xref: /linux/drivers/net/tun.c (revision 8faabc041a001140564f718dabe37753e88b37fa)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  TUN - Universal TUN/TAP device driver.
4  *  Copyright (C) 1999-2002 Maxim Krasnyansky <maxk@qualcomm.com>
5  *
6  *  $Id: tun.c,v 1.15 2002/03/01 02:44:24 maxk Exp $
7  */
8 
9 /*
10  *  Changes:
11  *
12  *  Mike Kershaw <dragorn@kismetwireless.net> 2005/08/14
13  *    Add TUNSETLINK ioctl to set the link encapsulation
14  *
15  *  Mark Smith <markzzzsmith@yahoo.com.au>
16  *    Use eth_random_addr() for tap MAC address.
17  *
18  *  Harald Roelle <harald.roelle@ifi.lmu.de>  2004/04/20
19  *    Fixes in packet dropping, queue length setting and queue wakeup.
20  *    Increased default tx queue length.
21  *    Added ethtool API.
22  *    Minor cleanups
23  *
24  *  Daniel Podlejski <underley@underley.eu.org>
25  *    Modifications for 2.3.99-pre5 kernel.
26  */
27 
28 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
29 
30 #define DRV_NAME	"tun"
31 #define DRV_VERSION	"1.6"
32 #define DRV_DESCRIPTION	"Universal TUN/TAP device driver"
33 #define DRV_COPYRIGHT	"(C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>"
34 
35 #include <linux/module.h>
36 #include <linux/errno.h>
37 #include <linux/kernel.h>
38 #include <linux/sched/signal.h>
39 #include <linux/major.h>
40 #include <linux/slab.h>
41 #include <linux/poll.h>
42 #include <linux/fcntl.h>
43 #include <linux/init.h>
44 #include <linux/skbuff.h>
45 #include <linux/netdevice.h>
46 #include <linux/etherdevice.h>
47 #include <linux/miscdevice.h>
48 #include <linux/ethtool.h>
49 #include <linux/rtnetlink.h>
50 #include <linux/compat.h>
51 #include <linux/if.h>
52 #include <linux/if_arp.h>
53 #include <linux/if_ether.h>
54 #include <linux/if_tun.h>
55 #include <linux/if_vlan.h>
56 #include <linux/crc32.h>
57 #include <linux/math.h>
58 #include <linux/nsproxy.h>
59 #include <linux/virtio_net.h>
60 #include <linux/rcupdate.h>
61 #include <net/net_namespace.h>
62 #include <net/netns/generic.h>
63 #include <net/rtnetlink.h>
64 #include <net/sock.h>
65 #include <net/xdp.h>
66 #include <net/ip_tunnels.h>
67 #include <linux/seq_file.h>
68 #include <linux/uio.h>
69 #include <linux/skb_array.h>
70 #include <linux/bpf.h>
71 #include <linux/bpf_trace.h>
72 #include <linux/mutex.h>
73 #include <linux/ieee802154.h>
74 #include <uapi/linux/if_ltalk.h>
75 #include <uapi/linux/if_fddi.h>
76 #include <uapi/linux/if_hippi.h>
77 #include <uapi/linux/if_fc.h>
78 #include <net/ax25.h>
79 #include <net/rose.h>
80 #include <net/6lowpan.h>
81 #include <net/rps.h>
82 
83 #include <linux/uaccess.h>
84 #include <linux/proc_fs.h>
85 
86 static void tun_default_link_ksettings(struct net_device *dev,
87 				       struct ethtool_link_ksettings *cmd);
88 
89 #define TUN_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
90 
91 /* TUN device flags */
92 
93 /* IFF_ATTACH_QUEUE is never stored in device flags,
94  * overload it to mean fasync when stored there.
95  */
96 #define TUN_FASYNC	IFF_ATTACH_QUEUE
97 /* High bits in flags field are unused. */
98 #define TUN_VNET_LE     0x80000000
99 #define TUN_VNET_BE     0x40000000
100 
101 #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
102 		      IFF_MULTI_QUEUE | IFF_NAPI | IFF_NAPI_FRAGS)
103 
104 #define GOODCOPY_LEN 128
105 
106 #define FLT_EXACT_COUNT 8
107 struct tap_filter {
108 	unsigned int    count;    /* Number of addrs. Zero means disabled */
109 	u32             mask[2];  /* Mask of the hashed addrs */
110 	unsigned char	addr[FLT_EXACT_COUNT][ETH_ALEN];
111 };
112 
113 /* MAX_TAP_QUEUES 256 is chosen to allow rx/tx queues to be equal
114  * to max number of VCPUs in guest. */
115 #define MAX_TAP_QUEUES 256
116 #define MAX_TAP_FLOWS  4096
117 
118 #define TUN_FLOW_EXPIRE (3 * HZ)
119 
120 /* A tun_file connects an open character device to a tuntap netdevice. It
121  * also contains all socket related structures (except sock_fprog and tap_filter)
122  * to serve as one transmit queue for tuntap device. The sock_fprog and
123  * tap_filter were kept in tun_struct since they were used for filtering for the
124  * netdevice not for a specific queue (at least I didn't see the requirement for
125  * this).
126  *
127  * RCU usage:
128  * The tun_file and tun_struct are loosely coupled, the pointer from one to the
129  * other can only be read while rcu_read_lock or rtnl_lock is held.
130  */
131 struct tun_file {
132 	struct sock sk;
133 	struct socket socket;
134 	struct tun_struct __rcu *tun;
135 	struct fasync_struct *fasync;
136 	/* only used for fasnyc */
137 	unsigned int flags;
138 	union {
139 		u16 queue_index;
140 		unsigned int ifindex;
141 	};
142 	struct napi_struct napi;
143 	bool napi_enabled;
144 	bool napi_frags_enabled;
145 	struct mutex napi_mutex;	/* Protects access to the above napi */
146 	struct list_head next;
147 	struct tun_struct *detached;
148 	struct ptr_ring tx_ring;
149 	struct xdp_rxq_info xdp_rxq;
150 };
151 
152 struct tun_page {
153 	struct page *page;
154 	int count;
155 };
156 
157 struct tun_flow_entry {
158 	struct hlist_node hash_link;
159 	struct rcu_head rcu;
160 	struct tun_struct *tun;
161 
162 	u32 rxhash;
163 	u32 rps_rxhash;
164 	int queue_index;
165 	unsigned long updated ____cacheline_aligned_in_smp;
166 };
167 
168 #define TUN_NUM_FLOW_ENTRIES 1024
169 #define TUN_MASK_FLOW_ENTRIES (TUN_NUM_FLOW_ENTRIES - 1)
170 
171 struct tun_prog {
172 	struct rcu_head rcu;
173 	struct bpf_prog *prog;
174 };
175 
176 /* Since the socket were moved to tun_file, to preserve the behavior of persist
177  * device, socket filter, sndbuf and vnet header size were restore when the
178  * file were attached to a persist device.
179  */
180 struct tun_struct {
181 	struct tun_file __rcu	*tfiles[MAX_TAP_QUEUES];
182 	unsigned int            numqueues;
183 	unsigned int 		flags;
184 	kuid_t			owner;
185 	kgid_t			group;
186 
187 	struct net_device	*dev;
188 	netdev_features_t	set_features;
189 #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
190 			  NETIF_F_TSO6 | NETIF_F_GSO_UDP_L4)
191 
192 	int			align;
193 	int			vnet_hdr_sz;
194 	int			sndbuf;
195 	struct tap_filter	txflt;
196 	struct sock_fprog	fprog;
197 	/* protected by rtnl lock */
198 	bool			filter_attached;
199 	u32			msg_enable;
200 	spinlock_t lock;
201 	struct hlist_head flows[TUN_NUM_FLOW_ENTRIES];
202 	struct timer_list flow_gc_timer;
203 	unsigned long ageing_time;
204 	unsigned int numdisabled;
205 	struct list_head disabled;
206 	void *security;
207 	u32 flow_count;
208 	u32 rx_batched;
209 	atomic_long_t rx_frame_errors;
210 	struct bpf_prog __rcu *xdp_prog;
211 	struct tun_prog __rcu *steering_prog;
212 	struct tun_prog __rcu *filter_prog;
213 	struct ethtool_link_ksettings link_ksettings;
214 	/* init args */
215 	struct file *file;
216 	struct ifreq *ifr;
217 };
218 
219 struct veth {
220 	__be16 h_vlan_proto;
221 	__be16 h_vlan_TCI;
222 };
223 
224 static void tun_flow_init(struct tun_struct *tun);
225 static void tun_flow_uninit(struct tun_struct *tun);
226 
tun_napi_receive(struct napi_struct * napi,int budget)227 static int tun_napi_receive(struct napi_struct *napi, int budget)
228 {
229 	struct tun_file *tfile = container_of(napi, struct tun_file, napi);
230 	struct sk_buff_head *queue = &tfile->sk.sk_write_queue;
231 	struct sk_buff_head process_queue;
232 	struct sk_buff *skb;
233 	int received = 0;
234 
235 	__skb_queue_head_init(&process_queue);
236 
237 	spin_lock(&queue->lock);
238 	skb_queue_splice_tail_init(queue, &process_queue);
239 	spin_unlock(&queue->lock);
240 
241 	while (received < budget && (skb = __skb_dequeue(&process_queue))) {
242 		napi_gro_receive(napi, skb);
243 		++received;
244 	}
245 
246 	if (!skb_queue_empty(&process_queue)) {
247 		spin_lock(&queue->lock);
248 		skb_queue_splice(&process_queue, queue);
249 		spin_unlock(&queue->lock);
250 	}
251 
252 	return received;
253 }
254 
tun_napi_poll(struct napi_struct * napi,int budget)255 static int tun_napi_poll(struct napi_struct *napi, int budget)
256 {
257 	unsigned int received;
258 
259 	received = tun_napi_receive(napi, budget);
260 
261 	if (received < budget)
262 		napi_complete_done(napi, received);
263 
264 	return received;
265 }
266 
tun_napi_init(struct tun_struct * tun,struct tun_file * tfile,bool napi_en,bool napi_frags)267 static void tun_napi_init(struct tun_struct *tun, struct tun_file *tfile,
268 			  bool napi_en, bool napi_frags)
269 {
270 	tfile->napi_enabled = napi_en;
271 	tfile->napi_frags_enabled = napi_en && napi_frags;
272 	if (napi_en) {
273 		netif_napi_add_tx(tun->dev, &tfile->napi, tun_napi_poll);
274 		napi_enable(&tfile->napi);
275 	}
276 }
277 
tun_napi_enable(struct tun_file * tfile)278 static void tun_napi_enable(struct tun_file *tfile)
279 {
280 	if (tfile->napi_enabled)
281 		napi_enable(&tfile->napi);
282 }
283 
tun_napi_disable(struct tun_file * tfile)284 static void tun_napi_disable(struct tun_file *tfile)
285 {
286 	if (tfile->napi_enabled)
287 		napi_disable(&tfile->napi);
288 }
289 
tun_napi_del(struct tun_file * tfile)290 static void tun_napi_del(struct tun_file *tfile)
291 {
292 	if (tfile->napi_enabled)
293 		netif_napi_del(&tfile->napi);
294 }
295 
tun_napi_frags_enabled(const struct tun_file * tfile)296 static bool tun_napi_frags_enabled(const struct tun_file *tfile)
297 {
298 	return tfile->napi_frags_enabled;
299 }
300 
301 #ifdef CONFIG_TUN_VNET_CROSS_LE
tun_legacy_is_little_endian(struct tun_struct * tun)302 static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
303 {
304 	return tun->flags & TUN_VNET_BE ? false :
305 		virtio_legacy_is_little_endian();
306 }
307 
tun_get_vnet_be(struct tun_struct * tun,int __user * argp)308 static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
309 {
310 	int be = !!(tun->flags & TUN_VNET_BE);
311 
312 	if (put_user(be, argp))
313 		return -EFAULT;
314 
315 	return 0;
316 }
317 
tun_set_vnet_be(struct tun_struct * tun,int __user * argp)318 static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
319 {
320 	int be;
321 
322 	if (get_user(be, argp))
323 		return -EFAULT;
324 
325 	if (be)
326 		tun->flags |= TUN_VNET_BE;
327 	else
328 		tun->flags &= ~TUN_VNET_BE;
329 
330 	return 0;
331 }
332 #else
tun_legacy_is_little_endian(struct tun_struct * tun)333 static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
334 {
335 	return virtio_legacy_is_little_endian();
336 }
337 
tun_get_vnet_be(struct tun_struct * tun,int __user * argp)338 static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
339 {
340 	return -EINVAL;
341 }
342 
tun_set_vnet_be(struct tun_struct * tun,int __user * argp)343 static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
344 {
345 	return -EINVAL;
346 }
347 #endif /* CONFIG_TUN_VNET_CROSS_LE */
348 
tun_is_little_endian(struct tun_struct * tun)349 static inline bool tun_is_little_endian(struct tun_struct *tun)
350 {
351 	return tun->flags & TUN_VNET_LE ||
352 		tun_legacy_is_little_endian(tun);
353 }
354 
tun16_to_cpu(struct tun_struct * tun,__virtio16 val)355 static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
356 {
357 	return __virtio16_to_cpu(tun_is_little_endian(tun), val);
358 }
359 
cpu_to_tun16(struct tun_struct * tun,u16 val)360 static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 val)
361 {
362 	return __cpu_to_virtio16(tun_is_little_endian(tun), val);
363 }
364 
tun_hashfn(u32 rxhash)365 static inline u32 tun_hashfn(u32 rxhash)
366 {
367 	return rxhash & TUN_MASK_FLOW_ENTRIES;
368 }
369 
tun_flow_find(struct hlist_head * head,u32 rxhash)370 static struct tun_flow_entry *tun_flow_find(struct hlist_head *head, u32 rxhash)
371 {
372 	struct tun_flow_entry *e;
373 
374 	hlist_for_each_entry_rcu(e, head, hash_link) {
375 		if (e->rxhash == rxhash)
376 			return e;
377 	}
378 	return NULL;
379 }
380 
tun_flow_create(struct tun_struct * tun,struct hlist_head * head,u32 rxhash,u16 queue_index)381 static struct tun_flow_entry *tun_flow_create(struct tun_struct *tun,
382 					      struct hlist_head *head,
383 					      u32 rxhash, u16 queue_index)
384 {
385 	struct tun_flow_entry *e = kmalloc(sizeof(*e), GFP_ATOMIC);
386 
387 	if (e) {
388 		netif_info(tun, tx_queued, tun->dev,
389 			   "create flow: hash %u index %u\n",
390 			   rxhash, queue_index);
391 		e->updated = jiffies;
392 		e->rxhash = rxhash;
393 		e->rps_rxhash = 0;
394 		e->queue_index = queue_index;
395 		e->tun = tun;
396 		hlist_add_head_rcu(&e->hash_link, head);
397 		++tun->flow_count;
398 	}
399 	return e;
400 }
401 
tun_flow_delete(struct tun_struct * tun,struct tun_flow_entry * e)402 static void tun_flow_delete(struct tun_struct *tun, struct tun_flow_entry *e)
403 {
404 	netif_info(tun, tx_queued, tun->dev, "delete flow: hash %u index %u\n",
405 		   e->rxhash, e->queue_index);
406 	hlist_del_rcu(&e->hash_link);
407 	kfree_rcu(e, rcu);
408 	--tun->flow_count;
409 }
410 
tun_flow_flush(struct tun_struct * tun)411 static void tun_flow_flush(struct tun_struct *tun)
412 {
413 	int i;
414 
415 	spin_lock_bh(&tun->lock);
416 	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
417 		struct tun_flow_entry *e;
418 		struct hlist_node *n;
419 
420 		hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link)
421 			tun_flow_delete(tun, e);
422 	}
423 	spin_unlock_bh(&tun->lock);
424 }
425 
tun_flow_delete_by_queue(struct tun_struct * tun,u16 queue_index)426 static void tun_flow_delete_by_queue(struct tun_struct *tun, u16 queue_index)
427 {
428 	int i;
429 
430 	spin_lock_bh(&tun->lock);
431 	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
432 		struct tun_flow_entry *e;
433 		struct hlist_node *n;
434 
435 		hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
436 			if (e->queue_index == queue_index)
437 				tun_flow_delete(tun, e);
438 		}
439 	}
440 	spin_unlock_bh(&tun->lock);
441 }
442 
tun_flow_cleanup(struct timer_list * t)443 static void tun_flow_cleanup(struct timer_list *t)
444 {
445 	struct tun_struct *tun = from_timer(tun, t, flow_gc_timer);
446 	unsigned long delay = tun->ageing_time;
447 	unsigned long next_timer = jiffies + delay;
448 	unsigned long count = 0;
449 	int i;
450 
451 	spin_lock(&tun->lock);
452 	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) {
453 		struct tun_flow_entry *e;
454 		struct hlist_node *n;
455 
456 		hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) {
457 			unsigned long this_timer;
458 
459 			this_timer = e->updated + delay;
460 			if (time_before_eq(this_timer, jiffies)) {
461 				tun_flow_delete(tun, e);
462 				continue;
463 			}
464 			count++;
465 			if (time_before(this_timer, next_timer))
466 				next_timer = this_timer;
467 		}
468 	}
469 
470 	if (count)
471 		mod_timer(&tun->flow_gc_timer, round_jiffies_up(next_timer));
472 	spin_unlock(&tun->lock);
473 }
474 
tun_flow_update(struct tun_struct * tun,u32 rxhash,struct tun_file * tfile)475 static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
476 			    struct tun_file *tfile)
477 {
478 	struct hlist_head *head;
479 	struct tun_flow_entry *e;
480 	unsigned long delay = tun->ageing_time;
481 	u16 queue_index = tfile->queue_index;
482 
483 	head = &tun->flows[tun_hashfn(rxhash)];
484 
485 	rcu_read_lock();
486 
487 	e = tun_flow_find(head, rxhash);
488 	if (likely(e)) {
489 		/* TODO: keep queueing to old queue until it's empty? */
490 		if (READ_ONCE(e->queue_index) != queue_index)
491 			WRITE_ONCE(e->queue_index, queue_index);
492 		if (e->updated != jiffies)
493 			e->updated = jiffies;
494 		sock_rps_record_flow_hash(e->rps_rxhash);
495 	} else {
496 		spin_lock_bh(&tun->lock);
497 		if (!tun_flow_find(head, rxhash) &&
498 		    tun->flow_count < MAX_TAP_FLOWS)
499 			tun_flow_create(tun, head, rxhash, queue_index);
500 
501 		if (!timer_pending(&tun->flow_gc_timer))
502 			mod_timer(&tun->flow_gc_timer,
503 				  round_jiffies_up(jiffies + delay));
504 		spin_unlock_bh(&tun->lock);
505 	}
506 
507 	rcu_read_unlock();
508 }
509 
510 /* Save the hash received in the stack receive path and update the
511  * flow_hash table accordingly.
