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 DEFINE_PER_CPU(int, bpf_prog_active);
  22
  23 int sysctl_unprivileged_bpf_disabled __read_mostly;
  24
  25 static LIST_HEAD(bpf_map_types);
  26
  27 static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
  28 {
  29         struct bpf_map_type_list *tl;
  30         struct bpf_map *map;
  31
  32         list_for_each_entry(tl, &bpf_map_types, list_node) {
  33                 if (tl->type == attr->map_type) {
  34                         map = tl->ops->map_alloc(attr);
  35                         if (IS_ERR(map))
  36                                 return map;
  37                         map->ops = tl->ops;
  38                         map->map_type = attr->map_type;
  39                         return map;
  40                 }
  41         }
  42         return ERR_PTR(-EINVAL);
  43 }
  44
  45 /* boot time registration of different map implementations */
  46 void bpf_register_map_type(struct bpf_map_type_list *tl)
  47 {
  48         list_add(&tl->list_node, &bpf_map_types);
  49 }
  50
  51 int bpf_map_precharge_memlock(u32 pages)
  52 {
  53         struct user_struct *user = get_current_user();
  54         unsigned long memlock_limit, cur;
  55
  56         memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  57         cur = atomic_long_read(&user->locked_vm);
  58         free_uid(user);
  59         if (cur + pages > memlock_limit)
  60                 return -EPERM;
  61         return 0;
  62 }
  63
  64 static int bpf_map_charge_memlock(struct bpf_map *map)
  65 {
  66         struct user_struct *user = get_current_user();
  67         unsigned long memlock_limit;
  68
  69         memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  70
  71         atomic_long_add(map->pages, &user->locked_vm);
  72
  73         if (atomic_long_read(&user->locked_vm) > memlock_limit) {
  74                 atomic_long_sub(map->pages, &user->locked_vm);
  75                 free_uid(user);
  76                 return -EPERM;
  77         }
  78         map->user = user;
  79         return 0;
  80 }
  81
  82 static void bpf_map_uncharge_memlock(struct bpf_map *map)
  83 {
  84         struct user_struct *user = map->user;
  85
  86         atomic_long_sub(map->pages, &user->locked_vm);
  87         free_uid(user);
  88 }
  89
  90 /* called from workqueue */
  91 static void bpf_map_free_deferred(struct work_struct *work)
  92 {
  93         struct bpf_map *map = container_of(work, struct bpf_map, work);
  94
  95         bpf_map_uncharge_memlock(map);
  96         /* implementation dependent freeing */
  97         map->ops->map_free(map);
  98 }
  99
 100 static void bpf_map_put_uref(struct bpf_map *map)
 101 {
 102         if (atomic_dec_and_test(&map->usercnt)) {
 103                 if (map->map_type == BPF_MAP_TYPE_PROG_ARRAY)
 104                         bpf_fd_array_map_clear(map);
 105         }
 106 }
 107
 108 /* decrement map refcnt and schedule it for freeing via workqueue
 109  * (unrelying map implementation ops->map_free() might sleep)
 110  */
 111 void bpf_map_put(struct bpf_map *map)
 112 {
 113         if (atomic_dec_and_test(&map->refcnt)) {
 114                 INIT_WORK(&map->work, bpf_map_free_deferred);
 115                 schedule_work(&map->work);
 116         }
 117 }
 118
 119 void bpf_map_put_with_uref(struct bpf_map *map)
 120 {
 121         bpf_map_put_uref(map);
 122         bpf_map_put(map);
 123 }
 124
 125 static int bpf_map_release(struct inode *inode, struct file *filp)
 126 {
 127         bpf_map_put_with_uref(filp->private_data);
 128         return 0;
 129 }
 130
 131 #ifdef CONFIG_PROC_FS
 132 static void bpf_map_show_fdinfo(struct seq_file *m, struct file *filp)
 133 {
 134         const struct bpf_map *map = filp->private_data;
 135
 136         seq_printf(m,
 137                    "map_type:\t%u\n"
 138                    "key_size:\t%u\n"
 139                    "value_size:\t%u\n"
 140                    "max_entries:\t%u\n"
 141                    "map_flags:\t%#x\n",
 142                    map->map_type,
 143                    map->key_size,
 144                    map->value_size,
