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