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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
52#define DEV_CREATE_FLAG_MASK \
53 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
54
55struct xdp_dev_bulk_queue {
56 struct xdp_frame *q[DEV_MAP_BULK_SIZE];
57 struct list_head flush_node;
58 struct net_device *dev;
59 struct net_device *dev_rx;
60 unsigned int count;
61};
62
63struct bpf_dtab_netdev {
64 struct net_device *dev; /* must be first member, due to tracepoint */
65 struct hlist_node index_hlist;
66 struct bpf_dtab *dtab;
67 struct bpf_prog *xdp_prog;
68 struct rcu_head rcu;
69 unsigned int idx;
70 struct bpf_devmap_val val;
71};
72
73struct bpf_dtab {
74 struct bpf_map map;
75 struct bpf_dtab_netdev **netdev_map; /* DEVMAP type only */
76 struct list_head list;
77
78 /* these are only used for DEVMAP_HASH type maps */
79 struct hlist_head *dev_index_head;
80 spinlock_t index_lock;
81 unsigned int items;
82 u32 n_buckets;
83};
84
85static DEFINE_PER_CPU(struct list_head, dev_flush_list);
86static DEFINE_SPINLOCK(dev_map_lock);
87static LIST_HEAD(dev_map_list);
88
89static struct hlist_head *dev_map_create_hash(unsigned int entries,
90 int numa_node)
91{
92 int i;
93 struct hlist_head *hash;
94
95 hash = bpf_map_area_alloc(entries * sizeof(*hash), numa_node);
96 if (hash != NULL)
97 for (i = 0; i < entries; i++)
98 INIT_HLIST_HEAD(&hash[i]);
99
100 return hash;
101}
102
103static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
104 int idx)
105{
106 return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
107}
108
109static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
110{
111 u32 valsize = attr->value_size;
112 u64 cost = 0;
113 int err;
114
115 /* check sanity of attributes. 2 value sizes supported:
116 * 4 bytes: ifindex
117 * 8 bytes: ifindex + prog fd
118 */
119 if (attr->max_entries == 0 || attr->key_size != 4 ||
120 (valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
121 valsize != offsetofend(struct bpf_devmap_val, bpf_prog.fd)) ||
122 attr->map_flags & ~DEV_CREATE_FLAG_MASK)
123 return -EINVAL;
124
125 /* Lookup returns a pointer straight to dev->ifindex, so make sure the
126 * verifier prevents writes from the BPF side
127 */
128 attr->map_flags |= BPF_F_RDONLY_PROG;
129
130
131 bpf_map_init_from_attr(&dtab->map, attr);
132
133 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
134 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
135
136 if (!dtab->n_buckets) /* Overflow check */
137 return -EINVAL;
138 cost += (u64) sizeof(struct hlist_head) * dtab->n_buckets;
139 } else {
140 cost += (u64) dtab->map.max_entries * sizeof(struct bpf_dtab_netdev *);
141 }
142
143 /* if map size is larger than memlock limit, reject it */
144 err = bpf_map_charge_init(&dtab->map.memory, cost);
145 if (err)
146 return -EINVAL;
147
148 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
149 dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
150 dtab->map.numa_node);
151 if (!dtab->dev_index_head)
152 goto free_charge;
153
154 spin_lock_init(&dtab->index_lock);
155 } else {
156 dtab->netdev_map = bpf_map_area_alloc(dtab->map.max_entries *
157 sizeof(struct bpf_dtab_netdev *),
158 dtab->map.numa_node);
159 if (!dtab->netdev_map)
160 goto free_charge;
161 }
162
163 return 0;
164
165free_charge:
166 bpf_map_charge_finish(&dtab->map.memory);
167 return -ENOMEM;
168}
169
170static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
171{
172 struct bpf_dtab *dtab;
173 int err;
174
175 if (!capable(CAP_NET_ADMIN))
176 return ERR_PTR(-EPERM);
177
178 dtab = kzalloc(sizeof(*dtab), GFP_USER);
179 if (!dtab)
180 return ERR_PTR(-ENOMEM);
181
182 err = dev_map_init_map(dtab, attr);
183 if (err) {
184 kfree(dtab);
185 return ERR_PTR(err);
186 }
187
188 spin_lock(&dev_map_lock);
189 list_add_tail_rcu(&dtab->list, &dev_map_list);
190 spin_unlock(&dev_map_lock);
191
192 return &dtab->map;
193}
194
195static void dev_map_free(struct bpf_map *map)
196{
197 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
198 int i;
199
200 /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
201 * so the programs (can be more than one that used this map) were
202 * disconnected from events. The following synchronize_rcu() guarantees
203 * both rcu read critical sections complete and waits for
204 * preempt-disable regions (NAPI being the relevant context here) so we
205 * are certain there will be no further reads against the netdev_map and
206 * all flush operations are complete. Flush operations can only be done
207 * from NAPI context for this reason.
