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/*
* Copyright (C) 2016 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 "fscrypt/fscrypt_init_extensions.h"
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <cutils/properties.h>
#include <cutils/sockets.h>
#include <dirent.h>
#include <errno.h>
#include <fts.h>
#include <keyutils.h>
#include <logwrap/logwrap.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string>
#include <vector>
#include "fscrypt/fscrypt.h"
#define TAG "fscrypt"
static int set_system_de_policy_on(char const* dir);
int fscrypt_install_keyring()
{
key_serial_t device_keyring = add_key("keyring", "fscrypt", 0, 0,
KEY_SPEC_SESSION_KEYRING);
if (device_keyring == -1) {
PLOG(ERROR) << "Failed to create keyring";
return -1;
}
LOG(INFO) << "Keyring created with id " << device_keyring << " in process " << getpid();
return 0;
}
// TODO(b/139378601): use a single central implementation of this.
static void delete_dir_contents(const char* dir) {
char* const paths[2] = {const_cast<char*>(dir), nullptr};
FTS* fts = fts_open(paths, FTS_PHYSICAL | FTS_NOCHDIR | FTS_XDEV, nullptr);
FTSENT* cur;
while ((cur = fts_read(fts)) != nullptr) {
if (cur->fts_info == FTS_ERR) {
PLOG(ERROR) << "fts_read";
break;
}
if (strcmp(dir, cur->fts_path) == 0) {
continue;
}
switch (cur->fts_info) {
case FTS_D:
break; // Ignore these
case FTS_DP:
if (rmdir(cur->fts_path) == -1) {
PLOG(ERROR) << "rmdir " << cur->fts_path;
}
break;
default:
PLOG(ERROR) << "FTS unexpected type " << cur->fts_info << " at " << cur->fts_path;
if (rmdir(cur->fts_path) != -1) break;
// FALLTHRU (for gcc, lint, pcc, etc; and following for clang)
FALLTHROUGH_INTENDED;
case FTS_F:
case FTS_SL:
case FTS_SLNONE:
if (unlink(cur->fts_path) == -1) {
PLOG(ERROR) << "unlink " << cur->fts_path;
}
break;
}
}
if (fts_close(fts) != 0) {
PLOG(ERROR) << "fts_close";
}
}
int fscrypt_set_directory_policy(const char* dir)
{
const std::string prefix = "/data/";
if (!dir || strncmp(dir, prefix.c_str(), prefix.size())) {
return 0;
}
// Special-case /data/media/obb per b/64566063
if (strcmp(dir, "/data/media/obb") == 0) {
// Try to set policy on this directory, but if it is non-empty this may fail.
set_system_de_policy_on(dir);
return 0;
}
// Only set policy on first level /data directories
// To make this less restrictive, consider using a policy file.
// However this is overkill for as long as the policy is simply
// to apply a global policy to all /data folders created via makedir
if (strchr(dir + prefix.size(), '/')) {
return 0;
}
// Special case various directories that must not be encrypted,
// often because their subdirectories must be encrypted.
// This isn't a nice way to do this, see b/26641735
std::vector<std::string> directories_to_exclude = {
"lost+found",
"system_ce", "system_de",
"misc_ce", "misc_de",
"vendor_ce", "vendor_de",
"media",
"data", "user", "user_de",
"apex", "preloads", "app-staging",
"gsi",
};
for (const auto& d: directories_to_exclude) {
if ((prefix + d) == dir) {
LOG(INFO) << "Not setting policy on " << dir;
return 0;
}
}
int err = set_system_de_policy_on(dir);
if (err == 0) {
return 0;
}
// Empty these directories if policy setting fails.
std::vector<std::string> wipe_on_failure = {
"rollback", "rollback-observer", // b/139193659
};
for (const auto& d : wipe_on_failure) {
if ((prefix + d) == dir) {
LOG(ERROR) << "Setting policy failed, deleting: " << dir;
delete_dir_contents(dir);
err = set_system_de_policy_on(dir);
break;
}
}
return err;
}
static int set_system_de_policy_on(char const* dir) {
std::string ref_filename = std::string("/data") + fscrypt_key_ref;
std::string policy;
if (!android::base::ReadFileToString(ref_filename, &policy)) {
LOG(ERROR) << "Unable to read system policy to set on " << dir;
return -1;
}
auto type_filename = std::string("/data") + fscrypt_key_mode;
std::string modestring;
if (!android::base::ReadFileToString(type_filename, &modestring)) {
LOG(ERROR) << "Cannot read mode";
}
std::vector<std::string> modes = android::base::Split(modestring, ":");
if (modes.size() < 1 || modes.size() > 2) {
LOG(ERROR) << "Invalid encryption mode string: " << modestring;
return -1;
}
LOG(INFO) << "Setting policy on " << dir;
int result = fscrypt_policy_ensure(dir, policy.c_str(), policy.length(),
modes[0].c_str(),
modes.size() >= 2 ?
modes[1].c_str() : "aes-256-cts");
if (result) {
LOG(ERROR) << android::base::StringPrintf(
"Setting %02x%02x%02x%02x policy on %s failed!",
policy[0], policy[1], policy[2], policy[3], dir);
return -1;
}
return 0;
}
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