From 01604fb13f078b33d4ab03700c20772c8231be20 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Mon, 7 Aug 2023 19:35:01 +0000 Subject: [PATCH] Revert "fskeyring & userspace reboot: support CE keys" Userspace reboot turned out to be a dead end and is no longer supported. Therefore, remove the code from vold that handled keeping CE storage unlocked past the userdata filesystem being unmounted and mounted. This is a revert of commit 1c6731c64972 (https://r.android.com/1254615) with various conflicts resolved. Bug: 292469129 Change-Id: If530edaf7c1566dd3bd8b1322f935f38a2e66beb Merged-In: If530edaf7c1566dd3bd8b1322f935f38a2e66beb (cherry picked from commit 2b97a88ba4f29b98efd8b31ce6f2f36a2334acaf) --- FsCrypt.cpp | 18 -------- KeyUtil.cpp | 125 +++++++--------------------------------------------- KeyUtil.h | 18 ++------ 3 files changed, 20 insertions(+), 141 deletions(-) diff --git a/FsCrypt.cpp b/FsCrypt.cpp index ecb3c81..45b062d 100644 --- a/FsCrypt.cpp +++ b/FsCrypt.cpp @@ -482,17 +482,6 @@ static bool load_all_de_keys() { return true; } -// Attempt to reinstall CE keys for users that we think are unlocked. -static bool try_reload_ce_keys() { - for (const auto& [user_id, user_policies] : s_ce_policies) { - if (!android::vold::reloadKeyFromSessionKeyring(DATA_MNT_POINT, user_policies.internal)) { - LOG(ERROR) << "Failed to load CE key from session keyring for user " << user_id; - return false; - } - } - return true; -} - bool fscrypt_initialize_systemwide_keys() { LOG(INFO) << "fscrypt_initialize_systemwide_keys"; @@ -621,13 +610,6 @@ bool fscrypt_init_user0() { return false; } - // In some scenarios (e.g. userspace reboot) we might unmount userdata - // without doing a hard reboot. If CE keys were stored in fs keyring then - // they will be lost after unmount. Attempt to re-install them. - if (IsFbeEnabled() && android::vold::isFsKeyringSupported()) { - if (!try_reload_ce_keys()) return false; - } - fscrypt_init_user0_done = true; return true; } diff --git a/KeyUtil.cpp b/KeyUtil.cpp index 5a8b550..9e8920d 100644 --- a/KeyUtil.cpp +++ b/KeyUtil.cpp @@ -164,7 +164,7 @@ static bool fscryptKeyring(key_serial_t* device_keyring) { return true; } -// Add an encryption key of type "logon" to the global session keyring. +// Add an encryption key to the legacy global session keyring. static bool installKeyLegacy(const KeyBuffer& key, const std::string& raw_ref) { // Place fscrypt_key into automatically zeroing buffer. KeyBuffer fsKeyBuffer(sizeof(fscrypt_key)); @@ -187,32 +187,6 @@ static bool installKeyLegacy(const KeyBuffer& key, const std::string& raw_ref) { return true; } -// Installs fscrypt-provisioning key into session level kernel keyring. -// This allows for the given key to be installed back into filesystem keyring. -// For more context see reloadKeyFromSessionKeyring. -static bool installProvisioningKey(const KeyBuffer& key, const std::string& ref, - const fscrypt_key_specifier& key_spec) { - key_serial_t device_keyring; - if (!fscryptKeyring(&device_keyring)) return false; - - // Place fscrypt_provisioning_key_payload into automatically zeroing buffer. - KeyBuffer buf(sizeof(fscrypt_provisioning_key_payload) + key.size(), 0); - fscrypt_provisioning_key_payload& provisioning_key = - *reinterpret_cast(buf.data()); - memcpy(provisioning_key.raw, key.data(), key.size()); - provisioning_key.type = key_spec.type; - - key_serial_t key_id = add_key("fscrypt-provisioning", ref.c_str(), (void*)&provisioning_key, - buf.size(), device_keyring); - if (key_id == -1) { - PLOG(ERROR) << "Failed to insert fscrypt-provisioning key for " << ref - << " into session keyring"; - return false; - } - LOG(DEBUG) << "Added fscrypt-provisioning key for " << ref << " to session keyring"; - return true; -} - // Build a struct fscrypt_key_specifier for use in the key management