1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
3 */
4
5 /* Devmaps primary use is as a backend map for XDP BPF helper call
6 * bpf_redirect_map(). Because XDP is mostly concerned with performance we
7 * spent some effort to ensure the datapath with redirect maps does not use
8 * any locking. This is a quick note on the details.
9 *
10 * We have three possible paths to get into the devmap control plane bpf
11 * syscalls, bpf programs, and driver side xmit/flush operations. A bpf syscall
12 * will invoke an update, delete, or lookup operation. To ensure updates and
13 * deletes appear atomic from the datapath side xchg() is used to modify the
14 * netdev_map array. Then because the datapath does a lookup into the netdev_map
15 * array (read-only) from an RCU critical section we use call_rcu() to wait for
16 * an rcu grace period before free'ing the old data structures. This ensures the
17 * datapath always has a valid copy. However, the datapath does a "flush"
18 * operation that pushes any pending packets in the driver outside the RCU
19 * critical section. Each bpf_dtab_netdev tracks these pending operations using
20 * a per-cpu flush list. The bpf_dtab_netdev object will not be destroyed until
21 * this list is empty, indicating outstanding flush operations have completed.
22 *
23 * BPF syscalls may race with BPF program calls on any of the update, delete
24 * or lookup operations. As noted above the xchg() operation also keep the
25 * netdev_map consistent in this case. From the devmap side BPF programs
26 * calling into these operations are the same as multiple user space threads
27 * making system calls.
28 *
29 * Finally, any of the above may race with a netdev_unregister notifier. The
30 * unregister notifier must search for net devices in the map structure that
31 * contain a reference to the net device and remove them. This is a two step
32 * process (a) dereference the bpf_dtab_netdev object in netdev_map and (b)
33 * check to see if the ifindex is the same as the net_device being removed.
34 * When removing the dev a cmpxchg() is used to ensure the correct dev is
35 * removed, in the case of a concurrent update or delete operation it is
36 * possible that the initially referenced dev is no longer in the map. As the
37 * notifier hook walks the map we know that new dev references can not be
38 * added by the user because core infrastructure ensures dev_get_by_index()
39 * calls will fail at this point.
40 *
41 * The devmap_hash type is a map type which interprets keys as ifindexes and
42 * indexes these using a hashmap. This allows maps that use ifindex as key to be
43 * densely packed instead of having holes in the lookup array for unused
44 * ifindexes. The setup and packet enqueue/send code is shared between the two
45 * types of devmap; only the lookup and insertion is different.
46 */
47 #include <linux/bpf.h>
48 #include <net/xdp.h>
49 #include <linux/filter.h>
50 #include <trace/events/xdp.h>
51 #include <linux/btf_ids.h>
52
53 #define DEV_CREATE_FLAG_MASK \
54 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
55
56 struct xdp_dev_bulk_queue {
57 struct xdp_frame *q[DEV_MAP_BULK_SIZE];
58 struct list_head flush_node;
59 struct net_device *dev;
60 struct net_device *dev_rx;
61 struct bpf_prog *xdp_prog;
62 unsigned int count;
63 };
64
65 struct bpf_dtab_netdev {
66 struct net_device *dev; /* must be first member, due to tracepoint */
67 struct hlist_node index_hlist;
68 struct bpf_prog *xdp_prog;
69 struct rcu_head rcu;
70 unsigned int idx;
71 struct bpf_devmap_val val;
72 };
73
74 struct bpf_dtab {
75 struct bpf_map map;
76 struct bpf_dtab_netdev __rcu **netdev_map; /* DEVMAP type only */
77 struct list_head list;
78
79 /* these are only used for DEVMAP_HASH type maps */
80 struct hlist_head *dev_index_head;
81 spinlock_t index_lock;
82 unsigned int items;
83 u32 n_buckets;
84 };
85
86 static DEFINE_SPINLOCK(dev_map_lock);
87 static LIST_HEAD(dev_map_list);
88
89 static 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((u64) 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
103 static 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
109 static int dev_map_alloc_check(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 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
