/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */

#ifndef _LINUX_SKMSG_H
#define _LINUX_SKMSG_H

#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/scatterlist.h>
#include <linux/skbuff.h>

#include <net/sock.h>
#include <net/tcp.h>
#include <net/strparser.h>

#define MAX_MSG_FRAGS                   MAX_SKB_FRAGS

enum __sk_action {
        __SK_DROP = 0,
        __SK_PASS,
        __SK_REDIRECT,
        __SK_NONE,
};

struct sk_msg_sg {
        u32                             start;
        u32                             curr;
        u32                             end;
        u32                             size;
        u32                             copybreak;
        bool                            copy[MAX_MSG_FRAGS];
        /* The extra element is used for chaining the front and sections when
         * the list becomes partitioned (e.g. end < start). The crypto APIs
         * require the chaining.
         */
        struct scatterlist              data[MAX_MSG_FRAGS + 1];
};

/* UAPI in filter.c depends on struct sk_msg_sg being first element. */
struct sk_msg {
        struct sk_msg_sg                sg;
        void                            *data;
        void                            *data_end;
        u32                             apply_bytes;
        u32                             cork_bytes;
        u32                             flags;
        struct sk_buff                  *skb;
        struct sock                     *sk_redir;
        struct sock                     *sk;
        struct list_head                list;
};

struct sk_psock_progs {
        struct bpf_prog                 *msg_parser;
        struct bpf_prog                 *skb_parser;
        struct bpf_prog                 *skb_verdict;
};

enum sk_psock_state_bits {
        SK_PSOCK_TX_ENABLED,
};

struct sk_psock_link {
        struct list_head                list;
        struct bpf_map                  *map;
        void                            *link_raw;
};

struct sk_psock_parser {
        struct strparser                strp;
        bool                            enabled;
        void (*saved_data_ready)(struct sock *sk);
};

struct sk_psock_work_state {
        struct sk_buff                  *skb;
        u32                             len;
        u32                             off;
};

struct sk_psock {
        struct sock                     *sk;
        struct sock                     *sk_redir;
        u32                             apply_bytes;
        u32                             cork_bytes;
        u32                             eval;
        struct sk_msg                   *cork;
        struct sk_psock_progs           progs;
        struct sk_psock_parser          parser;
        struct sk_buff_head             ingress_skb;
        struct list_head                ingress_msg;
        unsigned long                   state;
        struct list_head                link;
        spinlock_t                      link_lock;
        refcount_t                      refcnt;
        void (*saved_unhash)(struct sock *sk);
        void (*saved_close)(struct sock *sk, long timeout);
        void (*saved_write_space)(struct sock *sk);
        struct proto                    *sk_proto;
        struct sk_psock_work_state      work_state;
        struct work_struct              work;
        union {
                struct rcu_head         rcu;
                struct work_struct      gc;
        };
};

int sk_msg_alloc(struct sock *sk, struct sk_msg *msg, int len,
                 int elem_first_coalesce);
int sk_msg_clone(struct sock *sk, struct sk_msg *dst, struct sk_msg *src,
                 u32 off, u32 len);
void sk_msg_trim(struct sock *sk, struct sk_msg *msg, int len);
int sk_msg_free(struct sock *sk, struct sk_msg *msg);
int sk_msg_free_nocharge(struct sock *sk, struct sk_msg *msg);
void sk_msg_free_partial(struct sock *sk, struct sk_msg *msg, u32 bytes);
void sk_msg_free_partial_nocharge(struct sock *sk, struct sk_msg *msg,
                                  u32 bytes);

void sk_msg_return(struct sock *sk, struct sk_msg *msg, int bytes);
void sk_msg_return_zero(struct sock *sk, struct sk_msg *msg, int bytes);

int sk_msg_zerocopy_from_iter(struct sock *sk, struct iov_iter *from,
                              struct sk_msg *msg, u32 bytes);
int sk_msg_memcopy_from_iter(struct sock *sk, struct iov_iter *from,
                             struct sk_msg *msg, u32 bytes);

static inline void sk_msg_check_to_free(struct sk_msg *msg, u32 i, u32 bytes)
{
        WARN_ON(i == msg->sg.end && bytes);
}

static inline void sk_msg_apply_bytes(struct sk_psock *psock, u32 bytes)
{
        if (psock->apply_bytes) {
                if (psock->apply_bytes < bytes)
                        psock->apply_bytes = 0;
                else
                        psock->apply_bytes -= bytes;
        }
}

static inline u32 sk_msg_iter_dist(u32 start, u32 end)
{
        return end >= start ? end - start : end + (MAX_MSG_FRAGS - start);
}

