sandboxed-api/sandboxed_api/sandbox2/examples/crc4/crc4sandbox.cc
Christian Blichmann 9b78e331fa Use newer gflags namespace for command-line flags
PiperOrigin-RevId: 251639941
Change-Id: I3037ce9510a3bc62cf5c899c64f2e7d344a8b4ee
2019-06-05 07:39:38 -07:00

156 lines
4.9 KiB
C++

// Copyright 2019 Google LLC. All Rights Reserved.
//
// 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.
// A demo sandbox for the crc4bin binary
#include <linux/filter.h>
#include <sys/resource.h>
#include <syscall.h>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include <glog/logging.h>
#include "sandboxed_api/util/flag.h"
#include "absl/memory/memory.h"
#include "sandboxed_api/sandbox2/comms.h"
#include "sandboxed_api/sandbox2/executor.h"
#include "sandboxed_api/sandbox2/ipc.h"
#include "sandboxed_api/sandbox2/limits.h"
#include "sandboxed_api/sandbox2/policy.h"
#include "sandboxed_api/sandbox2/policybuilder.h"
#include "sandboxed_api/sandbox2/result.h"
#include "sandboxed_api/sandbox2/sandbox2.h"
#include "sandboxed_api/sandbox2/util/bpf_helper.h"
#include "sandboxed_api/sandbox2/util/runfiles.h"
ABSL_FLAG(string, input, "", "Input to calculate CRC4 of.");
ABSL_FLAG(bool, call_syscall_not_allowed, false,
"Have sandboxee call clone (violation).");
namespace {
std::unique_ptr<sandbox2::Policy> GetPolicy() {
return sandbox2::PolicyBuilder()
.DisableNamespaces()
.AllowExit()
.AddPolicyOnSyscalls(
{__NR_read, __NR_write, __NR_close},
{ARG_32(0), JEQ32(sandbox2::Comms::kSandbox2ClientCommsFD, ALLOW)})
#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
defined(THREAD_SANITIZER)
.AllowSyscall(__NR_mmap)
#endif
.BuildOrDie();
}
bool SandboxedCRC4(sandbox2::Comms* comms, uint32_t* crc4) {
std::string input(absl::GetFlag(FLAGS_input));
const uint8_t* buf = reinterpret_cast<const uint8_t*>(input.data());
size_t buf_size = input.size();
if (!comms->SendBytes(buf, buf_size)) {
LOG(ERROR) << "sandboxee_comms->SendBytes() failed";
return false;
}
if (!comms->RecvUint32(crc4)) {
LOG(ERROR) << "sandboxee_comms->RecvUint32(&crc4) failed";
return false;
}
return true;
}
} // namespace
int main(int argc, char** argv) {
gflags::ParseCommandLineFlags(&argc, &argv, true);
google::InitGoogleLogging(argv[0]);
if (absl::GetFlag(FLAGS_input).empty()) {
LOG(ERROR) << "Parameter --input required.";
return 1;
}
std::string path = sandbox2::GetInternalDataDependencyFilePath(
"sandbox2/examples/crc4/crc4bin");
std::vector<std::string> args = {path};
if (absl::GetFlag(FLAGS_call_syscall_not_allowed)) {
args.push_back("-call_syscall_not_allowed");
}
std::vector<std::string> envs = {};
auto executor = absl::make_unique<sandbox2::Executor>(path, args, envs);
executor
// Sandboxing is enabled by the binary itself (i.e. the crc4bin is capable
// of enabling sandboxing on its own).
->set_enable_sandbox_before_exec(false)
.limits()
// Remove restrictions on the size of address-space of sandboxed
// processes.
->set_rlimit_as(RLIM64_INFINITY)
// Kill sandboxed processes with a signal (SIGXFSZ) if it writes more than
// these many bytes to the file-system.
.set_rlimit_fsize(1024)
.set_rlimit_cpu(60) // The CPU time limit in seconds.
.set_walltime_limit(absl::Seconds(5));
auto* comms = executor->ipc()->comms();
auto policy = GetPolicy();
sandbox2::Sandbox2 s2(std::move(executor), std::move(policy));
// Let the sandboxee run.
if (!s2.RunAsync()) {
auto result = s2.AwaitResult();
LOG(ERROR) << "RunAsync failed: " << result.ToString();
return 2;
}
uint32_t crc4;
if (!SandboxedCRC4(comms, &crc4)) {
LOG(ERROR) << "GetCRC4 failed";
if (!s2.IsTerminated()) {
// Kill the sandboxee, because failure to receive the data over the Comms
// channel doesn't automatically mean that the sandboxee itself had
// already finished. The final reason will not be overwritten, so if
// sandboxee finished because of e.g. timeout, the TIMEOUT reason will be
// reported.
LOG(INFO) << "Killing sandboxee";
s2.Kill();
}
}
auto result = s2.AwaitResult();
if (result.final_status() != sandbox2::Result::OK) {
LOG(ERROR) << "Sandbox error: " << result.ToString();
return 3; // e.g. sandbox violation, signal (sigsegv)
}
auto code = result.reason_code();
if (code) {
LOG(ERROR) << "Sandboxee exited with non-zero: " << code;
return 4; // e.g. normal child error
}
LOG(INFO) << "Sandboxee finished: " << result.ToString();
printf("0x%08x\n", crc4);
return EXIT_SUCCESS;
}