124 /* Hash table size must be power of 2; roundup_pow_of_two()
125 * can overflow into UB on 32-bit arches
126 */
127 if (attr->max_entries > 1UL << 31)
128 return -EINVAL;
129 }
130
131 return 0;
132 }
133
134 static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
135 {
136 /* Lookup returns a pointer straight to dev->ifindex, so make sure the
137 * verifier prevents writes from the BPF side
138 */
139 attr->map_flags |= BPF_F_RDONLY_PROG;
140 bpf_map_init_from_attr(&dtab->map, attr);
141
142 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
143 /* Hash table size must be power of 2 */
144 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
145 dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
146 dtab->map.numa_node);
147 if (!dtab->dev_index_head)
148 return -ENOMEM;
149
150 spin_lock_init(&dtab->index_lock);
151 } else {
152 dtab->netdev_map = bpf_map_area_alloc((u64) dtab->map.max_entries *
153 sizeof(struct bpf_dtab_netdev *),
154 dtab->map.numa_node);
155 if (!dtab->netdev_map)
156 return -ENOMEM;
157 }
158
159 return 0;
160 }
161
162 static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
163 {
164 struct bpf_dtab *dtab;
165 int err;
166
167 dtab = bpf_map_area_alloc(sizeof(*dtab), NUMA_NO_NODE);
168 if (!dtab)
169 return ERR_PTR(-ENOMEM);
170
171 err = dev_map_init_map(dtab, attr);
172 if (err) {
173 bpf_map_area_free(dtab);
174 return ERR_PTR(err);
175 }
176
177 spin_lock(&dev_map_lock);
178 list_add_tail_rcu(&dtab->list, &dev_map_list);
179 spin_unlock(&dev_map_lock);
180
181 return &dtab->map;
182 }
183
184 static void dev_map_free(struct bpf_map *map)
185 {
186 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
187 int i;
188
189 /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
190 * so the programs (can be more than one that used this map) were
191 * disconnected from events. The following synchronize_rcu() guarantees
192 * both rcu read critical sections complete and waits for
193 * preempt-disable regions (NAPI being the relevant context here) so we
194 * are certain there will be no further reads against the netdev_map and
195 * all flush operations are complete. Flush operations can only be done
196 * from NAPI context for this reason.
197 */
198
199 spin_lock(&dev_map_lock);
200 list_del_rcu(&dtab->list);
201 spin_unlock(&dev_map_lock);
202
203 /* bpf_redirect_info->map is assigned in __bpf_xdp_redirect_map()
204 * during NAPI callback and cleared after the XDP redirect. There is no
205 * explicit RCU read section which protects bpf_redirect_info->map but
206 * local_bh_disable() also marks the beginning an RCU section. This
207 * makes the complete softirq callback RCU protected. Thus after
208 * following synchronize_rcu() there no bpf_redirect_info->map == map
209 * assignment.
210 */
211 synchronize_rcu();
212
213 /* Make sure prior __dev_map_entry_free() have completed. */
214 rcu_barrier();
215
216 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
217 for (i = 0; i < dtab->n_buckets; i++) {
218 struct bpf_dtab_netdev *dev;
219 struct hlist_head *head;
220 struct hlist_node *next;
221
222 head = dev_map_index_hash(dtab, i);
223
224 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
225 hlist_del_rcu(&dev->index_hlist);
226 if (dev->xdp_prog)
227 bpf_prog_put(dev->xdp_prog);
228 dev_put(dev->dev);
229 kfree(dev);
230 }
231 }
232
233 bpf_map_area_free(dtab->dev_index_head);
234 } else {
235 for (i = 0; i < dtab->map.max_entries; i++) {
236 struct bpf_dtab_netdev *dev;
237
238 dev = rcu_dereference_raw(dtab->netdev_map[i]);
239 if (!dev)
240 continue;
241
242 if (dev->xdp_prog)
243 bpf_prog_put(dev->xdp_prog);
244 dev_put(dev->dev);
245 kfree(dev);
246 }
247
248 bpf_map_area_free(dtab->netdev_map);
249 }
250
251 bpf_map_area_free(dtab);
252 }
253
254 static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
255 {
256 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
257 u32 index = key ? *(u32 *)key : U32_MAX;
258 u32 *next = next_key;
259
260 if (index >= dtab->map.max_entries) {
261 *next = 0;
262 return 0;
263 }
264
265 if (index == dtab->map.max_entries - 1)
266 return -ENOENT;
267 *next = index + 1;
268 return 0;
269 }
270
271 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
272 * by local_bh_disable() (from XDP calls inside NAPI). The
273 * rcu_read_lock_bh_held() below makes lockdep accept both.
