Home | History | Annotate | Download | only in init 
      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 "util.h"
     18 
     19 #include <ctype.h>
     20 #include <errno.h>
     21 #include <fcntl.h>
     22 #include <pwd.h>
     23 #include <stdarg.h>
     24 #include <stdio.h>
     25 #include <stdlib.h>
     26 #include <string.h>
     27 #include <sys/socket.h>
     28 #include <sys/un.h>
     29 #include <time.h>
     30 #include <unistd.h>
     31 
     32 #include <thread>
     33 
     34 #include <android-base/file.h>
     35 #include <android-base/logging.h>
     36 #include <android-base/stringprintf.h>
     37 #include <android-base/strings.h>
     38 #include <android-base/unique_fd.h>
     39 #include <cutils/android_reboot.h>
     40 #include <cutils/sockets.h>
     41 #include <selinux/android.h>
     42 
     43 #include "reboot.h"
     44 
     45 #if defined(__ANDROID__)
     46 #include <android-base/properties.h>
     47 
     48 #include "selinux.h"
     49 #else
     50 #include "host_init_stubs.h"
     51 #endif
     52 
     53 #ifdef _INIT_INIT_H
     54 #error "Do not include init.h in files used by ueventd or watchdogd; it will expose init's globals"
     55 #endif
     56 
     57 using android::base::boot_clock;
     58 using namespace std::literals::string_literals;
     59 
     60 namespace android {
     61 namespace init {
     62 
     63 const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android/");
     64 
     65 // DecodeUid() - decodes and returns the given string, which can be either the
     66 // numeric or name representation, into the integer uid or gid.
     67 Result<uid_t> DecodeUid(const std::string& name) {
     68     if (isalpha(name[0])) {
     69         passwd* pwd = getpwnam(name.c_str());
     70         if (!pwd) return ErrnoError() << "getpwnam failed";
     71 
     72         return pwd->pw_uid;
     73     }
     74 
     75     errno = 0;
     76     uid_t result = static_cast<uid_t>(strtoul(name.c_str(), 0, 0));
     77     if (errno) return ErrnoError() << "strtoul failed";
     78 
     79     return result;
     80 }
     81 
     82 /*
     83  * CreateSocket - 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 CreateSocket(const char* name, int type, bool passcred, mode_t perm, uid_t uid, gid_t gid,
     89                  const char* socketcon) {
     90     if (socketcon) {
     91         if (setsockcreatecon(socketcon) == -1) {
     92             PLOG(ERROR) << "setsockcreatecon(\"" << socketcon << "\") failed";
     93             return -1;
     94         }
     95     }
     96 
     97     android::base::unique_fd fd(socket(PF_UNIX, type, 0));
     98     if (fd < 0) {
     99         PLOG(ERROR) << "Failed to open socket '" << name << "'";
    100         return -1;
    101     }
    102 
    103     if (socketcon) setsockcreatecon(NULL);
    104 
    105     struct sockaddr_un addr;
    106     memset(&addr, 0 , sizeof(addr));
    107     addr.sun_family = AF_UNIX;
    108     snprintf(addr.sun_path, sizeof(addr.sun_path), ANDROID_SOCKET_DIR"/%s",
    109              name);
    110 
    111     if ((unlink(addr.sun_path) != 0) && (errno != ENOENT)) {
    112         PLOG(ERROR) << "Failed to unlink old socket '" << name << "'";
    113         return -1;
    114     }
    115 
    116     std::string secontext;
    117     if (SelabelLookupFileContext(addr.sun_path, S_IFSOCK, &secontext) && !secontext.empty()) {
    118         setfscreatecon(secontext.c_str());
    119     }
    120 
    121     if (passcred) {
    122         int on = 1;
    123         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on))) {
    124             PLOG(ERROR) << "Failed to set SO_PASSCRED '" << name << "'";
    125             return -1;
    126         }
    127     }
