/*
 * seccomp example for x86 (32-bit and 64-bit) with BPF macros
 *
 * Copyright (c) 2012 The Chromium OS Authors <chromium-os-dev@chromium.org>
 * Authors:
 *  Will Drewry <wad@chromium.org>
 *  Kees Cook <keescook@chromium.org>
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#ifndef _SECCOMP_BPF_H_
#define _SECCOMP_BPF_H_

#define _GNU_SOURCE 1
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>

#include <sys/prctl.h>
#ifndef PR_SET_NO_NEW_PRIVS
# define PR_SET_NO_NEW_PRIVS 38
#endif

#include <linux/unistd.h>
#include <linux/audit.h>
#include <linux/filter.h>
#include <linux/seccomp.h>

#define syscall_nr (offsetof(struct seccomp_data, nr))
#define arch_nr (offsetof(struct seccomp_data, arch))
#define arg_offset_0 (offsetof(struct seccomp_data, args[0]))
#define arg_offset_1 (offsetof(struct seccomp_data, args[1]))
#define arg_offset_2 (offsetof(struct seccomp_data, args[2]))
#define arg_offset_3 (offsetof(struct seccomp_data, args[3]))
#define arg_offset_4 (offsetof(struct seccomp_data, args[4]))
#define arg_offset_5 (offsetof(struct seccomp_data, args[5]))

#if defined(__x86_64__)
#define SECCOMP_REG(_ctx, _reg) ((_ctx)->uc_mcontext.gregs[(_reg)])
#define SECCOMP_RESULT(_ctx)    SECCOMP_REG(_ctx, REG_RAX)
#define SECCOMP_SYSCALL(_ctx)   SECCOMP_REG(_ctx, REG_RAX)
#define SECCOMP_IP(_ctx)        SECCOMP_REG(_ctx, REG_RIP)
#define SECCOMP_PARM1(_ctx)     SECCOMP_REG(_ctx, REG_RDI)
#define SECCOMP_PARM2(_ctx)     SECCOMP_REG(_ctx, REG_RSI)
#define SECCOMP_PARM3(_ctx)     SECCOMP_REG(_ctx, REG_RDX)
#define SECCOMP_PARM4(_ctx)     SECCOMP_REG(_ctx, REG_R10)
#define SECCOMP_PARM5(_ctx)     SECCOMP_REG(_ctx, REG_R8)
#define SECCOMP_PARM6(_ctx)     SECCOMP_REG(_ctx, REG_R9)
# define REG_SYSCALL	REG_RAX
# define ARCH_NR	AUDIT_ARCH_X86_64
#else
# warning "Platform does not support seccomp filter yet"
# define REG_SYSCALL	0
# define ARCH_NR	0
#endif

#define VALIDATE_ARCHITECTURE \
	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, arch_nr), \
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ARCH_NR, 1, 0), \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)

#define EXAMINE_SYSCALL \
	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, syscall_nr)

#define ALLOW_SYSCALL(name) \
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_##name, 0, 1), \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW)

#define TRACE_OPENS_FOR_READS_ONLY(name, arg_index) \
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_##name, 0, 5), \
	BPF_STMT(BPF_LD+BPF_W+BPF_ABS, arg_offset_##arg_index), \
	BPF_STMT(BPF_ALU+BPF_AND+BPF_K, O_ACCMODE), \
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, O_RDONLY, 0, 1), \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_TRACE), \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)

#define TRACE_SYSCALL(name) \
	BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_##name, 0, 1), \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_TRACE)

#define KILL_PROCESS \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)

#define ALLOW_ALL \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW)

#define TRACE_ALL \
	BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_TRACE)

#endif /* _SECCOMP_BPF_H_ */