264 lines
7.4 KiB
C
264 lines
7.4 KiB
C
/* 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 == __LITTLE_ENDIAN
|
|
#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)])
|
|
#elif __BYTE_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 == __LITTLE_ENDIAN
|
|
#define ENDIAN(_lo, _hi) _lo, _hi
|
|
#define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)
|
|
#elif __BYTE_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__ */
|