1 files changed, 521 insertions, 0 deletions

diff --git a/crypto/ext4crypt/Ext4Crypt.cpp b/crypto/ext4crypt/Ext4Crypt.cpp
new file mode 100644
index 000000000..423147d66
--- /dev/null
+++ b/crypto/ext4crypt/Ext4Crypt.cpp
@@ -0,0 +1,521 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#include "Ext4Crypt.h"
+#include "Decrypt.h"
+
+#include "KeyStorage.h"
+#include "Utils.h"
+
+#include <algorithm>
+#include <iomanip>
+#include <map>
+#include <set>
+#include <sstream>
+#include <string>
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <openssl/sha.h>
+#include <selinux/android.h>
+#include <stdio.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <iostream>
+
+#include <private/android_filesystem_config.h>
+
+#include "ext4_crypt.h"
+#include "key_control.h"
+
+#include <hardware/gatekeeper.h>
+#include "HashPassword.h"
+
+#define EMULATED_USES_SELINUX 0
+#define MANAGE_MISC_DIRS 0
+
+#include <cutils/fs.h>
+
+#include <android-base/file.h>
+//#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+
+#define LOG(x) std::cout
+#define PLOG(x) std::cout
+#define DATA_MNT_POINT "/data"
+
+using android::base::StringPrintf;
+using android::vold::kEmptyAuthentication;
+
+// NOTE: keep in sync with StorageManager
+//static constexpr int FLAG_STORAGE_DE = 1 << 0; // moved to Decrypt.h
+//static constexpr int FLAG_STORAGE_CE = 1 << 1;
+
+namespace {
+const std::string device_key_dir = std::string() + DATA_MNT_POINT + e4crypt_unencrypted_folder;
+const std::string device_key_path = device_key_dir + "/key";
+const std::string device_key_temp = device_key_dir + "/temp";
+
+const std::string user_key_dir = std::string() + DATA_MNT_POINT + "/misc/vold/user_keys";
+const std::string user_key_temp = user_key_dir + "/temp";
+
+bool s_global_de_initialized = false;
+
+// Some users are ephemeral, don't try to wipe their keys from disk
+std::set<userid_t> s_ephemeral_users;
+
+// Map user ids to key references
+std::map<userid_t, std::string> s_de_key_raw_refs;
+std::map<userid_t, std::string> s_ce_key_raw_refs;
+// TODO abolish this map. Keys should not be long-lived in user memory, only kernel memory.
+// See b/26948053
+std::map<userid_t, std::string> s_ce_keys;
+
+// ext4enc:TODO get this const from somewhere good
+const int EXT4_KEY_DESCRIPTOR_SIZE = 8;
+
+// ext4enc:TODO Include structure from somewhere sensible
+// MUST be in sync with ext4_crypto.c in kernel
+constexpr int EXT4_ENCRYPTION_MODE_AES_256_XTS = 1;
+constexpr int EXT4_AES_256_XTS_KEY_SIZE = 64;
+constexpr int EXT4_MAX_KEY_SIZE = 64;
+struct ext4_encryption_key {
+    uint32_t mode;
+    char raw[EXT4_MAX_KEY_SIZE];
+    uint32_t size;
+};
+}
+
+static bool e4crypt_is_emulated() {
+    return false; //property_get_bool("persist.sys.emulate_fbe", false);
+}
+
+static const char* escape_null(const char* value) {
+    return (value == nullptr) ? "null" : value;
+}
+
+// Get raw keyref - used to make keyname and to pass to ioctl
+static std::string generate_key_ref(const char* key, int length) {
+    SHA512_CTX c;
+
+    SHA512_Init(&c);
+    SHA512_Update(&c, key, length);
+    unsigned char key_ref1[SHA512_DIGEST_LENGTH];
+    SHA512_Final(key_ref1, &c);
+
+    SHA512_Init(&c);
+    SHA512_Update(&c, key_ref1, SHA512_DIGEST_LENGTH);
+    unsigned char key_ref2[SHA512_DIGEST_LENGTH];
+    SHA512_Final(key_ref2, &c);
+
+    static_assert(EXT4_KEY_DESCRIPTOR_SIZE <= SHA512_DIGEST_LENGTH,
+                  "Hash too short for descriptor");
+    return std::string((char*)key_ref2, EXT4_KEY_DESCRIPTOR_SIZE);
+}
+
+static bool fill_key(const std::string& key, ext4_encryption_key* ext4_key) {
+    if (key.size() != EXT4_AES_256_XTS_KEY_SIZE) {
+        LOG(ERROR) << "Wrong size key " << key.size();
+        return false;
+    }
