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platform_system_vold/Utils.cpp

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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "Utils.h"
#include "Process.h"
#include "sehandle.h"
#include <android-base/chrono_utils.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <cutils/fs.h>
#include <logwrap/logwrap.h>
#include <private/android_filesystem_config.h>
#include <private/android_projectid_config.h>
#include <dirent.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <mntent.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/xattr.h>
#include <unistd.h>
#include <filesystem>
#include <list>
#include <mutex>
#include <regex>
#include <thread>
#ifndef UMOUNT_NOFOLLOW
#define UMOUNT_NOFOLLOW 0x00000008 /* Don't follow symlink on umount */
#endif
using namespace std::chrono_literals;
using android::base::EndsWith;
using android::base::ReadFileToString;
using android::base::StartsWith;
using android::base::StringPrintf;
using android::base::unique_fd;
namespace android {
namespace vold {
char* sBlkidContext = nullptr;
char* sBlkidUntrustedContext = nullptr;
char* sFsckContext = nullptr;
char* sFsckUntrustedContext = nullptr;
bool sSleepOnUnmount = true;
static const char* kBlkidPath = "/system/bin/blkid";
static const char* kKeyPath = "/data/misc/vold";
static const char* kProcDevices = "/proc/devices";
static const char* kProcFilesystems = "/proc/filesystems";
static const char* kAndroidDir = "/Android/";
static const char* kAppDataDir = "/Android/data/";
static const char* kAppMediaDir = "/Android/media/";
static const char* kAppObbDir = "/Android/obb/";
static const char* kMediaProviderCtx = "u:r:mediaprovider:";
static const char* kMediaProviderAppCtx = "u:r:mediaprovider_app:";
// Lock used to protect process-level SELinux changes from racing with each
// other between multiple threads.
static std::mutex kSecurityLock;
std::string GetFuseMountPathForUser(userid_t user_id, const std::string& relative_upper_path) {
return StringPrintf("/mnt/user/%d/%s", user_id, relative_upper_path.c_str());
}
status_t CreateDeviceNode(const std::string& path, dev_t dev) {
std::lock_guard<std::mutex> lock(kSecurityLock);
const char* cpath = path.c_str();
status_t res = 0;
char* secontext = nullptr;
if (sehandle) {
if (!selabel_lookup(sehandle, &secontext, cpath, S_IFBLK)) {
setfscreatecon(secontext);
}
}
mode_t mode = 0660 | S_IFBLK;
if (mknod(cpath, mode, dev) < 0) {
if (errno != EEXIST) {
PLOG(ERROR) << "Failed to create device node for " << major(dev) << ":" << minor(dev)
<< " at " << path;
res = -errno;
}
}
if (secontext) {
setfscreatecon(nullptr);
freecon(secontext);
}
return res;
}
status_t DestroyDeviceNode(const std::string& path) {
const char* cpath = path.c_str();
if (TEMP_FAILURE_RETRY(unlink(cpath))) {
return -errno;
} else {
return OK;
}
}
// Sets a default ACL on the directory.
status_t SetDefaultAcl(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
std::vector<gid_t> additionalGids) {
if (IsSdcardfsUsed()) {
// sdcardfs magically takes care of this
return OK;
}
size_t num_entries = 3 + (additionalGids.size() > 0 ? additionalGids.size() + 1 : 0);
size_t size = sizeof(posix_acl_xattr_header) + num_entries * sizeof(posix_acl_xattr_entry);
auto buf = std::make_unique<uint8_t[]>(size);
posix_acl_xattr_header* acl_header = reinterpret_cast<posix_acl_xattr_header*>(buf.get());
acl_header->a_version = POSIX_ACL_XATTR_VERSION;
posix_acl_xattr_entry* entry =
reinterpret_cast<posix_acl_xattr_entry*>(buf.get() + sizeof(posix_acl_xattr_header));
int tag_index = 0;
entry[tag_index].e_tag = ACL_USER_OBJ;
// The existing mode_t mask has the ACL in the lower 9 bits:
// the lowest 3 for "other", the next 3 the group, the next 3 for the owner
// Use the mode_t masks to get these bits out, and shift them to get the
// correct value per entity.
//
// Eg if mode_t = 0700, rwx for the owner, then & S_IRWXU >> 6 results in 7
entry[tag_index].e_perm = (mode & S_IRWXU) >> 6;
entry[tag_index].e_id = uid;
tag_index++;
entry[tag_index].e_tag = ACL_GROUP_OBJ;
entry[tag_index].e_perm = (mode & S_IRWXG) >> 3;
entry[tag_index].e_id = gid;
tag_index++;
if (additionalGids.size() > 0) {
for (gid_t additional_gid : additionalGids) {
entry[tag_index].e_tag = ACL_GROUP;
entry[tag_index].e_perm = (mode & S_IRWXG) >> 3;
entry[tag_index].e_id = additional_gid;
tag_index++;
}
entry[tag_index].e_tag = ACL_MASK;
entry[tag_index].e_perm = (mode & S_IRWXG) >> 3;
entry[tag_index].e_id = 0;
tag_index++;
}
entry[tag_index].e_tag = ACL_OTHER;
entry[tag_index].e_perm = mode & S_IRWXO;
entry[tag_index].e_id = 0;
int ret = setxattr(path.c_str(), XATTR_NAME_POSIX_ACL_DEFAULT, acl_header, size, 0);
if (ret != 0) {
PLOG(ERROR) << "Failed to set default ACL on " << path;
}
return ret;
}
int SetQuotaInherit(const std::string& path) {
unsigned int flags;
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC)));
if (fd == -1) {
PLOG(ERROR) << "Failed to open " << path << " to set project id inheritance.";
return -1;
}
int ret = ioctl(fd, FS_IOC_GETFLAGS, &flags);
if (ret == -1) {
PLOG(ERROR) << "Failed to get flags for " << path << " to set project id inheritance.";
return ret;
}
flags |= FS_PROJINHERIT_FL;
ret = ioctl(fd, FS_IOC_SETFLAGS, &flags);
if (ret == -1) {
PLOG(ERROR) << "Failed to set flags for " << path << " to set project id inheritance.";
return ret;
}
return 0;
}
int SetQuotaProjectId(const std::string& path, long projectId) {
struct fsxattr fsx;
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC)));
if (fd == -1) {
PLOG(ERROR) << "Failed to open " << path << " to set project id.";
return -1;
}
int ret = ioctl(fd, FS_IOC_FSGETXATTR, &fsx);
if (ret == -1) {
PLOG(ERROR) << "Failed to get extended attributes for " << path << " to get project id.";
return ret;
}
fsx.fsx_projid = projectId;
ret = ioctl(fd, FS_IOC_FSSETXATTR, &fsx);
if (ret == -1) {
PLOG(ERROR) << "Failed to set project id on " << path;
return ret;
}
return 0;
}
int PrepareDirWithProjectId(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
long projectId) {
int ret = fs_prepare_dir(path.c_str(), mode, uid, gid);
if (ret != 0) {
return ret;
}
if (!IsSdcardfsUsed()) {
ret = SetQuotaProjectId(path, projectId);
}
return ret;
}
