| /* |
| * Copyright (C) 2020 The Android Open Source Project |
| * |
| * 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. |
| */ |
| |
| // Utility functions for VtsKernelEncryptionTest. |
| |
| #include <LzmaLib.h> |
| #include <android-base/properties.h> |
| #include <android-base/unique_fd.h> |
| #include <errno.h> |
| #include <ext4_utils/ext4.h> |
| #include <ext4_utils/ext4_sb.h> |
| #include <ext4_utils/ext4_utils.h> |
| #include <gtest/gtest.h> |
| #include <libdm/dm.h> |
| #include <linux/magic.h> |
| #include <mntent.h> |
| #include <openssl/cmac.h> |
| #include <unistd.h> |
| |
| #include "Keymaster.h" |
| #include "vts_kernel_encryption.h" |
| |
| using namespace android::dm; |
| |
| namespace android { |
| namespace kernel { |
| // Context in fixed input string comprises of software provided context, |
| // padding to eight bytes (if required) and the key policy. |
| static const std::vector<std::vector<uint8_t>> HwWrappedEncryptionKeyContexts = |
| { |
| {'i', 'n', 'l', 'i', 'n', 'e', ' ', 'e', 'n', 'c', 'r', 'y', |
| 'p', 't', 'i', 'o', 'n', ' ', 'k', 'e', 'y', 0x0, 0x0, 0x0, |
| 0x00, 0x00, 0x00, 0x02, 0x43, 0x00, 0x82, 0x50, 0x0, 0x0, 0x0, 0x0}, |
| // Below for "legacy && kdf tied to Trusted Execution |
| // Environment(TEE)". |
| // Where as above caters ( "all latest targets" || ("legacy && kdf |
| // not tied to TEE)). |
| {'i', 'n', 'l', 'i', 'n', 'e', ' ', 'e', 'n', 'c', 'r', 'y', |
| 'p', 't', 'i', 'o', 'n', ' ', 'k', 'e', 'y', 0x0, 0x0, 0x0, |
| 0x00, 0x00, 0x00, 0x01, 0x43, 0x00, 0x82, 0x18, 0x0, 0x0, 0x0, 0x0}, |
| }; |
| |
| static bool GetKdfContext(std::vector<uint8_t> *ctx) { |
| std::string kdf = |
| android::base::GetProperty("ro.crypto.hw_wrapped_keys.kdf", "v1"); |
| if (kdf == "v1") { |
| *ctx = HwWrappedEncryptionKeyContexts[0]; |
| return true; |
| } |
| if (kdf == "legacykdf") { |
| *ctx = HwWrappedEncryptionKeyContexts[1]; |
| return true; |
| } |
| ADD_FAILURE() << "Unknown KDF: " << kdf; |
| return false; |
| } |
| |
| // Offset in bytes to the filesystem superblock, relative to the beginning of |
| // the block device |
| constexpr int kExt4SuperBlockOffset = 1024; |
| constexpr int kF2fsSuperBlockOffset = 1024; |
| |
| // For F2FS: the offsets in bytes to the filesystem magic number and filesystem |
| // UUID, relative to the beginning of the block device |
| constexpr int kF2fsMagicOffset = kF2fsSuperBlockOffset; |
| constexpr int kF2fsUuidOffset = kF2fsSuperBlockOffset + 108; |
| |
| // hw-wrapped key size in bytes |
| constexpr int kHwWrappedKeySize = 32; |
| |
| std::string Errno() { return std::string(": ") + strerror(errno); } |
| |
| // Recursively deletes the file or directory at |path|, if it exists. |
| void DeleteRecursively(const std::string &path) { |
| if (unlink(path.c_str()) == 0 || errno == ENOENT) return; |
| ASSERT_EQ(EISDIR, errno) << "Failed to unlink " << path << Errno(); |
| |
| std::unique_ptr<DIR, int (*)(DIR *)> dirp(opendir(path.c_str()), closedir); |
| // If the directory was assigned an encryption policy that the kernel lacks |
| // crypto API support for, then opening it will fail, and it will be empty. |
| // So, we have to allow opening the directory to fail. |
| if (dirp != nullptr) { |
| struct dirent *entry; |
| while ((entry = readdir(dirp.get())) != nullptr) { |
| std::string filename(entry->d_name); |
| if (filename != "." && filename != "..") |
