path: root/test/syscalls/linux/xattr.cc

// Copyright 2019 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 <limits.h>
#include <sys/types.h>
#include <sys/xattr.h>
#include <unistd.h>

#include <string>
#include <vector>

#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "test/syscalls/linux/file_base.h"
#include "test/util/capability_util.h"
#include "test/util/posix_error.h"
#include "test/util/temp_path.h"
#include "test/util/test_util.h"

namespace gvisor {
namespace testing {

namespace {

class XattrTest : public FileTest {};

TEST_F(XattrTest, XattrNullName) {
  const char* path = test_file_name_.c_str();

  EXPECT_THAT(setxattr(path, nullptr, nullptr, 0, /*flags=*/0),
              SyscallFailsWithErrno(EFAULT));
  EXPECT_THAT(getxattr(path, nullptr, nullptr, 0),
              SyscallFailsWithErrno(EFAULT));
}

TEST_F(XattrTest, XattrEmptyName) {
  const char* path = test_file_name_.c_str();

  EXPECT_THAT(setxattr(path, "", nullptr, 0, /*flags=*/0),
              SyscallFailsWithErrno(ERANGE));
  EXPECT_THAT(getxattr(path, "", nullptr, 0), SyscallFailsWithErrno(ERANGE));
}

TEST_F(XattrTest, XattrLargeName) {
  const char* path = test_file_name_.c_str();
  std::string name = "user.";
  name += std::string(XATTR_NAME_MAX - name.length(), 'a');

  // An xattr should be whitelisted before it can be accessed--do not allow
  // arbitrary xattrs to be read/written in gVisor.
  if (!IsRunningOnGvisor()) {
    EXPECT_THAT(setxattr(path, name.c_str(), nullptr, 0, /*flags=*/0),
                SyscallSucceeds());
    EXPECT_THAT(getxattr(path, name.c_str(), nullptr, 0),
                SyscallSucceedsWithValue(0));
  }

  name += "a";
  EXPECT_THAT(setxattr(path, name.c_str(), nullptr, 0, /*flags=*/0),
              SyscallFailsWithErrno(ERANGE));
  EXPECT_THAT(getxattr(path, name.c_str(), nullptr, 0),
              SyscallFailsWithErrno(ERANGE));
}

TEST_F(XattrTest, XattrInvalidPrefix) {
  const char* path = test_file_name_.c_str();
  std::string name(XATTR_NAME_MAX, 'a');
  EXPECT_THAT(setxattr(path, name.c_str(), nullptr, 0, /*flags=*/0),
              SyscallFailsWithErrno(EOPNOTSUPP));
  EXPECT_THAT(getxattr(path, name.c_str(), nullptr, 0),
              SyscallFailsWithErrno(EOPNOTSUPP));
}

// Do not allow save/restore cycles after making the test file read-only, as
// the restore will fail to open it with r/w permissions.
TEST_F(XattrTest, XattrReadOnly_NoRandomSave) {
  // Drop capabilities that allow us to override file and directory permissions.
  ASSERT_NO_ERRNO(SetCapability(CAP_DAC_OVERRIDE, false));
  ASSERT_NO_ERRNO(SetCapability(CAP_DAC_READ_SEARCH, false));

  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  size_t size = sizeof(val);

  EXPECT_THAT(setxattr(path, name, &val, size, /*flags=*/0), SyscallSucceeds());

  DisableSave ds;
  ASSERT_NO_ERRNO(testing::Chmod(test_file_name_, S_IRUSR));

  EXPECT_THAT(setxattr(path, name, &val, size, /*flags=*/0),
              SyscallFailsWithErrno(EACCES));

  char buf = '-';
  EXPECT_THAT(getxattr(path, name, &buf, size), SyscallSucceedsWithValue(size));
  EXPECT_EQ(buf, val);
}

