1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
3 */
4
5/* Devmaps primary use is as a backend map for XDP BPF helper call
6 * bpf_redirect_map(). Because XDP is mostly concerned with performance we
7 * spent some effort to ensure the datapath with redirect maps does not use
8 * any locking. This is a quick note on the details.
9 *
10 * We have three possible paths to get into the devmap control plane bpf
11 * syscalls, bpf programs, and driver side xmit/flush operations. A bpf syscall
12 * will invoke an update, delete, or lookup operation. To ensure updates and
13 * deletes appear atomic from the datapath side xchg() is used to modify the
14 * netdev_map array. Then because the datapath does a lookup into the netdev_map
15 * array (read-only) from an RCU critical section we use call_rcu() to wait for
16 * an rcu grace period before free'ing the old data structures. This ensures the
17 * datapath always has a valid copy. However, the datapath does a "flush"
18 * operation that pushes any pending packets in the driver outside the RCU
19 * critical section. Each bpf_dtab_netdev tracks these pending operations using
20 * a per-cpu flush list. The bpf_dtab_netdev object will not be destroyed until
21 * this list is empty, indicating outstanding flush operations have completed.
22 *
23 * BPF syscalls may race with BPF program calls on any of the update, delete
24 * or lookup operations. As noted above the xchg() operation also keep the
25 * netdev_map consistent in this case. From the devmap side BPF programs
26 * calling into these operations are the same as multiple user space threads
27 * making system calls.
28 *
29 * Finally, any of the above may race with a netdev_unregister notifier. The
30 * unregister notifier must search for net devices in the map structure that
31 * contain a reference to the net device and remove them. This is a two step
32 * process (a) dereference the bpf_dtab_netdev object in netdev_map and (b)
33 * check to see if the ifindex is the same as the net_device being removed.
34 * When removing the dev a cmpxchg() is used to ensure the correct dev is
35 * removed, in the case of a concurrent update or delete operation it is
36 * possible that the initially referenced dev is no longer in the map. As the
37 * notifier hook walks the map we know that new dev references can not be
38 * added by the user because core infrastructure ensures dev_get_by_index()
39 * calls will fail at this point.
40 *
41 * The devmap_hash type is a map type which interprets keys as ifindexes and
42 * indexes these using a hashmap. This allows maps that use ifindex as key to be
43 * densely packed instead of having holes in the lookup array for unused
44 * ifindexes. The setup and packet enqueue/send code is shared between the two
45 * types of devmap; only the lookup and insertion is different.
46 */
47#include <linux/bpf.h>
48#include <net/xdp.h>
49#include <linux/filter.h>
50#include <trace/events/xdp.h>
51#include <linux/btf_ids.h>
52
53#define DEV_CREATE_FLAG_MASK \
54 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
55
56struct xdp_dev_bulk_queue {
57 struct xdp_frame *q[DEV_MAP_BULK_SIZE];
58 struct list_head flush_node;
59 struct net_device *dev;
60 struct net_device *dev_rx;
61 struct bpf_prog *xdp_prog;
62 unsigned int count;
63};
64
65struct bpf_dtab_netdev {
66 struct net_device *dev; /* must be first member, due to tracepoint */
67 struct hlist_node index_hlist;
68 struct bpf_prog *xdp_prog;
69 struct rcu_head rcu;
70 unsigned int idx;
71 struct bpf_devmap_val val;
72};
73
74struct bpf_dtab {
75 struct bpf_map map;
76 struct bpf_dtab_netdev __rcu **netdev_map; /* DEVMAP type only */
77 struct list_head list;
78
79 /* these are only used for DEVMAP_HASH type maps */
80 struct hlist_head *dev_index_head;
81 spinlock_t index_lock;
82 unsigned int items;
83 u32 n_buckets;
84};
85
86static DEFINE_PER_CPU(struct list_head, dev_flush_list);
87static DEFINE_SPINLOCK(dev_map_lock);
88static LIST_HEAD(dev_map_list);
89
90static struct hlist_head *dev_map_create_hash(unsigned int entries,
91 int numa_node)
92{
93 int i;
94 struct hlist_head *hash;
95
96 hash = bpf_map_area_alloc(size: (u64) entries * sizeof(*hash), numa_node);
97 if (hash != NULL)
98 for (i = 0; i < entries; i++)
99 INIT_HLIST_HEAD(&hash[i]);
100
101 return hash;
102}
103
104static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
105 int idx)
106{
107 return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
