1 /*
2  * Copyright (C) 2008 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 "util.h"
18 
19 #include <ctype.h>
20 #include <errno.h>
21 #include <fcntl.h>
22 #include <pwd.h>
23 #include <signal.h>
24 #include <stdarg.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <sys/socket.h>
29 #include <sys/un.h>
30 #include <time.h>
31 #include <unistd.h>
32 
33 #include <thread>
34 
35 #include <android-base/file.h>
36 #include <android-base/logging.h>
37 #include <android-base/properties.h>
38 #include <android-base/scopeguard.h>
39 #include <android-base/strings.h>
40 #include <android-base/unique_fd.h>
41 #include <cutils/sockets.h>
42 #include <selinux/android.h>
43 
44 #ifdef INIT_FULL_SOURCES
45 #include <android/api-level.h>
46 #include <sys/system_properties.h>
47 
48 #include "reboot_utils.h"
49 #include "selabel.h"
50 #include "selinux.h"
51 #else
52 #include "host_init_stubs.h"
53 #endif
54 
55 using android::base::boot_clock;
56 using android::base::StartsWith;
57 using namespace std::literals::string_literals;
58 
59 namespace android {
60 namespace init {
61 
62 const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android/");
63 
64 void (*trigger_shutdown)(const std::string& command) = nullptr;
65 
66 // DecodeUid() - decodes and returns the given string, which can be either the
67 // numeric or name representation, into the integer uid or gid.
DecodeUid(const std::string & name)68 Result<uid_t> DecodeUid(const std::string& name) {
69     if (isalpha(name[0])) {
70         passwd* pwd = getpwnam(name.c_str());
71         if (!pwd) return ErrnoError() << "getpwnam failed";
72 
73         return pwd->pw_uid;
74     }
75 
76     errno = 0;
77     uid_t result = static_cast<uid_t>(strtoul(name.c_str(), 0, 0));
78     if (errno) return ErrnoError() << "strtoul failed";
79 
80     return result;
81 }
82 
83 /*
84  * CreateSocket - creates a Unix domain socket in ANDROID_SOCKET_DIR
85  * ("/dev/socket") as dictated in init.rc. This socket is inherited by the
86  * daemon. We communicate the file descriptor's value via the environment
87  * variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
88  */
CreateSocket(const std::string & name,int type,bool passcred,mode_t perm,uid_t uid,gid_t gid,const std::string & socketcon)89 Result<int> CreateSocket(const std::string& name, int type, bool passcred, mode_t perm, uid_t uid,
90                          gid_t gid, const std::string& socketcon) {
91     if (!socketcon.empty()) {
92         if (setsockcreatecon(socketcon.c_str()) == -1) {
93             return ErrnoError() << "setsockcreatecon(\"" << socketcon << "\") failed";
94         }
95     }
96 
97     android::base::unique_fd fd(socket(PF_UNIX, type, 0));
98     if (fd < 0) {
99         return ErrnoError() << "Failed to open socket '" << name << "'";
100     }
101 
102     if (!socketcon.empty()) setsockcreatecon(nullptr);
103 
104     struct sockaddr_un addr;
105     memset(&addr, 0 , sizeof(addr));
106     addr.sun_family = AF_UNIX;
107     snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR "/%s", name.c_str());
108 
109     if ((unlink(addr.sun_path) != 0) && (errno != ENOENT)) {
110         return ErrnoError() << "Failed to unlink old socket '" << name << "'";
111     }
112 
113     std::string secontext;
114     if (SelabelLookupFileContext(addr.sun_path, S_IFSOCK, &secontext) && !secontext.empty()) {
115         setfscreatecon(secontext.c_str());
116     }
117 
118     if (passcred) {
119         int on = 1;
120         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on))) {
121             return ErrnoError() << "Failed to set SO_PASSCRED '" << name << "'";
122         }
123     }
124 
125     int ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
126     int savederrno = errno;
127 
128     if (!secontext.empty()) {
129         setfscreatecon(nullptr);
130     }
131 
132     auto guard = android::base::make_scope_guard([&addr] { unlink(addr.sun_path); });
133 
134     if (ret) {
135         errno = savederrno;
136         return ErrnoError() << "Failed to bind socket '" << name << "'";
137     }
138 
139     if (lchown(addr.sun_path, uid, gid)) {
140         return ErrnoError() << "Failed to lchown socket '" << addr.sun_path << "'";
141     }
142     if (fchmodat(AT_FDCWD, addr.sun_path, perm, AT_SYMLINK_NOFOLLOW)) {
143         return ErrnoError() << "Failed to fchmodat socket '" << addr.sun_path << "'";
144     }
145 
146     LOG(INFO) << "Created socket '" << addr.sun_path << "'"
147               << ", mode " << std::oct << perm << std::dec
148               << ", user " << uid
149               << ", group " << gid;
150 
151     guard.Disable();
152     return fd.release();
153 }
154 
ReadFile(const std::string & path)155 Result<std::string> ReadFile(const std::string& path) {
156     android::base::unique_fd fd(
157         TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC)));
158     if (fd == -1) {
159         return ErrnoError() << "open() failed";
160     }
161 
162     // For security reasons, disallow world-writable
163     // or group-writable files.
