libreoffice-online/common/SigUtil.cpp
Ashod Nakashian 5c9988f2e3 wsd: faster jail setup via bind-mount
loolmount now works and supports mounting and
unmounting, plus numerous improvements,
refactoring, logging, etc..  When enabled,
binding improves the jail setup time by anywhere
from 2x to orders of magnitude (in docker, f.e.).

A new config entry mount_jail_tree controls
whether mounting is used or the old method of
linking/copying of jail contents. It is set to
true by default and falls back to linking/copying.
A test mount is done when the setting is enabled,
and if mounting fails, it's disabled to avoid noise.

Temporarily disabled for unit-tests until we can
cleanup lingering mounts after Jenkins aborts our
build job. In a future patch we will have mount/jail
cleanup as part of make.

The network/system files in /etc that need frequent
refreshing are now updated in systemplate to make
their most recent version available in the jails.
These files can change during the course of loolwsd
lifetime, and are unlikely to be updated in
systemplate after installation at all. We link to
them in the systemplate/etc directory, and if that
fails, we copy them before forking each kit
instance to have the latest.

This reworks the approach used to bind-mount the
jails and the templates such that the total is
now down to only three mounts: systemplate, lo, tmp.

As now systemplate and lotemplate are shared, they
must be mounted as readonly, this means that user/
must now be moved into tmp/user/ which is writable.

The mount-points must be recursive, because we mount
lo/ within the mount-point of systemplate (which is
the root of the jail). But because we (re)bind
recursively, and because both systemplate and
lotemplate are mounted for each jails, we need to
make them unbindable, so they wouldn't multiply the
mount-points for each jails (an explosive growth!)
Contrarywise, we don't want the mount-points to
be shared, because we don't expect to add/remove
mounts after a jail is created.

The random temp directory is now created and set
correctly, plus many logging and other improvements.

Change-Id: Iae3fda5e876cf47d2cae6669a87b5b826a8748df
Reviewed-on: https://gerrit.libreoffice.org/c/online/+/92829
Tested-by: Jenkins
Tested-by: Jenkins CollaboraOffice <jenkinscollaboraoffice@gmail.com>
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
2020-07-01 05:42:43 +02:00