+    static_assert(EXT4_AES_256_XTS_KEY_SIZE <= sizeof(ext4_key->raw), "Key too long!");
+    ext4_key->mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+    ext4_key->size = key.size();
+    memset(ext4_key->raw, 0, sizeof(ext4_key->raw));
+    memcpy(ext4_key->raw, key.data(), key.size());
+    return true;
+}
+
+static std::string keyname(const std::string& raw_ref) {
+    std::ostringstream o;
+    o << "ext4:";
+    for (auto i : raw_ref) {
+        o << std::hex << std::setw(2) << std::setfill('0') << (int)i;
+    }
+    LOG(INFO) << "keyname is " << o.str() << "\n";
+    return o.str();
+}
+
+// Get the keyring we store all keys in
+static bool e4crypt_keyring(key_serial_t* device_keyring) {
+    *device_keyring = keyctl_search(KEY_SPEC_SESSION_KEYRING, "keyring", "e4crypt", 0);
+    if (*device_keyring == -1) {
+        PLOG(ERROR) << "Unable to find device keyring\n";
+        return false;
+    }
+    return true;
+}
+
+// Install password into global keyring
+// Return raw key reference for use in policy
+static bool install_key(const std::string& key, std::string* raw_ref) {
+    ext4_encryption_key ext4_key;
+    if (!fill_key(key, &ext4_key)) return false;
+    *raw_ref = generate_key_ref(ext4_key.raw, ext4_key.size);
+    auto ref = keyname(*raw_ref);
+    key_serial_t device_keyring;
+    if (!e4crypt_keyring(&device_keyring)) return false;
+    key_serial_t key_id =
+        add_key("logon", ref.c_str(), (void*)&ext4_key, sizeof(ext4_key), device_keyring);
+    if (key_id == -1) {
+        PLOG(ERROR) << "Failed to insert key into keyring " << device_keyring << "\n";
+        return false;
+    }
+    LOG(DEBUG) << "Added key " << key_id << " (" << ref << ") to keyring " << device_keyring
+               << " in process " << getpid() << "\n";
+    return true;
+}
+
+static std::string get_de_key_path(userid_t user_id) {
+LOG(INFO) << "get_de_key_path " << user_id << " " << StringPrintf("%s/de/%d", user_key_dir.c_str(), user_id) << "\n";
+    return StringPrintf("%s/de/%d", user_key_dir.c_str(), user_id);
+}
+
+static std::string get_ce_key_directory_path(userid_t user_id) {
+LOG(INFO) << "get_ce_key_directory_path " << user_id << ": " << StringPrintf("%s/ce/%d", user_key_dir.c_str(), user_id) << "\n";
+    return StringPrintf("%s/ce/%d", user_key_dir.c_str(), user_id);
+}
+
+// Returns the keys newest first
+static std::vector<std::string> get_ce_key_paths(const std::string& directory_path) {
+    auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(directory_path.c_str()), closedir);
+    if (!dirp) {
+        PLOG(ERROR) << "Unable to open ce key directory: " + directory_path;
+        return std::vector<std::string>();
+    }
+    std::vector<std::string> result;
+    for (;;) {
+        errno = 0;
+        auto const entry = readdir(dirp.get());
+        if (!entry) {
+            if (errno) {
+                PLOG(ERROR) << "Unable to read ce key directory: " + directory_path;
+                return std::vector<std::string>();
+            }
+            break;
+        }
+        if (entry->d_type != DT_DIR || entry->d_name[0] != 'c') {
+            LOG(DEBUG) << "Skipping non-key " << entry->d_name;
+            continue;
+        }
+        result.emplace_back(directory_path + "/" + entry->d_name);
+        LOG(INFO) << "get_ce_key_paths adding: " << directory_path + "/" + entry->d_name << "\n";
+    }
+    std::sort(result.begin(), result.end());
+    std::reverse(result.begin(), result.end());
+    return result;
+}
+
+static std::string get_ce_key_current_path(const std::string& directory_path) {
+LOG(INFO) << "get_ce_key_current_path: " << directory_path + "/current\n";
+    return directory_path + "/current";
+}
+
+// Discard all keys but the named one; rename it to canonical name.
