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_dtab *dtab;
  69         struct bpf_prog *xdp_prog;
  70         struct rcu_head rcu;
  71         unsigned int idx;
  72         struct bpf_devmap_val val;
  73 };
  74
  75 struct bpf_dtab {
  76         struct bpf_map map;
  77         struct bpf_dtab_netdev __rcu **netdev_map; /* DEVMAP type only */
  78         struct list_head list;
  79
  80         /* these are only used for DEVMAP_HASH type maps */
  81         struct hlist_head *dev_index_head;
  82         spinlock_t index_lock;
  83         unsigned int items;
  84         u32 n_buckets;
  85 };
  86
  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);
  90
  91 static struct hlist_head *dev_map_create_hash(unsigned int entries,
  92                                               int numa_node)
  93 {
  94         int i;
  95         struct hlist_head *hash;
  96
  97         hash = bpf_map_area_alloc((u64) entries * sizeof(*hash), numa_node);
  98         if (hash != NULL)
  99                 for (i = 0; i < entries; i++)
 100                         INIT_HLIST_HEAD(&hash[i]);
 101
 102         return hash;
 103 }
 104
 105 static inline struct hlist_head *dev_map_index_hash(struct bpf_dtab *dtab,
 106                                                     int idx)
 107 {
 108         return &dtab->dev_index_head[idx & (dtab->n_buckets - 1)];
 109 }
 110
 111 static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
 112 {
 113         u32 valsize = attr->value_size;
 114
 115         /* check sanity of attributes. 2 value sizes supported:
 116          * 4 bytes: ifindex
 117          * 8 bytes: ifindex + prog fd
 118          */
 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)
 123                 return -EINVAL;
 124
 125         /* Lookup returns a pointer straight to dev->ifindex, so make sure the
 126          * verifier prevents writes from the BPF side
 127          */
 128         attr->map_flags |= BPF_F_RDONLY_PROG;
 129
 130
 131         bpf_map_init_from_attr(&dtab->map, attr);
 132
 133         if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
 134                 dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
 135
 136                 if (!dtab->n_buckets) /* Overflow check */
 137                         return -EINVAL;
 138         }
 139
 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)
 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         if (!capable(CAP_NET_ADMIN))
 164                 return ERR_PTR(-EPERM);
 165
 166         dtab = kzalloc(sizeof(*dtab), GFP_USER | __GFP_ACCOUNT);
 167         if (!dtab)
 168                 return ERR_PTR(-ENOMEM);
 169
 170         err = dev_map_init_map(dtab, attr);
 171         if (err) {
 172                 kfree(dtab);
 173                 return ERR_PTR(err);
 174         }
 175
 176         spin_lock(&dev_map_lock);
 177         list_add_tail_rcu(&dtab->list, &dev_map_list);
 178         spin_unlock(&dev_map_lock);
 179
 180         return &dtab->map;
 181 }
 182
 183 static void dev_map_free(struct bpf_map *map)
 184 {
 185         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 186         int i;
 187
 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.
 196          */
 197
 198         spin_lock(&dev_map_lock);
 199         list_del_rcu(&dtab->list);
 200         spin_unlock(&dev_map_lock);
 201
 202         bpf_clear_redirect_map(map);
 203         synchronize_rcu();
 204
 205         /* Make sure prior __dev_map_entry_free() have completed. */
 206         rcu_barrier();
 207
 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;
 213
 214                         head = dev_map_index_hash(dtab, i);
 215
 216                         hlist_for_each_entry_safe(dev, next, head, index_hlist) {
 217                                 hlist_del_rcu(&dev->index_hlist);
 218                                 if (dev->xdp_prog)
 219                                         bpf_prog_put(dev->xdp_prog);
 220                                 dev_put(dev->dev);
 221                                 kfree(dev);
 222                         }
 223                 }
 224
 225                 bpf_map_area_free(dtab->dev_index_head);
 226         } else {
 227                 for (i = 0; i < dtab->map.max_entries; i++) {
 228                         struct bpf_dtab_netdev *dev;
 229
 230                         dev = rcu_dereference_raw(dtab->netdev_map[i]);
 231                         if (!dev)
 232                                 continue;
 233
 234                         if (dev->xdp_prog)
 235                                 bpf_prog_put(dev->xdp_prog);
 236                         dev_put(dev->dev);
 237                         kfree(dev);
 238                 }
 239
 240                 bpf_map_area_free(dtab->netdev_map);
 241         }
 242
 243         kfree(dtab);
 244 }
 245
 246 static int dev_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 247 {
 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;
 251
 252         if (index >= dtab->map.max_entries) {
 253                 *next = 0;
 254                 return 0;
 255         }
 256
 257         if (index == dtab->map.max_entries - 1)
 258                 return -ENOENT;
 259         *next = index + 1;
 260         return 0;
 261 }
 262
 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.
