ref: e86bd6a50933e99899d63de755d81b9805827a15
dir: /third_party/boringssl/src/crypto/fipsmodule/rand/urandom_test.cc/
/* Copyright (c) 2019, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <gtest/gtest.h>
#include <stdlib.h>
#include <openssl/rand.h>
#include "internal.h"
#include "getrandom_fillin.h"
#if defined(OPENSSL_X86_64) && !defined(BORINGSSL_SHARED_LIBRARY) && \
!defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE) && defined(USE_NR_getrandom)
#include <linux/random.h>
#include <sys/ptrace.h>
#include <sys/syscall.h>
#include <sys/user.h>
#include "fork_detect.h"
#if !defined(PTRACE_O_EXITKILL)
#define PTRACE_O_EXITKILL (1 << 20)
#endif
// This test can be run with $OPENSSL_ia32cap=~0x4000000000000000 in order to
// simulate the absence of RDRAND of machines that have it.
// Event represents a system call from urandom.c that is observed by the ptrace
// code in |GetTrace|.
struct Event {
enum class Syscall {
kGetRandom,
kOpen,
kUrandomRead,
kUrandomIoctl,
kAbort,
};
explicit Event(Syscall syscall) : type(syscall) {}
bool operator==(const Event &other) const {
return type == other.type && length == other.length &&
flags == other.flags &&
((filename == nullptr && other.filename == nullptr) ||
strcmp(filename, other.filename) == 0);
}
static Event GetRandom(size_t length, unsigned flags) {
Event e(Syscall::kGetRandom);
e.length = length;
e.flags = flags;
return e;
}
static Event Open(const char *filename) {
Event e(Syscall::kOpen);
e.filename = filename;
return e;
}
static Event UrandomRead(size_t length) {
Event e(Syscall::kUrandomRead);
e.length = length;
return e;
}
static Event UrandomIoctl() {
Event e(Syscall::kUrandomIoctl);
return e;
}
static Event Abort() {
Event e(Syscall::kAbort);
return e;
}
std::string String() const {
char buf[256];
switch (type) {
case Syscall::kGetRandom:
snprintf(buf, sizeof(buf), "getrandom(_, %zu, %d)", length, flags);
break;
case Syscall::kOpen:
snprintf(buf, sizeof(buf), "open(%s, _)", filename);
break;
case Syscall::kUrandomRead:
snprintf(buf, sizeof(buf), "read(urandom_fd, _, %zu)", length);
break;
case Syscall::kUrandomIoctl:
return "ioctl(urandom_fd, RNDGETENTCNT, _)";
case Syscall::kAbort:
return "abort()";
}
return std::string(buf);
}
const Syscall type;
size_t length = 0;
unsigned flags = 0;
const char *filename = nullptr;
};
static std::string ToString(const std::vector<Event> &trace) {
std::string ret;
for (const auto &event : trace) {
if (!ret.empty()) {
ret += ", ";
}
ret += event.String();
}
return ret;
}
// The following are flags to tell |GetTrace| to inject faults, using ptrace,
// into the entropy-related system calls.
// getrandom gives |ENOSYS|.
static const unsigned NO_GETRANDOM = 1;
// opening /dev/urandom fails.
static const unsigned NO_URANDOM = 2;
// getrandom always returns |EAGAIN| if given |GRNG_NONBLOCK|.
static const unsigned GETRANDOM_NOT_READY = 4;
// The ioctl on urandom returns only 255 bits of entropy the first time that
// it's called.
static const unsigned URANDOM_NOT_READY = 8;
// getrandom gives |EINVAL| unless |NO_GETRANDOM| is set.
static const unsigned GETRANDOM_ERROR = 16;
// Reading from /dev/urandom gives |EINVAL|.
static const unsigned URANDOM_ERROR = 32;
static const unsigned NEXT_FLAG = 64;
// GetTrace runs |thunk| in a forked process and observes the resulting system
// calls using ptrace. It simulates a variety of failures based on the contents
// of |flags| and records the observed events by appending to |out_trace|.
static void GetTrace(std::vector<Event> *out_trace, unsigned flags,
std::function<void()> thunk) {
const int child_pid = fork();
ASSERT_NE(-1, child_pid);
if (child_pid == 0) {
// Child process
if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0) {
perror("PTRACE_TRACEME");
_exit(1);
}
raise(SIGSTOP);
thunk();
_exit(0);
}
// Parent process
int status;
ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));
ASSERT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);
// Set options so that:
// a) the child process is killed once this process dies.