    128 
    129     int ret = bind(fd, (struct sockaddr *) &addr, sizeof (addr));
    130     int savederrno = errno;
    131 
    132     if (!secontext.empty()) {
    133         setfscreatecon(nullptr);
    134     }
    135 
    136     if (ret) {
    137         errno = savederrno;
    138         PLOG(ERROR) << "Failed to bind socket '" << name << "'";
    139         goto out_unlink;
    140     }
    141 
    142     if (lchown(addr.sun_path, uid, gid)) {
    143         PLOG(ERROR) << "Failed to lchown socket '" << addr.sun_path << "'";
    144         goto out_unlink;
    145     }
    146     if (fchmodat(AT_FDCWD, addr.sun_path, perm, AT_SYMLINK_NOFOLLOW)) {
    147         PLOG(ERROR) << "Failed to fchmodat socket '" << addr.sun_path << "'";
    148         goto out_unlink;
    149     }
    150 
    151     LOG(INFO) << "Created socket '" << addr.sun_path << "'"
    152               << ", mode " << std::oct << perm << std::dec
    153               << ", user " << uid
    154               << ", group " << gid;
    155 
    156     return fd.release();
    157 
    158 out_unlink:
    159     unlink(addr.sun_path);
    160     return -1;
    161 }
    162 
    163 Result<std::string> ReadFile(const std::string& path) {
    164     android::base::unique_fd fd(
    165         TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_NOFOLLOW | O_CLOEXEC)));
    166     if (fd == -1) {
    167         return ErrnoError() << "open() failed";
    168     }
    169 
    170     // For security reasons, disallow world-writable
    171     // or group-writable files.
    172     struct stat sb;
    173     if (fstat(fd, &sb) == -1) {
    174         return ErrnoError() << "fstat failed()";
    175     }
    176     if ((sb.st_mode & (S_IWGRP | S_IWOTH)) != 0) {
    177         return Error() << "Skipping insecure file";
    178     }
    179 
    180     std::string content;
    181     if (!android::base::ReadFdToString(fd, &content)) {
    182         return ErrnoError() << "Unable to read file contents";
    183     }
    184     return content;
    185 }
    186 
    187 static int OpenFile(const std::string& path, int flags, mode_t mode) {
    188     std::string secontext;
    189     if (SelabelLookupFileContext(path, mode, &secontext) && !secontext.empty()) {
    190         setfscreatecon(secontext.c_str());
    191     }
    192 
    193     int rc = open(path.c_str(), flags, mode);
    194 
    195     if (!secontext.empty()) {
    196         int save_errno = errno;
    197         setfscreatecon(nullptr);
    198         errno = save_errno;
    199     }
    200 
    201     return rc;
    202 }
    203 
    204 Result<Success> WriteFile(const std::string& path, const std::string& content) {
    205     android::base::unique_fd fd(TEMP_FAILURE_RETRY(
    206         OpenFile(path, O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC | O_CLOEXEC, 0600)));
    207     if (fd == -1) {
    208         return ErrnoError() << "open() failed";
    209     }
    210     if (!android::base::WriteStringToFd(content, fd)) {
    211         return ErrnoError() << "Unable to write file contents";
    212     }
    213     return Success();
    214 }
    215 
    216 bool mkdir_recursive(const std::string& path, mode_t mode) {
    217     std::string::size_type slash = 0;
    218     while ((slash = path.find('/', slash + 1)) != std::string::npos) {
    219         auto directory = path.substr(0, slash);
    220         struct stat info;
    221         if (stat(directory.c_str(), &info) != 0) {
    222             auto ret = make_dir(directory, mode);
    223             if (!ret && errno != EEXIST) return false;
    224         }
    225     }
    226     auto ret = make_dir(path, mode);
    227     if (!ret && errno != EEXIST) return false;
    228     return true;