108}
109
110static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
111{
112 u32 valsize = attr->value_size;
113
114 /* check sanity of attributes. 2 value sizes supported:
115 * 4 bytes: ifindex
116 * 8 bytes: ifindex + prog fd
117 */
118 if (attr->max_entries == 0 || attr->key_size != 4 ||
119 (valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
120 valsize != offsetofend(struct bpf_devmap_val, bpf_prog.fd)) ||
121 attr->map_flags & ~DEV_CREATE_FLAG_MASK)
122 return -EINVAL;
123
124 /* Lookup returns a pointer straight to dev->ifindex, so make sure the
125 * verifier prevents writes from the BPF side
126 */
127 attr->map_flags |= BPF_F_RDONLY_PROG;
128
129
130 bpf_map_init_from_attr(map: &dtab->map, attr);
131
132 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
133 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
134
135 if (!dtab->n_buckets) /* Overflow check */
136 return -EINVAL;
137 }
138
139 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
140 dtab->dev_index_head = dev_map_create_hash(entries: dtab->n_buckets,
141 numa_node: dtab->map.numa_node);
142 if (!dtab->dev_index_head)
143 return -ENOMEM;
144
145 spin_lock_init(&dtab->index_lock);
146 } else {
147 dtab->netdev_map = bpf_map_area_alloc(size: (u64) dtab->map.max_entries *
148 sizeof(struct bpf_dtab_netdev *),
149 numa_node: dtab->map.numa_node);
150 if (!dtab->netdev_map)
151 return -ENOMEM;
152 }
153
154 return 0;
155}
156
157static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
158{
159 struct bpf_dtab *dtab;
160 int err;
161
162 dtab = bpf_map_area_alloc(size: sizeof(*dtab), NUMA_NO_NODE);
163 if (!dtab)
164 return ERR_PTR(error: -ENOMEM);
165
166 err = dev_map_init_map(dtab, attr);
167 if (err) {
168 bpf_map_area_free(base: dtab);
169 return ERR_PTR(error: err);
170 }
171
172 spin_lock(lock: &dev_map_lock);
173 list_add_tail_rcu(new: &dtab->list, head: &dev_map_list);
174 spin_unlock(lock: &dev_map_lock);
175
176 return &dtab->map;
177}
178
179static void dev_map_free(struct bpf_map *map)
180{
181 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
182 int i;
183
184 /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
185 * so the programs (can be more than one that used this map) were
186 * disconnected from events. The following synchronize_rcu() guarantees
187 * both rcu read critical sections complete and waits for
188 * preempt-disable regions (NAPI being the relevant context here) so we
189 * are certain there will be no further reads against the netdev_map and
190 * all flush operations are complete. Flush operations can only be done
191 * from NAPI context for this reason.
192 */
193
194 spin_lock(lock: &dev_map_lock);
195 list_del_rcu(entry: &dtab->list);
196 spin_unlock(lock: &dev_map_lock);
197
198 bpf_clear_redirect_map(map);
199 synchronize_rcu();
200
201 /* Make sure prior __dev_map_entry_free() have completed. */
202 rcu_barrier();
203
204 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
205 for (i = 0; i < dtab->n_buckets; i++) {
206 struct bpf_dtab_netdev *dev;
207 struct hlist_head *head;
208 struct hlist_node *next;
209
210 head = dev_map_index_hash(dtab, idx: i);
211
212 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
213 hlist_del_rcu(n: &dev->index_hlist);
214 if (dev->xdp_prog)
215 bpf_prog_put(prog: dev->xdp_prog);
216 dev_put(dev: dev->dev);
217 kfree(objp: dev);
218 }
219 }
220
221 bpf_map_area_free(base: dtab->dev_index_head);
222 } else {
223 for (i = 0; i < dtab->map.max_entries; i++) {
224 struct bpf_dtab_netdev *dev;
225
226 dev = rcu_dereference_raw(dtab->netdev_map[i]);
227 if (!dev)
228 continue;
229
230 if (dev->xdp_prog)
231 bpf_prog_put(prog: dev->xdp_prog);
232 dev_put(dev: dev->dev);
233 kfree(objp: dev);
234 }
235
236 bpf_map_area_free(base: dtab->netdev_map);
237 }
238
239 bpf_map_area_free(base: dtab);
240}
241
242static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
243{
244 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
245 u32 index = key ? *(u32 *)key : U32_MAX;
246 u32 *next = next_key;
247
248 if (index >= dtab->map.max_entries) {
249 *next = 0;
250 return 0;
251 }
252
253 if (index == dtab->map.max_entries - 1)
254 return -ENOENT;
255 *next = index + 1;
256 return 0;
257}
258
259/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
260 * by local_bh_disable() (from XDP calls inside NAPI). The
261 * rcu_read_lock_bh_held() below makes lockdep accept both.
