blob: 49937b519aac6a1fa6f36dd517904e01a553d94c [file] [log] [blame]
// Copyright 2015 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 <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <sched.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <sys/prctl.h>
#include <sys/ptrace.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include <unistd.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/check.h"
#include "base/macros.h"
#include "base/posix/eintr_wrapper.h"
#include "base/synchronization/waitable_event.h"
#include "base/system/sys_info.h"
#include "base/threading/thread.h"
#include "build/build_config.h"
#include "build/chromeos_buildflags.h"
#include "sandbox/linux/bpf_dsl/bpf_dsl.h"
#include "sandbox/linux/bpf_dsl/errorcode.h"
#include "sandbox/linux/bpf_dsl/linux_syscall_ranges.h"
#include "sandbox/linux/bpf_dsl/policy.h"
#include "sandbox/linux/bpf_dsl/seccomp_macros.h"
#include "sandbox/linux/seccomp-bpf/bpf_tests.h"
#include "sandbox/linux/seccomp-bpf/die.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/syscall_wrappers.h"
#include "sandbox/linux/services/thread_helpers.h"
#include "sandbox/linux/system_headers/linux_syscalls.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
#define CASES SANDBOX_BPF_DSL_CASES
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(std::make_unique<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 denylist test
class DenylistNanosleepPolicy : public Policy {
public:
DenylistNanosleepPolicy() {}
~DenylistNanosleepPolicy() 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(DenylistNanosleepPolicy);
};
BPF_TEST_C(SandboxBPF, ApplyBasicDenylistPolicy, DenylistNanosleepPolicy) {
DenylistNanosleepPolicy::AssertNanosleepFails();
}
BPF_TEST_C(SandboxBPF, UseVsyscall, DenylistNanosleepPolicy) {
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));
}
bool IsSyscallForTestHarness(int sysno) {
if (sysno == __NR_exit_group || sysno == __NR_write) {
// exit_group is special and we really need it to work.
// write() is needed for BPF_ASSERT() to report a useful error message.
return true;
}
#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
defined(UNDEFINED_SANITIZER)
// UBSan_vptr checker needs mmap, munmap, pipe, write.
// ASan and MSan don't need any of these for normal operation, but they
// require at least mmap & munmap to print a report if an error is detected.
// ASan requires sigaltstack.
if (sysno == kMMapNr || sysno == __NR_munmap || sysno == __NR_pipe ||
sysno == __NR_sigaltstack) {
return true;
}
#endif
return false;
}
// Now do a simple allowlist test
class AllowlistGetpidPolicy : public Policy {
public:
AllowlistGetpidPolicy() {}
~AllowlistGetpidPolicy() override {}
ResultExpr EvaluateSyscall(int sysno) const override {
DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
if (IsSyscallForTestHarness(sysno) || sysno == __NR_getpid) {
return Allow();
}
return Error(ENOMEM);
}
private:
DISALLOW_COPY_AND_ASSIGN(AllowlistGetpidPolicy);
};
BPF_TEST_C(SandboxBPF, ApplyBasicAllowlistPolicy, AllowlistGetpidPolicy) {
// 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 denylist 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 DenylistNanosleepTrapPolicy : public Policy {
public:
explicit DenylistNanosleepTrapPolicy(int* aux) : aux_(aux) {}
~DenylistNanosleepTrapPolicy() 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(DenylistNanosleepTrapPolicy);
};
BPF_TEST(SandboxBPF,
BasicDenylistWithSigsys,
DenylistNanosleepTrapPolicy,
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);
};
// Depending on DCHECK being enabled or not the test may create some output.
// Therefore explicitly specify the death test to allow some noise.
BPF_DEATH_TEST_C(SandboxBPF,
StackingPolicy,
DEATH_SUCCESS_ALLOW_NOISE(),
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(std::make_unique<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 (IsSyscallForTestHarness(sysno)) {
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 (IsSyscallForTestHarness(syscall_number)) {
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::Registry()->EnableUnsafeTraps() == false);
setenv(kSandboxDebuggingEnv, "", 1);
SANDBOX_ASSERT(Trap::Registry()->EnableUnsafeTraps() == false);
setenv(kSandboxDebuggingEnv, "t", 1);
SANDBOX_ASSERT(Trap::Registry()->EnableUnsafeTraps() == 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, nullptr);
}
// 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, nullptr);
}
#if !defined(ADDRESS_SANITIZER)
// ASan does not allow changing the signal handler for SIGBUS, and treats it as
// a fatal signal.
