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Diffstat (limited to 'test/syscalls/linux/mount.cc')
| -rw-r--r-- | test/syscalls/linux/mount.cc | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/test/syscalls/linux/mount.cc b/test/syscalls/linux/mount.cc new file mode 100644 index 000000000..a3e9745cf --- /dev/null +++ b/test/syscalls/linux/mount.cc @@ -0,0 +1,327 @@ +// 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 |