kernel/bpf/devmap.c

   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_PER_CPU(struct list_head, dev_flush_list);
  87 static DEFINE_SPINLOCK(dev_map_lock);
  88 static LIST_HEAD(dev_map_list);
  89
  90 static 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((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
 104 static 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
 110 static 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(&dtab->map, attr);
 131
 132         if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
 133                 /* hash table size must be power of 2; roundup_pow_of_two() can
 134                  * overflow into UB on 32-bit arches, so check that first
 135                  */
 136                 if (dtab->map.max_entries > 1UL << 31)
 137                         return -EINVAL;
 138
 139                 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
 140
 141                 dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
 142                                                            dtab->map.numa_node);
 143                 if (!dtab->dev_index_head)
 144                         return -ENOMEM;
 145
 146                 spin_lock_init(&dtab->index_lock);
 147         } else {
 148                 dtab->netdev_map = bpf_map_area_alloc((u64) dtab->map.max_entries *
 149                                                       sizeof(struct bpf_dtab_netdev *),
 150                                                       dtab->map.numa_node);
 151                 if (!dtab->netdev_map)
 152                         return -ENOMEM;
 153         }
 154
 155         return 0;
 156 }
 157
 158 static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
 159 {
 160         struct bpf_dtab *dtab;
 161         int err;
 162
 163         dtab = bpf_map_area_alloc(sizeof(*dtab), NUMA_NO_NODE);
 164         if (!dtab)
 165                 return ERR_PTR(-ENOMEM);
 166
 167         err = dev_map_init_map(dtab, attr);
 168         if (err) {
 169                 bpf_map_area_free(dtab);
 170                 return ERR_PTR(err);
 171         }
 172
 173         spin_lock(&dev_map_lock);
 174         list_add_tail_rcu(&dtab->list, &dev_map_list);
 175         spin_unlock(&dev_map_lock);
 176
 177         return &dtab->map;
 178 }
 179
 180 static void dev_map_free(struct bpf_map *map)
 181 {
 182         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 183         int i;
 184
 185         /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
 186          * so the programs (can be more than one that used this map) were
 187          * disconnected from events. The following synchronize_rcu() guarantees
 188          * both rcu read critical sections complete and waits for
 189          * preempt-disable regions (NAPI being the relevant context here) so we
 190          * are certain there will be no further reads against the netdev_map and
 191          * all flush operations are complete. Flush operations can only be done
 192          * from NAPI context for this reason.
 193          */
 194
 195         spin_lock(&dev_map_lock);
 196         list_del_rcu(&dtab->list);
 197         spin_unlock(&dev_map_lock);
 198
 199         bpf_clear_redirect_map(map);
 200         synchronize_rcu();
 201
 202         /* Make sure prior __dev_map_entry_free() have completed. */
 203         rcu_barrier();
 204
 205         if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
 206                 for (i = 0; i < dtab->n_buckets; i++) {
 207                         struct bpf_dtab_netdev *dev;
 208                         struct hlist_head *head;
 209                         struct hlist_node *next;
 210
 211                         head = dev_map_index_hash(dtab, i);
 212
 213                         hlist_for_each_entry_safe(dev, next, head, index_hlist) {
 214                                 hlist_del_rcu(&dev->index_hlist);
 215                                 if (dev->xdp_prog)
 216                                         bpf_prog_put(dev->xdp_prog);
 217                                 dev_put(dev->dev);
 218                                 kfree(dev);
 219                         }
 220                 }
 221
 222                 bpf_map_area_free(dtab->dev_index_head);
 223         } else {
 224                 for (i = 0; i < dtab->map.max_entries; i++) {
 225                         struct bpf_dtab_netdev *dev;
 226
 227                         dev = rcu_dereference_raw(dtab->netdev_map[i]);
 228                         if (!dev)
 229                                 continue;
 230
 231                         if (dev->xdp_prog)
 232                                 bpf_prog_put(dev->xdp_prog);
 233                         dev_put(dev->dev);
 234                         kfree(dev);
 235                 }
 236
 237                 bpf_map_area_free(dtab->netdev_map);
 238         }
 239
 240         bpf_map_area_free(dtab);
 241 }
 242
 243 static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 244 {
 245         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 246         u32 index = key ? *(u32 *)key : U32_MAX;
 247         u32 *next = next_key;
 248
 249         if (index >= dtab->map.max_entries) {
 250                 *next = 0;
 251                 return 0;
 252         }
 253
 254         if (index == dtab->map.max_entries - 1)
 255                 return -ENOENT;
 256         *next = index + 1;
 257         return 0;
 258 }
 259
 260 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
 261  * by local_bh_disable() (from XDP calls inside NAPI). The
 262  * rcu_read_lock_bh_held() below makes lockdep accept both.