 145                    map->max_entries,
 146                    map->map_flags);
 147 }
 148 #endif
 149
 150 static const struct file_operations bpf_map_fops = {
 151 #ifdef CONFIG_PROC_FS
 152         .show_fdinfo    = bpf_map_show_fdinfo,
 153 #endif
 154         .release        = bpf_map_release,
 155 };
 156
 157 int bpf_map_new_fd(struct bpf_map *map)
 158 {
 159         return anon_inode_getfd("bpf-map", &bpf_map_fops, map,
 160                                 O_RDWR | O_CLOEXEC);
 161 }
 162
 163 /* helper macro to check that unused fields 'union bpf_attr' are zero */
 164 #define CHECK_ATTR(CMD) \
 165         memchr_inv((void *) &attr->CMD##_LAST_FIELD + \
 166                    sizeof(attr->CMD##_LAST_FIELD), 0, \
 167                    sizeof(*attr) - \
 168                    offsetof(union bpf_attr, CMD##_LAST_FIELD) - \
 169                    sizeof(attr->CMD##_LAST_FIELD)) != NULL
 170
 171 #define BPF_MAP_CREATE_LAST_FIELD map_flags
 172 /* called via syscall */
 173 static int map_create(union bpf_attr *attr)
 174 {
 175         struct bpf_map *map;
 176         int err;
 177
 178         err = CHECK_ATTR(BPF_MAP_CREATE);
 179         if (err)
 180                 return -EINVAL;
 181
 182         /* find map type and init map: hashtable vs rbtree vs bloom vs ... */
 183         map = find_and_alloc_map(attr);
 184         if (IS_ERR(map))
 185                 return PTR_ERR(map);
 186
 187         atomic_set(&map->refcnt, 1);
 188         atomic_set(&map->usercnt, 1);
 189
 190         err = bpf_map_charge_memlock(map);
 191         if (err)
 192                 goto free_map;
 193
 194         err = bpf_map_new_fd(map);
 195         if (err < 0)
 196                 /* failed to allocate fd */
 197                 goto free_map;
 198
 199         return err;
 200
 201 free_map:
 202         map->ops->map_free(map);
 203         return err;
 204 }
 205
 206 /* if error is returned, fd is released.
 207  * On success caller should complete fd access with matching fdput()
 208  */
 209 struct bpf_map *__bpf_map_get(struct fd f)
 210 {
 211         if (!f.file)
 212                 return ERR_PTR(-EBADF);
 213         if (f.file->f_op != &bpf_map_fops) {
 214                 fdput(f);
 215                 return ERR_PTR(-EINVAL);
 216         }
 217
 218         return f.file->private_data;
 219 }
 220
 221 /* prog's and map's refcnt limit */
 222 #define BPF_MAX_REFCNT 32768
 223
 224 struct bpf_map *bpf_map_inc(struct bpf_map *map, bool uref)
 225 {
 226         if (atomic_inc_return(&map->refcnt) > BPF_MAX_REFCNT) {
 227                 atomic_dec(&map->refcnt);
 228                 return ERR_PTR(-EBUSY);
 229         }
 230         if (uref)
 231                 atomic_inc(&map->usercnt);
 232         return map;
 233 }
 234
 235 struct bpf_map *bpf_map_get_with_uref(u32 ufd)
 236 {
 237         struct fd f = fdget(ufd);
 238         struct bpf_map *map;
 239
 240         map = __bpf_map_get(f);
 241         if (IS_ERR(map))
 242                 return map;
 243
 244         map = bpf_map_inc(map, true);
 245         fdput(f);
 246
 247         return map;
 248 }
 249
 250 /* helper to convert user pointers passed inside __aligned_u64 fields */
 251 static void __user *u64_to_ptr(__u64 val)
 252 {
 253         return (void __user *) (unsigned long) val;
 254 }
 255
 256 int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
 257 {
 258         return -ENOTSUPP;
 259 }
 260
 261 /* last field in 'union bpf_attr' used by this command */
 262 #define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
 263
 264 static int map_lookup_elem(union bpf_attr *attr)
 265 {
 266         void __user *ukey = u64_to_ptr(attr->key);
 267         void __user *uvalue = u64_to_ptr(attr->value);
 268         int ufd = attr->map_fd;
 269         struct bpf_map *map;
 270         void *key, *value, *ptr;
 271         u32 value_size;
 272         struct fd f;
 273         int err;
 274
 275         if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
 276                 return -EINVAL;
 277
 278         f = fdget(ufd);
 279         map = __bpf_map_get(f);
 280         if (IS_ERR(map))
