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
  52 #define DEV_CREATE_FLAG_MASK \
  53         (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
  54
  55 struct xdp_dev_bulk_queue {
  56         struct xdp_frame *q[DEV_MAP_BULK_SIZE];
  57         struct list_head flush_node;
  58         struct net_device *dev;
  59         struct net_device *dev_rx;
  60         struct bpf_prog *xdp_prog;
  61         unsigned int count;
  62 };
  63
  64 struct bpf_dtab_netdev {
  65         struct net_device *dev; /* must be first member, due to tracepoint */
  66         struct hlist_node index_hlist;
  67         struct bpf_dtab *dtab;
  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                 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(dtab->n_buckets,
 141                                                            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((u64) dtab->map.max_entries *
 148                                                       sizeof(struct bpf_dtab_netdev *),
 149                                                       dtab->map.numa_node);
 150                 if (!dtab->netdev_map)
 151                         return -ENOMEM;
 152         }
 153
 154         return 0;
 155 }
 156
 157 static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
 158 {
 159         struct bpf_dtab *dtab;
 160         int err;
 161
 162         if (!capable(CAP_NET_ADMIN))
 163                 return ERR_PTR(-EPERM);
 164
 165         dtab = kzalloc(sizeof(*dtab), GFP_USER | __GFP_ACCOUNT);
 166         if (!dtab)
 167                 return ERR_PTR(-ENOMEM);
 168
 169         err = dev_map_init_map(dtab, attr);
 170         if (err) {
 171                 kfree(dtab);
 172                 return ERR_PTR(err);
 173         }
 174
 175         spin_lock(&dev_map_lock);
 176         list_add_tail_rcu(&dtab->list, &dev_map_list);
 177         spin_unlock(&dev_map_lock);
 178
 179         return &dtab->map;
 180 }
 181
 182 static void dev_map_free(struct bpf_map *map)
 183 {
 184         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 185         int i;
 186
 187         /* At this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
 188          * so the programs (can be more than one that used this map) were
 189          * disconnected from events. The following synchronize_rcu() guarantees
 190          * both rcu read critical sections complete and waits for
 191          * preempt-disable regions (NAPI being the relevant context here) so we
 192          * are certain there will be no further reads against the netdev_map and
 193          * all flush operations are complete. Flush operations can only be done
 194          * from NAPI context for this reason.
 195          */
 196
 197         spin_lock(&dev_map_lock);
 198         list_del_rcu(&dtab->list);
 199         spin_unlock(&dev_map_lock);
 200
 201         bpf_clear_redirect_map(map);
 202         synchronize_rcu();
 203
 204         /* Make sure prior __dev_map_entry_free() have completed. */
 205         rcu_barrier();
 206
 207         if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
 208                 for (i = 0; i < dtab->n_buckets; i++) {
 209                         struct bpf_dtab_netdev *dev;
 210                         struct hlist_head *head;
 211                         struct hlist_node *next;
 212
 213                         head = dev_map_index_hash(dtab, i);
 214
 215                         hlist_for_each_entry_safe(dev, next, head, index_hlist) {
 216                                 hlist_del_rcu(&dev->index_hlist);
 217                                 if (dev->xdp_prog)
 218                                         bpf_prog_put(dev->xdp_prog);
 219                                 dev_put(dev->dev);
 220                                 kfree(dev);
 221                         }
 222                 }
 223
 224                 bpf_map_area_free(dtab->dev_index_head);
 225         } else {
 226                 for (i = 0; i < dtab->map.max_entries; i++) {
 227                         struct bpf_dtab_netdev *dev;
 228
 229                         dev = rcu_dereference_raw(dtab->netdev_map[i]);
 230                         if (!dev)
 231                                 continue;
 232
 233                         if (dev->xdp_prog)
 234                                 bpf_prog_put(dev->xdp_prog);
 235                         dev_put(dev->dev);
 236                         kfree(dev);
 237                 }
 238
 239                 bpf_map_area_free(dtab->netdev_map);
 240         }
 241
 242         kfree(dtab);
 243 }
 244
 245 static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 246 {
 247         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 248         u32 index = key ? *(u32 *)key : U32_MAX;
 249         u32 *next = next_key;
 250
 251         if (index >= dtab->map.max_entries) {
 252                 *next = 0;
 253                 return 0;
 254         }
 255
 256         if (index == dtab->map.max_entries - 1)
 257                 return -ENOENT;
 258         *next = index + 1;
 259         return 0;
 260 }
 261
 262 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
 263  * by local_bh_disable() (from XDP calls inside NAPI). The
 264  * rcu_read_lock_bh_held() below makes lockdep accept both.
