projects/linux·blob v5.11-rc1 · refs

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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
113 /* check sanity of attributes. 2 value sizes supported:
114 * 4 bytes: ifindex
115 * 8 bytes: ifindex + prog fd
116 */
117 if (attr->max_entries == 0 || attr->key_size != 4 ||
118 (valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
119 valsize != offsetofend(struct bpf_devmap_val, bpf_prog.fd)) ||
120 attr->map_flags & ~DEV_CREATE_FLAG_MASK)
121 return -EINVAL;
122
123 /* Lookup returns a pointer straight to dev->ifindex, so make sure the
124 * verifier prevents writes from the BPF side
125 */
126 attr->map_flags |= BPF_F_RDONLY_PROG;
127
128
129 bpf_map_init_from_attr(&dtab->map, attr);
130
131 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
132 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
133
134 if (!dtab->n_buckets) /* Overflow check */
135 return -EINVAL;
136 }
137
138 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
139 dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
140 dtab->map.numa_node);
141 if (!dtab->dev_index_head)
142 return -ENOMEM;
143
144 spin_lock_init(&dtab->index_lock);
145 } else {
146 dtab->netdev_map = bpf_map_area_alloc(dtab->map.max_entries *
147 sizeof(struct bpf_dtab_netdev *),
148 dtab->map.numa_node);
149 if (!dtab->netdev_map)
150 return -ENOMEM;
151 }
152
153 return 0;
154}
155
156static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
157{
158 struct bpf_dtab *dtab;
159 int err;
160
161 if (!capable(CAP_NET_ADMIN))
162 return ERR_PTR(-EPERM);
163
164 dtab = kzalloc(sizeof(*dtab), GFP_USER | __GFP_ACCOUNT);
165 if (!dtab)
166 return ERR_PTR(-ENOMEM);
167
168 err = dev_map_init_map(dtab, attr);
169 if (err) {
170 kfree(dtab);
171 return ERR_PTR(err);
172 }
173
174 spin_lock(&dev_map_lock);
175 list_add_tail_rcu(&dtab->list, &dev_map_list);
176 spin_unlock(&dev_map_lock);
177
178 return &dtab->map;
179}
180
181static void dev_map_free(struct bpf_map *map)
182{
183 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
184 int i;
185
186 /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
187 * so the programs (can be more than one that used this map) were
188 * disconnected from events. The following synchronize_rcu() guarantees
189 * both rcu read critical sections complete and waits for
190 * preempt-disable regions (NAPI being the relevant context here) so we
191 * are certain there will be no further reads against the netdev_map and
192 * all flush operations are complete. Flush operations can only be done
193 * from NAPI context for this reason.
194 */
195
196 spin_lock(&dev_map_lock);
197 list_del_rcu(&dtab->list);
198 spin_unlock(&dev_map_lock);
199
200 bpf_clear_redirect_map(map);
201 synchronize_rcu();
202
203 /* Make sure prior __dev_map_entry_free() have completed. */
204 rcu_barrier();
205
206 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
207 for (i = 0; i < dtab->n_buckets; i++) {
208 struct bpf_dtab_netdev *dev;
209 struct hlist_head *head;
210 struct hlist_node *next;
211
212 head = dev_map_index_hash(dtab, i);
213
214 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
215 hlist_del_rcu(&dev->index_hlist);
216 if (dev->xdp_prog)
217 bpf_prog_put(dev->xdp_prog);
218 dev_put(dev->dev);
219 kfree(dev);
220 }
221 }
222
223 bpf_map_area_free(dtab->dev_index_head);
224 } else {
225 for (i = 0; i < dtab->map.max_entries; i++) {
226 struct bpf_dtab_netdev *dev;
227
228 dev = dtab->netdev_map[i];
229 if (!dev)
230 continue;
231
232 if (dev->xdp_prog)
233 bpf_prog_put(dev->xdp_prog);
234 dev_put(dev->dev);
235 kfree(dev);
236 }
237
238 bpf_map_area_free(dtab->netdev_map);
239 }
240
241 kfree(dtab);
242}
243
244static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
245{
246 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
247 u32 index = key ? *(u32 *)key : U32_MAX;
248 u32 *next = next_key;
249
250 if (index >= dtab->map.max_entries) {
251 *next = 0;
252 return 0;
253 }
254
255 if (index == dtab->map.max_entries - 1)
256 return -ENOENT;
257 *next = index + 1;
258 return 0;
259}
260
261struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
262{
263 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
264 struct hlist_head *head = dev_map_index_hash(dtab, key);
265 struct bpf_dtab_netdev *dev;
266
