Ext4Crypt.cpp revision ab0b56aef33f04f4d7a352d5790b2d9cd9e7d6d3 
1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "Ext4Crypt.h"
18
19#include "KeyStorage.h"
20#include "Utils.h"
21
22#include <algorithm>
23#include <iomanip>
24#include <map>
25#include <set>
26#include <sstream>
27#include <string>
28
29#include <dirent.h>
30#include <errno.h>
31#include <fcntl.h>
32#include <limits.h>
33#include <openssl/sha.h>
34#include <selinux/android.h>
35#include <stdio.h>
36#include <sys/mount.h>
37#include <sys/stat.h>
38#include <sys/types.h>
39
40#include <private/android_filesystem_config.h>
41
42#include "cryptfs.h"
43#include "ext4_crypt.h"
44#include "key_control.h"
45
46#define EMULATED_USES_SELINUX 0
47#define MANAGE_MISC_DIRS 0
48
49#include <cutils/fs.h>
50
51#include <android-base/file.h>
52#include <android-base/logging.h>
53#include <android-base/stringprintf.h>
54
55using android::base::StringPrintf;
56using android::vold::kEmptyAuthentication;
57
58// NOTE: keep in sync with StorageManager
59static constexpr int FLAG_STORAGE_DE = 1 << 0;
60static constexpr int FLAG_STORAGE_CE = 1 << 1;
61
62namespace {
63const std::string device_key_dir = std::string() + DATA_MNT_POINT + e4crypt_unencrypted_folder;
64const std::string device_key_path = device_key_dir + "/key";
65const std::string device_key_temp = device_key_dir + "/temp";
66
67const std::string user_key_dir = std::string() + DATA_MNT_POINT + "/misc/vold/user_keys";
68const std::string user_key_temp = user_key_dir + "/temp";
69
70bool s_global_de_initialized = false;
71
72// Some users are ephemeral, don't try to wipe their keys from disk
73std::set<userid_t> s_ephemeral_users;
74
75// Map user ids to key references
76std::map<userid_t, std::string> s_de_key_raw_refs;
77std::map<userid_t, std::string> s_ce_key_raw_refs;
78// TODO abolish this map. Keys should not be long-lived in user memory, only kernel memory.
79// See b/26948053
80std::map<userid_t, std::string> s_ce_keys;
81
82// ext4enc:TODO get this const from somewhere good
83const int EXT4_KEY_DESCRIPTOR_SIZE = 8;
84
85// ext4enc:TODO Include structure from somewhere sensible
86// MUST be in sync with ext4_crypto.c in kernel
87constexpr int EXT4_ENCRYPTION_MODE_AES_256_XTS = 1;
88constexpr int EXT4_AES_256_XTS_KEY_SIZE = 64;
89constexpr int EXT4_MAX_KEY_SIZE = 64;
90struct ext4_encryption_key {
91    uint32_t mode;
92    char raw[EXT4_MAX_KEY_SIZE];
93    uint32_t size;
94};
95}
96
97static bool e4crypt_is_emulated() {
98    return property_get_bool("persist.sys.emulate_fbe", false);
99}
100
101static const char* escape_null(const char* value) {
102    return (value == nullptr) ? "null" : value;
103}
104
105// Get raw keyref - used to make keyname and to pass to ioctl
106static std::string generate_key_ref(const char* key, int length) {
107    SHA512_CTX c;
108
109    SHA512_Init(&c);
110    SHA512_Update(&c, key, length);
111    unsigned char key_ref1[SHA512_DIGEST_LENGTH];
112    SHA512_Final(key_ref1, &c);
113
114    SHA512_Init(&c);
115    SHA512_Update(&c, key_ref1, SHA512_DIGEST_LENGTH);
116    unsigned char key_ref2[SHA512_DIGEST_LENGTH];
117    SHA512_Final(key_ref2, &c);
118
119    static_assert(EXT4_KEY_DESCRIPTOR_SIZE <= SHA512_DIGEST_LENGTH,
120                  "Hash too short for descriptor");
121    return std::string((char*)key_ref2, EXT4_KEY_DESCRIPTOR_SIZE);
122}
123
124static bool fill_key(const std::string& key, ext4_encryption_key* ext4_key) {
125    if (key.size() != EXT4_AES_256_XTS_KEY_SIZE) {
126        LOG(ERROR) << "Wrong size key " << key.size();
127        return false;
128    }
129    static_assert(EXT4_AES_256_XTS_KEY_SIZE <= sizeof(ext4_key->raw), "Key too long!");
130    ext4_key->mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
131    ext4_key->size = key.size();
132    memset(ext4_key->raw, 0, sizeof(ext4_key->raw));