 265  */
 266 static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
 267 {
 268         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 269         struct hlist_head *head = dev_map_index_hash(dtab, key);
 270         struct bpf_dtab_netdev *dev;
 271
 272         hlist_for_each_entry_rcu(dev, head, index_hlist,
 273                                  lockdep_is_held(&dtab->index_lock))
 274                 if (dev->idx == key)
 275                         return dev;
 276
 277         return NULL;
 278 }
 279
 280 static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
 281                                     void *next_key)
 282 {
 283         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 284         u32 idx, *next = next_key;
 285         struct bpf_dtab_netdev *dev, *next_dev;
 286         struct hlist_head *head;
 287         int i = 0;
 288
 289         if (!key)
 290                 goto find_first;
 291
 292         idx = *(u32 *)key;
 293
 294         dev = __dev_map_hash_lookup_elem(map, idx);
 295         if (!dev)
 296                 goto find_first;
 297
 298         next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
 299                                     struct bpf_dtab_netdev, index_hlist);
 300
 301         if (next_dev) {
 302                 *next = next_dev->idx;
 303                 return 0;
 304         }
 305
 306         i = idx & (dtab->n_buckets - 1);
 307         i++;
 308
 309  find_first:
 310         for (; i < dtab->n_buckets; i++) {
 311                 head = dev_map_index_hash(dtab, i);
 312
 313                 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
 314                                             struct bpf_dtab_netdev,
 315                                             index_hlist);
 316                 if (next_dev) {
 317                         *next = next_dev->idx;
 318                         return 0;
 319                 }
 320         }
 321
 322         return -ENOENT;
 323 }
 324
 325 bool dev_map_can_have_prog(struct bpf_map *map)
 326 {
 327         if ((map->map_type == BPF_MAP_TYPE_DEVMAP ||
 328              map->map_type == BPF_MAP_TYPE_DEVMAP_HASH) &&
 329             map->value_size != offsetofend(struct bpf_devmap_val, ifindex))
 330                 return true;
 331
 332         return false;
 333 }
 334
 335 static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
 336                                 struct xdp_frame **frames, int n,
 337                                 struct net_device *dev)
 338 {
 339         struct xdp_txq_info txq = { .dev = dev };
 340         struct xdp_buff xdp;
 341         int i, nframes = 0;
 342
 343         for (i = 0; i < n; i++) {
 344                 struct xdp_frame *xdpf = frames[i];
 345                 u32 act;
 346                 int err;
 347
 348                 xdp_convert_frame_to_buff(xdpf, &xdp);
 349                 xdp.txq = &txq;
 350
 351                 act = bpf_prog_run_xdp(xdp_prog, &xdp);
 352                 switch (act) {
 353                 case XDP_PASS:
 354                         err = xdp_update_frame_from_buff(&xdp, xdpf);
 355                         if (unlikely(err < 0))
 356                                 xdp_return_frame_rx_napi(xdpf);
 357                         else
 358                                 frames[nframes++] = xdpf;
 359                         break;
 360                 default:
 361                         bpf_warn_invalid_xdp_action(act);
 362                         fallthrough;
 363                 case XDP_ABORTED:
 364                         trace_xdp_exception(dev, xdp_prog, act);
 365                         fallthrough;
 366                 case XDP_DROP:
 367                         xdp_return_frame_rx_napi(xdpf);
 368                         break;
 369                 }
 370         }
 371         return nframes; /* sent frames count */
 372 }
 373
 374 static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
 375 {
 376         struct net_device *dev = bq->dev;
 377         unsigned int cnt = bq->count;
 378         int sent = 0, err = 0;
 379         int to_send = cnt;
 380         int i;
 381
 382         if (unlikely(!cnt))
 383                 return;
 384
 385         for (i = 0; i < cnt; i++) {
 386                 struct xdp_frame *xdpf = bq->q[i];
 387
 388                 prefetch(xdpf);
 389         }
 390
 391         if (bq->xdp_prog) {
 392                 to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
 393                 if (!to_send)
 394                         goto out;
 395         }
 396
 397         sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
 398         if (sent < 0) {
 399                 /* If ndo_xdp_xmit fails with an errno, no frames have
 400                  * been xmit'ed.
