-/* Copyright (c) 2007-2021. The SimGrid Team. All rights reserved. */
+/* Copyright (c) 2007-2023. The SimGrid Team. All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
* under the terms of the license (GNU LGPL) which comes with this package. */
#include "src/mc/remote/CheckerSide.hpp"
+#include "src/mc/explo/Exploration.hpp"
+#include "src/mc/explo/LivenessChecker.hpp"
+#include "src/mc/sosp/RemoteProcessMemory.hpp"
+#include "xbt/system_error.hpp"
+
+#ifdef __linux__
+#include <sys/prctl.h>
+#endif
+
+#include <boost/tokenizer.hpp>
#include <csignal>
+#include <fcntl.h>
+#include <sys/ptrace.h>
#include <sys/wait.h>
-namespace simgrid {
-namespace mc {
+#ifdef __linux__
+#define WAITPID_CHECKED_FLAGS __WALL
+#else
+#define WAITPID_CHECKED_FLAGS 0
+#endif
+
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_checkerside, mc, "MC communication with the application");
+
+static simgrid::config::Flag<std::string> _sg_mc_setenv{
+ "model-check/setenv", "Extra environment variables to pass to the child process (ex: 'AZE=aze;QWE=qwe').", "",
+ [](std::string_view value) {
+ xbt_assert(value.empty() || value.find('=', 0) != std::string_view::npos,
+ "The 'model-check/setenv' parameter must be like 'AZE=aze', but it does not contain an equal sign.");
+ }};
+
+namespace simgrid::mc {
+
+XBT_ATTRIB_NORETURN static void run_child_process(int socket, const std::vector<char*>& args, bool need_ptrace)
+{
+ /* On startup, simix_global_init() calls simgrid::mc::Client::initialize(), which checks whether the MC_ENV_SOCKET_FD
+ * env variable is set. If so, MC mode is assumed, and the client is setup from its side
+ */
+
+#ifdef __linux__
+ // Make sure we do not outlive our parent
+ sigset_t mask;
+ sigemptyset(&mask);
+ xbt_assert(sigprocmask(SIG_SETMASK, &mask, nullptr) >= 0, "Could not unblock signals");
+ xbt_assert(prctl(PR_SET_PDEATHSIG, SIGHUP) == 0, "Could not PR_SET_PDEATHSIG");
+#endif
+
+ // Remove CLOEXEC to pass the socket to the application
+ int fdflags = fcntl(socket, F_GETFD, 0);
+ xbt_assert(fdflags != -1 && fcntl(socket, F_SETFD, fdflags & ~FD_CLOEXEC) != -1,
+ "Could not remove CLOEXEC for socket");
+
+ setenv(MC_ENV_SOCKET_FD, std::to_string(socket).c_str(), 1);
+ if (need_ptrace)
+ setenv("MC_NEED_PTRACE", "1", 1);
+
+ /* Setup the tokenizer that parses the cfg:model-check/setenv parameter */
+ using Tokenizer = boost::tokenizer<boost::char_separator<char>>;
+ boost::char_separator<char> semicol_sep(";");
+ boost::char_separator<char> equal_sep("=");
+ Tokenizer token_vars(_sg_mc_setenv.get(), semicol_sep); /* Iterate over all FOO=foo parts */
+ for (const auto& token : token_vars) {
+ std::vector<std::string> kv;
+ Tokenizer token_kv(token, equal_sep);
+ for (const auto& t : token_kv) /* Iterate over 'FOO' and then 'foo' in that 'FOO=foo' */
+ kv.push_back(t);