133    memcpy(ext4_key->raw, key.data(), key.size());
134    return true;
135}
136
137static std::string keyname(const std::string& raw_ref) {
138    std::ostringstream o;
139    o << "ext4:";
140    for (auto i : raw_ref) {
141        o << std::hex << std::setw(2) << std::setfill('0') << (int)i;
142    }
143    return o.str();
144}
145
146// Get the keyring we store all keys in
147static bool e4crypt_keyring(key_serial_t* device_keyring) {
148    *device_keyring = keyctl_search(KEY_SPEC_SESSION_KEYRING, "keyring", "e4crypt", 0);
149    if (*device_keyring == -1) {
150        PLOG(ERROR) << "Unable to find device keyring";
151        return false;
152    }
153    return true;
154}
155
156// Install password into global keyring
157// Return raw key reference for use in policy
158static bool install_key(const std::string& key, std::string* raw_ref) {
159    ext4_encryption_key ext4_key;
160    if (!fill_key(key, &ext4_key)) return false;
161    *raw_ref = generate_key_ref(ext4_key.raw, ext4_key.size);
162    auto ref = keyname(*raw_ref);
163    key_serial_t device_keyring;
164    if (!e4crypt_keyring(&device_keyring)) return false;
165    key_serial_t key_id =
166        add_key("logon", ref.c_str(), (void*)&ext4_key, sizeof(ext4_key), device_keyring);
167    if (key_id == -1) {
168        PLOG(ERROR) << "Failed to insert key into keyring " << device_keyring;
169        return false;
170    }
171    LOG(DEBUG) << "Added key " << key_id << " (" << ref << ") to keyring " << device_keyring
172               << " in process " << getpid();
173
174    return true;
175}
176
177static std::string get_de_key_path(userid_t user_id) {
178    return StringPrintf("%s/de/%d", user_key_dir.c_str(), user_id);
179}
180
181static std::string get_ce_key_directory_path(userid_t user_id) {
182    return StringPrintf("%s/ce/%d", user_key_dir.c_str(), user_id);
183}
184
185// Returns the keys newest first
186static std::vector<std::string> get_ce_key_paths(const std::string& directory_path) {
187    auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(directory_path.c_str()), closedir);
188    if (!dirp) {
189        PLOG(ERROR) << "Unable to open ce key directory: " + directory_path;
190        return std::vector<std::string>();
191    }
192    std::vector<std::string> result;
193    for (;;) {
194        errno = 0;
195        auto const entry = readdir(dirp.get());
196        if (!entry) {
197            if (errno) {
198                PLOG(ERROR) << "Unable to read ce key directory: " + directory_path;
199                return std::vector<std::string>();
200            }
201            break;
202        }
203        if (entry->d_type != DT_DIR || entry->d_name[0] != 'c') {
204            LOG(DEBUG) << "Skipping non-key " << entry->d_name;
205            continue;
206        }
207        result.emplace_back(directory_path + "/" + entry->d_name);
208    }
209    std::sort(result.begin(), result.end());
210    std::reverse(result.begin(), result.end());
211    return result;
212}
213
214static std::string get_ce_key_current_path(const std::string& directory_path) {
215    return directory_path + "/current";
216}
217
218static bool get_ce_key_new_path(const std::string& directory_path,
219                                const std::vector<std::string>& paths,
220                                std::string *ce_key_path) {
221    if (paths.empty()) {
222        *ce_key_path = get_ce_key_current_path(directory_path);
223        return true;
224    }
225    for (unsigned int i = 0; i < UINT_MAX; i++) {
226        auto const candidate = StringPrintf("%s/cx%010u", directory_path.c_str(), i);
227        if (paths[0] < candidate) {
228            *ce_key_path = candidate;
229            return true;
230        }
231    }
232    return false;
233}
234
235// Discard all keys but the named one; rename it to canonical name.
