Commit | Line | Data |
---|---|---|
b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
8ac270d1 WD |
2 | /* |
3 | * Example wrapper around BPF macros. | |
4 | * | |
5 | * Copyright (c) 2012 The Chromium OS Authors <chromium-os-dev@chromium.org> | |
6 | * Author: Will Drewry <wad@chromium.org> | |
7 | * | |
8 | * The code may be used by anyone for any purpose, | |
9 | * and can serve as a starting point for developing | |
10 | * applications using prctl(PR_SET_SECCOMP, 2, ...). | |
11 | * | |
12 | * No guarantees are provided with respect to the correctness | |
13 | * or functionality of this code. | |
14 | */ | |
15 | #ifndef __BPF_HELPER_H__ | |
16 | #define __BPF_HELPER_H__ | |
17 | ||
18 | #include <asm/bitsperlong.h> /* for __BITS_PER_LONG */ | |
19 | #include <endian.h> | |
20 | #include <linux/filter.h> | |
21 | #include <linux/seccomp.h> /* for seccomp_data */ | |
22 | #include <linux/types.h> | |
23 | #include <linux/unistd.h> | |
24 | #include <stddef.h> | |
25 | ||
26 | #define BPF_LABELS_MAX 256 | |
27 | struct bpf_labels { | |
28 | int count; | |
29 | struct __bpf_label { | |
30 | const char *label; | |
31 | __u32 location; | |
32 | } labels[BPF_LABELS_MAX]; | |
33 | }; | |
34 | ||
35 | int bpf_resolve_jumps(struct bpf_labels *labels, | |
36 | struct sock_filter *filter, size_t count); | |
37 | __u32 seccomp_bpf_label(struct bpf_labels *labels, const char *label); | |
38 | void seccomp_bpf_print(struct sock_filter *filter, size_t count); | |
39 | ||
40 | #define JUMP_JT 0xff | |
41 | #define JUMP_JF 0xff | |
42 | #define LABEL_JT 0xfe | |
43 | #define LABEL_JF 0xfe | |
44 | ||
45 | #define ALLOW \ | |
46 | BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW) | |
47 | #define DENY \ | |
48 | BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL) | |
49 | #define JUMP(labels, label) \ | |
50 | BPF_JUMP(BPF_JMP+BPF_JA, FIND_LABEL((labels), (label)), \ | |
51 | JUMP_JT, JUMP_JF) | |
52 | #define LABEL(labels, label) \ | |
53 | BPF_JUMP(BPF_JMP+BPF_JA, FIND_LABEL((labels), (label)), \ | |
54 | LABEL_JT, LABEL_JF) | |
55 | #define SYSCALL(nr, jt) \ | |
56 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (nr), 0, 1), \ | |
57 | jt | |
58 | ||
59 | /* Lame, but just an example */ | |
60 | #define FIND_LABEL(labels, label) seccomp_bpf_label((labels), #label) | |
61 | ||
62 | #define EXPAND(...) __VA_ARGS__ | |
de4bb3b9 HC |
63 | |
64 | /* Ensure that we load the logically correct offset. */ | |
65 | #if __BYTE_ORDER == __LITTLE_ENDIAN | |
66 | #define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) | |
67 | #elif __BYTE_ORDER == __BIG_ENDIAN | |
68 | #define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32) | |
69 | #else | |
70 | #error "Unknown endianness" | |
71 | #endif | |
72 | ||
8ac270d1 WD |
73 | /* Map all width-sensitive operations */ |
74 | #if __BITS_PER_LONG == 32 | |
75 | ||
76 | #define JEQ(x, jt) JEQ32(x, EXPAND(jt)) | |
77 | #define JNE(x, jt) JNE32(x, EXPAND(jt)) | |
78 | #define JGT(x, jt) JGT32(x, EXPAND(jt)) | |
79 | #define JLT(x, jt) JLT32(x, EXPAND(jt)) | |
80 | #define JGE(x, jt) JGE32(x, EXPAND(jt)) | |
81 | #define JLE(x, jt) JLE32(x, EXPAND(jt)) | |
82 | #define JA(x, jt) JA32(x, EXPAND(jt)) | |
83 | #define ARG(i) ARG_32(i) | |
8ac270d1 WD |
84 | |
85 | #elif __BITS_PER_LONG == 64 | |
86 | ||
87 | /* Ensure that we load the logically correct offset. */ | |
88 | #if __BYTE_ORDER == __LITTLE_ENDIAN | |
89 | #define ENDIAN(_lo, _hi) _lo, _hi | |
8ac270d1 WD |
90 | #define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32) |
91 | #elif __BYTE_ORDER == __BIG_ENDIAN | |
92 | #define ENDIAN(_lo, _hi) _hi, _lo | |
8ac270d1 | 93 | #define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) |
8ac270d1 WD |
94 | #endif |
95 | ||
96 | union arg64 { | |
97 | struct { | |
98 | __u32 ENDIAN(lo32, hi32); | |
99 | }; | |
100 | __u64 u64; | |
101 | }; | |
102 | ||
103 | #define JEQ(x, jt) \ | |
104 | JEQ64(((union arg64){.u64 = (x)}).lo32, \ | |
105 | ((union arg64){.u64 = (x)}).hi32, \ | |
106 | EXPAND(jt)) | |
107 | #define JGT(x, jt) \ | |
108 | JGT64(((union arg64){.u64 = (x)}).lo32, \ | |
109 | ((union arg64){.u64 = (x)}).hi32, \ | |
110 | EXPAND(jt)) | |
111 | #define JGE(x, jt) \ | |
112 | JGE64(((union arg64){.u64 = (x)}).lo32, \ | |
113 | ((union arg64){.u64 = (x)}).hi32, \ | |
114 | EXPAND(jt)) | |
115 | #define JNE(x, jt) \ | |
116 | JNE64(((union arg64){.u64 = (x)}).lo32, \ | |
117 | ((union arg64){.u64 = (x)}).hi32, \ | |
118 | EXPAND(jt)) | |
119 | #define JLT(x, jt) \ | |
120 | JLT64(((union arg64){.u64 = (x)}).lo32, \ | |
121 | ((union arg64){.u64 = (x)}).hi32, \ | |
122 | EXPAND(jt)) | |
123 | #define JLE(x, jt) \ | |
124 | JLE64(((union arg64){.u64 = (x)}).lo32, \ | |
125 | ((union arg64){.u64 = (x)}).hi32, \ | |
126 | EXPAND(jt)) | |
127 | ||
128 | #define JA(x, jt) \ | |
129 | JA64(((union arg64){.u64 = (x)}).lo32, \ | |
130 | ((union arg64){.u64 = (x)}).hi32, \ | |
131 | EXPAND(jt)) | |
132 | #define ARG(i) ARG_64(i) | |
133 | ||
134 | #else | |
135 | #error __BITS_PER_LONG value unusable. | |
136 | #endif | |
137 | ||
138 | /* Loads the arg into A */ | |
139 | #define ARG_32(idx) \ | |
140 | BPF_STMT(BPF_LD+BPF_W+BPF_ABS, LO_ARG(idx)) | |
141 | ||
916cafdc | 142 | /* Loads lo into M[0] and hi into M[1] and A */ |
8ac270d1 WD |
143 | #define ARG_64(idx) \ |
144 | BPF_STMT(BPF_LD+BPF_W+BPF_ABS, LO_ARG(idx)), \ | |
145 | BPF_STMT(BPF_ST, 0), /* lo -> M[0] */ \ | |
146 | BPF_STMT(BPF_LD+BPF_W+BPF_ABS, HI_ARG(idx)), \ | |
147 | BPF_STMT(BPF_ST, 1) /* hi -> M[1] */ | |
148 | ||
149 | #define JEQ32(value, jt) \ | |
150 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (value), 0, 1), \ | |
151 | jt | |
152 | ||
153 | #define JNE32(value, jt) \ | |
154 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (value), 1, 0), \ | |
155 | jt | |
156 | ||
916cafdc MS |
157 | #define JA32(value, jt) \ |
158 | BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (value), 0, 1), \ | |
159 | jt | |
160 | ||
161 | #define JGE32(value, jt) \ | |
162 | BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 0, 1), \ | |
163 | jt | |
164 | ||
165 | #define JGT32(value, jt) \ | |
166 | BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 0, 1), \ | |
167 | jt | |
168 | ||
169 | #define JLE32(value, jt) \ | |
170 | BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 1, 0), \ | |
171 | jt | |
172 | ||
173 | #define JLT32(value, jt) \ | |
174 | BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 1, 0), \ | |
175 | jt | |
176 | ||
177 | /* | |
178 | * All the JXX64 checks assume lo is saved in M[0] and hi is saved in both | |
179 | * A and M[1]. This invariant is kept by restoring A if necessary. | |
180 | */ | |
8ac270d1 | 181 | #define JEQ64(lo, hi, jt) \ |
916cafdc | 182 | /* if (hi != arg.hi) goto NOMATCH; */ \ |
8ac270d1 WD |
183 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \ |
184 | BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \ | |
916cafdc | 185 | /* if (lo != arg.lo) goto NOMATCH; */ \ |
8ac270d1 | 186 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (lo), 0, 2), \ |
916cafdc | 187 | BPF_STMT(BPF_LD+BPF_MEM, 1), \ |
8ac270d1 | 188 | jt, \ |
916cafdc | 189 | BPF_STMT(BPF_LD+BPF_MEM, 1) |
8ac270d1 WD |
190 | |
191 | #define JNE64(lo, hi, jt) \ | |
