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platform_system_core/libprocessgroup/processgroup.cpp
Bart Van Assche f32c4ecebb libprocessgroup: Provide SetProcessProfiles() and SetTaskProfiles() alternatives 
Provide alternative versions that do not force callers to create
std::string objects. This patch has the intended side-effect that all
callers that pass a {string} initializer list to the 'profiles' argument
now call an std::initializer_list<> overload instead of the const
std::vector<std::string>& overload.

Additionally, add std::function<> arguments instead of calling
ExecuteForProcess() or ExecuteForTask() directly to make it easier to
write unit tests for SetTaskProfiles() and SetProcessProfiles().

Bug: 213617178
Change-Id: Ica61e944a66a17178ee43a113b8ca082f7eb834b
Signed-off-by: Bart Van Assche <bvanassche@google.com>
2022-08-19 07:06:30 -07:00

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/*
* Copyright 2014 Google, Inc
*
* 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 <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <chrono>
#include <map>
#include <memory>
#include <mutex>
#include <set>
#include <string>
#include <thread>
#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 <cutils/android_filesystem_config.h>
#include <processgroup/processgroup.h>
#include <task_profiles.h>
using android::base::GetBoolProperty;
using android::base::StartsWith;
using android::base::StringPrintf;
using android::base::WriteStringToFile;
using namespace std::chrono_literals;
#define PROCESSGROUP_CGROUP_PROCS_FILE "/cgroup.procs"
bool CgroupGetControllerPath(const std::string& cgroup_name, std::string* path) {
auto controller = CgroupMap::GetInstance().FindController(cgroup_name);
if (!controller.HasValue()) {
return false;
}
if (path) {
*path = controller.path();
}
return true;
}
static bool CgroupGetMemcgAppsPath(std::string* path) {
CgroupController controller = CgroupMap::GetInstance().FindController("memory");
if (!controller.HasValue()) {
return false;
}
if (path) {
*path = controller.path();
if (controller.version() == 1) {
*path += "/apps";
}
}
return true;
}
bool CgroupGetControllerFromPath(const std::string& path, std::string* cgroup_name) {
auto controller = CgroupMap::GetInstance().FindControllerByPath(path);
if (!controller.HasValue()) {
return false;
}
if (cgroup_name) {
*cgroup_name = controller.name();
}
return true;
}
bool CgroupGetAttributePath(const std::string& attr_name, std::string* path) {
const TaskProfiles& tp = TaskProfiles::GetInstance();
const IProfileAttribute* attr = tp.GetAttribute(attr_name);
if (attr == nullptr) {
return false;
}
if (path) {
*path = StringPrintf("%s/%s", attr->controller()->path(), attr->file_name().c_str());
}
return true;
}
bool CgroupGetAttributePathForTask(const std::string& attr_name, int tid, std::string* path) {
const TaskProfiles& tp = TaskProfiles::GetInstance();
const IProfileAttribute* attr = tp.GetAttribute(attr_name);
if (attr == nullptr) {
return false;
}
if (!attr->GetPathForTask(tid, path)) {
PLOG(ERROR) << "Failed to find cgroup for tid " << tid;
return false;
}
return true;
}
bool UsePerAppMemcg() {
bool low_ram_device = GetBoolProperty("ro.config.low_ram", false);
return GetBoolProperty("ro.config.per_app_memcg", low_ram_device);
}
static bool isMemoryCgroupSupported() {
static bool memcg_supported = CgroupMap::GetInstance().FindController("memory").IsUsable();
return memcg_supported;
}
void DropTaskProfilesResourceCaching() {
TaskProfiles::GetInstance().DropResourceCaching(ProfileAction::RCT_TASK);
TaskProfiles::GetInstance().DropResourceCaching(ProfileAction::RCT_PROCESS);
