3 files changed, 170 insertions, 0 deletions

diff --git a/net/qrtr/Kconfig b/net/qrtr/Kconfig
index 326fd97444f5..1944834d225c 100644
--- a/net/qrtr/Kconfig
+++ b/net/qrtr/Kconfig
@@ -21,4 +21,11 @@ config QRTR_SMD
 	  Say Y here to support SMD based ipcrouter channels.  SMD is the
 	  most common transport for IPC Router.
 
+config QRTR_TUN
+	tristate "TUN device for Qualcomm IPC Router"
+	---help---
+	  Say Y here to expose a character device that allows user space to
+	  implement endpoints of QRTR, for purpose of tunneling data to other
+	  hosts or testing purposes.
+
 endif # QRTR
diff --git a/net/qrtr/Makefile b/net/qrtr/Makefile
index ab09e40f7c74..be012bfd3e52 100644
--- a/net/qrtr/Makefile
+++ b/net/qrtr/Makefile
@@ -2,3 +2,5 @@ obj-$(CONFIG_QRTR) := qrtr.o
 
 obj-$(CONFIG_QRTR_SMD) += qrtr-smd.o
 qrtr-smd-y	:= smd.o
+obj-$(CONFIG_QRTR_TUN) += qrtr-tun.o
+qrtr-tun-y	:= tun.o
diff --git a/net/qrtr/tun.c b/net/qrtr/tun.c
new file mode 100644
index 000000000000..ccff1e544c21
--- /dev/null
+++ b/net/qrtr/tun.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, Linaro Ltd */
+
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/skbuff.h>
+#include <linux/uaccess.h>
+
+#include "qrtr.h"
+
+struct qrtr_tun {
+	struct qrtr_endpoint ep;
+
+	struct sk_buff_head queue;
+	wait_queue_head_t readq;
+};
+
+static int qrtr_tun_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
+{
+	struct qrtr_tun *tun = container_of(ep, struct qrtr_tun, ep);
+
+	skb_queue_tail(&tun->queue, skb);
+
+	/* wake up any blocking processes, waiting for new data */
+	wake_up_interruptible(&tun->readq);
+
+	return 0;
+}
+
+static int qrtr_tun_open(struct inode *inode, struct file *filp)
+{
+	struct qrtr_tun *tun;
+
+	tun = kzalloc(sizeof(*tun), GFP_KERNEL);
+	if (!tun)
+		return -ENOMEM;
+
+	skb_queue_head_init(&tun->queue);
+	init_waitqueue_head(&tun->readq);
+
+	tun->ep.xmit = qrtr_tun_send;
+
+	filp->private_data = tun;
+
+	return qrtr_endpoint_register(&tun->ep, QRTR_EP_NID_AUTO);
+}
+
+static ssize_t qrtr_tun_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *filp = iocb->ki_filp;
+	struct qrtr_tun *tun = filp->private_data;
+	struct sk_buff *skb;
+	int count;
+
+	while (!(skb = skb_dequeue(&tun->queue))) {
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		/* Wait until we get data or the endpoint goes away */
+		if (wait_event_interruptible(tun->readq,
+					     !skb_queue_empty(&tun->queue)))
+			return -ERESTARTSYS;
+	}
+
+	count = min_t(size_t, iov_iter_count(to), skb->len);
+	if (copy_to_iter(skb->data, count, to) != count)
+		count = -EFAULT;
+
+	kfree_skb(skb);
+
+	return count;
+}
+
+static ssize_t qrtr_tun_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *filp = iocb->ki_filp;
+	struct qrtr_tun *tun = filp->private_data;
+	size_t len = iov_iter_count(from);
+	ssize_t ret;
+	void *kbuf;
+
+	kbuf = kzalloc(len, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	if (!copy_from_iter_full(kbuf, len, from))
+		return -EFAULT;
+
+	ret = qrtr_endpoint_post(&tun->ep, kbuf, len);
+
+	return ret < 0 ? ret : len;
+}
+
+static __poll_t qrtr_tun_poll(struct file *filp, poll_table *wait)
+{
+	struct qrtr_tun *tun = filp->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(filp, &tun->readq, wait);
+
+	if (!skb_queue_empty(&tun->queue))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	return mask;
+}
+
+static int qrtr_tun_release(struct inode *inode, struct file *filp)
+{
+	struct qrtr_tun *tun = filp->private_data;
+	struct sk_buff *skb;
+
+	qrtr_endpoint_unregister(&tun->ep);
+
+	/* Discard all SKBs */
+	while (!skb_queue_empty(&tun->queue)) {
+		skb = skb_dequeue(&tun->queue);
+		kfree_skb(skb);
+	}
+
+	kfree(tun);
+
+	return 0;
+}
+
+static const struct file_operations qrtr_tun_ops = {
+	.owner = THIS_MODULE,
+	.open = qrtr_tun_open,
+	.poll = qrtr_tun_poll,
+	.read_iter = qrtr_tun_read_iter,
+	.write_iter = qrtr_tun_write_iter,
+	.release = qrtr_tun_release,
+};
+
+static struct miscdevice qrtr_tun_miscdev = {
+	MISC_DYNAMIC_MINOR,
+	"qrtr-tun",
+	&qrtr_tun_ops,
+};
+
+static int __init qrtr_tun_init(void)
+{
+	int ret;
+
+	ret = misc_register(&qrtr_tun_miscdev);
+	if (ret)
+		pr_err("failed to register Qualcomm IPC Router tun device\n");
+
+	return ret;
+}
+
+static void __exit qrtr_tun_exit(void)
+{
+	misc_deregister(&qrtr_tun_miscdev);
+}
+
+module_init(qrtr_tun_init);
+module_exit(qrtr_tun_exit);
+
+MODULE_DESCRIPTION("Qualcomm IPC Router TUN device");
+MODULE_LICENSE("GPL v2");