916cafdc MS |
192 | /* if (hi != arg.hi) goto MATCH; */ \ |
193 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 3), \ | |
194 | BPF_STMT(BPF_LD+BPF_MEM, 0), \ | |
195 | /* if (lo != arg.lo) goto MATCH; */ \ | |
8ac270d1 | 196 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (lo), 2, 0), \ |
916cafdc | 197 | BPF_STMT(BPF_LD+BPF_MEM, 1), \ |
8ac270d1 | 198 | jt, \ |
916cafdc | 199 | BPF_STMT(BPF_LD+BPF_MEM, 1) |
8ac270d1 WD |
200 | |
201 | #define JA64(lo, hi, jt) \ | |
916cafdc | 202 | /* if (hi & arg.hi) goto MATCH; */ \ |
8ac270d1 | 203 | BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (hi), 3, 0), \ |
916cafdc MS |
204 | BPF_STMT(BPF_LD+BPF_MEM, 0), \ |
205 | /* if (lo & arg.lo) goto MATCH; */ \ | |
8ac270d1 | 206 | BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (lo), 0, 2), \ |
916cafdc | 207 | BPF_STMT(BPF_LD+BPF_MEM, 1), \ |
8ac270d1 | 208 | jt, \ |
916cafdc | 209 | BPF_STMT(BPF_LD+BPF_MEM, 1) |
8ac270d1 | 210 | |
8ac270d1 | 211 | #define JGE64(lo, hi, jt) \ |
916cafdc | 212 | /* if (hi > arg.hi) goto MATCH; */ \ |
8ac270d1 | 213 | BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (hi), 4, 0), \ |
916cafdc | 214 | /* if (hi != arg.hi) goto NOMATCH; */ \ |
8ac270d1 | 215 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \ |
916cafdc MS |
216 | BPF_STMT(BPF_LD+BPF_MEM, 0), \ |
217 | /* if (lo >= arg.lo) goto MATCH; */ \ | |
8ac270d1 | 218 | BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (lo), 0, 2), \ |
916cafdc | 219 | BPF_STMT(BPF_LD+BPF_MEM, 1), \ |
8ac270d1 | 220 | jt, \ |
916cafdc | 221 | BPF_STMT(BPF_LD+BPF_MEM, 1) |
8ac270d1 | 222 | |
8ac270d1 | 223 | #define JGT64(lo, hi, jt) \ |
916cafdc | 224 | /* if (hi > arg.hi) goto MATCH; */ \ |
8ac270d1 | 225 | BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (hi), 4, 0), \ |
916cafdc | 226 | /* if (hi != arg.hi) goto NOMATCH; */ \ |
8ac270d1 | 227 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \ |
916cafdc MS |
228 | BPF_STMT(BPF_LD+BPF_MEM, 0), \ |
229 | /* if (lo > arg.lo) goto MATCH; */ \ | |
8ac270d1 | 230 | BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (lo), 0, 2), \ |
916cafdc | 231 | BPF_STMT(BPF_LD+BPF_MEM, 1), \ |
8ac270d1 | 232 | jt, \ |
916cafdc | 233 | BPF_STMT(BPF_LD+BPF_MEM, 1) |
8ac270d1 WD |
234 | |
235 | #define JLE64(lo, hi, jt) \ | |
916cafdc MS |
236 | /* if (hi < arg.hi) goto MATCH; */ \ |
237 | BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (hi), 0, 4), \ | |
238 | /* if (hi != arg.hi) goto NOMATCH; */ \ | |
239 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \ | |
240 | BPF_STMT(BPF_LD+BPF_MEM, 0), \ | |
241 | /* if (lo <= arg.lo) goto MATCH; */ \ | |
8ac270d1 | 242 | BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (lo), 2, 0), \ |
916cafdc MS |
243 | BPF_STMT(BPF_LD+BPF_MEM, 1), \ |
244 | jt, \ | |
245 | BPF_STMT(BPF_LD+BPF_MEM, 1) | |
246 | ||
247 | #define JLT64(lo, hi, jt) \ | |
248 | /* if (hi < arg.hi) goto MATCH; */ \ | |
249 | BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (hi), 0, 4), \ | |
250 | /* if (hi != arg.hi) goto NOMATCH; */ \ | |
251 | BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \ | |
252 | BPF_STMT(BPF_LD+BPF_MEM, 0), \ | |
253 | /* if (lo < arg.lo) goto MATCH; */ \ | |
254 | BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (lo), 2, 0), \ | |
255 | BPF_STMT(BPF_LD+BPF_MEM, 1), \ | |
8ac270d1 | 256 | jt, \ |
916cafdc | 257 | BPF_STMT(BPF_LD+BPF_MEM, 1) |
8ac270d1 WD |
258 | |
259 | #define LOAD_SYSCALL_NR \ | |
260 | BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \ | |
261 | offsetof(struct seccomp_data, nr)) | |
262 | ||
263 | #endif /* __BPF_HELPER_H__ */ |