512  */
tun_flow_save_rps_rxhash(struct tun_flow_entry * e,u32 hash)513 static inline void tun_flow_save_rps_rxhash(struct tun_flow_entry *e, u32 hash)
514 {
515 	if (unlikely(e->rps_rxhash != hash))
516 		e->rps_rxhash = hash;
517 }
518 
519 /* We try to identify a flow through its rxhash. The reason that
520  * we do not check rxq no. is because some cards(e.g 82599), chooses
521  * the rxq based on the txq where the last packet of the flow comes. As
522  * the userspace application move between processors, we may get a
523  * different rxq no. here.
524  */
tun_automq_select_queue(struct tun_struct * tun,struct sk_buff * skb)525 static u16 tun_automq_select_queue(struct tun_struct *tun, struct sk_buff *skb)
526 {
527 	struct tun_flow_entry *e;
528 	u32 txq, numqueues;
529 
530 	numqueues = READ_ONCE(tun->numqueues);
531 
532 	txq = __skb_get_hash_symmetric(skb);
533 	e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq);
534 	if (e) {
535 		tun_flow_save_rps_rxhash(e, txq);
536 		txq = e->queue_index;
537 	} else {
538 		txq = reciprocal_scale(txq, numqueues);
539 	}
540 
541 	return txq;
542 }
543 
tun_ebpf_select_queue(struct tun_struct * tun,struct sk_buff * skb)544 static u16 tun_ebpf_select_queue(struct tun_struct *tun, struct sk_buff *skb)
545 {
546 	struct tun_prog *prog;
547 	u32 numqueues;
548 	u16 ret = 0;
549 
550 	numqueues = READ_ONCE(tun->numqueues);
551 	if (!numqueues)
552 		return 0;
553 
554 	prog = rcu_dereference(tun->steering_prog);
555 	if (prog)
556 		ret = bpf_prog_run_clear_cb(prog->prog, skb);
557 
558 	return ret % numqueues;
559 }
560 
tun_select_queue(struct net_device * dev,struct sk_buff * skb,struct net_device * sb_dev)561 static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,
562 			    struct net_device *sb_dev)
563 {
564 	struct tun_struct *tun = netdev_priv(dev);
565 	u16 ret;
566 
567 	rcu_read_lock();
568 	if (rcu_dereference(tun->steering_prog))
569 		ret = tun_ebpf_select_queue(tun, skb);
570 	else
571 		ret = tun_automq_select_queue(tun, skb);
572 	rcu_read_unlock();
573 
574 	return ret;
575 }
576 
tun_not_capable(struct tun_struct * tun)577 static inline bool tun_not_capable(struct tun_struct *tun)
578 {
579 	const struct cred *cred = current_cred();
580 	struct net *net = dev_net(tun->dev);
581 
582 	return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
583 		  (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
584 		!ns_capable(net->user_ns, CAP_NET_ADMIN);
585 }
586 
tun_set_real_num_queues(struct tun_struct * tun)587 static void tun_set_real_num_queues(struct tun_struct *tun)
588 {
589 	netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
590 	netif_set_real_num_rx_queues(tun->dev, tun->numqueues);
591 }
592 
tun_disable_queue(struct tun_struct * tun,struct tun_file * tfile)593 static void tun_disable_queue(struct tun_struct *tun, struct tun_file *tfile)
594 {
595 	tfile->detached = tun;
596 	list_add_tail(&tfile->next, &tun->disabled);
597 	++tun->numdisabled;
598 }
599 
tun_enable_queue(struct tun_file * tfile)600 static struct tun_struct *tun_enable_queue(struct tun_file *tfile)
601 {
602 	struct tun_struct *tun = tfile->detached;
603 
604 	tfile->detached = NULL;
605 	list_del_init(&tfile->next);
606 	--tun->numdisabled;
607 	return tun;
608 }
609 
tun_ptr_free(void * ptr)610 void tun_ptr_free(void *ptr)
611 {
612 	if (!ptr)
613 		return;
614 	if (tun_is_xdp_frame(ptr)) {
615 		struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
616 
617 		xdp_return_frame(xdpf);
618 	} else {
619 		__skb_array_destroy_skb(ptr);
620 	}
621 }
622 EXPORT_SYMBOL_GPL(tun_ptr_free);
623 
tun_queue_purge(struct tun_file * tfile)624 static void tun_queue_purge(struct tun_file *tfile)
625 {
626 	void *ptr;
627 
628 	while ((ptr = ptr_ring_consume(&tfile->tx_ring)) != NULL)
629 		tun_ptr_free(ptr);
630 
631 	skb_queue_purge(&tfile->sk.sk_write_queue);
632 	skb_queue_purge(&tfile->sk.sk_error_queue);
633 }
634 
__tun_detach(struct tun_file * tfile,bool clean)635 static void __tun_detach(struct tun_file *tfile, bool clean)
636 {
637 	struct tun_file *ntfile;
638 	struct tun_struct *tun;
639 
640 	tun = rtnl_dereference(tfile->tun);
641 
642 	if (tun && clean) {
643 		if (!tfile->detached)
644 			tun_napi_disable(tfile);
645 		tun_napi_del(tfile);
646 	}
647 
648 	if (tun && !tfile->detached) {
649 		u16 index = tfile->queue_index;
650 		BUG_ON(index >= tun->numqueues);
651 
652 		rcu_assign_pointer(tun->tfiles[index],
653 				   tun->tfiles[tun->numqueues - 1]);
654 		ntfile = rtnl_dereference(tun->tfiles[index]);
655 		ntfile->queue_index = index;
656 		ntfile->xdp_rxq.queue_index = index;
657 		rcu_assign_pointer(tun->tfiles[tun->numqueues - 1],
658 				   NULL);
659 
660 		--tun->numqueues;
661 		if (clean) {
662 			RCU_INIT_POINTER(tfile->tun, NULL);
663 			sock_put(&tfile->sk);
664 		} else {
665 			tun_disable_queue(tun, tfile);
666 			tun_napi_disable(tfile);
667 		}
668 
669 		synchronize_net();
670 		tun_flow_delete_by_queue(tun, tun->numqueues + 1);
671 		/* Drop read queue */
672 		tun_queue_purge(tfile);
673 		tun_set_real_num_queues(tun);
674 	} else if (tfile->detached && clean) {
675 		tun = tun_enable_queue(tfile);
676 		sock_put(&tfile->sk);
677 	}
678 
679 	if (clean) {
680 		if (tun && tun->numqueues == 0 && tun->numdisabled == 0) {
681 			netif_carrier_off(tun->dev);
682 
683 			if (!(tun->flags & IFF_PERSIST) &&
684 			    tun->dev->reg_state == NETREG_REGISTERED)
685 				unregister_netdevice(tun->dev);
686 		}
687 		if (tun)
688 			xdp_rxq_info_unreg(&tfile->xdp_rxq);
689 		ptr_ring_cleanup(&tfile->tx_ring, tun_ptr_free);
690 	}
691 }
692 
tun_detach(struct tun_file * tfile,bool clean)693 static void tun_detach(struct tun_file *tfile, bool clean)
694 {
695 	struct tun_struct *tun;
696 	struct net_device *dev;
697 
698 	rtnl_lock();
699 	tun = rtnl_dereference(tfile->tun);
700 	dev = tun ? tun->dev : NULL;
701 	__tun_detach(tfile, clean);
702 	if (dev)
703 		netdev_state_change(dev);
704 	rtnl_unlock();
705 
706 	if (clean)
707 		sock_put(&tfile->sk);
708 }
709 
tun_detach_all(struct net_device * dev)710 static void tun_detach_all(struct net_device *dev)
711 {
712 	struct tun_struct *tun = netdev_priv(dev);
713 	struct tun_file *tfile, *tmp;
714 	int i, n = tun->numqueues;
715 
716 	for (i = 0; i < n; i++) {
717 		tfile = rtnl_dereference(tun->tfiles[i]);
718 		BUG_ON(!tfile);
719 		tun_napi_disable(tfile);
720 		tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
721 		tfile->socket.sk->sk_data_ready(tfile->socket.sk);
722 		RCU_INIT_POINTER(tfile->tun, NULL);
723 		--tun->numqueues;
724 	}
725 	list_for_each_entry(tfile, &tun->disabled, next) {
726 		tfile->socket.sk->sk_shutdown = RCV_SHUTDOWN;
727 		tfile->socket.sk->sk_data_ready(tfile->socket.sk);
728 		RCU_INIT_POINTER(tfile->tun, NULL);
729 	}
730 	BUG_ON(tun->numqueues != 0);
731 
732 	synchronize_net();
733 	for (i = 0; i < n; i++) {
734 		tfile = rtnl_dereference(tun->tfiles[i]);
735 		tun_napi_del(tfile);
736 		/* Drop read queue */
737 		tun_queue_purge(tfile);
738 		xdp_rxq_info_unreg(&tfile->xdp_rxq);
739 		sock_put(&tfile->sk);
740 	}
741 	list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
742 		tun_napi_del(tfile);
743 		tun_enable_queue(tfile);
744 		tun_queue_purge(tfile);
745 		xdp_rxq_info_unreg(&tfile->xdp_rxq);
746 		sock_put(&tfile->sk);
747 	}
748 	BUG_ON(tun->numdisabled != 0);
749 
750 	if (tun->flags & IFF_PERSIST)
751 		module_put(THIS_MODULE);
752 }
753 
tun_attach(struct tun_struct * tun,struct file * file,bool skip_filter,bool napi,bool napi_frags,bool publish_tun)754 static int tun_attach(struct tun_struct *tun, struct file *file,
755 		      bool skip_filter, bool napi, bool napi_frags,
756 		      bool publish_tun)
757 {
758 	struct tun_file *tfile = file->private_data;
759 	struct net_device *dev = tun->dev;
760 	int err;
761 
762 	err = security_tun_dev_attach(tfile->socket.sk, tun->security);
763 	if (err < 0)
764 		goto out;
765 
766 	err = -EINVAL;
767 	if (rtnl_dereference(tfile->tun) && !tfile->detached)
768 		goto out;
769 
770 	err = -EBUSY;
771 	if (!(tun->flags & IFF_MULTI_QUEUE) && tun->numqueues == 1)
772 		goto out;
773 
774 	err = -E2BIG;
775 	if (!tfile->detached &&
776 	    tun->numqueues + tun->numdisabled == MAX_TAP_QUEUES)
777 		goto out;
778 
779 	err = 0;
780 
781 	/* Re-attach the filter to persist device */
782 	if (!skip_filter && (tun->filter_attached == true)) {
783 		lock_sock(tfile->socket.sk);
784 		err = sk_attach_filter(&tun->fprog, tfile->socket.sk);
785 		release_sock(tfile->socket.sk);
786 		if (!err)
787 			goto out;
788 	}
789 
790 	if (!tfile->detached &&
791 	    ptr_ring_resize(&tfile->tx_ring, dev->tx_queue_len,
792 			    GFP_KERNEL, tun_ptr_free)) {
793 		err = -ENOMEM;
794 		goto out;
795 	}
796 
797 	tfile->queue_index = tun->numqueues;
798 	tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
799 
800 	if (tfile->detached) {
801 		/* Re-attach detached tfile, updating XDP queue_index */
802 		WARN_ON(!xdp_rxq_info_is_reg(&tfile->xdp_rxq));
803 
804 		if (tfile->xdp_rxq.queue_index    != tfile->queue_index)
805 			tfile->xdp_rxq.queue_index = tfile->queue_index;
806 	} else {
807 		/* Setup XDP RX-queue info, for new tfile getting attached */
808 		err = xdp_rxq_info_reg(&tfile->xdp_rxq,
809 				       tun->dev, tfile->queue_index, 0);
810 		if (err < 0)
811 			goto out;
812 		err = xdp_rxq_info_reg_mem_model(&tfile->xdp_rxq,
813 						 MEM_TYPE_PAGE_SHARED, NULL);
814 		if (err < 0) {
815 			xdp_rxq_info_unreg(&tfile->xdp_rxq);
816 			goto out;
817 		}
818 		err = 0;
819 	}
820 
821 	if (tfile->detached) {
822 		tun_enable_queue(tfile);
823 		tun_napi_enable(tfile);
824 	} else {
825 		sock_hold(&tfile->sk);
826 		tun_napi_init(tun, tfile, napi, napi_frags);
827 	}
828 
829 	if (rtnl_dereference(tun->xdp_prog))
830 		sock_set_flag(&tfile->sk, SOCK_XDP);
831 
832 	/* device is allowed to go away first, so no need to hold extra
833 	 * refcnt.
834 	 */
835 
836 	/* Publish tfile->tun and tun->tfiles only after we've fully
837 	 * initialized tfile; otherwise we risk using half-initialized
838 	 * object.
839 	 */
840 	if (publish_tun)
841 		rcu_assign_pointer(tfile->tun, tun);
842 	rcu_assign_pointer(tun->tfiles[tun->numqueues], tfile);
843 	tun->numqueues++;
844 	tun_set_real_num_queues(tun);
845 out:
846 	return err;
847 }
848 
tun_get(struct tun_file * tfile)849 static struct tun_struct *tun_get(struct tun_file *tfile)
850 {
851 	struct tun_struct *tun;
852 
853 	rcu_read_lock();
854 	tun = rcu_dereference(tfile->tun);
855 	if (tun)
856 		dev_hold(tun->dev);
857 	rcu_read_unlock();
858 
859 	return tun;
860 }
861 
tun_put(struct tun_struct * tun)862 static void tun_put(struct tun_struct *tun)
863 {
864 	dev_put(tun->dev);
865 }
866 
867 /* TAP filtering */
addr_hash_set(u32 * mask,const u8 * addr)868 static void addr_hash_set(u32 *mask, const u8 *addr)
869 {
870 	int n = ether_crc(ETH_ALEN, addr) >> 26;
871 	mask[n >> 5] |= (1 << (n & 31));
872 }
873 
addr_hash_test(const u32 * mask,const u8 * addr)874 static unsigned int addr_hash_test(const u32 *mask, const u8 *addr)
875 {
876 	int n = ether_crc(ETH_ALEN, addr) >> 26;
877 	return mask[n >> 5] & (1 << (n & 31));
878 }
879 
update_filter(struct tap_filter * filter,void __user * arg)880 static int update_filter(struct tap_filter *filter, void __user *arg)
881 {
882 	struct { u8 u[ETH_ALEN]; } *addr;
883 	struct tun_filter uf;
884 	int err, alen, n, nexact;
885 
886 	if (copy_from_user(&uf, arg, sizeof(uf)))
887 		return -EFAULT;
888 
889 	if (!uf.count) {
890 		/* Disabled */
891 		filter->count = 0;
892 		return 0;
893 	}
894 
895 	alen = ETH_ALEN * uf.count;
896 	addr = memdup_user(arg + sizeof(uf), alen);
897 	if (IS_ERR(addr))
898 		return PTR_ERR(addr);
899 
900 	/* The filter is updated without holding any locks. Which is
901 	 * perfectly safe. We disable it first and in the worst
902 	 * case we'll accept a few undesired packets. */
903 	filter->count = 0;
904 	wmb();
905 
906 	/* Use first set of addresses as an exact filter */
907 	for (n = 0; n < uf.count && n < FLT_EXACT_COUNT; n++)
908 		memcpy(filter->addr[n], addr[n].u, ETH_ALEN);
909 
910 	nexact = n;
911 
912 	/* Remaining multicast addresses are hashed,
913 	 * unicast will leave the filter disabled. */
914 	memset(filter->mask, 0, sizeof(filter->mask));
915 	for (; n < uf.count; n++) {
916 		if (!is_multicast_ether_addr(addr[n].u)) {
917 			err = 0; /* no filter */
918 			goto free_addr;
919 		}
920 		addr_hash_set(filter->mask, addr[n].u);
921 	}
922 
923 	/* For ALLMULTI just set the mask to all ones.
924 	 * This overrides the mask populated above. */
925 	if ((uf.flags & TUN_FLT_ALLMULTI))
926 		memset(filter->mask, ~0, sizeof(filter->mask));
927 
928 	/* Now enable the filter */
929 	wmb();
930 	filter->count = nexact;
931 
932 	/* Return the number of exact filters */
933 	err = nexact;
934 free_addr:
935 	kfree(addr);
936 	return err;
937 }
938 
939 /* Returns: 0 - drop, !=0 - accept */
run_filter(struct tap_filter * filter,const struct sk_buff * skb)940 static int run_filter(struct tap_filter *filter, const struct sk_buff *skb)
941 {
942 	/* Cannot use eth_hdr(skb) here because skb_mac_hdr() is incorrect
943 	 * at this point. */
944 	struct ethhdr *eh = (struct ethhdr *) skb->data;
945 	int i;
946 
947 	/* Exact match */
948 	for (i = 0; i < filter->count; i++)
949 		if (ether_addr_equal(eh->h_dest, filter->addr[i]))
950 			return 1;
951 
952 	/* Inexact match (multicast only) */
953 	if (is_multicast_ether_addr(eh->h_dest))
954 		return addr_hash_test(filter->mask, eh->h_dest);
955 
956 	return 0;
957 }
958 
959 /*
960  * Checks whether the packet is accepted or not.
