1 /*
2  * Copyright (C) 2008 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 #include <stdarg.h>
18 #include <stdlib.h>
19 #include <stdio.h>
20 #include <string.h>
21 #include <fcntl.h>
22 #include <ctype.h>
23 #include <errno.h>
24 #include <time.h>
25 #include <ftw.h>
26 
27 #include <selinux/label.h>
28 #include <selinux/android.h>
29 
30 #include <sys/stat.h>
31 #include <sys/types.h>
32 #include <sys/socket.h>
33 #include <sys/un.h>
34 
35 #include <base/file.h>
36 
37 /* for ANDROID_SOCKET_* */
38 #include <cutils/sockets.h>
39 #include <base/stringprintf.h>
40 
41 #include <private/android_filesystem_config.h>
42 
43 #include "init.h"
44 #include "log.h"
45 #include "util.h"
46 
47 /*
48  * android_name_to_id - returns the integer uid/gid associated with the given
49  * name, or -1U on error.
50  */
android_name_to_id(const char * name)51 static unsigned int android_name_to_id(const char *name)
52 {
53     const struct android_id_info *info = android_ids;
54     unsigned int n;
55 
56     for (n = 0; n < android_id_count; n++) {
57         if (!strcmp(info[n].name, name))
58             return info[n].aid;
59     }
60 
61     return -1U;
62 }
63 
64 /*
65  * decode_uid - decodes and returns the given string, which can be either the
66  * numeric or name representation, into the integer uid or gid. Returns -1U on
67  * error.
68  */
decode_uid(const char * s)69 unsigned int decode_uid(const char *s)
70 {
71     unsigned int v;
72 
73     if (!s || *s == '\0')
74         return -1U;
75     if (isalpha(s[0]))
76         return android_name_to_id(s);
77 
78     errno = 0;
79     v = (unsigned int) strtoul(s, 0, 0);
80     if (errno)
81         return -1U;
82     return v;
83 }
84 
85 /*
86  * create_socket - creates a Unix domain socket in ANDROID_SOCKET_DIR
87  * ("/dev/socket") as dictated in init.rc. This socket is inherited by the
88  * daemon. We communicate the file descriptor's value via the environment
89  * variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
90  */
create_socket(const char * name,int type,mode_t perm,uid_t uid,gid_t gid,const char * socketcon)91 int create_socket(const char *name, int type, mode_t perm, uid_t uid,
92                   gid_t gid, const char *socketcon)
93 {
94     struct sockaddr_un addr;
95     int fd, ret;
96     char *filecon;
97 
98     if (socketcon)
99         setsockcreatecon(socketcon);
100 
101     fd = socket(PF_UNIX, type, 0);
102     if (fd < 0) {
103         ERROR("Failed to open socket '%s': %s\n", name, strerror(errno));
104         return -1;
105     }
106 
107     if (socketcon)
108         setsockcreatecon(NULL);
109 
110     memset(&addr, 0 , sizeof(addr));
111     addr.sun_family = AF_UNIX;
112     snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR"/%s",
113              name);
114 
115     ret = unlink(addr.sun_path);
116     if (ret != 0 && errno != ENOENT) {
117         ERROR("Failed to unlink old socket '%s': %s\n", name, strerror(errno));
118         goto out_close;
119     }
120 
121     filecon = NULL;
122     if (sehandle) {
123         ret = selabel_lookup(sehandle, &filecon, addr.sun_path, S_IFSOCK);
124         if (ret == 0)
125             setfscreatecon(filecon);
126     }
127 
128     ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
129     if (ret) {
130         ERROR("Failed to bind socket '%s': %s\n", name, strerror(errno));
131         goto out_unlink;
132     }
133 
134     setfscreatecon(NULL);
135     freecon(filecon);
136 
137     chown(addr.sun_path, uid, gid);
138     chmod(addr.sun_path, perm);
139 
140     INFO("Created socket '%s' with mode '%o', user '%d', group '%d'\n",
141          addr.sun_path, perm, uid, gid);
142 
143     return fd;
144 
145 out_unlink:
146     unlink(addr.sun_path);
147 out_close:
148     close(fd);
149     return -1;
150 }
151 
read_file(const char * path,std::string * content)152 bool read_file(const char* path, std::string* content) {
153     content->clear();
154 
155     int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC));
156     if (fd == -1) {
157         return false;
158     }
159 
160     // For security reasons, disallow world-writable
161     // or group-writable files.
