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         if (!len)
  84                 return -EINVAL;
  85
  86         if (len > KMALLOC_MAX_SIZE)
  87                 return -ENOMEM;
  88
  89         kbuf = kzalloc(len, GFP_KERNEL);
  90         if (!kbuf)
  91                 return -ENOMEM;
  92
  93         if (!copy_from_iter_full(kbuf, len, from)) {
  94                 kfree(kbuf);
  95                 return -EFAULT;
  96         }
  97
  98         ret = qrtr_endpoint_post(&tun->ep, kbuf, len);
  99
 100         kfree(kbuf);
 101         return ret < 0 ? ret : len;
 102 }
 103
 104 static __poll_t qrtr_tun_poll(struct file *filp, poll_table *wait)
 105 {
 106         struct qrtr_tun *tun = filp->private_data;
 107         __poll_t mask = 0;
 108
 109         poll_wait(filp, &tun->readq, wait);
 110
 111         if (!skb_queue_empty(&tun->queue))
 112                 mask |= EPOLLIN | EPOLLRDNORM;
 113
 114         return mask;
 115 }
 116
 117 static int qrtr_tun_release(struct inode *inode, struct file *filp)
 118 {
 119         struct qrtr_tun *tun = filp->private_data;
 120
 121         qrtr_endpoint_unregister(&tun->ep);
 122
 123         /* Discard all SKBs */
 124         skb_queue_purge(&tun->queue);
 125
 126         kfree(tun);
 127
 128         return 0;
 129 }
 130
 131 static const struct file_operations qrtr_tun_ops = {
 132         .owner = THIS_MODULE,
 133         .open = qrtr_tun_open,
 134         .poll = qrtr_tun_poll,
 135         .read_iter = qrtr_tun_read_iter,
 136         .write_iter = qrtr_tun_write_iter,
 137         .release = qrtr_tun_release,
 138 };
 139
 140 static struct miscdevice qrtr_tun_miscdev = {
 141         MISC_DYNAMIC_MINOR,
 142         "qrtr-tun",
 143         &qrtr_tun_ops,
 144 };
 145
 146 static int __init qrtr_tun_init(void)
 147 {
 148         int ret;
 149
 150         ret = misc_register(&qrtr_tun_miscdev);
 151         if (ret)
 152                 pr_err("failed to register Qualcomm IPC Router tun device\n");
 153
 154         return ret;
 155 }
 156
 157 static void __exit qrtr_tun_exit(void)
 158 {
 159         misc_deregister(&qrtr_tun_miscdev);
 160 }
 161
 162 module_init(qrtr_tun_init);
 163 module_exit(qrtr_tun_exit);
 164
 165 MODULE_DESCRIPTION("Qualcomm IPC Router TUN device");
 166 MODULE_LICENSE("GPL v2");