 263  */
 264 static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
 265 {
 266         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 267         struct hlist_head *head = dev_map_index_hash(dtab, key);
 268         struct bpf_dtab_netdev *dev;
 269
 270         hlist_for_each_entry_rcu(dev, head, index_hlist,
 271                                  lockdep_is_held(&dtab->index_lock))
 272                 if (dev->idx == key)
 273                         return dev;
 274
 275         return NULL;
 276 }
 277
 278 static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
 279                                     void *next_key)
 280 {
 281         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 282         u32 idx, *next = next_key;
 283         struct bpf_dtab_netdev *dev, *next_dev;
 284         struct hlist_head *head;
 285         int i = 0;
 286
 287         if (!key)
 288                 goto find_first;
 289
 290         idx = *(u32 *)key;
 291
 292         dev = __dev_map_hash_lookup_elem(map, idx);
 293         if (!dev)
 294                 goto find_first;
 295
 296         next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
 297                                     struct bpf_dtab_netdev, index_hlist);
 298
 299         if (next_dev) {
 300                 *next = next_dev->idx;
 301                 return 0;
 302         }
 303
 304         i = idx & (dtab->n_buckets - 1);
 305         i++;
 306
 307  find_first:
 308         for (; i < dtab->n_buckets; i++) {
 309                 head = dev_map_index_hash(dtab, i);
 310
 311                 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
 312                                             struct bpf_dtab_netdev,
 313                                             index_hlist);
 314                 if (next_dev) {
 315                         *next = next_dev->idx;
 316                         return 0;
 317                 }
 318         }
 319
 320         return -ENOENT;
 321 }
 322
 323 static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
 324                                 struct xdp_frame **frames, int n,
 325                                 struct net_device *dev)
 326 {
 327         struct xdp_txq_info txq = { .dev = dev };
 328         struct xdp_buff xdp;
 329         int i, nframes = 0;
 330
 331         for (i = 0; i < n; i++) {
 332                 struct xdp_frame *xdpf = frames[i];
 333                 u32 act;
 334                 int err;
 335
 336                 xdp_convert_frame_to_buff(xdpf, &xdp);
 337                 xdp.txq = &txq;
 338
 339                 act = bpf_prog_run_xdp(xdp_prog, &xdp);
 340                 switch (act) {
 341                 case XDP_PASS:
 342                         err = xdp_update_frame_from_buff(&xdp, xdpf);
 343                         if (unlikely(err < 0))
 344                                 xdp_return_frame_rx_napi(xdpf);
 345                         else
 346                                 frames[nframes++] = xdpf;
 347                         break;
 348                 default:
 349                         bpf_warn_invalid_xdp_action(NULL, xdp_prog, act);
 350                         fallthrough;
 351                 case XDP_ABORTED:
 352                         trace_xdp_exception(dev, xdp_prog, act);
 353                         fallthrough;
 354                 case XDP_DROP:
 355                         xdp_return_frame_rx_napi(xdpf);
 356                         break;
 357                 }
 358         }
 359         return nframes; /* sent frames count */
 360 }
 361
 362 static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
 363 {
 364         struct net_device *dev = bq->dev;
 365         unsigned int cnt = bq->count;
 366         int sent = 0, err = 0;
 367         int to_send = cnt;
 368         int i;
 369
 370         if (unlikely(!cnt))
 371                 return;
 372
 373         for (i = 0; i < cnt; i++) {
 374                 struct xdp_frame *xdpf = bq->q[i];
 375
 376                 prefetch(xdpf);
 377         }
 378
 379         if (bq->xdp_prog) {
 380                 to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
 381                 if (!to_send)
 382                         goto out;
 383         }
 384
 385         sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
 386         if (sent < 0) {
 387                 /* If ndo_xdp_xmit fails with an errno, no frames have
 388                  * been xmit'ed.