236// No point in acting on errors in this; ignore them.
237static void fixate_user_ce_key(const std::string& directory_path, const std::string &to_fix,
238                               const std::vector<std::string>& paths) {
239    for (auto const other_path: paths) {
240        if (other_path != to_fix) {
241            android::vold::destroyKey(other_path);
242        }
243    }
244    auto const current_path = get_ce_key_current_path(directory_path);
245    if (to_fix != current_path) {
246        LOG(DEBUG) << "Renaming " << to_fix << " to " << current_path;
247        if (rename(to_fix.c_str(), current_path.c_str()) != 0) {
248            PLOG(WARNING) << "Unable to rename " << to_fix << " to " << current_path;
249        }
250    }
251}
252
253static bool read_and_fixate_user_ce_key(userid_t user_id,
254                                        const android::vold::KeyAuthentication& auth,
255                                        std::string *ce_key) {
256    auto const directory_path = get_ce_key_directory_path(user_id);
257    auto const paths = get_ce_key_paths(directory_path);
258    for (auto const ce_key_path: paths) {
259        LOG(DEBUG) << "Trying user CE key " << ce_key_path;
260        if (android::vold::retrieveKey(ce_key_path, auth, ce_key)) {
261            LOG(DEBUG) << "Successfully retrieved key";
262            fixate_user_ce_key(directory_path, ce_key_path, paths);
263            return true;
264        }
265    }
266    LOG(ERROR) << "Failed to find working ce key for user " << user_id;
267    return false;
268}
269
270static bool read_and_install_user_ce_key(userid_t user_id,
271                                         const android::vold::KeyAuthentication& auth) {
272    if (s_ce_key_raw_refs.count(user_id) != 0) return true;
273    std::string ce_key;
274    if (!read_and_fixate_user_ce_key(user_id, auth, &ce_key)) return false;
275    std::string ce_raw_ref;
276    if (!install_key(ce_key, &ce_raw_ref)) return false;
277    s_ce_keys[user_id] = ce_key;
278    s_ce_key_raw_refs[user_id] = ce_raw_ref;
279    LOG(DEBUG) << "Installed ce key for user " << user_id;
280    return true;
281}
282
283static bool prepare_dir(const std::string& dir, mode_t mode, uid_t uid, gid_t gid) {
284    LOG(DEBUG) << "Preparing: " << dir;
285    if (fs_prepare_dir(dir.c_str(), mode, uid, gid) != 0) {
286        PLOG(ERROR) << "Failed to prepare " << dir;
287        return false;
288    }
289    return true;
290}
291
292static bool destroy_dir(const std::string& dir) {
293    LOG(DEBUG) << "Destroying: " << dir;
294    if (rmdir(dir.c_str()) != 0 && errno != ENOENT) {
295        PLOG(ERROR) << "Failed to destroy " << dir;
296        return false;
297    }
298    return true;
299}
300
301static bool random_key(std::string* key) {
302    if (android::vold::ReadRandomBytes(EXT4_AES_256_XTS_KEY_SIZE, *key) != 0) {
303        // TODO status_t plays badly with PLOG, fix it.
304        LOG(ERROR) << "Random read failed";
305        return false;
306    }
307    return true;
308}
309
310static bool path_exists(const std::string& path) {
311    return access(path.c_str(), F_OK) == 0;
312}
313
314// NB this assumes that there is only one thread listening for crypt commands, because
315// it creates keys in a fixed location.