262 */
263static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
264{
265 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
266 struct hlist_head *head = dev_map_index_hash(dtab, idx: key);
267 struct bpf_dtab_netdev *dev;
268
269 hlist_for_each_entry_rcu(dev, head, index_hlist,
270 lockdep_is_held(&dtab->index_lock))
271 if (dev->idx == key)
272 return dev;
273
274 return NULL;
275}
276
277static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
278 void *next_key)
279{
280 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
281 u32 idx, *next = next_key;
282 struct bpf_dtab_netdev *dev, *next_dev;
283 struct hlist_head *head;
284 int i = 0;
285
286 if (!key)
287 goto find_first;
288
289 idx = *(u32 *)key;
290
291 dev = __dev_map_hash_lookup_elem(map, key: idx);
292 if (!dev)
293 goto find_first;
294
295 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
296 struct bpf_dtab_netdev, index_hlist);
297
298 if (next_dev) {
299 *next = next_dev->idx;
300 return 0;
301 }
302
303 i = idx & (dtab->n_buckets - 1);
304 i++;
305
306 find_first:
307 for (; i < dtab->n_buckets; i++) {
308 head = dev_map_index_hash(dtab, idx: i);
309
310 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
311 struct bpf_dtab_netdev,
312 index_hlist);
313 if (next_dev) {
314 *next = next_dev->idx;
315 return 0;
316 }
317 }
318
319 return -ENOENT;
320}
321
322static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
323 struct xdp_frame **frames, int n,
324 struct net_device *dev)
325{
326 struct xdp_txq_info txq = { .dev = dev };
327 struct xdp_buff xdp;
328 int i, nframes = 0;
329
330 for (i = 0; i < n; i++) {
331 struct xdp_frame *xdpf = frames[i];
332 u32 act;
333 int err;
334
335 xdp_convert_frame_to_buff(frame: xdpf, xdp: &xdp);
336 xdp.txq = &txq;
337
338 act = bpf_prog_run_xdp(prog: xdp_prog, xdp: &xdp);
339 switch (act) {
340 case XDP_PASS:
341 err = xdp_update_frame_from_buff(xdp: &xdp, xdp_frame: xdpf);
342 if (unlikely(err < 0))
343 xdp_return_frame_rx_napi(xdpf);
344 else
345 frames[nframes++] = xdpf;
346 break;
347 default:
348 bpf_warn_invalid_xdp_action(NULL, prog: xdp_prog, act);
349 fallthrough;
350 case XDP_ABORTED:
351 trace_xdp_exception(dev, xdp: xdp_prog, act);
352 fallthrough;
353 case XDP_DROP:
354 xdp_return_frame_rx_napi(xdpf);
355 break;
356 }
357 }
358 return nframes; /* sent frames count */
359}
360
361static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
362{
363 struct net_device *dev = bq->dev;
364 unsigned int cnt = bq->count;
365 int sent = 0, err = 0;
366 int to_send = cnt;
367 int i;
368
369 if (unlikely(!cnt))
370 return;
371
372 for (i = 0; i < cnt; i++) {
373 struct xdp_frame *xdpf = bq->q[i];
374
375 prefetch(xdpf);
376 }
377
378 if (bq->xdp_prog) {
379 to_send = dev_map_bpf_prog_run(xdp_prog: bq->xdp_prog, frames: bq->q, n: cnt, dev);
380 if (!to_send)
381 goto out;
382 }
383
384 sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
385 if (sent < 0) {
386 /* If ndo_xdp_xmit fails with an errno, no frames have
387 * been xmit'ed.
388 */
389 err = sent;
390 sent = 0;
391 }
392
393 /* If not all frames have been transmitted, it is our
394 * responsibility to free them
395 */
396 for (i = sent; unlikely(i < to_send); i++)
397 xdp_return_frame_rx_napi(xdpf: bq->q[i]);
398
399out:
400 bq->count = 0;
401 trace_xdp_devmap_xmit(from_dev: bq->dev_rx, to_dev: dev, sent, drops: cnt - sent, err);
402}
403
404/* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
405 * driver before returning from its napi->poll() routine. See the comment above
406 * xdp_do_flush() in filter.c.
