18eb877246
Vold was trusting system_server too much and allowed for pretty much any path in mount()/bindMount() calls for incremental. This CL adds validation to make sure it's only accessing own directories. This includes enforcing no symlinks in the paths Bug: 198657657 Bug: 216722132 Test: manual Change-Id: I6035447f94ef44c4ae3294c3ae47de2d7210683a Merged-In: I6035447f94ef44c4ae3294c3ae47de2d7210683a
224 lines
8.7 KiB
C++
224 lines
8.7 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_VOLD_UTILS_H
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#define ANDROID_VOLD_UTILS_H
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#include "KeyBuffer.h"
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#include <android-base/macros.h>
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#include <android-base/unique_fd.h>
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#include <cutils/multiuser.h>
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#include <selinux/selinux.h>
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#include <utils/Errors.h>
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#include <chrono>
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#include <string>
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#include <string_view>
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#include <vector>
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struct DIR;
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namespace android {
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namespace vold {
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static const char* kVoldAppDataIsolationEnabled = "persist.sys.vold_app_data_isolation_enabled";
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static const char* kExternalStorageSdcardfs = "external_storage.sdcardfs.enabled";
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static const char* kFuseBpfEnabled = "persist.sys.fuse.bpf.enable";
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static constexpr std::chrono::seconds kUntrustedFsckSleepTime(45);
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/* SELinux contexts used depending on the block device type */
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extern char* sBlkidContext;
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extern char* sBlkidUntrustedContext;
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extern char* sFsckContext;
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extern char* sFsckUntrustedContext;
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// TODO remove this with better solution, b/64143519
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extern bool sSleepOnUnmount;
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std::string GetFuseMountPathForUser(userid_t user_id, const std::string& relative_upper_path);
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status_t CreateDeviceNode(const std::string& path, dev_t dev);
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status_t DestroyDeviceNode(const std::string& path);
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status_t SetDefaultAcl(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
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std::vector<gid_t> additionalGids);
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status_t AbortFuseConnections();
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int SetQuotaInherit(const std::string& path);
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int SetQuotaProjectId(const std::string& path, long projectId);
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/*
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* Creates and sets up an application-specific path on external
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* storage with the correct ACL and project ID (if needed).
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*
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* ONLY for use with app-specific data directories on external storage!
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* (eg, /Android/data/com.foo, /Android/obb/com.foo, etc.)
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*/
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int PrepareAppDirFromRoot(const std::string& path, const std::string& root, int appUid,
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bool fixupExisting);
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/* fs_prepare_dir wrapper that creates with SELinux context */
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status_t PrepareDir(const std::string& path, mode_t mode, uid_t uid, gid_t gid,
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unsigned int attrs = 0);
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/* Really unmounts the path, killing active processes along the way */
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status_t ForceUnmount(const std::string& path);
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/* Kills any processes using given path */
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status_t KillProcessesUsingPath(const std::string& path);
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/* Kills any processes using given tmpfs mount prifix */
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status_t KillProcessesWithTmpfsMountPrefix(const std::string& path);
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/* Creates bind mount from source to target */
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status_t BindMount(const std::string& source, const std::string& target);
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/** Creates a symbolic link to target */
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status_t Symlink(const std::string& target, const std::string& linkpath);
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/** Calls unlink(2) at linkpath */
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status_t Unlink(const std::string& linkpath);
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/** Creates the given directory if it is not already available */
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status_t CreateDir(const std::string& dir, mode_t mode);
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bool FindValue(const std::string& raw, const std::string& key, std::string* value);
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/* Reads filesystem metadata from device at path */
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status_t ReadMetadata(const std::string& path, std::string* fsType, std::string* fsUuid,
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std::string* fsLabel);
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/* Reads filesystem metadata from untrusted device at path */
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status_t ReadMetadataUntrusted(const std::string& path, std::string* fsType, std::string* fsUuid,
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std::string* fsLabel);
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/* Returns either WEXITSTATUS() status, or a negative errno */
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status_t ForkExecvp(const std::vector<std::string>& args,
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std::vector<std::string>* output = nullptr, char* context = nullptr);
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status_t ForkExecvpTimeout(const std::vector<std::string>& args, std::chrono::seconds timeout,
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char* context = nullptr);
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pid_t ForkExecvpAsync(const std::vector<std::string>& args, char* context = nullptr);
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/* Gets block device size in bytes */
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status_t GetBlockDevSize(int fd, uint64_t* size);
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status_t GetBlockDevSize(const std::string& path, uint64_t* size);
