1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2013-2018, The Linux Foundation. All rights reserved.
3  *
4  * RMNET configuration engine
5  */
6 
7 #include <net/sock.h>
8 #include <linux/module.h>
9 #include <linux/netlink.h>
10 #include <linux/netdevice.h>
11 #include "rmnet_config.h"
12 #include "rmnet_handlers.h"
13 #include "rmnet_vnd.h"
14 #include "rmnet_private.h"
15 
16 /* Local Definitions and Declarations */
17 
18 static const struct nla_policy rmnet_policy[IFLA_RMNET_MAX + 1] = {
19 	[IFLA_RMNET_MUX_ID]	= { .type = NLA_U16 },
20 	[IFLA_RMNET_FLAGS]	= { .len = sizeof(struct ifla_rmnet_flags) },
21 };
22 
23 static int rmnet_is_real_dev_registered(const struct net_device *real_dev)
24 {
25 	return rcu_access_pointer(real_dev->rx_handler) == rmnet_rx_handler;
26 }
27 
28 /* Needs rtnl lock */
29 static struct rmnet_port*
30 rmnet_get_port_rtnl(const struct net_device *real_dev)
31 {
32 	return rtnl_dereference(real_dev->rx_handler_data);
33 }
34 
35 static int rmnet_unregister_real_device(struct net_device *real_dev)
36 {
37 	struct rmnet_port *port = rmnet_get_port_rtnl(real_dev);
38 
39 	if (port->nr_rmnet_devs)
40 		return -EINVAL;
41 
42 	netdev_rx_handler_unregister(real_dev);
43 
44 	kfree(port);
45 
46 	netdev_dbg(real_dev, "Removed from rmnet\n");
47 	return 0;
48 }
49 
50 static int rmnet_register_real_device(struct net_device *real_dev)
51 {
52 	struct rmnet_port *port;
53 	int rc, entry;
54 
55 	ASSERT_RTNL();
56 
57 	if (rmnet_is_real_dev_registered(real_dev))
58 		return 0;
59 
60 	port = kzalloc(sizeof(*port), GFP_ATOMIC);
61 	if (!port)
62 		return -ENOMEM;
63 
64 	port->dev = real_dev;
65 	rc = netdev_rx_handler_register(real_dev, rmnet_rx_handler, port);
66 	if (rc) {
67 		kfree(port);
68 		return -EBUSY;
69 	}
70 
71 	for (entry = 0; entry < RMNET_MAX_LOGICAL_EP; entry++)
72 		INIT_HLIST_HEAD(&port->muxed_ep[entry]);
73 
74 	netdev_dbg(real_dev, "registered with rmnet\n");
75 	return 0;
76 }
77 
78 static void rmnet_unregister_bridge(struct rmnet_port *port)
79 {
80 	struct net_device *bridge_dev, *real_dev, *rmnet_dev;
81 	struct rmnet_port *real_port;
82 
83 	if (port->rmnet_mode != RMNET_EPMODE_BRIDGE)
84 		return;
85 
86 	rmnet_dev = port->rmnet_dev;
87 	if (!port->nr_rmnet_devs) {
88 		/* bridge device */
89 		real_dev = port->bridge_ep;
90 		bridge_dev = port->dev;
91 
92 		real_port = rmnet_get_port_rtnl(real_dev);
93 		real_port->bridge_ep = NULL;
94 		real_port->rmnet_mode = RMNET_EPMODE_VND;
95 	} else {
96 		/* real device */
97 		bridge_dev = port->bridge_ep;
98 
99 		port->bridge_ep = NULL;
100 		port->rmnet_mode = RMNET_EPMODE_VND;
101 	}
102 
103 	netdev_upper_dev_unlink(bridge_dev, rmnet_dev);
104 	rmnet_unregister_real_device(bridge_dev);
105 }
106 
107 static int rmnet_newlink(struct net *src_net, struct net_device *dev,
108 			 struct nlattr *tb[], struct nlattr *data[],
109 			 struct netlink_ext_ack *extack)
110 {
111 	u32 data_format = RMNET_FLAGS_INGRESS_DEAGGREGATION;
112 	struct net_device *real_dev;
113 	int mode = RMNET_EPMODE_VND;
114 	struct rmnet_endpoint *ep;
115 	struct rmnet_port *port;
116 	int err = 0;
117 	u16 mux_id;
118 
119 	if (!tb[IFLA_LINK]) {
