kernel/bpf/local_storage.c

   1 //SPDX-License-Identifier: GPL-2.0
   2 #include <linux/bpf-cgroup.h>
   3 #include <linux/bpf.h>
   4 #include <linux/btf.h>
   5 #include <linux/bug.h>
   6 #include <linux/filter.h>
   7 #include <linux/mm.h>
   8 #include <linux/rbtree.h>
   9 #include <linux/slab.h>
  10 #include <uapi/linux/btf.h>
  11
  12 DEFINE_PER_CPU(struct bpf_cgroup_storage*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
  13
  14 #ifdef CONFIG_CGROUP_BPF
  15
  16 #define LOCAL_STORAGE_CREATE_FLAG_MASK                                  \
  17         (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
  18
  19 struct bpf_cgroup_storage_map {
  20         struct bpf_map map;
  21
  22         spinlock_t lock;
  23         struct bpf_prog *prog;
  24         struct rb_root root;
  25         struct list_head list;
  26 };
  27
  28 static struct bpf_cgroup_storage_map *map_to_storage(struct bpf_map *map)
  29 {
  30         return container_of(map, struct bpf_cgroup_storage_map, map);
  31 }
  32
  33 static int bpf_cgroup_storage_key_cmp(
  34         const struct bpf_cgroup_storage_key *key1,
  35         const struct bpf_cgroup_storage_key *key2)
  36 {
  37         if (key1->cgroup_inode_id < key2->cgroup_inode_id)
  38                 return -1;
  39         else if (key1->cgroup_inode_id > key2->cgroup_inode_id)
  40                 return 1;
  41         else if (key1->attach_type < key2->attach_type)
  42                 return -1;
  43         else if (key1->attach_type > key2->attach_type)
  44                 return 1;
  45         return 0;
  46 }
  47
  48 static struct bpf_cgroup_storage *cgroup_storage_lookup(
  49         struct bpf_cgroup_storage_map *map, struct bpf_cgroup_storage_key *key,
  50         bool locked)
  51 {
  52         struct rb_root *root = &map->root;
  53         struct rb_node *node;
  54
  55         if (!locked)
  56                 spin_lock_bh(&map->lock);
  57
  58         node = root->rb_node;
  59         while (node) {
  60                 struct bpf_cgroup_storage *storage;
  61
  62                 storage = container_of(node, struct bpf_cgroup_storage, node);
  63
  64                 switch (bpf_cgroup_storage_key_cmp(key, &storage->key)) {
  65                 case -1:
  66                         node = node->rb_left;
  67                         break;
  68                 case 1:
  69                         node = node->rb_right;
  70                         break;
  71                 default:
  72                         if (!locked)
  73                                 spin_unlock_bh(&map->lock);
  74                         return storage;
  75                 }
  76         }
  77
  78         if (!locked)
  79                 spin_unlock_bh(&map->lock);
  80
  81         return NULL;
  82 }
  83
  84 static int cgroup_storage_insert(struct bpf_cgroup_storage_map *map,
  85                                  struct bpf_cgroup_storage *storage)
  86 {
  87         struct rb_root *root = &map->root;
  88         struct rb_node **new = &(root->rb_node), *parent = NULL;
  89
  90         while (*new) {
  91                 struct bpf_cgroup_storage *this;
  92
  93                 this = container_of(*new, struct bpf_cgroup_storage, node);
  94
  95                 parent = *new;
  96                 switch (bpf_cgroup_storage_key_cmp(&storage->key, &this->key)) {
  97                 case -1:
  98                         new = &((*new)->rb_left);
  99                         break;
 100                 case 1:
 101                         new = &((*new)->rb_right);
 102                         break;
 103                 default:
 104                         return -EEXIST;
 105                 }
 106         }
 107
 108         rb_link_node(&storage->node, parent, new);
 109         rb_insert_color(&storage->node, root);
 110
 111         return 0;
 112 }
 113
 114 static void *cgroup_storage_lookup_elem(struct bpf_map *_map, void *_key)
 115 {
 116         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 117         struct bpf_cgroup_storage_key *key = _key;
 118         struct bpf_cgroup_storage *storage;
 119
 120         storage = cgroup_storage_lookup(map, key, false);
 121         if (!storage)
 122                 return NULL;
 123
 124         return &READ_ONCE(storage->buf)->data[0];
 125 }
 126
 127 static int cgroup_storage_update_elem(struct bpf_map *map, void *_key,
