1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
3  */
4 
5 /* Devmaps primary use is as a backend map for XDP BPF helper call
6  * bpf_redirect_map(). Because XDP is mostly concerned with performance we
7  * spent some effort to ensure the datapath with redirect maps does not use
8  * any locking. This is a quick note on the details.
9  *
10  * We have three possible paths to get into the devmap control plane bpf
11  * syscalls, bpf programs, and driver side xmit/flush operations. A bpf syscall
12  * will invoke an update, delete, or lookup operation. To ensure updates and
13  * deletes appear atomic from the datapath side xchg() is used to modify the
14  * netdev_map array. Then because the datapath does a lookup into the netdev_map
15  * array (read-only) from an RCU critical section we use call_rcu() to wait for
16  * an rcu grace period before free'ing the old data structures. This ensures the
17  * datapath always has a valid copy. However, the datapath does a "flush"
18  * operation that pushes any pending packets in the driver outside the RCU
19  * critical section. Each bpf_dtab_netdev tracks these pending operations using
20  * a per-cpu flush list. The bpf_dtab_netdev object will not be destroyed  until
21  * this list is empty, indicating outstanding flush operations have completed.
22  *
23  * BPF syscalls may race with BPF program calls on any of the update, delete
24  * or lookup operations. As noted above the xchg() operation also keep the
25  * netdev_map consistent in this case. From the devmap side BPF programs
26  * calling into these operations are the same as multiple user space threads
27  * making system calls.
28  *
29  * Finally, any of the above may race with a netdev_unregister notifier. The
30  * unregister notifier must search for net devices in the map structure that
31  * contain a reference to the net device and remove them. This is a two step
32  * process (a) dereference the bpf_dtab_netdev object in netdev_map and (b)
33  * check to see if the ifindex is the same as the net_device being removed.
34  * When removing the dev a cmpxchg() is used to ensure the correct dev is
35  * removed, in the case of a concurrent update or delete operation it is
36  * possible that the initially referenced dev is no longer in the map. As the
37  * notifier hook walks the map we know that new dev references can not be
38  * added by the user because core infrastructure ensures dev_get_by_index()
39  * calls will fail at this point.
40  *
41  * The devmap_hash type is a map type which interprets keys as ifindexes and
42  * indexes these using a hashmap. This allows maps that use ifindex as key to be
43  * densely packed instead of having holes in the lookup array for unused
44  * ifindexes. The setup and packet enqueue/send code is shared between the two
45  * types of devmap; only the lookup and insertion is different.
46  */
47 #include <linux/bpf.h>
48 #include <net/xdp.h>
49 #include <linux/filter.h>
50 #include <trace/events/xdp.h>
51 #include <linux/btf_ids.h>
52 
53 #define DEV_CREATE_FLAG_MASK \
54 	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
55 
56 struct xdp_dev_bulk_queue {
57 	struct xdp_frame *q[DEV_MAP_BULK_SIZE];
58 	struct list_head flush_node;
59 	struct net_device *dev;
60 	struct net_device *dev_rx;
61 	struct bpf_prog *xdp_prog;
62 	unsigned int count;
63 };
64 
65 struct bpf_dtab_netdev {
66 	struct net_device *dev; /* must be first member, due to tracepoint */
67 	struct hlist_node index_hlist;
68 	struct bpf_prog *xdp_prog;
69 	struct rcu_head rcu;
70 	unsigned int idx;
71 	struct bpf_devmap_val val;
72 };
73 
74 struct bpf_dtab {
75 	struct bpf_map map;
76 	struct bpf_dtab_netdev __rcu **netdev_map; /* DEVMAP type only */
77 	struct list_head list;
78 
79 	/* these are only used for DEVMAP_HASH type maps */
80 	struct hlist_head *dev_index_head;
81 	spinlock_t index_lock;
82 	unsigned int items;
83 	u32 n_buckets;
84 };
85 
86 static DEFINE_PER_CPU(struct list_head, dev_flush_list);
87 static DEFINE_SPINLOCK(dev_map_lock);
88 static LIST_HEAD(dev_map_list);
89 
dev_map_create_hash(unsigned int entries,int numa_node)90 static struct hlist_head *dev_map_create_hash(unsigned int entries,
91 					      int numa_node)
92 {
93 	int i;
94 	struct hlist_head *hash;
95 
96 	hash = bpf_map_area_alloc((u64) entries * sizeof(*hash), numa_node);
97 	if (hash != NULL)
98 		for (i = 0; i < entries; i++)
99 			INIT_HLIST_HEAD(&hash[i]);
100 
101 	return hash;
102 }
103 
dev_map_index_hash(struct bpf_dtab * dtab,int idx)104 static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
105 						    int idx)
106 {
107 	return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
108 }
109 