| DeleteRecursively(path + "/" + filename); |
| } |
| } |
| ASSERT_EQ(0, rmdir(path.c_str())) |
| << "Failed to remove directory " << path << Errno(); |
| } |
| |
| // Generates some "random" bytes. Not secure; this is for testing only. |
| void RandomBytesForTesting(std::vector<uint8_t> &bytes) { |
| for (size_t i = 0; i < bytes.size(); i++) { |
| bytes[i] = rand(); |
| } |
| } |
| |
| // Generates a "random" key. Not secure; this is for testing only. |
| std::vector<uint8_t> GenerateTestKey(size_t size) { |
| std::vector<uint8_t> key(size); |
| RandomBytesForTesting(key); |
| return key; |
| } |
| |
| std::string BytesToHex(const std::vector<uint8_t> &bytes) { |
| std::ostringstream o; |
| for (uint8_t b : bytes) { |
| o << std::hex << std::setw(2) << std::setfill('0') << (int)b; |
| } |
| return o.str(); |
| } |
| |
| bool GetFirstApiLevel(int *first_api_level) { |
| *first_api_level = |
| android::base::GetIntProperty("ro.product.first_api_level", 0); |
| if (*first_api_level == 0) { |
| ADD_FAILURE() << "ro.product.first_api_level is unset"; |
| return false; |
| } |
| GTEST_LOG_(INFO) << "ro.product.first_api_level = " << *first_api_level; |
| return true; |
| } |
| |
| // Gets the block device and type of the filesystem mounted on |mountpoint|. |
| // This block device is the one on which the filesystem is directly located. In |
| // the case of device-mapper that means something like /dev/mapper/dm-5, not the |
| // underlying device like /dev/block/by-name/userdata. |
| static bool GetFsBlockDeviceAndType(const std::string &mountpoint, |
| std::string *fs_blk_device, |
| std::string *fs_type) { |
| std::unique_ptr<FILE, int (*)(FILE *)> mnts(setmntent("/proc/mounts", "re"), |
| endmntent); |
| if (!mnts) { |
| ADD_FAILURE() << "Failed to open /proc/mounts" << Errno(); |
| return false; |
| } |
| struct mntent *mnt; |
| while ((mnt = getmntent(mnts.get())) != nullptr) { |
| if (mnt->mnt_dir == mountpoint) { |
| *fs_blk_device = mnt->mnt_fsname; |
| *fs_type = mnt->mnt_type; |
| return true; |
| } |
| } |
| ADD_FAILURE() << "No /proc/mounts entry found for " << mountpoint; |
| return false; |
| } |
| |
| // Gets the UUID of the filesystem of type |fs_type| that's located on |
| // |fs_blk_device|. |
| // |
| // Unfortunately there's no kernel API to get the UUID; instead we have to read |
| // it from the filesystem superblock. |
| static bool GetFilesystemUuid(const std::string &fs_blk_device, |
| const std::string &fs_type, |
| FilesystemUuid *fs_uuid) { |
| android::base::unique_fd fd( |
| open(fs_blk_device.c_str(), O_RDONLY | O_CLOEXEC)); |
| if (fd < 0) { |
| ADD_FAILURE() << "Failed to open fs block device " << fs_blk_device |
| << Errno(); |
| return false; |
| } |
| |
| if (fs_type == "ext4") { |
| struct ext4_super_block sb; |
| |
| if (pread(fd, &sb, sizeof(sb), kExt4SuperBlockOffset) != sizeof(sb)) { |
| ADD_FAILURE() << "Error reading ext4 superblock from " << fs_blk_device |
| << Errno(); |
| return false; |
| } |
| if (sb.s_magic != cpu_to_le16(EXT4_SUPER_MAGIC)) { |
| ADD_FAILURE() << "Failed to find ext4 superblock on " << fs_blk_device; |
| return false; |
| } |
| static_assert(sizeof(sb.s_uuid) == kFilesystemUuidSize); |
| memcpy(fs_uuid->bytes, sb.s_uuid, kFilesystemUuidSize); |
| } else if (fs_type == "f2fs") { |
| // Android doesn't have an f2fs equivalent of libext4_utils, so we have to |
| // hard-code the offset to the magic number and UUID. |