+ xbt_assert(kv.size() == 2, "Parse error on 'model-check/setenv' value %s. Does it contain an equal sign?",
+ token.c_str());
+ XBT_INFO("setenv '%s'='%s'", kv[0].c_str(), kv[1].c_str());
+ setenv(kv[0].c_str(), kv[1].c_str(), 1);
+ }
+
+ /* And now, exec the child process */
+ int i = 1;
+ while (args[i] != nullptr && args[i][0] == '-')
+ i++;
+
+ xbt_assert(args[i] != nullptr,
+ "Unable to find a binary to exec on the command line. Did you only pass config flags?");
+
+ execvp(args[i], args.data() + i);
+ XBT_CRITICAL("The model-checked process failed to exec(%s): %s.\n"
+ " Make sure that your binary exists on disk and is executable.",
+ args[i], strerror(errno));
+ if (strchr(args[i], '=') != nullptr)
+ XBT_CRITICAL("If you want to pass environment variables to the application, please use --cfg=model-check/setenv:%s",
+ args[i]);
+
+ xbt_die("Aborting now.");
+}
+
+static void wait_application_process(pid_t pid)
+{
+ XBT_DEBUG("Waiting for the model-checked process");
+ int status;
+
+ // The model-checked process SIGSTOP itself to signal it's ready:
+ xbt_assert(waitpid(pid, &status, WAITPID_CHECKED_FLAGS) == pid && WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP,
+ "Could not wait model-checked process");
+
+ errno = 0;
+#ifdef __linux__
+ ptrace(PTRACE_SETOPTIONS, pid, nullptr, PTRACE_O_TRACEEXIT);
+ ptrace(PTRACE_CONT, pid, 0, 0);
+#elif defined BSD
+ ptrace(PT_CONTINUE, pid, (caddr_t)1, 0);
+#else
+#error "no ptrace equivalent coded for this platform"
+#endif
+ xbt_assert(errno == 0,
+ "Ptrace does not seem to be usable in your setup (errno: %d). "
+ "If you run from within a docker, adding `--cap-add SYS_PTRACE` to the docker line may help. "
+ "If it does not help, please report this bug.",
+ errno);
+}
-void CheckerSide::start(void (*handler)(int, short, void*), ModelChecker* mc)
+void CheckerSide::setup_events(bool socket_only)
{
auto* base = event_base_new();
base_.reset(base);
- auto* socket_event = event_new(base, get_channel().get_socket(), EV_READ | EV_PERSIST, handler, mc);
- event_add(socket_event, nullptr);
- socket_event_.reset(socket_event);
+ socket_event_ = event_new(
+ base, get_channel().get_socket(), EV_READ | EV_PERSIST,
+ [](evutil_socket_t, short events, void* arg) {
+ auto checker = static_cast<simgrid::mc::CheckerSide*>(arg);
+ if (events == EV_READ) {
+ std::array<char, MC_MESSAGE_LENGTH> buffer;
+ ssize_t size = recv(checker->get_channel().get_socket(), buffer.data(), buffer.size(), MSG_DONTWAIT);
+ if (size == -1) {
+ XBT_ERROR("Channel::receive failure: %s", strerror(errno));
+ if (errno != EAGAIN)
+ throw simgrid::xbt::errno_error();
+ }
- auto* signal_event = event_new(base, SIGCHLD, EV_SIGNAL | EV_PERSIST, handler, mc);
- event_add(signal_event, nullptr);
- signal_event_.reset(signal_event);
+ if (size == 0) // The app closed the socket. It must be dead by now.