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/* Gets block device size in 512 byte sectors */
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status_t GetBlockDev512Sectors(const std::string& path, uint64_t* nr_sec);
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status_t ReadRandomBytes(size_t bytes, std::string& out);
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status_t ReadRandomBytes(size_t bytes, char* buffer);
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status_t GenerateRandomUuid(std::string& out);
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/* Converts hex string to raw bytes, ignoring [ :-] */
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status_t HexToStr(const std::string& hex, std::string& str);
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/* Converts raw bytes to hex string */
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status_t StrToHex(const std::string& str, std::string& hex);
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/* Converts raw key bytes to hex string */
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status_t StrToHex(const KeyBuffer& str, KeyBuffer& hex);
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/* Normalize given hex string into consistent format */
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status_t NormalizeHex(const std::string& in, std::string& out);
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uint64_t GetFreeBytes(const std::string& path);
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uint64_t GetTreeBytes(const std::string& path);
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bool IsFilesystemSupported(const std::string& fsType);
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bool IsSdcardfsUsed();
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bool IsFuseDaemon(const pid_t pid);
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/* Wipes contents of block device at given path */
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status_t WipeBlockDevice(const std::string& path);
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std::string BuildKeyPath(const std::string& partGuid);
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std::string BuildDataSystemLegacyPath(userid_t userid);
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std::string BuildDataSystemCePath(userid_t userid);
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std::string BuildDataSystemDePath(userid_t userid);
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std::string BuildDataMiscLegacyPath(userid_t userid);
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std::string BuildDataMiscCePath(userid_t userid);
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std::string BuildDataMiscDePath(userid_t userid);
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std::string BuildDataProfilesDePath(userid_t userid);
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std::string BuildDataVendorCePath(userid_t userid);
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std::string BuildDataVendorDePath(userid_t userid);
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std::string BuildDataPath(const std::string& volumeUuid);
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std::string BuildDataMediaCePath(const std::string& volumeUuid, userid_t userid);
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std::string BuildDataUserCePath(const std::string& volumeUuid, userid_t userid);
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std::string BuildDataUserDePath(const std::string& volumeUuid, userid_t userid);
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dev_t GetDevice(const std::string& path);
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bool IsSameFile(const std::string& path1, const std::string& path2);
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status_t EnsureDirExists(const std::string& path, mode_t mode, uid_t uid, gid_t gid);
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status_t RestoreconRecursive(const std::string& path);
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// TODO: promote to android::base
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bool Readlinkat(int dirfd, const std::string& path, std::string* result);
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// Handles dynamic major assignment for virtio-block
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bool IsVirtioBlkDevice(unsigned int major);
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status_t UnmountTreeWithPrefix(const std::string& prefix);
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status_t UnmountTree(const std::string& mountPoint);
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bool IsDotOrDotDot(const struct dirent& ent);
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status_t DeleteDirContentsAndDir(const std::string& pathname);
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status_t DeleteDirContents(const std::string& pathname);
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status_t WaitForFile(const char* filename, std::chrono::nanoseconds timeout);
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bool pathExists(const std::string& path);
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bool FsyncDirectory(const std::string& dirname);
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bool FsyncParentDirectory(const std::string& path);
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bool MkdirsSync(const std::string& path, mode_t mode);
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bool writeStringToFile(const std::string& payload, const std::string& filename);
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void ConfigureMaxDirtyRatioForFuse(const std::string& fuse_mount, unsigned int max_ratio);
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void ConfigureReadAheadForFuse(const std::string& fuse_mount, size_t read_ahead_kb);
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status_t MountUserFuse(userid_t user_id, const std::string& absolute_lower_path,
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const std::string& relative_upper_path, android::base::unique_fd* fuse_fd);
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status_t UnmountUserFuse(userid_t userId, const std::string& absolute_lower_path,
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const std::string& relative_upper_path);
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status_t PrepareAndroidDirs(const std::string& volumeRoot);
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// Open a given directory as an FD, and return that and the corresponding procfs virtual
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// symlink path that can be used in any API that accepts a path string. Path stays valid until
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// the directory FD is closed.
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//
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// This may be useful when an API wants to restrict a path passed from an untrusted process,
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// and do it without any TOCTOU attacks possible (e.g. where an attacker replaces one of
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// the components with a symlink after the check passed). In that case opening a path through
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// this function guarantees that the target directory stays the same, and that it can be
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// referenced inside the current process via the virtual procfs symlink returned here.
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std::pair<android::base::unique_fd, std::string> OpenDirInProcfs(std::string_view path);
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} // namespace vold
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} // namespace android
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#endif
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