/* 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/err.h>
  #include <linux/vmalloc.h>
  #include <linux/slab.h>
  #include <linux/mm.h>

  #include <linux/filter.h>

  #include <linux/perf_event.h>

  static void bpf_array_free_percpu(struct bpf_array *array)
  {
  	int i;
  
  	for (i = 0; i < array->map.max_entries; i++)
  		free_percpu(array->pptrs[i]);
  }
  
  static int bpf_array_alloc_percpu(struct bpf_array *array)
  {
  	void __percpu *ptr;
  	int i;
  
  	for (i = 0; i < array->map.max_entries; i++) {
  		ptr = __alloc_percpu_gfp(array->elem_size, 8,
  					 GFP_USER | __GFP_NOWARN);
  		if (!ptr) {
  			bpf_array_free_percpu(array);
  			return -ENOMEM;
  		}
  		array->pptrs[i] = ptr;
  	}
  
  	return 0;
  }

  /* Called from syscall */
  static struct bpf_map *array_map_alloc(union bpf_attr *attr)
  {

  	bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;

  	struct bpf_array *array;

  	u64 array_size;
  	u32 elem_size;

  
  	/* check sanity of attributes */
  	if (attr->max_entries == 0 || attr->key_size != 4 ||

  	    attr->value_size == 0 || attr->map_flags)

  		return ERR_PTR(-EINVAL);

  	if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1))
  		/* if value_size is bigger, the user space won't be able to
  		 * access the elements.
  		 */
  		return ERR_PTR(-E2BIG);

  	elem_size = round_up(attr->value_size, 8);

  	array_size = sizeof(*array);
  	if (percpu)
  		array_size += (u64) attr->max_entries * sizeof(void *);
  	else
  		array_size += (u64) attr->max_entries * elem_size;
  
  	/* make sure there is no u32 overflow later in round_up() */
  	if (array_size >= U32_MAX - PAGE_SIZE)

  		return ERR_PTR(-ENOMEM);

  	/* allocate all map elements and zero-initialize them */

  	array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);

  	if (!array) {

  		array = vzalloc(array_size);

  		if (!array)
  			return ERR_PTR(-ENOMEM);
  	}
  
  	/* copy mandatory map attributes */

  	array->map.map_type = attr->map_type;

  	array->map.key_size = attr->key_size;
  	array->map.value_size = attr->value_size;
  	array->map.max_entries = attr->max_entries;

  	array->elem_size = elem_size;

  	if (!percpu)
  		goto out;
  
  	array_size += (u64) attr->max_entries * elem_size * num_possible_cpus();
  
  	if (array_size >= U32_MAX - PAGE_SIZE ||
  	    elem_size > PCPU_MIN_UNIT_SIZE || bpf_array_alloc_percpu(array)) {
  		kvfree(array);
  		return ERR_PTR(-ENOMEM);
  	}
  out:
  	array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;

  	return &array->map;

  }
  
  /* Called from syscall or from eBPF program */
  static void *array_map_lookup_elem(struct bpf_map *map, void *key)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;

  	if (unlikely(index >= array->map.max_entries))

  		return NULL;
  
  	return array->value + array->elem_size * index;
  }

  /* Called from eBPF program */
  static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  
  	if (unlikely(index >= array->map.max_entries))
  		return NULL;
  
  	return this_cpu_ptr(array->pptrs[index]);
  }

  int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  	void __percpu *pptr;
  	int cpu, off = 0;
  	u32 size;
  
  	if (unlikely(index >= array->map.max_entries))
  		return -ENOENT;
  
  	/* per_cpu areas are zero-filled and bpf programs can only
  	 * access 'value_size' of them, so copying rounded areas
  	 * will not leak any kernel data
  	 */
  	size = round_up(map->value_size, 8);
  	rcu_read_lock();
  	pptr = array->pptrs[index];
  	for_each_possible_cpu(cpu) {
  		bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
  		off += size;
  	}
  	rcu_read_unlock();
  	return 0;
  }

