file_sync_service.cpp revision 20a96c7d792cf55c76b6291b46480e584face9bf 
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 <log/log.h>
25#include <selinux/android.h>
26#include <stdio.h>
27#include <stdlib.h>
28#include <string.h>
29#include <sys/stat.h>
30#include <sys/types.h>
31#include <unistd.h>
32#include <utime.h>
33
34#include "adb.h"
35#include "adb_io.h"
36#include "adb_utils.h"
37#include "private/android_filesystem_config.h"
38#include "security_log_tags.h"
39
40#include <android-base/stringprintf.h>
41#include <android-base/strings.h>
42
43static bool should_use_fs_config(const std::string& path) {
44    // TODO: use fs_config to configure permissions on /data.
45    return android::base::StartsWith(path, "/system/") ||
46           android::base::StartsWith(path, "/vendor/") ||
47           android::base::StartsWith(path, "/oem/");
48}
49
50static bool secure_mkdirs(const std::string& path) {
51    uid_t uid = -1;
52    gid_t gid = -1;
53    unsigned int mode = 0775;
54    uint64_t cap = 0;
55
56    if (path[0] != '/') return false;
57
58    std::vector<std::string> path_components = android::base::Split(path, "/");
59    std::string partial_path;
60    for (const auto& path_component : path_components) {
61        if (partial_path.back() != OS_PATH_SEPARATOR) partial_path += OS_PATH_SEPARATOR;
62        partial_path += path_component;
63
64        if (should_use_fs_config(partial_path)) {
65            fs_config(partial_path.c_str(), 1, nullptr, &uid, &gid, &mode, &cap);
66        }
67        if (adb_mkdir(partial_path.c_str(), mode) == -1) {
68            if (errno != EEXIST) {
69                return false;
70            }
71        } else {
72            if (chown(partial_path.c_str(), uid, gid) == -1) {
73                return false;
74            }
75            // Not all filesystems support setting SELinux labels. http://b/23530370.
76            selinux_android_restorecon(partial_path.c_str(), 0);
77        }
78    }
79    return true;
80}
81
82static bool do_stat(int s, const char* path) {
83    syncmsg msg;
84    msg.stat.id = ID_STAT;
85
86    struct stat st;
87    memset(&st, 0, sizeof(st));
88    // TODO: add a way to report that the stat failed!
89    lstat(path, &st);
90    msg.stat.mode = st.st_mode;
91    msg.stat.size = st.st_size;
92    msg.stat.time = st.st_mtime;
93
94    return WriteFdExactly(s, &msg.stat, sizeof(msg.stat));
95}
96
97static bool do_list(int s, const char* path) {
98    dirent* de;
99
100    syncmsg msg;
101    msg.dent.id = ID_DENT;
102
103    std::unique_ptr<DIR, int(*)(DIR*)> d(opendir(path), closedir);
104    if (!d) goto done;
105
106    while ((de = readdir(d.get()))) {
107        std::string filename(android::base::StringPrintf("%s/%s", path, de->d_name));
108
109        struct stat st;
110        if (lstat(filename.c_str(), &st) == 0) {
111            size_t d_name_length = strlen(de->d_name);
112            msg.dent.mode = st.st_mode;
113            msg.dent.size = st.st_size;
114            msg.dent.time = st.st_mtime;
115            msg.dent.namelen = d_name_length;
116
117            if (!WriteFdExactly(s, &msg.dent, sizeof(msg.dent)) ||
118                    !WriteFdExactly(s, de->d_name, d_name_length)) {
119                return false;
120            }
121        }
122    }
123
124done:
125    msg.dent.id = ID_DONE;
126    msg.dent.mode = 0;
127    msg.dent.size = 0;
128    msg.dent.time = 0;
129    msg.dent.namelen = 0;
130    return WriteFdExactly(s, &msg.dent, sizeof(msg.dent));
131}
132
133// Make sure that SendFail from adb_io.cpp isn't accidentally used in this file.
134#pragma GCC poison SendFail
135
136static bool SendSyncFail(int fd, const std::string& reason) {
137    D("sync: failure: %s", reason.c_str());
138
139    syncmsg msg;
140    msg.data.id = ID_FAIL;
141    msg.data.size = reason.size();
142    return WriteFdExactly(fd, &msg.data, sizeof(msg.data)) && WriteFdExactly(fd, reason);
143}
144
145static bool SendSyncFailErrno(int fd, const std::string& reason) {
146    return SendSyncFail(fd, android::base::StringPrintf("%s: %s", reason.c_str(), strerror(errno)));
147}
148
149static bool handle_send_file(int s, const char* path, uid_t uid,
150                             gid_t gid, mode_t mode, std::vector<char>& buffer, bool do_unlink) {
151    syncmsg msg;
152    unsigned int timestamp = 0;
153
154    __android_log_security_bswrite(SEC_TAG_ADB_SEND_FILE, path);
155
156    int fd = adb_open_mode(path, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, mode);
157    if (fd < 0 && errno == ENOENT) {
158        if (!secure_mkdirs(adb_dirname(path))) {
159            SendSyncFailErrno(s, "secure_mkdirs failed");
160            goto fail;
161        }
162        fd = adb_open_mode(path, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, mode);
163    }
164    if (fd < 0 && errno == EEXIST) {
165        fd = adb_open_mode(path, O_WRONLY | O_CLOEXEC, mode);
166    }
167    if (fd < 0) {
168        SendSyncFailErrno(s, "couldn't create file");
169        goto fail;
170    } else {
171        if (fchown(fd, uid, gid) == -1) {
172            SendSyncFailErrno(s, "fchown failed");
173            goto fail;
174        }
175
176        // Not all filesystems support setting SELinux labels. http://b/23530370.