961  * Returns: 0 - drop, !=0 - accept
962  */
check_filter(struct tap_filter * filter,const struct sk_buff * skb)963 static int check_filter(struct tap_filter *filter, const struct sk_buff *skb)
964 {
965 	if (!filter->count)
966 		return 1;
967 
968 	return run_filter(filter, skb);
969 }
970 
971 /* Network device part of the driver */
972 
973 static const struct ethtool_ops tun_ethtool_ops;
974 
tun_net_init(struct net_device * dev)975 static int tun_net_init(struct net_device *dev)
976 {
977 	struct tun_struct *tun = netdev_priv(dev);
978 	struct ifreq *ifr = tun->ifr;
979 	int err;
980 
981 	spin_lock_init(&tun->lock);
982 
983 	err = security_tun_dev_alloc_security(&tun->security);
984 	if (err < 0)
985 		return err;
986 
987 	tun_flow_init(tun);
988 
989 	dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
990 	dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
991 			   TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
992 			   NETIF_F_HW_VLAN_STAG_TX;
993 	dev->features = dev->hw_features;
994 	dev->vlan_features = dev->features &
995 			     ~(NETIF_F_HW_VLAN_CTAG_TX |
996 			       NETIF_F_HW_VLAN_STAG_TX);
997 	dev->lltx = true;
998 
999 	tun->flags = (tun->flags & ~TUN_FEATURES) |
1000 		      (ifr->ifr_flags & TUN_FEATURES);
1001 
1002 	INIT_LIST_HEAD(&tun->disabled);
1003 	err = tun_attach(tun, tun->file, false, ifr->ifr_flags & IFF_NAPI,
1004 			 ifr->ifr_flags & IFF_NAPI_FRAGS, false);
1005 	if (err < 0) {
1006 		tun_flow_uninit(tun);
1007 		security_tun_dev_free_security(tun->security);
1008 		return err;
1009 	}
1010 	return 0;
1011 }
1012 
1013 /* Net device detach from fd. */
tun_net_uninit(struct net_device * dev)1014 static void tun_net_uninit(struct net_device *dev)
1015 {
1016 	tun_detach_all(dev);
1017 }
1018 
1019 /* Net device open. */
tun_net_open(struct net_device * dev)1020 static int tun_net_open(struct net_device *dev)
1021 {
1022 	netif_tx_start_all_queues(dev);
1023 
1024 	return 0;
1025 }
1026 
1027 /* Net device close. */
tun_net_close(struct net_device * dev)1028 static int tun_net_close(struct net_device *dev)
1029 {
1030 	netif_tx_stop_all_queues(dev);
1031 	return 0;
1032 }
1033 
1034 /* Net device start xmit */
tun_automq_xmit(struct tun_struct * tun,struct sk_buff * skb)1035 static void tun_automq_xmit(struct tun_struct *tun, struct sk_buff *skb)
1036 {
1037 #ifdef CONFIG_RPS
1038 	if (tun->numqueues == 1 && static_branch_unlikely(&rps_needed)) {
1039 		/* Select queue was not called for the skbuff, so we extract the
1040 		 * RPS hash and save it into the flow_table here.
1041 		 */
1042 		struct tun_flow_entry *e;
1043 		__u32 rxhash;
1044 
1045 		rxhash = __skb_get_hash_symmetric(skb);
1046 		e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)], rxhash);
1047 		if (e)
1048 			tun_flow_save_rps_rxhash(e, rxhash);
1049 	}
1050 #endif
1051 }
1052 
run_ebpf_filter(struct tun_struct * tun,struct sk_buff * skb,int len)1053 static unsigned int run_ebpf_filter(struct tun_struct *tun,
1054 				    struct sk_buff *skb,
1055 				    int len)
1056 {
1057 	struct tun_prog *prog = rcu_dereference(tun->filter_prog);
1058 
1059 	if (prog)
1060 		len = bpf_prog_run_clear_cb(prog->prog, skb);
1061 
1062 	return len;
1063 }
1064 
1065 /* Net device start xmit */
tun_net_xmit(struct sk_buff * skb,struct net_device * dev)1066 static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
1067 {
1068 	struct tun_struct *tun = netdev_priv(dev);
1069 	enum skb_drop_reason drop_reason;
1070 	int txq = skb->queue_mapping;
1071 	struct netdev_queue *queue;
1072 	struct tun_file *tfile;
1073 	int len = skb->len;
1074 
1075 	rcu_read_lock();
1076 	tfile = rcu_dereference(tun->tfiles[txq]);
1077 
1078 	/* Drop packet if interface is not attached */
1079 	if (!tfile) {
1080 		drop_reason = SKB_DROP_REASON_DEV_READY;
1081 		goto drop;
1082 	}
1083 
1084 	if (!rcu_dereference(tun->steering_prog))
1085 		tun_automq_xmit(tun, skb);
1086 
1087 	netif_info(tun, tx_queued, tun->dev, "%s %d\n", __func__, skb->len);
1088 
1089 	/* Drop if the filter does not like it.
1090 	 * This is a noop if the filter is disabled.
1091 	 * Filter can be enabled only for the TAP devices. */
1092 	if (!check_filter(&tun->txflt, skb)) {
1093 		drop_reason = SKB_DROP_REASON_TAP_TXFILTER;
1094 		goto drop;
1095 	}
1096 
1097 	if (tfile->socket.sk->sk_filter &&
1098 	    sk_filter(tfile->socket.sk, skb)) {
1099 		drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
1100 		goto drop;
1101 	}
1102 
1103 	len = run_ebpf_filter(tun, skb, len);
1104 	if (len == 0) {
1105 		drop_reason = SKB_DROP_REASON_TAP_FILTER;
1106 		goto drop;
1107 	}
1108 
1109 	if (pskb_trim(skb, len)) {
1110 		drop_reason = SKB_DROP_REASON_NOMEM;
1111 		goto drop;
1112 	}
1113 
1114 	if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC))) {
1115 		drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;
1116 		goto drop;
1117 	}
1118 
1119 	skb_tx_timestamp(skb);
1120 
1121 	/* Orphan the skb - required as we might hang on to it
1122 	 * for indefinite time.
1123 	 */
1124 	skb_orphan(skb);
1125 
1126 	nf_reset_ct(skb);
1127 
1128 	if (ptr_ring_produce(&tfile->tx_ring, skb)) {
1129 		drop_reason = SKB_DROP_REASON_FULL_RING;
1130 		goto drop;
1131 	}
1132 
1133 	/* dev->lltx requires to do our own update of trans_start */
1134 	queue = netdev_get_tx_queue(dev, txq);
1135 	txq_trans_cond_update(queue);
1136 
1137 	/* Notify and wake up reader process */
1138 	if (tfile->flags & TUN_FASYNC)
1139 		kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
1140 	tfile->socket.sk->sk_data_ready(tfile->socket.sk);
1141 
1142 	rcu_read_unlock();
1143 	return NETDEV_TX_OK;
1144 
1145 drop:
1146 	dev_core_stats_tx_dropped_inc(dev);
1147 	skb_tx_error(skb);
1148 	kfree_skb_reason(skb, drop_reason);
1149 	rcu_read_unlock();
1150 	return NET_XMIT_DROP;
1151 }
1152 
tun_net_mclist(struct net_device * dev)1153 static void tun_net_mclist(struct net_device *dev)
1154 {
1155 	/*
1156 	 * This callback is supposed to deal with mc filter in
1157 	 * _rx_ path and has nothing to do with the _tx_ path.
1158 	 * In rx path we always accept everything userspace gives us.
1159 	 */
1160 }
1161 
tun_net_fix_features(struct net_device * dev,netdev_features_t features)1162 static netdev_features_t tun_net_fix_features(struct net_device *dev,
1163 	netdev_features_t features)
1164 {
1165 	struct tun_struct *tun = netdev_priv(dev);
1166 
1167 	return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
1168 }
1169 
tun_set_headroom(struct net_device * dev,int new_hr)1170 static void tun_set_headroom(struct net_device *dev, int new_hr)
1171 {
1172 	struct tun_struct *tun = netdev_priv(dev);
1173 
1174 	if (new_hr < NET_SKB_PAD)
1175 		new_hr = NET_SKB_PAD;
1176 
1177 	tun->align = new_hr;
1178 }
1179 
1180 static void
tun_net_get_stats64(struct net_device * dev,struct rtnl_link_stats64 * stats)1181 tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
1182 {
1183 	struct tun_struct *tun = netdev_priv(dev);
1184 
1185 	dev_get_tstats64(dev, stats);
1186 
1187 	stats->rx_frame_errors +=
1188 		(unsigned long)atomic_long_read(&tun->rx_frame_errors);
1189 }
1190 
tun_xdp_set(struct net_device * dev,struct bpf_prog * prog,struct netlink_ext_ack * extack)1191 static int tun_xdp_set(struct net_device *dev, struct bpf_prog *prog,
1192 		       struct netlink_ext_ack *extack)
1193 {
1194 	struct tun_struct *tun = netdev_priv(dev);
1195 	struct tun_file *tfile;
1196 	struct bpf_prog *old_prog;
1197 	int i;
1198 
1199 	old_prog = rtnl_dereference(tun->xdp_prog);
1200 	rcu_assign_pointer(tun->xdp_prog, prog);
1201 	if (old_prog)
1202 		bpf_prog_put(old_prog);
1203 
1204 	for (i = 0; i < tun->numqueues; i++) {
1205 		tfile = rtnl_dereference(tun->tfiles[i]);
1206 		if (prog)
1207 			sock_set_flag(&tfile->sk, SOCK_XDP);
1208 		else
1209 			sock_reset_flag(&tfile->sk, SOCK_XDP);
1210 	}
1211 	list_for_each_entry(tfile, &tun->disabled, next) {
1212 		if (prog)
1213 			sock_set_flag(&tfile->sk, SOCK_XDP);
1214 		else
1215 			sock_reset_flag(&tfile->sk, SOCK_XDP);
1216 	}
1217 
1218 	return 0;
1219 }
1220 
tun_xdp(struct net_device * dev,struct netdev_bpf * xdp)1221 static int tun_xdp(struct net_device *dev, struct netdev_bpf *xdp)
1222 {
1223 	switch (xdp->command) {
1224 	case XDP_SETUP_PROG:
1225 		return tun_xdp_set(dev, xdp->prog, xdp->extack);
1226 	default:
1227 		return -EINVAL;
1228 	}
1229 }
1230 
tun_net_change_carrier(struct net_device * dev,bool new_carrier)1231 static int tun_net_change_carrier(struct net_device *dev, bool new_carrier)
1232 {
1233 	if (new_carrier) {
1234 		struct tun_struct *tun = netdev_priv(dev);
1235 
1236 		if (!tun->numqueues)
1237 			return -EPERM;
1238 
1239 		netif_carrier_on(dev);
1240 	} else {
1241 		netif_carrier_off(dev);
1242 	}
1243 	return 0;
1244 }
1245 
1246 static const struct net_device_ops tun_netdev_ops = {
1247 	.ndo_init		= tun_net_init,
1248 	.ndo_uninit		= tun_net_uninit,
1249 	.ndo_open		= tun_net_open,
1250 	.ndo_stop		= tun_net_close,
1251 	.ndo_start_xmit		= tun_net_xmit,
1252 	.ndo_fix_features	= tun_net_fix_features,
1253 	.ndo_select_queue	= tun_select_queue,
1254 	.ndo_set_rx_headroom	= tun_set_headroom,
1255 	.ndo_get_stats64	= tun_net_get_stats64,
1256 	.ndo_change_carrier	= tun_net_change_carrier,
1257 };
1258 
__tun_xdp_flush_tfile(struct tun_file * tfile)1259 static void __tun_xdp_flush_tfile(struct tun_file *tfile)
1260 {
1261 	/* Notify and wake up reader process */
1262 	if (tfile->flags & TUN_FASYNC)
1263 		kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
1264 	tfile->socket.sk->sk_data_ready(tfile->socket.sk);
1265 }
1266 
tun_xdp_xmit(struct net_device * dev,int n,struct xdp_frame ** frames,u32 flags)1267 static int tun_xdp_xmit(struct net_device *dev, int n,
1268 			struct xdp_frame **frames, u32 flags)
1269 {
1270 	struct tun_struct *tun = netdev_priv(dev);
1271 	struct tun_file *tfile;
1272 	u32 numqueues;
1273 	int nxmit = 0;
1274 	int i;
1275 
1276 	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
1277 		return -EINVAL;
1278 
1279 	rcu_read_lock();
1280 
1281 resample:
1282 	numqueues = READ_ONCE(tun->numqueues);
1283 	if (!numqueues) {
1284 		rcu_read_unlock();
1285 		return -ENXIO; /* Caller will free/return all frames */
1286 	}
1287 
1288 	tfile = rcu_dereference(tun->tfiles[smp_processor_id() %
1289 					    numqueues]);
1290 	if (unlikely(!tfile))
1291 		goto resample;
1292 
1293 	spin_lock(&tfile->tx_ring.producer_lock);
1294 	for (i = 0; i < n; i++) {
1295 		struct xdp_frame *xdp = frames[i];
1296 		/* Encode the XDP flag into lowest bit for consumer to differ
1297 		 * XDP buffer from sk_buff.
1298 		 */
1299 		void *frame = tun_xdp_to_ptr(xdp);
1300 
1301 		if (__ptr_ring_produce(&tfile->tx_ring, frame)) {
1302 			dev_core_stats_tx_dropped_inc(dev);
1303 			break;
1304 		}
1305 		nxmit++;
1306 	}
1307 	spin_unlock(&tfile->tx_ring.producer_lock);
1308 
1309 	if (flags & XDP_XMIT_FLUSH)
1310 		__tun_xdp_flush_tfile(tfile);
1311 
1312 	rcu_read_unlock();
1313 	return nxmit;
1314 }
1315 
tun_xdp_tx(struct net_device * dev,struct xdp_buff * xdp)1316 static int tun_xdp_tx(struct net_device *dev, struct xdp_buff *xdp)
1317 {
1318 	struct xdp_frame *frame = xdp_convert_buff_to_frame(xdp);
1319 	int nxmit;
1320 
1321 	if (unlikely(!frame))
1322 		return -EOVERFLOW;
1323 
1324 	nxmit = tun_xdp_xmit(dev, 1, &frame, XDP_XMIT_FLUSH);
1325 	if (!nxmit)
1326 		xdp_return_frame_rx_napi(frame);
1327 	return nxmit;
1328 }
1329 
1330 static const struct net_device_ops tap_netdev_ops = {
1331 	.ndo_init		= tun_net_init,
1332 	.ndo_uninit		= tun_net_uninit,
1333 	.ndo_open		= tun_net_open,
1334 	.ndo_stop		= tun_net_close,
1335 	.ndo_start_xmit		= tun_net_xmit,
1336 	.ndo_fix_features	= tun_net_fix_features,
1337 	.ndo_set_rx_mode	= tun_net_mclist,
1338 	.ndo_set_mac_address	= eth_mac_addr,
1339 	.ndo_validate_addr	= eth_validate_addr,
1340 	.ndo_select_queue	= tun_select_queue,
1341 	.ndo_features_check	= passthru_features_check,
1342 	.ndo_set_rx_headroom	= tun_set_headroom,
1343 	.ndo_bpf		= tun_xdp,
1344 	.ndo_xdp_xmit		= tun_xdp_xmit,
1345 	.ndo_change_carrier	= tun_net_change_carrier,
1346 };
1347 
tun_flow_init(struct tun_struct * tun)1348 static void tun_flow_init(struct tun_struct *tun)
1349 {
1350 	int i;
1351 
1352 	for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++)
1353 		INIT_HLIST_HEAD(&tun->flows[i]);
1354 
1355 	tun->ageing_time = TUN_FLOW_EXPIRE;
1356 	timer_setup(&tun->flow_gc_timer, tun_flow_cleanup, 0);
1357 	mod_timer(&tun->flow_gc_timer,
1358 		  round_jiffies_up(jiffies + tun->ageing_time));
1359 }
1360 
tun_flow_uninit(struct tun_struct * tun)1361 static void tun_flow_uninit(struct tun_struct *tun)
1362 {
1363 	del_timer_sync(&tun->flow_gc_timer);
1364 	tun_flow_flush(tun);
1365 }
1366 
1367 #define MIN_MTU 68
1368 #define MAX_MTU 65535
1369 
1370 /* Initialize net device. */
tun_net_initialize(struct net_device * dev)1371 static void tun_net_initialize(struct net_device *dev)
1372 {
1373 	struct tun_struct *tun = netdev_priv(dev);
1374 
1375 	switch (tun->flags & TUN_TYPE_MASK) {
1376 	case IFF_TUN:
1377 		dev->netdev_ops = &tun_netdev_ops;
1378 		dev->header_ops = &ip_tunnel_header_ops;
1379 
1380 		/* Point-to-Point TUN Device */
1381 		dev->hard_header_len = 0;
1382 		dev->addr_len = 0;
1383 		dev->mtu = 1500;
1384 
1385 		/* Zero header length */
1386 		dev->type = ARPHRD_NONE;
1387 		dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1388 		break;
1389 
1390 	case IFF_TAP:
1391 		dev->netdev_ops = &tap_netdev_ops;
1392 		/* Ethernet TAP Device */
1393 		ether_setup(dev);
1394 		dev->priv_flags &= ~IFF_TX_SKB_SHARING;
1395 		dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
1396 
1397 		eth_hw_addr_random(dev);
1398 
1399 		/* Currently tun does not support XDP, only tap does. */
1400 		dev->xdp_features = NETDEV_XDP_ACT_BASIC |
1401 				    NETDEV_XDP_ACT_REDIRECT |
1402 				    NETDEV_XDP_ACT_NDO_XMIT;
1403 
1404 		break;
1405 	}
1406 
1407 	dev->min_mtu = MIN_MTU;
1408 	dev->max_mtu = MAX_MTU - dev->hard_header_len;
1409 }
1410 
tun_sock_writeable(struct tun_struct * tun,struct tun_file * tfile)1411 static bool tun_sock_writeable(struct tun_struct *tun, struct tun_file *tfile)
1412 {
1413 	struct sock *sk = tfile->socket.sk;
1414 
1415 	return (tun->dev->flags & IFF_UP) && sock_writeable(sk);
1416 }
1417 
1418 /* Character device part */
1419 
1420 /* Poll */
tun_chr_poll(struct file * file,poll_table * wait)1421 static __poll_t tun_chr_poll(struct file *file, poll_table *wait)
1422 {
1423 	struct tun_file *tfile = file->private_data;
1424 	struct tun_struct *tun = tun_get(tfile);
1425 	struct sock *sk;
1426 	__poll_t mask = 0;
1427 
1428 	if (!tun)
1429 		return EPOLLERR;
1430 
1431 	sk = tfile->socket.sk;
1432 
1433 	poll_wait(file, sk_sleep(sk), wait);
1434 
1435 	if (!ptr_ring_empty(&tfile->tx_ring))
1436 		mask |= EPOLLIN | EPOLLRDNORM;
1437 
1438 	/* Make sure SOCKWQ_ASYNC_NOSPACE is set if not writable to
1439 	 * guarantee EPOLLOUT to be raised by either here or
1440 	 * tun_sock_write_space(). Then process could get notification
1441 	 * after it writes to a down device and meets -EIO.
