1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2017 Covalent IO, Inc. http://covalent.io
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.
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.
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.
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.
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.
47 #include <linux/bpf.h>
49 #include <linux/filter.h>
50 #include <trace/events/xdp.h>
51 #include <linux/btf_ids.h>
53 #define DEV_CREATE_FLAG_MASK \
54 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
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;
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_dtab *dtab;
69 struct bpf_prog *xdp_prog;
72 struct bpf_devmap_val val;
77 struct bpf_dtab_netdev __rcu **netdev_map; /* DEVMAP type only */
78 struct list_head list;
80 /* these are only used for DEVMAP_HASH type maps */
81 struct hlist_head *dev_index_head;
82 spinlock_t index_lock;
87 static DEFINE_PER_CPU(struct list_head, dev_flush_list);
88 static DEFINE_SPINLOCK(dev_map_lock);
89 static LIST_HEAD(dev_map_list);
91 static struct hlist_head *dev_map_create_hash(unsigned int entries,
95 struct hlist_head *hash;
97 hash = bpf_map_area_alloc((u64) entries * sizeof(*hash), numa_node);
99 for (i = 0; i < entries; i++)
100 INIT_HLIST_HEAD(&hash[i]);
105 static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
108 return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
111 static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
113 u32 valsize = attr->value_size;
115 /* check sanity of attributes. 2 value sizes supported:
117 * 8 bytes: ifindex + prog fd
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)
125 /* Lookup returns a pointer straight to dev->ifindex, so make sure the
126 * verifier prevents writes from the BPF side
128 attr->map_flags |= BPF_F_RDONLY_PROG;
131 bpf_map_init_from_attr(&dtab->map, attr);
133 if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
134 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
136 if (!dtab->n_buckets) /* Overflow check */
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)
146 spin_lock_init(&dtab->index_lock);
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)
158 static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
160 struct bpf_dtab *dtab;
163 if (!capable(CAP_NET_ADMIN))
164 return ERR_PTR(-EPERM);
166 dtab = bpf_map_area_alloc(sizeof(*dtab), NUMA_NO_NODE);
168 return ERR_PTR(-ENOMEM);
170 err = dev_map_init_map(dtab, attr);
172 bpf_map_area_free(dtab);
176 spin_lock(&dev_map_lock);
177 list_add_tail_rcu(&dtab->list, &dev_map_list);
178 spin_unlock(&dev_map_lock);
183 static void dev_map_free(struct bpf_map *map)
185 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
188 /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
189 * so the programs (can be more than one that used this map) were
190 * disconnected from events. The following synchronize_rcu() guarantees
191 * both rcu read critical sections complete and waits for
192 * preempt-disable regions (NAPI being the relevant context here) so we
193 * are certain there will be no further reads against the netdev_map and
194 * all flush operations are complete. Flush operations can only be done
195 * from NAPI context for this reason.
198 spin_lock(&dev_map_lock);
199 list_del_rcu(&dtab->list);
200 spin_unlock(&dev_map_lock);
202 bpf_clear_redirect_map(map);
205 /* Make sure prior __dev_map_entry_free() have completed. */
208 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
209 for (i = 0; i < dtab->n_buckets; i++) {
210 struct bpf_dtab_netdev *dev;
211 struct hlist_head *head;
212 struct hlist_node *next;
214 head = dev_map_index_hash(dtab, i);
216 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
217 hlist_del_rcu(&dev->index_hlist);
219 bpf_prog_put(dev->xdp_prog);
225 bpf_map_area_free(dtab->dev_index_head);
227 for (i = 0; i < dtab->map.max_entries; i++) {
228 struct bpf_dtab_netdev *dev;
230 dev = rcu_dereference_raw(dtab->netdev_map[i]);
235 bpf_prog_put(dev->xdp_prog);
240 bpf_map_area_free(dtab->netdev_map);
243 bpf_map_area_free(dtab);
246 static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
248 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
249 u32 index = key ? *(u32 *)key : U32_MAX;
250 u32 *next = next_key;
252 if (index >= dtab->map.max_entries) {
257 if (index == dtab->map.max_entries - 1)
263 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
264 * by local_bh_disable() (from XDP calls inside NAPI). The
265 * rcu_read_lock_bh_held() below makes lockdep accept both.