dev_map_init_map(struct bpf_dtab * dtab,union bpf_attr * attr)110 static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
111 {
112 	u32 valsize = attr->value_size;
113 
114 	/* check sanity of attributes. 2 value sizes supported:
115 	 * 4 bytes: ifindex
116 	 * 8 bytes: ifindex + prog fd
117 	 */
118 	if (attr->max_entries == 0 || attr->key_size != 4 ||
119 	    (valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
120 	     valsize != offsetofend(struct bpf_devmap_val, bpf_prog.fd)) ||
121 	    attr->map_flags & ~DEV_CREATE_FLAG_MASK)
122 		return -EINVAL;
123 
124 	/* Lookup returns a pointer straight to dev->ifindex, so make sure the
125 	 * verifier prevents writes from the BPF side
126 	 */
127 	attr->map_flags |= BPF_F_RDONLY_PROG;
128 
129 
130 	bpf_map_init_from_attr(&dtab->map, attr);
131 
132 	if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
133 		dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
134 
135 		if (!dtab->n_buckets) /* Overflow check */
136 			return -EINVAL;
137 	}
138 
139 	if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
140 		dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
141 							   dtab->map.numa_node);
142 		if (!dtab->dev_index_head)
143 			return -ENOMEM;
144 
145 		spin_lock_init(&dtab->index_lock);
146 	} else {
147 		dtab->netdev_map = bpf_map_area_alloc((u64) dtab->map.max_entries *
148 						      sizeof(struct bpf_dtab_netdev *),
149 						      dtab->map.numa_node);
150 		if (!dtab->netdev_map)
151 			return -ENOMEM;
152 	}
153 
154 	return 0;
155 }
156 
dev_map_alloc(union bpf_attr * attr)157 static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
158 {
159 	struct bpf_dtab *dtab;
160 	int err;
161 
162 	dtab = bpf_map_area_alloc(sizeof(*dtab), NUMA_NO_NODE);
163 	if (!dtab)
164 		return ERR_PTR(-ENOMEM);
165 
166 	err = dev_map_init_map(dtab, attr);
167 	if (err) {
168 		bpf_map_area_free(dtab);
169 		return ERR_PTR(err);
170 	}
171 
172 	spin_lock(&dev_map_lock);
173 	list_add_tail_rcu(&dtab->list, &dev_map_list);
174 	spin_unlock(&dev_map_lock);
175 
176 	return &dtab->map;
177 }
178 
dev_map_free(struct bpf_map * map)179 static void dev_map_free(struct bpf_map *map)
180 {
181 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
182 	int i;
183 
184 	/* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
185 	 * so the programs (can be more than one that used this map) were
186 	 * disconnected from events. The following synchronize_rcu() guarantees
187 	 * both rcu read critical sections complete and waits for
188 	 * preempt-disable regions (NAPI being the relevant context here) so we
189 	 * are certain there will be no further reads against the netdev_map and
190 	 * all flush operations are complete. Flush operations can only be done
191 	 * from NAPI context for this reason.
192 	 */
193 
194 	spin_lock(&dev_map_lock);
195 	list_del_rcu(&dtab->list);
196 	spin_unlock(&dev_map_lock);
197 
198 	bpf_clear_redirect_map(map);
199 	synchronize_rcu();
200 
201 	/* Make sure prior __dev_map_entry_free() have completed. */
202 	rcu_barrier();
203 
204 	if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
205 		for (i = 0; i < dtab->n_buckets; i++) {
206 			struct bpf_dtab_netdev *dev;
207 			struct hlist_head *head;
208 			struct hlist_node *next;
209 
210 			head = dev_map_index_hash(dtab, i);
211 
212 			hlist_for_each_entry_safe(dev, next, head, index_hlist) {
213 				hlist_del_rcu(&dev->index_hlist);
214 				if (dev->xdp_prog)
215 					bpf_prog_put(dev->xdp_prog);
216 				dev_put(dev->dev);
217 				kfree(dev);
218 			}
219 		}
220 
221 		bpf_map_area_free(dtab->dev_index_head);
222 	} else {
223 		for (i = 0; i < dtab->map.max_entries; i++) {
224 			struct bpf_dtab_netdev *dev;
225 
226 			dev = rcu_dereference_raw(dtab->netdev_map[i]);
227 			if (!dev)
228 				continue;
229 
230 			if (dev->xdp_prog)
231 				bpf_prog_put(dev->xdp_prog);
232 			dev_put(dev->dev);
233 			kfree(dev);
234 		}
235 
236 		bpf_map_area_free(dtab->netdev_map);
237 	}
238 
239 	bpf_map_area_free(dtab);
240 }
241 
dev_map_get_next_key(struct bpf_map * map,void * key,void * next_key)242 static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
243 {
244 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
245 	u32 index = key ? *(u32 *)key : U32_MAX;
246 	u32 *next = next_key;
247 
248 	if (index >= dtab->map.max_entries) {
249 		*next = 0;
250 		return 0;
251 	}
252 
253 	if (index == dtab->map.max_entries - 1)
254 		return -ENOENT;
255 	*next = index + 1;
256 	return 0;
257 }
258 
259 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
260  * by local_bh_disable() (from XDP calls inside NAPI). The
261  * rcu_read_lock_bh_held() below makes lockdep accept both.
