/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Generic nexthop implementation
 *
 * Copyright (c) 2017-19 Cumulus Networks
 * Copyright (c) 2017-19 David Ahern <dsa@cumulusnetworks.com>
 */

#ifndef __LINUX_NEXTHOP_H
#define __LINUX_NEXTHOP_H

#include <linux/netdevice.h>
#include <linux/notifier.h>
#include <linux/route.h>
#include <linux/types.h>
#include <net/ip_fib.h>
#include <net/ip6_fib.h>
#include <net/netlink.h>

#define NEXTHOP_VALID_USER_FLAGS RTNH_F_ONLINK

struct nexthop;

struct nh_config {
        u32             nh_id;

        u8              nh_family;
        u8              nh_protocol;
        u8              nh_blackhole;
        u8              nh_fdb;
        u32             nh_flags;

        int             nh_ifindex;
        struct net_device *dev;

        union {
                __be32          ipv4;
                struct in6_addr ipv6;
        } gw;

        struct nlattr   *nh_grp;
        u16             nh_grp_type;
        u16             nh_grp_res_num_buckets;
        unsigned long   nh_grp_res_idle_timer;
        unsigned long   nh_grp_res_unbalanced_timer;
        bool            nh_grp_res_has_num_buckets;
        bool            nh_grp_res_has_idle_timer;
        bool            nh_grp_res_has_unbalanced_timer;

        struct nlattr   *nh_encap;
        u16             nh_encap_type;

        u32             nlflags;
        struct nl_info  nlinfo;
};

struct nh_info {
        struct hlist_node       dev_hash;    /* entry on netns devhash */
        struct nexthop          *nh_parent;

        u8                      family;
        bool                    reject_nh;
        bool                    fdb_nh;

        union {
                struct fib_nh_common    fib_nhc;
                struct fib_nh           fib_nh;
                struct fib6_nh          fib6_nh;
        };
};

struct nh_res_bucket {
        struct nh_grp_entry __rcu *nh_entry;
        atomic_long_t           used_time;
        unsigned long           migrated_time;
        bool                    occupied;
        u8                      nh_flags;
};

struct nh_res_table {
        struct net              *net;
        u32                     nhg_id;
        struct delayed_work     upkeep_dw;

        /* List of NHGEs that have too few buckets ("uw" for underweight).
         * Reclaimed buckets will be given to entries in this list.
         */
        struct list_head        uw_nh_entries;
        unsigned long           unbalanced_since;

        u32                     idle_timer;
        u32                     unbalanced_timer;

        u16                     num_nh_buckets;
        struct nh_res_bucket    nh_buckets[];
};

struct nh_grp_entry {
        struct nexthop  *nh;
        u8              weight;

        union {
                struct {
                        atomic_t        upper_bound;
                } hthr;
                struct {
                        /* Member on uw_nh_entries. */
                        struct list_head        uw_nh_entry;

                        u16                     count_buckets;
                        u16                     wants_buckets;
                } res;
        };

        struct list_head nh_list;
        struct nexthop  *nh_parent;  /* nexthop of group with this entry */
};

struct nh_group {
        struct nh_group         *spare; /* spare group for removals */
        u16                     num_nh;
        bool                    is_multipath;
        bool                    hash_threshold;
        bool                    resilient;
        bool                    fdb_nh;
        bool                    has_v4;

        struct nh_res_table __rcu *res_table;
        struct nh_grp_entry     nh_entries[];
};

struct nexthop {
        struct rb_node          rb_node;    /* entry on netns rbtree */
        struct list_head        fi_list;    /* v4 entries using nh */
        struct list_head        f6i_list;   /* v6 entries using nh */
        struct list_head        fdb_list;   /* fdb entries using this nh */
        struct list_head        grp_list;   /* nh group entries using this nh */
        struct net              *net;

        u32                     id;

        u8                      protocol;   /* app managing this nh */
        u8                      nh_flags;
        bool                    is_group;

        refcount_t              refcnt;
        struct rcu_head         rcu;

        union {
                struct nh_info  __rcu *nh_info;
                struct nh_group __rcu *nh_grp;
        };
};

