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      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 /* for ANDROID_SOCKET_* */
     36 #include <cutils/sockets.h>
     37 
     38 #include <private/android_filesystem_config.h>
     39 
     40 #include "init.h"
     41 #include "log.h"
     42 #include "util.h"
     43 
     44 /*
     45  * android_name_to_id - returns the integer uid/gid associated with the given
     46  * name, or -1U on error.
     47  */
     48 static unsigned int android_name_to_id(const char *name)
     49 {
     50     const struct android_id_info *info = android_ids;
     51     unsigned int n;
     52 
     53     for (n = 0; n < android_id_count; n++) {
     54         if (!strcmp(info[n].name, name))
     55             return info[n].aid;
     56     }
     57 
     58     return -1U;
     59 }
     60 
     61 /*
     62  * decode_uid - decodes and returns the given string, which can be either the
     63  * numeric or name representation, into the integer uid or gid. Returns -1U on
     64  * error.
     65  */
     66 unsigned int decode_uid(const char *s)
     67 {
     68     unsigned int v;
     69 
     70     if (!s || *s == '\0')
     71         return -1U;
     72     if (isalpha(s[0]))
     73         return android_name_to_id(s);
     74 
     75     errno = 0;
     76     v = (unsigned int) strtoul(s, 0, 0);
     77     if (errno)
     78         return -1U;
     79     return v;
     80 }
     81 
     82 /*
     83  * create_socket - creates a Unix domain socket in ANDROID_SOCKET_DIR
     84  * ("/dev/socket") as dictated in init.rc. This socket is inherited by the
     85  * daemon. We communicate the file descriptor's value via the environment
     86  * variable ANDROID_SOCKET_ENV_PREFIX<name> ("ANDROID_SOCKET_foo").
     87  */
     88 int create_socket(const char *name, int type, mode_t perm, uid_t uid,
     89                   gid_t gid, const char *socketcon)
     90 {
     91     struct sockaddr_un addr;
     92     int fd, ret;
     93     char *filecon;
     94 
     95     if (socketcon)
     96         setsockcreatecon(socketcon);
     97 
     98     fd = socket(PF_UNIX, type, 0);
     99     if (fd < 0) {
    100         ERROR("Failed to open socket '%s': %s\n", name, strerror(errno));
    101         return -1;
    102     }
    103 
    104     if (socketcon)
    105         setsockcreatecon(NULL);
    106 
    107     memset(&addr, 0 , sizeof(addr));
    108     addr.sun_family = AF_UNIX;
    109     snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR"/%s",
    110              name);
    111 
    112     ret = unlink(addr.sun_path);
    113     if (ret != 0 && errno != ENOENT) {
    114         ERROR("Failed to unlink old socket '%s': %s\n", name, strerror(errno));
    115         goto out_close;
    116     }
    117 
    118     filecon = NULL;
    119     if (sehandle) {
    120         ret = selabel_lookup(sehandle, &filecon, addr.sun_path, S_IFSOCK);
    121         if (ret == 0)
    122             setfscreatecon(filecon);
    123     }
    124 
    125     ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
    126     if (ret) {
    127         ERROR("Failed to bind socket '%s': %s\n", name, strerror(errno));
    128         goto out_unlink;
    129     }
    130 
    131     setfscreatecon(NULL);
    132     freecon(filecon);
    133 
    134     chown(addr.sun_path, uid, gid);
    135     chmod(addr.sun_path, perm);
    136 
    137     INFO("Created socket '%s' with mode '%o', user '%d', group '%d'\n",
    138          addr.sun_path, perm, uid, gid);
    139 
    140     return fd;
    141 
    142 out_unlink:
    143     unlink(addr.sun_path);
    144 out_close:
    145     close(fd);
    146     return -1;
    147 }