#define sk_msg_iter_var_prev(var)                       \
        do {                                            \
                if (var == 0)                           \
                        var = MAX_MSG_FRAGS - 1;        \
                else                                    \
                        var--;                          \
        } while (0)

#define sk_msg_iter_var_next(var)                       \
        do {                                            \
                var++;                                  \
                if (var == MAX_MSG_FRAGS)               \
                        var = 0;                        \
        } while (0)

#define sk_msg_iter_prev(msg, which)                    \
        sk_msg_iter_var_prev(msg->sg.which)

#define sk_msg_iter_next(msg, which)                    \
        sk_msg_iter_var_next(msg->sg.which)

static inline void sk_msg_clear_meta(struct sk_msg *msg)
{
        memset(&msg->sg, 0, offsetofend(struct sk_msg_sg, copy));
}

static inline void sk_msg_init(struct sk_msg *msg)
{
        BUILD_BUG_ON(ARRAY_SIZE(msg->sg.data) - 1 != MAX_MSG_FRAGS);
        memset(msg, 0, sizeof(*msg));
        sg_init_marker(msg->sg.data, MAX_MSG_FRAGS);
}

static inline void sk_msg_xfer(struct sk_msg *dst, struct sk_msg *src,
                               int which, u32 size)
{
        dst->sg.data[which] = src->sg.data[which];
        dst->sg.data[which].length  = size;
        dst->sg.size               += size;
        src->sg.data[which].length -= size;
        src->sg.data[which].offset += size;
}

static inline void sk_msg_xfer_full(struct sk_msg *dst, struct sk_msg *src)
{
        memcpy(dst, src, sizeof(*src));
        sk_msg_init(src);
}

static inline bool sk_msg_full(const struct sk_msg *msg)
{
        return (msg->sg.end == msg->sg.start) && msg->sg.size;
}

static inline u32 sk_msg_elem_used(const struct sk_msg *msg)
{
        if (sk_msg_full(msg))
                return MAX_MSG_FRAGS;

        return sk_msg_iter_dist(msg->sg.start, msg->sg.end);
}

static inline struct scatterlist *sk_msg_elem(struct sk_msg *msg, int which)
{
        return &msg->sg.data[which];
}

static inline struct scatterlist sk_msg_elem_cpy(struct sk_msg *msg, int which)
{
        return msg->sg.data[which];
}

static inline struct page *sk_msg_page(struct sk_msg *msg, int which)
{
        return sg_page(sk_msg_elem(msg, which));
}

static inline bool sk_msg_to_ingress(const struct sk_msg *msg)
{
        return msg->flags & BPF_F_INGRESS;
}

static inline void sk_msg_compute_data_pointers(struct sk_msg *msg)
{
        struct scatterlist *sge = sk_msg_elem(msg, msg->sg.start);

        if (msg->sg.copy[msg->sg.start]) {
                msg->data = NULL;
                msg->data_end = NULL;
        } else {
                msg->data = sg_virt(sge);
                msg->data_end = msg->data + sge->length;
        }
}

static inline void sk_msg_page_add(struct sk_msg *msg, struct page *page,
                                   u32 len, u32 offset)
{
        struct scatterlist *sge;

        get_page(page);
        sge = sk_msg_elem(msg, msg->sg.end);
        sg_set_page(sge, page, len, offset);
        sg_unmark_end(sge);

        msg->sg.copy[msg->sg.end] = true;
        msg->sg.size += len;
        sk_msg_iter_next(msg, end);
}

static inline void sk_msg_sg_copy(struct sk_msg *msg, u32 i, bool copy_state)
{
        do {
                msg->sg.copy[i] = copy_state;
                sk_msg_iter_var_next(i);
                if (i == msg->sg.end)
                        break;
        } while (1);
}

static inline void sk_msg_sg_copy_set(struct sk_msg *msg, u32 start)
{
        sk_msg_sg_copy(msg, start, true);
}

static inline void sk_msg_sg_copy_clear(struct sk_msg *msg, u32 start)
{
        sk_msg_sg_copy(msg, start, false);
}

static inline struct sk_psock *sk_psock(const struct sock *sk)
{
        return rcu_dereference_sk_user_data(sk);
}

static inline void sk_psock_queue_msg(struct sk_psock *psock,
                                      struct sk_msg *msg)
{
        list_add_tail(&msg->list, &psock->ingress_msg);
}

static inline bool sk_psock_queue_empty(const struct sk_psock *psock)
{
        return psock ? list_empty(&psock->ingress_msg) : true;
}

static inline void sk_psock_report_error(struct sk_psock *psock, int err)
{
        struct sock *sk = psock->sk;

