1da49dc9b4
Deny write access to /data/resource-cache for UIDs other than root and system. While this is already handled by SELinux rules, add an additional layer of security to explicitly prevent malicious apps from messing with the system's idmap files. Test: make idmap2_tests Change-Id: Id986633558d5d02452276f05f64337a8700f148a
111 lines
3.3 KiB
C++
111 lines
3.3 KiB
C++
/*
|
|
* Copyright (C) 2018 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#include <dirent.h>
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
|
|
#include <cerrno>
|
|
#include <climits>
|
|
#include <cstdlib>
|
|
#include <cstring>
|
|
#include <fstream>
|
|
#include <memory>
|
|
#include <string>
|
|
#include <utility>
|
|
#include <vector>
|
|
|
|
#include "android-base/file.h"
|
|
#include "android-base/macros.h"
|
|
#include "android-base/stringprintf.h"
|
|
#include "private/android_filesystem_config.h"
|
|
|
|
#include "idmap2/FileUtils.h"
|
|
|
|
namespace android::idmap2::utils {
|
|
|
|
std::unique_ptr<std::vector<std::string>> FindFiles(const std::string& root, bool recurse,
|
|
const FindFilesPredicate& predicate) {
|
|
DIR* dir = opendir(root.c_str());
|
|
if (dir == nullptr) {
|
|
return nullptr;
|
|
}
|
|
std::unique_ptr<std::vector<std::string>> vector(new std::vector<std::string>());
|
|
struct dirent* dirent;
|
|
while ((dirent = readdir(dir)) != nullptr) {
|
|
const std::string path = root + "/" + dirent->d_name;
|
|
if (predicate(dirent->d_type, path)) {
|
|
vector->push_back(path);
|
|
}
|
|
if (recurse && dirent->d_type == DT_DIR && strcmp(dirent->d_name, ".") != 0 &&
|
|
strcmp(dirent->d_name, "..") != 0) {
|
|
auto sub_vector = FindFiles(path, recurse, predicate);
|
|
if (!sub_vector) {
|
|
closedir(dir);
|
|
return nullptr;
|
|
}
|
|
vector->insert(vector->end(), sub_vector->begin(), sub_vector->end());
|
|
}
|
|
}
|
|
closedir(dir);
|
|
|
|
return vector;
|
|
}
|
|
|
|
std::unique_ptr<std::string> ReadFile(const std::string& path) {
|
|
std::unique_ptr<std::string> str(new std::string());
|
|
std::ifstream fin(path);
|
|
str->append({std::istreambuf_iterator<char>(fin), std::istreambuf_iterator<char>()});
|
|
fin.close();
|
|
return str;
|
|
}
|
|
|
|
std::unique_ptr<std::string> ReadFile(int fd) {
|
|
static constexpr const size_t kBufSize = 1024;
|
|
|
|
std::unique_ptr<std::string> str(new std::string());
|
|
char buf[kBufSize];
|
|
ssize_t r;
|
|
while ((r = read(fd, buf, sizeof(buf))) > 0) {
|
|
str->append(buf, r);
|
|
}
|
|
return r == 0 ? std::move(str) : nullptr;
|
|
}
|
|
|
|
#ifdef __ANDROID__
|
|
bool UidHasWriteAccessToPath(uid_t uid, const std::string& path) {
|
|
// resolve symlinks and relative paths; the directories must exist
|
|
std::string canonical_path;
|
|
if (!base::Realpath(base::Dirname(path), &canonical_path)) {
|
|
return false;
|
|
}
|
|
|
|
const std::string cache_subdir = base::StringPrintf("%s/", kIdmapCacheDir);
|
|
if (canonical_path == kIdmapCacheDir ||
|
|
canonical_path.compare(0, cache_subdir.size(), cache_subdir) == 0) {
|
|
// limit access to /data/resource-cache to root and system
|
|
return uid == AID_ROOT || uid == AID_SYSTEM;
|
|
}
|
|
return true;
|
|
}
|
|
#else
|
|
bool UidHasWriteAccessToPath(uid_t uid ATTRIBUTE_UNUSED, const std::string& path ATTRIBUTE_UNUSED) {
|
|
return true;
|
|
}
|
|
#endif
|
|
|
|
} // namespace android::idmap2::utils
|