162     struct stat sb;
163     if (fstat(fd, &sb) == -1) {
164         ERROR("fstat failed for '%s': %s\n", path, strerror(errno));
165         return false;
166     }
167     if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
168         ERROR("skipping insecure file '%s'\n", path);
169         return false;
170     }
171 
172     bool okay = android::base::ReadFdToString(fd, content);
173     close(fd);
174     return okay;
175 }
176 
write_file(const char * path,const char * content)177 int write_file(const char* path, const char* content) {
178     int fd = TEMP_FAILURE_RETRY(open(path, O_WRONLY|O_CREAT|O_NOFOLLOW|O_CLOEXEC, 0600));
179     if (fd == -1) {
180         NOTICE("write_file: Unable to open '%s': %s\n", path, strerror(errno));
181         return -1;
182     }
183     int result = android::base::WriteStringToFd(content, fd) ? 0 : -1;
184     if (result == -1) {
185         NOTICE("write_file: Unable to write to '%s': %s\n", path, strerror(errno));
186     }
187     close(fd);
188     return result;
189 }
190 
191 #define MAX_MTD_PARTITIONS 16
192 
193 static struct {
194     char name[16];
195     int number;
196 } mtd_part_map[MAX_MTD_PARTITIONS];
197 
198 static int mtd_part_count = -1;
199 
find_mtd_partitions(void)200 static void find_mtd_partitions(void)
201 {
202     int fd;
203     char buf[1024];
204     char *pmtdbufp;
205     ssize_t pmtdsize;
206     int r;
207 
208     fd = open("/proc/mtd", O_RDONLY|O_CLOEXEC);
209     if (fd < 0)
210         return;
211 
212     buf[sizeof(buf) - 1] = '\0';
213     pmtdsize = read(fd, buf, sizeof(buf) - 1);
214     pmtdbufp = buf;
215     while (pmtdsize > 0) {
216         int mtdnum, mtdsize, mtderasesize;
217         char mtdname[16];
218         mtdname[0] = '\0';
219         mtdnum = -1;
220         r = sscanf(pmtdbufp, "mtd%d: %x %x %15s",
221                    &mtdnum, &mtdsize, &mtderasesize, mtdname);
222         if ((r == 4) && (mtdname[0] == '"')) {
223             char *x = strchr(mtdname + 1, '"');
224             if (x) {
225                 *x = 0;
226             }
227             INFO("mtd partition %d, %s\n", mtdnum, mtdname + 1);
228             if (mtd_part_count < MAX_MTD_PARTITIONS) {
229                 strcpy(mtd_part_map[mtd_part_count].name, mtdname + 1);
230                 mtd_part_map[mtd_part_count].number = mtdnum;
231                 mtd_part_count++;
232             } else {
233                 ERROR("too many mtd partitions\n");
234             }
235         }
236         while (pmtdsize > 0 && *pmtdbufp != '\n') {
237             pmtdbufp++;
238             pmtdsize--;
239         }
240         if (pmtdsize > 0) {
241             pmtdbufp++;
242             pmtdsize--;
243         }
244     }
245     close(fd);
246 }
247 
mtd_name_to_number(const char * name)248 int mtd_name_to_number(const char *name)
249 {
250     int n;
251     if (mtd_part_count < 0) {
252         mtd_part_count = 0;
253         find_mtd_partitions();
254     }
255     for (n = 0; n < mtd_part_count; n++) {
256         if (!strcmp(name, mtd_part_map[n].name)) {
257             return mtd_part_map[n].number;
258         }
259     }
260     return -1;
261 }
262 
gettime()263 time_t gettime() {
264     timespec now;
265     clock_gettime(CLOCK_MONOTONIC, &now);
266     return now.tv_sec;
267 }
268 
gettime_ns()269 uint64_t gettime_ns() {
270     timespec now;
271     clock_gettime(CLOCK_MONOTONIC, &now);
272     return static_cast<uint64_t>(now.tv_sec) * UINT64_C(1000000000) + now.tv_nsec;
273 }
274 
mkdir_recursive(const char * pathname,mode_t mode)275 int mkdir_recursive(const char *pathname, mode_t mode)
276 {
277     char buf[128];
278     const char *slash;
279     const char *p = pathname;
280     int width;
281     int ret;
282     struct stat info;
283 
284     while ((slash = strchr(p, '/')) != NULL) {
285         width = slash - pathname;
286         p = slash + 1;
287         if (width < 0)
288             break;
289         if (width == 0)
290             continue;
291         if ((unsigned int)width > sizeof(buf) - 1) {
292             ERROR("path too long for mkdir_recursive\n");
293             return -1;
294         }
295         memcpy(buf, pathname, width);
296         buf[width] = 0;
297         if (stat(buf, &info) != 0) {
298             ret = make_dir(buf, mode);
299             if (ret && errno != EEXIST)
300                 return ret;
301         }
302     }
303     ret = make_dir(pathname, mode);
304     if (ret && errno != EEXIST)
305         return ret;
306     return 0;
307 }
308 
309 /*
310  * replaces any unacceptable characters with '_', the
311  * length of the resulting string is equal to the input string
312  */
sanitize(char * s)313 void sanitize(char *s)
314 {
315     const char* accept =
316             "abcdefghijklmnopqrstuvwxyz"