ioctls. static bool buildKeySpecifier(fscrypt_key_specifier* spec, const EncryptionPolicy& policy) { switch (policy.options.version) { @@ -240,34 +214,6 @@ static bool buildKeySpecifier(fscrypt_key_specifier* spec, const EncryptionPolic } } -// Installs key into keyring of a filesystem mounted on |mountpoint|. -// -// It's callers responsibility to fill key specifier, and either arg->raw or arg->key_id. -// -// In case arg->key_spec.type equals to FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER -// arg->key_spec.u.identifier will be populated with raw key reference generated -// by kernel. -// -// For documentation on difference between arg->raw and arg->key_id see -// https://www.kernel.org/doc/html/latest/filesystems/fscrypt.html#fs-ioc-add-encryption-key -static bool installFsKeyringKey(const std::string& mountpoint, const EncryptionOptions& options, - fscrypt_add_key_arg* arg) { - if (options.use_hw_wrapped_key) arg->__flags |= __FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED; - - android::base::unique_fd fd(open(mountpoint.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC)); - if (fd == -1) { - PLOG(ERROR) << "Failed to open " << mountpoint << " to install key"; - return false; - } - - if (ioctl(fd, FS_IOC_ADD_ENCRYPTION_KEY, arg) != 0) { - PLOG(ERROR) << "Failed to install fscrypt key to " << mountpoint; - return false; - } - - return true; -} - bool installKey(const std::string& mountpoint, const EncryptionOptions& options, const KeyBuffer& key, EncryptionPolicy* policy) { const std::lock_guard lock(fscrypt_keyring_mutex); @@ -304,24 +250,33 @@ bool installKey(const std::string& mountpoint, const EncryptionOptions& options, return false; } + if (options.use_hw_wrapped_key) arg->__flags |= __FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED; + // Provide the raw key. arg->raw_size = key.size(); memcpy(arg->raw, key.data(), key.size()); - if (!installFsKeyringKey(mountpoint, options, arg)) return false; + android::base::unique_fd fd(open(mountpoint.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC)); + if (fd == -1) { + PLOG(ERROR) << "Failed to open " << mountpoint << " to install key"; + return false; + } + + if (ioctl(fd, FS_IOC_ADD_ENCRYPTION_KEY, arg) != 0) { + PLOG(ERROR) << "Failed to install fscrypt key to " << mountpoint; + return false; + } if (arg->key_spec.type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) { // Retrieve the key identifier that the kernel computed. policy->key_raw_ref = std::string((char*)arg->key_spec.u.identifier, FSCRYPT_KEY_IDENTIFIER_SIZE); } - std::string ref = keyrefstring(policy->key_raw_ref); - LOG(DEBUG) << "Installed fscrypt key with ref " << ref << " to " << mountpoint; - - if (!installProvisioningKey(key, ref, arg->key_spec)) return false; + LOG(DEBUG) << "Installed fscrypt key with ref " << keyrefstring(policy->key_raw_ref) << " to " + << mountpoint; return true; } -// Remove an encryption key of type "logon" from the global session keyring. +// Remove an encryption key from the legacy global session keyring. static bool evictKeyLegacy(const std::string& raw_ref) { key_serial_t device_keyring; if (!fscryptKeyring(&device_keyring)) return false; @@ -344,26 +299,6 @@ static bool evictKeyLegacy(const std::string& raw_ref) { return success; } -static bool evictProvisioningKey(const std::string& ref) { - key_serial_t device_keyring; - if (!fscryptKeyring(&device_keyring)) { - return false; - } - - auto key_serial = keyctl_search(device_keyring, "fscrypt-provisioning", ref.c_str(), 0); - if (key_serial == -1 && errno != ENOKEY) { - PLOG(ERROR) << "Error searching session keyring for fscrypt-provisioning key for " << ref; - return false; - } - - if (key_serial != -1 && keyctl_unlink(key_serial, device_keyring) != 0) { - PLOG(ERROR) << "Failed to unlink fscrypt-provisioning key for " << ref - << " from session keyring"; - return false; - } - return true; -} - static void waitForBusyFiles(const struct fscrypt_key_specifier key_spec, const std::string ref, const std::string mountpoint) { android::base::unique_fd fd(open(mountpoint.