/*-
 * 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.
 */

/*
 * Tests for the "allow_other" mount option.  They must be in their own
 * file so they can be run as root
 */

extern "C" {
#include <sys/types.h>
#include <sys/extattr.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
}

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

using namespace testing;

const static char FULLPATH[] = "mountpoint/some_file.txt";
const static char RELPATH[] = "some_file.txt";

class NoAllowOther: public FuseTest {

public:
virtual void SetUp() {
        if (geteuid() != 0) {
                GTEST_SKIP() << "This test must be run as root";
        }

        FuseTest::SetUp();
}
};

class AllowOther: public NoAllowOther {

public:
virtual void SetUp() {
        m_allow_other = true;
        NoAllowOther::SetUp();
}
};

TEST_F(AllowOther, allowed)
{
        int status;

        fork(true, &status, [&] {
                        uint64_t ino = 42;

                        expect_lookup(RELPATH, ino, S_IFREG | 0644, 0, 1);
                        expect_open(ino, 0, 1);
                        expect_flush(ino, 1, ReturnErrno(0));
                        expect_release(ino, FH);
                }, []() {
                        int fd;

                        fd = open(FULLPATH, O_RDONLY);
                        if (fd < 0) {
                                perror("open");
                                return(1);
                        }

                        leak(fd);
                        return 0;
                }
        );
        ASSERT_EQ(0, WEXITSTATUS(status));
}

/* Check that fusefs uses the correct credentials for FUSE operations */
TEST_F(AllowOther, creds)
{
        int status;
        uid_t uid;
        gid_t gid;

        get_unprivileged_id(&uid, &gid);
        fork(true, &status, [=] {
                        EXPECT_CALL(*m_mock, process( ResultOf([=](auto in) {
                                return (in.header.opcode == FUSE_LOOKUP &&
                                        in.header.uid == uid &&
                                        in.header.gid == gid);
                                }, Eq(true)),
                                _)
                        ).Times(1)
                        .WillOnce(Invoke(ReturnErrno(ENOENT)));
                }, []() {
                        eaccess(FULLPATH, F_OK);
                        return 0;
                }
        );
        ASSERT_EQ(0, WEXITSTATUS(status));
}

/*
 * A variation of the Open.multiple_creds test showing how the bug can lead to a
 * privilege elevation.  The first process is privileged and opens a file only
 * visible to root.  The second process is unprivileged and shouldn't be able
 * to open the file, but does thanks to the bug
 */
TEST_F(AllowOther, privilege_escalation)
{
        int fd1, status;
        const static uint64_t ino = 42;
        const static uint64_t fh = 100;

        /* Fork a child to open the file with different credentials */
        fork(true, &status, [&] {

                expect_lookup(RELPATH, ino, S_IFREG | 0600, 0, 2);
                EXPECT_CALL(*m_mock, process(
                        ResultOf([=](auto in) {
                                return (in.header.opcode == FUSE_OPEN &&
                                        in.header.pid == (uint32_t)getpid() &&
                                        in.header.uid == (uint32_t)geteuid() &&
                                        in.header.nodeid == ino);
                        }, Eq(true)),
                        _)
                ).WillOnce(Invoke(
                        ReturnImmediate([](auto in __unused, auto& out) {
                        out.body.open.fh = fh;
                        out.header.len = sizeof(out.header);
                        SET_OUT_HEADER_LEN(out, open);
                })));

                EXPECT_CALL(*m_mock, process(
                        ResultOf([=](auto in) {
                                return (in.header.opcode == FUSE_OPEN &&
                                        in.header.pid != (uint32_t)getpid() &&
                                        in.header.uid != (uint32_t)geteuid() &&
                                        in.header.nodeid == ino);
                        }, Eq(true)),
                        _)
                ).Times(AnyNumber())
                .WillRepeatedly(Invoke(ReturnErrno(EPERM)));

                fd1 = open(FULLPATH, O_RDONLY);
                ASSERT_LE(0, fd1) << strerror(errno);
        }, [] {
                int fd0;

                fd0 = open(FULLPATH, O_RDONLY);
                if (fd0 >= 0) {
                        fprintf(stderr, "Privilege escalation!\n");
                        return 1;
                }
                if (errno != EPERM) {
                        fprintf(stderr, "Unexpected error %s\n",
                                strerror(errno));
                        return 1;
                }
                leak(fd0);
                return 0;
        }
        );
        ASSERT_EQ(0, WEXITSTATUS(status));
        leak(fd1);
}