+ checker->handle_waitpid();
+ else if (not checker->handle_message(buffer.data(), size))
+ checker->break_loop();
+ } else {
+ xbt_die("Unexpected event");
+ }
+ },
+ this);
+ event_add(socket_event_, nullptr);
+
+ if (socket_only) {
+ signal_event_ = nullptr;
+ } else {
+ signal_event_ = event_new(
+ base, SIGCHLD, EV_SIGNAL | EV_PERSIST,
+ [](evutil_socket_t sig, short events, void* arg) {
+ auto checker = static_cast<simgrid::mc::CheckerSide*>(arg);
+ if (events == EV_SIGNAL) {
+ if (sig == SIGCHLD)
+ checker->handle_waitpid();
+ else
+ xbt_die("Unexpected signal: %d", sig);
+ } else {
+ xbt_die("Unexpected event");
+ }
+ },
+ this);
+ event_add(signal_event_, nullptr);
+ }
+}
+
+/* When this constructor is called, no other checkerside exists */
+CheckerSide::CheckerSide(const std::vector<char*>& args, bool need_memory_info) : running_(true)
+{
+ // Create an AF_LOCAL socketpair used for exchanging messages between the model-checker process (ancestor)
+ // and the application process (child)
+ int sockets[2];
+ xbt_assert(socketpair(AF_LOCAL, SOCK_SEQPACKET | SOCK_CLOEXEC, 0, sockets) != -1, "Could not create socketpair: %s",
+ strerror(errno));
+
+ pid_ = fork();
+ xbt_assert(pid_ >= 0, "Could not fork application process");
+
+ if (pid_ == 0) { // Child
+ ::close(sockets[1]);
+ run_child_process(sockets[0], args, need_memory_info); // We need ptrace if we need the mem info
+ DIE_IMPOSSIBLE;
+ }
+
+ // Parent (model-checker):
+ ::close(sockets[0]);
+ channel_.reset_socket(sockets[1]);
+
+ setup_events(false); /* we need a signal handler too */
+ if (need_memory_info) {
+ // setup ptrace and sync with the app
+ wait_application_process(pid_);
+
+ // Request the initial memory on need
+ channel_.send(MessageType::NEED_MEMINFO);
+ s_mc_message_need_meminfo_reply_t answer;
+ ssize_t answer_size = channel_.receive(answer);
+ xbt_assert(answer_size != -1, "Could not receive message");
+ xbt_assert(answer.type == MessageType::NEED_MEMINFO_REPLY,
+ "The received message is not the NEED_MEMINFO_REPLY I was expecting but of type %s",
+ to_c_str(answer.type));
+ xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
+
+ /* We now have enough info to create the memory address space */
+ remote_memory_ = std::make_unique<simgrid::mc::RemoteProcessMemory>(pid_, answer.mmalloc_default_mdp);
+ }
+
+ wait_for_requests();
+}
+
+CheckerSide::~CheckerSide()
+{
+ event_del(socket_event_);
+ event_free(socket_event_);
+ if (signal_event_ != nullptr) {
+ event_del(signal_event_);
+ event_free(signal_event_);
+ }
+}
+
+/* This constructor is called when cloning a checkerside to get its application to fork away */
+CheckerSide::CheckerSide(int socket, CheckerSide* child_checker)
+ : channel_(socket), running_(true), child_checker_(child_checker)
+{
+ setup_events(true); // We already have a signal handled in that case
+
+ s_mc_message_int_t answer;
+ ssize_t s = get_channel().receive(answer);
+ xbt_assert(s != -1, "Could not receive answer to FORK_REPLY");
+ xbt_assert(s == sizeof answer, "Broken message (size=%zd; expected %zu)", s, sizeof answer);
+ xbt_assert(answer.type == MessageType::FORK_REPLY,
+ "Received unexpected message %s (%i); expected MessageType::FORK_REPLY (%i)", to_c_str(answer.type),
+ (int)answer.type, (int)MessageType::FORK_REPLY);
+ pid_ = answer.value;
+
+ wait_for_requests();
}
-void CheckerSide::dispatch()
