kernel/bpf/syscall.c - codeaurora/cp-linux - Gitiles

 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
  * License as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * General Public License for more details.
  */
 #include <linux/bpf.h>
 #include <linux/syscalls.h>
 #include <linux/slab.h>
 #include <linux/anon_inodes.h>
 #include <linux/file.h>
 #include <linux/license.h>
 #include <linux/filter.h>
 #include <linux/version.h>

 int sysctl_unprivileged_bpf_disabled __read_mostly;

 static LIST_HEAD(bpf_map_types);

 static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
 {
 	struct bpf_map_type_list *tl;
 	struct bpf_map *map;

 	list_for_each_entry(tl, &bpf_map_types, list_node) {
 		if (tl->type == attr->map_type) {
 			map = tl->ops->map_alloc(attr);
 			if (IS_ERR(map))
 				return map;
 			map->ops = tl->ops;
 			map->map_type = attr->map_type;
 			return map;
 		}
 	}
 	return ERR_PTR(-EINVAL);
 }

 /* boot time registration of different map implementations */
 void bpf_register_map_type(struct bpf_map_type_list *tl)
 {
 	list_add(&tl->list_node, &bpf_map_types);
 }

 static int bpf_map_charge_memlock(struct bpf_map *map)
 {
 	struct user_struct *user = get_current_user();
 	unsigned long memlock_limit;

 	memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

 	atomic_long_add(map->pages, &user->locked_vm);

 	if (atomic_long_read(&user->locked_vm) > memlock_limit) {
 		atomic_long_sub(map->pages, &user->locked_vm);
 		free_uid(user);
 		return -EPERM;
 	}
 	map->user = user;
 	return 0;
 }

 static void bpf_map_uncharge_memlock(struct bpf_map *map)
 {
 	struct user_struct *user = map->user;

 	atomic_long_sub(map->pages, &user->locked_vm);
 	free_uid(user);
 }

 /* called from workqueue */
 static void bpf_map_free_deferred(struct work_struct *work)
 {
 	struct bpf_map *map = container_of(work, struct bpf_map, work);

 	bpf_map_uncharge_memlock(map);
 	/* implementation dependent freeing */
 	map->ops->map_free(map);
 }

 static void bpf_map_put_uref(struct bpf_map *map)
 {
 	if (atomic_dec_and_test(&map->usercnt)) {
 		if (map->map_type == BPF_MAP_TYPE_PROG_ARRAY)
 			bpf_fd_array_map_clear(map);
 	}
 }

 /* decrement map refcnt and schedule it for freeing via workqueue
  * (unrelying map implementation ops->map_free() might sleep)
  */
 void bpf_map_put(struct bpf_map *map)
 {
 	if (atomic_dec_and_test(&map->refcnt)) {
 		INIT_WORK(&map->work, bpf_map_free_deferred);
 		schedule_work(&map->work);
 	}
 }

 void bpf_map_put_with_uref(struct bpf_map *map)
 {
 	bpf_map_put_uref(map);
 	bpf_map_put(map);
 }

 static int bpf_map_release(struct inode *inode, struct file *filp)
 {
 	bpf_map_put_with_uref(filp->private_data);
 	return 0;
 }

 static const struct file_operations bpf_map_fops = {
 	.release = bpf_map_release,
 };

 int bpf_map_new_fd(struct bpf_map *map)
 {
 	return anon_inode_getfd("bpf-map", &bpf_map_fops, map,
 				O_RDWR | O_CLOEXEC);
 }

 /* helper macro to check that unused fields 'union bpf_attr' are zero */
 #define CHECK_ATTR(CMD) \
 	memchr_inv((void *) &attr->CMD##_LAST_FIELD + \
 		   sizeof(attr->CMD##_LAST_FIELD), 0, \
 		   sizeof(*attr) - \
 		   offsetof(union bpf_attr, CMD##_LAST_FIELD) - \
 		   sizeof(attr->CMD##_LAST_FIELD)) != NULL

 #define BPF_MAP_CREATE_LAST_FIELD max_entries
 /* called via syscall */
 static int map_create(union bpf_attr *attr)
 {
 	struct bpf_map *map;
 	int err;

 	err = CHECK_ATTR(BPF_MAP_CREATE);
 	if (err)
 		return -EINVAL;

 	/* find map type and init map: hashtable vs rbtree vs bloom vs ... */
 	map = find_and_alloc_map(attr);
 	if (IS_ERR(map))
 		return PTR_ERR(map);

 	atomic_set(&map->refcnt, 1);
 	atomic_set(&map->usercnt, 1);

 	err = bpf_map_charge_memlock(map);
 	if (err)
 		goto free_map;

 	err = bpf_map_new_fd(map);
 	if (err < 0)
 		/* failed to allocate fd */
 		goto free_map;

 	return err;

 free_map:
 	map->ops->map_free(map);
 	return err;
 }

 /* if error is returned, fd is released.
  * On success caller should complete fd access with matching fdput()
  */
 struct bpf_map *__bpf_map_get(struct fd f)
 {
 	if (!f.file)
 		return ERR_PTR(-EBADF);
 	if (f.file->f_op != &bpf_map_fops) {
 		fdput(f);
 		return ERR_PTR(-EINVAL);
 	}

 	return f.file->private_data;
 }

 /* prog's and map's refcnt limit */
 #define BPF_MAX_REFCNT 32768

 struct bpf_map *bpf_map_inc(struct bpf_map *map, bool uref)
 {
 	if (atomic_inc_return(&map->refcnt) > BPF_MAX_REFCNT) {
 		atomic_dec(&map->refcnt);
 		return ERR_PTR(-EBUSY);
 	}
 	if (uref)
 		atomic_inc(&map->usercnt);
 	return map;
 }

 struct bpf_map *bpf_map_get_with_uref(u32 ufd)
 {
 	struct fd f = fdget(ufd);
 	struct bpf_map *map;

 	map = __bpf_map_get(f);
 	if (IS_ERR(map))
 		return map;

 	map = bpf_map_inc(map, true);
 	fdput(f);

 	return map;
 }

 /* helper to convert user pointers passed inside __aligned_u64 fields */
 static void __user *u64_to_ptr(__u64 val)
 {
 	return (void __user *) (unsigned long) val;
 }

