/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *      Linux INET6 implementation 
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>     
 */

#ifndef _IP6_FIB_H
#define _IP6_FIB_H

#include <linux/ipv6_route.h>
#include <linux/rtnetlink.h>
#include <linux/spinlock.h>
#include <linux/notifier.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/ip_fib.h>
#include <net/netlink.h>
#include <net/inetpeer.h>
#include <net/fib_notifier.h>
#include <linux/indirect_call_wrapper.h>
#include <uapi/linux/bpf.h>

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
#define FIB6_TABLE_HASHSZ 256
#else
#define FIB6_TABLE_HASHSZ 1
#endif

#define RT6_DEBUG 2

struct rt6_info;
struct fib6_info;

struct fib6_config {
        u32             fc_table;
        u32             fc_metric;
        int             fc_dst_len;
        int             fc_src_len;
        int             fc_ifindex;
        u32             fc_flags;
        u32             fc_protocol;
        u16             fc_type;        /* only 8 bits are used */
        u16             fc_delete_all_nh : 1,
                        fc_ignore_dev_down:1,
                        __unused : 14;
        u32             fc_nh_id;

        struct in6_addr fc_dst;
        struct in6_addr fc_src;
        struct in6_addr fc_prefsrc;
        struct in6_addr fc_gateway;

        unsigned long   fc_expires;
        struct nlattr   *fc_mx;
        int             fc_mx_len;
        int             fc_mp_len;
        struct nlattr   *fc_mp;

        struct nl_info  fc_nlinfo;
        struct nlattr   *fc_encap;
        u16             fc_encap_type;
        bool            fc_is_fdb;
};

struct fib6_node {
        struct fib6_node __rcu  *parent;
        struct fib6_node __rcu  *left;
        struct fib6_node __rcu  *right;
#ifdef CONFIG_IPV6_SUBTREES
        struct fib6_node __rcu  *subtree;
#endif
        struct fib6_info __rcu  *leaf;

        __u16                   fn_bit;         /* bit key */
        __u16                   fn_flags;
        int                     fn_sernum;
        struct fib6_info __rcu  *rr_ptr;
        struct rcu_head         rcu;
};

struct fib6_gc_args {
        int                     timeout;
        int                     more;
};

#ifndef CONFIG_IPV6_SUBTREES
#define FIB6_SUBTREE(fn)        NULL

static inline bool fib6_routes_require_src(const struct net *net)
{
        return false;
}

static inline void fib6_routes_require_src_inc(struct net *net) {}
static inline void fib6_routes_require_src_dec(struct net *net) {}

#else

static inline bool fib6_routes_require_src(const struct net *net)
{
        return net->ipv6.fib6_routes_require_src > 0;
}

static inline void fib6_routes_require_src_inc(struct net *net)
{
        net->ipv6.fib6_routes_require_src++;
}

static inline void fib6_routes_require_src_dec(struct net *net)
{
        net->ipv6.fib6_routes_require_src--;
}

#define FIB6_SUBTREE(fn)        (rcu_dereference_protected((fn)->subtree, 1))
#endif

/*
 *      routing information
 *
 */

struct rt6key {
        struct in6_addr addr;
        int             plen;
};

struct fib6_table;

struct rt6_exception_bucket {
        struct hlist_head       chain;
        int                     depth;
};

struct rt6_exception {
        struct hlist_node       hlist;
        struct rt6_info         *rt6i;
        unsigned long           stamp;
        struct rcu_head         rcu;
};

#define FIB6_EXCEPTION_BUCKET_SIZE_SHIFT 10
#define FIB6_EXCEPTION_BUCKET_SIZE (1 << FIB6_EXCEPTION_BUCKET_SIZE_SHIFT)
#define FIB6_MAX_DEPTH 5

struct fib6_nh {
        struct fib_nh_common    nh_common;

#ifdef CONFIG_IPV6_ROUTER_PREF
        unsigned long           last_probe;
#endif

        struct rt6_info * __percpu *rt6i_pcpu;
        struct rt6_exception_bucket __rcu *rt6i_exception_bucket;
};

struct fib6_info {
        struct fib6_table               *fib6_table;
        struct fib6_info __rcu          *fib6_next;
        struct fib6_node __rcu          *fib6_node;