384 lines
9.5 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#include <config.h>
#include "SigUtil.hpp"
#if !defined(__ANDROID__)
# include <execinfo.h>
#endif
#include <csignal>
#include <sys/poll.h>
#include <sys/uio.h>
#include <unistd.h>
#include <atomic>
#include <cassert>
#include <chrono>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <mutex>
#include <sstream>
#include <string>
#include <thread>
#include <Socket.hpp>
#include "Common.hpp"
#include "Log.hpp"
#ifndef IOS
static std::atomic<bool> TerminationFlag(false);
static std::atomic<bool> DumpGlobalState(false);
static std::atomic<bool> ShutdownRequestFlag(false);
namespace SigUtil
{
bool getShutdownRequestFlag()
{
return ShutdownRequestFlag;
}
bool getTerminationFlag()
{
return TerminationFlag;
}
void setTerminationFlag()
{
TerminationFlag = true;
}
#if MOBILEAPP
void resetTerminationFlag()
{
TerminationFlag = false;
}
#endif
#if !MOBILEAPP
bool getDumpGlobalState()
{
return DumpGlobalState;
}
void resetDumpGlobalState()
{
DumpGlobalState = false;
}
/// This traps the signal-handler so we don't _Exit
/// while dumping stack trace. It's re-entrant.
/// Used to safely increment and decrement the signal-handler trap.
class SigHandlerTrap
{
static std::atomic<int> SigHandling;
public:
SigHandlerTrap() { ++SigHandlerTrap::SigHandling; }
~SigHandlerTrap() { --SigHandlerTrap::SigHandling; }
/// Check that we have exclusive access to the trap.
/// Otherwise, there is another signal in progress.
bool isExclusive() const
{
// Return true if we are alone.
return SigHandlerTrap::SigHandling == 1;
}
/// Wait for the trap to clear.
static void wait()
{
while (SigHandlerTrap::SigHandling)
sleep(1);
}
};
std::atomic<int> SigHandlerTrap::SigHandling;
void waitSigHandlerTrap()
{
SigHandlerTrap::wait();
}
const char *signalName(const int signo)
{
switch (signo)
{
#define CASE(x) case SIG##x: return "SIG" #x
CASE(HUP);
CASE(INT);
CASE(QUIT);
CASE(ILL);
CASE(ABRT);
CASE(FPE);
CASE(KILL);
CASE(SEGV);
CASE(PIPE);
CASE(ALRM);
CASE(TERM);
CASE(USR1);
CASE(USR2);
CASE(CHLD);
CASE(CONT);
CASE(STOP);
CASE(TSTP);
CASE(TTIN);
CASE(TTOU);
CASE(BUS);
#ifdef SIGPOLL
CASE(POLL);
#endif
CASE(PROF);
CASE(SYS);
CASE(TRAP);
CASE(URG);
CASE(VTALRM);
CASE(XCPU);
CASE(XFSZ);
#ifdef SIGEMT
CASE(EMT);
#endif
#ifdef SIGSTKFLT
CASE(STKFLT);
#endif
#if defined(SIGIO) && SIGIO != SIGPOLL
CASE(IO);
#endif
#ifdef SIGPWR
CASE(PWR);
#endif
#ifdef SIGLOST
CASE(LOST);
#endif
CASE(WINCH);
#if defined(SIGINFO) && SIGINFO != SIGPWR
CASE(INFO);
#endif
#undef CASE
default:
return "unknown";
}
}
static
void handleTerminationSignal(const int signal)
{
bool hardExit = false;
const char *domain;
if (!ShutdownRequestFlag && (signal == SIGINT || signal == SIGTERM))
{
domain = " Shutdown signal received: ";
ShutdownRequestFlag = true;
}
else if (!TerminationFlag)
{
domain = " Forced-Termination signal received: ";
TerminationFlag = true;
}
else
{
domain = " ok, ok - hard-termination signal received: ";
hardExit = true;
}
Log::signalLogPrefix();
Log::signalLog(domain);
Log::signalLog(signalName(signal));
Log::signalLog("\n");
if (!hardExit)
SocketPoll::wakeupWorld();
else
{
::signal (signal, SIG_DFL);
::raise (signal);
}
}
void requestShutdown()
{
ShutdownRequestFlag = true;
SocketPoll::wakeupWorld();
}
void setTerminationSignals()
{
struct sigaction action;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
action.sa_handler = handleTerminationSignal;
sigaction(SIGINT, &action, nullptr);
sigaction(SIGTERM, &action, nullptr);
sigaction(SIGQUIT, &action, nullptr);
sigaction(SIGHUP, &action, nullptr);
}
static char FatalGdbString[256] = { '\0' };
static
void handleFatalSignal(const int signal)
{
SigHandlerTrap guard;
bool bReEntered = !guard.isExclusive();
Log::signalLogPrefix();
// Heap corruption can re-enter through backtrace.
if (bReEntered)
Log::signalLog(" Fatal double signal received: ");
else
Log::signalLog(" Fatal signal received: ");
Log::signalLog(signalName(signal));
struct sigaction action;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
action.sa_handler = SIG_DFL;
sigaction(signal, &action, nullptr);
if (!bReEntered)
dumpBacktrace();
// let default handler process the signal
::raise(signal);
}
void dumpBacktrace()
{
#if !defined(__ANDROID__)
Log::signalLog("\nBacktrace ");
Log::signalLogNumber(getpid());
Log::signalLog(":\n");
const int maxSlots = 50;
void *backtraceBuffer[maxSlots];
const int numSlots = backtrace(backtraceBuffer, maxSlots);
if (numSlots > 0)
{
backtrace_symbols_fd(backtraceBuffer, numSlots, STDERR_FILENO);
}
#else
LOG_SYS("Backtrace not available on Android.");
#endif
if (std::getenv("LOOL_DEBUG"))
{
Log::signalLog(FatalGdbString);
LOG_ERR("Sleeping 30s to allow debugging.");
sleep(30);
}
}
void setFatalSignals()
{
struct sigaction action;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
action.sa_handler = handleFatalSignal;
sigaction(SIGSEGV, &action, nullptr);
sigaction(SIGBUS, &action, nullptr);
sigaction(SIGABRT, &action, nullptr);
sigaction(SIGILL, &action, nullptr);
sigaction(SIGFPE, &action, nullptr);
// Prepare this in advance just in case.
std::ostringstream stream;
stream << "\nERROR: Fatal signal! Attach debugger with:\n"
<< "sudo gdb --pid=" << getpid() << "\n or \n"
<< "sudo gdb --q --n --ex 'thread apply all backtrace full' --batch --pid="
<< getpid() << '\n';
std::string streamStr = stream.str();
assert (sizeof (FatalGdbString) > strlen(streamStr.c_str()) + 1);
strncpy(FatalGdbString, streamStr.c_str(), sizeof(FatalGdbString)-1);
FatalGdbString[sizeof(FatalGdbString)-1] = '\0';
}
static
void handleUserSignal(const int signal)
{
Log::signalLogPrefix();
Log::signalLog(" User signal received: ");
Log::signalLog(signalName(signal));
Log::signalLog("\n");
if (signal == SIGUSR1)
{
DumpGlobalState = true;
SocketPoll::wakeupWorld();
}
}
static
void handleDebuggerSignal(const int /*signal*/)
{}
void setUserSignals()
{
struct sigaction action;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
action.sa_handler = handleUserSignal;
sigaction(SIGUSR1, &action, nullptr);
}
void setDebuggerSignal()
{
struct sigaction action;
sigemptyset(&action.sa_mask);
action.sa_flags = 0;
action.sa_handler = handleDebuggerSignal;
sigaction(SIGUSR1, &action, nullptr);
}
/// Kill the given pid with SIGKILL as default. Returns true when the pid does not exist any more.
bool killChild(const int pid, const int signal)
{
LOG_DBG("Killing PID: " << pid);
// Don't kill anything in the fuzzer case: pid == 0 would kill the fuzzer itself, and
// killing random other processes is not a great idea, either.
if (Util::isFuzzing() || kill(pid, signal) == 0 || errno == ESRCH)
{
// Killed or doesn't exist.
return true;
}
LOG_SYS("Error when trying to kill PID: " << pid << ". Will wait for termination.");
const int sleepMs = 50;
const int count = std::max(CHILD_REBALANCE_INTERVAL_MS / sleepMs, 2);
for (int i = 0; i < count; ++i)
{
if (kill(pid, 0) == 0 || errno == ESRCH)
{
// Doesn't exist.
return true;
}
std::this_thread::sleep_for(std::chrono::milliseconds(sleepMs));
}
return false;
}
#endif // !MOBILEAPP
}
#endif // !IOS
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */