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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 
55 using android::base::StringPrintf;
56 using android::vold::kEmptyAuthentication;
57 
58 // NOTE: keep in sync with StorageManager
59 static constexpr int FLAG_STORAGE_DE = 1 << 0;
60 static constexpr int FLAG_STORAGE_CE = 1 << 1;
61 
62 namespace {
63 const std::string device_key_dir = std::string() + DATA_MNT_POINT + e4crypt_unencrypted_folder;
64 const std::string device_key_path = device_key_dir + "/key";
65 const std::string device_key_temp = device_key_dir + "/temp";
66 
67 const std::string user_key_dir = std::string() + DATA_MNT_POINT + "/misc/vold/user_keys";
68 const std::string user_key_temp = user_key_dir + "/temp";
69 
70 bool s_global_de_initialized = false;
71 
72 // Some users are ephemeral, don't try to wipe their keys from disk
73 std::set<userid_t> s_ephemeral_users;
74 
75 // Map user ids to key references
76 std::map<userid_t, std::string> s_de_key_raw_refs;
77 std::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
80 std::map<userid_t, std::string> s_ce_keys;
81 
82 // ext4enc:TODO get this const from somewhere good
83 const 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
87 constexpr int EXT4_ENCRYPTION_MODE_AES_256_XTS = 1;
88 constexpr int EXT4_AES_256_XTS_KEY_SIZE = 64;
89 constexpr int EXT4_MAX_KEY_SIZE = 64;
90 struct ext4_encryption_key {
91     uint32_t mode;
92     char raw[EXT4_MAX_KEY_SIZE];
93     uint32_t size;
94 };
95 }
96 
e4crypt_is_emulated()97 static bool e4crypt_is_emulated() {
98     return property_get_bool("persist.sys.emulate_fbe", false);
99 }
100 
escape_null(const char * value)101 static 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
generate_key_ref(const char * key,int length)106 static 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 
fill_key(const std::string & key,ext4_encryption_key * ext4_key)124 static 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 
keyname(const std::string & raw_ref)137 static 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
e4crypt_keyring(key_serial_t * device_keyring)147 static 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
install_key(const std::string & key,std::string * raw_ref)158 static 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 
get_de_key_path(userid_t user_id)177 static 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 
get_ce_key_directory_path(userid_t user_id)181 static 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
get_ce_key_paths(const std::string & directory_path)186 static 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 
get_ce_key_current_path(const std::string & directory_path)214 static std::string get_ce_key_current_path(const std::string& directory_path) {
215     return directory_path + "/current";
216 }
217 
get_ce_key_new_path(const std::string & directory_path,const std::vector<std::string> & paths,std::string * ce_key_path)218 static 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.
fixate_user_ce_key(const std::string & directory_path,const std::string & to_fix,const std::vector<std::string> & paths)237 static 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 
read_and_fixate_user_ce_key(userid_t user_id,const android::vold::KeyAuthentication & auth,std::string * ce_key)253 static 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 
read_and_install_user_ce_key(userid_t user_id,const android::vold::KeyAuthentication & auth)270 static 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 
prepare_dir(const std::string & dir,mode_t mode,uid_t uid,gid_t gid)283 static 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 
destroy_dir(const std::string & dir)292 static 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 
random_key(std::string * key)301 static 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 
path_exists(const std::string & path)310 static 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.