 401                  */
 402                 err = sent;
 403                 sent = 0;
 404         }
 405
 406         /* If not all frames have been transmitted, it is our
 407          * responsibility to free them
 408          */
 409         for (i = sent; unlikely(i < to_send); i++)
 410                 xdp_return_frame_rx_napi(bq->q[i]);
 411
 412 out:
 413         bq->count = 0;
 414         trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
 415 }
 416
 417 /* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
 418  * driver before returning from its napi->poll() routine. See the comment above
 419  * xdp_do_flush() in filter.c.
 420  */
 421 void __dev_flush(void)
 422 {
 423         struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
 424         struct xdp_dev_bulk_queue *bq, *tmp;
 425
 426         list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
 427                 bq_xmit_all(bq, XDP_XMIT_FLUSH);
 428                 bq->dev_rx = NULL;
 429                 bq->xdp_prog = NULL;
 430                 __list_del_clearprev(&bq->flush_node);
 431         }
 432 }
 433
 434 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
 435  * by local_bh_disable() (from XDP calls inside NAPI). The
 436  * rcu_read_lock_bh_held() below makes lockdep accept both.
 437  */
 438 static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
 439 {
 440         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 441         struct bpf_dtab_netdev *obj;
 442
 443         if (key >= map->max_entries)
 444                 return NULL;
 445
 446         obj = rcu_dereference_check(dtab->netdev_map[key],
 447                                     rcu_read_lock_bh_held());
 448         return obj;
 449 }
 450
 451 /* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
 452  * variable access, and map elements stick around. See comment above
 453  * xdp_do_flush() in filter.c.
 454  */
 455 static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 456                        struct net_device *dev_rx, struct bpf_prog *xdp_prog)
 457 {
 458         struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
 459         struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
 460
 461         if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
 462                 bq_xmit_all(bq, 0);
 463
 464         /* Ingress dev_rx will be the same for all xdp_frame's in
 465          * bulk_queue, because bq stored per-CPU and must be flushed
 466          * from net_device drivers NAPI func end.
 467          *
 468          * Do the same with xdp_prog and flush_list since these fields
 469          * are only ever modified together.
 470          */
 471         if (!bq->dev_rx) {
 472                 bq->dev_rx = dev_rx;
 473                 bq->xdp_prog = xdp_prog;
 474                 list_add(&bq->flush_node, flush_list);
 475         }
 476
 477         bq->q[bq->count++] = xdpf;
 478 }
 479
 480 static inline int __xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
 481                                 struct net_device *dev_rx,
 482                                 struct bpf_prog *xdp_prog)
 483 {
 484         struct xdp_frame *xdpf;
 485         int err;
 486
 487         if (!dev->netdev_ops->ndo_xdp_xmit)
 488                 return -EOPNOTSUPP;
 489
 490         err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
 491         if (unlikely(err))
 492                 return err;
 493
 494         xdpf = xdp_convert_buff_to_frame(xdp);
 495         if (unlikely(!xdpf))
 496                 return -EOVERFLOW;
 497
 498         bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
 499         return 0;
 500 }
 501
 502 int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
 503                     struct net_device *dev_rx)
 504 {
 505         return __xdp_enqueue(dev, xdp, dev_rx, NULL);
 506 }
 507
 508 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
 509                     struct net_device *dev_rx)
 510 {
 511         struct net_device *dev = dst->dev;
 512
 513         return __xdp_enqueue(dev, xdp, dev_rx, dst->xdp_prog);
 514 }
 515
 516 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_buff *xdp,
 517                          int exclude_ifindex)
 518 {
 519         if (!obj || obj->dev->ifindex == exclude_ifindex ||
 520             !obj->dev->netdev_ops->ndo_xdp_xmit)
 521                 return false;
 522
 523         if (xdp_ok_fwd_dev(obj->dev, xdp->data_end - xdp->data))
 524                 return false;
 525
 526         return true;
 527 }
 528
 529 static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
 530                                  struct net_device *dev_rx,
 531                                  struct xdp_frame *xdpf)
 532 {
 533         struct xdp_frame *nxdpf;
 534
 535         nxdpf = xdpf_clone(xdpf);
 536         if (!nxdpf)
 537                 return -ENOMEM;
 538
 539         bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
 540
 541         return 0;
 542 }
 543
 544 int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
 545                           struct bpf_map *map, bool exclude_ingress)
 546 {
 547         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 548         int exclude_ifindex = exclude_ingress ? dev_rx->ifindex : 0;
 549         struct bpf_dtab_netdev *dst, *last_dst = NULL;
 550         struct hlist_head *head;
 551         struct xdp_frame *xdpf;
 552         unsigned int i;
 553         int err;
 554
 555         xdpf = xdp_convert_buff_to_frame(xdp);
 556         if (unlikely(!xdpf))
 557                 return -EOVERFLOW;
 558
