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update master-with-bazel from master branch

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BoringSSL Robot
2023-02-22 23:18:17 +00:00
parent 3b9d3420ba 85a1e2e01c
commit ef7865d3ab
3 changed files with 568 additions and 70 deletions
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src/crypto/fipsmodule/rand/rand.c
-6
View File
@@ -169,12 +169,6 @@ void CRYPTO_get_seed_entropy(uint8_t *out_entropy, size_t out_entropy_len,
} else {
CRYPTO_sysrand_for_seed(out_entropy, out_entropy_len);
}
if (boringssl_fips_break_test("CRNG")) {
// This breaks the "continuous random number generator test" defined in FIPS
// 140-2, section 4.9.2, and implemented in |rand_get_seed|.
OPENSSL_memset(out_entropy, 0, out_entropy_len);
}
}
// In passive entropy mode, entropy is supplied from outside of the module via
src/crypto/fipsmodule/rand/urandom_test.cc
+443 -61
View File
@@ -15,18 +15,24 @@
#include <gtest/gtest.h>
#include <stdlib.h>
#include <openssl/bytestring.h>
#include <openssl/ctrdrbg.h>
#include <openssl/rand.h>
#include "internal.h"
#include "getrandom_fillin.h"
#include "internal.h"
#if defined(OPENSSL_X86_64) && !defined(BORINGSSL_SHARED_LIBRARY) && \
!defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE) && defined(USE_NR_getrandom)
#if (defined(OPENSSL_X86_64) || defined(OPENSSL_AARCH64)) && \
!defined(BORINGSSL_SHARED_LIBRARY) && \
defined(OPENSSL_URANDOM) && defined(USE_NR_getrandom)
#include <elf.h>
#include <linux/random.h>
#include <sys/ptrace.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <sys/user.h>
#include "fork_detect.h"
@@ -35,6 +41,23 @@
#define PTRACE_O_EXITKILL (1 << 20)
#endif
#if defined(OPENSSL_ANDROID)
static const bool kIsAndroid = true;
#else
static const bool kIsAndroid = false;
#endif
#if defined(BORINGSSL_FIPS)
static const bool kIsFIPS = true;
#else
static const bool kIsFIPS = false;
#endif
static const bool kUsesDaemon = kIsFIPS && kIsAndroid;
// kDaemonWriteLength is the number of bytes that the entropy daemon writes.
static const size_t kDaemonWriteLength = 496;
// This test can be run with $OPENSSL_ia32cap=~0x4000000000000000 in order to
// simulate the absence of RDRAND of machines that have it.
@@ -45,6 +68,10 @@ struct Event {
kGetRandom,
kOpen,
kUrandomRead,
kSocket,
kConnect,
kSocketRead,
kSocketClose,
kAbort,
};
@@ -53,8 +80,7 @@ struct Event {
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);
filename == other.filename;
}
static Event GetRandom(size_t length, unsigned flags) {
@@ -64,7 +90,7 @@ struct Event {
return e;
}
static Event Open(const char *filename) {
static Event Open(const std::string &filename) {
Event e(Syscall::kOpen);
e.filename = filename;
return e;
@@ -76,6 +102,27 @@ struct Event {
return e;
}
static Event Socket() {
Event e(Syscall::kSocket);
return e;
}
static Event Connect() {
Event e(Syscall::kConnect);
return e;
}
static Event SocketRead(size_t length) {
Event e(Syscall::kSocketRead);
e.length = length;
return e;
}
static Event SocketClose() {
Event e(Syscall::kSocketClose);
return e;
}
static Event Abort() {
Event e(Syscall::kAbort);
return e;
@@ -90,13 +137,26 @@ struct Event {
break;
case Syscall::kOpen:
snprintf(buf, sizeof(buf), "open(%s, _)", filename);
snprintf(buf, sizeof(buf), "open(%s, _)", filename.c_str());
break;
case Syscall::kUrandomRead:
snprintf(buf, sizeof(buf), "read(urandom_fd, _, %zu)", length);
break;
case Syscall::kSocket:
return "socket(UNIX, STREAM, _)";
case Syscall::kConnect:
return "connect(sock, _, _)";
case Syscall::kSocketRead:
snprintf(buf, sizeof(buf), "read(sock_fd, _, %zu)", length);
break;
case Syscall::kSocketClose:
return "close(sock)";
case Syscall::kAbort:
return "abort()";
}
@@ -107,7 +167,7 @@ struct Event {
const Syscall type;
size_t length = 0;
unsigned flags = 0;
const char *filename = nullptr;
std::string filename;
};
static std::string ToString(const std::vector<Event> &trace) {
@@ -134,7 +194,224 @@ static const unsigned GETRANDOM_NOT_READY = 4;
static const unsigned GETRANDOM_ERROR = 8;
// Reading from /dev/urandom gives |EINVAL|.
