// SPDX-License-Identifier: GPL-2.0-only
/* drivers/atm/atmtcp.c - ATM over TCP "device" driver */

/* Written 1997-2000 by Werner Almesberger, EPFL LRC/ICA */


#include <linux/module.h>
#include <linux/wait.h>
#include <linux/atmdev.h>
#include <linux/atm_tcp.h>
#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/atomic.h>


extern int atm_init_aal5(struct atm_vcc *vcc); /* "raw" AAL5 transport */


#define PRIV(dev) ((struct atmtcp_dev_data *) ((dev)->dev_data))


struct atmtcp_dev_data {
        struct atm_vcc *vcc;    /* control VCC; NULL if detached */
        int persist;            /* non-zero if persistent */
};


#define DEV_LABEL    "atmtcp"

#define MAX_VPI_BITS  8 /* simplifies life */
#define MAX_VCI_BITS 16


/*
 * Hairy code ahead: the control VCC may be closed while we're still
 * waiting for an answer, so we need to re-validate out_vcc every once
 * in a while.
 */


static int atmtcp_send_control(struct atm_vcc *vcc,int type,
    const struct atmtcp_control *msg,int flag)
{
        DECLARE_WAITQUEUE(wait,current);
        struct atm_vcc *out_vcc;
        struct sk_buff *skb;
        struct atmtcp_control *new_msg;
        int old_test;
        int error = 0;

        out_vcc = PRIV(vcc->dev) ? PRIV(vcc->dev)->vcc : NULL;
        if (!out_vcc) return -EUNATCH;
        skb = alloc_skb(sizeof(*msg),GFP_KERNEL);
        if (!skb) return -ENOMEM;
        mb();
        out_vcc = PRIV(vcc->dev) ? PRIV(vcc->dev)->vcc : NULL;
        if (!out_vcc) {
                dev_kfree_skb(skb);
                return -EUNATCH;
        }
        atm_force_charge(out_vcc,skb->truesize);
        new_msg = skb_put(skb, sizeof(*new_msg));
        *new_msg = *msg;
        new_msg->hdr.length = ATMTCP_HDR_MAGIC;
        new_msg->type = type;
        memset(&new_msg->vcc,0,sizeof(atm_kptr_t));
        *(struct atm_vcc **) &new_msg->vcc = vcc;
        old_test = test_bit(flag,&vcc->flags);
        out_vcc->push(out_vcc,skb);
        add_wait_queue(sk_sleep(sk_atm(vcc)), &wait);
        while (test_bit(flag,&vcc->flags) == old_test) {
                mb();
                out_vcc = PRIV(vcc->dev) ? PRIV(vcc->dev)->vcc : NULL;
                if (!out_vcc) {
                        error = -EUNATCH;
                        break;
                }
                set_current_state(TASK_UNINTERRUPTIBLE);
                schedule();
        }
        set_current_state(TASK_RUNNING);
        remove_wait_queue(sk_sleep(sk_atm(vcc)), &wait);
        return error;
}


static int atmtcp_recv_control(const struct atmtcp_control *msg)
{
        struct atm_vcc *vcc = *(struct atm_vcc **) &msg->vcc;

        vcc->vpi = msg->addr.sap_addr.vpi;
        vcc->vci = msg->addr.sap_addr.vci;
        vcc->qos = msg->qos;
        sk_atm(vcc)->sk_err = -msg->result;
        switch (msg->type) {
            case ATMTCP_CTRL_OPEN:
                change_bit(ATM_VF_READY,&vcc->flags);
                break;
            case ATMTCP_CTRL_CLOSE:
                change_bit(ATM_VF_ADDR,&vcc->flags);
                break;
            default:
                printk(KERN_ERR "atmtcp_recv_control: unknown type %d\n",
                    msg->type);
                return -EINVAL;
        }
        wake_up(sk_sleep(sk_atm(vcc)));
        return 0;
}


static void atmtcp_v_dev_close(struct atm_dev *dev)
{
        /* Nothing.... Isn't this simple :-)  -- REW */
}


static int atmtcp_v_open(struct atm_vcc *vcc)
{
        struct atmtcp_control msg;
        int error;
        short vpi = vcc->vpi;
        int vci = vcc->vci;

