xref: /illumos-gate/usr/src/test/libc-tests/tests/random/arc4random_forksig.c (revision 9d12795f)

/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright (c) 2015, Joyent, Inc.
 */

/*
 * Tests to make sure that a parent and child do not get the same arc4random
 * state across a fork from a signal handler. This source file is used to make
 * two tests. One which initializes the data in advance, one of which does not.
 */

#include <stdlib.h>
#include <sys/mman.h>
#include <assert.h>
#include <errno.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <signal.h>
#include <strings.h>

typedef struct arc4_fork {
	uint32_t	af_parent;
	uint32_t	af_child;
	uint8_t		af_pbuf[4096];
	uint8_t		af_cbuf[4096];
} arc4_fork_t;

arc4_fork_t *fork_data;
static pid_t pid;

/*ARGSUSED*/
static void
siguser_fork(int sig, siginfo_t *sip, void *ucp)
{
	pid = fork();
}

int
main(void)
{
	int e, i, ret;
	pid_t child;
	struct sigaction sact;

	bzero(&sact, sizeof (struct sigaction));
	sact.sa_flags = SA_SIGINFO;
	sact.sa_sigaction = siguser_fork;

	(void) sigemptyset(&sact.sa_mask);
	ret = sigaction(SIGUSR1, &sact, NULL);
	assert(ret == 0);

#ifdef	ARC4_PREINIT
	(void) arc4random();
#endif

	fork_data = (arc4_fork_t *)mmap(NULL, sizeof (arc4_fork_t),
	    PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
	assert(fork_data != MAP_FAILED);

	ret = raise(SIGUSR1);
	assert(ret == 0);
	assert(pid != -1);
	if (pid == 0) {
		fork_data->af_child = arc4random();
		arc4random_buf(fork_data->af_cbuf, sizeof (fork_data->af_cbuf));
		exit(0);
	}

	fork_data->af_parent = arc4random();
	arc4random_buf(fork_data->af_pbuf, sizeof (fork_data->af_pbuf));
	do {
		child = wait(&e);
	} while (child == -1 && errno == EINTR);
	assert(child == pid);

	/* Now verify our data doesn't match */
	assert(fork_data->af_parent != fork_data->af_child);

	/*
	 * For the buffer here, we're mostly concerned that they aren't somehow
	 * getting the same stream.
	 */
	for (i = 0; i < sizeof (fork_data->af_pbuf); i++) {
		if (fork_data->af_pbuf[i] != fork_data->af_cbuf[i])
			break;
	}
	assert(i != sizeof (fork_data->af_pbuf));

	return (0);
}