TEST_F(NoAllowOther, disallowed)
{
        int status;

        fork(true, &status, [] {
                }, []() {
                        int fd;

                        fd = open(FULLPATH, O_RDONLY);
                        if (fd >= 0) {
                                fprintf(stderr, "open should've failed\n");
                                leak(fd);
                                return(1);
                        } else if (errno != EPERM) {
                                fprintf(stderr, "Unexpected error: %s\n",
                                        strerror(errno));
                                return(1);
                        }
                        return 0;
                }
        );
        ASSERT_EQ(0, WEXITSTATUS(status));
}

/* 
 * When -o allow_other is not used, users other than the owner aren't allowed
 * to open anything inside of the mount point, not just the mountpoint itself
 * This is a regression test for bug 237052
 */
TEST_F(NoAllowOther, disallowed_beneath_root)
{
        const static char RELPATH2[] = "other_dir";
        const static uint64_t ino = 42;
        const static uint64_t ino2 = 43;
        int dfd, status;

        expect_lookup(RELPATH, ino, S_IFDIR | 0755, 0, 1);
        EXPECT_LOOKUP(ino, RELPATH2)
        .WillRepeatedly(Invoke(ReturnImmediate([=](auto in __unused, auto& out) {
                SET_OUT_HEADER_LEN(out, entry);
                out.body.entry.attr.mode = S_IFREG | 0644;
                out.body.entry.nodeid = ino2;
                out.body.entry.attr.nlink = 1;
                out.body.entry.attr_valid = UINT64_MAX;
        })));
        expect_opendir(ino);
        dfd = open(FULLPATH, O_DIRECTORY);
        ASSERT_LE(0, dfd) << strerror(errno);

        fork(true, &status, [] {
                }, [&]() {
                        int fd;

                        fd = openat(dfd, RELPATH2, O_RDONLY);
                        if (fd >= 0) {
                                fprintf(stderr, "openat should've failed\n");
                                leak(fd);
                                return(1);
                        } else if (errno != EPERM) {
                                fprintf(stderr, "Unexpected error: %s\n",
                                        strerror(errno));
                                return(1);
                        }
                        return 0;
                }
        );
        ASSERT_EQ(0, WEXITSTATUS(status));

        leak(dfd);
}

/* 
 * Provide coverage for the extattr methods, which have a slightly different
 * code path
 */
TEST_F(NoAllowOther, setextattr)
{
        int ino = 42, status;

        fork(true, &status, [&] {
                        EXPECT_LOOKUP(FUSE_ROOT_ID, RELPATH)
                        .WillOnce(Invoke(
                        ReturnImmediate([=](auto in __unused, auto& out) {
                                SET_OUT_HEADER_LEN(out, entry);
                                out.body.entry.attr_valid = UINT64_MAX;
                                out.body.entry.entry_valid = UINT64_MAX;
                                out.body.entry.attr.mode = S_IFREG | 0644;
                                out.body.entry.nodeid = ino;
                        })));

                        /*
                         * lookup the file to get it into the cache.
                         * Otherwise, the unprivileged lookup will fail with
                         * EACCES
                         */
                        ASSERT_EQ(0, access(FULLPATH, F_OK)) << strerror(errno);
                }, [&]() {
                        const char value[] = "whatever";
                        ssize_t value_len = strlen(value) + 1;
                        int ns = EXTATTR_NAMESPACE_USER;
                        ssize_t r;

                        r = extattr_set_file(FULLPATH, ns, "foo",
                                (const void*)value, value_len);
                        if (r >= 0) {
                                fprintf(stderr, "should've failed\n");
                                return(1);
                        } else if (errno != EPERM) {
                                fprintf(stderr, "Unexpected error: %s\n",
                                        strerror(errno));
                                return(1);
                        }
                        return 0;
                }
        );
        ASSERT_EQ(0, WEXITSTATUS(status));
}