file_sync_service.cpp revision 65fe2516b402ed8903f2ce39a86fa0bdc2b263a6 
1/*
2 * Copyright (C) 2007 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 TRACE_TAG SYNC
18
19#include "sysdeps.h"
20#include "file_sync_service.h"
21
22#include <dirent.h>
23#include <errno.h>
24#include <selinux/android.h>
25#include <stdio.h>
26#include <stdlib.h>
27#include <string.h>
28#include <sys/stat.h>
29#include <sys/types.h>
30#include <unistd.h>
31#include <utime.h>
32
33#include "adb.h"
34#include "adb_io.h"
35#include "private/android_filesystem_config.h"
36
37#include <base/stringprintf.h>
38#include <base/strings.h>
39
40static bool should_use_fs_config(const std::string& path) {
41    // TODO: use fs_config to configure permissions on /data.
42    return android::base::StartsWith(path, "/system/") ||
43           android::base::StartsWith(path, "/vendor/") ||
44           android::base::StartsWith(path, "/oem/");
45}
46
47static bool secure_mkdirs(const std::string& path) {
48    uid_t uid = -1;
49    gid_t gid = -1;
50    unsigned int mode = 0775;
51    uint64_t cap = 0;
52
53    if (path[0] != '/') return false;
54
55    std::vector<std::string> path_components = android::base::Split(path, "/");
56    path_components.pop_back(); // For "/system/bin/sh", only create "/system/bin".
57
58    std::string partial_path;
59    for (const auto& path_component : path_components) {
60        if (partial_path.back() != OS_PATH_SEPARATOR) partial_path += OS_PATH_SEPARATOR;
61        partial_path += path_component;
62
63        if (should_use_fs_config(partial_path)) {
64            fs_config(partial_path.c_str(), 1, nullptr, &uid, &gid, &mode, &cap);
65        }
66        if (adb_mkdir(partial_path.c_str(), mode) == -1) {
67            if (errno != EEXIST) {
68                return false;
69            }
70        } else {
71            if (chown(partial_path.c_str(), uid, gid) == -1) {
72                return false;
73            }
74            // Not all filesystems support setting SELinux labels. http://b/23530370.
75            selinux_android_restorecon(partial_path.c_str(), 0);
76        }
77    }
78    return true;
79}
80
81static bool do_stat(int s, const char* path) {
82    syncmsg msg;
83    msg.stat.id = ID_STAT;
84
85    struct stat st;
86    memset(&st, 0, sizeof(st));
87    // TODO: add a way to report that the stat failed!
88    lstat(path, &st);
89    msg.stat.mode = st.st_mode;
90    msg.stat.size = st.st_size;
91    msg.stat.time = st.st_mtime;
92
93    return WriteFdExactly(s, &msg.stat, sizeof(msg.stat));
94}
95
96static bool do_list(int s, const char* path) {
97    dirent* de;
98
99    syncmsg msg;
100    msg.dent.id = ID_DENT;
101
102    std::unique_ptr<DIR, int(*)(DIR*)> d(opendir(path), closedir);
103    if (!d) goto done;
104
105    while ((de = readdir(d.get()))) {
106        std::string filename(android::base::StringPrintf("%s/%s", path, de->d_name));
107
108        struct stat st;
109        if (lstat(filename.c_str(), &st) == 0) {
110            size_t d_name_length = strlen(de->d_name);
111            msg.dent.mode = st.st_mode;
112            msg.dent.size = st.st_size;
113            msg.dent.time = st.st_mtime;
114            msg.dent.namelen = d_name_length;
115
116            if (!WriteFdExactly(s, &msg.dent, sizeof(msg.dent)) ||
117                    !WriteFdExactly(s, de->d_name, d_name_length)) {
118                return false;
119            }
120        }
121    }
122
123done:
124    msg.dent.id = ID_DONE;
125    msg.dent.mode = 0;
126    msg.dent.size = 0;
127    msg.dent.time = 0;
128    msg.dent.namelen = 0;
129    return WriteFdExactly(s, &msg.dent, sizeof(msg.dent));
130}
131
132static bool SendSyncFail(int fd, const std::string& reason) {
133    D("sync: failure: %s", reason.c_str());
134
135    syncmsg msg;
136    msg.data.id = ID_FAIL;
137    msg.data.size = reason.size();
138    return WriteFdExactly(fd, &msg.data, sizeof(msg.data)) && WriteFdExactly(fd, reason);
139}
140
141static bool SendSyncFailErrno(int fd, const std::string& reason) {
142    return SendSyncFail(fd, android::base::StringPrintf("%s: %s", reason.c_str(), strerror(errno)));
143}
144
145static bool handle_send_file(int s, const char* path, uid_t uid,
146                             gid_t gid, mode_t mode, std::vector<char>& buffer, bool do_unlink) {
147    syncmsg msg;
148    unsigned int timestamp = 0;
149
150    int fd = adb_open_mode(path, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, mode);
151    if (fd < 0 && errno == ENOENT) {
152        if (!secure_mkdirs(path)) {
153            SendSyncFailErrno(s, "secure_mkdirs failed");
154            goto fail;
155        }
156        fd = adb_open_mode(path, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, mode);
157    }
158    if (fd < 0 && errno == EEXIST) {
159        fd = adb_open_mode(path, O_WRONLY | O_CLOEXEC, mode);
160    }
161    if (fd < 0) {
162        SendSyncFailErrno(s, "couldn't create file");
163        goto fail;
164    } else {
165        if (fchown(fd, uid, gid) == -1) {
166            SendSyncFailErrno(s, "fchown failed");
167            goto fail;
168        }
169
170        // Not all filesystems support setting SELinux labels. http://b/23530370.