static const unsigned URANDOM_ERROR = 16;
static const unsigned NEXT_FLAG = 32;
static const unsigned SOCKET_ERROR = 32;
static const unsigned CONNECT_ERROR = 64;
static const unsigned SOCKET_READ_ERROR = 128;
static const unsigned SOCKET_READ_SHORT = 256;
static const unsigned NEXT_FLAG = 512;
// regs_read fetches the registers of |child_pid| and writes them to |out_regs|.
// That structure will contain at least the following members:
// syscall: the syscall number, if registers were read just before entering
// one.
// args[0..2]: syscall arguments, if registers were read just before
// entering one.
// ret: the syscall return value, if registers were read just after finishing
// one.
//
// This call returns true on success and false otherwise.
static bool regs_read(struct regs *out_regs, int child_pid);
// regs_set_ret sets the return value of the system call that |child_pid| has
// just finished, to |ret|. It returns true on success and false otherwise.
static bool regs_set_ret(int child_pid, int ret);
// regs_break_syscall causes the system call that |child_pid| is about to enter
// to fail to run.
static bool regs_break_syscall(int child_pid, const struct regs *orig_regs);
#if defined(OPENSSL_X86_64)
struct regs {
uintptr_t syscall;
uintptr_t args[3];
uintptr_t ret;
struct user_regs_struct regs;
};
static bool regs_read(struct regs *out_regs, int child_pid) {
if (ptrace(PTRACE_GETREGS, child_pid, nullptr, &out_regs->regs) != 0) {
return false;
}
out_regs->syscall = out_regs->regs.orig_rax;
out_regs->ret = out_regs->regs.rax;
out_regs->args[0] = out_regs->regs.rdi;
out_regs->args[1] = out_regs->regs.rsi;
out_regs->args[2] = out_regs->regs.rdx;
return true;
}
static bool regs_set_ret(int child_pid, int ret) {
struct regs regs;
if (!regs_read(&regs, child_pid)) {
return false;
}
regs.regs.rax = ret;
return ptrace(PTRACE_SETREGS, child_pid, nullptr, &regs.regs) == 0;
}
static bool regs_break_syscall(int child_pid, const struct regs *orig_regs) {
// Replacing the syscall number with -1 doesn't work on AArch64 thus we set
// the first argument to -1, which suffices to break the syscalls that we care
// about here.
struct user_regs_struct regs;
memcpy(&regs, &orig_regs->regs, sizeof(regs));
regs.rdi = -1;
return ptrace(PTRACE_SETREGS, child_pid, nullptr, &regs) == 0;
}
#elif defined(OPENSSL_AARCH64)
struct regs {
uintptr_t syscall;
uintptr_t args[3];
uintptr_t ret;
uint64_t regs[9];
};
static bool regs_read(struct regs *out_regs, int child_pid) {
struct iovec io;
io.iov_base = out_regs->regs;
io.iov_len = sizeof(out_regs->regs);
if (ptrace(PTRACE_GETREGSET, child_pid, NT_PRSTATUS, &io) != 0) {
return false;
}
out_regs->syscall = out_regs->regs[8];
out_regs->ret = out_regs->regs[0];
out_regs->args[0] = out_regs->regs[0];
out_regs->args[1] = out_regs->regs[1];
out_regs->args[2] = out_regs->regs[2];
return true;
}
static bool regs_set(int child_pid, const struct regs *new_regs) {
struct iovec io;
io.iov_base = (void *) new_regs->regs;
io.iov_len = sizeof(new_regs->regs);
return ptrace(PTRACE_SETREGSET, child_pid, NT_PRSTATUS, &io) == 0;
}
static bool regs_set_ret(int child_pid, int ret) {
struct regs regs;
if (!regs_read(&regs, child_pid)) {
return false;
}
regs.regs[0] = ret;
return regs_set(child_pid, &regs);
}
static bool regs_break_syscall(int child_pid, const struct regs *orig_regs) {
// Replacing the syscall number with -1 doesn't work on AArch64 thus we set
// the first argument to -1, which suffices to break the syscalls that we care
// about here.
struct regs copy = *orig_regs;
copy.regs[0] = -1;
return regs_set(child_pid, orig_regs);
}
#endif
// SyscallResult is like std::optional<int>.