 /* last field in 'union bpf_attr' used by this command */
 #define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value

 static int map_lookup_elem(union bpf_attr *attr)
 {
 	void __user *ukey = u64_to_ptr(attr->key);
 	void __user *uvalue = u64_to_ptr(attr->value);
 	int ufd = attr->map_fd;
 	struct bpf_map *map;
 	void *key, *value, *ptr;
 	struct fd f;
 	int err;

 	if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
 		return -EINVAL;

 	f = fdget(ufd);
 	map = __bpf_map_get(f);
 	if (IS_ERR(map))
 		return PTR_ERR(map);

 	err = -ENOMEM;
 	key = kmalloc(map->key_size, GFP_USER);
 	if (!key)
 		goto err_put;

 	err = -EFAULT;
 	if (copy_from_user(key, ukey, map->key_size) != 0)
 		goto free_key;

 	err = -ENOMEM;
 	value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN);
 	if (!value)
 		goto free_key;

 	rcu_read_lock();
 	ptr = map->ops->map_lookup_elem(map, key);
 	if (ptr)
 		memcpy(value, ptr, map->value_size);
 	rcu_read_unlock();

 	err = -ENOENT;
 	if (!ptr)
 		goto free_value;

 	err = -EFAULT;
 	if (copy_to_user(uvalue, value, map->value_size) != 0)
 		goto free_value;

 	err = 0;

 free_value:
 	kfree(value);
 free_key:
 	kfree(key);
 err_put:
 	fdput(f);
 	return err;
 }

 #define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags

 static int map_update_elem(union bpf_attr *attr)
 {
 	void __user *ukey = u64_to_ptr(attr->key);
 	void __user *uvalue = u64_to_ptr(attr->value);
 	int ufd = attr->map_fd;
 	struct bpf_map *map;
 	void *key, *value;
 	struct fd f;
 	int err;

 	if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
 		return -EINVAL;

 	f = fdget(ufd);
 	map = __bpf_map_get(f);
 	if (IS_ERR(map))
 		return PTR_ERR(map);

 	err = -ENOMEM;
 	key = kmalloc(map->key_size, GFP_USER);
 	if (!key)
 		goto err_put;

 	err = -EFAULT;
 	if (copy_from_user(key, ukey, map->key_size) != 0)
 		goto free_key;

 	err = -ENOMEM;
 	value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN);
 	if (!value)
 		goto free_key;

 	err = -EFAULT;
 	if (copy_from_user(value, uvalue, map->value_size) != 0)
 		goto free_value;

 	/* eBPF program that use maps are running under rcu_read_lock(),
 	 * therefore all map accessors rely on this fact, so do the same here
 	 */
 	rcu_read_lock();
 	err = map->ops->map_update_elem(map, key, value, attr->flags);
 	rcu_read_unlock();

 free_value:
 	kfree(value);
 free_key:
 	kfree(key);
 err_put:
 	fdput(f);
 	return err;
 }

 #define BPF_MAP_DELETE_ELEM_LAST_FIELD key

 static int map_delete_elem(union bpf_attr *attr)
 {
 	void __user *ukey = u64_to_ptr(attr->key);
 	int ufd = attr->map_fd;
 	struct bpf_map *map;
 	struct fd f;
 	void *key;
 	int err;

 	if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
 		return -EINVAL;

 	f = fdget(ufd);
 	map = __bpf_map_get(f);
 	if (IS_ERR(map))
 		return PTR_ERR(map);

 	err = -ENOMEM;
 	key = kmalloc(map->key_size, GFP_USER);
 	if (!key)
 		goto err_put;

 	err = -EFAULT;
 	if (copy_from_user(key, ukey, map->key_size) != 0)
 		goto free_key;

 	rcu_read_lock();
 	err = map->ops->map_delete_elem(map, key);
 	rcu_read_unlock();

 free_key:
 	kfree(key);
 err_put:
 	fdput(f);
 	return err;
 }

 /* last field in 'union bpf_attr' used by this command */
 #define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key

 static int map_get_next_key(union bpf_attr *attr)
 {
 	void __user *ukey = u64_to_ptr(attr->key);
 	void __user *unext_key = u64_to_ptr(attr->next_key);
 	int ufd = attr->map_fd;
 	struct bpf_map *map;
 	void *key, *next_key;
 	struct fd f;
 	int err;

 	if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
 		return -EINVAL;

 	f = fdget(ufd);
 	map = __bpf_map_get(f);
 	if (IS_ERR(map))
 		return PTR_ERR(map);

 	err = -ENOMEM;
 	key = kmalloc(map->key_size, GFP_USER);
 	if (!key)
 		goto err_put;

 	err = -EFAULT;
 	if (copy_from_user(key, ukey, map->key_size) != 0)
 		goto free_key;

 	err = -ENOMEM;
 	next_key = kmalloc(map->key_size, GFP_USER);
 	if (!next_key)
 		goto free_key;

 	rcu_read_lock();
 	err = map->ops->map_get_next_key(map, key, next_key);
 	rcu_read_unlock();
 	if (err)
 		goto free_next_key;