317             "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
318             "0123456789"
319             "_-.";
320 
321     if (!s)
322         return;
323 
324     while (*s) {
325         s += strspn(s, accept);
326         if (*s) *s++ = '_';
327     }
328 }
329 
make_link_init(const char * oldpath,const char * newpath)330 void make_link_init(const char *oldpath, const char *newpath)
331 {
332     int ret;
333     char buf[256];
334     char *slash;
335     int width;
336 
337     slash = strrchr(newpath, '/');
338     if (!slash)
339         return;
340     width = slash - newpath;
341     if (width <= 0 || width > (int)sizeof(buf) - 1)
342         return;
343     memcpy(buf, newpath, width);
344     buf[width] = 0;
345     ret = mkdir_recursive(buf, 0755);
346     if (ret)
347         ERROR("Failed to create directory %s: %s (%d)\n", buf, strerror(errno), errno);
348 
349     ret = symlink(oldpath, newpath);
350     if (ret && errno != EEXIST)
351         ERROR("Failed to symlink %s to %s: %s (%d)\n", oldpath, newpath, strerror(errno), errno);
352 }
353 
remove_link(const char * oldpath,const char * newpath)354 void remove_link(const char *oldpath, const char *newpath)
355 {
356     char path[256];
357     ssize_t ret;
358     ret = readlink(newpath, path, sizeof(path) - 1);
359     if (ret <= 0)
360         return;
361     path[ret] = 0;
362     if (!strcmp(path, oldpath))
363         unlink(newpath);
364 }
365 
wait_for_file(const char * filename,int timeout)366 int wait_for_file(const char *filename, int timeout)
367 {
368     struct stat info;
369     uint64_t timeout_time_ns = gettime_ns() + timeout * UINT64_C(1000000000);
370     int ret = -1;
371 
372     while (gettime_ns() < timeout_time_ns && ((ret = stat(filename, &info)) < 0))
373         usleep(10000);
374 
375     return ret;
376 }
377 
open_devnull_stdio(void)378 void open_devnull_stdio(void)
379 {
380     // Try to avoid the mknod() call if we can. Since SELinux makes
381     // a /dev/null replacement available for free, let's use it.
382     int fd = open("/sys/fs/selinux/null", O_RDWR);
383     if (fd == -1) {
384         // OOPS, /sys/fs/selinux/null isn't available, likely because
385         // /sys/fs/selinux isn't mounted. Fall back to mknod.
386         static const char *name = "/dev/__null__";
387         if (mknod(name, S_IFCHR | 0600, (1 << 8) | 3) == 0) {
388             fd = open(name, O_RDWR);
389             unlink(name);
390         }
391         if (fd == -1) {
392             exit(1);
393         }
394     }
395 
396     dup2(fd, 0);
397     dup2(fd, 1);
398     dup2(fd, 2);
399     if (fd > 2) {
400         close(fd);
401     }
402 }
403 
import_kernel_cmdline(bool in_qemu,std::function<void (char *,bool)> import_kernel_nv)404 void import_kernel_cmdline(bool in_qemu, std::function<void(char*,bool)> import_kernel_nv)
405 {
406     char cmdline[2048];
407     char *ptr;
408     int fd;
409 
410     fd = open("/proc/cmdline", O_RDONLY | O_CLOEXEC);
411     if (fd >= 0) {
412         int n = read(fd, cmdline, sizeof(cmdline) - 1);
413         if (n < 0) n = 0;
414 
415         /* get rid of trailing newline, it happens */
416         if (n > 0 && cmdline[n-1] == '\n') n--;
417 
418         cmdline[n] = 0;
419         close(fd);
420     } else {
421         cmdline[0] = 0;
422     }
423 
424     ptr = cmdline;
425     while (ptr && *ptr) {
426         char *x = strchr(ptr, ' ');
427         if (x != 0) *x++ = 0;
428         import_kernel_nv(ptr, in_qemu);
429         ptr = x;
430     }
431 }
432 
make_dir(const char * path,mode_t mode)433 int make_dir(const char *path, mode_t mode)
434 {
435     int rc;
436 
437     char *secontext = NULL;
438 
439     if (sehandle) {
440         selabel_lookup(sehandle, &secontext, path, mode);
441         setfscreatecon(secontext);
442     }
443 
444     rc = mkdir(path, mode);
445 
446     if (secontext) {
447         int save_errno = errno;
448         freecon(secontext);
449         setfscreatecon(NULL);
450         errno = save_errno;
451     }
452 
453     return rc;
454 }
455 
restorecon(const char * pathname)456 int restorecon(const char* pathname)
457 {
458     return selinux_android_restorecon(pathname, 0);
459 }
460 
restorecon_recursive(const char * pathname)461 int restorecon_recursive(const char* pathname)
462 {
463     return selinux_android_restorecon(pathname, SELINUX_ANDROID_RESTORECON_RECURSE);
464 }
465 
466 /*
467  * Writes hex_len hex characters (1/2 byte) to hex from bytes.
468  */
bytes_to_hex(const uint8_t * bytes,size_t bytes_len)469 std::string bytes_to_hex(const uint8_t* bytes, size_t bytes_len) {
470     std::string hex("0x");
471     for (size_t i = 0; i < bytes_len; i++)
472         android::base::StringAppendF(&hex, "%02x", bytes[i]);
473     return hex;
474 }
475