177        selinux_android_restorecon(path, 0);
178
179        // fchown clears the setuid bit - restore it if present.
180        // Ignore the result of calling fchmod. It's not supported
181        // by all filesystems. b/12441485
182        fchmod(fd, mode);
183    }
184
185    while (true) {
186        if (!ReadFdExactly(s, &msg.data, sizeof(msg.data))) goto fail;
187
188        if (msg.data.id != ID_DATA) {
189            if (msg.data.id == ID_DONE) {
190                timestamp = msg.data.size;
191                break;
192            }
193            SendSyncFail(s, "invalid data message");
194            goto abort;
195        }
196
197        if (msg.data.size > buffer.size()) {  // TODO: resize buffer?
198            SendSyncFail(s, "oversize data message");
199            goto abort;
200        }
201
202        if (!ReadFdExactly(s, &buffer[0], msg.data.size)) goto abort;
203
204        if (!WriteFdExactly(fd, &buffer[0], msg.data.size)) {
205            SendSyncFailErrno(s, "write failed");
206            goto fail;
207        }
208    }
209
210    adb_close(fd);
211
212    utimbuf u;
213    u.actime = timestamp;
214    u.modtime = timestamp;
215    utime(path, &u);
216
217    msg.status.id = ID_OKAY;
218    msg.status.msglen = 0;
219    return WriteFdExactly(s, &msg.status, sizeof(msg.status));
220
221fail:
222    // If there's a problem on the device, we'll send an ID_FAIL message and
223    // close the socket. Unfortunately the kernel will sometimes throw that
224    // data away if the other end keeps writing without reading (which is
225    // the case with old versions of adb). To maintain compatibility, keep
226    // reading and throwing away ID_DATA packets until the other side notices
227    // that we've reported an error.
228    while (true) {
229        if (!ReadFdExactly(s, &msg.data, sizeof(msg.data))) goto fail;
230
231        if (msg.data.id == ID_DONE) {
232            goto abort;
233        } else if (msg.data.id != ID_DATA) {
234            char id[5];
235            memcpy(id, &msg.data.id, sizeof(msg.data.id));
236            id[4] = '\0';
237            D("handle_send_fail received unexpected id '%s' during failure", id);
238            goto abort;
239        }
240
241        if (msg.data.size > buffer.size()) {
242            D("handle_send_fail received oversized packet of length '%u' during failure",
243              msg.data.size);
244            goto abort;
245        }
246
247        if (!ReadFdExactly(s, &buffer[0], msg.data.size)) goto abort;
248    }
249
250abort:
251    if (fd >= 0) adb_close(fd);
252    if (do_unlink) adb_unlink(path);
253    return false;
254}
255
256#if defined(_WIN32)
257extern bool handle_send_link(int s, const std::string& path, std::vector<char>& buffer) __attribute__((error("no symlinks on Windows")));
258#else
259static bool handle_send_link(int s, const std::string& path, std::vector<char>& buffer) {
260    syncmsg msg;
261    unsigned int len;
262    int ret;
263
264    if (!ReadFdExactly(s, &msg.data, sizeof(msg.data))) return false;
265
266    if (msg.data.id != ID_DATA) {
267        SendSyncFail(s, "invalid data message: expected ID_DATA");
268        return false;
269    }
270
271    len = msg.data.size;
272    if (len > buffer.size()) { // TODO: resize buffer?
273        SendSyncFail(s, "oversize data message");
274        return false;
275    }
276    if (!ReadFdExactly(s, &buffer[0], len)) return false;
277
278    ret = symlink(&buffer[0], path.c_str());
279    if (ret && errno == ENOENT) {
280        if (!secure_mkdirs(adb_dirname(path))) {
281            SendSyncFailErrno(s, "secure_mkdirs failed");
282            return false;
283        }
284        ret = symlink(&buffer[0], path.c_str());
285    }
286    if (ret) {
287        SendSyncFailErrno(s, "symlink failed");
288        return false;
289    }
290
291    if (!ReadFdExactly(s, &msg.data, sizeof(msg.data))) return false;
292
293    if (msg.data.id == ID_DONE) {
294        msg.status.id = ID_OKAY;
295        msg.status.msglen = 0;
296        if (!WriteFdExactly(s, &msg.status, sizeof(msg.status))) return false;
297    } else {
298        SendSyncFail(s, "invalid data message: expected ID_DONE");
299        return false;
300    }
301
302    return true;
303}
304#endif
305
306static bool do_send(int s, const std::string& spec, std::vector<char>& buffer) {
307    // 'spec' is of the form "/some/path,0755". Break it up.