// Do not allow save/restore cycles after making the test file write-only, as
// the restore will fail to open it with r/w permissions.
TEST_F(XattrTest, XattrWriteOnly_NoRandomSave) {
  // Drop capabilities that allow us to override file and directory permissions.
  ASSERT_NO_ERRNO(SetCapability(CAP_DAC_OVERRIDE, false));
  ASSERT_NO_ERRNO(SetCapability(CAP_DAC_READ_SEARCH, false));

  DisableSave ds;
  ASSERT_NO_ERRNO(testing::Chmod(test_file_name_, S_IWUSR));

  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  size_t size = sizeof(val);

  EXPECT_THAT(setxattr(path, name, &val, size, /*flags=*/0), SyscallSucceeds());

  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallFailsWithErrno(EACCES));
}

TEST_F(XattrTest, XattrTrustedWithNonadmin) {
  // TODO(b/127675828): Support setxattr and getxattr with "trusted" prefix.
  SKIP_IF(IsRunningOnGvisor());
  SKIP_IF(ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));

  const char* path = test_file_name_.c_str();
  const char name[] = "trusted.abc";
  EXPECT_THAT(setxattr(path, name, nullptr, 0, /*flags=*/0),
              SyscallFailsWithErrno(EPERM));
  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallFailsWithErrno(ENODATA));
}

TEST_F(XattrTest, XattrOnDirectory) {
  TempPath dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
  const char name[] = "user.test";
  EXPECT_THAT(setxattr(dir.path().c_str(), name, NULL, 0, /*flags=*/0),
              SyscallSucceeds());
  EXPECT_THAT(getxattr(dir.path().c_str(), name, NULL, 0),
              SyscallSucceedsWithValue(0));
}

TEST_F(XattrTest, XattrOnSymlink) {
  TempPath dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
  TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
      TempPath::CreateSymlinkTo(dir.path(), test_file_name_));
  const char name[] = "user.test";
  EXPECT_THAT(setxattr(link.path().c_str(), name, NULL, 0, /*flags=*/0),
              SyscallSucceeds());
  EXPECT_THAT(getxattr(link.path().c_str(), name, NULL, 0),
              SyscallSucceedsWithValue(0));
}

TEST_F(XattrTest, XattrOnInvalidFileTypes) {
  const char name[] = "user.test";

  char char_device[] = "/dev/zero";
  EXPECT_THAT(setxattr(char_device, name, NULL, 0, /*flags=*/0),
              SyscallFailsWithErrno(EPERM));
  EXPECT_THAT(getxattr(char_device, name, NULL, 0),
              SyscallFailsWithErrno(ENODATA));

  // Use tmpfs, where creation of named pipes is supported.
  const std::string fifo = NewTempAbsPathInDir("/dev/shm");
  const char* path = fifo.c_str();
  EXPECT_THAT(mknod(path, S_IFIFO | S_IRUSR | S_IWUSR, 0), SyscallSucceeds());
  EXPECT_THAT(setxattr(path, name, NULL, 0, /*flags=*/0),
              SyscallFailsWithErrno(EPERM));
  EXPECT_THAT(getxattr(path, name, NULL, 0), SyscallFailsWithErrno(ENODATA));
}

TEST_F(XattrTest, SetxattrSizeSmallerThanValue) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  std::vector<char> val = {'a', 'a'};
  size_t size = 1;
  EXPECT_THAT(setxattr(path, name, val.data(), size, /*flags=*/0),
              SyscallSucceeds());

  std::vector<char> buf = {'-', '-'};
  std::vector<char> expected_buf = {'a', '-'};
  EXPECT_THAT(getxattr(path, name, buf.data(), buf.size()),
              SyscallSucceedsWithValue(size));
  EXPECT_EQ(buf, expected_buf);
}

TEST_F(XattrTest, SetxattrZeroSize) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  EXPECT_THAT(setxattr(path, name, &val, 0, /*flags=*/0), SyscallSucceeds());

  char buf = '-';
  EXPECT_THAT(getxattr(path, name, &buf, XATTR_SIZE_MAX),
              SyscallSucceedsWithValue(0));
  EXPECT_EQ(buf, '-');
}

