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/bpf_local_storage.h>
   5 #include <linux/btf.h>
   6 #include <linux/bug.h>
   7 #include <linux/filter.h>
   8 #include <linux/mm.h>
   9 #include <linux/rbtree.h>
  10 #include <linux/slab.h>
  11 #include <uapi/linux/btf.h>
  12 #include <linux/btf_ids.h>
  13
  14 #ifdef CONFIG_CGROUP_BPF
  15
  16 #include "../cgroup/cgroup-internal.h"
  17
  18 #define LOCAL_STORAGE_CREATE_FLAG_MASK                                  \
  19         (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
  20
  21 struct bpf_cgroup_storage_map {
  22         struct bpf_map map;
  23
  24         spinlock_t lock;
  25         struct rb_root root;
  26         struct list_head list;
  27 };
  28
  29 static struct bpf_cgroup_storage_map *map_to_storage(struct bpf_map *map)
  30 {
  31         return container_of(map, struct bpf_cgroup_storage_map, map);
  32 }
  33
  34 static bool attach_type_isolated(const struct bpf_map *map)
  35 {
  36         return map->key_size == sizeof(struct bpf_cgroup_storage_key);
  37 }
  38
  39 static int bpf_cgroup_storage_key_cmp(const struct bpf_cgroup_storage_map *map,
  40                                       const void *_key1, const void *_key2)
  41 {
  42         if (attach_type_isolated(&map->map)) {
  43                 const struct bpf_cgroup_storage_key *key1 = _key1;
  44                 const struct bpf_cgroup_storage_key *key2 = _key2;
  45
  46                 if (key1->cgroup_inode_id < key2->cgroup_inode_id)
  47                         return -1;
  48                 else if (key1->cgroup_inode_id > key2->cgroup_inode_id)
  49                         return 1;
  50                 else if (key1->attach_type < key2->attach_type)
  51                         return -1;
  52                 else if (key1->attach_type > key2->attach_type)
  53                         return 1;
  54         } else {
  55                 const __u64 *cgroup_inode_id1 = _key1;
  56                 const __u64 *cgroup_inode_id2 = _key2;
  57
  58                 if (*cgroup_inode_id1 < *cgroup_inode_id2)
  59                         return -1;
  60                 else if (*cgroup_inode_id1 > *cgroup_inode_id2)
  61                         return 1;
  62         }
  63         return 0;
  64 }
  65
  66 struct bpf_cgroup_storage *
  67 cgroup_storage_lookup(struct bpf_cgroup_storage_map *map,
  68                       void *key, bool locked)
  69 {
  70         struct rb_root *root = &map->root;
  71         struct rb_node *node;
  72
  73         if (!locked)
  74                 spin_lock_bh(&map->lock);
  75
  76         node = root->rb_node;
  77         while (node) {
  78                 struct bpf_cgroup_storage *storage;
  79
  80                 storage = container_of(node, struct bpf_cgroup_storage, node);
  81
  82                 switch (bpf_cgroup_storage_key_cmp(map, key, &storage->key)) {
  83                 case -1:
  84                         node = node->rb_left;
  85                         break;
  86                 case 1:
  87                         node = node->rb_right;
  88                         break;
  89                 default:
  90                         if (!locked)
  91                                 spin_unlock_bh(&map->lock);
  92                         return storage;
  93                 }
  94         }
  95
  96         if (!locked)
  97                 spin_unlock_bh(&map->lock);
  98
  99         return NULL;
 100 }
 101
 102 static int cgroup_storage_insert(struct bpf_cgroup_storage_map *map,
 103                                  struct bpf_cgroup_storage *storage)
 104 {
 105         struct rb_root *root = &map->root;
 106         struct rb_node **new = &(root->rb_node), *parent = NULL;
 107
 108         while (*new) {
 109                 struct bpf_cgroup_storage *this;
 110
 111                 this = container_of(*new, struct bpf_cgroup_storage, node);
 112
 113                 parent = *new;
 114                 switch (bpf_cgroup_storage_key_cmp(map, &storage->key, &this->key)) {
 115                 case -1:
 116                         new = &((*new)->rb_left);
 117                         break;
 118                 case 1:
 119                         new = &((*new)->rb_right);
 120                         break;
 121                 default:
 122                         return -EEXIST;
 123                 }
 124         }
 125
 126         rb_link_node(&storage->node, parent, new);
 127         rb_insert_color(&storage->node, root);
 128
 129         return 0;
 130 }
 131
 132 static void *cgroup_storage_lookup_elem(struct bpf_map *_map, void *key)
 133 {
 134         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 135         struct bpf_cgroup_storage *storage;
 136
 137         storage = cgroup_storage_lookup(map, key, false);
 138         if (!storage)
 139                 return NULL;
 140
 141         return &READ_ONCE(storage->buf)->data[0];
 142 }
 143
 144 static long cgroup_storage_update_elem(struct bpf_map *map, void *key,
 145                                        void *value, u64 flags)
 146 {
 147         struct bpf_cgroup_storage *storage;
 148         struct bpf_storage_buffer *new;
 149
 150         if (unlikely(flags & ~(BPF_F_LOCK | BPF_EXIST)))
