xref: /third_party/ltp/testcases/kernel/syscalls/fanotify/fanotify18.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) 2018 Matthew Bobrowski. All Rights Reserved.
 *
 * Started by Matthew Bobrowski <mbobrowski@mbobrowski.org>
 */

/*\
 * [Description]
 * This set of tests is to ensure that the unprivileged listener feature of
 * fanotify is functioning as expected. The objective this test case file
 * is to validate whether any forbidden flags that are passed by an
 * unprivileged user return the correct error result.
 */

#define _GNU_SOURCE
#include "config.h"

#include <pwd.h>
#include <stdio.h>
#include <errno.h>
#include "tst_test.h"

#ifdef HAVE_SYS_FANOTIFY_H
#include "fanotify.h"

/*
 * This is a set of intialization flags that are not permitted to be used by an
 * unprivileged user. Thus, if supplied, either EPERM or EINVAL should be
 * returned to the calling process respectively.
 */
#define DISALLOWED_INIT_FLAGS	(FAN_UNLIMITED_QUEUE | FAN_UNLIMITED_MARKS | \
				 FAN_CLASS_CONTENT | FAN_CLASS_PRE_CONTENT | \
				 FAN_REPORT_TID)

/*
 * This is a set of mark flags that are not permitted to be used with an
 * unprivileged listener.
 */
#define DISALLOWED_MARK_FLAGS	(FAN_MARK_MOUNT | FAN_MARK_FILESYSTEM)

#define MOUNT_PATH	"fs_mnt"
#define TEST_FILE	MOUNT_PATH "/testfile"

static int fd_notify;

static struct test_case_t {
	const char *name;
	unsigned long init_flags;
	unsigned long mark_flags;
	unsigned long long mark_mask;
} test_cases[] = {
	{
		"init_flags: missing FAN_REPORT_FID",
		FAN_CLASS_NOTIF,
		0, 0
	},
	{
		"init_flags: FAN_CLASS_CONTENT",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_CLASS_CONTENT,
		0, 0
	},
	{
		"init_flags: FAN_CLASS_PRE_CONTENT",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_CLASS_PRE_CONTENT,
		0, 0
	},
	{
		"init_flags: FAN_UNLIMITED_QUEUE",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_UNLIMITED_QUEUE,
		0, 0
	},
	{
		"init_flags: FAN_UNLIMITED_MARKS",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_UNLIMITED_MARKS,
		0, 0
	},
	{
		"init_flags: FAN_REPORT_TID",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_REPORT_TID,
		0, 0
	},
	{
		"init_flags: FAN_CLASS_NOTIF, "
		"mark_flags: FAN_MARK_ADD | FAN_MARK_MOUNT",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_CLASS_NOTIF,
		FAN_MARK_ADD | FAN_MARK_MOUNT, FAN_ALL_EVENTS
	},
	{
		"init_flags: FAN_CLASS_NOTIF, "
		"mark_flags: FAN_MARK_ADD | FAN_MARK_FILESYSTEM",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_CLASS_NOTIF,
		FAN_MARK_ADD | FAN_MARK_FILESYSTEM, FAN_ALL_EVENTS
	},
	{
		"init_flags: FAN_CLASS_NOTIF, "
		"mark_flags: FAN_MARK_ADD, "
		"mark_mask: FAN_ALL_EVENTS",
		FANOTIFY_REQUIRED_USER_INIT_FLAGS | FAN_CLASS_NOTIF,
		FAN_MARK_ADD, FAN_ALL_EVENTS
	}
};

static void test_fanotify(unsigned int n)
{
	struct test_case_t *tc = &test_cases[n];

	tst_res(TINFO, "Test #%d %s", n, tc->name);

	/* Initialize fanotify */
	fd_notify = fanotify_init(tc->init_flags, O_RDONLY);

	if (fd_notify < 0) {
		if (errno == EPERM &&
		    ((tc->init_flags & DISALLOWED_INIT_FLAGS) ||
		     (tc->init_flags & FANOTIFY_REQUIRED_USER_INIT_FLAGS) !=
		      FANOTIFY_REQUIRED_USER_INIT_FLAGS)) {
			tst_res(TPASS, "Received result EPERM, as expected");
			return;
		}

		tst_brk(TBROK | TERRNO,
			"fanotify_init(0x%lx, O_RDONLY) failed",
			tc->init_flags);
	}

	/* Attempt to place mark on object */
	if (fanotify_mark(fd_notify, tc->mark_flags, tc->mark_mask, AT_FDCWD,
				TEST_FILE) < 0) {
		/*
		 * Unprivileged users are only allowed to mark inodes and not
		 * permitted to use access permissions
		 */
		if (errno == EPERM &&
			(tc->mark_flags & DISALLOWED_MARK_FLAGS ||
			 tc->mark_mask & FAN_ALL_PERM_EVENTS)) {
			tst_res(TPASS, "Received result EPERM, as expected");
			goto out;
		}

		tst_brk(TBROK | TERRNO,
			"fanotify_mark(%d, %lx, %llx, AT_FDCWD, %s) "
			"failed",
			fd_notify,
			tc->mark_flags,
			tc->mark_mask,
			TEST_FILE);
	}

	tst_res(TPASS,
		"fanotify_init() and fanotify_mark() returned successfully, "
		"as expected");

out:
	SAFE_CLOSE(fd_notify);
}

static void setup(void)
{
	int fd;
	struct passwd *nobody;

	SAFE_TOUCH(TEST_FILE, 0666, NULL);

	/* Check for kernel fanotify support */
	REQUIRE_FANOTIFY_INIT_FLAGS_SUPPORTED_ON_FS(FAN_REPORT_FID, TEST_FILE);

	/* Relinquish privileged user */
	if (geteuid() == 0) {
		tst_res(TINFO,
			"Running as privileged user, revoking permissions.");
		nobody = SAFE_GETPWNAM("nobody");
		SAFE_SETUID(nobody->pw_uid);
	}

	/* Check for unprivileged fanotify support */
	fd = fanotify_init(FANOTIFY_REQUIRED_USER_INIT_FLAGS, O_RDONLY);
	if (fd < 0) {
		tst_brk(TCONF,
			"unprivileged fanotify not supported by kernel?");
	}
	SAFE_CLOSE(fd);
}

static void cleanup(void)
{
	if (fd_notify > 0)
		SAFE_CLOSE(fd_notify);
}

static struct tst_test test = {
	.test = test_fanotify,
	.tcnt = ARRAY_SIZE(test_cases),
	.setup = setup,
	.cleanup = cleanup,
	.needs_root = 1,
	.mount_device = 1,
	.mntpoint = MOUNT_PATH,
};

#else
	TST_TEST_TCONF("system doesn't have required fanotify support");
#endif