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 static int dev_map_bpf_prog_run(struct bpf_prog *xdp_prog,
 326                                 struct xdp_frame **frames, int n,
 327                                 struct net_device *dev)
 328 {
 329         struct xdp_txq_info txq = { .dev = dev };
 330         struct xdp_buff xdp;
 331         int i, nframes = 0;
 332
 333         for (i = 0; i < n; i++) {
 334                 struct xdp_frame *xdpf = frames[i];
 335                 u32 act;
 336                 int err;
 337
 338                 xdp_convert_frame_to_buff(xdpf, &xdp);
 339                 xdp.txq = &txq;
 340
 341                 act = bpf_prog_run_xdp(xdp_prog, &xdp);
 342                 switch (act) {
 343                 case XDP_PASS:
 344                         err = xdp_update_frame_from_buff(&xdp, xdpf);
 345                         if (unlikely(err < 0))
 346                                 xdp_return_frame_rx_napi(xdpf);
 347                         else
 348                                 frames[nframes++] = xdpf;
 349                         break;
 350                 default:
 351                         bpf_warn_invalid_xdp_action(act);
 352                         fallthrough;
 353                 case XDP_ABORTED:
 354                         trace_xdp_exception(dev, xdp_prog, act);
 355                         fallthrough;
 356                 case XDP_DROP:
 357                         xdp_return_frame_rx_napi(xdpf);
 358                         break;
 359                 }
 360         }
 361         return nframes; /* sent frames count */
 362 }
 363
 364 static void bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
 365 {
 366         struct net_device *dev = bq->dev;
 367         unsigned int cnt = bq->count;
 368         int sent = 0, err = 0;
 369         int to_send = cnt;
 370         int i;
 371
 372         if (unlikely(!cnt))
 373                 return;
 374
 375         for (i = 0; i < cnt; i++) {
 376                 struct xdp_frame *xdpf = bq->q[i];
 377
 378                 prefetch(xdpf);
 379         }
 380
 381         if (bq->xdp_prog) {
 382                 to_send = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
 383                 if (!to_send)
 384                         goto out;
 385         }
 386
 387         sent = dev->netdev_ops->ndo_xdp_xmit(dev, to_send, bq->q, flags);
 388         if (sent < 0) {
 389                 /* If ndo_xdp_xmit fails with an errno, no frames have
 390                  * been xmit'ed.
 391                  */
 392                 err = sent;
 393                 sent = 0;
 394         }
 395
 396         /* If not all frames have been transmitted, it is our
 397          * responsibility to free them
 398          */
 399         for (i = sent; unlikely(i < to_send); i++)
 400                 xdp_return_frame_rx_napi(bq->q[i]);
 401
 402 out:
 403         bq->count = 0;
 404         trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, cnt - sent, err);
 405 }
 406
 407 /* __dev_flush is called from xdp_do_flush() which _must_ be signalled from the
 408  * driver before returning from its napi->poll() routine. See the comment above
 409  * xdp_do_flush() in filter.c.
 410  */
 411 void __dev_flush(void)
 412 {
 413         struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
 414         struct xdp_dev_bulk_queue *bq, *tmp;
 415
 416         list_for_each_entry_safe(bq, tmp, flush_list, flush_node) {
 417                 bq_xmit_all(bq, XDP_XMIT_FLUSH);
 418                 bq->dev_rx = NULL;
 419                 bq->xdp_prog = NULL;
 420                 __list_del_clearprev(&bq->flush_node);
 421         }
 422 }
 423
 424 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
 425  * by local_bh_disable() (from XDP calls inside NAPI). The
 426  * rcu_read_lock_bh_held() below makes lockdep accept both.
 427  */
 428 static void *__dev_map_lookup_elem(struct bpf_map *map, u32 key)
 429 {
 430         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 431         struct bpf_dtab_netdev *obj;
 432
 433         if (key >= map->max_entries)
 434                 return NULL;
 435
 436         obj = rcu_dereference_check(dtab->netdev_map[key],
 437                                     rcu_read_lock_bh_held());
 438         return obj;
 439 }
 440
 441 /* Runs in NAPI, i.e., softirq under local_bh_disable(). Thus, safe percpu
 442  * variable access, and map elements stick around. See comment above
 443  * xdp_do_flush() in filter.c.