262  */
__dev_map_hash_lookup_elem(struct bpf_map * map,u32 key)263 static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
264 {
265 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
266 	struct hlist_head *head = dev_map_index_hash(dtab, key);
267 	struct bpf_dtab_netdev *dev;
268 
269 	hlist_for_each_entry_rcu(dev, head, index_hlist,
270 				 lockdep_is_held(&dtab->index_lock))
271 		if (dev->idx == key)
272 			return dev;
273 
274 	return NULL;
275 }
276 
dev_map_hash_get_next_key(struct bpf_map * map,void * key,void * next_key)277 static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
278 				    void *next_key)
279 {
280 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
281 	u32 idx, *next = next_key;
282 	struct bpf_dtab_netdev *dev, *next_dev;
283 	struct hlist_head *head;
284 	int i = 0;
285 
286 	if (!key)
287 		goto find_first;
288 
289 	idx = *(u32 *)key;
290 
291 	dev = __dev_map_hash_lookup_elem(map, idx);
292 	if (!dev)
293 		goto find_first;
294 
295 	next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
296 				    struct bpf_dtab_netdev, index_hlist);
297 
298 	if (next_dev) {
299 		*next = next_dev->idx;
300 		return 0;
301 	}
302 
303 	i = idx & (dtab->n_buckets - 1);
304 	i++;
305 
306  find_first:
307 	for (; i < dtab->n_buckets; i++) {
308 		head = dev_map_index_hash(dtab, i);
309 
310 		next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
311 					    struct bpf_dtab_netdev,
312 					    index_hlist);
313 		if (next_dev) {
314 			*next = next_dev->idx;
315 			return 0;
316 		}
317 	}
318 
319 	return -ENOENT;
320 }
321 
dev_map_bpf_prog_run(struct bpf_prog * xdp_prog,struct xdp_frame ** frames,int n,struct net_device * dev)322 static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
323 				struct xdp_frame **frames, int n,
324 				struct net_device *dev)
325 {
326 	struct xdp_txq_info txq = { .dev = dev };
327 	struct xdp_buff xdp;
328 	int i, nframes = 0;
329 
330 	for (i = 0; i < n; i++) {
331 		struct xdp_frame *xdpf = frames[i];
332 		u32 act;
333 		int err;
334 
335 		xdp_convert_frame_to_buff(xdpf, &xdp);
336 		xdp.txq = &txq;
337 
338 		act = bpf_prog_run_xdp(xdp_prog, &xdp);
339 		switch (act) {
340 		case XDP_PASS:
341 			err = xdp_update_frame_from_buff(&xdp, xdpf);
342 			if (unlikely(err < 0))
343 				xdp_return_frame_rx_napi(xdpf);
344 			else
345 				frames[nframes++] = xdpf;
346 			break;
347 		default:
348 			bpf_warn_invalid_xdp_action(NULL, xdp_prog, act);
349 			fallthrough;
350 		case XDP_ABORTED:
351 			trace_xdp_exception(dev, xdp_prog, act);
352 			fallthrough;
353 		case XDP_DROP:
354 			xdp_return_frame_rx_napi(xdpf);
355 			break;
356 		}
357 	}
358 	return nframes; /* sent frames count */
359 }
360 
bq_xmit_all(struct xdp_dev_bulk_queue * bq,u32 flags)361 static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
362 {
363 	struct net_device *dev = bq->dev;
364 	unsigned int cnt = bq->count;
365 	int sent = 0, err = 0;
366 	int to_send = cnt;
367 	int i;
368 
369 	if (unlikely(!cnt))
370 		return;
371 
372 	for (i = 0; i < cnt; i++) {
373 		struct xdp_frame *xdpf = bq->q[i];
374 
375 		prefetch(xdpf);
376 	}
377 
378 	if (bq->xdp_prog) {
379 		to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
380 		if (!to_send)
381 			goto out;
382 	}
383 
384 	sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
385 	if (sent < 0) {
386 		/* If ndo_xdp_xmit fails with an errno, no frames have
387 		 * been xmit'ed.
388 		 */
389 		err = sent;
390 		sent = 0;
391 	}
392 
393 	/* If not all frames have been transmitted, it is our
394 	 * responsibility to free them
395 	 */
396 	for (i = sent; unlikely(i < to_send); i++)
397 		xdp_return_frame_rx_napi(bq->q[i]);
398 
399 out:
400 	bq->count = 0;
401 	trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
402 }
403 
404 /* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
405  * driver before returning from its napi->poll() routine. See the comment above
406  * xdp_do_flush() in filter.c.
407  */
__dev_flush(void)408 void __dev_flush(void)
409 {
410 	struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
411 	struct xdp_dev_bulk_queue *bq, *tmp;
412 
413 	list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
414 		bq_xmit_all(bq, XDP_XMIT_FLUSH);
415 		bq->dev_rx = NULL;
416 		bq->xdp_prog = NULL;
417 		__list_del_clearprev(&bq->flush_node);
418 	}
419 }
420 
421 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
422  * by local_bh_disable() (from XDP calls inside NAPI). The
423  * rcu_read_lock_bh_held() below makes lockdep accept both.