 	err = -EFAULT;
 	if (copy_to_user(unext_key, next_key, map->key_size) != 0)
 		goto free_next_key;

 	err = 0;

 free_next_key:
 	kfree(next_key);
 free_key:
 	kfree(key);
 err_put:
 	fdput(f);
 	return err;
 }

 static LIST_HEAD(bpf_prog_types);

 static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
 {
 	struct bpf_prog_type_list *tl;

 	list_for_each_entry(tl, &bpf_prog_types, list_node) {
 		if (tl->type == type) {
 			prog->aux->ops = tl->ops;
 			prog->type = type;
 			return 0;
 		}
 	}

 	return -EINVAL;
 }

 void bpf_register_prog_type(struct bpf_prog_type_list *tl)
 {
 	list_add(&tl->list_node, &bpf_prog_types);
 }

 /* fixup insn->imm field of bpf_call instructions:
  * if (insn->imm == BPF_FUNC_map_lookup_elem)
  *      insn->imm = bpf_map_lookup_elem - __bpf_call_base;
  * else if (insn->imm == BPF_FUNC_map_update_elem)
  *      insn->imm = bpf_map_update_elem - __bpf_call_base;
  * else ...
  *
  * this function is called after eBPF program passed verification
  */
 static void fixup_bpf_calls(struct bpf_prog *prog)
 {
 	const struct bpf_func_proto *fn;
 	int i;

 	for (i = 0; i < prog->len; i++) {
 		struct bpf_insn *insn = &prog->insnsi[i];

 		if (insn->code == (BPF_JMP | BPF_CALL)) {
 			/* we reach here when program has bpf_call instructions
 			 * and it passed bpf_check(), means that
 			 * ops->get_func_proto must have been supplied, check it
 			 */
 			BUG_ON(!prog->aux->ops->get_func_proto);

 			if (insn->imm == BPF_FUNC_get_route_realm)
 				prog->dst_needed = 1;
 			if (insn->imm == BPF_FUNC_get_prandom_u32)
 				bpf_user_rnd_init_once();
 			if (insn->imm == BPF_FUNC_tail_call) {
 				/* mark bpf_tail_call as different opcode
 				 * to avoid conditional branch in
 				 * interpeter for every normal call
 				 * and to prevent accidental JITing by
 				 * JIT compiler that doesn't support
 				 * bpf_tail_call yet
 				 */
 				insn->imm = 0;
 				insn->code |= BPF_X;
 				continue;
 			}

 			fn = prog->aux->ops->get_func_proto(insn->imm);
 			/* all functions that have prototype and verifier allowed
 			 * programs to call them, must be real in-kernel functions
 			 */
 			BUG_ON(!fn->func);
 			insn->imm = fn->func - __bpf_call_base;
 		}
 	}
 }

 /* drop refcnt on maps used by eBPF program and free auxilary data */
 static void free_used_maps(struct bpf_prog_aux *aux)
 {
 	int i;

 	for (i = 0; i < aux->used_map_cnt; i++)
 		bpf_map_put(aux->used_maps[i]);

 	kfree(aux->used_maps);
 }

 static int bpf_prog_charge_memlock(struct bpf_prog *prog)
 {
 	struct user_struct *user = get_current_user();
 	unsigned long memlock_limit;

 	memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

 	atomic_long_add(prog->pages, &user->locked_vm);
 	if (atomic_long_read(&user->locked_vm) > memlock_limit) {
 		atomic_long_sub(prog->pages, &user->locked_vm);
 		free_uid(user);
 		return -EPERM;
 	}
 	prog->aux->user = user;
 	return 0;
 }

 static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
 {
 	struct user_struct *user = prog->aux->user;

 	atomic_long_sub(prog->pages, &user->locked_vm);
 	free_uid(user);
 }

 static void __prog_put_common(struct rcu_head *rcu)
 {
 	struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);

 	free_used_maps(aux);
 	bpf_prog_uncharge_memlock(aux->prog);
 	bpf_prog_free(aux->prog);
 }

 /* version of bpf_prog_put() that is called after a grace period */
 void bpf_prog_put_rcu(struct bpf_prog *prog)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt))
 		call_rcu(&prog->aux->rcu, __prog_put_common);
 }

 void bpf_prog_put(struct bpf_prog *prog)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt))
 		__prog_put_common(&prog->aux->rcu);
 }
 EXPORT_SYMBOL_GPL(bpf_prog_put);

 static int bpf_prog_release(struct inode *inode, struct file *filp)
 {
 	struct bpf_prog *prog = filp->private_data;

 	bpf_prog_put_rcu(prog);
 	return 0;
 }

 static const struct file_operations bpf_prog_fops = {
         .release = bpf_prog_release,
 };

 int bpf_prog_new_fd(struct bpf_prog *prog)
 {
 	return anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog,
 				O_RDWR | O_CLOEXEC);
 }

 static struct bpf_prog *__bpf_prog_get(struct fd f)
 {
 	if (!f.file)
 		return ERR_PTR(-EBADF);
 	if (f.file->f_op != &bpf_prog_fops) {
 		fdput(f);
 		return ERR_PTR(-EINVAL);
 	}

 	return f.file->private_data;
 }

 struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
 {
 	if (atomic_inc_return(&prog->aux->refcnt) > BPF_MAX_REFCNT) {
 		atomic_dec(&prog->aux->refcnt);
 		return ERR_PTR(-EBUSY);
 	}
 	return prog;
 }