 389                  */
 390                 err = sent;
 391                 sent = 0;
 392         }
 393
 394         /* If not all frames have been transmitted, it is our
 395          * responsibility to free them
 396          */
 397         for (i = sent; unlikely(i < to_send); i++)
 398                 xdp_return_frame_rx_napi(bq->q[i]);
 399
 400 out:
 401         bq->count = 0;
 402         trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
 403 }
 404
 405 /* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
 406  * driver before returning from its napi->poll() routine. See the comment above
 407  * xdp_do_flush() in filter.c.
 408  */
 409 void __dev_flush(void)
 410 {
 411         struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
 412         struct xdp_dev_bulk_queue *bq, *tmp;
 413
 414         list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
 415                 bq_xmit_all(bq, XDP_XMIT_FLUSH);
 416                 bq->dev_rx = NULL;
 417                 bq->xdp_prog = NULL;
 418                 __list_del_clearprev(&bq->flush_node);
 419         }
 420 }
 421
 422 #ifdef CONFIG_DEBUG_NET
 423 bool dev_check_flush(void)
 424 {
 425         if (list_empty(this_cpu_ptr(&dev_flush_list)))
 426                 return false;
 427         __dev_flush();
 428         return true;
 429 }
 430 #endif
 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 list_head *flush_list = this_cpu_ptr(&dev_flush_list);
 457         struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
 458
 459         if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
 460                 bq_xmit_all(bq, 0);
 461
 462         /* Ingress dev_rx will be the same for all xdp_frame's in
 463          * bulk_queue, because bq stored per-CPU and must be flushed
 464          * from net_device drivers NAPI func end.
 465          *
 466          * Do the same with xdp_prog and flush_list since these fields
 467          * are only ever modified together.
 468          */
 469         if (!bq->dev_rx) {
 470                 bq->dev_rx = dev_rx;
 471                 bq->xdp_prog = xdp_prog;
 472                 list_add(&bq->flush_node, flush_list);
 473         }
 474
 475         bq->q[bq->count++] = xdpf;
 476 }
 477
 478 static inline int __xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 479                                 struct net_device *dev_rx,
 480                                 struct bpf_prog *xdp_prog)
 481 {
 482         int err;
 483
 484         if (!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
 485                 return -EOPNOTSUPP;
 486
 487         if (unlikely(!(dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
 488                      xdp_frame_has_frags(xdpf)))
 489                 return -EOPNOTSUPP;
 490
 491         err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
 492         if (unlikely(err))
 493                 return err;
 494
 495         bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
 496         return 0;
 497 }
 498
 499 static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
 500 {
 501         struct xdp_txq_info txq = { .dev = dst->dev };
 502         struct xdp_buff xdp;
 503         u32 act;
 504
 505         if (!dst->xdp_prog)
 506                 return XDP_PASS;
 507
 508         __skb_pull(skb, skb->mac_len);
 509         xdp.txq = &txq;
 510
 511         act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
 512         switch (act) {
 513         case XDP_PASS:
 514                 __skb_push(skb, skb->mac_len);
 515                 break;
 516         default:
 517                 bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
 518                 fallthrough;
 519         case XDP_ABORTED:
 520                 trace_xdp_exception(dst->dev, dst->xdp_prog, act);
 521                 fallthrough;
 522         case XDP_DROP:
 523                 kfree_skb(skb);
 524                 break;
 525         }
 526
 527         return act;
 528 }
 529
 530 int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 531                     struct net_device *dev_rx)
 532 {
 533         return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
 534 }
 535
 536 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
 537                     struct net_device *dev_rx)
 538 {
 539         struct net_device *dev = dst->dev;
 540
 541         return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
 542 }
 543
 544 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
 545 {
 546         if (!obj)
 547                 return false;
 548
 549         if (!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT))
 550                 return false;
 551
 552         if (unlikely(!(obj->dev->xdp_features & NETDEV_XDP_ACT_NDO_XMIT_SG) &&
 553                      xdp_frame_has_frags(xdpf)))
 554                 return false;
 555
 556         if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
 557                 return false;
 558
 559         return true;
 560 }
 561
 562 static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
 563                                  struct net_device *dev_rx,
 564                                  struct xdp_frame *xdpf)
 565 {
 566         struct xdp_frame *nxdpf;
 567
 568         nxdpf = xdpf_clone(xdpf);
 569         if (!nxdpf)
 570                 return -ENOMEM;
 571
 572         bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
 573
 574         return 0;
 575 }
 576
 577 static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
 578 {
 579         while (num_excluded--) {
 580                 if (ifindex == excluded[num_excluded])
 581                         return true;
 582         }
 583         return false;
 584 }
 585
 586 /* Get ifindex of each upper device. 'indexes' must be able to hold at
 587  * least MAX_NEST_DEV elements.