 281                 return PTR_ERR(map);
 282
 283         err = -ENOMEM;
 284         key = kmalloc(map->key_size, GFP_USER);
 285         if (!key)
 286                 goto err_put;
 287
 288         err = -EFAULT;
 289         if (copy_from_user(key, ukey, map->key_size) != 0)
 290                 goto free_key;
 291
 292         if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 293             map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
 294                 value_size = round_up(map->value_size, 8) * num_possible_cpus();
 295         else
 296                 value_size = map->value_size;
 297
 298         err = -ENOMEM;
 299         value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
 300         if (!value)
 301                 goto free_key;
 302
 303         if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH) {
 304                 err = bpf_percpu_hash_copy(map, key, value);
 305         } else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
 306                 err = bpf_percpu_array_copy(map, key, value);
 307         } else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) {
 308                 err = bpf_stackmap_copy(map, key, value);
 309         } else {
 310                 rcu_read_lock();
 311                 ptr = map->ops->map_lookup_elem(map, key);
 312                 if (ptr)
 313                         memcpy(value, ptr, value_size);
 314                 rcu_read_unlock();
 315                 err = ptr ? 0 : -ENOENT;
 316         }
 317
 318         if (err)
 319                 goto free_value;
 320
 321         err = -EFAULT;
 322         if (copy_to_user(uvalue, value, value_size) != 0)
 323                 goto free_value;
 324
 325         err = 0;
 326
 327 free_value:
 328         kfree(value);
 329 free_key:
 330         kfree(key);
 331 err_put:
 332         fdput(f);
 333         return err;
 334 }
 335
 336 #define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags
 337
 338 static int map_update_elem(union bpf_attr *attr)
 339 {
 340         void __user *ukey = u64_to_ptr(attr->key);
 341         void __user *uvalue = u64_to_ptr(attr->value);
 342         int ufd = attr->map_fd;
 343         struct bpf_map *map;
 344         void *key, *value;
 345         u32 value_size;
 346         struct fd f;
 347         int err;
 348
 349         if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
 350                 return -EINVAL;
 351
 352         f = fdget(ufd);
 353         map = __bpf_map_get(f);
 354         if (IS_ERR(map))
 355                 return PTR_ERR(map);
 356
 357         err = -ENOMEM;
 358         key = kmalloc(map->key_size, GFP_USER);
 359         if (!key)
 360                 goto err_put;
 361
 362         err = -EFAULT;
 363         if (copy_from_user(key, ukey, map->key_size) != 0)
 364                 goto free_key;
 365
 366         if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 367             map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
 368                 value_size = round_up(map->value_size, 8) * num_possible_cpus();
 369         else
 370                 value_size = map->value_size;
 371
 372         err = -ENOMEM;
 373         value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
 374         if (!value)
 375                 goto free_key;
 376
 377         err = -EFAULT;
 378         if (copy_from_user(value, uvalue, value_size) != 0)
 379                 goto free_value;
 380
 381         /* must increment bpf_prog_active to avoid kprobe+bpf triggering from
 382          * inside bpf map update or delete otherwise deadlocks are possible
 383          */
 384         preempt_disable();
 385         __this_cpu_inc(bpf_prog_active);
 386         if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH) {
 387                 err = bpf_percpu_hash_update(map, key, value, attr->flags);
 388         } else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
 389                 err = bpf_percpu_array_update(map, key, value, attr->flags);
 390         } else {
 391                 rcu_read_lock();
 392                 err = map->ops->map_update_elem(map, key, value, attr->flags);
