
        (atomic_read(&dest->weight) == 0);
#else
    return 0;
#endif
}

/*
 *  Checking if the destination of a connection template is available.
 *  If available, return 1, otherwise invalidate this connection
 *  template and return 0.
 */
int ip_vs_check_template(struct ip_vs_conn *ct)
{
    struct ip_vs_dest *dest = ct->dest;
    struct netns_ipvs *ipvs = net_ipvs(ip_vs_conn_net(ct));

    /*
     * Checking the dest server status.
     */
    if ((dest == NULL) ||
        !(dest->flags & IP_VS_DEST_F_AVAILABLE) ||
        expire_quiescent_template(ipvs, dest)) {
        IP_VS_DBG_BUF(9, "check_template: dest not available for "
                  "protocol %s s:%s:%d v:%s:%d "
                  "-> d:%s:%d\n",
                  ip_vs_proto_name(ct->protocol),
                  IP_VS_DBG_ADDR(ct->af, &ct->caddr),
                  ntohs(ct->cport),
                  IP_VS_DBG_ADDR(ct->af, &ct->vaddr),
                  ntohs(ct->vport),
                  IP_VS_DBG_ADDR(ct->af, &ct->daddr),
                  ntohs(ct->dport));

        /*
         * Invalidate the connection template
         */
        if (ct->vport != htons(0xffff)) {
            if (ip_vs_conn_unhash(ct)) {
                ct->dport = htons(0xffff);
                ct->vport = htons(0xffff);
                ct->cport = 0;
                ip_vs_conn_hash(ct);
            }
        }

        /*
         * Simply decrease the refcnt of the template,
         * don't restart its timer.
         */
        atomic_dec(&ct->refcnt);
        return 0;
    }
    return 1;
}

static void ip_vs_conn_expire(unsigned long data)
{
    struct ip_vs_conn *cp = (struct ip_vs_conn *)data;
    struct net *net = ip_vs_conn_net(cp);
    struct netns_ipvs *ipvs = net_ipvs(net);

    cp->timeout = 60*HZ;

    /*
     *  hey, I'm using it
     */
    atomic_inc(&cp->refcnt);

    /*
     *  do I control anybody?
     */
    if (atomic_read(&cp->n_control))
        goto expire_later;

    /*
     *  unhash it if it is hashed in the conn table
     */
    if (!ip_vs_conn_unhash(cp) && !(cp->flags & IP_VS_CONN_F_ONE_PACKET))
        goto expire_later;

    /*
     *  refcnt==1 implies I'm the only one referrer
     */
    if (likely(atomic_read(&cp->refcnt) == 1)) {
        /* delete the timer if it is activated by other users */
        if (timer_pending(&cp->timer))
            del_timer(&cp->timer);

        /* does anybody control me? */
        if (cp->control)
            ip_vs_control_del(cp);

        if (cp->flags & IP_VS_CONN_F_NFCT) {
            ip_vs_conn_drop_conntrack(cp);
            /* Do not access conntracks during subsys cleanup
             * because nf_conntrack_find_get can not be used after
             * conntrack cleanup for the net.
             */
            smp_rmb();
            if (ipvs->enable)
                ip_vs_conn_drop_conntrack(cp);
        }

        ip_vs_pe_put(cp->pe);
        kfree(cp->pe_data);
        if (unlikely(cp->app != NULL))
            ip_vs_unbind_app(cp);
        ip_vs_unbind_dest(cp);
        if (cp->flags & IP_VS_CONN_F_NO_CPORT)
            atomic_dec(&ip_vs_conn_no_cport_cnt);
        atomic_dec(&ipvs->conn_count);

        kmem_cache_free(ip_vs_conn_cachep, cp);
        return;
    }

    /* hash it back to the table */
    ip_vs_conn_hash(cp);

  expire_later:
    IP_VS_DBG(7, "delayed: conn->refcnt-1=%d conn->n_control=%d\n",
          atomic_read(&cp->refcnt)-1,
          atomic_read(&cp->n_control));

    if (ipvs->sync_state & IP_VS_STATE_MASTER)
        ip_vs_sync_conn(net, cp, sysctl_sync_threshold(ipvs));

    ip_vs_conn_put(cp);
}


void ip_vs_conn_expire_now(struct ip_vs_conn *cp)
{
    if (del_timer(&cp->timer))
        mod_timer(&cp->timer, jiffies);
}