407 */
408void __dev_flush(void)
409{
410 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
411 struct xdp_dev_bulk_queue *bq, *tmp;
412
413 list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
414 bq_xmit_all(bq, XDP_XMIT_FLUSH);
415 bq->dev_rx = NULL;
416 bq->xdp_prog = NULL;
417 __list_del_clearprev(entry: &bq->flush_node);
418 }
419}
420
421#ifdef CONFIG_DEBUG_NET
422bool dev_check_flush(void)
423{
424 if (list_empty(this_cpu_ptr(&dev_flush_list)))
425 return false;
426 __dev_flush();
427 return true;
428}
429#endif
430
431/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
432 * by local_bh_disable() (from XDP calls inside NAPI). The
433 * rcu_read_lock_bh_held() below makes lockdep accept both.
434 */
435static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
436{
437 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
438 struct bpf_dtab_netdev *obj;
439
440 if (key >= map->max_entries)
441 return NULL;
442
443 obj = rcu_dereference_check(dtab->netdev_map[key],
444 rcu_read_lock_bh_held());
445 return obj;
446}
447
448/* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
449 * variable access, and map elements stick around. See comment above
450 * xdp_do_flush() in filter.c.
451 */
452static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
453 struct net_device *dev_rx, struct bpf_prog *xdp_prog)
454{
455 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
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, flags: 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 bq->dev_rx = dev_rx;
470 bq->xdp_prog = xdp_prog;
471 list_add(new: &bq->flush_node, head: flush_list);
472 }
473
474 bq->q[bq->count++] = xdpf;
475}
476
477static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
478 struct net_device *dev_rx,
479 struct bpf_prog *xdp_prog)
480{
481 int err;
482
483 if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
484 return -EOPNOTSUPP;
485
486 if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
487 xdp_frame_has_frags(xdpf)))
488 return -EOPNOTSUPP;
489
490 err = xdp_ok_fwd_dev(fwd: dev, pktlen: xdp_get_frame_len(xdpf));
491 if (unlikely(err))
492 return err;
493
494 bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
495 return 0;
496}
497
498static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
499{
500 struct xdp_txq_info txq = { .dev = dst->dev };
501 struct xdp_buff xdp;
502 u32 act;
503
504 if (!dst->xdp_prog)
505 return XDP_PASS;
506
507 __skb_pull(skb, len: skb->mac_len);
508 xdp.txq = &txq;
509
510 act = bpf_prog_run_generic_xdp(skb, xdp: &xdp, xdp_prog: dst->xdp_prog);
511 switch (act) {
512 case XDP_PASS:
513 __skb_push(skb, len: skb->mac_len);
514 break;
515 default:
516 bpf_warn_invalid_xdp_action(NULL, prog: dst->xdp_prog, act);
517 fallthrough;
518 case XDP_ABORTED:
519 trace_xdp_exception(dev: dst->dev, xdp: dst->xdp_prog, act);
520 fallthrough;
521 case XDP_DROP:
522 kfree_skb(skb);
523 break;
524 }
525
526 return act;
527}
528
529int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
530 struct net_device *dev_rx)
531{
532 return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
533}
534
535int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
536 struct net_device *dev_rx)
537{
538 struct net_device *dev = dst->dev;
539
540 return __xdp_enqueue(dev, xdpf, dev_rx, xdp_prog: dst->xdp_prog);
541}
542
543static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
544{
545 if (!obj)
546 return false;
547
548 if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
549 return false;
550
551 if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
552 xdp_frame_has_frags(xdpf)))
553 return false;
554
555 if (xdp_ok_fwd_dev(fwd: obj->dev, pktlen: xdp_get_frame_len(xdpf)))
556 return false;
557
558 return true;
559}
560
561static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
562 struct net_device *dev_rx,
563 struct xdp_frame *xdpf)
564{
565 struct xdp_frame *nxdpf;
566
567 nxdpf = xdpf_clone(xdpf);
568 if (!nxdpf)
569 return -ENOMEM;
570
571 bq_enqueue(dev: obj->dev, xdpf: nxdpf, dev_rx, xdp_prog: obj->xdp_prog);
572
573 return 0;
574}
575
576static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
577{
578 while (num_excluded--) {
579 if (ifindex == excluded[num_excluded])
580 return true;
581 }
582 return false;
583}
584
585/* Get ifindex of each upper device. 'indexes' must be able to hold at
586 * least MAX_NEST_DEV elements.
587 * Returns the number of ifindexes added.