208 */
209
210 spin_lock(&dev_map_lock);
211 list_del_rcu(&dtab->list);
212 spin_unlock(&dev_map_lock);
213
214 bpf_clear_redirect_map(map);
215 synchronize_rcu();
216
217 /* Make sure prior __dev_map_entry_free() have completed. */
218 rcu_barrier();
219
220 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
221 for (i = 0; i < dtab->n_buckets; i++) {
222 struct bpf_dtab_netdev *dev;
223 struct hlist_head *head;
224 struct hlist_node *next;
225
226 head = dev_map_index_hash(dtab, i);
227
228 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
229 hlist_del_rcu(&dev->index_hlist);
230 if (dev->xdp_prog)
231 bpf_prog_put(dev->xdp_prog);
232 dev_put(dev->dev);
233 kfree(dev);
234 }
235 }
236
237 bpf_map_area_free(dtab->dev_index_head);
238 } else {
239 for (i = 0; i < dtab->map.max_entries; i++) {
240 struct bpf_dtab_netdev *dev;
241
242 dev = dtab->netdev_map[i];
243 if (!dev)
244 continue;
245
246 if (dev->xdp_prog)
247 bpf_prog_put(dev->xdp_prog);
248 dev_put(dev->dev);
249 kfree(dev);
250 }
251
252 bpf_map_area_free(dtab->netdev_map);
253 }
254
255 kfree(dtab);
256}
257
258static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
259{
260 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
261 u32 index = key ? *(u32 *)key : U32_MAX;
262 u32 *next = next_key;
263
264 if (index >= dtab->map.max_entries) {
265 *next = 0;
266 return 0;
267 }
268
269 if (index == dtab->map.max_entries - 1)
270 return -ENOENT;
271 *next = index + 1;
272 return 0;
273}
274
275struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
276{
277 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
278 struct hlist_head *head = dev_map_index_hash(dtab, key);
279 struct bpf_dtab_netdev *dev;
280
281 hlist_for_each_entry_rcu(dev, head, index_hlist,
282 lockdep_is_held(&dtab->index_lock))
283 if (dev->idx == key)
284 return dev;
285
286 return NULL;
287}
288
289static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
290 void *next_key)
291{
292 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
293 u32 idx, *next = next_key;
294 struct bpf_dtab_netdev *dev, *next_dev;
295 struct hlist_head *head;
296 int i = 0;
297
298 if (!key)
299 goto find_first;
300
301 idx = *(u32 *)key;
302
303 dev = __dev_map_hash_lookup_elem(map, idx);
304 if (!dev)
305 goto find_first;
306
307 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
308 struct bpf_dtab_netdev, index_hlist);
309
310 if (next_dev) {
311 *next = next_dev->idx;
312 return 0;
313 }
314
315 i = idx & (dtab->n_buckets - 1);
316 i++;
317
318 find_first:
319 for (; i < dtab->n_buckets; i++) {
320 head = dev_map_index_hash(dtab, i);
321
322 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
323 struct bpf_dtab_netdev,
324 index_hlist);
325 if (next_dev) {
326 *next = next_dev->idx;
327 return 0;
328 }
329 }
330
331 return -ENOENT;
332}
333
334bool dev_map_can_have_prog(struct bpf_map *map)
335{
336 if ((map->map_type == BPF_MAP_TYPE_DEVMAP ||
337 map->map_type == BPF_MAP_TYPE_DEVMAP_HASH) &&
338 map->value_size != offsetofend(struct bpf_devmap_val, ifindex))
339 return true;
340
341 return false;
342}
343
344static int bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
345{
346 struct net_device *dev = bq->dev;
347 int sent = 0, drops = 0, err = 0;
348 int i;
349
350 if (unlikely(!bq->count))
351 return 0;
352
353 for (i = 0; i < bq->count; i++) {
354 struct xdp_frame *xdpf = bq->q[i];
355
356 prefetch(xdpf);
357 }
358
359 sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, flags);
360 if (sent < 0) {
361 err = sent;
362 sent = 0;
363 goto error;
364 }
365 drops = bq->count - sent;
366out:
367 bq->count = 0;
368
369 trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, drops, err);
370 bq->dev_rx = NULL;
371 __list_del_clearprev(&bq->flush_node);
372 return 0;
373error:
374 /* If ndo_xdp_xmit fails with an errno, no frames have been
375 * xmit'ed and it's our responsibility to them free all.
376 */
377 for (i = 0; i < bq->count; i++) {
378 struct xdp_frame *xdpf = bq->q[i];
379
380 xdp_return_frame_rx_napi(xdpf);
381 drops++;
382 }
383 goto out;
384}
385
386/* __dev_flush is called from xdp_do_flush() which _must_ be signaled
387 * from the driver before returning from its napi->poll() routine. The poll()
388 * routine is called either from busy_poll context or net_rx_action signaled
389 * from NET_RX_SOFTIRQ. Either way the poll routine must complete before the
390 * net device can be torn down. On devmap tear down we ensure the flush list
391 * is empty before completing to ensure all flush operations have completed.
392 * When drivers update the bpf program they may need to ensure any flush ops
393 * are also complete. Using synchronize_rcu or call_rcu will suffice for this
394 * because both wait for napi context to exit.
395 */
396void __dev_flush(void)
397{
398 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
399 struct xdp_dev_bulk_queue *bq, *tmp;
400
401 list_for_each_entry_safe(bq, tmp, flush_list, flush_node)
402 bq_xmit_all(bq, XDP_XMIT_FLUSH);
403}
404
405/* rcu_read_lock (from syscall and BPF contexts) ensures that if a delete and/or
406 * update happens in parallel here a dev_put wont happen until after reading the
407 * ifindex.
408 */
409struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
410{
411 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
412 struct bpf_dtab_netdev *obj;
413
414 if (key >= map->max_entries)
415 return NULL;
416
417 obj = READ_ONCE(dtab->netdev_map[key]);
418 return obj;
419}
420
421/* Runs under RCU-read-side, plus in softirq under NAPI protection.
422 * Thus, safe percpu variable access.
423 */
424static int bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
425 struct net_device *dev_rx)
426{
427 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
428 struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
429
430 if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
431 bq_xmit_all(bq, 0);
432
433 /* Ingress dev_rx will be the same for all xdp_frame's in
434 * bulk_queue, because bq stored per-CPU and must be flushed
435 * from net_device drivers NAPI func end.
436 */
437 if (!bq->dev_rx)
438 bq->dev_rx = dev_rx;
439
440 bq->q[bq->count++] = xdpf;
441
442 if (!bq->flush_node.prev)
443 list_add(&bq->flush_node, flush_list);
444
445 return 0;
446}
447
448static inline int __xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
449 struct net_device *dev_rx)
450{
451 struct xdp_frame *xdpf;
452 int err;
453
454 if (!dev->netdev_ops->ndo_xdp_xmit)
455 return -EOPNOTSUPP;
456
457 err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
458 if (unlikely(err))
459 return err;
460
461 xdpf = xdp_convert_buff_to_frame(xdp);
462 if (unlikely(!xdpf))
463 return -EOVERFLOW;
464
465 return bq_enqueue(dev, xdpf, dev_rx);
466}
467
468static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
469 struct xdp_buff *xdp,
470 struct bpf_prog *xdp_prog)
471{
472 struct xdp_txq_info txq = { .dev = dev };
473 u32 act;
474
475 xdp_set_data_meta_invalid(xdp);
476 xdp->txq = &txq;
477
478 act = bpf_prog_run_xdp(xdp_prog, xdp);
479 switch (act) {
480 case XDP_PASS:
481 return xdp;
482 case XDP_DROP:
483 break;
484 default:
485 bpf_warn_invalid_xdp_action(act);
486 fallthrough;
487 case XDP_ABORTED:
488 trace_xdp_exception(dev, xdp_prog, act);
489 break;
490 }
491
492 xdp_return_buff(xdp);
493 return NULL;
494}
495
496int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
497 struct net_device *dev_rx)
498{
499 return __xdp_enqueue(dev, xdp, dev_rx);
500}
501
502int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
503 struct net_device *dev_rx)
504{
505 struct net_device *dev = dst->dev;
506
507 if (dst->xdp_prog) {
508 xdp = dev_map_run_prog(dev, xdp, dst->xdp_prog);
509 if (!xdp)
510 return 0;
511 }
512 return __xdp_enqueue(dev, xdp, dev_rx);
513}
514
515int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
516 struct bpf_prog *xdp_prog)
517{
518 int err;
519
520 err = xdp_ok_fwd_dev(dst->dev, skb->len);
521 if (unlikely(err))
522 return err;
523 skb->dev = dst->dev;
524 generic_xdp_tx(skb, xdp_prog);
525
526 return 0;
527}
528
529static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
530{
531 struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
532
533 return obj ? &obj->val : NULL;
534}
535
536static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
537{
538 struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
539 *(u32 *)key);
540 return obj ? &obj->val : NULL;
541}
542
543static void __dev_map_entry_free(struct rcu_head *rcu)
544{
545 struct bpf_dtab_netdev *dev;
546
547 dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
548 if (dev->xdp_prog)
549 bpf_prog_put(dev->xdp_prog);
550 dev_put(dev->dev);
551 kfree(dev);
552}
553
554static int dev_map_delete_elem(struct bpf_map *map, void *key)
555{
556 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
557 struct bpf_dtab_netdev *old_dev;
558 int k = *(u32 *)key;
559
560 if (k >= map->max_entries)
561 return -EINVAL;
562
563 /* Use call_rcu() here to ensure any rcu critical sections have
564 * completed as well as any flush operations because call_rcu
565 * will wait for preempt-disable region to complete, NAPI in this
566 * context. And additionally, the driver tear down ensures all
567 * soft irqs are complete before removing the net device in the
568 * case of dev_put equals zero.