308    size_t comma = spec.find_last_of(',');
309    if (comma == std::string::npos) {
310        SendSyncFail(s, "missing , in ID_SEND");
311        return false;
312    }
313
314    std::string path = spec.substr(0, comma);
315
316    errno = 0;
317    mode_t mode = strtoul(spec.substr(comma + 1).c_str(), nullptr, 0);
318    if (errno != 0) {
319        SendSyncFail(s, "bad mode");
320        return false;
321    }
322
323    // Don't delete files before copying if they are not "regular" or symlinks.
324    struct stat st;
325    bool do_unlink = (lstat(path.c_str(), &st) == -1) || S_ISREG(st.st_mode) || S_ISLNK(st.st_mode);
326    if (do_unlink) {
327        adb_unlink(path.c_str());
328    }
329
330    if (S_ISLNK(mode)) {
331        return handle_send_link(s, path.c_str(), buffer);
332    }
333
334    // Copy user permission bits to "group" and "other" permissions.
335    mode &= 0777;
336    mode |= ((mode >> 3) & 0070);
337    mode |= ((mode >> 3) & 0007);
338
339    uid_t uid = -1;
340    gid_t gid = -1;
341    uint64_t cap = 0;
342    if (should_use_fs_config(path)) {
343        unsigned int broken_api_hack = mode;
344        fs_config(path.c_str(), 0, nullptr, &uid, &gid, &broken_api_hack, &cap);
345        mode = broken_api_hack;
346    }
347    return handle_send_file(s, path.c_str(), uid, gid, mode, buffer, do_unlink);
348}
349
350static bool do_recv(int s, const char* path, std::vector<char>& buffer) {
351    __android_log_security_bswrite(SEC_TAG_ADB_RECV_FILE, path);
352
353    int fd = adb_open(path, O_RDONLY | O_CLOEXEC);
354    if (fd < 0) {
355        SendSyncFailErrno(s, "open failed");
356        return false;
357    }
358
359    syncmsg msg;
360    msg.data.id = ID_DATA;
361    while (true) {
362        int r = adb_read(fd, &buffer[0], buffer.size());
363        if (r <= 0) {
364            if (r == 0) break;
365            SendSyncFailErrno(s, "read failed");
366            adb_close(fd);
367            return false;
368        }
369        msg.data.size = r;
370        if (!WriteFdExactly(s, &msg.data, sizeof(msg.data)) || !WriteFdExactly(s, &buffer[0], r)) {
371            adb_close(fd);
372            return false;
373        }
374    }
375
376    adb_close(fd);
377
378    msg.data.id = ID_DONE;
379    msg.data.size = 0;
380    return WriteFdExactly(s, &msg.data, sizeof(msg.data));
381}
382
383static bool handle_sync_command(int fd, std::vector<char>& buffer) {
384    D("sync: waiting for request");
385
386    SyncRequest request;
387    if (!ReadFdExactly(fd, &request, sizeof(request))) {
388        SendSyncFail(fd, "command read failure");
389        return false;
390    }
391    size_t path_length = request.path_length;
392    if (path_length > 1024) {
393        SendSyncFail(fd, "path too long");
394        return false;
395    }
396    char name[1025];
397    if (!ReadFdExactly(fd, name, path_length)) {
398        SendSyncFail(fd, "filename read failure");
399        return false;
400    }
401    name[path_length] = 0;
402
403    const char* id = reinterpret_cast<const char*>(&request.id);
404    D("sync: '%.4s' '%s'", id, name);
405
406    switch (request.id) {
407      case ID_STAT:
408        if (!do_stat(fd, name)) return false;
409        break;
410      case ID_LIST:
411        if (!do_list(fd, name)) return false;
412        break;
413      case ID_SEND:
414        if (!do_send(fd, name, buffer)) return false;
415        break;
416      case ID_RECV:
417        if (!do_recv(fd, name, buffer)) return false;
418        break;
419      case ID_QUIT:
420        return false;
421      default:
422        SendSyncFail(fd, android::base::StringPrintf("unknown command '%.4s' (%08x)",
423                                                     id, request.id));
424        return false;
425    }
426
427    return true;
428}
429
430void file_sync_service(int fd, void* cookie) {
431    std::vector<char> buffer(SYNC_DATA_MAX);
432
433    while (handle_sync_command(fd, buffer)) {
434    }
435
436    D("sync: done");
437    adb_close(fd);
438}
439