projects/linux·blob v6.5 · 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#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_dtab *dtab;
69 struct bpf_prog *xdp_prog;
70 struct rcu_head rcu;
71 unsigned int idx;
72 struct bpf_devmap_val val;
73};
74
75struct bpf_dtab {
76 struct bpf_map map;
77 struct bpf_dtab_netdev __rcu **netdev_map; /* DEVMAP type only */
78 struct list_head list;
79
80 /* these are only used for DEVMAP_HASH type maps */
81 struct hlist_head *dev_index_head;
82 spinlock_t index_lock;
83 unsigned int items;
84 u32 n_buckets;
85};
86
87static DEFINE_PER_CPU(struct list_head, dev_flush_list);
88static DEFINE_SPINLOCK(dev_map_lock);
89static LIST_HEAD(dev_map_list);
90
91static struct hlist_head *dev_map_create_hash(unsigned int entries,
92 int numa_node)
93{
94 int i;
95 struct hlist_head *hash;
96
97 hash = bpf_map_area_alloc((u64) entries * sizeof(*hash), numa_node);
98 if (hash != NULL)
99 for (i = 0; i < entries; i++)
100 INIT_HLIST_HEAD(&hash[i]);
101
102 return hash;
103}
104
105static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
106 int idx)
107{
108 return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
109}
110
111static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
112{
113 u32 valsize = attr->value_size;
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 }
139
140 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
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/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
423 * by local_bh_disable() (from XDP calls inside NAPI). The
424 * rcu_read_lock_bh_held() below makes lockdep accept both.
425 */
426static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
427{
428 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
429 struct bpf_dtab_netdev *obj;
430
431 if (key >= map->max_entries)
432 return NULL;
433
434 obj = rcu_dereference_check(dtab->netdev_map[key],
435 rcu_read_lock_bh_held());
436 return obj;
437}
438
439/* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
440 * variable access, and map elements stick around. See comment above
441 * xdp_do_flush() in filter.c.
442 */
443static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
444 struct net_device *dev_rx, struct bpf_prog *xdp_prog)
445{
446 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
447 struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
448
449 if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
450 bq_xmit_all(bq, 0);
451
452 /* Ingress dev_rx will be the same for all xdp_frame's in
453 * bulk_queue, because bq stored per-CPU and must be flushed
454 * from net_device drivers NAPI func end.
455 *
456 * Do the same with xdp_prog and flush_list since these fields
457 * are only ever modified together.
458 */
459 if (!bq->dev_rx) {
460 bq->dev_rx = dev_rx;
461 bq->xdp_prog = xdp_prog;
462 list_add(&bq->flush_node, flush_list);
463 }
464
465 bq->q[bq->count++] = xdpf;
466}
467
468static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
469 struct net_device *dev_rx,
470 struct bpf_prog *xdp_prog)
471{
472 int err;
473
474 if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
475 return -EOPNOTSUPP;
476
477 if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
478 xdp_frame_has_frags(xdpf)))
479 return -EOPNOTSUPP;
480
481 err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
482 if (unlikely(err))
483 return err;
484
485 bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
486 return 0;
487}
488
489static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
490{
491 struct xdp_txq_info txq = { .dev = dst->dev };
492 struct xdp_buff xdp;
493 u32 act;
494
495 if (!dst->xdp_prog)
496 return XDP_PASS;
497
498 __skb_pull(skb, skb->mac_len);
499 xdp.txq = &txq;
500
501 act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
502 switch (act) {
503 case XDP_PASS:
504 __skb_push(skb, skb->mac_len);
505 break;
506 default:
507 bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
508 fallthrough;
509 case XDP_ABORTED:
510 trace_xdp_exception(dst->dev, dst->xdp_prog, act);
511 fallthrough;
512 case XDP_DROP:
513 kfree_skb(skb);
514 break;
515 }
516
517 return act;
518}
519
520int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
521 struct net_device *dev_rx)
522{
523 return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
524}
525
526int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
527 struct net_device *dev_rx)
528{
529 struct net_device *dev = dst->dev;
530
531 return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
532}
533
534static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
535{
536 if (!obj)
537 return false;
538
539 if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
540 return false;
541
542 if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
543 xdp_frame_has_frags(xdpf)))
544 return false;
545
546 if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
547 return false;
548
549 return true;
550}
551
552static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
553 struct net_device *dev_rx,
554 struct xdp_frame *xdpf)
555{
556 struct xdp_frame *nxdpf;
557
558 nxdpf = xdpf_clone(xdpf);
559 if (!nxdpf)
560 return -ENOMEM;
561
562 bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
563
564 return 0;
565}
566
567static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
568{
569 while (num_excluded--) {
570 if (ifindex == excluded[num_excluded])
571 return true;
572 }
573 return false;
574}
575
576/* Get ifindex of each upper device. 'indexes' must be able to hold at
577 * least MAX_NEST_DEV elements.
