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 -1 18 19 struct bpf_reg_state { 20 enum bpf_reg_type type; 21 union { 22 /* valid when type == CONST_IMM | PTR_TO_STACK | UNKNOWN_VALUE */ 23 s64 imm; 24 25 /* valid when type == PTR_TO_PACKET* */ 26 struct { 27 u16 off; 28 u16 range; 29 }; 30 31 /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | 32 * PTR_TO_MAP_VALUE_OR_NULL 33 */ 34 struct bpf_map *map_ptr; 35 }; 36 u32 id; 37 /* Used to determine if any memory access using this register will 38 * result in a bad access. These two fields must be last. 39 * See states_equal() 40 */ 41 s64 min_value; 42 u64 max_value; 43 u32 min_align; 44 u32 aux_off; 45 u32 aux_off_align; 46 }; 47 48 enum bpf_stack_slot_type { 49 STACK_INVALID, /* nothing was stored in this stack slot */ 50 STACK_SPILL, /* register spilled into stack */ 51 STACK_MISC /* BPF program wrote some data into this slot */ 52 }; 53 54 #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ 55 56 /* state of the program: 57 * type of all registers and stack info 58 */ 59 struct bpf_verifier_state { 60 struct bpf_reg_state regs[MAX_BPF_REG]; 61 u8 stack_slot_type[MAX_BPF_STACK]; 62 struct bpf_reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE]; 63 }; 64 65 /* linked list of verifier states used to prune search */ 66 struct bpf_verifier_state_list { 67 struct bpf_verifier_state state; 68 struct bpf_verifier_state_list *next; 69 }; 70 71 struct bpf_insn_aux_data { 72 union { 73 enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ 74 struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */ 75 }; 76 int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ 77 int converted_op_size; /* the valid value width after perceived conversion */ 78 }; 79 80 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ 81 82 struct bpf_verifier_env; 83 struct bpf_ext_analyzer_ops { 84 int (*insn_hook)(struct bpf_verifier_env *env, 85 int insn_idx, int prev_insn_idx); 86 }; 87 88 /* single container for all structs 89 * one verifier_env per bpf_check() call 90 */ 91 struct bpf_verifier_env { 92 struct bpf_prog *prog; /* eBPF program being verified */ 93 struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ 94 int stack_size; /* number of states to be processed */ 95 bool strict_alignment; /* perform strict pointer alignment checks */ 96 struct bpf_verifier_state cur_state; /* current verifier state */ 97 struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ 98 const struct bpf_ext_analyzer_ops *analyzer_ops; /* external analyzer ops */ 99 void *analyzer_priv; /* pointer to external analyzer's private data */ 100 struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ 101 u32 used_map_cnt; /* number of used maps */ 102 u32 id_gen; /* used to generate unique reg IDs */ 103 bool allow_ptr_leaks; 104 bool seen_direct_write; 105 bool varlen_map_value_access; 106 struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ 107 }; 108 109 int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops, 110 void *priv); 111 112 #endif /* _LINUX_BPF_VERIFIER_H */ 113