    229 }
    230 
    231 int wait_for_file(const char* filename, std::chrono::nanoseconds timeout) {
    232     android::base::Timer t;
    233     while (t.duration() < timeout) {
    234         struct stat sb;
    235         if (stat(filename, &sb) != -1) {
    236             LOG(INFO) << "wait for '" << filename << "' took " << t;
    237             return 0;
    238         }
    239         std::this_thread::sleep_for(10ms);
    240     }
    241     LOG(WARNING) << "wait for '" << filename << "' timed out and took " << t;
    242     return -1;
    243 }
    244 
    245 void import_kernel_cmdline(bool in_qemu,
    246                            const std::function<void(const std::string&, const std::string&, bool)>& fn) {
    247     std::string cmdline;
    248     android::base::ReadFileToString("/proc/cmdline", &cmdline);
    249 
    250     for (const auto& entry : android::base::Split(android::base::Trim(cmdline), " ")) {
    251         std::vector<std::string> pieces = android::base::Split(entry, "=");
    252         if (pieces.size() == 2) {
    253             fn(pieces[0], pieces[1], in_qemu);
    254         }
    255     }
    256 }
    257 
    258 bool make_dir(const std::string& path, mode_t mode) {
    259     std::string secontext;
    260     if (SelabelLookupFileContext(path, mode, &secontext) && !secontext.empty()) {
    261         setfscreatecon(secontext.c_str());
    262     }
    263 
    264     int rc = mkdir(path.c_str(), mode);
    265 
    266     if (!secontext.empty()) {
    267         int save_errno = errno;
    268         setfscreatecon(nullptr);
    269         errno = save_errno;
    270     }
    271 
    272     return rc == 0;
    273 }
    274 
    275 /*
    276  * Writes hex_len hex characters (1/2 byte) to hex from bytes.
    277  */
    278 std::string bytes_to_hex(const uint8_t* bytes, size_t bytes_len) {
    279     std::string hex("0x");
    280     for (size_t i = 0; i < bytes_len; i++)
    281         android::base::StringAppendF(&hex, "%02x", bytes[i]);
    282     return hex;
    283 }
    284 
    285 /*
    286  * Returns true is pathname is a directory
    287  */
    288 bool is_dir(const char* pathname) {
    289     struct stat info;
    290     if (stat(pathname, &info) == -1) {
    291         return false;
    292     }
    293     return S_ISDIR(info.st_mode);
    294 }
    295 
    296 bool expand_props(const std::string& src, std::string* dst) {
    297     const char* src_ptr = src.c_str();
    298 
    299     if (!dst) {
    300         return false;
    301     }
    302 
    303     /* - variables can either be $x.y or ${x.y}, in case they are only part
    304      *   of the string.
    305      * - will accept $$ as a literal $.
    306      * - no nested property expansion, i.e. ${foo.${bar}} is not supported,
    307      *   bad things will happen
    308      * - ${x.y:-default} will return default value if property empty.
    309      */
    310     while (*src_ptr) {
    311         const char* c;
    312 
    313         c = strchr(src_ptr, '$');
    314         if (!c) {
    315             dst->append(src_ptr);
    316             return true;
    317         }
    318 
    319         dst->append(src_ptr, c);
    320         c++;
    321 
    322         if (*c == '$') {
    323             dst->push_back(*(c++));
    324             src_ptr = c;
    325             continue;
    326         } else if (*c == '\0') {
    327             return true;
    328         }
    329 
    330         std::string prop_name;
    331         std::string def_val;
    332         if (*c == '{') {
    333             c++;
    334             const char* end = strchr(c, '}');
    335             if (!end) {
    336                 // failed to find closing brace, abort.