267 hlist_for_each_entry_rcu(dev, head, index_hlist,
268 lockdep_is_held(&dtab->index_lock))
269 if (dev->idx == key)
270 return dev;
271
272 return NULL;
273}
274
275static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
276 void *next_key)
277{
278 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
279 u32 idx, *next = next_key;
280 struct bpf_dtab_netdev *dev, *next_dev;
281 struct hlist_head *head;
282 int i = 0;
283
284 if (!key)
285 goto find_first;
286
287 idx = *(u32 *)key;
288
289 dev = __dev_map_hash_lookup_elem(map, idx);
290 if (!dev)
291 goto find_first;
292
293 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
294 struct bpf_dtab_netdev, index_hlist);
295
296 if (next_dev) {
297 *next = next_dev->idx;
298 return 0;
299 }
300
301 i = idx & (dtab->n_buckets - 1);
302 i++;
303
304 find_first:
305 for (; i < dtab->n_buckets; i++) {
306 head = dev_map_index_hash(dtab, i);
307
308 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
309 struct bpf_dtab_netdev,
310 index_hlist);
311 if (next_dev) {
312 *next = next_dev->idx;
313 return 0;
314 }
315 }
316
317 return -ENOENT;
318}
319
320bool dev_map_can_have_prog(struct bpf_map *map)
321{
322 if ((map->map_type == BPF_MAP_TYPE_DEVMAP ||
323 map->map_type == BPF_MAP_TYPE_DEVMAP_HASH) &&
324 map->value_size != offsetofend(struct bpf_devmap_val, ifindex))
325 return true;
326
327 return false;
328}
329
330static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
331{
332 struct net_device *dev = bq->dev;
333 int sent = 0, drops = 0, err = 0;
334 int i;
335
336 if (unlikely(!bq->count))
337 return;
338
339 for (i = 0; i < bq->count; i++) {
340 struct xdp_frame *xdpf = bq->q[i];
341
342 prefetch(xdpf);
343 }
344
345 sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, flags);
346 if (sent < 0) {
347 err = sent;
348 sent = 0;
349 goto error;
350 }
351 drops = bq->count - sent;
352out:
353 bq->count = 0;
354
355 trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, drops, err);
356 bq->dev_rx = NULL;
357 __list_del_clearprev(&bq->flush_node);
358 return;
359error:
360 /* If ndo_xdp_xmit fails with an errno, no frames have been
361 * xmit'ed and it's our responsibility to them free all.
362 */
363 for (i = 0; i < bq->count; i++) {
364 struct xdp_frame *xdpf = bq->q[i];
365
366 xdp_return_frame_rx_napi(xdpf);
367 drops++;
368 }
369 goto out;
370}
371
372/* __dev_flush is called from xdp_do_flush() which _must_ be signaled
373 * from the driver before returning from its napi->poll() routine. The poll()
374 * routine is called either from busy_poll context or net_rx_action signaled
375 * from NET_RX_SOFTIRQ. Either way the poll routine must complete before the
376 * net device can be torn down. On devmap tear down we ensure the flush list
377 * is empty before completing to ensure all flush operations have completed.
378 * When drivers update the bpf program they may need to ensure any flush ops
379 * are also complete. Using synchronize_rcu or call_rcu will suffice for this
380 * because both wait for napi context to exit.
381 */
382void __dev_flush(void)
383{
384 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
385 struct xdp_dev_bulk_queue *bq, *tmp;
386
387 list_for_each_entry_safe(bq, tmp, flush_list, flush_node)
388 bq_xmit_all(bq, XDP_XMIT_FLUSH);
389}
390
391/* rcu_read_lock (from syscall and BPF contexts) ensures that if a delete and/or
392 * update happens in parallel here a dev_put wont happen until after reading the
393 * ifindex.
394 */
395struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
396{
397 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
398 struct bpf_dtab_netdev *obj;
399
400 if (key >= map->max_entries)
401 return NULL;
402
403 obj = READ_ONCE(dtab->netdev_map[key]);
404 return obj;
405}
406
407/* Runs under RCU-read-side, plus in softirq under NAPI protection.
408 * Thus, safe percpu variable access.
409 */
410static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
411 struct net_device *dev_rx)
412{
413 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
414 struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
415
416 if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
417 bq_xmit_all(bq, 0);
418
419 /* Ingress dev_rx will be the same for all xdp_frame's in
420 * bulk_queue, because bq stored per-CPU and must be flushed
421 * from net_device drivers NAPI func end.