171        selinux_android_restorecon(path, 0);
172
173        // fchown clears the setuid bit - restore it if present.
174        // Ignore the result of calling fchmod. It's not supported
175        // by all filesystems. b/12441485
176        fchmod(fd, mode);
177    }
178
179    while (true) {
180        unsigned int len;
181
182        if (!ReadFdExactly(s, &msg.data, sizeof(msg.data))) goto fail;
183
184        if (msg.data.id != ID_DATA) {
185            if (msg.data.id == ID_DONE) {
186                timestamp = msg.data.size;
187                break;
188            }
189            SendSyncFail(s, "invalid data message");
190            goto fail;
191        }
192        len = msg.data.size;
193        if (len > buffer.size()) { // TODO: resize buffer?
194            SendSyncFail(s, "oversize data message");
195            goto fail;
196        }
197
198        if (!ReadFdExactly(s, &buffer[0], len)) goto fail;
199
200        if (!WriteFdExactly(fd, &buffer[0], len)) {
201            SendSyncFailErrno(s, "write failed");
202            goto fail;
203        }
204    }
205
206    adb_close(fd);
207
208    utimbuf u;
209    u.actime = timestamp;
210    u.modtime = timestamp;
211    utime(path, &u);
212
213    msg.status.id = ID_OKAY;
214    msg.status.msglen = 0;
215    return WriteFdExactly(s, &msg.status, sizeof(msg.status));
216
217fail:
218    if (fd >= 0) adb_close(fd);
219    if (do_unlink) adb_unlink(path);
220    return false;
221}
222
223#if defined(_WIN32)
224extern bool handle_send_link(int s, const std::string& path, std::vector<char>& buffer) __attribute__((error("no symlinks on Windows")));
225#else
226static bool handle_send_link(int s, const std::string& path, std::vector<char>& buffer) {
227    syncmsg msg;
228    unsigned int len;
229    int ret;
230
231    if (!ReadFdExactly(s, &msg.data, sizeof(msg.data))) return false;
232
233    if (msg.data.id != ID_DATA) {
234        SendSyncFail(s, "invalid data message: expected ID_DATA");
235        return false;
236    }
237
238    len = msg.data.size;
239    if (len > buffer.size()) { // TODO: resize buffer?
240        SendSyncFail(s, "oversize data message");
241        return false;
242    }
243    if (!ReadFdExactly(s, &buffer[0], len)) return false;
244
245    ret = symlink(&buffer[0], path.c_str());
246    if (ret && errno == ENOENT) {
247        if (!secure_mkdirs(path)) {
248            SendSyncFailErrno(s, "secure_mkdirs failed");
249            return false;
250        }
251        ret = symlink(&buffer[0], path.c_str());
252    }
253    if (ret) {
254        SendSyncFailErrno(s, "symlink failed");
255        return false;
256    }
257
258    if (!ReadFdExactly(s, &msg.data, sizeof(msg.data))) return false;
259
260    if (msg.data.id == ID_DONE) {
261        msg.status.id = ID_OKAY;
262        msg.status.msglen = 0;
263        if (!WriteFdExactly(s, &msg.status, sizeof(msg.status))) return false;
264    } else {
265        SendFail(s, "invalid data message: expected ID_DONE");
266        return false;
267    }
268
269    return true;
270}
271#endif
272
273static bool do_send(int s, const std::string& spec, std::vector<char>& buffer) {
274    // 'spec' is of the form "/some/path,0755". Break it up.