578 * Returns the number of ifindexes added.
579 */
580static int get_upper_ifindexes(struct net_device *dev, int *indexes)
581{
582 struct net_device *upper;
583 struct list_head *iter;
584 int n = 0;
585
586 netdev_for_each_upper_dev_rcu(dev, upper, iter) {
587 indexes[n++] = upper->ifindex;
588 }
589 return n;
590}
591
592int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
593 struct bpf_map *map, bool exclude_ingress)
594{
595 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
596 struct bpf_dtab_netdev *dst, *last_dst = NULL;
597 int excluded_devices[1+MAX_NEST_DEV];
598 struct hlist_head *head;
599 int num_excluded = 0;
600 unsigned int i;
601 int err;
602
603 if (exclude_ingress) {
604 num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
605 excluded_devices[num_excluded++] = dev_rx->ifindex;
606 }
607
608 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
609 for (i = 0; i < map->max_entries; i++) {
610 dst = rcu_dereference_check(dtab->netdev_map[i],
611 rcu_read_lock_bh_held());
612 if (!is_valid_dst(dst, xdpf))
613 continue;
614
615 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
616 continue;
617
618 /* we only need n-1 clones; last_dst enqueued below */
619 if (!last_dst) {
620 last_dst = dst;
621 continue;
622 }
623
624 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
625 if (err)
626 return err;
627
628 last_dst = dst;
629 }
630 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
631 for (i = 0; i < dtab->n_buckets; i++) {
632 head = dev_map_index_hash(dtab, i);
633 hlist_for_each_entry_rcu(dst, head, index_hlist,
634 lockdep_is_held(&dtab->index_lock)) {
635 if (!is_valid_dst(dst, xdpf))
636 continue;
637
638 if (is_ifindex_excluded(excluded_devices, num_excluded,
639 dst->dev->ifindex))
640 continue;
641
642 /* we only need n-1 clones; last_dst enqueued below */
643 if (!last_dst) {
644 last_dst = dst;
645 continue;
646 }
647
648 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
649 if (err)
650 return err;
651
652 last_dst = dst;
653 }
654 }
655 }
656
657 /* consume the last copy of the frame */
658 if (last_dst)
659 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
660 else
661 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
662
663 return 0;
664}
665
666int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
667 struct bpf_prog *xdp_prog)
668{
669 int err;
670
671 err = xdp_ok_fwd_dev(dst->dev, skb->len);
672 if (unlikely(err))
673 return err;
674
675 /* Redirect has already succeeded semantically at this point, so we just
676 * return 0 even if packet is dropped. Helper below takes care of
677 * freeing skb.
