Stop using a regex for setupAppDir.
This was hard to read and understand. Instead, fall back to explicit
string operations with more comments on what we're doing and what we're
allowing.
This also fixes an issue where apps were asking us to create dirs on
their behalf that our more than 2 levels deep, eg
com.foo/files/downloads ; I thought such paths weren't allowed, but
apparently they are (and there's no good reason for us to not set them
up correctly).
Bug: 149407572
Test: launch opera
Change-Id: I7c64831032b66e90960b96e41ee42c7d616a759c
diff --git a/Utils.cpp b/Utils.cpp
index b31008c..6a67071 100644
--- a/Utils.cpp
+++ b/Utils.cpp
@@ -223,77 +223,103 @@
return ret;
}
-static gid_t getAppDirGid(const std::string& appDir) {
- gid_t gid = AID_MEDIA_RW;
- if (!IsFilesystemSupported("sdcardfs")) {
- if (appDir == android::vold::kAppDataDir) {
- gid = AID_EXT_DATA_RW;
- } else if (appDir == android::vold::kAppObbDir) {
- gid = AID_EXT_OBB_RW;
- } else if (appDir == android::vold::kAppMediaDir) {
- gid = AID_MEDIA_RW;
- } else {
- gid = AID_MEDIA_RW;
- }
+int PrepareAppDirFromRoot(const std::string& path, const std::string& root, int appUid) {
+ long projectId;
+ size_t pos;
+ int ret = 0;
+
+ // Make sure the Android/ directories exist and are setup correctly
+ ret = PrepareAndroidDirs(root);
+ if (ret != 0) {
+ LOG(ERROR) << "Failed to prepare Android/ directories.";
+ return ret;
}
- return gid;
-}
+ // Now create the application-specific subdir(s)
+ // path is something like /data/media/0/Android/data/com.foo/files
+ // First, chop off the volume root, eg /data/media/0
+ std::string pathFromRoot = path.substr(root.length());
-int PrepareAppDirFromRoot(std::string path, int appUid) {
- int ret = 0;
- // Extract various parts of the path to setup correctly
- // Sample path:
- // /data/media/0/Android/data/com.foo/files
- // [1]: path in which to create app-specific dir, eg. /data/media/0/Android/data/
- // [2]: the part of [1] starting from /Android, eg. /Android/data/
- // [3]: the package name part of the path, eg. com.foo
- // [4]: the directory to create within [3], eg files
- std::regex re("(^/.*(/Android/(?:data|media|obb|sandbox)/))([^/]+)/([^/]+)?/?");
+ uid_t uid = appUid;
+ gid_t gid = AID_MEDIA_RW;
+ std::string appDir;
- std::smatch match;
- bool is_match = regex_match(path, match, re);
-
- if (!is_match) {
+ // Check that the next part matches one of the allowed Android/ dirs
+ if (StartsWith(pathFromRoot, kAppDataDir)) {
+ appDir = kAppDataDir;
+ if (!IsFilesystemSupported("sdcardfs")) {
+ gid = AID_EXT_DATA_RW;
+ }
+ } else if (StartsWith(pathFromRoot, kAppMediaDir)) {
+ appDir = kAppMediaDir;
+ if (!IsFilesystemSupported("sdcardfs")) {
+ gid = AID_MEDIA_RW;
+ }
+ } else if (StartsWith(pathFromRoot, kAppMediaDir)) {
+ appDir = kAppObbDir;
+ if (!IsFilesystemSupported("sdcardfs")) {
+ gid = AID_EXT_OBB_RW;
+ }
+ } else {
LOG(ERROR) << "Invalid application directory: " << path;
return -EINVAL;
}
- uid_t uid = appUid;
- gid_t gid = getAppDirGid(match.str(2));
// mode = 770, plus sticky bit on directory to inherit GID when apps
// create subdirs
mode_t mode = S_IRWXU | S_IRWXG | S_ISGID;
- long projectId = uid - AID_APP_START + AID_EXT_GID_START;
+ // the project ID for application-specific directories is directly
+ // derived from their uid
- // First, create the package-path
- std::string package_path = match.str(1) + match.str(3);
- ret = PrepareDirWithProjectId(package_path, mode, uid, gid, projectId);
- if (ret) {
- return ret;
+ // Chop off the generic application-specific part, eg /Android/data/
+ // this leaves us with something like com.foo/files/
+ std::string leftToCreate = pathFromRoot.substr(appDir.length());
+ if (!EndsWith(leftToCreate, "/")) {
+ leftToCreate += "/";
+ }
+ std::string pathToCreate = root + appDir;
+ int depth = 0;
+ bool withinCache = false;
+ while ((pos = leftToCreate.find('/')) != std::string::npos) {
+ std::string component = leftToCreate.substr(0, pos + 1);
+ leftToCreate = leftToCreate.erase(0, pos + 1);
+ pathToCreate = pathToCreate + component;
+
+ if (appDir == kAppDataDir && depth == 1 && component == "cache/") {
+ // All dirs use the "app" project ID, except for the cache dirs in
+ // Android/data, eg Android/data/com.foo/cache
+ // Note that this "sticks" - eg subdirs of this dir need the same
+ // project ID.
+ withinCache = true;
+ }
+ if (withinCache) {
+ projectId = uid - AID_APP_START + AID_CACHE_GID_START;
+ } else {
+ projectId = uid - AID_APP_START + AID_EXT_GID_START;
+ }
+ ret = PrepareDirWithProjectId(pathToCreate, mode, uid, gid, projectId);
+ if (ret != 0) {
+ return ret;
+ }
+
+ if (depth == 0) {
+ // Set the default ACL on the top-level application-specific directories,
+ // to ensure that even if applications run with a umask of 0077,
+ // new directories within these directories will allow the GID
+ // specified here to write; this is necessary for apps like
+ // installers and MTP, that require access here.
+ //
+ // See man (5) acl for more details.
+ ret = SetDefault770Acl(pathToCreate, uid, gid);
+ if (ret != 0) {
+ return ret;
+ }
+ }
+
+ depth++;
}
- // Set the default ACL, to ensure that even if applications run with a
- // umask of 0077, new directories within these directories will allow the
- // GID specified here to write; this is necessary for apps like installers
- // and MTP, that require access here.
- //
- // See man (5) acl for more details.
- ret = SetDefault770Acl(package_path, uid, gid);
- if (ret) {
- return ret;
- }
-
- // Next, create the directory within the package, if needed
- if (match.size() <= 4) {
- return OK;
- }
-
- if (match.str(4) == "cache") {
- // All dirs use the "app" project ID, except for the cache dir
- projectId = uid - AID_APP_START + AID_CACHE_GID_START;
- }
- return PrepareDirWithProjectId(path, mode, uid, gid, projectId);
+ return OK;
}
status_t PrepareDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid) {