 444  */
 445 static void bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
 446                        struct net_device *dev_rx, struct bpf_prog *xdp_prog)
 447 {
 448         struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
 449         struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
 450
 451         if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
 452                 bq_xmit_all(bq, 0);
 453
 454         /* Ingress dev_rx will be the same for all xdp_frame's in
 455          * bulk_queue, because bq stored per-CPU and must be flushed
 456          * from net_device drivers NAPI func end.
 457          *
 458          * Do the same with xdp_prog and flush_list since these fields
 459          * are only ever modified together.
 460          */
 461         if (!bq->dev_rx) {
 462                 bq->dev_rx = dev_rx;
 463                 bq->xdp_prog = xdp_prog;
 464                 list_add(&bq->flush_node, flush_list);
 465         }
 466
 467         bq->q[bq->count++] = xdpf;
 468 }
 469
 470 static inline int __xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
 471                                 struct net_device *dev_rx,
 472                                 struct bpf_prog *xdp_prog)
 473 {
 474         struct xdp_frame *xdpf;
 475         int err;
 476
 477         if (!dev->netdev_ops->ndo_xdp_xmit)
 478                 return -EOPNOTSUPP;
 479
 480         err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
 481         if (unlikely(err))
 482                 return err;
 483
 484         xdpf = xdp_convert_buff_to_frame(xdp);
 485         if (unlikely(!xdpf))
 486                 return -EOVERFLOW;
 487
 488         bq_enqueue(dev, xdpf, dev_rx, xdp_prog);
 489         return 0;
 490 }
 491
 492 static u32 dev_map_bpf_prog_run_skb(struct sk_buff *skb, struct bpf_dtab_netdev *dst)
 493 {
 494         struct xdp_txq_info txq = { .dev = dst->dev };
 495         struct xdp_buff xdp;
 496         u32 act;
 497
 498         if (!dst->xdp_prog)
 499                 return XDP_PASS;
 500
 501         __skb_pull(skb, skb->mac_len);
 502         xdp.txq = &txq;
 503
 504         act = bpf_prog_run_generic_xdp(skb, &xdp, dst->xdp_prog);
 505         switch (act) {
 506         case XDP_PASS:
 507                 __skb_push(skb, skb->mac_len);
 508                 break;
 509         default:
 510                 bpf_warn_invalid_xdp_action(act);
 511                 fallthrough;
 512         case XDP_ABORTED:
 513                 trace_xdp_exception(dst->dev, dst->xdp_prog, act);
 514                 fallthrough;
 515         case XDP_DROP:
 516                 kfree_skb(skb);
 517                 break;
 518         }
 519
 520         return act;
 521 }
 522
 523 int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
 524                     struct net_device *dev_rx)
 525 {
 526         return __xdp_enqueue(dev, xdp, dev_rx, NULL);
 527 }
 528
 529 int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
 530                     struct net_device *dev_rx)
 531 {
 532         struct net_device *dev = dst->dev;
 533
 534         return __xdp_enqueue(dev, xdp, dev_rx, dst->xdp_prog);
 535 }
 536
 537 static bool is_valid_dst(struct bpf_dtab_netdev *obj, struct xdp_buff *xdp,
 538                          int exclude_ifindex)
 539 {
 540         if (!obj || obj->dev->ifindex == exclude_ifindex ||
 541             !obj->dev->netdev_ops->ndo_xdp_xmit)
 542                 return false;
 543
 544         if (xdp_ok_fwd_dev(obj->dev, xdp->data_end - xdp->data))
 545                 return false;
 546
 547         return true;
 548 }
 549
 550 static int dev_map_enqueue_clone(struct bpf_dtab_netdev *obj,
 551                                  struct net_device *dev_rx,