    148 
    149 /* reads a file, making sure it is terminated with \n \0 */
    150 void *read_file(const char *fn, unsigned *_sz)
    151 {
    152     char *data;
    153     int sz;
    154     int fd;
    155     struct stat sb;
    156 
    157     data = 0;
    158     fd = open(fn, O_RDONLY);
    159     if(fd < 0) return 0;
    160 
    161     // for security reasons, disallow world-writable
    162     // or group-writable files
    163     if (fstat(fd, &sb) < 0) {
    164         ERROR("fstat failed for '%s'\n", fn);
    165         goto oops;
    166     }
    167     if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
    168         ERROR("skipping insecure file '%s'\n", fn);
    169         goto oops;
    170     }
    171 
    172     sz = lseek(fd, 0, SEEK_END);
    173     if(sz < 0) goto oops;
    174 
    175     if(lseek(fd, 0, SEEK_SET) != 0) goto oops;
    176 
    177     data = (char*) malloc(sz + 2);
    178     if(data == 0) goto oops;
    179 
    180     if(read(fd, data, sz) != sz) goto oops;
    181     close(fd);
    182     data[sz] = '\n';
    183     data[sz+1] = 0;
    184     if(_sz) *_sz = sz;
    185     return data;
    186 
    187 oops:
    188     close(fd);
    189     if(data != 0) free(data);
    190     return 0;
    191 }
    192 
    193 #define MAX_MTD_PARTITIONS 16
    194 
    195 static struct {
    196     char name[16];
    197     int number;
    198 } mtd_part_map[MAX_MTD_PARTITIONS];
    199 
    200 static int mtd_part_count = -1;
    201 
    202 static void find_mtd_partitions(void)
    203 {
    204     int fd;
    205     char buf[1024];
    206     char *pmtdbufp;
    207     ssize_t pmtdsize;
    208     int r;
    209 
    210     fd = open("/proc/mtd", O_RDONLY);
    211     if (fd < 0)
    212         return;
    213 
    214     buf[sizeof(buf) - 1] = '\0';
    215     pmtdsize = read(fd, buf, sizeof(buf) - 1);
    216     pmtdbufp = buf;
    217     while (pmtdsize > 0) {
    218         int mtdnum, mtdsize, mtderasesize;
    219         char mtdname[16];
    220         mtdname[0] = '\0';
    221         mtdnum = -1;
    222         r = sscanf(pmtdbufp, "mtd%d: %x %x %15s",
    223                    &mtdnum, &mtdsize, &mtderasesize, mtdname);
    224         if ((r == 4) && (mtdname[0] == '"')) {
    225             char *x = strchr(mtdname + 1, '"');
    226             if (x) {
    227                 *x = 0;
    228             }
    229             INFO("mtd partition %d, %s\n", mtdnum, mtdname + 1);
    230             if (mtd_part_count < MAX_MTD_PARTITIONS) {
    231                 strcpy(mtd_part_map[mtd_part_count].name, mtdname + 1);
    232                 mtd_part_map[mtd_part_count].number = mtdnum;
    233                 mtd_part_count++;
    234             } else {
    235                 ERROR("too many mtd partitions\n");
    236             }
    237         }
    238         while (pmtdsize > 0 && *pmtdbufp != '\n') {
    239             pmtdbufp++;
    240             pmtdsize--;
    241         }
    242         if (pmtdsize > 0) {
    243             pmtdbufp++;
    244             pmtdsize--;
    245         }
    246     }
    247     close(fd);
    248 }
    249 
    250 int mtd_name_to_number(const char *name)
    251 {
    252     int n;
    253     if (mtd_part_count < 0) {
    254         mtd_part_count = 0;
    255         find_mtd_partitions();
    256     }
    257     for (n = 0; n < mtd_part_count; n++) {
    258         if (!strcmp(name, mtd_part_map[n].name)) {
    259             return mtd_part_map[n].number;
    260         }
    261     }
    262     return -1;
    263 }
    264 
    265 /*
    266  * gettime() - returns the time in seconds of the system's monotonic clock or
    267  * zero on error.