| |
| __le32 magic; |
| if (pread(fd, &magic, sizeof(magic), kF2fsMagicOffset) != sizeof(magic)) { |
| ADD_FAILURE() << "Error reading f2fs superblock from " << fs_blk_device |
| << Errno(); |
| return false; |
| } |
| if (magic != cpu_to_le32(F2FS_SUPER_MAGIC)) { |
| ADD_FAILURE() << "Failed to find f2fs superblock on " << fs_blk_device; |
| return false; |
| } |
| if (pread(fd, fs_uuid->bytes, kFilesystemUuidSize, kF2fsUuidOffset) != |
| kFilesystemUuidSize) { |
| ADD_FAILURE() << "Failed to read f2fs filesystem UUID from " |
| << fs_blk_device << Errno(); |
| return false; |
| } |
| } else { |
| ADD_FAILURE() << "Unknown filesystem type " << fs_type; |
| return false; |
| } |
| return true; |
| } |
| |
| // Gets the raw block device of the filesystem that is mounted from |
| // |fs_blk_device|. By "raw block device" we mean a block device from which we |
| // can read the encrypted file contents and filesystem metadata. When metadata |
| // encryption is disabled, this is simply |fs_blk_device|. When metadata |
| // encryption is enabled, then |fs_blk_device| is a dm-default-key device and |
| // the "raw block device" is the parent of this dm-default-key device. |
| // |
| // We don't just use the block device listed in the fstab, because (a) it can be |
| // a logical partition name which needs extra code to map to a block device, and |
| // (b) due to block-level checkpointing, there can be a dm-bow device between |
| // the fstab partition and dm-default-key. dm-bow can remap sectors, but for |
| // encryption testing we don't want any sector remapping. So the correct block |
| // device to read ciphertext from is the one directly underneath dm-default-key. |
| static bool GetRawBlockDevice(const std::string &fs_blk_device, |
| std::string *raw_blk_device) { |
| DeviceMapper &dm = DeviceMapper::Instance(); |
| |
| if (!dm.IsDmBlockDevice(fs_blk_device)) { |
| GTEST_LOG_(INFO) |
| << fs_blk_device |
| << " is not a device-mapper device; metadata encryption is disabled"; |
| *raw_blk_device = fs_blk_device; |
| return true; |
| } |
| const std::optional<std::string> name = |
| dm.GetDmDeviceNameByPath(fs_blk_device); |
| if (!name) { |
| ADD_FAILURE() << "Failed to get name of device-mapper device " |
| << fs_blk_device; |
| return false; |
| } |
| |
| std::vector<DeviceMapper::TargetInfo> table; |
| if (!dm.GetTableInfo(*name, &table)) { |
| ADD_FAILURE() << "Failed to get table of device-mapper device " << *name; |
| return false; |
| } |
| if (table.size() != 1) { |
| GTEST_LOG_(INFO) << fs_blk_device |
| << " has multiple device-mapper targets; assuming " |
| "metadata encryption is disabled"; |
| *raw_blk_device = fs_blk_device; |
| return true; |
| } |
| const std::string target_type = dm.GetTargetType(table[0].spec); |
| if (target_type != "default-key") { |
| GTEST_LOG_(INFO) << fs_blk_device << " is a dm-" << target_type |
| << " device, not dm-default-key; assuming metadata " |
| "encryption is disabled"; |
| *raw_blk_device = fs_blk_device; |
| return true; |
| } |
| std::optional<std::string> parent = |
| dm.GetParentBlockDeviceByPath(fs_blk_device); |
| if (!parent) { |
| ADD_FAILURE() << "Failed to get parent of dm-default-key device " << *name; |
| return false; |
| } |
| *raw_blk_device = *parent; |
| return true; |
| } |
| |
| // Gets information about the filesystem mounted on |mountpoint|. |
