LXR linux/net/qrtr/tun.c

   1// SPDX-License-Identifier: GPL-2.0
   2/* Copyright (c) 2018, Linaro Ltd */
   3
   4#include <linux/miscdevice.h>
   5#include <linux/module.h>
   6#include <linux/poll.h>
   7#include <linux/skbuff.h>
   8#include <linux/uaccess.h>
   9
  10#include "qrtr.h"
  11
  12struct qrtr_tun {
  13        struct qrtr_endpoint ep;
  14
  15        struct sk_buff_head queue;
  16        wait_queue_head_t readq;
  17};
  18
  19static int qrtr_tun_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
  20{
  21        struct qrtr_tun *tun = container_of(ep, struct qrtr_tun, ep);
  22
  23        skb_queue_tail(&tun->queue, skb);
  24
  25        /* wake up any blocking processes, waiting for new data */
  26        wake_up_interruptible(&tun->readq);
  27
  28        return 0;
  29}
  30
  31static int qrtr_tun_open(struct inode *inode, struct file *filp)
  32{
  33        struct qrtr_tun *tun;
  34
  35        tun = kzalloc(sizeof(*tun), GFP_KERNEL);
  36        if (!tun)
  37                return -ENOMEM;
  38
  39        skb_queue_head_init(&tun->queue);
  40        init_waitqueue_head(&tun->readq);
  41
  42        tun->ep.xmit = qrtr_tun_send;
  43
  44        filp->private_data = tun;
  45
  46        return qrtr_endpoint_register(&tun->ep, QRTR_EP_NID_AUTO);
  47}
  48
  49static ssize_t qrtr_tun_read_iter(struct kiocb *iocb, struct iov_iter *to)
  50{
  51        struct file *filp = iocb->ki_filp;
  52        struct qrtr_tun *tun = filp->private_data;
  53        struct sk_buff *skb;
  54        int count;
  55
  56        while (!(skb = skb_dequeue(&tun->queue))) {
  57                if (filp->f_flags & O_NONBLOCK)
  58                        return -EAGAIN;
  59
  60                /* Wait until we get data or the endpoint goes away */
  61                if (wait_event_interruptible(tun->readq,
  62                                             !skb_queue_empty(&tun->queue)))
  63                        return -ERESTARTSYS;
  64        }
  65
  66        count = min_t(size_t, iov_iter_count(to), skb->len);
  67        if (copy_to_iter(skb->data, count, to) != count)
  68                count = -EFAULT;
  69
  70        kfree_skb(skb);
  71
  72        return count;
  73}
  74
  75static ssize_t qrtr_tun_write_iter(struct kiocb *iocb, struct iov_iter *from)
  76{
  77        struct file *filp = iocb->ki_filp;
  78        struct qrtr_tun *tun = filp->private_data;
  79        size_t len = iov_iter_count(from);
  80        ssize_t ret;
  81        void *kbuf;
  82
  83        kbuf = kzalloc(len, GFP_KERNEL);
  84        if (!kbuf)
  85                return -ENOMEM;
  86
  87        if (!copy_from_iter_full(kbuf, len, from)) {
  88                kfree(kbuf);
  89                return -EFAULT;
  90        }
  91
  92        ret = qrtr_endpoint_post(&tun->ep, kbuf, len);
  93
  94        kfree(kbuf);
  95        return ret < 0 ? ret : len;
  96}
  97
  98static __poll_t qrtr_tun_poll(struct file *filp, poll_table *wait)
  99{
 100        struct qrtr_tun *tun = filp->private_data;
 101        __poll_t mask = 0;
 102
 103        poll_wait(filp, &tun->readq, wait);
 104
 105        if (!skb_queue_empty(&tun->queue))
 106                mask |= EPOLLIN | EPOLLRDNORM;
 107
 108        return mask;
 109}
 110
 111static int qrtr_tun_release(struct inode *inode, struct file *filp)
 112{
 113        struct qrtr_tun *tun = filp->private_data;
 114
 115        qrtr_endpoint_unregister(&tun->ep);
 116
 117        /* Discard all SKBs */
 118        skb_queue_purge(&tun->queue);
 119
 120        kfree(tun);
 121
 122        return 0;
 123}
 124
 125static const struct file_operations qrtr_tun_ops = {
 126        .owner = THIS_MODULE,
 127        .open = qrtr_tun_open,
 128        .poll = qrtr_tun_poll,
 129        .read_iter = qrtr_tun_read_iter,
 130        .write_iter = qrtr_tun_write_iter,
 131        .release = qrtr_tun_release,
 132};
 133
 134static struct miscdevice qrtr_tun_miscdev = {
 135        MISC_DYNAMIC_MINOR,
 136        "qrtr-tun",
 137        &qrtr_tun_ops,
 138};
 139
 140static int __init qrtr_tun_init(void)
 141{
 142        int ret;
 143
 144        ret = misc_register(&qrtr_tun_miscdev);
 145        if (ret)
 146                pr_err("failed to register Qualcomm IPC Router tun device\n");
 147
 148        return ret;
 149}
 150
 151static void __exit qrtr_tun_exit(void)
 152{
 153        misc_deregister(&qrtr_tun_miscdev);
 154}
 155
 156module_init(qrtr_tun_init);
 157module_exit(qrtr_tun_exit);
 158
 159MODULE_DESCRIPTION("Qualcomm IPC Router TUN device");
 160MODULE_LICENSE("GPL v2");
 161