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Evict adoptable storage CE and DE keys when possible am: 1eddb7cb6d am: 51961be5c0 am: 11dd35816f

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Original change: https://android-review.googlesource.com/c/platform/system/vold/+/2685268

Change-Id: Icbdc9126a4ff2738bd5c3bd09e80aaa55076bec6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
This commit is contained in:
Eric Biggers 2023-10-06 21:46:24 +00:00 committed by Automerger Merge Worker
commit 7ad54533d6
1 changed files with 81 additions and 55 deletions
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136
FsCrypt.cpp
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@ -106,15 +106,25 @@ std::set<userid_t> s_ephemeral_users;
// New CE keys that haven't been committed to disk yet
std::map<userid_t, KeyBuffer> s_new_ce_keys;
// CE key fixation operations that have been deferred to checkpoint commit
std::map<std::string, std::string> s_deferred_fixations;
// The system DE encryption policy
EncryptionPolicy s_device_policy;
// Map user ids to encryption policies
std::map<userid_t, EncryptionPolicy> s_de_policies;
std::map<userid_t, EncryptionPolicy> s_ce_policies;
// Struct that holds the EncryptionPolicy for each CE or DE key that is currently installed
// (added to the kernel) for a particular user
struct UserPolicies {
// Internal storage policy. Exists whenever a user's UserPolicies exists at all, and used
// instead of a map entry keyed by an empty UUID to make this invariant explicit.
EncryptionPolicy internal;
// Adoptable storage policies, indexed by (nonempty) volume UUID
std::map<std::string, EncryptionPolicy> adoptable;
};
// CE key fixation operations that have been deferred to checkpoint commit
std::map<std::string, std::string> s_deferred_fixations;
// The currently installed CE and DE keys for each user. Protected by VolumeManager::mCryptLock.
std::map<userid_t, UserPolicies> s_ce_policies;
std::map<userid_t, UserPolicies> s_de_policies;
} // namespace
@ -398,7 +408,7 @@ static bool create_de_key(userid_t user_id, bool ephemeral) {
return false;
EncryptionPolicy de_policy;
if (!install_storage_key(DATA_MNT_POINT, s_data_options, de_key, &de_policy)) return false;
s_de_policies[user_id] = de_policy;
s_de_policies[user_id].internal = de_policy;
LOG(INFO) << "Created DE key for user " << user_id;
return true;
}
@ -416,21 +426,11 @@ static bool create_ce_key(userid_t user_id, bool ephemeral) {
}
EncryptionPolicy ce_policy;
if (!install_storage_key(DATA_MNT_POINT, s_data_options, ce_key, &ce_policy)) return false;
s_ce_policies[user_id] = ce_policy;
s_ce_policies[user_id].internal = ce_policy;
LOG(INFO) << "Created CE key for user " << user_id;
return true;
}
static bool lookup_policy(const std::map<userid_t, EncryptionPolicy>& key_map, userid_t user_id,
EncryptionPolicy* policy) {
auto refi = key_map.find(user_id);
if (refi == key_map.end()) {
return false;
}
*policy = refi->second;
return true;
}
static bool is_numeric(const char* name) {
for (const char* p = name; *p != '\0'; p++) {
if (!isdigit(*p)) return false;
@ -470,8 +470,8 @@ static bool load_all_de_keys() {
}
EncryptionPolicy de_policy;
if (!install_storage_key(DATA_MNT_POINT, s_data_options, de_key, &de_policy)) return false;
auto ret = s_de_policies.insert({user_id, de_policy});
if (!ret.second && ret.first->second != de_policy) {
const auto& [existing, is_new] = s_de_policies.insert({user_id, {de_policy, {}}});
if (!is_new && existing->second.internal != de_policy) {
LOG(ERROR) << "DE policy for user" << user_id << " changed";
return false;
}
@ -484,9 +484,9 @@ static bool load_all_de_keys() {
// Attempt to reinstall CE keys for users that we think are unlocked.
static bool try_reload_ce_keys() {
for (const auto& it : s_ce_policies) {
if (!android::vold::reloadKeyFromSessionKeyring(DATA_MNT_POINT, it.second)) {
LOG(ERROR) << "Failed to load CE key from session keyring for user " << it.first;
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;
}
}
@ -549,8 +549,8 @@ static bool prepare_special_dirs() {
// On first boot, we'll be creating /data/data for the first time, and user
// 0's CE key will be installed already since it was just created. Take the
// opportunity to also set the encryption policy of /data/data right away.
