/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _NET_NEIGHBOUR_H
#define _NET_NEIGHBOUR_H

#include <linux/neighbour.h>

/*
 *      Generic neighbour manipulation
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>
 *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
 *
 *      Changes:
 *
 *      Harald Welte:           <laforge@gnumonks.org>
 *              - Add neighbour cache statistics like rtstat
 */

#include <linux/atomic.h>
#include <linux/refcount.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/bitmap.h>

#include <linux/err.h>
#include <linux/sysctl.h>
#include <linux/workqueue.h>
#include <net/rtnetlink.h>
#include <net/neighbour_tables.h>

/*
 * NUD stands for "neighbor unreachability detection"
 */

#define NUD_IN_TIMER    (NUD_INCOMPLETE|NUD_REACHABLE|NUD_DELAY|NUD_PROBE)
#define NUD_VALID       (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE|NUD_PROBE|NUD_STALE|NUD_DELAY)
#define NUD_CONNECTED   (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE)

struct neighbour;

enum {
        NEIGH_VAR_MCAST_PROBES,
        NEIGH_VAR_UCAST_PROBES,
        NEIGH_VAR_APP_PROBES,
        NEIGH_VAR_MCAST_REPROBES,
        NEIGH_VAR_RETRANS_TIME,
        NEIGH_VAR_BASE_REACHABLE_TIME,
        NEIGH_VAR_DELAY_PROBE_TIME,
        NEIGH_VAR_INTERVAL_PROBE_TIME_MS,
        NEIGH_VAR_GC_STALETIME,
        NEIGH_VAR_QUEUE_LEN_BYTES,
        NEIGH_VAR_PROXY_QLEN,
        NEIGH_VAR_ANYCAST_DELAY,
        NEIGH_VAR_PROXY_DELAY,
        NEIGH_VAR_LOCKTIME,
#define NEIGH_VAR_DATA_MAX (NEIGH_VAR_LOCKTIME + 1)
        /* Following are used as a second way to access one of the above */
        NEIGH_VAR_QUEUE_LEN, /* same data as NEIGH_VAR_QUEUE_LEN_BYTES */
        NEIGH_VAR_RETRANS_TIME_MS, /* same data as NEIGH_VAR_RETRANS_TIME */
        NEIGH_VAR_BASE_REACHABLE_TIME_MS, /* same data as NEIGH_VAR_BASE_REACHABLE_TIME */
        /* Following are used by "default" only */
        NEIGH_VAR_GC_INTERVAL,
        NEIGH_VAR_GC_THRESH1,
        NEIGH_VAR_GC_THRESH2,
        NEIGH_VAR_GC_THRESH3,
        NEIGH_VAR_MAX
};

struct neigh_parms {
        possible_net_t net;
        struct net_device *dev;
        netdevice_tracker dev_tracker;
        struct list_head list;
        int     (*neigh_setup)(struct neighbour *);
        struct neigh_table *tbl;

        void    *sysctl_table;

        int dead;
        refcount_t refcnt;
        struct rcu_head rcu_head;

        int     reachable_time;
        u32     qlen;
        int     data[NEIGH_VAR_DATA_MAX];
        DECLARE_BITMAP(data_state, NEIGH_VAR_DATA_MAX);
};

static inline void neigh_var_set(struct neigh_parms *p, int index, int val)
{
        set_bit(index, p->data_state);
        WRITE_ONCE(p->data[index], val);
}

#define __NEIGH_VAR(p, attr) ((p)->data[NEIGH_VAR_ ## attr])
#define NEIGH_VAR(p, attr) READ_ONCE(__NEIGH_VAR(p, attr))
#define NEIGH_VAR_PTR(p, attr) (&(__NEIGH_VAR(p, attr)))

