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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "mozilla/Assertions.h"
#include "mozilla/Atomics.h"
#include "mozilla/Types.h"
#include <dlfcn.h>
#include <signal.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/inotify.h>
#ifdef MOZ_X11
# include <X11/Xlib.h>
#endif
// Signal number used to enable seccomp on each thread.
extern mozilla::Atomic<int> gSeccompTsyncBroadcastSignum;
static bool SigSetNeedsFixup(const sigset_t* aSet) {
int tsyncSignum = gSeccompTsyncBroadcastSignum;
return aSet != nullptr &&
(sigismember(aSet, SIGSYS) ||
(tsyncSignum != 0 && sigismember(aSet, tsyncSignum)));
}
static void SigSetFixup(sigset_t* aSet) {
int tsyncSignum = gSeccompTsyncBroadcastSignum;
int rv = sigdelset(aSet, SIGSYS);
MOZ_RELEASE_ASSERT(rv == 0);
if (tsyncSignum != 0) {
rv = sigdelset(aSet, tsyncSignum);
MOZ_RELEASE_ASSERT(rv == 0);
}
}
// This file defines a hook for sigprocmask() and pthread_sigmask().
// Bug 1176099: some threads block SIGSYS signal which breaks our seccomp-bpf
// sandbox. To avoid this, we intercept the call and remove SIGSYS.
//
// ENOSYS indicates an error within the hook function itself.
static int HandleSigset(int (*aRealFunc)(int, const sigset_t*, sigset_t*),
int aHow, const sigset_t* aSet, sigset_t* aOldSet,
bool aUseErrno) {
if (!aRealFunc) {
if (aUseErrno) {
errno = ENOSYS;
return -1;
}
return ENOSYS;
}
// Avoid unnecessary work
if (aHow == SIG_UNBLOCK || !SigSetNeedsFixup(aSet)) {
return aRealFunc(aHow, aSet, aOldSet);
}
sigset_t newSet = *aSet;
SigSetFixup(&newSet);
return aRealFunc(aHow, &newSet, aOldSet);
}
extern "C" MOZ_EXPORT int sigprocmask(int how, const sigset_t* set,
sigset_t* oldset) {
static auto sRealFunc =
(int (*)(int, const sigset_t*, sigset_t*))dlsym(RTLD_NEXT, "sigprocmask");
return HandleSigset(sRealFunc, how, set, oldset, true);
}
extern "C" MOZ_EXPORT int pthread_sigmask(int how, const sigset_t* set,
sigset_t* oldset) {
static auto sRealFunc = (int (*)(int, const sigset_t*, sigset_t*))dlsym(
RTLD_NEXT, "pthread_sigmask");
return HandleSigset(sRealFunc, how, set, oldset, false);
}
extern "C" MOZ_EXPORT int sigaction(int signum, const struct sigaction* act,
struct sigaction* oldact) {
static auto sRealFunc =
(int (*)(int, const struct sigaction*, struct sigaction*))dlsym(
RTLD_NEXT, "sigaction");
if (!sRealFunc) {
errno = ENOSYS;
return -1;
}
if (act == nullptr || !SigSetNeedsFixup(&act->sa_mask)) {
return sRealFunc(signum, act, oldact);
}
struct sigaction newact = *act;
SigSetFixup(&newact.sa_mask);
return sRealFunc(signum, &newact, oldact);
}
extern "C" MOZ_EXPORT int inotify_init(void) { return inotify_init1(0); }
extern "C" MOZ_EXPORT int inotify_init1(int flags) {
errno = ENOSYS;
return -1;
}
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