root/kernel/bpf/arraymap.c

DEFINITIONS

1. bpf_array_free_percpu
2. bpf_array_alloc_percpu
3. array_map_alloc_check
4. array_map_alloc
5. array_map_lookup_elem
6. array_map_direct_value_addr
7. array_map_direct_value_meta
8. array_map_gen_lookup
9. percpu_array_map_lookup_elem
10. bpf_percpu_array_copy
11. array_map_get_next_key
12. array_map_update_elem
13. bpf_percpu_array_update
14. array_map_delete_elem
15. array_map_free
16. array_map_seq_show_elem
17. percpu_array_map_seq_show_elem
18. array_map_check_btf
19. fd_array_map_alloc_check
20. fd_array_map_free
21. fd_array_map_lookup_elem
22. bpf_fd_array_map_lookup_elem
23. bpf_fd_array_map_update_elem
24. fd_array_map_delete_elem
25. prog_fd_array_get_ptr
26. prog_fd_array_put_ptr
27. prog_fd_array_sys_lookup_elem
28. bpf_fd_array_map_clear
29. prog_array_map_seq_show_elem
30. bpf_event_entry_gen
31. __bpf_event_entry_free
32. bpf_event_entry_free_rcu
33. perf_event_fd_array_get_ptr
34. perf_event_fd_array_put_ptr
35. perf_event_fd_array_release
36. cgroup_fd_array_get_ptr
37. cgroup_fd_array_put_ptr
38. cgroup_fd_array_free
39. array_of_map_alloc
40. array_of_map_free
41. array_of_map_lookup_elem
42. array_of_map_gen_lookup

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   3  * Copyright (c) 2016,2017 Facebook
   4  */
   5 #include <linux/bpf.h>
   6 #include <linux/btf.h>
   7 #include <linux/err.h>
   8 #include <linux/slab.h>
   9 #include <linux/mm.h>
  10 #include <linux/filter.h>
  11 #include <linux/perf_event.h>
  12 #include <uapi/linux/btf.h>
  13 
  14 #include "map_in_map.h"
  15 
  16 #define ARRAY_CREATE_FLAG_MASK \
  17         (BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
  18 
  19 static void bpf_array_free_percpu(struct bpf_array *array)
  20 {
  21         int i;
  22 
  23         for (i = 0; i < array->map.max_entries; i++) {
  24                 free_percpu(array->pptrs[i]);
  25                 cond_resched();
  26         }
  27 }
  28 
  29 static int bpf_array_alloc_percpu(struct bpf_array *array)
  30 {
  31         void __percpu *ptr;
  32         int i;
  33 
  34         for (i = 0; i < array->map.max_entries; i++) {
  35                 ptr = __alloc_percpu_gfp(array->elem_size, 8,
  36                                          GFP_USER | __GFP_NOWARN);
  37                 if (!ptr) {
  38                         bpf_array_free_percpu(array);
  39                         return -ENOMEM;
  40                 }
  41                 array->pptrs[i] = ptr;
  42                 cond_resched();
  43         }
  44 
  45         return 0;
  46 }
  47 
  48 /* Called from syscall */
  49 int array_map_alloc_check(union bpf_attr *attr)
  50 {
  51         bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
  52         int numa_node = bpf_map_attr_numa_node(attr);
  53 
  54         /* check sanity of attributes */
  55         if (attr->max_entries == 0 || attr->key_size != 4 ||
  56             attr->value_size == 0 ||
  57             attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||
  58             !bpf_map_flags_access_ok(attr->map_flags) ||
  59             (percpu && numa_node != NUMA_NO_NODE))
  60                 return -EINVAL;
  61 
  62         if (attr->value_size > KMALLOC_MAX_SIZE)
  63                 /* if value_size is bigger, the user space won't be able to
  64                  * access the elements.