588 */
589static int get_upper_ifindexes(struct net_device *dev, int *indexes)
590{
591 struct net_device *upper;
592 struct list_head *iter;
593 int n = 0;
594
595 netdev_for_each_upper_dev_rcu(dev, upper, iter) {
596 indexes[n++] = upper->ifindex;
597 }
598 return n;
599}
600
601int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
602 struct bpf_map *map, bool exclude_ingress)
603{
604 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
605 struct bpf_dtab_netdev *dst, *last_dst = NULL;
606 int excluded_devices[1+MAX_NEST_DEV];
607 struct hlist_head *head;
608 int num_excluded = 0;
609 unsigned int i;
610 int err;
611
612 if (exclude_ingress) {
613 num_excluded = get_upper_ifindexes(dev: dev_rx, indexes: excluded_devices);
614 excluded_devices[num_excluded++] = dev_rx->ifindex;
615 }
616
617 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
618 for (i = 0; i < map->max_entries; i++) {
619 dst = rcu_dereference_check(dtab->netdev_map[i],
620 rcu_read_lock_bh_held());
621 if (!is_valid_dst(obj: dst, xdpf))
622 continue;
623
624 if (is_ifindex_excluded(excluded: excluded_devices, num_excluded, ifindex: dst->dev->ifindex))
625 continue;
626
627 /* we only need n-1 clones; last_dst enqueued below */
628 if (!last_dst) {
629 last_dst = dst;
630 continue;
631 }
632
633 err = dev_map_enqueue_clone(obj: last_dst, dev_rx, xdpf);
634 if (err)
635 return err;
636
637 last_dst = dst;
638 }
639 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
640 for (i = 0; i < dtab->n_buckets; i++) {
641 head = dev_map_index_hash(dtab, idx: i);
642 hlist_for_each_entry_rcu(dst, head, index_hlist,
643 lockdep_is_held(&dtab->index_lock)) {
644 if (!is_valid_dst(obj: dst, xdpf))
645 continue;
646
647 if (is_ifindex_excluded(excluded: excluded_devices, num_excluded,
648 ifindex: dst->dev->ifindex))
649 continue;
650
651 /* we only need n-1 clones; last_dst enqueued below */
652 if (!last_dst) {
653 last_dst = dst;
654 continue;
655 }
656
657 err = dev_map_enqueue_clone(obj: last_dst, dev_rx, xdpf);
658 if (err)
659 return err;
660
661 last_dst = dst;
662 }
663 }
664 }
665
666 /* consume the last copy of the frame */
667 if (last_dst)
668 bq_enqueue(dev: last_dst->dev, xdpf, dev_rx, xdp_prog: last_dst->xdp_prog);
669 else
670 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
671
672 return 0;
673}
674
675int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
676 struct bpf_prog *xdp_prog)
677{
678 int err;
679
680 err = xdp_ok_fwd_dev(fwd: dst->dev, pktlen: skb->len);
681 if (unlikely(err))
682 return err;
683
684 /* Redirect has already succeeded semantically at this point, so we just
685 * return 0 even if packet is dropped. Helper below takes care of
686 * freeing skb.
687 */
688 if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
689 return 0;
690
691 skb->dev = dst->dev;
692 generic_xdp_tx(skb, xdp_prog);
693
694 return 0;
695}
696
697static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
698 struct sk_buff *skb,
699 struct bpf_prog *xdp_prog)
700{
701 struct sk_buff *nskb;
702 int err;
703
704 nskb = skb_clone(skb, GFP_ATOMIC);
705 if (!nskb)
706 return -ENOMEM;
707
708 err = dev_map_generic_redirect(dst, skb: nskb, xdp_prog);
709 if (unlikely(err)) {
710 consume_skb(skb: nskb);
711 return err;
712 }
713
714 return 0;
715}
716
717int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
718 struct bpf_prog *xdp_prog, struct bpf_map *map,
719 bool exclude_ingress)
720{
721 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
722 struct bpf_dtab_netdev *dst, *last_dst = NULL;
723 int excluded_devices[1+MAX_NEST_DEV];
724 struct hlist_head *head;
725 struct hlist_node *next;
726 int num_excluded = 0;
727 unsigned int i;
728 int err;
729
730 if (exclude_ingress) {
731 num_excluded = get_upper_ifindexes(dev, indexes: excluded_devices);
732 excluded_devices[num_excluded++] = dev->ifindex;
733 }
734
735 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
736 for (i = 0; i < map->max_entries; i++) {
737 dst = rcu_dereference_check(dtab->netdev_map[i],
