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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 "Utils.h"
18 
19 #include "Process.h"
20 #include "sehandle.h"
21 
22 #include <android-base/chrono_utils.h>
23 #include <android-base/file.h>
24 #include <android-base/logging.h>
25 #include <android-base/properties.h>
26 #include <android-base/stringprintf.h>
27 #include <android-base/strings.h>
28 #include <android-base/unique_fd.h>
29 #include <cutils/fs.h>
30 #include <logwrap/logwrap.h>
31 #include <private/android_filesystem_config.h>
32 
33 #include <dirent.h>
34 #include <fcntl.h>
35 #include <linux/fs.h>
36 #include <mntent.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <unistd.h>
40 #include <sys/mount.h>
41 #include <sys/stat.h>
42 #include <sys/statvfs.h>
43 #include <sys/sysmacros.h>
44 #include <sys/types.h>
45 #include <sys/wait.h>
46 
47 #include <list>
48 #include <mutex>
49 #include <thread>
50 
51 #ifndef UMOUNT_NOFOLLOW
52 #define UMOUNT_NOFOLLOW 0x00000008 /* Don't follow symlink on umount */
53 #endif
54 
55 using namespace std::chrono_literals;
56 using android::base::ReadFileToString;
57 using android::base::StringPrintf;
58 
59 namespace android {
60 namespace vold {
61 
62 security_context_t sBlkidContext = nullptr;
63 security_context_t sBlkidUntrustedContext = nullptr;
64 security_context_t sFsckContext = nullptr;
65 security_context_t sFsckUntrustedContext = nullptr;
66 
67 bool sSleepOnUnmount = true;
68 
69 static const char* kBlkidPath = "/system/bin/blkid";
70 static const char* kKeyPath = "/data/misc/vold";
71 
72 static const char* kProcFilesystems = "/proc/filesystems";
73 
74 // Lock used to protect process-level SELinux changes from racing with each
75 // other between multiple threads.
76 static std::mutex kSecurityLock;
77 
CreateDeviceNode(const std::string & path,dev_t dev)78 status_t CreateDeviceNode(const std::string& path, dev_t dev) {
79     std::lock_guard<std::mutex> lock(kSecurityLock);
80     const char* cpath = path.c_str();
81     status_t res = 0;
82 
83     char* secontext = nullptr;
84     if (sehandle) {
85         if (!selabel_lookup(sehandle, &secontext, cpath, S_IFBLK)) {
86             setfscreatecon(secontext);
87         }
88     }
89 
90     mode_t mode = 0660 | S_IFBLK;
91     if (mknod(cpath, mode, dev) < 0) {
92         if (errno != EEXIST) {
93             PLOG(ERROR) << "Failed to create device node for " << major(dev) << ":" << minor(dev)
94                         << " at " << path;
95             res = -errno;
96         }
97     }
98 
99     if (secontext) {
100         setfscreatecon(nullptr);
101         freecon(secontext);
102     }
103 
104     return res;
105 }
106 
DestroyDeviceNode(const std::string & path)107 status_t DestroyDeviceNode(const std::string& path) {
108     const char* cpath = path.c_str();
109     if (TEMP_FAILURE_RETRY(unlink(cpath))) {
110         return -errno;
111     } else {
112         return OK;
113     }
114 }
115 
PrepareDir(const std::string & path,mode_t mode,uid_t uid,gid_t gid)116 status_t PrepareDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid) {
117     std::lock_guard<std::mutex> lock(kSecurityLock);
118     const char* cpath = path.c_str();
119 
120     char* secontext = nullptr;
121     if (sehandle) {
122         if (!selabel_lookup(sehandle, &secontext, cpath, S_IFDIR)) {
123             setfscreatecon(secontext);
124         }
125     }
126 
127     int res = fs_prepare_dir(cpath, mode, uid, gid);
128 
129     if (secontext) {
130         setfscreatecon(nullptr);
131         freecon(secontext);
132     }
133 
134     if (res == 0) {
135         return OK;
136     } else {
137         return -errno;
138     }
139 }
140 
ForceUnmount(const std::string & path)141 status_t ForceUnmount(const std::string& path) {
142     const char* cpath = path.c_str();
143     if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
144         return OK;
145     }
146     // Apps might still be handling eject request, so wait before
147     // we start sending signals
148     if (sSleepOnUnmount) sleep(5);
149 
150     KillProcessesWithOpenFiles(path, SIGINT);
151     if (sSleepOnUnmount) sleep(5);
152     if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
153         return OK;
154     }
155 
156     KillProcessesWithOpenFiles(path, SIGTERM);
157     if (sSleepOnUnmount) sleep(5);
158     if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
159         return OK;
160     }
161 
162     KillProcessesWithOpenFiles(path, SIGKILL);
163     if (sSleepOnUnmount) sleep(5);
