// SPDX-License-Identifier: GPL-2.0
/* net/atm/signaling.c - ATM signaling */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/errno.h>        /* error codes */
#include <linux/kernel.h>       /* printk */
#include <linux/skbuff.h>
#include <linux/wait.h>
#include <linux/sched.h>        /* jiffies and HZ */
#include <linux/atm.h>          /* ATM stuff */
#include <linux/atmsap.h>
#include <linux/atmsvc.h>
#include <linux/atmdev.h>
#include <linux/bitops.h>
#include <linux/slab.h>

#include "resources.h"
#include "signaling.h"

struct atm_vcc *sigd = NULL;

/*
 * find_get_vcc - validate and get a reference to a vcc pointer
 * @vcc: the vcc pointer to validate
 *
 * This function validates that @vcc points to a registered VCC in vcc_hash.
 * If found, it increments the socket reference count and returns the vcc.
 * The caller must call sock_put(sk_atm(vcc)) when done.
 *
 * Returns the vcc pointer if valid, NULL otherwise.
 */
static struct atm_vcc *find_get_vcc(struct atm_vcc *vcc)
{
        int i;

        read_lock(&vcc_sklist_lock);
        for (i = 0; i < VCC_HTABLE_SIZE; i++) {
                struct sock *s;

                sk_for_each(s, &vcc_hash[i]) {
                        if (atm_sk(s) == vcc) {
                                sock_hold(s);
                                read_unlock(&vcc_sklist_lock);
                                return vcc;
                        }
                }
        }
        read_unlock(&vcc_sklist_lock);
        return NULL;
}

static void sigd_put_skb(struct sk_buff *skb)
{
        if (!sigd) {
                pr_debug("atmsvc: no signaling daemon\n");
                kfree_skb(skb);
                return;
        }
        atm_force_charge(sigd, skb->truesize);
        skb_queue_tail(&sk_atm(sigd)->sk_receive_queue, skb);
        sk_atm(sigd)->sk_data_ready(sk_atm(sigd));
}

static void modify_qos(struct atm_vcc *vcc, struct atmsvc_msg *msg)
{
        struct sk_buff *skb;

        if (test_bit(ATM_VF_RELEASED, &vcc->flags) ||
            !test_bit(ATM_VF_READY, &vcc->flags))
                return;
        msg->type = as_error;
        if (!vcc->dev->ops->change_qos)
                msg->reply = -EOPNOTSUPP;
        else {
                /* should lock VCC */
                msg->reply = vcc->dev->ops->change_qos(vcc, &msg->qos,
                                                       msg->reply);
                if (!msg->reply)
                        msg->type = as_okay;
        }
        /*
         * Should probably just turn around the old skb. But then, the buffer
         * space accounting needs to follow the change too. Maybe later.
         */
        while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
                schedule();
        *(struct atmsvc_msg *)skb_put(skb, sizeof(struct atmsvc_msg)) = *msg;
        sigd_put_skb(skb);
}

static int sigd_send(struct atm_vcc *vcc, struct sk_buff *skb)
{
        struct atmsvc_msg *msg;
        struct atm_vcc *session_vcc;
        struct sock *sk;

        msg = (struct atmsvc_msg *) skb->data;
        WARN_ON(refcount_sub_and_test(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc));

        vcc = find_get_vcc(*(struct atm_vcc **)&msg->vcc);
        if (!vcc) {
                pr_debug("invalid vcc pointer in msg\n");
                dev_kfree_skb(skb);
                return -EINVAL;
        }

        pr_debug("%d (0x%lx)\n", (int)msg->type, (unsigned long)vcc);
        sk = sk_atm(vcc);

        switch (msg->type) {
        case as_okay:
                sk->sk_err = -msg->reply;
                clear_bit(ATM_VF_WAITING, &vcc->flags);
                if (!*vcc->local.sas_addr.prv && !*vcc->local.sas_addr.pub) {
                        vcc->local.sas_family = AF_ATMSVC;
                        memcpy(vcc->local.sas_addr.prv,
                               msg->local.sas_addr.prv, ATM_ESA_LEN);
                        memcpy(vcc->local.sas_addr.pub,
                               msg->local.sas_addr.pub, ATM_E164_LEN + 1);
                }
                session_vcc = vcc->session ? vcc->session : vcc;
                if (session_vcc->vpi || session_vcc->vci)
                        break;
                session_vcc->itf = msg->pvc.sap_addr.itf;
                session_vcc->vpi = msg->pvc.sap_addr.vpi;
                session_vcc->vci = msg->pvc.sap_addr.vci;
                if (session_vcc->vpi || session_vcc->vci)
                        session_vcc->qos = msg->qos;
                break;
        case as_error:
                clear_bit(ATM_VF_REGIS, &vcc->flags);
                clear_bit(ATM_VF_READY, &vcc->flags);
                sk->sk_err = -msg->reply;
                clear_bit(ATM_VF_WAITING, &vcc->flags);
                break;
        case as_indicate:
                /* Release the reference from msg->vcc, we'll use msg->listen_vcc instead */
                sock_put(sk);

