Process::cb_ret_t Backend::handleSignal(ProcControlAPI::Event::const_ptr ev) {
Process::cb_ret_t retState = Process::cbDefault;
// Shut down non-recoverable
EventSignal::const_ptr signal = ev->getEventSignal();
Process::const_ptr curProcess = ev->getProcess();
Thread::const_ptr curThread = ev->getThread();
int signum = signal->getSignal();
set<DysectAPI::Event*> subscribedEvents;
if(Async::getSignalSubscribers(subscribedEvents, signum)) {
set<DysectAPI::Event*>::iterator eventIter = subscribedEvents.begin();
for(;eventIter != subscribedEvents.end(); eventIter++) {
Err::verbose(true, "Handling signal..");
DysectAPI::Event* dysectEvent = *eventIter;
handleEvent(curProcess, curThread, dysectEvent);
}
} else {
Err::info(true, "No handlers for signal %d", signum);
}
if(signal) {
switch(signum) {
// Fatal signals
case SIGINT:
case SIGQUIT:
case SIGILL:
case SIGTRAP:
case SIGSEGV:
case SIGFPE:
Err::info(true, "Non recoverable signal %d - stopping process", signum);
retState = Process::cbProcStop;
// Enqueue termination
Backend::enqueueDetach(curProcess);
break;
// Non-fatal signals
default:
retState = Process::cbDefault;
break;
}
}
return retState;
}
PCEventHandler::RTSignalResult
PCEventHandler::handleRTSignal(EventSignal::const_ptr ev, PCProcess *evProc) const {
// Check whether the signal was sent from the RT library by checking variables
// in the library -- if we cannot be determine whether this signal came from
// the RT library, assume it did not.
if( evProc->runtime_lib.size() == 0 ) return NotRTSignal;
Address sync_event_breakpoint_addr = evProc->getRTEventBreakpointAddr();
Address sync_event_id_addr = evProc->getRTEventIdAddr();
Address sync_event_arg1_addr = evProc->getRTEventArg1Addr();
int breakpoint = 0;
int status = 0;
Address arg1 = 0;
int zero = 0;
// Check that all addresses could be determined
if( sync_event_breakpoint_addr == 0
|| sync_event_id_addr == 0
|| sync_event_arg1_addr == 0 )
{
return NotRTSignal;
}
// First, check breakpoint...
if( !evProc->readDataWord((const void *)sync_event_breakpoint_addr,
sizeof(int), &breakpoint, false) ) return NotRTSignal;
switch(breakpoint) {
case NoRTBreakpoint:
proccontrol_printf("%s[%d]: signal is not RT library signal\n",
FILE__, __LINE__);
return NotRTSignal;
case NormalRTBreakpoint:
case SoftRTBreakpoint:
// More work to do
break;
default:
proccontrol_printf("%s[%d]: invalid value for RT library breakpoint variable\n",
FILE__, __LINE__);
return NotRTSignal;
}
// Make sure we don't get this event twice....
if( !evProc->writeDataWord((void *)sync_event_breakpoint_addr, sizeof(int), &zero) ) {
proccontrol_printf("%s[%d]: failed to reset RT library breakpoint variable\n",
FILE__, __LINE__);
return NotRTSignal;
}
// Get the type of the event
if( !evProc->readDataWord((const void *)sync_event_id_addr, sizeof(int),
&status, false) ) return NotRTSignal;
if( status == DSE_undefined ) {
proccontrol_printf("%s[%d]: signal is not RT library signal\n", FILE__, __LINE__);
return NotRTSignal;
}
// get runtime library arg1 address
if( !evProc->readDataWord((const void *)sync_event_arg1_addr,
evProc->getAddressWidth(), &arg1, false) ) {
proccontrol_printf("%s[%d]: failed to read RT library arg1 variable\n",
FILE__, __LINE__);
return NotRTSignal;
}
if( !isValidRTSignal(ev->getSignal(), (RTBreakpointVal) breakpoint, arg1, status) ) return NotRTSignal;
BPatch_process *bproc = BPatch::bpatch->getProcessByPid(evProc->getPid());
if( bproc == NULL ) {
proccontrol_printf("%s[%d]: no corresponding BPatch_process for process %d\n",
FILE__, __LINE__, evProc->getPid());
return ErrorInDecoding;
}
// See pcEventHandler.h (SYSCALL HANDLING) for a description of what
// is going on here
Event::ptr newEvt;
switch(status) {
case DSE_forkEntry:
proccontrol_printf("%s[%d]: decoded forkEntry, arg = %lx\n",
FILE__, __LINE__, arg1);
if (PCEventMuxer::useBreakpoint(EventType(EventType::Pre, EventType::Fork)))
{
proccontrol_printf("%s[%d]: reporting fork entry event to BPatch layer\n",
FILE__, __LINE__);
BPatch::bpatch->registerForkingProcess(evProc->getPid(), NULL);
}
break;
case DSE_forkExit:
proccontrol_printf("%s[%d]: decoded forkExit, arg = %lx\n",
FILE__, __LINE__, arg1);
if (PCEventMuxer::useBreakpoint(EventType(EventType::Post, EventType::Fork))) {