738 rcu_read_lock_bh_held());
739 if (!dst)
740 continue;
741
742 if (is_ifindex_excluded(excluded: excluded_devices, num_excluded, ifindex: dst->dev->ifindex))
743 continue;
744
745 /* we only need n-1 clones; last_dst enqueued below */
746 if (!last_dst) {
747 last_dst = dst;
748 continue;
749 }
750
751 err = dev_map_redirect_clone(dst: last_dst, skb, xdp_prog);
752 if (err)
753 return err;
754
755 last_dst = dst;
756
757 }
758 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
759 for (i = 0; i < dtab->n_buckets; i++) {
760 head = dev_map_index_hash(dtab, idx: i);
761 hlist_for_each_entry_safe(dst, next, head, index_hlist) {
762 if (!dst)
763 continue;
764
765 if (is_ifindex_excluded(excluded: excluded_devices, num_excluded,
766 ifindex: dst->dev->ifindex))
767 continue;
768
769 /* we only need n-1 clones; last_dst enqueued below */
770 if (!last_dst) {
771 last_dst = dst;
772 continue;
773 }
774
775 err = dev_map_redirect_clone(dst: last_dst, skb, xdp_prog);
776 if (err)
777 return err;
778
779 last_dst = dst;
780 }
781 }
782 }
783
784 /* consume the first skb and return */
785 if (last_dst)
786 return dev_map_generic_redirect(dst: last_dst, skb, xdp_prog);
787
788 /* dtab is empty */
789 consume_skb(skb);
790 return 0;
791}
792
793static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
794{
795 struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, key: *(u32 *)key);
796
797 return obj ? &obj->val : NULL;
798}
799
800static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
801{
802 struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
803 key: *(u32 *)key);
804 return obj ? &obj->val : NULL;
805}
806
807static void __dev_map_entry_free(struct rcu_head *rcu)
808{
809 struct bpf_dtab_netdev *dev;
810
811 dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
812 if (dev->xdp_prog)
813 bpf_prog_put(prog: dev->xdp_prog);
814 dev_put(dev: dev->dev);
815 kfree(objp: dev);
816}
817
818static long dev_map_delete_elem(struct bpf_map *map, void *key)
819{
820 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
821 struct bpf_dtab_netdev *old_dev;
822 int k = *(u32 *)key;
823
824 if (k >= map->max_entries)
825 return -EINVAL;
826
827 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
828 if (old_dev) {
829 call_rcu(head: &old_dev->rcu, func: __dev_map_entry_free);
830 atomic_dec(v: (atomic_t *)&dtab->items);
831 }
832 return 0;
833}
834
835static long dev_map_hash_delete_elem(struct bpf_map *map, void *key)
836{
837 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
838 struct bpf_dtab_netdev *old_dev;
839 int k = *(u32 *)key;
840 unsigned long flags;
841 int ret = -ENOENT;
842
843 spin_lock_irqsave(&dtab->index_lock, flags);
844
845 old_dev = __dev_map_hash_lookup_elem(map, key: k);
846 if (old_dev) {
847 dtab->items--;
848 hlist_del_init_rcu(n: &old_dev->index_hlist);
849 call_rcu(head: &old_dev->rcu, func: __dev_map_entry_free);
850 ret = 0;
851 }
852 spin_unlock_irqrestore(lock: &dtab->index_lock, flags);
853
854 return ret;
855}
856
857static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
858 struct bpf_dtab *dtab,
859 struct bpf_devmap_val *val,
860 unsigned int idx)
861{
862 struct bpf_prog *prog = NULL;
863 struct bpf_dtab_netdev *dev;
864
865 dev = bpf_map_kmalloc_node(map: &dtab->map, size: sizeof(*dev),
866 GFP_NOWAIT | __GFP_NOWARN,
867 node: dtab->map.numa_node);
868 if (!dev)
869 return ERR_PTR(error: -ENOMEM);
870
871 dev->dev = dev_get_by_index(net, ifindex: val->ifindex);
872 if (!dev->dev)
873 goto err_out;
874
875 if (val->bpf_prog.fd > 0) {
876 prog = bpf_prog_get_type_dev(ufd: val->bpf_prog.fd,
877 type: BPF_PROG_TYPE_XDP, attach_drv: false);
878 if (IS_ERR(ptr: prog))
879 goto err_put_dev;
880 if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
881 !bpf_prog_map_compatible(map: &dtab->map, fp: prog))
882 goto err_put_prog;
883 }
884
885 dev->idx = idx;
886 if (prog) {
887 dev->xdp_prog = prog;
888 dev->val.bpf_prog.id = prog->aux->id;
889 } else {
890 dev->xdp_prog = NULL;
891 dev->val.bpf_prog.id = 0;
892 }