164     struct stat sb;
165     if (fstat(fd, &sb) == -1) {
166         return ErrnoError() << "fstat failed()";
167     }
168     if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
169         return Error() << "Skipping insecure file";
170     }
171 
172     std::string content;
173     if (!android::base::ReadFdToString(fd, &content)) {
174         return ErrnoError() << "Unable to read file contents";
175     }
176     return content;
177 }
178 
OpenFile(const std::string & path,int flags,mode_t mode)179 static int OpenFile(const std::string& path, int flags, mode_t mode) {
180     std::string secontext;
181     if (SelabelLookupFileContext(path, mode, &secontext) && !secontext.empty()) {
182         setfscreatecon(secontext.c_str());
183     }
184 
185     int rc = open(path.c_str(), flags, mode);
186 
187     if (!secontext.empty()) {
188         int save_errno = errno;
189         setfscreatecon(nullptr);
190         errno = save_errno;
191     }
192 
193     return rc;
194 }
195 
WriteFile(const std::string & path,const std::string & content)196 Result<void> WriteFile(const std::string& path, const std::string& content) {
197     android::base::unique_fd fd(TEMP_FAILURE_RETRY(
198         OpenFile(path, O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0600)));
199     if (fd == -1) {
200         return ErrnoError() << "open() failed";
201     }
202     if (!android::base::WriteStringToFd(content, fd)) {
203         return ErrnoError() << "Unable to write file contents";
204     }
205     return {};
206 }
207 
mkdir_recursive(const std::string & path,mode_t mode)208 bool mkdir_recursive(const std::string& path, mode_t mode) {
209     std::string::size_type slash = 0;
210     while ((slash = path.find('/', slash + 1)) != std::string::npos) {
211         auto directory = path.substr(0, slash);
212         struct stat info;
213         if (stat(directory.c_str(), &info) != 0) {
214             auto ret = make_dir(directory, mode);
215             if (!ret && errno != EEXIST) return false;
216         }
217     }
218     auto ret = make_dir(path, mode);
219     if (!ret && errno != EEXIST) return false;
220     return true;
221 }
222 
wait_for_file(const char * filename,std::chrono::nanoseconds timeout)223 int wait_for_file(const char* filename, std::chrono::nanoseconds timeout) {
224     android::base::Timer t;
225     while (t.duration() < timeout) {
226         struct stat sb;
227         if (stat(filename, &sb) != -1) {
228             LOG(INFO) << "wait for '" << filename << "' took " << t;
229             return 0;
230         }
231         std::this_thread::sleep_for(10ms);
232     }
233     LOG(WARNING) << "wait for '" << filename << "' timed out and took " << t;
234     return -1;
235 }
236 
ImportKernelCmdline(const std::function<void (const std::string &,const std::string &)> & fn)237 void ImportKernelCmdline(const std::function<void(const std::string&, const std::string&)>& fn) {
238     std::string cmdline;
239     android::base::ReadFileToString("/proc/cmdline", &cmdline);
240 
241     for (const auto& entry : android::base::Split(android::base::Trim(cmdline), " ")) {
242         std::vector<std::string> pieces = android::base::Split(entry, "=");
243         if (pieces.size() == 2) {
244             fn(pieces[0], pieces[1]);
245         }
246     }
247 }
248 
ImportBootconfig(const std::function<void (const std::string &,const std::string &)> & fn)249 void ImportBootconfig(const std::function<void(const std::string&, const std::string&)>& fn) {
250     std::string bootconfig;
251     android::base::ReadFileToString("/proc/bootconfig", &bootconfig);
252 
253     for (const auto& entry : android::base::Split(bootconfig, "\n")) {
254         std::vector<std::string> pieces = android::base::Split(entry, "=");
255         if (pieces.size() == 2) {
256             // get rid of the extra space between a list of values and remove the quotes.