 552                                  struct xdp_frame *xdpf)
 553 {
 554         struct xdp_frame *nxdpf;
 555
 556         nxdpf = xdpf_clone(xdpf);
 557         if (!nxdpf)
 558                 return -ENOMEM;
 559
 560         bq_enqueue(obj->dev, nxdpf, dev_rx, obj->xdp_prog);
 561
 562         return 0;
 563 }
 564
 565 int dev_map_enqueue_multi(struct xdp_buff *xdp, struct net_device *dev_rx,
 566                           struct bpf_map *map, bool exclude_ingress)
 567 {
 568         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 569         int exclude_ifindex = exclude_ingress ? dev_rx->ifindex : 0;
 570         struct bpf_dtab_netdev *dst, *last_dst = NULL;
 571         struct hlist_head *head;
 572         struct xdp_frame *xdpf;
 573         unsigned int i;
 574         int err;
 575
 576         xdpf = xdp_convert_buff_to_frame(xdp);
 577         if (unlikely(!xdpf))
 578                 return -EOVERFLOW;
 579
 580         if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 581                 for (i = 0; i < map->max_entries; i++) {
 582                         dst = rcu_dereference_check(dtab->netdev_map[i],
 583                                                     rcu_read_lock_bh_held());
 584                         if (!is_valid_dst(dst, xdp, exclude_ifindex))
 585                                 continue;
 586
 587                         /* we only need n-1 clones; last_dst enqueued below */
 588                         if (!last_dst) {
 589                                 last_dst = dst;
 590                                 continue;
 591                         }
 592
 593                         err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 594                         if (err)
 595                                 return err;
 596
 597                         last_dst = dst;
 598                 }
 599         } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
 600                 for (i = 0; i < dtab->n_buckets; i++) {
 601                         head = dev_map_index_hash(dtab, i);
 602                         hlist_for_each_entry_rcu(dst, head, index_hlist,
 603                                                  lockdep_is_held(&dtab->index_lock)) {
 604                                 if (!is_valid_dst(dst, xdp, exclude_ifindex))
 605                                         continue;
 606
 607                                 /* we only need n-1 clones; last_dst enqueued below */
 608                                 if (!last_dst) {
 609                                         last_dst = dst;
 610                                         continue;
 611                                 }
 612
 613                                 err = dev_map_enqueue_clone(last_dst, dev_rx, xdpf);
 614                                 if (err)
 615                                         return err;
 616
 617                                 last_dst = dst;
 618                         }
 619                 }
 620         }
 621
 622         /* consume the last copy of the frame */
 623         if (last_dst)
 624                 bq_enqueue(last_dst->dev, xdpf, dev_rx, last_dst->xdp_prog);
 625         else
 626                 xdp_return_frame_rx_napi(xdpf); /* dtab is empty */
 627
 628         return 0;
 629 }
 630
 631 int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
 632                              struct bpf_prog *xdp_prog)
 633 {
 634         int err;
 635
 636         err = xdp_ok_fwd_dev(dst->dev, skb->len);
 637         if (unlikely(err))
 638                 return err;
 639
 640         /* Redirect has already succeeded semantically at this point, so we just
 641          * return 0 even if packet is dropped. Helper below takes care of
 642          * freeing skb.