316static bool store_key(const std::string& key_path, const std::string& tmp_path,
317                      const android::vold::KeyAuthentication& auth, const std::string& key) {
318    if (path_exists(key_path)) {
319        LOG(ERROR) << "Already exists, cannot create key at: " << key_path;
320        return false;
321    }
322    if (path_exists(tmp_path)) {
323        android::vold::destroyKey(tmp_path);  // May be partially created so ignore errors
324    }
325    if (!android::vold::storeKey(tmp_path, auth, key)) return false;
326    if (rename(tmp_path.c_str(), key_path.c_str()) != 0) {
327        PLOG(ERROR) << "Unable to move new key to location: " << key_path;
328        return false;
329    }
330    LOG(DEBUG) << "Created key " << key_path;
331    return true;
332}
333
334static bool create_and_install_user_keys(userid_t user_id, bool create_ephemeral) {
335    std::string de_key, ce_key;
336    if (!random_key(&de_key)) return false;
337    if (!random_key(&ce_key)) return false;
338    if (create_ephemeral) {
339        // If the key should be created as ephemeral, don't store it.
340        s_ephemeral_users.insert(user_id);
341    } else {
342        auto const directory_path = get_ce_key_directory_path(user_id);
343        if (!prepare_dir(directory_path, 0700, AID_ROOT, AID_ROOT)) return false;
344        auto const paths = get_ce_key_paths(directory_path);
345        std::string ce_key_path;
346        if (!get_ce_key_new_path(directory_path, paths, &ce_key_path)) return false;
347        if (!store_key(ce_key_path, user_key_temp,
348                kEmptyAuthentication, ce_key)) return false;
349        fixate_user_ce_key(directory_path, ce_key_path, paths);
350        // Write DE key second; once this is written, all is good.
351        if (!store_key(get_de_key_path(user_id), user_key_temp,
352                kEmptyAuthentication, de_key)) return false;
353    }
354    std::string de_raw_ref;
355    if (!install_key(de_key, &de_raw_ref)) return false;
356    s_de_key_raw_refs[user_id] = de_raw_ref;
357    std::string ce_raw_ref;
358    if (!install_key(ce_key, &ce_raw_ref)) return false;
359    s_ce_keys[user_id] = ce_key;
360    s_ce_key_raw_refs[user_id] = ce_raw_ref;
361    LOG(DEBUG) << "Created keys for user " << user_id;
362    return true;
363}
364
365static bool lookup_key_ref(const std::map<userid_t, std::string>& key_map, userid_t user_id,
366                           std::string* raw_ref) {
367    auto refi = key_map.find(user_id);
368    if (refi == key_map.end()) {
369        LOG(ERROR) << "Cannot find key for " << user_id;
370        return false;
371    }
372    *raw_ref = refi->second;
373    return true;
374}
375
376static bool ensure_policy(const std::string& raw_ref, const std::string& path) {
377    if (e4crypt_policy_ensure(path.c_str(),
378                              raw_ref.data(), raw_ref.size(),
379                              cryptfs_get_file_encryption_mode()) != 0) {
380        LOG(ERROR) << "Failed to set policy on: " << path;
381        return false;
382    }
383    return true;
384}
385
386static bool is_numeric(const char* name) {
387    for (const char* p = name; *p != '\0'; p++) {
388        if (!isdigit(*p)) return false;
389    }
390    return true;
391}
392
393static bool load_all_de_keys() {
394    auto de_dir = user_key_dir + "/de";
395    auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(de_dir.c_str()), closedir);
396    if (!dirp) {
397        PLOG(ERROR) << "Unable to read de key directory";
398        return false;
399    }
400    for (;;) {
401        errno = 0;
402        auto entry = readdir(dirp.get());
403        if (!entry) {
404            if (errno) {
405                PLOG(ERROR) << "Unable to read de key directory";
406                return false;
407            }
408            break;
409        }
410        if (entry->d_type != DT_DIR || !is_numeric(entry->d_name)) {
411            LOG(DEBUG) << "Skipping non-de-key " << entry->d_name;
412            continue;
413        }
414        userid_t user_id = atoi(entry->d_name);
415        if (s_de_key_raw_refs.count(user_id) == 0) {
416            auto key_path = de_dir + "/" + entry->d_name;
417            std::string key;
418            if (!android::vold::retrieveKey(key_path, kEmptyAuthentication, &key)) return false;
419            std::string raw_ref;
420            if (!install_key(key, &raw_ref)) return false;
421            s_de_key_raw_refs[user_id] = raw_ref;
422            LOG(DEBUG) << "Installed de key for user " << user_id;
423        }
424    }
425    // ext4enc:TODO: go through all DE directories, ensure that all user dirs have the
426    // correct policy set on them, and that no rogue ones exist.
