/* 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/vmalloc.h>
  #include <linux/mmzone.h>

  #include <linux/anon_inodes.h>

  #include <linux/file.h>

  #include <linux/license.h>
  #include <linux/filter.h>

  #include <linux/version.h>

  DEFINE_PER_CPU(int, bpf_prog_active);

  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);
  }

  void *bpf_map_area_alloc(size_t size)
  {
  	/* We definitely need __GFP_NORETRY, so OOM killer doesn't
  	 * trigger under memory pressure as we really just want to
  	 * fail instead.
  	 */
  	const gfp_t flags = __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO;
  	void *area;
  
  	if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
  		area = kmalloc(size, GFP_USER | flags);
  		if (area != NULL)
  			return area;
  	}
  
  	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | flags,
  			 PAGE_KERNEL);
  }
  
  void bpf_map_area_free(void *area)
  {
  	kvfree(area);
  }

  int bpf_map_precharge_memlock(u32 pages)
  {
  	struct user_struct *user = get_current_user();
  	unsigned long memlock_limit, cur;
  
  	memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  	cur = atomic_long_read(&user->locked_vm);
  	free_uid(user);
  	if (cur + pages > memlock_limit)
  		return -EPERM;
  	return 0;
  }

  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)
  {

  	struct bpf_map *map = filp->private_data;
  
  	if (map->ops->map_release)
  		map->ops->map_release(map, filp);
  
  	bpf_map_put_with_uref(map);

  	return 0;
  }

  #ifdef CONFIG_PROC_FS
  static void bpf_map_show_fdinfo(struct seq_file *m, struct file *filp)
  {
  	const struct bpf_map *map = filp->private_data;
  
  	seq_printf(m,
  		   "map_type:\t%u
  "
  		   "key_size:\t%u
  "
  		   "value_size:\t%u
  "

  		   "max_entries:\t%u
  "
  		   "map_flags:\t%#x
  ",

  		   map->map_type,
  		   map->key_size,
  		   map->value_size,

  		   map->max_entries,
  		   map->map_flags);

  }
  #endif

  static const struct file_operations bpf_map_fops = {

  #ifdef CONFIG_PROC_FS
  	.show_fdinfo	= bpf_map_show_fdinfo,
  #endif
  	.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 map_flags

  /* 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_nouncharge;

  	err = bpf_map_new_fd(map);

  	if (err < 0)
  		/* failed to allocate fd */
  		goto free_map;
  
  	return err;
  
  free_map:

  	bpf_map_uncharge_memlock(map);
  free_map_nouncharge:

  	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;
  }

  int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
  {
  	return -ENOTSUPP;
  }

  /* 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;

  	u32 value_size;

  	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;

  	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
  	    map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
  		value_size = round_up(map->value_size, 8) * num_possible_cpus();
  	else
  		value_size = map->value_size;

  	err = -ENOMEM;

  	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);

  	if (!value)

  		goto free_key;

  	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH) {
  		err = bpf_percpu_hash_copy(map, key, value);
  	} else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
  		err = bpf_percpu_array_copy(map, key, value);

  	} else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) {
  		err = bpf_stackmap_copy(map, key, value);

  	} else {
  		rcu_read_lock();
  		ptr = map->ops->map_lookup_elem(map, key);
  		if (ptr)
  			memcpy(value, ptr, value_size);
  		rcu_read_unlock();
  		err = ptr ? 0 : -ENOENT;
  	}

  	if (err)

  		goto free_value;

  
  	err = -EFAULT;

  	if (copy_to_user(uvalue, value, 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;

  	u32 value_size;

  	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;

  	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
  	    map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
  		value_size = round_up(map->value_size, 8) * num_possible_cpus();
  	else
  		value_size = map->value_size;

  	err = -ENOMEM;

  	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);

  	if (!value)
  		goto free_key;
  
  	err = -EFAULT;

  	if (copy_from_user(value, uvalue, value_size) != 0)

  		goto free_value;

  	/* must increment bpf_prog_active to avoid kprobe+bpf triggering from
  	 * inside bpf map update or delete otherwise deadlocks are possible
  	 */
  	preempt_disable();
  	__this_cpu_inc(bpf_prog_active);

  	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH) {
  		err = bpf_percpu_hash_update(map, key, value, attr->flags);
  	} else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
  		err = bpf_percpu_array_update(map, key, value, attr->flags);

  	} else if (map->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY ||

  		   map->map_type == BPF_MAP_TYPE_PROG_ARRAY ||
  		   map->map_type == BPF_MAP_TYPE_CGROUP_ARRAY) {

  		rcu_read_lock();
  		err = bpf_fd_array_map_update_elem(map, f.file, key, value,
  						   attr->flags);
  		rcu_read_unlock();

  	} else {
  		rcu_read_lock();
  		err = map->ops->map_update_elem(map, key, value, attr->flags);
  		rcu_read_unlock();
  	}

  	__this_cpu_dec(bpf_prog_active);
  	preempt_enable();

  
  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;

  	preempt_disable();
  	__this_cpu_inc(bpf_prog_active);

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

  	__this_cpu_dec(bpf_prog_active);
  	preempt_enable();

  
  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);
  }
  
  /* 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 __bpf_prog_put_rcu(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);
  }

  void bpf_prog_put(struct bpf_prog *prog)
  {

  	if (atomic_dec_and_test(&prog->aux->refcnt))

  		call_rcu(&prog->aux->rcu, __bpf_prog_put_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(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_add(struct bpf_prog *prog, int i)

  {

  	if (atomic_add_return(i, &prog->aux->refcnt) > BPF_MAX_REFCNT) {
  		atomic_sub(i, &prog->aux->refcnt);

  		return ERR_PTR(-EBUSY);
  	}
  	return prog;
  }

  EXPORT_SYMBOL_GPL(bpf_prog_add);
  
  struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
  {
  	return bpf_prog_add(prog, 1);
  }

  static struct bpf_prog *__bpf_prog_get(u32 ufd, enum bpf_prog_type *type)

  {
  	struct fd f = fdget(ufd);
  	struct bpf_prog *prog;

  	prog = ____bpf_prog_get(f);

  	if (IS_ERR(prog))
  		return prog;

  	if (type && prog->type != *type) {
  		prog = ERR_PTR(-EINVAL);
  		goto out;
  	}

  	prog = bpf_prog_inc(prog);

  out:

  	fdput(f);
  	return prog;
  }

  
  struct bpf_prog *bpf_prog_get(u32 ufd)
  {
  	return __bpf_prog_get(ufd, NULL);
  }
  
  struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type)
  {
  	return __bpf_prog_get(ufd, &type);
  }
  EXPORT_SYMBOL_GPL(bpf_prog_get_type);

  
  /* 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;
  
  	/* eBPF program is ready to be JITed */

  	prog = bpf_prog_select_runtime(prog, &err);

  	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;
  }