Linux Sandbox: reorganize

sandbox/linux/bpf_dsl/bpf_dsl_more_unittest.cc

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sandbox/linux/bpf_dsl/bpf_dsl.h"
-
-#include <errno.h>
-#include <fcntl.h>
-#include <pthread.h>
-#include <sched.h>
-#include <signal.h>
-#include <sys/prctl.h>
-#include <sys/ptrace.h>
-#include <sys/syscall.h>
-#include <sys/time.h>
-#include <sys/types.h>
-#include <sys/utsname.h>
-#include <unistd.h>
-#include <sys/socket.h>
-
-#if defined(ANDROID)
-// Work-around for buggy headers in Android's NDK
-#define __user
-#endif
-#include <linux/futex.h>
-
-#include "base/bind.h"
-#include "base/logging.h"
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/posix/eintr_wrapper.h"
-#include "base/synchronization/waitable_event.h"
-#include "base/sys_info.h"
-#include "base/threading/thread.h"
-#include "build/build_config.h"
-#include "sandbox/linux/bpf_dsl/policy.h"
-#include "sandbox/linux/seccomp-bpf/bpf_tests.h"
-#include "sandbox/linux/seccomp-bpf/die.h"
-#include "sandbox/linux/seccomp-bpf/errorcode.h"
-#include "sandbox/linux/seccomp-bpf/linux_seccomp.h"
-#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
-#include "sandbox/linux/seccomp-bpf/syscall.h"
-#include "sandbox/linux/seccomp-bpf/trap.h"
-#include "sandbox/linux/services/linux_syscalls.h"
-#include "sandbox/linux/services/syscall_wrappers.h"
-#include "sandbox/linux/services/thread_helpers.h"
-#include "sandbox/linux/syscall_broker/broker_file_permission.h"
-#include "sandbox/linux/syscall_broker/broker_process.h"
-#include "sandbox/linux/tests/scoped_temporary_file.h"
-#include "sandbox/linux/tests/unit_tests.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-// Workaround for Android's prctl.h file.
-#ifndef PR_GET_ENDIAN
-#define PR_GET_ENDIAN 19
-#endif
-#ifndef PR_CAPBSET_READ
-#define PR_CAPBSET_READ 23
-#define PR_CAPBSET_DROP 24
-#endif
-
-namespace sandbox {
-namespace bpf_dsl {
-
-namespace {
-
-const int kExpectedReturnValue = 42;
-const char kSandboxDebuggingEnv[] = "CHROME_SANDBOX_DEBUGGING";
-
-// Set the global environment to allow the use of UnsafeTrap() policies.
-void EnableUnsafeTraps() {
-  // The use of UnsafeTrap() causes us to print a warning message. This is
-  // generally desirable, but it results in the unittest failing, as it doesn't
-  // expect any messages on "stderr". So, temporarily disable messages. The
-  // BPF_TEST() is guaranteed to turn messages back on, after the policy
-  // function has completed.
-  setenv(kSandboxDebuggingEnv, "t", 0);
-  Die::SuppressInfoMessages(true);
-}
-
-// BPF_TEST does a lot of the boiler-plate code around setting up a
-// policy and optional passing data between the caller, the policy and
-// any Trap() handlers. This is great for writing short and concise tests,
-// and it helps us accidentally forgetting any of the crucial steps in
-// setting up the sandbox. But it wouldn't hurt to have at least one test
-// that explicitly walks through all these steps.
-
-intptr_t IncreaseCounter(const struct arch_seccomp_data& args, void* aux) {
-  BPF_ASSERT(aux);
-  int* counter = static_cast<int*>(aux);
-  return (*counter)++;
-}
-
-class VerboseAPITestingPolicy : public Policy {
- public:
-  explicit VerboseAPITestingPolicy(int* counter_ptr)
-      : counter_ptr_(counter_ptr) {}
-  ~VerboseAPITestingPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    if (sysno == __NR_uname) {
-      return Trap(IncreaseCounter, counter_ptr_);
-    }
-    return Allow();
-  }
-
- private:
-  int* counter_ptr_;
-
-  DISALLOW_COPY_AND_ASSIGN(VerboseAPITestingPolicy);
-};
-
-SANDBOX_TEST(SandboxBPF, DISABLE_ON_TSAN(VerboseAPITesting)) {
-  if (SandboxBPF::SupportsSeccompSandbox(
-          SandboxBPF::SeccompLevel::SINGLE_THREADED)) {
-    static int counter = 0;
-
-    SandboxBPF sandbox(new VerboseAPITestingPolicy(&counter));
-    BPF_ASSERT(sandbox.StartSandbox(SandboxBPF::SeccompLevel::SINGLE_THREADED));
-
-    BPF_ASSERT_EQ(0, counter);
-    BPF_ASSERT_EQ(0, syscall(__NR_uname, 0));
-    BPF_ASSERT_EQ(1, counter);
-    BPF_ASSERT_EQ(1, syscall(__NR_uname, 0));
-    BPF_ASSERT_EQ(2, counter);
-  }
-}
-
-// A simple blacklist test
-
-class BlacklistNanosleepPolicy : public Policy {
- public:
-  BlacklistNanosleepPolicy() {}
-  ~BlacklistNanosleepPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    switch (sysno) {
-      case __NR_nanosleep:
-        return Error(EACCES);
-      default:
-        return Allow();
-    }
-  }
-
-  static void AssertNanosleepFails() {
-    const struct timespec ts = {0, 0};
-    errno = 0;
-    BPF_ASSERT_EQ(-1, HANDLE_EINTR(syscall(__NR_nanosleep, &ts, NULL)));
-    BPF_ASSERT_EQ(EACCES, errno);
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(BlacklistNanosleepPolicy);
-};
-
-BPF_TEST_C(SandboxBPF, ApplyBasicBlacklistPolicy, BlacklistNanosleepPolicy) {
-  BlacklistNanosleepPolicy::AssertNanosleepFails();
-}
-
-BPF_TEST_C(SandboxBPF, UseVsyscall, BlacklistNanosleepPolicy) {
-  time_t current_time;
-  // time() is implemented as a vsyscall. With an older glibc, with
-  // vsyscall=emulate and some versions of the seccomp BPF patch
-  // we may get SIGKILL-ed. Detect this!
-  BPF_ASSERT_NE(static_cast<time_t>(-1), time(&current_time));
-}
-
-// Now do a simple whitelist test
-
-class WhitelistGetpidPolicy : public Policy {
- public:
-  WhitelistGetpidPolicy() {}
-  ~WhitelistGetpidPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    switch (sysno) {
-      case __NR_getpid:
-      case __NR_exit_group:
-        return Allow();
-      default:
-        return Error(ENOMEM);
-    }
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(WhitelistGetpidPolicy);
-};
-
-BPF_TEST_C(SandboxBPF, ApplyBasicWhitelistPolicy, WhitelistGetpidPolicy) {
-  // getpid() should be allowed
-  errno = 0;
-  BPF_ASSERT(sys_getpid() > 0);
-  BPF_ASSERT(errno == 0);
-
-  // getpgid() should be denied
-  BPF_ASSERT(getpgid(0) == -1);
-  BPF_ASSERT(errno == ENOMEM);
-}
-
-// A simple blacklist policy, with a SIGSYS handler
-intptr_t EnomemHandler(const struct arch_seccomp_data& args, void* aux) {
-  // We also check that the auxiliary data is correct
-  SANDBOX_ASSERT(aux);
-  *(static_cast<int*>(aux)) = kExpectedReturnValue;
-  return -ENOMEM;
-}
-
-class BlacklistNanosleepTrapPolicy : public Policy {
- public:
-  explicit BlacklistNanosleepTrapPolicy(int* aux) : aux_(aux) {}
-  ~BlacklistNanosleepTrapPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    switch (sysno) {
-      case __NR_nanosleep:
-        return Trap(EnomemHandler, aux_);
-      default:
-        return Allow();
-    }
-  }
-
- private:
-  int* aux_;
-
-  DISALLOW_COPY_AND_ASSIGN(BlacklistNanosleepTrapPolicy);
-};
-
-BPF_TEST(SandboxBPF,
-         BasicBlacklistWithSigsys,
-         BlacklistNanosleepTrapPolicy,
-         int /* (*BPF_AUX) */) {
-  // getpid() should work properly
-  errno = 0;
-  BPF_ASSERT(sys_getpid() > 0);
-  BPF_ASSERT(errno == 0);
-
-  // Our Auxiliary Data, should be reset by the signal handler
-  *BPF_AUX = -1;
-  const struct timespec ts = {0, 0};
-  BPF_ASSERT(syscall(__NR_nanosleep, &ts, NULL) == -1);
-  BPF_ASSERT(errno == ENOMEM);
-
-  // We expect the signal handler to modify AuxData
-  BPF_ASSERT(*BPF_AUX == kExpectedReturnValue);
-}
-
-// A simple test that verifies we can return arbitrary errno values.
-
-class ErrnoTestPolicy : public Policy {
- public:
-  ErrnoTestPolicy() {}
-  ~ErrnoTestPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(ErrnoTestPolicy);
-};
-
-ResultExpr ErrnoTestPolicy::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-  switch (sysno) {
-    case __NR_dup3:  // dup2 is a wrapper of dup3 in android
-#if defined(__NR_dup2)
-    case __NR_dup2:
-#endif
-      // Pretend that dup2() worked, but don't actually do anything.
-      return Error(0);
-    case __NR_setuid:
-#if defined(__NR_setuid32)
-    case __NR_setuid32:
-#endif
-      // Return errno = 1.
-      return Error(1);
-    case __NR_setgid:
-#if defined(__NR_setgid32)
-    case __NR_setgid32:
-#endif
-      // Return maximum errno value (typically 4095).
-      return Error(ErrorCode::ERR_MAX_ERRNO);
-    case __NR_uname:
-      // Return errno = 42;
-      return Error(42);
-    default:
-      return Allow();
-  }
-}
-
-BPF_TEST_C(SandboxBPF, ErrnoTest, ErrnoTestPolicy) {
-  // Verify that dup2() returns success, but doesn't actually run.
-  int fds[4];
-  BPF_ASSERT(pipe(fds) == 0);
-  BPF_ASSERT(pipe(fds + 2) == 0);
-  BPF_ASSERT(dup2(fds[2], fds[0]) == 0);
-  char buf[1] = {};
-  BPF_ASSERT(write(fds[1], "\x55", 1) == 1);
-  BPF_ASSERT(write(fds[3], "\xAA", 1) == 1);
-  BPF_ASSERT(read(fds[0], buf, 1) == 1);
-
-  // If dup2() executed, we will read \xAA, but it dup2() has been turned
-  // into a no-op by our policy, then we will read \x55.
-  BPF_ASSERT(buf[0] == '\x55');
-
-  // Verify that we can return the minimum and maximum errno values.
-  errno = 0;
-  BPF_ASSERT(setuid(0) == -1);
-  BPF_ASSERT(errno == 1);
-
-  // On Android, errno is only supported up to 255, otherwise errno
-  // processing is skipped.
-  // We work around this (crbug.com/181647).
-  if (sandbox::IsAndroid() && setgid(0) != -1) {
-    errno = 0;
-    BPF_ASSERT(setgid(0) == -ErrorCode::ERR_MAX_ERRNO);
-    BPF_ASSERT(errno == 0);
-  } else {
-    errno = 0;
-    BPF_ASSERT(setgid(0) == -1);
-    BPF_ASSERT(errno == ErrorCode::ERR_MAX_ERRNO);
-  }
-
-  // Finally, test an errno in between the minimum and maximum.
-  errno = 0;
-  struct utsname uts_buf;
-  BPF_ASSERT(uname(&uts_buf) == -1);
-  BPF_ASSERT(errno == 42);
-}
-
-// Testing the stacking of two sandboxes
-
-class StackingPolicyPartOne : public Policy {
- public:
-  StackingPolicyPartOne() {}
-  ~StackingPolicyPartOne() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    switch (sysno) {
-      case __NR_getppid: {
-        const Arg<int> arg(0);
-        return If(arg == 0, Allow()).Else(Error(EPERM));
-      }
-      default:
-        return Allow();
-    }
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(StackingPolicyPartOne);
-};
-
-class StackingPolicyPartTwo : public Policy {
- public:
-  StackingPolicyPartTwo() {}
-  ~StackingPolicyPartTwo() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    switch (sysno) {
-      case __NR_getppid: {
-        const Arg<int> arg(0);
-        return If(arg == 0, Error(EINVAL)).Else(Allow());
-      }
-      default:
-        return Allow();
-    }
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(StackingPolicyPartTwo);
-};
-
-BPF_TEST_C(SandboxBPF, StackingPolicy, StackingPolicyPartOne) {
-  errno = 0;
-  BPF_ASSERT(syscall(__NR_getppid, 0) > 0);
-  BPF_ASSERT(errno == 0);
-
-  BPF_ASSERT(syscall(__NR_getppid, 1) == -1);
-  BPF_ASSERT(errno == EPERM);
-
-  // Stack a second sandbox with its own policy. Verify that we can further
-  // restrict filters, but we cannot relax existing filters.