  65                  */
  66                 return -E2BIG;
  67 
  68         return 0;
  69 }
  70 
  71 static struct bpf_map *array_map_alloc(union bpf_attr *attr)
  72 {
  73         bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
  74         int ret, numa_node = bpf_map_attr_numa_node(attr);
  75         u32 elem_size, index_mask, max_entries;
  76         bool unpriv = !capable(CAP_SYS_ADMIN);
  77         u64 cost, array_size, mask64;
  78         struct bpf_map_memory mem;
  79         struct bpf_array *array;
  80 
  81         elem_size = round_up(attr->value_size, 8);
  82 
  83         max_entries = attr->max_entries;
  84 
  85         /* On 32 bit archs roundup_pow_of_two() with max_entries that has
  86          * upper most bit set in u32 space is undefined behavior due to
  87          * resulting 1U << 32, so do it manually here in u64 space.
  88          */
  89         mask64 = fls_long(max_entries - 1);
  90         mask64 = 1ULL << mask64;
  91         mask64 -= 1;
  92 
  93         index_mask = mask64;
  94         if (unpriv) {
  95                 /* round up array size to nearest power of 2,
  96                  * since cpu will speculate within index_mask limits
  97                  */
  98                 max_entries = index_mask + 1;
  99                 /* Check for overflows. */
 100                 if (max_entries < attr->max_entries)
 101                         return ERR_PTR(-E2BIG);
 102         }
 103 
 104         array_size = sizeof(*array);
 105         if (percpu)
 106                 array_size += (u64) max_entries * sizeof(void *);
 107         else
 108                 array_size += (u64) max_entries * elem_size;
 109 
 110         /* make sure there is no u32 overflow later in round_up() */
 111         cost = array_size;
 112         if (percpu)
 113                 cost += (u64)attr->max_entries * elem_size * num_possible_cpus();
 114 
 115         ret = bpf_map_charge_init(&mem, cost);
 116         if (ret < 0)
 117                 return ERR_PTR(ret);
 118 
 119         /* allocate all map elements and zero-initialize them */
 120         array = bpf_map_area_alloc(array_size, numa_node);
 121         if (!array) {
 122                 bpf_map_charge_finish(&mem);
 123                 return ERR_PTR(-ENOMEM);
 124         }
 125         array->index_mask = index_mask;
 126         array->map.unpriv_array = unpriv;
 127 
 128         /* copy mandatory map attributes */
 129         bpf_map_init_from_attr(&array->map, attr);
 130         bpf_map_charge_move(&array->map.memory, &mem);
 131         array->elem_size = elem_size;
 132 
 133         if (percpu && bpf_array_alloc_percpu(array)) {
 134                 bpf_map_charge_finish(&array->map.memory);
 135                 bpf_map_area_free(array);
 136                 return ERR_PTR(-ENOMEM);
 137         }
 138 
 139         return &array->map;
 140 }
 141 
 142 /* Called from syscall or from eBPF program */
 143 static void *array_map_lookup_elem(struct bpf_map *map, void *key)
 144 {
 145         struct bpf_array *array = container_of(map, struct bpf_array, map);
 146         u32 index = *(u32 *)key;
 147 
 148         if (unlikely(index >= array->map.max_entries))
 149                 return NULL;
 150 
 151         return array->value + array->elem_size * (index & array->index_mask);
 152 }
 153 
 154 static int array_map_direct_value_addr(const struct bpf_map *map, u64 *imm,
 155                                        u32 off)
 156 {
 157         struct bpf_array *array = container_of(map, struct bpf_array, map);
 158 
 159         if (map->max_entries != 1)
 160                 return -ENOTSUPP;
 161         if (off >= map->value_size)
 162                 return -EINVAL;
 163 
 164         *imm = (unsigned long)array->value;
 165         return 0;
 166 }
 167 
 168 static int array_map_direct_value_meta(const struct bpf_map *map, u64 imm,
 169                                        u32 *off)
 170 {
 171         struct bpf_array *array = container_of(map, struct bpf_array, map);
 172         u64 base = (unsigned long)array->value;
 173         u64 range = array->elem_size;
 174 
 175         if (map->max_entries != 1)
 176                 return -ENOTSUPP;
 177         if (imm < base || imm >= base + range)
 178                 return -ENOENT;
 179 
 180         *off = imm - base;
 181         return 0;
 182 }
 183 
 184 /* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
 185 static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 186 {
 187         struct bpf_array *array = container_of(map, struct bpf_array, map);
 188         struct bpf_insn *insn = insn_buf;
 189         u32 elem_size = round_up(map->value_size, 8);
 190         const int ret = BPF_REG_0;
 191         const int map_ptr = BPF_REG_1;
 192         const int index = BPF_REG_2;
 193 
 194         *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
 195         *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
 196         if (map->unpriv_array) {
 197                 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 4);
 198                 *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
 199         } else {
 200                 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
 201         }
 202 
 203         if (is_power_of_2(elem_size)) {
 204                 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
 205         } else {
 206                 *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
 207         }
 208         *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
 209         *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
 210         *insn++ = BPF_MOV64_IMM(ret, 0);
 211         return insn - insn_buf;
 212 }
 213 
 214 /* Called from eBPF program */
 215 static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
 216 {
 217         struct bpf_array *array = container_of(map, struct bpf_array, map);
 218         u32 index = *(u32 *)key;
 219 
 220         if (unlikely(index >= array->map.max_entries))
 221                 return NULL;
 222 
 223         return this_cpu_ptr(array->pptrs[index & array->index_mask]);
 224 }
 225 
 226 int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
 227 {
 228         struct bpf_array *array = container_of(map, struct bpf_array, map);
 229         u32 index = *(u32 *)key;
 230         void __percpu *pptr;
 231         int cpu, off = 0;
 232         u32 size;
 233 
 234         if (unlikely(index >= array->map.max_entries))
 235                 return -ENOENT;
 236 
 237         /* per_cpu areas are zero-filled and bpf programs can only
 238          * access 'value_size' of them, so copying rounded areas
 239          * will not leak any kernel data
 240          */
 241         size = round_up(map->value_size, 8);
 242         rcu_read_lock();
 243         pptr = array->pptrs[index & array->index_mask];
 244         for_each_possible_cpu(cpu) {
 245                 bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
 246                 off += size;
 247         }
 248         rcu_read_unlock();
 249         return 0;
 250 }
 251 
 252 /* Called from syscall */
 253 static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
 254 {
 255         struct bpf_array *array = container_of(map, struct bpf_array, map);
 256         u32 index = key ? *(u32 *)key : U32_MAX;
 257         u32 *next = (u32 *)next_key;
 258 
 259         if (index >= array->map.max_entries) {
 260                 *next = 0;
 261                 return 0;
 262         }
 263 
 264         if (index == array->map.max_entries - 1)
 265                 return -ENOENT;
 266 
 267         *next = index + 1;
 268         return 0;
 269 }
 270 
 271 /* Called from syscall or from eBPF program */
 272 static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
 273                                  u64 map_flags)
 274 {
 275         struct bpf_array *array = container_of(map, struct bpf_array, map);
 276         u32 index = *(u32 *)key;
 277         char *val;
 278 
 279         if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
 280                 /* unknown flags */
 281                 return -EINVAL;
 282 
 283         if (unlikely(index >= array->map.max_entries))
 284                 /* all elements were pre-allocated, cannot insert a new one */
 285                 return -E2BIG;
 286 
 287         if (unlikely(map_flags & BPF_NOEXIST))
 288                 /* all elements already exist */
 289                 return -EEXIST;
 290 
 291         if (unlikely((map_flags & BPF_F_LOCK) &&
 292                      !map_value_has_spin_lock(map)))
 293                 return -EINVAL;
 294 
 295         if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
 296                 memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
 297                        value, map->value_size);
 298         } else {
 299                 val = array->value +
 300                         array->elem_size * (index & array->index_mask);
 301                 if (map_flags & BPF_F_LOCK)
 302                         copy_map_value_locked(map, val, value, false);
 303                 else
 304                         copy_map_value(map, val, value);
 305         }
 306         return 0;
 307 }
 308 
 309 int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
 310                             u64 map_flags)
 311 {
 312         struct bpf_array *array = container_of(map, struct bpf_array, map);