427    return true;
428}
429
430bool e4crypt_initialize_global_de() {
431    LOG(INFO) << "e4crypt_initialize_global_de";
432
433    if (s_global_de_initialized) {
434        LOG(INFO) << "Already initialized";
435        return true;
436    }
437
438    std::string mode_filename = std::string("/data") + e4crypt_key_mode;
439    std::string mode = cryptfs_get_file_encryption_mode();
440    if (!android::base::WriteStringToFile(mode, mode_filename)) {
441        PLOG(ERROR) << "Cannot save type";
442        return false;
443    }
444
445    std::string device_key;
446    if (path_exists(device_key_path)) {
447        if (!android::vold::retrieveKey(device_key_path,
448                kEmptyAuthentication, &device_key)) return false;
449    } else {
450        LOG(INFO) << "Creating new key";
451        if (!random_key(&device_key)) return false;
452        if (!store_key(device_key_path, device_key_temp,
453                kEmptyAuthentication, device_key)) return false;
454    }
455
456    std::string device_key_ref;
457    if (!install_key(device_key, &device_key_ref)) {
458        LOG(ERROR) << "Failed to install device key";
459        return false;
460    }
461
462    std::string ref_filename = std::string("/data") + e4crypt_key_ref;
463    if (!android::base::WriteStringToFile(device_key_ref, ref_filename)) {
464        PLOG(ERROR) << "Cannot save key reference";
465        return false;
466    }
467
468    s_global_de_initialized = true;
469    return true;
470}
471
472bool e4crypt_init_user0() {
473    LOG(DEBUG) << "e4crypt_init_user0";
474    if (e4crypt_is_native()) {
475        if (!prepare_dir(user_key_dir, 0700, AID_ROOT, AID_ROOT)) return false;
476        if (!prepare_dir(user_key_dir + "/ce", 0700, AID_ROOT, AID_ROOT)) return false;
477        if (!prepare_dir(user_key_dir + "/de", 0700, AID_ROOT, AID_ROOT)) return false;
478        if (!path_exists(get_de_key_path(0))) {
479            if (!create_and_install_user_keys(0, false)) return false;
480        }
481        // TODO: switch to loading only DE_0 here once framework makes
482        // explicit calls to install DE keys for secondary users
483        if (!load_all_de_keys()) return false;
484    }
485    // We can only safely prepare DE storage here, since CE keys are probably
486    // entangled with user credentials.  The framework will always prepare CE
487    // storage once CE keys are installed.
488    if (!e4crypt_prepare_user_storage(nullptr, 0, 0, FLAG_STORAGE_DE)) {
489        LOG(ERROR) << "Failed to prepare user 0 storage";
490        return false;
491    }
492
493    // If this is a non-FBE device that recently left an emulated mode,
494    // restore user data directories to known-good state.
495    if (!e4crypt_is_native() && !e4crypt_is_emulated()) {
496        e4crypt_unlock_user_key(0, 0, "!", "!");
497    }
498
499    return true;
500}
501
502bool e4crypt_vold_create_user_key(userid_t user_id, int serial, bool ephemeral) {
503    LOG(DEBUG) << "e4crypt_vold_create_user_key for " << user_id << " serial " << serial;
504    if (!e4crypt_is_native()) {
505        return true;
506    }
507    // FIXME test for existence of key that is not loaded yet
508    if (s_ce_key_raw_refs.count(user_id) != 0) {
509        LOG(ERROR) << "Already exists, can't e4crypt_vold_create_user_key for " << user_id
510                   << " serial " << serial;
511        // FIXME should we fail the command?