static int FixupAppDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid, long projectId) {
namespace fs = std::filesystem;
// Setup the directory itself correctly
int ret = PrepareDirWithProjectId(path, mode, uid, gid, projectId);
if (ret != OK) {
return ret;
}
// Fixup all of its file entries
for (const auto& itEntry : fs::directory_iterator(path)) {
ret = lchown(itEntry.path().c_str(), uid, gid);
if (ret != 0) {
return ret;
}
ret = chmod(itEntry.path().c_str(), mode);
if (ret != 0) {
return ret;
}
if (!IsSdcardfsUsed()) {
ret = SetQuotaProjectId(itEntry.path(), projectId);
if (ret != 0) {
return ret;
}
}
}
return OK;
}
int PrepareAppDirFromRoot(const std::string& path, const std::string& root, int appUid,
bool fixupExisting) {
long projectId;
size_t pos;
int ret = 0;
bool sdcardfsSupport = IsSdcardfsUsed();
// Make sure the Android/ directories exist and are setup correctly
ret = PrepareAndroidDirs(root);
if (ret != 0) {
LOG(ERROR) << "Failed to prepare Android/ directories.";
return ret;
}
// Now create the application-specific subdir(s)
// path is something like /data/media/0/Android/data/com.foo/files
// First, chop off the volume root, eg /data/media/0
std::string pathFromRoot = path.substr(root.length());
uid_t uid = appUid;
gid_t gid = AID_MEDIA_RW;
std::vector<gid_t> additionalGids;
std::string appDir;
// Check that the next part matches one of the allowed Android/ dirs
if (StartsWith(pathFromRoot, kAppDataDir)) {
appDir = kAppDataDir;
if (!sdcardfsSupport) {
gid = AID_EXT_DATA_RW;
// Also add the app's own UID as a group; since apps belong to a group
// that matches their UID, this ensures that they will always have access to
// the files created in these dirs, even if they are created by other processes
additionalGids.push_back(uid);
}
} else if (StartsWith(pathFromRoot, kAppMediaDir)) {
appDir = kAppMediaDir;
if (!sdcardfsSupport) {
gid = AID_MEDIA_RW;
}
} else if (StartsWith(pathFromRoot, kAppObbDir)) {
appDir = kAppObbDir;
if (!sdcardfsSupport) {
gid = AID_EXT_OBB_RW;
// See comments for kAppDataDir above
additionalGids.push_back(uid);
}
} else {
LOG(ERROR) << "Invalid application directory: " << path;
return -EINVAL;
}
// mode = 770, plus sticky bit on directory to inherit GID when apps
// create subdirs
mode_t mode = S_IRWXU | S_IRWXG | S_ISGID;
// the project ID for application-specific directories is directly
// derived from their uid
// Chop off the generic application-specific part, eg /Android/data/
// this leaves us with something like com.foo/files/
std::string leftToCreate = pathFromRoot.substr(appDir.length());
if (!EndsWith(leftToCreate, "/")) {
leftToCreate += "/";
}
std::string pathToCreate = root + appDir;
int depth = 0;
// Derive initial project ID
if (appDir == kAppDataDir || appDir == kAppMediaDir) {
projectId = uid - AID_APP_START + PROJECT_ID_EXT_DATA_START;
} else if (appDir == kAppObbDir) {
projectId = uid - AID_APP_START + PROJECT_ID_EXT_OBB_START;
}
while ((pos = leftToCreate.find('/')) != std::string::npos) {
std::string component = leftToCreate.substr(0, pos + 1);
leftToCreate = leftToCreate.erase(0, pos + 1);
pathToCreate = pathToCreate + component;
if (appDir == kAppDataDir && depth == 1 && component == "cache/") {
// All dirs use the "app" project ID, except for the cache dirs in
// Android/data, eg Android/data/com.foo/cache
// Note that this "sticks" - eg subdirs of this dir need the same
// project ID.
projectId = uid - AID_APP_START + PROJECT_ID_EXT_CACHE_START;
}
if (fixupExisting && access(pathToCreate.c_str(), F_OK) == 0) {
// Fixup all files in this existing directory with the correct UID/GID
// and project ID.
ret = FixupAppDir(pathToCreate, mode, uid, gid, projectId);
} else {
ret = PrepareDirWithProjectId(pathToCreate, mode, uid, gid, projectId);
}
if (ret != 0) {
return ret;
}
if (depth == 0) {
// Set the default ACL on the top-level application-specific directories,
// to ensure that even if applications run with a umask of 0077,
// new directories within these directories will allow the GID
// specified here to write; this is necessary for apps like
// installers and MTP, that require access here.
//
// See man (5) acl for more details.
ret = SetDefaultAcl(pathToCreate, mode, uid, gid, additionalGids);
if (ret != 0) {
return ret;
}
if (!sdcardfsSupport) {
// Set project ID inheritance, so that future subdirectories inherit the
// same project ID
ret = SetQuotaInherit(pathToCreate);
if (ret != 0) {
return ret;
}
}
}
depth++;
}
return OK;
}
int SetAttrs(const std::string& path, unsigned int attrs) {
unsigned int flags;
android::base::unique_fd fd(
TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_NONBLOCK | O_CLOEXEC)));
if (fd == -1) {
PLOG(ERROR) << "Failed to open " << path;
return -1;
}
if (ioctl(fd, FS_IOC_GETFLAGS, &flags)) {
PLOG(ERROR) << "Failed to get flags for " << path;
return -1;
}
if ((flags & attrs) == attrs) return 0;
flags |= attrs;
if (ioctl(fd, FS_IOC_SETFLAGS, &flags)) {
PLOG(ERROR) << "Failed to set flags for " << path << "(0x" << std::hex << attrs << ")";
return -1;
}
return 0;
}
status_t PrepareDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
unsigned int attrs) {
std::lock_guard<std::mutex> lock(kSecurityLock);
const char* cpath = path.c_str();
char* secontext = nullptr;
if (sehandle) {
if (!selabel_lookup(sehandle, &secontext, cpath, S_IFDIR)) {
setfscreatecon(secontext);
}
}
int res = fs_prepare_dir(cpath, mode, uid, gid);
if (secontext) {
setfscreatecon(nullptr);
freecon(secontext);
}
if (res) return -errno;
if (attrs) res = SetAttrs(path, attrs);
if (res == 0) {
return OK;
} else {
return -errno;
}
}
status_t ForceUnmount(const std::string& path) {
const char* cpath = path.c_str();
if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
return OK;
}
// Apps might still be handling eject request, so wait before
// we start sending signals
if (sSleepOnUnmount) sleep(5);
KillProcessesWithOpenFiles(path, SIGINT);
if (sSleepOnUnmount) sleep(5);
if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
return OK;
}
KillProcessesWithOpenFiles(path, SIGTERM);
if (sSleepOnUnmount) sleep(5);
if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
return OK;
}
KillProcessesWithOpenFiles(path, SIGKILL);
if (sSleepOnUnmount) sleep(5);
