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/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <cstring>
#include <stdexcept>
#ifdef HAVE_LIBCAP
#include <sys/capability.h>
#include <sys/prctl.h>
#endif
#include "capabilities.hh"
#include "misc.hh"
bool dropCapabilities([[maybe_unused]] std::set<std::string> capabilitiesToKeep)
{
#ifdef HAVE_LIBCAP
cap_t caps = cap_get_proc();
if (caps != nullptr) {
cap_clear(caps);
if (!capabilitiesToKeep.empty()) {
std::vector<cap_value_t> toKeep;
toKeep.reserve(capabilitiesToKeep.size());
for (const auto& capToKeep : capabilitiesToKeep) {
cap_value_t value;
int res = cap_from_name(capToKeep.c_str(), &value);
if (res != 0) {
cap_free(caps);
throw std::runtime_error("Unable to convert capability name '" + capToKeep + "': " + stringerror());
}
toKeep.push_back(value);
}
if (cap_set_flag(caps, CAP_EFFECTIVE, toKeep.size(), toKeep.data(), CAP_SET) != 0) {
cap_free(caps);
throw std::runtime_error("Unable to set effective flag capabilities: " + stringerror());
}
if (cap_set_flag(caps, CAP_PERMITTED, toKeep.size(), toKeep.data(), CAP_SET) != 0) {
cap_free(caps);
throw std::runtime_error("Unable to set permitted flag capabilities: " + stringerror());
}
}
if (cap_set_proc(caps) != 0) {
cap_free(caps);
if (errno == EPERM) {
return false;
}
throw std::runtime_error("Unable to drop capabilities: " + stringerror());
}
cap_free(caps);
return true;
}
#endif /* HAVE_LIBCAP */
return false;
}
bool dropCapabilitiesAfterSwitchingIDs()
{
#ifdef HAVE_LIBCAP
#ifdef PR_SET_KEEPCAPS
if (prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) == 0) {
return true;
}
#endif /* PR_SET_KEEPCAPS */
return false;
#else
return false;
#endif /* HAVE_LIBCAP */
}
bool keepCapabilitiesAfterSwitchingIDs()
{
#ifdef HAVE_LIBCAP
#ifdef PR_SET_KEEPCAPS
if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == 0) {
return true;
}
#endif /* PR_SET_KEEPCAPS */
return false;
#else
return false;
#endif /* HAVE_LIBCAP */
}
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