/*
 *  Create a new connection entry and hash it into the ip_vs_conn_tab
 */
struct ip_vs_conn *
ip_vs_conn_new(const struct ip_vs_conn_param *p,
           const union nf_inet_addr *daddr, __be16 dport, unsigned int flags,
           struct ip_vs_dest *dest, __u32 fwmark)
{
    struct ip_vs_conn *cp;
    struct netns_ipvs *ipvs = net_ipvs(p->net);
    struct ip_vs_proto_data *pd = ip_vs_proto_data_get(p->net,
                               p->protocol);

    cp = kmem_cache_zalloc(ip_vs_conn_cachep, GFP_ATOMIC);
    if (cp == NULL) {
        IP_VS_ERR_RL("%s(): no memory\n", __func__);
        return NULL;
    }

    INIT_HLIST_NODE(&cp->c_list);
    setup_timer(&cp->timer, ip_vs_conn_expire, (unsigned long)cp);
    ip_vs_conn_net_set(cp, p->net);
    cp->af         = p->af;
    cp->protocol       = p->protocol;
    ip_vs_addr_copy(p->af, &cp->caddr, p->caddr);
    cp->cport      = p->cport;
    ip_vs_addr_copy(p->af, &cp->vaddr, p->vaddr);
    cp->vport      = p->vport;
    /* proto should only be IPPROTO_IP if d_addr is a fwmark */
    ip_vs_addr_copy(p->protocol == IPPROTO_IP ? AF_UNSPEC : p->af,
            &cp->daddr, daddr);
    cp->dport          = dport;
    cp->flags      = flags;
    cp->fwmark         = fwmark;
    if (flags & IP_VS_CONN_F_TEMPLATE && p->pe) {
        ip_vs_pe_get(p->pe);
        cp->pe = p->pe;
        cp->pe_data = p->pe_data;
        cp->pe_data_len = p->pe_data_len;
    }
    spin_lock_init(&cp->lock);

    /*
     * Set the entry is referenced by the current thread before hashing
     * it in the table, so that other thread run ip_vs_random_dropentry
     * but cannot drop this entry.
     */
    atomic_set(&cp->refcnt, 1);

    atomic_set(&cp->n_control, 0);
    atomic_set(&cp->in_pkts, 0);

    atomic_inc(&ipvs->conn_count);
    if (flags & IP_VS_CONN_F_NO_CPORT)
        atomic_inc(&ip_vs_conn_no_cport_cnt);

    /* Bind the connection with a destination server */
    ip_vs_bind_dest(cp, dest);

    /* Set its state and timeout */
    cp->state = 0;
    cp->timeout = 3*HZ;
    cp->sync_endtime = jiffies & ~3UL;

    /* Bind its packet transmitter */
#ifdef CONFIG_IP_VS_IPV6
    if (p->af == AF_INET6)
        ip_vs_bind_xmit_v6(cp);
    else
#endif
        ip_vs_bind_xmit(cp);

    if (unlikely(pd && atomic_read(&pd->appcnt)))
        ip_vs_bind_app(cp, pd->pp);

    /*
     * Allow conntrack to be preserved. By default, conntrack
     * is created and destroyed for every packet.
     * Sometimes keeping conntrack can be useful for
     * IP_VS_CONN_F_ONE_PACKET too.
     */

    if (ip_vs_conntrack_enabled(ipvs))
        cp->flags |= IP_VS_CONN_F_NFCT;

    /* Hash it in the ip_vs_conn_tab finally */
    ip_vs_conn_hash(cp);

    return cp;
}

/*
 *  /proc/net/ip_vs_conn entries
 */
#ifdef CONFIG_PROC_FS
struct ip_vs_iter_state {
    struct seq_net_private  p;
    struct hlist_head   *l;
};

static void *ip_vs_conn_array(struct seq_file *seq, loff_t pos)
{
    int idx;
    struct ip_vs_conn *cp;
    struct ip_vs_iter_state *iter = seq->private;
    struct hlist_node *n;

    for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {
        ct_read_lock_bh(idx);
        hlist_for_each_entry(cp, n, &ip_vs_conn_tab[idx], c_list) {
            if (pos-- == 0) {
                iter->l = &ip_vs_conn_tab[idx];
                return cp;
            }
        }
        ct_read_unlock_bh(idx);
    }

    return NULL;
}

static void *ip_vs_conn_seq_start(struct seq_file *seq, loff_t *pos)
{
    struct ip_vs_iter_state *iter = seq->private;

    iter->l = NULL;
    return *pos ? ip_vs_conn_array(seq, *pos - 1) :SEQ_START_TOKEN;
}

static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    struct ip_vs_conn *cp = v;
    struct ip_vs_iter_state *iter = seq->private;
    struct hlist_node *e;
    struct hlist_head *l = iter->l;
    int idx;