| bool GetFilesystemInfo(const std::string &mountpoint, FilesystemInfo *info) { |
| if (!GetFsBlockDeviceAndType(mountpoint, &info->fs_blk_device, &info->type)) |
| return false; |
| |
| if (!GetFilesystemUuid(info->fs_blk_device, info->type, &info->uuid)) |
| return false; |
| |
| if (!GetRawBlockDevice(info->fs_blk_device, &info->raw_blk_device)) |
| return false; |
| |
| GTEST_LOG_(INFO) << info->fs_blk_device << " is mounted on " << mountpoint |
| << " with type " << info->type << "; UUID is " |
| << BytesToHex(info->uuid.bytes) << ", raw block device is " |
| << info->raw_blk_device; |
| return true; |
| } |
| |
| // Returns true if the given data seems to be random. |
| // |
| // Check compressibility rather than byte frequencies. Compressibility is a |
| // stronger test since it also detects repetitions. |
| // |
| // To check compressibility, use LZMA rather than DEFLATE/zlib/gzip because LZMA |
| // compression is stronger and supports a much larger dictionary. DEFLATE is |
| // limited to a 32 KiB dictionary. So, data repeating after 32 KiB (or more) |
| // would not be detected with DEFLATE. But LZMA can detect it. |
| bool VerifyDataRandomness(const std::vector<uint8_t> &bytes) { |
| // To avoid flakiness, allow the data to be compressed a tiny bit by chance. |
| // There is at most a 2^-32 chance that random data can be compressed to be 4 |
| // bytes shorter. In practice it's even lower due to compression overhead. |
| size_t destLen = bytes.size() - std::min<size_t>(4, bytes.size()); |
| std::vector<uint8_t> dest(destLen); |
| uint8_t outProps[LZMA_PROPS_SIZE]; |
| size_t outPropsSize = LZMA_PROPS_SIZE; |
| int ret; |
| |
| ret = LzmaCompress(dest.data(), &destLen, bytes.data(), bytes.size(), |
| outProps, &outPropsSize, |
| 6, // compression level (0 <= level <= 9) |
| bytes.size(), // dictionary size |
| -1, -1, -1, -1, // lc, lp, bp, fb (-1 selects the default) |
| 1); // number of threads |
| |
| if (ret == SZ_ERROR_OUTPUT_EOF) return true; // incompressible |
| |
| if (ret == SZ_OK) { |
| ADD_FAILURE() << "Data is not random! Compressed " << bytes.size() |
| << " to " << destLen << " bytes"; |
| } else { |
| ADD_FAILURE() << "LZMA compression error: ret=" << ret; |
| } |
| return false; |
| } |
| |
| static bool TryPrepareHwWrappedKey(Keymaster &keymaster, |
| const std::string &master_key_string, |
| std::string *exported_key_string, |
| bool rollback_resistance) { |
| // This key is used to drive a CMAC-based KDF |
| auto paramBuilder = |
| km::AuthorizationSetBuilder().AesEncryptionKey(kHwWrappedKeySize * 8); |
| if (rollback_resistance) { |
| paramBuilder.Authorization(km::TAG_ROLLBACK_RESISTANCE); |
| } |
| paramBuilder.Authorization(km::TAG_STORAGE_KEY); |
| |
| std::string wrapped_key_blob; |
| if (keymaster.importKey(paramBuilder, master_key_string, &wrapped_key_blob) && |
| keymaster.exportKey(wrapped_key_blob, exported_key_string)) { |
| return true; |
| } |
| // It's fine for Keymaster not to support hardware-wrapped keys, but |
| // if generateKey works, importKey must too. |
| if (keymaster.generateKey(paramBuilder, &wrapped_key_blob) && |
| keymaster.exportKey(wrapped_key_blob, exported_key_string)) { |
| ADD_FAILURE() << "generateKey succeeded but importKey failed"; |
| } |
| return false; |
| } |
| |
| bool CreateHwWrappedKey(std::vector<uint8_t> *master_key, |
| std::vector<uint8_t> *exported_key) { |