        /* Multipath routes:
         * siblings is a list of fib6_info that have the same metric/weight,
         * destination, but not the same gateway. nsiblings is just a cache
         * to speed up lookup.
         */
        union {
                struct list_head        fib6_siblings;
                struct list_head        nh_list;
        };
        unsigned int                    fib6_nsiblings;

        refcount_t                      fib6_ref;
        unsigned long                   expires;

        struct hlist_node               gc_link;

        struct dst_metrics              *fib6_metrics;
#define fib6_pmtu               fib6_metrics->metrics[RTAX_MTU-1]

        struct rt6key                   fib6_dst;
        u32                             fib6_flags;
        struct rt6key                   fib6_src;
        struct rt6key                   fib6_prefsrc;

        u32                             fib6_metric;
        u8                              fib6_protocol;
        u8                              fib6_type;

        u8                              offload;
        u8                              trap;
        u8                              offload_failed;

        u8                              should_flush:1,
                                        dst_nocount:1,
                                        dst_nopolicy:1,
                                        fib6_destroying:1,
                                        unused:4;

        struct list_head                purge_link;
        struct rcu_head                 rcu;
        struct nexthop                  *nh;
        struct fib6_nh                  fib6_nh[];
};

struct rt6_info {
        struct dst_entry                dst;
        struct fib6_info __rcu          *from;
        int                             sernum;

        struct rt6key                   rt6i_dst;
        struct rt6key                   rt6i_src;
        struct in6_addr                 rt6i_gateway;
        struct inet6_dev                *rt6i_idev;
        u32                             rt6i_flags;

        /* more non-fragment space at head required */
        unsigned short                  rt6i_nfheader_len;
};

struct fib6_result {
        struct fib6_nh          *nh;
        struct fib6_info        *f6i;
        u32                     fib6_flags;
        u8                      fib6_type;
        struct rt6_info         *rt6;
};

#define for_each_fib6_node_rt_rcu(fn)                                   \
        for (rt = rcu_dereference((fn)->leaf); rt;                      \
             rt = rcu_dereference(rt->fib6_next))

#define for_each_fib6_walker_rt(w)                                      \
        for (rt = (w)->leaf; rt;                                        \
             rt = rcu_dereference_protected(rt->fib6_next, 1))

#define dst_rt6_info(_ptr) container_of_const(_ptr, struct rt6_info, dst)

static inline struct inet6_dev *ip6_dst_idev(const struct dst_entry *dst)
{
        return dst_rt6_info(dst)->rt6i_idev;
}

static inline bool fib6_requires_src(const struct fib6_info *rt)
{
        return rt->fib6_src.plen > 0;
}

/* The callers should hold f6i->fib6_table->tb6_lock if a route has ever
 * been added to a table before.
 */
static inline void fib6_clean_expires(struct fib6_info *f6i)
{
        f6i->fib6_flags &= ~RTF_EXPIRES;
        f6i->expires = 0;
}

/* The callers should hold f6i->fib6_table->tb6_lock if a route has ever
 * been added to a table before.
 */
static inline void fib6_set_expires(struct fib6_info *f6i,
                                    unsigned long expires)
{
        f6i->expires = expires;
        f6i->fib6_flags |= RTF_EXPIRES;
}

static inline bool fib6_check_expired(const struct fib6_info *f6i)
{
        if (f6i->fib6_flags & RTF_EXPIRES)
                return time_after(jiffies, f6i->expires);
        return false;
}

/* Function to safely get fn->fn_sernum for passed in rt
 * and store result in passed in cookie.
 * Return true if we can get cookie safely
 * Return false if not
 */
static inline bool fib6_get_cookie_safe(const struct fib6_info *f6i,
                                        u32 *cookie)
{
        struct fib6_node *fn;
        bool status = false;

        fn = rcu_dereference(f6i->fib6_node);

        if (fn) {
                *cookie = READ_ONCE(fn->fn_sernum);
                /* pairs with smp_wmb() in __fib6_update_sernum_upto_root() */
                smp_rmb();
                status = true;
        }

        return status;
}

static inline u32 rt6_get_cookie(const struct rt6_info *rt)
{
        struct fib6_info *from;
        u32 cookie = 0;

        if (rt->sernum)
                return rt->sernum;

        rcu_read_lock();

        from = rcu_dereference(rt->from);
        if (from)
                fib6_get_cookie_safe(from, &cookie);

        rcu_read_unlock();

        return cookie;
}

static inline void ip6_rt_put(struct rt6_info *rt)
{
        /* dst_release() accepts a NULL parameter.
         * We rely on dst being first structure in struct rt6_info
         */
        BUILD_BUG_ON(offsetof(struct rt6_info, dst) != 0);
        dst_release(&rt->dst);
}

struct fib6_info *fib6_info_alloc(gfp_t gfp_flags, bool with_fib6_nh);
void fib6_info_destroy_rcu(struct rcu_head *head);

