47 lines
1.7 KiB
C++
47 lines
1.7 KiB
C++
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#include <sys/mman.h>
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#include <libreborn/libreborn.h>
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#include "patch-internal.h"
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// Limit To 512 overwrite_calls() Uses
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#define CODE_BLOCK_SIZE 4096
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static unsigned char *code_block = NULL;
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#define CODE_SIZE 8
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static int code_block_remaining = CODE_BLOCK_SIZE;
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// Create Long Overwrite At Current Position
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static void long_overwrite(void *start, void *target) {
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unsigned char patch_data[4] = {0x04, 0xf0, 0x1f, 0xe5}; // "ldr pc, [pc, #-0x4]"
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_patch(NULL, -1, start, patch_data);
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_patch_address(NULL, -1, (void *) (((unsigned char *) start) + 4), target);
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}
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void *update_code_block(void *target) {
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// BL Instructions can only access a limited portion of memory.
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// So this allocates memory closer to the original instruction,
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// that when run, will jump into the actual target.
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if (code_block == NULL) {
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code_block = (unsigned char *) mmap((void *) 0x200000, CODE_BLOCK_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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if (code_block == MAP_FAILED) {
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ERR("Unable To Allocate Code Block: %s", strerror(errno));
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}
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DEBUG("Code Block Allocated At: 0x%08x", (uint32_t) code_block);
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// Store Segment
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segment_data data;
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data.start = code_block;
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data.end = (void *) (((uintptr_t) code_block) + CODE_BLOCK_SIZE);
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data.is_executable = true;
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data.is_writable = true;
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add_segment(data);
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}
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if (code_block_remaining < CODE_SIZE) {
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ERR("Maximum Amount Of overwrite_calls() Uses Reached");
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}
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long_overwrite(code_block, target);
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// Return
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return code_block;
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}
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void increment_code_block() {
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code_block = code_block + CODE_SIZE;
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code_block_remaining = code_block_remaining - CODE_SIZE;
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}
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