 266  */
 267 static void *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key)
 268 {
 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;
 272
 273         hlist_for_each_entry_rcu(dev, head, index_hlist,
 274                                  lockdep_is_held(&dtab->index_lock))
 275                 if (dev->idx == key)
 276                         return dev;
 277
 278         return NULL;
 279 }
 280
 281 static int dev_map_hash_get_next_key(struct bpf_map *map, void *key,
 282                                     void *next_key)
 283 {
 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;
 288         int i = 0;
 289
 290         if (!key)
 291                 goto find_first;
 292
 293         idx = *(u32 *)key;
 294
 295         dev = __dev_map_hash_lookup_elem(map, idx);
 296         if (!dev)
 297                 goto find_first;
 298
 299         next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&dev->index_hlist)),
 300                                     struct bpf_dtab_netdev, index_hlist);
 301
 302         if (next_dev) {
 303                 *next = next_dev->idx;
 304                 return 0;
 305         }
 306
 307         i = idx & (dtab->n_buckets - 1);
 308         i++;
 309
 310  find_first:
 311         for (; i < dtab->n_buckets; i++) {
 312                 head = dev_map_index_hash(dtab, i);
 313
 314                 next_dev = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
 315                                             struct bpf_dtab_netdev,
 316                                             index_hlist);
 317                 if (next_dev) {
 318                         *next = next_dev->idx;
 319                         return 0;
 320                 }
 321         }
 322
 323         return -ENOENT;
 324 }
 325
 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)
 329 {
 330         struct xdp_txq_info txq = { .dev = dev };
 331         struct xdp_buff xdp;
 332         int i, nframes = 0;
 333
 334         for (i = 0; i < n; i++) {
 335                 struct xdp_frame *xdpf = frames[i];
 336                 u32 act;
 337                 int err;
 338
 339                 xdp_convert_frame_to_buff(xdpf, &xdp);
 340                 xdp.txq = &txq;
 341
 342                 act = bpf_prog_run_xdp(xdp_prog, &xdp);
 343                 switch (act) {
 344                 case XDP_PASS:
 345                         err = xdp_update_frame_from_buff(&xdp, xdpf);
 346                         if (unlikely(err < 0))
 347                                 xdp_return_frame_rx_napi(xdpf);
 348                         else
 349                                 frames[nframes++] = xdpf;
 350                         break;
 351                 default:
 352                         bpf_warn_invalid_xdp_action(NULL, xdp_prog, act);
 353                         fallthrough;
 354                 case XDP_ABORTED:
 355                         trace_xdp_exception(dev, xdp_prog, act);
 356                         fallthrough;
 357                 case XDP_DROP:
 358                         xdp_return_frame_rx_napi(xdpf);
 359                         break;
 360                 }
 361         }
 362         return nframes; /* sent frames count */
 363 }
 364
 365 static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
 366 {
 367         struct net_device *dev = bq->dev;
 368         unsigned int cnt = bq->count;
 369         int sent = 0, err = 0;
 370         int to_send = cnt;
 371         int i;
 372
 373         if (unlikely(!cnt))
 374                 return;
 375
 376         for (i = 0; i < cnt; i++) {
 377                 struct xdp_frame *xdpf = bq->q[i];
 378
 379                 prefetch(xdpf);
 380         }
 381
 382         if (bq->xdp_prog) {
 383                 to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
 384                 if (!to_send)
 385                         goto out;
 386         }
 387
 388         sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
 389         if (sent < 0) {
 390                 /* If ndo_xdp_xmit fails with an errno, no frames have
 391                  * been xmit'ed.
 392                  */
 393                 err = sent;
 394                 sent = 0;
 395         }
 396
 397         /* If not all frames have been transmitted, it is our
 398          * responsibility to free them
 399          */
 400         for (i = sent; unlikely(i < to_send); i++)
 401                 xdp_return_frame_rx_napi(bq->q[i]);
 402
 403 out:
 404         bq->count = 0;
 405         trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
 406 }
 407
 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.
