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>
20 static LIST_HEAD(bpf_map_types);
22 static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
24 struct bpf_map_type_list *tl;
27 list_for_each_entry(tl, &bpf_map_types, list_node) {
28 if (tl->type == attr->map_type) {
29 map = tl->ops->map_alloc(attr);
33 map->map_type = attr->map_type;
37 return ERR_PTR(-EINVAL);
40 /* boot time registration of different map implementations */
41 void bpf_register_map_type(struct bpf_map_type_list *tl)
43 list_add(&tl->list_node, &bpf_map_types);
46 /* called from workqueue */
47 static void bpf_map_free_deferred(struct work_struct *work)
49 struct bpf_map *map = container_of(work, struct bpf_map, work);
51 /* implementation dependent freeing */
52 map->ops->map_free(map);
55 /* decrement map refcnt and schedule it for freeing via workqueue
56 * (unrelying map implementation ops->map_free() might sleep)
58 void bpf_map_put(struct bpf_map *map)
60 if (atomic_dec_and_test(&map->refcnt)) {
61 INIT_WORK(&map->work, bpf_map_free_deferred);
62 schedule_work(&map->work);
66 static int bpf_map_release(struct inode *inode, struct file *filp)
68 struct bpf_map *map = filp->private_data;
74 static const struct file_operations bpf_map_fops = {
75 .release = bpf_map_release,
78 /* helper macro to check that unused fields 'union bpf_attr' are zero */
79 #define CHECK_ATTR(CMD) \
80 memchr_inv((void *) &attr->CMD##_LAST_FIELD + \
81 sizeof(attr->CMD##_LAST_FIELD), 0, \
83 offsetof(union bpf_attr, CMD##_LAST_FIELD) - \
84 sizeof(attr->CMD##_LAST_FIELD)) != NULL
86 #define BPF_MAP_CREATE_LAST_FIELD max_entries
87 /* called via syscall */
88 static int map_create(union bpf_attr *attr)
93 err = CHECK_ATTR(BPF_MAP_CREATE);
97 /* find map type and init map: hashtable vs rbtree vs bloom vs ... */
98 map = find_and_alloc_map(attr);
102 atomic_set(&map->refcnt, 1);
104 err = anon_inode_getfd("bpf-map", &bpf_map_fops, map, O_RDWR | O_CLOEXEC);
107 /* failed to allocate fd */
113 map->ops->map_free(map);
117 /* if error is returned, fd is released.
118 * On success caller should complete fd access with matching fdput()
120 struct bpf_map *bpf_map_get(struct fd f)
125 return ERR_PTR(-EBADF);
127 if (f.file->f_op != &bpf_map_fops) {
129 return ERR_PTR(-EINVAL);
132 map = f.file->private_data;
137 /* helper to convert user pointers passed inside __aligned_u64 fields */
138 static void __user *u64_to_ptr(__u64 val)
140 return (void __user *) (unsigned long) val;
143 /* last field in 'union bpf_attr' used by this command */
144 #define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
146 static int map_lookup_elem(union bpf_attr *attr)
148 void __user *ukey = u64_to_ptr(attr->key);
149 void __user *uvalue = u64_to_ptr(attr->value);
150 int ufd = attr->map_fd;
151 struct fd f = fdget(ufd);
156 if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
159 map = bpf_map_get(f);
164 key = kmalloc(map->key_size, GFP_USER);
169 if (copy_from_user(key, ukey, map->key_size) != 0)
174 value = map->ops->map_lookup_elem(map, key);
179 if (copy_to_user(uvalue, value, map->value_size) != 0)
193 #define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags
195 static int map_update_elem(union bpf_attr *attr)
197 void __user *ukey = u64_to_ptr(attr->key);
198 void __user *uvalue = u64_to_ptr(attr->value);
199 int ufd = attr->map_fd;
200 struct fd f = fdget(ufd);