// TODO: use std::optional when we can use C++17.
class SyscallResult {
public:
SyscallResult &operator=(int value) {
has_value_ = true;
value_ = value;
return *this;
}
int value() const {
if (!has_value_) {
abort();
}
return value_;
}
bool has_value() const { return has_value_; }
private:
bool has_value_ = false;
int value_ = 0;
};
// memcpy_to_remote copies |n| bytes from |in_src| in the local address space,
// to |dest| in the address space of |child_pid|.
static void memcpy_to_remote(int child_pid, uint64_t dest, const void *in_src,
size_t n) {
const uint8_t *src = reinterpret_cast<const uint8_t *>(in_src);
// ptrace always works with ill-defined "words", which appear to be 64-bit
// on 64-bit systems.
#if !defined(OPENSSL_64_BIT)
#error "This code probably doesn't work"
#endif
while (n) {
const uintptr_t aligned_addr = dest & ~7;
const uintptr_t offset = dest - aligned_addr;
const size_t space = 8 - offset;
size_t todo = n;
if (todo > space) {
todo = space;
}
uint64_t word;
if (offset == 0 && todo == 8) {
word = CRYPTO_load_u64_le(src);
} else {
uint8_t bytes[8];
CRYPTO_store_u64_le(
bytes, ptrace(PTRACE_PEEKDATA, child_pid,
reinterpret_cast<void *>(aligned_addr), nullptr));
memcpy(&bytes[offset], src, todo);
word = CRYPTO_load_u64_le(bytes);
}
ASSERT_EQ(0, ptrace(PTRACE_POKEDATA, child_pid,
reinterpret_cast<void *>(aligned_addr),
reinterpret_cast<void *>(word)));
src += todo;
n -= todo;
dest += todo;
}
}
static uint8_t get_byte_from_remote(int child_pid, uint64_t ptr) {
// ptrace always works with ill-defined "words", which appear to be 64-bit
// on 64-bit systems.
#if !defined(OPENSSL_64_BIT)
#error "This code probably doesn't work"
#endif
const uintptr_t aligned_addr = ptr & ~7;
const uintptr_t offset = ptr - aligned_addr;
uint64_t word = ptrace(PTRACE_PEEKDATA, child_pid,
reinterpret_cast<void *>(aligned_addr), 0);
uint8_t bytes[8];
CRYPTO_store_u64_le(bytes, word);
return bytes[offset];
}
static std::string get_string_from_remote(int child_pid, uint64_t ptr) {
std::string ret;
for (;;) {
const uint8_t byte = get_byte_from_remote(child_pid, ptr);
if (byte == 0) {
break;
}
ret.push_back((char)byte);
ptr++;
}
return ret;
}
// 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
@@ -173,6 +450,10 @@ static void GetTrace(std::vector<Event> *out_trace, unsigned flags,
// process, if it opens it.
int urandom_fd = -1;
// sock_fd tracks the file descriptor number for the socket to the entropy
// daemon, if one is opened.
int sock_fd = -1;
for (;;) {
// Advance the child to the next system call.
ASSERT_EQ(0, ptrace(PTRACE_SYSCALL, child_pid, 0, 0));
@@ -187,64 +468,120 @@ static void GetTrace(std::vector<Event> *out_trace, unsigned flags,
// 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, &regs));
const auto syscall_number = regs.orig_rax;
struct regs regs;
ASSERT_TRUE(regs_read(&regs, child_pid));
bool is_opening_urandom = false;
// inject_error is zero to indicate that the system call should run
bool is_socket_call = false;
bool is_socket_read = false;
uint64_t socket_read_bytes = 0;
// force_result is unset 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;
// should not run and that the given value should be injected on return.
SyscallResult force_result;
switch (syscall_number) {
switch (regs.syscall) {
case __NR_getrandom:
if (flags & NO_GETRANDOM) {
inject_error = -ENOSYS;
force_result = -ENOSYS;
} else if (flags & GETRANDOM_ERROR) {
inject_error = -EINVAL;
force_result = -EINVAL;
} else if (flags & GETRANDOM_NOT_READY) {
if (regs.rdx & GRND_NONBLOCK) {
inject_error = -EAGAIN;
if (regs.args[2] & GRND_NONBLOCK) {
force_result = -EAGAIN;
}
}
out_trace->push_back(
Event::GetRandom(/*length=*/regs.rsi, /*flags=*/regs.rdx));
Event::GetRandom(/*length=*/regs.args[1], /*flags=*/regs.args[2]));
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 defined(OPENSSL_X86_64)
case __NR_open:
#endif
{
uintptr_t filename_ptr =
(regs.syscall == __NR_openat) ? regs.args[1] : regs.args[0];
const std::string filename = get_string_from_remote(child_pid, filename_ptr);
if (filename.find("/dev/__properties__/") == 0) {
// Android may try opening these files as part of SELinux support.