 559         if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 560                 for (i = 0; i < map->max_entries; i++) {
 561                         dst = rcu_dereference_check(dtab->netdev_map[i],
 562                                                     rcu_read_lock_bh_held());
 563                         if (!is_valid_dst(dst, xdp, exclude_ifindex))
 564                                 continue;
 565
 566                         /* we only need n-1 clones; last_dst enqueued below */
 567                         if (!last_dst) {
 568                                 last_dst = dst;
 569                                 continue;
 570                         }
 571
 572                         err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 573                         if (err)
 574                                 return err;
 575
 576                         last_dst = dst;
 577                 }
 578         } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
 579                 for (i = 0; i < dtab->n_buckets; i++) {
 580                         head = dev_map_index_hash(dtab, i);
 581                         hlist_for_each_entry_rcu(dst, head, index_hlist,
 582                                                  lockdep_is_held(&dtab->index_lock)) {
 583                                 if (!is_valid_dst(dst, xdp, exclude_ifindex))
 584                                         continue;
 585
 586                                 /* we only need n-1 clones; last_dst enqueued below */
 587                                 if (!last_dst) {
 588                                         last_dst = dst;
 589                                         continue;
 590                                 }
 591
 592                                 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 593                                 if (err)
 594                                         return err;
 595
 596                                 last_dst = dst;
 597                         }
 598                 }
 599         }
 600
 601         /* consume the last copy of the frame */
 602         if (last_dst)
 603                 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
 604         else
 605                 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
 606
 607         return 0;
 608 }
 609
 610 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 611                              struct bpf_prog *xdp_prog)
 612 {
 613         int err;
 614
 615         err = xdp_ok_fwd_dev(dst->dev, skb->len);
 616         if (unlikely(err))
 617                 return err;
 618         skb->dev = dst->dev;
 619         generic_xdp_tx(skb, xdp_prog);
 620
 621         return 0;
 622 }
 623
 624 static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
 625                                   struct sk_buff *skb,
 626                                   struct bpf_prog *xdp_prog)
 627 {
 628         struct sk_buff *nskb;
 629         int err;
 630
 631         nskb = skb_clone(skb, GFP_ATOMIC);
 632         if (!nskb)
 633                 return -ENOMEM;
 634
 635         err = dev_map_generic_redirect(dst, nskb, xdp_prog);
 636         if (unlikely(err)) {
 637                 consume_skb(nskb);
 638                 return err;
 639         }
 640
 641         return 0;
 642 }
 643
 644 int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
 645                            struct bpf_prog *xdp_prog, struct bpf_map *map,
 646                            bool exclude_ingress)
 647 {
 648         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 649         int exclude_ifindex = exclude_ingress ? dev->ifindex : 0;
 650         struct bpf_dtab_netdev *dst, *last_dst = NULL;
 651         struct hlist_head *head;
 652         struct hlist_node *next;
 653         unsigned int i;
 654         int err;
 655
 656         if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 657                 for (i = 0; i < map->max_entries; i++) {
 658                         dst = rcu_dereference_check(dtab->netdev_map[i],
 659                                                     rcu_read_lock_bh_held());
 660                         if (!dst || dst->dev->ifindex == exclude_ifindex)
 661                                 continue;
 662
 663                         /* we only need n-1 clones; last_dst enqueued below */
 664                         if (!last_dst) {
 665                                 last_dst = dst;
 666                                 continue;
 667                         }
 668
 669                         err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 670                         if (err)
 671                                 return err;
 672
 673                         last_dst = dst;
 674                 }
 675         } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
 676                 for (i = 0; i < dtab->n_buckets; i++) {
 677                         head = dev_map_index_hash(dtab, i);
 678                         hlist_for_each_entry_safe(dst, next, head, index_hlist) {
 679                                 if (!dst || dst->dev->ifindex == exclude_ifindex)
 680                                         continue;
 681
 682                                 /* we only need n-1 clones; last_dst enqueued below */
 683                                 if (!last_dst) {
 684                                         last_dst = dst;
 685                                         continue;
 686                                 }
 687
 688                                 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 689                                 if (err)