164     if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
165         return OK;
166     }
167 
168     return -errno;
169 }
170 
KillProcessesUsingPath(const std::string & path)171 status_t KillProcessesUsingPath(const std::string& path) {
172     if (KillProcessesWithOpenFiles(path, SIGINT) == 0) {
173         return OK;
174     }
175     if (sSleepOnUnmount) sleep(5);
176 
177     if (KillProcessesWithOpenFiles(path, SIGTERM) == 0) {
178         return OK;
179     }
180     if (sSleepOnUnmount) sleep(5);
181 
182     if (KillProcessesWithOpenFiles(path, SIGKILL) == 0) {
183         return OK;
184     }
185     if (sSleepOnUnmount) sleep(5);
186 
187     // Send SIGKILL a second time to determine if we've
188     // actually killed everyone with open files
189     if (KillProcessesWithOpenFiles(path, SIGKILL) == 0) {
190         return OK;
191     }
192     PLOG(ERROR) << "Failed to kill processes using " << path;
193     return -EBUSY;
194 }
195 
BindMount(const std::string & source,const std::string & target)196 status_t BindMount(const std::string& source, const std::string& target) {
197     if (UnmountTree(target) < 0) {
198         return -errno;
199     }
200     if (TEMP_FAILURE_RETRY(mount(source.c_str(), target.c_str(), nullptr, MS_BIND, nullptr)) < 0) {
201         PLOG(ERROR) << "Failed to bind mount " << source << " to " << target;
202         return -errno;
203     }
204     return OK;
205 }
206 
Symlink(const std::string & target,const std::string & linkpath)207 status_t Symlink(const std::string& target, const std::string& linkpath) {
208     if (Unlink(linkpath) < 0) {
209         return -errno;
210     }
211     if (TEMP_FAILURE_RETRY(symlink(target.c_str(), linkpath.c_str())) < 0) {
212         PLOG(ERROR) << "Failed to create symlink " << linkpath << " to " << target;
213         return -errno;
214     }
215     return OK;
216 }
217 
Unlink(const std::string & linkpath)218 status_t Unlink(const std::string& linkpath) {
219     if (TEMP_FAILURE_RETRY(unlink(linkpath.c_str())) < 0 && errno != EINVAL && errno != ENOENT) {
220         PLOG(ERROR) << "Failed to unlink " << linkpath;
221         return -errno;
222     }
223     return OK;
224 }
225 
CreateDir(const std::string & dir,mode_t mode)226 status_t CreateDir(const std::string& dir, mode_t mode) {
227     struct stat sb;
228     if (TEMP_FAILURE_RETRY(stat(dir.c_str(), &sb)) == 0) {
229         if (S_ISDIR(sb.st_mode)) {
230             return OK;
231         } else if (TEMP_FAILURE_RETRY(unlink(dir.c_str())) == -1) {
232             PLOG(ERROR) << "Failed to unlink " << dir;
233             return -errno;
234         }
235     } else if (errno != ENOENT) {
236         PLOG(ERROR) << "Failed to stat " << dir;
237         return -errno;
238     }
239     if (TEMP_FAILURE_RETRY(mkdir(dir.c_str(), mode)) == -1 && errno != EEXIST) {
240         PLOG(ERROR) << "Failed to mkdir " << dir;
241         return -errno;
242     }
243     return OK;
244 }
245 
FindValue(const std::string & raw,const std::string & key,std::string * value)246 bool FindValue(const std::string& raw, const std::string& key, std::string* value) {
247     auto qual = key + "=\"";
248     size_t start = 0;
249     while (true) {
250         start = raw.find(qual, start);
251         if (start == std::string::npos) return false;
252         if (start == 0 || raw[start - 1] == ' ') {
253             break;
254         }
255         start += 1;
256     }
257     start += qual.length();
258 
259     auto end = raw.find("\"", start);
260     if (end == std::string::npos) return false;
261 
262     *value = raw.substr(start, end - start);
263     return true;
264 }
265 
readMetadata(const std::string & path,std::string * fsType,std::string * fsUuid,std::string * fsLabel,bool untrusted)266 static status_t readMetadata(const std::string& path, std::string* fsType, std::string* fsUuid,
267                              std::string* fsLabel, bool untrusted) {
268     fsType->clear();
269     fsUuid->clear();
270     fsLabel->clear();
271 
272     std::vector<std::string> cmd;
273     cmd.push_back(kBlkidPath);
274     cmd.push_back("-c");
275     cmd.push_back("/dev/null");
276     cmd.push_back("-s");
277     cmd.push_back("TYPE");
278     cmd.push_back("-s");
279     cmd.push_back("UUID");
280     cmd.push_back("-s");
281     cmd.push_back("LABEL");
282     cmd.push_back(path);
283 
284     std::vector<std::string> output;
285     status_t res = ForkExecvp(cmd, &output, untrusted ? sBlkidUntrustedContext : sBlkidContext);
286     if (res != OK) {
287         LOG(WARNING) << "blkid failed to identify " << path;