 393                 rcu_read_unlock();
 394         }
 395         __this_cpu_dec(bpf_prog_active);
 396         preempt_enable();
 397
 398 free_value:
 399         kfree(value);
 400 free_key:
 401         kfree(key);
 402 err_put:
 403         fdput(f);
 404         return err;
 405 }
 406
 407 #define BPF_MAP_DELETE_ELEM_LAST_FIELD key
 408
 409 static int map_delete_elem(union bpf_attr *attr)
 410 {
 411         void __user *ukey = u64_to_ptr(attr->key);
 412         int ufd = attr->map_fd;
 413         struct bpf_map *map;
 414         struct fd f;
 415         void *key;
 416         int err;
 417
 418         if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
 419                 return -EINVAL;
 420
 421         f = fdget(ufd);
 422         map = __bpf_map_get(f);
 423         if (IS_ERR(map))
 424                 return PTR_ERR(map);
 425
 426         err = -ENOMEM;
 427         key = kmalloc(map->key_size, GFP_USER);
 428         if (!key)
 429                 goto err_put;
 430
 431         err = -EFAULT;
 432         if (copy_from_user(key, ukey, map->key_size) != 0)
 433                 goto free_key;
 434
 435         preempt_disable();
 436         __this_cpu_inc(bpf_prog_active);
 437         rcu_read_lock();
 438         err = map->ops->map_delete_elem(map, key);
 439         rcu_read_unlock();
 440         __this_cpu_dec(bpf_prog_active);
 441         preempt_enable();
 442
 443 free_key:
 444         kfree(key);
 445 err_put:
 446         fdput(f);
 447         return err;
 448 }
 449
 450 /* last field in 'union bpf_attr' used by this command */
 451 #define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key
 452
 453 static int map_get_next_key(union bpf_attr *attr)
 454 {
 455         void __user *ukey = u64_to_ptr(attr->key);
 456         void __user *unext_key = u64_to_ptr(attr->next_key);
 457         int ufd = attr->map_fd;
 458         struct bpf_map *map;
 459         void *key, *next_key;
 460         struct fd f;
 461         int err;
 462
 463         if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
 464                 return -EINVAL;
 465
 466         f = fdget(ufd);
 467         map = __bpf_map_get(f);
 468         if (IS_ERR(map))
 469                 return PTR_ERR(map);
 470
 471         err = -ENOMEM;
 472         key = kmalloc(map->key_size, GFP_USER);
 473         if (!key)
 474                 goto err_put;
 475
 476         err = -EFAULT;
 477         if (copy_from_user(key, ukey, map->key_size) != 0)
 478                 goto free_key;
 479
 480         err = -ENOMEM;
 481         next_key = kmalloc(map->key_size, GFP_USER);
 482         if (!next_key)
 483                 goto free_key;
 484
 485         rcu_read_lock();
 486         err = map->ops->map_get_next_key(map, key, next_key);
 487         rcu_read_unlock();
 488         if (err)
 489                 goto free_next_key;
 490
 491         err = -EFAULT;
 492         if (copy_to_user(unext_key, next_key, map->key_size) != 0)
 493                 goto free_next_key;
 494
 495         err = 0;
 496
 497 free_next_key:
 498         kfree(next_key);
 499 free_key:
 500         kfree(key);
 501 err_put:
 502         fdput(f);
 503         return err;
 504 }
 505
 506 static LIST_HEAD(bpf_prog_types);
 507
 508 static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
 509 {
 510         struct bpf_prog_type_list *tl;
 511
 512         list_for_each_entry(tl, &bpf_prog_types, list_node) {
 513                 if (tl->type == type) {
 514                         prog->aux->ops = tl->ops;
 515                         prog->type = type;
 516                         return 0;
 517                 }
 518         }
 519
 520         return -EINVAL;
 521 }
 522
 523 void bpf_register_prog_type(struct bpf_prog_type_list *tl)
 524 {
 525         list_add(&tl->list_node, &bpf_prog_types);
 526 }
 527
 528 /* fixup insn->imm field of bpf_call instructions:
 529  * if (insn->imm == BPF_FUNC_map_lookup_elem)
 530  *      insn->imm = bpf_map_lookup_elem - __bpf_call_base;
 531  * else if (insn->imm == BPF_FUNC_map_update_elem)
 532  *      insn->imm = bpf_map_update_elem - __bpf_call_base;
 533  * else ...