 690                                         return err;
 691
 692                                 last_dst = dst;
 693                         }
 694                 }
 695         }
 696
 697         /* consume the first skb and return */
 698         if (last_dst)
 699                 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
 700
 701         /* dtab is empty */
 702         consume_skb(skb);
 703         return 0;
 704 }
 705
 706 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 707 {
 708         struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
 709
 710         return obj ? &obj->val : NULL;
 711 }
 712
 713 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
 714 {
 715         struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
 716                                                                 *(u32 *)key);
 717         return obj ? &obj->val : NULL;
 718 }
 719
 720 static void __dev_map_entry_free(struct rcu_head *rcu)
 721 {
 722         struct bpf_dtab_netdev *dev;
 723
 724         dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
 725         if (dev->xdp_prog)
 726                 bpf_prog_put(dev->xdp_prog);
 727         dev_put(dev->dev);
 728         kfree(dev);
 729 }
 730
 731 static int dev_map_delete_elem(struct bpf_map *map, void *key)
 732 {
 733         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 734         struct bpf_dtab_netdev *old_dev;
 735         int k = *(u32 *)key;
 736
 737         if (k >= map->max_entries)
 738                 return -EINVAL;
 739
 740         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
 741         if (old_dev)
 742                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 743         return 0;
 744 }
 745
 746 static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
 747 {
 748         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 749         struct bpf_dtab_netdev *old_dev;
 750         int k = *(u32 *)key;
 751         unsigned long flags;
 752         int ret = -ENOENT;
 753
 754         spin_lock_irqsave(&dtab->index_lock, flags);
 755
 756         old_dev = __dev_map_hash_lookup_elem(map, k);
 757         if (old_dev) {
 758                 dtab->items--;
 759                 hlist_del_init_rcu(&old_dev->index_hlist);
 760                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 761                 ret = 0;
 762         }
 763         spin_unlock_irqrestore(&dtab->index_lock, flags);
 764
 765         return ret;
 766 }
 767
 768 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 769                                                     struct bpf_dtab *dtab,
 770                                                     struct bpf_devmap_val *val,
 771                                                     unsigned int idx)
 772 {
 773         struct bpf_prog *prog = NULL;
 774         struct bpf_dtab_netdev *dev;
 775
 776         dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
 777                                    GFP_ATOMIC | __GFP_NOWARN,
 778                                    dtab->map.numa_node);
 779         if (!dev)
 780                 return ERR_PTR(-ENOMEM);
 781
 782         dev->dev = dev_get_by_index(net, val->ifindex);
 783         if (!dev->dev)
 784                 goto err_out;
 785
 786         if (val->bpf_prog.fd > 0) {
 787                 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
 788                                              BPF_PROG_TYPE_XDP, false);
 789                 if (IS_ERR(prog))
 790                         goto err_put_dev;
 791                 if (prog->expected_attach_type != BPF_XDP_DEVMAP)
 792                         goto err_put_prog;
 793         }
 794
 795         dev->idx = idx;
 796         dev->dtab = dtab;
 797         if (prog) {
 798                 dev->xdp_prog = prog;
 799                 dev->val.bpf_prog.id = prog->aux->id;
 800         } else {
 801                 dev->xdp_prog = NULL;
 802                 dev->val.bpf_prog.id = 0;
 803         }
 804         dev->val.ifindex = val->ifindex;
 805
 806         return dev;
 807 err_put_prog:
 808         bpf_prog_put(prog);
 809 err_put_dev:
 810         dev_put(dev->dev);
 811 err_out:
 812         kfree(dev);
 813         return ERR_PTR(-EINVAL);
 814 }
 815
 816 static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
 817                                  void *key, void *value, u64 map_flags)
 818 {
 819         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 820         struct bpf_dtab_netdev *dev, *old_dev;
 821         struct bpf_devmap_val val = {};
 822         u32 i = *(u32 *)key;
 823
 824         if (unlikely(map_flags > BPF_EXIST))
 825                 return -EINVAL;
 826         if (unlikely(i >= dtab->map.max_entries))
 827                 return -E2BIG;
 828         if (unlikely(map_flags == BPF_NOEXIST))
 829                 return -EEXIST;
 830
 831         /* already verified value_size <= sizeof val */
 832         memcpy(&val, value, map->value_size);
 833
 834         if (!val.ifindex) {
 835                 dev = NULL;
 836                 /* can not specify fd if ifindex is 0 */
 837                 if (val.bpf_prog.fd > 0)
 838                         return -EINVAL;
 839         } else {
 840                 dev = __dev_map_alloc_node(net, dtab, &val, i);
 841                 if (IS_ERR(dev))
 842                         return PTR_ERR(dev);
 843         }
 844
 845         /* Use call_rcu() here to ensure rcu critical sections have completed
 846          * Remembering the driver side flush operation will happen before the
 847          * net device is removed.