// b) System calls result in a WSTOPSIG value of (SIGTRAP | 0x80) rather
// than just SIGTRAP. (This doesn't matter here, but it's recommended
// practice so that it's distinct from the signal itself.)
ASSERT_EQ(0, ptrace(PTRACE_SETOPTIONS, child_pid, nullptr,
PTRACE_O_EXITKILL | PTRACE_O_TRACESYSGOOD))
<< strerror(errno);
// urandom_fd tracks the file descriptor number for /dev/urandom in the child
// process, if it opens it.
int urandom_fd = -1;
for (;;) {
// Advance the child to the next system call.
ASSERT_EQ(0, ptrace(PTRACE_SYSCALL, child_pid, 0, 0));
ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));
// The child may have aborted rather than made a system call.
if (WIFSTOPPED(status) && WSTOPSIG(status) == SIGABRT) {
out_trace->push_back(Event::Abort());
break;
}
// Otherwise the only valid ptrace event is a system call stop.
ASSERT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == (SIGTRAP | 0x80));
struct user_regs_struct regs;
ASSERT_EQ(0, ptrace(PTRACE_GETREGS, child_pid, nullptr, ®s));
const auto syscall_number = regs.orig_rax;
bool is_opening_urandom = false;
bool is_urandom_ioctl = false;
uintptr_t ioctl_output_addr = 0;
// inject_error is zero to indicate that the system call should run
// normally. Otherwise it's, e.g. -EINVAL, to indicate that the system call
// should not run and that error should be injected on return.
int inject_error = 0;
switch (syscall_number) {
case __NR_getrandom:
if (flags & NO_GETRANDOM) {
inject_error = -ENOSYS;
} else if (flags & GETRANDOM_ERROR) {
inject_error = -EINVAL;
} else if (flags & GETRANDOM_NOT_READY) {
if (regs.rdx & GRND_NONBLOCK) {
inject_error = -EAGAIN;
}
}
out_trace->push_back(
Event::GetRandom(/*length=*/regs.rsi, /*flags=*/regs.rdx));
break;
case __NR_openat:
case __NR_open: {
// It's assumed that any arguments to open(2) are constants in read-only
// memory and thus the pointer in the child's context will also be a
// valid pointer in our address space.
const char *filename = reinterpret_cast<const char *>(
(syscall_number == __NR_openat) ? regs.rsi : regs.rdi);
out_trace->push_back(Event::Open(filename));
is_opening_urandom = strcmp(filename, "/dev/urandom") == 0;
if (is_opening_urandom && (flags & NO_URANDOM)) {
inject_error = -ENOENT;
}
break;
}
case __NR_read: {
const int read_fd = regs.rdi;
if (urandom_fd >= 0 && urandom_fd == read_fd) {
out_trace->push_back(Event::UrandomRead(/*length=*/regs.rdx));
if (flags & URANDOM_ERROR) {
inject_error = -EINVAL;
}
}
break;
}
case __NR_ioctl: {
const int ioctl_fd = regs.rdi;
if (urandom_fd >= 0 && ioctl_fd == urandom_fd &&
regs.rsi == RNDGETENTCNT) {
out_trace->push_back(Event::UrandomIoctl());
is_urandom_ioctl = true;
ioctl_output_addr = regs.rdx;
}
}
}
if (inject_error) {
// Replace the system call number with -1 to cause the kernel to ignore
// the call. The -ENOSYS will be replaced later with the value of
// |inject_error|.
regs.orig_rax = -1;
ASSERT_EQ(0, ptrace(PTRACE_SETREGS, child_pid, nullptr, ®s));
}
ASSERT_EQ(0, ptrace(PTRACE_SYSCALL, child_pid, 0, 0));
ASSERT_EQ(child_pid, waitpid(child_pid, &status, 0));
// If the system call was exit/exit_group, the process may be terminated
// rather than have exited the system call.
if (WIFEXITED(status)) {
ASSERT_EQ(0, WEXITSTATUS(status));
return;
}
// Otherwise the next state must be a system call exit stop. This is
// indistinguishable from a system call entry, we just have to keep track
// and know that these events happen in pairs.
