cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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map_populate.c (2484B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright (c) 2018 Dmitry Safonov, Arista Networks
      4 *
      5 * MAP_POPULATE | MAP_PRIVATE should COW VMA pages.
      6 */
      7
      8#define _GNU_SOURCE
      9#include <errno.h>
     10#include <fcntl.h>
     11#include <sys/mman.h>
     12#include <sys/socket.h>
     13#include <sys/types.h>
     14#include <sys/wait.h>
     15#include <stdio.h>
     16#include <stdlib.h>
     17#include <string.h>
     18#include <unistd.h>
     19
     20#ifndef MMAP_SZ
     21#define MMAP_SZ		4096
     22#endif
     23
     24#define BUG_ON(condition, description)					\
     25	do {								\
     26		if (condition) {					\
     27			fprintf(stderr, "[FAIL]\t%s:%d\t%s:%s\n", __func__, \
     28				__LINE__, (description), strerror(errno)); \
     29			exit(1);					\
     30		}							\
     31	} while (0)
     32
     33static int parent_f(int sock, unsigned long *smap, int child)
     34{
     35	int status, ret;
     36
     37	ret = read(sock, &status, sizeof(int));
     38	BUG_ON(ret <= 0, "read(sock)");
     39
     40	*smap = 0x22222BAD;
     41	ret = msync(smap, MMAP_SZ, MS_SYNC);
     42	BUG_ON(ret, "msync()");
     43
     44	ret = write(sock, &status, sizeof(int));
     45	BUG_ON(ret <= 0, "write(sock)");
     46
     47	waitpid(child, &status, 0);
     48	BUG_ON(!WIFEXITED(status), "child in unexpected state");
     49
     50	return WEXITSTATUS(status);
     51}
     52
     53static int child_f(int sock, unsigned long *smap, int fd)
     54{
     55	int ret, buf = 0;
     56
     57	smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
     58			MAP_PRIVATE | MAP_POPULATE, fd, 0);
     59	BUG_ON(smap == MAP_FAILED, "mmap()");
     60
     61	BUG_ON(*smap != 0xdeadbabe, "MAP_PRIVATE | MAP_POPULATE changed file");
     62
     63	ret = write(sock, &buf, sizeof(int));
     64	BUG_ON(ret <= 0, "write(sock)");
     65
     66	ret = read(sock, &buf, sizeof(int));
     67	BUG_ON(ret <= 0, "read(sock)");
     68
     69	BUG_ON(*smap == 0x22222BAD, "MAP_POPULATE didn't COW private page");
     70	BUG_ON(*smap != 0xdeadbabe, "mapping was corrupted");
     71
     72	return 0;
     73}
     74
     75int main(int argc, char **argv)
     76{
     77	int sock[2], child, ret;
     78	FILE *ftmp;
     79	unsigned long *smap;
     80
     81	ftmp = tmpfile();
     82	BUG_ON(ftmp == 0, "tmpfile()");
     83
     84	ret = ftruncate(fileno(ftmp), MMAP_SZ);
     85	BUG_ON(ret, "ftruncate()");
     86
     87	smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
     88			MAP_SHARED, fileno(ftmp), 0);
     89	BUG_ON(smap == MAP_FAILED, "mmap()");
     90
     91	*smap = 0xdeadbabe;
     92	/* Probably unnecessary, but let it be. */
     93	ret = msync(smap, MMAP_SZ, MS_SYNC);
     94	BUG_ON(ret, "msync()");
     95
     96	ret = socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sock);
     97	BUG_ON(ret, "socketpair()");
     98
     99	child = fork();
    100	BUG_ON(child == -1, "fork()");
    101
    102	if (child) {
    103		ret = close(sock[0]);
    104		BUG_ON(ret, "close()");
    105
    106		return parent_f(sock[1], smap, child);
    107	}
    108
    109	ret = close(sock[1]);
    110	BUG_ON(ret, "close()");
    111
    112	return child_f(sock[0], smap, fileno(ftmp));
    113}