424  */
__dev_map_lookup_elem(struct bpf_map * map,u32 key)425 static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
426 {
427 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
428 	struct bpf_dtab_netdev *obj;
429 
430 	if (key >= map->max_entries)
431 		return NULL;
432 
433 	obj = rcu_dereference_check(dtab->netdev_map[key],
434 				    rcu_read_lock_bh_held());
435 	return obj;
436 }
437 
438 /* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
439  * variable access, and map elements stick around. See comment above
440  * xdp_do_flush() in filter.c.
441  */
bq_enqueue(struct net_device * dev,struct xdp_frame * xdpf,struct net_device * dev_rx,struct bpf_prog * xdp_prog)442 static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
443 		       struct net_device *dev_rx, struct bpf_prog *xdp_prog)
444 {
445 	struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
446 	struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
447 
448 	if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
449 		bq_xmit_all(bq, 0);
450 
451 	/* Ingress dev_rx will be the same for all xdp_frame's in
452 	 * bulk_queue, because bq stored per-CPU and must be flushed
453 	 * from net_device drivers NAPI func end.
454 	 *
455 	 * Do the same with xdp_prog and flush_list since these fields
456 	 * are only ever modified together.
457 	 */
458 	if (!bq->dev_rx) {
459 		bq->dev_rx = dev_rx;
460 		bq->xdp_prog = xdp_prog;
461 		list_add(&bq->flush_node, flush_list);
462 	}
463 
464 	bq->q[bq->count++] = xdpf;
465 }
466 
__xdp_enqueue(struct net_device * dev,struct xdp_frame * xdpf,struct net_device * dev_rx,struct bpf_prog * xdp_prog)467 static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
468 				struct net_device *dev_rx,
469 				struct bpf_prog *xdp_prog)
470 {
471 	int err;
472 
473 	if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
474 		return -EOPNOTSUPP;
475 
476 	if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
477 		     xdp_frame_has_frags(xdpf)))
478 		return -EOPNOTSUPP;
479 
480 	err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
481 	if (unlikely(err))
482 		return err;
483 
484 	bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
485 	return 0;
486 }
487 
dev_map_bpf_prog_run_skb(struct sk_buff * skb,struct bpf_dtab_netdev * dst)488 static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
489 {
490 	struct xdp_txq_info txq = { .dev = dst->dev };
491 	struct xdp_buff xdp;
492 	u32 act;
493 
494 	if (!dst->xdp_prog)
495 		return XDP_PASS;
496 
497 	__skb_pull(skb, skb->mac_len);
498 	xdp.txq = &txq;
499 
500 	act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
501 	switch (act) {
502 	case XDP_PASS:
503 		__skb_push(skb, skb->mac_len);
504 		break;
505 	default:
506 		bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
507 		fallthrough;
508 	case XDP_ABORTED:
509 		trace_xdp_exception(dst->dev, dst->xdp_prog, act);
510 		fallthrough;
511 	case XDP_DROP:
512 		kfree_skb(skb);
513 		break;
514 	}
515 
516 	return act;
517 }
518 
dev_xdp_enqueue(struct net_device * dev,struct xdp_frame * xdpf,struct net_device * dev_rx)519 int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
520 		    struct net_device *dev_rx)
521 {
522 	return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
523 }
524 
dev_map_enqueue(struct bpf_dtab_netdev * dst,struct xdp_frame * xdpf,struct net_device * dev_rx)525 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
526 		    struct net_device *dev_rx)
527 {
528 	struct net_device *dev = dst->dev;
529 
530 	return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
531 }
532 
is_valid_dst(struct bpf_dtab_netdev * obj,struct xdp_frame * xdpf)533 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
534 {
535 	if (!obj)
536 		return false;
537 
538 	if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
539 		return false;
540 
541 	if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
542 		     xdp_frame_has_frags(xdpf)))
543 		return false;
544 
545 	if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
546 		return false;
547 
548 	return true;
549 }
550 
dev_map_enqueue_clone(struct bpf_dtab_netdev * obj,struct net_device * dev_rx,struct xdp_frame * xdpf)551 static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
552 				 struct net_device *dev_rx,
553 				 struct xdp_frame *xdpf)
554 {
555 	struct xdp_frame *nxdpf;
556 
557 	nxdpf = xdpf_clone(xdpf);
558 	if (!nxdpf)
559 		return -ENOMEM;
560 
561 	bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
562 
563 	return 0;
564 }
565 
is_ifindex_excluded(int * excluded,int num_excluded,int ifindex)566 static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
567 {
568 	while (num_excluded--) {
569 		if (ifindex == excluded[num_excluded])
570 			return true;
571 	}
572 	return false;
573 }
574 
575 /* Get ifindex of each upper device. 'indexes' must be able to hold at
576  * least MAX_NEST_DEV elements.
577  * Returns the number of ifindexes added.