205 if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
208 map = bpf_map_get(f);
213 key = kmalloc(map->key_size, GFP_USER);
218 if (copy_from_user(key, ukey, map->key_size) != 0)
222 value = kmalloc(map->value_size, GFP_USER);
227 if (copy_from_user(value, uvalue, map->value_size) != 0)
230 /* eBPF program that use maps are running under rcu_read_lock(),
231 * therefore all map accessors rely on this fact, so do the same here
234 err = map->ops->map_update_elem(map, key, value, attr->flags);
246 #define BPF_MAP_DELETE_ELEM_LAST_FIELD key
248 static int map_delete_elem(union bpf_attr *attr)
250 void __user *ukey = u64_to_ptr(attr->key);
251 int ufd = attr->map_fd;
252 struct fd f = fdget(ufd);
257 if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
260 map = bpf_map_get(f);
265 key = kmalloc(map->key_size, GFP_USER);
270 if (copy_from_user(key, ukey, map->key_size) != 0)
274 err = map->ops->map_delete_elem(map, key);
284 /* last field in 'union bpf_attr' used by this command */
285 #define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key
287 static int map_get_next_key(union bpf_attr *attr)
289 void __user *ukey = u64_to_ptr(attr->key);
290 void __user *unext_key = u64_to_ptr(attr->next_key);
291 int ufd = attr->map_fd;
292 struct fd f = fdget(ufd);
294 void *key, *next_key;
297 if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
300 map = bpf_map_get(f);
305 key = kmalloc(map->key_size, GFP_USER);
310 if (copy_from_user(key, ukey, map->key_size) != 0)
314 next_key = kmalloc(map->key_size, GFP_USER);
319 err = map->ops->map_get_next_key(map, key, next_key);
325 if (copy_to_user(unext_key, next_key, map->key_size) != 0)
339 static LIST_HEAD(bpf_prog_types);
341 static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
343 struct bpf_prog_type_list *tl;
345 list_for_each_entry(tl, &bpf_prog_types, list_node) {
346 if (tl->type == type) {
347 prog->aux->ops = tl->ops;
348 prog->aux->prog_type = type;
355 void bpf_register_prog_type(struct bpf_prog_type_list *tl)
357 list_add(&tl->list_node, &bpf_prog_types);
360 /* fixup insn->imm field of bpf_call instructions:
361 * if (insn->imm == BPF_FUNC_map_lookup_elem)
362 * insn->imm = bpf_map_lookup_elem - __bpf_call_base;
363 * else if (insn->imm == BPF_FUNC_map_update_elem)
364 * insn->imm = bpf_map_update_elem - __bpf_call_base;
367 * this function is called after eBPF program passed verification
369 static void fixup_bpf_calls(struct bpf_prog *prog)
371 const struct bpf_func_proto *fn;
374 for (i = 0; i < prog->len; i++) {
375 struct bpf_insn *insn = &prog->insnsi[i];
377 if (insn->code == (BPF_JMP | BPF_CALL)) {
378 /* we reach here when program has bpf_call instructions
379 * and it passed bpf_check(), means that
380 * ops->get_func_proto must have been supplied, check it
382 BUG_ON(!prog->aux->ops->get_func_proto);
384 fn = prog->aux->ops->get_func_proto(insn->imm);
385 /* all functions that have prototype and verifier allowed
386 * programs to call them, must be real in-kernel functions
389 insn->imm = fn->func - __bpf_call_base;
394 /* drop refcnt on maps used by eBPF program and free auxilary data */
395 static void free_used_maps(struct bpf_prog_aux *aux)
399 for (i = 0; i < aux->used_map_cnt; i++)
400 bpf_map_put(aux->used_maps[i]);
402 kfree(aux->used_maps);
405 void bpf_prog_put(struct bpf_prog *prog)
407 if (atomic_dec_and_test(&prog->aux->refcnt)) {
408 free_used_maps(prog->aux);