 411  */
 412 void __dev_flush(void)
 413 {
 414         struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
 415         struct xdp_dev_bulk_queue *bq, *tmp;
 416
 417         list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
 418                 bq_xmit_all(bq, XDP_XMIT_FLUSH);
 419                 bq->dev_rx = NULL;
 420                 bq->xdp_prog = NULL;
 421                 __list_del_clearprev(&bq->flush_node);
 422         }
 423 }
 424
 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.
 428  */
 429 static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
 430 {
 431         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 432         struct bpf_dtab_netdev *obj;
 433
 434         if (key >= map->max_entries)
 435                 return NULL;
 436
 437         obj = rcu_dereference_check(dtab->netdev_map[key],
 438                                     rcu_read_lock_bh_held());
 439         return obj;
 440 }
 441
 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.
 445  */
 446 static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 447                        struct net_device *dev_rx, struct bpf_prog *xdp_prog)
 448 {
 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);
 451
 452         if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
 453                 bq_xmit_all(bq, 0);
 454
 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.
 458          *
 459          * Do the same with xdp_prog and flush_list since these fields
 460          * are only ever modified together.
 461          */
 462         if (!bq->dev_rx) {
 463                 bq->dev_rx = dev_rx;
 464                 bq->xdp_prog = xdp_prog;
 465                 list_add(&bq->flush_node, flush_list);
 466         }
 467
 468         bq->q[bq->count++] = xdpf;
 469 }
 470
 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)
 474 {
 475         int err;
 476
 477         if (!dev->netdev_ops->ndo_xdp_xmit)
 478                 return -EOPNOTSUPP;
 479
 480         err = xdp_ok_fwd_dev(dev, xdp_get_frame_len(xdpf));
 481         if (unlikely(err))
 482                 return err;
 483
 484         bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
 485         return 0;
 486 }
 487
 488 static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
 489 {
 490         struct xdp_txq_info txq = { .dev = dst->dev };
 491         struct xdp_buff xdp;
 492         u32 act;
 493
 494         if (!dst->xdp_prog)
 495                 return XDP_PASS;
 496
 497         __skb_pull(skb, skb->mac_len);
 498         xdp.txq = &txq;
 499
 500         act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
 501         switch (act) {
 502         case XDP_PASS:
 503                 __skb_push(skb, skb->mac_len);
 504                 break;
 505         default:
 506                 bpf_warn_invalid_xdp_action(NULL, dst->xdp_prog, act);
 507                 fallthrough;
 508         case XDP_ABORTED:
 509                 trace_xdp_exception(dst->dev, dst->xdp_prog, act);
 510                 fallthrough;
 511         case XDP_DROP:
 512                 kfree_skb(skb);
 513                 break;
 514         }
 515
 516         return act;
 517 }
 518
 519 int dev_xdp_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 520                     struct net_device *dev_rx)
 521 {
 522         return __xdp_enqueue(dev, xdpf, dev_rx, NULL);
 523 }
 524
 525 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_frame *xdpf,
 526                     struct net_device *dev_rx)
 527 {
 528         struct net_device *dev = dst->dev;
 529
 530         return __xdp_enqueue(dev, xdpf, dev_rx, dst->xdp_prog);
 531 }
 532
 533 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_frame *xdpf)
 534 {
 535         if (!obj ||
 536             !obj->dev->netdev_ops->ndo_xdp_xmit)
 537                 return false;
 538
 539         if (xdp_ok_fwd_dev(obj->dev, xdp_get_frame_len(xdpf)))
 540                 return false;
 541
 542         return true;
 543 }
 544
 545 static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
 546                                  struct net_device *dev_rx,
 547                                  struct xdp_frame *xdpf)
 548 {
 549         struct xdp_frame *nxdpf;
 550
 551         nxdpf = xdpf_clone(xdpf);
 552         if (!nxdpf)
 553                 return -ENOMEM;
 554
 555         bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
 556
 557         return 0;
 558 }
 559
 560 static inline bool is_ifindex_excluded(int *excluded, int num_excluded, int ifindex)
 561 {
 562         while (num_excluded--) {
 563                 if (ifindex == excluded[num_excluded])
 564                         return true;
 565         }
 566         return false;
 567 }
 568
 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.