422 */
423 if (!bq->dev_rx)
424 bq->dev_rx = dev_rx;
425
426 bq->q[bq->count++] = xdpf;
427
428 if (!bq->flush_node.prev)
429 list_add(&bq->flush_node, flush_list);
430}
431
432static inline int __xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
433 struct net_device *dev_rx)
434{
435 struct xdp_frame *xdpf;
436 int err;
437
438 if (!dev->netdev_ops->ndo_xdp_xmit)
439 return -EOPNOTSUPP;
440
441 err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
442 if (unlikely(err))
443 return err;
444
445 xdpf = xdp_convert_buff_to_frame(xdp);
446 if (unlikely(!xdpf))
447 return -EOVERFLOW;
448
449 bq_enqueue(dev, xdpf, dev_rx);
450 return 0;
451}
452
453static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
454 struct xdp_buff *xdp,
455 struct bpf_prog *xdp_prog)
456{
457 struct xdp_txq_info txq = { .dev = dev };
458 u32 act;
459
460 xdp_set_data_meta_invalid(xdp);
461 xdp->txq = &txq;
462
463 act = bpf_prog_run_xdp(xdp_prog, xdp);
464 switch (act) {
465 case XDP_PASS:
466 return xdp;
467 case XDP_DROP:
468 break;
469 default:
470 bpf_warn_invalid_xdp_action(act);
471 fallthrough;
472 case XDP_ABORTED:
473 trace_xdp_exception(dev, xdp_prog, act);
474 break;
475 }
476
477 xdp_return_buff(xdp);
478 return NULL;
479}
480
481int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
482 struct net_device *dev_rx)
483{
484 return __xdp_enqueue(dev, xdp, dev_rx);
485}
486
487int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
488 struct net_device *dev_rx)
489{
490 struct net_device *dev = dst->dev;
491
492 if (dst->xdp_prog) {
493 xdp = dev_map_run_prog(dev, xdp, dst->xdp_prog);
494 if (!xdp)
495 return 0;
496 }
497 return __xdp_enqueue(dev, xdp, dev_rx);
498}
499
500int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
501 struct bpf_prog *xdp_prog)
502{
503 int err;
504
505 err = xdp_ok_fwd_dev(dst->dev, skb->len);
506 if (unlikely(err))
507 return err;
508 skb->dev = dst->dev;
509 generic_xdp_tx(skb, xdp_prog);
510
511 return 0;
512}
513
514static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
515{
516 struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
517
518 return obj ? &obj->val : NULL;
519}
520
521static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
522{
523 struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
524 *(u32 *)key);
525 return obj ? &obj->val : NULL;
526}
527
528static void __dev_map_entry_free(struct rcu_head *rcu)
529{
530 struct bpf_dtab_netdev *dev;
531
532 dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
533 if (dev->xdp_prog)
534 bpf_prog_put(dev->xdp_prog);
535 dev_put(dev->dev);
536 kfree(dev);
537}
538
539static int dev_map_delete_elem(struct bpf_map *map, void *key)
540{
541 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
542 struct bpf_dtab_netdev *old_dev;
543 int k = *(u32 *)key;
544
545 if (k >= map->max_entries)
546 return -EINVAL;
547
548 /* Use call_rcu() here to ensure any rcu critical sections have
549 * completed as well as any flush operations because call_rcu
550 * will wait for preempt-disable region to complete, NAPI in this
551 * context. And additionally, the driver tear down ensures all
552 * soft irqs are complete before removing the net device in the
553 * case of dev_put equals zero.