 534  *
 535  * this function is called after eBPF program passed verification
 536  */
 537 static void fixup_bpf_calls(struct bpf_prog *prog)
 538 {
 539         const struct bpf_func_proto *fn;
 540         int i;
 541
 542         for (i = 0; i < prog->len; i++) {
 543                 struct bpf_insn *insn = &prog->insnsi[i];
 544
 545                 if (insn->code == (BPF_JMP | BPF_CALL)) {
 546                         /* we reach here when program has bpf_call instructions
 547                          * and it passed bpf_check(), means that
 548                          * ops->get_func_proto must have been supplied, check it
 549                          */
 550                         BUG_ON(!prog->aux->ops->get_func_proto);
 551
 552                         if (insn->imm == BPF_FUNC_get_route_realm)
 553                                 prog->dst_needed = 1;
 554                         if (insn->imm == BPF_FUNC_get_prandom_u32)
 555                                 bpf_user_rnd_init_once();
 556                         if (insn->imm == BPF_FUNC_tail_call) {
 557                                 /* mark bpf_tail_call as different opcode
 558                                  * to avoid conditional branch in
 559                                  * interpeter for every normal call
 560                                  * and to prevent accidental JITing by
 561                                  * JIT compiler that doesn't support
 562                                  * bpf_tail_call yet
 563                                  */
 564                                 insn->imm = 0;
 565                                 insn->code |= BPF_X;
 566                                 continue;
 567                         }
 568
 569                         fn = prog->aux->ops->get_func_proto(insn->imm);
 570                         /* all functions that have prototype and verifier allowed
 571                          * programs to call them, must be real in-kernel functions
 572                          */
 573                         BUG_ON(!fn->func);
 574                         insn->imm = fn->func - __bpf_call_base;
 575                 }
 576         }
 577 }
 578
 579 /* drop refcnt on maps used by eBPF program and free auxilary data */
 580 static void free_used_maps(struct bpf_prog_aux *aux)
 581 {
 582         int i;
 583
 584         for (i = 0; i < aux->used_map_cnt; i++)
 585                 bpf_map_put(aux->used_maps[i]);
 586
 587         kfree(aux->used_maps);
 588 }
 589
 590 static int bpf_prog_charge_memlock(struct bpf_prog *prog)
 591 {
 592         struct user_struct *user = get_current_user();
 593         unsigned long memlock_limit;
 594
 595         memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 596
 597         atomic_long_add(prog->pages, &user->locked_vm);
 598         if (atomic_long_read(&user->locked_vm) > memlock_limit) {
 599                 atomic_long_sub(prog->pages, &user->locked_vm);
 600                 free_uid(user);
 601                 return -EPERM;
 602         }
 603         prog->aux->user = user;
 604         return 0;
 605 }
 606
 607 static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
 608 {
 609         struct user_struct *user = prog->aux->user;
 610
 611         atomic_long_sub(prog->pages, &user->locked_vm);
 612         free_uid(user);
 613 }
 614
 615 static void __prog_put_common(struct rcu_head *rcu)
 616 {
 617         struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);
 618
 619         free_used_maps(aux);
 620         bpf_prog_uncharge_memlock(aux->prog);
 621         bpf_prog_free(aux->prog);
 622 }
 623
 624 /* version of bpf_prog_put() that is called after a grace period */
 625 void bpf_prog_put_rcu(struct bpf_prog *prog)
 626 {
 627         if (atomic_dec_and_test(&prog->aux->refcnt))
 628                 call_rcu(&prog->aux->rcu, __prog_put_common);
 629 }
 630
 631 void bpf_prog_put(struct bpf_prog *prog)
 632 {