 572  */
 573 static int get_upper_ifindexes(struct net_device *dev, int *indexes)
 574 {
 575         struct net_device *upper;
 576         struct list_head *iter;
 577         int n = 0;
 578
 579         netdev_for_each_upper_dev_rcu(dev, upper, iter) {
 580                 indexes[n++] = upper->ifindex;
 581         }
 582         return n;
 583 }
 584
 585 int dev_map_enqueue_multi(struct xdp_frame *xdpf, struct net_device *dev_rx,
 586                           struct bpf_map *map, bool exclude_ingress)
 587 {
 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;
 593         unsigned int i;
 594         int err;
 595
 596         if (exclude_ingress) {
 597                 num_excluded = get_upper_ifindexes(dev_rx, excluded_devices);
 598                 excluded_devices[num_excluded++] = dev_rx->ifindex;
 599         }
 600
 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))
 606                                 continue;
 607
 608                         if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
 609                                 continue;
 610
 611                         /* we only need n-1 clones; last_dst enqueued below */
 612                         if (!last_dst) {
 613                                 last_dst = dst;
 614                                 continue;
 615                         }
 616
 617                         err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 618                         if (err)
 619                                 return err;
 620
 621                         last_dst = dst;
 622                 }
 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))
 629                                         continue;
 630
 631                                 if (is_ifindex_excluded(excluded_devices, num_excluded,
 632                                                         dst->dev->ifindex))
 633                                         continue;
 634
 635                                 /* we only need n-1 clones; last_dst enqueued below */
 636                                 if (!last_dst) {
 637                                         last_dst = dst;
 638                                         continue;
 639                                 }
 640
 641                                 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 642                                 if (err)
 643                                         return err;
 644
 645                                 last_dst = dst;
 646                         }
 647                 }
 648         }
 649
 650         /* consume the last copy of the frame */
 651         if (last_dst)
 652                 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
 653         else
 654                 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
 655
 656         return 0;
 657 }
 658
 659 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 660                              struct bpf_prog *xdp_prog)
 661 {
 662         int err;
 663
 664         err = xdp_ok_fwd_dev(dst->dev, skb->len);
 665         if (unlikely(err))
 666                 return err;
 667
 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
 670          * freeing skb.
 671          */
 672         if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
 673                 return 0;
 674
 675         skb->dev = dst->dev;
 676         generic_xdp_tx(skb, xdp_prog);
 677
 678         return 0;
 679 }
 680
 681 static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
 682                                   struct sk_buff *skb,
 683                                   struct bpf_prog *xdp_prog)
 684 {
 685         struct sk_buff *nskb;
 686         int err;
 687
 688         nskb = skb_clone(skb, GFP_ATOMIC);
 689         if (!nskb)
 690                 return -ENOMEM;
 691
 692         err = dev_map_generic_redirect(dst, nskb, xdp_prog);
 693         if (unlikely(err)) {
 694                 consume_skb(nskb);
 695                 return err;
 696         }
 697
 698         return 0;
 699 }
 700
 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)
 704 {
 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;
 711         unsigned int i;
 712         int err;
 713
 714         if (exclude_ingress) {
 715                 num_excluded = get_upper_ifindexes(dev, excluded_devices);
 716                 excluded_devices[num_excluded++] = dev->ifindex;
 717         }
 718
 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());
 723                         if (!dst)
 724                                 continue;
 725
 726                         if (is_ifindex_excluded(excluded_devices, num_excluded, dst->dev->ifindex))
 727                                 continue;
 728
 729                         /* we only need n-1 clones; last_dst enqueued below */
 730                         if (!last_dst) {
 731                                 last_dst = dst;
 732                                 continue;
 733                         }
 734
 735                         err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 736                         if (err)
 737                                 return err;
 738
 739                         last_dst = dst;
 740
 741                 }
 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) {
 746                                 if (!dst)
 747                                         continue;
 748
 749                                 if (is_ifindex_excluded(excluded_devices, num_excluded,
 750                                                         dst->dev->ifindex))
 751                                         continue;
 752
 753                                 /* we only need n-1 clones; last_dst enqueued below */
 754                                 if (!last_dst) {