274 */
275 static void *__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
289 static 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
334 static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
335 struct xdp_frame **frames, int n,
336 struct net_device *dev)
337 {
338 struct xdp_txq_info txq = { .dev = dev };
339 struct xdp_buff xdp;
340 int i, nframes = 0;
341
342 for (i = 0; i < n; i++) {
343 struct xdp_frame *xdpf = frames[i];
344 u32 act;
345 int err;
346
347 xdp_convert_frame_to_buff(xdpf, &xdp);
348 xdp.txq = &txq;
349
350 act = bpf_prog_run_xdp(xdp_prog, &xdp);
351 switch (act) {
352 case XDP_PASS:
353 err = xdp_update_frame_from_buff(&xdp, xdpf);
354 if (unlikely(err < 0))
355 xdp_return_frame_rx_napi(xdpf);
356 else
357 frames[nframes++] = xdpf;
358 break;
359 default:
360 bpf_warn_invalid_xdp_action(NULL, xdp_prog, act);
361 fallthrough;
362 case XDP_ABORTED:
363 trace_xdp_exception(dev, xdp_prog, act);
364 fallthrough;
365 case XDP_DROP:
366 xdp_return_frame_rx_napi(xdpf);
367 break;
368 }
369 }
370 return nframes; /* sent frames count */
371 }
372
373 static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
374 {
375 struct net_device *dev = bq->dev;
376 unsigned int cnt = bq->count;
377 int sent = 0, err = 0;
378 int to_send = cnt;
379 int i;
380
381 if (unlikely(!cnt))
382 return;
383
384 for (i = 0; i < cnt; i++) {
385 struct xdp_frame *xdpf = bq->q[i];
386
387 prefetch(xdpf);
388 }
389
390 if (bq->xdp_prog) {
391 to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
392 if (!to_send)
393 goto out;
394 }
395
396 sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
397 if (sent < 0) {
398 /* If ndo_xdp_xmit fails with an errno, no frames have
399 * been xmit'ed.
400 */
401 err = sent;
402 sent = 0;
403 }
404
405 /* If not all frames have been transmitted, it is our
406 * responsibility to free them
407 */
408 for (i = sent; unlikely(i < to_send); i++)
409 xdp_return_frame_rx_napi(bq->q[i]);
410
411 out:
412 bq->count = 0;
413 trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
414 }
415
416 /* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
417 * driver before returning from its napi->poll() routine. See the comment above
418 * xdp_do_flush() in filter.c.
419 */
420 void __dev_flush(struct list_head *flush_list)
421 {
422 struct xdp_dev_bulk_queue *bq, *tmp;
423
424 list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
425 bq_xmit_all(bq, XDP_XMIT_FLUSH);
426 bq->dev_rx = NULL;
427 bq->xdp_prog = NULL;
428 __list_del_clearprev(&bq->flush_node);
429 }
430 }
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 */
436 static 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 */
453 static 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 xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
457
458 if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
459 bq_xmit_all(bq, 0);
460
461 /* Ingress dev_rx will be the same for all xdp_frame's in
462 * bulk_queue, because bq stored per-CPU and must be flushed
463 * from net_device drivers NAPI func end.
464 *
465 * Do the same with xdp_prog and flush_list since these fields
466 * are only ever modified together.
