sandboxed-api/sandboxed_api/sandbox2/policy_test.cc
Sandboxed API Team 5513e560eb Add option to block the ptrace system call instead of denying it.
PiperOrigin-RevId: 451347905
Change-Id: Iaed0f6f116bca3be4e6e7009dddd4dd6267823bb
2022-05-27 02:57:37 -07:00

332 lines
11 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.
#include "sandboxed_api/sandbox2/policy.h"
#include <sys/resource.h>
#include <syscall.h>
#include <cerrno>
#include <cstdlib>
#include <string>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/memory/memory.h"
#include "absl/strings/string_view.h"
#include "sandboxed_api/config.h"
#include "sandboxed_api/sandbox2/executor.h"
#include "sandboxed_api/sandbox2/limits.h"
#include "sandboxed_api/sandbox2/policybuilder.h"
#include "sandboxed_api/sandbox2/result.h"
#include "sandboxed_api/sandbox2/sandbox2.h"
#include "sandboxed_api/sandbox2/syscall.h"
#include "sandboxed_api/sandbox2/util/bpf_helper.h"
#include "sandboxed_api/testing.h"
namespace sandbox2 {
namespace {
using ::sapi::GetTestSourcePath;
using ::testing::Eq;
PolicyBuilder CreatePolicyTestPolicyBuilder() {
return PolicyBuilder()
.DisableNamespaces()
.AllowStaticStartup()
.AllowExit()
.AllowRead()
.AllowWrite()
.AllowSyscall(__NR_close)
.AllowSyscall(__NR_getppid)
.AllowTCGETS()
.BlockSyscallsWithErrno(
{
#ifdef __NR_open
__NR_open,
#endif
__NR_openat,
#ifdef __NR_access
__NR_access,
#endif
#ifdef __NR_faccessat
__NR_faccessat,
#endif
},
ENOENT)
.BlockSyscallWithErrno(__NR_prlimit64, EPERM);
}
std::unique_ptr<Policy> PolicyTestcasePolicy() {
return CreatePolicyTestPolicyBuilder().BuildOrDie();
}
#ifdef SAPI_X86_64
// Test that 32-bit syscalls from 64-bit are disallowed.
TEST(PolicyTest, AMD64Syscall32PolicyAllowed) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "1"};
Sandbox2 s2(std::make_unique<Executor>(path, args), PolicyTestcasePolicy());
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
EXPECT_THAT(result.reason_code(), Eq(1)); // __NR_exit in 32-bit
EXPECT_THAT(result.GetSyscallArch(), Eq(sapi::cpu::kX86));
}
// Test that 32-bit syscalls from 64-bit for FS checks are disallowed.
TEST(PolicyTest, AMD64Syscall32FsAllowed) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "2"};
Sandbox2 s2(std::make_unique<Executor>(path, args), PolicyTestcasePolicy());
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
EXPECT_THAT(result.reason_code(),
Eq(33)); // __NR_access in 32-bit
EXPECT_THAT(result.GetSyscallArch(), Eq(sapi::cpu::kX86));
}
#endif
// Test that ptrace(2) is disallowed.
TEST(PolicyTest, PtraceDisallowed) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "3"};
Sandbox2 s2(std::make_unique<Executor>(path, args), PolicyTestcasePolicy());
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
EXPECT_THAT(result.reason_code(), Eq(__NR_ptrace));
}
TEST(PolicyTest, PtraceBlocked) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "8"};
Sandbox2 s2(std::make_unique<Executor>(path, args),
CreatePolicyTestPolicyBuilder()
.BlockSyscallWithErrno(__NR_ptrace, EPERM)
.BuildOrDie());
auto result = s2.Run();
// The policy binary fails with an error if the system call is *not* blocked.
ASSERT_THAT(result.final_status(), Eq(Result::OK));
}
// Test that clone(2) with flag CLONE_UNTRACED is disallowed.
TEST(PolicyTest, CloneUntracedDisallowed) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "4"};
Sandbox2 s2(std::make_unique<Executor>(path, args), PolicyTestcasePolicy());
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
EXPECT_THAT(result.reason_code(), Eq(__NR_clone));
}
// Test that bpf(2) is disallowed.
TEST(PolicyTest, BpfDisallowed) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "5"};
Sandbox2 s2(std::make_unique<Executor>(path, args), PolicyTestcasePolicy());
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
EXPECT_THAT(result.reason_code(), Eq(__NR_bpf));
}
// Test that bpf(2) can return EPERM.
TEST(PolicyTest, BpfPermissionDenied) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "7"};
auto policy = CreatePolicyTestPolicyBuilder()
.BlockSyscallWithErrno(__NR_bpf, EPERM)
.BuildOrDie();
Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
auto result = s2.Run();
// bpf(2) is not a violation due to explicit policy. EPERM is expected.