678 */
679 if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
680 return 0;
681
682 skb->dev = dst->dev;
683 generic_xdp_tx(skb, xdp_prog);
684
685 return 0;
686}
687
688static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
689 struct sk_buff *skb,
690 struct bpf_prog *xdp_prog)
691{
692 struct sk_buff *nskb;
693 int err;
694
695 nskb = skb_clone(skb, GFP_ATOMIC);
696 if (!nskb)
697 return -ENOMEM;
698
699 err = dev_map_generic_redirect(dst, nskb, xdp_prog);
700 if (unlikely(err)) {
701 consume_skb(nskb);
702 return err;
703 }
704
705 return 0;
706}
707
708int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
709 struct bpf_prog *xdp_prog, struct bpf_map *map,
710 bool exclude_ingress)
711{
712 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
713 struct bpf_dtab_netdev *dst, *last_dst = NULL;
714 int excluded_devices[1+MAX_NEST_DEV];
715 struct hlist_head *head;
716 struct hlist_node *next;
717 int num_excluded = 0;
718 unsigned int i;
719 int err;
720
721 if (exclude_ingress) {
722 num_excluded = get_upper_ifindexes(dev, excluded_devices);
723 excluded_devices[num_excluded++] = dev->ifindex;
724 }
725
726 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
727 for (i = 0; i < map->max_entries; i++) {
728 dst = rcu_dereference_check(dtab->netdev_map[i],
729 rcu_read_lock_bh_held());
730 if (!dst)
731 continue;
732
733 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
734 continue;
735
736 /* we only need n-1 clones; last_dst enqueued below */
737 if (!last_dst) {
738 last_dst = dst;
739 continue;
740 }
741
742 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
743 if (err)
744 return err;
745
746 last_dst = dst;
747
748 }
749 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
750 for (i = 0; i < dtab->n_buckets; i++) {
751 head = dev_map_index_hash(dtab, i);
752 hlist_for_each_entry_safe(dst, next, head, index_hlist) {
753 if (!dst)
754 continue;
755
756 if (is_ifindex_excluded(excluded_devices, num_excluded,
757 dst->dev->ifindex))
758 continue;
759
760 /* we only need n-1 clones; last_dst enqueued below */
761 if (!last_dst) {
762 last_dst = dst;
763 continue;
764 }
765
766 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
767 if (err)
768 return err;
769
770 last_dst = dst;
771 }
772 }
773 }
774
775 /* consume the first skb and return */
776 if (last_dst)
777 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
778
779 /* dtab is empty */
780 consume_skb(skb);
781 return 0;
782}
783
784static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
785{
786 struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
787
788 return obj ? &obj->val : NULL;
789}
790
791static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
792{
793 struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
794 *(u32 *)key);
795 return obj ? &obj->val : NULL;
796}
797
798static void __dev_map_entry_free(struct rcu_head *rcu)
799{
800 struct bpf_dtab_netdev *dev;
801
802 dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
803 if (dev->xdp_prog)
804 bpf_prog_put(dev->xdp_prog);
805 dev_put(dev->dev);
806 kfree(dev);
807}
808
809static long dev_map_delete_elem(struct bpf_map *map, void *key)
810{
811 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
812 struct bpf_dtab_netdev *old_dev;
813 int k = *(u32 *)key;
814
815 if (k >= map->max_entries)
816 return -EINVAL;
817
818 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
819 if (old_dev) {
820 call_rcu(&old_dev->rcu, __dev_map_entry_free);
821 atomic_dec((atomic_t *)&dtab->items);
822 }
823 return 0;
824}
825
826static long dev_map_hash_delete_elem(struct bpf_map *map, void *key)
827{
828 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
829 struct bpf_dtab_netdev *old_dev;
830 int k = *(u32 *)key;
831 unsigned long flags;
832 int ret = -ENOENT;
833
834 spin_lock_irqsave(&dtab->index_lock, flags);
835
836 old_dev = __dev_map_hash_lookup_elem(map, k);
837 if (old_dev) {
838 dtab->items--;
839 hlist_del_init_rcu(&old_dev->index_hlist);
840 call_rcu(&old_dev->rcu, __dev_map_entry_free);
841 ret = 0;
842 }
843 spin_unlock_irqrestore(&dtab->index_lock, flags);
844
845 return ret;
846}
847
848static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
849 struct bpf_dtab *dtab,
850 struct bpf_devmap_val *val,
851 unsigned int idx)
852{
853 struct bpf_prog *prog = NULL;
854 struct bpf_dtab_netdev *dev;
855
856 dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
857 GFP_NOWAIT | __GFP_NOWARN,
858 dtab->map.numa_node);
859 if (!dev)
860 return ERR_PTR(-ENOMEM);
861
862 dev->dev = dev_get_by_index(net, val->ifindex);
863 if (!dev->dev)
864 goto err_out;
865
866 if (val->bpf_prog.fd > 0) {
867 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
868 BPF_PROG_TYPE_XDP, false);
869 if (IS_ERR(prog))
870 goto err_put_dev;
871 if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
872 !bpf_prog_map_compatible(&dtab->map, prog))
873 goto err_put_prog;
874 }
875
876 dev->idx = idx;
877 dev->dtab = dtab;
878 if (prog) {
879 dev->xdp_prog = prog;
880 dev->val.bpf_prog.id = prog->aux->id;
881 } else {
882 dev->xdp_prog = NULL;
883 dev->val.bpf_prog.id = 0;
884 }
885 dev->val.ifindex = val->ifindex;
886
887 return dev;
888err_put_prog:
889 bpf_prog_put(prog);
890err_put_dev:
891 dev_put(dev->dev);
892err_out:
893 kfree(dev);
894 return ERR_PTR(-EINVAL);
895}
896
897static long __dev_map_update_elem(struct net *net, struct bpf_map *map,
898 void *key, void *value, u64 map_flags)
899{
900 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
901 struct bpf_dtab_netdev *dev, *old_dev;
902 struct bpf_devmap_val val = {};
903 u32 i = *(u32 *)key;
904
905 if (unlikely(map_flags > BPF_EXIST))
906 return -EINVAL;
907 if (unlikely(i >= dtab->map.max_entries))
908 return -E2BIG;
909 if (unlikely(map_flags == BPF_NOEXIST))
910 return -EEXIST;
911
912 /* already verified value_size <= sizeof val */
913 memcpy(&val, value, map->value_size);
914
915 if (!val.ifindex) {
916 dev = NULL;
917 /* can not specify fd if ifindex is 0 */
918 if (val.bpf_prog.fd > 0)
919 return -EINVAL;
920 } else {
921 dev = __dev_map_alloc_node(net, dtab, &val, i);
922 if (IS_ERR(dev))
923 return PTR_ERR(dev);
924 }
925
926 /* Use call_rcu() here to ensure rcu critical sections have completed
927 * Remembering the driver side flush operation will happen before the
928 * net device is removed.