  /* Called from syscall */
  static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  	u32 *next = (u32 *)next_key;
  
  	if (index >= array->map.max_entries) {
  		*next = 0;
  		return 0;
  	}
  
  	if (index == array->map.max_entries - 1)
  		return -ENOENT;
  
  	*next = index + 1;
  	return 0;
  }
  
  /* Called from syscall or from eBPF program */
  static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
  				 u64 map_flags)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;

  	if (unlikely(map_flags > BPF_EXIST))

  		/* unknown flags */
  		return -EINVAL;

  	if (unlikely(index >= array->map.max_entries))

  		/* all elements were pre-allocated, cannot insert a new one */
  		return -E2BIG;

  	if (unlikely(map_flags == BPF_NOEXIST))

  		/* all elements already exist */

  		return -EEXIST;

  	if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
  		memcpy(this_cpu_ptr(array->pptrs[index]),
  		       value, map->value_size);
  	else
  		memcpy(array->value + array->elem_size * index,
  		       value, map->value_size);

  	return 0;
  }

  int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
  			    u64 map_flags)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	u32 index = *(u32 *)key;
  	void __percpu *pptr;
  	int cpu, off = 0;
  	u32 size;
  
  	if (unlikely(map_flags > BPF_EXIST))
  		/* unknown flags */
  		return -EINVAL;
  
  	if (unlikely(index >= array->map.max_entries))
  		/* all elements were pre-allocated, cannot insert a new one */
  		return -E2BIG;
  
  	if (unlikely(map_flags == BPF_NOEXIST))
  		/* all elements already exist */
  		return -EEXIST;
  
  	/* the user space will provide round_up(value_size, 8) bytes that
  	 * will be copied into per-cpu area. bpf programs can only access
  	 * value_size of it. During lookup the same extra bytes will be
  	 * returned or zeros which were zero-filled by percpu_alloc,
  	 * so no kernel data leaks possible
  	 */
  	size = round_up(map->value_size, 8);
  	rcu_read_lock();
  	pptr = array->pptrs[index];
  	for_each_possible_cpu(cpu) {
  		bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
  		off += size;
  	}
  	rcu_read_unlock();
  	return 0;
  }

  /* Called from syscall or from eBPF program */
  static int array_map_delete_elem(struct bpf_map *map, void *key)
  {
  	return -EINVAL;
  }
  
  /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
  static void array_map_free(struct bpf_map *map)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  
  	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
  	 * so the programs (can be more than one that used this map) were
  	 * disconnected from events. Wait for outstanding programs to complete
  	 * and free the array
  	 */
  	synchronize_rcu();

  	if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
  		bpf_array_free_percpu(array);

  	kvfree(array);
  }

  static const struct bpf_map_ops array_ops = {

  	.map_alloc = array_map_alloc,
  	.map_free = array_map_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = array_map_lookup_elem,
  	.map_update_elem = array_map_update_elem,
  	.map_delete_elem = array_map_delete_elem,
  };

  static struct bpf_map_type_list array_type __read_mostly = {

  	.ops = &array_ops,
  	.type = BPF_MAP_TYPE_ARRAY,
  };

  static const struct bpf_map_ops percpu_array_ops = {
  	.map_alloc = array_map_alloc,
  	.map_free = array_map_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = percpu_array_map_lookup_elem,
  	.map_update_elem = array_map_update_elem,
  	.map_delete_elem = array_map_delete_elem,
  };
  
  static struct bpf_map_type_list percpu_array_type __read_mostly = {
  	.ops = &percpu_array_ops,
  	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
  };

  static int __init register_array_map(void)
  {

  	bpf_register_map_type(&array_type);

  	bpf_register_map_type(&percpu_array_type);

  	return 0;
  }
  late_initcall(register_array_map);

  static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)

  {

  	/* only file descriptors can be stored in this type of map */

  	if (attr->value_size != sizeof(u32))
  		return ERR_PTR(-EINVAL);
  	return array_map_alloc(attr);
  }

  static void fd_array_map_free(struct bpf_map *map)

