platform_system_core/init/descriptors.cpp
Mark Salyzyn 978fd0ea25 init: service file command only opens existing files
Mixing open or create, along with attribute(MAC) and permissions(DAC)
is a security and confusion issue.

Fix an issue where fcntl F_SETFD was called to clear O_NONBLOCK, when
it should have been F_SETFL.  Did not present a problem because the
current user of this feature does writes and control messages only.

Test: gTest logd-unit-tests and check dmesg for logd content.
Bug: 32450474
Bug: 33242020
Change-Id: I23cb9a9be5ddb7e8e9c58c79838bc07536e766e6
2016-12-05 11:26:39 -08:00

125 lines
4.1 KiB
C++

/*
* 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 "descriptors.h"
#include <ctype.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
#include <cutils/android_get_control_file.h>
#include <cutils/sockets.h>
#include "init.h"
#include "log.h"
#include "util.h"
DescriptorInfo::DescriptorInfo(const std::string& name, const std::string& type, uid_t uid,
gid_t gid, int perm, const std::string& context)
: name_(name), type_(type), uid_(uid), gid_(gid), perm_(perm), context_(context) {
}
DescriptorInfo::~DescriptorInfo() {
}
std::ostream& operator<<(std::ostream& os, const DescriptorInfo& info) {
return os << " descriptors " << info.name_ << " " << info.type_ << " " << std::oct << info.perm_;
}
bool DescriptorInfo::operator==(const DescriptorInfo& other) const {
return name_ == other.name_ && type_ == other.type_ && key() == other.key();
}
void DescriptorInfo::CreateAndPublish(const std::string& globalContext) const {
// Create
const std::string& contextStr = context_.empty() ? globalContext : context_;
int fd = Create(contextStr);
if (fd < 0) return;
// Publish
std::string publishedName = key() + name_;
std::for_each(publishedName.begin(), publishedName.end(),
[] (char& c) { c = isalnum(c) ? c : '_'; });
std::string val = android::base::StringPrintf("%d", fd);
add_environment(publishedName.c_str(), val.c_str());
// make sure we don't close on exec
fcntl(fd, F_SETFD, 0);
}
void DescriptorInfo::Clean() const {
}
SocketInfo::SocketInfo(const std::string& name, const std::string& type, uid_t uid,
gid_t gid, int perm, const std::string& context)
: DescriptorInfo(name, type, uid, gid, perm, context) {
}
void SocketInfo::Clean() const {
unlink(android::base::StringPrintf(ANDROID_SOCKET_DIR "/%s", name().c_str()).c_str());
}
int SocketInfo::Create(const std::string& context) const {
int flags = ((type() == "stream" ? SOCK_STREAM :
(type() == "dgram" ? SOCK_DGRAM :
SOCK_SEQPACKET)));
return create_socket(name().c_str(), flags, perm(), uid(), gid(), context.c_str());
}
const std::string SocketInfo::key() const {
return ANDROID_SOCKET_ENV_PREFIX;
}
FileInfo::FileInfo(const std::string& name, const std::string& type, uid_t uid,
gid_t gid, int perm, const std::string& context)
// defaults OK for uid,..., they are ignored for this class.
: DescriptorInfo(name, type, uid, gid, perm, context) {
}
int FileInfo::Create(const std::string&) const {
int flags = (type() == "r") ? O_RDONLY :
(type() == "w") ? O_WRONLY :
O_RDWR;
// Make sure we do not block on open (eg: devices can chose to block on
// carrier detect). Our intention is never to delay launch of a service
// for such a condition. The service can perform its own blocking on
// carrier detect.
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(name().c_str(),
flags | O_NONBLOCK)));
if (fd < 0) {
PLOG(ERROR) << "Failed to open file '" << name().c_str() << "'";
return -1;
}
// Fixup as we set O_NONBLOCK for open, the intent for fd is to block reads.
fcntl(fd, F_SETFL, flags);
LOG(INFO) << "Opened file '" << name().c_str() << "'"
<< ", flags " << std::oct << flags << std::dec;
return fd.release();
}
const std::string FileInfo::key() const {
return ANDROID_FILE_ENV_PREFIX;
}