kernel/bpf/syscall.c

   1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  *
   7  * This program is distributed in the hope that it will be useful, but
   8  * WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10  * General Public License for more details.
  11  */
  12 #include <linux/bpf.h>
  13 #include <linux/syscalls.h>
  14 #include <linux/slab.h>
  15 #include <linux/anon_inodes.h>
  16 #include <linux/file.h>
  17 #include <linux/license.h>
  18 #include <linux/filter.h>
  19 #include <linux/version.h>
  20
  21 int sysctl_unprivileged_bpf_disabled __read_mostly;
  22
  23 static LIST_HEAD(bpf_map_types);
  24
  25 static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
  26 {
  27         struct bpf_map_type_list *tl;
  28         struct bpf_map *map;
  29
  30         list_for_each_entry(tl, &bpf_map_types, list_node) {
  31                 if (tl->type == attr->map_type) {
  32                         map = tl->ops->map_alloc(attr);
  33                         if (IS_ERR(map))
  34                                 return map;
  35                         map->ops = tl->ops;
  36                         map->map_type = attr->map_type;
  37                         return map;
  38                 }
  39         }
  40         return ERR_PTR(-EINVAL);
  41 }
  42
  43 /* boot time registration of different map implementations */
  44 void bpf_register_map_type(struct bpf_map_type_list *tl)
  45 {
  46         list_add(&tl->list_node, &bpf_map_types);
  47 }
  48
  49 static int bpf_map_charge_memlock(struct bpf_map *map)
  50 {
  51         struct user_struct *user = get_current_user();
  52         unsigned long memlock_limit;
  53
  54         memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  55
  56         atomic_long_add(map->pages, &user->locked_vm);
  57
  58         if (atomic_long_read(&user->locked_vm) > memlock_limit) {
  59                 atomic_long_sub(map->pages, &user->locked_vm);
  60                 free_uid(user);
  61                 return -EPERM;
  62         }
  63         map->user = user;
  64         return 0;
  65 }
  66
  67 static void bpf_map_uncharge_memlock(struct bpf_map *map)
  68 {
  69         struct user_struct *user = map->user;
  70
  71         atomic_long_sub(map->pages, &user->locked_vm);
  72         free_uid(user);
  73 }
  74
  75 /* called from workqueue */
  76 static void bpf_map_free_deferred(struct work_struct *work)
  77 {
  78         struct bpf_map *map = container_of(work, struct bpf_map, work);
  79
  80         bpf_map_uncharge_memlock(map);
  81         /* implementation dependent freeing */
  82         map->ops->map_free(map);
  83 }
  84
  85 /* decrement map refcnt and schedule it for freeing via workqueue
  86  * (unrelying map implementation ops->map_free() might sleep)
  87  */
  88 void bpf_map_put(struct bpf_map *map)
  89 {
  90         if (atomic_dec_and_test(&map->refcnt)) {
  91                 INIT_WORK(&map->work, bpf_map_free_deferred);
  92                 schedule_work(&map->work);
  93         }
  94 }
  95
  96 static int bpf_map_release(struct inode *inode, struct file *filp)
  97 {
  98         struct bpf_map *map = filp->private_data;
  99
 100         if (map->map_type == BPF_MAP_TYPE_PROG_ARRAY)
 101                 /* prog_array stores refcnt-ed bpf_prog pointers
 102                  * release them all when user space closes prog_array_fd
 103                  */
 104                 bpf_fd_array_map_clear(map);
 105
 106         bpf_map_put(map);
 107         return 0;
 108 }
 109
 110 static const struct file_operations bpf_map_fops = {
 111         .release = bpf_map_release,
 112 };
 113
 114 int bpf_map_new_fd(struct bpf_map *map)
 115 {
 116         return anon_inode_getfd("bpf-map", &bpf_map_fops, map,
 117                                 O_RDWR | O_CLOEXEC);
 118 }
 119
 120 /* helper macro to check that unused fields 'union bpf_attr' are zero */
 121 #define CHECK_ATTR(CMD) \
 122         memchr_inv((void *) &attr->CMD##_LAST_FIELD + \
 123                    sizeof(attr->CMD##_LAST_FIELD), 0, \
 124                    sizeof(*attr) - \
 125                    offsetof(union bpf_attr, CMD##_LAST_FIELD) - \
 126                    sizeof(attr->CMD##_LAST_FIELD)) != NULL
 127
 128 #define BPF_MAP_CREATE_LAST_FIELD max_entries
 129 /* called via syscall */
 130 static int map_create(union bpf_attr *attr)
 131 {
 132         struct bpf_map *map;
 133         int err;
 134
 135         err = CHECK_ATTR(BPF_MAP_CREATE);
 136         if (err)
 137                 return -EINVAL;
 138
 139         /* find map type and init map: hashtable vs rbtree vs bloom vs ... */
 140         map = find_and_alloc_map(attr);
 141         if (IS_ERR(map))
 142                 return PTR_ERR(map);
 143
 144         atomic_set(&map->refcnt, 1);
 145
 146         err = bpf_map_charge_memlock(map);
 147         if (err)
 148                 goto free_map;
 149
 150         err = bpf_map_new_fd(map);
 151         if (err < 0)
 152                 /* failed to allocate fd */
 153                 goto free_map;
 154
 155         return err;
 156
 157 free_map:
 158         map->ops->map_free(map);
 159         return err;
 160 }
 161
 162 /* if error is returned, fd is released.