}
bool SetProcessProfiles(uid_t uid, pid_t pid, const std::vector<std::string>& profiles) {
return TaskProfiles::GetInstance().SetProcessProfiles(
uid, pid, std::span<const std::string>(profiles), false);
}
bool SetProcessProfiles(uid_t uid, pid_t pid, std::initializer_list<std::string_view> profiles) {
return TaskProfiles::GetInstance().SetProcessProfiles(
uid, pid, std::span<const std::string_view>(profiles), false);
}
bool SetProcessProfiles(uid_t uid, pid_t pid, std::span<const std::string_view> profiles) {
return TaskProfiles::GetInstance().SetProcessProfiles(uid, pid, profiles, false);
}
bool SetProcessProfilesCached(uid_t uid, pid_t pid, const std::vector<std::string>& profiles) {
return TaskProfiles::GetInstance().SetProcessProfiles(
uid, pid, std::span<const std::string>(profiles), true);
}
bool SetTaskProfiles(int tid, const std::vector<std::string>& profiles, bool use_fd_cache) {
return TaskProfiles::GetInstance().SetTaskProfiles(tid, std::span<const std::string>(profiles),
use_fd_cache);
}
bool SetTaskProfiles(int tid, std::initializer_list<std::string_view> profiles, bool use_fd_cache) {
return TaskProfiles::GetInstance().SetTaskProfiles(
tid, std::span<const std::string_view>(profiles), use_fd_cache);
}
bool SetTaskProfiles(int tid, std::span<const std::string_view> profiles, bool use_fd_cache) {
return TaskProfiles::GetInstance().SetTaskProfiles(tid, profiles, use_fd_cache);
}
// C wrapper for SetProcessProfiles.
// No need to have this in the header file because this function is specifically for crosvm. Crosvm
// which is written in Rust has its own declaration of this foreign function and doesn't rely on the
// header. See
// https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3574427/5/src/linux/android.rs#12
extern "C" bool android_set_process_profiles(uid_t uid, pid_t pid, size_t num_profiles,
const char* profiles[]) {
std::vector<std::string_view> profiles_;
profiles_.reserve(num_profiles);
for (size_t i = 0; i < num_profiles; i++) {
profiles_.emplace_back(profiles[i]);
}
return SetProcessProfiles(uid, pid, std::span<const std::string_view>(profiles_));
}
static std::string ConvertUidToPath(const char* cgroup, uid_t uid) {
return StringPrintf("%s/uid_%d", cgroup, uid);
}
static std::string ConvertUidPidToPath(const char* cgroup, uid_t uid, int pid) {
return StringPrintf("%s/uid_%d/pid_%d", cgroup, uid, pid);
}
static int RemoveProcessGroup(const char* cgroup, uid_t uid, int pid, unsigned int retries) {
int ret = 0;
auto uid_pid_path = ConvertUidPidToPath(cgroup, uid, pid);
auto uid_path = ConvertUidToPath(cgroup, uid);
while (retries--) {
ret = rmdir(uid_pid_path.c_str());
if (!ret || errno != EBUSY) break;
std::this_thread::sleep_for(5ms);
}
return ret;
}
static bool RemoveUidProcessGroups(const std::string& uid_path, bool empty_only) {
std::unique_ptr<DIR, decltype(&closedir)> uid(opendir(uid_path.c_str()), closedir);
bool empty = true;
if (uid != NULL) {
dirent* dir;
while ((dir = readdir(uid.get())) != nullptr) {
if (dir->d_type != DT_DIR) {
continue;
}
if (!StartsWith(dir->d_name, "pid_")) {
continue;
}
auto path = StringPrintf("%s/%s", uid_path.c_str(), dir->d_name);
if (empty_only) {
struct stat st;
auto procs_file = StringPrintf("%s/%s", path.c_str(),
PROCESSGROUP_CGROUP_PROCS_FILE);
if (stat(procs_file.c_str(), &st) == -1) {
PLOG(ERROR) << "Failed to get stats for " << procs_file;
continue;
}
if (st.st_size > 0) {
// skip non-empty groups
LOG(VERBOSE) << "Skipping non-empty group " << path;
empty = false;
continue;
}
}
LOG(VERBOSE) << "Removing " << path;
if (rmdir(path.c_str()) == -1) {
if (errno != EBUSY) {