578  */
get_upper_ifindexes(struct net_device * dev,int * indexes)579 static int get_upper_ifindexes(struct net_device *dev, int *indexes)
580 {
581 	struct net_device *upper;
582 	struct list_head *iter;
583 	int n = 0;
584 
585 	netdev_for_each_upper_dev_rcu(dev, upper, iter) {
586 		indexes[n++] = upper->ifindex;
587 	}
588 	return n;
589 }
590 
dev_map_enqueue_multi(struct xdp_frame * xdpf,struct net_device * dev_rx,struct bpf_map * map,bool exclude_ingress)591 int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
592 			  struct bpf_map *map, bool exclude_ingress)
593 {
594 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
595 	struct bpf_dtab_netdev *dst, *last_dst = NULL;
596 	int excluded_devices[1+MAX_NEST_DEV];
597 	struct hlist_head *head;
598 	int num_excluded = 0;
599 	unsigned int i;
600 	int err;
601 
602 	if (exclude_ingress) {
603 		num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
604 		excluded_devices[num_excluded++] = dev_rx->ifindex;
605 	}
606 
607 	if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
608 		for (i = 0; i < map->max_entries; i++) {
609 			dst = rcu_dereference_check(dtab->netdev_map[i],
610 						    rcu_read_lock_bh_held());
611 			if (!is_valid_dst(dst, xdpf))
612 				continue;
613 
614 			if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
615 				continue;
616 
617 			/* we only need n-1 clones; last_dst enqueued below */
618 			if (!last_dst) {
619 				last_dst = dst;
620 				continue;
621 			}
622 
623 			err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
624 			if (err)
625 				return err;
626 
627 			last_dst = dst;
628 		}
629 	} else { /* BPF_MAP_TYPE_DEVMAP_HASH */
630 		for (i = 0; i < dtab->n_buckets; i++) {
631 			head = dev_map_index_hash(dtab, i);
632 			hlist_for_each_entry_rcu(dst, head, index_hlist,
633 						 lockdep_is_held(&dtab->index_lock)) {
634 				if (!is_valid_dst(dst, xdpf))
635 					continue;
636 
637 				if (is_ifindex_excluded(excluded_devices, num_excluded,
638 							dst->dev->ifindex))
639 					continue;
640 
641 				/* we only need n-1 clones; last_dst enqueued below */
642 				if (!last_dst) {
643 					last_dst = dst;
644 					continue;
645 				}
646 
647 				err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
648 				if (err)
649 					return err;
650 
651 				last_dst = dst;
652 			}
653 		}
654 	}
655 
656 	/* consume the last copy of the frame */
657 	if (last_dst)
658 		bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
659 	else
660 		xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
661 
662 	return 0;
663 }
664 
dev_map_generic_redirect(struct bpf_dtab_netdev * dst,struct sk_buff * skb,struct bpf_prog * xdp_prog)665 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
666 			     struct bpf_prog *xdp_prog)
667 {
668 	int err;
669 
670 	err = xdp_ok_fwd_dev(dst->dev, skb->len);
671 	if (unlikely(err))
672 		return err;
673 
674 	/* Redirect has already succeeded semantically at this point, so we just
675 	 * return 0 even if packet is dropped. Helper below takes care of
676 	 * freeing skb.
677 	 */
678 	if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
679 		return 0;
680 
681 	skb->dev = dst->dev;
682 	generic_xdp_tx(skb, xdp_prog);
683 
684 	return 0;
685 }
686 
dev_map_redirect_clone(struct bpf_dtab_netdev * dst,struct sk_buff * skb,struct bpf_prog * xdp_prog)687 static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
688 				  struct sk_buff *skb,
689 				  struct bpf_prog *xdp_prog)
690 {
691 	struct sk_buff *nskb;
692 	int err;
693 
694 	nskb = skb_clone(skb, GFP_ATOMIC);
695 	if (!nskb)
696 		return -ENOMEM;
697 
698 	err = dev_map_generic_redirect(dst, nskb, xdp_prog);
699 	if (unlikely(err)) {
700 		consume_skb(nskb);
701 		return err;
702 	}
703 
704 	return 0;
705 }
706 
dev_map_redirect_multi(struct net_device * dev,struct sk_buff * skb,struct bpf_prog * xdp_prog,struct bpf_map * map,bool exclude_ingress)707 int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
708 			   struct bpf_prog *xdp_prog, struct bpf_map *map,
709 			   bool exclude_ingress)
710 {
711 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
712 	struct bpf_dtab_netdev *dst, *last_dst = NULL;
713 	int excluded_devices[1+MAX_NEST_DEV];
714 	struct hlist_head *head;
715 	struct hlist_node *next;
716 	int num_excluded = 0;
717 	unsigned int i;
718 	int err;
719 
720 	if (exclude_ingress) {
721 		num_excluded = get_upper_ifindexes(dev, excluded_devices);
722 		excluded_devices[num_excluded++] = dev->ifindex;
723 	}
724 
725 	if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
726 		for (i = 0; i < map->max_entries; i++) {
727 			dst = rcu_dereference_check(dtab->netdev_map[i],
728 						    rcu_read_lock_bh_held());
729 			if (!dst)
730 				continue;
731 
732 			if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
733 				continue;
734 
735 			/* we only need n-1 clones; last_dst enqueued below */
736 			if (!last_dst) {
737 				last_dst = dst;
738 				continue;
739 			}
740 
741 			err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
742 			if (err)
743 				return err;
744 
745 			last_dst = dst;
746 
747 		}
748 	} else { /* BPF_MAP_TYPE_DEVMAP_HASH */
749 		for (i = 0; i < dtab->n_buckets; i++) {
750 			head = dev_map_index_hash(dtab, i);