257             std::string value = android::base::StringReplace(pieces[1], "\", \"", ",", true);
258             value.erase(std::remove(value.begin(), value.end(), '"'), value.end());
259             fn(android::base::Trim(pieces[0]), android::base::Trim(value));
260         }
261     }
262 }
263 
make_dir(const std::string & path,mode_t mode)264 bool make_dir(const std::string& path, mode_t mode) {
265     std::string secontext;
266     if (SelabelLookupFileContext(path, mode, &secontext) && !secontext.empty()) {
267         setfscreatecon(secontext.c_str());
268     }
269 
270     int rc = mkdir(path.c_str(), mode);
271 
272     if (!secontext.empty()) {
273         int save_errno = errno;
274         setfscreatecon(nullptr);
275         errno = save_errno;
276     }
277 
278     return rc == 0;
279 }
280 
281 /*
282  * Returns true is pathname is a directory
283  */
is_dir(const char * pathname)284 bool is_dir(const char* pathname) {
285     struct stat info;
286     if (stat(pathname, &info) == -1) {
287         return false;
288     }
289     return S_ISDIR(info.st_mode);
290 }
291 
ExpandProps(const std::string & src)292 Result<std::string> ExpandProps(const std::string& src) {
293     const char* src_ptr = src.c_str();
294 
295     std::string dst;
296 
297     /* - variables can either be $x.y or ${x.y}, in case they are only part
298      *   of the string.
299      * - will accept $$ as a literal $.
300      * - no nested property expansion, i.e. ${foo.${bar}} is not supported,
301      *   bad things will happen
302      * - ${x.y:-default} will return default value if property empty.
303      */
304     while (*src_ptr) {
305         const char* c;
306 
307         c = strchr(src_ptr, '$');
308         if (!c) {
309             dst.append(src_ptr);
310             return dst;
311         }
312 
313         dst.append(src_ptr, c);
314         c++;
315 
316         if (*c == '$') {
317             dst.push_back(*(c++));
318             src_ptr = c;
319             continue;
320         } else if (*c == '\0') {
321             return dst;
322         }
323 
324         std::string prop_name;
325         std::string def_val;
326         if (*c == '{') {
327             c++;
328             const char* end = strchr(c, '}');
329             if (!end) {
330                 // failed to find closing brace, abort.