 313         u32 index = *(u32 *)key;
 314         void __percpu *pptr;
 315         int cpu, off = 0;
 316         u32 size;
 317 
 318         if (unlikely(map_flags > BPF_EXIST))
 319                 /* unknown flags */
 320                 return -EINVAL;
 321 
 322         if (unlikely(index >= array->map.max_entries))
 323                 /* all elements were pre-allocated, cannot insert a new one */
 324                 return -E2BIG;
 325 
 326         if (unlikely(map_flags == BPF_NOEXIST))
 327                 /* all elements already exist */
 328                 return -EEXIST;
 329 
 330         /* the user space will provide round_up(value_size, 8) bytes that
 331          * will be copied into per-cpu area. bpf programs can only access
 332          * value_size of it. During lookup the same extra bytes will be
 333          * returned or zeros which were zero-filled by percpu_alloc,
 334          * so no kernel data leaks possible
 335          */
 336         size = round_up(map->value_size, 8);
 337         rcu_read_lock();
 338         pptr = array->pptrs[index & array->index_mask];
 339         for_each_possible_cpu(cpu) {
 340                 bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
 341                 off += size;
 342         }
 343         rcu_read_unlock();
 344         return 0;
 345 }
 346 
 347 /* Called from syscall or from eBPF program */
 348 static int array_map_delete_elem(struct bpf_map *map, void *key)
 349 {
 350         return -EINVAL;
 351 }
 352 
 353 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
 354 static void array_map_free(struct bpf_map *map)
 355 {
 356         struct bpf_array *array = container_of(map, struct bpf_array, map);
 357 
 358         /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
 359          * so the programs (can be more than one that used this map) were
 360          * disconnected from events. Wait for outstanding programs to complete
 361          * and free the array
 362          */
 363         synchronize_rcu();
 364 
 365         if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
 366                 bpf_array_free_percpu(array);
 367 
 368         bpf_map_area_free(array);
 369 }
 370 
 371 static void array_map_seq_show_elem(struct bpf_map *map, void *key,
 372                                     struct seq_file *m)
 373 {
 374         void *value;
 375 
 376         rcu_read_lock();
 377 
 378         value = array_map_lookup_elem(map, key);
 379         if (!value) {
 380                 rcu_read_unlock();
 381                 return;
 382         }
 383 
 384         if (map->btf_key_type_id)
 385                 seq_printf(m, "%u: ", *(u32 *)key);
 386         btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
 387         seq_puts(m, "\n");
 388 
 389         rcu_read_unlock();
 390 }
 391 
 392 static void percpu_array_map_seq_show_elem(struct bpf_map *map, void *key,
 393                                            struct seq_file *m)
 394 {
 395         struct bpf_array *array = container_of(map, struct bpf_array, map);
 396         u32 index = *(u32 *)key;
 397         void __percpu *pptr;
 398         int cpu;
 399 
 400         rcu_read_lock();
 401 
 402         seq_printf(m, "%u: {\n", *(u32 *)key);
 403         pptr = array->pptrs[index & array->index_mask];
 404         for_each_possible_cpu(cpu) {
 405                 seq_printf(m, "\tcpu%d: ", cpu);
 406                 btf_type_seq_show(map->btf, map->btf_value_type_id,
 407                                   per_cpu_ptr(pptr, cpu), m);
 408                 seq_puts(m, "\n");
 409         }
 410         seq_puts(m, "}\n");
 411 
 412         rcu_read_unlock();
 413 }
 414 
 415 static int array_map_check_btf(const struct bpf_map *map,
 416                                const struct btf *btf,
 417                                const struct btf_type *key_type,
 418                                const struct btf_type *value_type)
 419 {
 420         u32 int_data;
 421 
 422         /* One exception for keyless BTF: .bss/.data/.rodata map */
 423         if (btf_type_is_void(key_type)) {
 424                 if (map->map_type != BPF_MAP_TYPE_ARRAY ||
 425                     map->max_entries != 1)
 426                         return -EINVAL;
 427 
 428                 if (BTF_INFO_KIND(value_type->info) != BTF_KIND_DATASEC)
 429                         return -EINVAL;
 430 
 431                 return 0;
 432         }
 433 
 434         if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
 435                 return -EINVAL;
 436 
 437         int_data = *(u32 *)(key_type + 1);
 438         /* bpf array can only take a u32 key. This check makes sure
 439          * that the btf matches the attr used during map_create.