 848          */
 849         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
 850         if (old_dev)
 851                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 852
 853         return 0;
 854 }
 855
 856 static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
 857                                u64 map_flags)
 858 {
 859         return __dev_map_update_elem(current->nsproxy->net_ns,
 860                                      map, key, value, map_flags);
 861 }
 862
 863 static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 864                                      void *key, void *value, u64 map_flags)
 865 {
 866         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 867         struct bpf_dtab_netdev *dev, *old_dev;
 868         struct bpf_devmap_val val = {};
 869         u32 idx = *(u32 *)key;
 870         unsigned long flags;
 871         int err = -EEXIST;
 872
 873         /* already verified value_size <= sizeof val */
 874         memcpy(&val, value, map->value_size);
 875
 876         if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
 877                 return -EINVAL;
 878
 879         spin_lock_irqsave(&dtab->index_lock, flags);
 880
 881         old_dev = __dev_map_hash_lookup_elem(map, idx);
 882         if (old_dev && (map_flags & BPF_NOEXIST))
 883                 goto out_err;
 884
 885         dev = __dev_map_alloc_node(net, dtab, &val, idx);
 886         if (IS_ERR(dev)) {
 887                 err = PTR_ERR(dev);
 888                 goto out_err;
 889         }
 890
 891         if (old_dev) {
 892                 hlist_del_rcu(&old_dev->index_hlist);
 893         } else {
 894                 if (dtab->items >= dtab->map.max_entries) {
 895                         spin_unlock_irqrestore(&dtab->index_lock, flags);
 896                         call_rcu(&dev->rcu, __dev_map_entry_free);
 897                         return -E2BIG;
 898                 }
 899                 dtab->items++;
 900         }
 901
 902         hlist_add_head_rcu(&dev->index_hlist,
 903                            dev_map_index_hash(dtab, idx));
 904         spin_unlock_irqrestore(&dtab->index_lock, flags);
 905
 906         if (old_dev)
 907                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 908
 909         return 0;
 910
 911 out_err:
 912         spin_unlock_irqrestore(&dtab->index_lock, flags);
 913         return err;
 914 }
 915
 916 static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
 917                                    u64 map_flags)
 918 {
 919         return __dev_map_hash_update_elem(current->nsproxy->net_ns,
 920                                          map, key, value, map_flags);
 921 }
 922
 923 static int dev_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
 924 {
 925         return __bpf_xdp_redirect_map(map, ifindex, flags,
 926                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
 927                                       __dev_map_lookup_elem);
 928 }
 929
 930 static int dev_hash_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
 931 {
 932         return __bpf_xdp_redirect_map(map, ifindex, flags,
 933                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
 934                                       __dev_map_hash_lookup_elem);
 935 }
 936
 937 static int dev_map_btf_id;
 938 const struct bpf_map_ops dev_map_ops = {
 939         .map_meta_equal = bpf_map_meta_equal,
 940         .map_alloc = dev_map_alloc,
 941         .map_free = dev_map_free,
 942         .map_get_next_key = dev_map_get_next_key,
 943         .map_lookup_elem = dev_map_lookup_elem,
 944         .map_update_elem = dev_map_update_elem,
 945         .map_delete_elem = dev_map_delete_elem,
 946         .map_check_btf = map_check_no_btf,
 947         .map_btf_name = "bpf_dtab",
 948         .map_btf_id = &dev_map_btf_id,
 949         .map_redirect = dev_map_redirect,
 950 };
 951
 952 static int dev_map_hash_map_btf_id;
 953 const struct bpf_map_ops dev_map_hash_ops = {
 954         .map_meta_equal = bpf_map_meta_equal,
 955         .map_alloc = dev_map_alloc,
 956         .map_free = dev_map_free,
 957         .map_get_next_key = dev_map_hash_get_next_key,
 958         .map_lookup_elem = dev_map_hash_lookup_elem,
 959         .map_update_elem = dev_map_hash_update_elem,