if (!umount2(cpath, UMOUNT_NOFOLLOW) || errno == EINVAL || errno == ENOENT) {
return OK;
}
PLOG(INFO) << "ForceUnmount failed";
return -errno;
}
status_t KillProcessesWithTmpfsMountPrefix(const std::string& path) {
if (KillProcessesWithTmpfsMounts(path, SIGINT) == 0) {
return OK;
}
if (sSleepOnUnmount) sleep(5);
if (KillProcessesWithTmpfsMounts(path, SIGTERM) == 0) {
return OK;
}
if (sSleepOnUnmount) sleep(5);
if (KillProcessesWithTmpfsMounts(path, SIGKILL) == 0) {
return OK;
}
if (sSleepOnUnmount) sleep(5);
// Send SIGKILL a second time to determine if we've
// actually killed everyone mount
if (KillProcessesWithTmpfsMounts(path, SIGKILL) == 0) {
return OK;
}
PLOG(ERROR) << "Failed to kill processes using " << path;
return -EBUSY;
}
status_t KillProcessesUsingPath(const std::string& path) {
if (KillProcessesWithOpenFiles(path, SIGINT, false /* killFuseDaemon */) == 0) {
return OK;
}
if (sSleepOnUnmount) sleep(5);
if (KillProcessesWithOpenFiles(path, SIGTERM, false /* killFuseDaemon */) == 0) {
return OK;
}
if (sSleepOnUnmount) sleep(5);
if (KillProcessesWithOpenFiles(path, SIGKILL, false /* killFuseDaemon */) == 0) {
return OK;
}
if (sSleepOnUnmount) sleep(5);
// Send SIGKILL a second time to determine if we've
// actually killed everyone with open files
// This time, we also kill the FUSE daemon if found
if (KillProcessesWithOpenFiles(path, SIGKILL, true /* killFuseDaemon */) == 0) {
return OK;
}
PLOG(ERROR) << "Failed to kill processes using " << path;
return -EBUSY;
}
status_t BindMount(const std::string& source, const std::string& target) {
if (UnmountTree(target) < 0) {
return -errno;
}
if (TEMP_FAILURE_RETRY(mount(source.c_str(), target.c_str(), nullptr, MS_BIND, nullptr)) < 0) {
PLOG(ERROR) << "Failed to bind mount " << source << " to " << target;
return -errno;
}
return OK;
}
status_t Symlink(const std::string& target, const std::string& linkpath) {
if (Unlink(linkpath) < 0) {
return -errno;
}
if (TEMP_FAILURE_RETRY(symlink(target.c_str(), linkpath.c_str())) < 0) {
PLOG(ERROR) << "Failed to create symlink " << linkpath << " to " << target;
return -errno;
}
return OK;
}
status_t Unlink(const std::string& linkpath) {
if (TEMP_FAILURE_RETRY(unlink(linkpath.c_str())) < 0 && errno != EINVAL && errno != ENOENT) {
PLOG(ERROR) << "Failed to unlink " << linkpath;
return -errno;
}
return OK;
}
status_t CreateDir(const std::string& dir, mode_t mode) {
struct stat sb;
if (TEMP_FAILURE_RETRY(stat(dir.c_str(), &sb)) == 0) {
if (S_ISDIR(sb.st_mode)) {
return OK;
} else if (TEMP_FAILURE_RETRY(unlink(dir.c_str())) == -1) {
PLOG(ERROR) << "Failed to unlink " << dir;
return -errno;
}
} else if (errno != ENOENT) {
PLOG(ERROR) << "Failed to stat " << dir;
return -errno;
}
if (TEMP_FAILURE_RETRY(mkdir(dir.c_str(), mode)) == -1 && errno != EEXIST) {
PLOG(ERROR) << "Failed to mkdir " << dir;
return -errno;
}
return OK;
}
bool FindValue(const std::string& raw, const std::string& key, std::string* value) {
auto qual = key + "=\"";
size_t start = 0;
while (true) {
start = raw.find(qual, start);
if (start == std::string::npos) return false;
if (start == 0 || raw[start - 1] == ' ') {
break;
}
start += 1;
}
start += qual.length();
auto end = raw.find("\"", start);
if (end == std::string::npos) return false;
*value = raw.substr(start, end - start);
return true;
}
static status_t readMetadata(const std::string& path, std::string* fsType, std::string* fsUuid,
std::string* fsLabel, bool untrusted) {
fsType->clear();
fsUuid->clear();
fsLabel->clear();
std::vector<std::string> cmd;
cmd.push_back(kBlkidPath);
cmd.push_back("-c");
cmd.push_back("/dev/null");
cmd.push_back("-s");
cmd.push_back("TYPE");
cmd.push_back("-s");
cmd.push_back("UUID");
cmd.push_back("-s");
cmd.push_back("LABEL");
cmd.push_back(path);
std::vector<std::string> output;
status_t res = ForkExecvp(cmd, &output, untrusted ? sBlkidUntrustedContext : sBlkidContext);
if (res != OK) {
LOG(WARNING) << "blkid failed to identify " << path;
return res;
}
for (const auto& line : output) {
// Extract values from blkid output, if defined
FindValue(line, "TYPE", fsType);
FindValue(line, "UUID", fsUuid);
FindValue(line, "LABEL", fsLabel);
}
return OK;
}
status_t ReadMetadata(const std::string& path, std::string* fsType, std::string* fsUuid,
std::string* fsLabel) {
return readMetadata(path, fsType, fsUuid, fsLabel, false);
}
status_t ReadMetadataUntrusted(const std::string& path, std::string* fsType, std::string* fsUuid,
std::string* fsLabel) {
return readMetadata(path, fsType, fsUuid, fsLabel, true);
}
static std::vector<const char*> ConvertToArgv(const std::vector<std::string>& args) {
std::vector<const char*> argv;
argv.reserve(args.size() + 1);
for (const auto& arg : args) {
if (argv.empty()) {
LOG(DEBUG) << arg;
} else {
LOG(DEBUG) << " " << arg;
}
argv.emplace_back(arg.data());
}
argv.emplace_back(nullptr);
return argv;
}
static status_t ReadLinesFromFdAndLog(std::vector<std::string>* output,
android::base::unique_fd ufd) {
std::unique_ptr<FILE, int (*)(FILE*)> fp(android::base::Fdopen(std::move(ufd), "r"), fclose);
if (!fp) {
PLOG(ERROR) << "fdopen in ReadLinesFromFdAndLog";
return -errno;
}
if (output) output->clear();
char line[1024];
while (fgets(line, sizeof(line), fp.get()) != nullptr) {
LOG(DEBUG) << line;
if (output) output->emplace_back(line);
}
return OK;
}
status_t ForkExecvp(const std::vector<std::string>& args, std::vector<std::string>* output,
char* context) {
auto argv = ConvertToArgv(args);
android::base::unique_fd pipe_read, pipe_write;
if (!android::base::Pipe(&pipe_read, &pipe_write)) {
PLOG(ERROR) << "Pipe in ForkExecvp";
return -errno;
}
pid_t pid = fork();
if (pid == 0) {
if (context) {
if (setexeccon(context)) {
LOG(ERROR) << "Failed to setexeccon in ForkExecvp";
abort();
}
}
pipe_read.reset();
if (dup2(pipe_write.get(), STDOUT_FILENO) == -1) {
PLOG(ERROR) << "dup2 in ForkExecvp";
_exit(EXIT_FAILURE);
}
pipe_write.reset();
execvp(argv[0], const_cast<char**>(argv.data()));
PLOG(ERROR) << "exec in ForkExecvp";
_exit(EXIT_FAILURE);
}
if (pid == -1) {
PLOG(ERROR) << "fork in ForkExecvp";
return -errno;
}
pipe_write.reset();
auto st = ReadLinesFromFdAndLog(output, std::move(pipe_read));
if (st != 0) return st;
int status;
if (waitpid(pid, &status, 0) == -1) {