TEST_F(XattrTest, SetxattrSizeTooLarge) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";

  // Note that each particular fs implementation may stipulate a lower size
  // limit, in which case we actually may fail (e.g. error with ENOSPC) for
  // some sizes under XATTR_SIZE_MAX.
  size_t size = XATTR_SIZE_MAX + 1;
  std::vector<char> val(size);
  EXPECT_THAT(setxattr(path, name, val.data(), size, /*flags=*/0),
              SyscallFailsWithErrno(E2BIG));

  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallFailsWithErrno(ENODATA));
}

TEST_F(XattrTest, SetxattrNullValueAndNonzeroSize) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  EXPECT_THAT(setxattr(path, name, nullptr, 1, /*flags=*/0),
              SyscallFailsWithErrno(EFAULT));

  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallFailsWithErrno(ENODATA));
}

TEST_F(XattrTest, SetxattrNullValueAndZeroSize) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  EXPECT_THAT(setxattr(path, name, nullptr, 0, /*flags=*/0), SyscallSucceeds());

  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallSucceedsWithValue(0));
}

TEST_F(XattrTest, SetxattrValueTooLargeButOKSize) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  std::vector<char> val(XATTR_SIZE_MAX + 1);
  std::fill(val.begin(), val.end(), 'a');
  size_t size = 1;
  EXPECT_THAT(setxattr(path, name, val.data(), size, /*flags=*/0),
              SyscallSucceeds());

  std::vector<char> buf = {'-', '-'};
  std::vector<char> expected_buf = {'a', '-'};
  EXPECT_THAT(getxattr(path, name, buf.data(), size),
              SyscallSucceedsWithValue(size));
  EXPECT_EQ(buf, expected_buf);
}

TEST_F(XattrTest, SetxattrReplaceWithSmaller) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  std::vector<char> val = {'a', 'a'};
  EXPECT_THAT(setxattr(path, name, val.data(), 2, /*flags=*/0),
              SyscallSucceeds());
  EXPECT_THAT(setxattr(path, name, val.data(), 1, /*flags=*/0),
              SyscallSucceeds());

  std::vector<char> buf = {'-', '-'};
  std::vector<char> expected_buf = {'a', '-'};
  EXPECT_THAT(getxattr(path, name, buf.data(), 2), SyscallSucceedsWithValue(1));
  EXPECT_EQ(buf, expected_buf);
}

TEST_F(XattrTest, SetxattrReplaceWithLarger) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  std::vector<char> val = {'a', 'a'};
  EXPECT_THAT(setxattr(path, name, val.data(), 1, /*flags=*/0),
              SyscallSucceeds());
  EXPECT_THAT(setxattr(path, name, val.data(), 2, /*flags=*/0),
              SyscallSucceeds());

  std::vector<char> buf = {'-', '-'};
  EXPECT_THAT(getxattr(path, name, buf.data(), 2), SyscallSucceedsWithValue(2));
  EXPECT_EQ(buf, val);
}

TEST_F(XattrTest, SetxattrCreateFlag) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  EXPECT_THAT(setxattr(path, name, nullptr, 0, XATTR_CREATE),
              SyscallSucceeds());
  EXPECT_THAT(setxattr(path, name, nullptr, 0, XATTR_CREATE),
              SyscallFailsWithErrno(EEXIST));

  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallSucceedsWithValue(0));
}

TEST_F(XattrTest, SetxattrReplaceFlag) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  EXPECT_THAT(setxattr(path, name, nullptr, 0, XATTR_REPLACE),
              SyscallFailsWithErrno(ENODATA));
  EXPECT_THAT(setxattr(path, name, nullptr, 0, /*flags=*/0), SyscallSucceeds());
  EXPECT_THAT(setxattr(path, name, nullptr, 0, XATTR_REPLACE),
              SyscallSucceeds());

