cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

urandom_read.c (1985B)

      1#include <stdbool.h>
      2#include <stdio.h>
      3#include <unistd.h>
      4#include <errno.h>
      5#include <sys/types.h>
      6#include <sys/stat.h>
      7#include <fcntl.h>
      8#include <stdlib.h>
      9#include <signal.h>
     10
     11#define _SDT_HAS_SEMAPHORES 1
     12#include "sdt.h"
     13
     14#define SEC(name) __attribute__((section(name), used))
     15
     16#define BUF_SIZE 256
     17
     18/* defined in urandom_read_aux.c */
     19void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz);
     20/* these are coming from urandom_read_lib{1,2}.c */
     21void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz);
     22void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz);
     23
     24unsigned short urand_read_with_sema_semaphore SEC(".probes");
     25
     26static __attribute__((noinline))
     27void urandom_read(int fd, int count)
     28{
     29	char buf[BUF_SIZE];
     30	int i;
     31
     32	for (i = 0; i < count; ++i) {
     33		read(fd, buf, BUF_SIZE);
     34
     35		/* trigger USDTs defined in executable itself */
     36		urand_read_without_sema(i, count, BUF_SIZE);
     37		STAP_PROBE3(urand, read_with_sema, i, count, BUF_SIZE);
     38
     39		/* trigger USDTs defined in shared lib */
     40		urandlib_read_without_sema(i, count, BUF_SIZE);
     41		urandlib_read_with_sema(i, count, BUF_SIZE);
     42	}
     43}
     44
     45static volatile bool parent_ready;
     46
     47static void handle_sigpipe(int sig)
     48{
     49	parent_ready = true;
     50}
     51
     52int main(int argc, char *argv[])
     53{
     54	int fd = open("/dev/urandom", O_RDONLY);
     55	int count = 4;
     56	bool report_pid = false;
     57
     58	if (fd < 0)
     59		return 1;
     60
     61	if (argc >= 2)
     62		count = atoi(argv[1]);
     63	if (argc >= 3) {
     64		report_pid = true;
     65		/* install SIGPIPE handler to catch when parent closes their
     66		 * end of the pipe (on the other side of our stdout)
     67		 */
     68		signal(SIGPIPE, handle_sigpipe);
     69	}
     70
     71	/* report PID and wait for parent process to send us "signal" by
     72	 * closing stdout
     73	 */
     74	if (report_pid) {
     75		while (!parent_ready) {
     76			fprintf(stdout, "%d\n", getpid());
     77			fflush(stdout);
     78		}
     79		/* at this point stdout is closed, parent process knows our
     80		 * PID and is ready to trace us
     81		 */
     82	}
     83
     84	urandom_read(fd, count);
     85
     86	close(fd);
     87	return 0;
     88}