 /* called by sockets/tracing/seccomp before attaching program to an event
  * pairs with bpf_prog_put()
  */
 struct bpf_prog *bpf_prog_get(u32 ufd)
 {
 	struct fd f = fdget(ufd);
 	struct bpf_prog *prog;

 	prog = __bpf_prog_get(f);
 	if (IS_ERR(prog))
 		return prog;

 	prog = bpf_prog_inc(prog);
 	fdput(f);

 	return prog;
 }
 EXPORT_SYMBOL_GPL(bpf_prog_get);

 /* last field in 'union bpf_attr' used by this command */
 #define	BPF_PROG_LOAD_LAST_FIELD kern_version

 static int bpf_prog_load(union bpf_attr *attr)
 {
 	enum bpf_prog_type type = attr->prog_type;
 	struct bpf_prog *prog;
 	int err;
 	char license[128];
 	bool is_gpl;

 	if (CHECK_ATTR(BPF_PROG_LOAD))
 		return -EINVAL;

 	/* copy eBPF program license from user space */
 	if (strncpy_from_user(license, u64_to_ptr(attr->license),
 			      sizeof(license) - 1) < 0)
 		return -EFAULT;
 	license[sizeof(license) - 1] = 0;

 	/* eBPF programs must be GPL compatible to use GPL-ed functions */
 	is_gpl = license_is_gpl_compatible(license);

 	if (attr->insn_cnt >= BPF_MAXINSNS)
 		return -EINVAL;

 	if (type == BPF_PROG_TYPE_KPROBE &&
 	    attr->kern_version != LINUX_VERSION_CODE)
 		return -EINVAL;

 	if (type != BPF_PROG_TYPE_SOCKET_FILTER && !capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	/* plain bpf_prog allocation */
 	prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER);
 	if (!prog)
 		return -ENOMEM;

 	err = bpf_prog_charge_memlock(prog);
 	if (err)
 		goto free_prog_nouncharge;

 	prog->len = attr->insn_cnt;

 	err = -EFAULT;
 	if (copy_from_user(prog->insns, u64_to_ptr(attr->insns),
 			   prog->len * sizeof(struct bpf_insn)) != 0)
 		goto free_prog;

 	prog->orig_prog = NULL;
 	prog->jited = 0;

 	atomic_set(&prog->aux->refcnt, 1);
 	prog->gpl_compatible = is_gpl ? 1 : 0;

 	/* find program type: socket_filter vs tracing_filter */
 	err = find_prog_type(type, prog);
 	if (err < 0)
 		goto free_prog;

 	/* run eBPF verifier */
 	err = bpf_check(&prog, attr);
 	if (err < 0)
 		goto free_used_maps;

 	/* fixup BPF_CALL->imm field */
 	fixup_bpf_calls(prog);

 	/* eBPF program is ready to be JITed */
 	err = bpf_prog_select_runtime(prog);
 	if (err < 0)
 		goto free_used_maps;

 	err = bpf_prog_new_fd(prog);
 	if (err < 0)
 		/* failed to allocate fd */
 		goto free_used_maps;

 	return err;

 free_used_maps:
 	free_used_maps(prog->aux);
 free_prog:
 	bpf_prog_uncharge_memlock(prog);
 free_prog_nouncharge:
 	bpf_prog_free(prog);
 	return err;
 }

 #define BPF_OBJ_LAST_FIELD bpf_fd

 static int bpf_obj_pin(const union bpf_attr *attr)
 {
 	if (CHECK_ATTR(BPF_OBJ))
 		return -EINVAL;

 	return bpf_obj_pin_user(attr->bpf_fd, u64_to_ptr(attr->pathname));
 }

 static int bpf_obj_get(const union bpf_attr *attr)
 {
 	if (CHECK_ATTR(BPF_OBJ) || attr->bpf_fd != 0)
 		return -EINVAL;

 	return bpf_obj_get_user(u64_to_ptr(attr->pathname));
 }

 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
 	union bpf_attr attr = {};
 	int err;

 	if (!capable(CAP_SYS_ADMIN) && sysctl_unprivileged_bpf_disabled)
 		return -EPERM;

 	if (!access_ok(VERIFY_READ, uattr, 1))
 		return -EFAULT;

 	if (size > PAGE_SIZE)	/* silly large */
 		return -E2BIG;

 	/* If we're handed a bigger struct than we know of,
 	 * ensure all the unknown bits are 0 - i.e. new
 	 * user-space does not rely on any kernel feature
 	 * extensions we dont know about yet.
 	 */
 	if (size > sizeof(attr)) {
 		unsigned char __user *addr;
 		unsigned char __user *end;
 		unsigned char val;

 		addr = (void __user *)uattr + sizeof(attr);
 		end  = (void __user *)uattr + size;

 		for (; addr < end; addr++) {
 			err = get_user(val, addr);
 			if (err)
 				return err;
 			if (val)
 				return -E2BIG;
 		}
 		size = sizeof(attr);
 	}