893 dev->val.ifindex = val->ifindex;
894
895 return dev;
896err_put_prog:
897 bpf_prog_put(prog);
898err_put_dev:
899 dev_put(dev: dev->dev);
900err_out:
901 kfree(objp: dev);
902 return ERR_PTR(error: -EINVAL);
903}
904
905static long __dev_map_update_elem(struct net *net, struct bpf_map *map,
906 void *key, void *value, u64 map_flags)
907{
908 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
909 struct bpf_dtab_netdev *dev, *old_dev;
910 struct bpf_devmap_val val = {};
911 u32 i = *(u32 *)key;
912
913 if (unlikely(map_flags > BPF_EXIST))
914 return -EINVAL;
915 if (unlikely(i >= dtab->map.max_entries))
916 return -E2BIG;
917 if (unlikely(map_flags == BPF_NOEXIST))
918 return -EEXIST;
919
920 /* already verified value_size <= sizeof val */
921 memcpy(&val, value, map->value_size);
922
923 if (!val.ifindex) {
924 dev = NULL;
925 /* can not specify fd if ifindex is 0 */
926 if (val.bpf_prog.fd > 0)
927 return -EINVAL;
928 } else {
929 dev = __dev_map_alloc_node(net, dtab, val: &val, idx: i);
930 if (IS_ERR(ptr: dev))
931 return PTR_ERR(ptr: dev);
932 }
933
934 /* Use call_rcu() here to ensure rcu critical sections have completed
935 * Remembering the driver side flush operation will happen before the
936 * net device is removed.
937 */
938 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
939 if (old_dev)
940 call_rcu(head: &old_dev->rcu, func: __dev_map_entry_free);
941 else
942 atomic_inc(v: (atomic_t *)&dtab->items);
943
944 return 0;
945}
946
947static long dev_map_update_elem(struct bpf_map *map, void *key, void *value,
948 u64 map_flags)
949{
950 return __dev_map_update_elem(current->nsproxy->net_ns,
951 map, key, value, map_flags);
952}
953
954static long __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
955 void *key, void *value, u64 map_flags)
956{
957 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
958 struct bpf_dtab_netdev *dev, *old_dev;
959 struct bpf_devmap_val val = {};
960 u32 idx = *(u32 *)key;
961 unsigned long flags;
962 int err = -EEXIST;
963
964 /* already verified value_size <= sizeof val */
965 memcpy(&val, value, map->value_size);
966
967 if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
968 return -EINVAL;
969
970 spin_lock_irqsave(&dtab->index_lock, flags);
971
972 old_dev = __dev_map_hash_lookup_elem(map, key: idx);
973 if (old_dev && (map_flags & BPF_NOEXIST))
974 goto out_err;
975
976 dev = __dev_map_alloc_node(net, dtab, val: &val, idx);
977 if (IS_ERR(ptr: dev)) {
978 err = PTR_ERR(ptr: dev);
979 goto out_err;
980 }
981
982 if (old_dev) {
983 hlist_del_rcu(n: &old_dev->index_hlist);
984 } else {
985 if (dtab->items >= dtab->map.max_entries) {
986 spin_unlock_irqrestore(lock: &dtab->index_lock, flags);
987 call_rcu(head: &dev->rcu, func: __dev_map_entry_free);
988 return -E2BIG;
989 }
990 dtab->items++;
991 }
992
993 hlist_add_head_rcu(n: &dev->index_hlist,
994 h: dev_map_index_hash(dtab, idx));
995 spin_unlock_irqrestore(lock: &dtab->index_lock, flags);
996
997 if (old_dev)
998 call_rcu(head: &old_dev->rcu, func: __dev_map_entry_free);
999
1000 return 0;
1001
1002out_err:
1003 spin_unlock_irqrestore(lock: &dtab->index_lock, flags);
1004 return err;
1005}
1006
1007static long dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
1008 u64 map_flags)
1009{
1010 return __dev_map_hash_update_elem(current->nsproxy->net_ns,
1011 map, key, value, map_flags);
1012}
1013
1014static long dev_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1015{
1016 return __bpf_xdp_redirect_map(map, index: ifindex, flags,
1017 flag_mask: BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1018 lookup_elem: __dev_map_lookup_elem);
1019}
1020
1021static long dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1022{
1023 return __bpf_xdp_redirect_map(map, index: ifindex, flags,
1024 flag_mask: BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1025 lookup_elem: __dev_map_hash_lookup_elem);
1026}
1027
1028static u64 dev_map_mem_usage(const struct bpf_map *map)
1029{
1030 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