PLOG(ERROR) << "waitpid in ForkExecvp";
return -errno;
}
if (!WIFEXITED(status)) {
LOG(ERROR) << "Process did not exit normally, status: " << status;
return -ECHILD;
}
if (WEXITSTATUS(status)) {
LOG(ERROR) << "Process exited with code: " << WEXITSTATUS(status);
return WEXITSTATUS(status);
}
return OK;
}
status_t ForkExecvpTimeout(const std::vector<std::string>& args, std::chrono::seconds timeout,
char* context) {
int status;
pid_t wait_timeout_pid = fork();
if (wait_timeout_pid == 0) {
pid_t pid = ForkExecvpAsync(args, context);
if (pid == -1) {
_exit(EXIT_FAILURE);
}
pid_t timer_pid = fork();
if (timer_pid == 0) {
sleep(timeout.count());
_exit(ETIMEDOUT);
}
if (timer_pid == -1) {
PLOG(ERROR) << "fork in ForkExecvpAsync_timeout";
kill(pid, SIGTERM);
_exit(EXIT_FAILURE);
}
pid_t finished = wait(&status);
if (finished == pid) {
kill(timer_pid, SIGTERM);
} else {
kill(pid, SIGTERM);
}
if (!WIFEXITED(status)) {
_exit(ECHILD);
}
_exit(WEXITSTATUS(status));
}
if (waitpid(wait_timeout_pid, &status, 0) == -1) {
PLOG(ERROR) << "waitpid in ForkExecvpAsync_timeout";
return -errno;
}
if (!WIFEXITED(status)) {
LOG(ERROR) << "Process did not exit normally, status: " << status;
return -ECHILD;
}
if (WEXITSTATUS(status)) {
LOG(ERROR) << "Process exited with code: " << WEXITSTATUS(status);
return WEXITSTATUS(status);
}
return OK;
}
pid_t ForkExecvpAsync(const std::vector<std::string>& args, char* context) {
auto argv = ConvertToArgv(args);
pid_t pid = fork();
if (pid == 0) {
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
if (context) {
if (setexeccon(context)) {
LOG(ERROR) << "Failed to setexeccon in ForkExecvpAsync";
abort();
}
}
execvp(argv[0], const_cast<char**>(argv.data()));
PLOG(ERROR) << "exec in ForkExecvpAsync";
_exit(EXIT_FAILURE);
}
if (pid == -1) {
PLOG(ERROR) << "fork in ForkExecvpAsync";
return -1;
}
return pid;
}
status_t ReadRandomBytes(size_t bytes, std::string& out) {
out.resize(bytes);
return ReadRandomBytes(bytes, &out[0]);
}
status_t ReadRandomBytes(size_t bytes, char* buf) {
int fd = TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOFOLLOW));
if (fd == -1) {
return -errno;
}
ssize_t n;
while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], bytes))) > 0) {
bytes -= n;
buf += n;
}
close(fd);
if (bytes == 0) {
return OK;
} else {
return -EIO;
}
}
status_t GenerateRandomUuid(std::string& out) {
status_t res = ReadRandomBytes(16, out);
if (res == OK) {
out[6] &= 0x0f; /* clear version */
out[6] |= 0x40; /* set to version 4 */
out[8] &= 0x3f; /* clear variant */
out[8] |= 0x80; /* set to IETF variant */
}
return res;
}
status_t HexToStr(const std::string& hex, std::string& str) {
str.clear();
bool even = true;
char cur = 0;
for (size_t i = 0; i < hex.size(); i++) {
int val = 0;
switch (hex[i]) {
// clang-format off
case ' ': case '-': case ':': continue;
case 'f': case 'F': val = 15; break;
case 'e': case 'E': val = 14; break;
case 'd': case 'D': val = 13; break;
case 'c': case 'C': val = 12; break;
case 'b': case 'B': val = 11; break;
case 'a': case 'A': val = 10; break;
case '9': val = 9; break;
case '8': val = 8; break;
case '7': val = 7; break;
case '6': val = 6; break;
case '5': val = 5; break;
case '4': val = 4; break;
case '3': val = 3; break;
case '2': val = 2; break;
case '1': val = 1; break;
case '0': val = 0; break;
default: return -EINVAL;
// clang-format on
}
if (even) {
cur = val << 4;
} else {
cur += val;
str.push_back(cur);
cur = 0;
}
even = !even;
}
return even ? OK : -EINVAL;
}
static const char* kLookup = "0123456789abcdef";
status_t StrToHex(const std::string& str, std::string& hex) {
hex.clear();
for (size_t i = 0; i < str.size(); i++) {
hex.push_back(kLookup[(str[i] & 0xF0) >> 4]);
hex.push_back(kLookup[str[i] & 0x0F]);
}
return OK;
}
status_t StrToHex(const KeyBuffer& str, KeyBuffer& hex) {
hex.clear();
for (size_t i = 0; i < str.size(); i++) {
hex.push_back(kLookup[(str.data()[i] & 0xF0) >> 4]);
hex.push_back(kLookup[str.data()[i] & 0x0F]);
}
return OK;
}
status_t NormalizeHex(const std::string& in, std::string& out) {
std::string tmp;
if (HexToStr(in, tmp)) {
return -EINVAL;
}
return StrToHex(tmp, out);
}
status_t GetBlockDevSize(int fd, uint64_t* size) {
if (ioctl(fd, BLKGETSIZE64, size)) {
return -errno;
}
return OK;
}
status_t GetBlockDevSize(const std::string& path, uint64_t* size) {
int fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
status_t res = OK;
if (fd < 0) {
return -errno;
}
res = GetBlockDevSize(fd, size);
close(fd);
return res;
}
status_t GetBlockDev512Sectors(const std::string& path, uint64_t* nr_sec) {
uint64_t size;
status_t res = GetBlockDevSize(path, &size);
if (res != OK) {
return res;
}
*nr_sec = size / 512;
return OK;
}
uint64_t GetFreeBytes(const std::string& path) {
struct statvfs sb;
if (statvfs(path.c_str(), &sb) == 0) {
return (uint64_t)sb.f_bavail * sb.f_frsize;
} else {
return -1;
}
}
// TODO: borrowed from frameworks/native/libs/diskusage/ which should
// eventually be migrated into system/
static int64_t stat_size(struct stat* s) {
int64_t blksize = s->st_blksize;
// count actual blocks used instead of nominal file size
int64_t size = s->st_blocks * 512;
if (blksize) {
/* round up to filesystem block size */
size = (size + blksize - 1) & (~(blksize - 1));
}
return size;
}
// TODO: borrowed from frameworks/native/libs/diskusage/ which should
// eventually be migrated into system/
int64_t calculate_dir_size(int dfd) {
int64_t size = 0;
struct stat s;
DIR* d;
struct dirent* de;
d = fdopendir(dfd);
if (d == NULL) {
close(dfd);
return 0;
}
while ((de = readdir(d))) {
const char* name = de->d_name;
if (fstatat(dfd, name, &s, AT_SYMLINK_NOFOLLOW) == 0) {
size += stat_size(&s);
}
if (de->d_type == DT_DIR) {
int subfd;
/* always skip "." and ".." */
if (IsDotOrDotDot(*de)) continue;
subfd = openat(dfd, name, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
if (subfd >= 0) {
size += calculate_dir_size(subfd);
}
}
}
closedir(d);
return size;
}
uint64_t GetTreeBytes(const std::string& path) {
int dirfd = open(path.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC);
if (dirfd < 0) {
PLOG(WARNING) << "Failed to open " << path;
return -1;
} else {
return calculate_dir_size(dirfd);
}
}
// TODO: Use a better way to determine if it's media provider app.