267 static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
269 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
270 struct hlist_head *head = dev_map_index_hash(dtab, key);
271 struct bpf_dtab_netdev *dev;
273 hlist_for_each_entry_rcu(dev, head, index_hlist,
274 lockdep_is_held(&dtab->index_lock))
281 static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
284 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
285 u32 idx, *next = next_key;
286 struct bpf_dtab_netdev *dev, *next_dev;
287 struct hlist_head *head;
295 dev = __dev_map_hash_lookup_elem(map, idx);
299 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
300 struct bpf_dtab_netdev, index_hlist);
303 *next = next_dev->idx;
307 i = idx & (dtab->n_buckets - 1);
311 for (; i < dtab->n_buckets; i++) {
312 head = dev_map_index_hash(dtab, i);
314 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
315 struct bpf_dtab_netdev,
318 *next = next_dev->idx;
326 static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
327 struct xdp_frame **frames, int n,
328 struct net_device *dev)
330 struct xdp_txq_info txq = { .dev = dev };
334 for (i = 0; i < n; i++) {
335 struct xdp_frame *xdpf = frames[i];
339 xdp_convert_frame_to_buff(xdpf, &xdp);
342 act = bpf_prog_run_xdp(xdp_prog, &xdp);
345 err = xdp_update_frame_from_buff(&xdp, xdpf);
346 if (unlikely(err < 0))
347 xdp_return_frame_rx_napi(xdpf);
349 frames[nframes++] = xdpf;
352 bpf_warn_invalid_xdp_action(NULL, xdp_prog, act);
355 trace_xdp_exception(dev, xdp_prog, act);
358 xdp_return_frame_rx_napi(xdpf);
362 return nframes; /* sent frames count */
365 static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
367 struct net_device *dev = bq->dev;
368 unsigned int cnt = bq->count;
369 int sent = 0, err = 0;
376 for (i = 0; i < cnt; i++) {
377 struct xdp_frame *xdpf = bq->q[i];
383 to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
388 sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
390 /* If ndo_xdp_xmit fails with an errno, no frames have
397 /* If not all frames have been transmitted, it is our
398 * responsibility to free them
400 for (i = sent; unlikely(i < to_send); i++)
401 xdp_return_frame_rx_napi(bq->q[i]);
405 trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
408 /* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
409 * driver before returning from its napi->poll() routine. See the comment above
410 * xdp_do_flush() in filter.c.
412 void __dev_flush(void)
414 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
415 struct xdp_dev_bulk_queue *bq, *tmp;
417 list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
418 bq_xmit_all(bq, XDP_XMIT_FLUSH);
421 __list_del_clearprev(&bq->flush_node);
425 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
426 * by local_bh_disable() (from XDP calls inside NAPI). The
427 * rcu_read_lock_bh_held() below makes lockdep accept both.
429 static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
431 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
432 struct bpf_dtab_netdev *obj;
434 if (key >= map->max_entries)
437 obj = rcu_dereference_check(dtab->netdev_map[key],
438 rcu_read_lock_bh_held());
442 /* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
443 * variable access, and map elements stick around. See comment above
444 * xdp_do_flush() in filter.c.
446 static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
447 struct net_device *dev_rx, struct bpf_prog *xdp_prog)
449 struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
450 struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
452 if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
455 /* Ingress dev_rx will be the same for all xdp_frame's in
456 * bulk_queue, because bq stored per-CPU and must be flushed
457 * from net_device drivers NAPI func end.
459 * Do the same with xdp_prog and flush_list since these fields
460 * are only ever modified together.
