[deliverable/linux.git] / kernel / bpf / helpers.c

/* 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/rcupdate.h>

/* If kernel subsystem is allowing eBPF programs to call this function,
 * inside its own verifier_ops->get_func_proto() callback it should return
 * bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
 *
 * Different map implementations will rely on rcu in map methods
 * lookup/update/delete, therefore eBPF programs must run under rcu lock
 * if program is allowed to access maps, so check rcu_read_lock_held in
 * all three functions.
 */
static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
	/* verifier checked that R1 contains a valid pointer to bpf_map
	 * and R2 points to a program stack and map->key_size bytes were
	 * initialized
	 */
	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
	void *key = (void *) (unsigned long) r2;
	void *value;

	WARN_ON_ONCE(!rcu_read_lock_held());

	value = map->ops->map_lookup_elem(map, key);

	/* lookup() returns either pointer to element value or NULL
	 * which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type
	 */
	return (unsigned long) value;
}

struct bpf_func_proto bpf_map_lookup_elem_proto = {
	.func = bpf_map_lookup_elem,
	.gpl_only = false,
	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
	.arg1_type = ARG_CONST_MAP_PTR,
	.arg2_type = ARG_PTR_TO_MAP_KEY,
};

static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
	void *key = (void *) (unsigned long) r2;
	void *value = (void *) (unsigned long) r3;

	WARN_ON_ONCE(!rcu_read_lock_held());

	return map->ops->map_update_elem(map, key, value, r4);
}

struct bpf_func_proto bpf_map_update_elem_proto = {
	.func = bpf_map_update_elem,
	.gpl_only = false,
	.ret_type = RET_INTEGER,
	.arg1_type = ARG_CONST_MAP_PTR,
	.arg2_type = ARG_PTR_TO_MAP_KEY,
	.arg3_type = ARG_PTR_TO_MAP_VALUE,
	.arg4_type = ARG_ANYTHING,
};

static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
	void *key = (void *) (unsigned long) r2;

	WARN_ON_ONCE(!rcu_read_lock_held());

	return map->ops->map_delete_elem(map, key);
}

struct bpf_func_proto bpf_map_delete_elem_proto = {
	.func = bpf_map_delete_elem,
	.gpl_only = false,
	.ret_type = RET_INTEGER,
	.arg1_type = ARG_CONST_MAP_PTR,
	.arg2_type = ARG_PTR_TO_MAP_KEY,
};
Commit	Line	Data
d0003ec0 AS	1	/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
	2	*
	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.
	6	*
	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.
	11	*/
	12	#include <linux/bpf.h>
	13	#include <linux/rcupdate.h>
	14
	15	/* If kernel subsystem is allowing eBPF programs to call this function,
	16	* inside its own verifier_ops->get_func_proto() callback it should return
	17	* bpf_map_lookup_elem_proto, so that verifier can properly check the arguments
	18	*
	19	* Different map implementations will rely on rcu in map methods
	20	* lookup/update/delete, therefore eBPF programs must run under rcu lock
	21	* if program is allowed to access maps, so check rcu_read_lock_held in
	22	* all three functions.
	23	*/
	24	static u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
	25	{
	26	/* verifier checked that R1 contains a valid pointer to bpf_map
	27	* and R2 points to a program stack and map->key_size bytes were
	28	* initialized
	29	*/
	30	struct bpf_map map = (struct bpf_map ) (unsigned long) r1;
	31	void key = (void ) (unsigned long) r2;
	32	void *value;
	33
	34	WARN_ON_ONCE(!rcu_read_lock_held());
	35
	36	value = map->ops->map_lookup_elem(map, key);
	37
	38	/* lookup() returns either pointer to element value or NULL
	39	* which is the meaning of PTR_TO_MAP_VALUE_OR_NULL type
	40	*/
	41	return (unsigned long) value;
	42	}
	43
	44	struct bpf_func_proto bpf_map_lookup_elem_proto = {
	45	.func = bpf_map_lookup_elem,
	46	.gpl_only = false,
	47	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
	48	.arg1_type = ARG_CONST_MAP_PTR,
	49	.arg2_type = ARG_PTR_TO_MAP_KEY,
	50	};
	51
	52	static u64 bpf_map_update_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
	53	{
	54	struct bpf_map map = (struct bpf_map ) (unsigned long) r1;
	55	void key = (void ) (unsigned long) r2;
	56	void value = (void ) (unsigned long) r3;
	57
	58	WARN_ON_ONCE(!rcu_read_lock_held());
	59
	60	return map->ops->map_update_elem(map, key, value, r4);
	61	}
	62
	63	struct bpf_func_proto bpf_map_update_elem_proto = {
	64	.func = bpf_map_update_elem,
65	.gpl_only = false,
66	.ret_type = RET_INTEGER,
67	.arg1_type = ARG_CONST_MAP_PTR,
68	.arg2_type = ARG_PTR_TO_MAP_KEY,
69	.arg3_type = ARG_PTR_TO_MAP_VALUE,
70	.arg4_type = ARG_ANYTHING,
71	};
72
73	static u64 bpf_map_delete_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
74	{
75	struct bpf_map map = (struct bpf_map ) (unsigned long) r1;
76	void key = (void ) (unsigned long) r2;
77
78	WARN_ON_ONCE(!rcu_read_lock_held());
79
80	return map->ops->map_delete_elem(map, key);
81	}
82
83	struct bpf_func_proto bpf_map_delete_elem_proto = {
84	.func = bpf_map_delete_elem,
85	.gpl_only = false,
86	.ret_type = RET_INTEGER,
87	.arg1_type = ARG_CONST_MAP_PTR,
88	.arg2_type = ARG_PTR_TO_MAP_KEY,
89	};