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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 <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 <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::GetBoolProperty;
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 bool Mkdir(const std::string& path, mode_t mode, const std::string& uid,
const std::string& gid) {
if (mode == 0) {
mode = 0755;
}
if (mkdir(path.c_str(), mode) != 0) {
/* chmod in case the directory already exists */
if (errno == EEXIST) {
if (fchmodat(AT_FDCWD, path.c_str(), mode, AT_SYMLINK_NOFOLLOW) != 0) {
// /acct is a special case when the directory already exists
// TODO: check if file mode is already what we want instead of using EROFS
if (errno != EROFS) {
PLOG(ERROR) << "fchmodat() failed for " << path;
return false;
}
}
} else {
PLOG(ERROR) << "mkdir() failed for " << path;
return false;
}
}
if (uid.empty()) {
return true;
}
passwd* uid_pwd = getpwnam(uid.c_str());
if (!uid_pwd) {
PLOG(ERROR) << "Unable to decode UID for '" << uid << "'";
return false;
}
uid_t pw_uid = uid_pwd->pw_uid;
gid_t 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;
}
if (lchown(path.c_str(), pw_uid, gr_gid) < 0) {
PLOG(ERROR) << "lchown() failed for " << path;
return false;
}
/* chown may have cleared S_ISUID and S_ISGID, chmod again */
if (mode & (S_ISUID | S_ISGID)) {
if (fchmodat(AT_FDCWD, path.c_str(), mode, AT_SYMLINK_NOFOLLOW) != 0) {
PLOG(ERROR) << "fchmodat() failed for " << path;
return false;
}
}
return true;
}
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::Reader reader;
Json::Value root;
if (!reader.parse(json_doc, root)) {
LOG(ERROR) << "Failed to parse cgroups description: " << reader.getFormattedErrorMessages();
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();
auto iter = descriptors->find(name);
if (iter == descriptors->end()) {
descriptors->emplace(
name, CgroupDescriptor(
1, name, cgroups[i]["Path"].asString(),
std::strtoul(cgroups[i]["Mode"].asString().c_str(), 0, 8),
cgroups[i]["UID"].asString(), cgroups[i]["GID"].asString()));
} else {
iter->second = CgroupDescriptor(
1, name, cgroups[i]["Path"].asString(),
std::strtoul(cgroups[i]["Mode"].asString().c_str(), 0, 8),
cgroups[i]["UID"].asString(), cgroups[i]["GID"].asString());
}
}
}
if (root.isMember("Cgroups2")) {
const Json::Value& cgroups2 = root["Cgroups2"];
auto iter = descriptors->find(CGROUPV2_CONTROLLER_NAME);
if (iter == descriptors->end()) {
descriptors->emplace(
CGROUPV2_CONTROLLER_NAME,
CgroupDescriptor(2, CGROUPV2_CONTROLLER_NAME, cgroups2["Path"].asString(),
std::strtoul(cgroups2["Mode"].asString().c_str(), 0, 8),
cgroups2["UID"].asString(), cgroups2["GID"].asString()));
} else {
iter->second =
CgroupDescriptor(2, CGROUPV2_CONTROLLER_NAME, cgroups2["Path"].asString(),
std::strtoul(cgroups2["Mode"].asString().c_str(), 0, 8),
cgroups2["UID"].asString(), cgroups2["GID"].asString());
}
}
return true;
}
static bool ReadDescriptors(std::map<std::string, CgroupDescriptor>* descriptors) {
// load system cgroup descriptors
if (!ReadDescriptorsFromFile(CGROUPS_DESC_FILE, 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 SetupCgroup(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;
}
int result;
if (controller->version() == 2) {
result = mount("none", controller->path(), "cgroup2", MS_NODEV | MS_NOEXEC | MS_NOSUID,
nullptr);
} else {
// 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.
if (!strcmp(controller->name(), "cpuset")) {
// mount cpuset none /dev/cpuset nodev noexec nosuid
result = mount("none", controller->path(), controller->name(),
MS_NODEV | MS_NOEXEC | MS_NOSUID, nullptr);
} else {
// mount cgroup none <path> nodev noexec nosuid <controller>
result = mount("none", controller->path(), "cgroup", MS_NODEV | MS_NOEXEC | MS_NOSUID,
controller->name());
}
}
if (result < 0) {
PLOG(ERROR) << "Failed to mount " << controller->name() << " cgroup";
return false;
}
return true;
}
#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)
: controller_(version, name, path), mode_(mode), uid_(uid), gid_(gid) {}
} // 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 SetupCgroups 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 (const auto& [name, descriptor] : descriptors) {
if (!SetupCgroup(descriptor)) {
// issue a warning and proceed with the next cgroup
// TODO: mark the descriptor as invalid and skip it in WriteRcFile()
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;
}