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// SPDX-License-Identifier: GPL-2.0-or-later
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "drop_privs.h"
int
drop_privs(void)
{
/* drop gid */
if (setgid(getgid()) != 0)
return -errno;
/* drop uid */
if (setuid(getuid()) != 0)
return -errno;
/* Try to regain root. If this succeeds, we failed to drop
privileges. Don't do this as root, else the check will fail. */
if (getuid() != 0 && setuid(0) != -1)
return -EPERM;
return 0;
}
int
check_and_drop_privs(void)
{
int r;
if (geteuid() == getuid() &&
getegid() == getgid())
return 0;
fprintf(stderr, "Binary has the setuid or setgid bit set, please remove it.\n");
r = drop_privs();
if (r < 0)
{
fprintf(stderr, "Dropping privileges failed: %s\n", strerror(-r));
return r;
}
return 0;
}
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