 	/* copy attributes from user space, may be less than sizeof(bpf_attr) */
 	if (copy_from_user(&attr, uattr, size) != 0)
 		return -EFAULT;

 	switch (cmd) {
 	case BPF_MAP_CREATE:
 		err = map_create(&attr);
 		break;
 	case BPF_MAP_LOOKUP_ELEM:
 		err = map_lookup_elem(&attr);
 		break;
 	case BPF_MAP_UPDATE_ELEM:
 		err = map_update_elem(&attr);
 		break;
 	case BPF_MAP_DELETE_ELEM:
 		err = map_delete_elem(&attr);
 		break;
 	case BPF_MAP_GET_NEXT_KEY:
 		err = map_get_next_key(&attr);
 		break;
 	case BPF_PROG_LOAD:
 		err = bpf_prog_load(&attr);
 		break;
 	case BPF_OBJ_PIN:
 		err = bpf_obj_pin(&attr);
 		break;
 	case BPF_OBJ_GET:
 		err = bpf_obj_get(&attr);
 		break;
 	default:
 		err = -EINVAL;
 		break;
 	}

 	return err;
 }
	/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of version 2 of the GNU General Public
	* License as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*/
	#include <linux/bpf.h>
	#include <linux/syscalls.h>
	#include <linux/slab.h>
	#include <linux/anon_inodes.h>
	#include <linux/file.h>
	#include <linux/license.h>
	#include <linux/filter.h>
	#include <linux/version.h>

	int sysctl_unprivileged_bpf_disabled __read_mostly;

	static LIST_HEAD(bpf_map_types);

	static struct bpf_map find_and_alloc_map(union bpf_attr attr)
	{
	struct bpf_map_type_list *tl;
	struct bpf_map *map;

	list_for_each_entry(tl, &bpf_map_types, list_node) {
	if (tl->type == attr->map_type) {
	map = tl->ops->map_alloc(attr);
	if (IS_ERR(map))
	return map;
	map->ops = tl->ops;
	map->map_type = attr->map_type;
	return map;
	}
	}
	return ERR_PTR(-EINVAL);
	}

	/* boot time registration of different map implementations */
	void bpf_register_map_type(struct bpf_map_type_list *tl)
	{
	list_add(&tl->list_node, &bpf_map_types);
	}

	static int bpf_map_charge_memlock(struct bpf_map *map)
	{
	struct user_struct *user = get_current_user();
	unsigned long memlock_limit;

	memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	atomic_long_add(map->pages, &user->locked_vm);

	if (atomic_long_read(&user->locked_vm) > memlock_limit) {
	atomic_long_sub(map->pages, &user->locked_vm);
	free_uid(user);
	return -EPERM;
	}
	map->user = user;
	return 0;
	}

	static void bpf_map_uncharge_memlock(struct bpf_map *map)
	{
	struct user_struct *user = map->user;

	atomic_long_sub(map->pages, &user->locked_vm);
	free_uid(user);
	}

	/* called from workqueue */
	static void bpf_map_free_deferred(struct work_struct *work)
	{
	struct bpf_map *map = container_of(work, struct bpf_map, work);

	bpf_map_uncharge_memlock(map);
	/* implementation dependent freeing */
	map->ops->map_free(map);
	}

	static void bpf_map_put_uref(struct bpf_map *map)
	{
	if (atomic_dec_and_test(&map->usercnt)) {
	if (map->map_type == BPF_MAP_TYPE_PROG_ARRAY)
	bpf_fd_array_map_clear(map);
	}
	}

	/* decrement map refcnt and schedule it for freeing via workqueue
	* (unrelying map implementation ops->map_free() might sleep)
	*/
	void bpf_map_put(struct bpf_map *map)
	{
	if (atomic_dec_and_test(&map->refcnt)) {
	INIT_WORK(&map->work, bpf_map_free_deferred);
	schedule_work(&map->work);
	}
	}

	void bpf_map_put_with_uref(struct bpf_map *map)
	{
	bpf_map_put_uref(map);
	bpf_map_put(map);
	}

	static int bpf_map_release(struct inode inode, struct file filp)
	{
	bpf_map_put_with_uref(filp->private_data);
	return 0;
	}

	static const struct file_operations bpf_map_fops = {
	.release = bpf_map_release,
	};

	int bpf_map_new_fd(struct bpf_map *map)
	{
	return anon_inode_getfd("bpf-map", &bpf_map_fops, map,
	O_RDWR \| O_CLOEXEC);
	}

	/* helper macro to check that unused fields 'union bpf_attr' are zero */
	#define CHECK_ATTR(CMD) \
	memchr_inv((void *) &attr->CMD##_LAST_FIELD + \
	sizeof(attr->CMD##_LAST_FIELD), 0, \
	sizeof(*attr) - \
	offsetof(union bpf_attr, CMD##_LAST_FIELD) - \
	sizeof(attr->CMD##_LAST_FIELD)) != NULL

	#define BPF_MAP_CREATE_LAST_FIELD max_entries
	/* called via syscall */
	static int map_create(union bpf_attr *attr)
	{
	struct bpf_map *map;
	int err;

	err = CHECK_ATTR(BPF_MAP_CREATE);
	if (err)
	return -EINVAL;

	/* find map type and init map: hashtable vs rbtree vs bloom vs ... */
	map = find_and_alloc_map(attr);
	if (IS_ERR(map))
	return PTR_ERR(map);

	atomic_set(&map->refcnt, 1);
	atomic_set(&map->usercnt, 1);

	err = bpf_map_charge_memlock(map);
	if (err)
	goto free_map;

	err = bpf_map_new_fd(map);
	if (err < 0)
	/* failed to allocate fd */
	goto free_map;

	return err;

	free_map:
	map->ops->map_free(map);
	return err;
	}

	/* if error is returned, fd is released.
	* On success caller should complete fd access with matching fdput()
	*/
	struct bpf_map *__bpf_map_get(struct fd f)
	{
	if (!f.file)
	return ERR_PTR(-EBADF);
	if (f.file->f_op != &bpf_map_fops) {
	fdput(f);
	return ERR_PTR(-EINVAL);
	}

	return f.file->private_data;
	}

	/* prog's and map's refcnt limit */
	#define BPF_MAX_REFCNT 32768

	struct bpf_map bpf_map_inc(struct bpf_map map, bool uref)
	{
	if (atomic_inc_return(&map->refcnt) > BPF_MAX_REFCNT) {
	atomic_dec(&map->refcnt);
	return ERR_PTR(-EBUSY);
	}
	if (uref)
	atomic_inc(&map->usercnt);
	return map;
	}

	struct bpf_map *bpf_map_get_with_uref(u32 ufd)
	{
	struct fd f = fdget(ufd);
	struct bpf_map *map;

	map = __bpf_map_get(f);
	if (IS_ERR(map))
	return map;

	map = bpf_map_inc(map, true);
	fdput(f);

	return map;
	}

	/* helper to convert user pointers passed inside __aligned_u64 fields */
	static void __user *u64_to_ptr(__u64 val)
	{
	return (void __user *) (unsigned long) val;
	}