288         return res;
289     }
290 
291     for (const auto& line : output) {
292         // Extract values from blkid output, if defined
293         FindValue(line, "TYPE", fsType);
294         FindValue(line, "UUID", fsUuid);
295         FindValue(line, "LABEL", fsLabel);
296     }
297 
298     return OK;
299 }
300 
ReadMetadata(const std::string & path,std::string * fsType,std::string * fsUuid,std::string * fsLabel)301 status_t ReadMetadata(const std::string& path, std::string* fsType, std::string* fsUuid,
302                       std::string* fsLabel) {
303     return readMetadata(path, fsType, fsUuid, fsLabel, false);
304 }
305 
ReadMetadataUntrusted(const std::string & path,std::string * fsType,std::string * fsUuid,std::string * fsLabel)306 status_t ReadMetadataUntrusted(const std::string& path, std::string* fsType, std::string* fsUuid,
307                                std::string* fsLabel) {
308     return readMetadata(path, fsType, fsUuid, fsLabel, true);
309 }
310 
ConvertToArgv(const std::vector<std::string> & args)311 static std::vector<const char*> ConvertToArgv(const std::vector<std::string>& args) {
312     std::vector<const char*> argv;
313     argv.reserve(args.size() + 1);
314     for (const auto& arg : args) {
315         if (argv.empty()) {
316             LOG(DEBUG) << arg;
317         } else {
318             LOG(DEBUG) << "    " << arg;
319         }
320         argv.emplace_back(arg.data());
321     }
322     argv.emplace_back(nullptr);
323     return argv;
324 }
325 
ReadLinesFromFdAndLog(std::vector<std::string> * output,android::base::unique_fd ufd)326 static status_t ReadLinesFromFdAndLog(std::vector<std::string>* output,
327                                       android::base::unique_fd ufd) {
328     std::unique_ptr<FILE, int (*)(FILE*)> fp(android::base::Fdopen(std::move(ufd), "r"), fclose);
329     if (!fp) {
330         PLOG(ERROR) << "fdopen in ReadLinesFromFdAndLog";
331         return -errno;
332     }
333     if (output) output->clear();
334     char line[1024];
335     while (fgets(line, sizeof(line), fp.get()) != nullptr) {
336         LOG(DEBUG) << line;
337         if (output) output->emplace_back(line);
338     }
339     return OK;
340 }
341 
ForkExecvp(const std::vector<std::string> & args,std::vector<std::string> * output,security_context_t context)342 status_t ForkExecvp(const std::vector<std::string>& args, std::vector<std::string>* output,
343                     security_context_t context) {
344     auto argv = ConvertToArgv(args);
345 
346     android::base::unique_fd pipe_read, pipe_write;
347     if (!android::base::Pipe(&pipe_read, &pipe_write)) {
348         PLOG(ERROR) << "Pipe in ForkExecvp";
349         return -errno;
350     }
351 
352     pid_t pid = fork();
353     if (pid == 0) {
354         if (context) {
355             if (setexeccon(context)) {
356                 LOG(ERROR) << "Failed to setexeccon in ForkExecvp";
357                 abort();
358             }
359         }
360         pipe_read.reset();
361         if (dup2(pipe_write.get(), STDOUT_FILENO) == -1) {
362             PLOG(ERROR) << "dup2 in ForkExecvp";
363             _exit(EXIT_FAILURE);
364         }
365         pipe_write.reset();
366         execvp(argv[0], const_cast<char**>(argv.data()));
367         PLOG(ERROR) << "exec in ForkExecvp";
368         _exit(EXIT_FAILURE);
369     }
370     if (pid == -1) {
371         PLOG(ERROR) << "fork in ForkExecvp";
372         return -errno;
373     }
374 
375     pipe_write.reset();
376     auto st = ReadLinesFromFdAndLog(output, std::move(pipe_read));
377     if (st != 0) return st;
378 
379     int status;
380     if (waitpid(pid, &status, 0) == -1) {
381         PLOG(ERROR) << "waitpid in ForkExecvp";
382         return -errno;
383     }
384     if (!WIFEXITED(status)) {
385         LOG(ERROR) << "Process did not exit normally, status: " << status;
386         return -ECHILD;
387     }
388     if (WEXITSTATUS(status)) {
389         LOG(ERROR) << "Process exited with code: " << WEXITSTATUS(status);
390         return WEXITSTATUS(status);
391     }
392     return OK;
393 }
394 
ForkExecvpAsync(const std::vector<std::string> & args)395 pid_t ForkExecvpAsync(const std::vector<std::string>& args) {
396     auto argv = ConvertToArgv(args);
397 
398     pid_t pid = fork();
399     if (pid == 0) {
400         close(STDIN_FILENO);
401         close(STDOUT_FILENO);
402         close(STDERR_FILENO);
403 
404         execvp(argv[0], const_cast<char**>(argv.data()));
405         PLOG(ERROR) << "exec in ForkExecvpAsync";
406         _exit(EXIT_FAILURE);
407     }