 128                                       void *value, u64 flags)
 129 {
 130         struct bpf_cgroup_storage_key *key = _key;
 131         struct bpf_cgroup_storage *storage;
 132         struct bpf_storage_buffer *new;
 133
 134         if (unlikely(flags & ~(BPF_F_LOCK | BPF_EXIST | BPF_NOEXIST)))
 135                 return -EINVAL;
 136
 137         if (unlikely(flags & BPF_NOEXIST))
 138                 return -EINVAL;
 139
 140         if (unlikely((flags & BPF_F_LOCK) &&
 141                      !map_value_has_spin_lock(map)))
 142                 return -EINVAL;
 143
 144         storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
 145                                         key, false);
 146         if (!storage)
 147                 return -ENOENT;
 148
 149         if (flags & BPF_F_LOCK) {
 150                 copy_map_value_locked(map, storage->buf->data, value, false);
 151                 return 0;
 152         }
 153
 154         new = kmalloc_node(sizeof(struct bpf_storage_buffer) +
 155                            map->value_size,
 156                            __GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN,
 157                            map->numa_node);
 158         if (!new)
 159                 return -ENOMEM;
 160
 161         memcpy(&new->data[0], value, map->value_size);
 162         check_and_init_map_lock(map, new->data);
 163
 164         new = xchg(&storage->buf, new);
 165         kfree_rcu(new, rcu);
 166
 167         return 0;
 168 }
 169
 170 int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *_key,
 171                                    void *value)
 172 {
 173         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 174         struct bpf_cgroup_storage_key *key = _key;
 175         struct bpf_cgroup_storage *storage;
 176         int cpu, off = 0;
 177         u32 size;
 178
 179         rcu_read_lock();
 180         storage = cgroup_storage_lookup(map, key, false);
 181         if (!storage) {
 182                 rcu_read_unlock();
 183                 return -ENOENT;
 184         }
 185
 186         /* per_cpu areas are zero-filled and bpf programs can only
 187          * access 'value_size' of them, so copying rounded areas
 188          * will not leak any kernel data
 189          */
 190         size = round_up(_map->value_size, 8);
 191         for_each_possible_cpu(cpu) {
 192                 bpf_long_memcpy(value + off,
 193                                 per_cpu_ptr(storage->percpu_buf, cpu), size);
 194                 off += size;
 195         }
 196         rcu_read_unlock();
 197         return 0;
 198 }
 199
 200 int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *_key,
 201                                      void *value, u64 map_flags)
 202 {
 203         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 204         struct bpf_cgroup_storage_key *key = _key;
 205         struct bpf_cgroup_storage *storage;
 206         int cpu, off = 0;
 207         u32 size;
 208
 209         if (map_flags != BPF_ANY && map_flags != BPF_EXIST)
 210                 return -EINVAL;
 211
 212         rcu_read_lock();
 213         storage = cgroup_storage_lookup(map, key, false);
 214         if (!storage) {
 215                 rcu_read_unlock();
 216                 return -ENOENT;
 217         }
 218
 219         /* the user space will provide round_up(value_size, 8) bytes that
 220          * will be copied into per-cpu area. bpf programs can only access
 221          * value_size of it. During lookup the same extra bytes will be
 222          * returned or zeros which were zero-filled by percpu_alloc,
 223          * so no kernel data leaks possible
 224          */
 225         size = round_up(_map->value_size, 8);
 226         for_each_possible_cpu(cpu) {
 227                 bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu),
 228                                 value + off, size);
 229                 off += size;
 230         }
 231         rcu_read_unlock();
 232         return 0;
 233 }
 234
 235 static int cgroup_storage_get_next_key(struct bpf_map *_map, void *_key,
 236                                        void *_next_key)
 237 {
 238         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 239         struct bpf_cgroup_storage_key *key = _key;
 240         struct bpf_cgroup_storage_key *next = _next_key;
