too aggressive on seccomp cleanup

experimental/webtry/seccomp_bpf.h

 /*
  * 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.
  *
  * A stripped down version of the file found in this tutorial: http://outflux.net/teach-seccomp/.
  */
 #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>
+#ifdef HAVE_LINUX_SECCOMP_H
+# include <linux/seccomp.h>
+#endif
+#ifndef SECCOMP_MODE_FILTER
+# define SECCOMP_MODE_FILTER             2 /* uses user-supplied filter. */
+# define SECCOMP_RET_KILL      0x00000000U /* kill the task immediately */
+# define SECCOMP_RET_TRAP      0x00030000U /* disallow and force a SIGSYS */
+# define SECCOMP_RET_ALLOW     0x7fff0000U /* allow */
+struct seccomp_data {
+    int nr;
+    __u32 arch;
+    __u64 instruction_pointer;
+    __u64 args[6];
+};
+#endif
+#ifndef SYS_SECCOMP
+# define SYS_SECCOMP 1
+#endif
 
 #define syscall_nr (offsetof(struct seccomp_data, nr))
 
 #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 KILL_PROCESS \
         BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)
 
 #endif /* _SECCOMP_BPF_H_ */