512        return true;
513    }
514    if (!create_and_install_user_keys(user_id, ephemeral)) {
515        return false;
516    }
517    return true;
518}
519
520bool e4crypt_destroy_user_key(userid_t user_id) {
521    LOG(DEBUG) << "e4crypt_destroy_user_key(" << user_id << ")";
522    if (!e4crypt_is_native()) {
523        return true;
524    }
525    bool success = true;
526    s_ce_keys.erase(user_id);
527    std::string raw_ref;
528    s_ce_key_raw_refs.erase(user_id);
529    s_de_key_raw_refs.erase(user_id);
530    auto it = s_ephemeral_users.find(user_id);
531    if (it != s_ephemeral_users.end()) {
532        s_ephemeral_users.erase(it);
533    } else {
534        for (auto const path: get_ce_key_paths(get_ce_key_directory_path(user_id))) {
535            success &= android::vold::destroyKey(path);
536        }
537        auto de_key_path = get_de_key_path(user_id);
538        if (path_exists(de_key_path)) {
539            success &= android::vold::destroyKey(de_key_path);
540        } else {
541            LOG(INFO) << "Not present so not erasing: " << de_key_path;
542        }
543    }
544    return success;
545}
546
547static bool emulated_lock(const std::string& path) {
548    if (chmod(path.c_str(), 0000) != 0) {
549        PLOG(ERROR) << "Failed to chmod " << path;
550        return false;
551    }
552#if EMULATED_USES_SELINUX
553    if (setfilecon(path.c_str(), "u:object_r:storage_stub_file:s0") != 0) {
554        PLOG(WARNING) << "Failed to setfilecon " << path;
555        return false;
556    }
557#endif
558    return true;
559}
560
561static bool emulated_unlock(const std::string& path, mode_t mode) {
562    if (chmod(path.c_str(), mode) != 0) {
563        PLOG(ERROR) << "Failed to chmod " << path;
564        // FIXME temporary workaround for b/26713622
565        if (e4crypt_is_emulated()) return false;
566    }
567#if EMULATED_USES_SELINUX
568    if (selinux_android_restorecon(path.c_str(), SELINUX_ANDROID_RESTORECON_FORCE) != 0) {
569        PLOG(WARNING) << "Failed to restorecon " << path;
570        // FIXME temporary workaround for b/26713622
571        if (e4crypt_is_emulated()) return false;
572    }
573#endif
574    return true;
575}
576
577static bool parse_hex(const char* hex, std::string* result) {
578    if (strcmp("!", hex) == 0) {
579        *result = "";
580        return true;
581    }
582    if (android::vold::HexToStr(hex, *result) != 0) {
583        LOG(ERROR) << "Invalid FBE hex string";  // Don't log the string for security reasons
584        return false;
585    }
586    return true;
587}
588
589bool e4crypt_add_user_key_auth(userid_t user_id, int serial, const char* token_hex,
590                          const char* secret_hex) {
591    LOG(DEBUG) << "e4crypt_add_user_key_auth " << user_id << " serial=" << serial
592               << " token_present=" << (strcmp(token_hex, "!") != 0);
593    if (!e4crypt_is_native()) return true;
594    if (s_ephemeral_users.count(user_id) != 0) return true;
595    std::string token, secret;
596    if (!parse_hex(token_hex, &token)) return false;
597    if (!parse_hex(secret_hex, &secret)) return false;
598    auto auth = secret.empty() ? kEmptyAuthentication
599                                   : android::vold::KeyAuthentication(token, secret);
600    auto it = s_ce_keys.find(user_id);
601    if (it == s_ce_keys.end()) {
602        LOG(ERROR) << "Key not loaded into memory, can't change for user " << user_id;
603        return false;
604    }
605    auto ce_key = it->second;
606    auto const directory_path = get_ce_key_directory_path(user_id);
607    auto const paths = get_ce_key_paths(directory_path);
608    std::string ce_key_path;
609    if (!get_ce_key_new_path(directory_path, paths, &ce_key_path)) return false;
610    if (!store_key(ce_key_path, user_key_temp, auth, ce_key)) return false;
611    return true;
612}
613
614bool e4crypt_fixate_newest_user_key_auth(userid_t user_id) {
615    LOG(DEBUG) << "e4crypt_fixate_newest_user_key_auth " << user_id;
616    if (!e4crypt_is_native()) return true;
617    auto const directory_path = get_ce_key_directory_path(user_id);
618    auto const paths = get_ce_key_paths(directory_path);
619    if (paths.empty()) {