bool IsFuseDaemon(const pid_t pid) {
auto path = StringPrintf("/proc/%d/mounts", pid);
char* tmp;
if (lgetfilecon(path.c_str(), &tmp) < 0) {
return false;
}
bool result = android::base::StartsWith(tmp, kMediaProviderAppCtx)
|| android::base::StartsWith(tmp, kMediaProviderCtx);
freecon(tmp);
return result;
}
bool IsFilesystemSupported(const std::string& fsType) {
std::string supported;
if (!ReadFileToString(kProcFilesystems, &supported)) {
PLOG(ERROR) << "Failed to read supported filesystems";
return false;
}
return supported.find(fsType + "\n") != std::string::npos;
}
bool IsSdcardfsUsed() {
return IsFilesystemSupported("sdcardfs") &&
base::GetBoolProperty(kExternalStorageSdcardfs, true);
}
status_t WipeBlockDevice(const std::string& path) {
status_t res = -1;
const char* c_path = path.c_str();
uint64_t range[2] = {0, 0};
int fd = TEMP_FAILURE_RETRY(open(c_path, O_RDWR | O_CLOEXEC));
if (fd == -1) {
PLOG(ERROR) << "Failed to open " << path;
goto done;
}
if (GetBlockDevSize(fd, &range[1]) != OK) {
PLOG(ERROR) << "Failed to determine size of " << path;
goto done;
}
LOG(INFO) << "About to discard " << range[1] << " on " << path;
if (ioctl(fd, BLKDISCARD, &range) == 0) {
LOG(INFO) << "Discard success on " << path;
res = 0;
} else {
PLOG(ERROR) << "Discard failure on " << path;
}
done:
close(fd);
return res;
}
static bool isValidFilename(const std::string& name) {
if (name.empty() || (name == ".") || (name == "..") || (name.find('/') != std::string::npos)) {
return false;
} else {
return true;
}
}
std::string BuildKeyPath(const std::string& partGuid) {
return StringPrintf("%s/expand_%s.key", kKeyPath, partGuid.c_str());
}
std::string BuildDataSystemLegacyPath(userid_t userId) {
return StringPrintf("%s/system/users/%u", BuildDataPath("").c_str(), userId);
}
std::string BuildDataSystemCePath(userid_t userId) {
return StringPrintf("%s/system_ce/%u", BuildDataPath("").c_str(), userId);
}
std::string BuildDataSystemDePath(userid_t userId) {
return StringPrintf("%s/system_de/%u", BuildDataPath("").c_str(), userId);
}
std::string BuildDataMiscLegacyPath(userid_t userId) {
return StringPrintf("%s/misc/user/%u", BuildDataPath("").c_str(), userId);
}
// Keep in sync with installd (frameworks/native/cmds/installd/utils.h)
std::string BuildDataProfilesDePath(userid_t userId) {
return StringPrintf("%s/misc/profiles/cur/%u", BuildDataPath("").c_str(), userId);
}
std::string BuildDataVendorCePath(userid_t userId) {
return StringPrintf("%s/vendor_ce/%u", BuildDataPath("").c_str(), userId);
}
std::string BuildDataVendorDePath(userid_t userId) {
return StringPrintf("%s/vendor_de/%u", BuildDataPath("").c_str(), userId);
}
std::string BuildDataPath(const std::string& volumeUuid) {
// TODO: unify with installd path generation logic
if (volumeUuid.empty()) {
return "/data";
} else {
CHECK(isValidFilename(volumeUuid));
return StringPrintf("/mnt/expand/%s", volumeUuid.c_str());
}
}
std::string BuildDataMediaCePath(const std::string& volumeUuid, userid_t userId) {
// TODO: unify with installd path generation logic
std::string data(BuildDataPath(volumeUuid));
return StringPrintf("%s/media/%u", data.c_str(), userId);
}
std::string BuildDataMiscCePath(const std::string& volumeUuid, userid_t userId) {
return StringPrintf("%s/misc_ce/%u", BuildDataPath(volumeUuid).c_str(), userId);
}
std::string BuildDataMiscDePath(const std::string& volumeUuid, userid_t userId) {
return StringPrintf("%s/misc_de/%u", BuildDataPath(volumeUuid).c_str(), userId);
}
std::string BuildDataUserCePath(const std::string& volumeUuid, userid_t userId) {
// TODO: unify with installd path generation logic
std::string data(BuildDataPath(volumeUuid));
if (volumeUuid.empty() && userId == 0) {
std::string legacy = StringPrintf("%s/data", data.c_str());
struct stat sb;
if (lstat(legacy.c_str(), &sb) == 0 && S_ISDIR(sb.st_mode)) {
/* /data/data is dir, return /data/data for legacy system */
return legacy;
}
}
return StringPrintf("%s/user/%u", data.c_str(), userId);
}
std::string BuildDataUserDePath(const std::string& volumeUuid, userid_t userId) {
// TODO: unify with installd path generation logic
std::string data(BuildDataPath(volumeUuid));
return StringPrintf("%s/user_de/%u", data.c_str(), userId);
}
dev_t GetDevice(const std::string& path) {
struct stat sb;
if (stat(path.c_str(), &sb)) {
PLOG(WARNING) << "Failed to stat " << path;
return 0;
} else {
return sb.st_dev;
}
}
// Returns true if |path1| names the same existing file or directory as |path2|.
bool IsSameFile(const std::string& path1, const std::string& path2) {
struct stat stbuf1, stbuf2;
if (stat(path1.c_str(), &stbuf1) != 0 || stat(path2.c_str(), &stbuf2) != 0) return false;
return stbuf1.st_ino == stbuf2.st_ino && stbuf1.st_dev == stbuf2.st_dev;
}
status_t RestoreconRecursive(const std::string& path) {
LOG(DEBUG) << "Starting restorecon of " << path;
static constexpr const char* kRestoreconString = "selinux.restorecon_recursive";
android::base::SetProperty(kRestoreconString, "");
android::base::SetProperty(kRestoreconString, path);
android::base::WaitForProperty(kRestoreconString, path);
LOG(DEBUG) << "Finished restorecon of " << path;
return OK;
}
bool Readlinkat(int dirfd, const std::string& path, std::string* result) {
// Shamelessly borrowed from android::base::Readlink()
result->clear();
// Most Linux file systems (ext2 and ext4, say) limit symbolic links to
// 4095 bytes. Since we'll copy out into the string anyway, it doesn't
// waste memory to just start there. We add 1 so that we can recognize
// whether it actually fit (rather than being truncated to 4095).
