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	 e87eac9273
			
		
	
	
		e87eac9273
		
	
	
	
	
		
			
			This achieves two things: - Programs can now intentionally perform arbitrary syscalls by calling syscall(). This allows us to work on things like syscall fuzzing. - It restricts the ability of userspace to make syscalls to a single 4KB page of code. In order to call the kernel directly, an attacker must now locate this page and call through it.
		
			
				
	
	
		
			95 lines
		
	
	
	
		
			2.9 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			95 lines
		
	
	
	
		
			2.9 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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|  * All rights reserved.
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|  *
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|  * Redistribution and use in source and binary forms, with or without
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|  * modification, are permitted provided that the following conditions are met:
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|  *
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|  * 1. Redistributions of source code must retain the above copyright notice, this
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|  *    list of conditions and the following disclaimer.
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|  *
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|  * 2. Redistributions in binary form must reproduce the above copyright notice,
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|  *    this list of conditions and the following disclaimer in the documentation
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|  *    and/or other materials provided with the distribution.
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|  *
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|  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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|  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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|  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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|  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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|  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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|  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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|  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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|  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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|  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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|  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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|  */
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| 
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| #include <errno.h>
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| #include <fcntl.h>
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| #include <stdarg.h>
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| #include <string.h>
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| #include <syscall.h>
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| 
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| extern "C" {
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| 
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| int fcntl(int fd, int cmd, ...)
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| {
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|     va_list ap;
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|     va_start(ap, cmd);
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|     u32 extra_arg = va_arg(ap, u32);
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|     int rc = syscall(SC_fcntl, fd, cmd, extra_arg);
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|     va_end(ap);
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|     __RETURN_WITH_ERRNO(rc, rc, -1);
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| }
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| 
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| int watch_file(const char* path, size_t path_length)
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| {
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|     int rc = syscall(SC_watch_file, path, path_length);
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|     __RETURN_WITH_ERRNO(rc, rc, -1);
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| }
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| 
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| int creat(const char* path, mode_t mode)
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| {
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|     return open(path, O_CREAT | O_WRONLY | O_TRUNC, mode);
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| }
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| 
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| int open(const char* path, int options, ...)
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| {
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|     if (!path) {
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|         errno = EFAULT;
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|         return -1;
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|     }
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|     auto path_length = strlen(path);
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|     if (path_length > INT32_MAX) {
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|         errno = EINVAL;
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|         return -1;
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|     }
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|     va_list ap;
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|     va_start(ap, options);
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|     auto mode = (mode_t)va_arg(ap, unsigned);
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|     va_end(ap);
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|     Syscall::SC_open_params params { AT_FDCWD, { path, path_length }, options, mode };
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|     int rc = syscall(SC_open, ¶ms);
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|     __RETURN_WITH_ERRNO(rc, rc, -1);
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| }
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| 
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| int openat(int dirfd, const char* path, int options, ...)
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| {
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|     if (!path) {
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|         errno = EFAULT;
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|         return -1;
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|     }
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|     auto path_length = strlen(path);
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|     if (path_length > INT32_MAX) {
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|         errno = EINVAL;
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|         return -1;
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|     }
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|     va_list ap;
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|     va_start(ap, options);
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|     auto mode = (mode_t)va_arg(ap, unsigned);
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|     va_end(ap);
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|     Syscall::SC_open_params params { dirfd, { path, path_length }, options, mode };
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|     int rc = syscall(SC_open, ¶ms);
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|     __RETURN_WITH_ERRNO(rc, rc, -1);
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| }
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| }
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