 163  * On success caller should complete fd access with matching fdput()
 164  */
 165 struct bpf_map *__bpf_map_get(struct fd f)
 166 {
 167         if (!f.file)
 168                 return ERR_PTR(-EBADF);
 169         if (f.file->f_op != &bpf_map_fops) {
 170                 fdput(f);
 171                 return ERR_PTR(-EINVAL);
 172         }
 173
 174         return f.file->private_data;
 175 }
 176
 177 struct bpf_map *bpf_map_get(u32 ufd)
 178 {
 179         struct fd f = fdget(ufd);
 180         struct bpf_map *map;
 181
 182         map = __bpf_map_get(f);
 183         if (IS_ERR(map))
 184                 return map;
 185
 186         atomic_inc(&map->refcnt);
 187         fdput(f);
 188
 189         return map;
 190 }
 191
 192 /* helper to convert user pointers passed inside __aligned_u64 fields */
 193 static void __user *u64_to_ptr(__u64 val)
 194 {
 195         return (void __user *) (unsigned long) val;
 196 }
 197
 198 /* last field in 'union bpf_attr' used by this command */
 199 #define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
 200
 201 static int map_lookup_elem(union bpf_attr *attr)
 202 {
 203         void __user *ukey = u64_to_ptr(attr->key);
 204         void __user *uvalue = u64_to_ptr(attr->value);
 205         int ufd = attr->map_fd;
 206         struct bpf_map *map;
 207         void *key, *value, *ptr;
 208         struct fd f;
 209         int err;
 210
 211         if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
 212                 return -EINVAL;
 213
 214         f = fdget(ufd);
 215         map = __bpf_map_get(f);
 216         if (IS_ERR(map))
 217                 return PTR_ERR(map);
 218
 219         err = -ENOMEM;
 220         key = kmalloc(map->key_size, GFP_USER);
 221         if (!key)
 222                 goto err_put;
 223
 224         err = -EFAULT;
 225         if (copy_from_user(key, ukey, map->key_size) != 0)
 226                 goto free_key;
 227
 228         err = -ENOMEM;
 229         value = kmalloc(map->value_size, GFP_USER);
 230         if (!value)
 231                 goto free_key;
 232
 233         rcu_read_lock();
 234         ptr = map->ops->map_lookup_elem(map, key);
 235         if (ptr)
 236                 memcpy(value, ptr, map->value_size);
 237         rcu_read_unlock();
 238
 239         err = -ENOENT;
 240         if (!ptr)
 241                 goto free_value;
 242
 243         err = -EFAULT;
 244         if (copy_to_user(uvalue, value, map->value_size) != 0)
 245                 goto free_value;
 246
 247         err = 0;
 248
 249 free_value:
 250         kfree(value);
 251 free_key:
 252         kfree(key);
 253 err_put:
 254         fdput(f);
 255         return err;
 256 }
 257
 258 #define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags
 259
 260 static int map_update_elem(union bpf_attr *attr)
 261 {
 262         void __user *ukey = u64_to_ptr(attr->key);
 263         void __user *uvalue = u64_to_ptr(attr->value);
 264         int ufd = attr->map_fd;
 265         struct bpf_map *map;
 266         void *key, *value;
 267         struct fd f;
 268         int err;
 269
 270         if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
 271                 return -EINVAL;
 272
 273         f = fdget(ufd);
 274         map = __bpf_map_get(f);
 275         if (IS_ERR(map))
 276                 return PTR_ERR(map);
 277
 278         err = -ENOMEM;
 279         key = kmalloc(map->key_size, GFP_USER);
 280         if (!key)
 281                 goto err_put;
 282
 283         err = -EFAULT;
 284         if (copy_from_user(key, ukey, map->key_size) != 0)
 285                 goto free_key;
 286
 287         err = -ENOMEM;
 288         value = kmalloc(map->value_size, GFP_USER);
 289         if (!value)
 290                 goto free_key;
 291
 292         err = -EFAULT;
 293         if (copy_from_user(value, uvalue, map->value_size) != 0)
 294                 goto free_value;
 295
 296         /* eBPF program that use maps are running under rcu_read_lock(),
 297          * therefore all map accessors rely on this fact, so do the same here