 588  * Returns the number of ifindexes added.
 589  */
 590 static int get_upper_ifindexes(struct net_device *dev, int *indexes)
 591 {
 592         struct net_device *upper;
 593         struct list_head *iter;
 594         int n = 0;
 595
 596         netdev_for_each_upper_dev_rcu(dev, upper, iter) {
 597                 indexes[n++] = upper->ifindex;
 598         }
 599         return n;
 600 }
 601
 602 int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
 603                           struct bpf_map *map, bool exclude_ingress)
 604 {
 605         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 606         struct bpf_dtab_netdev *dst, *last_dst = NULL;
 607         int excluded_devices[1+MAX_NEST_DEV];
 608         struct hlist_head *head;
 609         int num_excluded = 0;
 610         unsigned int i;
 611         int err;
 612
 613         if (exclude_ingress) {
 614                 num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
 615                 excluded_devices[num_excluded++] = dev_rx->ifindex;
 616         }
 617
 618         if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 619                 for (i = 0; i < map->max_entries; i++) {
 620                         dst = rcu_dereference_check(dtab->netdev_map[i],
 621                                                     rcu_read_lock_bh_held());
 622                         if (!is_valid_dst(dst, xdpf))
 623                                 continue;
 624
 625                         if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
 626                                 continue;
 627
 628                         /* we only need n-1 clones; last_dst enqueued below */
 629                         if (!last_dst) {
 630                                 last_dst = dst;
 631                                 continue;
 632                         }
 633
 634                         err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 635                         if (err)
 636                                 return err;
 637
 638                         last_dst = dst;
 639                 }
 640         } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
 641                 for (i = 0; i < dtab->n_buckets; i++) {
 642                         head = dev_map_index_hash(dtab, i);
 643                         hlist_for_each_entry_rcu(dst, head, index_hlist,
 644                                                  lockdep_is_held(&dtab->index_lock)) {
 645                                 if (!is_valid_dst(dst, xdpf))
 646                                         continue;
 647
 648                                 if (is_ifindex_excluded(excluded_devices, num_excluded,
 649                                                         dst->dev->ifindex))
 650                                         continue;
 651
 652                                 /* we only need n-1 clones; last_dst enqueued below */
 653                                 if (!last_dst) {
 654                                         last_dst = dst;
 655                                         continue;
 656                                 }
 657
 658                                 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 659                                 if (err)
 660                                         return err;
 661
 662                                 last_dst = dst;
 663                         }
 664                 }
 665         }
 666
 667         /* consume the last copy of the frame */
 668         if (last_dst)
 669                 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
 670         else
 671                 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
 672
 673         return 0;
 674 }
 675
 676 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 677                              struct bpf_prog *xdp_prog)
 678 {
 679         int err;
 680
 681         err = xdp_ok_fwd_dev(dst->dev, skb->len);
 682         if (unlikely(err))
 683                 return err;
 684
 685         /* Redirect has already succeeded semantically at this point, so we just
 686          * return 0 even if packet is dropped. Helper below takes care of
 687          * freeing skb.
 688          */
 689         if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
 690                 return 0;
 691
 692         skb->dev = dst->dev;
 693         generic_xdp_tx(skb, xdp_prog);
 694
 695         return 0;
 696 }
 697
 698 static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
 699                                   struct sk_buff *skb,
 700                                   struct bpf_prog *xdp_prog)
 701 {
 702         struct sk_buff *nskb;
 703         int err;
 704
 705         nskb = skb_clone(skb, GFP_ATOMIC);
 706         if (!nskb)
 707                 return -ENOMEM;
 708
 709         err = dev_map_generic_redirect(dst, nskb, xdp_prog);
 710         if (unlikely(err)) {
 711                 consume_skb(nskb);
 712                 return err;
 713         }
 714
 715         return 0;
 716 }
 717
 718 int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
 719                            struct bpf_prog *xdp_prog, struct bpf_map *map,
 720                            bool exclude_ingress)
 721 {
 722         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 723         struct bpf_dtab_netdev *dst, *last_dst = NULL;
 724         int excluded_devices[1+MAX_NEST_DEV];
 725         struct hlist_head *head;
 726         struct hlist_node *next;
 727         int num_excluded = 0;
 728         unsigned int i;
 729         int err;
 730
 731         if (exclude_ingress) {
 732                 num_excluded = get_upper_ifindexes(dev, excluded_devices);
 733                 excluded_devices[num_excluded++] = dev->ifindex;
 734         }
 735
 736         if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 737                 for (i = 0; i < map->max_entries; i++) {
 738                         dst = rcu_dereference_check(dtab->netdev_map[i],
 739                                                     rcu_read_lock_bh_held());
 740                         if (!dst)
 741                                 continue;
 742
 743                         if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
 744                                 continue;
 745
 746                         /* we only need n-1 clones; last_dst enqueued below */
 747                         if (!last_dst) {
 748                                 last_dst = dst;
 749                                 continue;
 750                         }
 751
 752                         err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 753                         if (err)
 754                                 return err;
 755
 756                         last_dst = dst;
 757
 758                 }
 759         } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
 760                 for (i = 0; i < dtab->n_buckets; i++) {
 761                         head = dev_map_index_hash(dtab, i);
 762                         hlist_for_each_entry_safe(dst, next, head, index_hlist) {
 763                                 if (!dst)
 764                                         continue;
 765
 766                                 if (is_ifindex_excluded(excluded_devices, num_excluded,
 767                                                         dst->dev->ifindex))
 768                                         continue;
 769
 770                                 /* we only need n-1 clones; last_dst enqueued below */
 771                                 if (!last_dst) {
 772                                         last_dst = dst;
 773                                         continue;
 774                                 }
 775
 776                                 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 777                                 if (err)
 778                                         return err;
 779
 780                                 last_dst = dst;
 781                         }
 782                 }
 783         }
 784
 785         /* consume the first skb and return */
 786         if (last_dst)
 787                 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
 788
 789         /* dtab is empty */
 790         consume_skb(skb);
 791         return 0;
 792 }
 793
 794 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 795 {
 796         struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
 797
 798         return obj ? &obj->val : NULL;
 799 }
 800
 801 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
 802 {
 803         struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
 804                                                                 *(u32 *)key);
 805         return obj ? &obj->val : NULL;
 806 }
 807
 808 static void __dev_map_entry_free(struct rcu_head *rcu)
 809 {
 810         struct bpf_dtab_netdev *dev;
 811