    268  */
    269 time_t gettime(void)
    270 {
    271     struct timespec ts;
    272     int ret;
    273 
    274     ret = clock_gettime(CLOCK_MONOTONIC, &ts);
    275     if (ret < 0) {
    276         ERROR("clock_gettime(CLOCK_MONOTONIC) failed: %s\n", strerror(errno));
    277         return 0;
    278     }
    279 
    280     return ts.tv_sec;
    281 }
    282 
    283 int mkdir_recursive(const char *pathname, mode_t mode)
    284 {
    285     char buf[128];
    286     const char *slash;
    287     const char *p = pathname;
    288     int width;
    289     int ret;
    290     struct stat info;
    291 
    292     while ((slash = strchr(p, '/')) != NULL) {
    293         width = slash - pathname;
    294         p = slash + 1;
    295         if (width < 0)
    296             break;
    297         if (width == 0)
    298             continue;
    299         if ((unsigned int)width > sizeof(buf) - 1) {
    300             ERROR("path too long for mkdir_recursive\n");
    301             return -1;
    302         }
    303         memcpy(buf, pathname, width);
    304         buf[width] = 0;
    305         if (stat(buf, &info) != 0) {
    306             ret = make_dir(buf, mode);
    307             if (ret && errno != EEXIST)
    308                 return ret;
    309         }
    310     }
    311     ret = make_dir(pathname, mode);
    312     if (ret && errno != EEXIST)
    313         return ret;
    314     return 0;
    315 }
    316 
    317 /*
    318  * replaces any unacceptable characters with '_', the
    319  * length of the resulting string is equal to the input string
    320  */
    321 void sanitize(char *s)
    322 {
    323     const char* accept =
    324             "abcdefghijklmnopqrstuvwxyz"
    325             "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    326             "0123456789"
    327             "_-.";
    328 
    329     if (!s)
    330         return;
    331 
    332     while (*s) {
    333         s += strspn(s, accept);
    334         if (*s) *s++ = '_';
    335     }
    336 }
    337 
    338 void make_link(const char *oldpath, const char *newpath)
    339 {
    340     int ret;
    341     char buf[256];
    342     char *slash;
    343     int width;
    344 
    345     slash = strrchr(newpath, '/');
    346     if (!slash)
    347         return;
    348     width = slash - newpath;
    349     if (width <= 0 || width > (int)sizeof(buf) - 1)
    350         return;
    351     memcpy(buf, newpath, width);
    352     buf[width] = 0;
    353     ret = mkdir_recursive(buf, 0755);
    354     if (ret)
    355         ERROR("Failed to create directory %s: %s (%d)\n", buf, strerror(errno), errno);
    356 
    357     ret = symlink(oldpath, newpath);
    358     if (ret && errno != EEXIST)
    359         ERROR("Failed to symlink %s to %s: %s (%d)\n", oldpath, newpath, strerror(errno), errno);
    360 }
    361 
    362 void remove_link(const char *oldpath, const char *newpath)
    363 {
    364     char path[256];
    365     ssize_t ret;
    366     ret = readlink(newpath, path, sizeof(path) - 1);
    367     if (ret <= 0)
    368         return;
    369     path[ret] = 0;
    370     if (!strcmp(path, oldpath))
    371         unlink(newpath);
    372 }
    373 
    374 int wait_for_file(const char *filename, int timeout)
    375 {
    376     struct stat info;
    377     time_t timeout_time = gettime() + timeout;
    378     int ret = -1;
    379 
    380     while (gettime() < timeout_time && ((ret = stat(filename, &info)) < 0))
    381         usleep(10000);
    382 
    383     return ret;
    384 }
    385 
    386 void open_devnull_stdio(void)
    387 {
    388     int fd;
    389     static const char *name = "/dev/__null__";
    390     if (mknod(name, S_IFCHR | 0600, (1 << 8) | 3) == 0) {
    391         fd = open(name, O_RDWR);
    392         unlink(name);
    393         if (fd >= 0) {
    394             dup2(fd, 0);
    395             dup2(fd, 1);
    396             dup2(fd, 2);
