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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
#ifndef OPENVPN_COMMON_USERGROUP_H
#define OPENVPN_COMMON_USERGROUP_H
#include <pwd.h>
#include <grp.h>
#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <string>
#include <openvpn/common/platform.hpp>
#ifdef OPENVPN_PLATFORM_LINUX
#include <sys/prctl.h>
#endif
#include <openvpn/common/size.hpp>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/to_string.hpp>
#include <openvpn/common/strerror.hpp>
namespace openvpn {
// NOTE: -- SetUserGroup object does not own passwd and group
// objects, therefore *pw and *gr can change under us.
class SetUserGroup
{
public:
OPENVPN_EXCEPTION(user_group_err);
SetUserGroup(const std::string &user, const std::string &group, const bool strict)
: SetUserGroup(user.empty() ? nullptr : user.c_str(),
group.empty() ? nullptr : group.c_str(),
strict)
{
}
SetUserGroup(const char *user, const char *group, const bool strict)
: pw(nullptr),
gr(nullptr)
{
if (user)
{
pw = ::getpwnam(user);
if (!pw && strict)
OPENVPN_THROW(user_group_err, "user lookup failed for '" << user << '\'');
user_name = user;
}
if (group)
{
gr = ::getgrnam(group);
if (!gr && strict)
OPENVPN_THROW(user_group_err, "group lookup failed for '" << group << '\'');
group_name = group;
}
}
virtual ~SetUserGroup() = default;
const std::string &user() const
{
return user_name;
}
const std::string &group() const
{
return group_name;
}
virtual void pre_thread() const
{
}
virtual void post_thread() const
{
}
virtual void activate() const
{
do_setgid_setgroups();
do_setuid();
retain_core_dumps();
}
void chown(const std::string &fn) const
{
if (pw && gr)
{
const int status = ::chown(fn.c_str(), uid(), gid());
if (status < 0)
{
const int eno = errno;
OPENVPN_THROW(user_group_err, "chown " << user_name << '.' << group_name << ' ' << fn << " : " << strerror_str(eno));
}
}
}
void chown(const int fd, const std::string &title) const
{
if (pw && gr)
{
const int status = ::fchown(fd, uid(), gid());
if (status < 0)
{
const int eno = errno;
OPENVPN_THROW(user_group_err, "chown " << user_name << '.' << group_name << ' ' << title << " : " << strerror_str(eno));
}
}
}
void invalidate()
{
pw = nullptr;
gr = nullptr;
}
uid_t uid() const
{
if (pw)
return pw->pw_uid;
else
return -1;
}
gid_t gid() const
{
if (gr)
return gr->gr_gid;
else
return -1;
}
bool uid_defined() const
{
return bool(pw);
}
bool gid_defined() const
{
return bool(gr);
}
bool defined() const
{
return uid_defined() && gid_defined();
}
protected:
void do_setgid_setgroups() const
{
if (gr)
{
if (::setgid(gr->gr_gid))
{
const int eno = errno;
OPENVPN_THROW(user_group_err, "setgid failed for group '" << group_name << "': " << strerror_str(eno));
}
gid_t gr_list[1];
gr_list[0] = gr->gr_gid;
if (::setgroups(1, gr_list))
{
const int eno = errno;
OPENVPN_THROW(user_group_err, "setgroups failed for group '" << group_name << "': " << strerror_str(eno));
}
OPENVPN_LOG("GID set to '" << group_name << '\'');
}
}
void do_setuid() const
{
if (pw)
{
if (::setuid(pw->pw_uid))
{
const int eno = errno;
OPENVPN_THROW(user_group_err, "setuid failed for user '" << user_name << "': " << strerror_str(eno));
}
OPENVPN_LOG("UID set to '" << user_name << '\'');
}
}
void retain_core_dumps() const
{
#ifdef OPENVPN_PLATFORM_LINUX
// retain core dumpability after setgid/setuid
if (gr || pw)
{
if (::prctl(PR_SET_DUMPABLE, 1))
{
const int eno = errno;
OPENVPN_THROW(user_group_err, "SetUserGroup prctl PR_SET_DUMPABLE fail: " << strerror_str(eno));
}
}
#endif
}
std::string user_name;
std::string group_name;
struct passwd *pw;
struct group *gr;
};
} // namespace openvpn
#endif
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