120 		NL_SET_ERR_MSG_MOD(extack, "link not specified");
121 		return -EINVAL;
122 	}
123 
124 	real_dev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
125 	if (!real_dev || !dev)
126 		return -ENODEV;
127 
128 	if (!data[IFLA_RMNET_MUX_ID])
129 		return -EINVAL;
130 
131 	ep = kzalloc(sizeof(*ep), GFP_ATOMIC);
132 	if (!ep)
133 		return -ENOMEM;
134 
135 	mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
136 
137 	err = rmnet_register_real_device(real_dev);
138 	if (err)
139 		goto err0;
140 
141 	port = rmnet_get_port_rtnl(real_dev);
142 	err = rmnet_vnd_newlink(mux_id, dev, port, real_dev, ep);
143 	if (err)
144 		goto err1;
145 
146 	err = netdev_upper_dev_link(real_dev, dev, extack);
147 	if (err < 0)
148 		goto err2;
149 
150 	port->rmnet_mode = mode;
151 	port->rmnet_dev = dev;
152 
153 	hlist_add_head_rcu(&ep->hlnode, &port->muxed_ep[mux_id]);
154 
155 	if (data[IFLA_RMNET_FLAGS]) {
156 		struct ifla_rmnet_flags *flags;
157 
158 		flags = nla_data(data[IFLA_RMNET_FLAGS]);
159 		data_format = flags->flags & flags->mask;
160 	}
161 
162 	netdev_dbg(dev, "data format [0x%08X]\n", data_format);
163 	port->data_format = data_format;
164 
165 	return 0;
166 
167 err2:
168 	unregister_netdevice(dev);
169 	rmnet_vnd_dellink(mux_id, port, ep);
170 err1:
171 	rmnet_unregister_real_device(real_dev);
172 err0:
173 	kfree(ep);
174 	return err;
175 }
176 
177 static void rmnet_dellink(struct net_device *dev, struct list_head *head)
178 {
179 	struct rmnet_priv *priv = netdev_priv(dev);
180 	struct net_device *real_dev, *bridge_dev;
181 	struct rmnet_port *real_port, *bridge_port;
182 	struct rmnet_endpoint *ep;
183 	u8 mux_id = priv->mux_id;
184 
185 	real_dev = priv->real_dev;
186 
187 	if (!rmnet_is_real_dev_registered(real_dev))
188 		return;
189 
190 	real_port = rmnet_get_port_rtnl(real_dev);
191 	bridge_dev = real_port->bridge_ep;
192 	if (bridge_dev) {
193 		bridge_port = rmnet_get_port_rtnl(bridge_dev);
194 		rmnet_unregister_bridge(bridge_port);
195 	}
196 
197 	ep = rmnet_get_endpoint(real_port, mux_id);
198 	if (ep) {
199 		hlist_del_init_rcu(&ep->hlnode);
200 		rmnet_vnd_dellink(mux_id, real_port, ep);
201 		kfree(ep);
202 	}
203 
204 	netdev_upper_dev_unlink(real_dev, dev);
205 	rmnet_unregister_real_device(real_dev);
206 	unregister_netdevice_queue(dev, head);
207 }
208 
209 static void rmnet_force_unassociate_device(struct net_device *real_dev)
210 {
211 	struct hlist_node *tmp_ep;
212 	struct rmnet_endpoint *ep;
213 	struct rmnet_port *port;
214 	unsigned long bkt_ep;
215 	LIST_HEAD(list);
216 
217 	port = rmnet_get_port_rtnl(real_dev);
218 
219 	if (port->nr_rmnet_devs) {
220 		/* real device */
221 		rmnet_unregister_bridge(port);
222 		hash_for_each_safe(port->muxed_ep, bkt_ep, tmp_ep, ep, hlnode) {
223 			unregister_netdevice_queue(ep->egress_dev, &list);
224 			netdev_upper_dev_unlink(real_dev, ep->egress_dev);
225 			rmnet_vnd_dellink(ep->mux_id, port, ep);
226 			hlist_del_init_rcu(&ep->hlnode);
227 			kfree(ep);
228 		}
229 		rmnet_unregister_real_device(real_dev);
230 		unregister_netdevice_many(&list);
231 	} else {
232 		rmnet_unregister_bridge(port);
233 	}
234 }
235 
236 static int rmnet_config_notify_cb(struct notifier_block *nb,