/* In ndo_neigh_setup, NEIGH_VAR_INIT should be used.
 * In other cases, NEIGH_VAR_SET should be used.
 */
#define NEIGH_VAR_INIT(p, attr, val) (__NEIGH_VAR(p, attr) = val)
#define NEIGH_VAR_SET(p, attr, val) neigh_var_set(p, NEIGH_VAR_ ## attr, val)

static inline void neigh_parms_data_state_setall(struct neigh_parms *p)
{
        bitmap_fill(p->data_state, NEIGH_VAR_DATA_MAX);
}

static inline void neigh_parms_data_state_cleanall(struct neigh_parms *p)
{
        bitmap_zero(p->data_state, NEIGH_VAR_DATA_MAX);
}

struct neigh_statistics {
        unsigned long allocs;           /* number of allocated neighs */
        unsigned long destroys;         /* number of destroyed neighs */
        unsigned long hash_grows;       /* number of hash resizes */

        unsigned long res_failed;       /* number of failed resolutions */

        unsigned long lookups;          /* number of lookups */
        unsigned long hits;             /* number of hits (among lookups) */

        unsigned long rcv_probes_mcast; /* number of received mcast ipv6 */
        unsigned long rcv_probes_ucast; /* number of received ucast ipv6 */

        unsigned long periodic_gc_runs; /* number of periodic GC runs */
        unsigned long forced_gc_runs;   /* number of forced GC runs */

        unsigned long unres_discards;   /* number of unresolved drops */
        unsigned long table_fulls;      /* times even gc couldn't help */
};

#define NEIGH_CACHE_STAT_INC(tbl, field) this_cpu_inc((tbl)->stats->field)

struct neighbour {
        struct hlist_node       hash;
        struct hlist_node       dev_list;
        struct neigh_table      *tbl;
        struct neigh_parms      *parms;
        unsigned long           confirmed;
        unsigned long           updated;
        rwlock_t                lock;
        refcount_t              refcnt;
        unsigned int            arp_queue_len_bytes;
        struct sk_buff_head     arp_queue;
        struct timer_list       timer;
        unsigned long           used;
        atomic_t                probes;
        u8                      nud_state;
        u8                      type;
        u8                      dead;
        u8                      protocol;
        u32                     flags;
        seqlock_t               ha_lock;
        unsigned char           ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))] __aligned(8);
        struct hh_cache         hh;
        int                     (*output)(struct neighbour *, struct sk_buff *);
        const struct neigh_ops  *ops;
        struct list_head        gc_list;
        struct list_head        managed_list;
        struct rcu_head         rcu;
        struct net_device       *dev;
        netdevice_tracker       dev_tracker;
        u8                      primary_key[];
} __randomize_layout;

struct neigh_ops {
        int                     family;
        void                    (*solicit)(struct neighbour *, struct sk_buff *);
        void                    (*error_report)(struct neighbour *, struct sk_buff *);
        int                     (*output)(struct neighbour *, struct sk_buff *);
        int                     (*connected_output)(struct neighbour *, struct sk_buff *);
};

struct pneigh_entry {
        struct pneigh_entry     __rcu *next;
        possible_net_t          net;
        struct net_device       *dev;
        netdevice_tracker       dev_tracker;
        union {
                struct list_head        free_node;
                struct rcu_head         rcu;
        };
        u32                     flags;
        u8                      protocol;
        bool                    permanent;
        u32                     key[];
};

/*
 *      neighbour table manipulation
 */

#define NEIGH_NUM_HASH_RND      4

struct neigh_hash_table {
        struct hlist_head       *hash_heads;
        unsigned int            hash_shift;
        __u32                   hash_rnd[NEIGH_NUM_HASH_RND];
        struct rcu_head         rcu;
};


struct neigh_table {
        int                     family;
        unsigned int            entry_size;
        unsigned int            key_len;
        __be16                  protocol;
        __u32                   (*hash)(const void *pkey,
                                        const struct net_device *dev,
                                        __u32 *hash_rnd);
        bool                    (*key_eq)(const struct neighbour *, const void *pkey);
        int                     (*constructor)(struct neighbour *);
        int                     (*pconstructor)(struct pneigh_entry *);
        void                    (*pdestructor)(struct pneigh_entry *);
        void                    (*proxy_redo)(struct sk_buff *skb);
        int                     (*is_multicast)(const void *pkey);
        bool                    (*allow_add)(const struct net_device *dev,
                                             struct netlink_ext_ack *extack);
        char                    *id;
        struct neigh_parms      parms;
        struct list_head        parms_list;
        int                     gc_interval;
        int                     gc_thresh1;
        int                     gc_thresh2;
        int                     gc_thresh3;
        unsigned long           last_flush;
        struct delayed_work     gc_work;
        struct delayed_work     managed_work;
        struct timer_list       proxy_timer;
        struct sk_buff_head     proxy_queue;
        atomic_t                entries;
        atomic_t                gc_entries;
        struct list_head        gc_list;
        struct list_head        managed_list;
        spinlock_t              lock;
        unsigned long           last_rand;
        struct neigh_statistics __percpu *stats;
        struct neigh_hash_table __rcu *nht;
        struct mutex            phash_lock;
        struct pneigh_entry     __rcu **phash_buckets;
};

static inline int neigh_parms_family(struct neigh_parms *p)
{
        return p->tbl->family;
}