ASSERT_TRUE(WIFSTOPPED(status) && WSTOPSIG(status) == (SIGTRAP | 0x80));
if (inject_error) {
if (inject_error != -ENOSYS) {
ASSERT_EQ(0, ptrace(PTRACE_GETREGS, child_pid, nullptr, ®s));
regs.rax = inject_error;
ASSERT_EQ(0, ptrace(PTRACE_SETREGS, child_pid, nullptr, ®s));
}
} else if (is_opening_urandom) {
ASSERT_EQ(0, ptrace(PTRACE_GETREGS, child_pid, nullptr, ®s));
urandom_fd = regs.rax;
} else if (is_urandom_ioctl) {
// The result is the number of bits of entropy that the kernel currently
// believes that it has. urandom.c waits until 256 bits are ready.
int result = 256;
// If we are simulating urandom not being ready then we have the ioctl
// indicate one too few bits of entropy the first time it's queried.
if (flags & URANDOM_NOT_READY) {
result--;
flags &= ~URANDOM_NOT_READY;
}
// ptrace always works with ill-defined "words", which appear to be 64-bit
// on x86-64. Since the ioctl result is a 32-bit int, do a
// read-modify-write to inject the answer.
const uintptr_t aligned_addr = ioctl_output_addr & ~7;
const uintptr_t offset = ioctl_output_addr - aligned_addr;
union {
uint64_t word;
uint8_t bytes[8];
} u;
u.word = ptrace(PTRACE_PEEKDATA, child_pid,
reinterpret_cast<void *>(aligned_addr), nullptr);
memcpy(&u.bytes[offset], &result, sizeof(result));
ASSERT_EQ(0, ptrace(PTRACE_POKEDATA, child_pid,
reinterpret_cast<void *>(aligned_addr),
reinterpret_cast<void *>(u.word)));
}
}
}
// TestFunction is the function that |GetTrace| is asked to trace.
static void TestFunction() {
uint8_t byte;
RAND_bytes(&byte, sizeof(byte));
RAND_bytes(&byte, sizeof(byte));
}
static bool have_fork_detection() {
return CRYPTO_get_fork_generation() != 0;
}
// TestFunctionPRNGModel is a model of how the urandom.c code will behave when
// |TestFunction| is run. It should return the same trace of events that
// |GetTrace| will observe the real code making.
static std::vector<Event> TestFunctionPRNGModel(unsigned flags) {
#if defined(BORINGSSL_FIPS)
static const bool is_fips = true;
#else
static const bool is_fips = false;
#endif
std::vector<Event> ret;
bool urandom_probed = false;
bool getrandom_ready = false;
// Probe for getrandom support
ret.push_back(Event::GetRandom(1, GRND_NONBLOCK));
std::function<void()> wait_for_entropy;
std::function<bool(bool, size_t)> sysrand;
if (flags & NO_GETRANDOM) {
ret.push_back(Event::Open("/dev/urandom"));
if (flags & NO_URANDOM) {
ret.push_back(Event::Abort());
return ret;
}
wait_for_entropy = [&ret, &urandom_probed, flags] {
if (!is_fips || urandom_probed) {
return;
}
// Probe urandom for entropy.
ret.push_back(Event::UrandomIoctl());
if (flags & URANDOM_NOT_READY) {
// If the first attempt doesn't report enough entropy, probe
// repeatedly until it does, which will happen with the second attempt.
