debuggerd/crasher/crasher.cpp - android-core - Git at Google

 /*
  * Copyright 2006, The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "crasher"

 #include <assert.h>
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <pthread.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/mman.h>
 #include <sys/prctl.h>
 #include <unistd.h>

 // We test both kinds of logging.
 #include <android-base/logging.h>
 #include <log/log.h>

 #include "seccomp_policy.h"

 #if defined(STATIC_CRASHER)
 #include "debuggerd/handler.h"
 #endif

 #if defined(__arm__)
 // See https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt for details.
 #define __kuser_helper_version (*(int32_t*) 0xffff0ffc)
 typedef void * (__kuser_get_tls_t)(void);
 #define __kuser_get_tls (*(__kuser_get_tls_t*) 0xffff0fe0)
 typedef int (__kuser_cmpxchg_t)(int oldval, int newval, volatile int *ptr);
 #define __kuser_cmpxchg (*(__kuser_cmpxchg_t*) 0xffff0fc0)
 typedef void (__kuser_dmb_t)(void);
 #define __kuser_dmb (*(__kuser_dmb_t*) 0xffff0fa0)
 typedef int (__kuser_cmpxchg64_t)(const int64_t*, const int64_t*, volatile int64_t*);
 #define __kuser_cmpxchg64 (*(__kuser_cmpxchg64_t*) 0xffff0f60)
 #endif

 #define noinline __attribute__((__noinline__))

 // Avoid name mangling so that stacks are more readable.
 extern "C" {

 void crash1(void);
 void crashnostack(void);

 int do_action(const char* arg);

 noinline void maybe_abort() {
     if (time(0) != 42) {
         abort();
     }
 }

 char* smash_stack_dummy_buf;
 noinline void smash_stack_dummy_function(volatile int* plen) {
   smash_stack_dummy_buf[*plen] = 0;
 }

 // This must be marked with "__attribute__ ((noinline))", to ensure the
 // compiler generates the proper stack guards around this function.
 // Assign local array address to global variable to force stack guards.
 // Use another noinline function to corrupt the stack.
 noinline int smash_stack(volatile int* plen) {
     printf("%s: deliberately corrupting stack...\n", getprogname());

     char buf[128];
     smash_stack_dummy_buf = buf;
     // This should corrupt stack guards and make process abort.
     smash_stack_dummy_function(plen);
     return 0;
 }

 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Winfinite-recursion"

 void* global = 0; // So GCC doesn't optimize the tail recursion out of overflow_stack.

 noinline void overflow_stack(void* p) {
     void* buf[1];
     buf[0] = p;
     global = buf;
     overflow_stack(&buf);
 }

 #pragma clang diagnostic pop

 noinline void* thread_callback(void* raw_arg) {
     const char* arg = reinterpret_cast<const char*>(raw_arg);
     return reinterpret_cast<void*>(static_cast<uintptr_t>(do_action(arg)));
 }

 noinline int do_action_on_thread(const char* arg) {
     pthread_t t;
     pthread_create(&t, nullptr, thread_callback, const_cast<char*>(arg));
     void* result = nullptr;
     pthread_join(t, &result);
     return reinterpret_cast<uintptr_t>(result);
 }

 noinline int crash3(int a) {
     *reinterpret_cast<int*>(0xdead) = a;
     return a*4;
 }

 noinline int crash2(int a) {
     a = crash3(a) + 2;
     return a*3;
 }

 noinline int crash(int a) {
     a = crash2(a) + 1;
     return a*2;
 }

 noinline void abuse_heap() {
     char buf[16];
     free(buf); // GCC is smart enough to warn about this, but we're doing it deliberately.
 }

 noinline void sigsegv_non_null() {
     int* a = (int *)(&do_action);
     *a = 42;
 }

 noinline void fprintf_null() {
     fprintf(nullptr, "oops");
 }

 noinline void readdir_null() {
     readdir(nullptr);
 }

 noinline int strlen_null() {
     char* sneaky_null = nullptr;
     return strlen(sneaky_null);
 }

