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/*
* Copyright (C) 2019 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.
*/
//#define LOG_NDEBUG 0
#define LOG_TAG "libprocessgroup"
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <pwd.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include <regex>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
#include <android/cgrouprc.h>
#include <json/reader.h>
#include <json/value.h>
#include <processgroup/format/cgroup_file.h>
#include <processgroup/processgroup.h>
#include <processgroup/setup.h>
#include "cgroup_descriptor.h"
using android::base::GetUintProperty;
using android::base::StringPrintf;
using android::base::unique_fd;
namespace android {
namespace cgrouprc {
static constexpr const char* CGROUPS_DESC_FILE = "/etc/cgroups.json";
static constexpr const char* CGROUPS_DESC_VENDOR_FILE = "/vendor/etc/cgroups.json";
static constexpr const char* TEMPLATE_CGROUPS_DESC_API_FILE = "/etc/task_profiles/cgroups_%u.json";
static bool ChangeDirModeAndOwner(const std::string& path, mode_t mode, const std::string& uid,
const std::string& gid, bool permissive_mode = false) {
uid_t pw_uid = -1;
gid_t gr_gid = -1;
if (!uid.empty()) {
passwd* uid_pwd = getpwnam(uid.c_str());
if (!uid_pwd) {
PLOG(ERROR) << "Unable to decode UID for '" << uid << "'";
return false;
}
pw_uid = uid_pwd->pw_uid;
gr_gid = -1;
if (!gid.empty()) {
group* gid_pwd = getgrnam(gid.c_str());
if (!gid_pwd) {
PLOG(ERROR) << "Unable to decode GID for '" << gid << "'";
return false;
}
gr_gid = gid_pwd->gr_gid;
}
}
auto dir = std::unique_ptr<DIR, decltype(&closedir)>(opendir(path.c_str()), closedir);
if (dir == NULL) {
PLOG(ERROR) << "opendir failed for " << path;
return false;
}
struct dirent* dir_entry;
while ((dir_entry = readdir(dir.get()))) {
if (!strcmp("..", dir_entry->d_name)) {
continue;
}
std::string file_path = path + "/" + dir_entry->d_name;
if (pw_uid != -1 && lchown(file_path.c_str(), pw_uid, gr_gid) < 0) {
PLOG(ERROR) << "lchown() failed for " << file_path;
return false;
}
if (fchmodat(AT_FDCWD, file_path.c_str(), mode, AT_SYMLINK_NOFOLLOW) != 0 &&
(errno != EROFS || !permissive_mode)) {
PLOG(ERROR) << "fchmodat() failed for " << path;
return false;
}
}
return true;
}
static bool Mkdir(const std::string& path, mode_t mode, const std::string& uid,
const std::string& gid) {
bool permissive_mode = false;
if (mode == 0) {
/* Allow chmod to fail */
permissive_mode = true;
mode = 0755;
}
if (mkdir(path.c_str(), mode) != 0) {
// /acct is a special case when the directory already exists
if (errno != EEXIST) {
PLOG(ERROR) << "mkdir() failed for " << path;
return false;
} else {
permissive_mode = true;
}
}
if (uid.empty() && permissive_mode) {
return true;
}
if (!ChangeDirModeAndOwner(path, mode, uid, gid, permissive_mode)) {
PLOG(ERROR) << "change of ownership or mode failed for " << path;
return false;
}
return true;
}
static void MergeCgroupToDescriptors(std::map<std::string, CgroupDescriptor>* descriptors,
const Json::Value& cgroup, const std::string& name,
const std::string& root_path, int cgroups_version) {
const std::string cgroup_path = cgroup["Path"].asString();
std::string path;
if (!root_path.empty()) {
path = root_path;
if (cgroup_path != ".") {
path += "/";
path += cgroup_path;
}
} else {
path = cgroup_path;
}
uint32_t controller_flags = 0;
if (cgroup["NeedsActivation"].isBool() && cgroup["NeedsActivation"].asBool()) {
controller_flags |= CGROUPRC_CONTROLLER_FLAG_NEEDS_ACTIVATION;
}
if (cgroup["Optional"].isBool() && cgroup["Optional"].asBool()) {
