source: openpam/trunk/lib/openpam_ttyconv.c @ 437

/*-
 * Copyright (c) 2002-2003 Networks Associates Technology, Inc.
 * Copyright (c) 2004-2011 Dag-Erling Smørgrav
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by ThinkSec AS and
 * Network Associates Laboratories, the Security Research Division of
 * Network Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
 * ("CBOSS"), as part of the DARPA CHATS research program.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $Id: openpam_ttyconv.c 437 2011-09-13 12:00:13Z des $
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <sys/types.h>

#include <ctype.h>
#include <errno.h>
#include <setjmp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>

#include <security/pam_appl.h>

#include "openpam_impl.h"

int openpam_ttyconv_timeout = 0;

static void
timeout(int sig)
{

        (void)sig;
}

static char *
prompt(const char *msg)
{
        char buf[PAM_MAX_RESP_SIZE];
        struct sigaction action, saved_action;
        sigset_t saved_sigset, sigset;
        unsigned int saved_alarm;
        int eof, error, fd;
        size_t len;
        char *retval;
        char ch;

        sigemptyset(&sigset);
        sigaddset(&sigset, SIGINT);
        sigaddset(&sigset, SIGTSTP);
        sigprocmask(SIG_SETMASK, &sigset, &saved_sigset);
        action.sa_handler = &timeout;
        action.sa_flags = 0;
        sigemptyset(&action.sa_mask);
        sigaction(SIGALRM, &action, &saved_action);
        fputs(msg, stdout);
        fflush(stdout);
#ifdef HAVE_FPURGE
        fpurge(stdin);
#endif
        fd = fileno(stdin);
        buf[0] = '\0';
        eof = error = 0;
        saved_alarm = 0;
        if (openpam_ttyconv_timeout >= 0)
                saved_alarm = alarm(openpam_ttyconv_timeout);
        ch = '\0';
        for (len = 0; ch != '\n' && !eof && !error; ++len) {
                switch (read(fd, &ch, 1)) {
                case 1:
                        if (len < PAM_MAX_RESP_SIZE - 1) {
                                buf[len + 1] = '\0';
                                buf[len] = ch;
                        }
                        break;
                case 0:
                        eof = 1;
                        break;
                default:
                        error = errno;
                        break;
                }
        }
        if (openpam_ttyconv_timeout >= 0)
                alarm(0);
        sigaction(SIGALRM, &saved_action, NULL);
        sigprocmask(SIG_SETMASK, &saved_sigset, NULL);
        if (saved_alarm > 0)
                alarm(saved_alarm);
        if (error == EINTR)
                fputs(" timeout!", stderr);
        if (error || eof) {
                fputs("\n", stderr);
                memset(buf, 0, sizeof(buf));
                return (NULL);
        }
        /* trim trailing whitespace */
        for (len = strlen(buf); len > 0; --len)
                if (buf[len - 1] != '\r' && buf[len - 1] != '\n')
                        break;
        buf[len] = '\0';
        retval = strdup(buf);
        memset(buf, 0, sizeof(buf));
        return (retval);
}

static char *
prompt_echo_off(const char *msg)
{
        struct termios tattr;
        tcflag_t lflag;
        char *ret;
        int fd;

        fd = fileno(stdin);
        if (tcgetattr(fd, &tattr) != 0) {
                openpam_log(PAM_LOG_ERROR, "tcgetattr(): %m");
                return (NULL);
        }
        lflag = tattr.c_lflag;
        tattr.c_lflag &= ~ECHO;
        if (tcsetattr(fd, TCSAFLUSH, &tattr) != 0) {
                openpam_log(PAM_LOG_ERROR, "tcsetattr(): %m");
                return (NULL);
        }
        ret = prompt(msg);
        tattr.c_lflag = lflag;
        (void)tcsetattr(fd, TCSANOW, &tattr);
        if (ret != NULL)
                fputs("\n", stdout);
        return (ret);
}

/*
 * OpenPAM extension
 *
 * Simple tty-based conversation function
 */

int
openpam_ttyconv(int n,
         const struct pam_message **msg,
         struct pam_response **resp,
         void *data)
{
        struct pam_response *aresp;
        int i;

        ENTER();
        (void)data;
        if (n <= 0 || n > PAM_MAX_NUM_MSG)
                RETURNC(PAM_CONV_ERR);
        if ((aresp = calloc(n, sizeof *aresp)) == NULL)
                RETURNC(PAM_BUF_ERR);
        for (i = 0; i < n; ++i) {
                aresp[i].resp_retcode = 0;
                aresp[i].resp = NULL;
                switch (msg[i]->msg_style) {
                case PAM_PROMPT_ECHO_OFF:
                        aresp[i].resp = prompt_echo_off(msg[i]->msg);
                        if (aresp[i].resp == NULL)
                                goto fail;
                        break;
                case PAM_PROMPT_ECHO_ON:
                        aresp[i].resp = prompt(msg[i]->msg);
                        if (aresp[i].resp == NULL)
                                goto fail;
                        break;
                case PAM_ERROR_MSG:
                        fputs(msg[i]->msg, stderr);
                        if (strlen(msg[i]->msg) > 0 &&
                            msg[i]->msg[strlen(msg[i]->msg) - 1] != '\n')
                                fputc('\n', stderr);
                        break;
                case PAM_TEXT_INFO:
                        fputs(msg[i]->msg, stdout);
                        if (strlen(msg[i]->msg) > 0 &&
                            msg[i]->msg[strlen(msg[i]->msg) - 1] != '\n')
                                fputc('\n', stdout);
                        break;
                default:
                        goto fail;
                }
        }
        *resp = aresp;
        RETURNC(PAM_SUCCESS);
fail:
        for (i = 0; i < n; ++i) {
                if (aresp[i].resp != NULL) {
                        memset(aresp[i].resp, 0, strlen(aresp[i].resp));
                        FREE(aresp[i].resp);
                }
        }
        memset(aresp, 0, n * sizeof *aresp);
        FREE(aresp);
        *resp = NULL;
        RETURNC(PAM_CONV_ERR);
}

/*
 * Error codes:
 *
 *      PAM_SYSTEM_ERR
 *      PAM_BUF_ERR
 *      PAM_CONV_ERR
 */

/**
 * The =openpam_ttyconv function is a standard conversation function
 * suitable for use on TTY devices.
 * It should be adequate for the needs of most text-based interactive
 * programs.
 *
 * The =openpam_ttyconv function allows the application to specify a
 * timeout for user input by setting the global integer variable
 * :openpam_ttyconv_timeout to the length of the timeout in seconds.
 *
 * >openpam_nullconv
 * >pam_prompt
 * >pam_vprompt
 */