929 */
930 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
931 if (old_dev)
932 call_rcu(&old_dev->rcu, __dev_map_entry_free);
933 else
934 atomic_inc((atomic_t *)&dtab->items);
935
936 return 0;
937}
938
939static long dev_map_update_elem(struct bpf_map *map, void *key, void *value,
940 u64 map_flags)
941{
942 return __dev_map_update_elem(current->nsproxy->net_ns,
943 map, key, value, map_flags);
944}
945
946static long __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
947 void *key, void *value, u64 map_flags)
948{
949 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
950 struct bpf_dtab_netdev *dev, *old_dev;
951 struct bpf_devmap_val val = {};
952 u32 idx = *(u32 *)key;
953 unsigned long flags;
954 int err = -EEXIST;
955
956 /* already verified value_size <= sizeof val */
957 memcpy(&val, value, map->value_size);
958
959 if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
960 return -EINVAL;
961
962 spin_lock_irqsave(&dtab->index_lock, flags);
963
964 old_dev = __dev_map_hash_lookup_elem(map, idx);
965 if (old_dev && (map_flags & BPF_NOEXIST))
966 goto out_err;
967
968 dev = __dev_map_alloc_node(net, dtab, &val, idx);
969 if (IS_ERR(dev)) {
970 err = PTR_ERR(dev);
971 goto out_err;
972 }
973
974 if (old_dev) {
975 hlist_del_rcu(&old_dev->index_hlist);
976 } else {
977 if (dtab->items >= dtab->map.max_entries) {
978 spin_unlock_irqrestore(&dtab->index_lock, flags);
979 call_rcu(&dev->rcu, __dev_map_entry_free);
980 return -E2BIG;
981 }
982 dtab->items++;
983 }
984
985 hlist_add_head_rcu(&dev->index_hlist,
986 dev_map_index_hash(dtab, idx));
987 spin_unlock_irqrestore(&dtab->index_lock, flags);
988
989 if (old_dev)
990 call_rcu(&old_dev->rcu, __dev_map_entry_free);
991
992 return 0;
993
994out_err:
995 spin_unlock_irqrestore(&dtab->index_lock, flags);
996 return err;
997}
998
999static long dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
1000 u64 map_flags)
1001{
1002 return __dev_map_hash_update_elem(current->nsproxy->net_ns,
1003 map, key, value, map_flags);
1004}
1005
1006static long dev_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1007{
1008 return __bpf_xdp_redirect_map(map, ifindex, flags,
1009 BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1010 __dev_map_lookup_elem);
1011}
1012
1013static long dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1014{
1015 return __bpf_xdp_redirect_map(map, ifindex, flags,
1016 BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1017 __dev_map_hash_lookup_elem);
1018}
1019
1020static u64 dev_map_mem_usage(const struct bpf_map *map)
1021{
1022 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
1023 u64 usage = sizeof(struct bpf_dtab);
1024
1025 if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
1026 usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
1027 else
1028 usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
1029 usage += atomic_read((atomic_t *)&dtab->items) *
1030 (u64)sizeof(struct bpf_dtab_netdev);
1031 return usage;
1032}
1033
1034BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
1035const struct bpf_map_ops dev_map_ops = {
1036 .map_meta_equal = bpf_map_meta_equal,
1037 .map_alloc = dev_map_alloc,
1038 .map_free = dev_map_free,
1039 .map_get_next_key = dev_map_get_next_key,
1040 .map_lookup_elem = dev_map_lookup_elem,
1041 .map_update_elem = dev_map_update_elem,
1042 .map_delete_elem = dev_map_delete_elem,
1043 .map_check_btf = map_check_no_btf,
1044 .map_mem_usage = dev_map_mem_usage,