464 bq->xdp_prog = xdp_prog;
465 list_add(&bq->flush_node, flush_list);
468 bq->q[bq->count++] = xdpf;
471 static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
472 struct net_device *dev_rx,
473 struct bpf_prog *xdp_prog)
477 if (!dev->netdev_ops->ndo_xdp_xmit)
480 err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
484 bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
488 static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
490 struct xdp_txq_info txq = { .dev = dst->dev };
497 __skb_pull(skb, skb->mac_len);
500 act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
503 __skb_push(skb, skb->mac_len);
506 bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
509 trace_xdp_exception(dst->dev, dst->xdp_prog, act);
519 int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
520 struct net_device *dev_rx)
522 return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
525 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
526 struct net_device *dev_rx)
528 struct net_device *dev = dst->dev;
530 return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
533 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
536 !obj->dev->netdev_ops->ndo_xdp_xmit)
539 if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
545 static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
546 struct net_device *dev_rx,
547 struct xdp_frame *xdpf)
549 struct xdp_frame *nxdpf;
551 nxdpf = xdpf_clone(xdpf);
555 bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
560 static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
562 while (num_excluded--) {
563 if (ifindex == excluded[num_excluded])
569 /* Get ifindex of each upper device. 'indexes' must be able to hold at
570 * least MAX_NEST_DEV elements.
571 * Returns the number of ifindexes added.
573 static int get_upper_ifindexes(struct net_device *dev, int *indexes)
575 struct net_device *upper;
576 struct list_head *iter;
579 netdev_for_each_upper_dev_rcu(dev, upper, iter) {
580 indexes[n++] = upper->ifindex;
585 int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
586 struct bpf_map *map, bool exclude_ingress)
588 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
589 struct bpf_dtab_netdev *dst, *last_dst = NULL;
590 int excluded_devices[1+MAX_NEST_DEV];
591 struct hlist_head *head;
592 int num_excluded = 0;
596 if (exclude_ingress) {
597 num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
598 excluded_devices[num_excluded++] = dev_rx->ifindex;
601 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
602 for (i = 0; i < map->max_entries; i++) {
603 dst = rcu_dereference_check(dtab->netdev_map[i],
604 rcu_read_lock_bh_held());
605 if (!is_valid_dst(dst, xdpf))
608 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
611 /* we only need n-1 clones; last_dst enqueued below */
617 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
623 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
624 for (i = 0; i < dtab->n_buckets; i++) {
625 head = dev_map_index_hash(dtab, i);
626 hlist_for_each_entry_rcu(dst, head, index_hlist,
627 lockdep_is_held(&dtab->index_lock)) {
628 if (!is_valid_dst(dst, xdpf))
631 if (is_ifindex_excluded(excluded_devices, num_excluded,
635 /* we only need n-1 clones; last_dst enqueued below */
641 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
650 /* consume the last copy of the frame */
652 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
654 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
659 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
660 struct bpf_prog *xdp_prog)
664 err = xdp_ok_fwd_dev(dst->dev, skb->len);
668 /* Redirect has already succeeded semantically at this point, so we just
669 * return 0 even if packet is dropped. Helper below takes care of
672 if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
676 generic_xdp_tx(skb, xdp_prog);
681 static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
683 struct bpf_prog *xdp_prog)
685 struct sk_buff *nskb;
688 nskb = skb_clone(skb, GFP_ATOMIC);
692 err = dev_map_generic_redirect(dst, nskb, xdp_prog);
701 int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