#define NEIGH_PRIV_ALIGN        sizeof(long long)
#define NEIGH_ENTRY_SIZE(size)  ALIGN((size), NEIGH_PRIV_ALIGN)

static inline void *neighbour_priv(const struct neighbour *n)
{
        return (char *)n + n->tbl->entry_size;
}

/* flags for neigh_update() */
#define NEIGH_UPDATE_F_OVERRIDE                 BIT(0)
#define NEIGH_UPDATE_F_WEAK_OVERRIDE            BIT(1)
#define NEIGH_UPDATE_F_OVERRIDE_ISROUTER        BIT(2)
#define NEIGH_UPDATE_F_USE                      BIT(3)
#define NEIGH_UPDATE_F_MANAGED                  BIT(4)
#define NEIGH_UPDATE_F_EXT_LEARNED              BIT(5)
#define NEIGH_UPDATE_F_ISROUTER                 BIT(6)
#define NEIGH_UPDATE_F_ADMIN                    BIT(7)
#define NEIGH_UPDATE_F_EXT_VALIDATED            BIT(8)

/* In-kernel representation for NDA_FLAGS_EXT flags: */
#define NTF_OLD_MASK            0xff
#define NTF_EXT_SHIFT           8
#define NTF_EXT_MASK            (NTF_EXT_MANAGED | NTF_EXT_EXT_VALIDATED)

#define NTF_MANAGED             (NTF_EXT_MANAGED << NTF_EXT_SHIFT)
#define NTF_EXT_VALIDATED       (NTF_EXT_EXT_VALIDATED << NTF_EXT_SHIFT)

extern const struct nla_policy nda_policy[];

#define neigh_for_each_in_bucket(pos, head) hlist_for_each_entry(pos, head, hash)
#define neigh_for_each_in_bucket_rcu(pos, head) \
        hlist_for_each_entry_rcu(pos, head, hash)
#define neigh_for_each_in_bucket_safe(pos, tmp, head) \
        hlist_for_each_entry_safe(pos, tmp, head, hash)

static inline bool neigh_key_eq32(const struct neighbour *n, const void *pkey)
{
        return *(const u32 *)n->primary_key == *(const u32 *)pkey;
}

static inline bool neigh_key_eq128(const struct neighbour *n, const void *pkey)
{
        const u32 *n32 = (const u32 *)n->primary_key;
        const u32 *p32 = pkey;

        return ((n32[0] ^ p32[0]) | (n32[1] ^ p32[1]) |
                (n32[2] ^ p32[2]) | (n32[3] ^ p32[3])) == 0;
}

static inline struct neighbour *___neigh_lookup_noref(
        struct neigh_table *tbl,
        bool (*key_eq)(const struct neighbour *n, const void *pkey),
        __u32 (*hash)(const void *pkey,
                      const struct net_device *dev,
                      __u32 *hash_rnd),
        const void *pkey,
        struct net_device *dev)
{
        struct neigh_hash_table *nht = rcu_dereference(tbl->nht);
        struct neighbour *n;
        u32 hash_val;

        hash_val = hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift);
        neigh_for_each_in_bucket_rcu(n, &nht->hash_heads[hash_val])
                if (n->dev == dev && key_eq(n, pkey))
                        return n;

        return NULL;
}

static inline struct neighbour *__neigh_lookup_noref(struct neigh_table *tbl,
                                                     const void *pkey,
                                                     struct net_device *dev)
{
        return ___neigh_lookup_noref(tbl, tbl->key_eq, tbl->hash, pkey, dev);
}

static inline void neigh_confirm(struct neighbour *n)
{
        if (n) {
                unsigned long now = jiffies;