467 */
468 if (!bq->dev_rx) {
469 struct list_head *flush_list = bpf_net_ctx_get_dev_flush_list();
470
471 bq->dev_rx = dev_rx;
472 bq->xdp_prog = xdp_prog;
473 list_add(&bq->flush_node, flush_list);
474 }
475
476 bq->q[bq->count++] = xdpf;
477 }
478
479 static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
480 struct net_device *dev_rx,
481 struct bpf_prog *xdp_prog)
482 {
483 int err;
484
485 if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
486 return -EOPNOTSUPP;
487
488 if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
489 xdp_frame_has_frags(xdpf)))
490 return -EOPNOTSUPP;
491
492 err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
493 if (unlikely(err))
494 return err;
495
496 bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
497 return 0;
498 }
499
500 static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
501 {
502 struct xdp_txq_info txq = { .dev = dst->dev };
503 struct xdp_buff xdp;
504 u32 act;
505
506 if (!dst->xdp_prog)
507 return XDP_PASS;
508
509 __skb_pull(skb, skb->mac_len);
510 xdp.txq = &txq;
511
512 act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
513 switch (act) {
514 case XDP_PASS:
515 __skb_push(skb, skb->mac_len);
516 break;
517 default:
518 bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
519 fallthrough;
520 case XDP_ABORTED:
521 trace_xdp_exception(dst->dev, dst->xdp_prog, act);
522 fallthrough;
523 case XDP_DROP:
524 kfree_skb(skb);
525 break;
526 }
527
528 return act;
529 }
530
531 int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
532 struct net_device *dev_rx)
533 {
534 return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
535 }
536
537 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
538 struct net_device *dev_rx)
539 {
540 struct net_device *dev = dst->dev;
541
542 return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
543 }
544
545 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
546 {
547 if (!obj)
548 return false;
549
550 if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
551 return false;
552
553 if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
554 xdp_frame_has_frags(xdpf)))
555 return false;
556
557 if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
558 return false;
559
560 return true;
561 }
562
563 static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
564 struct net_device *dev_rx,
565 struct xdp_frame *xdpf)
566 {
567 struct xdp_frame *nxdpf;
568
569 nxdpf = xdpf_clone(xdpf);
570 if (!nxdpf)
571 return -ENOMEM;
572
573 bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
574
575 return 0;
576 }
577
578 static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
579 {
580 while (num_excluded--) {
581 if (ifindex == excluded[num_excluded])
582 return true;
583 }
584 return false;
585 }
586
587 /* Get ifindex of each upper device. 'indexes' must be able to hold at
588 * least MAX_NEST_DEV elements.
589 * Returns the number of ifindexes added.
590 */
591 static int get_upper_ifindexes(struct net_device *dev, int *indexes)
592 {
593 struct net_device *upper;
594 struct list_head *iter;
595 int n = 0;
596
597 netdev_for_each_upper_dev_rcu(dev, upper, iter) {
598 indexes[n++] = upper->ifindex;
599 }
600 return n;
601 }
602
603 int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
604 struct bpf_map *map, bool exclude_ingress)
605 {
606 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
607 struct bpf_dtab_netdev *dst, *last_dst = NULL;
608 int excluded_devices[1+MAX_NEST_DEV];
609 struct hlist_head *head;
610 int num_excluded = 0;
611 unsigned int i;
612 int err;
613
614 if (exclude_ingress) {
615 num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
616 excluded_devices[num_excluded++] = dev_rx->ifindex;
617 }
618
619 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
620 for (i = 0; i < map->max_entries; i++) {
621 dst = rcu_dereference_check(dtab->netdev_map[i],
622 rcu_read_lock_bh_held());
623 if (!is_valid_dst(dst, xdpf))
624 continue;
625
626 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
627 continue;
628
629 /* we only need n-1 clones; last_dst enqueued below */
630 if (!last_dst) {
631 last_dst = dst;
632 continue;
633 }
634
635 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
636 if (err)
637 return err;
638
639 last_dst = dst;
640 }
641 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
642 for (i = 0; i < dtab->n_buckets; i++) {
643 head = dev_map_index_hash(dtab, i);
644 hlist_for_each_entry_rcu(dst, head, index_hlist,
645 lockdep_is_held(&dtab->index_lock)) {
646 if (!is_valid_dst(dst, xdpf))
647 continue;
648
649 if (is_ifindex_excluded(excluded_devices, num_excluded,
650 dst->dev->ifindex))
651 continue;
652
653 /* we only need n-1 clones; last_dst enqueued below */
654 if (!last_dst) {
655 last_dst = dst;
656 continue;
657 }
658
659 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
660 if (err)
661 return err;
662
663 last_dst = dst;
664 }
665 }
666 }
667
668 /* consume the last copy of the frame */
669 if (last_dst)
670 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
671 else
672 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
673
674 return 0;
675 }
676
677 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
678 struct bpf_prog *xdp_prog)
679 {
680 int err;
681
682 err = xdp_ok_fwd_dev(dst->dev, skb->len);
683 if (unlikely(err))
684 return err;
685
686 /* Redirect has already succeeded semantically at this point, so we just
687 * return 0 even if packet is dropped. Helper below takes care of
688 * freeing skb.