 643          */
 644         if (dev_map_bpf_prog_run_skb(skb, dst) != XDP_PASS)
 645                 return 0;
 646
 647         skb->dev = dst->dev;
 648         generic_xdp_tx(skb, xdp_prog);
 649
 650         return 0;
 651 }
 652
 653 static int dev_map_redirect_clone(struct bpf_dtab_netdev *dst,
 654                                   struct sk_buff *skb,
 655                                   struct bpf_prog *xdp_prog)
 656 {
 657         struct sk_buff *nskb;
 658         int err;
 659
 660         nskb = skb_clone(skb, GFP_ATOMIC);
 661         if (!nskb)
 662                 return -ENOMEM;
 663
 664         err = dev_map_generic_redirect(dst, nskb, xdp_prog);
 665         if (unlikely(err)) {
 666                 consume_skb(nskb);
 667                 return err;
 668         }
 669
 670         return 0;
 671 }
 672
 673 int dev_map_redirect_multi(struct net_device *dev, struct sk_buff *skb,
 674                            struct bpf_prog *xdp_prog, struct bpf_map *map,
 675                            bool exclude_ingress)
 676 {
 677         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 678         int exclude_ifindex = exclude_ingress ? dev->ifindex : 0;
 679         struct bpf_dtab_netdev *dst, *last_dst = NULL;
 680         struct hlist_head *head;
 681         struct hlist_node *next;
 682         unsigned int i;
 683         int err;
 684
 685         if (map->map_type == BPF_MAP_TYPE_DEVMAP) {
 686                 for (i = 0; i < map->max_entries; i++) {
 687                         dst = rcu_dereference_check(dtab->netdev_map[i],
 688                                                     rcu_read_lock_bh_held());
 689                         if (!dst || dst->dev->ifindex == exclude_ifindex)
 690                                 continue;
 691
 692                         /* we only need n-1 clones; last_dst enqueued below */
 693                         if (!last_dst) {
 694                                 last_dst = dst;
 695                                 continue;
 696                         }
 697
 698                         err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 699                         if (err)
 700                                 return err;
 701
 702                         last_dst = dst;
 703                 }
 704         } else { /* BPF_MAP_TYPE_DEVMAP_HASH */
 705                 for (i = 0; i < dtab->n_buckets; i++) {
 706                         head = dev_map_index_hash(dtab, i);
 707                         hlist_for_each_entry_safe(dst, next, head, index_hlist) {
 708                                 if (!dst || dst->dev->ifindex == exclude_ifindex)
 709                                         continue;
 710
 711                                 /* we only need n-1 clones; last_dst enqueued below */
 712                                 if (!last_dst) {
 713                                         last_dst = dst;
 714                                         continue;
 715                                 }
 716
 717                                 err = dev_map_redirect_clone(last_dst, skb, xdp_prog);
 718                                 if (err)
 719                                         return err;
 720
 721                                 last_dst = dst;
 722                         }
 723                 }
 724         }
 725
 726         /* consume the first skb and return */
 727         if (last_dst)
 728                 return dev_map_generic_redirect(last_dst, skb, xdp_prog);
 729
 730         /* dtab is empty */
 731         consume_skb(skb);
 732         return 0;
 733 }
 734
 735 static void *dev_map_lookup_elem(struct bpf_map *map, void *key)
 736 {
 737         struct bpf_dtab_netdev *obj = __dev_map_lookup_elem(map, *(u32 *)key);
 738
 739         return obj ? &obj->val : NULL;
 740 }
 741
 742 static void *dev_map_hash_lookup_elem(struct bpf_map *map, void *key)
 743 {
 744         struct bpf_dtab_netdev *obj = __dev_map_hash_lookup_elem(map,
 745                                                                 *(u32 *)key);
 746         return obj ? &obj->val : NULL;
 747 }
 748
 749 static void __dev_map_entry_free(struct rcu_head *rcu)
 750 {
 751         struct bpf_dtab_netdev *dev;
 752
 753         dev = container_of(rcu, struct bpf_dtab_netdev, rcu);
 754         if (dev->xdp_prog)
 755                 bpf_prog_put(dev->xdp_prog);
 756         dev_put(dev->dev);
 757         kfree(dev);
 758 }