// They are ignored here.
} else {
out_trace->push_back(Event::Open(filename));
}
is_opening_urandom = (filename == "/dev/urandom");
if (is_opening_urandom && (flags & NO_URANDOM)) {
inject_error = -ENOENT;
force_result = -ENOENT;
}
break;
}
case __NR_read: {
const int read_fd = regs.rdi;
const int read_fd = regs.args[0];
if (urandom_fd >= 0 && urandom_fd == read_fd) {
out_trace->push_back(Event::UrandomRead(/*length=*/regs.rdx));
out_trace->push_back(Event::UrandomRead(/*length=*/regs.args[2]));
if (flags & URANDOM_ERROR) {
inject_error = -EINVAL;
force_result = -EINVAL;
}
} else if (sock_fd >= 0 && sock_fd == read_fd) {
uint64_t length = regs.args[2];
out_trace->push_back(Event::SocketRead(length));
if (flags & SOCKET_READ_ERROR) {
force_result = -EINVAL;
} else {
is_socket_read = true;
socket_read_bytes = length;
if (flags & SOCKET_READ_SHORT) {
ASSERT_GT(socket_read_bytes, 0u);
socket_read_bytes--;
flags &= ~SOCKET_READ_SHORT;
}
}
}
break;
}
case __NR_close: {
if (sock_fd >= 0 && static_cast<int>(regs.args[0]) == sock_fd) {
out_trace->push_back(Event::SocketClose());
sock_fd = -1;
}
break;
}
case __NR_socket: {
const int family = regs.args[0];
const int type = regs.args[1];
if (family == AF_UNIX && type == SOCK_STREAM) {
out_trace->push_back(Event::Socket());
is_socket_call = true;
if (flags & SOCKET_ERROR) {
force_result = -EINVAL;
}
}
break;
}
case __NR_connect: {
const int connect_fd = regs.args[0];
if (sock_fd >= 0 && connect_fd == sock_fd) {
out_trace->push_back(Event::Connect());
if (flags & CONNECT_ERROR) {
force_result = -EINVAL;
} else {
// The test system might not have an entropy daemon running so
// inject a success result.
force_result = 0;
}
}
break;
}
}
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, &regs));
if (force_result.has_value()) {
ASSERT_TRUE(regs_break_syscall(child_pid, &regs));
}
ASSERT_EQ(0, ptrace(PTRACE_SYSCALL, child_pid, 0, 0));
@@ -261,15 +598,26 @@ static void GetTrace(std::vector<Event> *out_trace, unsigned flags,
// 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, &regs));
regs.rax = inject_error;
ASSERT_EQ(0, ptrace(PTRACE_SETREGS, child_pid, nullptr, &regs));
}
if (force_result.has_value()) {
ASSERT_TRUE(regs_set_ret(child_pid, force_result.value()));
} else if (is_opening_urandom) {
ASSERT_EQ(0, ptrace(PTRACE_GETREGS, child_pid, nullptr, &regs));
urandom_fd = regs.rax;
ASSERT_TRUE(regs_read(&regs, child_pid));
urandom_fd = regs.ret;
} else if (is_socket_call) {
ASSERT_TRUE(regs_read(&regs, child_pid));
sock_fd = regs.ret;
} else if (is_socket_read) {
// Simulate a response from the entropy daemon since it might not be
// running on the current system.