 812         dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
 813         if (dev->xdp_prog)
 814                 bpf_prog_put(dev->xdp_prog);
 815         dev_put(dev->dev);
 816         kfree(dev);
 817 }
 818
 819 static long dev_map_delete_elem(struct bpf_map *map, void *key)
 820 {
 821         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 822         struct bpf_dtab_netdev *old_dev;
 823         int k = *(u32 *)key;
 824
 825         if (k >= map->max_entries)
 826                 return -EINVAL;
 827
 828         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
 829         if (old_dev) {
 830                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 831                 atomic_dec((atomic_t *)&dtab->items);
 832         }
 833         return 0;
 834 }
 835
 836 static long dev_map_hash_delete_elem(struct bpf_map *map, void *key)
 837 {
 838         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 839         struct bpf_dtab_netdev *old_dev;
 840         int k = *(u32 *)key;
 841         unsigned long flags;
 842         int ret = -ENOENT;
 843
 844         spin_lock_irqsave(&dtab->index_lock, flags);
 845
 846         old_dev = __dev_map_hash_lookup_elem(map, k);
 847         if (old_dev) {
 848                 dtab->items--;
 849                 hlist_del_init_rcu(&old_dev->index_hlist);
 850                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 851                 ret = 0;
 852         }
 853         spin_unlock_irqrestore(&dtab->index_lock, flags);
 854
 855         return ret;
 856 }
 857
 858 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 859                                                     struct bpf_dtab *dtab,
 860                                                     struct bpf_devmap_val *val,
 861                                                     unsigned int idx)
 862 {
 863         struct bpf_prog *prog = NULL;
 864         struct bpf_dtab_netdev *dev;
 865
 866         dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
 867                                    GFP_NOWAIT | __GFP_NOWARN,
 868                                    dtab->map.numa_node);
 869         if (!dev)
 870                 return ERR_PTR(-ENOMEM);
 871
 872         dev->dev = dev_get_by_index(net, val->ifindex);
 873         if (!dev->dev)
 874                 goto err_out;
 875
 876         if (val->bpf_prog.fd > 0) {
 877                 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
 878                                              BPF_PROG_TYPE_XDP, false);
 879                 if (IS_ERR(prog))
 880                         goto err_put_dev;
 881                 if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
 882                     !bpf_prog_map_compatible(&dtab->map, prog))
 883                         goto err_put_prog;
 884         }
 885
 886         dev->idx = idx;
 887         if (prog) {
 888                 dev->xdp_prog = prog;
 889                 dev->val.bpf_prog.id = prog->aux->id;
 890         } else {
 891                 dev->xdp_prog = NULL;
 892                 dev->val.bpf_prog.id = 0;
 893         }
 894         dev->val.ifindex = val->ifindex;
 895
 896         return dev;
 897 err_put_prog:
 898         bpf_prog_put(prog);
 899 err_put_dev:
 900         dev_put(dev->dev);
 901 err_out:
 902         kfree(dev);
 903         return ERR_PTR(-EINVAL);
 904 }
 905
 906 static long __dev_map_update_elem(struct net *net, struct bpf_map *map,
 907                                   void *key, void *value, u64 map_flags)
 908 {
 909         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 910         struct bpf_dtab_netdev *dev, *old_dev;
 911         struct bpf_devmap_val val = {};
 912         u32 i = *(u32 *)key;
 913
 914         if (unlikely(map_flags > BPF_EXIST))
 915                 return -EINVAL;
 916         if (unlikely(i >= dtab->map.max_entries))
 917                 return -E2BIG;
 918         if (unlikely(map_flags == BPF_NOEXIST))
 919                 return -EEXIST;
 920
 921         /* already verified value_size <= sizeof val */
 922         memcpy(&val, value, map->value_size);
 923
 924         if (!val.ifindex) {
 925                 dev = NULL;
 926                 /* can not specify fd if ifindex is 0 */
 927                 if (val.bpf_prog.fd > 0)
 928                         return -EINVAL;
 929         } else {
 930                 dev = __dev_map_alloc_node(net, dtab, &val, i);
 931                 if (IS_ERR(dev))
 932                         return PTR_ERR(dev);
 933         }
 934
 935         /* Use call_rcu() here to ensure rcu critical sections have completed
 936          * Remembering the driver side flush operation will happen before the
 937          * net device is removed.