 151                 return -EINVAL;
 152
 153         if (unlikely((flags & BPF_F_LOCK) &&
 154                      !btf_record_has_field(map->record, BPF_SPIN_LOCK)))
 155                 return -EINVAL;
 156
 157         storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
 158                                         key, false);
 159         if (!storage)
 160                 return -ENOENT;
 161
 162         if (flags & BPF_F_LOCK) {
 163                 copy_map_value_locked(map, storage->buf->data, value, false);
 164                 return 0;
 165         }
 166
 167         new = bpf_map_kmalloc_node(map, struct_size(new, data, map->value_size),
 168                                    __GFP_ZERO | GFP_NOWAIT | __GFP_NOWARN,
 169                                    map->numa_node);
 170         if (!new)
 171                 return -ENOMEM;
 172
 173         memcpy(&new->data[0], value, map->value_size);
 174         check_and_init_map_value(map, new->data);
 175
 176         new = xchg(&storage->buf, new);
 177         kfree_rcu(new, rcu);
 178
 179         return 0;
 180 }
 181
 182 int bpf_percpu_cgroup_storage_copy(struct bpf_map *_map, void *key,
 183                                    void *value)
 184 {
 185         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 186         struct bpf_cgroup_storage *storage;
 187         int cpu, off = 0;
 188         u32 size;
 189
 190         rcu_read_lock();
 191         storage = cgroup_storage_lookup(map, key, false);
 192         if (!storage) {
 193                 rcu_read_unlock();
 194                 return -ENOENT;
 195         }
 196
 197         /* per_cpu areas are zero-filled and bpf programs can only
 198          * access 'value_size' of them, so copying rounded areas
 199          * will not leak any kernel data
 200          */
 201         size = round_up(_map->value_size, 8);
 202         for_each_possible_cpu(cpu) {
 203                 bpf_long_memcpy(value + off,
 204                                 per_cpu_ptr(storage->percpu_buf, cpu), size);
 205                 off += size;
 206         }
 207         rcu_read_unlock();
 208         return 0;
 209 }
 210
 211 int bpf_percpu_cgroup_storage_update(struct bpf_map *_map, void *key,
 212                                      void *value, u64 map_flags)
 213 {
 214         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 215         struct bpf_cgroup_storage *storage;
 216         int cpu, off = 0;
 217         u32 size;
 218
 219         if (map_flags != BPF_ANY && map_flags != BPF_EXIST)
 220                 return -EINVAL;
 221
 222         rcu_read_lock();
 223         storage = cgroup_storage_lookup(map, key, false);
 224         if (!storage) {
 225                 rcu_read_unlock();
 226                 return -ENOENT;
 227         }
 228
 229         /* the user space will provide round_up(value_size, 8) bytes that
 230          * will be copied into per-cpu area. bpf programs can only access
 231          * value_size of it. During lookup the same extra bytes will be
 232          * returned or zeros which were zero-filled by percpu_alloc,
 233          * so no kernel data leaks possible
 234          */
 235         size = round_up(_map->value_size, 8);
 236         for_each_possible_cpu(cpu) {
 237                 bpf_long_memcpy(per_cpu_ptr(storage->percpu_buf, cpu),
 238                                 value + off, size);
 239                 off += size;
 240         }
 241         rcu_read_unlock();
 242         return 0;
 243 }
 244
 245 static int cgroup_storage_get_next_key(struct bpf_map *_map, void *key,
 246                                        void *_next_key)
 247 {
 248         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 249         struct bpf_cgroup_storage *storage;
 250
 251         spin_lock_bh(&map->lock);
 252
 253         if (list_empty(&map->list))
 254                 goto enoent;
 255
 256         if (key) {
 257                 storage = cgroup_storage_lookup(map, key, true);
 258                 if (!storage)
 259                         goto enoent;
 260
 261                 storage = list_next_entry(storage, list_map);
 262                 if (!storage)
 263                         goto enoent;
 264         } else {
 265                 storage = list_first_entry(&map->list,
 266                                          struct bpf_cgroup_storage, list_map);
 267         }
 268
 269         spin_unlock_bh(&map->lock);
 270
 271         if (attach_type_isolated(&map->map)) {
 272                 struct bpf_cgroup_storage_key *next = _next_key;
 273                 *next = storage->key;
 274         } else {
 275                 __u64 *next = _next_key;
 276                 *next = storage->key.cgroup_inode_id;
 277         }
 278         return 0;
 279
 280 enoent:
 281         spin_unlock_bh(&map->lock);
 282         return -ENOENT;
 283 }
 284
 285 static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
 286 {
 287         __u32 max_value_size = BPF_LOCAL_STORAGE_MAX_VALUE_SIZE;
 288         int numa_node = bpf_map_attr_numa_node(attr);
 289         struct bpf_cgroup_storage_map *map;
 290
 291         /* percpu is bound by PCPU_MIN_UNIT_SIZE, non-percu
 292          * is the same as other local storages.
