1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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.
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.
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>
21 static LIST_HEAD(bpf_map_types);
23 static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
25 struct bpf_map_type_list *tl;
28 list_for_each_entry(tl, &bpf_map_types, list_node) {
29 if (tl->type == attr->map_type) {
30 map = tl->ops->map_alloc(attr);
34 map->map_type = attr->map_type;
38 return ERR_PTR(-EINVAL);
41 /* boot time registration of different map implementations */
42 void bpf_register_map_type(struct bpf_map_type_list *tl)
44 list_add(&tl->list_node, &bpf_map_types);
47 /* called from workqueue */
48 static void bpf_map_free_deferred(struct work_struct *work)
50 struct bpf_map *map = container_of(work, struct bpf_map, work);
52 /* implementation dependent freeing */
53 map->ops->map_free(map);
56 /* decrement map refcnt and schedule it for freeing via workqueue
57 * (unrelying map implementation ops->map_free() might sleep)
59 void bpf_map_put(struct bpf_map *map)
61 if (atomic_dec_and_test(&map->refcnt)) {
62 INIT_WORK(&map->work, bpf_map_free_deferred);
63 schedule_work(&map->work);
67 static int bpf_map_release(struct inode *inode, struct file *filp)
69 struct bpf_map *map = filp->private_data;
75 static const struct file_operations bpf_map_fops = {
76 .release = bpf_map_release,
79 /* helper macro to check that unused fields 'union bpf_attr' are zero */
80 #define CHECK_ATTR(CMD) \
81 memchr_inv((void *) &attr->CMD##_LAST_FIELD + \
82 sizeof(attr->CMD##_LAST_FIELD), 0, \
84 offsetof(union bpf_attr, CMD##_LAST_FIELD) - \
85 sizeof(attr->CMD##_LAST_FIELD)) != NULL
87 #define BPF_MAP_CREATE_LAST_FIELD max_entries
88 /* called via syscall */
89 static int map_create(union bpf_attr *attr)
94 err = CHECK_ATTR(BPF_MAP_CREATE);
98 /* find map type and init map: hashtable vs rbtree vs bloom vs ... */
99 map = find_and_alloc_map(attr);
103 atomic_set(&map->refcnt, 1);
105 err = anon_inode_getfd("bpf-map", &bpf_map_fops, map, O_RDWR | O_CLOEXEC);
108 /* failed to allocate fd */
114 map->ops->map_free(map);
118 /* if error is returned, fd is released.
119 * On success caller should complete fd access with matching fdput()
121 struct bpf_map *bpf_map_get(struct fd f)
126 return ERR_PTR(-EBADF);
128 if (f.file->f_op != &bpf_map_fops) {
130 return ERR_PTR(-EINVAL);
133 map = f.file->private_data;
138 /* helper to convert user pointers passed inside __aligned_u64 fields */
139 static void __user *u64_to_ptr(__u64 val)
141 return (void __user *) (unsigned long) val;
144 /* last field in 'union bpf_attr' used by this command */
145 #define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
147 static int map_lookup_elem(union bpf_attr *attr)
149 void __user *ukey = u64_to_ptr(attr->key);
150 void __user *uvalue = u64_to_ptr(attr->value);
151 int ufd = attr->map_fd;
152 struct fd f = fdget(ufd);
154 void *key, *value, *ptr;
157 if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
160 map = bpf_map_get(f);
165 key = kmalloc(map->key_size, GFP_USER);
170 if (copy_from_user(key, ukey, map->key_size) != 0)
174 value = kmalloc(map->value_size, GFP_USER);
179 ptr = map->ops->map_lookup_elem(map, key);
181 memcpy(value, ptr, map->value_size);
189 if (copy_to_user(uvalue, value, map->value_size) != 0)
203 #define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags
205 static int map_update_elem(union bpf_attr *attr)
207 void __user *ukey = u64_to_ptr(attr->key);