702 struct bpf_prog *xdp_prog, struct bpf_map *map,
703 bool exclude_ingress)
705 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
706 struct bpf_dtab_netdev *dst, *last_dst = NULL;
707 int excluded_devices[1+MAX_NEST_DEV];
708 struct hlist_head *head;
709 struct hlist_node *next;
710 int num_excluded = 0;
714 if (exclude_ingress) {
715 num_excluded = get_upper_ifindexes(dev, excluded_devices);
716 excluded_devices[num_excluded++] = dev->ifindex;
719 if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
720 for (i = 0; i < map->max_entries; i++) {
721 dst = rcu_dereference_check(dtab->netdev_map[i],
722 rcu_read_lock_bh_held());
726 if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
729 /* we only need n-1 clones; last_dst enqueued below */
735 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
742 } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
743 for (i = 0; i < dtab->n_buckets; i++) {
744 head = dev_map_index_hash(dtab, i);
745 hlist_for_each_entry_safe(dst, next, head, index_hlist) {
749 if (is_ifindex_excluded(excluded_devices, num_excluded,
753 /* we only need n-1 clones; last_dst enqueued below */
759 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
768 /* consume the first skb and return */
770 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
777 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
779 struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
781 return obj ? &obj->val : NULL;
784 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
786 struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
788 return obj ? &obj->val : NULL;
791 static void __dev_map_entry_free(struct rcu_head *rcu)
793 struct bpf_dtab_netdev *dev;
795 dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
797 bpf_prog_put(dev->xdp_prog);
802 static int dev_map_delete_elem(struct bpf_map *map, void *key)
804 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
805 struct bpf_dtab_netdev *old_dev;
808 if (k >= map->max_entries)
811 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
813 call_rcu(&old_dev->rcu, __dev_map_entry_free);
817 static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
819 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
820 struct bpf_dtab_netdev *old_dev;
825 spin_lock_irqsave(&dtab->index_lock, flags);
827 old_dev = __dev_map_hash_lookup_elem(map, k);
830 hlist_del_init_rcu(&old_dev->index_hlist);
831 call_rcu(&old_dev->rcu, __dev_map_entry_free);
834 spin_unlock_irqrestore(&dtab->index_lock, flags);
839 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
840 struct bpf_dtab *dtab,
841 struct bpf_devmap_val *val,
844 struct bpf_prog *prog = NULL;
845 struct bpf_dtab_netdev *dev;
847 dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
848 GFP_NOWAIT | __GFP_NOWARN,
849 dtab->map.numa_node);
851 return ERR_PTR(-ENOMEM);
853 dev->dev = dev_get_by_index(net, val->ifindex);
857 if (val->bpf_prog.fd > 0) {
858 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
859 BPF_PROG_TYPE_XDP, false);
862 if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
863 !bpf_prog_map_compatible(&dtab->map, prog))
870 dev->xdp_prog = prog;
871 dev->val.bpf_prog.id = prog->aux->id;
873 dev->xdp_prog = NULL;
874 dev->val.bpf_prog.id = 0;
876 dev->val.ifindex = val->ifindex;
885 return ERR_PTR(-EINVAL);
888 static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
889 void *key, void *value, u64 map_flags)
891 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
892 struct bpf_dtab_netdev *dev, *old_dev;
893 struct bpf_devmap_val val = {};
896 if (unlikely(map_flags > BPF_EXIST))
898 if (unlikely(i >= dtab->map.max_entries))
900 if (unlikely(map_flags == BPF_NOEXIST))
903 /* already verified value_size <= sizeof val */
904 memcpy(&val, value, map->value_size);
908 /* can not specify fd if ifindex is 0 */
909 if (val.bpf_prog.fd > 0)
912 dev = __dev_map_alloc_node(net, dtab, &val, i);
917 /* Use call_rcu() here to ensure rcu critical sections have completed
918 * Remembering the driver side flush operation will happen before the
919 * net device is removed.