-  SandboxBPF sandbox(new StackingPolicyPartTwo());
-  BPF_ASSERT(sandbox.StartSandbox(SandboxBPF::SeccompLevel::SINGLE_THREADED));
-
-  errno = 0;
-  BPF_ASSERT(syscall(__NR_getppid, 0) == -1);
-  BPF_ASSERT(errno == EINVAL);
-
-  BPF_ASSERT(syscall(__NR_getppid, 1) == -1);
-  BPF_ASSERT(errno == EPERM);
-}
-
-// A more complex, but synthetic policy. This tests the correctness of the BPF
-// program by iterating through all syscalls and checking for an errno that
-// depends on the syscall number. Unlike the Verifier, this exercises the BPF
-// interpreter in the kernel.
-
-// We try to make sure we exercise optimizations in the BPF compiler. We make
-// sure that the compiler can have an opportunity to coalesce syscalls with
-// contiguous numbers and we also make sure that disjoint sets can return the
-// same errno.
-int SysnoToRandomErrno(int sysno) {
-  // Small contiguous sets of 3 system calls return an errno equal to the
-  // index of that set + 1 (so that we never return a NUL errno).
-  return ((sysno & ~3) >> 2) % 29 + 1;
-}
-
-class SyntheticPolicy : public Policy {
- public:
-  SyntheticPolicy() {}
-  ~SyntheticPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    if (sysno == __NR_exit_group || sysno == __NR_write) {
-      // exit_group() is special, we really need it to work.
-      // write() is needed for BPF_ASSERT() to report a useful error message.
-      return Allow();
-    }
-    return Error(SysnoToRandomErrno(sysno));
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(SyntheticPolicy);
-};
-
-BPF_TEST_C(SandboxBPF, SyntheticPolicy, SyntheticPolicy) {
-  // Ensure that that kExpectedReturnValue + syscallnumber + 1 does not int
-  // overflow.
-  BPF_ASSERT(std::numeric_limits<int>::max() - kExpectedReturnValue - 1 >=
-             static_cast<int>(MAX_PUBLIC_SYSCALL));
-
-  for (int syscall_number = static_cast<int>(MIN_SYSCALL);
-       syscall_number <= static_cast<int>(MAX_PUBLIC_SYSCALL);
-       ++syscall_number) {
-    if (syscall_number == __NR_exit_group || syscall_number == __NR_write) {
-      // exit_group() is special
-      continue;
-    }
-    errno = 0;
-    BPF_ASSERT(syscall(syscall_number) == -1);
-    BPF_ASSERT(errno == SysnoToRandomErrno(syscall_number));
-  }
-}
-
-#if defined(__arm__)
-// A simple policy that tests whether ARM private system calls are supported
-// by our BPF compiler and by the BPF interpreter in the kernel.
-
-// For ARM private system calls, return an errno equal to their offset from
-// MIN_PRIVATE_SYSCALL plus 1 (to avoid NUL errno).
-int ArmPrivateSysnoToErrno(int sysno) {
-  if (sysno >= static_cast<int>(MIN_PRIVATE_SYSCALL) &&
-      sysno <= static_cast<int>(MAX_PRIVATE_SYSCALL)) {
-    return (sysno - MIN_PRIVATE_SYSCALL) + 1;
-  } else {
-    return ENOSYS;
-  }
-}
-
-class ArmPrivatePolicy : public Policy {
- public:
-  ArmPrivatePolicy() {}
-  ~ArmPrivatePolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    // Start from |__ARM_NR_set_tls + 1| so as not to mess with actual
-    // ARM private system calls.
-    if (sysno >= static_cast<int>(__ARM_NR_set_tls + 1) &&
-        sysno <= static_cast<int>(MAX_PRIVATE_SYSCALL)) {
-      return Error(ArmPrivateSysnoToErrno(sysno));
-    }
-    return Allow();
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(ArmPrivatePolicy);
-};
-
-BPF_TEST_C(SandboxBPF, ArmPrivatePolicy, ArmPrivatePolicy) {
-  for (int syscall_number = static_cast<int>(__ARM_NR_set_tls + 1);
-       syscall_number <= static_cast<int>(MAX_PRIVATE_SYSCALL);
-       ++syscall_number) {
-    errno = 0;
-    BPF_ASSERT(syscall(syscall_number) == -1);
-    BPF_ASSERT(errno == ArmPrivateSysnoToErrno(syscall_number));
-  }
-}
-#endif  // defined(__arm__)
-
-intptr_t CountSyscalls(const struct arch_seccomp_data& args, void* aux) {
-  // Count all invocations of our callback function.
-  ++*reinterpret_cast<int*>(aux);
-
-  // Verify that within the callback function all filtering is temporarily
-  // disabled.
-  BPF_ASSERT(sys_getpid() > 1);
-
-  // Verify that we can now call the underlying system call without causing
-  // infinite recursion.
-  return SandboxBPF::ForwardSyscall(args);
-}
-
-class GreyListedPolicy : public Policy {
- public:
-  explicit GreyListedPolicy(int* aux) : aux_(aux) {
-    // Set the global environment for unsafe traps once.
-    EnableUnsafeTraps();
-  }
-  ~GreyListedPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    // Some system calls must always be allowed, if our policy wants to make
-    // use of UnsafeTrap()
-    if (SandboxBPF::IsRequiredForUnsafeTrap(sysno)) {
-      return Allow();
-    } else if (sysno == __NR_getpid) {
-      // Disallow getpid()
-      return Error(EPERM);
-    } else {
-      // Allow (and count) all other system calls.
-      return UnsafeTrap(CountSyscalls, aux_);
-    }
-  }
-
- private:
-  int* aux_;
-
-  DISALLOW_COPY_AND_ASSIGN(GreyListedPolicy);
-};
-
-BPF_TEST(SandboxBPF, GreyListedPolicy, GreyListedPolicy, int /* (*BPF_AUX) */) {
-  BPF_ASSERT(sys_getpid() == -1);
-  BPF_ASSERT(errno == EPERM);
-  BPF_ASSERT(*BPF_AUX == 0);
-  BPF_ASSERT(syscall(__NR_geteuid) == syscall(__NR_getuid));
-  BPF_ASSERT(*BPF_AUX == 2);
-  char name[17] = {};
-  BPF_ASSERT(!syscall(__NR_prctl,
-                      PR_GET_NAME,
-                      name,
-                      (void*)NULL,
-                      (void*)NULL,
-                      (void*)NULL));
-  BPF_ASSERT(*BPF_AUX == 3);
-  BPF_ASSERT(*name);
-}
-
-SANDBOX_TEST(SandboxBPF, EnableUnsafeTrapsInSigSysHandler) {
-  // Disabling warning messages that could confuse our test framework.
-  setenv(kSandboxDebuggingEnv, "t", 0);
-  Die::SuppressInfoMessages(true);
-
-  unsetenv(kSandboxDebuggingEnv);
-  SANDBOX_ASSERT(Trap::EnableUnsafeTrapsInSigSysHandler() == false);
-  setenv(kSandboxDebuggingEnv, "", 1);
-  SANDBOX_ASSERT(Trap::EnableUnsafeTrapsInSigSysHandler() == false);
-  setenv(kSandboxDebuggingEnv, "t", 1);
-  SANDBOX_ASSERT(Trap::EnableUnsafeTrapsInSigSysHandler() == true);
-}
-
-intptr_t PrctlHandler(const struct arch_seccomp_data& args, void*) {
-  if (args.args[0] == PR_CAPBSET_DROP && static_cast<int>(args.args[1]) == -1) {
-    // prctl(PR_CAPBSET_DROP, -1) is never valid. The kernel will always
-    // return an error. But our handler allows this call.
-    return 0;
-  } else {
-    return SandboxBPF::ForwardSyscall(args);
-  }
-}
-
-class PrctlPolicy : public Policy {
- public:
-  PrctlPolicy() {}
-  ~PrctlPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    setenv(kSandboxDebuggingEnv, "t", 0);
-    Die::SuppressInfoMessages(true);
-
-    if (sysno == __NR_prctl) {
-      // Handle prctl() inside an UnsafeTrap()
-      return UnsafeTrap(PrctlHandler, NULL);
-    }
-
-    // Allow all other system calls.
-    return Allow();
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(PrctlPolicy);
-};
-
-BPF_TEST_C(SandboxBPF, ForwardSyscall, PrctlPolicy) {
-  // This call should never be allowed. But our policy will intercept it and
-  // let it pass successfully.
-  BPF_ASSERT(
-      !prctl(PR_CAPBSET_DROP, -1, (void*)NULL, (void*)NULL, (void*)NULL));
-
-  // Verify that the call will fail, if it makes it all the way to the kernel.
-  BPF_ASSERT(
-      prctl(PR_CAPBSET_DROP, -2, (void*)NULL, (void*)NULL, (void*)NULL) == -1);
-
-  // And verify that other uses of prctl() work just fine.
-  char name[17] = {};
-  BPF_ASSERT(!syscall(__NR_prctl,
-                      PR_GET_NAME,
-                      name,
-                      (void*)NULL,
-                      (void*)NULL,
-                      (void*)NULL));
-  BPF_ASSERT(*name);
-
-  // Finally, verify that system calls other than prctl() are completely
-  // unaffected by our policy.
-  struct utsname uts = {};
-  BPF_ASSERT(!uname(&uts));
-  BPF_ASSERT(!strcmp(uts.sysname, "Linux"));
-}
-
-intptr_t AllowRedirectedSyscall(const struct arch_seccomp_data& args, void*) {
-  return SandboxBPF::ForwardSyscall(args);
-}
-
-class RedirectAllSyscallsPolicy : public Policy {
- public:
-  RedirectAllSyscallsPolicy() {}
-  ~RedirectAllSyscallsPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(RedirectAllSyscallsPolicy);
-};
-
-ResultExpr RedirectAllSyscallsPolicy::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-  setenv(kSandboxDebuggingEnv, "t", 0);
-  Die::SuppressInfoMessages(true);
-
-  // Some system calls must always be allowed, if our policy wants to make
-  // use of UnsafeTrap()
-  if (SandboxBPF::IsRequiredForUnsafeTrap(sysno))
-    return Allow();
-  return UnsafeTrap(AllowRedirectedSyscall, NULL);
-}
-
-int bus_handler_fd_ = -1;
-
-void SigBusHandler(int, siginfo_t* info, void* void_context) {
-  BPF_ASSERT(write(bus_handler_fd_, "\x55", 1) == 1);
-}
-
-BPF_TEST_C(SandboxBPF, SigBus, RedirectAllSyscallsPolicy) {
-  // We use the SIGBUS bit in the signal mask as a thread-local boolean
-  // value in the implementation of UnsafeTrap(). This is obviously a bit
-  // of a hack that could conceivably interfere with code that uses SIGBUS
-  // in more traditional ways. This test verifies that basic functionality
-  // of SIGBUS is not impacted, but it is certainly possibly to construe
-  // more complex uses of signals where our use of the SIGBUS mask is not
-  // 100% transparent. This is expected behavior.
-  int fds[2];
-  BPF_ASSERT(socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0);
-  bus_handler_fd_ = fds[1];
-  struct sigaction sa = {};
-  sa.sa_sigaction = SigBusHandler;
-  sa.sa_flags = SA_SIGINFO;
-  BPF_ASSERT(sigaction(SIGBUS, &sa, NULL) == 0);
-  raise(SIGBUS);
-  char c = '\000';
-  BPF_ASSERT(read(fds[0], &c, 1) == 1);
-  BPF_ASSERT(close(fds[0]) == 0);
-  BPF_ASSERT(close(fds[1]) == 0);
-  BPF_ASSERT(c == 0x55);
-}
-
-BPF_TEST_C(SandboxBPF, SigMask, RedirectAllSyscallsPolicy) {
-  // Signal masks are potentially tricky to handle. For instance, if we
-  // ever tried to update them from inside a Trap() or UnsafeTrap() handler,
-  // the call to sigreturn() at the end of the signal handler would undo
-  // all of our efforts. So, it makes sense to test that sigprocmask()
-  // works, even if we have a policy in place that makes use of UnsafeTrap().