331                 return Error() << "unexpected end of string in '" << src << "', looking for }";
332             }
333             prop_name = std::string(c, end);
334             c = end + 1;
335             size_t def = prop_name.find(":-");
336             if (def < prop_name.size()) {
337                 def_val = prop_name.substr(def + 2);
338                 prop_name = prop_name.substr(0, def);
339             }
340         } else {
341             prop_name = c;
342             if (SelinuxGetVendorAndroidVersion() >= __ANDROID_API_R__) {
343                 return Error() << "using deprecated syntax for specifying property '" << c
344                                << "', use ${name} instead";
345             } else {
346                 LOG(ERROR) << "using deprecated syntax for specifying property '" << c
347                            << "', use ${name} instead";
348             }
349             c += prop_name.size();
350         }
351 
352         if (prop_name.empty()) {
353             return Error() << "invalid zero-length property name in '" << src << "'";
354         }
355 
356         std::string prop_val = android::base::GetProperty(prop_name, "");
357         if (prop_val.empty()) {
358             if (def_val.empty()) {
359                 return Error() << "property '" << prop_name << "' doesn't exist while expanding '"
360                                << src << "'";
361             }
362             prop_val = def_val;
363         }
364 
365         dst.append(prop_val);
366         src_ptr = c;
367     }
368 
369     return dst;
370 }
371 
init_android_dt_dir()372 static std::string init_android_dt_dir() {
373     // Use the standard procfs-based path by default
374     std::string android_dt_dir = kDefaultAndroidDtDir;
375     // The platform may specify a custom Android DT path in kernel cmdline
376     ImportKernelCmdline([&](const std::string& key, const std::string& value) {
377         if (key == "androidboot.android_dt_dir") {
378             android_dt_dir = value;
379         }
380     });
381     // ..Or bootconfig
382     if (android_dt_dir == kDefaultAndroidDtDir) {
383         ImportBootconfig([&](const std::string& key, const std::string& value) {
384             if (key == "androidboot.android_dt_dir") {
385                 android_dt_dir = value;
386             }
387         });
388     }
389 
390     LOG(INFO) << "Using Android DT directory " << android_dt_dir;
391     return android_dt_dir;
392 }
393 
394 // FIXME: The same logic is duplicated in system/core/fs_mgr/
get_android_dt_dir()395 const std::string& get_android_dt_dir() {
396     // Set once and saves time for subsequent calls to this function
397     static const std::string kAndroidDtDir = init_android_dt_dir();
398     return kAndroidDtDir;
399 }
400 
401 // Reads the content of device tree file under the platform's Android DT directory.
402 // Returns true if the read is success, false otherwise.
read_android_dt_file(const std::string & sub_path,std::string * dt_content)403 bool read_android_dt_file(const std::string& sub_path, std::string* dt_content) {
404     const std::string file_name = get_android_dt_dir() + sub_path;
405     if (android::base::ReadFileToString(file_name, dt_content)) {
406         if (!dt_content->empty()) {
407             dt_content->pop_back();  // Trims the trailing '\0' out.
408             return true;
409         }
410     }
411     return false;
412 }
413 
is_android_dt_value_expected(const std::string & sub_path,const std::string & expected_content)414 bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content) {
415     std::string dt_content;
416     if (read_android_dt_file(sub_path, &dt_content)) {
417         if (dt_content == expected_content) {
418             return true;
419         }
420     }
421     return false;
422 }
423 
IsLegalPropertyName(const std::string & name)424 bool IsLegalPropertyName(const std::string& name) {
425     size_t namelen = name.size();
426 
427     if (namelen < 1) return false;
428     if (name[0] == '.') return false;
429     if (name[namelen - 1] == '.') return false;
430 
431     /* Only allow alphanumeric, plus '.', '-', '@', ':', or '_' */
432     /* Don't allow ".." to appear in a property name */
433     for (size_t i = 0; i < namelen; i++) {
434         if (name[i] == '.') {
435             // i=0 is guaranteed to never have a dot. See above.
436             if (name[i - 1] == '.') return false;
437             continue;
438         }
439         if (name[i] == '_' || name[i] == '-' || name[i] == '@' || name[i] == ':') continue;
440         if (name[i] >= 'a' && name[i] <= 'z') continue;
441         if (name[i] >= 'A' && name[i] <= 'Z') continue;
442         if (name[i] >= '0' && name[i] <= '9') continue;
443         return false;
444     }
445 
446     return true;
447 }
448 
IsLegalPropertyValue(const std::string & name,const std::string & value)449 Result<void> IsLegalPropertyValue(const std::string& name, const std::string& value) {
450     if (value.size() >= PROP_VALUE_MAX && !StartsWith(name, "ro.")) {
451         return Error() << "Property value too long";
452     }
453 
454     if (mbstowcs(nullptr, value.data(), 0) == static_cast<std::size_t>(-1)) {
455         return Error() << "Value is not a UTF8 encoded string";
456     }
457 
458     return {};
459 }
460 
FscryptInferAction(const std::string & dir)461 static FscryptAction FscryptInferAction(const std::string& dir) {
462     const std::string prefix = "/data/";
463 
464     if (!android::base::StartsWith(dir, prefix)) {
465         return FscryptAction::kNone;
466     }
467 
468     // Special-case /data/media/obb per b/64566063
469     if (dir == "/data/media/obb") {
470         // Try to set policy on this directory, but if it is non-empty this may fail.