	/* last field in 'union bpf_attr' used by this command */
	#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value

	static int map_lookup_elem(union bpf_attr *attr)
	{
	void __user *ukey = u64_to_ptr(attr->key);
	void __user *uvalue = u64_to_ptr(attr->value);
	int ufd = attr->map_fd;
	struct bpf_map *map;
	void key, value, *ptr;
	struct fd f;
	int err;

	if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
	return -EINVAL;

	f = fdget(ufd);
	map = __bpf_map_get(f);
	if (IS_ERR(map))
	return PTR_ERR(map);

	err = -ENOMEM;
	key = kmalloc(map->key_size, GFP_USER);
	if (!key)
	goto err_put;

	err = -EFAULT;
	if (copy_from_user(key, ukey, map->key_size) != 0)
	goto free_key;

	err = -ENOMEM;
	value = kmalloc(map->value_size, GFP_USER \| __GFP_NOWARN);
	if (!value)
	goto free_key;

	rcu_read_lock();
	ptr = map->ops->map_lookup_elem(map, key);
	if (ptr)
	memcpy(value, ptr, map->value_size);
	rcu_read_unlock();

	err = -ENOENT;
	if (!ptr)
	goto free_value;

	err = -EFAULT;
	if (copy_to_user(uvalue, value, map->value_size) != 0)
	goto free_value;

	err = 0;

	free_value:
	kfree(value);
	free_key:
	kfree(key);
	err_put:
	fdput(f);
	return err;
	}

	#define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags

	static int map_update_elem(union bpf_attr *attr)
	{
	void __user *ukey = u64_to_ptr(attr->key);
	void __user *uvalue = u64_to_ptr(attr->value);
	int ufd = attr->map_fd;
	struct bpf_map *map;
	void key, value;
	struct fd f;
	int err;

	if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
	return -EINVAL;

	f = fdget(ufd);
	map = __bpf_map_get(f);
	if (IS_ERR(map))
	return PTR_ERR(map);

	err = -ENOMEM;
	key = kmalloc(map->key_size, GFP_USER);
	if (!key)
	goto err_put;

	err = -EFAULT;
	if (copy_from_user(key, ukey, map->key_size) != 0)
	goto free_key;

	err = -ENOMEM;
	value = kmalloc(map->value_size, GFP_USER \| __GFP_NOWARN);
	if (!value)
	goto free_key;

	err = -EFAULT;
	if (copy_from_user(value, uvalue, map->value_size) != 0)
	goto free_value;

	/* eBPF program that use maps are running under rcu_read_lock(),
	* therefore all map accessors rely on this fact, so do the same here
	*/
	rcu_read_lock();
	err = map->ops->map_update_elem(map, key, value, attr->flags);
	rcu_read_unlock();

	free_value:
	kfree(value);
	free_key:
	kfree(key);
	err_put:
	fdput(f);
	return err;
	}

	#define BPF_MAP_DELETE_ELEM_LAST_FIELD key

	static int map_delete_elem(union bpf_attr *attr)
	{
	void __user *ukey = u64_to_ptr(attr->key);
	int ufd = attr->map_fd;
	struct bpf_map *map;
	struct fd f;
	void *key;
	int err;

	if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
	return -EINVAL;

	f = fdget(ufd);
	map = __bpf_map_get(f);
	if (IS_ERR(map))
	return PTR_ERR(map);

	err = -ENOMEM;
	key = kmalloc(map->key_size, GFP_USER);
	if (!key)
	goto err_put;

	err = -EFAULT;
	if (copy_from_user(key, ukey, map->key_size) != 0)
	goto free_key;

	rcu_read_lock();
	err = map->ops->map_delete_elem(map, key);
	rcu_read_unlock();

	free_key:
	kfree(key);
	err_put:
	fdput(f);
	return err;
	}

	/* last field in 'union bpf_attr' used by this command */
	#define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key

	static int map_get_next_key(union bpf_attr *attr)
	{
	void __user *ukey = u64_to_ptr(attr->key);
	void __user *unext_key = u64_to_ptr(attr->next_key);
	int ufd = attr->map_fd;
	struct bpf_map *map;
	void key, next_key;
	struct fd f;
	int err;

	if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
	return -EINVAL;

	f = fdget(ufd);
	map = __bpf_map_get(f);
	if (IS_ERR(map))
	return PTR_ERR(map);

	err = -ENOMEM;
	key = kmalloc(map->key_size, GFP_USER);
	if (!key)
	goto err_put;

	err = -EFAULT;
	if (copy_from_user(key, ukey, map->key_size) != 0)
	goto free_key;

	err = -ENOMEM;
	next_key = kmalloc(map->key_size, GFP_USER);
	if (!next_key)
	goto free_key;

	rcu_read_lock();
	err = map->ops->map_get_next_key(map, key, next_key);
	rcu_read_unlock();
	if (err)
	goto free_next_key;

	err = -EFAULT;
	if (copy_to_user(unext_key, next_key, map->key_size) != 0)
	goto free_next_key;

	err = 0;

	free_next_key:
	kfree(next_key);
	free_key:
	kfree(key);
	err_put:
	fdput(f);
	return err;
	}

	static LIST_HEAD(bpf_prog_types);

	static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog)
	{
	struct bpf_prog_type_list *tl;

	list_for_each_entry(tl, &bpf_prog_types, list_node) {
	if (tl->type == type) {
	prog->aux->ops = tl->ops;
	prog->type = type;
	return 0;
	}
	}

	return -EINVAL;
	}

	void bpf_register_prog_type(struct bpf_prog_type_list *tl)
	{
	list_add(&tl->list_node, &bpf_prog_types);
	}

