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/* wydawca - automatic release submission daemon
   Copyright (C) 2007, 2009-2013, 2017, 2019-2021 Sergey Poznyakoff

   Wydawca 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.

   Wydawca 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 wydawca. If not, see <http://www.gnu.org/licenses/>. */

#include "wydawca.h"

int
wydawca_userprivs(uid_t uid, gid_t gid, gid_t * grplist, size_t ngrp)
{
    int rc = 0;

    if (uid == 0)
	return 0;

    /* Reset group permissions */
    if (geteuid() == 0 && setgroups(ngrp, grplist)) {
	wy_log(LOG_CRIT, "setgroups(%lu, %lu...): %s",
	       (unsigned long) ngrp, (unsigned long) grplist[0],
	       strerror(errno));
	return rc;
    }

    /* Switch to the user's gid. On some OSes the effective gid must
       be reset first */

#if defined(HAVE_SETEGID)
    if ((rc = setegid(gid)) < 0)
	wy_log(LOG_CRIT, "setegid(%lu): %s",
	       (unsigned long) gid, strerror(errno));
#elif defined(HAVE_SETREGID)
    if ((rc = setregid(gid, gid)) < 0)
	wy_log(LOG_CRIT, "setregid(%lu,%lu)d: %s",
	       (unsigned long) gid, (unsigned long) gid, strerror(errno));
#elif defined(HAVE_SETRESGID)
    if ((rc = setresgid(gid, gid, gid)) < 0)
	wy_log(LOG_CRIT, "setresgid(%lu,%lu,%lu): %s",
	       (unsigned long) gid, (unsigned long) gid,
	       (unsigned long) gid, strerror(errno));
#endif

    if (rc == 0 && gid != 0) {
	if ((rc = setgid(gid)) < 0 && getegid() != gid)
	    wy_log(LOG_CRIT, "setgid(%lu): %s",
		   (unsigned long) gid, strerror(errno));
	if (rc == 0 && getegid() != gid) {
	    wy_log(LOG_CRIT, _("cannot set effective gid to %lu"),
		   (unsigned long) gid);
	    rc = 1;
	}
    }

    /* Now reset uid */
    if (rc == 0 && uid != 0) {
	uid_t euid;

	if (setuid(uid) ||
	    geteuid() != uid ||
	    (getuid() != uid && (geteuid() == 0 || getuid() == 0))) {

#if defined(HAVE_SETREUID)
	    if (geteuid() != uid) {
		if (setreuid(uid, -1) < 0) {
		    wy_log(LOG_CRIT,
			   "setreuid(%lu,-1): %s",
			   (unsigned long) uid, strerror(errno));
		    rc = 1;
		}
		if (setuid(uid) < 0) {
		    wy_log(LOG_CRIT,
			   "setreuid(%lu,-1): %s",
			   (unsigned long) uid, strerror(errno));
		    rc = 1;
		}
	    } else
#endif
	    {
		wy_log(LOG_CRIT, "setuid(%lu): %s",
		       (unsigned long) uid, strerror(errno));
		rc = 1;
	    }
	}

	euid = geteuid();
	if (uid != 0 && setuid(0) == 0) {
	    wy_log(LOG_CRIT, _("seteuid(0) succeeded when it should not"));
	    rc = 1;
	} else if (uid != euid && setuid(euid) == 0) {
	    wy_log(LOG_CRIT, _("cannot drop non-root setuid privileges"));
	    rc = 1;
	}
    }

    return rc;
}

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