 633         if (atomic_dec_and_test(&prog->aux->refcnt))
 634                 __prog_put_common(&prog->aux->rcu);
 635 }
 636 EXPORT_SYMBOL_GPL(bpf_prog_put);
 637
 638 static int bpf_prog_release(struct inode *inode, struct file *filp)
 639 {
 640         struct bpf_prog *prog = filp->private_data;
 641
 642         bpf_prog_put_rcu(prog);
 643         return 0;
 644 }
 645
 646 static const struct file_operations bpf_prog_fops = {
 647         .release = bpf_prog_release,
 648 };
 649
 650 int bpf_prog_new_fd(struct bpf_prog *prog)
 651 {
 652         return anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog,
 653                                 O_RDWR | O_CLOEXEC);
 654 }
 655
 656 static struct bpf_prog *__bpf_prog_get(struct fd f)
 657 {
 658         if (!f.file)
 659                 return ERR_PTR(-EBADF);
 660         if (f.file->f_op != &bpf_prog_fops) {
 661                 fdput(f);
 662                 return ERR_PTR(-EINVAL);
 663         }
 664
 665         return f.file->private_data;
 666 }
 667
 668 struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
 669 {
 670         if (atomic_inc_return(&prog->aux->refcnt) > BPF_MAX_REFCNT) {
 671                 atomic_dec(&prog->aux->refcnt);
 672                 return ERR_PTR(-EBUSY);
 673         }
 674         return prog;
 675 }
 676
 677 /* called by sockets/tracing/seccomp before attaching program to an event
 678  * pairs with bpf_prog_put()
 679  */
 680 struct bpf_prog *bpf_prog_get(u32 ufd)
 681 {
 682         struct fd f = fdget(ufd);
 683         struct bpf_prog *prog;
 684
 685         prog = __bpf_prog_get(f);
 686         if (IS_ERR(prog))
 687                 return prog;
 688
 689         prog = bpf_prog_inc(prog);
 690         fdput(f);
 691
 692         return prog;
 693 }
 694 EXPORT_SYMBOL_GPL(bpf_prog_get);
 695
 696 /* last field in 'union bpf_attr' used by this command */
 697 #define BPF_PROG_LOAD_LAST_FIELD kern_version
 698
 699 static int bpf_prog_load(union bpf_attr *attr)
 700 {
 701         enum bpf_prog_type type = attr->prog_type;
 702         struct bpf_prog *prog;
 703         int err;
 704         char license[128];
 705         bool is_gpl;
 706
 707         if (CHECK_ATTR(BPF_PROG_LOAD))
 708                 return -EINVAL;
 709
 710         /* copy eBPF program license from user space */
 711         if (strncpy_from_user(license, u64_to_ptr(attr->license),
 712                               sizeof(license) - 1) < 0)
 713                 return -EFAULT;
 714         license[sizeof(license) - 1] = 0;
 715
 716         /* eBPF programs must be GPL compatible to use GPL-ed functions */
 717         is_gpl = license_is_gpl_compatible(license);
 718
 719         if (attr->insn_cnt >= BPF_MAXINSNS)
 720                 return -EINVAL;
 721
 722         if (type == BPF_PROG_TYPE_KPROBE &&
 723             attr->kern_version != LINUX_VERSION_CODE)
 724                 return -EINVAL;
 725
 726         if (type != BPF_PROG_TYPE_SOCKET_FILTER && !capable(CAP_SYS_ADMIN))
 727                 return -EPERM;
 728
 729         /* plain bpf_prog allocation */
 730         prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER);
 731         if (!prog)
 732                 return -ENOMEM;
 733
 734         err = bpf_prog_charge_memlock(prog);
 735         if (err)
 736                 goto free_prog_nouncharge;
 737
 738         prog->len = attr->insn_cnt;
 739
 740         err = -EFAULT;
 741         if (copy_from_user(prog->insns, u64_to_ptr(attr->insns),
 742                            prog->len * sizeof(struct bpf_insn)) != 0)
 743                 goto free_prog;
 744
 745         prog->orig_prog = NULL;
 746         prog->jited = 0;
 747
 748         atomic_set(&prog->aux->refcnt, 1);
 749         prog->gpl_compatible = is_gpl ? 1 : 0;
 750
 751         /* find program type: socket_filter vs tracing_filter */
 752         err = find_prog_type(type, prog);
 753         if (err < 0)
 754                 goto free_prog;
 755
