1 /*
2 * Copyright (C) 2017 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 /*
18 * Tool to create a directory with the right SELinux context applied, or
19 * apply the context if it's absent. Also fixes mode, uid, gid.
20 */
21
22 #include <iostream>
23 #include <string>
24 #include <vector>
25
26 #include <dirent.h>
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <sys/stat.h>
30 #include <sys/types.h>
31
32 #include <android-base/logging.h>
33 #include <android-base/scopeguard.h>
34
35 #include <cutils/fs.h>
36 #include <selinux/android.h>
37
38 #include "Utils.h"
39 #include "android/os/IVold.h"
40
41 #include <private/android_filesystem_config.h>
42
usage(const char * progname)43 static void usage(const char* progname) {
44 std::cerr << "Usage: " << progname << " [ prepare | destroy ] <volume_uuid> <user_id> <flags>"
45 << std::endl;
46 exit(-1);
47 }
48
small_int(const std::string & s)49 static bool small_int(const std::string& s) {
50 return !s.empty() && s.size() < 7 && s.find_first_not_of("0123456789") == std::string::npos;
51 }
52
valid_uuid(const std::string & s)53 static bool valid_uuid(const std::string& s) {
54 return s.size() < 40 && s.find_first_not_of("0123456789abcdefABCDEF-_") == std::string::npos;
55 }
56
prepare_dir(struct selabel_handle * sehandle,mode_t mode,uid_t uid,gid_t gid,const std::string & path)57 static bool prepare_dir(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
58 const std::string& path) {
59 auto clearfscreatecon = android::base::make_scope_guard([] { setfscreatecon(nullptr); });
60 auto secontext = std::unique_ptr<char, void (*)(char*)>(nullptr, freecon);
61 char* tmp_secontext;
62 if (sehandle && selabel_lookup(sehandle, &tmp_secontext, path.c_str(), S_IFDIR) == 0) {
63 secontext.reset(tmp_secontext);
64 }
65 LOG(DEBUG) << "Setting up mode " << std::oct << mode << std::dec << " uid " << uid << " gid "
66 << gid << " context " << secontext.get() << " on path: " << path;
67 if (secontext) {
68 if (setfscreatecon(secontext.get()) != 0) {
69 PLOG(ERROR) << "Unable to read setfscreatecon for: " << path;
70 return false;
71 }
72 }
73 if (fs_prepare_dir(path.c_str(), mode, uid, gid) != 0) {
74 return false;
75 }
76 if (secontext) {
77 char* tmp_oldsecontext = nullptr;
78 if (lgetfilecon(path.c_str(), &tmp_oldsecontext) < 0) {
79 PLOG(ERROR) << "Unable to read secontext for: " << path;
80 return false;
81 }
82 auto oldsecontext = std::unique_ptr<char, void (*)(char*)>(tmp_oldsecontext, freecon);
83 if (strcmp(secontext.get(), oldsecontext.get()) != 0) {
84 LOG(INFO) << "Relabelling from " << ((char*)oldsecontext.get()) << " to "
85 << ((char*)secontext.get()) << ": " << path;
86 if (lsetfilecon(path.c_str(), secontext.get()) != 0) {
87 PLOG(ERROR) << "Relabelling failed for: " << path;
88 return false;
89 }
90 }
91 }
92 return true;
93 }
94
rmrf_contents(const std::string & path)95 static bool rmrf_contents(const std::string& path) {
96 auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(path.c_str()), closedir);
97 if (!dirp) {
98 PLOG(ERROR) << "Unable to open directory: " << path;
99 return false;
100 }
101 bool res = true;
102 for (;;) {
103 errno = 0;
104 auto const entry = readdir(dirp.get());
105 if (!entry) {
106 if (errno) {
107 PLOG(ERROR) << "readdir failed on: " << path;
108 return false;
109 }
110 return res;
111 }
112 if (entry->d_name[0] == '.') continue;
113 auto subdir = path + "/" + entry->d_name;
114 if (0 !=
115 android::vold::ForkExecvp(std::vector<std::string>{"/system/bin/rm", "-rf", subdir})) {
116 LOG(ERROR) << "rm -rf failed on " << subdir;
117 res = false;
118 }
119 }
120 }
121
prepare_subdirs(const std::string & volume_uuid,int user_id,int flags)122 static bool prepare_subdirs(const std::string& volume_uuid, int user_id, int flags) {
123 struct selabel_handle* sehandle = selinux_android_file_context_handle();
124
125 if (volume_uuid.empty()) {
126 if (flags & android::os::IVold::STORAGE_FLAG_DE) {
127 auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
128 if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/vold")) return false;
129 if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/storaged")) return false;
130
131 auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
132 if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, vendor_de_path + "/fpdata")) {
133 return false;
134 }
135 }
136 if (flags & android::os::IVold::STORAGE_FLAG_CE) {
137 auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
138 if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/vold")) return false;
139 if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/storaged")) return false;
140 }
141 }
142 return true;
143 }
144
destroy_subdirs(const std::string & volume_uuid,int user_id,int flags)145 static bool destroy_subdirs(const std::string& volume_uuid, int user_id, int flags) {
146 bool res = true;
147 if (volume_uuid.empty()) {
148 if (flags & android::os::IVold::STORAGE_FLAG_CE) {
149 auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
150 res &= rmrf_contents(misc_ce_path);
151
152 auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
153 res &= rmrf_contents(vendor_ce_path);
154 }
155 if (flags & android::os::IVold::STORAGE_FLAG_DE) {
156 auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
157 res &= rmrf_contents(misc_de_path);
158
159 auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
160 res &= rmrf_contents(vendor_de_path);
161 }
162 }
163 return res;
164 }
165
main(int argc,const char * const argv[])166 int main(int argc, const char* const argv[]) {
167 android::base::InitLogging(const_cast<char**>(argv));
168 std::vector<std::string> args(argv + 1, argv + argc);
169
170 if (args.size() != 4 || !valid_uuid(args[1]) || !small_int(args[2]) || !small_int(args[3])) {
171 usage(argv[0]);
172 return -1;
173 }
174
175 auto volume_uuid = args[1];
176 int user_id = stoi(args[2]);
177 int flags = stoi(args[3]);
178 if (args[0] == "prepare") {
179 if (!prepare_subdirs(volume_uuid, user_id, flags)) return -1;
180 } else if (args[0] == "destroy") {
181 if (!destroy_subdirs(volume_uuid, user_id, flags)) return -1;
182 } else {
183 usage(argv[0]);
184 return -1;
185 }
186 return 0;
187 }
188