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