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/*
* Copyright (C) 2017 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.
*/
#pragma once
#include <stdlib.h>
#include <string.h>
#include <sys/capability.h>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <selinux/android.h>
uint8_t kBase64Map[256] = {
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255,
255, 254, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255,
255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255
};
uint8_t* DecodeBase64(const char* src, size_t* dst_size) {
CHECK(dst_size != nullptr);
std::vector<uint8_t> tmp;
uint32_t t = 0, y = 0;
int g = 3;
for (size_t i = 0; src[i] != '\0'; ++i) {
uint8_t c = kBase64Map[src[i] & 0xFF];
if (c == 255) continue;
// the final = symbols are read and used to trim the remaining bytes
if (c == 254) {
c = 0;
// prevent g < 0 which would potentially allow an overflow later
if (--g < 0) {
*dst_size = 0;
return nullptr;
}
} else if (g != 3) {
// we only allow = to be at the end
*dst_size = 0;
return nullptr;
}
t = (t << 6) | c;
if (++y == 4) {
tmp.push_back((t >> 16) & 255);
if (g > 1) {
tmp.push_back((t >> 8) & 255);
}
if (g > 2) {
tmp.push_back(t & 255);
}
y = t = 0;
}
}
if (y != 0) {
*dst_size = 0;
return nullptr;
}
std::unique_ptr<uint8_t[]> dst(new uint8_t[tmp.size()]);
*dst_size = tmp.size();
std::copy(tmp.begin(), tmp.end(), dst.get());
return dst.release();
}
bool WriteBase64ToFile(const char* base64, const std::string& file,
uid_t uid, gid_t gid, int mode, std::string* error_msg) {
CHECK(base64 != nullptr);
size_t length;
std::unique_ptr<uint8_t[]> bytes(DecodeBase64(base64, &length));
CHECK(bytes != nullptr);
int fd = open(file.c_str(), O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
using android::base::StringPrintf;
if (fd < 0) {
*error_msg = StringPrintf("Could not open file %s: %s", file.c_str(), strerror(errno));
return false;
}
size_t wrote = 0;
while (wrote < length) {
ssize_t cur = write(fd, bytes.get() + wrote, length - wrote);
if (cur == -1) {
*error_msg = StringPrintf("Could not write file %s: %s", file.c_str(), strerror(errno));
return false;
}
wrote += cur;
}
if (::chown(file.c_str(), uid, gid) != 0) {
*error_msg = StringPrintf("Could not chown file %s: %s", file.c_str(), strerror(errno));
return false;
}
if (::chmod(file.c_str(), mode) != 0) {
*error_msg = StringPrintf("Could not chmod file %s: %s", file.c_str(), strerror(errno));
return false;
}
return true;
}
// TODO(calin): fix dexopt drop_capabilities and move to general utils (b/69678790).
bool DropCapabilities(uid_t uid, gid_t gid) {
if (setgid(gid) != 0) {
PLOG(ERROR) << "setgid failed: " << gid;
return false;
}
if (setuid(uid) != 0) {
PLOG(ERROR) << "setuid failed: " << uid;
return false;
}
// drop capabilities
struct __user_cap_header_struct capheader;
struct __user_cap_data_struct capdata[2];
memset(&capheader, 0, sizeof(capheader));
memset(&capdata, 0, sizeof(capdata));
capheader.version = _LINUX_CAPABILITY_VERSION_3;
if (capset(&capheader, &capdata[0]) < 0) {
PLOG(ERROR) << "capset failed";
return false;
}
return true;
}
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