PLOG(WARNING) << "Failed to remove " << path;
}
empty = false;
}
}
}
return empty;
}
void removeAllProcessGroupsInternal(bool empty_only) {
std::vector<std::string> cgroups;
std::string path, memcg_apps_path;
if (CgroupGetControllerPath(CGROUPV2_CONTROLLER_NAME, &path)) {
cgroups.push_back(path);
}
if (CgroupGetMemcgAppsPath(&memcg_apps_path) && memcg_apps_path != path) {
cgroups.push_back(memcg_apps_path);
}
for (std::string cgroup_root_path : cgroups) {
std::unique_ptr<DIR, decltype(&closedir)> root(opendir(cgroup_root_path.c_str()), closedir);
if (root == NULL) {
PLOG(ERROR) << __func__ << " failed to open " << cgroup_root_path;
} else {
dirent* dir;
while ((dir = readdir(root.get())) != nullptr) {
if (dir->d_type != DT_DIR) {
continue;
}
if (!StartsWith(dir->d_name, "uid_")) {
continue;
}
auto path = StringPrintf("%s/%s", cgroup_root_path.c_str(), dir->d_name);
if (!RemoveUidProcessGroups(path, empty_only)) {
LOG(VERBOSE) << "Skip removing " << path;
continue;
}
LOG(VERBOSE) << "Removing " << path;
if (rmdir(path.c_str()) == -1 && errno != EBUSY) {
PLOG(WARNING) << "Failed to remove " << path;
}
}
}
}
}
void removeAllProcessGroups() {
LOG(VERBOSE) << "removeAllProcessGroups()";
removeAllProcessGroupsInternal(false);
}
void removeAllEmptyProcessGroups() {
LOG(VERBOSE) << "removeAllEmptyProcessGroups()";
removeAllProcessGroupsInternal(true);
}
/**
* Process groups are primarily created by the Zygote, meaning that uid/pid groups are created by
* the user root. Ownership for the newly created cgroup and all of its files must thus be
* transferred for the user/group passed as uid/gid before system_server can properly access them.
*/
static bool MkdirAndChown(const std::string& path, mode_t mode, uid_t uid, gid_t gid) {
if (mkdir(path.c_str(), mode) == -1) {
if (errno == EEXIST) {
// Directory already exists and permissions have been set at the time it was created
return true;
}
return false;
}
auto dir = std::unique_ptr<DIR, decltype(&closedir)>(opendir(path.c_str()), closedir);
if (dir == NULL) {
PLOG(ERROR) << "opendir failed for " << path;
goto err;
}
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 (lchown(file_path.c_str(), uid, gid) < 0) {
PLOG(ERROR) << "lchown failed for " << file_path;
goto err;
}
if (fchmodat(AT_FDCWD, file_path.c_str(), mode, AT_SYMLINK_NOFOLLOW) != 0) {
PLOG(ERROR) << "fchmodat failed for " << file_path;
goto err;
}
}
return true;
err:
int saved_errno = errno;
rmdir(path.c_str());
errno = saved_errno;
return false;
}
// Returns number of processes killed on success
// Returns 0 if there are no processes in the process cgroup left to kill
// Returns -1 on error
static int DoKillProcessGroupOnce(const char* cgroup, uid_t uid, int initialPid, int signal) {
auto path = ConvertUidPidToPath(cgroup, uid, initialPid) + PROCESSGROUP_CGROUP_PROCS_FILE;
std::unique_ptr<FILE, decltype(&fclose)> fd(fopen(path.c_str(), "re"), fclose);
if (!fd) {
if (errno == ENOENT) {
// This happens when process is already dead
return 0;
}
PLOG(WARNING) << __func__ << " failed to open process cgroup uid " << uid << " pid "
<< initialPid;
return -1;
}
// We separate all of the pids in the cgroup into those pids that are also the leaders of
// process groups (stored in the pgids set) and those that are not (stored in the pids set).
std::set<pid_t> pgids;
pgids.emplace(initialPid);
std::set<pid_t> pids;
pid_t pid;
int processes = 0;
while (fscanf(fd.get(), "%d\n", &pid) == 1 && pid >= 0) {
processes++;
if (pid == 0) {
// Should never happen... but if it does, trying to kill this
// will boomerang right back and kill us! Let's not let that happen.
