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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; | |
53 | }; | |
f1174f77 EC |
54 | /* Fixed part of pointer offset, pointer types only */ |
55 | s32 off; | |
56 | /* For PTR_TO_PACKET, used to find other pointers with the same variable | |
57 | * offset, so they can share range knowledge. | |
58 | * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we | |
59 | * came from, when one is tested for != NULL. | |
60 | */ | |
d2a4dd37 | 61 | u32 id; |
dc503a8a | 62 | /* Ordering of fields matters. See states_equal() */ |
f1174f77 EC |
63 | /* For scalar types (SCALAR_VALUE), this represents our knowledge of |
64 | * the actual value. | |
65 | * For pointer types, this represents the variable part of the offset | |
66 | * from the pointed-to object, and is shared with all bpf_reg_states | |
67 | * with the same id as us. | |
68 | */ | |
69 | struct tnum var_off; | |
d2a4dd37 | 70 | /* Used to determine if any memory access using this register will |
f1174f77 EC |
71 | * result in a bad access. |
72 | * These refer to the same value as var_off, not necessarily the actual | |
73 | * contents of the register. | |
d2a4dd37 | 74 | */ |
b03c9f9f EC |
75 | s64 smin_value; /* minimum possible (s64)value */ |
76 | s64 smax_value; /* maximum possible (s64)value */ | |
77 | u64 umin_value; /* minimum possible (u64)value */ | |
78 | u64 umax_value; /* maximum possible (u64)value */ | |
f4d7e40a AS |
79 | /* Inside the callee two registers can be both PTR_TO_STACK like |
80 | * R1=fp-8 and R2=fp-8, but one of them points to this function stack | |
81 | * while another to the caller's stack. To differentiate them 'frameno' | |
82 | * is used which is an index in bpf_verifier_state->frame[] array | |
83 | * pointing to bpf_func_state. | |
84 | * This field must be second to last, for states_equal() reasons. | |
85 | */ | |
86 | u32 frameno; | |
dc503a8a EC |
87 | /* This field must be last, for states_equal() reasons. */ |
88 | enum bpf_reg_liveness live; | |
58e2af8b JK |
89 | }; |
90 | ||
91 | enum bpf_stack_slot_type { | |
92 | STACK_INVALID, /* nothing was stored in this stack slot */ | |
93 | STACK_SPILL, /* register spilled into stack */ | |
cc2b14d5 AS |
94 | STACK_MISC, /* BPF program wrote some data into this slot */ |
95 | STACK_ZERO, /* BPF program wrote constant zero */ | |
58e2af8b JK |
96 | }; |
97 | ||
98 | #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ | |
99 | ||
638f5b90 AS |
100 | struct bpf_stack_state { |
101 | struct bpf_reg_state spilled_ptr; | |
102 | u8 slot_type[BPF_REG_SIZE]; | |
103 | }; | |
104 | ||
58e2af8b JK |
105 | /* state of the program: |
106 | * type of all registers and stack info | |
107 | */ | |
f4d7e40a | 108 | struct bpf_func_state { |
58e2af8b | 109 | struct bpf_reg_state regs[MAX_BPF_REG]; |
dc503a8a | 110 | struct bpf_verifier_state *parent; |
f4d7e40a AS |
111 | /* index of call instruction that called into this func */ |
112 | int callsite; | |
113 | /* stack frame number of this function state from pov of | |
114 | * enclosing bpf_verifier_state. | |
115 | * 0 = main function, 1 = first callee. | |
116 | */ | |
117 | u32 frameno; | |
118 | /* subprog number == index within subprog_stack_depth | |
119 | * zero == main subprog | |
120 | */ | |
121 | u32 subprogno; | |
122 | ||
123 | /* should be second to last. See copy_func_state() */ | |
638f5b90 AS |
124 | int allocated_stack; |
125 | struct bpf_stack_state *stack; | |
58e2af8b JK |
126 | }; |
127 | ||
f4d7e40a AS |
128 | #define MAX_CALL_FRAMES 8 |
129 | struct bpf_verifier_state { | |
130 | /* call stack tracking */ | |
131 | struct bpf_func_state *frame[MAX_CALL_FRAMES]; | |
