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         int ret;
  35
  36         tun = kzalloc(sizeof(*tun), GFP_KERNEL);
  37         if (!tun)
  38                 return -ENOMEM;
  39
  40         skb_queue_head_init(&tun->queue);
  41         init_waitqueue_head(&tun->readq);
  42
  43         tun->ep.xmit = qrtr_tun_send;
  44
  45         filp->private_data = tun;
  46
  47         ret = qrtr_endpoint_register(&tun->ep, QRTR_EP_NID_AUTO);
  48         if (ret)
  49                 goto out;
  50
  51         return 0;
  52
  53 out:
  54         filp->private_data = NULL;
  55         kfree(tun);
  56         return ret;
  57 }
  58
  59 static ssize_t qrtr_tun_read_iter(struct kiocb *iocb, struct iov_iter *to)
  60 {
  61         struct file *filp = iocb->ki_filp;
  62         struct qrtr_tun *tun = filp->private_data;
  63         struct sk_buff *skb;
  64         int count;
  65
  66         while (!(skb = skb_dequeue(&tun->queue))) {
  67                 if (filp->f_flags & O_NONBLOCK)
  68                         return -EAGAIN;
  69
  70                 /* Wait until we get data or the endpoint goes away */
  71                 if (wait_event_interruptible(tun->readq,
  72                                              !skb_queue_empty(&tun->queue)))
  73                         return -ERESTARTSYS;
  74         }
  75
  76         count = min_t(size_t, iov_iter_count(to), skb->len);
  77         if (copy_to_iter(skb->data, count, to) != count)
  78                 count = -EFAULT;
  79
  80         kfree_skb(skb);
  81
  82         return count;
  83 }
  84
  85 static ssize_t qrtr_tun_write_iter(struct kiocb *iocb, struct iov_iter *from)
  86 {
  87         struct file *filp = iocb->ki_filp;
  88         struct qrtr_tun *tun = filp->private_data;
  89         size_t len = iov_iter_count(from);
  90         ssize_t ret;
  91         void *kbuf;
  92
  93         if (!len)
  94                 return -EINVAL;
  95
  96         if (len > KMALLOC_MAX_SIZE)
  97                 return -ENOMEM;
  98
  99         kbuf = kzalloc(len, GFP_KERNEL);
 100         if (!kbuf)
 101                 return -ENOMEM;
 102
 103         if (!copy_from_iter_full(kbuf, len, from)) {
 104                 kfree(kbuf);
 105                 return -EFAULT;
 106         }
 107
 108         ret = qrtr_endpoint_post(&tun->ep, kbuf, len);
 109
 110         kfree(kbuf);
 111         return ret < 0 ? ret : len;
 112 }
 113
 114 static __poll_t qrtr_tun_poll(struct file *filp, poll_table *wait)
 115 {
 116         struct qrtr_tun *tun = filp->private_data;
 117         __poll_t mask = 0;
 118
 119         poll_wait(filp, &tun->readq, wait);
 120
 121         if (!skb_queue_empty(&tun->queue))
 122                 mask |= EPOLLIN | EPOLLRDNORM;
 123
 124         return mask;
 125 }
 126
 127 static int qrtr_tun_release(struct inode *inode, struct file *filp)
 128 {
 129         struct qrtr_tun *tun = filp->private_data;
 130
 131         qrtr_endpoint_unregister(&tun->ep);
 132
 133         /* Discard all SKBs */
 134         skb_queue_purge(&tun->queue);
 135
 136         kfree(tun);
 137
 138         return 0;
 139 }
 140
 141 static const struct file_operations qrtr_tun_ops = {
 142         .owner = THIS_MODULE,
 143         .open = qrtr_tun_open,
 144         .poll = qrtr_tun_poll,
 145         .read_iter = qrtr_tun_read_iter,
 146         .write_iter = qrtr_tun_write_iter,
 147         .release = qrtr_tun_release,
 148 };
 149
 150 static struct miscdevice qrtr_tun_miscdev = {
 151         MISC_DYNAMIC_MINOR,
 152         "qrtr-tun",
 153         &qrtr_tun_ops,
 154 };
 155
 156 static int __init qrtr_tun_init(void)
 157 {
 158         int ret;
 159
 160         ret = misc_register(&qrtr_tun_miscdev);
 161         if (ret)
 162                 pr_err("failed to register Qualcomm IPC Router tun device\n");
 163
 164         return ret;
 165 }
 166
 167 static void __exit qrtr_tun_exit(void)
 168 {
 169         misc_deregister(&qrtr_tun_miscdev);
 170 }
 171
 172 module_init(qrtr_tun_init);
 173 module_exit(qrtr_tun_exit);
 174
 175 MODULE_DESCRIPTION("Qualcomm IPC Router TUN device");
 176 MODULE_LICENSE("GPL v2");