enum nexthop_event_type {
        NEXTHOP_EVENT_DEL,
        NEXTHOP_EVENT_REPLACE,
        NEXTHOP_EVENT_RES_TABLE_PRE_REPLACE,
        NEXTHOP_EVENT_BUCKET_REPLACE,
};

enum nh_notifier_info_type {
        NH_NOTIFIER_INFO_TYPE_SINGLE,
        NH_NOTIFIER_INFO_TYPE_GRP,
        NH_NOTIFIER_INFO_TYPE_RES_TABLE,
        NH_NOTIFIER_INFO_TYPE_RES_BUCKET,
};

struct nh_notifier_single_info {
        struct net_device *dev;
        u8 gw_family;
        union {
                __be32 ipv4;
                struct in6_addr ipv6;
        };
        u8 is_reject:1,
           is_fdb:1,
           has_encap:1;
};

struct nh_notifier_grp_entry_info {
        u8 weight;
        u32 id;
        struct nh_notifier_single_info nh;
};

struct nh_notifier_grp_info {
        u16 num_nh;
        bool is_fdb;
        struct nh_notifier_grp_entry_info nh_entries[];
};

struct nh_notifier_res_bucket_info {
        u16 bucket_index;
        unsigned int idle_timer_ms;
        bool force;
        struct nh_notifier_single_info old_nh;
        struct nh_notifier_single_info new_nh;
};

struct nh_notifier_res_table_info {
        u16 num_nh_buckets;
        struct nh_notifier_single_info nhs[];
};

struct nh_notifier_info {
        struct net *net;
        struct netlink_ext_ack *extack;
        u32 id;
        enum nh_notifier_info_type type;
        union {
                struct nh_notifier_single_info *nh;
                struct nh_notifier_grp_info *nh_grp;
                struct nh_notifier_res_table_info *nh_res_table;
                struct nh_notifier_res_bucket_info *nh_res_bucket;
        };
};

int register_nexthop_notifier(struct net *net, struct notifier_block *nb,
                              struct netlink_ext_ack *extack);
int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);
void nexthop_set_hw_flags(struct net *net, u32 id, bool offload, bool trap);
void nexthop_bucket_set_hw_flags(struct net *net, u32 id, u16 bucket_index,
                                 bool offload, bool trap);
void nexthop_res_grp_activity_update(struct net *net, u32 id, u16 num_buckets,
                                     unsigned long *activity);

/* caller is holding rcu or rtnl; no reference taken to nexthop */
struct nexthop *nexthop_find_by_id(struct net *net, u32 id);
void nexthop_free_rcu(struct rcu_head *head);

static inline bool nexthop_get(struct nexthop *nh)
{
        return refcount_inc_not_zero(&nh->refcnt);
}

static inline void nexthop_put(struct nexthop *nh)
{
        if (refcount_dec_and_test(&nh->refcnt))
                call_rcu(&nh->rcu, nexthop_free_rcu);
}

static inline bool nexthop_cmp(const struct nexthop *nh1,
                               const struct nexthop *nh2)
{
        return nh1 == nh2;
}

static inline bool nexthop_is_fdb(const struct nexthop *nh)
{
        if (nh->is_group) {
                const struct nh_group *nh_grp;

                nh_grp = rcu_dereference_rtnl(nh->nh_grp);
                return nh_grp->fdb_nh;
        } else {
                const struct nh_info *nhi;

                nhi = rcu_dereference_rtnl(nh->nh_info);
                return nhi->fdb_nh;
        }
}

static inline bool nexthop_has_v4(const struct nexthop *nh)
{
        if (nh->is_group) {
                struct nh_group *nh_grp;

                nh_grp = rcu_dereference_rtnl(nh->nh_grp);
                return nh_grp->has_v4;
        }
        return false;
}

static inline bool nexthop_is_multipath(const struct nexthop *nh)
{
        if (nh->is_group) {
                struct nh_group *nh_grp;

                nh_grp = rcu_dereference_rtnl(nh->nh_grp);
                return nh_grp->is_multipath;
        }
        return false;
}

struct nexthop *nexthop_select_path(struct nexthop *nh, int hash);

static inline unsigned int nexthop_num_path(const struct nexthop *nh)
{
        unsigned int rc = 1;