 293          */
 294         if (attr->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
 295                 max_value_size = min_t(__u32, max_value_size,
 296                                        PCPU_MIN_UNIT_SIZE);
 297
 298         if (attr->key_size != sizeof(struct bpf_cgroup_storage_key) &&
 299             attr->key_size != sizeof(__u64))
 300                 return ERR_PTR(-EINVAL);
 301
 302         if (attr->value_size == 0)
 303                 return ERR_PTR(-EINVAL);
 304
 305         if (attr->value_size > max_value_size)
 306                 return ERR_PTR(-E2BIG);
 307
 308         if (attr->map_flags & ~LOCAL_STORAGE_CREATE_FLAG_MASK ||
 309             !bpf_map_flags_access_ok(attr->map_flags))
 310                 return ERR_PTR(-EINVAL);
 311
 312         if (attr->max_entries)
 313                 /* max_entries is not used and enforced to be 0 */
 314                 return ERR_PTR(-EINVAL);
 315
 316         map = bpf_map_area_alloc(sizeof(struct bpf_cgroup_storage_map), numa_node);
 317         if (!map)
 318                 return ERR_PTR(-ENOMEM);
 319
 320         /* copy mandatory map attributes */
 321         bpf_map_init_from_attr(&map->map, attr);
 322
 323         spin_lock_init(&map->lock);
 324         map->root = RB_ROOT;
 325         INIT_LIST_HEAD(&map->list);
 326
 327         return &map->map;
 328 }
 329
 330 static void cgroup_storage_map_free(struct bpf_map *_map)
 331 {
 332         struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 333         struct list_head *storages = &map->list;
 334         struct bpf_cgroup_storage *storage, *stmp;
 335
 336         cgroup_lock();
 337
 338         list_for_each_entry_safe(storage, stmp, storages, list_map) {
 339                 bpf_cgroup_storage_unlink(storage);
 340                 bpf_cgroup_storage_free(storage);
 341         }
 342
 343         cgroup_unlock();
 344
 345         WARN_ON(!RB_EMPTY_ROOT(&map->root));
 346         WARN_ON(!list_empty(&map->list));
 347
 348         bpf_map_area_free(map);
 349 }
 350
 351 static long cgroup_storage_delete_elem(struct bpf_map *map, void *key)
 352 {
 353         return -EINVAL;
 354 }
 355
 356 static int cgroup_storage_check_btf(const struct bpf_map *map,
 357                                     const struct btf *btf,
 358                                     const struct btf_type *key_type,
 359                                     const struct btf_type *value_type)
 360 {
 361         if (attach_type_isolated(map)) {
 362                 struct btf_member *m;
 363                 u32 offset, size;
 364
 365                 /* Key is expected to be of struct bpf_cgroup_storage_key type,
 366                  * which is:
 367                  * struct bpf_cgroup_storage_key {
 368                  *      __u64   cgroup_inode_id;
 369                  *      __u32   attach_type;
 370                  * };
 371                  */
 372
 373                 /*
 374                  * Key_type must be a structure with two fields.
 375                  */
 376                 if (BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ||
 377                     BTF_INFO_VLEN(key_type->info) != 2)
 378                         return -EINVAL;
 379
 380                 /*
 381                  * The first field must be a 64 bit integer at 0 offset.