proccontrol_printf("%s[%d]: reporting fork exit event to ProcControlAPI\n",
FILE__, __LINE__);
newEvt = Event::ptr(new EventFork(EventType::Pre, (Dyninst::PID)arg1));
}
break;
case DSE_execEntry:
proccontrol_printf("%s[%d]: decoded execEntry, arg = %lx\n",
FILE__, __LINE__, arg1);
// For now, just note that the process is going to exec
evProc->setExecing(true);
break;
case DSE_execExit:
proccontrol_printf("%s[%d]: decoded execExit, arg = %lx\n",
FILE__, __LINE__, arg1);
// This is not currently used by Dyninst internals for anything
// We rely on ProcControlAPI for this and it should be impossible
// to get this via a breakpoint
return ErrorInDecoding;
case DSE_exitEntry:
proccontrol_printf("%s[%d]: decoded exitEntry, arg = %lx\n",
FILE__, __LINE__, arg1);
/* Entry of exit, used for the callback. We need to trap before
the process has actually exited as the callback may want to
read from the process */
if (PCEventMuxer::useBreakpoint(EventType(EventType::Pre, EventType::Exit))) {
if (PCEventMuxer::useCallback(EventType(EventType::Pre, EventType::Exit))) {
proccontrol_printf("%s[%d]: reporting exit entry event to ProcControlAPI\n",
FILE__, __LINE__);
newEvt = Event::ptr(new EventExit(EventType::Pre, (int)arg1));
}
else {
proccontrol_printf("%s[%d]: reporting exit entry event to BPatch layer\n",
FILE__, __LINE__);
evProc->triggerNormalExit((int)arg1);
}
}
break;
case DSE_loadLibrary:
proccontrol_printf("%s[%d]: decoded loadLibrary (error), arg = %lx\n",
FILE__, __LINE__, arg1);
// This is no longer used
return ErrorInDecoding;
case DSE_lwpExit:
proccontrol_printf("%s[%d]: decoded lwpExit (error), arg = %lx\n",
FILE__, __LINE__, arg1);
// This is not currently used on any platform
return ErrorInDecoding;
case DSE_snippetBreakpoint:
proccontrol_printf("%s[%d]: decoded snippetBreak, arg = %lx\n",
FILE__, __LINE__, arg1);
bproc->setLastSignal(ev->getSignal());
evProc->setDesiredProcessState(PCProcess::ps_stopped);
break;
case DSE_stopThread:
proccontrol_printf("%s[%d]: decoded stopThread, arg = %lx\n",
FILE__, __LINE__, arg1);
bproc->setLastSignal(ev->getSignal());
if( !handleStopThread(evProc, arg1) ) {
proccontrol_printf("%s[%d]: failed to handle stopped thread event\n",
FILE__, __LINE__);
return ErrorInDecoding;
}
break;
case DSE_dynFuncCall:
proccontrol_printf("%s[%d]: decoded dynamic callsite event, arg = %lx\n",
FILE__, __LINE__, arg1);
if( !handleDynFuncCall(evProc, bproc, arg1) ) {
proccontrol_printf("%s[%d]: failed to handle dynamic callsite event\n",
FILE__, __LINE__);
return ErrorInDecoding;
}
break;
case DSE_userMessage:
proccontrol_printf("%s[%d]: decoded user message event, arg = %lx\n",
FILE__, __LINE__, arg1);
if( !handleUserMessage(evProc, bproc, arg1) ) {
proccontrol_printf("%s[%d]: failed to handle user message event\n",
FILE__, __LINE__);
return ErrorInDecoding;
}
break;
default:
return NotRTSignal;
}
// Behavior common to all syscalls
if( newEvt != NULL ) {
// Report the event to ProcControlAPI, make sure process remains stopped
evProc->setReportingEvent(true);
newEvt->setProcess(ev->getProcess());
newEvt->setThread(ev->getThread());
// In the callback thread, the process and thread are stopped
newEvt->setSyncType(Event::sync_process);
newEvt->setUserEvent(true);
ProcControlAPI::mbox()->enqueue(newEvt);
}
return IsRTSignal;
}
bool PCEventHandler::handleSignal(EventSignal::const_ptr ev, PCProcess *evProc) const {
proccontrol_printf("%s[%d]: thread %d/%d received signal %d\n",
FILE__, __LINE__, ev->getProcess()->getPid(), ev->getThread()->getLWP(),
ev->getSignal());
// Check whether it is a signal from the RT library (note: this will internally
// handle any entry/exit to syscalls and make the necessary up calls as appropriate)
RTSignalResult result = handleRTSignal(ev, evProc);
if( result == ErrorInDecoding ) {
proccontrol_printf("%s[%d]: failed to determine whether signal came from RT library\n",
FILE__, __LINE__);
return false;
}
if( result == IsRTSignal ) {
// handleRTSignal internally does all handling for the events in order to keep
// related logic in one place
proccontrol_printf("%s[%d]: signal came from RT library\n", FILE__, __LINE__);
return true;
}
// check if windows access violation, defensive mode, and write permissions.
