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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 "test/util/verity_util.h"
#include "test/util/fs_util.h"
#include "test/util/mount_util.h"
#include "test/util/temp_path.h"
namespace gvisor {
namespace testing {
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();
}
std::string MerklePath(absl::string_view path) {
return JoinPath(Dirname(path),
std::string(kMerklePrefix) + std::string(Basename(path)));
}
std::string MerkleRootPath(absl::string_view path) {
return JoinPath(Dirname(path),
std::string(kMerkleRootPrefix) + std::string(Basename(path)));
}
PosixError FlipRandomBit(int fd, int size) {
// Generate a random offset in the file.
srand(time(nullptr));
unsigned int seed = 0;
int random_offset = rand_r(&seed) % size;
// Read a random byte and flip a bit in it.
char buf[1];
RETURN_ERROR_IF_SYSCALL_FAIL(PreadFd(fd, buf, 1, random_offset));
buf[0] ^= 1;
RETURN_ERROR_IF_SYSCALL_FAIL(PwriteFd(fd, buf, 1, random_offset));
return NoError();
}
PosixErrorOr<std::string> MountVerity(std::string tmpfs_dir,
std::string filename,
std::vector<EnableTarget> targets) {
// Mount a verity fs on the existing tmpfs mount.
std::string mount_opts = "lower_path=" + tmpfs_dir;
ASSIGN_OR_RETURN_ERRNO(TempPath verity_dir, TempPath::CreateDir());
RETURN_ERROR_IF_SYSCALL_FAIL(
mount("", verity_dir.path().c_str(), "verity", 0, mount_opts.c_str()));
// Enable the file, symlink(if provided) and the directory.
ASSIGN_OR_RETURN_ERRNO(
auto fd, Open(JoinPath(verity_dir.path(), filename), O_RDONLY, 0777));
RETURN_ERROR_IF_SYSCALL_FAIL(ioctl(fd.get(), FS_IOC_ENABLE_VERITY));
for (const EnableTarget& target : targets) {
ASSIGN_OR_RETURN_ERRNO(
auto target_fd,
Open(JoinPath(verity_dir.path(), target.path), target.flags, 0777));
RETURN_ERROR_IF_SYSCALL_FAIL(ioctl(target_fd.get(), FS_IOC_ENABLE_VERITY));
}
ASSIGN_OR_RETURN_ERRNO(auto dir_fd, Open(verity_dir.path(), O_RDONLY, 0777));
RETURN_ERROR_IF_SYSCALL_FAIL(ioctl(dir_fd.get(), FS_IOC_ENABLE_VERITY));
// 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;
RETURN_ERROR_IF_SYSCALL_FAIL(
ioctl(dir_fd.get(), FS_IOC_MEASURE_VERITY, digest));
// Mount a verity fs with specified root hash.
mount_opts +=
",root_hash=" + BytesToHexString(digest->digest, digest->digest_size);
ASSIGN_OR_RETURN_ERRNO(TempPath verity_with_hash_dir, TempPath::CreateDir());
RETURN_ERROR_IF_SYSCALL_FAIL(mount("", verity_with_hash_dir.path().c_str(),
"verity", 0, mount_opts.c_str()));
// Verity directories should not be deleted. Release the TempPath objects to
// prevent those directories from being deleted by the destructor.
verity_dir.release();
return verity_with_hash_dir.release();
}
} // namespace testing
} // namespace gvisor
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