237 				  unsigned long event, void *data)
238 {
239 	struct net_device *real_dev = netdev_notifier_info_to_dev(data);
240 
241 	if (!rmnet_is_real_dev_registered(real_dev))
242 		return NOTIFY_DONE;
243 
244 	switch (event) {
245 	case NETDEV_UNREGISTER:
246 		netdev_dbg(real_dev, "Kernel unregister\n");
247 		rmnet_force_unassociate_device(real_dev);
248 		break;
249 
250 	default:
251 		break;
252 	}
253 
254 	return NOTIFY_DONE;
255 }
256 
257 static struct notifier_block rmnet_dev_notifier __read_mostly = {
258 	.notifier_call = rmnet_config_notify_cb,
259 };
260 
261 static int rmnet_rtnl_validate(struct nlattr *tb[], struct nlattr *data[],
262 			       struct netlink_ext_ack *extack)
263 {
264 	u16 mux_id;
265 
266 	if (!data || !data[IFLA_RMNET_MUX_ID])
267 		return -EINVAL;
268 
269 	mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
270 	if (mux_id > (RMNET_MAX_LOGICAL_EP - 1))
271 		return -ERANGE;
272 
273 	return 0;
274 }
275 
276 static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[],
277 			    struct nlattr *data[],
278 			    struct netlink_ext_ack *extack)
279 {
280 	struct rmnet_priv *priv = netdev_priv(dev);
281 	struct net_device *real_dev;
282 	struct rmnet_endpoint *ep;
283 	struct rmnet_port *port;
284 	u16 mux_id;
285 
286 	if (!dev)
287 		return -ENODEV;
288 
289 	real_dev = priv->real_dev;
290 	if (!rmnet_is_real_dev_registered(real_dev))
291 		return -ENODEV;
292 
293 	port = rmnet_get_port_rtnl(real_dev);
294 
295 	if (data[IFLA_RMNET_MUX_ID]) {
296 		mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
297 		if (rmnet_get_endpoint(port, mux_id)) {
298 			NL_SET_ERR_MSG_MOD(extack, "MUX ID already exists");
299 			return -EINVAL;
300 		}
301 		ep = rmnet_get_endpoint(port, priv->mux_id);
302 		if (!ep)
303 			return -ENODEV;
304 
305 		hlist_del_init_rcu(&ep->hlnode);
306 		hlist_add_head_rcu(&ep->hlnode, &port->muxed_ep[mux_id]);
307 
308 		ep->mux_id = mux_id;
309 		priv->mux_id = mux_id;
310 	}
311 
312 	if (data[IFLA_RMNET_FLAGS]) {
313 		struct ifla_rmnet_flags *flags;
314 
315 		flags = nla_data(data[IFLA_RMNET_FLAGS]);
316 		port->data_format = flags->flags & flags->mask;
317 	}
318 
319 	return 0;
320 }
321 
322 static size_t rmnet_get_size(const struct net_device *dev)
323 {
324 	return
325 		/* IFLA_RMNET_MUX_ID */
326 		nla_total_size(2) +
327 		/* IFLA_RMNET_FLAGS */
328 		nla_total_size(sizeof(struct ifla_rmnet_flags));
329 }
330 
331 static int rmnet_fill_info(struct sk_buff *skb, const struct net_device *dev)
332 {
333 	struct rmnet_priv *priv = netdev_priv(dev);
334 	struct net_device *real_dev;
335 	struct ifla_rmnet_flags f;
336 	struct rmnet_port *port;
337 
338 	real_dev = priv->real_dev;
339 
340 	if (nla_put_u16(skb, IFLA_RMNET_MUX_ID, priv->mux_id))
341 		goto nla_put_failure;
342 
343 	if (rmnet_is_real_dev_registered(real_dev)) {
344 		port = rmnet_get_port_rtnl(real_dev);
345 		f.flags = port->data_format;
346 	} else {
347 		f.flags = 0;
348 	}
349 
350 	f.mask  = ~0;
351 
352 	if (nla_put(skb, IFLA_RMNET_FLAGS, sizeof(f), &f))
353 		goto nla_put_failure;
354 
355 	return 0;
356 
357 nla_put_failure:
358 	return -EMSGSIZE;
359 }
360 