+std::unique_ptr<CheckerSide> CheckerSide::clone(int master_socket)
+{
+ s_mc_message_int_t m = {};
+ m.type = MessageType::FORK;
+ m.value = getpid();
+ xbt_assert(get_channel().send(m) == 0, "Could not ask the app to fork on need.");
+
+ int sock = accept(master_socket, nullptr /* I know who's connecting*/, nullptr);
+ xbt_assert(sock > 0, "Cannot accept the incomming connection of the forked app: %s.", strerror(errno));
+
+ return std::make_unique<CheckerSide>(sock, this);
+}
+
+void CheckerSide::finalize(bool terminate_asap)
+{
+ s_mc_message_int_t m = {};
+ m.type = MessageType::FINALIZE;
+ m.value = terminate_asap;
+ xbt_assert(get_channel().send(m) == 0, "Could not ask the app to finalize on need");
+
+ s_mc_message_t answer;
+ ssize_t s = get_channel().receive(answer);
+ xbt_assert(s != -1, "Could not receive answer to FINALIZE");
+ xbt_assert(s == sizeof answer, "Broken message (size=%zd; expected %zu)", s, sizeof answer);
+ xbt_assert(answer.type == MessageType::FINALIZE_REPLY,
+ "Received unexpected message %s (%i); expected MessageType::FINALIZE_REPLY (%i)", to_c_str(answer.type),
+ (int)answer.type, (int)MessageType::FINALIZE_REPLY);
+}
+
+void CheckerSide::dispatch_events() const
{
event_base_dispatch(base_.get());
}
-void CheckerSide::break_loop()
+void CheckerSide::break_loop() const
{
event_base_loopbreak(base_.get());
}
-} // namespace mc
-} // namespace simgrid
+bool CheckerSide::handle_message(const char* buffer, ssize_t size)
+{
+ s_mc_message_t base_message;
+ xbt_assert(size >= (ssize_t)sizeof(base_message), "Broken message. Got only %ld bytes.", size);
+ memcpy(&base_message, buffer, sizeof(base_message));
+
+ switch (base_message.type) {
+ case MessageType::IGNORE_HEAP: {
+ if (remote_memory_ != nullptr) {
+ s_mc_message_ignore_heap_t message;
+ xbt_assert(size == sizeof(message), "Broken message");
+ memcpy(&message, buffer, sizeof(message));
+
+ IgnoredHeapRegion region;
+ region.block = message.block;
+ region.fragment = message.fragment;
+ region.address = message.address;
+ region.size = message.size;
+ get_remote_memory()->ignore_heap(region);
+ } else {
+ XBT_INFO("Ignoring a IGNORE_HEAP message because we don't need to introspect memory.");
+ }
+ break;
+ }
+
+ case MessageType::UNIGNORE_HEAP: {
+ if (remote_memory_ != nullptr) {
+ s_mc_message_ignore_memory_t message;
+ xbt_assert(size == sizeof(message), "Broken message");
+ memcpy(&message, buffer, sizeof(message));
+ get_remote_memory()->unignore_heap((void*)message.addr, message.size);
+ } else {
+ XBT_INFO("Ignoring an UNIGNORE_HEAP message because we don't need to introspect memory.");
+ }
+ break;
+ }
+
+ case MessageType::IGNORE_MEMORY: {
+ if (remote_memory_ != nullptr) {
+ s_mc_message_ignore_memory_t message;
+ xbt_assert(size == sizeof(message), "Broken message");
+ memcpy(&message, buffer, sizeof(message));
+ get_remote_memory()->ignore_region(message.addr, message.size);
+ } else {
+ XBT_INFO("Ignoring an IGNORE_MEMORY message because we don't need to introspect memory.");
+ }
+ break;
+ }
+
+ case MessageType::STACK_REGION: {
+ if (remote_memory_ != nullptr) {
+ s_mc_message_stack_region_t message;
+ xbt_assert(size == sizeof(message), "Broken message");
+ memcpy(&message, buffer, sizeof(message));
+ get_remote_memory()->stack_areas().push_back(message.stack_region);
+ } else {
+ XBT_INFO("Ignoring an STACK_REGION message because we don't need to introspect memory.");