 298          */
 299         rcu_read_lock();
 300         err = map->ops->map_update_elem(map, key, value, attr->flags);
 301         rcu_read_unlock();
 302
 303 free_value:
 304         kfree(value);
 305 free_key:
 306         kfree(key);
 307 err_put:
 308         fdput(f);
 309         return err;
 310 }
 311
 312 #define BPF_MAP_DELETE_ELEM_LAST_FIELD key
 313
 314 static int map_delete_elem(union bpf_attr *attr)
 315 {
 316         void __user *ukey = u64_to_ptr(attr->key);
 317         int ufd = attr->map_fd;
 318         struct bpf_map *map;
 319         struct fd f;
 320         void *key;
 321         int err;
 322
 323         if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
 324                 return -EINVAL;
 325
 326         f = fdget(ufd);
 327         map = __bpf_map_get(f);
 328         if (IS_ERR(map))
 329                 return PTR_ERR(map);
 330
 331         err = -ENOMEM;
 332         key = kmalloc(map->key_size, GFP_USER);
 333         if (!key)
 334                 goto err_put;
 335
 336         err = -EFAULT;
 337         if (copy_from_user(key, ukey, map->key_size) != 0)
 338                 goto free_key;
 339
 340         rcu_read_lock();
 341         err = map->ops->map_delete_elem(map, key);
 342         rcu_read_unlock();
 343
 344 free_key:
 345         kfree(key);
 346 err_put:
 347         fdput(f);
 348         return err;
 349 }
 350
 351 /* last field in 'union bpf_attr' used by this command */
 352 #define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key
 353
 354 static int map_get_next_key(union bpf_attr *attr)
 355 {
 356         void __user *ukey = u64_to_ptr(attr->key);
 357         void __user *unext_key = u64_to_ptr(attr->next_key);
 358         int ufd = attr->map_fd;
 359         struct bpf_map *map;
 360         void *key, *next_key;
 361         struct fd f;
 362         int err;
 363
 364         if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
 365                 return -EINVAL;
 366
 367         f = fdget(ufd);
 368         map = __bpf_map_get(f);
 369         if (IS_ERR(map))
 370                 return PTR_ERR(map);
 371
 372         err = -ENOMEM;
 373         key = kmalloc(map->key_size, GFP_USER);
 374         if (!key)
 375                 goto err_put;
 376
 377         err = -EFAULT;
 378         if (copy_from_user(key, ukey, map->key_size) != 0)
 379                 goto free_key;
 380
 381         err = -ENOMEM;
 382         next_key = kmalloc(map->key_size, GFP_USER);
 383         if (!next_key)
 384                 goto free_key;
 385
 386         rcu_read_lock();
 387         err = map->ops->map_get_next_key(map, key, next_key);
 388         rcu_read_unlock();
 389         if (err)
 390                 goto free_next_key;
 391
 392         err = -EFAULT;
 393         if (copy_to_user(unext_key, next_key, map->key_size) != 0)
 394                 goto free_next_key;
 395
 396         err = 0;
 397
 398 free_next_key:
 399         kfree(next_key);
 400 free_key:
 401         kfree(key);
 402 err_put:
 403         fdput(f);
 404         return err;
 405 }
 406
 407 static LIST_HEAD(bpf_prog_types);
 408
 409 static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
 410 {
 411         struct bpf_prog_type_list *tl;
 412
 413         list_for_each_entry(tl, &bpf_prog_types, list_node) {
 414                 if (tl->type == type) {
 415                         prog->aux->ops = tl->ops;
 416                         prog->type = type;
 417                         return 0;
 418                 }
 419         }
 420
 421         return -EINVAL;
 422 }
 423
 424 void bpf_register_prog_type(struct bpf_prog_type_list *tl)
 425 {
 426         list_add(&tl->list_node, &bpf_prog_types);
 427 }
 428
 429 /* fixup insn->imm field of bpf_call instructions:
 430  * if (insn->imm == BPF_FUNC_map_lookup_elem)
 431  *      insn->imm = bpf_map_lookup_elem - __bpf_call_base;
 432  * else if (insn->imm == BPF_FUNC_map_update_elem)
 433  *      insn->imm = bpf_map_update_elem - __bpf_call_base;
 434  * else ...