 static int usage() {
     fprintf(stderr, "usage: %s KIND\n", getprogname());
     fprintf(stderr, "\n");
     fprintf(stderr, "where KIND is:\n");
     fprintf(stderr, "  smash-stack           overwrite a -fstack-protector guard\n");
     fprintf(stderr, "  stack-overflow        recurse until the stack overflows\n");
     fprintf(stderr, "  nostack               crash with a NULL stack pointer\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "  heap-corruption       cause a libc abort by corrupting the heap\n");
     fprintf(stderr, "  heap-usage            cause a libc abort by abusing a heap function\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "  abort                 call abort()\n");
     fprintf(stderr, "  assert                call assert() without a function\n");
     fprintf(stderr, "  assert2               call assert() with a function\n");
     fprintf(stderr, "  exit                  call exit(1)\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "  fortify               fail a _FORTIFY_SOURCE check\n");
     fprintf(stderr, "  seccomp               fail a seccomp check\n");
 #if defined(__arm__)
     fprintf(stderr, "  kuser_helper_version  call kuser_helper_version\n");
     fprintf(stderr, "  kuser_get_tls         call kuser_get_tls\n");
     fprintf(stderr, "  kuser_cmpxchg         call kuser_cmpxchg\n");
     fprintf(stderr, "  kuser_memory_barrier  call kuser_memory_barrier\n");
     fprintf(stderr, "  kuser_cmpxchg64       call kuser_cmpxchg64\n");
 #endif
     fprintf(stderr, "\n");
     fprintf(stderr, "  LOG_ALWAYS_FATAL      call liblog LOG_ALWAYS_FATAL\n");
     fprintf(stderr, "  LOG_ALWAYS_FATAL_IF   call liblog LOG_ALWAYS_FATAL_IF\n");
     fprintf(stderr, "  LOG-FATAL             call libbase LOG(FATAL)\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "  SIGFPE                cause a SIGFPE\n");
     fprintf(stderr, "  SIGSEGV               cause a SIGSEGV at address 0x0 (synonym: crash)\n");
     fprintf(stderr, "  SIGSEGV-non-null      cause a SIGSEGV at a non-zero address\n");
     fprintf(stderr, "  SIGSEGV-unmapped      mmap/munmap a region of memory and then attempt to access it\n");
     fprintf(stderr, "  SIGTRAP               cause a SIGTRAP\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "  fprintf-NULL          pass a null pointer to fprintf\n");
     fprintf(stderr, "  readdir-NULL          pass a null pointer to readdir\n");
     fprintf(stderr, "  strlen-NULL           pass a null pointer to strlen\n");
     fprintf(stderr, "  pthread_join-NULL     pass a null pointer to pthread_join\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "  no_new_privs          set PR_SET_NO_NEW_PRIVS and then abort\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "prefix any of the above with 'thread-' to run on a new thread\n");
     fprintf(stderr, "prefix any of the above with 'exhaustfd-' to exhaust\n");
     fprintf(stderr, "all available file descriptors before crashing.\n");
     fprintf(stderr, "prefix any of the above with 'wait-' to wait until input is received on stdin\n");

     return EXIT_FAILURE;
 }

 noinline int do_action(const char* arg) {
     // Prefixes.
     if (!strncmp(arg, "wait-", strlen("wait-"))) {
       char buf[1];
       TEMP_FAILURE_RETRY(read(STDIN_FILENO, buf, sizeof(buf)));
       return do_action(arg + strlen("wait-"));
     } else if (!strncmp(arg, "exhaustfd-", strlen("exhaustfd-"))) {
       errno = 0;
       while (errno != EMFILE) {
         open("/dev/null", O_RDONLY);
       }
       return do_action(arg + strlen("exhaustfd-"));
     } else if (!strncmp(arg, "thread-", strlen("thread-"))) {
         return do_action_on_thread(arg + strlen("thread-"));
     }