                vcc = find_get_vcc(*(struct atm_vcc **)&msg->listen_vcc);
                if (!vcc) {
                        pr_debug("invalid listen_vcc pointer in msg\n");
                        dev_kfree_skb(skb);
                        return -EINVAL;
                }

                sk = sk_atm(vcc);
                pr_debug("as_indicate!!!\n");
                lock_sock(sk);
                if (sk_acceptq_is_full(sk)) {
                        sigd_enq(NULL, as_reject, vcc, NULL, NULL);
                        dev_kfree_skb(skb);
                        goto as_indicate_complete;
                }
                sk_acceptq_added(sk);
                skb_queue_tail(&sk->sk_receive_queue, skb);
                pr_debug("waking sk_sleep(sk) 0x%p\n", sk_sleep(sk));
                sk->sk_state_change(sk);
as_indicate_complete:
                release_sock(sk);
                /* Paired with find_get_vcc(msg->listen_vcc) above */
                sock_put(sk);
                return 0;
        case as_close:
                set_bit(ATM_VF_RELEASED, &vcc->flags);
                vcc_release_async(vcc, msg->reply);
                goto out;
        case as_modify:
                modify_qos(vcc, msg);
                break;
        case as_addparty:
        case as_dropparty:
                WRITE_ONCE(sk->sk_err_soft, -msg->reply);
                                        /* < 0 failure, otherwise ep_ref */
                clear_bit(ATM_VF_WAITING, &vcc->flags);
                break;
        default:
                pr_alert("bad message type %d\n", (int)msg->type);
                /* Paired with find_get_vcc(msg->vcc) above */
                sock_put(sk);
                return -EINVAL;
        }
        sk->sk_state_change(sk);
out:
        dev_kfree_skb(skb);
        /* Paired with find_get_vcc(msg->vcc) above */
        sock_put(sk);
        return 0;
}

void sigd_enq2(struct atm_vcc *vcc, enum atmsvc_msg_type type,
               struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
               const struct sockaddr_atmsvc *svc, const struct atm_qos *qos,
               int reply)
{
        struct sk_buff *skb;
        struct atmsvc_msg *msg;
        static unsigned int session = 0;

        pr_debug("%d (0x%p)\n", (int)type, vcc);
        while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
                schedule();
        msg = skb_put_zero(skb, sizeof(struct atmsvc_msg));
        msg->type = type;
        *(struct atm_vcc **) &msg->vcc = vcc;
        *(struct atm_vcc **) &msg->listen_vcc = listen_vcc;
        msg->reply = reply;
        if (qos)
                msg->qos = *qos;
        if (vcc)
                msg->sap = vcc->sap;
        if (svc)
                msg->svc = *svc;
        if (vcc)
                msg->local = vcc->local;
        if (pvc)
                msg->pvc = *pvc;
        if (vcc) {
                if (type == as_connect && test_bit(ATM_VF_SESSION, &vcc->flags))
                        msg->session = ++session;
                        /* every new pmp connect gets the next session number */
        }
        sigd_put_skb(skb);
        if (vcc)
                set_bit(ATM_VF_REGIS, &vcc->flags);
}

void sigd_enq(struct atm_vcc *vcc, enum atmsvc_msg_type type,
              struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
              const struct sockaddr_atmsvc *svc)
{
        sigd_enq2(vcc, type, listen_vcc, pvc, svc, vcc ? &vcc->qos : NULL, 0);
        /* other ISP applications may use "reply" */
}

static void purge_vcc(struct atm_vcc *vcc)
{
        if (sk_atm(vcc)->sk_family == PF_ATMSVC &&
            !test_bit(ATM_VF_META, &vcc->flags)) {
                set_bit(ATM_VF_RELEASED, &vcc->flags);
                clear_bit(ATM_VF_REGIS, &vcc->flags);
                vcc_release_async(vcc, -EUNATCH);
        }
}

static void sigd_close(struct atm_vcc *vcc)
{
        struct sock *s;
        int i;

        pr_debug("\n");
        sigd = NULL;
        if (skb_peek(&sk_atm(vcc)->sk_receive_queue))
                pr_err("closing with requests pending\n");
        skb_queue_purge(&sk_atm(vcc)->sk_receive_queue);

        read_lock(&vcc_sklist_lock);
        for (i = 0; i < VCC_HTABLE_SIZE; ++i) {
                struct hlist_head *head = &vcc_hash[i];

                sk_for_each(s, head) {
                        vcc = atm_sk(s);

                        purge_vcc(vcc);
                }
        }
        read_unlock(&vcc_sklist_lock);
}

static const struct atmdev_ops sigd_dev_ops = {
        .close = sigd_close,
        .send = sigd_send
};

static struct atm_dev sigd_dev = {
        .ops =          &sigd_dev_ops,
        .type =         "sig",
        .number =       999,
        .lock =         __SPIN_LOCK_UNLOCKED(sigd_dev.lock)
};

int sigd_attach(struct atm_vcc *vcc)
{
        if (sigd)
                return -EADDRINUSE;
        pr_debug("\n");
        sigd = vcc;
        vcc->dev = &sigd_dev;
        vcc_insert_socket(sk_atm(vcc));
        set_bit(ATM_VF_META, &vcc->flags);
        set_bit(ATM_VF_READY, &vcc->flags);
        return 0;
}