readlink.cc

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2019 The FreeBSD Foundation
 *
 * This software was developed by BFF Storage Systems, LLC under sponsorship
 * from the FreeBSD Foundation.
 *
 * 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.
 */

extern "C" {
#include <sys/param.h>

#include <unistd.h>
}

#include "mockfs.hh"
#include "utils.hh"

using namespace testing;

class Readlink: public FuseTest {
public:
void expect_lookup(const char *relpath, uint64_t ino)
{
	FuseTest::expect_lookup(relpath, ino, S_IFLNK | 0777, 0, 1);
}
void expect_readlink(uint64_t ino, ProcessMockerT r)
{
	EXPECT_CALL(*m_mock, process(
		ResultOf([=](auto in) {
			return (in.header.opcode == FUSE_READLINK &&
				in.header.nodeid == ino);
		}, Eq(true)),
		_)
	).WillOnce(Invoke(r));
}

};

class PushSymlinksIn: public Readlink {
	virtual void SetUp() {
		m_push_symlinks_in = true;
		Readlink::SetUp();
	}
};

TEST_F(Readlink, eloop)
{
	const char FULLPATH[] = "mountpoint/src";
	const char RELPATH[] = "src";
	const uint64_t ino = 42;
	char buf[80];

	expect_lookup(RELPATH, ino);
	expect_readlink(ino, ReturnErrno(ELOOP));

	EXPECT_EQ(-1, readlink(FULLPATH, buf, sizeof(buf)));
	EXPECT_EQ(ELOOP, errno);
}

/*
 * If a malicious or buggy server returns a NUL in the FUSE_READLINK result, it
 * should be handled gracefully.
 * https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=274268
 */
TEST_F(Readlink, embedded_nul)
{
	const char FULLPATH[] = "mountpoint/src";
	const char RELPATH[] = "src";
	const char dst[] = "dst\0stuff";
	char buf[80];
	const uint64_t ino = 42;

	EXPECT_LOOKUP(FUSE_ROOT_ID, RELPATH)
	.WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto& out) {
		SET_OUT_HEADER_LEN(out, entry);
		out.body.entry.attr.mode = S_IFLNK | 0777;
		out.body.entry.nodeid = ino;
		out.body.entry.attr_valid = UINT64_MAX;
		out.body.entry.entry_valid = UINT64_MAX;
	})));

	EXPECT_CALL(*m_mock, process(
		ResultOf([=](auto in) {
			return (in.header.opcode == FUSE_READLINK &&
				in.header.nodeid == ino);
		}, Eq(true)),
		_)
	).WillRepeatedly(Invoke(ReturnImmediate([=](auto in __unused, auto& out) {
		memcpy(out.body.str, dst, sizeof(dst));
		out.header.len = sizeof(out.header) + sizeof(dst) + 1;
	})));

	EXPECT_EQ(-1, readlink(FULLPATH, buf, sizeof(buf)));
	EXPECT_EQ(EIO, errno);
	EXPECT_EQ(-1, access(FULLPATH, R_OK));
	EXPECT_EQ(EIO, errno);
}

TEST_F(Readlink, ok)
{
	const char FULLPATH[] = "mountpoint/src";
	const char RELPATH[] = "src";
	const char dst[] = "dst";
	const uint64_t ino = 42;
	char buf[80];

	expect_lookup(RELPATH, ino);
	expect_readlink(ino, ReturnImmediate([=](auto in __unused, auto& out) {
		strlcpy(out.body.str, dst, sizeof(out.body.str));
		out.header.len = sizeof(out.header) + strlen(dst) + 1;
	}));

	EXPECT_EQ(static_cast<ssize_t>(strlen(dst)) + 1,
		  readlink(FULLPATH, buf, sizeof(buf)));
	EXPECT_STREQ(dst, buf);
}

TEST_F(PushSymlinksIn, readlink)
{
	const char FULLPATH[] = "mountpoint/src";
	const char RELPATH[] = "src";
	const char dst[] = "/dst";
	const uint64_t ino = 42;
	char buf[MAXPATHLEN], wd[MAXPATHLEN], want[MAXPATHLEN];
	int len;

	expect_lookup(RELPATH, ino);
	expect_readlink(ino, ReturnImmediate([=](auto in __unused, auto& out) {
		strlcpy(out.body.str, dst, sizeof(out.body.str));
		out.header.len = sizeof(out.header) + strlen(dst) + 1;
	}));

	ASSERT_NE(nullptr, getcwd(wd, sizeof(wd))) << strerror(errno);
	len = snprintf(want, sizeof(want), "%s/mountpoint%s", wd, dst);
	ASSERT_LE(0, len) << strerror(errno);

	EXPECT_EQ(static_cast<ssize_t>(len) + 1,
		readlink(FULLPATH, buf, sizeof(buf)));
	EXPECT_STREQ(want, buf);
}