        memset(&msg,0,sizeof(msg));
        msg.addr.sap_family = AF_ATMPVC;
        msg.hdr.vpi = htons(vpi);
        msg.addr.sap_addr.vpi = vpi;
        msg.hdr.vci = htons(vci);
        msg.addr.sap_addr.vci = vci;
        if (vpi == ATM_VPI_UNSPEC || vci == ATM_VCI_UNSPEC) return 0;
        msg.type = ATMTCP_CTRL_OPEN;
        msg.qos = vcc->qos;
        set_bit(ATM_VF_ADDR,&vcc->flags);
        clear_bit(ATM_VF_READY,&vcc->flags); /* just in case ... */
        error = atmtcp_send_control(vcc,ATMTCP_CTRL_OPEN,&msg,ATM_VF_READY);
        if (error) return error;
        return -sk_atm(vcc)->sk_err;
}


static void atmtcp_v_close(struct atm_vcc *vcc)
{
        struct atmtcp_control msg;

        memset(&msg,0,sizeof(msg));
        msg.addr.sap_family = AF_ATMPVC;
        msg.addr.sap_addr.vpi = vcc->vpi;
        msg.addr.sap_addr.vci = vcc->vci;
        clear_bit(ATM_VF_READY,&vcc->flags);
        (void) atmtcp_send_control(vcc,ATMTCP_CTRL_CLOSE,&msg,ATM_VF_ADDR);
}


static int atmtcp_v_ioctl(struct atm_dev *dev,unsigned int cmd,void __user *arg)
{
        struct atm_cirange ci;
        struct atm_vcc *vcc;
        struct sock *s;
        int i;

        if (cmd != ATM_SETCIRANGE) return -ENOIOCTLCMD;
        if (copy_from_user(&ci, arg,sizeof(ci))) return -EFAULT;
        if (ci.vpi_bits == ATM_CI_MAX) ci.vpi_bits = MAX_VPI_BITS;
        if (ci.vci_bits == ATM_CI_MAX) ci.vci_bits = MAX_VCI_BITS;
        if (ci.vpi_bits > MAX_VPI_BITS || ci.vpi_bits < 0 ||
            ci.vci_bits > MAX_VCI_BITS || ci.vci_bits < 0) return -EINVAL;
        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);
                        if (vcc->dev != dev)
                                continue;
                        if ((vcc->vpi >> ci.vpi_bits) ||
                            (vcc->vci >> ci.vci_bits)) {
                                read_unlock(&vcc_sklist_lock);
                                return -EBUSY;
                        }
                }
        }
        read_unlock(&vcc_sklist_lock);
        dev->ci_range = ci;
        return 0;
}


static int atmtcp_v_send(struct atm_vcc *vcc,struct sk_buff *skb)
{
        struct atmtcp_dev_data *dev_data;
        struct atm_vcc *out_vcc=NULL; /* Initializer quietens GCC warning */
        struct sk_buff *new_skb;
        struct atmtcp_hdr *hdr;
        int size;

        if (vcc->qos.txtp.traffic_class == ATM_NONE) {
                if (vcc->pop) vcc->pop(vcc,skb);
                else dev_kfree_skb(skb);
                return -EINVAL;
        }
        dev_data = PRIV(vcc->dev);
        if (dev_data) out_vcc = dev_data->vcc;
        if (!dev_data || !out_vcc) {
                if (vcc->pop) vcc->pop(vcc,skb);
                else dev_kfree_skb(skb);
                if (dev_data) return 0;
                atomic_inc(&vcc->stats->tx_err);
                return -ENOLINK;
        }
        size = skb->len+sizeof(struct atmtcp_hdr);
        new_skb = atm_alloc_charge(out_vcc,size,GFP_ATOMIC);
        if (!new_skb) {
                if (vcc->pop) vcc->pop(vcc,skb);
                else dev_kfree_skb(skb);
                atomic_inc(&vcc->stats->tx_err);
                return -ENOBUFS;
        }
        hdr = skb_put(new_skb, sizeof(struct atmtcp_hdr));
        hdr->vpi = htons(vcc->vpi);
        hdr->vci = htons(vcc->vci);
        hdr->length = htonl(skb->len);
        skb_copy_from_linear_data(skb, skb_put(new_skb, skb->len), skb->len);
        if (vcc->pop) vcc->pop(vcc,skb);
        else dev_kfree_skb(skb);
        out_vcc->push(out_vcc,new_skb);
        atomic_inc(&vcc->stats->tx);
        atomic_inc(&out_vcc->stats->rx);
        return 0;
}