 382                  */
 383                 m = (struct btf_member *)(key_type + 1);
 384                 size = sizeof_field(struct bpf_cgroup_storage_key, cgroup_inode_id);
 385                 if (!btf_member_is_reg_int(btf, key_type, m, 0, size))
 386                         return -EINVAL;
 387
 388                 /*
 389                  * The second field must be a 32 bit integer at 64 bit offset.
 390                  */
 391                 m++;
 392                 offset = offsetof(struct bpf_cgroup_storage_key, attach_type);
 393                 size = sizeof_field(struct bpf_cgroup_storage_key, attach_type);
 394                 if (!btf_member_is_reg_int(btf, key_type, m, offset, size))
 395                         return -EINVAL;
 396         } else {
 397                 u32 int_data;
 398
 399                 /*
 400                  * Key is expected to be u64, which stores the cgroup_inode_id
 401                  */
 402
 403                 if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
 404                         return -EINVAL;
 405
 406                 int_data = *(u32 *)(key_type + 1);
 407                 if (BTF_INT_BITS(int_data) != 64 || BTF_INT_OFFSET(int_data))
 408                         return -EINVAL;
 409         }
 410
 411         return 0;
 412 }
 413
 414 static void cgroup_storage_seq_show_elem(struct bpf_map *map, void *key,
 415                                          struct seq_file *m)
 416 {
 417         enum bpf_cgroup_storage_type stype;
 418         struct bpf_cgroup_storage *storage;
 419         int cpu;
 420
 421         rcu_read_lock();
 422         storage = cgroup_storage_lookup(map_to_storage(map), key, false);
 423         if (!storage) {
 424                 rcu_read_unlock();
 425                 return;
 426         }
 427
 428         btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
 429         stype = cgroup_storage_type(map);
 430         if (stype == BPF_CGROUP_STORAGE_SHARED) {
 431                 seq_puts(m, ": ");
 432                 btf_type_seq_show(map->btf, map->btf_value_type_id,
 433                                   &READ_ONCE(storage->buf)->data[0], m);
 434                 seq_puts(m, "\n");
 435         } else {
 436                 seq_puts(m, ": {\n");
 437                 for_each_possible_cpu(cpu) {
 438                         seq_printf(m, "\tcpu%d: ", cpu);
 439                         btf_type_seq_show(map->btf, map->btf_value_type_id,
 440                                           per_cpu_ptr(storage->percpu_buf, cpu),
 441                                           m);
 442                         seq_puts(m, "\n");
 443                 }
 444                 seq_puts(m, "}\n");
 445         }
 446         rcu_read_unlock();
 447 }
 448
 449 static u64 cgroup_storage_map_usage(const struct bpf_map *map)
 450 {
 451         /* Currently the dynamically allocated elements are not counted. */
 452         return sizeof(struct bpf_cgroup_storage_map);
 453 }
 454
 455 BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct,
 456                    bpf_cgroup_storage_map)
 457 const struct bpf_map_ops cgroup_storage_map_ops = {
 458         .map_alloc = cgroup_storage_map_alloc,
 459         .map_free = cgroup_storage_map_free,
 460         .map_get_next_key = cgroup_storage_get_next_key,
 461         .map_lookup_elem = cgroup_storage_lookup_elem,
 462         .map_update_elem = cgroup_storage_update_elem,
 463         .map_delete_elem = cgroup_storage_delete_elem,
 464         .map_check_btf = cgroup_storage_check_btf,
 465         .map_seq_show_elem = cgroup_storage_seq_show_elem,
 466         .map_mem_usage = cgroup_storage_map_usage,
 467         .map_btf_id = &cgroup_storage_map_btf_ids[0],
 468 };
 469
 470 int bpf_cgroup_storage_assign(struct bpf_prog_aux *aux, struct bpf_map *_map)
 471 {
 472         enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
 473
 474         if (aux->cgroup_storage[stype] &&
 475             aux->cgroup_storage[stype] != _map)
 476                 return -EBUSY;
 477
 478         aux->cgroup_storage[stype] = _map;
 479         return 0;
 480 }
 481
 482 static size_t bpf_cgroup_storage_calculate_size(struct bpf_map *map, u32 *pages)
 483 {
 484         size_t size;
 485
 486         if (cgroup_storage_type(map) == BPF_CGROUP_STORAGE_SHARED) {