 756         /* run eBPF verifier */
 757         err = bpf_check(&prog, attr);
 758         if (err < 0)
 759                 goto free_used_maps;
 760
 761         /* fixup BPF_CALL->imm field */
 762         fixup_bpf_calls(prog);
 763
 764         /* eBPF program is ready to be JITed */
 765         err = bpf_prog_select_runtime(prog);
 766         if (err < 0)
 767                 goto free_used_maps;
 768
 769         err = bpf_prog_new_fd(prog);
 770         if (err < 0)
 771                 /* failed to allocate fd */
 772                 goto free_used_maps;
 773
 774         return err;
 775
 776 free_used_maps:
 777         free_used_maps(prog->aux);
 778 free_prog:
 779         bpf_prog_uncharge_memlock(prog);
 780 free_prog_nouncharge:
 781         bpf_prog_free(prog);
 782         return err;
 783 }
 784
 785 #define BPF_OBJ_LAST_FIELD bpf_fd
 786
 787 static int bpf_obj_pin(const union bpf_attr *attr)
 788 {
 789         if (CHECK_ATTR(BPF_OBJ))
 790                 return -EINVAL;
 791
 792         return bpf_obj_pin_user(attr->bpf_fd, u64_to_ptr(attr->pathname));
 793 }
 794
 795 static int bpf_obj_get(const union bpf_attr *attr)
 796 {
 797         if (CHECK_ATTR(BPF_OBJ) || attr->bpf_fd != 0)
 798                 return -EINVAL;
 799
 800         return bpf_obj_get_user(u64_to_ptr(attr->pathname));
 801 }
 802
 803 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 804 {
 805         union bpf_attr attr = {};
 806         int err;
 807
 808         if (!capable(CAP_SYS_ADMIN) && sysctl_unprivileged_bpf_disabled)
 809                 return -EPERM;
 810
 811         if (!access_ok(VERIFY_READ, uattr, 1))
 812                 return -EFAULT;
 813
 814         if (size > PAGE_SIZE)   /* silly large */
 815                 return -E2BIG;
 816
 817         /* If we're handed a bigger struct than we know of,
 818          * ensure all the unknown bits are 0 - i.e. new
 819          * user-space does not rely on any kernel feature
 820          * extensions we dont know about yet.
 821          */
 822         if (size > sizeof(attr)) {
 823                 unsigned char __user *addr;
 824                 unsigned char __user *end;
 825                 unsigned char val;
 826
 827                 addr = (void __user *)uattr + sizeof(attr);
 828                 end  = (void __user *)uattr + size;
 829
 830                 for (; addr < end; addr++) {
 831                         err = get_user(val, addr);
 832                         if (err)
 833                                 return err;
 834                         if (val)
 835                                 return -E2BIG;
 836                 }
 837                 size = sizeof(attr);
 838         }
 839
 840         /* copy attributes from user space, may be less than sizeof(bpf_attr) */
 841         if (copy_from_user(&attr, uattr, size) != 0)
 842                 return -EFAULT;
 843
 844         switch (cmd) {
 845         case BPF_MAP_CREATE:
 846                 err = map_create(&attr);
 847                 break;
 848         case BPF_MAP_LOOKUP_ELEM:
 849                 err = map_lookup_elem(&attr);
 850                 break;
 851         case BPF_MAP_UPDATE_ELEM:
 852                 err = map_update_elem(&attr);
 853                 break;
 854         case BPF_MAP_DELETE_ELEM:
 855                 err = map_delete_elem(&attr);
 856                 break;
 857         case BPF_MAP_GET_NEXT_KEY:
 858                 err = map_get_next_key(&attr);
 859                 break;
 860         case BPF_PROG_LOAD:
 861                 err = bpf_prog_load(&attr);
 862                 break;
 863         case BPF_OBJ_PIN:
 864                 err = bpf_obj_pin(&attr);
 865                 break;
 866         case BPF_OBJ_GET:
 867                 err = bpf_obj_get(&attr);
 868                 break;
 869         default:
 870                 err = -EINVAL;
 871                 break;
 872         }
 873
 874         return err;
 875 }