-  // In practice, this works because we force sigprocmask() to be handled
-  // entirely in the kernel.
-  sigset_t mask0, mask1, mask2;
-
-  // Call sigprocmask() to verify that SIGUSR2 wasn't blocked, if we didn't
-  // change the mask (it shouldn't have been, as it isn't blocked by default
-  // in POSIX).
-  //
-  // Use SIGUSR2 because Android seems to use SIGUSR1 for some purpose.
-  sigemptyset(&mask0);
-  BPF_ASSERT(!sigprocmask(SIG_BLOCK, &mask0, &mask1));
-  BPF_ASSERT(!sigismember(&mask1, SIGUSR2));
-
-  // Try again, and this time we verify that we can block it. This
-  // requires a second call to sigprocmask().
-  sigaddset(&mask0, SIGUSR2);
-  BPF_ASSERT(!sigprocmask(SIG_BLOCK, &mask0, NULL));
-  BPF_ASSERT(!sigprocmask(SIG_BLOCK, NULL, &mask2));
-  BPF_ASSERT(sigismember(&mask2, SIGUSR2));
-}
-
-BPF_TEST_C(SandboxBPF, UnsafeTrapWithErrno, RedirectAllSyscallsPolicy) {
-  // An UnsafeTrap() (or for that matter, a Trap()) has to report error
-  // conditions by returning an exit code in the range -1..-4096. This
-  // should happen automatically if using ForwardSyscall(). If the TrapFnc()
-  // uses some other method to make system calls, then it is responsible
-  // for computing the correct return code.
-  // This test verifies that ForwardSyscall() does the correct thing.
-
-  // The glibc system wrapper will ultimately set errno for us. So, from normal
-  // userspace, all of this should be completely transparent.
-  errno = 0;
-  BPF_ASSERT(close(-1) == -1);
-  BPF_ASSERT(errno == EBADF);
-
-  // Explicitly avoid the glibc wrapper. This is not normally the way anybody
-  // would make system calls, but it allows us to verify that we don't
-  // accidentally mess with errno, when we shouldn't.
-  errno = 0;
-  struct arch_seccomp_data args = {};
-  args.nr = __NR_close;
-  args.args[0] = -1;
-  BPF_ASSERT(SandboxBPF::ForwardSyscall(args) == -EBADF);
-  BPF_ASSERT(errno == 0);
-}
-
-bool NoOpCallback() {
-  return true;
-}
-
-// Test a trap handler that makes use of a broker process to open().
-
-class InitializedOpenBroker {
- public:
-  InitializedOpenBroker() : initialized_(false) {
-    std::vector<syscall_broker::BrokerFilePermission> permissions;
-    permissions.push_back(
-        syscall_broker::BrokerFilePermission::ReadOnly("/proc/allowed"));
-    permissions.push_back(
-        syscall_broker::BrokerFilePermission::ReadOnly("/proc/cpuinfo"));
-
-    broker_process_.reset(
-        new syscall_broker::BrokerProcess(EPERM, permissions));
-    BPF_ASSERT(broker_process() != NULL);
-    BPF_ASSERT(broker_process_->Init(base::Bind(&NoOpCallback)));
-
-    initialized_ = true;
-  }
-  bool initialized() { return initialized_; }
-  class syscall_broker::BrokerProcess* broker_process() {
-    return broker_process_.get();
-  }
-
- private:
-  bool initialized_;
-  scoped_ptr<class syscall_broker::BrokerProcess> broker_process_;
-  DISALLOW_COPY_AND_ASSIGN(InitializedOpenBroker);
-};
-
-intptr_t BrokerOpenTrapHandler(const struct arch_seccomp_data& args,
-                               void* aux) {
-  BPF_ASSERT(aux);
-  syscall_broker::BrokerProcess* broker_process =
-      static_cast<syscall_broker::BrokerProcess*>(aux);
-  switch (args.nr) {
-    case __NR_faccessat:  // access is a wrapper of faccessat in android
-      BPF_ASSERT(static_cast<int>(args.args[0]) == AT_FDCWD);
-      return broker_process->Access(reinterpret_cast<const char*>(args.args[1]),
-                                    static_cast<int>(args.args[2]));
-#if defined(__NR_access)
-    case __NR_access:
-      return broker_process->Access(reinterpret_cast<const char*>(args.args[0]),
-                                    static_cast<int>(args.args[1]));
-#endif
-#if defined(__NR_open)
-    case __NR_open:
-      return broker_process->Open(reinterpret_cast<const char*>(args.args[0]),
-                                  static_cast<int>(args.args[1]));
-#endif
-    case __NR_openat:
-      // We only call open() so if we arrive here, it's because glibc uses
-      // the openat() system call.
-      BPF_ASSERT(static_cast<int>(args.args[0]) == AT_FDCWD);
-      return broker_process->Open(reinterpret_cast<const char*>(args.args[1]),
-                                  static_cast<int>(args.args[2]));
-    default:
-      BPF_ASSERT(false);
-      return -ENOSYS;
-  }
-}
-
-class DenyOpenPolicy : public Policy {
- public:
-  explicit DenyOpenPolicy(InitializedOpenBroker* iob) : iob_(iob) {}
-  ~DenyOpenPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-
-    switch (sysno) {
-      case __NR_faccessat:
-#if defined(__NR_access)
-      case __NR_access:
-#endif
-#if defined(__NR_open)
-      case __NR_open:
-#endif
-      case __NR_openat:
-        // We get a InitializedOpenBroker class, but our trap handler wants
-        // the syscall_broker::BrokerProcess object.
-        return Trap(BrokerOpenTrapHandler, iob_->broker_process());
-      default:
-        return Allow();
-    }
-  }
-
- private:
-  InitializedOpenBroker* iob_;
-
-  DISALLOW_COPY_AND_ASSIGN(DenyOpenPolicy);
-};
-
-// We use a InitializedOpenBroker class, so that we can run unsandboxed
-// code in its constructor, which is the only way to do so in a BPF_TEST.
-BPF_TEST(SandboxBPF,
-         UseOpenBroker,
-         DenyOpenPolicy,
-         InitializedOpenBroker /* (*BPF_AUX) */) {
-  BPF_ASSERT(BPF_AUX->initialized());
-  syscall_broker::BrokerProcess* broker_process = BPF_AUX->broker_process();
-  BPF_ASSERT(broker_process != NULL);
-
-  // First, use the broker "manually"
-  BPF_ASSERT(broker_process->Open("/proc/denied", O_RDONLY) == -EPERM);
-  BPF_ASSERT(broker_process->Access("/proc/denied", R_OK) == -EPERM);
-  BPF_ASSERT(broker_process->Open("/proc/allowed", O_RDONLY) == -ENOENT);
-  BPF_ASSERT(broker_process->Access("/proc/allowed", R_OK) == -ENOENT);
-
-  // Now use glibc's open() as an external library would.
-  BPF_ASSERT(open("/proc/denied", O_RDONLY) == -1);
-  BPF_ASSERT(errno == EPERM);
-
-  BPF_ASSERT(open("/proc/allowed", O_RDONLY) == -1);
-  BPF_ASSERT(errno == ENOENT);
-
-  // Also test glibc's openat(), some versions of libc use it transparently
-  // instead of open().
-  BPF_ASSERT(openat(AT_FDCWD, "/proc/denied", O_RDONLY) == -1);
-  BPF_ASSERT(errno == EPERM);
-
-  BPF_ASSERT(openat(AT_FDCWD, "/proc/allowed", O_RDONLY) == -1);
-  BPF_ASSERT(errno == ENOENT);
-
-  // And test glibc's access().
-  BPF_ASSERT(access("/proc/denied", R_OK) == -1);
-  BPF_ASSERT(errno == EPERM);
-
-  BPF_ASSERT(access("/proc/allowed", R_OK) == -1);
-  BPF_ASSERT(errno == ENOENT);
-
-  // This is also white listed and does exist.
-  int cpu_info_access = access("/proc/cpuinfo", R_OK);
-  BPF_ASSERT(cpu_info_access == 0);
-  int cpu_info_fd = open("/proc/cpuinfo", O_RDONLY);
-  BPF_ASSERT(cpu_info_fd >= 0);
-  char buf[1024];
-  BPF_ASSERT(read(cpu_info_fd, buf, sizeof(buf)) > 0);
-}
-
-// Simple test demonstrating how to use SandboxBPF::Cond()
-
-class SimpleCondTestPolicy : public Policy {
- public:
-  SimpleCondTestPolicy() {}
-  ~SimpleCondTestPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(SimpleCondTestPolicy);
-};
-
-ResultExpr SimpleCondTestPolicy::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-
-  // We deliberately return unusual errno values upon failure, so that we
-  // can uniquely test for these values. In a "real" policy, you would want
-  // to return more traditional values.
-  int flags_argument_position = -1;
-  switch (sysno) {
-#if defined(__NR_open)
-    case __NR_open:
-      flags_argument_position = 1;
-#endif
-    case __NR_openat: {  // open can be a wrapper for openat(2).
-      if (sysno == __NR_openat)
-        flags_argument_position = 2;
-
-      // Allow opening files for reading, but don't allow writing.
-      static_assert(O_RDONLY == 0, "O_RDONLY must be all zero bits");
-      const Arg<int> flags(flags_argument_position);
-      return If((flags & O_ACCMODE) != 0, Error(EROFS)).Else(Allow());
-    }
-    case __NR_prctl: {
-      // Allow prctl(PR_SET_DUMPABLE) and prctl(PR_GET_DUMPABLE), but
-      // disallow everything else.
-      const Arg<int> option(0);
-      return If(option == PR_SET_DUMPABLE || option == PR_GET_DUMPABLE, Allow())
-          .Else(Error(ENOMEM));
-    }
-    default:
-      return Allow();
-  }
-}
-
-BPF_TEST_C(SandboxBPF, SimpleCondTest, SimpleCondTestPolicy) {
-  int fd;
-  BPF_ASSERT((fd = open("/proc/self/comm", O_RDWR)) == -1);
-  BPF_ASSERT(errno == EROFS);
-  BPF_ASSERT((fd = open("/proc/self/comm", O_RDONLY)) >= 0);
-  close(fd);
-
-  int ret;
-  BPF_ASSERT((ret = prctl(PR_GET_DUMPABLE)) >= 0);
-  BPF_ASSERT(prctl(PR_SET_DUMPABLE, 1 - ret) == 0);
-  BPF_ASSERT(prctl(PR_GET_ENDIAN, &ret) == -1);
-  BPF_ASSERT(errno == ENOMEM);
-}
-
-// This test exercises the SandboxBPF::Cond() method by building a complex
-// tree of conditional equality operations. It then makes system calls and
-// verifies that they return the values that we expected from our BPF
-// program.
-class EqualityStressTest {
- public:
-  EqualityStressTest() {
-    // We want a deterministic test
-    srand(0);
-
-    // Iterates over system call numbers and builds a random tree of
-    // equality tests.
-    // We are actually constructing a graph of ArgValue objects. This
-    // graph will later be used to a) compute our sandbox policy, and
-    // b) drive the code that verifies the output from the BPF program.
-    static_assert(
-        kNumTestCases < (int)(MAX_PUBLIC_SYSCALL - MIN_SYSCALL - 10),
-        "kNumTestCases must be significantly smaller than the number "
-        "of system calls");
-    for (int sysno = MIN_SYSCALL, end = kNumTestCases; sysno < end; ++sysno) {
-      if (IsReservedSyscall(sysno)) {
-        // Skip reserved system calls. This ensures that our test frame
-        // work isn't impacted by the fact that we are overriding
-        // a lot of different system calls.
-        ++end;
-        arg_values_.push_back(NULL);
-      } else {
-        arg_values_.push_back(
-            RandomArgValue(rand() % kMaxArgs, 0, rand() % kMaxArgs));
-      }
-    }
-  }
-
-  ~EqualityStressTest() {
-    for (std::vector<ArgValue*>::iterator iter = arg_values_.begin();
-         iter != arg_values_.end();
-         ++iter) {
-      DeleteArgValue(*iter);
-    }
-  }
-
-  ResultExpr Policy(int sysno) {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    if (sysno < 0 || sysno >= (int)arg_values_.size() ||
-        IsReservedSyscall(sysno)) {
-      // We only return ErrorCode values for the system calls that
-      // are part of our test data. Every other system call remains
-      // allowed.