     // Actions.
     if (!strcasecmp(arg, "SIGSEGV-non-null")) {
         sigsegv_non_null();
     } else if (!strcasecmp(arg, "smash-stack")) {
         volatile int len = 128;
         return smash_stack(&len);
     } else if (!strcasecmp(arg, "stack-overflow")) {
         overflow_stack(nullptr);
     } else if (!strcasecmp(arg, "nostack")) {
         crashnostack();
     } else if (!strcasecmp(arg, "exit")) {
         exit(1);
     } else if (!strcasecmp(arg, "crash") || !strcmp(arg, "SIGSEGV")) {
         return crash(42);
     } else if (!strcasecmp(arg, "abort")) {
         maybe_abort();
     } else if (!strcasecmp(arg, "assert")) {
         __assert("some_file.c", 123, "false");
     } else if (!strcasecmp(arg, "assert2")) {
         __assert2("some_file.c", 123, "some_function", "false");
     } else if (!strcasecmp(arg, "fortify")) {
         char buf[10];
         __read_chk(-1, buf, 32, 10);
         while (true) pause();
     } else if (!strcasecmp(arg, "LOG(FATAL)")) {
         LOG(FATAL) << "hello " << 123;
     } else if (!strcasecmp(arg, "LOG_ALWAYS_FATAL")) {
         LOG_ALWAYS_FATAL("hello %s", "world");
     } else if (!strcasecmp(arg, "LOG_ALWAYS_FATAL_IF")) {
         LOG_ALWAYS_FATAL_IF(true, "hello %s", "world");
     } else if (!strcasecmp(arg, "SIGFPE")) {
         raise(SIGFPE);
         return EXIT_SUCCESS;
     } else if (!strcasecmp(arg, "SIGTRAP")) {
         raise(SIGTRAP);
         return EXIT_SUCCESS;
     } else if (!strcasecmp(arg, "fprintf-NULL")) {
         fprintf_null();
     } else if (!strcasecmp(arg, "readdir-NULL")) {
         readdir_null();
     } else if (!strcasecmp(arg, "strlen-NULL")) {
         return strlen_null();
     } else if (!strcasecmp(arg, "pthread_join-NULL")) {
         return pthread_join(0, nullptr);
     } else if (!strcasecmp(arg, "heap-usage")) {
         abuse_heap();
     } else if (!strcasecmp(arg, "SIGSEGV-unmapped")) {
         char* map = reinterpret_cast<char*>(mmap(nullptr, sizeof(int), PROT_READ | PROT_WRITE,
                                                  MAP_SHARED | MAP_ANONYMOUS, -1, 0));
         munmap(map, sizeof(int));
         map[0] = '8';
     } else if (!strcasecmp(arg, "seccomp")) {
         set_seccomp_filter();
         syscall(99999);
 #if defined(__arm__)
     } else if (!strcasecmp(arg, "kuser_helper_version")) {
         return __kuser_helper_version;
     } else if (!strcasecmp(arg, "kuser_get_tls")) {
         return !__kuser_get_tls();
     } else if (!strcasecmp(arg, "kuser_cmpxchg")) {
         return __kuser_cmpxchg(0, 0, 0);
     } else if (!strcasecmp(arg, "kuser_memory_barrier")) {
         __kuser_dmb();
     } else if (!strcasecmp(arg, "kuser_cmpxchg64")) {
         return __kuser_cmpxchg64(0, 0, 0);
 #endif
     } else if (!strcasecmp(arg, "no_new_privs")) {
         if (prctl(PR_SET_NO_NEW_PRIVS, 1) != 0) {
           fprintf(stderr, "prctl(PR_SET_NO_NEW_PRIVS, 1) failed: %s\n", strerror(errno));
           return EXIT_SUCCESS;
         }
         abort();
     } else {
         return usage();
     }

     fprintf(stderr, "%s: exiting normally!\n", getprogname());
     return EXIT_SUCCESS;
 }

 int main(int argc, char** argv) {
 #if defined(STATIC_CRASHER)
     debuggerd_callbacks_t callbacks = {
       .get_abort_message = []() {
         static struct {
           size_t size;
           char msg[32];
         } msg;

         msg.size = strlen("dummy abort message");
         memcpy(msg.msg, "dummy abort message", strlen("dummy abort message"));
         return reinterpret_cast<abort_msg_t*>(&msg);
       },
       .post_dump = nullptr
     };
     debuggerd_init(&callbacks);
 #endif

     if (argc == 1) crash1();
     else if (argc == 2) return do_action(argv[1]);

     return usage();
 }

 };
	/*
	* Copyright 2006, The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "crasher"

	#include <assert.h>
	#include <dirent.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <pthread.h>
	#include <signal.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/mman.h>
	#include <sys/prctl.h>
	#include <unistd.h>