408     if (pid == -1) {
409         PLOG(ERROR) << "fork in ForkExecvpAsync";
410         return -1;
411     }
412     return pid;
413 }
414 
ReadRandomBytes(size_t bytes,std::string & out)415 status_t ReadRandomBytes(size_t bytes, std::string& out) {
416     out.resize(bytes);
417     return ReadRandomBytes(bytes, &out[0]);
418 }
419 
ReadRandomBytes(size_t bytes,char * buf)420 status_t ReadRandomBytes(size_t bytes, char* buf) {
421     int fd = TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOFOLLOW));
422     if (fd == -1) {
423         return -errno;
424     }
425 
426     ssize_t n;
427     while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], bytes))) > 0) {
428         bytes -= n;
429         buf += n;
430     }
431     close(fd);
432 
433     if (bytes == 0) {
434         return OK;
435     } else {
436         return -EIO;
437     }
438 }
439 
GenerateRandomUuid(std::string & out)440 status_t GenerateRandomUuid(std::string& out) {
441     status_t res = ReadRandomBytes(16, out);
442     if (res == OK) {
443         out[6] &= 0x0f; /* clear version        */
444         out[6] |= 0x40; /* set to version 4     */
445         out[8] &= 0x3f; /* clear variant        */
446         out[8] |= 0x80; /* set to IETF variant  */
447     }
448     return res;
449 }
450 
HexToStr(const std::string & hex,std::string & str)451 status_t HexToStr(const std::string& hex, std::string& str) {
452     str.clear();
453     bool even = true;
454     char cur = 0;
455     for (size_t i = 0; i < hex.size(); i++) {
456         int val = 0;
457         switch (hex[i]) {
458             // clang-format off
459             case ' ': case '-': case ':': continue;
460             case 'f': case 'F': val = 15; break;
461             case 'e': case 'E': val = 14; break;
462             case 'd': case 'D': val = 13; break;
463             case 'c': case 'C': val = 12; break;
464             case 'b': case 'B': val = 11; break;
465             case 'a': case 'A': val = 10; break;
466             case '9': val = 9; break;
467             case '8': val = 8; break;
468             case '7': val = 7; break;
469             case '6': val = 6; break;
470             case '5': val = 5; break;
471             case '4': val = 4; break;
472             case '3': val = 3; break;
473             case '2': val = 2; break;
474             case '1': val = 1; break;
475             case '0': val = 0; break;
476             default: return -EINVAL;
477                 // clang-format on
478         }
479 
480         if (even) {
481             cur = val << 4;
482         } else {
483             cur += val;
484             str.push_back(cur);
485             cur = 0;
486         }
487         even = !even;
488     }
489     return even ? OK : -EINVAL;
490 }
491 
492 static const char* kLookup = "0123456789abcdef";
493 
StrToHex(const std::string & str,std::string & hex)494 status_t StrToHex(const std::string& str, std::string& hex) {
495     hex.clear();
496     for (size_t i = 0; i < str.size(); i++) {
497         hex.push_back(kLookup[(str[i] & 0xF0) >> 4]);
498         hex.push_back(kLookup[str[i] & 0x0F]);
499     }
500     return OK;
501 }
502 
StrToHex(const KeyBuffer & str,KeyBuffer & hex)503 status_t StrToHex(const KeyBuffer& str, KeyBuffer& hex) {
504     hex.clear();
505     for (size_t i = 0; i < str.size(); i++) {
506         hex.push_back(kLookup[(str.data()[i] & 0xF0) >> 4]);
507         hex.push_back(kLookup[str.data()[i] & 0x0F]);
508     }
509     return OK;
510 }
511 
NormalizeHex(const std::string & in,std::string & out)512 status_t NormalizeHex(const std::string& in, std::string& out) {
513     std::string tmp;
514     if (HexToStr(in, tmp)) {
515         return -EINVAL;
516     }
517     return StrToHex(tmp, out);
518 }
519 
GetBlockDevSize(int fd,uint64_t * size)520 status_t GetBlockDevSize(int fd, uint64_t* size) {
521     if (ioctl(fd, BLKGETSIZE64, size)) {
522         return -errno;
523     }
524 
525     return OK;
526 }
527 
GetBlockDevSize(const std::string & path,uint64_t * size)528 status_t GetBlockDevSize(const std::string& path, uint64_t* size) {
529     int fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
530     status_t res = OK;
531 
532     if (fd < 0) {
533         return -errno;
534     }
535 
536     res = GetBlockDevSize(fd, size);
537 
538     close(fd);
539 
540     return res;
541 }
542 
GetBlockDev512Sectors(const std::string & path,uint64_t * nr_sec)543 status_t GetBlockDev512Sectors(const std::string& path, uint64_t* nr_sec) {
544     uint64_t size;
545     status_t res = GetBlockDevSize(path, &size);