689 */
690 if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
691 return 0;
692
693 skb->dev = dst->dev;
694 generic_xdp_tx(skb, xdp_prog);
695
696 return 0;
697 }
698
699 static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
700 struct sk_buff *skb,
701 struct bpf_prog *xdp_prog)
702 {
703 struct sk_buff *nskb;
704 int err;
705
706 nskb = skb_clone(skb, GFP_ATOMIC);
707 if (!nskb)
708 return -ENOMEM;
709
710 err = dev_map_generic_redirect(dst, nskb, xdp_prog);
711 if (unlikely(err)) {
712 consume_skb(nskb);
713 return err;
714 }
715
716 return 0;
717 }
718
719 int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
720 struct bpf_prog *xdp_prog, struct bpf_map *map,
721 bool exclude_ingress)
722 {
723 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
724 struct bpf_dtab_netdev *dst, *last_dst = NULL;
725 int excluded_devices[1+MAX_NEST_DEV];
726 struct hlist_head *head;
727 struct hlist_node *next;
728 int num_excluded = 0;
729 unsigned int i;
730 int err;
731
732 if (exclude_ingress) {
733 num_excluded = get_upper_ifindexes(dev, excluded_devices);
734 excluded_devices[num_excluded++] = dev->ifindex;
735 }
736
737 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
738 for (i = 0; i < map->max_entries; i++) {
739 dst = rcu_dereference_check(dtab->netdev_map[i],
740 rcu_read_lock_bh_held());
741 if (!dst)
742 continue;
743
744 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
745 continue;
746
747 /* we only need n-1 clones; last_dst enqueued below */
748 if (!last_dst) {
749 last_dst = dst;
750 continue;
751 }
752
753 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
754 if (err)
755 return err;
756
757 last_dst = dst;
758
759 }
760 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
761 for (i = 0; i < dtab->n_buckets; i++) {
762 head = dev_map_index_hash(dtab, i);
763 hlist_for_each_entry_safe(dst, next, head, index_hlist) {
764 if (is_ifindex_excluded(excluded_devices, num_excluded,
765 dst->dev->ifindex))
766 continue;
767
768 /* we only need n-1 clones; last_dst enqueued below */
769 if (!last_dst) {
770 last_dst = dst;
771 continue;
772 }
773
774 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
775 if (err)
776 return err;
777
778 last_dst = dst;
779 }
780 }
781 }
782
783 /* consume the first skb and return */
784 if (last_dst)
785 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
786
787 /* dtab is empty */
788 consume_skb(skb);
789 return 0;
790 }
791
792 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
793 {
794 struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
795
796 return obj ? &obj->val : NULL;
797 }
798
799 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
800 {
801 struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
802 *(u32 *)key);
803 return obj ? &obj->val : NULL;
804 }
805
806 static void __dev_map_entry_free(struct rcu_head *rcu)
807 {
808 struct bpf_dtab_netdev *dev;
809
810 dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
811 if (dev->xdp_prog)
812 bpf_prog_put(dev->xdp_prog);
813 dev_put(dev->dev);
814 kfree(dev);
815 }
816
817 static long dev_map_delete_elem(struct bpf_map *map, void *key)
818 {