static int atmtcp_v_proc(struct atm_dev *dev,loff_t *pos,char *page)
{
        struct atmtcp_dev_data *dev_data = PRIV(dev);

        if (*pos) return 0;
        if (!dev_data->persist) return sprintf(page,"ephemeral\n");
        return sprintf(page,"persistent, %sconnected\n",
            dev_data->vcc ? "" : "dis");
}


static void atmtcp_c_close(struct atm_vcc *vcc)
{
        struct atm_dev *atmtcp_dev;
        struct atmtcp_dev_data *dev_data;

        atmtcp_dev = (struct atm_dev *) vcc->dev_data;
        dev_data = PRIV(atmtcp_dev);
        dev_data->vcc = NULL;
        if (dev_data->persist) return;
        atmtcp_dev->dev_data = NULL;
        kfree(dev_data);
        atm_dev_deregister(atmtcp_dev);
        vcc->dev_data = NULL;
        module_put(THIS_MODULE);
}


static struct atm_vcc *find_vcc(struct atm_dev *dev, short vpi, int vci)
{
        struct hlist_head *head;
        struct atm_vcc *vcc;
        struct sock *s;

        head = &vcc_hash[vci & (VCC_HTABLE_SIZE -1)];

        sk_for_each(s, head) {
                vcc = atm_sk(s);
                if (vcc->dev == dev &&
                    vcc->vci == vci && vcc->vpi == vpi &&
                    vcc->qos.rxtp.traffic_class != ATM_NONE) {
                                return vcc;
                }
        }
        return NULL;
}

static int atmtcp_c_pre_send(struct atm_vcc *vcc, struct sk_buff *skb)
{
        struct atmtcp_hdr *hdr;

        if (skb->len < sizeof(struct atmtcp_hdr))
                return -EINVAL;

        hdr = (struct atmtcp_hdr *)skb->data;
        if (hdr->length == ATMTCP_HDR_MAGIC)
                return -EINVAL;

        return 0;
}

static int atmtcp_c_send(struct atm_vcc *vcc,struct sk_buff *skb)
{
        struct atm_dev *dev;
        struct atmtcp_hdr *hdr;
        struct atm_vcc *out_vcc;
        struct sk_buff *new_skb;
        int result = 0;

        dev = vcc->dev_data;
        hdr = (struct atmtcp_hdr *) skb->data;
        if (hdr->length == ATMTCP_HDR_MAGIC) {
                result = atmtcp_recv_control(
                    (struct atmtcp_control *) skb->data);
                goto done;
        }
        read_lock(&vcc_sklist_lock);
        out_vcc = find_vcc(dev, ntohs(hdr->vpi), ntohs(hdr->vci));
        read_unlock(&vcc_sklist_lock);
        if (!out_vcc) {
                result = -EUNATCH;
                atomic_inc(&vcc->stats->tx_err);
                goto done;
        }
        skb_pull(skb,sizeof(struct atmtcp_hdr));
        new_skb = atm_alloc_charge(out_vcc,skb->len,GFP_KERNEL);
        if (!new_skb) {
                result = -ENOBUFS;
                goto done;
        }
        __net_timestamp(new_skb);
        skb_copy_from_linear_data(skb, skb_put(new_skb, skb->len), skb->len);
        out_vcc->push(out_vcc,new_skb);
        atomic_inc(&vcc->stats->tx);
        atomic_inc(&out_vcc->stats->rx);
done:
        if (vcc->pop) vcc->pop(vcc,skb);
        else dev_kfree_skb(skb);
        return result;
}


/*
 * Device operations for the virtual ATM devices created by ATMTCP.
 */


static const struct atmdev_ops atmtcp_v_dev_ops = {
        .dev_close      = atmtcp_v_dev_close,
        .open           = atmtcp_v_open,
        .close          = atmtcp_v_close,
        .ioctl          = atmtcp_v_ioctl,
        .send           = atmtcp_v_send,
        .proc_read      = atmtcp_v_proc,
        .owner          = THIS_MODULE
};