store_key(const std::string & key_path,const std::string & tmp_path,const android::vold::KeyAuthentication & auth,const std::string & key)316 static 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 
create_and_install_user_keys(userid_t user_id,bool create_ephemeral)334 static 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 
lookup_key_ref(const std::map<userid_t,std::string> & key_map,userid_t user_id,std::string * raw_ref)365 static 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 
ensure_policy(const std::string & raw_ref,const std::string & path)376 static 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 
is_numeric(const char * name)386 static 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 
load_all_de_keys()393 static 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 
e4crypt_initialize_global_de()430 bool 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 
e4crypt_init_user0()472 bool 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 
e4crypt_vold_create_user_key(userid_t user_id,int serial,bool ephemeral)502 bool 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 
e4crypt_destroy_user_key(userid_t user_id)520 bool 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 
emulated_lock(const std::string & path)547 static 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 
emulated_unlock(const std::string & path,mode_t mode)561 static 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 
parse_hex(const char * hex,std::string * result)577 static 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 
e4crypt_add_user_key_auth(userid_t user_id,int serial,const char * token_hex,const char * secret_hex)589 bool 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 
e4crypt_fixate_newest_user_key_auth(userid_t user_id)614 bool 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     if (s_ephemeral_users.count(user_id) != 0) return true;
618     auto const directory_path = get_ce_key_directory_path(user_id);
619     auto const paths = get_ce_key_paths(directory_path);
620     if (paths.empty()) {
621         LOG(ERROR) << "No ce keys present, cannot fixate for user " << user_id;
622         return false;
623     }
624     fixate_user_ce_key(directory_path, paths[0], paths);
625     return true;
626 }
627 
628 // TODO: rename to 'install' for consistency, and take flags to know which keys to install
e4crypt_unlock_user_key(userid_t user_id,int serial,const char * token_hex,const char * secret_hex)629 bool e4crypt_unlock_user_key(userid_t user_id, int serial, const char* token_hex,
630                              const char* secret_hex) {
631     LOG(DEBUG) << "e4crypt_unlock_user_key " << user_id << " serial=" << serial
632                << " token_present=" << (strcmp(token_hex, "!") != 0);
633     if (e4crypt_is_native()) {
634         if (s_ce_key_raw_refs.count(user_id) != 0) {
635             LOG(WARNING) << "Tried to unlock already-unlocked key for user " << user_id;
636             return true;
637         }
638         std::string token, secret;
639         if (!parse_hex(token_hex, &token)) return false;
640         if (!parse_hex(secret_hex, &secret)) return false;
641         android::vold::KeyAuthentication auth(token, secret);
642         if (!read_and_install_user_ce_key(user_id, auth)) {
643             LOG(ERROR) << "Couldn't read key for " << user_id;
644             return false;
645         }
646     } else {
647         // When in emulation mode, we just use chmod. However, we also
648         // unlock directories when not in emulation mode, to bring devices
649         // back into a known-good state.
650         if (!emulated_unlock(android::vold::BuildDataSystemCePath(user_id), 0771) ||
651             !emulated_unlock(android::vold::BuildDataMiscCePath(user_id), 01771) ||
652             !emulated_unlock(android::vold::BuildDataMediaCePath(nullptr, user_id), 0770) ||
653             !emulated_unlock(android::vold::BuildDataUserCePath(nullptr, user_id), 0771)) {
654             LOG(ERROR) << "Failed to unlock user " << user_id;
655             return false;
656         }
657     }
658     return true;
659 }
660 
661 // TODO: rename to 'evict' for consistency
e4crypt_lock_user_key(userid_t user_id)662 bool e4crypt_lock_user_key(userid_t user_id) {
663     if (e4crypt_is_native()) {
664         // TODO: remove from kernel keyring
665     } else if (e4crypt_is_emulated()) {
666         // When in emulation mode, we just use chmod
667         if (!emulated_lock(android::vold::BuildDataSystemCePath(user_id)) ||
668             !emulated_lock(android::vold::BuildDataMiscCePath(user_id)) ||
669             !emulated_lock(android::vold::BuildDataMediaCePath(nullptr, user_id)) ||
670             !emulated_lock(android::vold::BuildDataUserCePath(nullptr, user_id))) {
671             LOG(ERROR) << "Failed to lock user " << user_id;
672             return false;
673         }
674     }
675 
676     return true;
677 }
678 
e4crypt_prepare_user_storage(const char * volume_uuid,userid_t user_id,int serial,int flags)679 bool e4crypt_prepare_user_storage(const char* volume_uuid, userid_t user_id, int serial,
680         int flags) {
681     LOG(DEBUG) << "e4crypt_prepare_user_storage for volume " << escape_null(volume_uuid)
682                << ", user " << user_id << ", serial " << serial << ", flags " << flags;
683 
684     if (flags & FLAG_STORAGE_DE) {
685         // DE_sys key
686         auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);
687         auto misc_legacy_path = android::vold::BuildDataMiscLegacyPath(user_id);