static inline void fib6_info_hold(struct fib6_info *f6i)
{
        refcount_inc(&f6i->fib6_ref);
}

static inline bool fib6_info_hold_safe(struct fib6_info *f6i)
{
        return refcount_inc_not_zero(&f6i->fib6_ref);
}

static inline void fib6_info_release(struct fib6_info *f6i)
{
        if (f6i && refcount_dec_and_test(&f6i->fib6_ref)) {
                DEBUG_NET_WARN_ON_ONCE(!hlist_unhashed(&f6i->gc_link));
                call_rcu_hurry(&f6i->rcu, fib6_info_destroy_rcu);
        }
}

enum fib6_walk_state {
#ifdef CONFIG_IPV6_SUBTREES
        FWS_S,
#endif
        FWS_L,
        FWS_R,
        FWS_C,
        FWS_U
};

struct fib6_walker {
        struct list_head lh;
        struct fib6_node *root, *node;
        struct fib6_info *leaf;
        enum fib6_walk_state state;
        unsigned int skip;
        unsigned int count;
        unsigned int skip_in_node;
        int (*func)(struct fib6_walker *);
        void *args;
};

struct rt6_statistics {
        __u32           fib_nodes;              /* all fib6 nodes */
        __u32           fib_route_nodes;        /* intermediate nodes */
        __u32           fib_rt_entries;         /* rt entries in fib table */
        __u32           fib_rt_cache;           /* cached rt entries in exception table */
        __u32           fib_discarded_routes;   /* total number of routes delete */

        /* The following stat is not protected by any lock */
        atomic_t        fib_rt_alloc;           /* total number of routes alloced */
};

#define RTN_TL_ROOT     0x0001
#define RTN_ROOT        0x0002          /* tree root node               */
#define RTN_RTINFO      0x0004          /* node with valid routing info */

/*
 *      priority levels (or metrics)
 *
 */


struct fib6_table {
        struct hlist_node       tb6_hlist;
        u32                     tb6_id;
        spinlock_t              tb6_lock;
        struct fib6_node        tb6_root;
        struct inet_peer_base   tb6_peers;
        unsigned int            flags;
        unsigned int            fib_seq; /* writes protected by rtnl_mutex */
        struct hlist_head       tb6_gc_hlist;   /* GC candidates */
#define RT6_TABLE_HAS_DFLT_ROUTER       BIT(0)
};

#define RT6_TABLE_UNSPEC        RT_TABLE_UNSPEC
#define RT6_TABLE_MAIN          RT_TABLE_MAIN
#define RT6_TABLE_DFLT          RT6_TABLE_MAIN
#define RT6_TABLE_INFO          RT6_TABLE_MAIN
#define RT6_TABLE_PREFIX        RT6_TABLE_MAIN

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
#define FIB6_TABLE_MIN          1
#define FIB6_TABLE_MAX          RT_TABLE_MAX
#define RT6_TABLE_LOCAL         RT_TABLE_LOCAL
#else
#define FIB6_TABLE_MIN          RT_TABLE_MAIN
#define FIB6_TABLE_MAX          FIB6_TABLE_MIN
#define RT6_TABLE_LOCAL         RT6_TABLE_MAIN
#endif

typedef struct rt6_info *(*pol_lookup_t)(struct net *,
                                         struct fib6_table *,
                                         struct flowi6 *,
                                         const struct sk_buff *, int);

struct fib6_entry_notifier_info {
        struct fib_notifier_info info; /* must be first */
        struct fib6_info *rt;
        unsigned int nsiblings;
};

/*
 *      exported functions
 */

struct fib6_table *fib6_get_table(struct net *net, u32 id);
struct fib6_table *fib6_new_table(struct net *net, u32 id);
struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
                                   const struct sk_buff *skb,
                                   int flags, pol_lookup_t lookup);

/* called with rcu lock held; can return error pointer
 * caller needs to select path
 */
int fib6_lookup(struct net *net, int oif, struct flowi6 *fl6,
                struct fib6_result *res, int flags);

