77 lines
2.7 KiB
C++
77 lines
2.7 KiB
C++
// Copyright 2019 Google LLC
|
|
//
|
|
// 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
|
|
//
|
|
// https://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.
|
|
|
|
// This file is an example of a binary which is intended to be sandboxed by the
|
|
// sandbox2, and which uses a built-in fork-server to spawn new sandboxees
|
|
// (instead of doing fork/execve via the Fork-Server).
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <cstdint>
|
|
|
|
#include "absl/base/log_severity.h"
|
|
#include "absl/flags/parse.h"
|
|
#include "absl/log/globals.h"
|
|
#include "absl/log/initialize.h"
|
|
#include "sandboxed_api/sandbox2/comms.h"
|
|
#include "sandboxed_api/sandbox2/forkingclient.h"
|
|
#include "sandboxed_api/util/raw_logging.h"
|
|
|
|
// Just return the value received over the Comms channel from the parent.
|
|
static int SandboxeeFunction(sandbox2::Comms* comms) {
|
|
int32_t i;
|
|
// SAPI_RAW_CHECK() uses smaller set of syscalls than regular CHECK().
|
|
SAPI_RAW_CHECK(comms->RecvInt32(&i), "Receiving an int32_t");
|
|
|
|
// Make sure that we're not the init process in the custom forkserver
|
|
// child.
|
|
SAPI_RAW_CHECK(getpid() == 2, "Unexpected PID");
|
|
return i;
|
|
}
|
|
|
|
int main(int argc, char* argv[]) {
|
|
absl::ParseCommandLine(argc, argv);
|
|
|
|
// Writing to stderr limits the number of invoked syscalls.
|
|
absl::SetStderrThreshold(absl::LogSeverityAtLeast::kInfo);
|
|
absl::InitializeLog();
|
|
|
|
// Instantiate Comms channel with the parent Executor
|
|
sandbox2::Comms comms(sandbox2::Comms::kDefaultConnection);
|
|
sandbox2::ForkingClient s2client(&comms);
|
|
|
|
for (;;) {
|
|
// Start a new process, if the sandboxer requests us to do so. No need to
|
|
// wait for the new process, as the call to sandbox2::Client::Fork will
|
|
// indirectly call sigaction(SIGCHLD, sa_flags=SA_NOCLDWAIT) in the parent.
|
|
pid_t pid = s2client.WaitAndFork();
|
|
if (pid == -1) {
|
|
SAPI_RAW_CHECK(false, "Could not spawn a new sandboxee");
|
|
}
|
|
// Child - return to the main(), to continue with code which is supposed to
|
|
// be sandboxed. From now on the comms channel (in the child) is set up over
|
|
// a new file descriptor pair, reachable from a separate Executor in the
|
|
// sandboxer.
|
|
if (pid == 0) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Start sandboxing here
|
|
s2client.SandboxMeHere();
|
|
|
|
// This section of code runs sandboxed
|
|
return SandboxeeFunction(&comms);
|
|
}
|