 487                 size = sizeof(struct bpf_storage_buffer) + map->value_size;
 488                 *pages = round_up(sizeof(struct bpf_cgroup_storage) + size,
 489                                   PAGE_SIZE) >> PAGE_SHIFT;
 490         } else {
 491                 size = map->value_size;
 492                 *pages = round_up(round_up(size, 8) * num_possible_cpus(),
 493                                   PAGE_SIZE) >> PAGE_SHIFT;
 494         }
 495
 496         return size;
 497 }
 498
 499 struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
 500                                         enum bpf_cgroup_storage_type stype)
 501 {
 502         const gfp_t gfp = __GFP_ZERO | GFP_USER;
 503         struct bpf_cgroup_storage *storage;
 504         struct bpf_map *map;
 505         size_t size;
 506         u32 pages;
 507
 508         map = prog->aux->cgroup_storage[stype];
 509         if (!map)
 510                 return NULL;
 511
 512         size = bpf_cgroup_storage_calculate_size(map, &pages);
 513
 514         storage = bpf_map_kmalloc_node(map, sizeof(struct bpf_cgroup_storage),
 515                                        gfp, map->numa_node);
 516         if (!storage)
 517                 goto enomem;
 518
 519         if (stype == BPF_CGROUP_STORAGE_SHARED) {
 520                 storage->buf = bpf_map_kmalloc_node(map, size, gfp,
 521                                                     map->numa_node);
 522                 if (!storage->buf)
 523                         goto enomem;
 524                 check_and_init_map_value(map, storage->buf->data);
 525         } else {
 526                 storage->percpu_buf = bpf_map_alloc_percpu(map, size, 8, gfp);
 527                 if (!storage->percpu_buf)
 528                         goto enomem;
 529         }
 530
 531         storage->map = (struct bpf_cgroup_storage_map *)map;
 532
 533         return storage;
 534
 535 enomem:
 536         kfree(storage);
 537         return ERR_PTR(-ENOMEM);
 538 }
 539
 540 static void free_shared_cgroup_storage_rcu(struct rcu_head *rcu)
 541 {
 542         struct bpf_cgroup_storage *storage =
 543                 container_of(rcu, struct bpf_cgroup_storage, rcu);
 544
 545         kfree(storage->buf);
 546         kfree(storage);
 547 }
 548
 549 static void free_percpu_cgroup_storage_rcu(struct rcu_head *rcu)
 550 {
 551         struct bpf_cgroup_storage *storage =
 552                 container_of(rcu, struct bpf_cgroup_storage, rcu);
 553
 554         free_percpu(storage->percpu_buf);
 555         kfree(storage);
 556 }
 557
 558 void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage)
 559 {
 560         enum bpf_cgroup_storage_type stype;
 561         struct bpf_map *map;
 562
 563         if (!storage)
 564                 return;
 565
 566         map = &storage->map->map;
 567         stype = cgroup_storage_type(map);
 568         if (stype == BPF_CGROUP_STORAGE_SHARED)
 569                 call_rcu(&storage->rcu, free_shared_cgroup_storage_rcu);
 570         else
 571                 call_rcu(&storage->rcu, free_percpu_cgroup_storage_rcu);
 572 }
 573
 574 void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
 575                              struct cgroup *cgroup,
 576                              enum bpf_attach_type type)
 577 {
 578         struct bpf_cgroup_storage_map *map;
 579
 580         if (!storage)
 581                 return;
 582
 583         storage->key.attach_type = type;
 584         storage->key.cgroup_inode_id = cgroup_id(cgroup);
 585
 586         map = storage->map;
 587
 588         spin_lock_bh(&map->lock);
 589         WARN_ON(cgroup_storage_insert(map, storage));
 590         list_add(&storage->list_map, &map->list);
 591         list_add(&storage->list_cg, &cgroup->bpf.storages);
 592         spin_unlock_bh(&map->lock);
 593 }
 594
 595 void bpf_cgroup_storage_unlink(struct bpf_cgroup_storage *storage)
 596 {
 597         struct bpf_cgroup_storage_map *map;
 598         struct rb_root *root;
 599
 600         if (!storage)
 601                 return;
 602
 603         map = storage->map;
 604
 605         spin_lock_bh(&map->lock);
 606         root = &map->root;
 607         rb_erase(&storage->node, root);
 608
 609         list_del(&storage->list_map);
 610         list_del(&storage->list_cg);
 611         spin_unlock_bh(&map->lock);
 612 }
 613
 614 #endif