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@ -57,6 +57,7 @@
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#include <android-base/logging.h>
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#include <android-base/properties.h>
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#include <android-base/stringprintf.h>
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#include <android-base/strings.h>
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#include <android-base/unique_fd.h>
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using android::base::StringPrintf;
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@ -70,7 +71,10 @@ namespace {
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struct PolicyKeyRef {
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std::string contents_mode;
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std::string filenames_mode;
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int policy_version;
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std::string key_raw_ref;
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PolicyKeyRef() : policy_version(0) {}
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};
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const std::string device_key_dir = std::string() + DATA_MNT_POINT + fscrypt_unencrypted_folder;
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@ -199,13 +203,66 @@ static bool read_and_fixate_user_ce_key(userid_t user_id,
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return false;
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}
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// Retrieve the options to use for encryption policies on the /data filesystem.
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static void get_data_file_encryption_options(PolicyKeyRef* key_ref) {
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auto entry = GetEntryForMountPoint(&fstab_default, DATA_MNT_POINT);
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if (entry == nullptr) {
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return;
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}
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key_ref->contents_mode = entry->file_contents_mode;
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key_ref->filenames_mode = entry->file_names_mode;
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key_ref->policy_version = entry->file_policy_version;
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}
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// Retrieve the version to use for encryption policies on the /data filesystem.
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static int get_data_file_policy_version(void) {
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auto entry = GetEntryForMountPoint(&fstab_default, DATA_MNT_POINT);
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if (entry == nullptr) {
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return 0;
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}
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return entry->file_policy_version;
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}
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// Retrieve the options to use for encryption policies on adoptable storage.
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static bool get_volume_file_encryption_options(PolicyKeyRef* key_ref) {
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key_ref->contents_mode =
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android::base::GetProperty("ro.crypto.volume.contents_mode", "aes-256-xts");
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key_ref->filenames_mode =
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android::base::GetProperty("ro.crypto.volume.filenames_mode", "aes-256-heh");
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key_ref->policy_version = 1;
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std::string raw_flags = android::base::GetProperty("ro.crypto.volume.flags", "");
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auto flags = android::base::Split(raw_flags, "+");
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for (const auto& flag : flags) {
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if (flag == "v1") {
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key_ref->policy_version = 1;
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} else if (flag == "v2") {
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key_ref->policy_version = 2;
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} else {
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LOG(ERROR) << "Unknown flag in ro.crypto.volume.flags: " << flag;
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return false;
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}
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}
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return true;
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}
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// Install a key for use by encrypted files on the /data filesystem.
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static bool install_data_key(const KeyBuffer& key, std::string* raw_ref) {
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return android::vold::installKey(key, DATA_MNT_POINT, get_data_file_policy_version(), raw_ref);
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}
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// Evict a key for use by encrypted files on the /data filesystem.
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static bool evict_data_key(const std::string& raw_ref) {
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return android::vold::evictKey(DATA_MNT_POINT, raw_ref, get_data_file_policy_version());
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}
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static bool read_and_install_user_ce_key(userid_t user_id,
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const android::vold::KeyAuthentication& auth) {
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if (s_ce_key_raw_refs.count(user_id) != 0) return true;
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KeyBuffer ce_key;
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if (!read_and_fixate_user_ce_key(user_id, auth, &ce_key)) return false;
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std::string ce_raw_ref;
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if (!android::vold::installKey(ce_key, &ce_raw_ref)) return false;
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if (!install_data_key(ce_key, &ce_raw_ref)) return false;
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s_ce_keys[user_id] = std::move(ce_key);
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s_ce_key_raw_refs[user_id] = ce_raw_ref;
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LOG(DEBUG) << "Installed ce key for user " << user_id;
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@ -255,10 +312,10 @@ static bool create_and_install_user_keys(userid_t user_id, bool create_ephemeral
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return false;
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}
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std::string de_raw_ref;