569 */
570 old_dev = xchg(&dtab->netdev_map[k], NULL);
571 if (old_dev)
572 call_rcu(&old_dev->rcu, __dev_map_entry_free);
573 return 0;
574}
575
576static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
577{
578 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
579 struct bpf_dtab_netdev *old_dev;
580 int k = *(u32 *)key;
581 unsigned long flags;
582 int ret = -ENOENT;
583
584 spin_lock_irqsave(&dtab->index_lock, flags);
585
586 old_dev = __dev_map_hash_lookup_elem(map, k);
587 if (old_dev) {
588 dtab->items--;
589 hlist_del_init_rcu(&old_dev->index_hlist);
590 call_rcu(&old_dev->rcu, __dev_map_entry_free);
591 ret = 0;
592 }
593 spin_unlock_irqrestore(&dtab->index_lock, flags);
594
595 return ret;
596}
597
598static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
599 struct bpf_dtab *dtab,
600 struct bpf_devmap_val *val,
601 unsigned int idx)
602{
603 struct bpf_prog *prog = NULL;
604 struct bpf_dtab_netdev *dev;
605
606 dev = kmalloc_node(sizeof(*dev), GFP_ATOMIC | __GFP_NOWARN,
607 dtab->map.numa_node);
608 if (!dev)
609 return ERR_PTR(-ENOMEM);
610
611 dev->dev = dev_get_by_index(net, val->ifindex);
612 if (!dev->dev)
613 goto err_out;
614
615 if (val->bpf_prog.fd > 0) {
616 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
617 BPF_PROG_TYPE_XDP, false);
618 if (IS_ERR(prog))
619 goto err_put_dev;
620 if (prog->expected_attach_type != BPF_XDP_DEVMAP)
621 goto err_put_prog;
622 }
623
624 dev->idx = idx;
625 dev->dtab = dtab;
626 if (prog) {
627 dev->xdp_prog = prog;
628 dev->val.bpf_prog.id = prog->aux->id;
629 } else {
630 dev->xdp_prog = NULL;
631 dev->val.bpf_prog.id = 0;
632 }
633 dev->val.ifindex = val->ifindex;
634
635 return dev;
636err_put_prog:
637 bpf_prog_put(prog);
638err_put_dev:
639 dev_put(dev->dev);
640err_out:
641 kfree(dev);
642 return ERR_PTR(-EINVAL);
643}
644
645static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
646 void *key, void *value, u64 map_flags)
647{
648 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
649 struct bpf_dtab_netdev *dev, *old_dev;
650 struct bpf_devmap_val val = {};
651 u32 i = *(u32 *)key;
652
653 if (unlikely(map_flags > BPF_EXIST))
654 return -EINVAL;
655 if (unlikely(i >= dtab->map.max_entries))
656 return -E2BIG;
657 if (unlikely(map_flags == BPF_NOEXIST))
658 return -EEXIST;
659
660 /* already verified value_size <= sizeof val */
661 memcpy(&val, value, map->value_size);
662
663 if (!val.ifindex) {
664 dev = NULL;
665 /* can not specify fd if ifindex is 0 */
666 if (val.bpf_prog.fd > 0)
667 return -EINVAL;
668 } else {
669 dev = __dev_map_alloc_node(net, dtab, &val, i);
670 if (IS_ERR(dev))
671 return PTR_ERR(dev);
672 }
673
674 /* Use call_rcu() here to ensure rcu critical sections have completed
675 * Remembering the driver side flush operation will happen before the
676 * net device is removed.