        if (nh->is_group) {
                struct nh_group *nh_grp;

                nh_grp = rcu_dereference_rtnl(nh->nh_grp);
                if (nh_grp->is_multipath)
                        rc = nh_grp->num_nh;
        }

        return rc;
}

static inline
struct nexthop *nexthop_mpath_select(const struct nh_group *nhg, int nhsel)
{
        /* for_nexthops macros in fib_semantics.c grabs a pointer to
         * the nexthop before checking nhsel
         */
        if (nhsel >= nhg->num_nh)
                return NULL;

        return nhg->nh_entries[nhsel].nh;
}

static inline
int nexthop_mpath_fill_node(struct sk_buff *skb, struct nexthop *nh,
                            u8 rt_family)
{
        struct nh_group *nhg = rtnl_dereference(nh->nh_grp);
        int i;

        for (i = 0; i < nhg->num_nh; i++) {
                struct nexthop *nhe = nhg->nh_entries[i].nh;
                struct nh_info *nhi = rcu_dereference_rtnl(nhe->nh_info);
                struct fib_nh_common *nhc = &nhi->fib_nhc;
                int weight = nhg->nh_entries[i].weight;

                if (fib_add_nexthop(skb, nhc, weight, rt_family, 0) < 0)
                        return -EMSGSIZE;
        }

        return 0;
}

/* called with rcu lock */
static inline bool nexthop_is_blackhole(const struct nexthop *nh)
{
        const struct nh_info *nhi;

        if (nh->is_group) {
                struct nh_group *nh_grp;

                nh_grp = rcu_dereference_rtnl(nh->nh_grp);
                if (nh_grp->num_nh > 1)
                        return false;

                nh = nh_grp->nh_entries[0].nh;
        }

        nhi = rcu_dereference_rtnl(nh->nh_info);
        return nhi->reject_nh;
}

static inline void nexthop_path_fib_result(struct fib_result *res, int hash)
{
        struct nh_info *nhi;
        struct nexthop *nh;

        nh = nexthop_select_path(res->fi->nh, hash);
        nhi = rcu_dereference(nh->nh_info);
        res->nhc = &nhi->fib_nhc;
}

/* called with rcu read lock or rtnl held */
static inline
struct fib_nh_common *nexthop_fib_nhc(struct nexthop *nh, int nhsel)
{
        struct nh_info *nhi;

        BUILD_BUG_ON(offsetof(struct fib_nh, nh_common) != 0);
        BUILD_BUG_ON(offsetof(struct fib6_nh, nh_common) != 0);

        if (nh->is_group) {
                struct nh_group *nh_grp;

                nh_grp = rcu_dereference_rtnl(nh->nh_grp);
                if (nh_grp->is_multipath) {
                        nh = nexthop_mpath_select(nh_grp, nhsel);
                        if (!nh)
                                return NULL;
                }
        }

        nhi = rcu_dereference_rtnl(nh->nh_info);
        return &nhi->fib_nhc;
}

/* called from fib_table_lookup with rcu_lock */
static inline
struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
                                             int fib_flags,
                                             const struct flowi4 *flp,
                                             int *nhsel)
{
        struct nh_info *nhi;

        if (nh->is_group) {
                struct nh_group *nhg = rcu_dereference(nh->nh_grp);
                int i;

                for (i = 0; i < nhg->num_nh; i++) {
                        struct nexthop *nhe = nhg->nh_entries[i].nh;

                        nhi = rcu_dereference(nhe->nh_info);
                        if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
                                *nhsel = i;
                                return &nhi->fib_nhc;
                        }
                }
        } else {
                nhi = rcu_dereference(nh->nh_info);
                if (fib_lookup_good_nhc(&nhi->fib_nhc, fib_flags, flp)) {
                        *nhsel = 0;
                        return &nhi->fib_nhc;
                }
        }

        return NULL;
}

static inline bool nexthop_uses_dev(const struct nexthop *nh,
                                    const struct net_device *dev)
{
        struct nh_info *nhi;

        if (nh->is_group) {
                struct nh_group *nhg = rcu_dereference(nh->nh_grp);
                int i;

                for (i = 0; i < nhg->num_nh; i++) {
                        struct nexthop *nhe = nhg->nh_entries[i].nh;

