/*-
 * Copyright (c) 2014 EMC Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <err.h>
#include <fcntl.h>
#include <kvm.h>
#include <limits.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>
#include <atf-c.h>

enum {
	NL_NPROCS,
	NL_MAXPROC,
	NL_MARKER
};

static struct {
	int order;
	const char *name;
} namelist[] = {
	{ NL_NPROCS, "_nprocs" },
	{ NL_MAXPROC, "_maxproc" },
	{ NL_MARKER, "" },
};
#define NNAMES	(sizeof(namelist) / sizeof(*namelist))
static struct nlist nl[NNAMES];

#define MULTIUSERFUZZ 5

void
t2(void)
{
	pid_t p;

	for (;;) {
		if ((p = fork()) == 0) {
			sleep(2);
			_exit(0);
		}
		if (p == -1)
			break;
	}
}

void
t1(int priv)
{
	pid_t p;
	struct passwd *pw;

	if ((p = fork()) == 0) {
		if ((pw = getpwnam("nobody")) == NULL)
			err(1, "no such user: nobody");

		if (priv == 0) {
			if (setgroups(1, &pw->pw_gid) ||
			    setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
			    seteuid(pw->pw_uid) || setuid(pw->pw_uid)) 
				err(1, "Can't drop privileges to \"nobody\"");
		}
		endpwent();

		t2();
		_exit(0);
	}
	waitpid(p, NULL, 0);
}

int
getprocs(void)
{
	kvm_t *kd;
	char *nlistf;
	char *memf;
	char buf[_POSIX2_LINE_MAX];
	int i;
	int nprocs, maxproc;

	nlistf = memf = NULL;
	for (i = 0; i < (int)NNAMES; i++)
		nl[namelist[i].order].n_name = strdup(namelist[i].name);

	if ((kd = kvm_openfiles(nlistf, memf, NULL, O_RDONLY, buf)) == NULL)
		errx(1, "kvm_openfile(%s, %s): %s", nlistf, memf, buf);
	if (kvm_nlist(kd, nl) == -1)
		errx(1, "kvm_nlist: %s", kvm_geterr(kd));
	if (kvm_read(kd, nl[NL_NPROCS].n_value, &nprocs,
	    sizeof(nprocs)) != sizeof(nprocs))
		errx(1, "kvm_read(): %s", kvm_geterr(kd));
	if (kvm_read(kd, nl[NL_MAXPROC].n_value, &maxproc,
	    sizeof(maxproc)) != sizeof(maxproc))
		errx(1, "kvm_read(): %s", kvm_geterr(kd));
	fprintf(stderr, "%d/%d (%d left)\n",
	    nprocs, maxproc, maxproc - nprocs - 1);
	kvm_close(kd);

	return (maxproc - nprocs - 1);
}

ATF_TC(checkmaxproc);
ATF_TC_HEAD(checkmaxproc, tc)
{
        atf_tc_set_md_var(tc, "require.user", "root");
	atf_tc_set_md_var(tc, "descr",
	    "Check proc limit for unprivileged users");
}
ATF_TC_BODY(checkmaxproc, tc)
{
	int i, n;

	n = getprocs();
	for (i = 0; i < n / 10 * 8; i++) {
		if (fork() == 0) {
			sleep(2);
			_exit(0);
		}
	}

	t1(0);
	ATF_REQUIRE(getprocs() >= 10 - MULTIUSERFUZZ);
}


ATF_TP_ADD_TCS(tp)
{

        ATF_TP_ADD_TC(tp, checkmaxproc);

        return atf_no_error();
}