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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 <dlfcn.h>
#include <signal.h>
#include <errno.h>
#include "mozilla/Types.h"
#include <stdio.h>
#include <stdlib.h>
// Signal number used to enable seccomp on each thread.
extern int gSeccompTsyncBroadcastSignum;
// 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 (aSet == NULL || aHow == SIG_UNBLOCK) {
return aRealFunc(aHow, aSet, aOldSet);
}
sigset_t newSet = *aSet;
if (sigdelset(&newSet, SIGSYS) != 0 ||
(gSeccompTsyncBroadcastSignum &&
sigdelset(&newSet, gSeccompTsyncBroadcastSignum) != 0)) {
if (aUseErrno) {
errno = ENOSYS;
return -1;
}
return ENOSYS;
}
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);
}
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