819 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
820 struct bpf_dtab_netdev *old_dev;
821 int k = *(u32 *)key;
822
823 if (k >= map->max_entries)
824 return -EINVAL;
825
826 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
827 if (old_dev) {
828 call_rcu(&old_dev->rcu, __dev_map_entry_free);
829 atomic_dec((atomic_t *)&dtab->items);
830 }
831 return 0;
832 }
833
834 static long dev_map_hash_delete_elem(struct bpf_map *map, void *key)
835 {
836 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
837 struct bpf_dtab_netdev *old_dev;
838 int k = *(u32 *)key;
839 unsigned long flags;
840 int ret = -ENOENT;
841
842 spin_lock_irqsave(&dtab->index_lock, flags);
843
844 old_dev = __dev_map_hash_lookup_elem(map, k);
845 if (old_dev) {
846 dtab->items--;
847 hlist_del_init_rcu(&old_dev->index_hlist);
848 call_rcu(&old_dev->rcu, __dev_map_entry_free);
849 ret = 0;
850 }
851 spin_unlock_irqrestore(&dtab->index_lock, flags);
852
853 return ret;
854 }
855
856 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
857 struct bpf_dtab *dtab,
858 struct bpf_devmap_val *val,
859 unsigned int idx)
860 {
861 struct bpf_prog *prog = NULL;
862 struct bpf_dtab_netdev *dev;
863
864 dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
865 GFP_NOWAIT | __GFP_NOWARN,
866 dtab->map.numa_node);
867 if (!dev)
868 return ERR_PTR(-ENOMEM);
869
870 dev->dev = dev_get_by_index(net, val->ifindex);
871 if (!dev->dev)
872 goto err_out;
873
874 if (val->bpf_prog.fd > 0) {
875 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
876 BPF_PROG_TYPE_XDP, false);
877 if (IS_ERR(prog))
878 goto err_put_dev;
879 if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
880 !bpf_prog_map_compatible(&dtab->map, prog))
881 goto err_put_prog;
882 }
883
884 dev->idx = idx;
885 if (prog) {
886 dev->xdp_prog = prog;
887 dev->val.bpf_prog.id = prog->aux->id;
888 } else {
889 dev->xdp_prog = NULL;
890 dev->val.bpf_prog.id = 0;
891 }
892 dev->val.ifindex = val->ifindex;
893
894 return dev;
895 err_put_prog:
896 bpf_prog_put(prog);
897 err_put_dev:
898 dev_put(dev->dev);
899 err_out:
900 kfree(dev);
901 return ERR_PTR(-EINVAL);
902 }
903
904 static long __dev_map_update_elem(struct net *net, struct bpf_map *map,
905 void *key, void *value, u64 map_flags)
906 {
907 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
908 struct bpf_dtab_netdev *dev, *old_dev;
909 struct bpf_devmap_val val = {};
910 u32 i = *(u32 *)key;
911
912 if (unlikely(map_flags > BPF_EXIST))
913 return -EINVAL;
914 if (unlikely(i >= dtab->map.max_entries))
915 return -E2BIG;
916 if (unlikely(map_flags == BPF_NOEXIST))
917 return -EEXIST;
918
919 /* already verified value_size <= sizeof val */
920 memcpy(&val, value, map->value_size);
921
922 if (!val.ifindex) {
923 dev = NULL;
924 /* can not specify fd if ifindex is 0 */
925 if (val.bpf_prog.fd > 0)
926 return -EINVAL;
927 } else {
928 dev = __dev_map_alloc_node(net, dtab, &val, i);
929 if (IS_ERR(dev))
930 return PTR_ERR(dev);
931 }
932
933 /* Use call_rcu() here to ensure rcu critical sections have completed
934 * Remembering the driver side flush operation will happen before the
935 * net device is removed.