361 struct rtnl_link_ops rmnet_link_ops __read_mostly = {
362 	.kind		= "rmnet",
363 	.maxtype	= __IFLA_RMNET_MAX,
364 	.priv_size	= sizeof(struct rmnet_priv),
365 	.setup		= rmnet_vnd_setup,
366 	.validate	= rmnet_rtnl_validate,
367 	.newlink	= rmnet_newlink,
368 	.dellink	= rmnet_dellink,
369 	.get_size	= rmnet_get_size,
370 	.changelink     = rmnet_changelink,
371 	.policy		= rmnet_policy,
372 	.fill_info	= rmnet_fill_info,
373 };
374 
375 struct rmnet_port *rmnet_get_port_rcu(struct net_device *real_dev)
376 {
377 	if (rmnet_is_real_dev_registered(real_dev))
378 		return rcu_dereference_bh(real_dev->rx_handler_data);
379 	else
380 		return NULL;
381 }
382 
383 struct rmnet_endpoint *rmnet_get_endpoint(struct rmnet_port *port, u8 mux_id)
384 {
385 	struct rmnet_endpoint *ep;
386 
387 	hlist_for_each_entry_rcu(ep, &port->muxed_ep[mux_id], hlnode) {
388 		if (ep->mux_id == mux_id)
389 			return ep;
390 	}
391 
392 	return NULL;
393 }
394 
395 int rmnet_add_bridge(struct net_device *rmnet_dev,
396 		     struct net_device *slave_dev,
397 		     struct netlink_ext_ack *extack)
398 {
399 	struct rmnet_priv *priv = netdev_priv(rmnet_dev);
400 	struct net_device *real_dev = priv->real_dev;
401 	struct rmnet_port *port, *slave_port;
402 	int err;
403 
404 	port = rmnet_get_port_rtnl(real_dev);
405 
406 	/* If there is more than one rmnet dev attached, its probably being
407 	 * used for muxing. Skip the briding in that case
408 	 */
409 	if (port->nr_rmnet_devs > 1)
410 		return -EINVAL;
411 
412 	if (port->rmnet_mode != RMNET_EPMODE_VND)
413 		return -EINVAL;
414 
415 	if (rmnet_is_real_dev_registered(slave_dev))
416 		return -EBUSY;
417 
418 	err = rmnet_register_real_device(slave_dev);
419 	if (err)
420 		return -EBUSY;
421 
422 	err = netdev_master_upper_dev_link(slave_dev, rmnet_dev, NULL, NULL,
423 					   extack);
424 	if (err) {
425 		rmnet_unregister_real_device(slave_dev);
426 		return err;
427 	}
428 
429 	slave_port = rmnet_get_port_rtnl(slave_dev);
430 	slave_port->rmnet_mode = RMNET_EPMODE_BRIDGE;
431 	slave_port->bridge_ep = real_dev;
432 	slave_port->rmnet_dev = rmnet_dev;
433 
434 	port->rmnet_mode = RMNET_EPMODE_BRIDGE;
435 	port->bridge_ep = slave_dev;
436 
437 	netdev_dbg(slave_dev, "registered with rmnet as slave\n");
438 	return 0;
439 }
440 
441 int rmnet_del_bridge(struct net_device *rmnet_dev,
442 		     struct net_device *slave_dev)
443 {
444 	struct rmnet_port *port = rmnet_get_port_rtnl(slave_dev);
445 
446 	rmnet_unregister_bridge(port);
447 
448 	netdev_dbg(slave_dev, "removed from rmnet as slave\n");
449 	return 0;
450 }
451 
452 /* Startup/Shutdown */
453 
454 static int __init rmnet_init(void)
455 {
456 	int rc;
457 
458 	rc = register_netdevice_notifier(&rmnet_dev_notifier);
459 	if (rc != 0)
460 		return rc;
461 
462 	rc = rtnl_link_register(&rmnet_link_ops);
463 	if (rc != 0) {
464 		unregister_netdevice_notifier(&rmnet_dev_notifier);
465 		return rc;
466 	}
467 	return rc;
468 }
469 
470 static void __exit rmnet_exit(void)
471 {
472 	rtnl_link_unregister(&rmnet_link_ops);
473 	unregister_netdevice_notifier(&rmnet_dev_notifier);
474 }
475 
476 module_init(rmnet_init)
477 module_exit(rmnet_exit)
478 MODULE_LICENSE("GPL v2");
479