nf_conntrack_ecache.h

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/*
 * connection tracking event cache.
 */

#ifndef _NF_CONNTRACK_ECACHE_H
#define _NF_CONNTRACK_ECACHE_H
#include <net/netfilter/nf_conntrack.h>

#include <net/net_namespace.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_common.h>
#include <linux/netfilter/nf_conntrack_tuple_common.h>
#include <net/netfilter/nf_conntrack_extend.h>

struct nf_conntrack_ecache {
    unsigned long cache;    /* bitops want long */
    unsigned long missed;   /* missed events */
    u16 ctmask;     /* bitmask of ct events to be delivered */
    u16 expmask;        /* bitmask of expect events to be delivered */
    u32 portid;     /* netlink portid of destroyer */
    struct timer_list timeout;
};

static inline struct nf_conntrack_ecache *
nf_ct_ecache_find(const struct nf_conn *ct)
{
#ifdef CONFIG_NF_CONNTRACK_EVENTS
    return nf_ct_ext_find(ct, NF_CT_EXT_ECACHE);
#else
    return NULL;
#endif
}

static inline struct nf_conntrack_ecache *
nf_ct_ecache_ext_add(struct nf_conn *ct, u16 ctmask, u16 expmask, gfp_t gfp)
{
#ifdef CONFIG_NF_CONNTRACK_EVENTS
    struct net *net = nf_ct_net(ct);
    struct nf_conntrack_ecache *e;

    if (!ctmask && !expmask && net->ct.sysctl_events) {
        ctmask = ~0;
        expmask = ~0;
    }
    if (!ctmask && !expmask)
        return NULL;

    e = nf_ct_ext_add(ct, NF_CT_EXT_ECACHE, gfp);
    if (e) {
        e->ctmask  = ctmask;
        e->expmask = expmask;
    }
    return e;
#else
    return NULL;
#endif
};

#ifdef CONFIG_NF_CONNTRACK_EVENTS
/* This structure is passed to event handler */
struct nf_ct_event {
    struct nf_conn *ct;
    u32 portid;
    int report;
};

struct nf_ct_event_notifier {
    int (*fcn)(unsigned int events, struct nf_ct_event *item);
};

extern int nf_conntrack_register_notifier(struct net *net, struct nf_ct_event_notifier *nb);
extern void nf_conntrack_unregister_notifier(struct net *net, struct nf_ct_event_notifier *nb);

extern void nf_ct_deliver_cached_events(struct nf_conn *ct);

static inline void
nf_conntrack_event_cache(enum ip_conntrack_events event, struct nf_conn *ct)
{
    struct net *net = nf_ct_net(ct);
    struct nf_conntrack_ecache *e;

    if (!rcu_access_pointer(net->ct.nf_conntrack_event_cb))
        return;

    e = nf_ct_ecache_find(ct);
    if (e == NULL)
        return;

    set_bit(event, &e->cache);
}

static inline int
nf_conntrack_eventmask_report(unsigned int eventmask,
                  struct nf_conn *ct,
                  u32 portid,
                  int report)
{
    int ret = 0;
    struct net *net = nf_ct_net(ct);
    struct nf_ct_event_notifier *notify;
    struct nf_conntrack_ecache *e;

    rcu_read_lock();
    notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
    if (notify == NULL)
        goto out_unlock;

    e = nf_ct_ecache_find(ct);
    if (e == NULL)
        goto out_unlock;

    if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct)) {
        struct nf_ct_event item = {
            .ct     = ct,
            .portid = e->portid ? e->portid : portid,
            .report = report
        };
        /* This is a resent of a destroy event? If so, skip missed */
        unsigned long missed = e->portid ? 0 : e->missed;

        if (!((eventmask | missed) & e->ctmask))
            goto out_unlock;

        ret = notify->fcn(eventmask | missed, &item);
        if (unlikely(ret < 0 || missed)) {
            spin_lock_bh(&ct->lock);
            if (ret < 0) {
                /* This is a destroy event that has been
                 * triggered by a process, we store the PORTID
                 * to include it in the retransmission. */
                if (eventmask & (1 << IPCT_DESTROY) &&
                    e->portid == 0 && portid != 0)
                    e->portid = portid;
                else
                    e->missed |= eventmask;
            } else
                e->missed &= ~missed;
            spin_unlock_bh(&ct->lock);
        }
    }
out_unlock:
    rcu_read_unlock();
    return ret;
}

static inline int
nf_conntrack_event_report(enum ip_conntrack_events event, struct nf_conn *ct,
              u32 portid, int report)
{
    return nf_conntrack_eventmask_report(1 << event, ct, portid, report);
}

static inline int
nf_conntrack_event(enum ip_conntrack_events event, struct nf_conn *ct)
{
    return nf_conntrack_eventmask_report(1 << event, ct, 0, 0);
}

struct nf_exp_event {
    struct nf_conntrack_expect *exp;
    u32 portid;
    int report;
};

struct nf_exp_event_notifier {
    int (*fcn)(unsigned int events, struct nf_exp_event *item);
};

extern int nf_ct_expect_register_notifier(struct net *net, struct nf_exp_event_notifier *nb);
extern void nf_ct_expect_unregister_notifier(struct net *net, struct nf_exp_event_notifier *nb);

static inline void
nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
              struct nf_conntrack_expect *exp,
              u32 portid,
              int report)
{
    struct net *net = nf_ct_exp_net(exp);
    struct nf_exp_event_notifier *notify;
    struct nf_conntrack_ecache *e;

    rcu_read_lock();
    notify = rcu_dereference(net->ct.nf_expect_event_cb);
    if (notify == NULL)
        goto out_unlock;

    e = nf_ct_ecache_find(exp->master);
    if (e == NULL)
        goto out_unlock;

    if (e->expmask & (1 << event)) {
        struct nf_exp_event item = {
            .exp    = exp,
            .portid = portid,
            .report = report
        };
        notify->fcn(1 << event, &item);
    }
out_unlock:
    rcu_read_unlock();
}

static inline void
nf_ct_expect_event(enum ip_conntrack_expect_events event,
           struct nf_conntrack_expect *exp)
{
    nf_ct_expect_event_report(event, exp, 0, 0);
}

extern int nf_conntrack_ecache_init(struct net *net);
extern void nf_conntrack_ecache_fini(struct net *net);

#else /* CONFIG_NF_CONNTRACK_EVENTS */

static inline void nf_conntrack_event_cache(enum ip_conntrack_events event,
                        struct nf_conn *ct) {}
static inline int nf_conntrack_eventmask_report(unsigned int eventmask,
                        struct nf_conn *ct,
                        u32 portid,
                        int report) { return 0; }
static inline int nf_conntrack_event(enum ip_conntrack_events event,
                     struct nf_conn *ct) { return 0; }
static inline int nf_conntrack_event_report(enum ip_conntrack_events event,
                        struct nf_conn *ct,
                        u32 portid,
                        int report) { return 0; }
static inline void nf_ct_deliver_cached_events(const struct nf_conn *ct) {}
static inline void nf_ct_expect_event(enum ip_conntrack_expect_events event,
                      struct nf_conntrack_expect *exp) {}
static inline void nf_ct_expect_event_report(enum ip_conntrack_expect_events e,
                         struct nf_conntrack_expect *exp,
                         u32 portid,
                         int report) {}

static inline int nf_conntrack_ecache_init(struct net *net)
{
    return 0;
}

static inline void nf_conntrack_ecache_fini(struct net *net)
{
}
#endif /* CONFIG_NF_CONNTRACK_EVENTS */

#endif /*_NF_CONNTRACK_ECACHE_H*/