497 lines
16 KiB
C++
497 lines
16 KiB
C++
/*
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* Copyright 2014 Google, Inc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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//#define LOG_NDEBUG 0
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#define LOG_TAG "libprocessgroup"
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#include <assert.h>
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <chrono>
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#include <map>
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#include <memory>
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#include <mutex>
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#include <set>
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#include <string>
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#include <thread>
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#include <android-base/file.h>
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#include <android-base/logging.h>
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#include <android-base/properties.h>
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#include <android-base/stringprintf.h>
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#include <android-base/strings.h>
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#include <cutils/android_filesystem_config.h>
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#include <processgroup/processgroup.h>
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#include <task_profiles.h>
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using android::base::GetBoolProperty;
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using android::base::StartsWith;
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using android::base::StringPrintf;
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using android::base::WriteStringToFile;
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using namespace std::chrono_literals;
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#define PROCESSGROUP_CGROUP_PROCS_FILE "/cgroup.procs"
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bool CgroupGetControllerPath(const std::string& cgroup_name, std::string* path) {
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auto controller = CgroupMap::GetInstance().FindController(cgroup_name);
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if (!controller.HasValue()) {
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return false;
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}
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if (path) {
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*path = controller.path();
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}
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return true;
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}
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bool CgroupGetAttributePath(const std::string& attr_name, std::string* path) {
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const TaskProfiles& tp = TaskProfiles::GetInstance();
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const ProfileAttribute* attr = tp.GetAttribute(attr_name);
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if (attr == nullptr) {
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return false;
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}
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if (path) {
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*path = StringPrintf("%s/%s", attr->controller()->path(), attr->file_name().c_str());
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}
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return true;
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}
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bool CgroupGetAttributePathForTask(const std::string& attr_name, int tid, std::string* path) {
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const TaskProfiles& tp = TaskProfiles::GetInstance();
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const ProfileAttribute* attr = tp.GetAttribute(attr_name);
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if (attr == nullptr) {
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return false;
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}
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if (!attr->GetPathForTask(tid, path)) {
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PLOG(ERROR) << "Failed to find cgroup for tid " << tid;
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return false;
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}
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return true;
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}
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bool UsePerAppMemcg() {
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bool low_ram_device = GetBoolProperty("ro.config.low_ram", false);
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return GetBoolProperty("ro.config.per_app_memcg", low_ram_device);
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}
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static bool isMemoryCgroupSupported() {
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static bool memcg_supported = CgroupMap::GetInstance().FindController("memory").IsUsable();
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return memcg_supported;
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}
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void DropTaskProfilesResourceCaching() {
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TaskProfiles::GetInstance().DropResourceCaching();
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}
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bool SetProcessProfiles(uid_t uid, pid_t pid, const std::vector<std::string>& profiles) {
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return TaskProfiles::GetInstance().SetProcessProfiles(uid, pid, profiles);
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}
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bool SetTaskProfiles(int tid, const std::vector<std::string>& profiles, bool use_fd_cache) {
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return TaskProfiles::GetInstance().SetTaskProfiles(tid, profiles, use_fd_cache);
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}
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static std::string ConvertUidToPath(const char* cgroup, uid_t uid) {
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return StringPrintf("%s/uid_%d", cgroup, uid);
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}
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static std::string ConvertUidPidToPath(const char* cgroup, uid_t uid, int pid) {
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return StringPrintf("%s/uid_%d/pid_%d", cgroup, uid, pid);
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}
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static int RemoveProcessGroup(const char* cgroup, uid_t uid, int pid, unsigned int retries) {
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int ret = 0;
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auto uid_pid_path = ConvertUidPidToPath(cgroup, uid, pid);
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auto uid_path = ConvertUidToPath(cgroup, uid);
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if (retries == 0) {
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retries = 1;
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}
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while (retries--) {
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ret = rmdir(uid_pid_path.c_str());
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if (!ret || errno != EBUSY) break;
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std::this_thread::sleep_for(5ms);
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}
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// With the exception of boot or shutdown, system uid_ folders are always populated. Spinning
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// here would needlessly delay most pid removals. Additionally, once empty a uid_ cgroup won't
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// have processes hanging on it (we've already spun for all its pid_), so there's no need to
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// spin anyway.
