/*      $OpenBSD: setgid_child.c,v 1.3 2021/12/15 18:42:38 anton Exp $  */
/*
 *      Written by Bret Stephen Lambert <blambert@openbsd.org> 2014
 *      Public Domain.
 */

#include <sys/types.h>
#include <sys/signal.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/wait.h>

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <pwd.h>
#include <unistd.h>

#include "setuid_regress.h"

int
main(int argc, const char *argv[])
{
        struct kinfo_proc        kproc;
        struct passwd           *pw;
        pid_t                    pid;
        int                      status;

        if ((pw = getpwnam(_SETUID_REGRESS_USER)) == NULL)
                err(1, "unknown user \"%s\"", _SETUID_REGRESS_USER);

        if (setgid(pw->pw_gid) == -1)
                err(1, "setgid");

        switch ((pid = fork())) {

        default:
                waitpid(pid, &status, 0);
                if (WIFSIGNALED(status))
                        errx(1, "child exited due to signal %d",
                            WTERMSIG(status));
                else if (WEXITSTATUS(status) != 0)
                        errx(1, "child exited with status %d",
                            WEXITSTATUS(status));
                break;

        case 0:
                /*
                 * From the setgid man page:
                 *   The setgid() function sets the real and effective user IDs
                 *   and the saved set-user-ID of the current process
                 */
                checkgids(pw->pw_gid, pw->pw_gid, pw->pw_gid, "setgid child");

                /* should only respond to setgid upon exec */
                if (issetugid())
                        errx(1, "child incorrectly marked as issetugid()");

                if (read_kproc_pid(&kproc, getpid()) == -1)
                        err(1, "kproc read failed");

                if (!(kproc.p_psflags & PS_SUGID))
                        errx(1, "PS_SUGID not set");
                if (kproc.p_psflags & PS_SUGIDEXEC)
                        errx(1, "PS_SUGIDEXEC incorrectly set");

                break;

        case -1:
                err(1, "fork");
                /* NOTREACHED */
        }

        exit(0);
}