1442 	 */
1443 	if (tun_sock_writeable(tun, tfile) ||
1444 	    (!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags) &&
1445 	     tun_sock_writeable(tun, tfile)))
1446 		mask |= EPOLLOUT | EPOLLWRNORM;
1447 
1448 	if (tun->dev->reg_state != NETREG_REGISTERED)
1449 		mask = EPOLLERR;
1450 
1451 	tun_put(tun);
1452 	return mask;
1453 }
1454 
tun_napi_alloc_frags(struct tun_file * tfile,size_t len,const struct iov_iter * it)1455 static struct sk_buff *tun_napi_alloc_frags(struct tun_file *tfile,
1456 					    size_t len,
1457 					    const struct iov_iter *it)
1458 {
1459 	struct sk_buff *skb;
1460 	size_t linear;
1461 	int err;
1462 	int i;
1463 
1464 	if (it->nr_segs > MAX_SKB_FRAGS + 1 ||
1465 	    len > (ETH_MAX_MTU - NET_SKB_PAD - NET_IP_ALIGN))
1466 		return ERR_PTR(-EMSGSIZE);
1467 
1468 	local_bh_disable();
1469 	skb = napi_get_frags(&tfile->napi);
1470 	local_bh_enable();
1471 	if (!skb)
1472 		return ERR_PTR(-ENOMEM);
1473 
1474 	linear = iov_iter_single_seg_count(it);
1475 	err = __skb_grow(skb, linear);
1476 	if (err)
1477 		goto free;
1478 
1479 	skb->len = len;
1480 	skb->data_len = len - linear;
1481 	skb->truesize += skb->data_len;
1482 
1483 	for (i = 1; i < it->nr_segs; i++) {
1484 		const struct iovec *iov = iter_iov(it) + i;
1485 		size_t fragsz = iov->iov_len;
1486 		struct page *page;
1487 		void *frag;
1488 
1489 		if (fragsz == 0 || fragsz > PAGE_SIZE) {
1490 			err = -EINVAL;
1491 			goto free;
1492 		}
1493 		frag = netdev_alloc_frag(fragsz);
1494 		if (!frag) {
1495 			err = -ENOMEM;
1496 			goto free;
1497 		}
1498 		page = virt_to_head_page(frag);
1499 		skb_fill_page_desc(skb, i - 1, page,
1500 				   frag - page_address(page), fragsz);
1501 	}
1502 
1503 	return skb;
1504 free:
1505 	/* frees skb and all frags allocated with napi_alloc_frag() */
1506 	napi_free_frags(&tfile->napi);
1507 	return ERR_PTR(err);
1508 }
1509 
1510 /* prepad is the amount to reserve at front.  len is length after that.
1511  * linear is a hint as to how much to copy (usually headers). */
tun_alloc_skb(struct tun_file * tfile,size_t prepad,size_t len,size_t linear,int noblock)1512 static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
1513 				     size_t prepad, size_t len,
1514 				     size_t linear, int noblock)
1515 {
1516 	struct sock *sk = tfile->socket.sk;
1517 	struct sk_buff *skb;
1518 	int err;
1519 
1520 	/* Under a page?  Don't bother with paged skb. */
1521 	if (prepad + len < PAGE_SIZE)
1522 		linear = len;
1523 
1524 	if (len - linear > MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
1525 		linear = len - MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER);
1526 	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
1527 				   &err, PAGE_ALLOC_COSTLY_ORDER);
1528 	if (!skb)
1529 		return ERR_PTR(err);
1530 
1531 	skb_reserve(skb, prepad);
1532 	skb_put(skb, linear);
1533 	skb->data_len = len - linear;
1534 	skb->len += len - linear;
1535 
1536 	return skb;
1537 }
1538 
tun_rx_batched(struct tun_struct * tun,struct tun_file * tfile,struct sk_buff * skb,int more)1539 static void tun_rx_batched(struct tun_struct *tun, struct tun_file *tfile,
1540 			   struct sk_buff *skb, int more)
1541 {
1542 	struct sk_buff_head *queue = &tfile->sk.sk_write_queue;
1543 	struct sk_buff_head process_queue;
1544 	u32 rx_batched = tun->rx_batched;
1545 	bool rcv = false;
1546 
1547 	if (!rx_batched || (!more && skb_queue_empty(queue))) {
1548 		local_bh_disable();
1549 		skb_record_rx_queue(skb, tfile->queue_index);
1550 		netif_receive_skb(skb);
1551 		local_bh_enable();
1552 		return;
1553 	}
1554 
1555 	spin_lock(&queue->lock);
1556 	if (!more || skb_queue_len(queue) == rx_batched) {
1557 		__skb_queue_head_init(&process_queue);
1558 		skb_queue_splice_tail_init(queue, &process_queue);
1559 		rcv = true;
1560 	} else {
1561 		__skb_queue_tail(queue, skb);
1562 	}
1563 	spin_unlock(&queue->lock);
1564 
1565 	if (rcv) {
1566 		struct sk_buff *nskb;
1567 
1568 		local_bh_disable();
1569 		while ((nskb = __skb_dequeue(&process_queue))) {
1570 			skb_record_rx_queue(nskb, tfile->queue_index);
1571 			netif_receive_skb(nskb);
1572 		}
1573 		skb_record_rx_queue(skb, tfile->queue_index);
1574 		netif_receive_skb(skb);
1575 		local_bh_enable();
1576 	}
1577 }
1578 
tun_can_build_skb(struct tun_struct * tun,struct tun_file * tfile,int len,int noblock,bool zerocopy)1579 static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile,
1580 			      int len, int noblock, bool zerocopy)
1581 {
1582 	if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
1583 		return false;
1584 
1585 	if (tfile->socket.sk->sk_sndbuf != INT_MAX)
1586 		return false;
1587 
1588 	if (!noblock)
1589 		return false;
1590 
1591 	if (zerocopy)
1592 		return false;
1593 
1594 	if (SKB_DATA_ALIGN(len + TUN_RX_PAD + XDP_PACKET_HEADROOM) +
1595 	    SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE)
1596 		return false;
1597 
1598 	return true;
1599 }
1600 
__tun_build_skb(struct tun_file * tfile,struct page_frag * alloc_frag,char * buf,int buflen,int len,int pad)1601 static struct sk_buff *__tun_build_skb(struct tun_file *tfile,
1602 				       struct page_frag *alloc_frag, char *buf,
1603 				       int buflen, int len, int pad)
1604 {
1605 	struct sk_buff *skb = build_skb(buf, buflen);
1606 
1607 	if (!skb)
1608 		return ERR_PTR(-ENOMEM);
1609 
1610 	skb_reserve(skb, pad);
1611 	skb_put(skb, len);
1612 	skb_set_owner_w(skb, tfile->socket.sk);
1613 
1614 	get_page(alloc_frag->page);
1615 	alloc_frag->offset += buflen;
1616 
1617 	return skb;
1618 }
1619 
tun_xdp_act(struct tun_struct * tun,struct bpf_prog * xdp_prog,struct xdp_buff * xdp,u32 act)1620 static int tun_xdp_act(struct tun_struct *tun, struct bpf_prog *xdp_prog,
1621 		       struct xdp_buff *xdp, u32 act)
1622 {
1623 	int err;
1624 
1625 	switch (act) {
1626 	case XDP_REDIRECT:
1627 		err = xdp_do_redirect(tun->dev, xdp, xdp_prog);
1628 		if (err) {
1629 			dev_core_stats_rx_dropped_inc(tun->dev);
1630 			return err;
1631 		}
1632 		dev_sw_netstats_rx_add(tun->dev, xdp->data_end - xdp->data);
1633 		break;
1634 	case XDP_TX:
1635 		err = tun_xdp_tx(tun->dev, xdp);
1636 		if (err < 0) {
1637 			dev_core_stats_rx_dropped_inc(tun->dev);
1638 			return err;
1639 		}
1640 		dev_sw_netstats_rx_add(tun->dev, xdp->data_end - xdp->data);
1641 		break;
1642 	case XDP_PASS:
1643 		break;
1644 	default:
1645 		bpf_warn_invalid_xdp_action(tun->dev, xdp_prog, act);
1646 		fallthrough;
1647 	case XDP_ABORTED:
1648 		trace_xdp_exception(tun->dev, xdp_prog, act);
1649 		fallthrough;
1650 	case XDP_DROP:
1651 		dev_core_stats_rx_dropped_inc(tun->dev);
1652 		break;
1653 	}
1654 
1655 	return act;
1656 }
1657 
tun_build_skb(struct tun_struct * tun,struct tun_file * tfile,struct iov_iter * from,struct virtio_net_hdr * hdr,int len,int * skb_xdp)1658 static struct sk_buff *tun_build_skb(struct tun_struct *tun,
1659 				     struct tun_file *tfile,
1660 				     struct iov_iter *from,
1661 				     struct virtio_net_hdr *hdr,
1662 				     int len, int *skb_xdp)
1663 {
1664 	struct page_frag *alloc_frag = &current->task_frag;
1665 	struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
1666 	struct bpf_prog *xdp_prog;
1667 	int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
1668 	char *buf;
1669 	size_t copied;
1670 	int pad = TUN_RX_PAD;
1671 	int err = 0;
1672 
1673 	rcu_read_lock();
1674 	xdp_prog = rcu_dereference(tun->xdp_prog);
1675 	if (xdp_prog)
1676 		pad += XDP_PACKET_HEADROOM;
1677 	buflen += SKB_DATA_ALIGN(len + pad);
1678 	rcu_read_unlock();
1679 
1680 	alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
1681 	if (unlikely(!skb_page_frag_refill(buflen, alloc_frag, GFP_KERNEL)))
1682 		return ERR_PTR(-ENOMEM);
1683 
1684 	buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
1685 	copied = copy_page_from_iter(alloc_frag->page,
1686 				     alloc_frag->offset + pad,
1687 				     len, from);
1688 	if (copied != len)
1689 		return ERR_PTR(-EFAULT);
1690 
1691 	/* There's a small window that XDP may be set after the check
1692 	 * of xdp_prog above, this should be rare and for simplicity
1693 	 * we do XDP on skb in case the headroom is not enough.
1694 	 */
1695 	if (hdr->gso_type || !xdp_prog) {
1696 		*skb_xdp = 1;
1697 		return __tun_build_skb(tfile, alloc_frag, buf, buflen, len,
1698 				       pad);
1699 	}
1700 
1701 	*skb_xdp = 0;
1702 
1703 	local_bh_disable();
1704 	rcu_read_lock();
1705 	bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
1706 	xdp_prog = rcu_dereference(tun->xdp_prog);
1707 	if (xdp_prog) {
1708 		struct xdp_buff xdp;
1709 		u32 act;
1710 
1711 		xdp_init_buff(&xdp, buflen, &tfile->xdp_rxq);
1712 		xdp_prepare_buff(&xdp, buf, pad, len, false);
1713 
1714 		act = bpf_prog_run_xdp(xdp_prog, &xdp);
1715 		if (act == XDP_REDIRECT || act == XDP_TX) {
1716 			get_page(alloc_frag->page);
1717 			alloc_frag->offset += buflen;
1718 		}
1719 		err = tun_xdp_act(tun, xdp_prog, &xdp, act);
1720 		if (err < 0) {
1721 			if (act == XDP_REDIRECT || act == XDP_TX)
1722 				put_page(alloc_frag->page);
1723 			goto out;
1724 		}
1725 
1726 		if (err == XDP_REDIRECT)
1727 			xdp_do_flush();
1728 		if (err != XDP_PASS)
1729 			goto out;
1730 
1731 		pad = xdp.data - xdp.data_hard_start;
1732 		len = xdp.data_end - xdp.data;
1733 	}
1734 	bpf_net_ctx_clear(bpf_net_ctx);
1735 	rcu_read_unlock();
1736 	local_bh_enable();
1737 
1738 	return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, pad);
1739 
1740 out:
1741 	bpf_net_ctx_clear(bpf_net_ctx);
1742 	rcu_read_unlock();
1743 	local_bh_enable();
1744 	return NULL;
1745 }
1746 
1747 /* Get packet from user space buffer */
tun_get_user(struct tun_struct * tun,struct tun_file * tfile,void * msg_control,struct iov_iter * from,int noblock,bool more)1748 static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
1749 			    void *msg_control, struct iov_iter *from,
1750 			    int noblock, bool more)
1751 {
1752 	struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
1753 	struct sk_buff *skb;
1754 	size_t total_len = iov_iter_count(from);
1755 	size_t len = total_len, align = tun->align, linear;
1756 	struct virtio_net_hdr gso = { 0 };
1757 	int good_linear;
1758 	int copylen;
1759 	bool zerocopy = false;
1760 	int err;
1761 	u32 rxhash = 0;
1762 	int skb_xdp = 1;
1763 	bool frags = tun_napi_frags_enabled(tfile);
1764 	enum skb_drop_reason drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
1765 
1766 	if (!(tun->flags & IFF_NO_PI)) {
1767 		if (len < sizeof(pi))
1768 			return -EINVAL;
1769 		len -= sizeof(pi);
1770 
1771 		if (!copy_from_iter_full(&pi, sizeof(pi), from))
1772 			return -EFAULT;
1773 	}
1774 
1775 	if (tun->flags & IFF_VNET_HDR) {
1776 		int vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
1777 
1778 		if (len < vnet_hdr_sz)
1779 			return -EINVAL;
1780 		len -= vnet_hdr_sz;
1781 
1782 		if (!copy_from_iter_full(&gso, sizeof(gso), from))
1783 			return -EFAULT;
1784 
1785 		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
1786 		    tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2 > tun16_to_cpu(tun, gso.hdr_len))
1787 			gso.hdr_len = cpu_to_tun16(tun, tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2);
1788 
1789 		if (tun16_to_cpu(tun, gso.hdr_len) > len)
1790 			return -EINVAL;
1791 		iov_iter_advance(from, vnet_hdr_sz - sizeof(gso));
1792 	}
1793 
1794 	if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
1795 		align += NET_IP_ALIGN;
1796 		if (unlikely(len < ETH_HLEN ||
1797 			     (gso.hdr_len && tun16_to_cpu(tun, gso.hdr_len) < ETH_HLEN)))
1798 			return -EINVAL;
1799 	}
1800 
1801 	good_linear = SKB_MAX_HEAD(align);
1802 
1803 	if (msg_control) {
1804 		struct iov_iter i = *from;
1805 
1806 		/* There are 256 bytes to be copied in skb, so there is
1807 		 * enough room for skb expand head in case it is used.
1808 		 * The rest of the buffer is mapped from userspace.
1809 		 */
1810 		copylen = gso.hdr_len ? tun16_to_cpu(tun, gso.hdr_len) : GOODCOPY_LEN;
1811 		if (copylen > good_linear)
1812 			copylen = good_linear;
1813 		linear = copylen;
1814 		iov_iter_advance(&i, copylen);
1815 		if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
1816 			zerocopy = true;
1817 	}
1818 
1819 	if (!frags && tun_can_build_skb(tun, tfile, len, noblock, zerocopy)) {
1820 		/* For the packet that is not easy to be processed
1821 		 * (e.g gso or jumbo packet), we will do it at after
1822 		 * skb was created with generic XDP routine.
1823 		 */
1824 		skb = tun_build_skb(tun, tfile, from, &gso, len, &skb_xdp);
1825 		err = PTR_ERR_OR_ZERO(skb);
1826 		if (err)
1827 			goto drop;
1828 		if (!skb)
1829 			return total_len;
1830 	} else {
1831 		if (!zerocopy) {
1832 			copylen = len;
1833 			if (tun16_to_cpu(tun, gso.hdr_len) > good_linear)
1834 				linear = good_linear;
1835 			else
1836 				linear = tun16_to_cpu(tun, gso.hdr_len);
1837 		}
1838 
1839 		if (frags) {
1840 			mutex_lock(&tfile->napi_mutex);
1841 			skb = tun_napi_alloc_frags(tfile, copylen, from);
1842 			/* tun_napi_alloc_frags() enforces a layout for the skb.
1843 			 * If zerocopy is enabled, then this layout will be
1844 			 * overwritten by zerocopy_sg_from_iter().
1845 			 */
1846 			zerocopy = false;
1847 		} else {
1848 			if (!linear)
1849 				linear = min_t(size_t, good_linear, copylen);
1850 
1851 			skb = tun_alloc_skb(tfile, align, copylen, linear,
1852 					    noblock);
1853 		}
1854 
1855 		err = PTR_ERR_OR_ZERO(skb);
1856 		if (err)
1857 			goto drop;
1858 
1859 		if (zerocopy)
1860 			err = zerocopy_sg_from_iter(skb, from);
1861 		else
1862 			err = skb_copy_datagram_from_iter(skb, 0, from, len);
1863 
1864 		if (err) {
1865 			err = -EFAULT;
1866 			drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;
1867 			goto drop;
1868 		}
1869 	}
1870 
1871 	if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun))) {
1872 		atomic_long_inc(&tun->rx_frame_errors);
1873 		err = -EINVAL;
1874 		goto free_skb;
1875 	}
1876 
1877 	switch (tun->flags & TUN_TYPE_MASK) {
1878 	case IFF_TUN:
1879 		if (tun->flags & IFF_NO_PI) {
1880 			u8 ip_version = skb->len ? (skb->data[0] >> 4) : 0;
1881 
1882 			switch (ip_version) {
1883 			case 4:
1884 				pi.proto = htons(ETH_P_IP);
1885 				break;
1886 			case 6:
1887 				pi.proto = htons(ETH_P_IPV6);
1888 				break;
1889 			default:
1890 				err = -EINVAL;
1891 				goto drop;
1892 			}
1893 		}
1894 
1895 		skb_reset_mac_header(skb);
1896 		skb->protocol = pi.proto;
1897 		skb->dev = tun->dev;
1898 		break;
1899 	case IFF_TAP:
1900 		if (frags && !pskb_may_pull(skb, ETH_HLEN)) {
1901 			err = -ENOMEM;
1902 			drop_reason = SKB_DROP_REASON_HDR_TRUNC;
1903 			goto drop;
1904 		}
1905 		skb->protocol = eth_type_trans(skb, tun->dev);
1906 		break;
1907 	}
1908 
1909 	/* copy skb_ubuf_info for callback when skb has no error */
1910 	if (zerocopy) {
1911 		skb_zcopy_init(skb, msg_control);
1912 	} else if (msg_control) {
1913 		struct ubuf_info *uarg = msg_control;
1914 		uarg->ops->complete(NULL, uarg, false);
1915 	}
1916 
1917 	skb_reset_network_header(skb);
1918 	skb_probe_transport_header(skb);
1919 	skb_record_rx_queue(skb, tfile->queue_index);
1920 
1921 	if (skb_xdp) {
1922 		struct bpf_prog *xdp_prog;
1923 		int ret;
1924 
1925 		local_bh_disable();
1926 		rcu_read_lock();
1927 		xdp_prog = rcu_dereference(tun->xdp_prog);
1928 		if (xdp_prog) {
1929 			ret = do_xdp_generic(xdp_prog, &skb);
1930 			if (ret != XDP_PASS) {
1931 				rcu_read_unlock();
1932 				local_bh_enable();
1933 				goto unlock_frags;
1934 			}
1935 		}
1936 		rcu_read_unlock();
1937 		local_bh_enable();
1938 	}
1939 
1940 	/* Compute the costly rx hash only if needed for flow updates.