1031 u64 usage = sizeof(struct bpf_dtab);
1032
1033 if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
1034 usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
1035 else
1036 usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
1037 usage += atomic_read(v: (atomic_t *)&dtab->items) *
1038 (u64)sizeof(struct bpf_dtab_netdev);
1039 return usage;
1040}
1041
1042BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
1043const struct bpf_map_ops dev_map_ops = {
1044 .map_meta_equal = bpf_map_meta_equal,
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
1057const struct bpf_map_ops dev_map_hash_ops = {
1058 .map_meta_equal = bpf_map_meta_equal,
1059 .map_alloc = dev_map_alloc,
1060 .map_free = dev_map_free,
1061 .map_get_next_key = dev_map_hash_get_next_key,
1062 .map_lookup_elem = dev_map_hash_lookup_elem,
1063 .map_update_elem = dev_map_hash_update_elem,
1064 .map_delete_elem = dev_map_hash_delete_elem,
1065 .map_check_btf = map_check_no_btf,
1066 .map_mem_usage = dev_map_mem_usage,
1067 .map_btf_id = &dev_map_btf_ids[0],
1068 .map_redirect = dev_hash_map_redirect,
1069};
1070
1071static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
1072 struct net_device *netdev)
1073{
1074 unsigned long flags;
1075 u32 i;
1076
1077 spin_lock_irqsave(&dtab->index_lock, flags);
1078 for (i = 0; i < dtab->n_buckets; i++) {
1079 struct bpf_dtab_netdev *dev;
1080 struct hlist_head *head;
1081 struct hlist_node *next;
1082
1083 head = dev_map_index_hash(dtab, idx: i);
1084
1085 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
1086 if (netdev != dev->dev)
1087 continue;
1088
1089 dtab->items--;
1090 hlist_del_rcu(n: &dev->index_hlist);
1091 call_rcu(head: &dev->rcu, func: __dev_map_entry_free);
1092 }
1093 }
1094 spin_unlock_irqrestore(lock: &dtab->index_lock, flags);
1095}
1096
1097static int dev_map_notification(struct notifier_block *notifier,
1098 ulong event, void *ptr)
1099{
1100 struct net_device *netdev = netdev_notifier_info_to_dev(info: ptr);
1101 struct bpf_dtab *dtab;
1102 int i, cpu;
1103
1104 switch (event) {
1105 case NETDEV_REGISTER:
1106 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1107 break;
1108
1109 /* will be freed in free_netdev() */
1110 netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1111 if (!netdev->xdp_bulkq)
1112 return NOTIFY_BAD;
1113
1114 for_each_possible_cpu(cpu)
1115 per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1116 break;
1117 case NETDEV_UNREGISTER:
1118 /* This rcu_read_lock/unlock pair is needed because
1119 * dev_map_list is an RCU list AND to ensure a delete
1120 * operation does not free a netdev_map entry while we
1121 * are comparing it against the netdev being unregistered.
1122 */
1123 rcu_read_lock();
1124 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
1125 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
1126 dev_map_hash_remove_netdev(dtab, netdev);
1127 continue;
1128 }
1129
1130 for (i = 0; i < dtab->map.max_entries; i++) {
1131 struct bpf_dtab_netdev *dev, *odev;
1132
1133 dev = rcu_dereference(dtab->netdev_map[i]);
1134 if (!dev || netdev != dev->dev)
1135 continue;
1136 odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1137 if (dev == odev) {
1138 call_rcu(head: &dev->rcu,
1139 func: __dev_map_entry_free);
1140 atomic_dec(v: (atomic_t *)&dtab->items);
1141 }
1142 }
1143 }
1144 rcu_read_unlock();
1145 break;
1146 default:
1147 break;
1148 }
1149 return NOTIFY_OK;
1150}
1151
1152static struct notifier_block dev_map_notifier = {
1153 .notifier_call = dev_map_notification,
1154};
1155
1156static int __init dev_map_init(void)
1157{
1158 int cpu;
1159
1160 /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1161 BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1162 offsetof(struct _bpf_dtab_netdev, dev));
1163 register_netdevice_notifier(nb: &dev_map_notifier);
1164
1165 for_each_possible_cpu(cpu)
1166 INIT_LIST_HEAD(list: &per_cpu(dev_flush_list, cpu));
1167 return 0;
1168}
1169
1170subsys_initcall(dev_map_init);
1171

source code of linux/kernel/bpf/devmap.c