mirror of
https://github.com/adron-s/mtik_initrd_hacks.git
synced 2025-12-10 07:44:40 +01:00
101 lines
2.9 KiB
C
101 lines
2.9 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <string.h>
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void die(int code){
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fprintf(stderr, "Dieing with exit code = %d\n", code);
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exit(code);
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}
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static unsigned char data[64 * 1024 * 1024];
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/* kernel header is 20 bytes:
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kernel start magic(8 bytes) - 07 00 01 00 00 00 0A 04
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kernel size(4 bytes) - variable
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tail magic(3 bytes) - 00 78 01
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chunks header or splitter(5 bytes) - 00 00 80 FF 7F or something else(for last chunk)
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*/
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void *do_kernel_start_search(unsigned char *p, void *end){
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uint64_t *k;
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do{
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k = (void*)p;
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if(*k == 0x040A000000010007LLU){ //check for kernel start magic value
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k = (void *)k + 8 + 4; //to tail magic
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/* printf("0x%08lx: %02X %02X %02X, %016lX\n", ((void*)p - (void*)data),
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p[12], p[13], p[14], *k); */
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if(*k == 0x7FFF800000017800LL){ //check for tail and chunk splitter values
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return (void*)p + 15; //return pointer to first chinks splitter
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}
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}
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p = (void *)p + 1;
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}while((void*)p + 20 <= end);
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return NULL;
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}
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void *do_kernel_extract(unsigned char *p, void *end, char *file_name){
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int fd;
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fd = open(file_name, O_WRONLY | O_CREAT);
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size_t len;
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int count = 0;
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if(fd < 0)
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die(-11);
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do{
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//usually chunks are 32768 bytes in size
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if(p[4] == 0x7F && p[3] == 0xFF && p[2] == 0x80 && p[1] == 0x00 && p[0] == 0x00){
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//printf("%02X %02X %02X %02X %02X\n", p[4], p[3], p[2], p[1], p[0]);
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p += 5; //skip chinks splitter
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len = write(fd, p, 0x8000);
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//printf("writing chunk %d, len = %zd bytes\n", count, len);
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count++;
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if(len != 0x8000){
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fprintf(stderr, "write to result file '%s' len < 0x8000: %zd\n", file_name, len);
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break;
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}
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p += len;
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}else{ //but the last chunk may be less
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//fprintf(stderr, "UNKNOWN tail is: %zd bytes !!!\n", end - (void*)p);
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printf("%02X %02X %02X %02X %02X\n", p[4], p[3], p[2], p[1], p[0]);
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len = p[2] << 8 | p[1]; //try to extract current chunk len from chunk header
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p += 5; //skip chinks splitter
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if(len > end - (void*)p)
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len = end - (void*)p;
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//last chunk?
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len = write(fd, p, len);
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printf("last chunk len: %zd\n", len);
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count++;
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break;
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}
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}while((void*)p + 5 <= end);
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printf("Successfully writed %d chunks to '%s'\n", count, file_name);
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close(fd);
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}
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int main(int argc, char *argv[]){
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int fd;
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void *start;
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size_t len;
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if(argc !=3)
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die(-1);
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fd = open(argv[1], O_RDONLY);
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if(fd < 0)
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die(-2);
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memset(data, 0x0, sizeof(data));
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len = read(fd, data, sizeof(data));
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close(fd);
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if(len <= 0)
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die(-3);
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printf("Successfully readed %zd bytes\n", len);
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printf("Begin of search...\n");
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start = do_kernel_start_search(data, (void*)data + len);
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if(!start){
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fprintf(stderr, "Can't find kernel start magic(64 bits)\n");
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die(-4);
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}
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printf("...search is Ended\n");
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printf("kernel start offset is fount at: 0x%08lx\n", start - (void*)data);
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do_kernel_extract(start, (void*)data + len, argv[2]);
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return 0;
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}
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