1941 	 * We may get a very small possibility of OOO during switching, not
1942 	 * worth to optimize.
1943 	 */
1944 	if (!rcu_access_pointer(tun->steering_prog) && tun->numqueues > 1 &&
1945 	    !tfile->detached)
1946 		rxhash = __skb_get_hash_symmetric(skb);
1947 
1948 	rcu_read_lock();
1949 	if (unlikely(!(tun->dev->flags & IFF_UP))) {
1950 		err = -EIO;
1951 		rcu_read_unlock();
1952 		drop_reason = SKB_DROP_REASON_DEV_READY;
1953 		goto drop;
1954 	}
1955 
1956 	if (frags) {
1957 		u32 headlen;
1958 
1959 		/* Exercise flow dissector code path. */
1960 		skb_push(skb, ETH_HLEN);
1961 		headlen = eth_get_headlen(tun->dev, skb->data,
1962 					  skb_headlen(skb));
1963 
1964 		if (unlikely(headlen > skb_headlen(skb))) {
1965 			WARN_ON_ONCE(1);
1966 			err = -ENOMEM;
1967 			dev_core_stats_rx_dropped_inc(tun->dev);
1968 napi_busy:
1969 			napi_free_frags(&tfile->napi);
1970 			rcu_read_unlock();
1971 			mutex_unlock(&tfile->napi_mutex);
1972 			return err;
1973 		}
1974 
1975 		if (likely(napi_schedule_prep(&tfile->napi))) {
1976 			local_bh_disable();
1977 			napi_gro_frags(&tfile->napi);
1978 			napi_complete(&tfile->napi);
1979 			local_bh_enable();
1980 		} else {
1981 			err = -EBUSY;
1982 			goto napi_busy;
1983 		}
1984 		mutex_unlock(&tfile->napi_mutex);
1985 	} else if (tfile->napi_enabled) {
1986 		struct sk_buff_head *queue = &tfile->sk.sk_write_queue;
1987 		int queue_len;
1988 
1989 		spin_lock_bh(&queue->lock);
1990 
1991 		if (unlikely(tfile->detached)) {
1992 			spin_unlock_bh(&queue->lock);
1993 			rcu_read_unlock();
1994 			err = -EBUSY;
1995 			goto free_skb;
1996 		}
1997 
1998 		__skb_queue_tail(queue, skb);
1999 		queue_len = skb_queue_len(queue);
2000 		spin_unlock(&queue->lock);
2001 
2002 		if (!more || queue_len > NAPI_POLL_WEIGHT)
2003 			napi_schedule(&tfile->napi);
2004 
2005 		local_bh_enable();
2006 	} else if (!IS_ENABLED(CONFIG_4KSTACKS)) {
2007 		tun_rx_batched(tun, tfile, skb, more);
2008 	} else {
2009 		netif_rx(skb);
2010 	}
2011 	rcu_read_unlock();
2012 
2013 	preempt_disable();
2014 	dev_sw_netstats_rx_add(tun->dev, len);
2015 	preempt_enable();
2016 
2017 	if (rxhash)
2018 		tun_flow_update(tun, rxhash, tfile);
2019 
2020 	return total_len;
2021 
2022 drop:
2023 	if (err != -EAGAIN)
2024 		dev_core_stats_rx_dropped_inc(tun->dev);
2025 
2026 free_skb:
2027 	if (!IS_ERR_OR_NULL(skb))
2028 		kfree_skb_reason(skb, drop_reason);
2029 
2030 unlock_frags:
2031 	if (frags) {
2032 		tfile->napi.skb = NULL;
2033 		mutex_unlock(&tfile->napi_mutex);
2034 	}
2035 
2036 	return err ?: total_len;
2037 }
2038 
tun_chr_write_iter(struct kiocb * iocb,struct iov_iter * from)2039 static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
2040 {
2041 	struct file *file = iocb->ki_filp;
2042 	struct tun_file *tfile = file->private_data;
2043 	struct tun_struct *tun = tun_get(tfile);
2044 	ssize_t result;
2045 	int noblock = 0;
2046 
2047 	if (!tun)
2048 		return -EBADFD;
2049 
2050 	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
2051 		noblock = 1;
2052 
2053 	result = tun_get_user(tun, tfile, NULL, from, noblock, false);
2054 
2055 	tun_put(tun);
2056 	return result;
2057 }
2058 
tun_put_user_xdp(struct tun_struct * tun,struct tun_file * tfile,struct xdp_frame * xdp_frame,struct iov_iter * iter)2059 static ssize_t tun_put_user_xdp(struct tun_struct *tun,
2060 				struct tun_file *tfile,
2061 				struct xdp_frame *xdp_frame,
2062 				struct iov_iter *iter)
2063 {
2064 	int vnet_hdr_sz = 0;
2065 	size_t size = xdp_frame->len;
2066 	size_t ret;
2067 
2068 	if (tun->flags & IFF_VNET_HDR) {
2069 		struct virtio_net_hdr gso = { 0 };
2070 
2071 		vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
2072 		if (unlikely(iov_iter_count(iter) < vnet_hdr_sz))
2073 			return -EINVAL;
2074 		if (unlikely(copy_to_iter(&gso, sizeof(gso), iter) !=
2075 			     sizeof(gso)))
2076 			return -EFAULT;
2077 		iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
2078 	}
2079 
2080 	ret = copy_to_iter(xdp_frame->data, size, iter) + vnet_hdr_sz;
2081 
2082 	preempt_disable();
2083 	dev_sw_netstats_tx_add(tun->dev, 1, ret);
2084 	preempt_enable();
2085 
2086 	return ret;
2087 }
2088 
2089 /* Put packet to the user space buffer */
tun_put_user(struct tun_struct * tun,struct tun_file * tfile,struct sk_buff * skb,struct iov_iter * iter)2090 static ssize_t tun_put_user(struct tun_struct *tun,
2091 			    struct tun_file *tfile,
2092 			    struct sk_buff *skb,
2093 			    struct iov_iter *iter)
2094 {
2095 	struct tun_pi pi = { 0, skb->protocol };
2096 	ssize_t total;
2097 	int vlan_offset = 0;
2098 	int vlan_hlen = 0;
2099 	int vnet_hdr_sz = 0;
2100 
2101 	if (skb_vlan_tag_present(skb))
2102 		vlan_hlen = VLAN_HLEN;
2103 
2104 	if (tun->flags & IFF_VNET_HDR)
2105 		vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
2106 
2107 	total = skb->len + vlan_hlen + vnet_hdr_sz;
2108 
2109 	if (!(tun->flags & IFF_NO_PI)) {
2110 		if (iov_iter_count(iter) < sizeof(pi))
2111 			return -EINVAL;
2112 
2113 		total += sizeof(pi);
2114 		if (iov_iter_count(iter) < total) {
2115 			/* Packet will be striped */
2116 			pi.flags |= TUN_PKT_STRIP;
2117 		}
2118 
2119 		if (copy_to_iter(&pi, sizeof(pi), iter) != sizeof(pi))
2120 			return -EFAULT;
2121 	}
2122 
2123 	if (vnet_hdr_sz) {
2124 		struct virtio_net_hdr gso;
2125 
2126 		if (iov_iter_count(iter) < vnet_hdr_sz)
2127 			return -EINVAL;
2128 
2129 		if (virtio_net_hdr_from_skb(skb, &gso,
2130 					    tun_is_little_endian(tun), true,
2131 					    vlan_hlen)) {
2132 			struct skb_shared_info *sinfo = skb_shinfo(skb);
2133 
2134 			if (net_ratelimit()) {
2135 				netdev_err(tun->dev, "unexpected GSO type: 0x%x, gso_size %d, hdr_len %d\n",
2136 					   sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
2137 					   tun16_to_cpu(tun, gso.hdr_len));
2138 				print_hex_dump(KERN_ERR, "tun: ",
2139 					       DUMP_PREFIX_NONE,
2140 					       16, 1, skb->head,
2141 					       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
2142 			}
2143 			WARN_ON_ONCE(1);
2144 			return -EINVAL;
2145 		}
2146 
2147 		if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
2148 			return -EFAULT;
2149 
2150 		iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
2151 	}
2152 
2153 	if (vlan_hlen) {
2154 		int ret;
2155 		struct veth veth;
2156 
2157 		veth.h_vlan_proto = skb->vlan_proto;
2158 		veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
2159 
2160 		vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
2161 
2162 		ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
2163 		if (ret || !iov_iter_count(iter))
2164 			goto done;
2165 
2166 		ret = copy_to_iter(&veth, sizeof(veth), iter);
2167 		if (ret != sizeof(veth) || !iov_iter_count(iter))
2168 			goto done;
2169 	}
2170 
2171 	skb_copy_datagram_iter(skb, vlan_offset, iter, skb->len - vlan_offset);
2172 
2173 done:
2174 	/* caller is in process context, */
2175 	preempt_disable();
2176 	dev_sw_netstats_tx_add(tun->dev, 1, skb->len + vlan_hlen);
2177 	preempt_enable();
2178 
2179 	return total;
2180 }
2181 
tun_ring_recv(struct tun_file * tfile,int noblock,int * err)2182 static void *tun_ring_recv(struct tun_file *tfile, int noblock, int *err)
2183 {
2184 	DECLARE_WAITQUEUE(wait, current);
2185 	void *ptr = NULL;
2186 	int error = 0;
2187 
2188 	ptr = ptr_ring_consume(&tfile->tx_ring);
2189 	if (ptr)
2190 		goto out;
2191 	if (noblock) {
2192 		error = -EAGAIN;
2193 		goto out;
2194 	}
2195 
2196 	add_wait_queue(&tfile->socket.wq.wait, &wait);
2197 
2198 	while (1) {
2199 		set_current_state(TASK_INTERRUPTIBLE);
2200 		ptr = ptr_ring_consume(&tfile->tx_ring);
2201 		if (ptr)
2202 			break;
2203 		if (signal_pending(current)) {
2204 			error = -ERESTARTSYS;
2205 			break;
2206 		}
2207 		if (tfile->socket.sk->sk_shutdown & RCV_SHUTDOWN) {
2208 			error = -EFAULT;
2209 			break;
2210 		}
2211 
2212 		schedule();
2213 	}
2214 
2215 	__set_current_state(TASK_RUNNING);
2216 	remove_wait_queue(&tfile->socket.wq.wait, &wait);
2217 
2218 out:
2219 	*err = error;
2220 	return ptr;
2221 }
2222 
tun_do_read(struct tun_struct * tun,struct tun_file * tfile,struct iov_iter * to,int noblock,void * ptr)2223 static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
2224 			   struct iov_iter *to,
2225 			   int noblock, void *ptr)
2226 {
2227 	ssize_t ret;
2228 	int err;
2229 
2230 	if (!iov_iter_count(to)) {
2231 		tun_ptr_free(ptr);
2232 		return 0;
2233 	}
2234 
2235 	if (!ptr) {
2236 		/* Read frames from ring */
2237 		ptr = tun_ring_recv(tfile, noblock, &err);
2238 		if (!ptr)
2239 			return err;
2240 	}
2241 
2242 	if (tun_is_xdp_frame(ptr)) {
2243 		struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
2244 
2245 		ret = tun_put_user_xdp(tun, tfile, xdpf, to);
2246 		xdp_return_frame(xdpf);
2247 	} else {
2248 		struct sk_buff *skb = ptr;
2249 
2250 		ret = tun_put_user(tun, tfile, skb, to);
2251 		if (unlikely(ret < 0))
2252 			kfree_skb(skb);
2253 		else
2254 			consume_skb(skb);
2255 	}
2256 
2257 	return ret;
2258 }
2259 
tun_chr_read_iter(struct kiocb * iocb,struct iov_iter * to)2260 static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
2261 {
2262 	struct file *file = iocb->ki_filp;
2263 	struct tun_file *tfile = file->private_data;
2264 	struct tun_struct *tun = tun_get(tfile);
2265 	ssize_t len = iov_iter_count(to), ret;
2266 	int noblock = 0;
2267 
2268 	if (!tun)
2269 		return -EBADFD;
2270 
2271 	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
2272 		noblock = 1;
2273 
2274 	ret = tun_do_read(tun, tfile, to, noblock, NULL);
2275 	ret = min_t(ssize_t, ret, len);
2276 	if (ret > 0)
2277 		iocb->ki_pos = ret;
2278 	tun_put(tun);
2279 	return ret;
2280 }
2281 
tun_prog_free(struct rcu_head * rcu)2282 static void tun_prog_free(struct rcu_head *rcu)
2283 {
2284 	struct tun_prog *prog = container_of(rcu, struct tun_prog, rcu);
2285 
2286 	bpf_prog_destroy(prog->prog);
2287 	kfree(prog);
2288 }
2289 
__tun_set_ebpf(struct tun_struct * tun,struct tun_prog __rcu ** prog_p,struct bpf_prog * prog)2290 static int __tun_set_ebpf(struct tun_struct *tun,
2291 			  struct tun_prog __rcu **prog_p,
2292 			  struct bpf_prog *prog)
2293 {
2294 	struct tun_prog *old, *new = NULL;
2295 
2296 	if (prog) {
2297 		new = kmalloc(sizeof(*new), GFP_KERNEL);
2298 		if (!new)
2299 			return -ENOMEM;
2300 		new->prog = prog;
2301 	}
2302 
2303 	spin_lock_bh(&tun->lock);
2304 	old = rcu_dereference_protected(*prog_p,
2305 					lockdep_is_held(&tun->lock));
2306 	rcu_assign_pointer(*prog_p, new);
2307 	spin_unlock_bh(&tun->lock);
2308 
2309 	if (old)
2310 		call_rcu(&old->rcu, tun_prog_free);
2311 
2312 	return 0;
2313 }
2314 
tun_free_netdev(struct net_device * dev)2315 static void tun_free_netdev(struct net_device *dev)
2316 {
2317 	struct tun_struct *tun = netdev_priv(dev);
2318 
2319 	BUG_ON(!(list_empty(&tun->disabled)));
2320 
2321 	tun_flow_uninit(tun);
2322 	security_tun_dev_free_security(tun->security);
2323 	__tun_set_ebpf(tun, &tun->steering_prog, NULL);
2324 	__tun_set_ebpf(tun, &tun->filter_prog, NULL);
2325 }
2326 
tun_setup(struct net_device * dev)2327 static void tun_setup(struct net_device *dev)
2328 {
2329 	struct tun_struct *tun = netdev_priv(dev);
2330 
2331 	tun->owner = INVALID_UID;
2332 	tun->group = INVALID_GID;
2333 	tun_default_link_ksettings(dev, &tun->link_ksettings);
2334 
2335 	dev->ethtool_ops = &tun_ethtool_ops;
2336 	dev->needs_free_netdev = true;
2337 	dev->priv_destructor = tun_free_netdev;
2338 	/* We prefer our own queue length */
2339 	dev->tx_queue_len = TUN_READQ_SIZE;
2340 }
2341 
2342 /* Trivial set of netlink ops to allow deleting tun or tap
2343  * device with netlink.