 440          */
 441         if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
 442                 return -EINVAL;
 443 
 444         return 0;
 445 }
 446 
 447 const struct bpf_map_ops array_map_ops = {
 448         .map_alloc_check = array_map_alloc_check,
 449         .map_alloc = array_map_alloc,
 450         .map_free = array_map_free,
 451         .map_get_next_key = array_map_get_next_key,
 452         .map_lookup_elem = array_map_lookup_elem,
 453         .map_update_elem = array_map_update_elem,
 454         .map_delete_elem = array_map_delete_elem,
 455         .map_gen_lookup = array_map_gen_lookup,
 456         .map_direct_value_addr = array_map_direct_value_addr,
 457         .map_direct_value_meta = array_map_direct_value_meta,
 458         .map_seq_show_elem = array_map_seq_show_elem,
 459         .map_check_btf = array_map_check_btf,
 460 };
 461 
 462 const struct bpf_map_ops percpu_array_map_ops = {
 463         .map_alloc_check = array_map_alloc_check,
 464         .map_alloc = array_map_alloc,
 465         .map_free = array_map_free,
 466         .map_get_next_key = array_map_get_next_key,
 467         .map_lookup_elem = percpu_array_map_lookup_elem,
 468         .map_update_elem = array_map_update_elem,
 469         .map_delete_elem = array_map_delete_elem,
 470         .map_seq_show_elem = percpu_array_map_seq_show_elem,
 471         .map_check_btf = array_map_check_btf,
 472 };
 473 
 474 static int fd_array_map_alloc_check(union bpf_attr *attr)
 475 {
 476         /* only file descriptors can be stored in this type of map */
 477         if (attr->value_size != sizeof(u32))
 478                 return -EINVAL;
 479         /* Program read-only/write-only not supported for special maps yet. */
 480         if (attr->map_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG))
 481                 return -EINVAL;
 482         return array_map_alloc_check(attr);
 483 }
 484 
 485 static void fd_array_map_free(struct bpf_map *map)
 486 {
 487         struct bpf_array *array = container_of(map, struct bpf_array, map);
 488         int i;
 489 
 490         synchronize_rcu();
 491 
 492         /* make sure it's empty */
 493         for (i = 0; i < array->map.max_entries; i++)
 494                 BUG_ON(array->ptrs[i] != NULL);
 495 
 496         bpf_map_area_free(array);
 497 }
 498 
 499 static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
 500 {
 501         return ERR_PTR(-EOPNOTSUPP);
 502 }
 503 
 504 /* only called from syscall */
 505 int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
 506 {
 507         void **elem, *ptr;
 508         int ret =  0;
 509 
 510         if (!map->ops->map_fd_sys_lookup_elem)
 511                 return -ENOTSUPP;
 512 
 513         rcu_read_lock();
 514         elem = array_map_lookup_elem(map, key);
 515         if (elem && (ptr = READ_ONCE(*elem)))
 516                 *value = map->ops->map_fd_sys_lookup_elem(ptr);
 517         else
 518                 ret = -ENOENT;
 519         rcu_read_unlock();
 520 
 521         return ret;
 522 }
 523 
 524 /* only called from syscall */
 525 int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
 526                                  void *key, void *value, u64 map_flags)
 527 {
 528         struct bpf_array *array = container_of(map, struct bpf_array, map);
 529         void *new_ptr, *old_ptr;
 530         u32 index = *(u32 *)key, ufd;
 531 
 532         if (map_flags != BPF_ANY)
 533                 return -EINVAL;
 534 
 535         if (index >= array->map.max_entries)
 536                 return -E2BIG;
 537 
 538         ufd = *(u32 *)value;
 539         new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
