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// Copyright 2021 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 <stdint.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "test/util/capability_util.h"
#include "test/util/fs_util.h"
#include "test/util/mount_util.h"
#include "test/util/temp_path.h"
#include "test/util/test_util.h"
#include "test/util/verity_util.h"
namespace gvisor {
namespace testing {
namespace {
const char kSymlink[] = "verity_symlink";
class SymlinkTest : public ::testing::Test {
protected:
void SetUp() override {
// Verity is implemented in VFS2.
SKIP_IF(IsRunningWithVFS1());
SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
// Mount a tmpfs file system, to be wrapped by a verity fs.
tmpfs_dir_ = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
ASSERT_THAT(mount("", tmpfs_dir_.path().c_str(), "tmpfs", 0, ""),
SyscallSucceeds());
// Create a new file in the tmpfs mount.
file_ = ASSERT_NO_ERRNO_AND_VALUE(
TempPath::CreateFileWith(tmpfs_dir_.path(), kContents, 0777));
filename_ = Basename(file_.path());
// Create a symlink to the file.
ASSERT_THAT(symlink(file_.path().c_str(),
JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
SyscallSucceeds());
}
TempPath tmpfs_dir_;
TempPath file_;
std::string filename_;
};
TEST_F(SymlinkTest, Success) {
std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(MountVerity(
tmpfs_dir_.path(), {EnableTarget(filename_, O_RDONLY),
EnableTarget(kSymlink, O_RDONLY | O_NOFOLLOW)}));
char buf[256];
EXPECT_THAT(
readlink(JoinPath(verity_dir, kSymlink).c_str(), buf, sizeof(buf)),
SyscallSucceeds());
auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir, kSymlink).c_str(), O_RDONLY, 0777));
EXPECT_THAT(ReadFd(verity_fd.get(), buf, sizeof(kContents)),
SyscallSucceeds());
}
TEST_F(SymlinkTest, DeleteLink) {
std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(MountVerity(
tmpfs_dir_.path(), {EnableTarget(filename_, O_RDONLY),
EnableTarget(kSymlink, O_RDONLY | O_NOFOLLOW)}));
ASSERT_THAT(unlink(JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
SyscallSucceeds());
char buf[256];
EXPECT_THAT(
readlink(JoinPath(verity_dir, kSymlink).c_str(), buf, sizeof(buf)),
SyscallFailsWithErrno(EIO));
EXPECT_THAT(open(JoinPath(verity_dir, kSymlink).c_str(), O_RDONLY, 0777),
SyscallFailsWithErrno(EIO));
}
TEST_F(SymlinkTest, ModifyLink) {
std::string verity_dir = ASSERT_NO_ERRNO_AND_VALUE(MountVerity(
tmpfs_dir_.path(), {EnableTarget(filename_, O_RDONLY),
EnableTarget(kSymlink, O_RDONLY | O_NOFOLLOW)}));
ASSERT_THAT(unlink(JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
SyscallSucceeds());
std::string newlink = "newlink";
ASSERT_THAT(symlink(JoinPath(tmpfs_dir_.path(), newlink).c_str(),
JoinPath(tmpfs_dir_.path(), kSymlink).c_str()),
SyscallSucceeds());
char buf[256];
EXPECT_THAT(
readlink(JoinPath(verity_dir, kSymlink).c_str(), buf, sizeof(buf)),
SyscallFailsWithErrno(EIO));
EXPECT_THAT(open(JoinPath(verity_dir, kSymlink).c_str(), O_RDONLY, 0777),
SyscallFailsWithErrno(EIO));
}
} // namespace
} // namespace testing
} // namespace gvisor
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