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if (!android::vold::installKey(de_key, &de_raw_ref)) return false;
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if (!install_data_key(de_key, &de_raw_ref)) return false;
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s_de_key_raw_refs[user_id] = de_raw_ref;
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std::string ce_raw_ref;
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if (!android::vold::installKey(ce_key, &ce_raw_ref)) return false;
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if (!install_data_key(ce_key, &ce_raw_ref)) return false;
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s_ce_keys[user_id] = ce_key;
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s_ce_key_raw_refs[user_id] = ce_raw_ref;
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LOG(DEBUG) << "Created keys for user " << user_id;
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@ -276,19 +333,10 @@ static bool lookup_key_ref(const std::map<userid_t, std::string>& key_map, useri
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return true;
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}
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static void get_data_file_encryption_modes(PolicyKeyRef* key_ref) {
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auto entry = GetEntryForMountPoint(&fstab_default, DATA_MNT_POINT);
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if (entry == nullptr) {
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return;
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}
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key_ref->contents_mode = entry->file_contents_mode;
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key_ref->filenames_mode = entry->file_names_mode;
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}
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static bool ensure_policy(const PolicyKeyRef& key_ref, const std::string& path) {
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return fscrypt_policy_ensure(path.c_str(), key_ref.key_raw_ref.data(),
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key_ref.key_raw_ref.size(), key_ref.contents_mode.c_str(),
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key_ref.filenames_mode.c_str()) == 0;
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key_ref.filenames_mode.c_str(), key_ref.policy_version) == 0;
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}
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static bool is_numeric(const char* name) {
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@ -325,7 +373,7 @@ static bool load_all_de_keys() {
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KeyBuffer key;
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if (!android::vold::retrieveKey(key_path, kEmptyAuthentication, &key)) return false;
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std::string raw_ref;
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if (!android::vold::installKey(key, &raw_ref)) return false;
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if (!install_data_key(key, &raw_ref)) return false;
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s_de_key_raw_refs[user_id] = raw_ref;
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LOG(DEBUG) << "Installed de key for user " << user_id;
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}
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@ -344,14 +392,18 @@ bool fscrypt_initialize_systemwide_keys() {
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}
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PolicyKeyRef device_ref;
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get_data_file_encryption_options(&device_ref);
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if (!android::vold::retrieveAndInstallKey(true, kEmptyAuthentication, device_key_path,
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device_key_temp, &device_ref.key_raw_ref))
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device_key_temp, "", device_ref.policy_version,
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&device_ref.key_raw_ref))
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return false;
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get_data_file_encryption_modes(&device_ref);
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std::string modestring = device_ref.contents_mode + ":" + device_ref.filenames_mode;
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std::string mode_filename = std::string("/data") + fscrypt_key_mode;
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if (!android::vold::writeStringToFile(modestring, mode_filename)) return false;
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std::string options_string =
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StringPrintf("%s:%s:v%d", device_ref.contents_mode.c_str(),
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device_ref.filenames_mode.c_str(), device_ref.policy_version);
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std::string options_filename = std::string("/data") + fscrypt_key_mode;
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if (!android::vold::writeStringToFile(options_string, options_filename)) return false;
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std::string ref_filename = std::string("/data") + fscrypt_key_ref;
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if (!android::vold::writeStringToFile(device_ref.key_raw_ref, ref_filename)) return false;
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@ -360,7 +412,7 @@ bool fscrypt_initialize_systemwide_keys() {
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KeyBuffer per_boot_key;
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if (!android::vold::randomKey(&per_boot_key)) return false;
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std::string per_boot_raw_ref;
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if (!android::vold::installKey(per_boot_key, &per_boot_raw_ref)) return false;
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if (!install_data_key(per_boot_key, &per_boot_raw_ref)) return false;
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std::string per_boot_ref_filename = std::string("/data") + fscrypt_key_per_boot_ref;
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if (!android::vold::writeStringToFile(per_boot_raw_ref, per_boot_ref_filename)) return false;
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LOG(INFO) << "Wrote per boot key reference to:" << per_boot_ref_filename;
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@ -419,15 +471,20 @@ bool fscrypt_vold_create_user_key(userid_t user_id, int serial, bool ephemeral)
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}
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// "Lock" all encrypted directories whose key has been removed. This is needed
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// because merely removing the keyring key doesn't affect inodes in the kernel's
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// inode cache whose per-file key was already set up. So to remove the per-file
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// keys and make the files "appear encrypted", these inodes must be evicted.
