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1/* SPDX-License-Identifier: GPL-2.0 */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 developing10 * applications using prctl(PR_SET_SECCOMP, 2, ...).11 *12 * No guarantees are provided with respect to the correctness13 * 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 25627struct bpf_labels {28 int count;29 struct __bpf_label {30 const char *label;31 __u32 location;32 } labels[BPF_LABELS_MAX];33};34 35int 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);38void seccomp_bpf_print(struct sock_filter *filter, size_t count);39 40#define JUMP_JT 0xff41#define JUMP_JF 0xff42#define LABEL_JT 0xfe43#define LABEL_JF 0xfe44 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 jt58 59/* Lame, but just an example */60#define FIND_LABEL(labels, label) seccomp_bpf_label((labels), #label)61 62#define EXPAND(...) __VA_ARGS__63 64/* Ensure that we load the logically correct offset. */65#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__66#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)])67#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__68#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)69#else70#error "Unknown endianness"71#endif72 73/* Map all width-sensitive operations */74#if __BITS_PER_LONG == 3275 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)84 85#elif __BITS_PER_LONG == 6486 87/* Ensure that we load the logically correct offset. */88#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__89#define ENDIAN(_lo, _hi) _lo, _hi90#define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)91#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__92#define ENDIAN(_lo, _hi) _hi, _lo93#define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)])94#endif95 96union 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#else135#error __BITS_PER_LONG value unusable.136#endif137 138/* Loads the arg into A */139#define ARG_32(idx) \140 BPF_STMT(BPF_LD+BPF_W+BPF_ABS, LO_ARG(idx))141 142/* Loads lo into M[0] and hi into M[1] and A */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 jt152 153#define JNE32(value, jt) \154 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (value), 1, 0), \155 jt156 157#define JA32(value, jt) \158 BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (value), 0, 1), \159 jt160 161#define JGE32(value, jt) \162 BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 0, 1), \163 jt164 165#define JGT32(value, jt) \166 BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 0, 1), \167 jt168 169#define JLE32(value, jt) \170 BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 1, 0), \171 jt172 173#define JLT32(value, jt) \174 BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 1, 0), \175 jt176 177/*178 * All the JXX64 checks assume lo is saved in M[0] and hi is saved in both179 * A and M[1]. This invariant is kept by restoring A if necessary.180 */181#define JEQ64(lo, hi, jt) \182 /* if (hi != arg.hi) goto NOMATCH; */ \183 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \184 BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \185 /* if (lo != arg.lo) goto NOMATCH; */ \186 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (lo), 0, 2), \187 BPF_STMT(BPF_LD+BPF_MEM, 1), \188 jt, \189 BPF_STMT(BPF_LD+BPF_MEM, 1)190 191#define JNE64(lo, hi, jt) \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; */ \196 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (lo), 2, 0), \197 BPF_STMT(BPF_LD+BPF_MEM, 1), \198 jt, \199 BPF_STMT(BPF_LD+BPF_MEM, 1)200 201#define JA64(lo, hi, jt) \202 /* if (hi & arg.hi) goto MATCH; */ \203 BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (hi), 3, 0), \204 BPF_STMT(BPF_LD+BPF_MEM, 0), \205 /* if (lo & arg.lo) goto MATCH; */ \206 BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (lo), 0, 2), \207 BPF_STMT(BPF_LD+BPF_MEM, 1), \208 jt, \209 BPF_STMT(BPF_LD+BPF_MEM, 1)210 211#define JGE64(lo, hi, jt) \212 /* if (hi > arg.hi) goto MATCH; */ \213 BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (hi), 4, 0), \214 /* if (hi != arg.hi) goto NOMATCH; */ \215 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \216 BPF_STMT(BPF_LD+BPF_MEM, 0), \217 /* if (lo >= arg.lo) goto MATCH; */ \218 BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (lo), 0, 2), \219 BPF_STMT(BPF_LD+BPF_MEM, 1), \220 jt, \221 BPF_STMT(BPF_LD+BPF_MEM, 1)222 223#define JGT64(lo, hi, jt) \224 /* if (hi > arg.hi) goto MATCH; */ \225 BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (hi), 4, 0), \226 /* if (hi != arg.hi) goto NOMATCH; */ \227 BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \228 BPF_STMT(BPF_LD+BPF_MEM, 0), \229 /* if (lo > arg.lo) goto MATCH; */ \230 BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (lo), 0, 2), \231 BPF_STMT(BPF_LD+BPF_MEM, 1), \232 jt, \233 BPF_STMT(BPF_LD+BPF_MEM, 1)234 235#define JLE64(lo, hi, jt) \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; */ \242 BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (lo), 2, 0), \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), \256 jt, \257 BPF_STMT(BPF_LD+BPF_MEM, 1)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__ */264