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February 19, 2016 07:17
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My totally working attempt at hooking 8 byte functions
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| #include "sys/mman.h" | |
| void tiny_hook(uint32_t* addr, uint32_t hook) { | |
| bool thumb = (uint32_t)addr & 1; | |
| if(thumb) | |
| addr = (uint32_t*) ((uint32_t) addr - 1); | |
| mprotect(addr, 9, PROT_READ | PROT_WRITE); | |
| *addr = (uint32_t) (thumb)? 0xF000F8DF : 0xE51FF008; // LDR PC, [PC] on Thumb and LDR PC, [PC, #-8] on ARM. | |
| *(addr + 1) = hook; | |
| mprotect(addr, 9, PROT_READ | PROT_EXEC); | |
| } |
Also decrementing addr for thumb before calling the first mprotect so that it changes write access to the same bytes as the second mprotect.
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There, fixed everything except the pagealigning for now.