 435  *
 436  * this function is called after eBPF program passed verification
 437  */
 438 static void fixup_bpf_calls(struct bpf_prog *prog)
 439 {
 440         const struct bpf_func_proto *fn;
 441         int i;
 442
 443         for (i = 0; i < prog->len; i++) {
 444                 struct bpf_insn *insn = &prog->insnsi[i];
 445
 446                 if (insn->code == (BPF_JMP | BPF_CALL)) {
 447                         /* we reach here when program has bpf_call instructions
 448                          * and it passed bpf_check(), means that
 449                          * ops->get_func_proto must have been supplied, check it
 450                          */
 451                         BUG_ON(!prog->aux->ops->get_func_proto);
 452
 453                         if (insn->imm == BPF_FUNC_get_route_realm)
 454                                 prog->dst_needed = 1;
 455                         if (insn->imm == BPF_FUNC_get_prandom_u32)
 456                                 bpf_user_rnd_init_once();
 457                         if (insn->imm == BPF_FUNC_tail_call) {
 458                                 /* mark bpf_tail_call as different opcode
 459                                  * to avoid conditional branch in
 460                                  * interpeter for every normal call
 461                                  * and to prevent accidental JITing by
 462                                  * JIT compiler that doesn't support
 463                                  * bpf_tail_call yet
 464                                  */
 465                                 insn->imm = 0;
 466                                 insn->code |= BPF_X;
 467                                 continue;
 468                         }
 469
 470                         fn = prog->aux->ops->get_func_proto(insn->imm);
 471                         /* all functions that have prototype and verifier allowed
 472                          * programs to call them, must be real in-kernel functions
 473                          */
 474                         BUG_ON(!fn->func);
 475                         insn->imm = fn->func - __bpf_call_base;
 476                 }
 477         }
 478 }
 479
 480 /* drop refcnt on maps used by eBPF program and free auxilary data */
 481 static void free_used_maps(struct bpf_prog_aux *aux)
 482 {
 483         int i;
 484
 485         for (i = 0; i < aux->used_map_cnt; i++)
 486                 bpf_map_put(aux->used_maps[i]);
 487
 488         kfree(aux->used_maps);
 489 }
 490
 491 static int bpf_prog_charge_memlock(struct bpf_prog *prog)
 492 {
 493         struct user_struct *user = get_current_user();
 494         unsigned long memlock_limit;
 495
 496         memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 497
 498         atomic_long_add(prog->pages, &user->locked_vm);
 499         if (atomic_long_read(&user->locked_vm) > memlock_limit) {
 500                 atomic_long_sub(prog->pages, &user->locked_vm);
 501                 free_uid(user);
 502                 return -EPERM;
 503         }
 504         prog->aux->user = user;
 505         return 0;
 506 }
 507
 508 static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
 509 {
 510         struct user_struct *user = prog->aux->user;
 511
 512         atomic_long_sub(prog->pages, &user->locked_vm);
 513         free_uid(user);
 514 }
 515
 516 static void __prog_put_common(struct rcu_head *rcu)
 517 {
 518         struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);
 519
 520         free_used_maps(aux);
 521         bpf_prog_uncharge_memlock(aux->prog);
 522         bpf_prog_free(aux->prog);
 523 }
 524
 525 /* version of bpf_prog_put() that is called after a grace period */
 526 void bpf_prog_put_rcu(struct bpf_prog *prog)
 527 {
 528         if (atomic_dec_and_test(&prog->aux->refcnt))
 529                 call_rcu(&prog->aux->rcu, __prog_put_common);