| *master_key = GenerateTestKey(kHwWrappedKeySize); |
| |
| Keymaster keymaster; |
| if (!keymaster) { |
| ADD_FAILURE() << "Unable to find keymaster"; |
| return false; |
| } |
| std::string master_key_string(master_key->begin(), master_key->end()); |
| std::string exported_key_string; |
| // Make two attempts to create a key, first with and then without |
| // rollback resistance. |
| if (TryPrepareHwWrappedKey(keymaster, master_key_string, &exported_key_string, |
| true) || |
| TryPrepareHwWrappedKey(keymaster, master_key_string, &exported_key_string, |
| false)) { |
| exported_key->assign(exported_key_string.begin(), |
| exported_key_string.end()); |
| return true; |
| } |
| GTEST_LOG_(INFO) << "Skipping test because device doesn't support " |
| "hardware-wrapped keys"; |
| return false; |
| } |
| |
| static void PushBigEndian32(uint32_t val, std::vector<uint8_t> *vec) { |
| for (int i = 24; i >= 0; i -= 8) { |
| vec->push_back((val >> i) & 0xFF); |
| } |
| } |
| |
| static void GetFixedInputString(uint32_t counter, |
| const std::vector<uint8_t> &label, |
| const std::vector<uint8_t> &context, |
| uint32_t derived_key_len, |
| std::vector<uint8_t> *fixed_input_string) { |
| PushBigEndian32(counter, fixed_input_string); |
| fixed_input_string->insert(fixed_input_string->end(), label.begin(), |
| label.end()); |
| fixed_input_string->push_back(0); |
| fixed_input_string->insert(fixed_input_string->end(), context.begin(), |
| context.end()); |
| PushBigEndian32(derived_key_len, fixed_input_string); |
| } |
| |
| static bool AesCmacKdfHelper(const std::vector<uint8_t> &key, |
| const std::vector<uint8_t> &label, |
| const std::vector<uint8_t> &context, |
| uint32_t output_key_size, |
| std::vector<uint8_t> *output_data) { |
| output_data->resize(output_key_size); |
| for (size_t count = 0; count < (output_key_size / kAesBlockSize); count++) { |
| std::vector<uint8_t> fixed_input_string; |
| GetFixedInputString(count + 1, label, context, (output_key_size * 8), |
| &fixed_input_string); |
| if (!AES_CMAC(output_data->data() + (kAesBlockSize * count), key.data(), |
| key.size(), fixed_input_string.data(), |
| fixed_input_string.size())) { |
| ADD_FAILURE() |
| << "AES_CMAC failed while deriving subkey from HW wrapped key"; |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| bool DeriveHwWrappedEncryptionKey(const std::vector<uint8_t> &master_key, |
| std::vector<uint8_t> *enc_key) { |
| std::vector<uint8_t> label{0x00, 0x00, 0x40, 0x00, 0x00, 0x00, |
| 0x00, 0x00, 0x00, 0x00, 0x20}; |
| |
| std::vector<uint8_t> ctx; |
| |
| if (!GetKdfContext(&ctx)) return false; |
| |
| return AesCmacKdfHelper(master_key, label, ctx, kAes256XtsKeySize, enc_key); |
| } |
| |
| bool DeriveHwWrappedRawSecret(const std::vector<uint8_t> &master_key, |
| std::vector<uint8_t> *secret) { |
| std::vector<uint8_t> label{0x00, 0x00, 0x40, 0x00, 0x00, 0x00, |
| 0x00, 0x00, 0x00, 0x00, 0x20}; |
| // Context in fixed input string comprises of software provided context, |
| // padding to eight bytes (if required) and the key policy. |
| std::vector<uint8_t> context = {'r', 'a', 'w', ' ', 's', 'e', 'c', |
| 'r', 'e', 't', 0x0, 0x0, 0x0, 0x0, |
| 0x0, 0x0, 0x00, 0x00, 0x00, 0x02, 0x17, |
| 0x00, 0x80, 0x50, 0x0, 0x0, 0x0, 0x0}; |
| |
| return AesCmacKdfHelper(master_key, label, context, kAes256KeySize, secret); |
| } |
| |
| } // namespace kernel |
| } // namespace android |