751 			hlist_for_each_entry_safe(dst, next, head, index_hlist) {
752 				if (!dst)
753 					continue;
754 
755 				if (is_ifindex_excluded(excluded_devices, num_excluded,
756 							dst->dev->ifindex))
757 					continue;
758 
759 				/* we only need n-1 clones; last_dst enqueued below */
760 				if (!last_dst) {
761 					last_dst = dst;
762 					continue;
763 				}
764 
765 				err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
766 				if (err)
767 					return err;
768 
769 				last_dst = dst;
770 			}
771 		}
772 	}
773 
774 	/* consume the first skb and return */
775 	if (last_dst)
776 		return dev_map_generic_redirect(last_dst, skb, xdp_prog);
777 
778 	/* dtab is empty */
779 	consume_skb(skb);
780 	return 0;
781 }
782 
dev_map_lookup_elem(struct bpf_map * map,void * key)783 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
784 {
785 	struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
786 
787 	return obj ? &obj->val : NULL;
788 }
789 
dev_map_hash_lookup_elem(struct bpf_map * map,void * key)790 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
791 {
792 	struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
793 								*(u32 *)key);
794 	return obj ? &obj->val : NULL;
795 }
796 
__dev_map_entry_free(struct rcu_head * rcu)797 static void __dev_map_entry_free(struct rcu_head *rcu)
798 {
799 	struct bpf_dtab_netdev *dev;
800 
801 	dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
802 	if (dev->xdp_prog)
803 		bpf_prog_put(dev->xdp_prog);
804 	dev_put(dev->dev);
805 	kfree(dev);
806 }
807 
dev_map_delete_elem(struct bpf_map * map,void * key)808 static long dev_map_delete_elem(struct bpf_map *map, void *key)
809 {
810 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
811 	struct bpf_dtab_netdev *old_dev;
812 	int k = *(u32 *)key;
813 
814 	if (k >= map->max_entries)
815 		return -EINVAL;
816 
817 	old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
818 	if (old_dev) {
819 		call_rcu(&old_dev->rcu, __dev_map_entry_free);
820 		atomic_dec((atomic_t *)&dtab->items);
821 	}
822 	return 0;
823 }
824 
dev_map_hash_delete_elem(struct bpf_map * map,void * key)825 static long dev_map_hash_delete_elem(struct bpf_map *map, void *key)
826 {
827 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
828 	struct bpf_dtab_netdev *old_dev;
829 	int k = *(u32 *)key;
830 	unsigned long flags;
831 	int ret = -ENOENT;
832 
833 	spin_lock_irqsave(&dtab->index_lock, flags);
834 
835 	old_dev = __dev_map_hash_lookup_elem(map, k);
836 	if (old_dev) {
837 		dtab->items--;
838 		hlist_del_init_rcu(&old_dev->index_hlist);
839 		call_rcu(&old_dev->rcu, __dev_map_entry_free);
840 		ret = 0;
841 	}
842 	spin_unlock_irqrestore(&dtab->index_lock, flags);
843 
844 	return ret;
845 }
846 
__dev_map_alloc_node(struct net * net,struct bpf_dtab * dtab,struct bpf_devmap_val * val,unsigned int idx)847 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
848 						    struct bpf_dtab *dtab,
849 						    struct bpf_devmap_val *val,
850 						    unsigned int idx)
851 {
852 	struct bpf_prog *prog = NULL;
853 	struct bpf_dtab_netdev *dev;
854 
855 	dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
856 				   GFP_NOWAIT | __GFP_NOWARN,
857 				   dtab->map.numa_node);
858 	if (!dev)
859 		return ERR_PTR(-ENOMEM);
860 
861 	dev->dev = dev_get_by_index(net, val->ifindex);
862 	if (!dev->dev)
863 		goto err_out;
864 
865 	if (val->bpf_prog.fd > 0) {
866 		prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
867 					     BPF_PROG_TYPE_XDP, false);
868 		if (IS_ERR(prog))
869 			goto err_put_dev;
870 		if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
871 		    !bpf_prog_map_compatible(&dtab->map, prog))
872 			goto err_put_prog;
873 	}
874 
875 	dev->idx = idx;
876 	if (prog) {
877 		dev->xdp_prog = prog;
878 		dev->val.bpf_prog.id = prog->aux->id;
879 	} else {
880 		dev->xdp_prog = NULL;
881 		dev->val.bpf_prog.id = 0;
882 	}
883 	dev->val.ifindex = val->ifindex;
884 
885 	return dev;
886 err_put_prog:
887 	bpf_prog_put(prog);
888 err_put_dev:
889 	dev_put(dev->dev);
890 err_out:
891 	kfree(dev);
892 	return ERR_PTR(-EINVAL);
893 }
894 
__dev_map_update_elem(struct net * net,struct bpf_map * map,void * key,void * value,u64 map_flags)895 static long __dev_map_update_elem(struct net *net, struct bpf_map *map,
896 				  void *key, void *value, u64 map_flags)
897 {
898 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
899 	struct bpf_dtab_netdev *dev, *old_dev;
900 	struct bpf_devmap_val val = {};
901 	u32 i = *(u32 *)key;
902 
903 	if (unlikely(map_flags > BPF_EXIST))
904 		return -EINVAL;
905 	if (unlikely(i >= dtab->map.max_entries))
906 		return -E2BIG;
907 	if (unlikely(map_flags == BPF_NOEXIST))
908 		return -EEXIST;
909 
910 	/* already verified value_size <= sizeof val */
911 	memcpy(&val, value, map->value_size);
912 
913 	if (!val.ifindex) {
914 		dev = NULL;
915 		/* can not specify fd if ifindex is 0 */
916 		if (val.bpf_prog.fd > 0)
917 			return -EINVAL;
918 	} else {
919 		dev = __dev_map_alloc_node(net, dtab, &val, i);
920 		if (IS_ERR(dev))
921 			return PTR_ERR(dev);
922 	}
923 
924 	/* Use call_rcu() here to ensure rcu critical sections have completed
925 	 * Remembering the driver side flush operation will happen before the
926 	 * net device is removed.