2344  */
tun_validate(struct nlattr * tb[],struct nlattr * data[],struct netlink_ext_ack * extack)2345 static int tun_validate(struct nlattr *tb[], struct nlattr *data[],
2346 			struct netlink_ext_ack *extack)
2347 {
2348 	NL_SET_ERR_MSG(extack,
2349 		       "tun/tap creation via rtnetlink is not supported.");
2350 	return -EOPNOTSUPP;
2351 }
2352 
tun_get_size(const struct net_device * dev)2353 static size_t tun_get_size(const struct net_device *dev)
2354 {
2355 	BUILD_BUG_ON(sizeof(u32) != sizeof(uid_t));
2356 	BUILD_BUG_ON(sizeof(u32) != sizeof(gid_t));
2357 
2358 	return nla_total_size(sizeof(uid_t)) + /* OWNER */
2359 	       nla_total_size(sizeof(gid_t)) + /* GROUP */
2360 	       nla_total_size(sizeof(u8)) + /* TYPE */
2361 	       nla_total_size(sizeof(u8)) + /* PI */
2362 	       nla_total_size(sizeof(u8)) + /* VNET_HDR */
2363 	       nla_total_size(sizeof(u8)) + /* PERSIST */
2364 	       nla_total_size(sizeof(u8)) + /* MULTI_QUEUE */
2365 	       nla_total_size(sizeof(u32)) + /* NUM_QUEUES */
2366 	       nla_total_size(sizeof(u32)) + /* NUM_DISABLED_QUEUES */
2367 	       0;
2368 }
2369 
tun_fill_info(struct sk_buff * skb,const struct net_device * dev)2370 static int tun_fill_info(struct sk_buff *skb, const struct net_device *dev)
2371 {
2372 	struct tun_struct *tun = netdev_priv(dev);
2373 
2374 	if (nla_put_u8(skb, IFLA_TUN_TYPE, tun->flags & TUN_TYPE_MASK))
2375 		goto nla_put_failure;
2376 	if (uid_valid(tun->owner) &&
2377 	    nla_put_u32(skb, IFLA_TUN_OWNER,
2378 			from_kuid_munged(current_user_ns(), tun->owner)))
2379 		goto nla_put_failure;
2380 	if (gid_valid(tun->group) &&
2381 	    nla_put_u32(skb, IFLA_TUN_GROUP,
2382 			from_kgid_munged(current_user_ns(), tun->group)))
2383 		goto nla_put_failure;
2384 	if (nla_put_u8(skb, IFLA_TUN_PI, !(tun->flags & IFF_NO_PI)))
2385 		goto nla_put_failure;
2386 	if (nla_put_u8(skb, IFLA_TUN_VNET_HDR, !!(tun->flags & IFF_VNET_HDR)))
2387 		goto nla_put_failure;
2388 	if (nla_put_u8(skb, IFLA_TUN_PERSIST, !!(tun->flags & IFF_PERSIST)))
2389 		goto nla_put_failure;
2390 	if (nla_put_u8(skb, IFLA_TUN_MULTI_QUEUE,
2391 		       !!(tun->flags & IFF_MULTI_QUEUE)))
2392 		goto nla_put_failure;
2393 	if (tun->flags & IFF_MULTI_QUEUE) {
2394 		if (nla_put_u32(skb, IFLA_TUN_NUM_QUEUES, tun->numqueues))
2395 			goto nla_put_failure;
2396 		if (nla_put_u32(skb, IFLA_TUN_NUM_DISABLED_QUEUES,
2397 				tun->numdisabled))
2398 			goto nla_put_failure;
2399 	}
2400 
2401 	return 0;
2402 
2403 nla_put_failure:
2404 	return -EMSGSIZE;
2405 }
2406 
2407 static struct rtnl_link_ops tun_link_ops __read_mostly = {
2408 	.kind		= DRV_NAME,
2409 	.priv_size	= sizeof(struct tun_struct),
2410 	.setup		= tun_setup,
2411 	.validate	= tun_validate,
2412 	.get_size       = tun_get_size,
2413 	.fill_info      = tun_fill_info,
2414 };
2415 
tun_sock_write_space(struct sock * sk)2416 static void tun_sock_write_space(struct sock *sk)
2417 {
2418 	struct tun_file *tfile;
2419 	wait_queue_head_t *wqueue;
2420 
2421 	if (!sock_writeable(sk))
2422 		return;
2423 
2424 	if (!test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
2425 		return;
2426 
2427 	wqueue = sk_sleep(sk);
2428 	if (wqueue && waitqueue_active(wqueue))
2429 		wake_up_interruptible_sync_poll(wqueue, EPOLLOUT |
2430 						EPOLLWRNORM | EPOLLWRBAND);
2431 
2432 	tfile = container_of(sk, struct tun_file, sk);
2433 	kill_fasync(&tfile->fasync, SIGIO, POLL_OUT);
2434 }
2435 
tun_put_page(struct tun_page * tpage)2436 static void tun_put_page(struct tun_page *tpage)
2437 {
2438 	if (tpage->page)
2439 		__page_frag_cache_drain(tpage->page, tpage->count);
2440 }
2441 
tun_xdp_one(struct tun_struct * tun,struct tun_file * tfile,struct xdp_buff * xdp,int * flush,struct tun_page * tpage)2442 static int tun_xdp_one(struct tun_struct *tun,
2443 		       struct tun_file *tfile,
2444 		       struct xdp_buff *xdp, int *flush,
2445 		       struct tun_page *tpage)
2446 {
2447 	unsigned int datasize = xdp->data_end - xdp->data;
2448 	struct tun_xdp_hdr *hdr = xdp->data_hard_start;
2449 	struct virtio_net_hdr *gso = &hdr->gso;
2450 	struct bpf_prog *xdp_prog;
2451 	struct sk_buff *skb = NULL;
2452 	struct sk_buff_head *queue;
2453 	u32 rxhash = 0, act;
2454 	int buflen = hdr->buflen;
2455 	int ret = 0;
2456 	bool skb_xdp = false;
2457 	struct page *page;
2458 
2459 	if (unlikely(datasize < ETH_HLEN))
2460 		return -EINVAL;
2461 
2462 	xdp_prog = rcu_dereference(tun->xdp_prog);
2463 	if (xdp_prog) {
2464 		if (gso->gso_type) {
2465 			skb_xdp = true;
2466 			goto build;
2467 		}
2468 
2469 		xdp_init_buff(xdp, buflen, &tfile->xdp_rxq);
2470 		xdp_set_data_meta_invalid(xdp);
2471 
2472 		act = bpf_prog_run_xdp(xdp_prog, xdp);
2473 		ret = tun_xdp_act(tun, xdp_prog, xdp, act);
2474 		if (ret < 0) {
2475 			put_page(virt_to_head_page(xdp->data));
2476 			return ret;
2477 		}
2478 
2479 		switch (ret) {
2480 		case XDP_REDIRECT:
2481 			*flush = true;
2482 			fallthrough;
2483 		case XDP_TX:
2484 			return 0;
2485 		case XDP_PASS:
2486 			break;
2487 		default:
2488 			page = virt_to_head_page(xdp->data);
2489 			if (tpage->page == page) {
2490 				++tpage->count;
2491 			} else {
2492 				tun_put_page(tpage);
2493 				tpage->page = page;
2494 				tpage->count = 1;
2495 			}
2496 			return 0;
2497 		}
2498 	}
2499 
2500 build:
2501 	skb = build_skb(xdp->data_hard_start, buflen);
2502 	if (!skb) {
2503 		ret = -ENOMEM;
2504 		goto out;
2505 	}
2506 
2507 	skb_reserve(skb, xdp->data - xdp->data_hard_start);
2508 	skb_put(skb, xdp->data_end - xdp->data);
2509 
2510 	if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) {
2511 		atomic_long_inc(&tun->rx_frame_errors);
2512 		kfree_skb(skb);
2513 		ret = -EINVAL;
2514 		goto out;
2515 	}
2516 
2517 	skb->protocol = eth_type_trans(skb, tun->dev);
2518 	skb_reset_network_header(skb);
2519 	skb_probe_transport_header(skb);
2520 	skb_record_rx_queue(skb, tfile->queue_index);
2521 
2522 	if (skb_xdp) {
2523 		ret = do_xdp_generic(xdp_prog, &skb);
2524 		if (ret != XDP_PASS) {
2525 			ret = 0;
2526 			goto out;
2527 		}
2528 	}
2529 
2530 	if (!rcu_dereference(tun->steering_prog) && tun->numqueues > 1 &&
2531 	    !tfile->detached)
2532 		rxhash = __skb_get_hash_symmetric(skb);
2533 
2534 	if (tfile->napi_enabled) {
2535 		queue = &tfile->sk.sk_write_queue;
2536 		spin_lock(&queue->lock);
2537 
2538 		if (unlikely(tfile->detached)) {
2539 			spin_unlock(&queue->lock);
2540 			kfree_skb(skb);
2541 			return -EBUSY;
2542 		}
2543 
2544 		__skb_queue_tail(queue, skb);
2545 		spin_unlock(&queue->lock);
2546 		ret = 1;
2547 	} else {
2548 		netif_receive_skb(skb);
2549 		ret = 0;
2550 	}
2551 
2552 	/* No need to disable preemption here since this function is
2553 	 * always called with bh disabled
2554 	 */
2555 	dev_sw_netstats_rx_add(tun->dev, datasize);
2556 
2557 	if (rxhash)
2558 		tun_flow_update(tun, rxhash, tfile);
2559 
2560 out:
2561 	return ret;
2562 }
2563 
tun_sendmsg(struct socket * sock,struct msghdr * m,size_t total_len)2564 static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
2565 {
2566 	int ret, i;
2567 	struct tun_file *tfile = container_of(sock, struct tun_file, socket);
2568 	struct tun_struct *tun = tun_get(tfile);
2569 	struct tun_msg_ctl *ctl = m->msg_control;
2570 	struct xdp_buff *xdp;
2571 
2572 	if (!tun)
2573 		return -EBADFD;
2574 
2575 	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
2576 	    ctl && ctl->type == TUN_MSG_PTR) {
2577 		struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
2578 		struct tun_page tpage;
2579 		int n = ctl->num;
2580 		int flush = 0, queued = 0;
2581 
2582 		memset(&tpage, 0, sizeof(tpage));
2583 
2584 		local_bh_disable();
2585 		rcu_read_lock();
2586 		bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
2587 
2588 		for (i = 0; i < n; i++) {
2589 			xdp = &((struct xdp_buff *)ctl->ptr)[i];
2590 			ret = tun_xdp_one(tun, tfile, xdp, &flush, &tpage);
2591 			if (ret > 0)
2592 				queued += ret;
2593 		}
2594 
2595 		if (flush)
2596 			xdp_do_flush();
2597 
2598 		if (tfile->napi_enabled && queued > 0)
2599 			napi_schedule(&tfile->napi);
2600 
2601 		bpf_net_ctx_clear(bpf_net_ctx);
2602 		rcu_read_unlock();
2603 		local_bh_enable();
2604 
2605 		tun_put_page(&tpage);
2606 
2607 		ret = total_len;
2608 		goto out;
2609 	}
2610 
2611 	ret = tun_get_user(tun, tfile, ctl ? ctl->ptr : NULL, &m->msg_iter,
2612 			   m->msg_flags & MSG_DONTWAIT,
2613 			   m->msg_flags & MSG_MORE);
2614 out:
2615 	tun_put(tun);
2616 	return ret;
2617 }
2618 
tun_recvmsg(struct socket * sock,struct msghdr * m,size_t total_len,int flags)2619 static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len,
2620 		       int flags)
2621 {
2622 	struct tun_file *tfile = container_of(sock, struct tun_file, socket);
2623 	struct tun_struct *tun = tun_get(tfile);
2624 	void *ptr = m->msg_control;
2625 	int ret;
2626 
2627 	if (!tun) {
2628 		ret = -EBADFD;
2629 		goto out_free;
2630 	}
2631 
2632 	if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) {
2633 		ret = -EINVAL;
2634 		goto out_put_tun;
2635 	}
2636 	if (flags & MSG_ERRQUEUE) {
2637 		ret = sock_recv_errqueue(sock->sk, m, total_len,
2638 					 SOL_PACKET, TUN_TX_TIMESTAMP);
2639 		goto out;
2640 	}
2641 	ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT, ptr);
2642 	if (ret > (ssize_t)total_len) {
2643 		m->msg_flags |= MSG_TRUNC;
2644 		ret = flags & MSG_TRUNC ? ret : total_len;
2645 	}
2646 out:
2647 	tun_put(tun);
2648 	return ret;
2649 
2650 out_put_tun:
2651 	tun_put(tun);
2652 out_free:
2653 	tun_ptr_free(ptr);
2654 	return ret;
2655 }
2656 
tun_ptr_peek_len(void * ptr)2657 static int tun_ptr_peek_len(void *ptr)
2658 {
2659 	if (likely(ptr)) {
2660 		if (tun_is_xdp_frame(ptr)) {
2661 			struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
2662 
2663 			return xdpf->len;
2664 		}
2665 		return __skb_array_len_with_tag(ptr);
2666 	} else {
2667 		return 0;
2668 	}
2669 }
2670 
tun_peek_len(struct socket * sock)2671 static int tun_peek_len(struct socket *sock)
2672 {
2673 	struct tun_file *tfile = container_of(sock, struct tun_file, socket);
2674 	struct tun_struct *tun;
2675 	int ret = 0;
2676 
2677 	tun = tun_get(tfile);
2678 	if (!tun)
2679 		return 0;
2680 
2681 	ret = PTR_RING_PEEK_CALL(&tfile->tx_ring, tun_ptr_peek_len);
2682 	tun_put(tun);
2683 
2684 	return ret;
2685 }
2686 
2687 /* Ops structure to mimic raw sockets with tun */
2688 static const struct proto_ops tun_socket_ops = {
2689 	.peek_len = tun_peek_len,
2690 	.sendmsg = tun_sendmsg,
2691 	.recvmsg = tun_recvmsg,
2692 };
2693 
2694 static struct proto tun_proto = {
2695 	.name		= "tun",
2696 	.owner		= THIS_MODULE,
2697 	.obj_size	= sizeof(struct tun_file),
2698 };
2699 
tun_flags(struct tun_struct * tun)2700 static int tun_flags(struct tun_struct *tun)
2701 {
2702 	return tun->flags & (TUN_FEATURES | IFF_PERSIST | IFF_TUN | IFF_TAP);
2703 }
2704 
tun_flags_show(struct device * dev,struct device_attribute * attr,char * buf)2705 static ssize_t tun_flags_show(struct device *dev, struct device_attribute *attr,
2706 			      char *buf)
2707 {
2708 	struct tun_struct *tun = netdev_priv(to_net_dev(dev));
2709 	return sysfs_emit(buf, "0x%x\n", tun_flags(tun));
2710 }
2711 
owner_show(struct device * dev,struct device_attribute * attr,char * buf)2712 static ssize_t owner_show(struct device *dev, struct device_attribute *attr,
2713 			  char *buf)
2714 {
2715 	struct tun_struct *tun = netdev_priv(to_net_dev(dev));
2716 	return uid_valid(tun->owner)?
2717 		sysfs_emit(buf, "%u\n",
2718 			   from_kuid_munged(current_user_ns(), tun->owner)) :
2719 		sysfs_emit(buf, "-1\n");
2720 }
2721 
group_show(struct device * dev,struct device_attribute * attr,char * buf)2722 static ssize_t group_show(struct device *dev, struct device_attribute *attr,
2723 			  char *buf)
2724 {
2725 	struct tun_struct *tun = netdev_priv(to_net_dev(dev));
2726 	return gid_valid(tun->group) ?
2727 		sysfs_emit(buf, "%u\n",
2728 			   from_kgid_munged(current_user_ns(), tun->group)) :
2729 		sysfs_emit(buf, "-1\n");
2730 }
2731 
2732 static DEVICE_ATTR_RO(tun_flags);
2733 static DEVICE_ATTR_RO(owner);
2734 static DEVICE_ATTR_RO(group);
2735 
2736 static struct attribute *tun_dev_attrs[] = {
2737 	&dev_attr_tun_flags.attr,
2738 	&dev_attr_owner.attr,
2739 	&dev_attr_group.attr,
2740 	NULL
2741 };
2742 
2743 static const struct attribute_group tun_attr_group = {
2744 	.attrs = tun_dev_attrs
2745 };
2746 
tun_set_iff(struct net * net,struct file * file,struct ifreq * ifr)2747 static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
2748 {
2749 	struct tun_struct *tun;
2750 	struct tun_file *tfile = file->private_data;
2751 	struct net_device *dev;
2752 	int err;
2753 
2754 	if (tfile->detached)
2755 		return -EINVAL;
2756 
2757 	if ((ifr->ifr_flags & IFF_NAPI_FRAGS)) {
2758 		if (!capable(CAP_NET_ADMIN))
2759 			return -EPERM;
2760 
2761 		if (!(ifr->ifr_flags & IFF_NAPI) ||
2762 		    (ifr->ifr_flags & TUN_TYPE_MASK) != IFF_TAP)
2763 			return -EINVAL;
2764 	}
2765 
2766 	dev = __dev_get_by_name(net, ifr->ifr_name);
2767 	if (dev) {
2768 		if (ifr->ifr_flags & IFF_TUN_EXCL)
2769 			return -EBUSY;
2770 		if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
2771 			tun = netdev_priv(dev);
2772 		else if ((ifr->ifr_flags & IFF_TAP) && dev->netdev_ops == &tap_netdev_ops)
2773 			tun = netdev_priv(dev);
2774 		else
2775 			return -EINVAL;
2776 
2777 		if (!!(ifr->ifr_flags & IFF_MULTI_QUEUE) !=
2778 		    !!(tun->flags & IFF_MULTI_QUEUE))
2779 			return -EINVAL;
2780 
2781 		if (tun_not_capable(tun))
2782 			return -EPERM;
2783 		err = security_tun_dev_open(tun->security);
2784 		if (err < 0)
2785 			return err;
2786 
2787 		err = tun_attach(tun, file, ifr->ifr_flags & IFF_NOFILTER,
2788 				 ifr->ifr_flags & IFF_NAPI,
2789 				 ifr->ifr_flags & IFF_NAPI_FRAGS, true);
2790 		if (err < 0)
2791 			return err;
2792 
2793 		if (tun->flags & IFF_MULTI_QUEUE &&
2794 		    (tun->numqueues + tun->numdisabled > 1)) {
2795 			/* One or more queue has already been attached, no need
2796 			 * to initialize the device again.
2797 			 */
2798 			netdev_state_change(dev);
2799 			return 0;
2800 		}
2801 
2802 		tun->flags = (tun->flags & ~TUN_FEATURES) |
2803 			      (ifr->ifr_flags & TUN_FEATURES);
2804 
2805 		netdev_state_change(dev);
2806 	} else {
2807 		char *name;
2808 		unsigned long flags = 0;
2809 		int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ?
2810 			     MAX_TAP_QUEUES : 1;
2811 
2812 		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
2813 			return -EPERM;
2814 		err = security_tun_dev_create();
2815 		if (err < 0)
2816 			return err;
2817 
2818 		/* Set dev type */
2819 		if (ifr->ifr_flags & IFF_TUN) {
2820 			/* TUN device */
2821 			flags |= IFF_TUN;
2822 			name = "tun%d";
2823 		} else if (ifr->ifr_flags & IFF_TAP) {
2824 			/* TAP device */
2825 			flags |= IFF_TAP;
2826 			name = "tap%d";
2827 		} else
2828 			return -EINVAL;
2829 
2830 		if (*ifr->ifr_name)
2831 			name = ifr->ifr_name;
2832 
2833 		dev = alloc_netdev_mqs(sizeof(struct tun_struct), name,
2834 				       NET_NAME_UNKNOWN, tun_setup, queues,
2835 				       queues);
2836 
2837 		if (!dev)
2838 			return -ENOMEM;
2839 
2840 		dev_net_set(dev, net);
2841 		dev->rtnl_link_ops = &tun_link_ops;
2842 		dev->ifindex = tfile->ifindex;
2843 		dev->sysfs_groups[0] = &tun_attr_group;
2844 
2845 		tun = netdev_priv(dev);
2846 		tun->dev = dev;
2847 		tun->flags = flags;
2848 		tun->txflt.count = 0;
2849 		tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
2850 
2851 		tun->align = NET_SKB_PAD;
2852 		tun->filter_attached = false;
2853 		tun->sndbuf = tfile->socket.sk->sk_sndbuf;
2854 		tun->rx_batched = 0;
2855 		RCU_INIT_POINTER(tun->steering_prog, NULL);
2856 
2857 		tun->ifr = ifr;
2858 		tun->file = file;
2859 
2860 		tun_net_initialize(dev);
2861 
2862 		err = register_netdevice(tun->dev);
2863 		if (err < 0) {
2864 			free_netdev(dev);
2865 			return err;
2866 		}
2867 		/* free_netdev() won't check refcnt, to avoid race
2868 		 * with dev_put() we need publish tun after registration.