 540         if (IS_ERR(new_ptr))
 541                 return PTR_ERR(new_ptr);
 542 
 543         old_ptr = xchg(array->ptrs + index, new_ptr);
 544         if (old_ptr)
 545                 map->ops->map_fd_put_ptr(old_ptr);
 546 
 547         return 0;
 548 }
 549 
 550 static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
 551 {
 552         struct bpf_array *array = container_of(map, struct bpf_array, map);
 553         void *old_ptr;
 554         u32 index = *(u32 *)key;
 555 
 556         if (index >= array->map.max_entries)
 557                 return -E2BIG;
 558 
 559         old_ptr = xchg(array->ptrs + index, NULL);
 560         if (old_ptr) {
 561                 map->ops->map_fd_put_ptr(old_ptr);
 562                 return 0;
 563         } else {
 564                 return -ENOENT;
 565         }
 566 }
 567 
 568 static void *prog_fd_array_get_ptr(struct bpf_map *map,
 569                                    struct file *map_file, int fd)
 570 {
 571         struct bpf_array *array = container_of(map, struct bpf_array, map);
 572         struct bpf_prog *prog = bpf_prog_get(fd);
 573 
 574         if (IS_ERR(prog))
 575                 return prog;
 576 
 577         if (!bpf_prog_array_compatible(array, prog)) {
 578                 bpf_prog_put(prog);
 579                 return ERR_PTR(-EINVAL);
 580         }
 581 
 582         return prog;
 583 }
 584 
 585 static void prog_fd_array_put_ptr(void *ptr)
 586 {
 587         bpf_prog_put(ptr);
 588 }
 589 
 590 static u32 prog_fd_array_sys_lookup_elem(void *ptr)
 591 {
 592         return ((struct bpf_prog *)ptr)->aux->id;
 593 }
 594 
 595 /* decrement refcnt of all bpf_progs that are stored in this map */
 596 static void bpf_fd_array_map_clear(struct bpf_map *map)
 597 {
 598         struct bpf_array *array = container_of(map, struct bpf_array, map);
 599         int i;
 600 
 601         for (i = 0; i < array->map.max_entries; i++)
 602                 fd_array_map_delete_elem(map, &i);
 603 }
 604 
 605 static void prog_array_map_seq_show_elem(struct bpf_map *map, void *key,
 606                                          struct seq_file *m)
 607 {
 608         void **elem, *ptr;
 609         u32 prog_id;
 610 
 611         rcu_read_lock();
 612 
 613         elem = array_map_lookup_elem(map, key);
 614         if (elem) {
 615                 ptr = READ_ONCE(*elem);
 616                 if (ptr) {
 617                         seq_printf(m, "%u: ", *(u32 *)key);
 618                         prog_id = prog_fd_array_sys_lookup_elem(ptr);
 619                         btf_type_seq_show(map->btf, map->btf_value_type_id,
 620                                           &prog_id, m);
 621                         seq_puts(m, "\n");
 622                 }
 623         }
 624 
 625         rcu_read_unlock();
 626 }
 627 
 628 const struct bpf_map_ops prog_array_map_ops = {
 629         .map_alloc_check = fd_array_map_alloc_check,
 630         .map_alloc = array_map_alloc,
 631         .map_free = fd_array_map_free,
 632         .map_get_next_key = array_map_get_next_key,
 633         .map_lookup_elem = fd_array_map_lookup_elem,
 634         .map_delete_elem = fd_array_map_delete_elem,
 635         .map_fd_get_ptr = prog_fd_array_get_ptr,
 636         .map_fd_put_ptr = prog_fd_array_put_ptr,
 637         .map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem,
 638         .map_release_uref = bpf_fd_array_map_clear,
 639         .map_seq_show_elem = prog_array_map_seq_show_elem,
 640 };
 641 
 642 static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
 643                                                    struct file *map_file)
 644 {
 645         struct bpf_event_entry *ee;