927 	 */
928 	old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
929 	if (old_dev)
930 		call_rcu(&old_dev->rcu, __dev_map_entry_free);
931 	else
932 		atomic_inc((atomic_t *)&dtab->items);
933 
934 	return 0;
935 }
936 
dev_map_update_elem(struct bpf_map * map,void * key,void * value,u64 map_flags)937 static long dev_map_update_elem(struct bpf_map *map, void *key, void *value,
938 				u64 map_flags)
939 {
940 	return __dev_map_update_elem(current->nsproxy->net_ns,
941 				     map, key, value, map_flags);
942 }
943 
__dev_map_hash_update_elem(struct net * net,struct bpf_map * map,void * key,void * value,u64 map_flags)944 static long __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
945 				       void *key, void *value, u64 map_flags)
946 {
947 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
948 	struct bpf_dtab_netdev *dev, *old_dev;
949 	struct bpf_devmap_val val = {};
950 	u32 idx = *(u32 *)key;
951 	unsigned long flags;
952 	int err = -EEXIST;
953 
954 	/* already verified value_size <= sizeof val */
955 	memcpy(&val, value, map->value_size);
956 
957 	if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
958 		return -EINVAL;
959 
960 	spin_lock_irqsave(&dtab->index_lock, flags);
961 
962 	old_dev = __dev_map_hash_lookup_elem(map, idx);
963 	if (old_dev && (map_flags & BPF_NOEXIST))
964 		goto out_err;
965 
966 	dev = __dev_map_alloc_node(net, dtab, &val, idx);
967 	if (IS_ERR(dev)) {
968 		err = PTR_ERR(dev);
969 		goto out_err;
970 	}
971 
972 	if (old_dev) {
973 		hlist_del_rcu(&old_dev->index_hlist);
974 	} else {
975 		if (dtab->items >= dtab->map.max_entries) {
976 			spin_unlock_irqrestore(&dtab->index_lock, flags);
977 			call_rcu(&dev->rcu, __dev_map_entry_free);
978 			return -E2BIG;
979 		}
980 		dtab->items++;
981 	}
982 
983 	hlist_add_head_rcu(&dev->index_hlist,
984 			   dev_map_index_hash(dtab, idx));
985 	spin_unlock_irqrestore(&dtab->index_lock, flags);
986 
987 	if (old_dev)
988 		call_rcu(&old_dev->rcu, __dev_map_entry_free);
989 
990 	return 0;
991 
992 out_err:
993 	spin_unlock_irqrestore(&dtab->index_lock, flags);
994 	return err;
995 }
996 
dev_map_hash_update_elem(struct bpf_map * map,void * key,void * value,u64 map_flags)997 static long dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
998 				     u64 map_flags)
999 {
1000 	return __dev_map_hash_update_elem(current->nsproxy->net_ns,
1001 					 map, key, value, map_flags);
1002 }
1003 
dev_map_redirect(struct bpf_map * map,u64 ifindex,u64 flags)1004 static long dev_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1005 {
1006 	return __bpf_xdp_redirect_map(map, ifindex, flags,
1007 				      BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1008 				      __dev_map_lookup_elem);
1009 }
1010 
dev_hash_map_redirect(struct bpf_map * map,u64 ifindex,u64 flags)1011 static long dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1012 {
1013 	return __bpf_xdp_redirect_map(map, ifindex, flags,
1014 				      BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1015 				      __dev_map_hash_lookup_elem);
1016 }
1017 
dev_map_mem_usage(const struct bpf_map * map)1018 static u64 dev_map_mem_usage(const struct bpf_map *map)
1019 {
1020 	struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
1021 	u64 usage = sizeof(struct bpf_dtab);
1022 
1023 	if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
1024 		usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
1025 	else
1026 		usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
1027 	usage += atomic_read((atomic_t *)&dtab->items) *
1028 			 (u64)sizeof(struct bpf_dtab_netdev);
1029 	return usage;
1030 }
1031 
1032 BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
1033 const struct bpf_map_ops dev_map_ops = {
1034 	.map_meta_equal = bpf_map_meta_equal,
1035 	.map_alloc = dev_map_alloc,
1036 	.map_free = dev_map_free,
1037 	.map_get_next_key = dev_map_get_next_key,
1038 	.map_lookup_elem = dev_map_lookup_elem,
1039 	.map_update_elem = dev_map_update_elem,