ret.push_back(Event::UrandomIoctl());
}
urandom_probed = true;
};
sysrand = [&ret, &wait_for_entropy, flags](bool block, size_t len) {
if (block) {
wait_for_entropy();
}
ret.push_back(Event::UrandomRead(len));
if (flags & URANDOM_ERROR) {
ret.push_back(Event::Abort());
return false;
}
return true;
};
} else {
if (flags & GETRANDOM_ERROR) {
ret.push_back(Event::Abort());
return ret;
}
getrandom_ready = (flags & GETRANDOM_NOT_READY) == 0;
wait_for_entropy = [&ret, &getrandom_ready] {
if (getrandom_ready) {
return;
}
ret.push_back(Event::GetRandom(1, GRND_NONBLOCK));
ret.push_back(Event::GetRandom(1, 0));
getrandom_ready = true;
};
sysrand = [&ret, &wait_for_entropy](bool block, size_t len) {
if (block) {
wait_for_entropy();
}
ret.push_back(Event::GetRandom(len, block ? 0 : GRND_NONBLOCK));
return true;
};
}
const size_t kSeedLength = CTR_DRBG_ENTROPY_LEN * (is_fips ? 10 : 1);
const size_t kAdditionalDataLength = 32;
if (!have_rdrand()) {
if ((!have_fork_detection() && !sysrand(true, kAdditionalDataLength)) ||
// Initialise CRNGT.
(is_fips && !sysrand(true, 16)) ||
!sysrand(true, kSeedLength) ||
// Second entropy draw.
(!have_fork_detection() && !sysrand(true, kAdditionalDataLength))) {
return ret;
}
} else if (
// First additional data. If fast RDRAND isn't available then a
// non-blocking OS entropy draw will be tried.
(!have_fast_rdrand() && !have_fork_detection() &&
!sysrand(false, kAdditionalDataLength)) ||
// Opportuntistic entropy draw in FIPS mode because RDRAND was used.
// In non-FIPS mode it's just drawn from |CRYPTO_sysrand| in a blocking
// way.
!sysrand(!is_fips, CTR_DRBG_ENTROPY_LEN) ||
// Second entropy draw's additional data.
(!have_fast_rdrand() && !have_fork_detection() &&
!sysrand(false, kAdditionalDataLength))) {
return ret;
}
return ret;
}
static void CheckInvariants(const std::vector<Event> &events) {
// If RDRAND is available then there should be no blocking syscalls in FIPS
// mode.
#if defined(BORINGSSL_FIPS)
if (have_rdrand()) {
for (const auto &event : events) {
switch (event.type) {
case Event::Syscall::kGetRandom:
if ((event.flags & GRND_NONBLOCK) == 0) {
ADD_FAILURE() << "Blocking getrandom found with RDRAND: "
<< ToString(events);
}
break;
case Event::Syscall::kUrandomIoctl:
ADD_FAILURE() << "Urandom polling found with RDRAND: "
<< ToString(events);
break;
default:
break;
}
}
}
#endif
}
// Tests that |TestFunctionPRNGModel| is a correct model for the code in
// urandom.c, at least to the limits of the the |Event| type.
TEST(URandomTest, Test) {
char buf[256];
#define TRACE_FLAG(flag) \
snprintf(buf, sizeof(buf), #flag ": %d", (flags & flag) != 0); \
SCOPED_TRACE(buf);
for (unsigned flags = 0; flags < NEXT_FLAG; flags++) {
TRACE_FLAG(NO_GETRANDOM);
TRACE_FLAG(NO_URANDOM);
TRACE_FLAG(GETRANDOM_NOT_READY);
TRACE_FLAG(URANDOM_NOT_READY);
TRACE_FLAG(GETRANDOM_ERROR);
TRACE_FLAG(URANDOM_ERROR);
const std::vector<Event> expected_trace = TestFunctionPRNGModel(flags);
CheckInvariants(expected_trace);
std::vector<Event> actual_trace;
GetTrace(&actual_trace, flags, TestFunction);
if (expected_trace != actual_trace) {
ADD_FAILURE() << "Expected: " << ToString(expected_trace)
<< "\nFound: " << ToString(actual_trace);
}
}
}
int main(int argc, char **argv) {
::testing::InitGoogleTest(&argc, argv);
if (getenv("BORINGSSL_IGNORE_MADV_WIPEONFORK")) {
CRYPTO_fork_detect_ignore_madv_wipeonfork_for_testing();
}
return RUN_ALL_TESTS();
}
#else
int main(int argc, char **argv) {
printf("PASS\n");
return 0;
}
#endif // X86_64 && !SHARED_LIBRARY && !UNSAFE_DETERMINISTIC_MODE &&
// USE_NR_getrandom