208 void __user *uvalue = u64_to_ptr(attr->value);
209 int ufd = attr->map_fd;
210 struct fd f = fdget(ufd);
215 if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
218 map = bpf_map_get(f);
223 key = kmalloc(map->key_size, GFP_USER);
228 if (copy_from_user(key, ukey, map->key_size) != 0)
232 value = kmalloc(map->value_size, GFP_USER);
237 if (copy_from_user(value, uvalue, map->value_size) != 0)
240 /* eBPF program that use maps are running under rcu_read_lock(),
241 * therefore all map accessors rely on this fact, so do the same here
244 err = map->ops->map_update_elem(map, key, value, attr->flags);
256 #define BPF_MAP_DELETE_ELEM_LAST_FIELD key
258 static int map_delete_elem(union bpf_attr *attr)
260 void __user *ukey = u64_to_ptr(attr->key);
261 int ufd = attr->map_fd;
262 struct fd f = fdget(ufd);
267 if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
270 map = bpf_map_get(f);
275 key = kmalloc(map->key_size, GFP_USER);
280 if (copy_from_user(key, ukey, map->key_size) != 0)
284 err = map->ops->map_delete_elem(map, key);
294 /* last field in 'union bpf_attr' used by this command */
295 #define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key
297 static int map_get_next_key(union bpf_attr *attr)
299 void __user *ukey = u64_to_ptr(attr->key);
300 void __user *unext_key = u64_to_ptr(attr->next_key);
301 int ufd = attr->map_fd;
302 struct fd f = fdget(ufd);
304 void *key, *next_key;
307 if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
310 map = bpf_map_get(f);
315 key = kmalloc(map->key_size, GFP_USER);
320 if (copy_from_user(key, ukey, map->key_size) != 0)
324 next_key = kmalloc(map->key_size, GFP_USER);
329 err = map->ops->map_get_next_key(map, key, next_key);
335 if (copy_to_user(unext_key, next_key, map->key_size) != 0)
349 static LIST_HEAD(bpf_prog_types);
351 static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
353 struct bpf_prog_type_list *tl;
355 list_for_each_entry(tl, &bpf_prog_types, list_node) {
356 if (tl->type == type) {
357 prog->aux->ops = tl->ops;
366 void bpf_register_prog_type(struct bpf_prog_type_list *tl)
368 list_add(&tl->list_node, &bpf_prog_types);
371 /* fixup insn->imm field of bpf_call instructions:
372 * if (insn->imm == BPF_FUNC_map_lookup_elem)
373 * insn->imm = bpf_map_lookup_elem - __bpf_call_base;
374 * else if (insn->imm == BPF_FUNC_map_update_elem)
375 * insn->imm = bpf_map_update_elem - __bpf_call_base;
378 * this function is called after eBPF program passed verification
380 static void fixup_bpf_calls(struct bpf_prog *prog)
382 const struct bpf_func_proto *fn;
385 for (i = 0; i < prog->len; i++) {
386 struct bpf_insn *insn = &prog->insnsi[i];
388 if (insn->code == (BPF_JMP | BPF_CALL)) {
389 /* we reach here when program has bpf_call instructions
390 * and it passed bpf_check(), means that
391 * ops->get_func_proto must have been supplied, check it
393 BUG_ON(!prog->aux->ops->get_func_proto);
395 fn = prog->aux->ops->get_func_proto(insn->imm);
396 /* all functions that have prototype and verifier allowed
397 * programs to call them, must be real in-kernel functions
400 insn->imm = fn->func - __bpf_call_base;
405 /* drop refcnt on maps used by eBPF program and free auxilary data */
406 static void free_used_maps(struct bpf_prog_aux *aux)
410 for (i = 0; i < aux->used_map_cnt; i++)
411 bpf_map_put(aux->used_maps[i]);
413 kfree(aux->used_maps);
416 void bpf_prog_put(struct bpf_prog *prog)
418 if (atomic_dec_and_test(&prog->aux->refcnt)) {
419 free_used_maps(prog->aux);
423 EXPORT_SYMBOL_GPL(bpf_prog_put);