std::vector<char> buf(4095 + 1);
while (true) {
ssize_t size = readlinkat(dirfd, path.c_str(), &buf[0], buf.size());
// Unrecoverable error?
if (size == -1) return false;
// It fit! (If size == buf.size(), it may have been truncated.)
if (static_cast<size_t>(size) < buf.size()) {
result->assign(&buf[0], size);
return true;
}
// Double our buffer and try again.
buf.resize(buf.size() * 2);
}
}
static unsigned int GetMajorBlockVirtioBlk() {
std::string devices;
if (!ReadFileToString(kProcDevices, &devices)) {
PLOG(ERROR) << "Unable to open /proc/devices";
return 0;
}
bool blockSection = false;
for (auto line : android::base::Split(devices, "\n")) {
if (line == "Block devices:") {
blockSection = true;
} else if (line == "Character devices:") {
blockSection = false;
} else if (blockSection) {
auto tokens = android::base::Split(line, " ");
if (tokens.size() == 2 && tokens[1] == "virtblk") {
return std::stoul(tokens[0]);
}
}
}
return 0;
}
bool IsVirtioBlkDevice(unsigned int major) {
// Most virtualized platforms expose block devices with the virtio-blk
// block device driver. Unfortunately, this driver does not use a fixed
// major number, but relies on the kernel to assign one from a specific
// range of block majors, which are allocated for "LOCAL/EXPERIMENAL USE"
// per Documentation/devices.txt. This is true even for the latest Linux
// kernel (4.4; see init() in drivers/block/virtio_blk.c).
static unsigned int kMajorBlockVirtioBlk = GetMajorBlockVirtioBlk();
return kMajorBlockVirtioBlk && major == kMajorBlockVirtioBlk;
}
status_t UnmountTree(const std::string& mountPoint) {
if (TEMP_FAILURE_RETRY(umount2(mountPoint.c_str(), MNT_DETACH)) < 0 && errno != EINVAL &&
errno != ENOENT) {
PLOG(ERROR) << "Failed to unmount " << mountPoint;
return -errno;
}
return OK;
}
bool IsDotOrDotDot(const struct dirent& ent) {
return strcmp(ent.d_name, ".") == 0 || strcmp(ent.d_name, "..") == 0;
}
static status_t delete_dir_contents(DIR* dir) {
// Shamelessly borrowed from android::installd
int dfd = dirfd(dir);
if (dfd < 0) {
return -errno;
}
status_t result = OK;
struct dirent* de;
while ((de = readdir(dir))) {
const char* name = de->d_name;
if (de->d_type == DT_DIR) {
/* always skip "." and ".." */
if (IsDotOrDotDot(*de)) continue;
android::base::unique_fd subfd(
openat(dfd, name, O_RDONLY | O_DIRECTORY | O_NOFOLLOW | O_CLOEXEC));
if (subfd.get() == -1) {
PLOG(ERROR) << "Couldn't openat " << name;
result = -errno;
continue;
}
std::unique_ptr<DIR, decltype(&closedir)> subdirp(
android::base::Fdopendir(std::move(subfd)), closedir);
if (!subdirp) {
PLOG(ERROR) << "Couldn't fdopendir " << name;
result = -errno;
continue;
}
result = delete_dir_contents(subdirp.get());
if (unlinkat(dfd, name, AT_REMOVEDIR) < 0) {
PLOG(ERROR) << "Couldn't unlinkat " << name;
result = -errno;
}
} else {
if (unlinkat(dfd, name, 0) < 0) {
PLOG(ERROR) << "Couldn't unlinkat " << name;
result = -errno;
}
}
}
return result;
}
status_t DeleteDirContentsAndDir(const std::string& pathname) {
status_t res = DeleteDirContents(pathname);
if (res < 0) {
return res;
}
if (TEMP_FAILURE_RETRY(rmdir(pathname.c_str())) < 0 && errno != ENOENT) {
PLOG(ERROR) << "rmdir failed on " << pathname;
return -errno;
}
LOG(VERBOSE) << "Success: rmdir on " << pathname;
return OK;
}
status_t DeleteDirContents(const std::string& pathname) {
// Shamelessly borrowed from android::installd
std::unique_ptr<DIR, decltype(&closedir)> dirp(opendir(pathname.c_str()), closedir);
if (!dirp) {
if (errno == ENOENT) {
return OK;
}
PLOG(ERROR) << "Failed to opendir " << pathname;
return -errno;
}
return delete_dir_contents(dirp.get());
}
// TODO(118708649): fix duplication with init/util.h
status_t WaitForFile(const char* filename, std::chrono::nanoseconds timeout) {
android::base::Timer t;
while (t.duration() < timeout) {
struct stat sb;
if (stat(filename, &sb) != -1) {
LOG(INFO) << "wait for '" << filename << "' took " << t;
return 0;
}
std::this_thread::sleep_for(10ms);
}
LOG(WARNING) << "wait for '" << filename << "' timed out and took " << t;
return -1;
}
bool pathExists(const std::string& path) {
return access(path.c_str(), F_OK) == 0;
}
bool FsyncDirectory(const std::string& dirname) {
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(dirname.c_str(), O_RDONLY | O_CLOEXEC)));
if (fd == -1) {
PLOG(ERROR) << "Failed to open " << dirname;
return false;
}
if (fsync(fd) == -1) {
if (errno == EROFS || errno == EINVAL) {
PLOG(WARNING) << "Skip fsync " << dirname
<< " on a file system does not support synchronization";
} else {
PLOG(ERROR) << "Failed to fsync " << dirname;
return false;
}
}
return true;
}
bool FsyncParentDirectory(const std::string& path) {
return FsyncDirectory(android::base::Dirname(path));
}
// Creates all parent directories of |path| that don't already exist. Assigns
// the specified |mode| to any new directories, and also fsync()s their parent
// directories so that the new directories get written to disk right away.
bool MkdirsSync(const std::string& path, mode_t mode) {
if (path[0] != '/') {
LOG(ERROR) << "MkdirsSync() needs an absolute path, but got " << path;
return false;
}
std::vector<std::string> components = android::base::Split(android::base::Dirname(path), "/");
std::string current_dir = "/";
for (const std::string& component : components) {
if (component.empty()) continue;
std::string parent_dir = current_dir;
if (current_dir != "/") current_dir += "/";
current_dir += component;
if (!pathExists(current_dir)) {
if (mkdir(current_dir.c_str(), mode) != 0) {
PLOG(ERROR) << "Failed to create " << current_dir;
return false;
}
if (!FsyncDirectory(parent_dir)) return false;
LOG(DEBUG) << "Created directory " << current_dir;
}
}
return true;
}
bool writeStringToFile(const std::string& payload, const std::string& filename) {
android::base::unique_fd fd(TEMP_FAILURE_RETRY(
open(filename.c_str(), O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0666)));
if (fd == -1) {
PLOG(ERROR) << "Failed to open " << filename;
return false;
}
if (!android::base::WriteStringToFd(payload, fd)) {
PLOG(ERROR) << "Failed to write to " << filename;
unlink(filename.c_str());
return false;
}
// fsync as close won't guarantee flush data
// see close(2), fsync(2) and b/68901441
if (fsync(fd) == -1) {
if (errno == EROFS || errno == EINVAL) {
PLOG(WARNING) << "Skip fsync " << filename
<< " on a file system does not support synchronization";
} else {
PLOG(ERROR) << "Failed to fsync " << filename;
unlink(filename.c_str());
return false;
}
}
return true;
}
status_t AbortFuseConnections() {
namespace fs = std::filesystem;
for (const auto& itEntry : fs::directory_iterator("/sys/fs/fuse/connections")) {
std::string fsPath = itEntry.path().string() + "/filesystem";
std::string fs;
// Virtiofs is on top of fuse and there isn't any user space daemon.
