140 lines
4.6 KiB
C++
140 lines
4.6 KiB
C++
// Copyright 2019 Google LLC. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// A demo sandbox for the custom_fork_bin binary.
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// Use: custom_fork_sandbox --logtostderr
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#include <syscall.h>
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#include <cstdlib>
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#include <memory>
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#include <string>
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#include <utility>
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#include <vector>
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#include <glog/logging.h>
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#include "absl/flags/flag.h"
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#include "absl/memory/memory.h"
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#include "sandboxed_api/sandbox2/comms.h"
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#include "sandboxed_api/sandbox2/executor.h"
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#include "sandboxed_api/sandbox2/forkserver.h"
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#include "sandboxed_api/sandbox2/ipc.h"
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#include "sandboxed_api/sandbox2/limits.h"
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#include "sandboxed_api/sandbox2/policy.h"
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#include "sandboxed_api/sandbox2/policybuilder.h"
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#include "sandboxed_api/sandbox2/result.h"
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#include "sandboxed_api/sandbox2/sandbox2.h"
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#include "sandboxed_api/sandbox2/util/runfiles.h"
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std::unique_ptr<sandbox2::Policy> GetPolicy() {
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return sandbox2::PolicyBuilder()
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// The most frequent syscall should go first in this sequence (to make it
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// fast).
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.AllowRead()
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.AllowWrite()
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.AllowExit()
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.AllowTime()
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.AllowSyscalls({
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__NR_close, __NR_getpid,
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#if defined(__NR_arch_prctl)
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// Not defined with every CPU architecture in Prod.
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__NR_arch_prctl,
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#endif // defined(__NR_arch_prctl)
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})
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#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
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defined(THREAD_SANITIZER)
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.AllowMmap()
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#endif
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.EnableNamespaces()
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.BuildOrDie();
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}
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static int SandboxIteration(sandbox2::ForkClient* fork_client, int32_t i) {
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// Now, start the sandboxee as usual, just use a different Executor
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// constructor, which takes pointer to the ForkClient.
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auto executor = absl::make_unique<sandbox2::Executor>(fork_client);
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// Set limits as usual.
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executor
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->limits()
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// Remove restrictions on the size of address-space of sandboxed
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// processes. Here, it's 1GiB.
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->set_rlimit_as(
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#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
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defined(THREAD_SANITIZER)
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RLIM64_INFINITY
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#else
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1ULL << 30 // 1GiB
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#endif
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)
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// Kill sandboxed processes with a signal (SIGXFSZ) if it writes more than
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// these many bytes to the file-system (including logs in prod, which
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// write to files STDOUT and STDERR).
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.set_rlimit_fsize(1024 /* bytes */)
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// The CPU time limit.
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.set_rlimit_cpu(10 /* CPU-seconds */)
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.set_walltime_limit(absl::Seconds(5));
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auto* comms = executor->ipc()->comms();
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auto policy = GetPolicy();
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sandbox2::Sandbox2 s2(std::move(executor), std::move(policy));
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// Let the sandboxee run (asynchronously).
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CHECK(s2.RunAsync());
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// Send integer, which will be returned as the sandboxee's exit code.
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CHECK(comms->SendInt32(i));
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auto result = s2.AwaitResult();
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LOG(INFO) << "Final execution status of PID " << s2.GetPid() << ": "
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<< result.ToString();
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if (result.final_status() != sandbox2::Result::OK) {
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return -1;
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}
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return result.reason_code();
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}
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int main(int argc, char** argv) {
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google::ParseCommandLineFlags(&argc, &argv, true);
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google::InitGoogleLogging(argv[0]);
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// Start a custom fork-server (via sandbox2::Executor).
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const std::string path = sandbox2::GetInternalDataDependencyFilePath(
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"sandbox2/examples/custom_fork/custom_fork_bin");
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std::vector<std::string> args = {path};
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std::vector<std::string> envs = {};
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auto fork_executor = absl::make_unique<sandbox2::Executor>(path, args, envs);
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// Start the fork-server (which is here: the custom_fork_bin process calling
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// sandbox2::Client::WaitAndFork() in a loop).
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//
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// This function returns immediately, returning std::unique_ptr<ForkClient>.
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//
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// If it's holding the nullptr, then this call had failed.
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auto fork_client = fork_executor->StartForkServer();
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if (!fork_client) {
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LOG(ERROR) << "Starting custom ForkServer failed";
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return EXIT_FAILURE;
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}
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LOG(INFO) << "Custom Fork-Server started";
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// Test new sandboxees: send them integers over Comms, and expect they will
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// exit with these specific exit codes.
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for (int i = 0; i < 10; i++) {
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CHECK_EQ(SandboxIteration(fork_client.get(), i), i);
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}
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return EXIT_SUCCESS;
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}
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