	/* fixup insn->imm field of bpf_call instructions:
	* if (insn->imm == BPF_FUNC_map_lookup_elem)
	* insn->imm = bpf_map_lookup_elem - __bpf_call_base;
	* else if (insn->imm == BPF_FUNC_map_update_elem)
	* insn->imm = bpf_map_update_elem - __bpf_call_base;
	* else ...
	*
	* this function is called after eBPF program passed verification
	*/
	static void fixup_bpf_calls(struct bpf_prog *prog)
	{
	const struct bpf_func_proto *fn;
	int i;

	for (i = 0; i < prog->len; i++) {
	struct bpf_insn *insn = &prog->insnsi[i];

	if (insn->code == (BPF_JMP \| BPF_CALL)) {
	/* we reach here when program has bpf_call instructions
	* and it passed bpf_check(), means that
	* ops->get_func_proto must have been supplied, check it
	*/
	BUG_ON(!prog->aux->ops->get_func_proto);

	if (insn->imm == BPF_FUNC_get_route_realm)
	prog->dst_needed = 1;
	if (insn->imm == BPF_FUNC_get_prandom_u32)
	bpf_user_rnd_init_once();
	if (insn->imm == BPF_FUNC_tail_call) {
	/* mark bpf_tail_call as different opcode
	* to avoid conditional branch in
	* interpeter for every normal call
	* and to prevent accidental JITing by
	* JIT compiler that doesn't support
	* bpf_tail_call yet
	*/
	insn->imm = 0;
	insn->code \|= BPF_X;
	continue;
	}

	fn = prog->aux->ops->get_func_proto(insn->imm);
	/* all functions that have prototype and verifier allowed
	* programs to call them, must be real in-kernel functions
	*/
	BUG_ON(!fn->func);
	insn->imm = fn->func - __bpf_call_base;
	}
	}
	}

	/* drop refcnt on maps used by eBPF program and free auxilary data */
	static void free_used_maps(struct bpf_prog_aux *aux)
	{
	int i;

	for (i = 0; i < aux->used_map_cnt; i++)
	bpf_map_put(aux->used_maps[i]);

	kfree(aux->used_maps);
	}

	static int bpf_prog_charge_memlock(struct bpf_prog *prog)
	{
	struct user_struct *user = get_current_user();
	unsigned long memlock_limit;

	memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	atomic_long_add(prog->pages, &user->locked_vm);
	if (atomic_long_read(&user->locked_vm) > memlock_limit) {
	atomic_long_sub(prog->pages, &user->locked_vm);
	free_uid(user);
	return -EPERM;
	}
	prog->aux->user = user;
	return 0;
	}

	static void bpf_prog_uncharge_memlock(struct bpf_prog *prog)
	{
	struct user_struct *user = prog->aux->user;

	atomic_long_sub(prog->pages, &user->locked_vm);
	free_uid(user);
	}

	static void __prog_put_common(struct rcu_head *rcu)
	{
	struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);

	free_used_maps(aux);
	bpf_prog_uncharge_memlock(aux->prog);
	bpf_prog_free(aux->prog);
	}

	/* version of bpf_prog_put() that is called after a grace period */
	void bpf_prog_put_rcu(struct bpf_prog *prog)
	{
	if (atomic_dec_and_test(&prog->aux->refcnt))
	call_rcu(&prog->aux->rcu, __prog_put_common);
	}

	void bpf_prog_put(struct bpf_prog *prog)
	{
	if (atomic_dec_and_test(&prog->aux->refcnt))
	__prog_put_common(&prog->aux->rcu);
	}
	EXPORT_SYMBOL_GPL(bpf_prog_put);

	static int bpf_prog_release(struct inode inode, struct file filp)
	{
	struct bpf_prog *prog = filp->private_data;

	bpf_prog_put_rcu(prog);
	return 0;
	}

	static const struct file_operations bpf_prog_fops = {
	.release = bpf_prog_release,
	};

	int bpf_prog_new_fd(struct bpf_prog *prog)
	{
	return anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog,
	O_RDWR \| O_CLOEXEC);
	}

	static struct bpf_prog *__bpf_prog_get(struct fd f)
	{
	if (!f.file)
	return ERR_PTR(-EBADF);
	if (f.file->f_op != &bpf_prog_fops) {
	fdput(f);
	return ERR_PTR(-EINVAL);
	}

	return f.file->private_data;
	}

	struct bpf_prog bpf_prog_inc(struct bpf_prog prog)
	{
	if (atomic_inc_return(&prog->aux->refcnt) > BPF_MAX_REFCNT) {
	atomic_dec(&prog->aux->refcnt);
	return ERR_PTR(-EBUSY);
	}
	return prog;
	}