1040 	.map_delete_elem = dev_map_delete_elem,
1041 	.map_check_btf = map_check_no_btf,
1042 	.map_mem_usage = dev_map_mem_usage,
1043 	.map_btf_id = &dev_map_btf_ids[0],
1044 	.map_redirect = dev_map_redirect,
1045 };
1046 
1047 const struct bpf_map_ops dev_map_hash_ops = {
1048 	.map_meta_equal = bpf_map_meta_equal,
1049 	.map_alloc = dev_map_alloc,
1050 	.map_free = dev_map_free,
1051 	.map_get_next_key = dev_map_hash_get_next_key,
1052 	.map_lookup_elem = dev_map_hash_lookup_elem,
1053 	.map_update_elem = dev_map_hash_update_elem,
1054 	.map_delete_elem = dev_map_hash_delete_elem,
1055 	.map_check_btf = map_check_no_btf,
1056 	.map_mem_usage = dev_map_mem_usage,
1057 	.map_btf_id = &dev_map_btf_ids[0],
1058 	.map_redirect = dev_hash_map_redirect,
1059 };
1060 
dev_map_hash_remove_netdev(struct bpf_dtab * dtab,struct net_device * netdev)1061 static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
1062 				       struct net_device *netdev)
1063 {
1064 	unsigned long flags;
1065 	u32 i;
1066 
1067 	spin_lock_irqsave(&dtab->index_lock, flags);
1068 	for (i = 0; i < dtab->n_buckets; i++) {
1069 		struct bpf_dtab_netdev *dev;
1070 		struct hlist_head *head;
1071 		struct hlist_node *next;
1072 
1073 		head = dev_map_index_hash(dtab, i);
1074 
1075 		hlist_for_each_entry_safe(dev, next, head, index_hlist) {
1076 			if (netdev != dev->dev)
1077 				continue;
1078 
1079 			dtab->items--;
1080 			hlist_del_rcu(&dev->index_hlist);
1081 			call_rcu(&dev->rcu, __dev_map_entry_free);
1082 		}
1083 	}
1084 	spin_unlock_irqrestore(&dtab->index_lock, flags);
1085 }
1086 
dev_map_notification(struct notifier_block * notifier,ulong event,void * ptr)1087 static int dev_map_notification(struct notifier_block *notifier,
1088 				ulong event, void *ptr)
1089 {
1090 	struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
1091 	struct bpf_dtab *dtab;
1092 	int i, cpu;
1093 
1094 	switch (event) {
1095 	case NETDEV_REGISTER:
1096 		if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1097 			break;
1098 
1099 		/* will be freed in free_netdev() */
1100 		netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1101 		if (!netdev->xdp_bulkq)
1102 			return NOTIFY_BAD;
1103 
1104 		for_each_possible_cpu(cpu)
1105 			per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1106 		break;
1107 	case NETDEV_UNREGISTER:
1108 		/* This rcu_read_lock/unlock pair is needed because
1109 		 * dev_map_list is an RCU list AND to ensure a delete
1110 		 * operation does not free a netdev_map entry while we
1111 		 * are comparing it against the netdev being unregistered.
1112 		 */
1113 		rcu_read_lock();
1114 		list_for_each_entry_rcu(dtab, &dev_map_list, list) {
1115 			if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
1116 				dev_map_hash_remove_netdev(dtab, netdev);
1117 				continue;
1118 			}
1119 
1120 			for (i = 0; i < dtab->map.max_entries; i++) {
1121 				struct bpf_dtab_netdev *dev, *odev;
1122 
1123 				dev = rcu_dereference(dtab->netdev_map[i]);
1124 				if (!dev || netdev != dev->dev)
1125 					continue;
1126 				odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1127 				if (dev == odev) {
1128 					call_rcu(&dev->rcu,
1129 						 __dev_map_entry_free);
1130 					atomic_dec((atomic_t *)&dtab->items);
1131 				}
1132 			}
1133 		}
1134 		rcu_read_unlock();
1135 		break;
1136 	default:
1137 		break;
1138 	}
1139 	return NOTIFY_OK;
1140 }
1141 
1142 static struct notifier_block dev_map_notifier = {
1143 	.notifier_call = dev_map_notification,
1144 };
1145 
dev_map_init(void)1146 static int __init dev_map_init(void)
1147 {
1148 	int cpu;
1149 
1150 	/* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1151 	BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1152 		     offsetof(struct _bpf_dtab_netdev, dev));
1153 	register_netdevice_notifier(&dev_map_notifier);
1154 
1155 	for_each_possible_cpu(cpu)
1156 		INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1157 	return 0;
1158 }
1159 
1160 subsys_initcall(dev_map_init);
1161