    337                 LOG(ERROR) << "unexpected end of string in '" << src << "', looking for }";
    338                 return false;
    339             }
    340             prop_name = std::string(c, end);
    341             c = end + 1;
    342             size_t def = prop_name.find(":-");
    343             if (def < prop_name.size()) {
    344                 def_val = prop_name.substr(def + 2);
    345                 prop_name = prop_name.substr(0, def);
    346             }
    347         } else {
    348             prop_name = c;
    349             LOG(ERROR) << "using deprecated syntax for specifying property '" << c << "', use ${name} instead";
    350             c += prop_name.size();
    351         }
    352 
    353         if (prop_name.empty()) {
    354             LOG(ERROR) << "invalid zero-length property name in '" << src << "'";
    355             return false;
    356         }
    357 
    358         std::string prop_val = android::base::GetProperty(prop_name, "");
    359         if (prop_val.empty()) {
    360             if (def_val.empty()) {
    361                 LOG(ERROR) << "property '" << prop_name << "' doesn't exist while expanding '" << src << "'";
    362                 return false;
    363             }
    364             prop_val = def_val;
    365         }
    366 
    367         dst->append(prop_val);
    368         src_ptr = c;
    369     }
    370 
    371     return true;
    372 }
    373 
    374 static std::string init_android_dt_dir() {
    375     // Use the standard procfs-based path by default
    376     std::string android_dt_dir = kDefaultAndroidDtDir;
    377     // The platform may specify a custom Android DT path in kernel cmdline
    378     import_kernel_cmdline(false,
    379                           [&](const std::string& key, const std::string& value, bool in_qemu) {
    380                               if (key == "androidboot.android_dt_dir") {
    381                                   android_dt_dir = value;
    382                               }
    383                           });
    384     LOG(INFO) << "Using Android DT directory " << android_dt_dir;
    385     return android_dt_dir;
    386 }
    387 
    388 // FIXME: The same logic is duplicated in system/core/fs_mgr/
    389 const std::string& get_android_dt_dir() {
    390     // Set once and saves time for subsequent calls to this function
    391     static const std::string kAndroidDtDir = init_android_dt_dir();
    392     return kAndroidDtDir;
    393 }
    394 
    395 // Reads the content of device tree file under the platform's Android DT directory.
    396 // Returns true if the read is success, false otherwise.
    397 bool read_android_dt_file(const std::string& sub_path, std::string* dt_content) {
    398     const std::string file_name = get_android_dt_dir() + sub_path;
    399     if (android::base::ReadFileToString(file_name, dt_content)) {
    400         if (!dt_content->empty()) {
    401             dt_content->pop_back();  // Trims the trailing '\0' out.
    402             return true;
    403         }
    404     }
    405     return false;
    406 }
    407 
    408 bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content) {
    409     std::string dt_content;
    410     if (read_android_dt_file(sub_path, &dt_content)) {
    411         if (dt_content == expected_content) {
    412             return true;
    413         }
    414     }
    415     return false;
    416 }
    417 
    418 bool IsLegalPropertyName(const std::string& name) {
    419     size_t namelen = name.size();
    420 
    421     if (namelen < 1) return false;
    422     if (name[0] == '.') return false;
    423     if (name[namelen - 1] == '.') return false;
    424 
    425     /* Only allow alphanumeric, plus '.', '-', '@', ':', or '_' */
    426     /* Don't allow ".." to appear in a property name */
    427     for (size_t i = 0; i < namelen; i++) {
    428         if (name[i] == '.') {
    429             // i=0 is guaranteed to never have a dot. See above.
    430             if (name[i - 1] == '.') return false;
    431             continue;
    432         }
    433         if (name[i] == '_' || name[i] == '-' || name[i] == '@' || name[i] == ':') continue;
    434         if (name[i] >= 'a' && name[i] <= 'z') continue;
    435         if (name[i] >= 'A' && name[i] <= 'Z') continue;
    436         if (name[i] >= '0' && name[i] <= '9') continue;
    437         return false;
    438     }
    439 
    440     return true;
    441 }
    442 
    443 }  // namespace init
    444 }  // namespace android
    445