620        LOG(ERROR) << "No ce keys present, cannot fixate for user " << user_id;
621        return false;
622    }
623    fixate_user_ce_key(directory_path, paths[0], paths);
624    return true;
625}
626
627// TODO: rename to 'install' for consistency, and take flags to know which keys to install
628bool e4crypt_unlock_user_key(userid_t user_id, int serial, const char* token_hex,
629                             const char* secret_hex) {
630    LOG(DEBUG) << "e4crypt_unlock_user_key " << user_id << " serial=" << serial
631               << " token_present=" << (strcmp(token_hex, "!") != 0);
632    if (e4crypt_is_native()) {
633        if (s_ce_key_raw_refs.count(user_id) != 0) {
634            LOG(WARNING) << "Tried to unlock already-unlocked key for user " << user_id;
635            return true;
636        }
637        std::string token, secret;
638        if (!parse_hex(token_hex, &token)) return false;
639        if (!parse_hex(secret_hex, &secret)) return false;
640        android::vold::KeyAuthentication auth(token, secret);
641        if (!read_and_install_user_ce_key(user_id, auth)) {
642            LOG(ERROR) << "Couldn't read key for " << user_id;
643            return false;
644        }
645    } else {
646        // When in emulation mode, we just use chmod. However, we also
647        // unlock directories when not in emulation mode, to bring devices
648        // back into a known-good state.
649        if (!emulated_unlock(android::vold::BuildDataSystemCePath(user_id), 0771) ||
650            !emulated_unlock(android::vold::BuildDataMiscCePath(user_id), 01771) ||
651            !emulated_unlock(android::vold::BuildDataMediaCePath(nullptr, user_id), 0770) ||
652            !emulated_unlock(android::vold::BuildDataUserCePath(nullptr, user_id), 0771)) {
653            LOG(ERROR) << "Failed to unlock user " << user_id;
654            return false;
655        }
656    }
657    return true;
658}
659
660// TODO: rename to 'evict' for consistency
661bool e4crypt_lock_user_key(userid_t user_id) {
662    if (e4crypt_is_native()) {
663        // TODO: remove from kernel keyring
664    } else if (e4crypt_is_emulated()) {
665        // When in emulation mode, we just use chmod
666        if (!emulated_lock(android::vold::BuildDataSystemCePath(user_id)) ||
667            !emulated_lock(android::vold::BuildDataMiscCePath(user_id)) ||
668            !emulated_lock(android::vold::BuildDataMediaCePath(nullptr, user_id)) ||
669            !emulated_lock(android::vold::BuildDataUserCePath(nullptr, user_id))) {
670            LOG(ERROR) << "Failed to lock user " << user_id;
671            return false;
672        }
673    }
674
675    return true;
676}
677
678bool e4crypt_prepare_user_storage(const char* volume_uuid, userid_t user_id, int serial,
679        int flags) {
680    LOG(DEBUG) << "e4crypt_prepare_user_storage for volume " << escape_null(volume_uuid)
681               << ", user " << user_id << ", serial " << serial << ", flags " << flags;
682
683    if (flags & FLAG_STORAGE_DE) {
684        // DE_sys key
685        auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);
686        auto misc_legacy_path = android::vold::BuildDataMiscLegacyPath(user_id);
687        auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
688        auto foreign_de_path = android::vold::BuildDataProfilesForeignDexDePath(user_id);
689
690        // DE_n key
691        auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
692        auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
693        auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
694
695        if (!prepare_dir(system_legacy_path, 0700, AID_SYSTEM, AID_SYSTEM)) return false;
696#if MANAGE_MISC_DIRS
697        if (!prepare_dir(misc_legacy_path, 0750, multiuser_get_uid(user_id, AID_SYSTEM),
698                multiuser_get_uid(user_id, AID_EVERYBODY))) return false;
699#endif
700        if (!prepare_dir(profiles_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
701        if (!prepare_dir(foreign_de_path, 0773, AID_SYSTEM, AID_SYSTEM)) return false;
702
703        if (!prepare_dir(system_de_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
704        if (!prepare_dir(misc_de_path, 01771, AID_SYSTEM, AID_MISC)) return false;