413 static int bpf_prog_release(struct inode *inode, struct file *filp)
415 struct bpf_prog *prog = filp->private_data;
421 static const struct file_operations bpf_prog_fops = {
422 .release = bpf_prog_release,
425 static struct bpf_prog *get_prog(struct fd f)
427 struct bpf_prog *prog;
430 return ERR_PTR(-EBADF);
432 if (f.file->f_op != &bpf_prog_fops) {
434 return ERR_PTR(-EINVAL);
437 prog = f.file->private_data;
442 /* called by sockets/tracing/seccomp before attaching program to an event
443 * pairs with bpf_prog_put()
445 struct bpf_prog *bpf_prog_get(u32 ufd)
447 struct fd f = fdget(ufd);
448 struct bpf_prog *prog;
455 atomic_inc(&prog->aux->refcnt);
460 /* last field in 'union bpf_attr' used by this command */
461 #define BPF_PROG_LOAD_LAST_FIELD log_buf
463 static int bpf_prog_load(union bpf_attr *attr)
465 enum bpf_prog_type type = attr->prog_type;
466 struct bpf_prog *prog;
471 if (CHECK_ATTR(BPF_PROG_LOAD))
474 /* copy eBPF program license from user space */
475 if (strncpy_from_user(license, u64_to_ptr(attr->license),
476 sizeof(license) - 1) < 0)
478 license[sizeof(license) - 1] = 0;
480 /* eBPF programs must be GPL compatible to use GPL-ed functions */
481 is_gpl = license_is_gpl_compatible(license);
483 if (attr->insn_cnt >= BPF_MAXINSNS)
486 /* plain bpf_prog allocation */
487 prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER);
491 prog->len = attr->insn_cnt;
494 if (copy_from_user(prog->insns, u64_to_ptr(attr->insns),
495 prog->len * sizeof(struct bpf_insn)) != 0)
498 prog->orig_prog = NULL;
501 atomic_set(&prog->aux->refcnt, 1);
502 prog->aux->is_gpl_compatible = is_gpl;
504 /* find program type: socket_filter vs tracing_filter */
505 err = find_prog_type(type, prog);
509 /* run eBPF verifier */
510 err = bpf_check(prog, attr);
515 /* fixup BPF_CALL->imm field */
516 fixup_bpf_calls(prog);
518 /* eBPF program is ready to be JITed */
519 bpf_prog_select_runtime(prog);
521 err = anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog, O_RDWR | O_CLOEXEC);
524 /* failed to allocate fd */
530 free_used_maps(prog->aux);
536 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
538 union bpf_attr attr = {};
541 /* the syscall is limited to root temporarily. This restriction will be
542 * lifted when security audit is clean. Note that eBPF+tracing must have
543 * this restriction, since it may pass kernel data to user space
545 if (!capable(CAP_SYS_ADMIN))
548 if (!access_ok(VERIFY_READ, uattr, 1))
551 if (size > PAGE_SIZE) /* silly large */
554 /* If we're handed a bigger struct than we know of,
555 * ensure all the unknown bits are 0 - i.e. new
556 * user-space does not rely on any kernel feature
557 * extensions we dont know about yet.
559 if (size > sizeof(attr)) {
560 unsigned char __user *addr;
561 unsigned char __user *end;
564 addr = (void __user *)uattr + sizeof(attr);
565 end = (void __user *)uattr + size;
567 for (; addr < end; addr++) {
568 err = get_user(val, addr);
577 /* copy attributes from user space, may be less than sizeof(bpf_attr) */
578 if (copy_from_user(&attr, uattr, size) != 0)
583 err = map_create(&attr);
585 case BPF_MAP_LOOKUP_ELEM:
586 err = map_lookup_elem(&attr);
588 case BPF_MAP_UPDATE_ELEM:
589 err = map_update_elem(&attr);
591 case BPF_MAP_DELETE_ELEM:
592 err = map_delete_elem(&attr);
594 case BPF_MAP_GET_NEXT_KEY:
595 err = map_get_next_key(&attr);
598 err = bpf_prog_load(&attr);