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

#include <linux/rhashtable-types.h>
#include <linux/completion.h>
#include <linux/in6.h>
#include <linux/rbtree_types.h>
#include <linux/refcount.h>
#include <net/dropreason-core.h>

/* Per netns frag queues directory */
struct fqdir {
        /* sysctls */
        long                    high_thresh;
        long                    low_thresh;
        int                     timeout;
        int                     max_dist;
        struct inet_frags       *f;
        struct net              *net;
        bool                    dead;

        struct rhashtable       rhashtable ____cacheline_aligned_in_smp;

        /* Keep atomic mem on separate cachelines in structs that include it */
        atomic_long_t           mem ____cacheline_aligned_in_smp;
        struct work_struct      destroy_work;
        struct llist_node       free_list;
};

/**
 * enum: fragment queue flags
 *
 * @INET_FRAG_FIRST_IN: first fragment has arrived
 * @INET_FRAG_LAST_IN: final fragment has arrived
 * @INET_FRAG_COMPLETE: frag queue has been processed and is due for destruction
 * @INET_FRAG_HASH_DEAD: inet_frag_kill() has not removed fq from rhashtable
 * @INET_FRAG_DROP: if skbs must be dropped (instead of being consumed)
 */
enum {
        INET_FRAG_FIRST_IN      = BIT(0),
        INET_FRAG_LAST_IN       = BIT(1),
        INET_FRAG_COMPLETE      = BIT(2),
        INET_FRAG_HASH_DEAD     = BIT(3),
        INET_FRAG_DROP          = BIT(4),
};

struct frag_v4_compare_key {
        __be32          saddr;
        __be32          daddr;
        u32             user;
        u32             vif;
        __be16          id;
        u16             protocol;
};

struct frag_v6_compare_key {
        struct in6_addr saddr;
        struct in6_addr daddr;
        u32             user;
        __be32          id;
        u32             iif;
};

/**
 * struct inet_frag_queue - fragment queue
 *
 * @node: rhash node
 * @key: keys identifying this frag.
 * @timer: queue expiration timer
 * @lock: spinlock protecting this frag
 * @refcnt: reference count of the queue
 * @rb_fragments: received fragments rb-tree root
 * @fragments_tail: received fragments tail
 * @last_run_head: the head of the last "run". see ip_fragment.c
 * @stamp: timestamp of the last received fragment
 * @len: total length of the original datagram
 * @meat: length of received fragments so far
 * @tstamp_type: stamp has a mono delivery time (EDT)
 * @flags: fragment queue flags
 * @max_size: maximum received fragment size
 * @fqdir: pointer to struct fqdir
 * @rcu: rcu head for freeing deferall
 */
struct inet_frag_queue {
        struct rhash_head       node;
        union {
                struct frag_v4_compare_key v4;
                struct frag_v6_compare_key v6;
        } key;
        struct timer_list       timer;
        spinlock_t              lock;
        refcount_t              refcnt;
        struct rb_root          rb_fragments;
        struct sk_buff          *fragments_tail;
        struct sk_buff          *last_run_head;
        ktime_t                 stamp;
        int                     len;
        int                     meat;
        u8                      tstamp_type;
        __u8                    flags;
        u16                     max_size;
        struct fqdir            *fqdir;
        struct rcu_head         rcu;
};

struct inet_frags {
        unsigned int            qsize;

        void                    (*constructor)(struct inet_frag_queue *q,
                                               const void *arg);
        void                    (*destructor)(struct inet_frag_queue *);
        void                    (*frag_expire)(struct timer_list *t);
        struct kmem_cache       *frags_cachep;
        const char              *frags_cache_name;
        struct rhashtable_params rhash_params;
        refcount_t              refcnt;
        struct completion       completion;
};

int inet_frags_init(struct inet_frags *);
void inet_frags_fini(struct inet_frags *);

int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net);

void fqdir_pre_exit(struct fqdir *fqdir);
void fqdir_exit(struct fqdir *fqdir);

void inet_frag_kill(struct inet_frag_queue *q, int *refs);
void inet_frag_destroy(struct inet_frag_queue *q);
struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key);

void inet_frag_queue_flush(struct inet_frag_queue *q,
                           enum skb_drop_reason reason);

static inline void inet_frag_putn(struct inet_frag_queue *q, int refs)
{
        if (refs && refcount_sub_and_test(refs, &q->refcnt))
                inet_frag_destroy(q);
}

/* Memory Tracking Functions. */

static inline long frag_mem_limit(const struct fqdir *fqdir)
{
        return atomic_long_read(&fqdir->mem);
}

static inline void sub_frag_mem_limit(struct fqdir *fqdir, long val)
{
        atomic_long_sub(val, &fqdir->mem);
}

static inline void add_frag_mem_limit(struct fqdir *fqdir, long val)
{
        atomic_long_add(val, &fqdir->mem);
}

/* RFC 3168 support :
 * We want to check ECN values of all fragments, do detect invalid combinations.
 * In ipq->ecn, we store the OR value of each ip4_frag_ecn() fragment value.
 */
#define IPFRAG_ECN_NOT_ECT      0x01 /* one frag had ECN_NOT_ECT */
#define IPFRAG_ECN_ECT_1        0x02 /* one frag had ECN_ECT_1 */
#define IPFRAG_ECN_ECT_0        0x04 /* one frag had ECN_ECT_0 */
#define IPFRAG_ECN_CE           0x08 /* one frag had ECN_CE */

extern const u8 ip_frag_ecn_table[16];

/* Return values of inet_frag_queue_insert() */
#define IPFRAG_OK       0
#define IPFRAG_DUP      1
#define IPFRAG_OVERLAP  2
int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb,
                           int offset, int end);
void *inet_frag_reasm_prepare(struct inet_frag_queue *q, struct sk_buff *skb,
                              struct sk_buff *parent);
void inet_frag_reasm_finish(struct inet_frag_queue *q, struct sk_buff *head,
                            void *reasm_data, bool try_coalesce);
struct sk_buff *inet_frag_pull_head(struct inet_frag_queue *q);

#endif