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC)); @@ -462,8 +397,6 @@ bool evictKey(const std::string& mountpoint, const EncryptionPolicy& policy) { std::thread busyFilesThread(waitForBusyFiles, arg.key_spec, ref, mountpoint); busyFilesThread.detach(); } - - if (!evictProvisioningKey(ref)) return false; return true; } @@ -485,31 +418,5 @@ bool retrieveOrGenerateKey(const std::string& key_path, const std::string& tmp_p return true; } -bool reloadKeyFromSessionKeyring(const std::string& mountpoint, const EncryptionPolicy& policy) { - key_serial_t device_keyring; - if (!fscryptKeyring(&device_keyring)) { - return false; - } - - std::string ref = keyrefstring(policy.key_raw_ref); - auto key_serial = keyctl_search(device_keyring, "fscrypt-provisioning", ref.c_str(), 0); - if (key_serial == -1) { - PLOG(ERROR) << "Failed to find fscrypt-provisioning key for " << ref - << " in session keyring"; - return false; - } - - LOG(DEBUG) << "Installing fscrypt-provisioning key for " << ref << " back into " << mountpoint - << " fs-keyring"; - - struct fscrypt_add_key_arg arg; - memset(&arg, 0, sizeof(arg)); - if (!buildKeySpecifier(&arg.key_spec, policy)) return false; - arg.key_id = key_serial; - if (!installFsKeyringKey(mountpoint, policy.options, &arg)) return false; - - return true; -} - } // namespace vold } // namespace android diff --git a/KeyUtil.h b/KeyUtil.h index 5940b8a..17a234e 100644 --- a/KeyUtil.h +++ b/KeyUtil.h @@ -49,16 +49,11 @@ bool isFsKeyringSupported(void); // on the specified filesystem using the specified encryption policy version. // // For v1 policies, we use FS_IOC_ADD_ENCRYPTION_KEY if the kernel supports it. -// Otherwise we add the key to the global session keyring as a "logon" key. +// Otherwise we add the key to the legacy global session keyring. // // For v2 policies, we always use FS_IOC_ADD_ENCRYPTION_KEY; it's the only way // the kernel supports. // -// If kernel supports FS_IOC_ADD_ENCRYPTION_KEY, also installs key of -// fscrypt-provisioning type to the global session keyring. This makes it -// possible to unmount and then remount mountpoint without losing the file-based -// key. -// // Returns %true on success, %false on failure. On success also sets *policy // to the EncryptionPolicy used to refer to this key. bool installKey(const std::string& mountpoint, const android::fscrypt::EncryptionOptions& options, @@ -66,10 +61,10 @@ bool installKey(const std::string& mountpoint, const android::fscrypt::Encryptio // Evict a file-based encryption key from the kernel. // -// This undoes the effect of installKey(). +// We use FS_IOC_REMOVE_ENCRYPTION_KEY if the kernel supports it. Otherwise we +// remove the key from the legacy global session keyring. // -// If the kernel doesn't support the filesystem-level keyring, the caller is -// responsible for dropping caches. +// In the latter case, the caller is responsible for dropping caches. bool evictKey(const std::string& mountpoint, const android::fscrypt::EncryptionPolicy& policy); // Retrieves the key from the named directory, or generates it if it doesn't @@ -78,11 +73,6 @@ bool retrieveOrGenerateKey(const std::string& key_path, const std::string& tmp_p const KeyAuthentication& key_authentication, const KeyGeneration& gen, KeyBuffer* key); -// Re-installs a file-based encryption key of fscrypt-provisioning type from the -// global session keyring back into fs keyring of the mountpoint. -bool reloadKeyFromSessionKeyring(const std::string& mountpoint, - const android::fscrypt::EncryptionPolicy& policy); - } // namespace vold } // namespace android