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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 <sys/mount.h>
#include <iomanip>
#include <sstream>
#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"
namespace gvisor {
namespace testing {
namespace {
#ifndef FS_IOC_ENABLE_VERITY
#define FS_IOC_ENABLE_VERITY 1082156677
#endif
#ifndef FS_IOC_MEASURE_VERITY
#define FS_IOC_MEASURE_VERITY 3221513862
#endif
#ifndef FS_VERITY_FL
#define FS_VERITY_FL 1048576
#endif
#ifndef FS_IOC_GETFLAGS
#define FS_IOC_GETFLAGS 2148034049
#endif
struct fsverity_digest {
__u16 digest_algorithm;
__u16 digest_size; /* input/output */
__u8 digest[];
};
constexpr int kMaxDigestSize = 64;
constexpr int kDefaultDigestSize = 32;
constexpr char kContents[] = "foobarbaz";
class IoctlTest : 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());
}
TempPath tmpfs_dir_;
TempPath file_;
std::string filename_;
};
// Provide a function to convert bytes to hex string, since
// absl::BytesToHexString does not seem to be compatible with golang
// hex.DecodeString used in verity due to zero-padding.
std::string BytesToHexString(uint8_t bytes[], int size) {
std::stringstream ss;
ss << std::hex;
for (int i = 0; i < size; ++i) {
ss << std::setw(2) << std::setfill('0') << static_cast<int>(bytes[i]);
}
return ss.str();
}
TEST_F(IoctlTest, Enable) {
// Mount a verity fs on the existing tmpfs mount.
std::string mount_opts = "lower_path=" + tmpfs_dir_.path();
auto const verity_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
ASSERT_THAT(
mount("", verity_dir.path().c_str(), "verity", 0, mount_opts.c_str()),
SyscallSucceeds());
// Confirm that the verity flag is absent.
int flag = 0;
auto const fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir.path(), filename_), O_RDONLY, 0777));
ASSERT_THAT(ioctl(fd.get(), FS_IOC_GETFLAGS, &flag), SyscallSucceeds());
EXPECT_EQ(flag & FS_VERITY_FL, 0);
// Enable the file and confirm that the verity flag is present.
ASSERT_THAT(ioctl(fd.get(), FS_IOC_ENABLE_VERITY), SyscallSucceeds());
ASSERT_THAT(ioctl(fd.get(), FS_IOC_GETFLAGS, &flag), SyscallSucceeds());
EXPECT_EQ(flag & FS_VERITY_FL, FS_VERITY_FL);
}
TEST_F(IoctlTest, Measure) {
// Mount a verity fs on the existing tmpfs mount.
std::string mount_opts = "lower_path=" + tmpfs_dir_.path();
auto const verity_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
ASSERT_THAT(
mount("", verity_dir.path().c_str(), "verity", 0, mount_opts.c_str()),
SyscallSucceeds());
// Confirm that the file cannot be measured.
auto const fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir.path(), filename_), O_RDONLY, 0777));
uint8_t digest_array[sizeof(struct fsverity_digest) + kMaxDigestSize] = {0};
struct fsverity_digest* digest =
reinterpret_cast<struct fsverity_digest*>(digest_array);
digest->digest_size = kMaxDigestSize;
ASSERT_THAT(ioctl(fd.get(), FS_IOC_MEASURE_VERITY, digest),
SyscallFailsWithErrno(ENODATA));
// Enable the file and confirm that the file can be measured.
ASSERT_THAT(ioctl(fd.get(), FS_IOC_ENABLE_VERITY), SyscallSucceeds());
ASSERT_THAT(ioctl(fd.get(), FS_IOC_MEASURE_VERITY, digest),
SyscallSucceeds());
EXPECT_EQ(digest->digest_size, kDefaultDigestSize);
}
TEST_F(IoctlTest, Mount) {
// Mount a verity fs on the existing tmpfs mount.
std::string mount_opts = "lower_path=" + tmpfs_dir_.path();
auto verity_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
ASSERT_THAT(
mount("", verity_dir.path().c_str(), "verity", 0, mount_opts.c_str()),
SyscallSucceeds());
// Enable both the file and the directory.
auto const fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_dir.path(), filename_), O_RDONLY, 0777));
ASSERT_THAT(ioctl(fd.get(), FS_IOC_ENABLE_VERITY), SyscallSucceeds());
auto const dir_fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(verity_dir.path(), O_RDONLY, 0777));
ASSERT_THAT(ioctl(dir_fd.get(), FS_IOC_ENABLE_VERITY), SyscallSucceeds());
// Measure the root hash.
uint8_t digest_array[sizeof(struct fsverity_digest) + kMaxDigestSize] = {0};
struct fsverity_digest* digest =
reinterpret_cast<struct fsverity_digest*>(digest_array);
digest->digest_size = kMaxDigestSize;
ASSERT_THAT(ioctl(dir_fd.get(), FS_IOC_MEASURE_VERITY, digest),
SyscallSucceeds());
// Mount a verity fs with specified root hash.
mount_opts +=
",root_hash=" + BytesToHexString(digest->digest, digest->digest_size);
auto verity_with_hash_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
ASSERT_THAT(mount("", verity_with_hash_dir.path().c_str(), "verity", 0,
mount_opts.c_str()),
SyscallSucceeds());
// Make sure the file can be open and read in the mounted verity fs.
auto const verity_fd = ASSERT_NO_ERRNO_AND_VALUE(
Open(JoinPath(verity_with_hash_dir.path(), filename_), O_RDONLY, 0777));
char buf[16];
EXPECT_THAT(ReadFd(fd.get(), buf, sizeof(kContents)), SyscallSucceeds());
// Verity directories should not be deleted. Release the TempPath objects to
// prevent those directories from being deleted by the destructor.
verity_dir.release();
verity_with_hash_dir.release();
}
} // namespace
} // namespace testing
} // namespace gvisor
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