ASSERT_THAT(result.final_status(), Eq(Result::OK));
EXPECT_THAT(result.reason_code(), Eq(EPERM));
}
TEST(PolicyTest, IsattyAllowed) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/policy");
std::vector<std::string> args = {path, "6"};
Sandbox2 s2(std::make_unique<Executor>(path, args), PolicyTestcasePolicy());
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::OK));
}
std::unique_ptr<Policy> MinimalTestcasePolicy() {
return PolicyBuilder()
.AllowStaticStartup()
.AllowExit()
.BlockSyscallWithErrno(__NR_prlimit64, EPERM)
#ifdef __NR_access
.BlockSyscallWithErrno(__NR_access, ENOENT)
#endif
.BuildOrDie();
}
// Test that we can sandbox a minimal static binary returning 0.
// If this starts failing, it means something changed, maybe in the way we
// compile static binaries, and we need to update the policy just above.
TEST(MinimalTest, MinimalBinaryWorks) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path = GetTestSourcePath("sandbox2/testcases/minimal");
std::vector<std::string> args = {path};
Sandbox2 s2(std::make_unique<Executor>(path, args), MinimalTestcasePolicy());
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::OK));
EXPECT_THAT(result.reason_code(), Eq(EXIT_SUCCESS));
}
// Test that we can sandbox a minimal non-static binary returning 0.
TEST(MinimalTest, MinimalSharedBinaryWorks) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path =
GetTestSourcePath("sandbox2/testcases/minimal_dynamic");
std::vector<std::string> args = {path};
auto policy = PolicyBuilder()
.AllowDynamicStartup()
.AllowOpen()
.AllowExit()
.AllowMmap()
#ifdef __NR_access
// New glibc accesses /etc/ld.so.preload
.BlockSyscallWithErrno(__NR_access, ENOENT)
#endif
.BlockSyscallWithErrno(__NR_prlimit64, EPERM)
.AddLibrariesForBinary(path)
.BuildOrDie();
Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::OK));
EXPECT_THAT(result.reason_code(), Eq(EXIT_SUCCESS));
}
// Test that the AllowSystemMalloc helper works as expected.
TEST(MallocTest, SystemMallocWorks) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path =
GetTestSourcePath("sandbox2/testcases/malloc_system");
std::vector<std::string> args = {path};
auto policy = PolicyBuilder()
.AllowStaticStartup()
.AllowSystemMalloc()
.AllowExit()
.BlockSyscallWithErrno(__NR_prlimit64, EPERM)
#ifdef __NR_access
.BlockSyscallWithErrno(__NR_access, ENOENT)
#endif
.BuildOrDie();
Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::OK));
EXPECT_THAT(result.reason_code(), Eq(EXIT_SUCCESS));
}
// Complicated test to see that AddPolicyOnSyscalls work as
// expected. Specifically a worrisome corner-case would be that the logic was
// almost correct, but that the jump targets were off slightly. This uses the
// AddPolicyOnSyscall multiple times in a row to make any miscalculation
// unlikely to pass this check.
TEST(MultipleSyscalls, AddPolicyOnSyscallsWorks) {
SKIP_SANITIZERS_AND_COVERAGE;
const std::string path =
GetTestSourcePath("sandbox2/testcases/add_policy_on_syscalls");
std::vector<std::string> args = {path};
auto policy = PolicyBuilder()
.AllowStaticStartup()
.AllowTcMalloc()
.AllowExit()
.AddPolicyOnSyscalls(
{
__NR_getuid,
__NR_getgid,
__NR_geteuid,
__NR_getegid,
#ifdef __NR_getuid32
__NR_getuid32,
#endif
#ifdef __NR_getgid32
__NR_getgid32,
#endif
#ifdef __NR_geteuid32
__NR_geteuid32,
#endif
#ifdef __NR_getegid32
__NR_getegid32,
#endif
},
{ALLOW})
.AddPolicyOnSyscalls(
{
__NR_getresuid,
__NR_getresgid,
#ifdef __NR_getresuid32
__NR_getresuid32,
#endif
#ifdef __NR_getresgid32
__NR_getresgid32,
#endif
},
{ERRNO(42)})
.AddPolicyOnSyscalls({__NR_read, __NR_write}, {ERRNO(43)})
.AddPolicyOnSyscall(__NR_umask, {DENY})
.BlockSyscallsWithErrno(
{
#ifdef __NR_open
__NR_open,
#endif
__NR_openat,
#ifdef __NR_access
__NR_access,
#endif
},
ENOENT)
.BlockSyscallWithErrno(__NR_prlimit64, EPERM)
.BuildOrDie();
Sandbox2 s2(std::make_unique<Executor>(path, args), std::move(policy));
auto result = s2.Run();
ASSERT_THAT(result.final_status(), Eq(Result::VIOLATION));
EXPECT_THAT(result.reason_code(), Eq(__NR_umask));
}
} // namespace
} // namespace sandbox2