 759
 760 static int dev_map_delete_elem(struct bpf_map *map, void *key)
 761 {
 762         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 763         struct bpf_dtab_netdev *old_dev;
 764         int k = *(u32 *)key;
 765
 766         if (k >= map->max_entries)
 767                 return -EINVAL;
 768
 769         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[k], NULL));
 770         if (old_dev)
 771                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 772         return 0;
 773 }
 774
 775 static int dev_map_hash_delete_elem(struct bpf_map *map, void *key)
 776 {
 777         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 778         struct bpf_dtab_netdev *old_dev;
 779         int k = *(u32 *)key;
 780         unsigned long flags;
 781         int ret = -ENOENT;
 782
 783         spin_lock_irqsave(&dtab->index_lock, flags);
 784
 785         old_dev = __dev_map_hash_lookup_elem(map, k);
 786         if (old_dev) {
 787                 dtab->items--;
 788                 hlist_del_init_rcu(&old_dev->index_hlist);
 789                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 790                 ret = 0;
 791         }
 792         spin_unlock_irqrestore(&dtab->index_lock, flags);
 793
 794         return ret;
 795 }
 796
 797 static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 798                                                     struct bpf_dtab *dtab,
 799                                                     struct bpf_devmap_val *val,
 800                                                     unsigned int idx)
 801 {
 802         struct bpf_prog *prog = NULL;
 803         struct bpf_dtab_netdev *dev;
 804
 805         dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
 806                                    GFP_ATOMIC | __GFP_NOWARN,
 807                                    dtab->map.numa_node);
 808         if (!dev)
 809                 return ERR_PTR(-ENOMEM);
 810
 811         dev->dev = dev_get_by_index(net, val->ifindex);
 812         if (!dev->dev)
 813                 goto err_out;
 814
 815         if (val->bpf_prog.fd > 0) {
 816                 prog = bpf_prog_get_type_dev(val->bpf_prog.fd,
 817                                              BPF_PROG_TYPE_XDP, false);
 818                 if (IS_ERR(prog))
 819                         goto err_put_dev;
 820                 if (prog->expected_attach_type != BPF_XDP_DEVMAP)
 821                         goto err_put_prog;
 822         }
 823
 824         dev->idx = idx;
 825         dev->dtab = dtab;
 826         if (prog) {
 827                 dev->xdp_prog = prog;
 828                 dev->val.bpf_prog.id = prog->aux->id;
 829         } else {
 830                 dev->xdp_prog = NULL;
 831                 dev->val.bpf_prog.id = 0;
 832         }
 833         dev->val.ifindex = val->ifindex;
 834
 835         return dev;
 836 err_put_prog:
 837         bpf_prog_put(prog);
 838 err_put_dev:
 839         dev_put(dev->dev);
 840 err_out:
 841         kfree(dev);
 842         return ERR_PTR(-EINVAL);
 843 }
 844
 845 static int __dev_map_update_elem(struct net *net, struct bpf_map *map,
 846                                  void *key, void *value, u64 map_flags)
 847 {
 848         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 849         struct bpf_dtab_netdev *dev, *old_dev;
 850         struct bpf_devmap_val val = {};
 851         u32 i = *(u32 *)key;
 852
 853         if (unlikely(map_flags > BPF_EXIST))
 854                 return -EINVAL;
 855         if (unlikely(i >= dtab->map.max_entries))
 856                 return -E2BIG;
 857         if (unlikely(map_flags == BPF_NOEXIST))
 858                 return -EEXIST;
 859
 860         /* already verified value_size <= sizeof val */
 861         memcpy(&val, value, map->value_size);
 862
 863         if (!val.ifindex) {
 864                 dev = NULL;
 865                 /* can not specify fd if ifindex is 0 */
 866                 if (val.bpf_prog.fd > 0)
 867                         return -EINVAL;
 868         } else {
 869                 dev = __dev_map_alloc_node(net, dtab, &val, i);
 870                 if (IS_ERR(dev))
 871                         return PTR_ERR(dev);
 872         }
 873
 874         /* Use call_rcu() here to ensure rcu critical sections have completed
 875          * Remembering the driver side flush operation will happen before the
 876          * net device is removed.