-      return Allow();
-    } else {
-      // ToErrorCode() turns an ArgValue object into an ErrorCode that is
-      // suitable for use by a sandbox policy.
-      return ToErrorCode(arg_values_[sysno]);
-    }
-  }
-
-  void VerifyFilter() {
-    // Iterate over all system calls. Skip the system calls that have
-    // previously been determined as being reserved.
-    for (int sysno = 0; sysno < (int)arg_values_.size(); ++sysno) {
-      if (!arg_values_[sysno]) {
-        // Skip reserved system calls.
-        continue;
-      }
-      // Verify that system calls return the values that we expect them to
-      // return. This involves passing different combinations of system call
-      // parameters in order to exercise all possible code paths through the
-      // BPF filter program.
-      // We arbitrarily start by setting all six system call arguments to
-      // zero. And we then recursive traverse our tree of ArgValues to
-      // determine the necessary combinations of parameters.
-      intptr_t args[6] = {};
-      Verify(sysno, args, *arg_values_[sysno]);
-    }
-  }
-
- private:
-  struct ArgValue {
-    int argno;  // Argument number to inspect.
-    int size;   // Number of test cases (must be > 0).
-    struct Tests {
-      uint32_t k_value;            // Value to compare syscall arg against.
-      int err;                     // If non-zero, errno value to return.
-      struct ArgValue* arg_value;  // Otherwise, more args needs inspecting.
-    }* tests;
-    int err;                     // If none of the tests passed, this is what
-    struct ArgValue* arg_value;  // we'll return (this is the "else" branch).
-  };
-
-  bool IsReservedSyscall(int sysno) {
-    // There are a handful of system calls that we should never use in our
-    // test cases. These system calls are needed to allow the test framework
-    // to run properly.
-    // If we wanted to write fully generic code, there are more system calls
-    // that could be listed here, and it is quite difficult to come up with a
-    // truly comprehensive list. After all, we are deliberately making system
-    // calls unavailable. In practice, we have a pretty good idea of the system
-    // calls that will be made by this particular test. So, this small list is
-    // sufficient. But if anybody copy'n'pasted this code for other uses, they
-    // would have to review that the list.
-    return sysno == __NR_read || sysno == __NR_write || sysno == __NR_exit ||
-           sysno == __NR_exit_group || sysno == __NR_restart_syscall;
-  }
-
-  ArgValue* RandomArgValue(int argno, int args_mask, int remaining_args) {
-    // Create a new ArgValue and fill it with random data. We use as bit mask
-    // to keep track of the system call parameters that have previously been
-    // set; this ensures that we won't accidentally define a contradictory
-    // set of equality tests.
-    struct ArgValue* arg_value = new ArgValue();
-    args_mask |= 1 << argno;
-    arg_value->argno = argno;
-
-    // Apply some restrictions on just how complex our tests can be.
-    // Otherwise, we end up with a BPF program that is too complicated for
-    // the kernel to load.
-    int fan_out = kMaxFanOut;
-    if (remaining_args > 3) {
-      fan_out = 1;
-    } else if (remaining_args > 2) {
-      fan_out = 2;
-    }
-
-    // Create a couple of different test cases with randomized values that
-    // we want to use when comparing system call parameter number "argno".
-    arg_value->size = rand() % fan_out + 1;
-    arg_value->tests = new ArgValue::Tests[arg_value->size];
-
-    uint32_t k_value = rand();
-    for (int n = 0; n < arg_value->size; ++n) {
-      // Ensure that we have unique values
-      k_value += rand() % (RAND_MAX / (kMaxFanOut + 1)) + 1;
-
-      // There are two possible types of nodes. Either this is a leaf node;
-      // in that case, we have completed all the equality tests that we
-      // wanted to perform, and we can now compute a random "errno" value that
-      // we should return. Or this is part of a more complex boolean
-      // expression; in that case, we have to recursively add tests for some
-      // of system call parameters that we have not yet included in our
-      // tests.
-      arg_value->tests[n].k_value = k_value;
-      if (!remaining_args || (rand() & 1)) {
-        arg_value->tests[n].err = (rand() % 1000) + 1;
-        arg_value->tests[n].arg_value = NULL;
-      } else {
-        arg_value->tests[n].err = 0;
-        arg_value->tests[n].arg_value =
-            RandomArgValue(RandomArg(args_mask), args_mask, remaining_args - 1);
-      }
-    }
-    // Finally, we have to define what we should return if none of the
-    // previous equality tests pass. Again, we can either deal with a leaf
-    // node, or we can randomly add another couple of tests.
-    if (!remaining_args || (rand() & 1)) {
-      arg_value->err = (rand() % 1000) + 1;
-      arg_value->arg_value = NULL;
-    } else {
-      arg_value->err = 0;
-      arg_value->arg_value =
-          RandomArgValue(RandomArg(args_mask), args_mask, remaining_args - 1);
-    }
-    // We have now built a new (sub-)tree of ArgValues defining a set of
-    // boolean expressions for testing random system call arguments against
-    // random values. Return this tree to our caller.
-    return arg_value;
-  }
-
-  int RandomArg(int args_mask) {
-    // Compute a random system call parameter number.
-    int argno = rand() % kMaxArgs;
-
-    // Make sure that this same parameter number has not previously been
-    // used. Otherwise, we could end up with a test that is impossible to
-    // satisfy (e.g. args[0] == 1 && args[0] == 2).
-    while (args_mask & (1 << argno)) {
-      argno = (argno + 1) % kMaxArgs;
-    }
-    return argno;
-  }
-
-  void DeleteArgValue(ArgValue* arg_value) {
-    // Delete an ArgValue and all of its child nodes. This requires
-    // recursively descending into the tree.
-    if (arg_value) {
-      if (arg_value->size) {
-        for (int n = 0; n < arg_value->size; ++n) {
-          if (!arg_value->tests[n].err) {
-            DeleteArgValue(arg_value->tests[n].arg_value);
-          }
-        }
-        delete[] arg_value->tests;
-      }
-      if (!arg_value->err) {
-        DeleteArgValue(arg_value->arg_value);
-      }
-      delete arg_value;
-    }
-  }
-
-  ResultExpr ToErrorCode(ArgValue* arg_value) {
-    // Compute the ResultExpr that should be returned, if none of our
-    // tests succeed (i.e. the system call parameter doesn't match any
-    // of the values in arg_value->tests[].k_value).
-    ResultExpr err;
-    if (arg_value->err) {
-      // If this was a leaf node, return the errno value that we expect to
-      // return from the BPF filter program.
-      err = Error(arg_value->err);
-    } else {
-      // If this wasn't a leaf node yet, recursively descend into the rest
-      // of the tree. This will end up adding a few more SandboxBPF::Cond()
-      // tests to our ErrorCode.
-      err = ToErrorCode(arg_value->arg_value);
-    }
-
-    // Now, iterate over all the test cases that we want to compare against.
-    // This builds a chain of SandboxBPF::Cond() tests
-    // (aka "if ... elif ... elif ... elif ... fi")
-    for (int n = arg_value->size; n-- > 0;) {
-      ResultExpr matched;
-      // Again, we distinguish between leaf nodes and subtrees.
-      if (arg_value->tests[n].err) {
-        matched = Error(arg_value->tests[n].err);
-      } else {
-        matched = ToErrorCode(arg_value->tests[n].arg_value);
-      }
-      // For now, all of our tests are limited to 32bit.
-      // We have separate tests that check the behavior of 32bit vs. 64bit
-      // conditional expressions.
-      const Arg<uint32_t> arg(arg_value->argno);
-      err = If(arg == arg_value->tests[n].k_value, matched).Else(err);
-    }
-    return err;
-  }
-
-  void Verify(int sysno, intptr_t* args, const ArgValue& arg_value) {
-    uint32_t mismatched = 0;
-    // Iterate over all the k_values in arg_value.tests[] and verify that
-    // we see the expected return values from system calls, when we pass
-    // the k_value as a parameter in a system call.
-    for (int n = arg_value.size; n-- > 0;) {
-      mismatched += arg_value.tests[n].k_value;
-      args[arg_value.argno] = arg_value.tests[n].k_value;
-      if (arg_value.tests[n].err) {
-        VerifyErrno(sysno, args, arg_value.tests[n].err);
-      } else {
-        Verify(sysno, args, *arg_value.tests[n].arg_value);
-      }
-    }
-  // Find a k_value that doesn't match any of the k_values in
-  // arg_value.tests[]. In most cases, the current value of "mismatched"
-  // would fit this requirement. But on the off-chance that it happens
-  // to collide, we double-check.
-  try_again:
-    for (int n = arg_value.size; n-- > 0;) {
-      if (mismatched == arg_value.tests[n].k_value) {
-        ++mismatched;
-        goto try_again;
-      }
-    }
-    // Now verify that we see the expected return value from system calls,
-    // if we pass a value that doesn't match any of the conditions (i.e. this
-    // is testing the "else" clause of the conditions).
-    args[arg_value.argno] = mismatched;
-    if (arg_value.err) {
-      VerifyErrno(sysno, args, arg_value.err);
-    } else {
-      Verify(sysno, args, *arg_value.arg_value);
-    }
-    // Reset args[arg_value.argno]. This is not technically needed, but it
-    // makes it easier to reason about the correctness of our tests.
-    args[arg_value.argno] = 0;
-  }
-
-  void VerifyErrno(int sysno, intptr_t* args, int err) {
-    // We installed BPF filters that return different errno values
-    // based on the system call number and the parameters that we decided
-    // to pass in. Verify that this condition holds true.
-    BPF_ASSERT(
-        Syscall::Call(
-            sysno, args[0], args[1], args[2], args[3], args[4], args[5]) ==
-        -err);
-  }
-
-  // Vector of ArgValue trees. These trees define all the possible boolean
-  // expressions that we want to turn into a BPF filter program.
-  std::vector<ArgValue*> arg_values_;
-
-  // Don't increase these values. We are pushing the limits of the maximum
-  // BPF program that the kernel will allow us to load. If the values are
-  // increased too much, the test will start failing.
-#if defined(__aarch64__)
-  static const int kNumTestCases = 30;
-#else
-  static const int kNumTestCases = 40;
-#endif
-  static const int kMaxFanOut = 3;
-  static const int kMaxArgs = 6;
-};
-
-class EqualityStressTestPolicy : public Policy {
- public:
-  explicit EqualityStressTestPolicy(EqualityStressTest* aux) : aux_(aux) {}
-  ~EqualityStressTestPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    return aux_->Policy(sysno);
-  }
-
- private:
-  EqualityStressTest* aux_;
-
-  DISALLOW_COPY_AND_ASSIGN(EqualityStressTestPolicy);
-};
-
-BPF_TEST(SandboxBPF,
-         EqualityTests,
-         EqualityStressTestPolicy,
-         EqualityStressTest /* (*BPF_AUX) */) {
-  BPF_AUX->VerifyFilter();
-}
-
-class EqualityArgumentWidthPolicy : public Policy {
- public:
-  EqualityArgumentWidthPolicy() {}
-  ~EqualityArgumentWidthPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(EqualityArgumentWidthPolicy);
-};
-
-ResultExpr EqualityArgumentWidthPolicy::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-  if (sysno == __NR_uname) {
-    const Arg<int> option(0);
-    const Arg<uint32_t> arg32(1);
-    const Arg<uint64_t> arg64(1);
-    return Switch(option)
-        .Case(0, If(arg32 == 0x55555555, Error(1)).Else(Error(2)))
-#if __SIZEOF_POINTER__ > 4
-        .Case(1, If(arg64 == 0x55555555AAAAAAAAULL, Error(1)).Else(Error(2)))
-#endif
-        .Default(Error(3));
-  }
-  return Allow();
-}
-
-BPF_TEST_C(SandboxBPF, EqualityArgumentWidth, EqualityArgumentWidthPolicy) {
-  BPF_ASSERT(Syscall::Call(__NR_uname, 0, 0x55555555) == -1);
-  BPF_ASSERT(Syscall::Call(__NR_uname, 0, 0xAAAAAAAA) == -2);
-#if __SIZEOF_POINTER__ > 4
-  // On 32bit machines, there is no way to pass a 64bit argument through the
-  // syscall interface. So, we have to skip the part of the test that requires
-  // 64bit arguments.