	// We test both kinds of logging.
	#include <android-base/logging.h>
	#include <log/log.h>

	#include "seccomp_policy.h"

	#if defined(STATIC_CRASHER)
	#include "debuggerd/handler.h"
	#endif

	#if defined(__arm__)
	// See https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt for details.
	#define __kuser_helper_version ((int32_t) 0xffff0ffc)
	typedef void * (__kuser_get_tls_t)(void);
	#define __kuser_get_tls ((__kuser_get_tls_t) 0xffff0fe0)
	typedef int (__kuser_cmpxchg_t)(int oldval, int newval, volatile int *ptr);
	#define __kuser_cmpxchg ((__kuser_cmpxchg_t) 0xffff0fc0)
	typedef void (__kuser_dmb_t)(void);
	#define __kuser_dmb ((__kuser_dmb_t) 0xffff0fa0)
	typedef int (__kuser_cmpxchg64_t)(const int64_t, const int64_t, volatile int64_t*);
	#define __kuser_cmpxchg64 ((__kuser_cmpxchg64_t) 0xffff0f60)
	#endif

	#define noinline __attribute__((__noinline__))

	// Avoid name mangling so that stacks are more readable.
	extern "C" {

	void crash1(void);
	void crashnostack(void);

	int do_action(const char* arg);

	noinline void maybe_abort() {
	if (time(0) != 42) {
	abort();
	}
	}

	char* smash_stack_dummy_buf;
	noinline void smash_stack_dummy_function(volatile int* plen) {
	smash_stack_dummy_buf[*plen] = 0;
	}

	// This must be marked with "__attribute__ ((noinline))", to ensure the
	// compiler generates the proper stack guards around this function.
	// Assign local array address to global variable to force stack guards.
	// Use another noinline function to corrupt the stack.
	noinline int smash_stack(volatile int* plen) {
	printf("%s: deliberately corrupting stack...\n", getprogname());

	char buf[128];
	smash_stack_dummy_buf = buf;
	// This should corrupt stack guards and make process abort.
	smash_stack_dummy_function(plen);
	return 0;
	}

	#pragma clang diagnostic push
	#pragma clang diagnostic ignored "-Winfinite-recursion"

	void* global = 0; // So GCC doesn't optimize the tail recursion out of overflow_stack.

	noinline void overflow_stack(void* p) {
	void* buf[1];
	buf[0] = p;
	global = buf;
	overflow_stack(&buf);
	}

	#pragma clang diagnostic pop

	noinline void* thread_callback(void* raw_arg) {
	const char* arg = reinterpret_cast<const char*>(raw_arg);
	return reinterpret_cast<void*>(static_cast<uintptr_t>(do_action(arg)));
	}

	noinline int do_action_on_thread(const char* arg) {
	pthread_t t;
	pthread_create(&t, nullptr, thread_callback, const_cast<char*>(arg));
	void* result = nullptr;
	pthread_join(t, &result);
	return reinterpret_cast<uintptr_t>(result);
	}

	noinline int crash3(int a) {
	reinterpret_cast<int>(0xdead) = a;
	return a*4;
	}

	noinline int crash2(int a) {
	a = crash3(a) + 2;
	return a*3;
	}

	noinline int crash(int a) {
	a = crash2(a) + 1;
	return a*2;
	}

	noinline void abuse_heap() {
	char buf[16];
	free(buf); // GCC is smart enough to warn about this, but we're doing it deliberately.
	}

	noinline void sigsegv_non_null() {
	int* a = (int *)(&do_action);
	*a = 42;
	}

	noinline void fprintf_null() {
	fprintf(nullptr, "oops");
	}

	noinline void readdir_null() {
	readdir(nullptr);
	}

	noinline int strlen_null() {
	char* sneaky_null = nullptr;
	return strlen(sneaky_null);
	}