 877          */
 878         old_dev = unrcu_pointer(xchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev)));
 879         if (old_dev)
 880                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 881
 882         return 0;
 883 }
 884
 885 static int dev_map_update_elem(struct bpf_map *map, void *key, void *value,
 886                                u64 map_flags)
 887 {
 888         return __dev_map_update_elem(current->nsproxy->net_ns,
 889                                      map, key, value, map_flags);
 890 }
 891
 892 static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map,
 893                                      void *key, void *value, u64 map_flags)
 894 {
 895         struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map);
 896         struct bpf_dtab_netdev *dev, *old_dev;
 897         struct bpf_devmap_val val = {};
 898         u32 idx = *(u32 *)key;
 899         unsigned long flags;
 900         int err = -EEXIST;
 901
 902         /* already verified value_size <= sizeof val */
 903         memcpy(&val, value, map->value_size);
 904
 905         if (unlikely(map_flags > BPF_EXIST || !val.ifindex))
 906                 return -EINVAL;
 907
 908         spin_lock_irqsave(&dtab->index_lock, flags);
 909
 910         old_dev = __dev_map_hash_lookup_elem(map, idx);
 911         if (old_dev && (map_flags & BPF_NOEXIST))
 912                 goto out_err;
 913
 914         dev = __dev_map_alloc_node(net, dtab, &val, idx);
 915         if (IS_ERR(dev)) {
 916                 err = PTR_ERR(dev);
 917                 goto out_err;
 918         }
 919
 920         if (old_dev) {
 921                 hlist_del_rcu(&old_dev->index_hlist);
 922         } else {
 923                 if (dtab->items >= dtab->map.max_entries) {
 924                         spin_unlock_irqrestore(&dtab->index_lock, flags);
 925                         call_rcu(&dev->rcu, __dev_map_entry_free);
 926                         return -E2BIG;
 927                 }
 928                 dtab->items++;
 929         }
 930
 931         hlist_add_head_rcu(&dev->index_hlist,
 932                            dev_map_index_hash(dtab, idx));
 933         spin_unlock_irqrestore(&dtab->index_lock, flags);
 934
 935         if (old_dev)
 936                 call_rcu(&old_dev->rcu, __dev_map_entry_free);
 937
 938         return 0;
 939
 940 out_err:
 941         spin_unlock_irqrestore(&dtab->index_lock, flags);
 942         return err;
 943 }
 944
 945 static int dev_map_hash_update_elem(struct bpf_map *map, void *key, void *value,
 946                                    u64 map_flags)
 947 {
 948         return __dev_map_hash_update_elem(current->nsproxy->net_ns,
 949                                          map, key, value, map_flags);
 950 }
 951
 952 static int dev_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
 953 {
 954         return __bpf_xdp_redirect_map(map, ifindex, flags,
 955                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
 956                                       __dev_map_lookup_elem);
 957 }
 958
 959 static int dev_hash_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags)
 960 {
 961         return __bpf_xdp_redirect_map(map, ifindex, flags,
 962                                       BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS,
 963                                       __dev_map_hash_lookup_elem);
 964 }
 965
 966 static int dev_map_btf_id;
 967 const struct bpf_map_ops dev_map_ops = {
 968         .map_meta_equal = bpf_map_meta_equal,
 969         .map_alloc = dev_map_alloc,
 970         .map_free = dev_map_free,
 971         .map_get_next_key = dev_map_get_next_key,
 972         .map_lookup_elem = dev_map_lookup_elem,
 973         .map_update_elem = dev_map_update_elem,
 974         .map_delete_elem = dev_map_delete_elem,
 975         .map_check_btf = map_check_no_btf,
 976         .map_btf_name = "bpf_dtab",
 977         .map_btf_id = &dev_map_btf_id,
 978         .map_redirect = dev_map_redirect,
 979 };
 980
 981 static int dev_map_hash_map_btf_id;
 982 const struct bpf_map_ops dev_map_hash_ops = {
 983         .map_meta_equal = bpf_map_meta_equal,
 984         .map_alloc = dev_map_alloc,
 985         .map_free = dev_map_free,
 986         .map_get_next_key = dev_map_hash_get_next_key,
 987         .map_lookup_elem = dev_map_hash_lookup_elem,
 988         .map_update_elem = dev_map_hash_update_elem,