546 
547     if (res != OK) {
548         return res;
549     }
550 
551     *nr_sec = size / 512;
552 
553     return OK;
554 }
555 
GetFreeBytes(const std::string & path)556 uint64_t GetFreeBytes(const std::string& path) {
557     struct statvfs sb;
558     if (statvfs(path.c_str(), &sb) == 0) {
559         return (uint64_t)sb.f_bavail * sb.f_frsize;
560     } else {
561         return -1;
562     }
563 }
564 
565 // TODO: borrowed from frameworks/native/libs/diskusage/ which should
566 // eventually be migrated into system/
stat_size(struct stat * s)567 static int64_t stat_size(struct stat* s) {
568     int64_t blksize = s->st_blksize;
569     // count actual blocks used instead of nominal file size
570     int64_t size = s->st_blocks * 512;
571 
572     if (blksize) {
573         /* round up to filesystem block size */
574         size = (size + blksize - 1) & (~(blksize - 1));
575     }
576 
577     return size;
578 }
579 
580 // TODO: borrowed from frameworks/native/libs/diskusage/ which should
581 // eventually be migrated into system/
calculate_dir_size(int dfd)582 int64_t calculate_dir_size(int dfd) {
583     int64_t size = 0;
584     struct stat s;
585     DIR* d;
586     struct dirent* de;
587 
588     d = fdopendir(dfd);
589     if (d == NULL) {
590         close(dfd);
591         return 0;
592     }
593 
594     while ((de = readdir(d))) {
595         const char* name = de->d_name;
596         if (fstatat(dfd, name, &s, AT_SYMLINK_NOFOLLOW) == 0) {
597             size += stat_size(&s);
598         }
599         if (de->d_type == DT_DIR) {
600             int subfd;
601 
602             /* always skip "." and ".." */
603             if (name[0] == '.') {
604                 if (name[1] == 0) continue;
605                 if ((name[1] == '.') && (name[2] == 0)) continue;
606             }
607 
608             subfd = openat(dfd, name, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
609             if (subfd >= 0) {
610                 size += calculate_dir_size(subfd);
611             }
612         }
613     }
614     closedir(d);
615     return size;
616 }
617 
GetTreeBytes(const std::string & path)618 uint64_t GetTreeBytes(const std::string& path) {
619     int dirfd = open(path.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC);
620     if (dirfd < 0) {
621         PLOG(WARNING) << "Failed to open " << path;
622         return -1;
623     } else {
624         return calculate_dir_size(dirfd);
625     }
626 }
627 
IsFilesystemSupported(const std::string & fsType)628 bool IsFilesystemSupported(const std::string& fsType) {
629     std::string supported;
630     if (!ReadFileToString(kProcFilesystems, &supported)) {
631         PLOG(ERROR) << "Failed to read supported filesystems";
632         return false;
633     }
634     return supported.find(fsType + "\n") != std::string::npos;
635 }
636 
WipeBlockDevice(const std::string & path)637 status_t WipeBlockDevice(const std::string& path) {
638     status_t res = -1;
639     const char* c_path = path.c_str();
640     uint64_t range[2] = {0, 0};
641 
642     int fd = TEMP_FAILURE_RETRY(open(c_path, O_RDWR | O_CLOEXEC));
643     if (fd == -1) {
644         PLOG(ERROR) << "Failed to open " << path;
645         goto done;
646     }
647 
648     if (GetBlockDevSize(fd, &range[1]) != OK) {
649         PLOG(ERROR) << "Failed to determine size of " << path;
650         goto done;
651     }
652 
653     LOG(INFO) << "About to discard " << range[1] << " on " << path;
654     if (ioctl(fd, BLKDISCARD, &range) == 0) {
655         LOG(INFO) << "Discard success on " << path;
656         res = 0;
657     } else {
658         PLOG(ERROR) << "Discard failure on " << path;
659     }
660 
661 done:
662     close(fd);
663     return res;
664 }
665 
isValidFilename(const std::string & name)666 static bool isValidFilename(const std::string& name) {
667     if (name.empty() || (name == ".") || (name == "..") || (name.find('/') != std::string::npos)) {
668         return false;
669     } else {
670         return true;
671     }
672 }
673 
BuildKeyPath(const std::string & partGuid)674 std::string BuildKeyPath(const std::string& partGuid) {
675     return StringPrintf("%s/expand_%s.key", kKeyPath, partGuid.c_str());
676 }
677 
BuildDataSystemLegacyPath(userid_t userId)678 std::string BuildDataSystemLegacyPath(userid_t userId) {
679     return StringPrintf("%s/system/users/%u", BuildDataPath("").c_str(), userId);
680 }
681 
BuildDataSystemCePath(userid_t userId)682 std::string BuildDataSystemCePath(userid_t userId) {
683     return StringPrintf("%s/system_ce/%u", BuildDataPath("").c_str(), userId);