                /* avoid dirtying neighbour */
                if (READ_ONCE(n->confirmed) != now)
                        WRITE_ONCE(n->confirmed, now);
        }
}

void neigh_table_init(int index, struct neigh_table *tbl);
int neigh_table_clear(int index, struct neigh_table *tbl);
struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
                               struct net_device *dev);
struct neighbour *__neigh_create(struct neigh_table *tbl, const void *pkey,
                                 struct net_device *dev, bool want_ref);
static inline struct neighbour *neigh_create(struct neigh_table *tbl,
                                             const void *pkey,
                                             struct net_device *dev)
{
        return __neigh_create(tbl, pkey, dev, true);
}
void neigh_destroy(struct neighbour *neigh);
int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb,
                       const bool immediate_ok);
int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, u32 flags,
                 u32 nlmsg_pid);
void __neigh_set_probe_once(struct neighbour *neigh);
bool neigh_remove_one(struct neighbour *ndel);
void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
int neigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
int neigh_carrier_down(struct neigh_table *tbl, struct net_device *dev);
int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb);
int neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb);
int neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb);
struct neighbour *neigh_event_ns(struct neigh_table *tbl,
                                                u8 *lladdr, void *saddr,
                                                struct net_device *dev);

struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
                                      struct neigh_table *tbl);
void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms);

static inline
struct net *neigh_parms_net(const struct neigh_parms *parms)
{
        return read_pnet(&parms->net);
}

unsigned long neigh_rand_reach_time(unsigned long base);

static inline void neigh_set_reach_time(struct neigh_parms *p)
{
        unsigned long base = NEIGH_VAR(p, BASE_REACHABLE_TIME);

        WRITE_ONCE(p->reachable_time, neigh_rand_reach_time(base));
}

void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
                    struct sk_buff *skb);
struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,
                                   const void *key, struct net_device *dev);
int pneigh_create(struct neigh_table *tbl, struct net *net, const void *key,
                  struct net_device *dev, u32 flags, u8 protocol,
                  bool permanent);
int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key,
                  struct net_device *dev);

static inline struct net *pneigh_net(const struct pneigh_entry *pneigh)
{
        return read_pnet(&pneigh->net);
}

void neigh_app_ns(struct neighbour *n);
void neigh_for_each(struct neigh_table *tbl,
                    void (*cb)(struct neighbour *, void *), void *cookie);
void __neigh_for_each_release(struct neigh_table *tbl,
                              int (*cb)(struct neighbour *));
int neigh_xmit(int fam, struct net_device *, const void *, struct sk_buff *);

struct neigh_seq_state {
        struct seq_net_private p;
        struct neigh_table *tbl;
        struct neigh_hash_table *nht;
        void *(*neigh_sub_iter)(struct neigh_seq_state *state,
                                struct neighbour *n, loff_t *pos);
        unsigned int bucket;
        unsigned int flags;
#define NEIGH_SEQ_NEIGH_ONLY    0x00000001
#define NEIGH_SEQ_IS_PNEIGH     0x00000002
#define NEIGH_SEQ_SKIP_NOARP    0x00000004
};
void *neigh_seq_start(struct seq_file *, loff_t *, struct neigh_table *,
                      unsigned int);
void *neigh_seq_next(struct seq_file *, void *, loff_t *);
void neigh_seq_stop(struct seq_file *, void *);

int neigh_proc_dointvec(const struct ctl_table *ctl, int write,
                        void *buffer, size_t *lenp, loff_t *ppos);
int neigh_proc_dointvec_jiffies(const struct ctl_table *ctl, int write,
                                void *buffer,
                                size_t *lenp, loff_t *ppos);
int neigh_proc_dointvec_ms_jiffies(const struct ctl_table *ctl, int write,
                                   void *buffer, size_t *lenp, loff_t *ppos);

int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
                          proc_handler *proc_handler);
void neigh_sysctl_unregister(struct neigh_parms *p);

static inline void __neigh_parms_put(struct neigh_parms *parms)
{
        refcount_dec(&parms->refcnt);
}

static inline struct neigh_parms *neigh_parms_clone(struct neigh_parms *parms)
{
        refcount_inc(&parms->refcnt);
        return parms;
}

/*
 *      Neighbour references
 */

static inline void neigh_release(struct neighbour *neigh)
{
        if (refcount_dec_and_test(&neigh->refcnt))
                neigh_destroy(neigh);
}

static inline struct neighbour * neigh_clone(struct neighbour *neigh)
{
        if (neigh)
                refcount_inc(&neigh->refcnt);
        return neigh;
}