	static int usage() {
	fprintf(stderr, "usage: %s KIND\n", getprogname());
	fprintf(stderr, "\n");
	fprintf(stderr, "where KIND is:\n");
	fprintf(stderr, " smash-stack overwrite a -fstack-protector guard\n");
	fprintf(stderr, " stack-overflow recurse until the stack overflows\n");
	fprintf(stderr, " nostack crash with a NULL stack pointer\n");
	fprintf(stderr, "\n");
	fprintf(stderr, " heap-corruption cause a libc abort by corrupting the heap\n");
	fprintf(stderr, " heap-usage cause a libc abort by abusing a heap function\n");
	fprintf(stderr, "\n");
	fprintf(stderr, " abort call abort()\n");
	fprintf(stderr, " assert call assert() without a function\n");
	fprintf(stderr, " assert2 call assert() with a function\n");
	fprintf(stderr, " exit call exit(1)\n");
	fprintf(stderr, "\n");
	fprintf(stderr, " fortify fail a _FORTIFY_SOURCE check\n");
	fprintf(stderr, " seccomp fail a seccomp check\n");
	#if defined(__arm__)
	fprintf(stderr, " kuser_helper_version call kuser_helper_version\n");
	fprintf(stderr, " kuser_get_tls call kuser_get_tls\n");
	fprintf(stderr, " kuser_cmpxchg call kuser_cmpxchg\n");
	fprintf(stderr, " kuser_memory_barrier call kuser_memory_barrier\n");
	fprintf(stderr, " kuser_cmpxchg64 call kuser_cmpxchg64\n");
	#endif
	fprintf(stderr, "\n");
	fprintf(stderr, " LOG_ALWAYS_FATAL call liblog LOG_ALWAYS_FATAL\n");
	fprintf(stderr, " LOG_ALWAYS_FATAL_IF call liblog LOG_ALWAYS_FATAL_IF\n");
	fprintf(stderr, " LOG-FATAL call libbase LOG(FATAL)\n");
	fprintf(stderr, "\n");
	fprintf(stderr, " SIGFPE cause a SIGFPE\n");
	fprintf(stderr, " SIGSEGV cause a SIGSEGV at address 0x0 (synonym: crash)\n");
	fprintf(stderr, " SIGSEGV-non-null cause a SIGSEGV at a non-zero address\n");
	fprintf(stderr, " SIGSEGV-unmapped mmap/munmap a region of memory and then attempt to access it\n");
	fprintf(stderr, " SIGTRAP cause a SIGTRAP\n");
	fprintf(stderr, "\n");
	fprintf(stderr, " fprintf-NULL pass a null pointer to fprintf\n");
	fprintf(stderr, " readdir-NULL pass a null pointer to readdir\n");
	fprintf(stderr, " strlen-NULL pass a null pointer to strlen\n");
	fprintf(stderr, " pthread_join-NULL pass a null pointer to pthread_join\n");
	fprintf(stderr, "\n");
	fprintf(stderr, " no_new_privs set PR_SET_NO_NEW_PRIVS and then abort\n");
	fprintf(stderr, "\n");
	fprintf(stderr, "prefix any of the above with 'thread-' to run on a new thread\n");
	fprintf(stderr, "prefix any of the above with 'exhaustfd-' to exhaust\n");
	fprintf(stderr, "all available file descriptors before crashing.\n");
	fprintf(stderr, "prefix any of the above with 'wait-' to wait until input is received on stdin\n");

	return EXIT_FAILURE;
	}

	noinline int do_action(const char* arg) {
	// Prefixes.
	if (!strncmp(arg, "wait-", strlen("wait-"))) {
	char buf[1];
	TEMP_FAILURE_RETRY(read(STDIN_FILENO, buf, sizeof(buf)));
	return do_action(arg + strlen("wait-"));
	} else if (!strncmp(arg, "exhaustfd-", strlen("exhaustfd-"))) {
	errno = 0;
	while (errno != EMFILE) {
	open("/dev/null", O_RDONLY);
	}
	return do_action(arg + strlen("exhaustfd-"));
	} else if (!strncmp(arg, "thread-", strlen("thread-"))) {
	return do_action_on_thread(arg + strlen("thread-"));
	}

