/*
* Copyright (C) 2015 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_TAG "cmd"
#include <utils/Log.h>
#include <binder/Parcel.h>
#include <binder/ProcessState.h>
#include <binder/IResultReceiver.h>
#include <binder/IServiceManager.h>
#include <binder/IShellCallback.h>
#include <binder/TextOutput.h>
#include <utils/Condition.h>
#include <utils/Mutex.h>
#include <utils/Vector.h>
#include <getopt.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <errno.h>
#include <memory>
#include "selinux/selinux.h"
#include "selinux/android.h"
#define DEBUG 0
using namespace android;
static int sort_func(const String16* lhs, const String16* rhs)
{
return lhs->compare(*rhs);
}
struct SecurityContext_Delete {
void operator()(security_context_t p) const {
freecon(p);
}
};
typedef std::unique_ptr<char[], SecurityContext_Delete> Unique_SecurityContext;
class MyShellCallback : public BnShellCallback
{
public:
bool mActive = true;
virtual int openFile(const String16& path, const String16& seLinuxContext,
const String16& mode) {
String8 path8(path);
char cwd[256];
getcwd(cwd, 256);
String8 fullPath(cwd);
fullPath.appendPath(path8);
if (!mActive) {
aerr << "Open attempt after active for: " << fullPath << endl;
return -EPERM;
}
#if DEBUG
ALOGD("openFile: %s, full=%s", path8.string(), fullPath.string());
#endif
int flags = 0;
bool checkRead = false;
bool checkWrite = false;
if (mode == String16("w")) {
flags = O_WRONLY|O_CREAT|O_TRUNC;
checkWrite = true;
} else if (mode == String16("w+")) {
flags = O_RDWR|O_CREAT|O_TRUNC;
checkRead = checkWrite = true;
} else if (mode == String16("r")) {
flags = O_RDONLY;
checkRead = true;
} else if (mode == String16("r+")) {
flags = O_RDWR;
checkRead = checkWrite = true;
} else {
aerr << "Invalid mode requested: " << mode.string() << endl;
return -EINVAL;
}
int fd = open(fullPath.string(), flags, S_IRWXU|S_IRWXG);
#if DEBUG
ALOGD("openFile: fd=%d", fd);
#endif
if (fd < 0) {
return fd;
}
if (is_selinux_enabled() && seLinuxContext.size() > 0) {
String8 seLinuxContext8(seLinuxContext);
security_context_t tmp = NULL;
getfilecon(fullPath.string(), &tmp);
Unique_SecurityContext context(tmp);
if (checkWrite) {
int accessGranted = selinux_check_access(seLinuxContext8.string(), context.get(),
"file", "write", NULL);
if (accessGranted != 0) {
#if DEBUG
ALOGD("openFile: failed selinux write check!");
#endif
close(fd);
aerr << "System server has no access to write file context " << context.get()
<< " (from path " << fullPath.string() << ", context "
<< seLinuxContext8.string() << ")" << endl;
return -EPERM;
}
}
if (checkRead) {
int accessGranted = selinux_check_access(seLinuxContext8.string(), context.get(),
"file", "read", NULL);
if (accessGranted != 0) {
#if DEBUG
ALOGD("openFile: failed selinux read check!");
#endif
close(fd);
aerr << "System server has no access to read file context " << context.get()
<< " (from path " << fullPath.string() << ", context "
<< seLinuxContext8.string() << ")" << endl;
return -EPERM;
}
}
}
return fd;
}
};
class MyResultReceiver : public BnResultReceiver
{
public:
Mutex mMutex;
Condition mCondition;
bool mHaveResult = false;
int32_t mResult = 0;
virtual void send(int32_t resultCode) {
AutoMutex _l(mMutex);
mResult = resultCode;
mHaveResult = true;
mCondition.signal();
}
int32_t waitForResult() {
AutoMutex _l(mMutex);
while (!mHaveResult) {
mCondition.wait(mMutex);
}
return mResult;
}
};
int main(int argc, char* const argv[])
{
signal(SIGPIPE, SIG_IGN);
sp<ProcessState> proc = ProcessState::self();
// setThreadPoolMaxThreadCount(0) actually tells the kernel it's
// not allowed to spawn any additional threads, but we still spawn
// a binder thread from userspace when we call startThreadPool().
// This is safe because we only have 2 callbacks, neither of which
// block.
// See b/36066697 for rationale
proc->setThreadPoolMaxThreadCount(0);
proc->startThreadPool();
#if DEBUG
ALOGD("cmd: starting");
#endif
sp<IServiceManager> sm = defaultServiceManager();
fflush(stdout);
if (sm == NULL) {
ALOGW("Unable to get default service manager!");
aerr << "cmd: Unable to get default service manager!" << endl;
return 20;
}
if (argc == 1) {
aerr << "cmd: No service specified; use -l to list all services" << endl;
return 20;
}
if ((argc == 2) && (strcmp(argv[1], "-l") == 0)) {
Vector<String16> services = sm->listServices();
services.sort(sort_func);
aout << "Currently running services:" << endl;
for (size_t i=0; i<services.size(); i++) {
sp<IBinder> service = sm->checkService(services[i]);
if (service != NULL) {
aout << " " << services[i] << endl;
}
}
return 0;
}
Vector<String16> args;
for (int i=2; i<argc; i++) {
args.add(String16(argv[i]));
}
String16 cmd = String16(argv[1]);
sp<IBinder> service = sm->checkService(cmd);
if (service == NULL) {
ALOGW("Can't find service %s", argv[1]);
aerr << "cmd: Can't find service: " << argv[1] << endl;
return 20;
}
sp<MyShellCallback> cb = new MyShellCallback();
sp<MyResultReceiver> result = new MyResultReceiver();
#if DEBUG
ALOGD("cmd: Invoking %s in=%d, out=%d, err=%d", argv[1], STDIN_FILENO, STDOUT_FILENO,
STDERR_FILENO);
#endif
// TODO: block until a result is returned to MyResultReceiver.
status_t err = IBinder::shellCommand(service, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, args,
cb, result);
if (err < 0) {
const char* errstr;
switch (err) {
case BAD_TYPE: errstr = "Bad type"; break;
case FAILED_TRANSACTION: errstr = "Failed transaction"; break;
case FDS_NOT_ALLOWED: errstr = "File descriptors not allowed"; break;
case UNEXPECTED_NULL: errstr = "Unexpected null"; break;
default: errstr = strerror(-err); break;
}
ALOGW("Failure calling service %s: %s (%d)", argv[1], errstr, -err);
aout << "cmd: Failure calling service " << argv[1] << ": " << errstr << " ("
<< (-err) << ")" << endl;
return err;
}
cb->mActive = false;
status_t res = result->waitForResult();
#if DEBUG
ALOGD("result=%d", (int)res);
#endif
return res;
}