 530 }
 531
 532 void bpf_prog_put(struct bpf_prog *prog)
 533 {
 534         if (atomic_dec_and_test(&prog->aux->refcnt))
 535                 __prog_put_common(&prog->aux->rcu);
 536 }
 537 EXPORT_SYMBOL_GPL(bpf_prog_put);
 538
 539 static int bpf_prog_release(struct inode *inode, struct file *filp)
 540 {
 541         struct bpf_prog *prog = filp->private_data;
 542
 543         bpf_prog_put_rcu(prog);
 544         return 0;
 545 }
 546
 547 static const struct file_operations bpf_prog_fops = {
 548         .release = bpf_prog_release,
 549 };
 550
 551 int bpf_prog_new_fd(struct bpf_prog *prog)
 552 {
 553         return anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog,
 554                                 O_RDWR | O_CLOEXEC);
 555 }
 556
 557 static struct bpf_prog *__bpf_prog_get(struct fd f)
 558 {
 559         if (!f.file)
 560                 return ERR_PTR(-EBADF);
 561         if (f.file->f_op != &bpf_prog_fops) {
 562                 fdput(f);
 563                 return ERR_PTR(-EINVAL);
 564         }
 565
 566         return f.file->private_data;
 567 }
 568
 569 /* called by sockets/tracing/seccomp before attaching program to an event
 570  * pairs with bpf_prog_put()
 571  */
 572 struct bpf_prog *bpf_prog_get(u32 ufd)
 573 {
 574         struct fd f = fdget(ufd);
 575         struct bpf_prog *prog;
 576
 577         prog = __bpf_prog_get(f);
 578         if (IS_ERR(prog))
 579                 return prog;
 580
 581         atomic_inc(&prog->aux->refcnt);
 582         fdput(f);
 583
 584         return prog;
 585 }
 586 EXPORT_SYMBOL_GPL(bpf_prog_get);
 587
 588 /* last field in 'union bpf_attr' used by this command */
 589 #define BPF_PROG_LOAD_LAST_FIELD kern_version
 590
 591 static int bpf_prog_load(union bpf_attr *attr)
 592 {
 593         enum bpf_prog_type type = attr->prog_type;
 594         struct bpf_prog *prog;
 595         int err;
 596         char license[128];
 597         bool is_gpl;
 598
 599         if (CHECK_ATTR(BPF_PROG_LOAD))
 600                 return -EINVAL;
 601
 602         /* copy eBPF program license from user space */
 603         if (strncpy_from_user(license, u64_to_ptr(attr->license),
 604                               sizeof(license) - 1) < 0)
 605                 return -EFAULT;
 606         license[sizeof(license) - 1] = 0;
 607
 608         /* eBPF programs must be GPL compatible to use GPL-ed functions */
 609         is_gpl = license_is_gpl_compatible(license);
 610
 611         if (attr->insn_cnt >= BPF_MAXINSNS)
 612                 return -EINVAL;
 613
 614         if (type == BPF_PROG_TYPE_KPROBE &&
 615             attr->kern_version != LINUX_VERSION_CODE)
 616                 return -EINVAL;
 617
 618         if (type != BPF_PROG_TYPE_SOCKET_FILTER && !capable(CAP_SYS_ADMIN))
 619                 return -EPERM;
 620
 621         /* plain bpf_prog allocation */
 622         prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER);
 623         if (!prog)
 624                 return -ENOMEM;
 625
 626         err = bpf_prog_charge_memlock(prog);
 627         if (err)
 628                 goto free_prog_nouncharge;
 629
 630         prog->len = attr->insn_cnt;
 631
 632         err = -EFAULT;
 633         if (copy_from_user(prog->insns, u64_to_ptr(attr->insns),
 634                            prog->len * sizeof(struct bpf_insn)) != 0)
 635                 goto free_prog;
 636
 637         prog->orig_prog = NULL;
 638         prog->jited = 0;
 639
 640         atomic_set(&prog->aux->refcnt, 1);
 641         prog->gpl_compatible = is_gpl ? 1 : 0;
 642
 643         /* find program type: socket_filter vs tracing_filter */
 644         err = find_prog_type(type, prog);
 645         if (err < 0)
 646                 goto free_prog;
 647
 648         /* run eBPF verifier */
 649         err = bpf_check(&prog, attr);
 650         if (err < 0)