 960         .map_delete_elem = dev_map_hash_delete_elem,
 961         .map_check_btf = map_check_no_btf,
 962         .map_btf_name = "bpf_dtab",
 963         .map_btf_id = &dev_map_hash_map_btf_id,
 964         .map_redirect = dev_hash_map_redirect,
 965 };
 966
 967 static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
 968                                        struct net_device *netdev)
 969 {
 970         unsigned long flags;
 971         u32 i;
 972
 973         spin_lock_irqsave(&dtab->index_lock, flags);
 974         for (i = 0; i < dtab->n_buckets; i++) {
 975                 struct bpf_dtab_netdev *dev;
 976                 struct hlist_head *head;
 977                 struct hlist_node *next;
 978
 979                 head = dev_map_index_hash(dtab, i);
 980
 981                 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
 982                         if (netdev != dev->dev)
 983                                 continue;
 984
 985                         dtab->items--;
 986                         hlist_del_rcu(&dev->index_hlist);
 987                         call_rcu(&dev->rcu, __dev_map_entry_free);
 988                 }
 989         }
 990         spin_unlock_irqrestore(&dtab->index_lock, flags);
 991 }
 992
 993 static int dev_map_notification(struct notifier_block *notifier,
 994                                 ulong event, void *ptr)
 995 {
 996         struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
 997         struct bpf_dtab *dtab;
 998         int i, cpu;
 999
1000         switch (event) {
1001         case NETDEV_REGISTER:
1002                 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1003                         break;
1004
1005                 /* will be freed in free_netdev() */
1006                 netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1007                 if (!netdev->xdp_bulkq)
1008                         return NOTIFY_BAD;
1009
1010                 for_each_possible_cpu(cpu)
1011                         per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1012                 break;
1013         case NETDEV_UNREGISTER:
1014                 /* This rcu_read_lock/unlock pair is needed because
1015                  * dev_map_list is an RCU list AND to ensure a delete
1016                  * operation does not free a netdev_map entry while we
1017                  * are comparing it against the netdev being unregistered.
1018                  */
1019                 rcu_read_lock();
1020                 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
1021                         if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
1022                                 dev_map_hash_remove_netdev(dtab, netdev);
1023                                 continue;
1024                         }
1025
1026                         for (i = 0; i < dtab->map.max_entries; i++) {
1027                                 struct bpf_dtab_netdev *dev, *odev;
1028
1029                                 dev = rcu_dereference(dtab->netdev_map[i]);
1030                                 if (!dev || netdev != dev->dev)
1031                                         continue;
1032                                 odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1033                                 if (dev == odev)
1034                                         call_rcu(&dev->rcu,
1035                                                  __dev_map_entry_free);
1036                         }
1037                 }
1038                 rcu_read_unlock();
1039                 break;
1040         default:
1041                 break;
1042         }
1043         return NOTIFY_OK;
1044 }
1045
1046 static struct notifier_block dev_map_notifier = {
1047         .notifier_call = dev_map_notification,
1048 };
1049
1050 static int __init dev_map_init(void)
1051 {
1052         int cpu;
1053
1054         /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1055         BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1056                      offsetof(struct _bpf_dtab_netdev, dev));
1057         register_netdevice_notifier(&dev_map_notifier);
1058
1059         for_each_possible_cpu(cpu)
1060                 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1061         return 0;
1062 }
1063
1064 subsys_initcall(dev_map_init);