2869 		 */
2870 		rcu_assign_pointer(tfile->tun, tun);
2871 	}
2872 
2873 	if (ifr->ifr_flags & IFF_NO_CARRIER)
2874 		netif_carrier_off(tun->dev);
2875 	else
2876 		netif_carrier_on(tun->dev);
2877 
2878 	/* Make sure persistent devices do not get stuck in
2879 	 * xoff state.
2880 	 */
2881 	if (netif_running(tun->dev))
2882 		netif_tx_wake_all_queues(tun->dev);
2883 
2884 	strcpy(ifr->ifr_name, tun->dev->name);
2885 	return 0;
2886 }
2887 
tun_get_iff(struct tun_struct * tun,struct ifreq * ifr)2888 static void tun_get_iff(struct tun_struct *tun, struct ifreq *ifr)
2889 {
2890 	strcpy(ifr->ifr_name, tun->dev->name);
2891 
2892 	ifr->ifr_flags = tun_flags(tun);
2893 
2894 }
2895 
2896 /* This is like a cut-down ethtool ops, except done via tun fd so no
2897  * privs required. */
set_offload(struct tun_struct * tun,unsigned long arg)2898 static int set_offload(struct tun_struct *tun, unsigned long arg)
2899 {
2900 	netdev_features_t features = 0;
2901 
2902 	if (arg & TUN_F_CSUM) {
2903 		features |= NETIF_F_HW_CSUM;
2904 		arg &= ~TUN_F_CSUM;
2905 
2906 		if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
2907 			if (arg & TUN_F_TSO_ECN) {
2908 				features |= NETIF_F_TSO_ECN;
2909 				arg &= ~TUN_F_TSO_ECN;
2910 			}
2911 			if (arg & TUN_F_TSO4)
2912 				features |= NETIF_F_TSO;
2913 			if (arg & TUN_F_TSO6)
2914 				features |= NETIF_F_TSO6;
2915 			arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
2916 		}
2917 
2918 		arg &= ~TUN_F_UFO;
2919 
2920 		/* TODO: for now USO4 and USO6 should work simultaneously */
2921 		if (arg & TUN_F_USO4 && arg & TUN_F_USO6) {
2922 			features |= NETIF_F_GSO_UDP_L4;
2923 			arg &= ~(TUN_F_USO4 | TUN_F_USO6);
2924 		}
2925 	}
2926 
2927 	/* This gives the user a way to test for new features in future by
2928 	 * trying to set them. */
2929 	if (arg)
2930 		return -EINVAL;
2931 
2932 	tun->set_features = features;
2933 	tun->dev->wanted_features &= ~TUN_USER_FEATURES;
2934 	tun->dev->wanted_features |= features;
2935 	netdev_update_features(tun->dev);
2936 
2937 	return 0;
2938 }
2939 
tun_detach_filter(struct tun_struct * tun,int n)2940 static void tun_detach_filter(struct tun_struct *tun, int n)
2941 {
2942 	int i;
2943 	struct tun_file *tfile;
2944 
2945 	for (i = 0; i < n; i++) {
2946 		tfile = rtnl_dereference(tun->tfiles[i]);
2947 		lock_sock(tfile->socket.sk);
2948 		sk_detach_filter(tfile->socket.sk);
2949 		release_sock(tfile->socket.sk);
2950 	}
2951 
2952 	tun->filter_attached = false;
2953 }
2954 
tun_attach_filter(struct tun_struct * tun)2955 static int tun_attach_filter(struct tun_struct *tun)
2956 {
2957 	int i, ret = 0;
2958 	struct tun_file *tfile;
2959 
2960 	for (i = 0; i < tun->numqueues; i++) {
2961 		tfile = rtnl_dereference(tun->tfiles[i]);
2962 		lock_sock(tfile->socket.sk);
2963 		ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
2964 		release_sock(tfile->socket.sk);
2965 		if (ret) {
2966 			tun_detach_filter(tun, i);
2967 			return ret;
2968 		}
2969 	}
2970 
2971 	tun->filter_attached = true;
2972 	return ret;
2973 }
2974 
tun_set_sndbuf(struct tun_struct * tun)2975 static void tun_set_sndbuf(struct tun_struct *tun)
2976 {
2977 	struct tun_file *tfile;
2978 	int i;
2979 
2980 	for (i = 0; i < tun->numqueues; i++) {
2981 		tfile = rtnl_dereference(tun->tfiles[i]);
2982 		tfile->socket.sk->sk_sndbuf = tun->sndbuf;
2983 	}
2984 }
2985 
tun_set_queue(struct file * file,struct ifreq * ifr)2986 static int tun_set_queue(struct file *file, struct ifreq *ifr)
2987 {
2988 	struct tun_file *tfile = file->private_data;
2989 	struct tun_struct *tun;
2990 	int ret = 0;
2991 
2992 	rtnl_lock();
2993 
2994 	if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
2995 		tun = tfile->detached;
2996 		if (!tun) {
2997 			ret = -EINVAL;
2998 			goto unlock;
2999 		}
3000 		ret = security_tun_dev_attach_queue(tun->security);
3001 		if (ret < 0)
3002 			goto unlock;
3003 		ret = tun_attach(tun, file, false, tun->flags & IFF_NAPI,
3004 				 tun->flags & IFF_NAPI_FRAGS, true);
3005 	} else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
3006 		tun = rtnl_dereference(tfile->tun);
3007 		if (!tun || !(tun->flags & IFF_MULTI_QUEUE) || tfile->detached)
3008 			ret = -EINVAL;
3009 		else
3010 			__tun_detach(tfile, false);
3011 	} else
3012 		ret = -EINVAL;
3013 
3014 	if (ret >= 0)
3015 		netdev_state_change(tun->dev);
3016 
3017 unlock:
3018 	rtnl_unlock();
3019 	return ret;
3020 }
3021 
tun_set_ebpf(struct tun_struct * tun,struct tun_prog __rcu ** prog_p,void __user * data)3022 static int tun_set_ebpf(struct tun_struct *tun, struct tun_prog __rcu **prog_p,
3023 			void __user *data)
3024 {
3025 	struct bpf_prog *prog;
3026 	int fd;
3027 
3028 	if (copy_from_user(&fd, data, sizeof(fd)))
3029 		return -EFAULT;
3030 
3031 	if (fd == -1) {
3032 		prog = NULL;
3033 	} else {
3034 		prog = bpf_prog_get_type(fd, BPF_PROG_TYPE_SOCKET_FILTER);
3035 		if (IS_ERR(prog))
3036 			return PTR_ERR(prog);
3037 	}
3038 
3039 	return __tun_set_ebpf(tun, prog_p, prog);
3040 }
3041 
3042 /* Return correct value for tun->dev->addr_len based on tun->dev->type. */
tun_get_addr_len(unsigned short type)3043 static unsigned char tun_get_addr_len(unsigned short type)
3044 {
3045 	switch (type) {
3046 	case ARPHRD_IP6GRE:
3047 	case ARPHRD_TUNNEL6:
3048 		return sizeof(struct in6_addr);
3049 	case ARPHRD_IPGRE:
3050 	case ARPHRD_TUNNEL:
3051 	case ARPHRD_SIT:
3052 		return 4;
3053 	case ARPHRD_ETHER:
3054 		return ETH_ALEN;
3055 	case ARPHRD_IEEE802154:
3056 	case ARPHRD_IEEE802154_MONITOR:
3057 		return IEEE802154_EXTENDED_ADDR_LEN;
3058 	case ARPHRD_PHONET_PIPE:
3059 	case ARPHRD_PPP:
3060 	case ARPHRD_NONE:
3061 		return 0;
3062 	case ARPHRD_6LOWPAN:
3063 		return EUI64_ADDR_LEN;
3064 	case ARPHRD_FDDI:
3065 		return FDDI_K_ALEN;
3066 	case ARPHRD_HIPPI:
3067 		return HIPPI_ALEN;
3068 	case ARPHRD_IEEE802:
3069 		return FC_ALEN;
3070 	case ARPHRD_ROSE:
3071 		return ROSE_ADDR_LEN;
3072 	case ARPHRD_NETROM:
3073 		return AX25_ADDR_LEN;
3074 	case ARPHRD_LOCALTLK:
3075 		return LTALK_ALEN;
3076 	default:
3077 		return 0;
3078 	}
3079 }
3080 
__tun_chr_ioctl(struct file * file,unsigned int cmd,unsigned long arg,int ifreq_len)3081 static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
3082 			    unsigned long arg, int ifreq_len)
3083 {
3084 	struct tun_file *tfile = file->private_data;
3085 	struct net *net = sock_net(&tfile->sk);
3086 	struct tun_struct *tun;
3087 	void __user* argp = (void __user*)arg;
3088 	unsigned int carrier;
3089 	struct ifreq ifr;
3090 	kuid_t owner;
3091 	kgid_t group;
3092 	int ifindex;
3093 	int sndbuf;
3094 	int vnet_hdr_sz;
3095 	int le;
3096 	int ret;
3097 	bool do_notify = false;
3098 
3099 	if (cmd == TUNSETIFF || cmd == TUNSETQUEUE ||
3100 	    (_IOC_TYPE(cmd) == SOCK_IOC_TYPE && cmd != SIOCGSKNS)) {
3101 		if (copy_from_user(&ifr, argp, ifreq_len))
3102 			return -EFAULT;
3103 	} else {
3104 		memset(&ifr, 0, sizeof(ifr));
3105 	}
3106 	if (cmd == TUNGETFEATURES) {
3107 		/* Currently this just means: "what IFF flags are valid?".
3108 		 * This is needed because we never checked for invalid flags on
3109 		 * TUNSETIFF.
3110 		 */
3111 		return put_user(IFF_TUN | IFF_TAP | IFF_NO_CARRIER |
3112 				TUN_FEATURES, (unsigned int __user*)argp);
3113 	} else if (cmd == TUNSETQUEUE) {
3114 		return tun_set_queue(file, &ifr);
3115 	} else if (cmd == SIOCGSKNS) {
3116 		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
3117 			return -EPERM;
3118 		return open_related_ns(&net->ns, get_net_ns);
3119 	}
3120 
3121 	rtnl_lock();
3122 
3123 	tun = tun_get(tfile);
3124 	if (cmd == TUNSETIFF) {
3125 		ret = -EEXIST;
3126 		if (tun)
3127 			goto unlock;
3128 
3129 		ifr.ifr_name[IFNAMSIZ-1] = '\0';
3130 
3131 		ret = tun_set_iff(net, file, &ifr);
3132 
3133 		if (ret)
3134 			goto unlock;
3135 
3136 		if (copy_to_user(argp, &ifr, ifreq_len))
3137 			ret = -EFAULT;
3138 		goto unlock;
3139 	}
3140 	if (cmd == TUNSETIFINDEX) {
3141 		ret = -EPERM;
3142 		if (tun)
3143 			goto unlock;
3144 
3145 		ret = -EFAULT;
3146 		if (copy_from_user(&ifindex, argp, sizeof(ifindex)))
3147 			goto unlock;
3148 		ret = -EINVAL;
3149 		if (ifindex < 0)
3150 			goto unlock;
3151 		ret = 0;
3152 		tfile->ifindex = ifindex;
3153 		goto unlock;
3154 	}
3155 
3156 	ret = -EBADFD;
3157 	if (!tun)
3158 		goto unlock;
3159 
3160 	netif_info(tun, drv, tun->dev, "tun_chr_ioctl cmd %u\n", cmd);
3161 
3162 	net = dev_net(tun->dev);
3163 	ret = 0;
3164 	switch (cmd) {
3165 	case TUNGETIFF:
3166 		tun_get_iff(tun, &ifr);
3167 
3168 		if (tfile->detached)
3169 			ifr.ifr_flags |= IFF_DETACH_QUEUE;
3170 		if (!tfile->socket.sk->sk_filter)
3171 			ifr.ifr_flags |= IFF_NOFILTER;
3172 
3173 		if (copy_to_user(argp, &ifr, ifreq_len))
3174 			ret = -EFAULT;
3175 		break;
3176 
3177 	case TUNSETNOCSUM:
3178 		/* Disable/Enable checksum */
3179 
3180 		/* [unimplemented] */
3181 		netif_info(tun, drv, tun->dev, "ignored: set checksum %s\n",
3182 			   arg ? "disabled" : "enabled");
3183 		break;
3184 
3185 	case TUNSETPERSIST:
3186 		/* Disable/Enable persist mode. Keep an extra reference to the
3187 		 * module to prevent the module being unprobed.
3188 		 */
3189 		if (arg && !(tun->flags & IFF_PERSIST)) {
3190 			tun->flags |= IFF_PERSIST;
3191 			__module_get(THIS_MODULE);
3192 			do_notify = true;
3193 		}
3194 		if (!arg && (tun->flags & IFF_PERSIST)) {
3195 			tun->flags &= ~IFF_PERSIST;
3196 			module_put(THIS_MODULE);
3197 			do_notify = true;
3198 		}
3199 
3200 		netif_info(tun, drv, tun->dev, "persist %s\n",
3201 			   arg ? "enabled" : "disabled");
3202 		break;
3203 
3204 	case TUNSETOWNER:
3205 		/* Set owner of the device */
3206 		owner = make_kuid(current_user_ns(), arg);
3207 		if (!uid_valid(owner)) {
3208 			ret = -EINVAL;
3209 			break;
3210 		}
3211 		tun->owner = owner;
3212 		do_notify = true;
3213 		netif_info(tun, drv, tun->dev, "owner set to %u\n",
3214 			   from_kuid(&init_user_ns, tun->owner));
3215 		break;
3216 
3217 	case TUNSETGROUP:
3218 		/* Set group of the device */
3219 		group = make_kgid(current_user_ns(), arg);
3220 		if (!gid_valid(group)) {
3221 			ret = -EINVAL;
3222 			break;
3223 		}
3224 		tun->group = group;
3225 		do_notify = true;
3226 		netif_info(tun, drv, tun->dev, "group set to %u\n",
3227 			   from_kgid(&init_user_ns, tun->group));
3228 		break;
3229 
3230 	case TUNSETLINK:
3231 		/* Only allow setting the type when the interface is down */
3232 		if (tun->dev->flags & IFF_UP) {
3233 			netif_info(tun, drv, tun->dev,
3234 				   "Linktype set failed because interface is up\n");
3235 			ret = -EBUSY;
3236 		} else {
3237 			ret = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE,
3238 						       tun->dev);
3239 			ret = notifier_to_errno(ret);
3240 			if (ret) {
3241 				netif_info(tun, drv, tun->dev,
3242 					   "Refused to change device type\n");
3243 				break;
3244 			}
3245 			tun->dev->type = (int) arg;
3246 			tun->dev->addr_len = tun_get_addr_len(tun->dev->type);
3247 			netif_info(tun, drv, tun->dev, "linktype set to %d\n",
3248 				   tun->dev->type);
3249 			call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE,
3250 						 tun->dev);
3251 		}
3252 		break;
3253 
3254 	case TUNSETDEBUG:
3255 		tun->msg_enable = (u32)arg;
3256 		break;
3257 
3258 	case TUNSETOFFLOAD:
3259 		ret = set_offload(tun, arg);
3260 		break;
3261 
3262 	case TUNSETTXFILTER:
3263 		/* Can be set only for TAPs */
3264 		ret = -EINVAL;
3265 		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
3266 			break;
3267 		ret = update_filter(&tun->txflt, (void __user *)arg);
3268 		break;
3269 
3270 	case SIOCGIFHWADDR:
3271 		/* Get hw address */
3272 		dev_get_mac_address(&ifr.ifr_hwaddr, net, tun->dev->name);
3273 		if (copy_to_user(argp, &ifr, ifreq_len))
3274 			ret = -EFAULT;
3275 		break;
3276 
3277 	case SIOCSIFHWADDR:
3278 		/* Set hw address */
3279 		ret = dev_set_mac_address_user(tun->dev, &ifr.ifr_hwaddr, NULL);
3280 		break;
3281 
3282 	case TUNGETSNDBUF:
3283 		sndbuf = tfile->socket.sk->sk_sndbuf;
3284 		if (copy_to_user(argp, &sndbuf, sizeof(sndbuf)))
3285 			ret = -EFAULT;
3286 		break;
3287 
3288 	case TUNSETSNDBUF:
3289 		if (copy_from_user(&sndbuf, argp, sizeof(sndbuf))) {
3290 			ret = -EFAULT;
3291 			break;
3292 		}
3293 		if (sndbuf <= 0) {
3294 			ret = -EINVAL;
3295 			break;
3296 		}
3297 
3298 		tun->sndbuf = sndbuf;
3299 		tun_set_sndbuf(tun);
3300 		break;
3301 
3302 	case TUNGETVNETHDRSZ:
3303 		vnet_hdr_sz = tun->vnet_hdr_sz;
3304 		if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
3305 			ret = -EFAULT;
3306 		break;
3307 
3308 	case TUNSETVNETHDRSZ:
3309 		if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
3310 			ret = -EFAULT;
3311 			break;
3312 		}
3313 		if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
3314 			ret = -EINVAL;
3315 			break;
3316 		}
3317 
3318 		tun->vnet_hdr_sz = vnet_hdr_sz;
3319 		break;
3320 
3321 	case TUNGETVNETLE:
3322 		le = !!(tun->flags & TUN_VNET_LE);
3323 		if (put_user(le, (int __user *)argp))
3324 			ret = -EFAULT;
3325 		break;
3326 
3327 	case TUNSETVNETLE:
3328 		if (get_user(le, (int __user *)argp)) {
3329 			ret = -EFAULT;
3330 			break;
3331 		}
3332 		if (le)
3333 			tun->flags |= TUN_VNET_LE;
3334 		else
3335 			tun->flags &= ~TUN_VNET_LE;
3336 		break;
3337 
3338 	case TUNGETVNETBE:
3339 		ret = tun_get_vnet_be(tun, argp);
3340 		break;
3341 
3342 	case TUNSETVNETBE:
3343 		ret = tun_set_vnet_be(tun, argp);
3344 		break;
3345 
3346 	case TUNATTACHFILTER:
3347 		/* Can be set only for TAPs */
3348 		ret = -EINVAL;
3349 		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
3350 			break;
3351 		ret = -EFAULT;
3352 		if (copy_from_user(&tun->fprog, argp, sizeof(tun->fprog)))
3353 			break;
3354 
3355 		ret = tun_attach_filter(tun);
3356 		break;
3357 
3358 	case TUNDETACHFILTER:
3359 		/* Can be set only for TAPs */
3360 		ret = -EINVAL;
3361 		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
3362 			break;
3363 		ret = 0;
3364 		tun_detach_filter(tun, tun->numqueues);
3365 		break;
3366 
3367 	case TUNGETFILTER:
3368 		ret = -EINVAL;
3369 		if ((tun->flags & TUN_TYPE_MASK) != IFF_TAP)
3370 			break;
3371 		ret = -EFAULT;
3372 		if (copy_to_user(argp, &tun->fprog, sizeof(tun->fprog)))
3373 			break;
3374 		ret = 0;
3375 		break;
3376 
3377 	case TUNSETSTEERINGEBPF:
3378 		ret = tun_set_ebpf(tun, &tun->steering_prog, argp);
3379 		break;
3380 
3381 	case TUNSETFILTEREBPF:
3382 		ret = tun_set_ebpf(tun, &tun->filter_prog, argp);
3383 		break;
3384 
3385 	case TUNSETCARRIER:
3386 		ret = -EFAULT;
3387 		if (copy_from_user(&carrier, argp, sizeof(carrier)))
3388 			goto unlock;
3389 
3390 		ret = tun_net_change_carrier(tun->dev, (bool)carrier);
3391 		break;
3392 
3393 	case TUNGETDEVNETNS:
3394 		ret = -EPERM;
3395 		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
3396 			goto unlock;
3397 		ret = open_related_ns(&net->ns, get_net_ns);
3398 		break;
3399 
3400 	default:
3401 		ret = -EINVAL;
3402 		break;
3403 	}
3404 
3405 	if (do_notify)
3406 		netdev_state_change(tun->dev);
3407 
3408 unlock:
3409 	rtnl_unlock();
3410 	if (tun)
3411 		tun_put(tun);
3412 	return ret;
3413 }
3414 
tun_chr_ioctl(struct file * file,unsigned int cmd,unsigned long arg)3415 static long tun_chr_ioctl(struct file *file,
3416 			  unsigned int cmd, unsigned long arg)
3417 {
3418 	return __tun_chr_ioctl(file, cmd, arg, sizeof (struct ifreq));
3419 }
3420 
3421 #ifdef CONFIG_COMPAT
tun_chr_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)3422 static long tun_chr_compat_ioctl(struct file *file,
3423 			 unsigned int cmd, unsigned long arg)
3424 {
3425 	switch (cmd) {
3426 	case TUNSETIFF:
3427 	case TUNGETIFF:
3428 	case TUNSETTXFILTER:
3429 	case TUNGETSNDBUF:
3430 	case TUNSETSNDBUF:
3431 	case SIOCGIFHWADDR:
3432 	case SIOCSIFHWADDR:
3433 		arg = (unsigned long)compat_ptr(arg);
3434 		break;
3435 	default:
3436 		arg = (compat_ulong_t)arg;
3437 		break;
3438 	}
3439 
3440 	/*
3441 	 * compat_ifreq is shorter than ifreq, so we must not access beyond
3442 	 * the end of that structure. All fields that are used in this
3443 	 * driver are compatible though, we don't need to convert the
3444 	 * contents.