/*
 * Device operations for the ATMTCP control device.
 */


static const struct atmdev_ops atmtcp_c_dev_ops = {
        .close          = atmtcp_c_close,
        .pre_send       = atmtcp_c_pre_send,
        .send           = atmtcp_c_send
};


static struct atm_dev atmtcp_control_dev = {
        .ops            = &atmtcp_c_dev_ops,
        .type           = "atmtcp",
        .number         = 999,
        .lock           = __SPIN_LOCK_UNLOCKED(atmtcp_control_dev.lock)
};


static int atmtcp_create(int itf,int persist,struct atm_dev **result)
{
        struct atmtcp_dev_data *dev_data;
        struct atm_dev *dev;

        dev_data = kmalloc_obj(*dev_data);
        if (!dev_data)
                return -ENOMEM;

        dev = atm_dev_register(DEV_LABEL,NULL,&atmtcp_v_dev_ops,itf,NULL);
        if (!dev) {
                kfree(dev_data);
                return itf == -1 ? -ENOMEM : -EBUSY;
        }
        dev->ci_range.vpi_bits = MAX_VPI_BITS;
        dev->ci_range.vci_bits = MAX_VCI_BITS;
        dev->dev_data = dev_data;
        PRIV(dev)->vcc = NULL;
        PRIV(dev)->persist = persist;
        if (result) *result = dev;
        return 0;
}


static int atmtcp_attach(struct atm_vcc *vcc,int itf)
{
        struct atm_dev *dev;

        dev = NULL;
        if (itf != -1) dev = atm_dev_lookup(itf);
        if (dev) {
                if (dev->ops != &atmtcp_v_dev_ops) {
                        atm_dev_put(dev);
                        return -EMEDIUMTYPE;
                }
                if (PRIV(dev)->vcc) {
                        atm_dev_put(dev);
                        return -EBUSY;
                }
        }
        else {
                int error;

                error = atmtcp_create(itf,0,&dev);
                if (error) return error;
        }
        PRIV(dev)->vcc = vcc;
        vcc->dev = &atmtcp_control_dev;
        vcc_insert_socket(sk_atm(vcc));
        set_bit(ATM_VF_META,&vcc->flags);
        set_bit(ATM_VF_READY,&vcc->flags);
        vcc->dev_data = dev;
        (void) atm_init_aal5(vcc); /* @@@ losing AAL in transit ... */
        vcc->stats = &atmtcp_control_dev.stats.aal5;
        return dev->number;
}


static int atmtcp_create_persistent(int itf)
{
        return atmtcp_create(itf,1,NULL);
}


static int atmtcp_remove_persistent(int itf)
{
        struct atm_dev *dev;
        struct atmtcp_dev_data *dev_data;

        dev = atm_dev_lookup(itf);
        if (!dev) return -ENODEV;
        if (dev->ops != &atmtcp_v_dev_ops) {
                atm_dev_put(dev);
                return -EMEDIUMTYPE;
        }
        dev_data = PRIV(dev);
        if (!dev_data->persist) {
                atm_dev_put(dev);
                return 0;
        }
        dev_data->persist = 0;
        if (PRIV(dev)->vcc) {
                atm_dev_put(dev);
                return 0;
        }
        kfree(dev_data);
        atm_dev_put(dev);
        atm_dev_deregister(dev);
        return 0;
}

static int atmtcp_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        int err = 0;
        struct atm_vcc *vcc = ATM_SD(sock);

        if (cmd != SIOCSIFATMTCP && cmd != ATMTCP_CREATE && cmd != ATMTCP_REMOVE)
                return -ENOIOCTLCMD;

        if (!capable(CAP_NET_ADMIN))
                return -EPERM;

        switch (cmd) {
                case SIOCSIFATMTCP:
                        err = atmtcp_attach(vcc, (int) arg);
                        if (err >= 0) {
                                sock->state = SS_CONNECTED;
                                __module_get(THIS_MODULE);
                        }
                        break;
                case ATMTCP_CREATE:
                        err = atmtcp_create_persistent((int) arg);
                        break;
                case ATMTCP_REMOVE:
                        err = atmtcp_remove_persistent((int) arg);
                        break;
        }
        return err;
}

static struct atm_ioctl atmtcp_ioctl_ops = {
        .owner  = THIS_MODULE,
        .ioctl  = atmtcp_ioctl,
};

static __init int atmtcp_init(void)
{
        register_atm_ioctl(&atmtcp_ioctl_ops);
        return 0;
}


static void __exit atmtcp_exit(void)
{
        deregister_atm_ioctl(&atmtcp_ioctl_ops);
}

MODULE_DESCRIPTION("ATM over TCP");
MODULE_LICENSE("GPL");
module_init(atmtcp_init);
module_exit(atmtcp_exit);