// Android user space doesn't manage it.
if (android::base::ReadFileToString(fsPath, &fs, false) &&
android::base::Trim(fs) == "virtiofs") {
LOG(INFO) << "Ignore virtiofs connection entry " << itEntry.path().string();
continue;
}
std::string abortPath = itEntry.path().string() + "/abort";
LOG(DEBUG) << "Aborting fuse connection entry " << abortPath;
bool ret = writeStringToFile("1", abortPath);
if (!ret) {
LOG(WARNING) << "Failed to write to " << abortPath;
}
}
return OK;
}
status_t EnsureDirExists(const std::string& path, mode_t mode, uid_t uid, gid_t gid) {
if (access(path.c_str(), F_OK) != 0) {
PLOG(WARNING) << "Dir does not exist: " << path;
if (fs_prepare_dir(path.c_str(), mode, uid, gid) != 0) {
return -errno;
}
}
return OK;
}
// Gets the sysfs path for parameters of the backing device info (bdi)
static std::string getBdiPathForMount(const std::string& mount) {
// First figure out MAJOR:MINOR of mount. Simplest way is to stat the path.
struct stat info;
if (stat(mount.c_str(), &info) != 0) {
PLOG(ERROR) << "Failed to stat " << mount;
return "";
}
unsigned int maj = major(info.st_dev);
unsigned int min = minor(info.st_dev);
return StringPrintf("/sys/class/bdi/%u:%u", maj, min);
}
// Configures max_ratio for the FUSE filesystem.
void ConfigureMaxDirtyRatioForFuse(const std::string& fuse_mount, unsigned int max_ratio) {
LOG(INFO) << "Configuring max_ratio of " << fuse_mount << " fuse filesystem to " << max_ratio;
if (max_ratio > 100) {
LOG(ERROR) << "Invalid max_ratio: " << max_ratio;
return;
}
std::string fuseBdiPath = getBdiPathForMount(fuse_mount);
if (fuseBdiPath == "") {
return;
}
std::string max_ratio_file = StringPrintf("%s/max_ratio", fuseBdiPath.c_str());
unique_fd fd(TEMP_FAILURE_RETRY(open(max_ratio_file.c_str(), O_WRONLY | O_CLOEXEC)));
if (fd.get() == -1) {
PLOG(ERROR) << "Failed to open " << max_ratio_file;
return;
}
LOG(INFO) << "Writing " << max_ratio << " to " << max_ratio_file;
if (!WriteStringToFd(std::to_string(max_ratio), fd)) {
PLOG(ERROR) << "Failed to write to " << max_ratio_file;
}
}
// Configures read ahead property of the fuse filesystem with the mount point |fuse_mount| by
// writing |read_ahead_kb| to the /sys/class/bdi/MAJOR:MINOR/read_ahead_kb.
void ConfigureReadAheadForFuse(const std::string& fuse_mount, size_t read_ahead_kb) {
LOG(INFO) << "Configuring read_ahead of " << fuse_mount << " fuse filesystem to "
<< read_ahead_kb << "kb";
std::string fuseBdiPath = getBdiPathForMount(fuse_mount);
if (fuseBdiPath == "") {
return;
}
// We found the bdi path for our filesystem, time to configure read ahead!
std::string read_ahead_file = StringPrintf("%s/read_ahead_kb", fuseBdiPath.c_str());
unique_fd fd(TEMP_FAILURE_RETRY(open(read_ahead_file.c_str(), O_WRONLY | O_CLOEXEC)));
if (fd.get() == -1) {
PLOG(ERROR) << "Failed to open " << read_ahead_file;
return;
}
LOG(INFO) << "Writing " << read_ahead_kb << " to " << read_ahead_file;
if (!WriteStringToFd(std::to_string(read_ahead_kb), fd)) {
PLOG(ERROR) << "Failed to write to " << read_ahead_file;
}
}
status_t MountUserFuse(userid_t user_id, const std::string& absolute_lower_path,
const std::string& relative_upper_path, android::base::unique_fd* fuse_fd) {
std::string pre_fuse_path(StringPrintf("/mnt/user/%d", user_id));
std::string fuse_path(
StringPrintf("%s/%s", pre_fuse_path.c_str(), relative_upper_path.c_str()));
std::string pre_pass_through_path(StringPrintf("/mnt/pass_through/%d", user_id));
std::string pass_through_path(
StringPrintf("%s/%s", pre_pass_through_path.c_str(), relative_upper_path.c_str()));
// Ensure that /mnt/user is 0700. With FUSE, apps don't need access to /mnt/user paths directly.
// Without FUSE however, apps need /mnt/user access so /mnt/user in init.rc is 0755 until here
auto result = PrepareDir("/mnt/user", 0750, AID_ROOT, AID_MEDIA_RW);
if (result != android::OK) {
PLOG(ERROR) << "Failed to prepare directory /mnt/user";
return -1;
}
// Shell is neither AID_ROOT nor AID_EVERYBODY. Since it equally needs 'execute' access to
// /mnt/user/0 to 'adb shell ls /sdcard' for instance, we set the uid bit of /mnt/user/0 to
// AID_SHELL. This gives shell access along with apps running as group everybody (user 0 apps)
// These bits should be consistent with what is set in zygote in
// com_android_internal_os_Zygote#MountEmulatedStorage on volume bind mount during app fork
result = PrepareDir(pre_fuse_path, 0710, user_id ? AID_ROOT : AID_SHELL,
multiuser_get_uid(user_id, AID_EVERYBODY));
if (result != android::OK) {
PLOG(ERROR) << "Failed to prepare directory " << pre_fuse_path;
return -1;
}
result = PrepareDir(fuse_path, 0700, AID_ROOT, AID_ROOT);
if (result != android::OK) {
PLOG(ERROR) << "Failed to prepare directory " << fuse_path;
return -1;
}
result = PrepareDir(pre_pass_through_path, 0710, AID_ROOT, AID_MEDIA_RW);
if (result != android::OK) {
PLOG(ERROR) << "Failed to prepare directory " << pre_pass_through_path;
return -1;
}
result = PrepareDir(pass_through_path, 0710, AID_ROOT, AID_MEDIA_RW);
if (result != android::OK) {
PLOG(ERROR) << "Failed to prepare directory " << pass_through_path;
return -1;
}
if (relative_upper_path == "emulated") {
std::string linkpath(StringPrintf("/mnt/user/%d/self", user_id));
result = PrepareDir(linkpath, 0755, AID_ROOT, AID_ROOT);
if (result != android::OK) {
PLOG(ERROR) << "Failed to prepare directory " << linkpath;
return -1;
}
linkpath += "/primary";
Symlink("/storage/emulated/" + std::to_string(user_id), linkpath);
std::string pass_through_linkpath(StringPrintf("/mnt/pass_through/%d/self", user_id));
result = PrepareDir(pass_through_linkpath, 0710, AID_ROOT, AID_MEDIA_RW);
if (result != android::OK) {
PLOG(ERROR) << "Failed to prepare directory " << pass_through_linkpath;
return -1;
}
pass_through_linkpath += "/primary";
Symlink("/storage/emulated/" + std::to_string(user_id), pass_through_linkpath);
}
// Open fuse fd.
