// 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 <fcntl.h> #include <sys/stat.h> #include <sys/types.h> #include <unistd.h> #include <string> #include "gtest/gtest.h" #include "test/util/capability_util.h" #include "test/util/file_descriptor.h" #include "test/util/fs_util.h" #include "test/util/temp_path.h" #include "test/util/test_util.h" namespace gvisor { namespace testing { namespace { TEST(ChmodTest, ChmodFileSucceeds) { // Drop capabilities that allow us to override file permissions. AutoCapability cap(CAP_DAC_OVERRIDE, false); auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); ASSERT_THAT(chmod(file.path().c_str(), 0466), SyscallSucceeds()); EXPECT_THAT(open(file.path().c_str(), O_RDWR), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, ChmodDirSucceeds) { // Drop capabilities that allow us to override file and directory permissions. AutoCapability cap1(CAP_DAC_OVERRIDE, false); AutoCapability cap2(CAP_DAC_READ_SEARCH, false); auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); const std::string fileInDir = NewTempAbsPathInDir(dir.path()); ASSERT_THAT(chmod(dir.path().c_str(), 0466), SyscallSucceeds()); EXPECT_THAT(open(fileInDir.c_str(), O_RDONLY), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodFileSucceeds) { // Drop capabilities that allow us to file directory permissions. AutoCapability cap(CAP_DAC_OVERRIDE, false); auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileMode(0666)); int fd; ASSERT_THAT(fd = open(file.path().c_str(), O_RDWR), SyscallSucceeds()); { const DisableSave ds; // File permissions are reduced. ASSERT_THAT(fchmod(fd, 0444), SyscallSucceeds()); EXPECT_THAT(close(fd), SyscallSucceeds()); } EXPECT_THAT(open(file.path().c_str(), O_RDWR), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodDirSucceeds) { // Drop capabilities that allow us to override file and directory permissions. AutoCapability cap1(CAP_DAC_OVERRIDE, false); AutoCapability cap2(CAP_DAC_READ_SEARCH, false); auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); int fd; ASSERT_THAT(fd = open(dir.path().c_str(), O_RDONLY | O_DIRECTORY), SyscallSucceeds()); { const DisableSave ds; // File permissions are reduced. ASSERT_THAT(fchmod(fd, 0), SyscallSucceeds()); EXPECT_THAT(close(fd), SyscallSucceeds()); } EXPECT_THAT(open(dir.path().c_str(), O_RDONLY), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodBadF) { ASSERT_THAT(fchmod(-1, 0444), SyscallFailsWithErrno(EBADF)); } TEST(ChmodTest, FchmodatBadF) { ASSERT_THAT(fchmodat(-1, "foo", 0444, 0), SyscallFailsWithErrno(EBADF)); } TEST(ChmodTest, FchmodFileWithOpath) { SKIP_IF(IsRunningWithVFS1()); auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_PATH)); ASSERT_THAT(fchmod(fd.get(), 0444), SyscallFailsWithErrno(EBADF)); } TEST(ChmodTest, FchmodDirWithOpath) { SKIP_IF(IsRunningWithVFS1()); const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); const auto fd = ASSERT_NO_ERRNO_AND_VALUE(Open(dir.path(), O_DIRECTORY | O_PATH)); ASSERT_THAT(fchmod(fd.get(), 0444), SyscallFailsWithErrno(EBADF)); } TEST(ChmodTest, FchmodatWithOpath) { SKIP_IF(IsRunningWithVFS1()); // Drop capabilities that allow us to override file permissions. AutoCapability cap(CAP_DAC_OVERRIDE, false); auto temp_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); const auto parent_fd = ASSERT_NO_ERRNO_AND_VALUE( Open(GetAbsoluteTestTmpdir().c_str(), O_PATH | O_DIRECTORY)); ASSERT_THAT( fchmodat(parent_fd.get(), std::string(Basename(temp_file.path())).c_str(), 0444, 0), SyscallSucceeds()); EXPECT_THAT(open(temp_file.path().c_str(), O_RDWR), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodatNotDir) { ASSERT_THAT(fchmodat(-1, "", 0444, 0), SyscallFailsWithErrno(ENOENT)); } TEST(ChmodTest, FchmodatFileAbsolutePath) { // Drop capabilities that allow us to override file permissions. AutoCapability cap(CAP_DAC_OVERRIDE, false); auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); ASSERT_THAT(fchmodat(-1, file.path().c_str(), 0444, 0), SyscallSucceeds()); EXPECT_THAT(open(file.path().c_str(), O_RDWR), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodatDirAbsolutePath) { // Drop capabilities that allow us to override file and directory permissions. AutoCapability cap1(CAP_DAC_OVERRIDE, false); AutoCapability cap2(CAP_DAC_READ_SEARCH, false); auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); int