/* called with rcu lock held; caller needs to select path */
int fib6_table_lookup(struct net *net, struct fib6_table *table,
                      int oif, struct flowi6 *fl6, struct fib6_result *res,
                      int strict);

void fib6_select_path(const struct net *net, struct fib6_result *res,
                      struct flowi6 *fl6, int oif, bool have_oif_match,
                      const struct sk_buff *skb, int strict);
struct fib6_node *fib6_node_lookup(struct fib6_node *root,
                                   const struct in6_addr *daddr,
                                   const struct in6_addr *saddr);

struct fib6_node *fib6_locate(struct fib6_node *root,
                              const struct in6_addr *daddr, int dst_len,
                              const struct in6_addr *saddr, int src_len,
                              bool exact_match);

void fib6_clean_all(struct net *net, int (*func)(struct fib6_info *, void *arg),
                    void *arg);
void fib6_clean_all_skip_notify(struct net *net,
                                int (*func)(struct fib6_info *, void *arg),
                                void *arg);

int fib6_add(struct fib6_node *root, struct fib6_info *rt,
             struct nl_info *info, struct netlink_ext_ack *extack);
int fib6_del(struct fib6_info *rt, struct nl_info *info);

static inline
void rt6_get_prefsrc(const struct rt6_info *rt, struct in6_addr *addr)
{
        const struct fib6_info *from;

        rcu_read_lock();

        from = rcu_dereference(rt->from);
        if (from)
                *addr = from->fib6_prefsrc.addr;
        else
                *addr = in6addr_any;

        rcu_read_unlock();
}

int fib6_nh_init(struct net *net, struct fib6_nh *fib6_nh,
                 struct fib6_config *cfg, gfp_t gfp_flags,
                 struct netlink_ext_ack *extack);
void fib6_nh_release(struct fib6_nh *fib6_nh);
void fib6_nh_release_dsts(struct fib6_nh *fib6_nh);

int call_fib6_entry_notifiers(struct net *net,
                              enum fib_event_type event_type,
                              struct fib6_info *rt,
                              struct netlink_ext_ack *extack);
int call_fib6_multipath_entry_notifiers(struct net *net,
                                        enum fib_event_type event_type,
                                        struct fib6_info *rt,
                                        unsigned int nsiblings,
                                        struct netlink_ext_ack *extack);
int call_fib6_entry_notifiers_replace(struct net *net, struct fib6_info *rt);
void fib6_rt_update(struct net *net, struct fib6_info *rt,
                    struct nl_info *info);
void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
                     unsigned int flags);

void fib6_age_exceptions(struct fib6_info *rt, struct fib6_gc_args *gc_args,
                         unsigned long now);
void fib6_run_gc(unsigned long expires, struct net *net, bool force);
void fib6_gc_cleanup(void);

int fib6_init(void);

#if IS_ENABLED(CONFIG_IPV6)
/* Add the route to the gc list if it is not already there
 *
 * The callers should hold f6i->fib6_table->tb6_lock.
 */
static inline void fib6_add_gc_list(struct fib6_info *f6i)
{
        /* If fib6_node is null, the f6i is not in (or removed from) the
         * table.
         *
         * There is a gap between finding the f6i from the table and
         * calling this function without the protection of the tb6_lock.
         * This check makes sure the f6i is not added to the gc list when
         * it is not on the table.
         */
        if (!rcu_dereference_protected(f6i->fib6_node,
                                       lockdep_is_held(&f6i->fib6_table->tb6_lock)))
                return;

        if (hlist_unhashed(&f6i->gc_link))
                hlist_add_head(&f6i->gc_link, &f6i->fib6_table->tb6_gc_hlist);
}

/* Remove the route from the gc list if it is on the list.
 *
 * The callers should hold f6i->fib6_table->tb6_lock.
 */
static inline void fib6_remove_gc_list(struct fib6_info *f6i)
{
        if (!hlist_unhashed(&f6i->gc_link))
                hlist_del_init(&f6i->gc_link);
}

static inline void fib6_may_remove_gc_list(struct net *net,
                                           struct fib6_info *f6i)
{
        struct fib6_gc_args gc_args;

        if (hlist_unhashed(&f6i->gc_link))
                return;

        gc_args.timeout = READ_ONCE(net->ipv6.sysctl.ip6_rt_gc_interval);
        gc_args.more = 0;

        rcu_read_lock();
        fib6_age_exceptions(f6i, &gc_args, jiffies);
        rcu_read_unlock();
}
#endif

struct ipv6_route_iter {
        struct seq_net_private p;
        struct fib6_walker w;
        loff_t skip;
        struct fib6_table *tbl;
        int sernum;
};

extern const struct seq_operations ipv6_route_seq_ops;

int call_fib6_notifier(struct notifier_block *nb,
                       enum fib_event_type event_type,
                       struct fib_notifier_info *info);
int call_fib6_notifiers(struct net *net, enum fib_event_type event_type,
                        struct fib_notifier_info *info);

int __net_init fib6_notifier_init(struct net *net);
void __net_exit fib6_notifier_exit(struct net *net);

