auth2-none.c

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/*
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 */

#include "includes.h"
RCSID("$OpenBSD: auth2-none.c,v 1.7 2004/05/11 19:01:43 deraadt Exp $");

#include "auth.h"
#include "xmalloc.h"
#include "packet.h"
#include "log.h"
#include "servconf.h"
#include "atomicio.h"
#include "compat.h"
#include "ssh2.h"
#include "monitor_wrap.h"

/* import */
extern ServerOptions options;

/* "none" is allowed only one time */
static int none_enabled = 1;

char *
auth2_read_banner(void)
{
        struct stat st;
        char *banner = NULL;
        size_t len, n;
        int fd;

        if ((fd = open(options.banner, O_RDONLY)) == -1)
                return (NULL);
        if (fstat(fd, &st) == -1) {
                close(fd);
                return (NULL);
        }
        if (st.st_size > 1*1024*1024) {
                close(fd);
                return (NULL);
        }

        len = (size_t)st.st_size;               /* truncate */
        banner = xmalloc(len + 1);
        n = atomicio(read, fd, banner, len);
        close(fd);

        if (n != len) {
                xfree(banner);
                return (NULL);
        }
        banner[n] = '\0';

        return (banner);
}

void
userauth_send_banner(const char *msg)
{
        if (datafellows & SSH_BUG_BANNER)
                return;

        packet_start(SSH2_MSG_USERAUTH_BANNER);
        packet_put_cstring(msg);
        packet_put_cstring("");         /* language, unused */
        packet_send();
        debug("%s: sent", __func__);
}

static void
userauth_banner(void)
{
        char *banner = NULL;

        if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
                return;

        if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
                goto done;
        userauth_send_banner(banner);

done:
        if (banner)
                xfree(banner);
}

static int
userauth_none(Authctxt *authctxt)
{
        none_enabled = 0;
        packet_check_eom();
        userauth_banner();
#ifdef HAVE_CYGWIN
        if (check_nt_auth(1, authctxt->pw) == 0)
                return (0);
#endif
        if (options.password_authentication)
                return (PRIVSEP(auth_password(authctxt, "")));
        return (0);
}

Authmethod method_none = {
        "none",
        userauth_none,
        &none_enabled
};

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