 938          */
 939         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
 940         if (old_dev)
 941                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 942         else
 943                 atomic_inc((atomic_t *)&dtab->items);
 944
 945         return 0;
 946 }
 947
 948 static long dev_map_update_elem(struct bpf_map *map, void *key, void *value,
 949                                 u64 map_flags)
 950 {
 951         return __dev_map_update_elem(current->nsproxy->net_ns,
 952                                      map, key, value, map_flags);
 953 }
 954
 955 static long __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 956                                        void *key, void *value, u64 map_flags)
 957 {
 958         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 959         struct bpf_dtab_netdev *dev, *old_dev;
 960         struct bpf_devmap_val val = {};
 961         u32 idx = *(u32 *)key;
 962         unsigned long flags;
 963         int err = -EEXIST;
 964
 965         /* already verified value_size <= sizeof val */
 966         memcpy(&val, value, map->value_size);
 967
 968         if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
 969                 return -EINVAL;
 970
 971         spin_lock_irqsave(&dtab->index_lock, flags);
 972
 973         old_dev = __dev_map_hash_lookup_elem(map, idx);
 974         if (old_dev && (map_flags & BPF_NOEXIST))
 975                 goto out_err;
 976
 977         dev = __dev_map_alloc_node(net, dtab, &val, idx);
 978         if (IS_ERR(dev)) {
 979                 err = PTR_ERR(dev);
 980                 goto out_err;
 981         }
 982
 983         if (old_dev) {
 984                 hlist_del_rcu(&old_dev->index_hlist);
 985         } else {
 986                 if (dtab->items >= dtab->map.max_entries) {
 987                         spin_unlock_irqrestore(&dtab->index_lock, flags);
 988                         call_rcu(&dev->rcu, __dev_map_entry_free);
 989                         return -E2BIG;
 990                 }
 991                 dtab->items++;
 992         }
 993
 994         hlist_add_head_rcu(&dev->index_hlist,
 995                            dev_map_index_hash(dtab, idx));
 996         spin_unlock_irqrestore(&dtab->index_lock, flags);
 997
 998         if (old_dev)
 999                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
1000
1001         return 0;
1002
1003 out_err:
1004         spin_unlock_irqrestore(&dtab->index_lock, flags);
1005         return err;
1006 }
1007
1008 static long dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
1009                                      u64 map_flags)
1010 {
1011         return __dev_map_hash_update_elem(current->nsproxy->net_ns,
1012                                          map, key, value, map_flags);
1013 }
1014
1015 static long dev_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1016 {
1017         return __bpf_xdp_redirect_map(map, ifindex, flags,
1018                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1019                                       __dev_map_lookup_elem);
1020 }
1021
1022 static long dev_hash_map_redirect(struct bpf_map *map, u64 ifindex, u64 flags)
1023 {
1024         return __bpf_xdp_redirect_map(map, ifindex, flags,
1025                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1026                                       __dev_map_hash_lookup_elem);
1027 }
1028
1029 static u64 dev_map_mem_usage(const struct bpf_map *map)
1030 {
1031         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
1032         u64 usage = sizeof(struct bpf_dtab);
1033
1034         if (map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)
1035                 usage += (u64)dtab->n_buckets * sizeof(struct hlist_head);
1036         else
1037                 usage += (u64)map->max_entries * sizeof(struct bpf_dtab_netdev *);
1038         usage += atomic_read((atomic_t *)&dtab->items) *
1039                          (u64)sizeof(struct bpf_dtab_netdev);
1040         return usage;
1041 }
1042
1043 BTF_ID_LIST_SINGLE(dev_map_btf_ids, struct, bpf_dtab)
1044 const struct bpf_map_ops dev_map_ops = {
1045         .map_meta_equal = bpf_map_meta_equal,
1046         .map_alloc = dev_map_alloc,
1047         .map_free = dev_map_free,
1048         .map_get_next_key = dev_map_get_next_key,
1049         .map_lookup_elem = dev_map_lookup_elem,
1050         .map_update_elem = dev_map_update_elem,
1051         .map_delete_elem = dev_map_delete_elem,
1052         .map_check_btf = map_check_no_btf,
1053         .map_mem_usage = dev_map_mem_usage,
1054         .map_btf_id = &dev_map_btf_ids[0],
1055         .map_redirect = dev_map_redirect,
1056 };
1057
1058 const struct bpf_map_ops dev_map_hash_ops = {
1059         .map_meta_equal = bpf_map_meta_equal,
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         int cpu;
1160
1161         /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1162         BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1163                      offsetof(struct _bpf_dtab_netdev, dev));
1164         register_netdevice_notifier(&dev_map_notifier);
1165
1166         for_each_possible_cpu(cpu)
1167                 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1168         return 0;
1169 }
1170
1171 subsys_initcall(dev_map_init);