fuse_fd->reset(open("/dev/fuse", O_RDWR | O_CLOEXEC));
if (fuse_fd->get() == -1) {
PLOG(ERROR) << "Failed to open /dev/fuse";
return -1;
}
// Note: leaving out default_permissions since we don't want kernel to do lower filesystem
// permission checks before routing to FUSE daemon.
const auto opts = StringPrintf(
"fd=%i,"
"rootmode=40000,"
"allow_other,"
"user_id=0,group_id=0,",
fuse_fd->get());
result = TEMP_FAILURE_RETRY(mount("/dev/fuse", fuse_path.c_str(), "fuse",
MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME | MS_LAZYTIME,
opts.c_str()));
if (result != 0) {
PLOG(ERROR) << "Failed to mount " << fuse_path;
return -errno;
}
if (IsSdcardfsUsed()) {
std::string sdcardfs_path(
StringPrintf("/mnt/runtime/full/%s", relative_upper_path.c_str()));
LOG(INFO) << "Bind mounting " << sdcardfs_path << " to " << pass_through_path;
return BindMount(sdcardfs_path, pass_through_path);
} else {
LOG(INFO) << "Bind mounting " << absolute_lower_path << " to " << pass_through_path;
return BindMount(absolute_lower_path, pass_through_path);
}
}
status_t UnmountUserFuse(userid_t user_id, const std::string& absolute_lower_path,
const std::string& relative_upper_path) {
std::string fuse_path(StringPrintf("/mnt/user/%d/%s", user_id, relative_upper_path.c_str()));
std::string pass_through_path(
StringPrintf("/mnt/pass_through/%d/%s", user_id, relative_upper_path.c_str()));
LOG(INFO) << "Unmounting fuse path " << fuse_path;
android::status_t result = ForceUnmount(fuse_path);
if (result != android::OK) {
// TODO(b/135341433): MNT_DETACH is needed for fuse because umount2 can fail with EBUSY.
// Figure out why we get EBUSY and remove this special casing if possible.
PLOG(ERROR) << "Failed to unmount. Trying MNT_DETACH " << fuse_path << " ...";
if (umount2(fuse_path.c_str(), UMOUNT_NOFOLLOW | MNT_DETACH) && errno != EINVAL &&
errno != ENOENT) {
PLOG(ERROR) << "Failed to unmount with MNT_DETACH " << fuse_path;
return -errno;
}
result = android::OK;
}
rmdir(fuse_path.c_str());
LOG(INFO) << "Unmounting pass_through_path " << pass_through_path;
auto status = ForceUnmount(pass_through_path);
if (status != android::OK) {
LOG(ERROR) << "Failed to unmount " << pass_through_path;
}
rmdir(pass_through_path.c_str());
return result;
}
status_t PrepareAndroidDirs(const std::string& volumeRoot) {
std::string androidDir = volumeRoot + kAndroidDir;
std::string androidDataDir = volumeRoot + kAppDataDir;
std::string androidObbDir = volumeRoot + kAppObbDir;
std::string androidMediaDir = volumeRoot + kAppMediaDir;
bool useSdcardFs = IsSdcardfsUsed();
// mode 0771 + sticky bit for inheriting GIDs
mode_t mode = S_IRWXU | S_IRWXG | S_IXOTH | S_ISGID;
if (fs_prepare_dir(androidDir.c_str(), mode, AID_MEDIA_RW, AID_MEDIA_RW) != 0) {
PLOG(ERROR) << "Failed to create " << androidDir;
return -errno;
}
gid_t dataGid = useSdcardFs ? AID_MEDIA_RW : AID_EXT_DATA_RW;
if (fs_prepare_dir(androidDataDir.c_str(), mode, AID_MEDIA_RW, dataGid) != 0) {
PLOG(ERROR) << "Failed to create " << androidDataDir;
return -errno;
}
gid_t obbGid = useSdcardFs ? AID_MEDIA_RW : AID_EXT_OBB_RW;
if (fs_prepare_dir(androidObbDir.c_str(), mode, AID_MEDIA_RW, obbGid) != 0) {
PLOG(ERROR) << "Failed to create " << androidObbDir;
return -errno;
}
// Some other apps, like installers, have write access to the OBB directory
// to pre-download them. To make sure newly created folders in this directory
// have the right permissions, set a default ACL.
SetDefaultAcl(androidObbDir, mode, AID_MEDIA_RW, obbGid, {});
if (fs_prepare_dir(androidMediaDir.c_str(), mode, AID_MEDIA_RW, AID_MEDIA_RW) != 0) {
PLOG(ERROR) << "Failed to create " << androidMediaDir;
return -errno;
}
return OK;
}
namespace ab = android::base;
static ab::unique_fd openDirFd(int parentFd, const char* name) {
return ab::unique_fd{::openat(parentFd, name, O_CLOEXEC | O_DIRECTORY | O_PATH | O_NOFOLLOW)};
}
static ab::unique_fd openAbsolutePathFd(std::string_view path) {
if (path.empty() || path[0] != '/') {
errno = EINVAL;
return {};
}
if (path == "/") {
return openDirFd(-1, "/");
}
// first component is special - it includes the leading slash
auto next = path.find('/', 1);
auto component = std::string(path.substr(0, next));
if (component == "..") {
errno = EINVAL;
return {};
}
auto fd = openDirFd(-1, component.c_str());
if (!fd.ok()) {
return fd;
}
path.remove_prefix(std::min(next + 1, path.size()));
while (next != path.npos && !path.empty()) {
next = path.find('/');
component.assign(path.substr(0, next));
fd = openDirFd(fd, component.c_str());
if (!fd.ok()) {
return fd;
}
path.remove_prefix(std::min(next + 1, path.size()));
}
return fd;
}
std::pair<android::base::unique_fd, std::string> OpenDirInProcfs(std::string_view path) {
auto fd = openAbsolutePathFd(path);
if (!fd.ok()) {
return {};
}
auto linkPath = std::string("/proc/self/fd/") += std::to_string(fd.get());
return {std::move(fd), std::move(linkPath)};
}
} // namespace vold
} // namespace android
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