677 */
678 old_dev = xchg(&dtab->netdev_map[i], dev);
679 if (old_dev)
680 call_rcu(&old_dev->rcu, __dev_map_entry_free);
681
682 return 0;
683}
684
685static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
686 u64 map_flags)
687{
688 return __dev_map_update_elem(current->nsproxy->net_ns,
689 map, key, value, map_flags);
690}
691
692static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
693 void *key, void *value, u64 map_flags)
694{
695 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
696 struct bpf_dtab_netdev *dev, *old_dev;
697 struct bpf_devmap_val val = {};
698 u32 idx = *(u32 *)key;
699 unsigned long flags;
700 int err = -EEXIST;
701
702 /* already verified value_size <= sizeof val */
703 memcpy(&val, value, map->value_size);
704
705 if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
706 return -EINVAL;
707
708 spin_lock_irqsave(&dtab->index_lock, flags);
709
710 old_dev = __dev_map_hash_lookup_elem(map, idx);
711 if (old_dev && (map_flags & BPF_NOEXIST))
712 goto out_err;
713
714 dev = __dev_map_alloc_node(net, dtab, &val, idx);
715 if (IS_ERR(dev)) {
716 err = PTR_ERR(dev);
717 goto out_err;
718 }
719
720 if (old_dev) {
721 hlist_del_rcu(&old_dev->index_hlist);
722 } else {
723 if (dtab->items >= dtab->map.max_entries) {
724 spin_unlock_irqrestore(&dtab->index_lock, flags);
725 call_rcu(&dev->rcu, __dev_map_entry_free);
726 return -E2BIG;
727 }
728 dtab->items++;
729 }
730
731 hlist_add_head_rcu(&dev->index_hlist,
732 dev_map_index_hash(dtab, idx));
733 spin_unlock_irqrestore(&dtab->index_lock, flags);
734
735 if (old_dev)
736 call_rcu(&old_dev->rcu, __dev_map_entry_free);
737
738 return 0;
739
740out_err:
741 spin_unlock_irqrestore(&dtab->index_lock, flags);
742 return err;
743}
744
745static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
746 u64 map_flags)
747{
748 return __dev_map_hash_update_elem(current->nsproxy->net_ns,
749 map, key, value, map_flags);
750}
751
752static int dev_map_btf_id;
753const struct bpf_map_ops dev_map_ops = {
754 .map_alloc = dev_map_alloc,
755 .map_free = dev_map_free,
756 .map_get_next_key = dev_map_get_next_key,
757 .map_lookup_elem = dev_map_lookup_elem,
758 .map_update_elem = dev_map_update_elem,
759 .map_delete_elem = dev_map_delete_elem,
760 .map_check_btf = map_check_no_btf,
761 .map_btf_name = "bpf_dtab",
762 .map_btf_id = &dev_map_btf_id,
763};
764
765static int dev_map_hash_map_btf_id;
766const struct bpf_map_ops dev_map_hash_ops = {
767 .map_alloc = dev_map_alloc,
768 .map_free = dev_map_free,
769 .map_get_next_key = dev_map_hash_get_next_key,
770 .map_lookup_elem = dev_map_hash_lookup_elem,
771 .map_update_elem = dev_map_hash_update_elem,
772 .map_delete_elem = dev_map_hash_delete_elem,
773 .map_check_btf = map_check_no_btf,
774 .map_btf_name = "bpf_dtab",
775 .map_btf_id = &dev_map_hash_map_btf_id,
776};
777
778static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
779 struct net_device *netdev)
780{
781 unsigned long flags;
782 u32 i;
783
784 spin_lock_irqsave(&dtab->index_lock, flags);
785 for (i = 0; i < dtab->n_buckets; i++) {
786 struct bpf_dtab_netdev *dev;
787 struct hlist_head *head;
788 struct hlist_node *next;
789
790 head = dev_map_index_hash(dtab, i);
791
792 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
793 if (netdev != dev->dev)
794 continue;
795
796 dtab->items--;
797 hlist_del_rcu(&dev->index_hlist);
798 call_rcu(&dev->rcu, __dev_map_entry_free);
799 }
800 }
801 spin_unlock_irqrestore(&dtab->index_lock, flags);
802}
803
804static int dev_map_notification(struct notifier_block *notifier,
805 ulong event, void *ptr)
806{
807 struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
808 struct bpf_dtab *dtab;
809 int i, cpu;
810
811 switch (event) {
812 case NETDEV_REGISTER:
813 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
814 break;
815
816 /* will be freed in free_netdev() */
817 netdev->xdp_bulkq =
818 __alloc_percpu_gfp(sizeof(struct xdp_dev_bulk_queue),
819 sizeof(void *), GFP_ATOMIC);
820 if (!netdev->xdp_bulkq)
821 return NOTIFY_BAD;
822
823 for_each_possible_cpu(cpu)
824 per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
825 break;
826 case NETDEV_UNREGISTER:
827 /* This rcu_read_lock/unlock pair is needed because
828 * dev_map_list is an RCU list AND to ensure a delete
829 * operation does not free a netdev_map entry while we
830 * are comparing it against the netdev being unregistered.
831 */
832 rcu_read_lock();
833 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
834 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
835 dev_map_hash_remove_netdev(dtab, netdev);
836 continue;
837 }
838
839 for (i = 0; i < dtab->map.max_entries; i++) {
840 struct bpf_dtab_netdev *dev, *odev;
841
842 dev = READ_ONCE(dtab->netdev_map[i]);
843 if (!dev || netdev != dev->dev)
844 continue;
845 odev = cmpxchg(&dtab->netdev_map[i], dev, NULL);
846 if (dev == odev)
847 call_rcu(&dev->rcu,
848 __dev_map_entry_free);
849 }
850 }
851 rcu_read_unlock();
852 break;
853 default:
854 break;
855 }
856 return NOTIFY_OK;
857}
858
859static struct notifier_block dev_map_notifier = {
860 .notifier_call = dev_map_notification,
861};
862
863static int __init dev_map_init(void)
864{
865 int cpu;
866
867 /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
868 BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
869 offsetof(struct _bpf_dtab_netdev, dev));
870 register_netdevice_notifier(&dev_map_notifier);
871
872 for_each_possible_cpu(cpu)
873 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
874 return 0;
875}
876
877subsys_initcall(dev_map_init);
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
56struct 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
65struct 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
74struct 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
86static DEFINE_PER_CPU(struct list_head, dev_flush_list);
87static DEFINE_SPINLOCK(dev_map_lock);
88static LIST_HEAD(dev_map_list);
89
90static 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
104static 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
110static 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 /* hash table size must be power of 2; roundup_pow_of_two() can
134 * overflow into UB on 32-bit arches, so check that first
135 */
136 if (dtab->map.max_entries > 1UL << 31)
137 return -EINVAL;
138
139 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
140
141 dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
142 dtab->map.numa_node);
143 if (!dtab->dev_index_head)
144 return -ENOMEM;
145
146 spin_lock_init(&dtab->index_lock);
147 } else {
148 dtab->netdev_map = bpf_map_area_alloc((u64) dtab->map.max_entries *
149 sizeof(struct bpf_dtab_netdev *),
150 dtab->map.numa_node);
151 if (!dtab->netdev_map)
152 return -ENOMEM;
153 }
154
155 return 0;
156}
157
158static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
159{
160 struct bpf_dtab *dtab;
161 int err;
162
163 dtab = bpf_map_area_alloc(sizeof(*dtab), NUMA_NO_NODE);
164 if (!dtab)
165 return ERR_PTR(-ENOMEM);
166
167 err = dev_map_init_map(dtab, attr);
168 if (err) {
169 bpf_map_area_free(dtab);
170 return ERR_PTR(err);
171 }
172
173 spin_lock(&dev_map_lock);
174 list_add_tail_rcu(&dtab->list, &dev_map_list);
175 spin_unlock(&dev_map_lock);
176
177 return &dtab->map;
178}
179
180static void dev_map_free(struct bpf_map *map)
181{
182 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
183 int i;
184
185 /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
186 * so the programs (can be more than one that used this map) were
187 * disconnected from events. The following synchronize_rcu() guarantees
188 * both rcu read critical sections complete and waits for
189 * preempt-disable regions (NAPI being the relevant context here) so we
190 * are certain there will be no further reads against the netdev_map and
191 * all flush operations are complete. Flush operations can only be done
192 * from NAPI context for this reason.