-  BPF_ASSERT(Syscall::Call(__NR_uname, 1, 0x55555555AAAAAAAAULL) == -1);
-  BPF_ASSERT(Syscall::Call(__NR_uname, 1, 0x5555555500000000ULL) == -2);
-  BPF_ASSERT(Syscall::Call(__NR_uname, 1, 0x5555555511111111ULL) == -2);
-  BPF_ASSERT(Syscall::Call(__NR_uname, 1, 0x11111111AAAAAAAAULL) == -2);
-#endif
-}
-
-#if __SIZEOF_POINTER__ > 4
-// On 32bit machines, there is no way to pass a 64bit argument through the
-// syscall interface. So, we have to skip the part of the test that requires
-// 64bit arguments.
-BPF_DEATH_TEST_C(SandboxBPF,
-                 EqualityArgumentUnallowed64bit,
-                 DEATH_MESSAGE("Unexpected 64bit argument detected"),
-                 EqualityArgumentWidthPolicy) {
-  Syscall::Call(__NR_uname, 0, 0x5555555555555555ULL);
-}
-#endif
-
-class EqualityWithNegativeArgumentsPolicy : public Policy {
- public:
-  EqualityWithNegativeArgumentsPolicy() {}
-  ~EqualityWithNegativeArgumentsPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    if (sysno == __NR_uname) {
-      // TODO(mdempsky): This currently can't be Arg<int> because then
-      // 0xFFFFFFFF will be treated as a (signed) int, and then when
-      // Arg::EqualTo casts it to uint64_t, it will be sign extended.
-      const Arg<unsigned> arg(0);
-      return If(arg == 0xFFFFFFFF, Error(1)).Else(Error(2));
-    }
-    return Allow();
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(EqualityWithNegativeArgumentsPolicy);
-};
-
-BPF_TEST_C(SandboxBPF,
-           EqualityWithNegativeArguments,
-           EqualityWithNegativeArgumentsPolicy) {
-  BPF_ASSERT(Syscall::Call(__NR_uname, 0xFFFFFFFF) == -1);
-  BPF_ASSERT(Syscall::Call(__NR_uname, -1) == -1);
-  BPF_ASSERT(Syscall::Call(__NR_uname, -1LL) == -1);
-}
-
-#if __SIZEOF_POINTER__ > 4
-BPF_DEATH_TEST_C(SandboxBPF,
-                 EqualityWithNegative64bitArguments,
-                 DEATH_MESSAGE("Unexpected 64bit argument detected"),
-                 EqualityWithNegativeArgumentsPolicy) {
-  // When expecting a 32bit system call argument, we look at the MSB of the
-  // 64bit value and allow both "0" and "-1". But the latter is allowed only
-  // iff the LSB was negative. So, this death test should error out.
-  BPF_ASSERT(Syscall::Call(__NR_uname, 0xFFFFFFFF00000000LL) == -1);
-}
-#endif
-
-class AllBitTestPolicy : public Policy {
- public:
-  AllBitTestPolicy() {}
-  ~AllBitTestPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  static ResultExpr HasAllBits32(uint32_t bits);
-  static ResultExpr HasAllBits64(uint64_t bits);
-
-  DISALLOW_COPY_AND_ASSIGN(AllBitTestPolicy);
-};
-
-ResultExpr AllBitTestPolicy::HasAllBits32(uint32_t bits) {
-  if (bits == 0) {
-    return Error(1);
-  }
-  const Arg<uint32_t> arg(1);
-  return If((arg & bits) == bits, Error(1)).Else(Error(0));
-}
-
-ResultExpr AllBitTestPolicy::HasAllBits64(uint64_t bits) {
-  if (bits == 0) {
-    return Error(1);
-  }
-  const Arg<uint64_t> arg(1);
-  return If((arg & bits) == bits, Error(1)).Else(Error(0));
-}
-
-ResultExpr AllBitTestPolicy::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-  // Test masked-equality cases that should trigger the "has all bits"
-  // peephole optimizations. We try to find bitmasks that could conceivably
-  // touch corner cases.
-  // For all of these tests, we override the uname(). We can make use with
-  // a single system call number, as we use the first system call argument to
-  // select the different bit masks that we want to test against.
-  if (sysno == __NR_uname) {
-    const Arg<int> option(0);
-    return Switch(option)
-        .Case(0, HasAllBits32(0x0))
-        .Case(1, HasAllBits32(0x1))
-        .Case(2, HasAllBits32(0x3))
-        .Case(3, HasAllBits32(0x80000000))
-#if __SIZEOF_POINTER__ > 4
-        .Case(4, HasAllBits64(0x0))
-        .Case(5, HasAllBits64(0x1))
-        .Case(6, HasAllBits64(0x3))
-        .Case(7, HasAllBits64(0x80000000))
-        .Case(8, HasAllBits64(0x100000000ULL))
-        .Case(9, HasAllBits64(0x300000000ULL))
-        .Case(10, HasAllBits64(0x100000001ULL))
-#endif
-        .Default(Kill("Invalid test case number"));
-  }
-  return Allow();
-}
-
-// Define a macro that performs tests using our test policy.
-// NOTE: Not all of the arguments in this macro are actually used!
-//       They are here just to serve as documentation of the conditions
-//       implemented in the test policy.
-//       Most notably, "op" and "mask" are unused by the macro. If you want
-//       to make changes to these values, you will have to edit the
-//       test policy instead.
-#define BITMASK_TEST(testcase, arg, op, mask, expected_value) \
-  BPF_ASSERT(Syscall::Call(__NR_uname, (testcase), (arg)) == (expected_value))
-
-// Our uname() system call returns ErrorCode(1) for success and
-// ErrorCode(0) for failure. Syscall::Call() turns this into an
-// exit code of -1 or 0.
-#define EXPECT_FAILURE 0
-#define EXPECT_SUCCESS -1
-
-// A couple of our tests behave differently on 32bit and 64bit systems, as
-// there is no way for a 32bit system call to pass in a 64bit system call
-// argument "arg".
-// We expect these tests to succeed on 64bit systems, but to tail on 32bit
-// systems.
-#define EXPT64_SUCCESS (sizeof(void*) > 4 ? EXPECT_SUCCESS : EXPECT_FAILURE)
-BPF_TEST_C(SandboxBPF, AllBitTests, AllBitTestPolicy) {
-  // 32bit test: all of 0x0 (should always be true)
-  BITMASK_TEST( 0,                   0, ALLBITS32,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 0,                   1, ALLBITS32,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 0,                   3, ALLBITS32,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 0,         0xFFFFFFFFU, ALLBITS32,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 0,                -1LL, ALLBITS32,          0, EXPECT_SUCCESS);
-
-  // 32bit test: all of 0x1
-  BITMASK_TEST( 1,                   0, ALLBITS32,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 1,                   1, ALLBITS32,        0x1, EXPECT_SUCCESS);
-  BITMASK_TEST( 1,                   2, ALLBITS32,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 1,                   3, ALLBITS32,        0x1, EXPECT_SUCCESS);
-
-  // 32bit test: all of 0x3
-  BITMASK_TEST( 2,                   0, ALLBITS32,        0x3, EXPECT_FAILURE);
-  BITMASK_TEST( 2,                   1, ALLBITS32,        0x3, EXPECT_FAILURE);
-  BITMASK_TEST( 2,                   2, ALLBITS32,        0x3, EXPECT_FAILURE);
-  BITMASK_TEST( 2,                   3, ALLBITS32,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 2,                   7, ALLBITS32,        0x3, EXPECT_SUCCESS);
-
-  // 32bit test: all of 0x80000000
-  BITMASK_TEST( 3,                   0, ALLBITS32, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 3,         0x40000000U, ALLBITS32, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 3,         0x80000000U, ALLBITS32, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 3,         0xC0000000U, ALLBITS32, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 3,       -0x80000000LL, ALLBITS32, 0x80000000, EXPECT_SUCCESS);
-
-#if __SIZEOF_POINTER__ > 4
-  // 64bit test: all of 0x0 (should always be true)
-  BITMASK_TEST( 4,                   0, ALLBITS64,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 4,                   1, ALLBITS64,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 4,                   3, ALLBITS64,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 4,         0xFFFFFFFFU, ALLBITS64,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 4,       0x100000000LL, ALLBITS64,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 4,       0x300000000LL, ALLBITS64,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 4,0x8000000000000000LL, ALLBITS64,          0, EXPECT_SUCCESS);
-  BITMASK_TEST( 4,                -1LL, ALLBITS64,          0, EXPECT_SUCCESS);
-
-  // 64bit test: all of 0x1
-  BITMASK_TEST( 5,                   0, ALLBITS64,          1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,                   1, ALLBITS64,          1, EXPECT_SUCCESS);
-  BITMASK_TEST( 5,                   2, ALLBITS64,          1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,                   3, ALLBITS64,          1, EXPECT_SUCCESS);
-  BITMASK_TEST( 5,       0x100000000LL, ALLBITS64,          1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,       0x100000001LL, ALLBITS64,          1, EXPECT_SUCCESS);
-  BITMASK_TEST( 5,       0x100000002LL, ALLBITS64,          1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,       0x100000003LL, ALLBITS64,          1, EXPECT_SUCCESS);
-
-  // 64bit test: all of 0x3
-  BITMASK_TEST( 6,                   0, ALLBITS64,          3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,                   1, ALLBITS64,          3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,                   2, ALLBITS64,          3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,                   3, ALLBITS64,          3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,                   7, ALLBITS64,          3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,       0x100000000LL, ALLBITS64,          3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,       0x100000001LL, ALLBITS64,          3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,       0x100000002LL, ALLBITS64,          3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,       0x100000003LL, ALLBITS64,          3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,       0x100000007LL, ALLBITS64,          3, EXPECT_SUCCESS);
-
-  // 64bit test: all of 0x80000000
-  BITMASK_TEST( 7,                   0, ALLBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,         0x40000000U, ALLBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,         0x80000000U, ALLBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,         0xC0000000U, ALLBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,       -0x80000000LL, ALLBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,       0x100000000LL, ALLBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,       0x140000000LL, ALLBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,       0x180000000LL, ALLBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,       0x1C0000000LL, ALLBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,      -0x180000000LL, ALLBITS64, 0x80000000, EXPECT_SUCCESS);
-
-  // 64bit test: all of 0x100000000
-  BITMASK_TEST( 8,       0x000000000LL, ALLBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x100000000LL, ALLBITS64,0x100000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 8,       0x200000000LL, ALLBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x300000000LL, ALLBITS64,0x100000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 8,       0x000000001LL, ALLBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x100000001LL, ALLBITS64,0x100000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 8,       0x200000001LL, ALLBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x300000001LL, ALLBITS64,0x100000000, EXPT64_SUCCESS);
-
-  // 64bit test: all of 0x300000000
-  BITMASK_TEST( 9,       0x000000000LL, ALLBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x100000000LL, ALLBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x200000000LL, ALLBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x300000000LL, ALLBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x700000000LL, ALLBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x000000001LL, ALLBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x100000001LL, ALLBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x200000001LL, ALLBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x300000001LL, ALLBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x700000001LL, ALLBITS64,0x300000000, EXPT64_SUCCESS);
-
-  // 64bit test: all of 0x100000001
-  BITMASK_TEST(10,       0x000000000LL, ALLBITS64,0x100000001, EXPECT_FAILURE);
-  BITMASK_TEST(10,       0x000000001LL, ALLBITS64,0x100000001, EXPECT_FAILURE);
-  BITMASK_TEST(10,       0x100000000LL, ALLBITS64,0x100000001, EXPECT_FAILURE);
-  BITMASK_TEST(10,       0x100000001LL, ALLBITS64,0x100000001, EXPT64_SUCCESS);
-  BITMASK_TEST(10,         0xFFFFFFFFU, ALLBITS64,0x100000001, EXPECT_FAILURE);
-  BITMASK_TEST(10,                 -1L, ALLBITS64,0x100000001, EXPT64_SUCCESS);
-#endif
-}
-
-class AnyBitTestPolicy : public Policy {
- public:
-  AnyBitTestPolicy() {}
-  ~AnyBitTestPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  static ResultExpr HasAnyBits32(uint32_t);
-  static ResultExpr HasAnyBits64(uint64_t);
-
-  DISALLOW_COPY_AND_ASSIGN(AnyBitTestPolicy);
-};
-
-ResultExpr AnyBitTestPolicy::HasAnyBits32(uint32_t bits) {
-  if (bits == 0) {
-    return Error(0);
-  }
-  const Arg<uint32_t> arg(1);
-  return If((arg & bits) != 0, Error(1)).Else(Error(0));
-}
-
-ResultExpr AnyBitTestPolicy::HasAnyBits64(uint64_t bits) {
-  if (bits == 0) {
-    return Error(0);
-  }
-  const Arg<uint64_t> arg(1);
-  return If((arg & bits) != 0, Error(1)).Else(Error(0));
-}
-
-ResultExpr AnyBitTestPolicy::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-  // Test masked-equality cases that should trigger the "has any bits"
-  // peephole optimizations. We try to find bitmasks that could conceivably
-  // touch corner cases.