 989         .map_delete_elem = dev_map_hash_delete_elem,
 990         .map_check_btf = map_check_no_btf,
 991         .map_btf_name = "bpf_dtab",
 992         .map_btf_id = &dev_map_hash_map_btf_id,
 993         .map_redirect = dev_hash_map_redirect,
 994 };
 995
 996 static void dev_map_hash_remove_netdev(struct bpf_dtab *dtab,
 997                                        struct net_device *netdev)
 998 {
 999         unsigned long flags;
1000         u32 i;
1001
1002         spin_lock_irqsave(&dtab->index_lock, flags);
1003         for (i = 0; i < dtab->n_buckets; i++) {
1004                 struct bpf_dtab_netdev *dev;
1005                 struct hlist_head *head;
1006                 struct hlist_node *next;
1007
1008                 head = dev_map_index_hash(dtab, i);
1009
1010                 hlist_for_each_entry_safe(dev, next, head, index_hlist) {
1011                         if (netdev != dev->dev)
1012                                 continue;
1013
1014                         dtab->items--;
1015                         hlist_del_rcu(&dev->index_hlist);
1016                         call_rcu(&dev->rcu, __dev_map_entry_free);
1017                 }
1018         }
1019         spin_unlock_irqrestore(&dtab->index_lock, flags);
1020 }
1021
1022 static int dev_map_notification(struct notifier_block *notifier,
1023                                 ulong event, void *ptr)
1024 {
1025         struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
1026         struct bpf_dtab *dtab;
1027         int i, cpu;
1028
1029         switch (event) {
1030         case NETDEV_REGISTER:
1031                 if (!netdev->netdev_ops->ndo_xdp_xmit || netdev->xdp_bulkq)
1032                         break;
1033
1034                 /* will be freed in free_netdev() */
1035                 netdev->xdp_bulkq = alloc_percpu(struct xdp_dev_bulk_queue);
1036                 if (!netdev->xdp_bulkq)
1037                         return NOTIFY_BAD;
1038
1039                 for_each_possible_cpu(cpu)
1040                         per_cpu_ptr(netdev->xdp_bulkq, cpu)->dev = netdev;
1041                 break;
1042         case NETDEV_UNREGISTER:
1043                 /* This rcu_read_lock/unlock pair is needed because
1044                  * dev_map_list is an RCU list AND to ensure a delete
1045                  * operation does not free a netdev_map entry while we
1046                  * are comparing it against the netdev being unregistered.
1047                  */
1048                 rcu_read_lock();
1049                 list_for_each_entry_rcu(dtab, &dev_map_list, list) {
1050                         if (dtab->map.map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
1051                                 dev_map_hash_remove_netdev(dtab, netdev);
1052                                 continue;
1053                         }
1054
1055                         for (i = 0; i < dtab->map.max_entries; i++) {
1056                                 struct bpf_dtab_netdev *dev, *odev;
1057
1058                                 dev = rcu_dereference(dtab->netdev_map[i]);
1059                                 if (!dev || netdev != dev->dev)
1060                                         continue;
1061                                 odev = unrcu_pointer(cmpxchg(&dtab->netdev_map[i], RCU_INITIALIZER(dev), NULL));
1062                                 if (dev == odev)
1063                                         call_rcu(&dev->rcu,
1064                                                  __dev_map_entry_free);
1065                         }
1066                 }
1067                 rcu_read_unlock();
1068                 break;
1069         default:
1070                 break;
1071         }
1072         return NOTIFY_OK;
1073 }
1074
1075 static struct notifier_block dev_map_notifier = {
1076         .notifier_call = dev_map_notification,
1077 };
1078
1079 static int __init dev_map_init(void)
1080 {
1081         int cpu;
1082
1083         /* Assure tracepoint shadow struct _bpf_dtab_netdev is in sync */
1084         BUILD_BUG_ON(offsetof(struct bpf_dtab_netdev, dev) !=
1085                      offsetof(struct _bpf_dtab_netdev, dev));
1086         register_netdevice_notifier(&dev_map_notifier);
1087
1088         for_each_possible_cpu(cpu)
1089                 INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
1090         return 0;
1091 }
1092
1093 subsys_initcall(dev_map_init);