mirror of
https://github.com/google/sandboxed-api.git
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317 lines
10 KiB
C++
317 lines
10 KiB
C++
// Copyright 2019 Google LLC
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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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// https://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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#include "sandboxed_api/sandbox2/policy.h"
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#include <syscall.h>
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#include <cerrno>
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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 "gmock/gmock.h"
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#include "gtest/gtest.h"
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#include "absl/strings/string_view.h"
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#include "sandboxed_api/config.h"
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#include "sandboxed_api/sandbox2/executor.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/bpf_helper.h"
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#include "sandboxed_api/testing.h"
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#include "sandboxed_api/util/status_matchers.h"
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namespace sandbox2 {
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namespace {
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using ::sapi::CreateDefaultPermissiveTestPolicy;
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using ::sapi::GetTestSourcePath;
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using ::testing::Eq;
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#ifdef SAPI_X86_64
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// Test that 32-bit syscalls from 64-bit are disallowed.
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TEST(PolicyTest, AMD64Syscall32PolicyAllowed) {
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SKIP_ANDROID;
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "1"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy,
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CreateDefaultPermissiveTestPolicy(path).TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
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EXPECT_THAT(result.reason_code(), Eq(1)); // __NR_exit in 32-bit
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EXPECT_THAT(result.GetSyscallArch(), Eq(sapi::cpu::kX86));
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}
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// Test that 32-bit syscalls from 64-bit for FS checks are disallowed.
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TEST(PolicyTest, AMD64Syscall32FsAllowed) {
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SKIP_ANDROID;
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "2"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy,
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CreateDefaultPermissiveTestPolicy(path).TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
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EXPECT_THAT(result.reason_code(),
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Eq(33)); // __NR_access in 32-bit
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EXPECT_THAT(result.GetSyscallArch(), Eq(sapi::cpu::kX86));
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}
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#endif
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// Test that ptrace(2) is disallowed.
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TEST(PolicyTest, PtraceDisallowed) {
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "3"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy,
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CreateDefaultPermissiveTestPolicy(path).TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
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EXPECT_THAT(result.reason_code(), Eq(__NR_ptrace));
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}
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TEST(PolicyTest, PtraceBlocked) {
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "8"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy,
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CreateDefaultPermissiveTestPolicy(path)
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.BlockSyscallWithErrno(__NR_ptrace, EPERM)
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.TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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// The policy binary fails with an error if the system call is *not* blocked.
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ASSERT_THAT(result.final_status(), Eq(Result::OK));
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}
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// Test that clone(2) with flag CLONE_UNTRACED is disallowed.
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TEST(PolicyTest, CloneUntracedDisallowed) {
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "4"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy,
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CreateDefaultPermissiveTestPolicy(path).TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
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EXPECT_THAT(result.reason_code(), Eq(__NR_clone));
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}
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// Test that bpf(2) is disallowed.
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TEST(PolicyTest, BpfDisallowed) {
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "5"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy,
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CreateDefaultPermissiveTestPolicy(path).TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
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EXPECT_THAT(result.reason_code(), Eq(__NR_bpf));
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}
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// Test that bpf(2) can return EPERM.
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TEST(PolicyTest, BpfPermissionDenied) {
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "7"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy,
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CreateDefaultPermissiveTestPolicy(path)
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.BlockSyscallWithErrno(__NR_bpf, EPERM)
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.TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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// bpf(2) is not a violation due to explicit policy. EPERM is expected.
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ASSERT_THAT(result.final_status(), Eq(Result::OK));
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EXPECT_THAT(result.reason_code(), Eq(EPERM));
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}
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TEST(PolicyTest, IsattyAllowed) {
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SKIP_SANITIZERS_AND_COVERAGE;
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sandbox2::PolicyBuilder builder;
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if constexpr (sapi::host_os::IsAndroid()) {
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builder.DisableNamespaces().AllowDynamicStartup();
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}
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builder.AllowStaticStartup()
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.AllowExit()
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.AllowRead()
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.AllowWrite()
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.AllowTCGETS();
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const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
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std::vector<std::string> args = {path, "6"};
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SAPI_ASSERT_OK_AND_ASSIGN(auto policy, builder.TryBuild());
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::OK));
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}
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std::unique_ptr<Policy> MinimalTestcasePolicy() {
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sandbox2::PolicyBuilder builder;
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if constexpr (sapi::host_os::IsAndroid()) {
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builder.AllowDynamicStartup();
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builder.DisableNamespaces();
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}
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builder.AllowStaticStartup().AllowExit();
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return builder.BuildOrDie();
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}
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// Test that we can sandbox a minimal static binary returning 0.