// unprotect pages if necessary.
if (evProc->getHybridMode() == BPatch_defensiveMode
&& ev->isFirst()
&& ev->getCause() == EventSignal::WriteViolation) {
malware_cerr << "Write to protected address 0x" << std::hex
<< ev->getAddress() << std::dec << std::endl;
Address addr = ev->getAddress();
mapped_object* obj = evProc->findObject(addr);
// retry finding object by its original address.
if (obj == NULL && evProc->isMemoryEmulated()) {
std::pair<bool, Address> trans =
evProc->getMemEm()->translateBackwards(addr);
if (trans.first) {
addr = trans.second;
obj = evProc->findObject(addr);
}
}
// change permissions if we can find this originally writable region
if (obj != NULL) {
SymtabAPI::Region* reg =
obj->parse_img()->getObject()->findEnclosingRegion(addr - obj->codeBase());
if (reg != NULL && (reg->getRegionPermissions() == SymtabAPI::Region::RP_RW
|| reg->getRegionPermissions() == SymtabAPI::Region::RP_RWX)) {
// change back permissions.
PCProcess::PCMemPerm rights(true, true, true);
evProc->changeMemoryProtections(
addr - (addr % evProc->getMemoryPageSize()),
evProc->getMemoryPageSize(),
rights /* PAGE_EXECUTE_READWRITE */ ,
false);
return true;
}
}
// else fall through to forwarding.
}
bool shouldForwardSignal = true;
BPatch_process *bpproc = BPatch::bpatch->getProcessByPid(evProc->getPid());
if( bpproc == NULL ) {
proccontrol_printf("%s[%d]: failed to locate BPatch_process for process %d\n",
FILE__, __LINE__, evProc->getPid());
}
if( shouldStopForSignal(ev->getSignal()) ) {
proccontrol_printf("%s[%d]: signal %d is stop signal, leaving process stopped\n",
FILE__, __LINE__, ev->getSignal());
evProc->setDesiredProcessState(PCProcess::ps_stopped);
shouldForwardSignal = false;
}
// Tell the BPatch layer we received a signal
if( bpproc ) bpproc->setLastSignal(ev->getSignal());
// Debugging only
if( (dyn_debug_proccontrol || dyn_debug_crash)
&& isCrashSignal(ev->getSignal()) ) {
fprintf(stderr, "Caught crash signal %d for thread %d/%d\n",
ev->getSignal(), ev->getProcess()->getPid(), ev->getThread()->getLWP());
RegisterPool regs;
if( !ev->getThread()->getAllRegisters(regs) ) {
fprintf(stderr, "%s[%d]: Failed to get registers for crash\n", FILE__, __LINE__);
}else{
fprintf(stderr, "Registers at crash:\n");
for(RegisterPool::iterator i = regs.begin(); i != regs.end(); i++) {
fprintf(stderr, "\t%s = 0x%lx\n", (*i).first.name().c_str(), (*i).second);
}
}
// Dump the stacks
pdvector<pdvector<Frame> > stackWalks;
evProc->walkStacks(stackWalks);
for (unsigned walk_iter = 0; walk_iter < stackWalks.size(); walk_iter++) {
fprintf(stderr, "Stack for pid %d, lwpid %d\n",
stackWalks[walk_iter][0].getProc()->getPid(),
stackWalks[walk_iter][0].getThread()->getLWP());
for( unsigned i = 0; i < stackWalks[walk_iter].size(); i++ ) {
cerr << stackWalks[walk_iter][i] << endl;
}
}
// User specifies the action, defaults to core dump
// (which corresponds to standard Dyninst behavior)
if(dyn_debug_crash_debugger) {
if( string(dyn_debug_crash_debugger).find("gdb") != string::npos ) {
evProc->launchDebugger();
// If for whatever reason this fails, fall back on sleep
dyn_debug_crash_debugger = const_cast<char *>("sleep");
}
if( string(dyn_debug_crash_debugger) == string("sleep") ) {
static volatile int spin = 1;
while(spin) sleep(1);
}
}
}
if(shouldForwardSignal ) {
// Now, explicitly set the signal to be delivered to the process
ev->setThreadSignal(ev->getSignal());
}
return true;
}