  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	int i;
  
  	synchronize_rcu();
  
  	/* make sure it's empty */
  	for (i = 0; i < array->map.max_entries; i++)

  		BUG_ON(array->ptrs[i] != NULL);

  	kvfree(array);
  }

  static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)

  {
  	return NULL;
  }
  
  /* only called from syscall */

  int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
  				 void *key, void *value, u64 map_flags)

  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);

  	void *new_ptr, *old_ptr;

  	u32 index = *(u32 *)key, ufd;
  
  	if (map_flags != BPF_ANY)
  		return -EINVAL;
  
  	if (index >= array->map.max_entries)
  		return -E2BIG;
  
  	ufd = *(u32 *)value;

  	new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);

  	if (IS_ERR(new_ptr))
  		return PTR_ERR(new_ptr);

  	old_ptr = xchg(array->ptrs + index, new_ptr);
  	if (old_ptr)
  		map->ops->map_fd_put_ptr(old_ptr);

  
  	return 0;
  }

  static int fd_array_map_delete_elem(struct bpf_map *map, void *key)

  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);

  	void *old_ptr;

  	u32 index = *(u32 *)key;
  
  	if (index >= array->map.max_entries)
  		return -E2BIG;

  	old_ptr = xchg(array->ptrs + index, NULL);
  	if (old_ptr) {
  		map->ops->map_fd_put_ptr(old_ptr);

  		return 0;
  	} else {
  		return -ENOENT;
  	}
  }

  static void *prog_fd_array_get_ptr(struct bpf_map *map,
  				   struct file *map_file, int fd)

  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	struct bpf_prog *prog = bpf_prog_get(fd);

  	if (IS_ERR(prog))
  		return prog;
  
  	if (!bpf_prog_array_compatible(array, prog)) {
  		bpf_prog_put(prog);
  		return ERR_PTR(-EINVAL);
  	}

  	return prog;
  }
  
  static void prog_fd_array_put_ptr(void *ptr)
  {

  	bpf_prog_put(ptr);

  }

  /* decrement refcnt of all bpf_progs that are stored in this map */

  void bpf_fd_array_map_clear(struct bpf_map *map)

  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	int i;
  
  	for (i = 0; i < array->map.max_entries; i++)

  		fd_array_map_delete_elem(map, &i);

  }
  
  static const struct bpf_map_ops prog_array_ops = {

  	.map_alloc = fd_array_map_alloc,
  	.map_free = fd_array_map_free,

  	.map_get_next_key = array_map_get_next_key,

  	.map_lookup_elem = fd_array_map_lookup_elem,

  	.map_delete_elem = fd_array_map_delete_elem,
  	.map_fd_get_ptr = prog_fd_array_get_ptr,
  	.map_fd_put_ptr = prog_fd_array_put_ptr,

  };
  
  static struct bpf_map_type_list prog_array_type __read_mostly = {
  	.ops = &prog_array_ops,
  	.type = BPF_MAP_TYPE_PROG_ARRAY,
  };
  
  static int __init register_prog_array_map(void)
  {
  	bpf_register_map_type(&prog_array_type);
  	return 0;
  }
  late_initcall(register_prog_array_map);

  static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
  						   struct file *map_file)

  {

  	struct bpf_event_entry *ee;

  	ee = kzalloc(sizeof(*ee), GFP_ATOMIC);

  	if (ee) {
  		ee->event = perf_file->private_data;
  		ee->perf_file = perf_file;
  		ee->map_file = map_file;
  	}
  
  	return ee;
  }
  
  static void __bpf_event_entry_free(struct rcu_head *rcu)
  {
  	struct bpf_event_entry *ee;
  
  	ee = container_of(rcu, struct bpf_event_entry, rcu);
  	fput(ee->perf_file);
  	kfree(ee);
  }
  
  static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
  {
  	call_rcu(&ee->rcu, __bpf_event_entry_free);

  }

  static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
  					 struct file *map_file, int fd)