684 }
685 
BuildDataSystemDePath(userid_t userId)686 std::string BuildDataSystemDePath(userid_t userId) {
687     return StringPrintf("%s/system_de/%u", BuildDataPath("").c_str(), userId);
688 }
689 
BuildDataMiscLegacyPath(userid_t userId)690 std::string BuildDataMiscLegacyPath(userid_t userId) {
691     return StringPrintf("%s/misc/user/%u", BuildDataPath("").c_str(), userId);
692 }
693 
BuildDataMiscCePath(userid_t userId)694 std::string BuildDataMiscCePath(userid_t userId) {
695     return StringPrintf("%s/misc_ce/%u", BuildDataPath("").c_str(), userId);
696 }
697 
BuildDataMiscDePath(userid_t userId)698 std::string BuildDataMiscDePath(userid_t userId) {
699     return StringPrintf("%s/misc_de/%u", BuildDataPath("").c_str(), userId);
700 }
701 
702 // Keep in sync with installd (frameworks/native/cmds/installd/utils.h)
BuildDataProfilesDePath(userid_t userId)703 std::string BuildDataProfilesDePath(userid_t userId) {
704     return StringPrintf("%s/misc/profiles/cur/%u", BuildDataPath("").c_str(), userId);
705 }
706 
BuildDataVendorCePath(userid_t userId)707 std::string BuildDataVendorCePath(userid_t userId) {
708     return StringPrintf("%s/vendor_ce/%u", BuildDataPath("").c_str(), userId);
709 }
710 
BuildDataVendorDePath(userid_t userId)711 std::string BuildDataVendorDePath(userid_t userId) {
712     return StringPrintf("%s/vendor_de/%u", BuildDataPath("").c_str(), userId);
713 }
714 
BuildDataPath(const std::string & volumeUuid)715 std::string BuildDataPath(const std::string& volumeUuid) {
716     // TODO: unify with installd path generation logic
717     if (volumeUuid.empty()) {
718         return "/data";
719     } else {
720         CHECK(isValidFilename(volumeUuid));
721         return StringPrintf("/mnt/expand/%s", volumeUuid.c_str());
722     }
723 }
724 
BuildDataMediaCePath(const std::string & volumeUuid,userid_t userId)725 std::string BuildDataMediaCePath(const std::string& volumeUuid, userid_t userId) {
726     // TODO: unify with installd path generation logic
727     std::string data(BuildDataPath(volumeUuid));
728     return StringPrintf("%s/media/%u", data.c_str(), userId);
729 }
730 
BuildDataUserCePath(const std::string & volumeUuid,userid_t userId)731 std::string BuildDataUserCePath(const std::string& volumeUuid, userid_t userId) {
732     // TODO: unify with installd path generation logic
733     std::string data(BuildDataPath(volumeUuid));
734     if (volumeUuid.empty() && userId == 0) {
735         std::string legacy = StringPrintf("%s/data", data.c_str());
736         struct stat sb;
737         if (lstat(legacy.c_str(), &sb) == 0 && S_ISDIR(sb.st_mode)) {
738             /* /data/data is dir, return /data/data for legacy system */
739             return legacy;
740         }
741     }
742     return StringPrintf("%s/user/%u", data.c_str(), userId);
743 }
744 
BuildDataUserDePath(const std::string & volumeUuid,userid_t userId)745 std::string BuildDataUserDePath(const std::string& volumeUuid, userid_t userId) {
746     // TODO: unify with installd path generation logic
747     std::string data(BuildDataPath(volumeUuid));
748     return StringPrintf("%s/user_de/%u", data.c_str(), userId);
749 }
750 
GetDevice(const std::string & path)751 dev_t GetDevice(const std::string& path) {
752     struct stat sb;
753     if (stat(path.c_str(), &sb)) {
754         PLOG(WARNING) << "Failed to stat " << path;
755         return 0;
756     } else {
757         return sb.st_dev;
758     }
759 }
760 
RestoreconRecursive(const std::string & path)761 status_t RestoreconRecursive(const std::string& path) {
762     LOG(DEBUG) << "Starting restorecon of " << path;
763 
764     static constexpr const char* kRestoreconString = "selinux.restorecon_recursive";
765 
766     android::base::SetProperty(kRestoreconString, "");
767     android::base::SetProperty(kRestoreconString, path);
768 
769     android::base::WaitForProperty(kRestoreconString, path);
770 
771     LOG(DEBUG) << "Finished restorecon of " << path;
772     return OK;
773 }
774 
Readlinkat(int dirfd,const std::string & path,std::string * result)775 bool Readlinkat(int dirfd, const std::string& path, std::string* result) {
776     // Shamelessly borrowed from android::base::Readlink()
777     result->clear();
778 
779     // Most Linux file systems (ext2 and ext4, say) limit symbolic links to
780     // 4095 bytes. Since we'll copy out into the string anyway, it doesn't
781     // waste memory to just start there. We add 1 so that we can recognize
782     // whether it actually fit (rather than being truncated to 4095).