fd; ASSERT_THAT(fd = open(dir.path().c_str(), O_RDONLY | O_DIRECTORY), SyscallSucceeds()); EXPECT_THAT(close(fd), SyscallSucceeds()); ASSERT_THAT(fchmodat(-1, dir.path().c_str(), 0, 0), SyscallSucceeds()); EXPECT_THAT(open(dir.path().c_str(), O_RDONLY), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodatFile) { // Drop capabilities that allow us to override file permissions. AutoCapability cap(CAP_DAC_OVERRIDE, false); auto temp_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); int parent_fd; ASSERT_THAT( parent_fd = open(GetAbsoluteTestTmpdir().c_str(), O_RDONLY | O_DIRECTORY), SyscallSucceeds()); ASSERT_THAT( fchmodat(parent_fd, std::string(Basename(temp_file.path())).c_str(), 0444, 0), SyscallSucceeds()); EXPECT_THAT(close(parent_fd), SyscallSucceeds()); EXPECT_THAT(open(temp_file.path().c_str(), O_RDWR), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodatDir) { // Drop capabilities that allow us to override file and directory permissions. AutoCapability cap1(CAP_DAC_OVERRIDE, false); AutoCapability cap2(CAP_DAC_READ_SEARCH, false); auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); int parent_fd; ASSERT_THAT( parent_fd = open(GetAbsoluteTestTmpdir().c_str(), O_RDONLY | O_DIRECTORY), SyscallSucceeds()); int fd; ASSERT_THAT(fd = open(dir.path().c_str(), O_RDONLY | O_DIRECTORY), SyscallSucceeds()); EXPECT_THAT(close(fd), SyscallSucceeds()); ASSERT_THAT( fchmodat(parent_fd, std::string(Basename(dir.path())).c_str(), 0, 0), SyscallSucceeds()); EXPECT_THAT(close(parent_fd), SyscallSucceeds()); EXPECT_THAT(open(dir.path().c_str(), O_RDONLY | O_DIRECTORY), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, ChmodDowngradeWritability) { auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileMode(0666)); int fd; ASSERT_THAT(fd = open(file.path().c_str(), O_RDWR), SyscallSucceeds()); const DisableSave ds; // Permissions are dropped. ASSERT_THAT(chmod(file.path().c_str(), 0444), SyscallSucceeds()); EXPECT_THAT(write(fd, "hello", 5), SyscallSucceedsWithValue(5)); EXPECT_THAT(close(fd), SyscallSucceeds()); } TEST(ChmodTest, ChmodFileToNoPermissionsSucceeds) { // Drop capabilities that allow us to override file permissions. AutoCapability cap1(CAP_DAC_OVERRIDE, false); AutoCapability cap2(CAP_DAC_READ_SEARCH, false); auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileMode(0666)); ASSERT_THAT(chmod(file.path().c_str(), 0), SyscallSucceeds()); EXPECT_THAT(open(file.path().c_str(), O_RDONLY), SyscallFailsWithErrno(EACCES)); } TEST(ChmodTest, FchmodDowngradeWritability) { auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); int fd; ASSERT_THAT(fd = open(file.path().c_str(), O_RDWR | O_CREAT, 0666), SyscallSucceeds()); const DisableSave ds; // Permissions are dropped. ASSERT_THAT(fchmod(fd, 0444), SyscallSucceeds()); EXPECT_THAT(write(fd, "hello", 5), SyscallSucceedsWithValue(5)); EXPECT_THAT(close(fd), SyscallSucceeds()); } TEST(ChmodTest, FchmodFileToNoPermissionsSucceeds) { // Drop capabilities that allow us to override file permissions. AutoCapability cap1(CAP_DAC_OVERRIDE, false); AutoCapability cap2(CAP_DAC_READ_SEARCH, false); auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileMode(0666)); int fd; ASSERT_THAT(fd = open(file.path().c_str(), O_RDWR), SyscallSucceeds()); { const DisableSave ds; // Permissions are dropped. ASSERT_THAT(fchmod(fd, 0), SyscallSucceeds()); EXPECT_THAT(close(fd), SyscallSucceeds()); } EXPECT_THAT(open(file.path().c_str(), O_RDONLY), SyscallFailsWithErrno(EACCES)); } // Verify that we can get a RW FD after chmod, even if a RO fd is left open. TEST(ChmodTest, ChmodWritableWithOpenFD) { // FIXME(b/72455313): broken on hostfs. if (IsRunningOnGvisor()) { return; } TempPath file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileMode(0444)); FileDescriptor fd1 = ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_RDONLY)); ASSERT_THAT(fchmod(fd1.get(), 0644), SyscallSucceeds()); // This FD is writable, even though fd1 has a read-only reference to the file. FileDescriptor fd2 = ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_RDWR)); // fd1 is not writable, but fd2 is. char c = 'a'; EXPECT_THAT(WriteFd(fd1.get(), &c, 1), SyscallFailsWithErrno(EBADF)); EXPECT_THAT(WriteFd(fd2.get(), &c, 1), SyscallSucceedsWithValue(1)); } } // namespace } // namespace testing } // namespace gvisor