 755                                         last_dst = dst;
 756                                         continue;
 757                                 }
 758
 759                                 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 760                                 if (err)
 761                                         return err;
 762
 763                                 last_dst = dst;
 764                         }
 765                 }
 766         }
 767
 768         /* consume the first skb and return */
 769         if (last_dst)
 770                 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
 771
 772         /* dtab is empty */
 773         consume_skb(skb);
 774         return 0;
 775 }
 776
 777 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 778 {
 779         struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
 780
 781         return obj ? &obj->val : NULL;
 782 }
 783
 784 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
 785 {
 786         struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
 787                                                                 *(u32 *)key);
 788         return obj ? &obj->val : NULL;
 789 }
 790
 791 static void __dev_map_entry_free(struct rcu_head *rcu)
 792 {
 793         struct bpf_dtab_netdev *dev;
 794
 795         dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
 796         if (dev->xdp_prog)
 797                 bpf_prog_put(dev->xdp_prog);
 798         dev_put(dev->dev);
 799         kfree(dev);
 800 }
 801
 802 static int dev_map_delete_elem(struct bpf_map *map, void *key)
 803 {
 804         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 805         struct bpf_dtab_netdev *old_dev;
 806         int k = *(u32 *)key;
 807
 808         if (k >= map->max_entries)
 809                 return -EINVAL;
 810
 811         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
 812         if (old_dev)
 813                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 814         return 0;
 815 }
 816
 817 static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
 818 {
 819         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 820         struct bpf_dtab_netdev *old_dev;
 821         int k = *(u32 *)key;
 822         unsigned long flags;
 823         int ret = -ENOENT;
 824
 825         spin_lock_irqsave(&dtab->index_lock, flags);
 826
 827         old_dev = __dev_map_hash_lookup_elem(map, k);
 828         if (old_dev) {
 829                 dtab->items--;
 830                 hlist_del_init_rcu(&old_dev->index_hlist);
 831                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 832                 ret = 0;
 833         }
 834         spin_unlock_irqrestore(&dtab->index_lock, flags);
 835
 836         return ret;
 837 }
 838
 839 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 840                                                     struct bpf_dtab *dtab,
 841                                                     struct bpf_devmap_val *val,
 842                                                     unsigned int idx)
 843 {
 844         struct bpf_prog *prog = NULL;
 845         struct bpf_dtab_netdev *dev;
 846
 847         dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
 848                                    GFP_NOWAIT | __GFP_NOWARN,
 849                                    dtab->map.numa_node);
 850         if (!dev)
 851                 return ERR_PTR(-ENOMEM);
 852
 853         dev->dev = dev_get_by_index(net, val->ifindex);
 854         if (!dev->dev)
 855                 goto err_out;
 856
 857         if (val->bpf_prog.fd > 0) {
 858                 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
 859                                              BPF_PROG_TYPE_XDP, false);
 860                 if (IS_ERR(prog))
 861                         goto err_put_dev;
 862                 if (prog->expected_attach_type != BPF_XDP_DEVMAP ||
 863                     !bpf_prog_map_compatible(&dtab->map, prog))
 864                         goto err_put_prog;
 865         }
 866
 867         dev->idx = idx;
 868         dev->dtab = dtab;
 869         if (prog) {
 870                 dev->xdp_prog = prog;
 871                 dev->val.bpf_prog.id = prog->aux->id;
 872         } else {
 873                 dev->xdp_prog = NULL;
 874                 dev->val.bpf_prog.id = 0;
 875         }
 876         dev->val.ifindex = val->ifindex;
 877
 878         return dev;
 879 err_put_prog:
 880         bpf_prog_put(prog);
 881 err_put_dev:
 882         dev_put(dev->dev);
 883 err_out:
 884         kfree(dev);
 885         return ERR_PTR(-EINVAL);
 886 }
 887
 888 static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
 889                                  void *key, void *value, u64 map_flags)
 890 {
 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 = {};
 894         u32 i = *(u32 *)key;
 895
 896         if (unlikely(map_flags > BPF_EXIST))
 897                 return -EINVAL;
 898         if (unlikely(i >= dtab->map.max_entries))
 899                 return -E2BIG;
 900         if (unlikely(map_flags == BPF_NOEXIST))
 901                 return -EEXIST;
 902
 903         /* already verified value_size <= sizeof val */
 904         memcpy(&val, value, map->value_size);
 905
 906         if (!val.ifindex) {
 907                 dev = NULL;
 908                 /* can not specify fd if ifindex is 0 */
 909                 if (val.bpf_prog.fd > 0)
 910                         return -EINVAL;
 911         } else {
 912                 dev = __dev_map_alloc_node(net, dtab, &val, i);
 913                 if (IS_ERR(dev))
 914                         return PTR_ERR(dev);
 915         }
 916
 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.