    ++*pos;
    if (v == SEQ_START_TOKEN)
        return ip_vs_conn_array(seq, 0);

    /* more on same hash chain? */
    if ((e = cp->c_list.next))
        return hlist_entry(e, struct ip_vs_conn, c_list);

    idx = l - ip_vs_conn_tab;
    ct_read_unlock_bh(idx);

    while (++idx < ip_vs_conn_tab_size) {
        ct_read_lock_bh(idx);
        hlist_for_each_entry(cp, e, &ip_vs_conn_tab[idx], c_list) {
            iter->l = &ip_vs_conn_tab[idx];
            return cp;
        }
        ct_read_unlock_bh(idx);
    }
    iter->l = NULL;
    return NULL;
}

static void ip_vs_conn_seq_stop(struct seq_file *seq, void *v)
{
    struct ip_vs_iter_state *iter = seq->private;
    struct hlist_head *l = iter->l;

    if (l)
        ct_read_unlock_bh(l - ip_vs_conn_tab);
}

static int ip_vs_conn_seq_show(struct seq_file *seq, void *v)
{

    if (v == SEQ_START_TOKEN)
        seq_puts(seq,
   "Pro FromIP   FPrt ToIP     TPrt DestIP   DPrt State       Expires PEName PEData\n");
    else {
        const struct ip_vs_conn *cp = v;
        struct net *net = seq_file_net(seq);
        char pe_data[IP_VS_PENAME_MAXLEN + IP_VS_PEDATA_MAXLEN + 3];
        size_t len = 0;

        if (!ip_vs_conn_net_eq(cp, net))
            return 0;
        if (cp->pe_data) {
            pe_data[0] = ' ';
            len = strlen(cp->pe->name);
            memcpy(pe_data + 1, cp->pe->name, len);
            pe_data[len + 1] = ' ';
            len += 2;
            len += cp->pe->show_pe_data(cp, pe_data + len);
        }
        pe_data[len] = '\0';

#ifdef CONFIG_IP_VS_IPV6
        if (cp->af == AF_INET6)
            seq_printf(seq, "%-3s %pI6 %04X %pI6 %04X "
                "%pI6 %04X %-11s %7lu%s\n",
                ip_vs_proto_name(cp->protocol),
                &cp->caddr.in6, ntohs(cp->cport),
                &cp->vaddr.in6, ntohs(cp->vport),
                &cp->daddr.in6, ntohs(cp->dport),
                ip_vs_state_name(cp->protocol, cp->state),
                (cp->timer.expires-jiffies)/HZ, pe_data);
        else
#endif
            seq_printf(seq,
                "%-3s %08X %04X %08X %04X"
                " %08X %04X %-11s %7lu%s\n",
                ip_vs_proto_name(cp->protocol),
                ntohl(cp->caddr.ip), ntohs(cp->cport),
                ntohl(cp->vaddr.ip), ntohs(cp->vport),
                ntohl(cp->daddr.ip), ntohs(cp->dport),
                ip_vs_state_name(cp->protocol, cp->state),
                (cp->timer.expires-jiffies)/HZ, pe_data);
    }
    return 0;
}

static const struct seq_operations ip_vs_conn_seq_ops = {
    .start = ip_vs_conn_seq_start,
    .next  = ip_vs_conn_seq_next,
    .stop  = ip_vs_conn_seq_stop,
    .show  = ip_vs_conn_seq_show,
};

static int ip_vs_conn_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &ip_vs_conn_seq_ops,
                sizeof(struct ip_vs_iter_state));
}

static const struct file_operations ip_vs_conn_fops = {
    .owner   = THIS_MODULE,
    .open    = ip_vs_conn_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release_net,
};

static const char *ip_vs_origin_name(unsigned int flags)
{
    if (flags & IP_VS_CONN_F_SYNC)
        return "SYNC";
    else
        return "LOCAL";
}

static int ip_vs_conn_sync_seq_show(struct seq_file *seq, void *v)
{

    if (v == SEQ_START_TOKEN)
        seq_puts(seq,
   "Pro FromIP   FPrt ToIP     TPrt DestIP   DPrt State       Origin Expires\n");
    else {
        const struct ip_vs_conn *cp = v;
        struct net *net = seq_file_net(seq);

        if (!ip_vs_conn_net_eq(cp, net))
            return 0;