554 */
555 old_dev = xchg(&dtab->netdev_map[k], NULL);
556 if (old_dev)
557 call_rcu(&old_dev->rcu, __dev_map_entry_free);
558 return 0;
559}
560
561static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
562{
563 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
564 struct bpf_dtab_netdev *old_dev;
565 int k = *(u32 *)key;
566 unsigned long flags;
567 int ret = -ENOENT;
568
569 spin_lock_irqsave(&dtab->index_lock, flags);
570
571 old_dev = __dev_map_hash_lookup_elem(map, k);
572 if (old_dev) {
573 dtab->items--;
574 hlist_del_init_rcu(&old_dev->index_hlist);
575 call_rcu(&old_dev->rcu, __dev_map_entry_free);
576 ret = 0;
577 }
578 spin_unlock_irqrestore(&dtab->index_lock, flags);
579
580 return ret;
581}
582
583static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
584 struct bpf_dtab *dtab,
585 struct bpf_devmap_val *val,
586 unsigned int idx)
587{
588 struct bpf_prog *prog = NULL;
589 struct bpf_dtab_netdev *dev;
590
591 dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
592 GFP_ATOMIC | __GFP_NOWARN,
593 dtab->map.numa_node);
594 if (!dev)
595 return ERR_PTR(-ENOMEM);
596
597 dev->dev = dev_get_by_index(net, val->ifindex);
598 if (!dev->dev)
599 goto err_out;
600
601 if (val->bpf_prog.fd > 0) {
602 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
603 BPF_PROG_TYPE_XDP, false);
604 if (IS_ERR(prog))
605 goto err_put_dev;
606 if (prog->expected_attach_type != BPF_XDP_DEVMAP)
607 goto err_put_prog;
608 }
609
610 dev->idx = idx;
611 dev->dtab = dtab;
612 if (prog) {
613 dev->xdp_prog = prog;
614 dev->val.bpf_prog.id = prog->aux->id;
615 } else {
616 dev->xdp_prog = NULL;
617 dev->val.bpf_prog.id = 0;
618 }
619 dev->val.ifindex = val->ifindex;
620
621 return dev;
622err_put_prog:
623 bpf_prog_put(prog);
624err_put_dev:
625 dev_put(dev->dev);
626err_out:
627 kfree(dev);
628 return ERR_PTR(-EINVAL);
629}
630
631static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
632 void *key, void *value, u64 map_flags)
633{
634 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
635 struct bpf_dtab_netdev *dev, *old_dev;
636 struct bpf_devmap_val val = {};
637 u32 i = *(u32 *)key;
638
639 if (unlikely(map_flags > BPF_EXIST))
640 return -EINVAL;
641 if (unlikely(i >= dtab->map.max_entries))
642 return -E2BIG;
643 if (unlikely(map_flags == BPF_NOEXIST))
644 return -EEXIST;
645
646 /* already verified value_size <= sizeof val */
647 memcpy(&val, value, map->value_size);
648
649 if (!val.ifindex) {
650 dev = NULL;
651 /* can not specify fd if ifindex is 0 */
652 if (val.bpf_prog.fd > 0)
653 return -EINVAL;
654 } else {
655 dev = __dev_map_alloc_node(net, dtab, &val, i);
656 if (IS_ERR(dev))
657 return PTR_ERR(dev);
658 }
659
660 /* Use call_rcu() here to ensure rcu critical sections have completed
661 * Remembering the driver side flush operation will happen before the
662 * net device is removed.
663 */
664 old_dev = xchg(&dtab->netdev_map[i], dev);
665 if (old_dev)
666 call_rcu(&old_dev->rcu, __dev_map_entry_free);
667
668 return 0;
669}
670
671static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
672 u64 map_flags)
673{
674 return __dev_map_update_elem(current->nsproxy->net_ns,
675 map, key, value, map_flags);
676}
677
678static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
679 void *key, void *value, u64 map_flags)
680{
681 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
682 struct bpf_dtab_netdev *dev, *old_dev;
683 struct bpf_devmap_val val = {};
684 u32 idx = *(u32 *)key;
685 unsigned long flags;
686 int err = -EEXIST;
687
688 /* already verified value_size <= sizeof val */
689 memcpy(&val, value, map->value_size);
690
691 if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
692 return -EINVAL;
693
694 spin_lock_irqsave(&dtab->index_lock, flags);
695
696 old_dev = __dev_map_hash_lookup_elem(map, idx);
697 if (old_dev && (map_flags & BPF_NOEXIST))
698 goto out_err;
699
700 dev = __dev_map_alloc_node(net, dtab, &val, idx);
701 if (IS_ERR(dev)) {
702 err = PTR_ERR(dev);
703 goto out_err;
704 }
705
706 if (old_dev) {
707 hlist_del_rcu(&old_dev->index_hlist);
708 } else {
709 if (dtab->items >= dtab->map.max_entries) {
710 spin_unlock_irqrestore(&dtab->index_lock, flags);
711 call_rcu(&dev->rcu, __dev_map_entry_free);
712 return -E2BIG;