controller_flags |= CGROUPRC_CONTROLLER_FLAG_OPTIONAL;
}
CgroupDescriptor descriptor(
cgroups_version, name, path, std::strtoul(cgroup["Mode"].asString().c_str(), 0, 8),
cgroup["UID"].asString(), cgroup["GID"].asString(), controller_flags);
auto iter = descriptors->find(name);
if (iter == descriptors->end()) {
descriptors->emplace(name, descriptor);
} else {
iter->second = descriptor;
}
}
static bool ReadDescriptorsFromFile(const std::string& file_name,
std::map<std::string, CgroupDescriptor>* descriptors) {
std::vector<CgroupDescriptor> result;
std::string json_doc;
if (!android::base::ReadFileToString(file_name, &json_doc)) {
PLOG(ERROR) << "Failed to read task profiles from " << file_name;
return false;
}
Json::CharReaderBuilder builder;
std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
Json::Value root;
std::string errorMessage;
if (!reader->parse(&*json_doc.begin(), &*json_doc.end(), &root, &errorMessage)) {
LOG(ERROR) << "Failed to parse cgroups description: " << errorMessage;
return false;
}
if (root.isMember("Cgroups")) {
const Json::Value& cgroups = root["Cgroups"];
for (Json::Value::ArrayIndex i = 0; i < cgroups.size(); ++i) {
std::string name = cgroups[i]["Controller"].asString();
MergeCgroupToDescriptors(descriptors, cgroups[i], name, "", 1);
}
}
if (root.isMember("Cgroups2")) {
const Json::Value& cgroups2 = root["Cgroups2"];
std::string root_path = cgroups2["Path"].asString();
MergeCgroupToDescriptors(descriptors, cgroups2, CGROUPV2_CONTROLLER_NAME, "", 2);
const Json::Value& childGroups = cgroups2["Controllers"];
for (Json::Value::ArrayIndex i = 0; i < childGroups.size(); ++i) {
std::string name = childGroups[i]["Controller"].asString();
MergeCgroupToDescriptors(descriptors, childGroups[i], name, root_path, 2);
}
}
return true;
}
static bool ReadDescriptors(std::map<std::string, CgroupDescriptor>* descriptors) {
// load system cgroup descriptors
if (!ReadDescriptorsFromFile(CGROUPS_DESC_FILE, descriptors)) {
return false;
}
// load API-level specific system cgroups descriptors if available
unsigned int api_level = GetUintProperty<unsigned int>("ro.product.first_api_level", 0);
if (api_level > 0) {
std::string api_cgroups_path =
android::base::StringPrintf(TEMPLATE_CGROUPS_DESC_API_FILE, api_level);
if (!access(api_cgroups_path.c_str(), F_OK) || errno != ENOENT) {
if (!ReadDescriptorsFromFile(api_cgroups_path, descriptors)) {
return false;
}
}
}
// load vendor cgroup descriptors if the file exists
if (!access(CGROUPS_DESC_VENDOR_FILE, F_OK) &&
!ReadDescriptorsFromFile(CGROUPS_DESC_VENDOR_FILE, descriptors)) {
return false;
}
return true;
}
// To avoid issues in sdk_mac build
#if defined(__ANDROID__)
static bool IsOptionalController(const format::CgroupController* controller) {
return controller->flags() & CGROUPRC_CONTROLLER_FLAG_OPTIONAL;
}
static bool MountV2CgroupController(const CgroupDescriptor& descriptor) {
const format::CgroupController* controller = descriptor.controller();
// /sys/fs/cgroup is created by cgroup2 with specific selinux permissions,
// try to create again in case the mount point is changed
if (!Mkdir(controller->path(), 0, "", "")) {
LOG(ERROR) << "Failed to create directory for " << controller->name() << " cgroup";
return false;
}
// The memory_recursiveprot mount option has been introduced by kernel commit
// 8a931f801340 ("mm: memcontrol: recursive memory.low protection"; v5.7). Try first to
// mount with that option enabled. If mounting fails because the kernel is too old,
// retry without that mount option.