#define neigh_hold(n)   refcount_inc(&(n)->refcnt)

static __always_inline int neigh_event_send_probe(struct neighbour *neigh,
                                                  struct sk_buff *skb,
                                                  const bool immediate_ok)
{
        unsigned long now = jiffies;

        if (READ_ONCE(neigh->used) != now)
                WRITE_ONCE(neigh->used, now);
        if (!(READ_ONCE(neigh->nud_state) & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE)))
                return __neigh_event_send(neigh, skb, immediate_ok);
        return 0;
}

static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
{
        return neigh_event_send_probe(neigh, skb, true);
}

#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
{
        unsigned int seq, hh_alen;

        do {
                seq = read_seqbegin(&hh->hh_lock);
                hh_alen = HH_DATA_ALIGN(ETH_HLEN);
                memcpy(skb->data - hh_alen, hh->hh_data, ETH_ALEN + hh_alen - ETH_HLEN);
        } while (read_seqretry(&hh->hh_lock, seq));
        return 0;
}
#endif

static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
{
        unsigned int hh_alen = 0;
        unsigned int seq;
        unsigned int hh_len;

        do {
                seq = read_seqbegin(&hh->hh_lock);
                hh_len = READ_ONCE(hh->hh_len);
                if (likely(hh_len <= HH_DATA_MOD)) {
                        hh_alen = HH_DATA_MOD;

                        /* skb_push() would proceed silently if we have room for
                         * the unaligned size but not for the aligned size:
                         * check headroom explicitly.
                         */
                        if (likely(skb_headroom(skb) >= HH_DATA_MOD)) {
                                /* this is inlined by gcc */
                                memcpy(skb->data - HH_DATA_MOD, hh->hh_data,
                                       HH_DATA_MOD);
                        }
                } else {
                        hh_alen = HH_DATA_ALIGN(hh_len);

                        if (likely(skb_headroom(skb) >= hh_alen)) {
                                memcpy(skb->data - hh_alen, hh->hh_data,
                                       hh_alen);
                        }
                }
        } while (read_seqretry(&hh->hh_lock, seq));

        if (WARN_ON_ONCE(skb_headroom(skb) < hh_alen)) {
                kfree_skb(skb);
                return NET_XMIT_DROP;
        }

        __skb_push(skb, hh_len);
        return dev_queue_xmit(skb);
}

static inline int neigh_output(struct neighbour *n, struct sk_buff *skb,
                               bool skip_cache)
{
        const struct hh_cache *hh = &n->hh;

        /* n->nud_state and hh->hh_len could be changed under us.
         * neigh_hh_output() is taking care of the race later.
         */
        if (!skip_cache &&
            (READ_ONCE(n->nud_state) & NUD_CONNECTED) &&
            READ_ONCE(hh->hh_len))
                return neigh_hh_output(hh, skb);

        return READ_ONCE(n->output)(n, skb);
}

static inline struct neighbour *
__neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat)
{
        struct neighbour *n = neigh_lookup(tbl, pkey, dev);

        if (n || !creat)
                return n;

        n = neigh_create(tbl, pkey, dev);
        return IS_ERR(n) ? NULL : n;
}

static inline struct neighbour *
__neigh_lookup_errno(struct neigh_table *tbl, const void *pkey,
  struct net_device *dev)
{
        struct neighbour *n = neigh_lookup(tbl, pkey, dev);

        if (n)
                return n;

        return neigh_create(tbl, pkey, dev);
}

struct neighbour_cb {
        unsigned long sched_next;
        unsigned int flags;
};

#define LOCALLY_ENQUEUED 0x1

#define NEIGH_CB(skb)   ((struct neighbour_cb *)(skb)->cb)

static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n,
                                     const struct net_device *dev)
{
        unsigned int seq;

        do {
                seq = read_seqbegin(&n->ha_lock);
                memcpy(dst, n->ha, dev->addr_len);
        } while (read_seqretry(&n->ha_lock, seq));
}

static inline void neigh_update_is_router(struct neighbour *neigh, u32 flags,
                                          int *notify)
{
        u8 ndm_flags = 0;

        ndm_flags |= (flags & NEIGH_UPDATE_F_ISROUTER) ? NTF_ROUTER : 0;
        if ((neigh->flags ^ ndm_flags) & NTF_ROUTER) {
                if (ndm_flags & NTF_ROUTER)
                        neigh->flags |= NTF_ROUTER;
                else
                        neigh->flags &= ~NTF_ROUTER;
                *notify = 1;
        }
}
#endif