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, nullptr) == 0);
kill(getpid(), 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);
}
#endif // !defined(ADDRESS_SANITIZER)
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, nullptr));
BPF_ASSERT(!sigprocmask(SIG_BLOCK, nullptr, &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);
}
// 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;
FALLTHROUGH;
#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 Switch(option)
.CASES((PR_SET_DUMPABLE, PR_GET_DUMPABLE), Allow())
.Default(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(nullptr);
} 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 = nullptr;
} 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 = nullptr;
} 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());
}
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());
}
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());
}
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 Switch(flags)
.CASES((kGlibcCloneMask, (kBaseAndroidCloneMask | CLONE_DETACHED),
kBaseAndroidCloneMask),
Allow())
.Default(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(Not(HasAllBits(flags, kMandatoryFlags)),
Trap(PthreadTrapHandler,
"Missing mandatory CLONE_XXX flags "
"when creating new thread"))
.ElseIf(AllOf(Not(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 nullptr;
}
static void PthreadTest() {
// Attempt to start a joinable thread. This should succeed.
pthread_t thread;
int thread_ran = 0;
BPF_ASSERT(!pthread_create(&thread, nullptr, ThreadFnc, &thread_ran));
BPF_ASSERT(!pthread_join(thread, nullptr));
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
#if defined(__GLIBC__)
#define PTRACE_GETREGS static_cast<enum __ptrace_request>(12)
#else
#define PTRACE_GETREGS 12
#endif // defined(__GLIBC__)
#endif // !defined(PTRACE_GETREGS)
#endif // defined(__aarch64__)
#if defined(__aarch64__)
#ifndef PTRACE_SETREGS
#if defined(__GLIBC__)
#define PTRACE_SETREGS static_cast<enum __ptrace_request>(13)
#else
#define PTRACE_SETREGS 13
#endif // defined(__GLIBC__)
#endif // !defined(PTRACE_SETREGS)
#endif // defined(__aarch64__)
// 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.
#if !defined(__arm__) && !defined(__aarch64__) && !defined(__mips__)
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);
#else
SECCOMP_PT_SYSCALL(*regs) = syscall_number;
return 0;
#endif
}
#endif
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.");
#elif 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.");
#else
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(std::make_unique<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));
}
#endif
}
// 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, nullptr);
}
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());
DenylistNanosleepPolicy::AssertNanosleepFails();
return nullptr;
}
SANDBOX_TEST(SandboxBPF, Tsync) {
const bool supports_multi_threaded = SandboxBPF::SupportsSeccompSandbox(
SandboxBPF::SeccompLevel::MULTI_THREADED);
// On Chrome OS tsync is mandatory.
#if BUILDFLAG(IS_CHROMEOS_ASH)
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(base::WaitableEvent::ResetPolicy::MANUAL,
base::WaitableEvent::InitialState::NOT_SIGNALED);
// Create a thread on which to invoke the blocked syscall.
pthread_t thread;
BPF_ASSERT_EQ(
0, pthread_create(&thread, nullptr, &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(std::make_unique<DenylistNanosleepPolicy>());
BPF_ASSERT(sandbox.StartSandbox(SandboxBPF::SeccompLevel::MULTI_THREADED));
// This thread should have the filter applied as well.
DenylistNanosleepPolicy::AssertNanosleepFails();
// Signal the condition to invoke the system call.
event.Signal();
// Wait for the thread to finish.
BPF_ASSERT_EQ(0, pthread_join(thread, nullptr));
}
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(std::make_unique<AllowAllPolicy>());
BPF_ASSERT(!sandbox.StartSandbox(SandboxBPF::SeccompLevel::SINGLE_THREADED));
}
// 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();
if (IsSyscallForTestHarness(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:
return Allow();
case __NR_getppid:
return UnsafeTrap(NoOpHandler, nullptr);
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