bpf: expose internal verfier structures

/* 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.

 */

#ifndef _LINUX_BPF_VERIFIER_H

#define _LINUX_BPF_VERIFIER_H 1

#include <linux/bpf.h> /* for enum bpf_reg_type */

#include <linux/filter.h> /* for MAX_BPF_STACK */

struct bpf_reg_state {

	enum bpf_reg_type type;

	union {

		/* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */

		s64 imm;

		/* valid when type == PTR_TO_PACKET* */

		struct {

			u32 id;

			u16 off;

			u16 range;

		};

		/* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |

		 *   PTR_TO_MAP_VALUE_OR_NULL

		 */

		struct bpf_map *map_ptr;

	};

};

enum bpf_stack_slot_type {

	STACK_INVALID,    /* nothing was stored in this stack slot */

	STACK_SPILL,      /* register spilled into stack */

	STACK_MISC	  /* BPF program wrote some data into this slot */

};

#define BPF_REG_SIZE 8	/* size of eBPF register in bytes */

/* state of the program:

 * type of all registers and stack info

 */

struct bpf_verifier_state {

	struct bpf_reg_state regs[MAX_BPF_REG];

	u8 stack_slot_type[MAX_BPF_STACK];

	struct bpf_reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE];

};

/* linked list of verifier states used to prune search */

struct bpf_verifier_state_list {

	struct bpf_verifier_state state;

	struct bpf_verifier_state_list *next;

};

struct bpf_insn_aux_data {

	enum bpf_reg_type ptr_type;	/* pointer type for load/store insns */

};

#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */

/* single container for all structs

 * one verifier_env per bpf_check() call

 */

struct bpf_verifier_env {

	struct bpf_prog *prog;		/* eBPF program being verified */

	struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */

	int stack_size;			/* number of states to be processed */

	struct bpf_verifier_state cur_state; /* current verifier state */

	struct bpf_verifier_state_list **explored_states; /* search pruning optimization */

	struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */

	u32 used_map_cnt;		/* number of used maps */

	u32 id_gen;			/* used to generate unique reg IDs */

	bool allow_ptr_leaks;

	bool seen_direct_write;

	struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */

};

#endif /* _LINUX_BPF_VERIFIER_H */