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"); 167