+// No point in acting on errors in this; ignore them.
+static void fixate_user_ce_key(const std::string& directory_path, const std::string &to_fix,
+                               const std::vector<std::string>& paths) {
+    for (auto const other_path: paths) {
+        if (other_path != to_fix) {
+            android::vold::destroyKey(other_path);
+        }
+    }
+    auto const current_path = get_ce_key_current_path(directory_path);
+    if (to_fix != current_path) {
+        LOG(DEBUG) << "Renaming " << to_fix << " to " << current_path;
+        if (rename(to_fix.c_str(), current_path.c_str()) != 0) {
+            PLOG(WARNING) << "Unable to rename " << to_fix << " to " << current_path;
+        }
+    }
+}
+
+static bool read_and_fixate_user_ce_key(userid_t user_id,
+                                        const android::vold::KeyAuthentication& auth,
+                                        std::string *ce_key) {
+    auto const directory_path = get_ce_key_directory_path(user_id);
+    auto const paths = get_ce_key_paths(directory_path);
+    for (auto const ce_key_path: paths) {
+        LOG(DEBUG) << "Trying user CE key " << ce_key_path;
+        if (android::vold::retrieveKey(ce_key_path, auth, ce_key)) {
+            LOG(DEBUG) << "Successfully retrieved key";
+            fixate_user_ce_key(directory_path, ce_key_path, paths);
+            return true;
+        }
+    }
+    LOG(ERROR) << "Failed to find working ce key for user " << user_id;
+    return false;
+}
+
+static bool read_and_install_user_ce_key(userid_t user_id,
+                                         const android::vold::KeyAuthentication& auth) {
+    if (s_ce_key_raw_refs.count(user_id) != 0) return true;
+    std::string ce_key;
+    if (!read_and_fixate_user_ce_key(user_id, auth, &ce_key)) return false;
+    std::string ce_raw_ref;
+    if (!install_key(ce_key, &ce_raw_ref)) return false;
+    s_ce_keys[user_id] = ce_key;
+    s_ce_key_raw_refs[user_id] = ce_raw_ref;
+    LOG(DEBUG) << "Installed ce key for user " << user_id;
+    return true;
+}
+
+static bool prepare_dir(const std::string& dir, mode_t mode, uid_t uid, gid_t gid) {
+    LOG(DEBUG) << "Preparing: " << dir << "\n";
+    return true;
+    return access(dir.c_str(), F_OK) == 0; // we don't want recovery creating directories or changing permissions at this point, so we will just return true if the path already exists
+    if (fs_prepare_dir(dir.c_str(), mode, uid, gid) != 0) {
+        PLOG(ERROR) << "Failed to prepare " << dir;
+        return false;
+    }
+    return true;
+}
+
+static bool path_exists(const std::string& path) {
+    return access(path.c_str(), F_OK) == 0;
+}
+
+static bool lookup_key_ref(const std::map<userid_t, std::string>& key_map, userid_t user_id,
+                           std::string* raw_ref) {
+    auto refi = key_map.find(user_id);
+    if (refi == key_map.end()) {
+        LOG(ERROR) << "Cannot find key for " << user_id;
+        return false;
+    }
+    *raw_ref = refi->second;
+    return true;
+}
+
+static bool ensure_policy(const std::string& raw_ref, const std::string& path) {
+    LOG(INFO) << "ensure_policy '" << path << "'\n";
+    return true;
+    return access(path.c_str(), F_OK) == 0; // ensure policy will set a policy if one is not set on an empty folder - we don't want to do this in recovery
+    /*if (e4crypt_policy_ensure(path.c_str(), raw_ref.data(), raw_ref.size()) != 0) {
+        LOG(ERROR) << "Failed to set policy on: " << path << "\n";
+        return false;
+    }
+    return true;*/
+}
+
+static bool is_numeric(const char* name) {
+    for (const char* p = name; *p != '\0'; p++) {
+        if (!isdigit(*p)) return false;
+    }
+    return true;
+}
+
+static bool load_all_de_keys() {
+    auto de_dir = user_key_dir + "/de";
+    auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(de_dir.c_str()), closedir);
+    if (!dirp) {
+        PLOG(ERROR) << "Unable to read de key directory";
+        return false;
+    }
+    for (;;) {
+        errno = 0;
+        auto entry = readdir(dirp.get());
+        if (!entry) {
+            if (errno) {
+                PLOG(ERROR) << "Unable to read de key directory";
+                return false;
+            }
+            break;
+        }
+        if (entry->d_type != DT_DIR || !is_numeric(entry->d_name)) {
+            LOG(DEBUG) << "Skipping non-de-key " << entry->d_name;
+            continue;
+        }
+        userid_t user_id = atoi(entry->d_name);
+        if (s_de_key_raw_refs.count(user_id) == 0) {
+            auto key_path = de_dir + "/" + entry->d_name;
+            std::string key;
+            if (!android::vold::retrieveKey(key_path, kEmptyAuthentication, &key)) return false;
+            std::string raw_ref;
+            if (!install_key(key, &raw_ref)) return false;
+            s_de_key_raw_refs[user_id] = raw_ref;
+            LOG(DEBUG) << "Installed de key for user " << user_id;
+        }
+    }
+    // ext4enc:TODO: go through all DE directories, ensure that all user dirs have the
+    // correct policy set on them, and that no rogue ones exist.
+    return true;
+}
+
+bool e4crypt_initialize_global_de() {
+
+    if (s_global_de_initialized) {
+        LOG(INFO) << "Already initialized\n";
+        return true;
+    }
+
+    std::string device_key;
+    if (path_exists(device_key_path)) {
+        if (!android::vold::retrieveKey(device_key_path,
+                kEmptyAuthentication, &device_key)) return false;
+    } else {
+        LOG(INFO) << "NOT Creating new key\n";
+        return false;
+    }
+
+    std::string device_key_ref;
+    if (!install_key(device_key, &device_key_ref)) {
+        LOG(ERROR) << "Failed to install device key\n";
+        return false;
+    }
+
+    s_global_de_initialized = true;
+    return true;
+}
+
+bool e4crypt_init_user0() {
+    if (e4crypt_is_native()) {
+        if (!prepare_dir(user_key_dir, 0700, AID_ROOT, AID_ROOT)) return false;
+        if (!prepare_dir(user_key_dir + "/ce", 0700, AID_ROOT, AID_ROOT)) return false;
+        if (!prepare_dir(user_key_dir + "/de", 0700, AID_ROOT, AID_ROOT)) return false;
+        if (!path_exists(get_de_key_path(0))) {
+            //if (!create_and_install_user_keys(0, false)) return false;
+            printf("de key path not found\n");
+            return false;
+        }
+        // TODO: switch to loading only DE_0 here once framework makes
+        // explicit calls to install DE keys for secondary users
+        if (!load_all_de_keys()) return false;
+    }
+    // We can only safely prepare DE storage here, since CE keys are probably
+    // entangled with user credentials.  The framework will always prepare CE
+    // storage once CE keys are installed.
+    if (!e4crypt_prepare_user_storage(nullptr, 0, 0, FLAG_STORAGE_DE)) {
+        LOG(ERROR) << "Failed to prepare user 0 storage";
+        return false;
+    }
+
+    // If this is a non-FBE device that recently left an emulated mode,
+    // restore user data directories to known-good state.
+    if (!e4crypt_is_native() && !e4crypt_is_emulated()) {
+        e4crypt_unlock_user_key(0, 0, "!", "!");
+    }
+
+    return true;
+}
+
+static bool parse_hex(const char* hex, std::string* result) {
+    if (strcmp("!", hex) == 0) {
+        *result = "";
+        return true;
+    }
+    if (android::vold::HexToStr(hex, *result) != 0) {
+        LOG(ERROR) << "Invalid FBE hex string";  // Don't log the string for security reasons
+        return false;
+    }
+    return true;
+}
+
+// TODO: rename to 'install' for consistency, and take flags to know which keys to install
+bool e4crypt_unlock_user_key(userid_t user_id, int serial, const char* token_hex,
+                             const char* secret_hex) {
+    if (e4crypt_is_native()) {
+        if (s_ce_key_raw_refs.count(user_id) != 0) {
+            LOG(WARNING) << "Tried to unlock already-unlocked key for user " << user_id;
+            return true;
+        }
+        std::string token, secret;
+        if (!parse_hex(token_hex, &token)) return false;
+        if (!parse_hex(secret_hex, &secret)) return false;
+        android::vold::KeyAuthentication auth(token, secret);
+        if (!read_and_install_user_ce_key(user_id, auth)) {
+            LOG(ERROR) << "Couldn't read key for " << user_id;
+            return false;
+        }
+    } else {
+		printf("Emulation mode not supported in TWRP\n");
+        // When in emulation mode, we just use chmod. However, we also
+        // unlock directories when not in emulation mode, to bring devices
+        // back into a known-good state.