if (mount("none", controller->path(), "cgroup2", MS_NODEV | MS_NOEXEC | MS_NOSUID,
"memory_recursiveprot") < 0) {
LOG(INFO) << "Mounting memcg with memory_recursiveprot failed. Retrying without.";
if (mount("none", controller->path(), "cgroup2", MS_NODEV | MS_NOEXEC | MS_NOSUID,
nullptr) < 0) {
PLOG(ERROR) << "Failed to mount cgroup v2";
return IsOptionalController(controller);
}
}
// selinux permissions change after mounting, so it's ok to change mode and owner now
if (!ChangeDirModeAndOwner(controller->path(), descriptor.mode(), descriptor.uid(),
descriptor.gid())) {
PLOG(ERROR) << "Change of ownership or mode failed for controller " << controller->name();
return IsOptionalController(controller);
}
return true;
}
static bool ActivateV2CgroupController(const CgroupDescriptor& descriptor) {
const format::CgroupController* controller = descriptor.controller();
if (!Mkdir(controller->path(), descriptor.mode(), descriptor.uid(), descriptor.gid())) {
LOG(ERROR) << "Failed to create directory for " << controller->name() << " cgroup";
return false;
}
if (controller->flags() & CGROUPRC_CONTROLLER_FLAG_NEEDS_ACTIVATION) {
std::string str = "+";
str += controller->name();
std::string path = controller->path();
path += "/cgroup.subtree_control";
if (!base::WriteStringToFile(str, path)) {
if (IsOptionalController(controller)) {
PLOG(INFO) << "Failed to activate optional controller " << controller->name();
return true;
}
PLOG(ERROR) << "Failed to activate controller " << controller->name();
return false;
}
}
return true;
}
static bool MountV1CgroupController(const CgroupDescriptor& descriptor) {
const format::CgroupController* controller = descriptor.controller();
// mkdir <path> [mode] [owner] [group]
if (!Mkdir(controller->path(), descriptor.mode(), descriptor.uid(), descriptor.gid())) {
LOG(ERROR) << "Failed to create directory for " << controller->name() << " cgroup";
return false;
}
// Unfortunately historically cpuset controller was mounted using a mount command
// different from all other controllers. This results in controller attributes not
// to be prepended with controller name. For example this way instead of
// /dev/cpuset/cpuset.cpus the attribute becomes /dev/cpuset/cpus which is what
// the system currently expects.
int res;
if (!strcmp(controller->name(), "cpuset")) {
// mount cpuset none /dev/cpuset nodev noexec nosuid
res = mount("none", controller->path(), controller->name(),
MS_NODEV | MS_NOEXEC | MS_NOSUID, nullptr);
} else {
// mount cgroup none <path> nodev noexec nosuid <controller>
res = mount("none", controller->path(), "cgroup", MS_NODEV | MS_NOEXEC | MS_NOSUID,
controller->name());
}
if (res != 0) {
if (IsOptionalController(controller)) {
PLOG(INFO) << "Failed to mount optional controller " << controller->name();
return true;
}
PLOG(ERROR) << "Failed to mount controller " << controller->name();
return false;
}
return true;
}
static bool SetupCgroup(const CgroupDescriptor& descriptor) {
const format::CgroupController* controller = descriptor.controller();
if (controller->version() == 2) {
if (!strcmp(controller->name(), CGROUPV2_CONTROLLER_NAME)) {
return MountV2CgroupController(descriptor);
} else {
return ActivateV2CgroupController(descriptor);
}
} else {
return MountV1CgroupController(descriptor);
}
}
#else
// Stubs for non-Android targets.