936 */
937 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
938 if (old_dev)
939 call_rcu(&old_dev->rcu, __dev_map_entry_free);
940 else
941 atomic_inc((atomic_t *)&dtab->items);
942
943 return 0;
944 }
945
946 static long dev_map_update_elem(struct bpf_map *map, void *key, void *value,
947 u64 map_flags)
948 {
949 return __dev_map_update_elem(current->nsproxy->net_ns,
950 map, key, value, map_flags);
951 }
952
953 static long __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
954 void *key, void *value, u64 map_flags)
955 {
956 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
957 struct bpf_dtab_netdev *dev, *old_dev;
958 struct bpf_devmap_val val = {};
959 u32 idx = *(u32 *)key;
960 unsigned long flags;
961 int err = -EEXIST;
962
963 /* already verified value_size <= sizeof val */
964 memcpy(&val, value, map->value_size);
965
966 if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
967 return -EINVAL;
968
969 spin_lock_irqsave(&dtab->index_lock, flags);
970
971 old_dev = __dev_map_hash_lookup_elem(map, idx);
972 if (old_dev && (map_flags & BPF_NOEXIST))
973 goto out_err;
974
975 dev = __dev_map_alloc_node(net, dtab, &val, idx);
976 if (IS_ERR(dev)) {
977 err = PTR_ERR(dev);
978 goto out_err;
979 }
980
981 if (old_dev) {
982 hlist_del_rcu(&old_dev->index_hlist);
983 } else {
984 if (dtab->items >= dtab->map.max_entries) {
985 spin_unlock_irqrestore(&dtab->index_lock, flags);
986 call_rcu(&dev->rcu, __dev_map_entry_free);
987 return -E2BIG;
988 }
989 dtab->items++;
990 }
991
992 hlist_add_head_rcu(&dev->index_hlist,
993 dev_map_index_hash(dtab, idx));
994 spin_unlock_irqrestore(&dtab->index_lock, flags);
995
996 if (old_dev)
997 call_rcu(&old_dev->rcu, __dev_map_entry_free);
998
999 return 0;
1000
1001 out_err:
1002 spin_unlock_irqrestore(&dtab->index_lock, flags);
1003 return err;
1004 }
1005
1006 static long dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
1007 u64 map_flags)
1008 {
1009 return __dev_map_hash_update_elem(current->nsproxy->net_ns,
1010 map, key, value, map_flags);
1011 }
1012
1013 static long dev_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_lookup_elem);
1018 }
1019
1020 static long dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1021 {
1022 return __bpf_xdp_redirect_map(map, ifindex, flags,
1023 BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1024 __dev_map_hash_lookup_elem);
1025 }
1026
1027 static u64 dev_map_mem_usage(const struct bpf_map *map)
1028 {
1029 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
1030 u64 usage = sizeof(struct bpf_dtab);
1031
1032 if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
1033 usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
1034 else
1035 usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
1036 usage += atomic_read((atomic_t *)&dtab->items) *
1037 (u64)sizeof(struct bpf_dtab_netdev);
1038 return usage;
1039 }
1040
1041 BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
1042 const struct bpf_map_ops dev_map_ops = {
1043 .map_meta_equal = bpf_map_meta_equal,
1044 .map_alloc_check = dev_map_alloc_check,
1045 .map_alloc = dev_map_alloc,
1046 .map_free = dev_map_free,
1047 .map_get_next_key = dev_map_get_next_key,
1048 .map_lookup_elem = dev_map_lookup_elem,
1049 .map_update_elem = dev_map_update_elem,
1050 .map_delete_elem = dev_map_delete_elem,
1051 .map_check_btf = map_check_no_btf,
1052 .map_mem_usage = dev_map_mem_usage,
1053 .map_btf_id = &dev_map_btf_ids[0],
1054 .map_redirect = dev_map_redirect,
1055 };
1056
1057 const struct bpf_map_ops dev_map_hash_ops = {
1058 .map_meta_equal = bpf_map_meta_equal,
1059 .map_alloc_check = dev_map_alloc_check,
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
1072 static 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
1098 static 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
1153 static struct notifier_block dev_map_notifier = {
1154 .notifier_call = dev_map_notification,
1155 };
1156
1157 static int __init dev_map_init(void)
1158 {
1159 /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1160 BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1161 offsetof(struct _bpf_dtab_netdev, dev));
1162 register_netdevice_notifier(&dev_map_notifier);
1163
1164 return 0;
1165 }
1166
1167 subsys_initcall(dev_map_init);
1168
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