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58e2af8b JK |
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 */ | |
f1174f77 | 12 | #include <linux/tnum.h> |
58e2af8b | 13 | |
b03c9f9f EC |
14 | /* Maximum variable offset umax_value permitted when resolving memory accesses. |
15 | * In practice this is far bigger than any realistic pointer offset; this limit | |
16 | * ensures that umax_value + (int)off + (int)size cannot overflow a u64. | |
17 | */ | |
bb7f0f98 | 18 | #define BPF_MAX_VAR_OFF (1 << 29) |
b03c9f9f EC |
19 | /* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures |
20 | * that converting umax_value to int cannot overflow. | |
21 | */ | |
bb7f0f98 | 22 | #define BPF_MAX_VAR_SIZ (1 << 29) |
48461135 | 23 | |
8e9cd9ce EC |
24 | /* Liveness marks, used for registers and spilled-regs (in stack slots). |
25 | * Read marks propagate upwards until they find a write mark; they record that | |
26 | * "one of this state's descendants read this reg" (and therefore the reg is | |
27 | * relevant for states_equal() checks). | |
28 | * Write marks collect downwards and do not propagate; they record that "the | |
29 | * straight-line code that reached this state (from its parent) wrote this reg" | |
30 | * (and therefore that reads propagated from this state or its descendants | |
31 | * should not propagate to its parent). | |
32 | * A state with a write mark can receive read marks; it just won't propagate | |
33 | * them to its parent, since the write mark is a property, not of the state, | |
34 | * but of the link between it and its parent. See mark_reg_read() and | |
35 | * mark_stack_slot_read() in kernel/bpf/verifier.c. | |
36 | */ | |
dc503a8a EC |
37 | enum bpf_reg_liveness { |
38 | REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */ | |
39 | REG_LIVE_READ, /* reg was read, so we're sensitive to initial value */ | |
40 | REG_LIVE_WRITTEN, /* reg was written first, screening off later reads */ | |
41 | }; | |
42 | ||
58e2af8b JK |
43 | struct bpf_reg_state { |
44 | enum bpf_reg_type type; | |
45 | union { | |
f1174f77 EC |
46 | /* valid when type == PTR_TO_PACKET */ |
47 | u16 range; | |
58e2af8b JK |
48 | |
49 | /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | | |
50 | * PTR_TO_MAP_VALUE_OR_NULL | |
51 | */ | |
52 | struct bpf_map *map_ptr; | |
9f4f72e7 DB |
53 | |
54 | /* Max size from any of the above. */ | |
55 | unsigned long raw; | |
58e2af8b | 56 | }; |
f1174f77 EC |
57 | /* Fixed part of pointer offset, pointer types only */ |
58 | s32 off; | |
59 | /* For PTR_TO_PACKET, used to find other pointers with the same variable | |
60 | * offset, so they can share range knowledge. | |
61 | * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we | |
62 | * came from, when one is tested for != NULL. | |
63 | */ | |
d2a4dd37 | 64 | u32 id; |
dc503a8a | 65 | /* Ordering of fields matters. See states_equal() */ |
f1174f77 EC |
66 | /* For scalar types (SCALAR_VALUE), this represents our knowledge of |
67 | * the actual value. | |
68 | * For pointer types, this represents the variable part of the offset | |
69 | * from the pointed-to object, and is shared with all bpf_reg_states | |
70 | * with the same id as us. | |
71 | */ | |
72 | struct tnum var_off; | |
d2a4dd37 | 73 | /* Used to determine if any memory access using this register will |
f1174f77 EC |
74 | * result in a bad access. |
75 | * These refer to the same value as var_off, not necessarily the actual | |
76 | * contents of the register. | |
d2a4dd37 | 77 | */ |
b03c9f9f EC |
78 | s64 smin_value; /* minimum possible (s64)value */ |
79 | s64 smax_value; /* maximum possible (s64)value */ | |
80 | u64 umin_value; /* minimum possible (u64)value */ | |
81 | u64 umax_value; /* maximum possible (u64)value */ | |
dc503a8a EC |
82 | /* This field must be last, for states_equal() reasons. */ |
83 | enum bpf_reg_liveness live; | |
58e2af8b JK |
84 | }; |
85 | ||
86 | enum bpf_stack_slot_type { | |
87 | STACK_INVALID, /* nothing was stored in this stack slot */ | |
88 | STACK_SPILL, /* register spilled into stack */ | |
89 | STACK_MISC /* BPF program wrote some data into this slot */ | |
90 | }; | |
91 | ||
92 | #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ | |
93 | ||
638f5b90 AS |
94 | struct bpf_stack_state { |
95 | struct bpf_reg_state spilled_ptr; | |