uint8_t entropy[kDaemonWriteLength];
ASSERT_LE(socket_read_bytes, sizeof(entropy));
for (size_t i = 0; i < sizeof(entropy); i++) {
entropy[i] = i & 0xff;
}
memcpy_to_remote(child_pid, regs.args[1], entropy, socket_read_bytes);
ASSERT_TRUE(regs_set_ret(child_pid, socket_read_bytes));
}
}
}
@@ -281,22 +629,43 @@ static void TestFunction() {
RAND_bytes(&byte, sizeof(byte));
}
static bool have_fork_detection() {
return CRYPTO_get_fork_generation() != 0;
static bool have_fork_detection() { return CRYPTO_get_fork_generation() != 0; }
static bool AppendDaemonEvents(std::vector<Event> *events, unsigned flags) {
events->push_back(Event::Socket());
if (flags & SOCKET_ERROR) {
return false;
}
bool ret = false;
events->push_back(Event::Connect());
if (flags & CONNECT_ERROR) {
goto out;
}
events->push_back(Event::SocketRead(kDaemonWriteLength));
if (flags & SOCKET_READ_ERROR) {
goto out;
}
if (flags & SOCKET_READ_SHORT) {
events->push_back(Event::SocketRead(1));
}
ret = true;
out:
events->push_back(Event::SocketClose());
return ret;
}
// 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 getrandom_ready = false;
const bool used_daemon = kUsesDaemon && AppendDaemonEvents(&ret, flags);
// Probe for getrandom support
ret.push_back(Event::GetRandom(1, GRND_NONBLOCK));
@@ -304,7 +673,7 @@ static std::vector<Event> TestFunctionPRNGModel(unsigned flags) {
std::function<bool(bool, size_t)> sysrand;
if (flags & NO_GETRANDOM) {
if (is_fips) {
if (kIsFIPS) {
// FIPS builds require getrandom.
ret.push_back(Event::Abort());
return ret;
@@ -349,13 +718,15 @@ static std::vector<Event> TestFunctionPRNGModel(unsigned flags) {
};
}
const size_t kSeedLength = CTR_DRBG_ENTROPY_LEN * (is_fips ? 10 : 1);
const size_t kSeedLength = CTR_DRBG_ENTROPY_LEN * (kIsFIPS ? 10 : 1);
const size_t kAdditionalDataLength = 32;
if (!have_rdrand()) {
if ((!have_fork_detection() && !sysrand(true, kAdditionalDataLength)) ||
// Initialise CRNGT.
!sysrand(true, kSeedLength + (is_fips ? 16 : 0)) ||
(!used_daemon && !sysrand(true, kSeedLength + (kIsFIPS ? 16 : 0))) ||
// Personalisation draw if the daemon was used.
(used_daemon && !sysrand(false, CTR_DRBG_ENTROPY_LEN)) ||
// Second entropy draw.
(!have_fork_detection() && !sysrand(true, kAdditionalDataLength))) {
return ret;
@@ -368,7 +739,7 @@ static std::vector<Event> TestFunctionPRNGModel(unsigned flags) {
// 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) ||
!sysrand(!kIsFIPS, CTR_DRBG_ENTROPY_LEN) ||
// Second entropy draw's additional data.
(!have_fast_rdrand() && !have_fork_detection() &&
!sysrand(false, kAdditionalDataLength))) {
@@ -410,11 +781,22 @@ TEST(URandomTest, Test) {
SCOPED_TRACE(buf);
for (unsigned flags = 0; flags < NEXT_FLAG; flags++) {
if (!kUsesDaemon && (flags & (SOCKET_ERROR | CONNECT_ERROR |
SOCKET_READ_ERROR | SOCKET_READ_SHORT))) {
// These cases are meaningless unless the code will try to use the entropy
// daemon.
continue;
}
TRACE_FLAG(NO_GETRANDOM);
TRACE_FLAG(NO_URANDOM);
TRACE_FLAG(GETRANDOM_NOT_READY);
TRACE_FLAG(GETRANDOM_ERROR);
TRACE_FLAG(URANDOM_ERROR);
TRACE_FLAG(SOCKET_ERROR);
TRACE_FLAG(CONNECT_ERROR);
TRACE_FLAG(SOCKET_READ_ERROR);
TRACE_FLAG(SOCKET_READ_SHORT);
const std::vector<Event> expected_trace = TestFunctionPRNGModel(flags);
CheckInvariants(expected_trace);
@@ -445,5 +827,5 @@ int main(int argc, char **argv) {
return 0;
}
#endif // X86_64 && !SHARED_LIBRARY && !UNSAFE_DETERMINISTIC_MODE &&
// USE_NR_getrandom
#endif // (X86_64 || AARCH64) && !SHARED_LIBRARY &&
// !UNSAFE_DETERMINISTIC_MODE && USE_NR_getrandom
src/crypto/rand_extra/passive.c
+125 -3
View File
@@ -15,21 +15,143 @@
#include <openssl/ctrdrbg.h>
#include "../fipsmodule/rand/internal.h"
#include "../internal.h"
#if defined(BORINGSSL_FIPS)
#define ENTROPY_READ_LEN \
(/* last_block size */ 16 + CTR_DRBG_ENTROPY_LEN * BORINGSSL_FIPS_OVERREAD)
#if defined(OPENSSL_ANDROID)
#include <errno.h>
#include <stdatomic.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
// socket_history_t enumerates whether the entropy daemon should be contacted
// for a given entropy request. Values other than socket_not_yet_attempted are
// sticky so if the first attempt to read from the daemon fails it's assumed
// that the daemon is not present and no more attempts will be made. If the
// first attempt is successful then attempts will be made forever more.