 241         struct bpf_cgroup_storage *storage;
 242
 243         spin_lock_bh(&map->lock);
 244
 245         if (list_empty(&map->list))
 246                 goto enoent;
 247
 248         if (key) {
 249                 storage = cgroup_storage_lookup(map, key, true);
 250                 if (!storage)
 251                         goto enoent;
 252
 253                 storage = list_next_entry(storage, list);
 254                 if (!storage)
 255                         goto enoent;
 256         } else {
 257                 storage = list_first_entry(&map->list,
 258                                          struct bpf_cgroup_storage, list);
 259         }
 260
 261         spin_unlock_bh(&map->lock);
 262         next->attach_type = storage->key.attach_type;
 263         next->cgroup_inode_id = storage->key.cgroup_inode_id;
 264         return 0;
 265
 266 enoent:
 267         spin_unlock_bh(&map->lock);
 268         return -ENOENT;
 269 }
 270
 271 static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
 272 {
 273         int numa_node = bpf_map_attr_numa_node(attr);
 274         struct bpf_cgroup_storage_map *map;
 275         struct bpf_map_memory mem;
 276         int ret;
 277
 278         if (attr->key_size != sizeof(struct bpf_cgroup_storage_key))
 279                 return ERR_PTR(-EINVAL);
 280
 281         if (attr->value_size == 0)
 282                 return ERR_PTR(-EINVAL);
 283
 284         if (attr->value_size > PAGE_SIZE)
 285                 return ERR_PTR(-E2BIG);
 286
 287         if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK ||
 288             !bpf_map_flags_access_ok(attr->map_flags))
 289                 return ERR_PTR(-EINVAL);
 290
 291         if (attr->max_entries)
 292                 /* max_entries is not used and enforced to be 0 */
 293                 return ERR_PTR(-EINVAL);
 294
 295         ret = bpf_map_charge_init(&mem, sizeof(struct bpf_cgroup_storage_map));
 296         if (ret < 0)
 297                 return ERR_PTR(ret);
 298
 299         map = kmalloc_node(sizeof(struct bpf_cgroup_storage_map),
 300                            __GFP_ZERO | GFP_USER, numa_node);
 301         if (!map) {
 302                 bpf_map_charge_finish(&mem);
 303                 return ERR_PTR(-ENOMEM);
 304         }
 305
 306         bpf_map_charge_move(&map->map.memory, &mem);
 307
 308         /* copy mandatory map attributes */
 309         bpf_map_init_from_attr(&map->map, attr);
 310
 311         spin_lock_init(&map->lock);
 312         map->root = RB_ROOT;
 313         INIT_LIST_HEAD(&map->list);
 314
 315         return &map->map;
 316 }
 317
 318 static void cgroup_storage_map_free(struct bpf_map *_map)
 319 {
 320         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 321
 322         WARN_ON(!RB_EMPTY_ROOT(&map->root));
 323         WARN_ON(!list_empty(&map->list));
 324
 325         kfree(map);
 326 }
 327
 328 static int cgroup_storage_delete_elem(struct bpf_map *map, void *key)
 329 {
 330         return -EINVAL;
 331 }
 332
 333 static int cgroup_storage_check_btf(const struct bpf_map *map,
 334                                     const struct btf *btf,
 335                                     const struct btf_type *key_type,
 336                                     const struct btf_type *value_type)
 337 {
 338         struct btf_member *m;
 339         u32 offset, size;
 340
 341         /* Key is expected to be of struct bpf_cgroup_storage_key type,
 342          * which is:
 343          * struct bpf_cgroup_storage_key {
 344          *      __u64   cgroup_inode_id;
 345          *      __u32   attach_type;
 346          * };
 347          */
 348
 349         /*
 350          * Key_type must be a structure with two fields.
 351          */
 352         if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
 353             BTF_INFO_VLEN(key_type->info) != 2)
 354                 return -EINVAL;
 355
 356         /*
 357          * The first field must be a 64 bit integer at 0 offset.
 358          */
 359         m = (struct btf_member *)(key_type + 1);
 360         size = sizeof_field(struct bpf_cgroup_storage_key, cgroup_inode_id);
 361         if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
 362                 return -EINVAL;
 363
 364         /*
 365          * The second field must be a 32 bit integer at 64 bit offset.
 366          */
 367         m++;
 368         offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
 369         size = sizeof_field(struct bpf_cgroup_storage_key, attach_type);
 370         if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
 371                 return -EINVAL;
 372
 373         return 0;
 374 }
 375
 376 static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *_key,
 377                                          struct seq_file *m)
 378 {
 379         enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
 380         struct bpf_cgroup_storage_key *key = _key;
 381         struct bpf_cgroup_storage *storage;
 382         int cpu;
 383
 384         rcu_read_lock();
 385         storage = cgroup_storage_lookup(map_to_storage(map), key, false);
 386         if (!storage) {
 387                 rcu_read_unlock();
 388                 return;
 389         }
 390
 391         btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
 392         stype = cgroup_storage_type(map);
 393         if (stype == BPF_CGROUP_STORAGE_SHARED) {
 394                 seq_puts(m, ": ");
 395                 btf_type_seq_show(map->btf, map->btf_value_type_id,
 396                                   &READ_ONCE(storage->buf)->data[0], m);
 397                 seq_puts(m, "\n");
 398         } else {
 399                 seq_puts(m, ": {\n");
 400                 for_each_possible_cpu(cpu) {
 401                         seq_printf(m, "\tcpu%d: ", cpu);
 402                         btf_type_seq_show(map->btf, map->btf_value_type_id,
 403                                           per_cpu_ptr(storage->percpu_buf, cpu),
 404                                           m);
 405                         seq_puts(m, "\n");
 406                 }
 407                 seq_puts(m, "}\n");
 408         }
 409         rcu_read_unlock();
 410 }
 411
 412 const struct bpf_map_ops cgroup_storage_map_ops = {
 413         .map_alloc = cgroup_storage_map_alloc,
 414         .map_free = cgroup_storage_map_free,
 415         .map_get_next_key = cgroup_storage_get_next_key,
 416         .map_lookup_elem = cgroup_storage_lookup_elem,
 417         .map_update_elem = cgroup_storage_update_elem,
 418         .map_delete_elem = cgroup_storage_delete_elem,
 419         .map_check_btf = cgroup_storage_check_btf,
 420         .map_seq_show_elem = cgroup_storage_seq_show_elem,
 421 };
 422
 423 int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
 424 {
 425         enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
 426         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 427         int ret = -EBUSY;
 428
 429         spin_lock_bh(&map->lock);
 430
 431         if (map->prog && map->prog != prog)
 432                 goto unlock;
 433         if (prog->aux->cgroup_storage[stype] &&
 434             prog->aux->cgroup_storage[stype] != _map)
 435                 goto unlock;
 436
 437         map->prog = prog;
 438         prog->aux->cgroup_storage[stype] = _map;
 439         ret = 0;
 440 unlock:
 441         spin_unlock_bh(&map->lock);
 442
 443         return ret;
 444 }
 445
 446 void bpf_cgroup_storage_release(struct bpf_prog *prog, struct bpf_map *_map)
 447 {
 448         enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
 449         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 450
 451         spin_lock_bh(&map->lock);
 452         if (map->prog == prog) {
 453                 WARN_ON(prog->aux->cgroup_storage[stype] != _map);
 454                 map->prog = NULL;
 455                 prog->aux->cgroup_storage[stype] = NULL;
 456         }
 457         spin_unlock_bh(&map->lock);
 458 }
 459
 460 static size_t bpf_cgroup_storage_calculate_size(struct bpf_map *map, u32 *pages)
 461 {
 462         size_t size;
 463
 464         if (cgroup_storage_type(map) == BPF_CGROUP_STORAGE_SHARED) {
 465                 size = sizeof(struct bpf_storage_buffer) + map->value_size;
 466                 *pages = round_up(sizeof(struct bpf_cgroup_storage) + size,
 467                                   PAGE_SIZE) >> PAGE_SHIFT;
 468         } else {
 469                 size = map->value_size;