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rmdir(uid_path.c_str());
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return ret;
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}
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static bool RemoveUidProcessGroups(const std::string& uid_path) {
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std::unique_ptr<DIR, decltype(&closedir)> uid(opendir(uid_path.c_str()), closedir);
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bool empty = true;
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if (uid != NULL) {
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dirent* dir;
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while ((dir = readdir(uid.get())) != nullptr) {
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if (dir->d_type != DT_DIR) {
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continue;
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}
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if (!StartsWith(dir->d_name, "pid_")) {
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continue;
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}
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auto path = StringPrintf("%s/%s", uid_path.c_str(), dir->d_name);
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LOG(VERBOSE) << "Removing " << path;
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if (rmdir(path.c_str()) == -1) {
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if (errno != EBUSY) {
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PLOG(WARNING) << "Failed to remove " << path;
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}
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empty = false;
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}
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}
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}
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return empty;
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}
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void removeAllProcessGroups() {
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LOG(VERBOSE) << "removeAllProcessGroups()";
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std::vector<std::string> cgroups;
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std::string path;
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if (CgroupGetControllerPath(CGROUPV2_CONTROLLER_NAME, &path)) {
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cgroups.push_back(path);
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}
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if (CgroupGetControllerPath("memory", &path)) {
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cgroups.push_back(path + "/apps");
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}
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for (std::string cgroup_root_path : cgroups) {
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std::unique_ptr<DIR, decltype(&closedir)> root(opendir(cgroup_root_path.c_str()), closedir);
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if (root == NULL) {
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PLOG(ERROR) << "Failed to open " << cgroup_root_path;
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} else {
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dirent* dir;
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while ((dir = readdir(root.get())) != nullptr) {
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if (dir->d_type != DT_DIR) {
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continue;
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}
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if (!StartsWith(dir->d_name, "uid_")) {
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continue;
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}
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auto path = StringPrintf("%s/%s", cgroup_root_path.c_str(), dir->d_name);
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if (!RemoveUidProcessGroups(path)) {
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LOG(VERBOSE) << "Skip removing " << path;
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continue;
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}
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LOG(VERBOSE) << "Removing " << path;
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if (rmdir(path.c_str()) == -1 && errno != EBUSY) {
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PLOG(WARNING) << "Failed to remove " << path;
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}
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}
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}
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}
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}
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/**
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* Process groups are primarily created by the Zygote, meaning that uid/pid groups are created by
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* the user root. Ownership for the newly created cgroup and all of its files must thus be
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* transferred for the user/group passed as uid/gid before system_server can properly access them.
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*/
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static bool MkdirAndChown(const std::string& path, mode_t mode, uid_t uid, gid_t gid) {
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if (mkdir(path.c_str(), mode) == -1 && errno != EEXIST) {
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return false;
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}
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auto dir = std::unique_ptr<DIR, decltype(&closedir)>(opendir(path.c_str()), closedir);
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if (dir == NULL) {
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PLOG(ERROR) << "opendir failed for " << path;
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goto err;
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}
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struct dirent* dir_entry;
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while ((dir_entry = readdir(dir.get()))) {
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if (!strcmp("..", dir_entry->d_name)) {
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continue;
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}
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std::string file_path = path + "/" + dir_entry->d_name;
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if (lchown(file_path.c_str(), uid, gid) < 0) {
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PLOG(ERROR) << "lchown failed for " << file_path;
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goto err;
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}
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if (fchmodat(AT_FDCWD, file_path.c_str(), mode, AT_SYMLINK_NOFOLLOW) != 0) {
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PLOG(ERROR) << "fchmodat failed for " << file_path;
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goto err;
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}
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}
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return true;
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err:
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int saved_errno = errno;
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rmdir(path.c_str());
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errno = saved_errno;
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return false;
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}
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// Returns number of processes killed on success
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// Returns 0 if there are no processes in the process cgroup left to kill
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// Returns -1 on error
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static int DoKillProcessGroupOnce(const char* cgroup, uid_t uid, int initialPid, int signal) {
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auto path = ConvertUidPidToPath(cgroup, uid, initialPid) + PROCESSGROUP_CGROUP_PROCS_FILE;
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std::unique_ptr<FILE, decltype(&fclose)> fd(fopen(path.c_str(), "re"), fclose);
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if (!fd) {
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if (errno == ENOENT) {
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// This happens when process is already dead
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return 0;
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}
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PLOG(WARNING) << "Failed to open process cgroup uid " << uid << " pid " << initialPid;
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return -1;
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}
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// We separate all of the pids in the cgroup into those pids that are also the leaders of
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// process groups (stored in the pgids set) and those that are not (stored in the pids set).
