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/*
* Copyright (c) 2012-2018 Zeex
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <stddef.h>
#include <unistd.h>
#include <sys/mman.h>
#include "subhook.h"
#ifdef SUBHOOK_APPLE
#include <mach/mach.h>
#endif
#define SUBHOOK_CODE_PROTECT_FLAGS (PROT_READ | PROT_WRITE | PROT_EXEC)
int subhook_unprotect(void *address, size_t size) {
long page_size;
void *aligned_address;
void *end;
size_t new_size;
page_size = sysconf(_SC_PAGESIZE);
aligned_address = (void *)((long)address & ~(page_size - 1));
/*
* Fix up the length - since we rounded the start address off, if a jump is
* right at the end of a page we could need to unprotect both.
*/
end = address + size;
new_size = end - aligned_address;
int error = mprotect(aligned_address, new_size, SUBHOOK_CODE_PROTECT_FLAGS);
#ifdef SUBHOOK_APPLE
if (error != 0) {
/* If mprotect fails, try to use VM_PROT_COPY with vm_protect. */
kern_return_t kret = vm_protect(mach_task_self(),
(unsigned long)aligned_address,
new_size,
0,
SUBHOOK_CODE_PROTECT_FLAGS | VM_PROT_COPY);
error = kret == KERN_SUCCESS ? 0 : -1;
}
#endif
return error;
}
void *subhook_alloc_code(void *target_address, size_t size) {
void *address;
(void)target_address;
address = mmap(NULL,
size,
SUBHOOK_CODE_PROTECT_FLAGS,
#if defined MAP_32BIT && !defined __APPLE__
MAP_32BIT |
#endif
MAP_PRIVATE | MAP_ANONYMOUS,
-1,
0);
return address == MAP_FAILED ? NULL : address;
}
int subhook_free_code(void *address, size_t size) {
if (address == NULL) {
return 0;
}
return munmap(address, size);
}
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