enum socket_history_t {
// initial value, no connections to the entropy daemon have been made yet.
socket_not_yet_attempted = 0,
// reading from the entropy daemon was successful
socket_success,
// reading from the entropy daemon failed.
socket_failed,
};
static _Atomic enum socket_history_t g_socket_history =
socket_not_yet_attempted;
// DAEMON_RESPONSE_LEN is the number of bytes that the entropy daemon replies
// with.
#define DAEMON_RESPONSE_LEN 496
static_assert(ENTROPY_READ_LEN == DAEMON_RESPONSE_LEN,
"entropy daemon response length mismatch");
static int get_seed_from_daemon(uint8_t *out_entropy, size_t out_entropy_len) {
// |RAND_need_entropy| should never call this function for more than
// |DAEMON_RESPONSE_LEN| bytes.
if (out_entropy_len > DAEMON_RESPONSE_LEN) {
abort();
}
const enum socket_history_t socket_history = atomic_load(&g_socket_history);
if (socket_history == socket_failed) {
return 0;
}
int ret = 0;
const int sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (sock < 0) {
goto out;
}
struct sockaddr_un sun;
memset(&sun, 0, sizeof(sun));
sun.sun_family = AF_UNIX;
static const char kSocketPath[] = "/dev/socket/prng_seeder";
static_assert(sizeof(kSocketPath) <= UNIX_PATH_MAX,
"kSocketPath too long");
OPENSSL_memcpy(sun.sun_path, kSocketPath, sizeof(kSocketPath));
if (connect(sock, (struct sockaddr *)&sun, sizeof(sun))) {
goto out;
}
uint8_t buffer[DAEMON_RESPONSE_LEN];
size_t done = 0;
while (done < sizeof(buffer)) {
ssize_t n;
do {
n = read(sock, buffer + done, sizeof(buffer) - done);
} while (n == -1 && errno == EINTR);
if (n < 1) {
goto out;
}
done += n;
}
if (done != DAEMON_RESPONSE_LEN) {
// The daemon should always write |DAEMON_RESPONSE_LEN| bytes on every
// connection.
goto out;
}
assert(out_entropy_len <= DAEMON_RESPONSE_LEN);
OPENSSL_memcpy(out_entropy, buffer, out_entropy_len);
ret = 1;
out:
if (socket_history == socket_not_yet_attempted) {
enum socket_history_t expected = socket_history;
// If another thread has already updated |g_socket_history| then we defer
// to their value.
atomic_compare_exchange_strong(&g_socket_history, &expected,
(ret == 0) ? socket_failed : socket_success);
}
close(sock);
return ret;
}
#else
static int get_seed_from_daemon(uint8_t *out_entropy, size_t out_entropy_len) {
return 0;
}
#endif // OPENSSL_ANDROID
// RAND_need_entropy is called by the FIPS module when it has blocked because of
// a lack of entropy. This signal is used as an indication to feed it more.
void RAND_need_entropy(size_t bytes_needed) {
uint8_t buf[/* last_block size */ 16 +
CTR_DRBG_ENTROPY_LEN * BORINGSSL_FIPS_OVERREAD];
uint8_t buf[ENTROPY_READ_LEN];
size_t todo = sizeof(buf);
if (todo > bytes_needed) {
todo = bytes_needed;
}
int want_additional_input;
CRYPTO_get_seed_entropy(buf, todo, &want_additional_input);
if (get_seed_from_daemon(buf, todo)) {
want_additional_input = 1;
} else {
CRYPTO_get_seed_entropy(buf, todo, &want_additional_input);
}
if (boringssl_fips_break_test("CRNG")) {
// This breaks the "continuous random number generator test" defined in FIPS
// 140-2, section 4.9.2, and implemented in |rand_get_seed|.
OPENSSL_memset(buf, 0, todo);
}
RAND_load_entropy(buf, todo, want_additional_input);
}