705        if (!prepare_dir(user_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
706
707        // For now, FBE is only supported on internal storage
708        if (e4crypt_is_native() && volume_uuid == nullptr) {
709            std::string de_raw_ref;
710            if (!lookup_key_ref(s_de_key_raw_refs, user_id, &de_raw_ref)) return false;
711            if (!ensure_policy(de_raw_ref, system_de_path)) return false;
712            if (!ensure_policy(de_raw_ref, misc_de_path)) return false;
713            if (!ensure_policy(de_raw_ref, user_de_path)) return false;
714        }
715    }
716
717    if (flags & FLAG_STORAGE_CE) {
718        // CE_n key
719        auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
720        auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
721        auto media_ce_path = android::vold::BuildDataMediaCePath(volume_uuid, user_id);
722        auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
723
724        if (!prepare_dir(system_ce_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
725        if (!prepare_dir(misc_ce_path, 01771, AID_SYSTEM, AID_MISC)) return false;
726        if (!prepare_dir(media_ce_path, 0770, AID_MEDIA_RW, AID_MEDIA_RW)) return false;
727        if (!prepare_dir(user_ce_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
728
729        // For now, FBE is only supported on internal storage
730        if (e4crypt_is_native() && volume_uuid == nullptr) {
731            std::string ce_raw_ref;
732            if (!lookup_key_ref(s_ce_key_raw_refs, user_id, &ce_raw_ref)) return false;
733            if (!ensure_policy(ce_raw_ref, system_ce_path)) return false;
734            if (!ensure_policy(ce_raw_ref, misc_ce_path)) return false;
735            if (!ensure_policy(ce_raw_ref, media_ce_path)) return false;
736            if (!ensure_policy(ce_raw_ref, user_ce_path)) return false;
737
738            // Now that credentials have been installed, we can run restorecon
739            // over these paths
740            // NOTE: these paths need to be kept in sync with libselinux
741            android::vold::RestoreconRecursive(system_ce_path);
742            android::vold::RestoreconRecursive(misc_ce_path);
743        }
744    }
745
746    return true;
747}
748
749bool e4crypt_destroy_user_storage(const char* volume_uuid, userid_t user_id, int flags) {
750    LOG(DEBUG) << "e4crypt_destroy_user_storage for volume " << escape_null(volume_uuid)
751               << ", user " << user_id << ", flags " << flags;
752    bool res = true;
753
754    if (flags & FLAG_STORAGE_DE) {
755        // DE_sys key
756        auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);
757        auto misc_legacy_path = android::vold::BuildDataMiscLegacyPath(user_id);
758        auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
759        auto foreign_de_path = android::vold::BuildDataProfilesForeignDexDePath(user_id);
760
761        // DE_n key
762        auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
763        auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
764        auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
765
766        if (volume_uuid == nullptr) {
767            res &= destroy_dir(system_legacy_path);
768#if MANAGE_MISC_DIRS
769            res &= destroy_dir(misc_legacy_path);
770#endif
771            res &= destroy_dir(profiles_de_path);
772            res &= destroy_dir(foreign_de_path);
773            res &= destroy_dir(system_de_path);
774            res &= destroy_dir(misc_de_path);
775        }
776        res &= destroy_dir(user_de_path);
777    }
778
779    if (flags & FLAG_STORAGE_CE) {
780        // CE_n key
781        auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
782        auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
783        auto media_ce_path = android::vold::BuildDataMediaCePath(volume_uuid, user_id);
784        auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
785
786        if (volume_uuid == nullptr) {
787            res &= destroy_dir(system_ce_path);
788            res &= destroy_dir(misc_ce_path);
789        }
790        res &= destroy_dir(media_ce_path);
791        res &= destroy_dir(user_ce_path);
792    }
793
794    return res;
795}
796