713 }
714 dtab->items++;
715 }
716
717 hlist_add_head_rcu(&dev->index_hlist,
718 dev_map_index_hash(dtab, idx));
719 spin_unlock_irqrestore(&dtab->index_lock, flags);
720
721 if (old_dev)
722 call_rcu(&old_dev->rcu, __dev_map_entry_free);
723
724 return 0;
725
726out_err:
727 spin_unlock_irqrestore(&dtab->index_lock, flags);
728 return err;
729}
730
731static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
732 u64 map_flags)
733{
734 return __dev_map_hash_update_elem(current->nsproxy->net_ns,
735 map, key, value, map_flags);
736}
737
738static int dev_map_btf_id;
739const struct bpf_map_ops dev_map_ops = {
740 .map_meta_equal = bpf_map_meta_equal,
741 .map_alloc = dev_map_alloc,
742 .map_free = dev_map_free,
743 .map_get_next_key = dev_map_get_next_key,
744 .map_lookup_elem = dev_map_lookup_elem,
745 .map_update_elem = dev_map_update_elem,
746 .map_delete_elem = dev_map_delete_elem,
747 .map_check_btf = map_check_no_btf,
748 .map_btf_name = "bpf_dtab",
749 .map_btf_id = &dev_map_btf_id,
750};
751
752static int dev_map_hash_map_btf_id;
753const struct bpf_map_ops dev_map_hash_ops = {
754 .map_meta_equal = bpf_map_meta_equal,
755 .map_alloc = dev_map_alloc,
756 .map_free = dev_map_free,
757 .map_get_next_key = dev_map_hash_get_next_key,
758 .map_lookup_elem = dev_map_hash_lookup_elem,
759 .map_update_elem = dev_map_hash_update_elem,
760 .map_delete_elem = dev_map_hash_delete_elem,
761 .map_check_btf = map_check_no_btf,
762 .map_btf_name = "bpf_dtab",
763 .map_btf_id = &dev_map_hash_map_btf_id,
764};
765
766static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
767 struct net_device *netdev)
768{
769 unsigned long flags;
770 u32 i;
771
772 spin_lock_irqsave(&dtab->index_lock, flags);
773 for (i = 0; i < dtab->n_buckets; i++) {
774 struct bpf_dtab_netdev *dev;
775 struct hlist_head *head;
776 struct hlist_node *next;
777
778 head = dev_map_index_hash(dtab, i);
779
780 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
781 if (netdev != dev->dev)
782 continue;
783
784 dtab->items--;
785 hlist_del_rcu(&dev->index_hlist);
786 call_rcu(&dev->rcu, __dev_map_entry_free);
787 }
788 }
789 spin_unlock_irqrestore(&dtab->index_lock, flags);
790}
791
792static int dev_map_notification(struct notifier_block *notifier,
793 ulong event, void *ptr)
794{
795 struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
796 struct bpf_dtab *dtab;
797 int i, cpu;
798
799 switch (event) {
800 case NETDEV_REGISTER:
801 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
802 break;
803
804 /* will be freed in free_netdev() */
805 netdev->xdp_bulkq =
806 __alloc_percpu_gfp(sizeof(struct xdp_dev_bulk_queue),
807 sizeof(void *), GFP_ATOMIC);
808 if (!netdev->xdp_bulkq)
809 return NOTIFY_BAD;
810
811 for_each_possible_cpu(cpu)
812 per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
813 break;
814 case NETDEV_UNREGISTER:
815 /* This rcu_read_lock/unlock pair is needed because
816 * dev_map_list is an RCU list AND to ensure a delete
817 * operation does not free a netdev_map entry while we
818 * are comparing it against the netdev being unregistered.
819 */
820 rcu_read_lock();
821 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
822 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
823 dev_map_hash_remove_netdev(dtab, netdev);
824 continue;
825 }
826
827 for (i = 0; i < dtab->map.max_entries; i++) {
828 struct bpf_dtab_netdev *dev, *odev;
829
830 dev = READ_ONCE(dtab->netdev_map[i]);
831 if (!dev || netdev != dev->dev)
832 continue;
833 odev = cmpxchg(&dtab->netdev_map[i], dev, NULL);
834 if (dev == odev)
835 call_rcu(&dev->rcu,
836 __dev_map_entry_free);
837 }
838 }
839 rcu_read_unlock();
840 break;
841 default:
842 break;
843 }
844 return NOTIFY_OK;
845}
846
847static struct notifier_block dev_map_notifier = {
848 .notifier_call = dev_map_notification,
849};
850
851static int __init dev_map_init(void)
852{
853 int cpu;
854
855 /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
856 BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
857 offsetof(struct _bpf_dtab_netdev, dev));
858 register_netdevice_notifier(&dev_map_notifier);
859
860 for_each_possible_cpu(cpu)
861 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
862 return 0;
863}
864
865subsys_initcall(dev_map_init);