unsigned int fib6_tables_seq_read(const struct net *net);
int fib6_tables_dump(struct net *net, struct notifier_block *nb,
                     struct netlink_ext_ack *extack);

void fib6_update_sernum(struct net *net, struct fib6_info *rt);
void fib6_update_sernum_upto_root(struct net *net, struct fib6_info *rt);
void fib6_update_sernum_stub(struct net *net, struct fib6_info *f6i);

void fib6_metric_set(struct fib6_info *f6i, int metric, u32 val);
static inline bool fib6_metric_locked(struct fib6_info *f6i, int metric)
{
        return !!(f6i->fib6_metrics->metrics[RTAX_LOCK - 1] & (1 << metric));
}
void fib6_info_hw_flags_set(struct net *net, struct fib6_info *f6i,
                            bool offload, bool trap, bool offload_failed);

#if IS_BUILTIN(CONFIG_IPV6) && defined(CONFIG_BPF_SYSCALL)
struct bpf_iter__ipv6_route {
        __bpf_md_ptr(struct bpf_iter_meta *, meta);
        __bpf_md_ptr(struct fib6_info *, rt);
};
#endif

INDIRECT_CALLABLE_DECLARE(struct rt6_info *ip6_pol_route_output(struct net *net,
                                             struct fib6_table *table,
                                             struct flowi6 *fl6,
                                             const struct sk_buff *skb,
                                             int flags));
INDIRECT_CALLABLE_DECLARE(struct rt6_info *ip6_pol_route_input(struct net *net,
                                             struct fib6_table *table,
                                             struct flowi6 *fl6,
                                             const struct sk_buff *skb,
                                             int flags));
INDIRECT_CALLABLE_DECLARE(struct rt6_info *__ip6_route_redirect(struct net *net,
                                             struct fib6_table *table,
                                             struct flowi6 *fl6,
                                             const struct sk_buff *skb,
                                             int flags));
INDIRECT_CALLABLE_DECLARE(struct rt6_info *ip6_pol_route_lookup(struct net *net,
                                             struct fib6_table *table,
                                             struct flowi6 *fl6,
                                             const struct sk_buff *skb,
                                             int flags));
static inline struct rt6_info *pol_lookup_func(pol_lookup_t lookup,
                                                struct net *net,
                                                struct fib6_table *table,
                                                struct flowi6 *fl6,
                                                const struct sk_buff *skb,
                                                int flags)
{
        return INDIRECT_CALL_4(lookup,
                               ip6_pol_route_output,
                               ip6_pol_route_input,
                               ip6_pol_route_lookup,
                               __ip6_route_redirect,
                               net, table, fl6, skb, flags);
}

#ifdef CONFIG_IPV6_MULTIPLE_TABLES
static inline bool fib6_has_custom_rules(const struct net *net)
{
        return net->ipv6.fib6_has_custom_rules;
}

int fib6_rules_init(void);
void fib6_rules_cleanup(void);
bool fib6_rule_default(const struct fib_rule *rule);
int fib6_rules_dump(struct net *net, struct notifier_block *nb,
                    struct netlink_ext_ack *extack);
unsigned int fib6_rules_seq_read(const struct net *net);

static inline bool fib6_rules_early_flow_dissect(struct net *net,
                                                 struct sk_buff *skb,
                                                 struct flowi6 *fl6,
                                                 struct flow_keys *flkeys)
{
        unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;

        if (!net->ipv6.fib6_rules_require_fldissect)
                return false;

        memset(flkeys, 0, sizeof(*flkeys));
        __skb_flow_dissect(net, skb, &flow_keys_dissector,
                           flkeys, NULL, 0, 0, 0, flag);

        fl6->fl6_sport = flkeys->ports.src;
        fl6->fl6_dport = flkeys->ports.dst;
        fl6->flowi6_proto = flkeys->basic.ip_proto;

        return true;
}
#else
static inline bool fib6_has_custom_rules(const struct net *net)
{
        return false;
}
static inline int               fib6_rules_init(void)
{
        return 0;
}
static inline void              fib6_rules_cleanup(void)
{
        return ;
}
static inline bool fib6_rule_default(const struct fib_rule *rule)
{
        return true;
}
static inline int fib6_rules_dump(struct net *net, struct notifier_block *nb,
                                  struct netlink_ext_ack *extack)
{
        return 0;
}
static inline unsigned int fib6_rules_seq_read(const struct net *net)
{
        return 0;
}
static inline bool fib6_rules_early_flow_dissect(struct net *net,
                                                 struct sk_buff *skb,
                                                 struct flowi6 *fl6,
                                                 struct flow_keys *flkeys)
{
        return false;
}
#endif
#endif