1 /* 2 * Copyright (C) 2015 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 #ifndef ANDROID_VOLD_UTILS_H 18 #define ANDROID_VOLD_UTILS_H 19 20 #include "KeyBuffer.h" 21 22 #include <android-base/macros.h> 23 #include <android-base/unique_fd.h> 24 #include <cutils/multiuser.h> 25 #include <selinux/selinux.h> 26 #include <utils/Errors.h> 27 28 #include <chrono> 29 #include <string> 30 #include <string_view> 31 #include <vector> 32 33 struct DIR; 34 35 namespace android { 36 namespace vold { 37 38 static const char* kVoldAppDataIsolationEnabled = "persist.sys.vold_app_data_isolation_enabled"; 39 static const char* kExternalStorageSdcardfs = "external_storage.sdcardfs.enabled"; 40 41 /* SELinux contexts used depending on the block device type */ 42 extern security_context_t sBlkidContext; 43 extern security_context_t sBlkidUntrustedContext; 44 extern security_context_t sFsckContext; 45 extern security_context_t sFsckUntrustedContext; 46 47 // TODO remove this with better solution, b/64143519 48 extern bool sSleepOnUnmount; 49 50 std::string GetFuseMountPathForUser(userid_t user_id, const std::string& relative_upper_path); 51 52 status_t CreateDeviceNode(const std::string& path, dev_t dev); 53 status_t DestroyDeviceNode(const std::string& path); 54 55 status_t SetDefaultAcl(const std::string& path, mode_t mode, uid_t uid, gid_t gid, 56 std::vector<gid_t> additionalGids); 57 58 status_t AbortFuseConnections(); 59 60 int SetQuotaInherit(const std::string& path); 61 int SetQuotaProjectId(const std::string& path, long projectId); 62 /* 63 * Creates and sets up an application-specific path on external 64 * storage with the correct ACL and project ID (if needed). 65 * 66 * ONLY for use with app-specific data directories on external storage! 67 * (eg, /Android/data/com.foo, /Android/obb/com.foo, etc.) 68 */ 69 int PrepareAppDirFromRoot(const std::string& path, const std::string& root, int appUid, 70 bool fixupExisting); 71 72 /* fs_prepare_dir wrapper that creates with SELinux context */ 73 status_t PrepareDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid, 74 unsigned int attrs = 0); 75 76 /* Really unmounts the path, killing active processes along the way */ 77 status_t ForceUnmount(const std::string& path); 78 79 /* Kills any processes using given path */ 80 status_t KillProcessesUsingPath(const std::string& path); 81 82 /* Kills any processes using given tmpfs mount prifix */ 83 status_t KillProcessesWithTmpfsMountPrefix(const std::string& path); 84 85 /* Creates bind mount from source to target */ 86 status_t BindMount(const std::string& source, const std::string& target); 87 88 /** Creates a symbolic link to target */ 89 status_t Symlink(const std::string& target, const std::string& linkpath); 90 91 /** Calls unlink(2) at linkpath */ 92 status_t Unlink(const std::string& linkpath); 93 94 /** Creates the given directory if it is not already available */ 95 status_t CreateDir(const std::string& dir, mode_t mode); 96 97 bool FindValue(const std::string& raw, const std::string& key, std::string* value); 98 99 /* Reads filesystem metadata from device at path */ 100 status_t ReadMetadata(const std::string& path, std::string* fsType, std::string* fsUuid, 101 std::string* fsLabel); 102 103 /* Reads filesystem metadata from untrusted device at path */ 104 status_t ReadMetadataUntrusted(const std::string& path, std::string* fsType, std::string* fsUuid, 105 std::string* fsLabel); 106 107 /* Returns either WEXITSTATUS() status, or a negative errno */ 108 status_t ForkExecvp(const std::vector<std::string>& args, std::vector<std::string>* output = nullptr, 109 security_context_t context = nullptr); 110 111 pid_t ForkExecvpAsync(const std::vector<std::string>& args); 112 113 /* Gets block device size in bytes */ 114 status_t GetBlockDevSize(int fd, uint64_t* size); 115 status_t GetBlockDevSize(const std::string& path, uint64_t* size); 116 /* Gets block device size in 512 byte sectors */ 117 status_t GetBlockDev512Sectors(const std::string& path, uint64_t* nr_sec); 118 119 status_t ReadRandomBytes(size_t bytes, std::string& out); 120 status_t ReadRandomBytes(size_t bytes, char* buffer); 121 status_t GenerateRandomUuid(std::string& out); 122 123 /* Converts hex string to raw bytes, ignoring [ :-] */ 124 status_t HexToStr(const