LOG(WARNING) << "Yikes, we've been told to kill pid 0! How about we don't do that?";
continue;
}
pid_t pgid = getpgid(pid);
if (pgid == -1) PLOG(ERROR) << "getpgid(" << pid << ") failed";
if (pgid == pid) {
pgids.emplace(pid);
} else {
pids.emplace(pid);
}
}
// Erase all pids that will be killed when we kill the process groups.
for (auto it = pids.begin(); it != pids.end();) {
pid_t pgid = getpgid(*it);
if (pgids.count(pgid) == 1) {
it = pids.erase(it);
} else {
++it;
}
}
// Kill all process groups.
for (const auto pgid : pgids) {
LOG(VERBOSE) << "Killing process group " << -pgid << " in uid " << uid
<< " as part of process cgroup " << initialPid;
if (kill(-pgid, signal) == -1 && errno != ESRCH) {
PLOG(WARNING) << "kill(" << -pgid << ", " << signal << ") failed";
}
}
// Kill remaining pids.
for (const auto pid : pids) {
LOG(VERBOSE) << "Killing pid " << pid << " in uid " << uid << " as part of process cgroup "
<< initialPid;
if (kill(pid, signal) == -1 && errno != ESRCH) {
PLOG(WARNING) << "kill(" << pid << ", " << signal << ") failed";
}
}
return feof(fd.get()) ? processes : -1;
}
static int KillProcessGroup(uid_t uid, int initialPid, int signal, int retries,
int* max_processes) {
std::string hierarchy_root_path;
CgroupGetControllerPath(CGROUPV2_CONTROLLER_NAME, &hierarchy_root_path);
const char* cgroup = hierarchy_root_path.c_str();
std::chrono::steady_clock::time_point start = std::chrono::steady_clock::now();
if (max_processes != nullptr) {
*max_processes = 0;
}
int retry = retries;
int processes;
while ((processes = DoKillProcessGroupOnce(cgroup, uid, initialPid, signal)) > 0) {
if (max_processes != nullptr && processes > *max_processes) {
*max_processes = processes;
}
LOG(VERBOSE) << "Killed " << processes << " processes for processgroup " << initialPid;
if (retry > 0) {
std::this_thread::sleep_for(5ms);
--retry;
} else {
break;
}
}
if (processes < 0) {
PLOG(ERROR) << "Error encountered killing process cgroup uid " << uid << " pid "
<< initialPid;
return -1;
}
std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
// We only calculate the number of 'processes' when killing the processes.
// In the retries == 0 case, we only kill the processes once and therefore
// will not have waited then recalculated how many processes are remaining
// after the first signals have been sent.
// Logging anything regarding the number of 'processes' here does not make sense.
if (processes == 0) {
if (retries > 0) {
LOG(INFO) << "Successfully killed process cgroup uid " << uid << " pid " << initialPid
<< " in " << static_cast<int>(ms) << "ms";
}
// 400 retries correspond to 2 secs max timeout
int err = RemoveProcessGroup(cgroup, uid, initialPid, 400);
if (isMemoryCgroupSupported() && UsePerAppMemcg()) {
std::string memcg_apps_path;
if (CgroupGetMemcgAppsPath(&memcg_apps_path) &&
RemoveProcessGroup(memcg_apps_path.c_str(), uid, initialPid, 400) < 0) {
return -1;
}
}
return err;
} else {
if (retries > 0) {
LOG(ERROR) << "Failed to kill process cgroup uid " << uid << " pid " << initialPid
<< " in " << static_cast<int>(ms) << "ms, " << processes
<< " processes remain";
}
return -1;
}
}
int killProcessGroup(uid_t uid, int initialPid, int signal, int* max_processes) {
return KillProcessGroup(uid, initialPid, signal, 40 /*retries*/, max_processes);
}
int killProcessGroupOnce(uid_t uid, int initialPid, int signal, int* max_processes) {