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// If this starts failing, it means something changed, maybe in the way we
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// compile static binaries, and we need to update the policy just above.
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TEST(MinimalTest, MinimalBinaryWorks) {
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SKIP_ANDROID;
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SKIP_SANITIZERS_AND_COVERAGE;
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const std::string path = GetTestSourcePath("sandbox2/testcases/minimal");
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std::vector<std::string> args = {path};
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Sandbox2 s2(std::make_unique<Executor>(path, args), MinimalTestcasePolicy());
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::OK));
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EXPECT_THAT(result.reason_code(), Eq(EXIT_SUCCESS));
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}
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// Test that we can sandbox a minimal non-static binary returning 0.
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TEST(MinimalTest, MinimalSharedBinaryWorks) {
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SKIP_SANITIZERS_AND_COVERAGE;
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const std::string path =
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GetTestSourcePath("sandbox2/testcases/minimal_dynamic");
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std::vector<std::string> args = {path};
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sandbox2::PolicyBuilder builder;
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if constexpr (sapi::host_os::IsAndroid()) {
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builder.DisableNamespaces();
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} else {
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builder.AddLibrariesForBinary(path);
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}
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builder.AllowDynamicStartup().AllowExit();
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auto policy = builder.BuildOrDie();
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::OK));
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EXPECT_THAT(result.reason_code(), Eq(EXIT_SUCCESS));
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}
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// Test that the AllowSystemMalloc helper works as expected.
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TEST(MallocTest, SystemMallocWorks) {
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SKIP_SANITIZERS_AND_COVERAGE;
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const std::string path =
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GetTestSourcePath("sandbox2/testcases/malloc_system");
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std::vector<std::string> args = {path};
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sandbox2::PolicyBuilder builder;
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if constexpr (sapi::host_os::IsAndroid()) {
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builder.DisableNamespaces();
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builder.AllowDynamicStartup();
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builder.AllowSyscalls({
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__NR_madvise,
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});
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}
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builder.AllowStaticStartup().AllowSystemMalloc().AllowExit();
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auto policy = builder.BuildOrDie();
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::OK));
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EXPECT_THAT(result.reason_code(), Eq(EXIT_SUCCESS));
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}
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// Complicated test to see that AddPolicyOnSyscalls work as
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// expected. Specifically a worrisome corner-case would be that the logic was
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// almost correct, but that the jump targets were off slightly. This uses the
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// AddPolicyOnSyscall multiple times in a row to make any miscalculation
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// unlikely to pass this check.
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TEST(MultipleSyscalls, AddPolicyOnSyscallsWorks) {
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SKIP_SANITIZERS_AND_COVERAGE;
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const std::string path =
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GetTestSourcePath("sandbox2/testcases/add_policy_on_syscalls");
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std::vector<std::string> args = {path};
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sandbox2::PolicyBuilder builder;
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if constexpr (sapi::host_os::IsAndroid()) {
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builder.DisableNamespaces();
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builder.AllowDynamicStartup();
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}
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builder.AllowStaticStartup()
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.AllowTcMalloc()
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.AllowExit()
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.AddPolicyOnSyscalls(
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{
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__NR_getuid,
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__NR_getgid,
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__NR_geteuid,
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__NR_getegid,
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#ifdef __NR_getuid32
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__NR_getuid32,
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#endif
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#ifdef __NR_getgid32
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__NR_getgid32,
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#endif
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#ifdef __NR_geteuid32
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__NR_geteuid32,
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#endif
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#ifdef __NR_getegid32
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__NR_getegid32,
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#endif
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},
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{ALLOW})
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.AddPolicyOnSyscalls(
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{
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__NR_getresuid,
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__NR_getresgid,
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#ifdef __NR_getresuid32
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__NR_getresuid32,
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#endif
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#ifdef __NR_getresgid32
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__NR_getresgid32,
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#endif
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},
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{ERRNO(42)})
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.AddPolicyOnSyscalls({__NR_read, __NR_write}, {ERRNO(43)})
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.AddPolicyOnSyscall(__NR_umask, {DENY});
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auto policy = builder.BuildOrDie();
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Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
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auto result = s2.Run();
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ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
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EXPECT_THAT(result.reason_code(), Eq(__NR_umask));
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}
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} // namespace
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} // namespace sandbox2
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