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
  12 struct qrtr_tun {
  13         struct qrtr_endpoint ep;
  14
  15         struct sk_buff_head queue;
  16         wait_queue_head_t readq;
  17 };
  18
  19 static 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
  31 static 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
  49 static 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
  75 static 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
  98 static __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
 111 static 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
 125 static 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
 134 static struct miscdevice qrtr_tun_miscdev = {
 135         MISC_DYNAMIC_MINOR,
 136         "qrtr-tun",
 137         &qrtr_tun_ops,
 138 };
 139
 140 static 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
 151 static void __exit qrtr_tun_exit(void)
 152 {
 153         misc_deregister(&qrtr_tun_miscdev);
 154 }
 155
 156 module_init(qrtr_tun_init);
 157 module_exit(qrtr_tun_exit);
 158
 159 MODULE_DESCRIPTION("Qualcomm IPC Router TUN device");
 160 MODULE_LICENSE("GPL v2");