	// Actions.
	if (!strcasecmp(arg, "SIGSEGV-non-null")) {
	sigsegv_non_null();
	} else if (!strcasecmp(arg, "smash-stack")) {
	volatile int len = 128;
	return smash_stack(&len);
	} else if (!strcasecmp(arg, "stack-overflow")) {
	overflow_stack(nullptr);
	} else if (!strcasecmp(arg, "nostack")) {
	crashnostack();
	} else if (!strcasecmp(arg, "exit")) {
	exit(1);
	} else if (!strcasecmp(arg, "crash") \|\| !strcmp(arg, "SIGSEGV")) {
	return crash(42);
	} else if (!strcasecmp(arg, "abort")) {
	maybe_abort();
	} else if (!strcasecmp(arg, "assert")) {
	__assert("some_file.c", 123, "false");
	} else if (!strcasecmp(arg, "assert2")) {
	__assert2("some_file.c", 123, "some_function", "false");
	} else if (!strcasecmp(arg, "fortify")) {
	char buf[10];
	__read_chk(-1, buf, 32, 10);
	while (true) pause();
	} else if (!strcasecmp(arg, "LOG(FATAL)")) {
	LOG(FATAL) << "hello " << 123;
	} else if (!strcasecmp(arg, "LOG_ALWAYS_FATAL")) {
	LOG_ALWAYS_FATAL("hello %s", "world");
	} else if (!strcasecmp(arg, "LOG_ALWAYS_FATAL_IF")) {
	LOG_ALWAYS_FATAL_IF(true, "hello %s", "world");
	} else if (!strcasecmp(arg, "SIGFPE")) {
	raise(SIGFPE);
	return EXIT_SUCCESS;
	} else if (!strcasecmp(arg, "SIGTRAP")) {
	raise(SIGTRAP);
	return EXIT_SUCCESS;
	} else if (!strcasecmp(arg, "fprintf-NULL")) {
	fprintf_null();
	} else if (!strcasecmp(arg, "readdir-NULL")) {
	readdir_null();
	} else if (!strcasecmp(arg, "strlen-NULL")) {
	return strlen_null();
	} else if (!strcasecmp(arg, "pthread_join-NULL")) {
	return pthread_join(0, nullptr);
	} else if (!strcasecmp(arg, "heap-usage")) {
	abuse_heap();
	} else if (!strcasecmp(arg, "SIGSEGV-unmapped")) {
	char* map = reinterpret_cast<char*>(mmap(nullptr, sizeof(int), PROT_READ \| PROT_WRITE,
	MAP_SHARED \| MAP_ANONYMOUS, -1, 0));
	munmap(map, sizeof(int));
	map[0] = '8';
	} else if (!strcasecmp(arg, "seccomp")) {
	set_seccomp_filter();
	syscall(99999);
	#if defined(__arm__)
	} else if (!strcasecmp(arg, "kuser_helper_version")) {
	return __kuser_helper_version;
	} else if (!strcasecmp(arg, "kuser_get_tls")) {
	return !__kuser_get_tls();
	} else if (!strcasecmp(arg, "kuser_cmpxchg")) {
	return __kuser_cmpxchg(0, 0, 0);
	} else if (!strcasecmp(arg, "kuser_memory_barrier")) {
	__kuser_dmb();
	} else if (!strcasecmp(arg, "kuser_cmpxchg64")) {
	return __kuser_cmpxchg64(0, 0, 0);
	#endif
	} else if (!strcasecmp(arg, "no_new_privs")) {
	if (prctl(PR_SET_NO_NEW_PRIVS, 1) != 0) {
	fprintf(stderr, "prctl(PR_SET_NO_NEW_PRIVS, 1) failed: %s\n", strerror(errno));
	return EXIT_SUCCESS;
	}
	abort();
	} else {
	return usage();
	}

	fprintf(stderr, "%s: exiting normally!\n", getprogname());
	return EXIT_SUCCESS;
	}

	int main(int argc, char** argv) {
	#if defined(STATIC_CRASHER)
	debuggerd_callbacks_t callbacks = {
	.get_abort_message = []() {
	static struct {
	size_t size;
	char msg[32];
	} msg;

	msg.size = strlen("dummy abort message");
	memcpy(msg.msg, "dummy abort message", strlen("dummy abort message"));
	return reinterpret_cast<abort_msg_t*>(&msg);
	},
	.post_dump = nullptr
	};
	debuggerd_init(&callbacks);
	#endif

	if (argc == 1) crash1();
	else if (argc == 2) return do_action(argv[1]);

	return usage();
	}

	};