EncryptionPolicy ce_policy;
if (lookup_policy(s_ce_policies, 0, &ce_policy)) {
if (s_ce_policies.count(0) != 0) {
const EncryptionPolicy& ce_policy = s_ce_policies[0].internal;
if (!prepare_dir_with_policy(data_data_dir, 0771, AID_SYSTEM, AID_SYSTEM, ce_policy)) {
// Preparing /data/data failed, yet we had just generated a new CE
// key because one wasn't stored. Before erroring out, try deleting
@ -671,29 +671,34 @@ static void drop_caches_if_needed() {
}
}
static bool evict_ce_key(userid_t user_id) {
// Evicts all the user's keys of one type from all volumes (internal and adoptable).
// This evicts either CE keys or DE keys, depending on which map is passed.
static bool evict_user_keys(std::map<userid_t, UserPolicies>& policy_map, userid_t user_id) {
bool success = true;
EncryptionPolicy policy;
// If we haven't loaded the CE key, no need to evict it.
if (lookup_policy(s_ce_policies, user_id, &policy)) {
success &= android::vold::evictKey(DATA_MNT_POINT, policy);
auto it = policy_map.find(user_id);
if (it != policy_map.end()) {
const UserPolicies& policies = it->second;
success &= android::vold::evictKey(BuildDataPath(""), policies.internal);
for (const auto& [volume_uuid, policy] : policies.adoptable) {
success &= android::vold::evictKey(BuildDataPath(volume_uuid), policy);
}
policy_map.erase(it);
drop_caches_if_needed();
}
s_ce_policies.erase(user_id);
return success;
}
// Evicts and destroys all CE and DE keys for a user. This is called when the user is removed.
bool fscrypt_destroy_user_key(userid_t user_id) {
LOG(DEBUG) << "fscrypt_destroy_user_key(" << user_id << ")";
if (!IsFbeEnabled()) {
return true;
}
bool success = true;
success &= evict_ce_key(user_id);
EncryptionPolicy de_policy;
success &= lookup_policy(s_de_policies, user_id, &de_policy) &&
android::vold::evictKey(DATA_MNT_POINT, de_policy);
s_de_policies.erase(user_id);
success &= evict_user_keys(s_ce_policies, user_id);
success &= evict_user_keys(s_de_policies, user_id);
if (!s_ephemeral_users.erase(user_id)) {
auto ce_path = get_ce_key_directory_path(user_id);
if (!s_new_ce_keys.erase(user_id)) {
@ -746,7 +751,7 @@ static std::string volume_secdiscardable_path(const std::string& volume_uuid) {
}
static bool read_or_create_volkey(const std::string& misc_path, const std::string& volume_uuid,
EncryptionPolicy* policy) {
UserPolicies& user_policies, EncryptionPolicy* policy) {
auto secdiscardable_path = volume_secdiscardable_path(volume_uuid);
std::string secdiscardable_hash;
if (android::vold::pathExists(secdiscardable_path)) {
@ -767,6 +772,7 @@ static bool read_or_create_volkey(const std::string& misc_path, const std::strin
if (!retrieveOrGenerateKey(key_path, key_path + "_tmp", auth, makeGen(options), &key))
return false;
if (!install_storage_key(BuildDataPath(volume_uuid), options, key, policy)) return false;
user_policies.adoptable[volume_uuid] = *policy;
return true;
}
@ -874,13 +880,15 @@ void fscrypt_deferred_fixate_ce_keys() {
std::vector<int> fscrypt_get_unlocked_users() {
std::vector<int> user_ids;
for (const auto& it : s_ce_policies) {
user_ids.push_back(it.first);
for (const auto& [user_id, user_policies] : s_ce_policies) {
user_ids.push_back(user_id);
}
return user_ids;
}
// TODO: rename to 'install' for consistency, and take flags to know which keys to install
// Unlocks internal CE storage for the given user. This only unlocks internal storage, since
// fscrypt_prepare_user_storage() has to be called for each adoptable storage volume anyway (since
// the volume might have been absent when the user was created), and that handles the unlocking.