static bool SetupCgroup(const CgroupDescriptor&) {
return false;
}
#endif
static bool WriteRcFile(const std::map<std::string, CgroupDescriptor>& descriptors) {
unique_fd fd(TEMP_FAILURE_RETRY(open(CGROUPS_RC_PATH, O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC,
S_IRUSR | S_IRGRP | S_IROTH)));
if (fd < 0) {
PLOG(ERROR) << "open() failed for " << CGROUPS_RC_PATH;
return false;
}
format::CgroupFile fl;
fl.version_ = format::CgroupFile::FILE_CURR_VERSION;
fl.controller_count_ = descriptors.size();
int ret = TEMP_FAILURE_RETRY(write(fd, &fl, sizeof(fl)));
if (ret < 0) {
PLOG(ERROR) << "write() failed for " << CGROUPS_RC_PATH;
return false;
}
for (const auto& [name, descriptor] : descriptors) {
ret = TEMP_FAILURE_RETRY(
write(fd, descriptor.controller(), sizeof(format::CgroupController)));
if (ret < 0) {
PLOG(ERROR) << "write() failed for " << CGROUPS_RC_PATH;
return false;
}
}
return true;
}
CgroupDescriptor::CgroupDescriptor(uint32_t version, const std::string& name,
const std::string& path, mode_t mode, const std::string& uid,
const std::string& gid, uint32_t flags = 0)
: controller_(version, flags, name, path), mode_(mode), uid_(uid), gid_(gid) {}
void CgroupDescriptor::set_mounted(bool mounted) {
uint32_t flags = controller_.flags();
if (mounted) {
flags |= CGROUPRC_CONTROLLER_FLAG_MOUNTED;
} else {
flags &= ~CGROUPRC_CONTROLLER_FLAG_MOUNTED;
}
controller_.set_flags(flags);
}
} // namespace cgrouprc
} // namespace android
bool CgroupSetup() {
using namespace android::cgrouprc;
std::map<std::string, CgroupDescriptor> descriptors;
if (getpid() != 1) {
LOG(ERROR) << "Cgroup setup can be done only by init process";
return false;
}
// Make sure we do this only one time. No need for std::call_once because
// init is a single-threaded process
if (access(CGROUPS_RC_PATH, F_OK) == 0) {
LOG(WARNING) << "Attempt to call CgroupSetup() more than once";
return true;
}
// load cgroups.json file
if (!ReadDescriptors(&descriptors)) {
LOG(ERROR) << "Failed to load cgroup description file";
return false;
}
// setup cgroups
for (auto& [name, descriptor] : descriptors) {
if (SetupCgroup(descriptor)) {
descriptor.set_mounted(true);
} else {
// issue a warning and proceed with the next cgroup
LOG(WARNING) << "Failed to setup " << name << " cgroup";
}
}
// mkdir <CGROUPS_RC_DIR> 0711 system system
if (!Mkdir(android::base::Dirname(CGROUPS_RC_PATH), 0711, "system", "system")) {
LOG(ERROR) << "Failed to create directory for " << CGROUPS_RC_PATH << " file";
return false;
}
// Generate <CGROUPS_RC_FILE> file which can be directly mmapped into
// process memory. This optimizes performance, memory usage
// and limits infrormation shared with unprivileged processes
// to the minimum subset of information from cgroups.json
if (!WriteRcFile(descriptors)) {
LOG(ERROR) << "Failed to write " << CGROUPS_RC_PATH << " file";
return false;
}
// chmod 0644 <CGROUPS_RC_PATH>
if (fchmodat(AT_FDCWD, CGROUPS_RC_PATH, 0644, AT_SYMLINK_NOFOLLOW) < 0) {
PLOG(ERROR) << "fchmodat() failed";
return false;
}
return true;
}
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