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// in the case where the keys are being put in the session keyring (rather in
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// the newer filesystem-level keyrings), because removing a key from the session
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// keyring doesn't affect inodes in the kernel's inode cache whose per-file key
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// was already set up. So to remove the per-file keys and make the files
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// "appear encrypted", these inodes must be evicted.
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//
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// To do this, sync() to clean all dirty inodes, then drop all reclaimable slab
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// objects systemwide. This is overkill, but it's the best available method
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// currently. Don't use drop_caches mode "3" because that also evicts pagecache
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// for in-use files; all files relevant here are already closed and sync'ed.
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static void drop_caches() {
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static void drop_caches_if_needed() {
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if (android::vold::isFsKeyringSupported()) {
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return;
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}
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sync();
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if (!writeStringToFile("2", "/proc/sys/vm/drop_caches")) {
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PLOG(ERROR) << "Failed to drop caches during key eviction";
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@ -440,8 +497,8 @@ static bool evict_ce_key(userid_t user_id) {
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std::string raw_ref;
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// If we haven't loaded the CE key, no need to evict it.
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if (lookup_key_ref(s_ce_key_raw_refs, user_id, &raw_ref)) {
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success &= android::vold::evictKey(raw_ref);
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drop_caches();
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success &= evict_data_key(raw_ref);
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drop_caches_if_needed();
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}
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s_ce_key_raw_refs.erase(user_id);
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return success;
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@ -455,8 +512,7 @@ bool fscrypt_destroy_user_key(userid_t user_id) {
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bool success = true;
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std::string raw_ref;
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success &= evict_ce_key(user_id);
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success &=
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lookup_key_ref(s_de_key_raw_refs, user_id, &raw_ref) && android::vold::evictKey(raw_ref);
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success &= lookup_key_ref(s_de_key_raw_refs, user_id, &raw_ref) && evict_data_key(raw_ref);
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s_de_key_raw_refs.erase(user_id);
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auto it = s_ephemeral_users.find(user_id);
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if (it != s_ephemeral_users.end()) {
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@ -546,14 +602,12 @@ static bool read_or_create_volkey(const std::string& misc_path, const std::strin
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return false;
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}
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android::vold::KeyAuthentication auth("", secdiscardable_hash);
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if (!android::vold::retrieveAndInstallKey(true, auth, key_path, key_path + "_tmp",
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&key_ref->key_raw_ref))
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return false;
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key_ref->contents_mode =
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android::base::GetProperty("ro.crypto.volume.contents_mode", "aes-256-xts");
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key_ref->filenames_mode =
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android::base::GetProperty("ro.crypto.volume.filenames_mode", "aes-256-heh");
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return true;
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if (!get_volume_file_encryption_options(key_ref)) return false;
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return android::vold::retrieveAndInstallKey(true, auth, key_path, key_path + "_tmp",
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volume_uuid, key_ref->policy_version,
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&key_ref->key_raw_ref);
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}
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static bool destroy_volkey(const std::string& misc_path, const std::string& volume_uuid) {
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@ -701,7 +755,7 @@ bool fscrypt_prepare_user_storage(const std::string& volume_uuid, userid_t user_
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PolicyKeyRef de_ref;
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if (volume_uuid.empty()) {
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if (!lookup_key_ref(s_de_key_raw_refs, user_id, &de_ref.key_raw_ref)) return false;
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get_data_file_encryption_modes(&de_ref);
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get_data_file_encryption_options(&de_ref);
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if (!ensure_policy(de_ref, system_de_path)) return false;
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if (!ensure_policy(de_ref, misc_de_path)) return false;
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if (!ensure_policy(de_ref, vendor_de_path)) return false;
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@ -732,7 +786,7 @@ bool fscrypt_prepare_user_storage(const std::string& volume_uuid, userid_t user_
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PolicyKeyRef ce_ref;
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if (volume_uuid.empty()) {
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if (!lookup_key_ref(s_ce_key_raw_refs, user_id, &ce_ref.key_raw_ref)) return false;
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get_data_file_encryption_modes(&ce_ref);
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get_data_file_encryption_options(&ce_ref);
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if (!ensure_policy(ce_ref, system_ce_path)) return false;
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if (!ensure_policy(ce_ref, misc_ce_path)) return false;
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if (!ensure_policy(ce_ref, vendor_ce_path)) return false;
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