96 | u8 slot_type[BPF_REG_SIZE]; | |
97 | }; | |
98 | ||
58e2af8b JK |
99 | /* state of the program: |
100 | * type of all registers and stack info | |
101 | */ | |
102 | struct bpf_verifier_state { | |
103 | struct bpf_reg_state regs[MAX_BPF_REG]; | |
dc503a8a | 104 | struct bpf_verifier_state *parent; |
010150ff | 105 | bool speculative; |
638f5b90 AS |
106 | int allocated_stack; |
107 | struct bpf_stack_state *stack; | |
58e2af8b JK |
108 | }; |
109 | ||
110 | /* linked list of verifier states used to prune search */ | |
111 | struct bpf_verifier_state_list { | |
112 | struct bpf_verifier_state state; | |
113 | struct bpf_verifier_state_list *next; | |
114 | }; | |
115 | ||
010150ff DB |
116 | /* Possible states for alu_state member. */ |
117 | #define BPF_ALU_SANITIZE_SRC 1U | |
118 | #define BPF_ALU_SANITIZE_DST 2U | |
119 | #define BPF_ALU_NEG_VALUE (1U << 2) | |
d51999cb | 120 | #define BPF_ALU_NON_POINTER (1U << 3) |
010150ff DB |
121 | #define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \ |
122 | BPF_ALU_SANITIZE_DST) | |
123 | ||
58e2af8b | 124 | struct bpf_insn_aux_data { |
81ed18ab AS |
125 | union { |
126 | enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ | |
3f62bcc9 | 127 | unsigned long map_state; /* pointer/poison value for maps */ |
010150ff | 128 | u32 alu_limit; /* limit for add/sub register with pointer */ |
81ed18ab | 129 | }; |
23994631 | 130 | int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ |
abd098e0 | 131 | int sanitize_stack_off; /* stack slot to be cleared */ |
c131187d | 132 | bool seen; /* this insn was processed by the verifier */ |
010150ff | 133 | u8 alu_state; /* used in combination with alu_limit */ |
58e2af8b JK |
134 | }; |
135 | ||
136 | #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ | |
137 | ||
a2a7d570 JK |
138 | #define BPF_VERIFIER_TMP_LOG_SIZE 1024 |
139 | ||
e7bf8249 JK |
140 | struct bpf_verifer_log { |
141 | u32 level; | |
a2a7d570 | 142 | char kbuf[BPF_VERIFIER_TMP_LOG_SIZE]; |
e7bf8249 JK |
143 | char __user *ubuf; |
144 | u32 len_used; | |
145 | u32 len_total; | |
146 | }; | |
147 | ||
148 | static inline bool bpf_verifier_log_full(const struct bpf_verifer_log *log) | |
149 | { | |
150 | return log->len_used >= log->len_total - 1; | |
151 | } | |
152 | ||
13a27dfc JK |
153 | struct bpf_verifier_env; |
154 | struct bpf_ext_analyzer_ops { | |
155 | int (*insn_hook)(struct bpf_verifier_env *env, | |
156 | int insn_idx, int prev_insn_idx); | |
157 | }; | |
158 | ||
58e2af8b JK |
159 | /* single container for all structs |
160 | * one verifier_env per bpf_check() call | |
161 | */ | |
162 | struct bpf_verifier_env { | |
f93a623f DB |
163 | u32 insn_idx; |
164 | u32 prev_insn_idx; | |
58e2af8b | 165 | struct bpf_prog *prog; /* eBPF program being verified */ |
00176a34 | 166 | const struct bpf_verifier_ops *ops; |
58e2af8b JK |
167 | struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ |
168 | int stack_size; /* number of states to be processed */ | |
e07b98d9 | 169 | bool strict_alignment; /* perform strict pointer alignment checks */ |
638f5b90 | 170 | struct bpf_verifier_state *cur_state; /* current verifier state */ |
58e2af8b | 171 | struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ |
ab3f0063 | 172 | const struct bpf_ext_analyzer_ops *dev_ops; /* device analyzer ops */ |
58e2af8b JK |
173 | struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ |
174 | u32 used_map_cnt; /* number of used maps */ | |
175 | u32 id_gen; /* used to generate unique reg IDs */ | |
176 | bool allow_ptr_leaks; | |
177 | bool seen_direct_write; | |
178 | struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ | |
61bd5218 JK |
179 | |
180 | struct bpf_verifer_log log; | |
58e2af8b JK |
181 | }; |
182 | ||
638f5b90 AS |
183 | static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) |
184 | { | |
185 | return env->cur_state->regs; | |
186 | } | |
187 | ||
ab3f0063 JK |
188 | #if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL) |
189 | int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env); | |
190 | #else | |
14380194 | 191 | static inline int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env) |
ab3f0063 JK |
192 | { |
193 | return -EOPNOTSUPP; | |
194 | } | |
195 | #endif | |
196 | ||
58e2af8b | 197 | #endif /* _LINUX_BPF_VERIFIER_H */ |