#ifdef CONFIG_IP_VS_IPV6
        if (cp->af == AF_INET6)
            seq_printf(seq, "%-3s %pI6 %04X %pI6 %04X %pI6 %04X %-11s %-6s %7lu\n",
                ip_vs_proto_name(cp->protocol),
                &cp->caddr.in6, ntohs(cp->cport),
                &cp->vaddr.in6, ntohs(cp->vport),
                &cp->daddr.in6, ntohs(cp->dport),
                ip_vs_state_name(cp->protocol, cp->state),
                ip_vs_origin_name(cp->flags),
                (cp->timer.expires-jiffies)/HZ);
        else
#endif
            seq_printf(seq,
                "%-3s %08X %04X %08X %04X "
                "%08X %04X %-11s %-6s %7lu\n",
                ip_vs_proto_name(cp->protocol),
                ntohl(cp->caddr.ip), ntohs(cp->cport),
                ntohl(cp->vaddr.ip), ntohs(cp->vport),
                ntohl(cp->daddr.ip), ntohs(cp->dport),
                ip_vs_state_name(cp->protocol, cp->state),
                ip_vs_origin_name(cp->flags),
                (cp->timer.expires-jiffies)/HZ);
    }
    return 0;
}

static const struct seq_operations ip_vs_conn_sync_seq_ops = {
    .start = ip_vs_conn_seq_start,
    .next  = ip_vs_conn_seq_next,
    .stop  = ip_vs_conn_seq_stop,
    .show  = ip_vs_conn_sync_seq_show,
};

static int ip_vs_conn_sync_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &ip_vs_conn_sync_seq_ops,
                sizeof(struct ip_vs_iter_state));
}

static const struct file_operations ip_vs_conn_sync_fops = {
    .owner   = THIS_MODULE,
    .open    = ip_vs_conn_sync_open,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .release = seq_release_net,
};

#endif


/*
 *      Randomly drop connection entries before running out of memory
 */
static inline int todrop_entry(struct ip_vs_conn *cp)
{
    /*
     * The drop rate array needs tuning for real environments.
     * Called from timer bh only => no locking
     */
    static const char todrop_rate[9] = {0, 1, 2, 3, 4, 5, 6, 7, 8};
    static char todrop_counter[9] = {0};
    int i;

    /* if the conn entry hasn't lasted for 60 seconds, don't drop it.
       This will leave enough time for normal connection to get
       through. */
    if (time_before(cp->timeout + jiffies, cp->timer.expires + 60*HZ))
        return 0;

    /* Don't drop the entry if its number of incoming packets is not
       located in [0, 8] */
    i = atomic_read(&cp->in_pkts);
    if (i > 8 || i < 0) return 0;

    if (!todrop_rate[i]) return 0;
    if (--todrop_counter[i] > 0) return 0;

    todrop_counter[i] = todrop_rate[i];
    return 1;
}

/* Called from keventd and must protect itself from softirqs */
void ip_vs_random_dropentry(struct net *net)
{
    int idx;
    struct ip_vs_conn *cp;

    /*
     * Randomly scan 1/32 of the whole table every second
     */
    for (idx = 0; idx < (ip_vs_conn_tab_size>>5); idx++) {
        unsigned int hash = net_random() & ip_vs_conn_tab_mask;
        struct hlist_node *n;

        /*
         *  Lock is actually needed in this loop.
         */
        ct_write_lock_bh(hash);

        hlist_for_each_entry(cp, n, &ip_vs_conn_tab[hash], c_list) {
            if (cp->flags & IP_VS_CONN_F_TEMPLATE)
                /* connection template */
                continue;
            if (!ip_vs_conn_net_eq(cp, net))
                continue;
            if (cp->protocol == IPPROTO_TCP) {
                switch(cp->state) {
                case IP_VS_TCP_S_SYN_RECV:
                case IP_VS_TCP_S_SYNACK:
                    break;

                case IP_VS_TCP_S_ESTABLISHED:
                    if (todrop_entry(cp))
                        break;
                    continue;

                default:
                    continue;
                }
            } else {
                if (!todrop_entry(cp))
                    continue;
            }