193 */
194
195 spin_lock(&dev_map_lock);
196 list_del_rcu(&dtab->list);
197 spin_unlock(&dev_map_lock);
198
199 bpf_clear_redirect_map(map);
200 synchronize_rcu();
201
202 /* Make sure prior __dev_map_entry_free() have completed. */
203 rcu_barrier();
204
205 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
206 for (i = 0; i < dtab->n_buckets; i++) {
207 struct bpf_dtab_netdev *dev;
208 struct hlist_head *head;
209 struct hlist_node *next;
210
211 head = dev_map_index_hash(dtab, i);
212
213 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
214 hlist_del_rcu(&dev->index_hlist);
215 if (dev->xdp_prog)
216 bpf_prog_put(dev->xdp_prog);
217 dev_put(dev->dev);
218 kfree(dev);
219 }
220 }
221
222 bpf_map_area_free(dtab->dev_index_head);
223 } else {
224 for (i = 0; i < dtab->map.max_entries; i++) {
225 struct bpf_dtab_netdev *dev;
226
227 dev = rcu_dereference_raw(dtab->netdev_map[i]);
228 if (!dev)
229 continue;
230
231 if (dev->xdp_prog)
232 bpf_prog_put(dev->xdp_prog);
233 dev_put(dev->dev);
234 kfree(dev);
235 }
236
237 bpf_map_area_free(dtab->netdev_map);
238 }
239
240 bpf_map_area_free(dtab);
241}
242
243static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
244{
245 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
246 u32 index = key ? *(u32 *)key : U32_MAX;
247 u32 *next = next_key;
248
249 if (index >= dtab->map.max_entries) {
250 *next = 0;
251 return 0;
252 }
253
254 if (index == dtab->map.max_entries - 1)
255 return -ENOENT;
256 *next = index + 1;
257 return 0;
258}
259
260/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
261 * by local_bh_disable() (from XDP calls inside NAPI). The
262 * rcu_read_lock_bh_held() below makes lockdep accept both.
263 */
264static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
265{
266 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
267 struct hlist_head *head = dev_map_index_hash(dtab, key);
268 struct bpf_dtab_netdev *dev;
269
270 hlist_for_each_entry_rcu(dev, head, index_hlist,
271 lockdep_is_held(&dtab->index_lock))
272 if (dev->idx == key)
273 return dev;
274
275 return NULL;
276}
277
278static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
279 void *next_key)
280{
281 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
282 u32 idx, *next = next_key;
283 struct bpf_dtab_netdev *dev, *next_dev;
284 struct hlist_head *head;
285 int i = 0;
286
287 if (!key)
288 goto find_first;
289
290 idx = *(u32 *)key;
291
292 dev = __dev_map_hash_lookup_elem(map, idx);
293 if (!dev)
294 goto find_first;
295
296 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
297 struct bpf_dtab_netdev, index_hlist);
298
299 if (next_dev) {
300 *next = next_dev->idx;
301 return 0;
302 }
303
304 i = idx & (dtab->n_buckets - 1);
305 i++;
306
307 find_first:
308 for (; i < dtab->n_buckets; i++) {
309 head = dev_map_index_hash(dtab, i);
310
311 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
312 struct bpf_dtab_netdev,
313 index_hlist);
314 if (next_dev) {
315 *next = next_dev->idx;
316 return 0;
317 }
318 }
319
320 return -ENOENT;
321}
322
323static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
324 struct xdp_frame **frames, int n,
325 struct net_device *dev)
326{
327 struct xdp_txq_info txq = { .dev = dev };
328 struct xdp_buff xdp;
329 int i, nframes = 0;
330
331 for (i = 0; i < n; i++) {
332 struct xdp_frame *xdpf = frames[i];
333 u32 act;
334 int err;
335
336 xdp_convert_frame_to_buff(xdpf, &xdp);
337 xdp.txq = &txq;
338
339 act = bpf_prog_run_xdp(xdp_prog, &xdp);
340 switch (act) {
341 case XDP_PASS:
342 err = xdp_update_frame_from_buff(&xdp, xdpf);
343 if (unlikely(err < 0))
344 xdp_return_frame_rx_napi(xdpf);
345 else
346 frames[nframes++] = xdpf;
347 break;
348 default:
349 bpf_warn_invalid_xdp_action(NULL, xdp_prog, act);
350 fallthrough;
351 case XDP_ABORTED:
352 trace_xdp_exception(dev, xdp_prog, act);
353 fallthrough;
354 case XDP_DROP:
355 xdp_return_frame_rx_napi(xdpf);
356 break;
357 }
358 }
359 return nframes; /* sent frames count */
360}
361
362static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
363{
364 struct net_device *dev = bq->dev;
365 unsigned int cnt = bq->count;
366 int sent = 0, err = 0;
367 int to_send = cnt;
368 int i;
369
370 if (unlikely(!cnt))
371 return;
372
373 for (i = 0; i < cnt; i++) {
374 struct xdp_frame *xdpf = bq->q[i];
375
376 prefetch(xdpf);
377 }
378
379 if (bq->xdp_prog) {
380 to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
381 if (!to_send)
382 goto out;
383 }
384
385 sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
386 if (sent < 0) {
387 /* If ndo_xdp_xmit fails with an errno, no frames have
388 * been xmit'ed.
389 */
390 err = sent;
391 sent = 0;
392 }
393
394 /* If not all frames have been transmitted, it is our
395 * responsibility to free them
396 */
397 for (i = sent; unlikely(i < to_send); i++)
398 xdp_return_frame_rx_napi(bq->q[i]);
399
400out:
401 bq->count = 0;
402 trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
403}
404
405/* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
406 * driver before returning from its napi->poll() routine. See the comment above
407 * xdp_do_flush() in filter.c.
408 */
409void __dev_flush(void)
410{
411 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
412 struct xdp_dev_bulk_queue *bq, *tmp;
413
414 list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
415 bq_xmit_all(bq, XDP_XMIT_FLUSH);
416 bq->dev_rx = NULL;
417 bq->xdp_prog = NULL;
418 __list_del_clearprev(&bq->flush_node);
419 }
420}
421
422#ifdef CONFIG_DEBUG_NET
423bool dev_check_flush(void)
424{
425 if (list_empty(this_cpu_ptr(&dev_flush_list)))
426 return false;
427 __dev_flush();
428 return true;
429}
430#endif
431
432/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
433 * by local_bh_disable() (from XDP calls inside NAPI). The
434 * rcu_read_lock_bh_held() below makes lockdep accept both.
435 */
436static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
437{
438 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
439 struct bpf_dtab_netdev *obj;
440
441 if (key >= map->max_entries)
442 return NULL;
443
444 obj = rcu_dereference_check(dtab->netdev_map[key],
445 rcu_read_lock_bh_held());
446 return obj;
447}
448
449/* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
450 * variable access, and map elements stick around. See comment above
451 * xdp_do_flush() in filter.c.
