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 #ifndef _LINUX_BPF_VERIFIER_H 8 #define _LINUX_BPF_VERIFIER_H 1 9 10 #include <linux/bpf.h> /* for enum bpf_reg_type */ 11 #include <linux/filter.h> /* for MAX_BPF_STACK */ 12 13 /* Just some arbitrary values so we can safely do math without overflowing and 14 * are obviously wrong for any sort of memory access. 15 */ 16 #define BPF_REGISTER_MAX_RANGE (1024 * 1024 * 1024) 17 #define BPF_REGISTER_MIN_RANGE -(1024 * 1024 * 1024) 18 19 struct bpf_reg_state { 20 enum bpf_reg_type type; 21 /* 22 * Used to determine if any memory access using this register will 23 * result in a bad access. 24 */ 25 u64 min_value, max_value; 26 union { 27 /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */ 28 s64 imm; 29 30 /* valid when type == PTR_TO_PACKET* */ 31 struct { 32 u32 id; 33 u16 off; 34 u16 range; 35 }; 36 37 /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | 38 * PTR_TO_MAP_VALUE_OR_NULL 39 */ 40 struct bpf_map *map_ptr; 41 }; 42 }; 43 44 enum bpf_stack_slot_type { 45 STACK_INVALID, /* nothing was stored in this stack slot */ 46 STACK_SPILL, /* register spilled into stack */ 47 STACK_MISC /* BPF program wrote some data into this slot */ 48 }; 49 50 #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ 51 52 /* state of the program: 53 * type of all registers and stack info 54 */ 55 struct bpf_verifier_state { 56 struct bpf_reg_state regs[MAX_BPF_REG]; 57 u8 stack_slot_type[MAX_BPF_STACK]; 58 struct bpf_reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; 59 }; 60 61 /* linked list of verifier states used to prune search */ 62 struct bpf_verifier_state_list { 63 struct bpf_verifier_state state; 64 struct bpf_verifier_state_list *next; 65 }; 66 67 struct bpf_insn_aux_data { 68 enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ 69 }; 70 71 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ 72 73 struct bpf_verifier_env; 74 struct bpf_ext_analyzer_ops { 75 int (*insn_hook)(struct bpf_verifier_env *env, 76 int insn_idx, int prev_insn_idx); 77 }; 78 79 /* single container for all structs 80 * one verifier_env per bpf_check() call 81 */ 82 struct bpf_verifier_env { 83 struct bpf_prog *prog; /* eBPF program being verified */ 84 struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ 85 int stack_size; /* number of states to be processed */ 86 struct bpf_verifier_state cur_state; /* current verifier state */ 87 struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ 88 const struct bpf_ext_analyzer_ops *analyzer_ops; /* external analyzer ops */ 89 void *analyzer_priv; /* pointer to external analyzer's private data */ 90 struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ 91 u32 used_map_cnt; /* number of used maps */ 92 u32 id_gen; /* used to generate unique reg IDs */ 93 bool allow_ptr_leaks; 94 bool seen_direct_write; 95 bool varlen_map_value_access; 96 struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ 97 }; 98 99 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, 100 void *priv); 101 102 #endif /* _LINUX_BPF_VERIFIER_H */ 103