 646 
 647         ee = kzalloc(sizeof(*ee), GFP_ATOMIC);
 648         if (ee) {
 649                 ee->event = perf_file->private_data;
 650                 ee->perf_file = perf_file;
 651                 ee->map_file = map_file;
 652         }
 653 
 654         return ee;
 655 }
 656 
 657 static void __bpf_event_entry_free(struct rcu_head *rcu)
 658 {
 659         struct bpf_event_entry *ee;
 660 
 661         ee = container_of(rcu, struct bpf_event_entry, rcu);
 662         fput(ee->perf_file);
 663         kfree(ee);
 664 }
 665 
 666 static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
 667 {
 668         call_rcu(&ee->rcu, __bpf_event_entry_free);
 669 }
 670 
 671 static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
 672                                          struct file *map_file, int fd)
 673 {
 674         struct bpf_event_entry *ee;
 675         struct perf_event *event;
 676         struct file *perf_file;
 677         u64 value;
 678 
 679         perf_file = perf_event_get(fd);
 680         if (IS_ERR(perf_file))
 681                 return perf_file;
 682 
 683         ee = ERR_PTR(-EOPNOTSUPP);
 684         event = perf_file->private_data;
 685         if (perf_event_read_local(event, &value, NULL, NULL) == -EOPNOTSUPP)
 686                 goto err_out;
 687 
 688         ee = bpf_event_entry_gen(perf_file, map_file);
 689         if (ee)
 690                 return ee;
 691         ee = ERR_PTR(-ENOMEM);
 692 err_out:
 693         fput(perf_file);
 694         return ee;
 695 }
 696 
 697 static void perf_event_fd_array_put_ptr(void *ptr)
 698 {
 699         bpf_event_entry_free_rcu(ptr);
 700 }
 701 
 702 static void perf_event_fd_array_release(struct bpf_map *map,
 703                                         struct file *map_file)
 704 {
 705         struct bpf_array *array = container_of(map, struct bpf_array, map);
 706         struct bpf_event_entry *ee;
 707         int i;
 708 
 709         rcu_read_lock();
 710         for (i = 0; i < array->map.max_entries; i++) {
 711                 ee = READ_ONCE(array->ptrs[i]);
 712                 if (ee && ee->map_file == map_file)
 713                         fd_array_map_delete_elem(map, &i);
 714         }
 715         rcu_read_unlock();
 716 }
 717 
 718 const struct bpf_map_ops perf_event_array_map_ops = {
 719         .map_alloc_check = fd_array_map_alloc_check,
 720         .map_alloc = array_map_alloc,
 721         .map_free = fd_array_map_free,
 722         .map_get_next_key = array_map_get_next_key,
 723         .map_lookup_elem = fd_array_map_lookup_elem,
 724         .map_delete_elem = fd_array_map_delete_elem,
 725         .map_fd_get_ptr = perf_event_fd_array_get_ptr,
 726         .map_fd_put_ptr = perf_event_fd_array_put_ptr,
 727         .map_release = perf_event_fd_array_release,
 728         .map_check_btf = map_check_no_btf,
 729 };
 730 
 731 #ifdef CONFIG_CGROUPS
 732 static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
 733                                      struct file *map_file /* not used */,
 734                                      int fd)
 735 {
 736         return cgroup_get_from_fd(fd);
 737 }
 738 
 739 static void cgroup_fd_array_put_ptr(void *ptr)
 740 {
 741         /* cgroup_put free cgrp after a rcu grace period */
 742         cgroup_put(ptr);
 743 }
 744 
 745 static void cgroup_fd_array_free(struct bpf_map *map)
 746 {
 747         bpf_fd_array_map_clear(map);
 748         fd_array_map_free(map);
 749 }
 750 
 751 const struct bpf_map_ops cgroup_array_map_ops = {
 752         .map_alloc_check = fd_array_map_alloc_check,
 753         .map_alloc = array_map_alloc,
 754         .map_free = cgroup_fd_array_free,