452 */
453static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
454 struct net_device *dev_rx, struct bpf_prog *xdp_prog)
455{
456 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
457 struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
458
459 if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
460 bq_xmit_all(bq, 0);
461
462 /* Ingress dev_rx will be the same for all xdp_frame's in
463 * bulk_queue, because bq stored per-CPU and must be flushed
464 * from net_device drivers NAPI func end.
465 *
466 * Do the same with xdp_prog and flush_list since these fields
467 * are only ever modified together.
468 */
469 if (!bq->dev_rx) {
470 bq->dev_rx = dev_rx;
471 bq->xdp_prog = xdp_prog;
472 list_add(&bq->flush_node, flush_list);
473 }
474
475 bq->q[bq->count++] = xdpf;
476}
477
478static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
479 struct net_device *dev_rx,
480 struct bpf_prog *xdp_prog)
481{
482 int err;
483
484 if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
485 return -EOPNOTSUPP;
486
487 if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
488 xdp_frame_has_frags(xdpf)))
489 return -EOPNOTSUPP;
490
491 err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
492 if (unlikely(err))
493 return err;
494
495 bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
496 return 0;
497}
498
499static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
500{
501 struct xdp_txq_info txq = { .dev = dst->dev };
502 struct xdp_buff xdp;
503 u32 act;
504
505 if (!dst->xdp_prog)
506 return XDP_PASS;
507
508 __skb_pull(skb, skb->mac_len);
509 xdp.txq = &txq;
510
511 act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
512 switch (act) {
513 case XDP_PASS:
514 __skb_push(skb, skb->mac_len);
515 break;
516 default:
517 bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
518 fallthrough;
519 case XDP_ABORTED:
520 trace_xdp_exception(dst->dev, dst->xdp_prog, act);
521 fallthrough;
522 case XDP_DROP:
523 kfree_skb(skb);
524 break;
525 }
526
527 return act;
528}
529
530int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
531 struct net_device *dev_rx)
532{
533 return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
534}
535
536int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
537 struct net_device *dev_rx)
538{
539 struct net_device *dev = dst->dev;
540
541 return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
542}
543
544static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
545{
546 if (!obj)
547 return false;
548
549 if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
550 return false;
551
552 if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
553 xdp_frame_has_frags(xdpf)))
554 return false;
555
556 if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
557 return false;
558
559 return true;
560}
561
562static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
563 struct net_device *dev_rx,
564 struct xdp_frame *xdpf)
565{
566 struct xdp_frame *nxdpf;
567
568 nxdpf = xdpf_clone(xdpf);
569 if (!nxdpf)
570 return -ENOMEM;
571
572 bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
573
574 return 0;
575}
576
577static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
578{
579 while (num_excluded--) {
580 if (ifindex == excluded[num_excluded])
581 return true;
582 }
583 return false;
584}
585
586/* Get ifindex of each upper device. 'indexes' must be able to hold at
587 * least MAX_NEST_DEV elements.
588 * Returns the number of ifindexes added.
589 */
590static int get_upper_ifindexes(struct net_device *dev, int *indexes)
591{
592 struct net_device *upper;
593 struct list_head *iter;
594 int n = 0;
595
596 netdev_for_each_upper_dev_rcu(dev, upper, iter) {
597 indexes[n++] = upper->ifindex;
598 }
599 return n;
600}
601
602int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
603 struct bpf_map *map, bool exclude_ingress)
604{
605 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
606 struct bpf_dtab_netdev *dst, *last_dst = NULL;
607 int excluded_devices[1+MAX_NEST_DEV];
608 struct hlist_head *head;
609 int num_excluded = 0;
610 unsigned int i;
611 int err;
612
613 if (exclude_ingress) {
614 num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
615 excluded_devices[num_excluded++] = dev_rx->ifindex;
616 }
617
618 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
619 for (i = 0; i < map->max_entries; i++) {
620 dst = rcu_dereference_check(dtab->netdev_map[i],
621 rcu_read_lock_bh_held());
622 if (!is_valid_dst(dst, xdpf))
623 continue;
624
625 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
626 continue;
627
628 /* we only need n-1 clones; last_dst enqueued below */
629 if (!last_dst) {
630 last_dst = dst;
631 continue;
632 }
633
634 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
635 if (err)
636 return err;
637
638 last_dst = dst;
639 }
640 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
641 for (i = 0; i < dtab->n_buckets; i++) {
642 head = dev_map_index_hash(dtab, i);
643 hlist_for_each_entry_rcu(dst, head, index_hlist,
644 lockdep_is_held(&dtab->index_lock)) {
645 if (!is_valid_dst(dst, xdpf))
646 continue;
647
648 if (is_ifindex_excluded(excluded_devices, num_excluded,
649 dst->dev->ifindex))
650 continue;
651
652 /* we only need n-1 clones; last_dst enqueued below */
653 if (!last_dst) {
654 last_dst = dst;
655 continue;
656 }
657
658 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
659 if (err)
660 return err;
661
662 last_dst = dst;
663 }
664 }
665 }
666
667 /* consume the last copy of the frame */
668 if (last_dst)
669 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
670 else
671 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
672
673 return 0;
674}
675
676int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
677 struct bpf_prog *xdp_prog)
678{
679 int err;
680
681 err = xdp_ok_fwd_dev(dst->dev, skb->len);
682 if (unlikely(err))
683 return err;
684
685 /* Redirect has already succeeded semantically at this point, so we just
686 * return 0 even if packet is dropped. Helper below takes care of
687 * freeing skb.