std::string& hex, std::string& str); 125 /* Converts raw bytes to hex string */ 126 status_t StrToHex(const std::string& str, std::string& hex); 127 /* Converts raw key bytes to hex string */ 128 status_t StrToHex(const KeyBuffer& str, KeyBuffer& hex); 129 /* Normalize given hex string into consistent format */ 130 status_t NormalizeHex(const std::string& in, std::string& out); 131 132 uint64_t GetFreeBytes(const std::string& path); 133 uint64_t GetTreeBytes(const std::string& path); 134 135 bool IsFilesystemSupported(const std::string& fsType); 136 bool IsSdcardfsUsed(); 137 bool IsFuseDaemon(const pid_t pid); 138 139 /* Wipes contents of block device at given path */ 140 status_t WipeBlockDevice(const std::string& path); 141 142 std::string BuildKeyPath(const std::string& partGuid); 143 144 std::string BuildDataSystemLegacyPath(userid_t userid); 145 std::string BuildDataSystemCePath(userid_t userid); 146 std::string BuildDataSystemDePath(userid_t userid); 147 std::string BuildDataMiscLegacyPath(userid_t userid); 148 std::string BuildDataMiscCePath(userid_t userid); 149 std::string BuildDataMiscDePath(userid_t userid); 150 std::string BuildDataProfilesDePath(userid_t userid); 151 std::string BuildDataVendorCePath(userid_t userid); 152 std::string BuildDataVendorDePath(userid_t userid); 153 154 std::string BuildDataPath(const std::string& volumeUuid); 155 std::string BuildDataMediaCePath(const std::string& volumeUuid, userid_t userid); 156 std::string BuildDataUserCePath(const std::string& volumeUuid, userid_t userid); 157 std::string BuildDataUserDePath(const std::string& volumeUuid, userid_t userid); 158 159 dev_t GetDevice(const std::string& path); 160 161 bool IsSameFile(const std::string& path1, const std::string& path2); 162 163 status_t EnsureDirExists(const std::string& path, mode_t mode, uid_t uid, gid_t gid); 164 165 status_t RestoreconRecursive(const std::string& path); 166 167 // TODO: promote to android::base 168 bool Readlinkat(int dirfd, const std::string& path, std::string* result); 169 170 // Handles dynamic major assignment for virtio-block 171 bool IsVirtioBlkDevice(unsigned int major); 172 173 status_t UnmountTreeWithPrefix(const std::string& prefix); 174 status_t UnmountTree(const std::string& mountPoint); 175 176 bool IsDotOrDotDot(const struct dirent& ent); 177 178 status_t DeleteDirContentsAndDir(const std::string& pathname); 179 status_t DeleteDirContents(const std::string& pathname); 180 181 status_t WaitForFile(const char* filename, std::chrono::nanoseconds timeout); 182 183 bool pathExists(const std::string& path); 184 185 bool FsyncDirectory(const std::string& dirname); 186 187 bool FsyncParentDirectory(const std::string& path); 188 189 bool MkdirsSync(const std::string& path, mode_t mode); 190 191 bool writeStringToFile(const std::string& payload, const std::string& filename); 192 193 void ConfigureMaxDirtyRatioForFuse(const std::string& fuse_mount, unsigned int max_ratio); 194 195 void ConfigureReadAheadForFuse(const std::string& fuse_mount, size_t read_ahead_kb); 196 197 status_t MountUserFuse(userid_t user_id, const std::string& absolute_lower_path, 198 const std::string& relative_upper_path, android::base::unique_fd* fuse_fd); 199 200 status_t UnmountUserFuse(userid_t userId, const std::string& absolute_lower_path, 201 const std::string& relative_upper_path); 202 203 status_t PrepareAndroidDirs(const std::string& volumeRoot); 204 205 // Open a given directory as an FD, and return that and the corresponding procfs virtual 206 // symlink path that can be used in any API that accepts a path string. Path stays valid until 207 // the directory FD is closed. 208 // 209 // This may be useful when an API wants to restrict a path passed from an untrusted process, 210 // and do it without any TOCTOU attacks possible (e.g. where an attacker replaces one of 211 // the components with a symlink after the check passed). In that case opening a path through 212 // this function guarantees that the target directory stays the same, and that it can be 213 // referenced inside the current process via the virtual procfs symlink returned here. 214 std::pair<android::base::unique_fd, std::string> OpenDirInProcfs(std::string_view path); 215 216 } // namespace vold 217 } // namespace android 218 219 #endif 220