1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "cmd"
18
19#include <utils/Log.h>
20#include <binder/Parcel.h>
21#include <binder/ProcessState.h>
22#include <binder/IResultReceiver.h>
23#include <binder/IServiceManager.h>
24#include <binder/IShellCallback.h>
25#include <binder/TextOutput.h>
26#include <utils/Condition.h>
27#include <utils/Mutex.h>
28#include <utils/Vector.h>
29
30#include <getopt.h>
31#include <stdlib.h>
32#include <stdio.h>
33#include <string.h>
34#include <unistd.h>
35#include <fcntl.h>
36#include <sys/time.h>
37#include <errno.h>
38#include <memory>
39
40#include "selinux/selinux.h"
41#include "selinux/android.h"
42
43#define DEBUG 0
44
45using namespace android;
46
47static int sort_func(const String16* lhs, const String16* rhs)
48{
49    return lhs->compare(*rhs);
50}
51
52struct SecurityContext_Delete {
53    void operator()(security_context_t p) const {
54        freecon(p);
55    }
56};
57typedef std::unique_ptr<char[], SecurityContext_Delete> Unique_SecurityContext;
58
59class MyShellCallback : public BnShellCallback
60{
61public:
62    bool mActive = true;
63
64    virtual int openFile(const String16& path, const String16& seLinuxContext,
65            const String16& mode) {
66        String8 path8(path);
67        char cwd[256];
68        getcwd(cwd, 256);
69        String8 fullPath(cwd);
70        fullPath.appendPath(path8);
71        if (!mActive) {
72            aerr << "Open attempt after active for: " << fullPath << endl;
73            return -EPERM;
74        }
75#if DEBUG
76        ALOGD("openFile: %s, full=%s", path8.string(), fullPath.string());
77#endif
78        int flags = 0;
79        bool checkRead = false;
80        bool checkWrite = false;
81        if (mode == String16("w")) {
82            flags = O_WRONLY|O_CREAT|O_TRUNC;
83            checkWrite = true;
84        } else if (mode == String16("w+")) {
85            flags = O_RDWR|O_CREAT|O_TRUNC;
86            checkRead = checkWrite = true;
87        } else if (mode == String16("r")) {
88            flags = O_RDONLY;
89            checkRead = true;
90        } else if (mode == String16("r+")) {
91            flags = O_RDWR;
92            checkRead = checkWrite = true;
93        } else {
94            aerr << "Invalid mode requested: " << mode.string() << endl;
95            return -EINVAL;
96        }
97        int fd = open(fullPath.string(), flags, S_IRWXU|S_IRWXG);
98#if DEBUG
99        ALOGD("openFile: fd=%d", fd);
100#endif
101        if (fd < 0) {
102            return fd;
103        }
104        if (is_selinux_enabled() && seLinuxContext.size() > 0) {
105            String8 seLinuxContext8(seLinuxContext);
106            security_context_t tmp = NULL;
107            getfilecon(fullPath.string(), &tmp);
108            Unique_SecurityContext context(tmp);
109            if (checkWrite) {
110                int accessGranted = selinux_check_access(seLinuxContext8.string(), context.get(),
111                        "file", "write", NULL);
112                if (accessGranted != 0) {
113#if DEBUG
114                    ALOGD("openFile: failed selinux write check!");
115#endif
116                    close(fd);
117                    aerr << "System server has no access to write file context " << context.get()
118                            << " (from path " << fullPath.string() << ", context "
119                            << seLinuxContext8.string() << ")" << endl;
120                    return -EPERM;
121                }
122            }
123            if (checkRead) {
124                int accessGranted = selinux_check_access(seLinuxContext8.string(), context.get(),
125                        "file", "read", NULL);
126                if (accessGranted != 0) {
127#if DEBUG
128                    ALOGD("openFile: failed selinux read check!");
129#endif
130                    close(fd);
131                    aerr << "System server has no access to read file context " << context.get()
132                            << " (from path " << fullPath.string() << ", context "
133                            << seLinuxContext8.string() << ")" << endl;
134                    return -EPERM;
135                }
136            }
137        }
138        return fd;
139    }
140};
141
142class MyResultReceiver : public BnResultReceiver
143{
144public:
145    Mutex mMutex;
146    Condition mCondition;
147    bool mHaveResult = false;
148    int32_t mResult = 0;
149
150    virtual void send(int32_t resultCode) {
151        AutoMutex _l(mMutex);
152        mResult = resultCode;
153        mHaveResult = true;
154        mCondition.signal();
155    }
156
157    int32_t waitForResult() {
158        AutoMutex _l(mMutex);
159        while (!mHaveResult) {
160            mCondition.wait(mMutex);
161        }
162        return mResult;
163    }
164};
165
166int main(int argc, char* const argv[])
167{
168    signal(SIGPIPE, SIG_IGN);
169    sp<ProcessState> proc = ProcessState::self();
170    // setThreadPoolMaxThreadCount(0) actually tells the kernel it's
171    // not allowed to spawn any additional threads, but we still spawn
172    // a binder thread from userspace when we call startThreadPool().
