1 files changed, 75 insertions, 0 deletions
diff --git a/capabilities.cc b/capabilities.cc
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--- /dev/null
+++ b/capabilities.cc
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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>
+#endif
+
+#include "capabilities.hh"
+#include "misc.hh"
+
+void dropCapabilities(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);
+       throw std::runtime_error("Unable to drop capabilities: " + stringerror());
+     }
+
+     cap_free(caps);
+   }
+#endif /* HAVE_LIBCAP */
+}