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/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtAddOn.JsonStream module of the Qt.
**
** $QT_BEGIN_LICENSE:LGPL$
** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qunixsandboxprocess_p.h"
#include <sys/stat.h>
#include <errno.h>
#if defined(Q_OS_LINUX)
#include <sys/types.h>
#include <unistd.h>
#include <grp.h>
#include <sys/prctl.h>
#if !defined(Q_OS_LINUX_ANDROID)
#include <sys/capability.h>
#endif
#include <signal.h>
#endif
#include <pwd.h>
#include <QDebug>
QT_BEGIN_NAMESPACE_PROCESSMANAGER
/*!
\class QUnixSandboxProcess
\brief The QUnixSandboxProcess class sets the UID and GID on a Unix process
\inmodule QtProcessManager
*/
/*!
Construct a UnixProcessBackend with \a uid, \a gid, \a umask, \a dropCapabilities,
and optional \a parent.
*/
QUnixSandboxProcess::QUnixSandboxProcess(qint64 uid, qint64 gid, qint64 umask, qint64 dropCapabilities, QObject *parent)
: QProcess(parent)
, m_uid(uid)
, m_gid(gid)
, m_umask(umask)
, m_dropCapabilities(dropCapabilities)
{
}
/*!
Set up child process UID, GID, and supplementary group list.
Also set the child process to be in its own process group and fix the umask
and the POSIX capabilities to drop.
Under Linux, the child process will be set to receive a SIGTERM signal
when the parent process dies.
The creator of the child process may have specified a UID and/or a
GID for the child process. Here are the currently supported cases:
\table
\header
\li UID
\li GID
\li Result
\row
\li Invalid
\li Invalid
\li The child runs with the same UID and GID as the parent
\row
\li \b{Valid}
\li Invalid
\li The UID is looked up from \c{/etc/passwd}. If it is
found, the UID and GID of the child are set from the values
found. The supplemetary group list is initialized from
\c{/etc/groups}. If the UID is not found, the child is killed.
\row
\li Invalid
\li \b{Valid}
\li The child's GID is set. The supplementary
group list is cleared.
\row
\li \b{Valid}
\li \b{Valid}
\li The child's UID and GID are set to the values specified. If
they happen to match the values in \c{/etc/passwd}
the supplementary group list is set as well. If they don't
match, the supplementary group list is cleared.
\endtable
In the "normal" use case, the calling process will set the UID and the
child process will automatically get the correct GID and
supplementary group list by looking up information from \c{/etc/passwd}.
In the "alternative" use cases, you can set both the UID/GID or you
can set just the GID. These cases are designed for running
processes that have a UID and/or GID that doesn't exist in the
\c{/etc/passwd} database.
*/
void QUnixSandboxProcess::setupChildProcess()
{
#if defined(Q_OS_LINUX)
if (::prctl(PR_SET_PDEATHSIG, SIGTERM))
qFatal("QUnixSandboxProcess prctl unable to set death signal: %s", strerror(errno));
#endif
if (::setpgid(0,0))
qFatal("QUnixSandboxProcess setpgid(): %s", strerror(errno));
if (m_umask >= 0) {
mode_t umask = m_umask;
::umask(umask);
}
if (m_uid >= 0) {
errno = 0;
struct passwd *pw = ::getpwuid(m_uid);
if (!pw && errno)
qFatal("QUnixSandboxProcess getpwuid(%ld): %s", (long) m_uid, strerror(errno));
gid_t gid = m_gid;
if (m_gid < 0) { // UID set, GID unset
if (!pw)
qFatal("QUnixSandboxProcess did not find uid %ld in database", (long) m_uid);
if (::initgroups(pw->pw_name, pw->pw_gid))
qFatal("QUnixSandboxProcess initgroups(%s, %ld): %s", pw->pw_name, (long) pw->pw_gid, strerror(errno));
gid = pw->pw_gid;
}
else { // UID set, GID set
if (pw && pw->pw_gid == m_gid) {
if (::initgroups(pw->pw_name, pw->pw_gid))
qFatal("QUnixSandboxProcess initgroups(%s, %ld): %s", pw->pw_name, (long) pw->pw_gid, strerror(errno));
} else {
if (::setgroups(0, NULL))
qFatal("QUnixSandboxProcess setgroups(0,NULL): %s", strerror(errno));
}
}
if (::setgid(gid))
qFatal("QUnixSandboxProcess setgid(%ld): %s", (long) gid, strerror(errno));
if (::setuid(m_uid))
qFatal("QUnixSandboxProcess setuid(%ld): %s", (long) m_uid, strerror(errno));
}
else if (m_gid >=0) { // UID unset, GID set
if (::setgroups(0, NULL))
qFatal("QUnixSandboxProcess setgroups(0,NULL): %s", strerror(errno));
if (::setgid(m_gid))
qFatal("QUnixSandboxProcess setgid(%ld): %s", (long) m_gid, strerror(errno));
}
#if defined (Q_OS_LINUX) && !defined(Q_OS_LINUX_ANDROID)
if (m_dropCapabilities >= 0) {
cap_t caps;
cap_value_t cap_list[63];
quint64 bit = 1;
int n = 0;
for (int i = 0; i < 63; ++i) {
if (m_dropCapabilities & (bit << i))
cap_list[n++] = i;
}
caps = ::cap_get_proc();
::cap_set_flag(caps, CAP_EFFECTIVE, n, cap_list, CAP_CLEAR);
::cap_set_flag(caps, CAP_INHERITABLE, n, cap_list, CAP_CLEAR);
::cap_set_flag(caps, CAP_PERMITTED, n, cap_list, CAP_CLEAR);
if (::cap_set_proc(caps) == -1)
qFatal("QUnixSandboxProcess cap_set_proc (%ld): %s", (long) m_dropCapabilities, strerror(errno));
::cap_free(caps);
}
#endif
}
#include "moc_qunixsandboxprocess_p.cpp"
QT_END_NAMESPACE_PROCESSMANAGER
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