            IP_VS_DBG(4, "del connection\n");
            ip_vs_conn_expire_now(cp);
            if (cp->control) {
                IP_VS_DBG(4, "del conn template\n");
                ip_vs_conn_expire_now(cp->control);
            }
        }
        ct_write_unlock_bh(hash);
    }
}


/*
 *      Flush all the connection entries in the ip_vs_conn_tab
 */
static void ip_vs_conn_flush(struct net *net)
{
    int idx;
    struct ip_vs_conn *cp;
    struct netns_ipvs *ipvs = net_ipvs(net);

flush_again:
    for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {
        struct hlist_node *n;

        /*
         *  Lock is actually needed in this loop.
         */
        ct_write_lock_bh(idx);

        hlist_for_each_entry(cp, n, &ip_vs_conn_tab[idx], c_list) {
            if (!ip_vs_conn_net_eq(cp, net))
                continue;
            IP_VS_DBG(4, "del connection\n");
            ip_vs_conn_expire_now(cp);
            if (cp->control) {
                IP_VS_DBG(4, "del conn template\n");
                ip_vs_conn_expire_now(cp->control);
            }
        }
        ct_write_unlock_bh(idx);
    }

    /* the counter may be not NULL, because maybe some conn entries
       are run by slow timer handler or unhashed but still referred */
    if (atomic_read(&ipvs->conn_count) != 0) {
        schedule();
        goto flush_again;
    }
}
/*
 * per netns init and exit
 */
int __net_init ip_vs_conn_net_init(struct net *net)
{
    struct netns_ipvs *ipvs = net_ipvs(net);

    atomic_set(&ipvs->conn_count, 0);

    proc_net_fops_create(net, "ip_vs_conn", 0, &ip_vs_conn_fops);
    proc_net_fops_create(net, "ip_vs_conn_sync", 0, &ip_vs_conn_sync_fops);
    return 0;
}

void __net_exit ip_vs_conn_net_cleanup(struct net *net)
{
    /* flush all the connection entries first */
    ip_vs_conn_flush(net);
    proc_net_remove(net, "ip_vs_conn");
    proc_net_remove(net, "ip_vs_conn_sync");
}

int __init ip_vs_conn_init(void)
{
    int idx;

    /* Compute size and mask */
    ip_vs_conn_tab_size = 1 << ip_vs_conn_tab_bits;
    ip_vs_conn_tab_mask = ip_vs_conn_tab_size - 1;

    /*
     * Allocate the connection hash table and initialize its list heads
     */
    ip_vs_conn_tab = vmalloc(ip_vs_conn_tab_size * sizeof(*ip_vs_conn_tab));
    if (!ip_vs_conn_tab)
        return -ENOMEM;

    /* Allocate ip_vs_conn slab cache */
    ip_vs_conn_cachep = kmem_cache_create("ip_vs_conn",
                          sizeof(struct ip_vs_conn), 0,
                          SLAB_HWCACHE_ALIGN, NULL);
    if (!ip_vs_conn_cachep) {
        vfree(ip_vs_conn_tab);
        return -ENOMEM;
    }

    pr_info("Connection hash table configured "
        "(size=%d, memory=%ldKbytes)\n",
        ip_vs_conn_tab_size,
        (long)(ip_vs_conn_tab_size*sizeof(struct list_head))/1024);
    IP_VS_DBG(0, "Each connection entry needs %Zd bytes at least\n",
          sizeof(struct ip_vs_conn));

    for (idx = 0; idx < ip_vs_conn_tab_size; idx++)
        INIT_HLIST_HEAD(&ip_vs_conn_tab[idx]);

    for (idx = 0; idx < CT_LOCKARRAY_SIZE; idx++)  {
        rwlock_init(&__ip_vs_conntbl_lock_array[idx].l);
    }

    /* calculate the random value for connection hash */
    get_random_bytes(&ip_vs_conn_rnd, sizeof(ip_vs_conn_rnd));

    return 0;
}

void ip_vs_conn_cleanup(void)
{
    /* Release the empty cache */
    kmem_cache_destroy(ip_vs_conn_cachep);
    vfree(ip_vs_conn_tab);
}