-  // For all of these tests, we override the uname(). We can make use with
-  // a single system call number, as we use the first system call argument to
-  // select the different bit masks that we want to test against.
-  if (sysno == __NR_uname) {
-    const Arg<int> option(0);
-    return Switch(option)
-        .Case(0, HasAnyBits32(0x0))
-        .Case(1, HasAnyBits32(0x1))
-        .Case(2, HasAnyBits32(0x3))
-        .Case(3, HasAnyBits32(0x80000000))
-#if __SIZEOF_POINTER__ > 4
-        .Case(4, HasAnyBits64(0x0))
-        .Case(5, HasAnyBits64(0x1))
-        .Case(6, HasAnyBits64(0x3))
-        .Case(7, HasAnyBits64(0x80000000))
-        .Case(8, HasAnyBits64(0x100000000ULL))
-        .Case(9, HasAnyBits64(0x300000000ULL))
-        .Case(10, HasAnyBits64(0x100000001ULL))
-#endif
-        .Default(Kill("Invalid test case number"));
-  }
-  return Allow();
-}
-
-BPF_TEST_C(SandboxBPF, AnyBitTests, AnyBitTestPolicy) {
-  // 32bit test: any of 0x0 (should always be false)
-  BITMASK_TEST( 0,                   0, ANYBITS32,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 0,                   1, ANYBITS32,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 0,                   3, ANYBITS32,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 0,         0xFFFFFFFFU, ANYBITS32,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 0,                -1LL, ANYBITS32,        0x0, EXPECT_FAILURE);
-
-  // 32bit test: any of 0x1
-  BITMASK_TEST( 1,                   0, ANYBITS32,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 1,                   1, ANYBITS32,        0x1, EXPECT_SUCCESS);
-  BITMASK_TEST( 1,                   2, ANYBITS32,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 1,                   3, ANYBITS32,        0x1, EXPECT_SUCCESS);
-
-  // 32bit test: any of 0x3
-  BITMASK_TEST( 2,                   0, ANYBITS32,        0x3, EXPECT_FAILURE);
-  BITMASK_TEST( 2,                   1, ANYBITS32,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 2,                   2, ANYBITS32,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 2,                   3, ANYBITS32,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 2,                   7, ANYBITS32,        0x3, EXPECT_SUCCESS);
-
-  // 32bit test: any of 0x80000000
-  BITMASK_TEST( 3,                   0, ANYBITS32, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 3,         0x40000000U, ANYBITS32, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 3,         0x80000000U, ANYBITS32, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 3,         0xC0000000U, ANYBITS32, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 3,       -0x80000000LL, ANYBITS32, 0x80000000, EXPECT_SUCCESS);
-
-#if __SIZEOF_POINTER__ > 4
-  // 64bit test: any of 0x0 (should always be false)
-  BITMASK_TEST( 4,                   0, ANYBITS64,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 4,                   1, ANYBITS64,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 4,                   3, ANYBITS64,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 4,         0xFFFFFFFFU, ANYBITS64,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 4,       0x100000000LL, ANYBITS64,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 4,       0x300000000LL, ANYBITS64,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 4,0x8000000000000000LL, ANYBITS64,        0x0, EXPECT_FAILURE);
-  BITMASK_TEST( 4,                -1LL, ANYBITS64,        0x0, EXPECT_FAILURE);
-
-  // 64bit test: any of 0x1
-  BITMASK_TEST( 5,                   0, ANYBITS64,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,                   1, ANYBITS64,        0x1, EXPECT_SUCCESS);
-  BITMASK_TEST( 5,                   2, ANYBITS64,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,                   3, ANYBITS64,        0x1, EXPECT_SUCCESS);
-  BITMASK_TEST( 5,       0x100000001LL, ANYBITS64,        0x1, EXPECT_SUCCESS);
-  BITMASK_TEST( 5,       0x100000000LL, ANYBITS64,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,       0x100000002LL, ANYBITS64,        0x1, EXPECT_FAILURE);
-  BITMASK_TEST( 5,       0x100000003LL, ANYBITS64,        0x1, EXPECT_SUCCESS);
-
-  // 64bit test: any of 0x3
-  BITMASK_TEST( 6,                   0, ANYBITS64,        0x3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,                   1, ANYBITS64,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,                   2, ANYBITS64,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,                   3, ANYBITS64,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,                   7, ANYBITS64,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,       0x100000000LL, ANYBITS64,        0x3, EXPECT_FAILURE);
-  BITMASK_TEST( 6,       0x100000001LL, ANYBITS64,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,       0x100000002LL, ANYBITS64,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,       0x100000003LL, ANYBITS64,        0x3, EXPECT_SUCCESS);
-  BITMASK_TEST( 6,       0x100000007LL, ANYBITS64,        0x3, EXPECT_SUCCESS);
-
-  // 64bit test: any of 0x80000000
-  BITMASK_TEST( 7,                   0, ANYBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,         0x40000000U, ANYBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,         0x80000000U, ANYBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,         0xC0000000U, ANYBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,       -0x80000000LL, ANYBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,       0x100000000LL, ANYBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,       0x140000000LL, ANYBITS64, 0x80000000, EXPECT_FAILURE);
-  BITMASK_TEST( 7,       0x180000000LL, ANYBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,       0x1C0000000LL, ANYBITS64, 0x80000000, EXPECT_SUCCESS);
-  BITMASK_TEST( 7,      -0x180000000LL, ANYBITS64, 0x80000000, EXPECT_SUCCESS);
-
-  // 64bit test: any of 0x100000000
-  BITMASK_TEST( 8,       0x000000000LL, ANYBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x100000000LL, ANYBITS64,0x100000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 8,       0x200000000LL, ANYBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x300000000LL, ANYBITS64,0x100000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 8,       0x000000001LL, ANYBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x100000001LL, ANYBITS64,0x100000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 8,       0x200000001LL, ANYBITS64,0x100000000, EXPECT_FAILURE);
-  BITMASK_TEST( 8,       0x300000001LL, ANYBITS64,0x100000000, EXPT64_SUCCESS);
-
-  // 64bit test: any of 0x300000000
-  BITMASK_TEST( 9,       0x000000000LL, ANYBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x100000000LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x200000000LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x300000000LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x700000000LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x000000001LL, ANYBITS64,0x300000000, EXPECT_FAILURE);
-  BITMASK_TEST( 9,       0x100000001LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x200000001LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x300000001LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-  BITMASK_TEST( 9,       0x700000001LL, ANYBITS64,0x300000000, EXPT64_SUCCESS);
-
-  // 64bit test: any of 0x100000001
-  BITMASK_TEST( 10,      0x000000000LL, ANYBITS64,0x100000001, EXPECT_FAILURE);
-  BITMASK_TEST( 10,      0x000000001LL, ANYBITS64,0x100000001, EXPECT_SUCCESS);
-  BITMASK_TEST( 10,      0x100000000LL, ANYBITS64,0x100000001, EXPT64_SUCCESS);
-  BITMASK_TEST( 10,      0x100000001LL, ANYBITS64,0x100000001, EXPECT_SUCCESS);
-  BITMASK_TEST( 10,        0xFFFFFFFFU, ANYBITS64,0x100000001, EXPECT_SUCCESS);
-  BITMASK_TEST( 10,                -1L, ANYBITS64,0x100000001, EXPECT_SUCCESS);
-#endif
-}
-
-class MaskedEqualTestPolicy : public Policy {
- public:
-  MaskedEqualTestPolicy() {}
-  ~MaskedEqualTestPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  static ResultExpr MaskedEqual32(uint32_t mask, uint32_t value);
-  static ResultExpr MaskedEqual64(uint64_t mask, uint64_t value);
-
-  DISALLOW_COPY_AND_ASSIGN(MaskedEqualTestPolicy);
-};
-
-ResultExpr MaskedEqualTestPolicy::MaskedEqual32(uint32_t mask, uint32_t value) {
-  const Arg<uint32_t> arg(1);
-  return If((arg & mask) == value, Error(1)).Else(Error(0));
-}
-
-ResultExpr MaskedEqualTestPolicy::MaskedEqual64(uint64_t mask, uint64_t value) {
-  const Arg<uint64_t> arg(1);
-  return If((arg & mask) == value, Error(1)).Else(Error(0));
-}
-
-ResultExpr MaskedEqualTestPolicy::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-
-  if (sysno == __NR_uname) {
-    const Arg<int> option(0);
-    return Switch(option)
-        .Case(0, MaskedEqual32(0x00ff00ff, 0x005500aa))
-#if __SIZEOF_POINTER__ > 4
-        .Case(1, MaskedEqual64(0x00ff00ff00000000, 0x005500aa00000000))
-        .Case(2, MaskedEqual64(0x00ff00ff00ff00ff, 0x005500aa005500aa))
-#endif
-        .Default(Kill("Invalid test case number"));
-  }
-
-  return Allow();
-}
-
-#define MASKEQ_TEST(rulenum, arg, expected_result) \
-  BPF_ASSERT(Syscall::Call(__NR_uname, (rulenum), (arg)) == (expected_result))
-
-BPF_TEST_C(SandboxBPF, MaskedEqualTests, MaskedEqualTestPolicy) {
-  // Allowed:    0x__55__aa
-  MASKEQ_TEST(0, 0x00000000, EXPECT_FAILURE);
-  MASKEQ_TEST(0, 0x00000001, EXPECT_FAILURE);
-  MASKEQ_TEST(0, 0x00000003, EXPECT_FAILURE);
-  MASKEQ_TEST(0, 0x00000100, EXPECT_FAILURE);
-  MASKEQ_TEST(0, 0x00000300, EXPECT_FAILURE);
-  MASKEQ_TEST(0, 0x005500aa, EXPECT_SUCCESS);
-  MASKEQ_TEST(0, 0x005500ab, EXPECT_FAILURE);
-  MASKEQ_TEST(0, 0x005600aa, EXPECT_FAILURE);
-  MASKEQ_TEST(0, 0x005501aa, EXPECT_SUCCESS);
-  MASKEQ_TEST(0, 0x005503aa, EXPECT_SUCCESS);
-  MASKEQ_TEST(0, 0x555500aa, EXPECT_SUCCESS);
-  MASKEQ_TEST(0, 0xaa5500aa, EXPECT_SUCCESS);
-
-#if __SIZEOF_POINTER__ > 4
-  // Allowed:    0x__55__aa________
-  MASKEQ_TEST(1, 0x0000000000000000, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x0000000000000010, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x0000000000000050, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x0000000100000000, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x0000000300000000, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x0000010000000000, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x0000030000000000, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x005500aa00000000, EXPECT_SUCCESS);
-  MASKEQ_TEST(1, 0x005500ab00000000, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x005600aa00000000, EXPECT_FAILURE);
-  MASKEQ_TEST(1, 0x005501aa00000000, EXPECT_SUCCESS);
-  MASKEQ_TEST(1, 0x005503aa00000000, EXPECT_SUCCESS);
-  MASKEQ_TEST(1, 0x555500aa00000000, EXPECT_SUCCESS);
-  MASKEQ_TEST(1, 0xaa5500aa00000000, EXPECT_SUCCESS);
-  MASKEQ_TEST(1, 0xaa5500aa00000000, EXPECT_SUCCESS);
-  MASKEQ_TEST(1, 0xaa5500aa0000cafe, EXPECT_SUCCESS);
-
-  // Allowed:    0x__55__aa__55__aa
-  MASKEQ_TEST(2, 0x0000000000000000, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x0000000000000010, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x0000000000000050, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x0000000100000000, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x0000000300000000, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x0000010000000000, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x0000030000000000, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x00000000005500aa, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x005500aa00000000, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x005500aa005500aa, EXPECT_SUCCESS);
-  MASKEQ_TEST(2, 0x005500aa005700aa, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x005700aa005500aa, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x005500aa004500aa, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x004500aa005500aa, EXPECT_FAILURE);
-  MASKEQ_TEST(2, 0x005512aa005500aa, EXPECT_SUCCESS);
-  MASKEQ_TEST(2, 0x005500aa005534aa, EXPECT_SUCCESS);
-  MASKEQ_TEST(2, 0xff5500aa0055ffaa, EXPECT_SUCCESS);
-#endif
-}
-
-intptr_t PthreadTrapHandler(const struct arch_seccomp_data& args, void* aux) {
-  if (args.args[0] != (CLONE_CHILD_CLEARTID | CLONE_CHILD_SETTID | SIGCHLD)) {
-    // We expect to get called for an attempt to fork(). No need to log that
-    // call. But if we ever get called for anything else, we want to verbosely
-    // print as much information as possible.