275    size_t comma = spec.find_last_of(',');
276    if (comma == std::string::npos) {
277        SendFail(s, "missing , in ID_SEND");
278        return false;
279    }
280
281    std::string path = spec.substr(0, comma);
282
283    errno = 0;
284    mode_t mode = strtoul(spec.substr(comma + 1).c_str(), nullptr, 0);
285    if (errno != 0) {
286        SendFail(s, "bad mode");
287        return false;
288    }
289
290    // Don't delete files before copying if they are not "regular" or symlinks.
291    struct stat st;
292    bool do_unlink = (lstat(path.c_str(), &st) == -1) || S_ISREG(st.st_mode) || S_ISLNK(st.st_mode);
293    if (do_unlink) {
294        adb_unlink(path.c_str());
295    }
296
297    if (S_ISLNK(mode)) {
298        return handle_send_link(s, path.c_str(), buffer);
299    }
300
301    // Copy user permission bits to "group" and "other" permissions.
302    mode &= 0777;
303    mode |= ((mode >> 3) & 0070);
304    mode |= ((mode >> 3) & 0007);
305
306    uid_t uid = -1;
307    gid_t gid = -1;
308    uint64_t cap = 0;
309    if (should_use_fs_config(path)) {
310        unsigned int broken_api_hack = mode;
311        fs_config(path.c_str(), 0, nullptr, &uid, &gid, &broken_api_hack, &cap);
312        mode = broken_api_hack;
313    }
314    return handle_send_file(s, path.c_str(), uid, gid, mode, buffer, do_unlink);
315}
316
317static bool do_recv(int s, const char* path, std::vector<char>& buffer) {
318    int fd = adb_open(path, O_RDONLY | O_CLOEXEC);
319    if (fd < 0) {
320        SendSyncFailErrno(s, "open failed");
321        return false;
322    }
323
324    syncmsg msg;
325    msg.data.id = ID_DATA;
326    while (true) {
327        int r = adb_read(fd, &buffer[0], buffer.size());
328        if (r <= 0) {
329            if (r == 0) break;
330            SendSyncFailErrno(s, "read failed");
331            adb_close(fd);
332            return false;
333        }
334        msg.data.size = r;
335        if (!WriteFdExactly(s, &msg.data, sizeof(msg.data)) || !WriteFdExactly(s, &buffer[0], r)) {
336            adb_close(fd);
337            return false;
338        }
339    }
340
341    adb_close(fd);
342
343    msg.data.id = ID_DONE;
344    msg.data.size = 0;
345    return WriteFdExactly(s, &msg.data, sizeof(msg.data));
346}
347
348static bool handle_sync_command(int fd, std::vector<char>& buffer) {
349    D("sync: waiting for request");
350
351    SyncRequest request;
352    if (!ReadFdExactly(fd, &request, sizeof(request))) {
353        SendSyncFail(fd, "command read failure");
354        return false;
355    }
356    size_t path_length = request.path_length;
357    if (path_length > 1024) {
358        SendSyncFail(fd, "path too long");
359        return false;
360    }
361    char name[1025];
362    if (!ReadFdExactly(fd, name, path_length)) {
363        SendSyncFail(fd, "filename read failure");
364        return false;
365    }
366    name[path_length] = 0;
367
368    const char* id = reinterpret_cast<const char*>(&request.id);
369    D("sync: '%.4s' '%s'", id, name);
370
371    switch (request.id) {
372      case ID_STAT:
373        if (!do_stat(fd, name)) return false;
374        break;
375      case ID_LIST:
376        if (!do_list(fd, name)) return false;
377        break;
378      case ID_SEND:
379        if (!do_send(fd, name, buffer)) return false;
380        break;
381      case ID_RECV:
382        if (!do_recv(fd, name, buffer)) return false;
383        break;
384      case ID_QUIT:
385        return false;
386      default:
387        SendSyncFail(fd, android::base::StringPrintf("unknown command '%.4s' (%08x)",
388                                                     id, request.id));
389        return false;
390    }
391
392    return true;
393}
394
395void file_sync_service(int fd, void* cookie) {
396    std::vector<char> buffer(SYNC_DATA_MAX);
397
398    while (handle_sync_command(fd, buffer)) {
399    }
400
401    D("sync: done");
402    adb_close(fd);
403}
404