  {

  	const struct perf_event_attr *attr;

  	struct bpf_event_entry *ee;
  	struct perf_event *event;
  	struct file *perf_file;

  	perf_file = perf_event_get(fd);
  	if (IS_ERR(perf_file))
  		return perf_file;

  	event = perf_file->private_data;
  	ee = ERR_PTR(-EINVAL);

  
  	attr = perf_event_attrs(event);

  	if (IS_ERR(attr) || attr->inherit)
  		goto err_out;
  
  	switch (attr->type) {
  	case PERF_TYPE_SOFTWARE:
  		if (attr->config != PERF_COUNT_SW_BPF_OUTPUT)
  			goto err_out;
  		/* fall-through */
  	case PERF_TYPE_RAW:
  	case PERF_TYPE_HARDWARE:
  		ee = bpf_event_entry_gen(perf_file, map_file);
  		if (ee)
  			return ee;
  		ee = ERR_PTR(-ENOMEM);
  		/* fall-through */
  	default:
  		break;
  	}

  err_out:
  	fput(perf_file);
  	return ee;

  }
  
  static void perf_event_fd_array_put_ptr(void *ptr)
  {

  	bpf_event_entry_free_rcu(ptr);
  }
  
  static void perf_event_fd_array_release(struct bpf_map *map,
  					struct file *map_file)
  {
  	struct bpf_array *array = container_of(map, struct bpf_array, map);
  	struct bpf_event_entry *ee;
  	int i;
  
  	rcu_read_lock();
  	for (i = 0; i < array->map.max_entries; i++) {
  		ee = READ_ONCE(array->ptrs[i]);
  		if (ee && ee->map_file == map_file)
  			fd_array_map_delete_elem(map, &i);
  	}
  	rcu_read_unlock();

  }
  
  static const struct bpf_map_ops perf_event_array_ops = {
  	.map_alloc = fd_array_map_alloc,

  	.map_free = fd_array_map_free,

  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = fd_array_map_lookup_elem,

  	.map_delete_elem = fd_array_map_delete_elem,
  	.map_fd_get_ptr = perf_event_fd_array_get_ptr,
  	.map_fd_put_ptr = perf_event_fd_array_put_ptr,

  	.map_release = perf_event_fd_array_release,

  };
  
  static struct bpf_map_type_list perf_event_array_type __read_mostly = {
  	.ops = &perf_event_array_ops,
  	.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
  };
  
  static int __init register_perf_event_array_map(void)
  {
  	bpf_register_map_type(&perf_event_array_type);
  	return 0;
  }
  late_initcall(register_perf_event_array_map);

  #ifdef CONFIG_CGROUPS

  static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
  				     struct file *map_file /* not used */,
  				     int fd)
  {
  	return cgroup_get_from_fd(fd);
  }
  
  static void cgroup_fd_array_put_ptr(void *ptr)
  {
  	/* cgroup_put free cgrp after a rcu grace period */
  	cgroup_put(ptr);
  }
  
  static void cgroup_fd_array_free(struct bpf_map *map)
  {
  	bpf_fd_array_map_clear(map);
  	fd_array_map_free(map);
  }
  
  static const struct bpf_map_ops cgroup_array_ops = {
  	.map_alloc = fd_array_map_alloc,
  	.map_free = cgroup_fd_array_free,
  	.map_get_next_key = array_map_get_next_key,
  	.map_lookup_elem = fd_array_map_lookup_elem,
  	.map_delete_elem = fd_array_map_delete_elem,
  	.map_fd_get_ptr = cgroup_fd_array_get_ptr,
  	.map_fd_put_ptr = cgroup_fd_array_put_ptr,
  };
  
  static struct bpf_map_type_list cgroup_array_type __read_mostly = {
  	.ops = &cgroup_array_ops,
  	.type = BPF_MAP_TYPE_CGROUP_ARRAY,
  };
  
  static int __init register_cgroup_array_map(void)
  {
  	bpf_register_map_type(&cgroup_array_type);
  	return 0;
  }
  late_initcall(register_cgroup_array_map);
  #endif