 651                 goto free_used_maps;
 652
 653         /* fixup BPF_CALL->imm field */
 654         fixup_bpf_calls(prog);
 655
 656         /* eBPF program is ready to be JITed */
 657         err = bpf_prog_select_runtime(prog);
 658         if (err < 0)
 659                 goto free_used_maps;
 660
 661         err = bpf_prog_new_fd(prog);
 662         if (err < 0)
 663                 /* failed to allocate fd */
 664                 goto free_used_maps;
 665
 666         return err;
 667
 668 free_used_maps:
 669         free_used_maps(prog->aux);
 670 free_prog:
 671         bpf_prog_uncharge_memlock(prog);
 672 free_prog_nouncharge:
 673         bpf_prog_free(prog);
 674         return err;
 675 }
 676
 677 #define BPF_OBJ_LAST_FIELD bpf_fd
 678
 679 static int bpf_obj_pin(const union bpf_attr *attr)
 680 {
 681         if (CHECK_ATTR(BPF_OBJ))
 682                 return -EINVAL;
 683
 684         return bpf_obj_pin_user(attr->bpf_fd, u64_to_ptr(attr->pathname));
 685 }
 686
 687 static int bpf_obj_get(const union bpf_attr *attr)
 688 {
 689         if (CHECK_ATTR(BPF_OBJ) || attr->bpf_fd != 0)
 690                 return -EINVAL;
 691
 692         return bpf_obj_get_user(u64_to_ptr(attr->pathname));
 693 }
 694
 695 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 696 {
 697         union bpf_attr attr = {};
 698         int err;
 699
 700         if (!capable(CAP_SYS_ADMIN) && sysctl_unprivileged_bpf_disabled)
 701                 return -EPERM;
 702
 703         if (!access_ok(VERIFY_READ, uattr, 1))
 704                 return -EFAULT;
 705
 706         if (size > PAGE_SIZE)   /* silly large */
 707                 return -E2BIG;
 708
 709         /* If we're handed a bigger struct than we know of,
 710          * ensure all the unknown bits are 0 - i.e. new
 711          * user-space does not rely on any kernel feature
 712          * extensions we dont know about yet.
 713          */
 714         if (size > sizeof(attr)) {
 715                 unsigned char __user *addr;
 716                 unsigned char __user *end;
 717                 unsigned char val;
 718
 719                 addr = (void __user *)uattr + sizeof(attr);
 720                 end  = (void __user *)uattr + size;
 721
 722                 for (; addr < end; addr++) {
 723                         err = get_user(val, addr);
 724                         if (err)
 725                                 return err;
 726                         if (val)
 727                                 return -E2BIG;
 728                 }
 729                 size = sizeof(attr);
 730         }
 731
 732         /* copy attributes from user space, may be less than sizeof(bpf_attr) */
 733         if (copy_from_user(&attr, uattr, size) != 0)
 734                 return -EFAULT;
 735
 736         switch (cmd) {
 737         case BPF_MAP_CREATE:
 738                 err = map_create(&attr);
 739                 break;
 740         case BPF_MAP_LOOKUP_ELEM:
 741                 err = map_lookup_elem(&attr);
 742                 break;
 743         case BPF_MAP_UPDATE_ELEM:
 744                 err = map_update_elem(&attr);
 745                 break;
 746         case BPF_MAP_DELETE_ELEM:
 747                 err = map_delete_elem(&attr);
 748                 break;
 749         case BPF_MAP_GET_NEXT_KEY:
 750                 err = map_get_next_key(&attr);
 751                 break;
 752         case BPF_PROG_LOAD:
 753                 err = bpf_prog_load(&attr);
 754                 break;
 755         case BPF_OBJ_PIN:
 756                 err = bpf_obj_pin(&attr);
 757                 break;
 758         case BPF_OBJ_GET:
 759                 err = bpf_obj_get(&attr);
 760                 break;
 761         default:
 762                 err = -EINVAL;
 763                 break;
 764         }
 765
 766         return err;
 767 }