-    const char* msg = (const char*)aux;
-    printf(
-        "Clone() was called with unexpected arguments\n"
-        "  nr: %d\n"
-        "  1: 0x%llX\n"
-        "  2: 0x%llX\n"
-        "  3: 0x%llX\n"
-        "  4: 0x%llX\n"
-        "  5: 0x%llX\n"
-        "  6: 0x%llX\n"
-        "%s\n",
-        args.nr,
-        (long long)args.args[0],
-        (long long)args.args[1],
-        (long long)args.args[2],
-        (long long)args.args[3],
-        (long long)args.args[4],
-        (long long)args.args[5],
-        msg);
-  }
-  return -EPERM;
-}
-
-class PthreadPolicyEquality : public Policy {
- public:
-  PthreadPolicyEquality() {}
-  ~PthreadPolicyEquality() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(PthreadPolicyEquality);
-};
-
-ResultExpr PthreadPolicyEquality::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-  // This policy allows creating threads with pthread_create(). But it
-  // doesn't allow any other uses of clone(). Most notably, it does not
-  // allow callers to implement fork() or vfork() by passing suitable flags
-  // to the clone() system call.
-  if (sysno == __NR_clone) {
-    // We have seen two different valid combinations of flags. Glibc
-    // uses the more modern flags, sets the TLS from the call to clone(), and
-    // uses futexes to monitor threads. Android's C run-time library, doesn't
-    // do any of this, but it sets the obsolete (and no-op) CLONE_DETACHED.
-    // More recent versions of Android don't set CLONE_DETACHED anymore, so
-    // the last case accounts for that.
-    // The following policy is very strict. It only allows the exact masks
-    // that we have seen in known implementations. It is probably somewhat
-    // stricter than what we would want to do.
-    const uint64_t kGlibcCloneMask = CLONE_VM | CLONE_FS | CLONE_FILES |
-                                     CLONE_SIGHAND | CLONE_THREAD |
-                                     CLONE_SYSVSEM | CLONE_SETTLS |
-                                     CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID;
-    const uint64_t kBaseAndroidCloneMask = CLONE_VM | CLONE_FS | CLONE_FILES |
-                                           CLONE_SIGHAND | CLONE_THREAD |
-                                           CLONE_SYSVSEM;
-    const Arg<unsigned long> flags(0);
-    return If(flags == kGlibcCloneMask ||
-                  flags == (kBaseAndroidCloneMask | CLONE_DETACHED) ||
-                  flags == kBaseAndroidCloneMask,
-              Allow()).Else(Trap(PthreadTrapHandler, "Unknown mask"));
-  }
-
-  return Allow();
-}
-
-class PthreadPolicyBitMask : public Policy {
- public:
-  PthreadPolicyBitMask() {}
-  ~PthreadPolicyBitMask() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override;
-
- private:
-  static BoolExpr HasAnyBits(const Arg<unsigned long>& arg, unsigned long bits);
-  static BoolExpr HasAllBits(const Arg<unsigned long>& arg, unsigned long bits);
-
-  DISALLOW_COPY_AND_ASSIGN(PthreadPolicyBitMask);
-};
-
-BoolExpr PthreadPolicyBitMask::HasAnyBits(const Arg<unsigned long>& arg,
-                                          unsigned long bits) {
-  return (arg & bits) != 0;
-}
-
-BoolExpr PthreadPolicyBitMask::HasAllBits(const Arg<unsigned long>& arg,
-                                          unsigned long bits) {
-  return (arg & bits) == bits;
-}
-
-ResultExpr PthreadPolicyBitMask::EvaluateSyscall(int sysno) const {
-  DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-  // This policy allows creating threads with pthread_create(). But it
-  // doesn't allow any other uses of clone(). Most notably, it does not
-  // allow callers to implement fork() or vfork() by passing suitable flags
-  // to the clone() system call.
-  if (sysno == __NR_clone) {
-    // We have seen two different valid combinations of flags. Glibc
-    // uses the more modern flags, sets the TLS from the call to clone(), and
-    // uses futexes to monitor threads. Android's C run-time library, doesn't
-    // do any of this, but it sets the obsolete (and no-op) CLONE_DETACHED.
-    // The following policy allows for either combination of flags, but it
-    // is generally a little more conservative than strictly necessary. We
-    // err on the side of rather safe than sorry.
-    // Very noticeably though, we disallow fork() (which is often just a
-    // wrapper around clone()).
-    const unsigned long kMandatoryFlags = CLONE_VM | CLONE_FS | CLONE_FILES |
-                                          CLONE_SIGHAND | CLONE_THREAD |
-                                          CLONE_SYSVSEM;
-    const unsigned long kFutexFlags =
-        CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID;
-    const unsigned long kNoopFlags = CLONE_DETACHED;
-    const unsigned long kKnownFlags =
-        kMandatoryFlags | kFutexFlags | kNoopFlags;
-
-    const Arg<unsigned long> flags(0);
-    return If(HasAnyBits(flags, ~kKnownFlags),
-              Trap(PthreadTrapHandler, "Unexpected CLONE_XXX flag found"))
-        .ElseIf(!HasAllBits(flags, kMandatoryFlags),
-                Trap(PthreadTrapHandler,
-                     "Missing mandatory CLONE_XXX flags "
-                     "when creating new thread"))
-        .ElseIf(
-             !HasAllBits(flags, kFutexFlags) && HasAnyBits(flags, kFutexFlags),
-             Trap(PthreadTrapHandler,
-                  "Must set either all or none of the TLS and futex bits in "
-                  "call to clone()"))
-        .Else(Allow());
-  }
-
-  return Allow();
-}
-
-static void* ThreadFnc(void* arg) {
-  ++*reinterpret_cast<int*>(arg);
-  Syscall::Call(__NR_futex, arg, FUTEX_WAKE, 1, 0, 0, 0);
-  return NULL;
-}
-
-static void PthreadTest() {
-  // Attempt to start a joinable thread. This should succeed.
-  pthread_t thread;
-  int thread_ran = 0;
-  BPF_ASSERT(!pthread_create(&thread, NULL, ThreadFnc, &thread_ran));
-  BPF_ASSERT(!pthread_join(thread, NULL));
-  BPF_ASSERT(thread_ran);
-
-  // Attempt to start a detached thread. This should succeed.
-  thread_ran = 0;
-  pthread_attr_t attr;
-  BPF_ASSERT(!pthread_attr_init(&attr));
-  BPF_ASSERT(!pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED));
-  BPF_ASSERT(!pthread_create(&thread, &attr, ThreadFnc, &thread_ran));
-  BPF_ASSERT(!pthread_attr_destroy(&attr));
-  while (Syscall::Call(__NR_futex, &thread_ran, FUTEX_WAIT, 0, 0, 0, 0) ==
-         -EINTR) {
-  }
-  BPF_ASSERT(thread_ran);
-
-  // Attempt to fork() a process using clone(). This should fail. We use the
-  // same flags that glibc uses when calling fork(). But we don't actually
-  // try calling the fork() implementation in the C run-time library, as
-  // run-time libraries other than glibc might call __NR_fork instead of
-  // __NR_clone, and that would introduce a bogus test failure.
-  int pid;
-  BPF_ASSERT(Syscall::Call(__NR_clone,
-                           CLONE_CHILD_CLEARTID | CLONE_CHILD_SETTID | SIGCHLD,
-                           0,
-                           0,
-                           &pid) == -EPERM);
-}
-
-BPF_TEST_C(SandboxBPF, PthreadEquality, PthreadPolicyEquality) {
-  PthreadTest();
-}
-
-BPF_TEST_C(SandboxBPF, PthreadBitMask, PthreadPolicyBitMask) {
-  PthreadTest();
-}
-
-// libc might not define these even though the kernel supports it.
-#ifndef PTRACE_O_TRACESECCOMP
-#define PTRACE_O_TRACESECCOMP 0x00000080
-#endif
-
-#ifdef PTRACE_EVENT_SECCOMP
-#define IS_SECCOMP_EVENT(status) ((status >> 16) == PTRACE_EVENT_SECCOMP)
-#else
-// When Debian/Ubuntu backported seccomp-bpf support into earlier kernels, they
-// changed the value of PTRACE_EVENT_SECCOMP from 7 to 8, since 7 was taken by
-// PTRACE_EVENT_STOP (upstream chose to renumber PTRACE_EVENT_STOP to 128).  If
-// PTRACE_EVENT_SECCOMP isn't defined, we have no choice but to consider both
-// values here.
-#define IS_SECCOMP_EVENT(status) ((status >> 16) == 7 || (status >> 16) == 8)
-#endif
-
-#if defined(__arm__)
-#ifndef PTRACE_SET_SYSCALL
-#define PTRACE_SET_SYSCALL 23
-#endif
-#endif
-
-#if defined(__aarch64__)
-#ifndef PTRACE_GETREGS
-#define PTRACE_GETREGS 12
-#endif
-#endif
-
-#if defined(__aarch64__)
-#ifndef PTRACE_SETREGS
-#define PTRACE_SETREGS 13
-#endif
-#endif
-
-// Changes the syscall to run for a child being sandboxed using seccomp-bpf with
-// PTRACE_O_TRACESECCOMP.  Should only be called when the child is stopped on
-// PTRACE_EVENT_SECCOMP.
-//
-// regs should contain the current set of registers of the child, obtained using
-// PTRACE_GETREGS.
-//
-// Depending on the architecture, this may modify regs, so the caller is
-// responsible for committing these changes using PTRACE_SETREGS.
-long SetSyscall(pid_t pid, regs_struct* regs, int syscall_number) {
-#if defined(__arm__)
-  // On ARM, the syscall is changed using PTRACE_SET_SYSCALL.  We cannot use the
-  // libc ptrace call as the request parameter is an enum, and
-  // PTRACE_SET_SYSCALL may not be in the enum.
-  return syscall(__NR_ptrace, PTRACE_SET_SYSCALL, pid, NULL, syscall_number);
-#endif
-
-  SECCOMP_PT_SYSCALL(*regs) = syscall_number;
-  return 0;
-}
-
-const uint16_t kTraceData = 0xcc;
-
-class TraceAllPolicy : public Policy {
- public:
-  TraceAllPolicy() {}
-  ~TraceAllPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int system_call_number) const override {
-    return Trace(kTraceData);
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(TraceAllPolicy);
-};
-
-SANDBOX_TEST(SandboxBPF, DISABLE_ON_TSAN(SeccompRetTrace)) {
-  if (!SandboxBPF::SupportsSeccompSandbox(
-          SandboxBPF::SeccompLevel::SINGLE_THREADED)) {
-    return;
-  }
-
-// This test is disabled on arm due to a kernel bug.
-// See https://code.google.com/p/chromium/issues/detail?id=383977
-#if defined(__arm__) || defined(__aarch64__)
-  printf("This test is currently disabled on ARM32/64 due to a kernel bug.");
-  return;
-#endif
-
-#if defined(__mips__)
-  // TODO: Figure out how to support specificity of handling indirect syscalls
-  //        in this test and enable it.
-  printf("This test is currently disabled on MIPS.");
-  return;
-#endif
-
-  pid_t pid = fork();
-  BPF_ASSERT_NE(-1, pid);
-  if (pid == 0) {
-    pid_t my_pid = getpid();
-    BPF_ASSERT_NE(-1, ptrace(PTRACE_TRACEME, -1, NULL, NULL));
-    BPF_ASSERT_EQ(0, raise(SIGSTOP));
-    SandboxBPF sandbox(new TraceAllPolicy);
-    BPF_ASSERT(sandbox.StartSandbox(SandboxBPF::SeccompLevel::SINGLE_THREADED));
-
-    // getpid is allowed.
