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/*
SSSD
Kerberos 5 Backend Module -- Utilities
Authors:
Sumit Bose <sbose@redhat.com>
Copyright (C) 2009 Red Hat
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
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, see <http://www.gnu.org/licenses/>.
*/
#include "util/util.h"
#include <grp.h>
errno_t become_user(uid_t uid, gid_t gid)
{
uid_t cuid;
int ret;
DEBUG(SSSDBG_FUNC_DATA, ("Trying to become user [%d][%d].\n", uid, gid));
/* skip call if we already are the requested user */
cuid = geteuid();
if (uid == cuid) {
DEBUG(SSSDBG_FUNC_DATA, ("Already user [%d].\n", uid));
return EOK;
}
/* drop supplmentary groups first */
ret = setgroups(0, NULL);
if (ret == -1) {
ret = errno;
DEBUG(SSSDBG_CRIT_FAILURE,
("setgroups failed [%d][%s].\n", ret, strerror(ret)));
return ret;
}
/* change gid so that root cannot be regained (changes saved gid too) */
ret = setresgid(gid, gid, gid);
if (ret == -1) {
ret = errno;
DEBUG(SSSDBG_CRIT_FAILURE,
("setresgid failed [%d][%s].\n", ret, strerror(ret)));
return ret;
}
/* change uid so that root cannot be regained (changes saved uid too) */
/* this call also takes care of dropping CAP_SETUID, so this is a PNR */
ret = setresuid(uid, uid, uid);
if (ret == -1) {
ret = errno;
DEBUG(SSSDBG_CRIT_FAILURE,
("setresuid failed [%d][%s].\n", ret, strerror(ret)));
return ret;
}
return EOK;
}
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