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std::set<pid_t> pgids;
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pgids.emplace(initialPid);
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std::set<pid_t> pids;
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pid_t pid;
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int processes = 0;
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while (fscanf(fd.get(), "%d\n", &pid) == 1 && pid >= 0) {
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processes++;
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if (pid == 0) {
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// Should never happen... but if it does, trying to kill this
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// will boomerang right back and kill us! Let's not let that happen.
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LOG(WARNING) << "Yikes, we've been told to kill pid 0! How about we don't do that?";
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continue;
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}
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pid_t pgid = getpgid(pid);
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if (pgid == -1) PLOG(ERROR) << "getpgid(" << pid << ") failed";
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if (pgid == pid) {
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pgids.emplace(pid);
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} else {
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pids.emplace(pid);
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}
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}
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// Erase all pids that will be killed when we kill the process groups.
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for (auto it = pids.begin(); it != pids.end();) {
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pid_t pgid = getpgid(*it);
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if (pgids.count(pgid) == 1) {
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it = pids.erase(it);
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} else {
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++it;
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}
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}
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// Kill all process groups.
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for (const auto pgid : pgids) {
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LOG(VERBOSE) << "Killing process group " << -pgid << " in uid " << uid
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<< " as part of process cgroup " << initialPid;
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if (kill(-pgid, signal) == -1 && errno != ESRCH) {
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PLOG(WARNING) << "kill(" << -pgid << ", " << signal << ") failed";
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}
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}
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// Kill remaining pids.
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for (const auto pid : pids) {
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LOG(VERBOSE) << "Killing pid " << pid << " in uid " << uid << " as part of process cgroup "
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<< initialPid;
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if (kill(pid, signal) == -1 && errno != ESRCH) {
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PLOG(WARNING) << "kill(" << pid << ", " << signal << ") failed";
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}
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}
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return feof(fd.get()) ? processes : -1;
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}
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static int KillProcessGroup(uid_t uid, int initialPid, int signal, int retries,
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int* max_processes) {
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std::string hierarchy_root_path;
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CgroupGetControllerPath(CGROUPV2_CONTROLLER_NAME, &hierarchy_root_path);
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const char* cgroup = hierarchy_root_path.c_str();
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std::chrono::steady_clock::time_point start = std::chrono::steady_clock::now();
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if (max_processes != nullptr) {
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*max_processes = 0;
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}
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int retry = retries;
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int processes;
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while ((processes = DoKillProcessGroupOnce(cgroup, uid, initialPid, signal)) > 0) {
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if (max_processes != nullptr && processes > *max_processes) {
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*max_processes = processes;
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}
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LOG(VERBOSE) << "Killed " << processes << " processes for processgroup " << initialPid;
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if (retry > 0) {
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std::this_thread::sleep_for(5ms);
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--retry;
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} else {
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break;
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}
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}
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if (processes < 0) {
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PLOG(ERROR) << "Error encountered killing process cgroup uid " << uid << " pid "
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<< initialPid;
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return -1;
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}
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std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
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auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
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// We only calculate the number of 'processes' when killing the processes.
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// In the retries == 0 case, we only kill the processes once and therefore
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// will not have waited then recalculated how many processes are remaining
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// after the first signals have been sent.
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// Logging anything regarding the number of 'processes' here does not make sense.