-    BPF_ASSERT_EQ(my_pid, sys_getpid());
-
-    // write to stdout is skipped and returns a fake value.
-    BPF_ASSERT_EQ(kExpectedReturnValue,
-                  syscall(__NR_write, STDOUT_FILENO, "A", 1));
-
-    // kill is rewritten to exit(kExpectedReturnValue).
-    syscall(__NR_kill, my_pid, SIGKILL);
-
-    // Should not be reached.
-    BPF_ASSERT(false);
-  }
-
-  int status;
-  BPF_ASSERT(HANDLE_EINTR(waitpid(pid, &status, WUNTRACED)) != -1);
-  BPF_ASSERT(WIFSTOPPED(status));
-
-  BPF_ASSERT_NE(-1,
-                ptrace(PTRACE_SETOPTIONS,
-                       pid,
-                       NULL,
-                       reinterpret_cast<void*>(PTRACE_O_TRACESECCOMP)));
-  BPF_ASSERT_NE(-1, ptrace(PTRACE_CONT, pid, NULL, NULL));
-  while (true) {
-    BPF_ASSERT(HANDLE_EINTR(waitpid(pid, &status, 0)) != -1);
-    if (WIFEXITED(status) || WIFSIGNALED(status)) {
-      BPF_ASSERT(WIFEXITED(status));
-      BPF_ASSERT_EQ(kExpectedReturnValue, WEXITSTATUS(status));
-      break;
-    }
-
-    if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGTRAP ||
-        !IS_SECCOMP_EVENT(status)) {
-      BPF_ASSERT_NE(-1, ptrace(PTRACE_CONT, pid, NULL, NULL));
-      continue;
-    }
-
-    unsigned long data;
-    BPF_ASSERT_NE(-1, ptrace(PTRACE_GETEVENTMSG, pid, NULL, &data));
-    BPF_ASSERT_EQ(kTraceData, data);
-
-    regs_struct regs;
-    BPF_ASSERT_NE(-1, ptrace(PTRACE_GETREGS, pid, NULL, &regs));
-    switch (SECCOMP_PT_SYSCALL(regs)) {
-      case __NR_write:
-        // Skip writes to stdout, make it return kExpectedReturnValue.  Allow
-        // writes to stderr so that BPF_ASSERT messages show up.
-        if (SECCOMP_PT_PARM1(regs) == STDOUT_FILENO) {
-          BPF_ASSERT_NE(-1, SetSyscall(pid, &regs, -1));
-          SECCOMP_PT_RESULT(regs) = kExpectedReturnValue;
-          BPF_ASSERT_NE(-1, ptrace(PTRACE_SETREGS, pid, NULL, &regs));
-        }
-        break;
-
-      case __NR_kill:
-        // Rewrite to exit(kExpectedReturnValue).
-        BPF_ASSERT_NE(-1, SetSyscall(pid, &regs, __NR_exit));
-        SECCOMP_PT_PARM1(regs) = kExpectedReturnValue;
-        BPF_ASSERT_NE(-1, ptrace(PTRACE_SETREGS, pid, NULL, &regs));
-        break;
-
-      default:
-        // Allow all other syscalls.
-        break;
-    }
-
-    BPF_ASSERT_NE(-1, ptrace(PTRACE_CONT, pid, NULL, NULL));
-  }
-}
-
-// Android does not expose pread64 nor pwrite64.
-#if !defined(OS_ANDROID)
-
-bool FullPwrite64(int fd, const char* buffer, size_t count, off64_t offset) {
-  while (count > 0) {
-    const ssize_t transfered =
-        HANDLE_EINTR(pwrite64(fd, buffer, count, offset));
-    if (transfered <= 0 || static_cast<size_t>(transfered) > count) {
-      return false;
-    }
-    count -= transfered;
-    buffer += transfered;
-    offset += transfered;
-  }
-  return true;
-}
-
-bool FullPread64(int fd, char* buffer, size_t count, off64_t offset) {
-  while (count > 0) {
-    const ssize_t transfered = HANDLE_EINTR(pread64(fd, buffer, count, offset));
-    if (transfered <= 0 || static_cast<size_t>(transfered) > count) {
-      return false;
-    }
-    count -= transfered;
-    buffer += transfered;
-    offset += transfered;
-  }
-  return true;
-}
-
-bool pread_64_was_forwarded = false;
-
-class TrapPread64Policy : public Policy {
- public:
-  TrapPread64Policy() {}
-  ~TrapPread64Policy() override {}
-
-  ResultExpr EvaluateSyscall(int system_call_number) const override {
-    // Set the global environment for unsafe traps once.
-    if (system_call_number == MIN_SYSCALL) {
-      EnableUnsafeTraps();
-    }
-
-    if (system_call_number == __NR_pread64) {
-      return UnsafeTrap(ForwardPreadHandler, NULL);
-    }
-    return Allow();
-  }
-
- private:
-  static intptr_t ForwardPreadHandler(const struct arch_seccomp_data& args,
-                                      void* aux) {
-    BPF_ASSERT(args.nr == __NR_pread64);
-    pread_64_was_forwarded = true;
-
-    return SandboxBPF::ForwardSyscall(args);
-  }
-
-  DISALLOW_COPY_AND_ASSIGN(TrapPread64Policy);
-};
-
-// pread(2) takes a 64 bits offset. On 32 bits systems, it will be split
-// between two arguments. In this test, we make sure that ForwardSyscall() can
-// forward it properly.
-BPF_TEST_C(SandboxBPF, Pread64, TrapPread64Policy) {
-  ScopedTemporaryFile temp_file;
-  const uint64_t kLargeOffset = (static_cast<uint64_t>(1) << 32) | 0xBEEF;
-  const char kTestString[] = "This is a test!";
-  BPF_ASSERT(FullPwrite64(
-      temp_file.fd(), kTestString, sizeof(kTestString), kLargeOffset));
-
-  char read_test_string[sizeof(kTestString)] = {0};
-  BPF_ASSERT(FullPread64(temp_file.fd(),
-                         read_test_string,
-                         sizeof(read_test_string),
-                         kLargeOffset));
-  BPF_ASSERT_EQ(0, memcmp(kTestString, read_test_string, sizeof(kTestString)));
-  BPF_ASSERT(pread_64_was_forwarded);
-}
-
-#endif  // !defined(OS_ANDROID)
-
-void* TsyncApplyToTwoThreadsFunc(void* cond_ptr) {
-  base::WaitableEvent* event = static_cast<base::WaitableEvent*>(cond_ptr);
-
-  // Wait for the main thread to signal that the filter has been applied.
-  if (!event->IsSignaled()) {
-    event->Wait();
-  }
-
-  BPF_ASSERT(event->IsSignaled());
-
-  BlacklistNanosleepPolicy::AssertNanosleepFails();
-
-  return NULL;
-}
-
-SANDBOX_TEST(SandboxBPF, Tsync) {
-  const bool supports_multi_threaded = SandboxBPF::SupportsSeccompSandbox(
-      SandboxBPF::SeccompLevel::MULTI_THREADED);
-// On Chrome OS tsync is mandatory.
-#if defined(OS_CHROMEOS)
-  if (base::SysInfo::IsRunningOnChromeOS()) {
-    BPF_ASSERT_EQ(true, supports_multi_threaded);
-  }
-// else a Chrome OS build not running on a Chrome OS device e.g. Chrome bots.
-// In this case fall through.
-#endif
-  if (!supports_multi_threaded) {
-    return;
-  }
-
-  base::WaitableEvent event(true, false);
-
-  // Create a thread on which to invoke the blocked syscall.
-  pthread_t thread;
-  BPF_ASSERT_EQ(
-      0, pthread_create(&thread, NULL, &TsyncApplyToTwoThreadsFunc, &event));
-
-  // Test that nanoseelp success.
-  const struct timespec ts = {0, 0};
-  BPF_ASSERT_EQ(0, HANDLE_EINTR(syscall(__NR_nanosleep, &ts, NULL)));
-
-  // Engage the sandbox.
-  SandboxBPF sandbox(new BlacklistNanosleepPolicy());
-  BPF_ASSERT(sandbox.StartSandbox(SandboxBPF::SeccompLevel::MULTI_THREADED));
-
-  // This thread should have the filter applied as well.
-  BlacklistNanosleepPolicy::AssertNanosleepFails();
-
-  // Signal the condition to invoke the system call.
-  event.Signal();
-
-  // Wait for the thread to finish.
-  BPF_ASSERT_EQ(0, pthread_join(thread, NULL));
-}
-
-class AllowAllPolicy : public Policy {
- public:
-  AllowAllPolicy() {}
-  ~AllowAllPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override { return Allow(); }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(AllowAllPolicy);
-};
-
-SANDBOX_DEATH_TEST(
-    SandboxBPF,
-    StartMultiThreadedAsSingleThreaded,
-    DEATH_MESSAGE(
-        ThreadHelpers::GetAssertSingleThreadedErrorMessageForTests())) {
-  base::Thread thread("sandbox.linux.StartMultiThreadedAsSingleThreaded");
-  BPF_ASSERT(thread.Start());
-
-  SandboxBPF sandbox(new AllowAllPolicy());
-  BPF_ASSERT(!sandbox.StartSandbox(SandboxBPF::SeccompLevel::SINGLE_THREADED));
-}
-
-// http://crbug.com/407357
-#if !defined(THREAD_SANITIZER)
-SANDBOX_DEATH_TEST(
-    SandboxBPF,
-    StartSingleThreadedAsMultiThreaded,
-    DEATH_MESSAGE(
-        "Cannot start sandbox; process may be single-threaded when "
-        "reported as not")) {
-  SandboxBPF sandbox(new AllowAllPolicy());
-  BPF_ASSERT(!sandbox.StartSandbox(SandboxBPF::SeccompLevel::MULTI_THREADED));
-}
-#endif  // !defined(THREAD_SANITIZER)
-
-// A stub handler for the UnsafeTrap. Never called.
-intptr_t NoOpHandler(const struct arch_seccomp_data& args, void*) {
-  return -1;
-}
-
-class UnsafeTrapWithCondPolicy : public Policy {
- public:
-  UnsafeTrapWithCondPolicy() {}
-  ~UnsafeTrapWithCondPolicy() override {}
-
-  ResultExpr EvaluateSyscall(int sysno) const override {
-    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
-    setenv(kSandboxDebuggingEnv, "t", 0);
-    Die::SuppressInfoMessages(true);
-
-    if (SandboxBPF::IsRequiredForUnsafeTrap(sysno))
-      return Allow();
-
-    switch (sysno) {
-      case __NR_uname: {
-        const Arg<uint32_t> arg(0);
-        return If(arg == 0, Allow()).Else(Error(EPERM));
-      }
-      case __NR_setgid: {
-        const Arg<uint32_t> arg(0);
-        return Switch(arg)
-            .Case(100, Error(ENOMEM))
-            .Case(200, Error(ENOSYS))
-            .Default(Error(EPERM));
-      }
-      case __NR_close:
-      case __NR_exit_group:
-      case __NR_write:
-        return Allow();
-      case __NR_getppid:
-        return UnsafeTrap(NoOpHandler, NULL);
-      default:
-        return Error(EPERM);
-    }
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(UnsafeTrapWithCondPolicy);
-};
-
-BPF_TEST_C(SandboxBPF, UnsafeTrapWithCond, UnsafeTrapWithCondPolicy) {
-  BPF_ASSERT_EQ(-1, syscall(__NR_uname, 0));
-  BPF_ASSERT_EQ(EFAULT, errno);
-
-  BPF_ASSERT_EQ(-1, syscall(__NR_uname, 1));
-  BPF_ASSERT_EQ(EPERM, errno);
-
-  BPF_ASSERT_EQ(-1, syscall(__NR_setgid, 100));
-  BPF_ASSERT_EQ(ENOMEM, errno);
-
-  BPF_ASSERT_EQ(-1, syscall(__NR_setgid, 200));
-  BPF_ASSERT_EQ(ENOSYS, errno);
-
-  BPF_ASSERT_EQ(-1, syscall(__NR_setgid, 300));
-  BPF_ASSERT_EQ(EPERM, errno);
-}
-
-}  // namespace
-
-}  // namespace bpf_dsl
-}  // namespace sandbox