	/* called by sockets/tracing/seccomp before attaching program to an event
	* pairs with bpf_prog_put()
	*/
	struct bpf_prog *bpf_prog_get(u32 ufd)
	{
	struct fd f = fdget(ufd);
	struct bpf_prog *prog;

	prog = __bpf_prog_get(f);
	if (IS_ERR(prog))
	return prog;

	prog = bpf_prog_inc(prog);
	fdput(f);

	return prog;
	}
	EXPORT_SYMBOL_GPL(bpf_prog_get);

	/* last field in 'union bpf_attr' used by this command */
	#define BPF_PROG_LOAD_LAST_FIELD kern_version

	static int bpf_prog_load(union bpf_attr *attr)
	{
	enum bpf_prog_type type = attr->prog_type;
	struct bpf_prog *prog;
	int err;
	char license[128];
	bool is_gpl;

	if (CHECK_ATTR(BPF_PROG_LOAD))
	return -EINVAL;

	/* copy eBPF program license from user space */
	if (strncpy_from_user(license, u64_to_ptr(attr->license),
	sizeof(license) - 1) < 0)
	return -EFAULT;
	license[sizeof(license) - 1] = 0;

	/* eBPF programs must be GPL compatible to use GPL-ed functions */
	is_gpl = license_is_gpl_compatible(license);

	if (attr->insn_cnt >= BPF_MAXINSNS)
	return -EINVAL;

	if (type == BPF_PROG_TYPE_KPROBE &&
	attr->kern_version != LINUX_VERSION_CODE)
	return -EINVAL;

	if (type != BPF_PROG_TYPE_SOCKET_FILTER && !capable(CAP_SYS_ADMIN))
	return -EPERM;

	/* plain bpf_prog allocation */
	prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER);
	if (!prog)
	return -ENOMEM;

	err = bpf_prog_charge_memlock(prog);
	if (err)
	goto free_prog_nouncharge;

	prog->len = attr->insn_cnt;

	err = -EFAULT;
	if (copy_from_user(prog->insns, u64_to_ptr(attr->insns),
	prog->len * sizeof(struct bpf_insn)) != 0)
	goto free_prog;

	prog->orig_prog = NULL;
	prog->jited = 0;

	atomic_set(&prog->aux->refcnt, 1);
	prog->gpl_compatible = is_gpl ? 1 : 0;

	/* find program type: socket_filter vs tracing_filter */
	err = find_prog_type(type, prog);
	if (err < 0)
	goto free_prog;

	/* run eBPF verifier */
	err = bpf_check(&prog, attr);
	if (err < 0)
	goto free_used_maps;

	/* fixup BPF_CALL->imm field */
	fixup_bpf_calls(prog);

	/* eBPF program is ready to be JITed */
	err = bpf_prog_select_runtime(prog);
	if (err < 0)
	goto free_used_maps;

	err = bpf_prog_new_fd(prog);
	if (err < 0)
	/* failed to allocate fd */
	goto free_used_maps;

	return err;

	free_used_maps:
	free_used_maps(prog->aux);
	free_prog:
	bpf_prog_uncharge_memlock(prog);
	free_prog_nouncharge:
	bpf_prog_free(prog);
	return err;
	}

	#define BPF_OBJ_LAST_FIELD bpf_fd

	static int bpf_obj_pin(const union bpf_attr *attr)
	{
	if (CHECK_ATTR(BPF_OBJ))
	return -EINVAL;

	return bpf_obj_pin_user(attr->bpf_fd, u64_to_ptr(attr->pathname));
	}

	static int bpf_obj_get(const union bpf_attr *attr)
	{
	if (CHECK_ATTR(BPF_OBJ) \|\| attr->bpf_fd != 0)
	return -EINVAL;

	return bpf_obj_get_user(u64_to_ptr(attr->pathname));
	}

	SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
	{
	union bpf_attr attr = {};
	int err;

	if (!capable(CAP_SYS_ADMIN) && sysctl_unprivileged_bpf_disabled)
	return -EPERM;

	if (!access_ok(VERIFY_READ, uattr, 1))
	return -EFAULT;

	if (size > PAGE_SIZE) /* silly large */
	return -E2BIG;

	/* If we're handed a bigger struct than we know of,
	* ensure all the unknown bits are 0 - i.e. new
	* user-space does not rely on any kernel feature
	* extensions we dont know about yet.
	*/
	if (size > sizeof(attr)) {
	unsigned char __user *addr;
	unsigned char __user *end;
	unsigned char val;

	addr = (void __user *)uattr + sizeof(attr);
	end = (void __user *)uattr + size;

	for (; addr < end; addr++) {
	err = get_user(val, addr);
	if (err)
	return err;
	if (val)
	return -E2BIG;
	}
	size = sizeof(attr);
	}

	/* copy attributes from user space, may be less than sizeof(bpf_attr) */
	if (copy_from_user(&attr, uattr, size) != 0)
	return -EFAULT;

	switch (cmd) {
	case BPF_MAP_CREATE:
	err = map_create(&attr);
	break;
	case BPF_MAP_LOOKUP_ELEM:
	err = map_lookup_elem(&attr);
	break;
	case BPF_MAP_UPDATE_ELEM:
	err = map_update_elem(&attr);
	break;
	case BPF_MAP_DELETE_ELEM:
	err = map_delete_elem(&attr);
	break;
	case BPF_MAP_GET_NEXT_KEY:
	err = map_get_next_key(&attr);
	break;
	case BPF_PROG_LOAD:
	err = bpf_prog_load(&attr);
	break;
	case BPF_OBJ_PIN:
	err = bpf_obj_pin(&attr);
	break;
	case BPF_OBJ_GET:
	err = bpf_obj_get(&attr);
	break;
	default:
	err = -EINVAL;
	break;
	}

	return err;
	}