425 static int bpf_prog_release(struct inode *inode, struct file *filp)
427 struct bpf_prog *prog = filp->private_data;
433 static const struct file_operations bpf_prog_fops = {
434 .release = bpf_prog_release,
437 static struct bpf_prog *get_prog(struct fd f)
439 struct bpf_prog *prog;
442 return ERR_PTR(-EBADF);
444 if (f.file->f_op != &bpf_prog_fops) {
446 return ERR_PTR(-EINVAL);
449 prog = f.file->private_data;
454 /* called by sockets/tracing/seccomp before attaching program to an event
455 * pairs with bpf_prog_put()
457 struct bpf_prog *bpf_prog_get(u32 ufd)
459 struct fd f = fdget(ufd);
460 struct bpf_prog *prog;
467 atomic_inc(&prog->aux->refcnt);
471 EXPORT_SYMBOL_GPL(bpf_prog_get);
473 /* last field in 'union bpf_attr' used by this command */
474 #define BPF_PROG_LOAD_LAST_FIELD kern_version
476 static int bpf_prog_load(union bpf_attr *attr)
478 enum bpf_prog_type type = attr->prog_type;
479 struct bpf_prog *prog;
484 if (CHECK_ATTR(BPF_PROG_LOAD))
487 /* copy eBPF program license from user space */
488 if (strncpy_from_user(license, u64_to_ptr(attr->license),
489 sizeof(license) - 1) < 0)
491 license[sizeof(license) - 1] = 0;
493 /* eBPF programs must be GPL compatible to use GPL-ed functions */
494 is_gpl = license_is_gpl_compatible(license);
496 if (attr->insn_cnt >= BPF_MAXINSNS)
499 if (type == BPF_PROG_TYPE_KPROBE &&
500 attr->kern_version != LINUX_VERSION_CODE)
503 /* plain bpf_prog allocation */
504 prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER);
508 prog->len = attr->insn_cnt;
511 if (copy_from_user(prog->insns, u64_to_ptr(attr->insns),
512 prog->len * sizeof(struct bpf_insn)) != 0)
515 prog->orig_prog = NULL;
518 atomic_set(&prog->aux->refcnt, 1);
519 prog->gpl_compatible = is_gpl;
521 /* find program type: socket_filter vs tracing_filter */
522 err = find_prog_type(type, prog);
526 /* run eBPF verifier */
527 err = bpf_check(&prog, attr);
531 /* fixup BPF_CALL->imm field */
532 fixup_bpf_calls(prog);
534 /* eBPF program is ready to be JITed */
535 bpf_prog_select_runtime(prog);
537 err = anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog, O_RDWR | O_CLOEXEC);
539 /* failed to allocate fd */
545 free_used_maps(prog->aux);
551 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
553 union bpf_attr attr = {};
556 /* the syscall is limited to root temporarily. This restriction will be
557 * lifted when security audit is clean. Note that eBPF+tracing must have
558 * this restriction, since it may pass kernel data to user space
560 if (!capable(CAP_SYS_ADMIN))
563 if (!access_ok(VERIFY_READ, uattr, 1))
566 if (size > PAGE_SIZE) /* silly large */
569 /* If we're handed a bigger struct than we know of,
570 * ensure all the unknown bits are 0 - i.e. new
571 * user-space does not rely on any kernel feature
572 * extensions we dont know about yet.
574 if (size > sizeof(attr)) {
575 unsigned char __user *addr;
576 unsigned char __user *end;
579 addr = (void __user *)uattr + sizeof(attr);
580 end = (void __user *)uattr + size;
582 for (; addr < end; addr++) {
583 err = get_user(val, addr);
592 /* copy attributes from user space, may be less than sizeof(bpf_attr) */
593 if (copy_from_user(&attr, uattr, size) != 0)
598 err = map_create(&attr);
600 case BPF_MAP_LOOKUP_ELEM:
601 err = map_lookup_elem(&attr);
603 case BPF_MAP_UPDATE_ELEM:
604 err = map_update_elem(&attr);
606 case BPF_MAP_DELETE_ELEM:
607 err = map_delete_elem(&attr);
609 case BPF_MAP_GET_NEXT_KEY:
610 err = map_get_next_key(&attr);
613 err = bpf_prog_load(&attr);