  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallSucceedsWithValue(0));
}

TEST_F(XattrTest, SetxattrInvalidFlags) {
  const char* path = test_file_name_.c_str();
  int invalid_flags = 0xff;
  EXPECT_THAT(setxattr(path, nullptr, nullptr, 0, invalid_flags),
              SyscallFailsWithErrno(EINVAL));
}

TEST_F(XattrTest, Getxattr) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  int val = 1234;
  size_t size = sizeof(val);
  EXPECT_THAT(setxattr(path, name, &val, size, /*flags=*/0), SyscallSucceeds());

  int buf = 0;
  EXPECT_THAT(getxattr(path, name, &buf, size), SyscallSucceedsWithValue(size));
  EXPECT_EQ(buf, val);
}

TEST_F(XattrTest, GetxattrSizeSmallerThanValue) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  std::vector<char> val = {'a', 'a'};
  size_t size = val.size();
  EXPECT_THAT(setxattr(path, name, &val, size, /*flags=*/0), SyscallSucceeds());

  char buf = '-';
  EXPECT_THAT(getxattr(path, name, &buf, 1), SyscallFailsWithErrno(ERANGE));
  EXPECT_EQ(buf, '-');
}

TEST_F(XattrTest, GetxattrSizeLargerThanValue) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  EXPECT_THAT(setxattr(path, name, &val, 1, /*flags=*/0), SyscallSucceeds());

  std::vector<char> buf(XATTR_SIZE_MAX);
  std::fill(buf.begin(), buf.end(), '-');
  std::vector<char> expected_buf = buf;
  expected_buf[0] = 'a';
  EXPECT_THAT(getxattr(path, name, buf.data(), buf.size()),
              SyscallSucceedsWithValue(1));
  EXPECT_EQ(buf, expected_buf);
}

TEST_F(XattrTest, GetxattrZeroSize) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  EXPECT_THAT(setxattr(path, name, &val, sizeof(val), /*flags=*/0),
              SyscallSucceeds());

  char buf = '-';
  EXPECT_THAT(getxattr(path, name, &buf, 0),
              SyscallSucceedsWithValue(sizeof(val)));
  EXPECT_EQ(buf, '-');
}

TEST_F(XattrTest, GetxattrSizeTooLarge) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  EXPECT_THAT(setxattr(path, name, &val, sizeof(val), /*flags=*/0),
              SyscallSucceeds());

  std::vector<char> buf(XATTR_SIZE_MAX + 1);
  std::fill(buf.begin(), buf.end(), '-');
  std::vector<char> expected_buf = buf;
  expected_buf[0] = 'a';
  EXPECT_THAT(getxattr(path, name, buf.data(), buf.size()),
              SyscallSucceedsWithValue(sizeof(val)));
  EXPECT_EQ(buf, expected_buf);
}

TEST_F(XattrTest, GetxattrNullValue) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  size_t size = sizeof(val);
  EXPECT_THAT(setxattr(path, name, &val, size, /*flags=*/0), SyscallSucceeds());

  EXPECT_THAT(getxattr(path, name, nullptr, size),
              SyscallFailsWithErrno(EFAULT));
}

TEST_F(XattrTest, GetxattrNullValueAndZeroSize) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  char val = 'a';
  size_t size = sizeof(val);
  // Set value with zero size.
  EXPECT_THAT(setxattr(path, name, &val, 0, /*flags=*/0), SyscallSucceeds());
  // Get value with nonzero size.
  EXPECT_THAT(getxattr(path, name, nullptr, size), SyscallSucceedsWithValue(0));

  // Set value with nonzero size.
  EXPECT_THAT(setxattr(path, name, &val, size, /*flags=*/0), SyscallSucceeds());
  // Get value with zero size.
  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallSucceedsWithValue(size));
}

TEST_F(XattrTest, GetxattrNonexistentName) {
  const char* path = test_file_name_.c_str();
  const char name[] = "user.test";
  EXPECT_THAT(getxattr(path, name, nullptr, 0), SyscallFailsWithErrno(ENODATA));
}

}  // namespace

}  // namespace testing
}  // namespace gvisor