return KillProcessGroup(uid, initialPid, signal, 0 /*retries*/, max_processes);
}
static int createProcessGroupInternal(uid_t uid, int initialPid, std::string cgroup,
bool activate_controllers) {
auto uid_path = ConvertUidToPath(cgroup.c_str(), uid);
struct stat cgroup_stat;
mode_t cgroup_mode = 0750;
uid_t cgroup_uid = AID_SYSTEM;
gid_t cgroup_gid = AID_SYSTEM;
int ret = 0;
if (stat(cgroup.c_str(), &cgroup_stat) < 0) {
PLOG(ERROR) << "Failed to get stats for " << cgroup;
} else {
cgroup_mode = cgroup_stat.st_mode;
cgroup_uid = cgroup_stat.st_uid;
cgroup_gid = cgroup_stat.st_gid;
}
if (!MkdirAndChown(uid_path, cgroup_mode, cgroup_uid, cgroup_gid)) {
PLOG(ERROR) << "Failed to make and chown " << uid_path;
return -errno;
}
if (activate_controllers) {
ret = CgroupMap::GetInstance().ActivateControllers(uid_path);
if (ret) {
LOG(ERROR) << "Failed to activate controllers in " << uid_path;
return ret;
}
}
auto uid_pid_path = ConvertUidPidToPath(cgroup.c_str(), uid, initialPid);
if (!MkdirAndChown(uid_pid_path, cgroup_mode, cgroup_uid, cgroup_gid)) {
PLOG(ERROR) << "Failed to make and chown " << uid_pid_path;
return -errno;
}
auto uid_pid_procs_file = uid_pid_path + PROCESSGROUP_CGROUP_PROCS_FILE;
if (!WriteStringToFile(std::to_string(initialPid), uid_pid_procs_file)) {
ret = -errno;
PLOG(ERROR) << "Failed to write '" << initialPid << "' to " << uid_pid_procs_file;
}
return ret;
}
int createProcessGroup(uid_t uid, int initialPid, bool memControl) {
std::string cgroup;
if (memControl && !UsePerAppMemcg()) {
PLOG(ERROR) << "service memory controls are used without per-process memory cgroup support";
return -EINVAL;
}
if (std::string memcg_apps_path;
isMemoryCgroupSupported() && UsePerAppMemcg() && CgroupGetMemcgAppsPath(&memcg_apps_path)) {
// Note by bvanassche: passing 'false' as fourth argument below implies that the v1
// hierarchy is used. It is not clear to me whether the above conditions guarantee that the
// v1 hierarchy is used.
int ret = createProcessGroupInternal(uid, initialPid, memcg_apps_path, false);
if (ret != 0) {
return ret;
}
}
CgroupGetControllerPath(CGROUPV2_CONTROLLER_NAME, &cgroup);
return createProcessGroupInternal(uid, initialPid, cgroup, true);
}
static bool SetProcessGroupValue(int tid, const std::string& attr_name, int64_t value) {
if (!isMemoryCgroupSupported()) {
PLOG(ERROR) << "Memcg is not mounted.";
return false;
}
std::string path;
if (!CgroupGetAttributePathForTask(attr_name, tid, &path)) {
PLOG(ERROR) << "Failed to find attribute '" << attr_name << "'";
return false;
}
if (!WriteStringToFile(std::to_string(value), path)) {
PLOG(ERROR) << "Failed to write '" << value << "' to " << path;
return false;
}
return true;
}
bool setProcessGroupSwappiness(uid_t, int pid, int swappiness) {
return SetProcessGroupValue(pid, "MemSwappiness", swappiness);
}
bool setProcessGroupSoftLimit(uid_t, int pid, int64_t soft_limit_in_bytes) {
return SetProcessGroupValue(pid, "MemSoftLimit", soft_limit_in_bytes);
}
bool setProcessGroupLimit(uid_t, int pid, int64_t limit_in_bytes) {
return SetProcessGroupValue(pid, "MemLimit", limit_in_bytes);
}
bool getAttributePathForTask(const std::string& attr_name, int tid, std::string* path) {
return CgroupGetAttributePathForTask(attr_name, tid, path);
}
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