3445 	 */
3446 	return __tun_chr_ioctl(file, cmd, arg, sizeof(struct compat_ifreq));
3447 }
3448 #endif /* CONFIG_COMPAT */
3449 
tun_chr_fasync(int fd,struct file * file,int on)3450 static int tun_chr_fasync(int fd, struct file *file, int on)
3451 {
3452 	struct tun_file *tfile = file->private_data;
3453 	int ret;
3454 
3455 	if (on) {
3456 		ret = file_f_owner_allocate(file);
3457 		if (ret)
3458 			goto out;
3459 	}
3460 
3461 	if ((ret = fasync_helper(fd, file, on, &tfile->fasync)) < 0)
3462 		goto out;
3463 
3464 	if (on) {
3465 		__f_setown(file, task_pid(current), PIDTYPE_TGID, 0);
3466 		tfile->flags |= TUN_FASYNC;
3467 	} else
3468 		tfile->flags &= ~TUN_FASYNC;
3469 	ret = 0;
3470 out:
3471 	return ret;
3472 }
3473 
tun_chr_open(struct inode * inode,struct file * file)3474 static int tun_chr_open(struct inode *inode, struct file * file)
3475 {
3476 	struct net *net = current->nsproxy->net_ns;
3477 	struct tun_file *tfile;
3478 
3479 	tfile = (struct tun_file *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
3480 					    &tun_proto, 0);
3481 	if (!tfile)
3482 		return -ENOMEM;
3483 	if (ptr_ring_init(&tfile->tx_ring, 0, GFP_KERNEL)) {
3484 		sk_free(&tfile->sk);
3485 		return -ENOMEM;
3486 	}
3487 
3488 	mutex_init(&tfile->napi_mutex);
3489 	RCU_INIT_POINTER(tfile->tun, NULL);
3490 	tfile->flags = 0;
3491 	tfile->ifindex = 0;
3492 
3493 	init_waitqueue_head(&tfile->socket.wq.wait);
3494 
3495 	tfile->socket.file = file;
3496 	tfile->socket.ops = &tun_socket_ops;
3497 
3498 	sock_init_data_uid(&tfile->socket, &tfile->sk, current_fsuid());
3499 
3500 	tfile->sk.sk_write_space = tun_sock_write_space;
3501 	tfile->sk.sk_sndbuf = INT_MAX;
3502 
3503 	file->private_data = tfile;
3504 	INIT_LIST_HEAD(&tfile->next);
3505 
3506 	sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
3507 
3508 	/* tun groks IOCB_NOWAIT just fine, mark it as such */
3509 	file->f_mode |= FMODE_NOWAIT;
3510 	return 0;
3511 }
3512 
tun_chr_close(struct inode * inode,struct file * file)3513 static int tun_chr_close(struct inode *inode, struct file *file)
3514 {
3515 	struct tun_file *tfile = file->private_data;
3516 
3517 	tun_detach(tfile, true);
3518 
3519 	return 0;
3520 }
3521 
3522 #ifdef CONFIG_PROC_FS
tun_chr_show_fdinfo(struct seq_file * m,struct file * file)3523 static void tun_chr_show_fdinfo(struct seq_file *m, struct file *file)
3524 {
3525 	struct tun_file *tfile = file->private_data;
3526 	struct tun_struct *tun;
3527 	struct ifreq ifr;
3528 
3529 	memset(&ifr, 0, sizeof(ifr));
3530 
3531 	rtnl_lock();
3532 	tun = tun_get(tfile);
3533 	if (tun)
3534 		tun_get_iff(tun, &ifr);
3535 	rtnl_unlock();
3536 
3537 	if (tun)
3538 		tun_put(tun);
3539 
3540 	seq_printf(m, "iff:\t%s\n", ifr.ifr_name);
3541 }
3542 #endif
3543 
3544 static const struct file_operations tun_fops = {
3545 	.owner	= THIS_MODULE,
3546 	.read_iter  = tun_chr_read_iter,
3547 	.write_iter = tun_chr_write_iter,
3548 	.poll	= tun_chr_poll,
3549 	.unlocked_ioctl	= tun_chr_ioctl,
3550 #ifdef CONFIG_COMPAT
3551 	.compat_ioctl = tun_chr_compat_ioctl,
3552 #endif
3553 	.open	= tun_chr_open,
3554 	.release = tun_chr_close,
3555 	.fasync = tun_chr_fasync,
3556 #ifdef CONFIG_PROC_FS
3557 	.show_fdinfo = tun_chr_show_fdinfo,
3558 #endif
3559 };
3560 
3561 static struct miscdevice tun_miscdev = {
3562 	.minor = TUN_MINOR,
3563 	.name = "tun",
3564 	.nodename = "net/tun",
3565 	.fops = &tun_fops,
3566 };
3567 
3568 /* ethtool interface */
3569 
tun_default_link_ksettings(struct net_device * dev,struct ethtool_link_ksettings * cmd)3570 static void tun_default_link_ksettings(struct net_device *dev,
3571 				       struct ethtool_link_ksettings *cmd)
3572 {
3573 	ethtool_link_ksettings_zero_link_mode(cmd, supported);
3574 	ethtool_link_ksettings_zero_link_mode(cmd, advertising);
3575 	cmd->base.speed		= SPEED_10000;
3576 	cmd->base.duplex	= DUPLEX_FULL;
3577 	cmd->base.port		= PORT_TP;
3578 	cmd->base.phy_address	= 0;
3579 	cmd->base.autoneg	= AUTONEG_DISABLE;
3580 }
3581 
tun_get_link_ksettings(struct net_device * dev,struct ethtool_link_ksettings * cmd)3582 static int tun_get_link_ksettings(struct net_device *dev,
3583 				  struct ethtool_link_ksettings *cmd)
3584 {
3585 	struct tun_struct *tun = netdev_priv(dev);
3586 
3587 	memcpy(cmd, &tun->link_ksettings, sizeof(*cmd));
3588 	return 0;
3589 }
3590 
tun_set_link_ksettings(struct net_device * dev,const struct ethtool_link_ksettings * cmd)3591 static int tun_set_link_ksettings(struct net_device *dev,
3592 				  const struct ethtool_link_ksettings *cmd)
3593 {
3594 	struct tun_struct *tun = netdev_priv(dev);
3595 
3596 	memcpy(&tun->link_ksettings, cmd, sizeof(*cmd));
3597 	return 0;
3598 }
3599 
tun_get_drvinfo(struct net_device * dev,struct ethtool_drvinfo * info)3600 static void tun_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
3601 {
3602 	struct tun_struct *tun = netdev_priv(dev);
3603 
3604 	strscpy(info->driver, DRV_NAME, sizeof(info->driver));
3605 	strscpy(info->version, DRV_VERSION, sizeof(info->version));
3606 
3607 	switch (tun->flags & TUN_TYPE_MASK) {
3608 	case IFF_TUN:
3609 		strscpy(info->bus_info, "tun", sizeof(info->bus_info));
3610 		break;
3611 	case IFF_TAP:
3612 		strscpy(info->bus_info, "tap", sizeof(info->bus_info));
3613 		break;
3614 	}
3615 }
3616 
tun_get_msglevel(struct net_device * dev)3617 static u32 tun_get_msglevel(struct net_device *dev)
3618 {
3619 	struct tun_struct *tun = netdev_priv(dev);
3620 
3621 	return tun->msg_enable;
3622 }
3623 
tun_set_msglevel(struct net_device * dev,u32 value)3624 static void tun_set_msglevel(struct net_device *dev, u32 value)
3625 {
3626 	struct tun_struct *tun = netdev_priv(dev);
3627 
3628 	tun->msg_enable = value;
3629 }
3630 
tun_get_coalesce(struct net_device * dev,struct ethtool_coalesce * ec,struct kernel_ethtool_coalesce * kernel_coal,struct netlink_ext_ack * extack)3631 static int tun_get_coalesce(struct net_device *dev,
3632 			    struct ethtool_coalesce *ec,
3633 			    struct kernel_ethtool_coalesce *kernel_coal,
3634 			    struct netlink_ext_ack *extack)
3635 {
3636 	struct tun_struct *tun = netdev_priv(dev);
3637 
3638 	ec->rx_max_coalesced_frames = tun->rx_batched;
3639 
3640 	return 0;
3641 }
3642 
tun_set_coalesce(struct net_device * dev,struct ethtool_coalesce * ec,struct kernel_ethtool_coalesce * kernel_coal,struct netlink_ext_ack * extack)3643 static int tun_set_coalesce(struct net_device *dev,
3644 			    struct ethtool_coalesce *ec,
3645 			    struct kernel_ethtool_coalesce *kernel_coal,
3646 			    struct netlink_ext_ack *extack)
3647 {
3648 	struct tun_struct *tun = netdev_priv(dev);
3649 
3650 	if (ec->rx_max_coalesced_frames > NAPI_POLL_WEIGHT)
3651 		tun->rx_batched = NAPI_POLL_WEIGHT;
3652 	else
3653 		tun->rx_batched = ec->rx_max_coalesced_frames;
3654 
3655 	return 0;
3656 }
3657 
tun_get_channels(struct net_device * dev,struct ethtool_channels * channels)3658 static void tun_get_channels(struct net_device *dev,
3659 			     struct ethtool_channels *channels)
3660 {
3661 	struct tun_struct *tun = netdev_priv(dev);
3662 
3663 	channels->combined_count = tun->numqueues;
3664 	channels->max_combined = tun->flags & IFF_MULTI_QUEUE ? MAX_TAP_QUEUES : 1;
3665 }
3666 
3667 static const struct ethtool_ops tun_ethtool_ops = {
3668 	.supported_coalesce_params = ETHTOOL_COALESCE_RX_MAX_FRAMES,
3669 	.get_drvinfo	= tun_get_drvinfo,
3670 	.get_msglevel	= tun_get_msglevel,
3671 	.set_msglevel	= tun_set_msglevel,
3672 	.get_link	= ethtool_op_get_link,
3673 	.get_channels   = tun_get_channels,
3674 	.get_ts_info	= ethtool_op_get_ts_info,
3675 	.get_coalesce   = tun_get_coalesce,
3676 	.set_coalesce   = tun_set_coalesce,
3677 	.get_link_ksettings = tun_get_link_ksettings,
3678 	.set_link_ksettings = tun_set_link_ksettings,
3679 };
3680 
tun_queue_resize(struct tun_struct * tun)3681 static int tun_queue_resize(struct tun_struct *tun)
3682 {
3683 	struct net_device *dev = tun->dev;
3684 	struct tun_file *tfile;
3685 	struct ptr_ring **rings;
3686 	int n = tun->numqueues + tun->numdisabled;
3687 	int ret, i;
3688 
3689 	rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL);
3690 	if (!rings)
3691 		return -ENOMEM;
3692 
3693 	for (i = 0; i < tun->numqueues; i++) {
3694 		tfile = rtnl_dereference(tun->tfiles[i]);
3695 		rings[i] = &tfile->tx_ring;
3696 	}
3697 	list_for_each_entry(tfile, &tun->disabled, next)
3698 		rings[i++] = &tfile->tx_ring;
3699 
3700 	ret = ptr_ring_resize_multiple(rings, n,
3701 				       dev->tx_queue_len, GFP_KERNEL,
3702 				       tun_ptr_free);
3703 
3704 	kfree(rings);
3705 	return ret;
3706 }
3707 
tun_device_event(struct notifier_block * unused,unsigned long event,void * ptr)3708 static int tun_device_event(struct notifier_block *unused,
3709 			    unsigned long event, void *ptr)
3710 {
3711 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
3712 	struct tun_struct *tun = netdev_priv(dev);
3713 	int i;
3714 
3715 	if (dev->rtnl_link_ops != &tun_link_ops)
3716 		return NOTIFY_DONE;
3717 
3718 	switch (event) {
3719 	case NETDEV_CHANGE_TX_QUEUE_LEN:
3720 		if (tun_queue_resize(tun))
3721 			return NOTIFY_BAD;
3722 		break;
3723 	case NETDEV_UP:
3724 		for (i = 0; i < tun->numqueues; i++) {
3725 			struct tun_file *tfile;
3726 
3727 			tfile = rtnl_dereference(tun->tfiles[i]);
3728 			tfile->socket.sk->sk_write_space(tfile->socket.sk);
3729 		}
3730 		break;
3731 	default:
3732 		break;
3733 	}
3734 
3735 	return NOTIFY_DONE;
3736 }
3737 
3738 static struct notifier_block tun_notifier_block __read_mostly = {
3739 	.notifier_call	= tun_device_event,
3740 };
3741 
tun_init(void)3742 static int __init tun_init(void)
3743 {
3744 	int ret = 0;
3745 
3746 	pr_info("%s, %s\n", DRV_DESCRIPTION, DRV_VERSION);
3747 
3748 	ret = rtnl_link_register(&tun_link_ops);
3749 	if (ret) {
3750 		pr_err("Can't register link_ops\n");
3751 		goto err_linkops;
3752 	}
3753 
3754 	ret = misc_register(&tun_miscdev);
3755 	if (ret) {
3756 		pr_err("Can't register misc device %d\n", TUN_MINOR);
3757 		goto err_misc;
3758 	}
3759 
3760 	ret = register_netdevice_notifier(&tun_notifier_block);
3761 	if (ret) {
3762 		pr_err("Can't register netdevice notifier\n");
3763 		goto err_notifier;
3764 	}
3765 
3766 	return  0;
3767 
3768 err_notifier:
3769 	misc_deregister(&tun_miscdev);
3770 err_misc:
3771 	rtnl_link_unregister(&tun_link_ops);
3772 err_linkops:
3773 	return ret;
3774 }
3775 
tun_cleanup(void)3776 static void __exit tun_cleanup(void)
3777 {
3778 	misc_deregister(&tun_miscdev);
3779 	rtnl_link_unregister(&tun_link_ops);
3780 	unregister_netdevice_notifier(&tun_notifier_block);
3781 }
3782 
3783 /* Get an underlying socket object from tun file.  Returns error unless file is
3784  * attached to a device.  The returned object works like a packet socket, it
3785  * can be used for sock_sendmsg/sock_recvmsg.  The caller is responsible for
3786  * holding a reference to the file for as long as the socket is in use. */
tun_get_socket(struct file * file)3787 struct socket *tun_get_socket(struct file *file)
3788 {
3789 	struct tun_file *tfile;
3790 	if (file->f_op != &tun_fops)
3791 		return ERR_PTR(-EINVAL);
3792 	tfile = file->private_data;
3793 	if (!tfile)
3794 		return ERR_PTR(-EBADFD);
3795 	return &tfile->socket;
3796 }
3797 EXPORT_SYMBOL_GPL(tun_get_socket);
3798 
tun_get_tx_ring(struct file * file)3799 struct ptr_ring *tun_get_tx_ring(struct file *file)
3800 {
3801 	struct tun_file *tfile;
3802 
3803 	if (file->f_op != &tun_fops)
3804 		return ERR_PTR(-EINVAL);
3805 	tfile = file->private_data;
3806 	if (!tfile)
3807 		return ERR_PTR(-EBADFD);
3808 	return &tfile->tx_ring;
3809 }
3810 EXPORT_SYMBOL_GPL(tun_get_tx_ring);
3811 
3812 module_init(tun_init);
3813 module_exit(tun_cleanup);
3814 MODULE_DESCRIPTION(DRV_DESCRIPTION);
3815 MODULE_AUTHOR(DRV_COPYRIGHT);
3816 MODULE_LICENSE("GPL");
3817 MODULE_ALIAS_MISCDEV(TUN_MINOR);
3818 MODULE_ALIAS("devname:net/tun");
3819