// Copyright 2018 The gVisor Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <sys/mount.h> #include <sys/stat.h> #include <unistd.h> #include <functional> #include <memory> #include <string> #include <vector> #include "gmock/gmock.h" #include "gtest/gtest.h" #include "absl/strings/string_view.h" #include "absl/time/time.h" #include "test/util/capability_util.h" #include "test/util/file_descriptor.h" #include "test/util/fs_util.h" #include "test/util/mount_util.h" #include "test/util/multiprocess_util.h" #include "test/util/posix_error.h" #include "test/util/temp_path.h" #include "test/util/test_util.h" #include "test/util/thread_util.h" namespace gvisor { namespace testing { namespace { TEST(MountTest, MountBadFilesystem) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); // Linux expects a valid target before it checks the file system name. auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); EXPECT_THAT(mount("", dir.path().c_str(), "foobar", 0, ""), SyscallFailsWithErrno(ENODEV)); } TEST(MountTest, MountInvalidTarget) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = NewTempAbsPath(); EXPECT_THAT(mount("", dir.c_str(), "tmpfs", 0, ""), SyscallFailsWithErrno(ENOENT)); } TEST(MountTest, MountPermDenied) { // Clear CAP_SYS_ADMIN. if (ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))) { EXPECT_NO_ERRNO(SetCapability(CAP_SYS_ADMIN, false)); } // Linux expects a valid target before checking capability. auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); EXPECT_THAT(mount("", dir.path().c_str(), "", 0, ""), SyscallFailsWithErrno(EPERM)); } TEST(MountTest, UmountPermDenied) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const mount = ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "tmpfs", 0, "", 0)); // Drop privileges in another thread, so we can still unmount the mounted // directory. ScopedThread([&]() { EXPECT_NO_ERRNO(SetCapability(CAP_SYS_ADMIN, false)); EXPECT_THAT(umount(dir.path().c_str()), SyscallFailsWithErrno(EPERM)); }); } TEST(MountTest, MountOverBusy) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const fd = ASSERT_NO_ERRNO_AND_VALUE( Open(JoinPath(dir.path(), "foo"), O_CREAT | O_RDWR, 0777)); // Should be able to mount over a busy directory. ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "tmpfs", 0, "", 0)); } TEST(MountTest, OpenFileBusy) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const mount = ASSERT_NO_ERRNO_AND_VALUE( Mount("", dir.path(), "tmpfs", 0, "mode=0700", 0)); auto const fd = ASSERT_NO_ERRNO_AND_VALUE( Open(JoinPath(dir.path(), "foo"), O_CREAT | O_RDWR, 0777)); // An open file should prevent unmounting. EXPECT_THAT(umount(dir.path().c_str()), SyscallFailsWithErrno(EBUSY)); } TEST(MountTest, UmountDetach) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); // structure: // // dir (mount point) // subdir // file // // We show that we can walk around in the mount after detach-unmount dir. // // We show that even though dir is unreachable from outside the mount, we can // still reach dir's (former) parent! auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); const struct stat before = ASSERT_NO_ERRNO_AND_VALUE(Stat(dir.path())); auto mount = ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "tmpfs", 0, "mode=0700", /* umountflags= */ MNT_DETACH)); const struct stat after = ASSERT_NO_ERRNO_AND_VALUE(Stat(dir.path())); EXPECT_NE(before.st_ino, after.st_ino); // Create files in the new mount. constexpr char kContents[] = "no no no"; auto const subdir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDirIn(dir.path())); auto const file = ASSERT_NO_ERRNO_AND_VALUE( TempPath::CreateFileWith(dir.path(), kContents, 0777)); auto const dir_fd = ASSERT_NO_ERRNO_AND_VALUE(Open(subdir.path(), O_RDONLY | O_DIRECTORY)); auto const fd = ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_RDONLY)); // Unmount the tmpfs. mount.Release()(); const struct stat after2 = ASSERT_NO_ERRNO_AND_VALUE(Stat(dir.path())); EXPECT_EQ(before.st_ino, after2.st_ino); // Can still read file after unmounting. std::vector<char> buf(sizeof(kContents)); EXPECT_THAT(ReadFd(fd.get(), buf.data(), buf.size()), SyscallSucceeds()); // Walk to dir. auto const mounted_dir = ASSERT_NO_ERRNO_AND_VALUE( OpenAt(dir_fd.get(), "..", O_DIRECTORY | O_RDONLY)); // Walk to dir/file. auto const fd_again = ASSERT_NO_ERRNO_AND_VALUE( OpenAt(mounted_dir.get(), std::string(Basename(file.path())), O_RDONLY)); std::vector<char> buf2(sizeof(kContents)); EXPECT_THAT(ReadFd(fd_again.get(), buf2.data(), buf2.size()), SyscallSucceeds()); EXPECT_EQ(buf, buf2); // Walking outside the unmounted realm should still work, too! auto const dir_parent = ASSERT_NO_ERRNO_AND_VALUE( OpenAt(mounted_dir.get(), "..", O_DIRECTORY | O_RDONLY)); } TEST(MountTest, ActiveSubmountBusy) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const mount1 = ASSERT_NO_ERRNO_AND_VALUE( Mount("", dir.path(), "tmpfs", 0, "mode=0700", 0)); auto const dir2 = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDirIn(dir.path())); auto const mount2 = ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir2.path(), "tmpfs", 0, "", 0)); // Since dir now has an active submount, should not be able to unmount. EXPECT_THAT(umount(dir.path().c_str()), SyscallFailsWithErrno(EBUSY)); } TEST(MountTest, MountTmpfs) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); // NOTE(b/129868551): Inode IDs are only stable across S/R if we have an open // FD for that inode. Since we are going to compare inode IDs below, get a // FileDescriptor for this directory here, which will be closed automatically // at the end of the test. auto const fd = ASSERT_NO_ERRNO_AND_VALUE(Open(dir.path(), O_DIRECTORY, O_RDONLY)); const struct stat before = ASSERT_NO_ERRNO_AND_VALUE(Stat(dir.path())); { auto const mount = ASSERT_NO_ERRNO_AND_VALUE( Mount("", dir.path(), "tmpfs", 0, "mode=0700", 0)); const struct stat s = ASSERT_NO_ERRNO_AND_VALUE(Stat(dir.path())); EXPECT_EQ(s.st_mode, S_IFDIR | 0700); EXPECT_NE(s.st_ino, before.st_ino); EXPECT_NO_ERRNO(Open(JoinPath(dir.path(), "foo"), O_CREAT | O_RDWR, 0777)); } // Now that dir is unmounted again, we should have the old inode back. const struct stat after = ASSERT_NO_ERRNO_AND_VALUE(Stat(dir.path())); EXPECT_EQ(before.st_ino, after.st_ino); } TEST(MountTest, MountTmpfsMagicValIgnored) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const mount = ASSERT_NO_ERRNO_AND_VALUE( Mount("", dir.path(), "tmpfs", MS_MGC_VAL, "mode=0700", 0)); } // Passing nullptr to data is equivalent to "". TEST(MountTest, NullData) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); EXPECT_THAT(mount("", dir.path().c_str(), "tmpfs", 0, nullptr), SyscallSucceeds()); EXPECT_THAT(umount2(dir.path().c_str(), 0), SyscallSucceeds()); } TEST(MountTest, MountReadonly) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const mount = ASSERT_NO_ERRNO_AND_VALUE( Mount("", dir.path(), "tmpfs", MS_RDONLY, "mode=0777", 0)); const struct stat s = ASSERT_NO_ERRNO_AND_VALUE(Stat(dir.path())); EXPECT_EQ(s.st_mode, S_IFDIR | 0777); std::string const filename = JoinPath(dir.path(), "foo"); EXPECT_THAT(open(filename.c_str(), O_RDWR | O_CREAT, 0777), SyscallFailsWithErrno(EROFS)); } PosixErrorOr<absl::Time> ATime(absl::string_view file) { struct stat s = {}; if (stat(std::string(file).c_str(), &s) == -1) { return PosixError(errno, "stat failed"); } return absl::TimeFromTimespec(s.st_atim); } TEST(MountTest, MountNoAtime) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const mount = ASSERT_NO_ERRNO_AND_VALUE( Mount("", dir.path(), "tmpfs", MS_NOATIME, "mode=0777", 0)); std::string const contents = "No no no, don't follow the instructions!"; auto const file = ASSERT_NO_ERRNO_AND_VALUE( TempPath::CreateFileWith(dir.path(), contents, 0777)); absl::Time const before = ASSERT_NO_ERRNO_AND_VALUE(ATime(file.path())); // Reading from the file should change the atime, but the MS_NOATIME flag // should prevent that. auto const fd = ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_RDWR)); char buf[100]; int read_n; ASSERT_THAT(read_n = read(fd.get(), buf, sizeof(buf)), SyscallSucceeds()); EXPECT_EQ(std::string(buf, read_n), contents); absl::Time const after = ASSERT_NO_ERRNO_AND_VALUE(ATime(file.path())); // Expect that atime hasn't changed. EXPECT_EQ(before, after); } TEST(MountTest, MountNoExec) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const mount = ASSERT_NO_ERRNO_AND_VALUE( Mount("", dir.path(), "tmpfs", MS_NOEXEC, "mode=0777", 0)); std::string const contents = "No no no, don't follow the instructions!"; auto const file = ASSERT_NO_ERRNO_AND_VALUE( TempPath::CreateFileWith(dir.path(), contents, 0777)); int execve_errno; ASSERT_NO_ERRNO_AND_VALUE( ForkAndExec(file.path(), {}, {}, nullptr, &execve_errno)); EXPECT_EQ(execve_errno, EACCES); } TEST(MountTest, RenameRemoveMountPoint) { SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); auto const dir_parent = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDirIn(dir_parent.path())); auto const new_dir = NewTempAbsPath(); auto const mount = ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "tmpfs", 0, "", 0)); ASSERT_THAT(rename(dir.path().c_str(), new_dir.c_str()), SyscallFailsWithErrno(EBUSY)); ASSERT_THAT(rmdir(dir.path().c_str()), SyscallFailsWithErrno(EBUSY)); } } // namespace } // namespace testing } // namespace gvisor