        sk->sk_err = err;
        sk->sk_error_report(sk);
}

struct sk_psock *sk_psock_init(struct sock *sk, int node);

int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock);
void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock);
void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock);

int sk_psock_msg_verdict(struct sock *sk, struct sk_psock *psock,
                         struct sk_msg *msg);

static inline struct sk_psock_link *sk_psock_init_link(void)
{
        return kzalloc(sizeof(struct sk_psock_link),
                       GFP_ATOMIC | __GFP_NOWARN);
}

static inline void sk_psock_free_link(struct sk_psock_link *link)
{
        kfree(link);
}

struct sk_psock_link *sk_psock_link_pop(struct sk_psock *psock);
#if defined(CONFIG_BPF_STREAM_PARSER)
void sk_psock_unlink(struct sock *sk, struct sk_psock_link *link);
#else
static inline void sk_psock_unlink(struct sock *sk,
                                   struct sk_psock_link *link)
{
}
#endif

void __sk_psock_purge_ingress_msg(struct sk_psock *psock);

static inline void sk_psock_cork_free(struct sk_psock *psock)
{
        if (psock->cork) {
                sk_msg_free(psock->sk, psock->cork);
                kfree(psock->cork);
                psock->cork = NULL;
        }
}

static inline void sk_psock_update_proto(struct sock *sk,
                                         struct sk_psock *psock,
                                         struct proto *ops)
{
        psock->saved_unhash = sk->sk_prot->unhash;
        psock->saved_close = sk->sk_prot->close;
        psock->saved_write_space = sk->sk_write_space;

        psock->sk_proto = sk->sk_prot;
        sk->sk_prot = ops;
}

static inline void sk_psock_restore_proto(struct sock *sk,
                                          struct sk_psock *psock)
{
        sk->sk_write_space = psock->saved_write_space;

        if (psock->sk_proto) {
                struct inet_connection_sock *icsk = inet_csk(sk);
                bool has_ulp = !!icsk->icsk_ulp_data;

                if (has_ulp)
                        tcp_update_ulp(sk, psock->sk_proto);
                else
                        sk->sk_prot = psock->sk_proto;
                psock->sk_proto = NULL;
        }
}

static inline void sk_psock_set_state(struct sk_psock *psock,
                                      enum sk_psock_state_bits bit)
{
        set_bit(bit, &psock->state);
}

static inline void sk_psock_clear_state(struct sk_psock *psock,
                                        enum sk_psock_state_bits bit)
{
        clear_bit(bit, &psock->state);
}

static inline bool sk_psock_test_state(const struct sk_psock *psock,
                                       enum sk_psock_state_bits bit)
{
        return test_bit(bit, &psock->state);
}

static inline struct sk_psock *sk_psock_get_checked(struct sock *sk)
{
        struct sk_psock *psock;

        rcu_read_lock();
        psock = sk_psock(sk);
        if (psock) {
                if (sk->sk_prot->recvmsg != tcp_bpf_recvmsg) {
                        psock = ERR_PTR(-EBUSY);
                        goto out;
                }

                if (!refcount_inc_not_zero(&psock->refcnt))
                        psock = ERR_PTR(-EBUSY);
        }
out:
        rcu_read_unlock();
        return psock;
}

static inline struct sk_psock *sk_psock_get(struct sock *sk)
{
        struct sk_psock *psock;

        rcu_read_lock();
        psock = sk_psock(sk);
        if (psock && !refcount_inc_not_zero(&psock->refcnt))
                psock = NULL;
        rcu_read_unlock();
        return psock;
}

void sk_psock_stop(struct sock *sk, struct sk_psock *psock);
void sk_psock_destroy(struct rcu_head *rcu);
void sk_psock_drop(struct sock *sk, struct sk_psock *psock);

static inline void sk_psock_put(struct sock *sk, struct sk_psock *psock)
{
        if (refcount_dec_and_test(&psock->refcnt))
                sk_psock_drop(sk, psock);
}

static inline void sk_psock_data_ready(struct sock *sk, struct sk_psock *psock)
{
        if (psock->parser.enabled)
                psock->parser.saved_data_ready(sk);
        else
                sk->sk_data_ready(sk);
}

static inline void psock_set_prog(struct bpf_prog **pprog,
                                  struct bpf_prog *prog)
{
        prog = xchg(pprog, prog);
        if (prog)
                bpf_prog_put(prog);
}

static inline void psock_progs_drop(struct sk_psock_progs *progs)
{
        psock_set_prog(&progs->msg_parser, NULL);
        psock_set_prog(&progs->skb_parser, NULL);
        psock_set_prog(&progs->skb_verdict, NULL);
}

#endif /* _LINUX_SKMSG_H */