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/*
* Copyright (C) 2018 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 <errno.h>
#include <error.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <set>
#include <string>
#include <vector>
#include <android-base/file.h>
#include <android-base/parseint.h>
#include <android-base/strings.h>
#include <packagelistparser/packagelistparser.h>
#include <private/android_filesystem_config.h>
#include <scoped_minijail.h>
#include <selinux/android.h>
// simpleperf_app_runner is used to run simpleperf to profile apps with <profileable shell="true">
// on user devices. It works as below:
// simpleperf cmds in shell -> simpleperf_app_runner -> /system/bin/simpleperf in app's context
//
// 1. User types simpleperf cmds in adb shell. If that is to profile an app, simpleperf calls
// /system/bin/simpleperf_app_runner with profiling arguments.
// 2. simpleperf_app_runner checks if the app is profileable_from_shell. Then it switches the
// process to the app's user id / group id, switches secontext to the app's domain, and
// executes /system/bin/simpleperf with profiling arguments.
// 3. /system/bin/simpleperf records profiling data and writes profiling data to a file descriptor
// opened by simpleperf cmds in shell.
struct PackageListCallbackArg {
const char* name;
pkg_info* info;
};
static bool PackageListParseCallback(pkg_info* info, void* userdata) {
PackageListCallbackArg* arg = static_cast<PackageListCallbackArg*>(userdata);
if (strcmp(arg->name, info->name) == 0) {
arg->info = info;
return false;
}
packagelist_free(info);
return true;
}
pkg_info* ReadPackageInfo(const char* pkgname) {
// Switch to package_info gid to read package info.
gid_t old_egid = getegid();
if (setegid(AID_PACKAGE_INFO) == -1) {
error(1, errno, "setegid failed");
}
PackageListCallbackArg arg;
arg.name = pkgname;
arg.info = nullptr;
if (!packagelist_parse(PackageListParseCallback, &arg)) {
error(1, errno, "packagelist_parse failed");
}
if (setegid(old_egid) == -1) {
error(1, errno, "setegid failed");
}
return arg.info;
}
std::vector<gid_t> GetSupplementaryGids(uid_t userAppId) {
std::vector<gid_t> gids;
int size = getgroups(0, &gids[0]);
if (size < 0) {
error(1, errno, "getgroups failed");
}
gids.resize(size);
size = getgroups(size, &gids[0]);
if (size != static_cast<int>(gids.size())) {
error(1, errno, "getgroups failed");
}
// Profile guide compiled oat files (like /data/app/xxx/oat/arm64/base.odex) are not readable
// worldwide (DEXOPT_PUBLIC flag isn't set). To support reading them (needed by simpleperf for
// profiling), add shared app gid to supplementary groups.
gid_t shared_app_gid = userAppId % AID_USER_OFFSET - AID_APP_START + AID_SHARED_GID_START;
gids.push_back(shared_app_gid);
return gids;
}
static void CheckSimpleperfArguments(const char* cmdname, char** args) {
if (strcmp(cmdname, "stat") != 0 && strcmp(cmdname, "record") != 0 &&
strcmp(cmdname, "api-collect") != 0) {
error(1, 0, "cmd isn't allowed: %s", cmdname);
}
std::set<std::string> zero_arg_options = {
"-b", "--csv", "--exit-with-parent", "-g", "--in-app", "--interval-only-values",
"--no-callchain-joiner", "--no-dump-kernel-symbols", "--no-dump-symbols", "--no-inherit",
"--post-unwind=no", "--post-unwind=yes", "--trace-offcpu", "--verbose",
};
std::set<std::string> one_arg_options = {
"-c", "--call-graph", "--callchain-joiner-min-matching-nodes", "--clockid", "--cpu",
"--cpu-percent", "--duration", "-e", "-f", "--group", "--interval", "-j", "--log", "-m",
"-p", "--size-limit", "-t",
};
// options with a file descriptor
std::set<std::string> fd_options = {
"--start_profiling_fd", "--stop-signal-fd", "--out-fd",
};
// options with path from /data/local/tmp/
std::set<std::string> path_options = {
"--symfs", "--tracepoint-events",
};
one_arg_options.insert(fd_options.begin(), fd_options.end());
one_arg_options.insert(path_options.begin(), path_options.end());
for (int i = 0; args[i] != nullptr; ++i) {
if (zero_arg_options.count(args[i])) {
continue;
} else if (one_arg_options.count(args[i])) {
if (args[i + 1] == nullptr) {
error(1, 0, "invalid arg: %s", args[i]);
}
if (fd_options.count(args[i])) {
// Check if the file descriptor is valid.
int fd;
if (!android::base::ParseInt(args[i + 1], &fd) || fd < 3 || fcntl(fd, F_GETFD) == -1) {
error(1, 0, "invalid fd for arg: %s", args[i]);
}
} else if (path_options.count(args[i])) {
std::string path;
if (!android::base::Realpath(args[i + 1], &path) ||
!android::base::StartsWith(path, "/data/local/tmp/")) {
error(1, 0, "invalid path for arg: %s", args[i]);
}
}
++i;
} else {
error(1, 0, "arg isn't allowed: %s", args[i]);
}
}
}
int main(int argc, char* argv[]) {
if (argc < 2) {
error(1, 0, "usage: simpleperf_app_runner package_name simpleperf_cmd simpleperf_cmd_args...");
}
if (argc < 3) {
error(1, 0, "no simpleperf command name");
}
char* pkgname = argv[1];
char* simpleperf_cmdname = argv[2];
int simpleperf_arg_start = 3;
CheckSimpleperfArguments(simpleperf_cmdname, argv + simpleperf_arg_start);
if (getuid() != AID_SHELL && getuid() != AID_ROOT) {
error(1, 0, "program can only run from shell or root");
}
pkg_info* info = ReadPackageInfo(pkgname);
if (info == nullptr) {
error(1, 0, "failed to find package %s", pkgname);
}
if (info->uid < AID_APP_START || info->uid > AID_APP_END) {
error(1, 0, "package isn't an application: %s", pkgname);
}
if (!info->profileable_from_shell) {
error(1, 0, "package isn't profileable from shell: %s", pkgname);
}
// Switch to the app's user id and group id.
uid_t uid = info->uid;
gid_t gid = info->uid;
std::vector<gid_t> supplementary_gids = GetSupplementaryGids(info->uid);
ScopedMinijail j(minijail_new());
minijail_change_uid(j.get(), uid);
minijail_change_gid(j.get(), gid);
minijail_set_supplementary_gids(j.get(), supplementary_gids.size(), &supplementary_gids[0]);
minijail_enter(j.get());
// Switch to the app's selinux context.
if (selinux_android_setcontext(uid, 0, info->seinfo, pkgname) < 0) {
error(1, errno, "couldn't set SELinux security context");
}
// Switch to the app's data directory.
if (TEMP_FAILURE_RETRY(chdir(info->data_dir)) == -1) {
error(1, errno, "couldn't chdir to package's data directory");
}
// Run /system/bin/simpleperf.
std::string simpleperf_in_system_img = "/system/bin/simpleperf";
int new_argc = 4 + argc - simpleperf_arg_start;
char* new_argv[new_argc + 1];
new_argv[0] = &simpleperf_in_system_img[0];
new_argv[1] = simpleperf_cmdname;
std::string app_option = "--app";
new_argv[2] = &app_option[0];
new_argv[3] = pkgname;
for (int i = 4, j = simpleperf_arg_start; j < argc;) {
new_argv[i++] = argv[j++];
}
new_argv[new_argc] = nullptr;
execvp(new_argv[0], new_argv);
error(1, errno, "exec failed");
}
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