132 | struct bpf_verifier_state *parent; | |
133 | u32 curframe; | |
134 | }; | |
135 | ||
58e2af8b JK |
136 | /* linked list of verifier states used to prune search */ |
137 | struct bpf_verifier_state_list { | |
138 | struct bpf_verifier_state state; | |
139 | struct bpf_verifier_state_list *next; | |
140 | }; | |
141 | ||
142 | struct bpf_insn_aux_data { | |
81ed18ab AS |
143 | union { |
144 | enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ | |
145 | struct bpf_map *map_ptr; /* pointer for call insn into lookup_elem */ | |
1c2a088a | 146 | s32 call_imm; /* saved imm field of call insn */ |
81ed18ab | 147 | }; |
23994631 | 148 | int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ |
c131187d | 149 | bool seen; /* this insn was processed by the verifier */ |
58e2af8b JK |
150 | }; |
151 | ||
152 | #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ | |
153 | ||
a2a7d570 JK |
154 | #define BPF_VERIFIER_TMP_LOG_SIZE 1024 |
155 | ||
b9193c1b | 156 | struct bpf_verifier_log { |
e7bf8249 | 157 | u32 level; |
a2a7d570 | 158 | char kbuf[BPF_VERIFIER_TMP_LOG_SIZE]; |
e7bf8249 JK |
159 | char __user *ubuf; |
160 | u32 len_used; | |
161 | u32 len_total; | |
162 | }; | |
163 | ||
b9193c1b | 164 | static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log) |
e7bf8249 JK |
165 | { |
166 | return log->len_used >= log->len_total - 1; | |
167 | } | |
168 | ||
77d2e05a MKL |
169 | static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) |
170 | { | |
171 | return log->level && log->ubuf && !bpf_verifier_log_full(log); | |
172 | } | |
173 | ||
cc8b0b92 AS |
174 | #define BPF_MAX_SUBPROGS 256 |
175 | ||
58e2af8b JK |
176 | /* single container for all structs |
177 | * one verifier_env per bpf_check() call | |
178 | */ | |
179 | struct bpf_verifier_env { | |
180 | struct bpf_prog *prog; /* eBPF program being verified */ | |
00176a34 | 181 | const struct bpf_verifier_ops *ops; |
58e2af8b JK |
182 | struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ |
183 | int stack_size; /* number of states to be processed */ | |
e07b98d9 | 184 | bool strict_alignment; /* perform strict pointer alignment checks */ |
638f5b90 | 185 | struct bpf_verifier_state *cur_state; /* current verifier state */ |
58e2af8b JK |
186 | struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ |
187 | struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ | |
188 | u32 used_map_cnt; /* number of used maps */ | |
189 | u32 id_gen; /* used to generate unique reg IDs */ | |
190 | bool allow_ptr_leaks; | |
191 | bool seen_direct_write; | |
192 | struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ | |
b9193c1b | 193 | struct bpf_verifier_log log; |
cc8b0b92 | 194 | u32 subprog_starts[BPF_MAX_SUBPROGS]; |
70a87ffe | 195 | /* computes the stack depth of each bpf function */ |
f4d7e40a | 196 | u16 subprog_stack_depth[BPF_MAX_SUBPROGS + 1]; |
cc8b0b92 | 197 | u32 subprog_cnt; |
58e2af8b JK |
198 | }; |
199 | ||
77d2e05a MKL |
200 | void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, |
201 | va_list args); | |
430e68d1 QM |
202 | __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, |
203 | const char *fmt, ...); | |
204 | ||
638f5b90 AS |
205 | static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) |
206 | { | |
f4d7e40a AS |
207 | struct bpf_verifier_state *cur = env->cur_state; |
208 | ||
209 | return cur->frame[cur->curframe]->regs; | |
638f5b90 AS |
210 | } |
211 | ||
ab3f0063 | 212 | int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env); |
cae1927c JK |
213 | int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env, |
214 | int insn_idx, int prev_insn_idx); | |
ab3f0063 | 215 | |
58e2af8b | 216 | #endif /* _LINUX_BPF_VERIFIER_H */ |