173    // This is safe because we only have 2 callbacks, neither of which
174    // block.
175    // See b/36066697 for rationale
176    proc->setThreadPoolMaxThreadCount(0);
177    proc->startThreadPool();
178
179#if DEBUG
180    ALOGD("cmd: starting");
181#endif
182    sp<IServiceManager> sm = defaultServiceManager();
183    fflush(stdout);
184    if (sm == NULL) {
185        ALOGW("Unable to get default service manager!");
186        aerr << "cmd: Unable to get default service manager!" << endl;
187        return 20;
188    }
189
190    if (argc == 1) {
191        aerr << "cmd: No service specified; use -l to list all services" << endl;
192        return 20;
193    }
194
195    if ((argc == 2) && (strcmp(argv[1], "-l") == 0)) {
196        Vector<String16> services = sm->listServices();
197        services.sort(sort_func);
198        aout << "Currently running services:" << endl;
199
200        for (size_t i=0; i<services.size(); i++) {
201            sp<IBinder> service = sm->checkService(services[i]);
202            if (service != NULL) {
203                aout << "  " << services[i] << endl;
204            }
205        }
206        return 0;
207    }
208
209    Vector<String16> args;
210    for (int i=2; i<argc; i++) {
211        args.add(String16(argv[i]));
212    }
213    String16 cmd = String16(argv[1]);
214    sp<IBinder> service = sm->checkService(cmd);
215    if (service == NULL) {
216        ALOGW("Can't find service %s", argv[1]);
217        aerr << "cmd: Can't find service: " << argv[1] << endl;
218        return 20;
219    }
220
221    sp<MyShellCallback> cb = new MyShellCallback();
222    sp<MyResultReceiver> result = new MyResultReceiver();
223
224#if DEBUG
225    ALOGD("cmd: Invoking %s in=%d, out=%d, err=%d", argv[1], STDIN_FILENO, STDOUT_FILENO,
226            STDERR_FILENO);
227#endif
228
229    // TODO: block until a result is returned to MyResultReceiver.
230    status_t err = IBinder::shellCommand(service, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, args,
231            cb, result);
232    if (err < 0) {
233        const char* errstr;
234        switch (err) {
235            case BAD_TYPE: errstr = "Bad type"; break;
236            case FAILED_TRANSACTION: errstr = "Failed transaction"; break;
237            case FDS_NOT_ALLOWED: errstr = "File descriptors not allowed"; break;
238            case UNEXPECTED_NULL: errstr = "Unexpected null"; break;
239            default: errstr = strerror(-err); break;
240        }
241        ALOGW("Failure calling service %s: %s (%d)", argv[1], errstr, -err);
242        aout << "cmd: Failure calling service " << argv[1] << ": " << errstr << " ("
243                << (-err) << ")" << endl;
244        return err;
245    }
246
247    cb->mActive = false;
248    status_t res = result->waitForResult();
249#if DEBUG
250    ALOGD("result=%d", (int)res);
251#endif
252    return res;
253}
254