921 old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
923 call_rcu(&old_dev->rcu, __dev_map_entry_free);
928 static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
931 return __dev_map_update_elem(current->nsproxy->net_ns,
932 map, key, value, map_flags);
935 static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
936 void *key, void *value, u64 map_flags)
938 struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
939 struct bpf_dtab_netdev *dev, *old_dev;
940 struct bpf_devmap_val val = {};
941 u32 idx = *(u32 *)key;
945 /* already verified value_size <= sizeof val */
946 memcpy(&val, value, map->value_size);
948 if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
951 spin_lock_irqsave(&dtab->index_lock, flags);
953 old_dev = __dev_map_hash_lookup_elem(map, idx);
954 if (old_dev && (map_flags & BPF_NOEXIST))
957 dev = __dev_map_alloc_node(net, dtab, &val, idx);
964 hlist_del_rcu(&old_dev->index_hlist);
966 if (dtab->items >= dtab->map.max_entries) {
967 spin_unlock_irqrestore(&dtab->index_lock, flags);
968 call_rcu(&dev->rcu, __dev_map_entry_free);
974 hlist_add_head_rcu(&dev->index_hlist,
975 dev_map_index_hash(dtab, idx));
976 spin_unlock_irqrestore(&dtab->index_lock, flags);
979 call_rcu(&old_dev->rcu, __dev_map_entry_free);
984 spin_unlock_irqrestore(&dtab->index_lock, flags);
988 static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
991 return __dev_map_hash_update_elem(current->nsproxy->net_ns,
992 map, key, value, map_flags);
995 static int dev_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
997 return __bpf_xdp_redirect_map(map, ifindex, flags,
998 BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
999 __dev_map_lookup_elem);
1002 static int dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1004 return __bpf_xdp_redirect_map(map, ifindex, flags,
1005 BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1006 __dev_map_hash_lookup_elem);
1009 BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
1010 const struct bpf_map_ops dev_map_ops = {
1011 .map_meta_equal = bpf_map_meta_equal,
1012 .map_alloc = dev_map_alloc,
1013 .map_free = dev_map_free,
1014 .map_get_next_key = dev_map_get_next_key,
1015 .map_lookup_elem = dev_map_lookup_elem,
1016 .map_update_elem = dev_map_update_elem,
1017 .map_delete_elem = dev_map_delete_elem,
1018 .map_check_btf = map_check_no_btf,
1019 .map_btf_id = &dev_map_btf_ids[0],
1020 .map_redirect = dev_map_redirect,
1023 const struct bpf_map_ops dev_map_hash_ops = {
1024 .map_meta_equal = bpf_map_meta_equal,
1025 .map_alloc = dev_map_alloc,
1026 .map_free = dev_map_free,
1027 .map_get_next_key = dev_map_hash_get_next_key,
1028 .map_lookup_elem = dev_map_hash_lookup_elem,
1029 .map_update_elem = dev_map_hash_update_elem,
1030 .map_delete_elem = dev_map_hash_delete_elem,
1031 .map_check_btf = map_check_no_btf,
1032 .map_btf_id = &dev_map_btf_ids[0],
1033 .map_redirect = dev_hash_map_redirect,
1036 static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
1037 struct net_device *netdev)
1039 unsigned long flags;
1042 spin_lock_irqsave(&dtab->index_lock, flags);
1043 for (i = 0; i < dtab->n_buckets; i++) {
1044 struct bpf_dtab_netdev *dev;
1045 struct hlist_head *head;
1046 struct hlist_node *next;
1048 head = dev_map_index_hash(dtab, i);
1050 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
1051 if (netdev != dev->dev)
1055 hlist_del_rcu(&dev->index_hlist);
1056 call_rcu(&dev->rcu, __dev_map_entry_free);
1059 spin_unlock_irqrestore(&dtab->index_lock, flags);
1062 static int dev_map_notification(struct notifier_block *notifier,
1063 ulong event, void *ptr)
1065 struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
1066 struct bpf_dtab *dtab;
1070 case NETDEV_REGISTER:
1071 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1074 /* will be freed in free_netdev() */
1075 netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1076 if (!netdev->xdp_bulkq)
1079 for_each_possible_cpu(cpu)
1080 per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1082 case NETDEV_UNREGISTER:
1083 /* This rcu_read_lock/unlock pair is needed because
1084 * dev_map_list is an RCU list AND to ensure a delete
1085 * operation does not free a netdev_map entry while we
1086 * are comparing it against the netdev being unregistered.
1089 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
1090 if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
1091 dev_map_hash_remove_netdev(dtab, netdev);
1095 for (i = 0; i < dtab->map.max_entries; i++) {
1096 struct bpf_dtab_netdev *dev, *odev;
1098 dev = rcu_dereference(dtab->netdev_map[i]);
1099 if (!dev || netdev != dev->dev)
1101 odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1104 __dev_map_entry_free);
1115 static struct notifier_block dev_map_notifier = {
1116 .notifier_call = dev_map_notification,
1119 static int __init dev_map_init(void)
1123 /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1124 BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1125 offsetof(struct _bpf_dtab_netdev, dev));
1126 register_netdevice_notifier(&dev_map_notifier);
1128 for_each_possible_cpu(cpu)
1129 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1133 subsys_initcall(dev_map_init);