688 */
689 if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
690 return 0;
691
692 skb->dev = dst->dev;
693 generic_xdp_tx(skb, xdp_prog);
694
695 return 0;
696}
697
698static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
699 struct sk_buff *skb,
700 struct bpf_prog *xdp_prog)
701{
702 struct sk_buff *nskb;
703 int err;
704
705 nskb = skb_clone(skb, GFP_ATOMIC);
706 if (!nskb)
707 return -ENOMEM;
708
709 err = dev_map_generic_redirect(dst, nskb, xdp_prog);
710 if (unlikely(err)) {
711 consume_skb(nskb);
712 return err;
713 }
714
715 return 0;
716}
717
718int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
719 struct bpf_prog *xdp_prog, struct bpf_map *map,
720 bool exclude_ingress)
721{
722 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
723 struct bpf_dtab_netdev *dst, *last_dst = NULL;
724 int excluded_devices[1+MAX_NEST_DEV];
725 struct hlist_head *head;
726 struct hlist_node *next;
727 int num_excluded = 0;
728 unsigned int i;
729 int err;
730
731 if (exclude_ingress) {
732 num_excluded = get_upper_ifindexes(dev, excluded_devices);
733 excluded_devices[num_excluded++] = dev->ifindex;
734 }
735
736 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
737 for (i = 0; i < map->max_entries; i++) {
738 dst = rcu_dereference_check(dtab->netdev_map[i],
739 rcu_read_lock_bh_held());
740 if (!dst)
741 continue;
742
743 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
744 continue;
745
746 /* we only need n-1 clones; last_dst enqueued below */
747 if (!last_dst) {
748 last_dst = dst;
749 continue;
750 }
751
752 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
753 if (err)
754 return err;
755
756 last_dst = dst;
757
758 }
759 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
760 for (i = 0; i < dtab->n_buckets; i++) {
761 head = dev_map_index_hash(dtab, i);
762 hlist_for_each_entry_safe(dst, next, head, index_hlist) {
763 if (!dst)
764 continue;
765
766 if (is_ifindex_excluded(excluded_devices, num_excluded,
767 dst->dev->ifindex))
768 continue;
769
770 /* we only need n-1 clones; last_dst enqueued below */
771 if (!last_dst) {
772 last_dst = dst;
773 continue;
774 }
775
776 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
777 if (err)
778 return err;
779
780 last_dst = dst;
781 }
782 }
783 }
784
785 /* consume the first skb and return */
786 if (last_dst)
787 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
788
789 /* dtab is empty */
790 consume_skb(skb);
791 return 0;
792}
793
794static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
795{
796 struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
797
798 return obj ? &obj->val : NULL;
799}
800
801static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
802{
803 struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
804 *(u32 *)key);
805 return obj ? &obj->val : NULL;
806}
807
808static void __dev_map_entry_free(struct rcu_head *rcu)
809{
810 struct bpf_dtab_netdev *dev;
811
812 dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
813 if (dev->xdp_prog)
814 bpf_prog_put(dev->xdp_prog);
815 dev_put(dev->dev);
816 kfree(dev);
817}
818
819static long dev_map_delete_elem(struct bpf_map *map, void *key)
820{
821 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
822 struct bpf_dtab_netdev *old_dev;
823 int k = *(u32 *)key;
824
825 if (k >= map->max_entries)
826 return -EINVAL;
827
828 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
829 if (old_dev) {
830 call_rcu(&old_dev->rcu, __dev_map_entry_free);
831 atomic_dec((atomic_t *)&dtab->items);
832 }
833 return 0;
834}
835
836static long dev_map_hash_delete_elem(struct bpf_map *map, void *key)
837{
838 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
839 struct bpf_dtab_netdev *old_dev;
840 int k = *(u32 *)key;
841 unsigned long flags;
842 int ret = -ENOENT;
843
844 spin_lock_irqsave(&dtab->index_lock, flags);
845
846 old_dev = __dev_map_hash_lookup_elem(map, k);
847 if (old_dev) {
848 dtab->items--;
849 hlist_del_init_rcu(&old_dev->index_hlist);
850 call_rcu(&old_dev->rcu, __dev_map_entry_free);
851 ret = 0;
852 }
853 spin_unlock_irqrestore(&dtab->index_lock, flags);
854
855 return ret;
856}
857
858static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
859 struct bpf_dtab *dtab,
860 struct bpf_devmap_val *val,
861 unsigned int idx)
862{
863 struct bpf_prog *prog = NULL;
864 struct bpf_dtab_netdev *dev;
865
866 dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
867 GFP_NOWAIT | __GFP_NOWARN,
868 dtab->map.numa_node);
869 if (!dev)
870 return ERR_PTR(-ENOMEM);
871
872 dev->dev = dev_get_by_index(net, val->ifindex);
873 if (!dev->dev)
874 goto err_out;
875
876 if (val->bpf_prog.fd > 0) {
877 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
878 BPF_PROG_TYPE_XDP, false);
879 if (IS_ERR(prog))
880 goto err_put_dev;
881 if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
882 !bpf_prog_map_compatible(&dtab->map, prog))
883 goto err_put_prog;
884 }
885
886 dev->idx = idx;
887 if (prog) {
888 dev->xdp_prog = prog;
889 dev->val.bpf_prog.id = prog->aux->id;
890 } else {
891 dev->xdp_prog = NULL;
892 dev->val.bpf_prog.id = 0;
893 }
894 dev->val.ifindex = val->ifindex;
895
896 return dev;
897err_put_prog:
898 bpf_prog_put(prog);
899err_put_dev:
900 dev_put(dev->dev);
901err_out:
902 kfree(dev);
903 return ERR_PTR(-EINVAL);
904}
905
906static long __dev_map_update_elem(struct net *net, struct bpf_map *map,
907 void *key, void *value, u64 map_flags)
908{
909 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
910 struct bpf_dtab_netdev *dev, *old_dev;
911 struct bpf_devmap_val val = {};
912 u32 i = *(u32 *)key;
913
914 if (unlikely(map_flags > BPF_EXIST))
915 return -EINVAL;
916 if (unlikely(i >= dtab->map.max_entries))
917 return -E2BIG;
918 if (unlikely(map_flags == BPF_NOEXIST))
919 return -EEXIST;
920
921 /* already verified value_size <= sizeof val */
922 memcpy(&val, value, map->value_size);
923
924 if (!val.ifindex) {
925 dev = NULL;
926 /* can not specify fd if ifindex is 0 */
927 if (val.bpf_prog.fd > 0)
928 return -EINVAL;
929 } else {
930 dev = __dev_map_alloc_node(net, dtab, &val, i);
931 if (IS_ERR(dev))
932 return PTR_ERR(dev);
933 }
934
935 /* Use call_rcu() here to ensure rcu critical sections have completed
936 * Remembering the driver side flush operation will happen before the
937 * net device is removed.