                        nhi = rcu_dereference(nhe->nh_info);
                        if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
                                return true;
                }
        } else {
                nhi = rcu_dereference(nh->nh_info);
                if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
                        return true;
        }

        return false;
}

static inline unsigned int fib_info_num_path(const struct fib_info *fi)
{
        if (unlikely(fi->nh))
                return nexthop_num_path(fi->nh);

        return fi->fib_nhs;
}

int fib_check_nexthop(struct nexthop *nh, u8 scope,
                      struct netlink_ext_ack *extack);

static inline struct fib_nh_common *fib_info_nhc(struct fib_info *fi, int nhsel)
{
        if (unlikely(fi->nh))
                return nexthop_fib_nhc(fi->nh, nhsel);

        return &fi->fib_nh[nhsel].nh_common;
}

/* only used when fib_nh is built into fib_info */
static inline struct fib_nh *fib_info_nh(struct fib_info *fi, int nhsel)
{
        WARN_ON(fi->nh);

        return &fi->fib_nh[nhsel];
}

/*
 * IPv6 variants
 */
int fib6_check_nexthop(struct nexthop *nh, struct fib6_config *cfg,
                       struct netlink_ext_ack *extack);

/* Caller should either hold rcu_read_lock(), or RTNL. */
static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh)
{
        struct nh_info *nhi;

        if (nh->is_group) {
                struct nh_group *nh_grp;

                nh_grp = rcu_dereference_rtnl(nh->nh_grp);
                nh = nexthop_mpath_select(nh_grp, 0);
                if (!nh)
                        return NULL;
        }

        nhi = rcu_dereference_rtnl(nh->nh_info);
        if (nhi->family == AF_INET6)
                return &nhi->fib6_nh;

        return NULL;
}

/* Variant of nexthop_fib6_nh().
 * Caller should either hold rcu_read_lock_bh(), or RTNL.
 */
static inline struct fib6_nh *nexthop_fib6_nh_bh(struct nexthop *nh)
{
        struct nh_info *nhi;

        if (nh->is_group) {
                struct nh_group *nh_grp;

                nh_grp = rcu_dereference_bh_rtnl(nh->nh_grp);
                nh = nexthop_mpath_select(nh_grp, 0);
                if (!nh)
                        return NULL;
        }

        nhi = rcu_dereference_bh_rtnl(nh->nh_info);
        if (nhi->family == AF_INET6)
                return &nhi->fib6_nh;

        return NULL;
}

static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i)
{
        struct fib6_nh *fib6_nh;

        fib6_nh = f6i->nh ? nexthop_fib6_nh(f6i->nh) : f6i->fib6_nh;
        return fib6_nh->fib_nh_dev;
}

static inline void nexthop_path_fib6_result(struct fib6_result *res, int hash)
{
        struct nexthop *nh = res->f6i->nh;
        struct nh_info *nhi;

        nh = nexthop_select_path(nh, hash);

        nhi = rcu_dereference_rtnl(nh->nh_info);
        if (nhi->reject_nh) {
                res->fib6_type = RTN_BLACKHOLE;
                res->fib6_flags |= RTF_REJECT;
                res->nh = nexthop_fib6_nh(nh);
        } else {
                res->nh = &nhi->fib6_nh;
        }
}

int nexthop_for_each_fib6_nh(struct nexthop *nh,
                             int (*cb)(struct fib6_nh *nh, void *arg),
                             void *arg);

static inline int nexthop_get_family(struct nexthop *nh)
{
        struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);

        return nhi->family;
}

static inline
struct fib_nh_common *nexthop_fdb_nhc(struct nexthop *nh)
{
        struct nh_info *nhi = rcu_dereference_rtnl(nh->nh_info);

        return &nhi->fib_nhc;
}

static inline struct fib_nh_common *nexthop_path_fdb_result(struct nexthop *nh,
                                                            int hash)
{
        struct nh_info *nhi;
        struct nexthop *nhp;

        nhp = nexthop_select_path(nh, hash);
        if (unlikely(!nhp))
                return NULL;
        nhi = rcu_dereference(nhp->nh_info);
        return &nhi->fib_nhc;
}
#endif