 470                 *pages = round_up(round_up(size, 8) * num_possible_cpus(),
 471                                   PAGE_SIZE) >> PAGE_SHIFT;
 472         }
 473
 474         return size;
 475 }
 476
 477 struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
 478                                         enum bpf_cgroup_storage_type stype)
 479 {
 480         struct bpf_cgroup_storage *storage;
 481         struct bpf_map *map;
 482         gfp_t flags;
 483         size_t size;
 484         u32 pages;
 485
 486         map = prog->aux->cgroup_storage[stype];
 487         if (!map)
 488                 return NULL;
 489
 490         size = bpf_cgroup_storage_calculate_size(map, &pages);
 491
 492         if (bpf_map_charge_memlock(map, pages))
 493                 return ERR_PTR(-EPERM);
 494
 495         storage = kmalloc_node(sizeof(struct bpf_cgroup_storage),
 496                                __GFP_ZERO | GFP_USER, map->numa_node);
 497         if (!storage)
 498                 goto enomem;
 499
 500         flags = __GFP_ZERO | GFP_USER;
 501
 502         if (stype == BPF_CGROUP_STORAGE_SHARED) {
 503                 storage->buf = kmalloc_node(size, flags, map->numa_node);
 504                 if (!storage->buf)
 505                         goto enomem;
 506                 check_and_init_map_lock(map, storage->buf->data);
 507         } else {
 508                 storage->percpu_buf = __alloc_percpu_gfp(size, 8, flags);
 509                 if (!storage->percpu_buf)
 510                         goto enomem;
 511         }
 512
 513         storage->map = (struct bpf_cgroup_storage_map *)map;
 514
 515         return storage;
 516
 517 enomem:
 518         bpf_map_uncharge_memlock(map, pages);
 519         kfree(storage);
 520         return ERR_PTR(-ENOMEM);
 521 }
 522
 523 static void free_shared_cgroup_storage_rcu(struct rcu_head *rcu)
 524 {
 525         struct bpf_cgroup_storage *storage =
 526                 container_of(rcu, struct bpf_cgroup_storage, rcu);
 527
 528         kfree(storage->buf);
 529         kfree(storage);
 530 }
 531
 532 static void free_percpu_cgroup_storage_rcu(struct rcu_head *rcu)
 533 {
 534         struct bpf_cgroup_storage *storage =
 535                 container_of(rcu, struct bpf_cgroup_storage, rcu);
 536
 537         free_percpu(storage->percpu_buf);
 538         kfree(storage);
 539 }
 540
 541 void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
 542 {
 543         enum bpf_cgroup_storage_type stype;
 544         struct bpf_map *map;
 545         u32 pages;
 546
 547         if (!storage)
 548                 return;
 549
 550         map = &storage->map->map;
 551
 552         bpf_cgroup_storage_calculate_size(map, &pages);
 553         bpf_map_uncharge_memlock(map, pages);
 554
 555         stype = cgroup_storage_type(map);
 556         if (stype == BPF_CGROUP_STORAGE_SHARED)
 557                 call_rcu(&storage->rcu, free_shared_cgroup_storage_rcu);
 558         else
 559                 call_rcu(&storage->rcu, free_percpu_cgroup_storage_rcu);
 560 }
 561
 562 void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
 563                              struct cgroup *cgroup,
 564                              enum bpf_attach_type type)
 565 {
 566         struct bpf_cgroup_storage_map *map;
 567
 568         if (!storage)
 569                 return;
 570
 571         storage->key.attach_type = type;
 572         storage->key.cgroup_inode_id = cgroup_id(cgroup);
 573
 574         map = storage->map;
 575
 576         spin_lock_bh(&map->lock);
 577         WARN_ON(cgroup_storage_insert(map, storage));
 578         list_add(&storage->list, &map->list);
 579         spin_unlock_bh(&map->lock);
 580 }
 581
 582 void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage)
 583 {
 584         struct bpf_cgroup_storage_map *map;
 585         struct rb_root *root;
 586
 587         if (!storage)
 588                 return;
 589
 590         map = storage->map;
 591
 592         spin_lock_bh(&map->lock);
 593         root = &map->root;
 594         rb_erase(&storage->node, root);
 595
 596         list_del(&storage->list);
 597         spin_unlock_bh(&map->lock);
 598 }
 599
 600 #endif