+        /*if (!emulated_unlock(android::vold::BuildDataSystemCePath(user_id), 0771) ||
+            !emulated_unlock(android::vold::BuildDataMiscCePath(user_id), 01771) ||
+            !emulated_unlock(android::vold::BuildDataMediaCePath(nullptr, user_id), 0770) ||
+            !emulated_unlock(android::vold::BuildDataUserCePath(nullptr, user_id), 0771)) {
+            LOG(ERROR) << "Failed to unlock user " << user_id;
+            return false;
+        }*/
+    }
+    return true;
+}
+
+bool e4crypt_prepare_user_storage(const char* volume_uuid, userid_t user_id, int serial,
+        int flags) {
+
+    if (flags & FLAG_STORAGE_DE) {
+        // DE_sys key
+        auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);
+        auto misc_legacy_path = android::vold::BuildDataMiscLegacyPath(user_id);
+        auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
+        auto foreign_de_path = android::vold::BuildDataProfilesForeignDexDePath(user_id);
+
+        // DE_n key
+        auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
+        auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
+        auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
+
+        if (!prepare_dir(system_legacy_path, 0700, AID_SYSTEM, AID_SYSTEM)) return false;
+#if MANAGE_MISC_DIRS
+        if (!prepare_dir(misc_legacy_path, 0750, multiuser_get_uid(user_id, AID_SYSTEM),
+                multiuser_get_uid(user_id, AID_EVERYBODY))) return false;
+#endif
+        if (!prepare_dir(profiles_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
+        if (!prepare_dir(foreign_de_path, 0773, AID_SYSTEM, AID_SYSTEM)) return false;
+
+        if (!prepare_dir(system_de_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
+        if (!prepare_dir(misc_de_path, 01771, AID_SYSTEM, AID_MISC)) return false;
+        if (!prepare_dir(user_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
+
+        // For now, FBE is only supported on internal storage
+        if (e4crypt_is_native() && volume_uuid == nullptr) {
+            std::string de_raw_ref;
+            if (!lookup_key_ref(s_de_key_raw_refs, user_id, &de_raw_ref)) return false;
+            if (!ensure_policy(de_raw_ref, system_de_path)) return false;
+            if (!ensure_policy(de_raw_ref, misc_de_path)) return false;
+            if (!ensure_policy(de_raw_ref, user_de_path)) return false;
+        }
+    }
+
+    if (flags & FLAG_STORAGE_CE) {
+        // CE_n key
+        auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
+        auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
+        auto media_ce_path = android::vold::BuildDataMediaCePath(volume_uuid, user_id);
+        auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
+
+        if (!prepare_dir(system_ce_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
+        if (!prepare_dir(misc_ce_path, 01771, AID_SYSTEM, AID_MISC)) return false;
+        if (!prepare_dir(media_ce_path, 0770, AID_MEDIA_RW, AID_MEDIA_RW)) return false;
+        if (!prepare_dir(user_ce_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
+
+        // For now, FBE is only supported on internal storage
+        if (e4crypt_is_native() && volume_uuid == nullptr) {
+            std::string ce_raw_ref;
+            if (!lookup_key_ref(s_ce_key_raw_refs, user_id, &ce_raw_ref)) return false;
+            if (!ensure_policy(ce_raw_ref, system_ce_path)) return false;
+            if (!ensure_policy(ce_raw_ref, misc_ce_path)) return false;
+            if (!ensure_policy(ce_raw_ref, media_ce_path)) return false;
+            if (!ensure_policy(ce_raw_ref, user_ce_path)) return false;
+        }
+    }
+
+    return true;
+}