    397             if (fd > 2) {
    398                 close(fd);
    399             }
    400             return;
    401         }
    402     }
    403 
    404     exit(1);
    405 }
    406 
    407 void get_hardware_name(char *hardware, unsigned int *revision)
    408 {
    409     const char *cpuinfo = "/proc/cpuinfo";
    410     char *data = NULL;
    411     size_t len = 0, limit = 1024;
    412     int fd, n;
    413     char *x, *hw, *rev;
    414 
    415     /* Hardware string was provided on kernel command line */
    416     if (hardware[0])
    417         return;
    418 
    419     fd = open(cpuinfo, O_RDONLY);
    420     if (fd < 0) return;
    421 
    422     for (;;) {
    423         x = realloc(data, limit);
    424         if (!x) {
    425             ERROR("Failed to allocate memory to read %s\n", cpuinfo);
    426             goto done;
    427         }
    428         data = x;
    429 
    430         n = read(fd, data + len, limit - len);
    431         if (n < 0) {
    432             ERROR("Failed reading %s: %s (%d)\n", cpuinfo, strerror(errno), errno);
    433             goto done;
    434         }
    435         len += n;
    436 
    437         if (len < limit)
    438             break;
    439 
    440         /* We filled the buffer, so increase size and loop to read more */
    441         limit *= 2;
    442     }
    443 
    444     data[len] = 0;
    445     hw = strstr(data, "\nHardware");
    446     rev = strstr(data, "\nRevision");
    447 
    448     if (hw) {
    449         x = strstr(hw, ": ");
    450         if (x) {
    451             x += 2;
    452             n = 0;
    453             while (*x && *x != '\n') {
    454                 if (!isspace(*x))
    455                     hardware[n++] = tolower(*x);
    456                 x++;
    457                 if (n == 31) break;
    458             }
    459             hardware[n] = 0;
    460         }
    461     }
    462 
    463     if (rev) {
    464         x = strstr(rev, ": ");
    465         if (x) {
    466             *revision = strtoul(x + 2, 0, 16);
    467         }
    468     }
    469 
    470 done:
    471     close(fd);
    472     free(data);
    473 }
    474 
    475 void import_kernel_cmdline(int in_qemu,
    476                            void (*import_kernel_nv)(char *name, int in_qemu))
    477 {
    478     char cmdline[2048];
    479     char *ptr;
    480     int fd;
    481 
    482     fd = open("/proc/cmdline", O_RDONLY);
    483     if (fd >= 0) {
    484         int n = read(fd, cmdline, sizeof(cmdline) - 1);
    485         if (n < 0) n = 0;
    486 
    487         /* get rid of trailing newline, it happens */
    488         if (n > 0 && cmdline[n-1] == '\n') n--;
    489 
    490         cmdline[n] = 0;
    491         close(fd);
    492     } else {
    493         cmdline[0] = 0;
    494     }
    495 
    496     ptr = cmdline;
    497     while (ptr && *ptr) {
    498         char *x = strchr(ptr, ' ');
    499         if (x != 0) *x++ = 0;
    500         import_kernel_nv(ptr, in_qemu);
    501         ptr = x;
    502     }
    503 }
    504 
    505 int make_dir(const char *path, mode_t mode)
    506 {
    507     int rc;
    508 
    509     char *secontext = NULL;
    510 
    511     if (sehandle) {
    512         selabel_lookup(sehandle, &secontext, path, mode);
    513         setfscreatecon(secontext);
    514     }
    515 
    516     rc = mkdir(path, mode);
    517 
    518     if (secontext) {
    519         int save_errno = errno;
    520         freecon(secontext);
    521         setfscreatecon(NULL);
    522         errno = save_errno;
    523     }
    524 
    525     return rc;
    526 }
    527 
    528 int restorecon(const char* pathname)
    529 {
    530     return selinux_android_restorecon(pathname, 0);
    531 }
    532 
    533 int restorecon_recursive(const char* pathname)
    534 {
    535     return selinux_android_restorecon(pathname, SELINUX_ANDROID_RESTORECON_RECURSE);
    536 }
    537