+ }
+ break;
+ }
+
+ case MessageType::REGISTER_SYMBOL: {
+ s_mc_message_register_symbol_t message;
+ xbt_assert(size == sizeof(message), "Broken message");
+ memcpy(&message, buffer, sizeof(message));
+ xbt_assert(not message.callback, "Support for client-side function proposition is not implemented.");
+ XBT_DEBUG("Received symbol: %s", message.name.data());
+
+ LivenessChecker::automaton_register_symbol(*get_remote_memory(), message.name.data(), remote((int*)message.data));
+ break;
+ }
+
+ case MessageType::WAITING:
+ return false;
+
+ case MessageType::ASSERTION_FAILED:
+ Exploration::get_instance()->report_assertion_failure();
+ break;
+
+ default:
+ xbt_die("Unexpected message from the application");
+ }
+ return true;
+}
+
+void CheckerSide::wait_for_requests()
+{
+ XBT_DEBUG("Resume the application");
+ if (get_channel().send(MessageType::CONTINUE) != 0)
+ throw xbt::errno_error();
+ clear_memory_cache();
+
+ if (running())
+ dispatch_events();
+}
+
+void CheckerSide::clear_memory_cache()
+{
+ if (remote_memory_)
+ remote_memory_->clear_cache();
+}
+
+void CheckerSide::handle_dead_child(int status)
+{
+ // From PTRACE_O_TRACEEXIT:
+#ifdef __linux__
+ if (status >> 8 == (SIGTRAP | (PTRACE_EVENT_EXIT << 8))) {
+ unsigned long eventmsg;
+ xbt_assert(ptrace(PTRACE_GETEVENTMSG, pid_, 0, &eventmsg) != -1, "Could not get exit status");
+ status = static_cast<int>(eventmsg);
+ if (WIFSIGNALED(status)) {
+ this->terminate();
+ Exploration::get_instance()->report_crash(status);
+ }
+ }
+#endif
+
+ // We don't care about non-lethal signals, just reinject them:
+ if (WIFSTOPPED(status)) {
+ XBT_DEBUG("Stopped with signal %i", (int)WSTOPSIG(status));
+ errno = 0;
+#ifdef __linux__
+ ptrace(PTRACE_CONT, pid_, 0, WSTOPSIG(status));
+#elif defined BSD
+ ptrace(PT_CONTINUE, pid_, (caddr_t)1, WSTOPSIG(status));
+#endif
+ xbt_assert(errno == 0, "Could not PTRACE_CONT: %s", strerror(errno));
+ }
+
+ else if (WIFSIGNALED(status)) {
+ this->terminate();
+ Exploration::get_instance()->report_crash(status);
+ } else if (WIFEXITED(status)) {
+ XBT_DEBUG("Child process is over");
+ this->terminate();
+ }
+}
+
+void CheckerSide::handle_waitpid()
+{
+ XBT_DEBUG("Check for wait event");
+
+ if (child_checker_ == nullptr) { // Wait directly
+ int status;
+ pid_t pid;
+ while ((pid = waitpid(-1, &status, WNOHANG)) != 0) {
+ if (pid == -1) {
+ if (errno == ECHILD) { // No more children:
+ xbt_assert(not this->running(), "Inconsistent state");
+ break;
+ } else {
+ xbt_die("Could not wait for pid: %s", strerror(errno));
+ }
+ }
+
+ if (pid == get_pid())
+ handle_dead_child(status);
+ }
+
+ } else { // Ask our proxy to wait for us
+
+ s_mc_message_int_t request = {};
+ request.type = MessageType::WAIT_CHILD;
+ request.value = pid_;
+ xbt_assert(child_checker_->get_channel().send(request) == 0,
+ "Could not ask my child to waitpid its child for me: %s", strerror(errno));
+
+ s_mc_message_int_t answer;
+ ssize_t answer_size = child_checker_->get_channel().receive(answer);
+ xbt_assert(answer_size != -1, "Could not receive message");
+ xbt_assert(answer.type == MessageType::WAIT_CHILD_REPLY,
+ "The received message is not the WAIT_CHILD_REPLY I was expecting but of type %s",
+ to_c_str(answer.type));
+ xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
+ handle_dead_child(answer.value);
+ }
+}
+} // namespace simgrid::mc