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if (processes == 0) {
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if (retries > 0) {
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LOG(INFO) << "Successfully killed process cgroup uid " << uid << " pid " << initialPid
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<< " in " << static_cast<int>(ms) << "ms";
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}
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int err = RemoveProcessGroup(cgroup, uid, initialPid, retries);
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if (isMemoryCgroupSupported() && UsePerAppMemcg()) {
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std::string memory_path;
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CgroupGetControllerPath("memory", &memory_path);
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memory_path += "/apps";
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if (RemoveProcessGroup(memory_path.c_str(), uid, initialPid, retries)) return -1;
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}
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return err;
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} else {
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if (retries > 0) {
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LOG(ERROR) << "Failed to kill process cgroup uid " << uid << " pid " << initialPid
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<< " in " << static_cast<int>(ms) << "ms, " << processes
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<< " processes remain";
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}
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return -1;
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}
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}
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int killProcessGroup(uid_t uid, int initialPid, int signal, int* max_processes) {
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return KillProcessGroup(uid, initialPid, signal, 40 /*retries*/, max_processes);
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}
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int killProcessGroupOnce(uid_t uid, int initialPid, int signal, int* max_processes) {
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return KillProcessGroup(uid, initialPid, signal, 0 /*retries*/, max_processes);
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}
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static int createProcessGroupInternal(uid_t uid, int initialPid, std::string cgroup) {
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auto uid_path = ConvertUidToPath(cgroup.c_str(), uid);
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if (!MkdirAndChown(uid_path, 0750, AID_SYSTEM, AID_SYSTEM)) {
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PLOG(ERROR) << "Failed to make and chown " << uid_path;
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return -errno;
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}
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auto uid_pid_path = ConvertUidPidToPath(cgroup.c_str(), uid, initialPid);
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if (!MkdirAndChown(uid_pid_path, 0750, AID_SYSTEM, AID_SYSTEM)) {
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PLOG(ERROR) << "Failed to make and chown " << uid_pid_path;
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return -errno;
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}
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auto uid_pid_procs_file = uid_pid_path + PROCESSGROUP_CGROUP_PROCS_FILE;
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int ret = 0;
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if (!WriteStringToFile(std::to_string(initialPid), uid_pid_procs_file)) {
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ret = -errno;
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PLOG(ERROR) << "Failed to write '" << initialPid << "' to " << uid_pid_procs_file;
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}
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return ret;
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}
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int createProcessGroup(uid_t uid, int initialPid, bool memControl) {
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std::string cgroup;
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if (memControl && !UsePerAppMemcg()) {
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PLOG(ERROR) << "service memory controls are used without per-process memory cgroup support";
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return -EINVAL;
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}
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if (isMemoryCgroupSupported() && UsePerAppMemcg()) {
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CgroupGetControllerPath("memory", &cgroup);
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cgroup += "/apps";
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int ret = createProcessGroupInternal(uid, initialPid, cgroup);
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if (ret != 0) {
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return ret;
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}
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}
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CgroupGetControllerPath(CGROUPV2_CONTROLLER_NAME, &cgroup);
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return createProcessGroupInternal(uid, initialPid, cgroup);
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}
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static bool SetProcessGroupValue(int tid, const std::string& attr_name, int64_t value) {
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if (!isMemoryCgroupSupported()) {
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PLOG(ERROR) << "Memcg is not mounted.";
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return false;
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}
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std::string path;
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if (!CgroupGetAttributePathForTask(attr_name, tid, &path)) {
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PLOG(ERROR) << "Failed to find attribute '" << attr_name << "'";
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return false;
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}
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if (!WriteStringToFile(std::to_string(value), path)) {
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PLOG(ERROR) << "Failed to write '" << value << "' to " << path;
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return false;
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}
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return true;
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}
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bool setProcessGroupSwappiness(uid_t, int pid, int swappiness) {
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return SetProcessGroupValue(pid, "MemSwappiness", swappiness);
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}
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bool setProcessGroupSoftLimit(uid_t, int pid, int64_t soft_limit_in_bytes) {
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return SetProcessGroupValue(pid, "MemSoftLimit", soft_limit_in_bytes);
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}
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bool setProcessGroupLimit(uid_t, int pid, int64_t limit_in_bytes) {
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return SetProcessGroupValue(pid, "MemLimit", limit_in_bytes);
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}
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