 755         .map_get_next_key = array_map_get_next_key,
 756         .map_lookup_elem = fd_array_map_lookup_elem,
 757         .map_delete_elem = fd_array_map_delete_elem,
 758         .map_fd_get_ptr = cgroup_fd_array_get_ptr,
 759         .map_fd_put_ptr = cgroup_fd_array_put_ptr,
 760         .map_check_btf = map_check_no_btf,
 761 };
 762 #endif
 763 
 764 static struct bpf_map *array_of_map_alloc(union bpf_attr *attr)
 765 {
 766         struct bpf_map *map, *inner_map_meta;
 767 
 768         inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
 769         if (IS_ERR(inner_map_meta))
 770                 return inner_map_meta;
 771 
 772         map = array_map_alloc(attr);
 773         if (IS_ERR(map)) {
 774                 bpf_map_meta_free(inner_map_meta);
 775                 return map;
 776         }
 777 
 778         map->inner_map_meta = inner_map_meta;
 779 
 780         return map;
 781 }
 782 
 783 static void array_of_map_free(struct bpf_map *map)
 784 {
 785         /* map->inner_map_meta is only accessed by syscall which
 786          * is protected by fdget/fdput.
 787          */
 788         bpf_map_meta_free(map->inner_map_meta);
 789         bpf_fd_array_map_clear(map);
 790         fd_array_map_free(map);
 791 }
 792 
 793 static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
 794 {
 795         struct bpf_map **inner_map = array_map_lookup_elem(map, key);
 796 
 797         if (!inner_map)
 798                 return NULL;
 799 
 800         return READ_ONCE(*inner_map);
 801 }
 802 
 803 static u32 array_of_map_gen_lookup(struct bpf_map *map,
 804                                    struct bpf_insn *insn_buf)
 805 {
 806         struct bpf_array *array = container_of(map, struct bpf_array, map);
 807         u32 elem_size = round_up(map->value_size, 8);
 808         struct bpf_insn *insn = insn_buf;
 809         const int ret = BPF_REG_0;
 810         const int map_ptr = BPF_REG_1;
 811         const int index = BPF_REG_2;
 812 
 813         *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
 814         *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
 815         if (map->unpriv_array) {
 816                 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6);
 817                 *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
 818         } else {
 819                 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
 820         }
 821         if (is_power_of_2(elem_size))
 822                 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
 823         else
 824                 *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
 825         *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
 826         *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
 827         *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
 828         *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
 829         *insn++ = BPF_MOV64_IMM(ret, 0);
 830 
 831         return insn - insn_buf;
 832 }
 833 
 834 const struct bpf_map_ops array_of_maps_map_ops = {
 835         .map_alloc_check = fd_array_map_alloc_check,
 836         .map_alloc = array_of_map_alloc,
 837         .map_free = array_of_map_free,
 838         .map_get_next_key = array_map_get_next_key,
 839         .map_lookup_elem = array_of_map_lookup_elem,
 840         .map_delete_elem = fd_array_map_delete_elem,
 841         .map_fd_get_ptr = bpf_map_fd_get_ptr,
 842         .map_fd_put_ptr = bpf_map_fd_put_ptr,
 843         .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
 844         .map_gen_lookup = array_of_map_gen_lookup,
 845         .map_check_btf = map_check_no_btf,
 846 };