 920          */
 921         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
 922         if (old_dev)
 923                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 924
 925         return 0;
 926 }
 927
 928 static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
 929                                u64 map_flags)
 930 {
 931         return __dev_map_update_elem(current->nsproxy->net_ns,
 932                                      map, key, value, map_flags);
 933 }
 934
 935 static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 936                                      void *key, void *value, u64 map_flags)
 937 {
 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;
 942         unsigned long flags;
 943         int err = -EEXIST;
 944
 945         /* already verified value_size <= sizeof val */
 946         memcpy(&val, value, map->value_size);
 947
 948         if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
 949                 return -EINVAL;
 950
 951         spin_lock_irqsave(&dtab->index_lock, flags);
 952
 953         old_dev = __dev_map_hash_lookup_elem(map, idx);
 954         if (old_dev && (map_flags & BPF_NOEXIST))
 955                 goto out_err;
 956
 957         dev = __dev_map_alloc_node(net, dtab, &val, idx);
 958         if (IS_ERR(dev)) {
 959                 err = PTR_ERR(dev);
 960                 goto out_err;
 961         }
 962
 963         if (old_dev) {
 964                 hlist_del_rcu(&old_dev->index_hlist);
 965         } else {
 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);
 969                         return -E2BIG;
 970                 }
 971                 dtab->items++;
 972         }
 973
 974         hlist_add_head_rcu(&dev->index_hlist,
 975                            dev_map_index_hash(dtab, idx));
 976         spin_unlock_irqrestore(&dtab->index_lock, flags);
 977
 978         if (old_dev)
 979                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 980
 981         return 0;
 982
 983 out_err:
 984         spin_unlock_irqrestore(&dtab->index_lock, flags);
 985         return err;
 986 }
 987
 988 static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
 989                                    u64 map_flags)
 990 {
 991         return __dev_map_hash_update_elem(current->nsproxy->net_ns,
 992                                          map, key, value, map_flags);
 993 }
 994
 995 static int dev_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
 996 {
 997         return __bpf_xdp_redirect_map(map, ifindex, flags,
 998                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
 999                                       __dev_map_lookup_elem);
1000 }
1001
1002 static int dev_hash_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
1003 {
1004         return __bpf_xdp_redirect_map(map, ifindex, flags,
1005                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
1006                                       __dev_map_hash_lookup_elem);
1007 }
1008
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,
1021 };
1022
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,
1034 };
1035
1036 static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
1037                                        struct net_device *netdev)
1038 {
1039         unsigned long flags;
1040         u32 i;
1041
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;
1047
1048                 head = dev_map_index_hash(dtab, i);
1049
1050                 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
1051                         if (netdev != dev->dev)
1052                                 continue;
1053
1054                         dtab->items--;
1055                         hlist_del_rcu(&dev->index_hlist);
1056                         call_rcu(&dev->rcu, __dev_map_entry_free);
1057                 }
1058         }
1059         spin_unlock_irqrestore(&dtab->index_lock, flags);
1060 }
1061
1062 static int dev_map_notification(struct notifier_block *notifier,
1063                                 ulong event, void *ptr)
1064 {
1065         struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
1066         struct bpf_dtab *dtab;
1067         int i, cpu;
1068
1069         switch (event) {
1070         case NETDEV_REGISTER:
1071                 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1072                         break;
1073
1074                 /* will be freed in free_netdev() */
1075                 netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1076                 if (!netdev->xdp_bulkq)
1077                         return NOTIFY_BAD;
1078
1079                 for_each_possible_cpu(cpu)
1080                         per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1081                 break;
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.
1087                  */
1088                 rcu_read_lock();
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);
1092                                 continue;
1093                         }
1094
1095                         for (i = 0; i < dtab->map.max_entries; i++) {
1096                                 struct bpf_dtab_netdev *dev, *odev;
1097
1098                                 dev = rcu_dereference(dtab->netdev_map[i]);
1099                                 if (!dev || netdev != dev->dev)
1100                                         continue;
1101                                 odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1102                                 if (dev == odev)
1103                                         call_rcu(&dev->rcu,
1104                                                  __dev_map_entry_free);
1105                         }
1106                 }
1107                 rcu_read_unlock();
1108                 break;
1109         default:
1110                 break;
1111         }
1112         return NOTIFY_OK;
1113 }
1114
1115 static struct notifier_block dev_map_notifier = {
1116         .notifier_call = dev_map_notification,
1117 };
1118
1119 static int __init dev_map_init(void)
1120 {
1121         int cpu;
1122
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);
1127
1128         for_each_possible_cpu(cpu)
1129                 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1130         return 0;
1131 }
1132
1133 subsys_initcall(dev_map_init);