471         return FscryptAction::kAttempt;
472     }
473 
474     // Only set policy on first level /data directories
475     // To make this less restrictive, consider using a policy file.
476     // However this is overkill for as long as the policy is simply
477     // to apply a global policy to all /data folders created via makedir
478     if (dir.find_first_of('/', prefix.size()) != std::string::npos) {
479         return FscryptAction::kNone;
480     }
481 
482     // Special case various directories that must not be encrypted,
483     // often because their subdirectories must be encrypted.
484     // This isn't a nice way to do this, see b/26641735
485     std::vector<std::string> directories_to_exclude = {
486             "lost+found", "system_ce", "system_de", "misc_ce",     "misc_de",
487             "vendor_ce",  "vendor_de", "media",     "data",        "user",
488             "user_de",    "apex",      "preloads",  "app-staging", "gsi",
489     };
490     for (const auto& d : directories_to_exclude) {
491         if ((prefix + d) == dir) {
492             return FscryptAction::kNone;
493         }
494     }
495     // Empty these directories if policy setting fails.
496     std::vector<std::string> wipe_on_failure = {
497             "rollback", "rollback-observer",  // b/139193659
498     };
499     for (const auto& d : wipe_on_failure) {
500         if ((prefix + d) == dir) {
501             return FscryptAction::kDeleteIfNecessary;
502         }
503     }
504     return FscryptAction::kRequire;
505 }
506 
ParseMkdir(const std::vector<std::string> & args)507 Result<MkdirOptions> ParseMkdir(const std::vector<std::string>& args) {
508     mode_t mode = 0755;
509     Result<uid_t> uid = -1;
510     Result<gid_t> gid = -1;
511     FscryptAction fscrypt_inferred_action = FscryptInferAction(args[1]);
512     FscryptAction fscrypt_action = fscrypt_inferred_action;
513     std::string ref_option = "ref";
514     bool set_option_encryption = false;
515     bool set_option_key = false;
516 
517     for (size_t i = 2; i < args.size(); i++) {
518         switch (i) {
519             case 2:
520                 mode = std::strtoul(args[2].c_str(), 0, 8);
521                 break;
522             case 3:
523                 uid = DecodeUid(args[3]);
524                 if (!uid.ok()) {
525                     return Error()
526                            << "Unable to decode UID for '" << args[3] << "': " << uid.error();
527                 }
528                 break;
529             case 4:
530                 gid = DecodeUid(args[4]);
531                 if (!gid.ok()) {
532                     return Error()
533                            << "Unable to decode GID for '" << args[4] << "': " << gid.error();
534                 }
535                 break;
536             default:
537                 auto parts = android::base::Split(args[i], "=");
538                 if (parts.size() != 2) {
539                     return Error() << "Can't parse option: '" << args[i] << "'";
540                 }
541                 auto optname = parts[0];
542                 auto optval = parts[1];
543                 if (optname == "encryption") {
544                     if (set_option_encryption) {
545                         return Error() << "Duplicated option: '" << optname << "'";
546                     }
547                     if (optval == "Require") {
548                         fscrypt_action = FscryptAction::kRequire;
549                     } else if (optval == "None") {
550                         fscrypt_action = FscryptAction::kNone;
551                     } else if (optval == "Attempt") {
552                         fscrypt_action = FscryptAction::kAttempt;
553                     } else if (optval == "DeleteIfNecessary") {
554                         fscrypt_action = FscryptAction::kDeleteIfNecessary;
555                     } else {
556                         return Error() << "Unknown encryption option: '" << optval << "'";
557                     }
558                     set_option_encryption = true;
559                 } else if (optname == "key") {
560                     if (set_option_key) {
561                         return Error() << "Duplicated option: '" << optname << "'";