783     std::vector<char> buf(4095 + 1);
784     while (true) {
785         ssize_t size = readlinkat(dirfd, path.c_str(), &buf[0], buf.size());
786         // Unrecoverable error?
787         if (size == -1) return false;
788         // It fit! (If size == buf.size(), it may have been truncated.)
789         if (static_cast<size_t>(size) < buf.size()) {
790             result->assign(&buf[0], size);
791             return true;
792         }
793         // Double our buffer and try again.
794         buf.resize(buf.size() * 2);
795     }
796 }
797 
IsRunningInEmulator()798 bool IsRunningInEmulator() {
799     return android::base::GetBoolProperty("ro.kernel.qemu", false);
800 }
801 
findMountPointsWithPrefix(const std::string & prefix,std::list<std::string> & mountPoints)802 static status_t findMountPointsWithPrefix(const std::string& prefix,
803                                           std::list<std::string>& mountPoints) {
804     // Add a trailing slash if the client didn't provide one so that we don't match /foo/barbaz
805     // when the prefix is /foo/bar
806     std::string prefixWithSlash(prefix);
807     if (prefix.back() != '/') {
808         android::base::StringAppendF(&prefixWithSlash, "/");
809     }
810 
811     std::unique_ptr<FILE, int (*)(FILE*)> mnts(setmntent("/proc/mounts", "re"), endmntent);
812     if (!mnts) {
813         PLOG(ERROR) << "Unable to open /proc/mounts";
814         return -errno;
815     }
816 
817     // Some volumes can be stacked on each other, so force unmount in
818     // reverse order to give us the best chance of success.
819     struct mntent* mnt;  // getmntent returns a thread local, so it's safe.
820     while ((mnt = getmntent(mnts.get())) != nullptr) {
821         auto mountPoint = std::string(mnt->mnt_dir) + "/";
822         if (android::base::StartsWith(mountPoint, prefixWithSlash)) {
823             mountPoints.push_front(mountPoint);
824         }
825     }
826     return OK;
827 }
828 
829 // Unmount all mountpoints that start with prefix. prefix itself doesn't need to be a mountpoint.
UnmountTreeWithPrefix(const std::string & prefix)830 status_t UnmountTreeWithPrefix(const std::string& prefix) {
831     std::list<std::string> toUnmount;
832     status_t result = findMountPointsWithPrefix(prefix, toUnmount);
833     if (result < 0) {
834         return result;
835     }
836     for (const auto& path : toUnmount) {
837         if (umount2(path.c_str(), MNT_DETACH)) {
838             PLOG(ERROR) << "Failed to unmount " << path;
839             result = -errno;
840         }
841     }
842     return result;
843 }
844 
UnmountTree(const std::string & mountPoint)845 status_t UnmountTree(const std::string& mountPoint) {
846     if (TEMP_FAILURE_RETRY(umount2(mountPoint.c_str(), MNT_DETACH)) < 0 && errno != EINVAL &&
847         errno != ENOENT) {
848         PLOG(ERROR) << "Failed to unmount " << mountPoint;
849         return -errno;
850     }
851     return OK;
852 }
853 
delete_dir_contents(DIR * dir)854 static status_t delete_dir_contents(DIR* dir) {
855     // Shamelessly borrowed from android::installd
856     int dfd = dirfd(dir);
857     if (dfd < 0) {
858         return -errno;
859     }
860 
861     status_t result = OK;
862     struct dirent* de;
863     while ((de = readdir(dir))) {
864         const char* name = de->d_name;
865         if (de->d_type == DT_DIR) {
866             /* always skip "." and ".." */
867             if (name[0] == '.') {
868                 if (name[1] == 0) continue;
869                 if ((name[1] == '.') && (name[2] == 0)) continue;
870             }
871 
872             android::base::unique_fd subfd(
873                 openat(dfd, name, O_RDONLY | O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC));
874             if (subfd.get() == -1) {
875                 PLOG(ERROR) << "Couldn't openat " << name;
876                 result = -errno;
877                 continue;
878             }
879             std::unique_ptr<DIR, decltype(&closedir)> subdirp(
880                 android::base::Fdopendir(std::move(subfd)), closedir);
881             if (!subdirp) {
882                 PLOG(ERROR) << "Couldn't fdopendir " << name;