bool fscrypt_unlock_user_key(userid_t user_id, int serial, const std::string& secret_hex) {
LOG(DEBUG) << "fscrypt_unlock_user_key " << user_id << " serial=" << serial;
if (!IsFbeEnabled()) return true;
@ -894,18 +902,16 @@ bool fscrypt_unlock_user_key(userid_t user_id, int serial, const std::string& se
if (!read_and_fixate_user_ce_key(user_id, *auth, &ce_key)) return false;
EncryptionPolicy ce_policy;
if (!install_storage_key(DATA_MNT_POINT, s_data_options, ce_key, &ce_policy)) return false;
s_ce_policies[user_id] = ce_policy;
s_ce_policies[user_id].internal = ce_policy;
LOG(DEBUG) << "Installed ce key for user " << user_id;
return true;
}
// TODO: rename to 'evict' for consistency
// Locks CE storage for the given user. This locks both internal and adoptable storage.
bool fscrypt_lock_user_key(userid_t user_id) {
LOG(DEBUG) << "fscrypt_lock_user_key " << user_id;
if (IsFbeEnabled()) {
return evict_ce_key(user_id);
}
return true;
if (!IsFbeEnabled()) return true;
return evict_user_keys(s_ce_policies, user_id);
}
static bool prepare_subdirs(const std::string& action, const std::string& volume_uuid,
@ -955,14 +961,18 @@ bool fscrypt_prepare_user_storage(const std::string& volume_uuid, userid_t user_
auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
if (IsFbeEnabled()) {
auto it = s_de_policies.find(user_id);
if (it == s_de_policies.end()) {
LOG(ERROR) << "Cannot find DE policy for user " << user_id;
return false;
}
UserPolicies& user_de_policies = it->second;
if (volume_uuid.empty()) {
if (!lookup_policy(s_de_policies, user_id, &de_policy)) {
LOG(ERROR) << "Cannot find DE policy for user " << user_id;
return false;
}
de_policy = user_de_policies.internal;
} else {
auto misc_de_empty_volume_path = android::vold::BuildDataMiscDePath("", user_id);
if (!read_or_create_volkey(misc_de_empty_volume_path, volume_uuid, &de_policy)) {
if (!read_or_create_volkey(misc_de_empty_volume_path, volume_uuid, user_de_policies,
&de_policy)) {
return false;
}
}
@ -999,14 +1009,18 @@ bool fscrypt_prepare_user_storage(const std::string& volume_uuid, userid_t user_
auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
if (IsFbeEnabled()) {
auto it = s_ce_policies.find(user_id);
if (it == s_ce_policies.end()) {
LOG(ERROR) << "Cannot find CE policy for user " << user_id;
return false;
}
UserPolicies& user_ce_policies = it->second;
if (volume_uuid.empty()) {
if (!lookup_policy(s_ce_policies, user_id, &ce_policy)) {
LOG(ERROR) << "Cannot find CE policy for user " << user_id;
return false;
}
ce_policy = user_ce_policies.internal;
} else {
auto misc_ce_empty_volume_path = android::vold::BuildDataMiscCePath("", user_id);
if (!read_or_create_volkey(misc_ce_empty_volume_path, volume_uuid, &ce_policy)) {
if (!read_or_create_volkey(misc_ce_empty_volume_path, volume_uuid, user_ce_policies,
&ce_policy)) {
return false;
}
}
@ -1136,6 +1150,13 @@ static bool destroy_volume_keys(const std::string& directory_path, const std::st
return res;
}
static void erase_volume_policies(std::map<userid_t, UserPolicies>& policy_map,
const std::string& volume_uuid) {
for (auto& [user_id, user_policies] : policy_map) {
user_policies.adoptable.erase(volume_uuid);
}
}
// Destroys all CE and DE keys for an adoptable storage volume that is permanently going away.
// Requires VolumeManager::mCryptLock.
bool fscrypt_destroy_volume_keys(const std::string& volume_uuid) {
@ -1146,5 +1167,10 @@ bool fscrypt_destroy_volume_keys(const std::string& volume_uuid) {
res &= android::vold::runSecdiscardSingle(secdiscardable_path);
res &= destroy_volume_keys("/data/misc_ce", volume_uuid);
res &= destroy_volume_keys("/data/misc_de", volume_uuid);
// Drop the CE and DE policies stored in memory, as they are not needed anymore. Note that it's
// not necessary to also evict the corresponding keys from the kernel, as that happens
// automatically as a result of the volume being unmounted.
erase_volume_policies(s_ce_policies, volume_uuid);
erase_volume_policies(s_de_policies, volume_uuid);
return res;
}