562                     }
563                     if (optval == "ref" || optval == "per_boot_ref") {
564                         ref_option = optval;
565                     } else {
566                         return Error() << "Unknown key option: '" << optval << "'";
567                     }
568                     set_option_key = true;
569                 } else {
570                     return Error() << "Unknown option: '" << args[i] << "'";
571                 }
572         }
573     }
574     if (set_option_key && fscrypt_action == FscryptAction::kNone) {
575         return Error() << "Key option set but encryption action is none";
576     }
577     const std::string prefix = "/data/";
578     if (StartsWith(args[1], prefix) &&
579         args[1].find_first_of('/', prefix.size()) == std::string::npos) {
580         if (!set_option_encryption) {
581             LOG(WARNING) << "Top-level directory needs encryption action, eg mkdir " << args[1]
582                          << " <mode> <uid> <gid> encryption=Require";
583         }
584         if (fscrypt_action == FscryptAction::kNone) {
585             LOG(INFO) << "Not setting encryption policy on: " << args[1];
586         }
587     }
588     if (fscrypt_action != fscrypt_inferred_action) {
589         LOG(WARNING) << "Inferred action different from explicit one, expected "
590                      << static_cast<int>(fscrypt_inferred_action) << " but got "
591                      << static_cast<int>(fscrypt_action);
592     }
593 
594     return MkdirOptions{args[1], mode, *uid, *gid, fscrypt_action, ref_option};
595 }
596 
ParseMountAll(const std::vector<std::string> & args)597 Result<MountAllOptions> ParseMountAll(const std::vector<std::string>& args) {
598     bool compat_mode = false;
599     bool import_rc = false;
600     if (SelinuxGetVendorAndroidVersion() <= __ANDROID_API_Q__) {
601         if (args.size() <= 1) {
602             return Error() << "mount_all requires at least 1 argument";
603         }
604         compat_mode = true;
605         import_rc = true;
606     }
607 
608     std::size_t first_option_arg = args.size();
609     enum mount_mode mode = MOUNT_MODE_DEFAULT;
610 
611     // If we are <= Q, then stop looking for non-fstab arguments at slot 2.
612     // Otherwise, stop looking at slot 1 (as the fstab path argument is optional >= R).
613     for (std::size_t na = args.size() - 1; na > (compat_mode ? 1 : 0); --na) {
614         if (args[na] == "--early") {
615             first_option_arg = na;
616             mode = MOUNT_MODE_EARLY;
617         } else if (args[na] == "--late") {
618             first_option_arg = na;
619             mode = MOUNT_MODE_LATE;
620             import_rc = false;
621         }
622     }
623 
624     std::string fstab_path;
625     if (first_option_arg > 1) {
626         fstab_path = args[1];
627     } else if (compat_mode) {
628         return Error() << "mount_all argument 1 must be the fstab path";
629     }
630 
631     std::vector<std::string> rc_paths;
632     for (std::size_t na = 2; na < first_option_arg; ++na) {
633         rc_paths.push_back(args[na]);
634     }
635 
636     return MountAllOptions{rc_paths, fstab_path, mode, import_rc};
637 }
638 
ParseRestorecon(const std::vector<std::string> & args)639 Result<std::pair<int, std::vector<std::string>>> ParseRestorecon(
640         const std::vector<std::string>& args) {
641     struct flag_type {
642         const char* name;
643         int value;
644     };
645     static const flag_type flags[] = {
646             {"--recursive", SELINUX_ANDROID_RESTORECON_RECURSE},
647             {"--skip-ce", SELINUX_ANDROID_RESTORECON_SKIPCE},
648             {"--cross-filesystems", SELINUX_ANDROID_RESTORECON_CROSS_FILESYSTEMS},
649             {0, 0}};
650 
651     int flag = 0;
652     std::vector<std::string> paths;
653 
654     bool in_flags = true;
655     for (size_t i = 1; i < args.size(); ++i) {
656         if (android::base::StartsWith(args[i], "--")) {
657             if (!in_flags) {
658                 return Error() << "flags must precede paths";
659             }
660             bool found = false;
661             for (size_t j = 0; flags[j].name; ++j) {