688         auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
689         auto foreign_de_path = android::vold::BuildDataProfilesForeignDexDePath(user_id);
690 
691         // DE_n key
692         auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
693         auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
694         auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
695 
696         if (!prepare_dir(system_legacy_path, 0700, AID_SYSTEM, AID_SYSTEM)) return false;
697 #if MANAGE_MISC_DIRS
698         if (!prepare_dir(misc_legacy_path, 0750, multiuser_get_uid(user_id, AID_SYSTEM),
699                 multiuser_get_uid(user_id, AID_EVERYBODY))) return false;
700 #endif
701         if (!prepare_dir(profiles_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
702         if (!prepare_dir(foreign_de_path, 0773, AID_SYSTEM, AID_SYSTEM)) return false;
703 
704         if (!prepare_dir(system_de_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
705         if (!prepare_dir(misc_de_path, 01771, AID_SYSTEM, AID_MISC)) return false;
706         if (!prepare_dir(user_de_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
707 
708         // For now, FBE is only supported on internal storage
709         if (e4crypt_is_native() && volume_uuid == nullptr) {
710             std::string de_raw_ref;
711             if (!lookup_key_ref(s_de_key_raw_refs, user_id, &de_raw_ref)) return false;
712             if (!ensure_policy(de_raw_ref, system_de_path)) return false;
713             if (!ensure_policy(de_raw_ref, misc_de_path)) return false;
714             if (!ensure_policy(de_raw_ref, user_de_path)) return false;
715         }
716     }
717 
718     if (flags & FLAG_STORAGE_CE) {
719         // CE_n key
720         auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
721         auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
722         auto media_ce_path = android::vold::BuildDataMediaCePath(volume_uuid, user_id);
723         auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
724 
725         if (!prepare_dir(system_ce_path, 0770, AID_SYSTEM, AID_SYSTEM)) return false;
726         if (!prepare_dir(misc_ce_path, 01771, AID_SYSTEM, AID_MISC)) return false;
727         if (!prepare_dir(media_ce_path, 0770, AID_MEDIA_RW, AID_MEDIA_RW)) return false;
728         if (!prepare_dir(user_ce_path, 0771, AID_SYSTEM, AID_SYSTEM)) return false;
729 
730         // For now, FBE is only supported on internal storage
731         if (e4crypt_is_native() && volume_uuid == nullptr) {
732             std::string ce_raw_ref;
733             if (!lookup_key_ref(s_ce_key_raw_refs, user_id, &ce_raw_ref)) return false;
734             if (!ensure_policy(ce_raw_ref, system_ce_path)) return false;
735             if (!ensure_policy(ce_raw_ref, misc_ce_path)) return false;
736             if (!ensure_policy(ce_raw_ref, media_ce_path)) return false;
737             if (!ensure_policy(ce_raw_ref, user_ce_path)) return false;
738 
739             // Now that credentials have been installed, we can run restorecon
740             // over these paths
741             // NOTE: these paths need to be kept in sync with libselinux
742             android::vold::RestoreconRecursive(system_ce_path);
743             android::vold::RestoreconRecursive(misc_ce_path);
744         }
745     }
746 
747     return true;
748 }
749 
e4crypt_destroy_user_storage(const char * volume_uuid,userid_t user_id,int flags)750 bool e4crypt_destroy_user_storage(const char* volume_uuid, userid_t user_id, int flags) {
751     LOG(DEBUG) << "e4crypt_destroy_user_storage for volume " << escape_null(volume_uuid)
752                << ", user " << user_id << ", flags " << flags;
753     bool res = true;
754 
755     if (flags & FLAG_STORAGE_DE) {
756         // DE_sys key
757         auto system_legacy_path = android::vold::BuildDataSystemLegacyPath(user_id);
758         auto misc_legacy_path = android::vold::BuildDataMiscLegacyPath(user_id);
759         auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
760         auto foreign_de_path = android::vold::BuildDataProfilesForeignDexDePath(user_id);
761 
762         // DE_n key
763         auto system_de_path = android::vold::BuildDataSystemDePath(user_id);
764         auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
765         auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
766 
767         if (volume_uuid == nullptr) {
768             res &= destroy_dir(system_legacy_path);
769 #if MANAGE_MISC_DIRS
770             res &= destroy_dir(misc_legacy_path);
771 #endif
772             res &= destroy_dir(profiles_de_path);
773             res &= destroy_dir(foreign_de_path);
774             res &= destroy_dir(system_de_path);
775             res &= destroy_dir(misc_de_path);
776         }
777         res &= destroy_dir(user_de_path);
778     }
779 
780     if (flags & FLAG_STORAGE_CE) {
781         // CE_n key
782         auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
783         auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
784         auto media_ce_path = android::vold::BuildDataMediaCePath(volume_uuid, user_id);
785         auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
786 
787         if (volume_uuid == nullptr) {
788             res &= destroy_dir(system_ce_path);
789             res &= destroy_dir(misc_ce_path);
790         }
791         res &= destroy_dir(media_ce_path);
792         res &= destroy_dir(user_ce_path);
793     }
794 
795     return res;
796 }
797