938 */
939 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
940 if (old_dev)
941 call_rcu(&old_dev->rcu, __dev_map_entry_free);
942 else
943 atomic_inc((atomic_t *)&dtab->items);
944
945 return 0;
946}
947
948static long dev_map_update_elem(struct bpf_map *map, void *key, void *value,
949 u64 map_flags)
950{
951 return __dev_map_update_elem(current->nsproxy->net_ns,
952 map, key, value, map_flags);
953}
954
955static long __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
956 void *key, void *value, u64 map_flags)
957{
958 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
959 struct bpf_dtab_netdev *dev, *old_dev;
960 struct bpf_devmap_val val = {};
961 u32 idx = *(u32 *)key;
962 unsigned long flags;
963 int err = -EEXIST;
964
965 /* already verified value_size <= sizeof val */
966 memcpy(&val, value, map->value_size);
967
968 if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
969 return -EINVAL;
970
971 spin_lock_irqsave(&dtab->index_lock, flags);
972
973 old_dev = __dev_map_hash_lookup_elem(map, idx);
974 if (old_dev && (map_flags & BPF_NOEXIST))
975 goto out_err;
976
977 dev = __dev_map_alloc_node(net, dtab, &val, idx);
978 if (IS_ERR(dev)) {
979 err = PTR_ERR(dev);
980 goto out_err;
981 }
982
983 if (old_dev) {
984 hlist_del_rcu(&old_dev->index_hlist);
985 } else {
986 if (dtab->items >= dtab->map.max_entries) {
987 spin_unlock_irqrestore(&dtab->index_lock, flags);
988 call_rcu(&dev->rcu, __dev_map_entry_free);
989 return -E2BIG;
990 }
991 dtab->items++;
992 }
993
994 hlist_add_head_rcu(&dev->index_hlist,
995 dev_map_index_hash(dtab, idx));
996 spin_unlock_irqrestore(&dtab->index_lock, flags);
997
998 if (old_dev)
999 call_rcu(&old_dev->rcu, __dev_map_entry_free);
1000
1001 return 0;
1002
1003out_err:
1004 spin_unlock_irqrestore(&dtab->index_lock, flags);
1005 return err;
1006}
1007
1008static long dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
1009 u64 map_flags)
1010{
1011 return __dev_map_hash_update_elem(current->nsproxy->net_ns,
1012 map, key, value, map_flags);
1013}
1014
1015static long dev_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1016{
1017 return __bpf_xdp_redirect_map(map, ifindex, flags,
1018 BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1019 __dev_map_lookup_elem);
1020}
1021
1022static long dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1023{
1024 return __bpf_xdp_redirect_map(map, ifindex, flags,
1025 BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1026 __dev_map_hash_lookup_elem);
1027}
1028
1029static u64 dev_map_mem_usage(const struct bpf_map *map)
1030{
1031 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
1032 u64 usage = sizeof(struct bpf_dtab);
1033
1034 if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
1035 usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
1036 else
1037 usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
1038 usage += atomic_read((atomic_t *)&dtab->items) *
1039 (u64)sizeof(struct bpf_dtab_netdev);
1040 return usage;
1041}
1042
1043BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
1044const struct bpf_map_ops dev_map_ops = {
1045 .map_meta_equal = bpf_map_meta_equal,
1046 .map_alloc = dev_map_alloc,
1047 .map_free = dev_map_free,
1048 .map_get_next_key = dev_map_get_next_key,
1049 .map_lookup_elem = dev_map_lookup_elem,
1050 .map_update_elem = dev_map_update_elem,
1051 .map_delete_elem = dev_map_delete_elem,
1052 .map_check_btf = map_check_no_btf,
1053 .map_mem_usage = dev_map_mem_usage,
1054 .map_btf_id = &dev_map_btf_ids[0],
1055 .map_redirect = dev_map_redirect,
1056};
1057
1058const struct bpf_map_ops dev_map_hash_ops = {
1059 .map_meta_equal = bpf_map_meta_equal,
1060 .map_alloc = dev_map_alloc,
1061 .map_free = dev_map_free,
1062 .map_get_next_key = dev_map_hash_get_next_key,
1063 .map_lookup_elem = dev_map_hash_lookup_elem,
1064 .map_update_elem = dev_map_hash_update_elem,
1065 .map_delete_elem = dev_map_hash_delete_elem,
1066 .map_check_btf = map_check_no_btf,
1067 .map_mem_usage = dev_map_mem_usage,
1068 .map_btf_id = &dev_map_btf_ids[0],
1069 .map_redirect = dev_hash_map_redirect,
1070};
1071
1072static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
1073 struct net_device *netdev)
1074{
1075 unsigned long flags;
1076 u32 i;
1077
1078 spin_lock_irqsave(&dtab->index_lock, flags);
1079 for (i = 0; i < dtab->n_buckets; i++) {
1080 struct bpf_dtab_netdev *dev;
1081 struct hlist_head *head;
1082 struct hlist_node *next;
1083
1084 head = dev_map_index_hash(dtab, i);
1085
1086 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
1087 if (netdev != dev->dev)
1088 continue;
1089
1090 dtab->items--;
1091 hlist_del_rcu(&dev->index_hlist);
1092 call_rcu(&dev->rcu, __dev_map_entry_free);
1093 }
1094 }
1095 spin_unlock_irqrestore(&dtab->index_lock, flags);
1096}
1097
1098static int dev_map_notification(struct notifier_block *notifier,
1099 ulong event, void *ptr)
1100{
1101 struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
1102 struct bpf_dtab *dtab;
1103 int i, cpu;
1104
1105 switch (event) {
1106 case NETDEV_REGISTER:
1107 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1108 break;
1109
1110 /* will be freed in free_netdev() */
1111 netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1112 if (!netdev->xdp_bulkq)
1113 return NOTIFY_BAD;
1114
1115 for_each_possible_cpu(cpu)
1116 per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1117 break;
1118 case NETDEV_UNREGISTER:
1119 /* This rcu_read_lock/unlock pair is needed because
1120 * dev_map_list is an RCU list AND to ensure a delete
1121 * operation does not free a netdev_map entry while we
1122 * are comparing it against the netdev being unregistered.
1123 */
1124 rcu_read_lock();
1125 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
1126 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
1127 dev_map_hash_remove_netdev(dtab, netdev);
1128 continue;
1129 }
1130
1131 for (i = 0; i < dtab->map.max_entries; i++) {
1132 struct bpf_dtab_netdev *dev, *odev;
1133
1134 dev = rcu_dereference(dtab->netdev_map[i]);
1135 if (!dev || netdev != dev->dev)
1136 continue;
1137 odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1138 if (dev == odev) {
1139 call_rcu(&dev->rcu,
1140 __dev_map_entry_free);
1141 atomic_dec((atomic_t *)&dtab->items);
1142 }
1143 }
1144 }
1145 rcu_read_unlock();
1146 break;
1147 default:
1148 break;
1149 }
1150 return NOTIFY_OK;
1151}
1152
1153static struct notifier_block dev_map_notifier = {
1154 .notifier_call = dev_map_notification,
1155};
1156
1157static int __init dev_map_init(void)
1158{
1159 int cpu;
1160
1161 /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1162 BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1163 offsetof(struct _bpf_dtab_netdev, dev));
1164 register_netdevice_notifier(&dev_map_notifier);
1165
1166 for_each_possible_cpu(cpu)
1167 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1168 return 0;
1169}
1170
1171subsys_initcall(dev_map_init);