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// 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 <grp.h>
#include <sys/types.h>
#include <unistd.h>
#include <vector>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/flags/flag.h"
#include "absl/synchronization/notification.h"
#include "test/util/capability_util.h"
#include "test/util/file_descriptor.h"
#include "test/util/fs_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"
ABSL_FLAG(int32, scratch_uid1, 65534, "first scratch UID");
ABSL_FLAG(int32, scratch_uid2, 65533, "second scratch UID");
ABSL_FLAG(int32, scratch_gid, 65534, "first scratch GID");
namespace gvisor {
namespace testing {
namespace {
TEST(ChownTest, FchownBadF) {
ASSERT_THAT(fchown(-1, 0, 0), SyscallFailsWithErrno(EBADF));
}
TEST(ChownTest, FchownatBadF) {
ASSERT_THAT(fchownat(-1, "fff", 0, 0, 0), SyscallFailsWithErrno(EBADF));
}
TEST(ChownTest, FchownatEmptyPath) {
const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
const auto fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(dir.path(), O_DIRECTORY | O_RDONLY));
ASSERT_THAT(fchownat(fd.get(), "", 0, 0, 0), SyscallFailsWithErrno(ENOENT));
}
using Chown =
std::function<PosixError(const std::string&, uid_t owner, gid_t group)>;
class ChownParamTest : public ::testing::TestWithParam<Chown> {};
TEST_P(ChownParamTest, ChownFileSucceeds) {
if (ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_CHOWN))) {
ASSERT_NO_ERRNO(SetCapability(CAP_CHOWN, false));
}
const auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
// At least *try* setting to a group other than the EGID.
gid_t gid;
EXPECT_THAT(gid = getegid(), SyscallSucceeds());
int num_groups;
EXPECT_THAT(num_groups = getgroups(0, nullptr), SyscallSucceeds());
if (num_groups > 0) {
std::vector<gid_t> list(num_groups);
EXPECT_THAT(getgroups(list.size(), list.data()), SyscallSucceeds());
gid = list[0];
}
EXPECT_NO_ERRNO(GetParam()(file.path(), geteuid(), gid));
struct stat s = {};
ASSERT_THAT(stat(file.path().c_str(), &s), SyscallSucceeds());
EXPECT_EQ(s.st_uid, geteuid());
EXPECT_EQ(s.st_gid, gid);
}
TEST_P(ChownParamTest, ChownFilePermissionDenied) {
SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SETUID)));
const auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileMode(0777));
// Drop privileges and change IDs only in child thread, or else this parent
// thread won't be able to open some log files after the test ends.
ScopedThread([&] {
// Drop privileges.
if (HaveCapability(CAP_CHOWN).ValueOrDie()) {
EXPECT_NO_ERRNO(SetCapability(CAP_CHOWN, false));
}
// Change EUID and EGID.
//
// See note about POSIX below.
EXPECT_THAT(
syscall(SYS_setresgid, -1, absl::GetFlag(FLAGS_scratch_gid), -1),
SyscallSucceeds());
EXPECT_THAT(
syscall(SYS_setresuid, -1, absl::GetFlag(FLAGS_scratch_uid1), -1),
SyscallSucceeds());
EXPECT_THAT(GetParam()(file.path(), geteuid(), getegid()),
PosixErrorIs(EPERM, ::testing::ContainsRegex("chown")));
});
}
TEST_P(ChownParamTest, ChownFileSucceedsAsRoot) {
SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability((CAP_CHOWN))));
SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability((CAP_SETUID))));
const std::string filename = NewTempAbsPath();
absl::Notification fileCreated, fileChowned;
// Change UID only in child thread, or else this parent thread won't be able
// to open some log files after the test ends.
ScopedThread t([&] {
// POSIX requires that all threads in a process share the same UIDs, so
// the NPTL setresuid wrappers use signals to make all threads execute the
// setresuid syscall. However, we want this thread to have its own set of
// credentials different from the parent process, so we use the raw
// syscall.
EXPECT_THAT(
syscall(SYS_setresuid, -1, absl::GetFlag(FLAGS_scratch_uid2), -1),
SyscallSucceeds());
// Create file and immediately close it.
FileDescriptor fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(filename, O_CREAT | O_RDWR, 0644));
fd.reset(); // Close the fd.
fileCreated.Notify();
fileChowned.WaitForNotification();
EXPECT_THAT(open(filename.c_str(), O_RDWR), SyscallFailsWithErrno(EACCES));
FileDescriptor fd2 = ASSERT_NO_ERRNO_AND_VALUE(Open(filename, O_RDONLY));
});
fileCreated.WaitForNotification();
// Set file's owners to someone different.
EXPECT_NO_ERRNO(GetParam()(filename, absl::GetFlag(FLAGS_scratch_uid1),
absl::GetFlag(FLAGS_scratch_gid)));
struct stat s;
EXPECT_THAT(stat(filename.c_str(), &s), SyscallSucceeds());
EXPECT_EQ(s.st_uid, absl::GetFlag(FLAGS_scratch_uid1));
EXPECT_EQ(s.st_gid, absl::GetFlag(FLAGS_scratch_gid));
fileChowned.Notify();
}
PosixError errorFromReturn(const std::string& name, int ret) {
if (ret == -1) {
return PosixError(errno, absl::StrCat(name, " failed"));
}
return NoError();
}
INSTANTIATE_TEST_SUITE_P(
ChownKinds, ChownParamTest,
::testing::Values(
[](const std::string& path, uid_t owner, gid_t group) -> PosixError {
int rc = chown(path.c_str(), owner, group);
MaybeSave();
return errorFromReturn("chown", rc);
},
[](const std::string& path, uid_t owner, gid_t group) -> PosixError {
int rc = lchown(path.c_str(), owner, group);
MaybeSave();
return errorFromReturn("lchown", rc);
},
[](const std::string& path, uid_t owner, gid_t group) -> PosixError {
ASSIGN_OR_RETURN_ERRNO(auto fd, Open(path, O_RDWR));
int rc = fchown(fd.get(), owner, group);
MaybeSave();
return errorFromReturn("fchown", rc);
},
[](const std::string& path, uid_t owner, gid_t group) -> PosixError {
ASSIGN_OR_RETURN_ERRNO(auto fd, Open(path, O_RDWR));
int rc = fchownat(fd.get(), "", owner, group, AT_EMPTY_PATH);
MaybeSave();
return errorFromReturn("fchownat-fd", rc);
},
[](const std::string& path, uid_t owner, gid_t group) -> PosixError {
ASSIGN_OR_RETURN_ERRNO(auto dirfd, Open(std::string(Dirname(path)),
O_DIRECTORY | O_RDONLY));
int rc = fchownat(dirfd.get(), std::string(Basename(path)).c_str(),
owner, group, 0);
MaybeSave();
return errorFromReturn("fchownat-dirfd", rc);
}));
} // namespace
} // namespace testing
} // namespace gvisor
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