662                 if (args[i] == flags[j].name) {
663                     flag |= flags[j].value;
664                     found = true;
665                     break;
666                 }
667             }
668             if (!found) {
669                 return Error() << "bad flag " << args[i];
670             }
671         } else {
672             in_flags = false;
673             paths.emplace_back(args[i]);
674         }
675     }
676     return std::pair(flag, paths);
677 }
678 
ParseSwaponAll(const std::vector<std::string> & args)679 Result<std::string> ParseSwaponAll(const std::vector<std::string>& args) {
680     if (args.size() <= 1) {
681         if (SelinuxGetVendorAndroidVersion() <= __ANDROID_API_Q__) {
682             return Error() << "swapon_all requires at least 1 argument";
683         }
684         return {};
685     }
686     return args[1];
687 }
688 
ParseUmountAll(const std::vector<std::string> & args)689 Result<std::string> ParseUmountAll(const std::vector<std::string>& args) {
690     if (args.size() <= 1) {
691         if (SelinuxGetVendorAndroidVersion() <= __ANDROID_API_Q__) {
692             return Error() << "umount_all requires at least 1 argument";
693         }
694         return {};
695     }
696     return args[1];
697 }
698 
InitAborter(const char * abort_message)699 static void InitAborter(const char* abort_message) {
700     // When init forks, it continues to use this aborter for LOG(FATAL), but we want children to
701     // simply abort instead of trying to reboot the system.
702     if (getpid() != 1) {
703         android::base::DefaultAborter(abort_message);
704         return;
705     }
706 
707     InitFatalReboot(SIGABRT);
708 }
709 
710 // The kernel opens /dev/console and uses that fd for stdin/stdout/stderr if there is a serial
711 // console enabled and no initramfs, otherwise it does not provide any fds for stdin/stdout/stderr.
712 // SetStdioToDevNull() is used to close these existing fds if they exist and replace them with
713 // /dev/null regardless.
714 //
715 // In the case that these fds are provided by the kernel, the exec of second stage init causes an
716 // SELinux denial as it does not have access to /dev/console.  In the case that they are not
717 // provided, exec of any further process is potentially dangerous as the first fd's opened by that
718 // process will take the stdin/stdout/stderr fileno's, which can cause issues if printf(), etc is
719 // then used by that process.
720 //
721 // Lastly, simply calling SetStdioToDevNull() in first stage init is not enough, since first
722 // stage init still runs in kernel context, future child processes will not have permissions to
723 // access any fds that it opens, including the one opened below for /dev/null.  Therefore,
724 // SetStdioToDevNull() must be called again in second stage init.
SetStdioToDevNull(char ** argv)725 void SetStdioToDevNull(char** argv) {
726     // Make stdin/stdout/stderr all point to /dev/null.
727     int fd = open("/dev/null", O_RDWR);  // NOLINT(android-cloexec-open)
728     if (fd == -1) {
729         int saved_errno = errno;
730         android::base::InitLogging(argv, &android::base::KernelLogger, InitAborter);
731         errno = saved_errno;
732         PLOG(FATAL) << "Couldn't open /dev/null";
733     }
734     dup2(fd, STDIN_FILENO);
735     dup2(fd, STDOUT_FILENO);
736     dup2(fd, STDERR_FILENO);
737     if (fd > STDERR_FILENO) close(fd);
738 }
739 
InitKernelLogging(char ** argv)740 void InitKernelLogging(char** argv) {
741     SetFatalRebootTarget();
742     android::base::InitLogging(argv, &android::base::KernelLogger, InitAborter);
743 }
744 
IsRecoveryMode()745 bool IsRecoveryMode() {
746     return access("/system/bin/recovery", F_OK) == 0;
747 }
748 
749 // Check if default mount namespace is ready to be used with APEX modules
750 static bool is_default_mount_namespace_ready = false;
751 
IsDefaultMountNamespaceReady()752 bool IsDefaultMountNamespaceReady() {
753     return is_default_mount_namespace_ready;
754 }
755 
SetDefaultMountNamespaceReady()756 void SetDefaultMountNamespaceReady() {
757     is_default_mount_namespace_ready = true;
758 }
759 
760 }  // namespace init
761 }  // namespace android
762