883                 result = -errno;
884                 continue;
885             }
886             result = delete_dir_contents(subdirp.get());
887             if (unlinkat(dfd, name, AT_REMOVEDIR) < 0) {
888                 PLOG(ERROR) << "Couldn't unlinkat " << name;
889                 result = -errno;
890             }
891         } else {
892             if (unlinkat(dfd, name, 0) < 0) {
893                 PLOG(ERROR) << "Couldn't unlinkat " << name;
894                 result = -errno;
895             }
896         }
897     }
898     return result;
899 }
900 
DeleteDirContentsAndDir(const std::string & pathname)901 status_t DeleteDirContentsAndDir(const std::string& pathname) {
902     status_t res = DeleteDirContents(pathname);
903     if (res < 0) {
904         return res;
905     }
906     if (TEMP_FAILURE_RETRY(rmdir(pathname.c_str())) < 0 && errno != ENOENT) {
907         PLOG(ERROR) << "rmdir failed on " << pathname;
908         return -errno;
909     }
910     LOG(VERBOSE) << "Success: rmdir on " << pathname;
911     return OK;
912 }
913 
DeleteDirContents(const std::string & pathname)914 status_t DeleteDirContents(const std::string& pathname) {
915     // Shamelessly borrowed from android::installd
916     std::unique_ptr<DIR, decltype(&closedir)> dirp(opendir(pathname.c_str()), closedir);
917     if (!dirp) {
918         if (errno == ENOENT) {
919             return OK;
920         }
921         PLOG(ERROR) << "Failed to opendir " << pathname;
922         return -errno;
923     }
924     return delete_dir_contents(dirp.get());
925 }
926 
927 // TODO(118708649): fix duplication with init/util.h
WaitForFile(const char * filename,std::chrono::nanoseconds timeout)928 status_t WaitForFile(const char* filename, std::chrono::nanoseconds timeout) {
929     android::base::Timer t;
930     while (t.duration() < timeout) {
931         struct stat sb;
932         if (stat(filename, &sb) != -1) {
933             LOG(INFO) << "wait for '" << filename << "' took " << t;
934             return 0;
935         }
936         std::this_thread::sleep_for(10ms);
937     }
938     LOG(WARNING) << "wait for '" << filename << "' timed out and took " << t;
939     return -1;
940 }
941 
FsyncDirectory(const std::string & dirname)942 bool FsyncDirectory(const std::string& dirname) {
943     android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(dirname.c_str(), O_RDONLY | O_CLOEXEC)));
944     if (fd == -1) {
945         PLOG(ERROR) << "Failed to open " << dirname;
946         return false;
947     }
948     if (fsync(fd) == -1) {
949         if (errno == EROFS || errno == EINVAL) {
950             PLOG(WARNING) << "Skip fsync " << dirname
951                           << " on a file system does not support synchronization";
952         } else {
953             PLOG(ERROR) << "Failed to fsync " << dirname;
954             return false;
955         }
956     }
957     return true;
958 }
959 
writeStringToFile(const std::string & payload,const std::string & filename)960 bool writeStringToFile(const std::string& payload, const std::string& filename) {
961     android::base::unique_fd fd(TEMP_FAILURE_RETRY(
962         open(filename.c_str(), O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0666)));
963     if (fd == -1) {
964         PLOG(ERROR) << "Failed to open " << filename;
965         return false;
966     }
967     if (!android::base::WriteStringToFd(payload, fd)) {
968         PLOG(ERROR) << "Failed to write to " << filename;
969         unlink(filename.c_str());
970         return false;
971     }
972     // fsync as close won't guarantee flush data
973     // see close(2), fsync(2) and b/68901441
974     if (fsync(fd) == -1) {
975         if (errno == EROFS || errno == EINVAL) {
976             PLOG(WARNING) << "Skip fsync " << filename
977                           << " on a file system does not support synchronization";
978         } else {
979             PLOG(ERROR) << "Failed to fsync " << filename;
980             unlink(filename.c_str());
981             return false;
982         }
983     }
984     return true;
985 }
986 
987 }  // namespace vold
988 }  // namespace android
989