1045 .map_btf_id = &dev_map_btf_ids[0],
1046 .map_redirect = dev_map_redirect,
1047};
1048
1049const struct bpf_map_ops dev_map_hash_ops = {
1050 .map_meta_equal = bpf_map_meta_equal,
1051 .map_alloc = dev_map_alloc,
1052 .map_free = dev_map_free,
1053 .map_get_next_key = dev_map_hash_get_next_key,
1054 .map_lookup_elem = dev_map_hash_lookup_elem,
1055 .map_update_elem = dev_map_hash_update_elem,
1056 .map_delete_elem = dev_map_hash_delete_elem,
1057 .map_check_btf = map_check_no_btf,
1058 .map_mem_usage = dev_map_mem_usage,
1059 .map_btf_id = &dev_map_btf_ids[0],
1060 .map_redirect = dev_hash_map_redirect,
1061};
1062
1063static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
1064 struct net_device *netdev)
1065{
1066 unsigned long flags;
1067 u32 i;
1068
1069 spin_lock_irqsave(&dtab->index_lock, flags);
1070 for (i = 0; i < dtab->n_buckets; i++) {
1071 struct bpf_dtab_netdev *dev;
1072 struct hlist_head *head;
1073 struct hlist_node *next;
1074
1075 head = dev_map_index_hash(dtab, i);
1076
1077 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
1078 if (netdev != dev->dev)
1079 continue;
1080
1081 dtab->items--;
1082 hlist_del_rcu(&dev->index_hlist);
1083 call_rcu(&dev->rcu, __dev_map_entry_free);
1084 }
1085 }
1086 spin_unlock_irqrestore(&dtab->index_lock, flags);
1087}
1088
1089static int dev_map_notification(struct notifier_block *notifier,
1090 ulong event, void *ptr)
1091{
1092 struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
1093 struct bpf_dtab *dtab;
1094 int i, cpu;
1095
1096 switch (event) {
1097 case NETDEV_REGISTER:
1098 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1099 break;
1100
1101 /* will be freed in free_netdev() */
1102 netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1103 if (!netdev->xdp_bulkq)
1104 return NOTIFY_BAD;
1105
1106 for_each_possible_cpu(cpu)
1107 per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1108 break;
1109 case NETDEV_UNREGISTER:
1110 /* This rcu_read_lock/unlock pair is needed because
1111 * dev_map_list is an RCU list AND to ensure a delete
1112 * operation does not free a netdev_map entry while we
1113 * are comparing it against the netdev being unregistered.
1114 */
1115 rcu_read_lock();
1116 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
1117 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
1118 dev_map_hash_remove_netdev(dtab, netdev);
1119 continue;
1120 }
1121
1122 for (i = 0; i < dtab->map.max_entries; i++) {
1123 struct bpf_dtab_netdev *dev, *odev;
1124
1125 dev = rcu_dereference(dtab->netdev_map[i]);
1126 if (!dev || netdev != dev->dev)
1127 continue;
1128 odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1129 if (dev == odev) {
1130 call_rcu(&dev->rcu,
1131 __dev_map_entry_free);
1132 atomic_dec((atomic_t *)&dtab->items);
1133 }
1134 }
1135 }
1136 rcu_read_unlock();
1137 break;
1138 default:
1139 break;
1140 }
1141 return NOTIFY_OK;
1142}
1143
1144static struct notifier_block dev_map_notifier = {
1145 .notifier_call = dev_map_notification,
1146};
1147
1148static int __init dev_map_init(void)
1149{
1150 int cpu;
1151
1152 /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1153 BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1154 offsetof(struct _bpf_dtab_netdev, dev));
1155 register_netdevice_notifier(&dev_map_notifier);
1156
1157 for_each_possible_cpu(cpu)
1158 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1159 return 0;
1160}
1161
1162subsys_initcall(dev_map_init);