~ubuntu-branches/ubuntu/lucid/openssh/lucid

/* $OpenBSD: auth2-chall.c,v 1.34 2008/12/09 04:32:22 djm Exp $ */

/*

 * Copyright (c) 2001 Markus Friedl.  All rights reserved.

 * Copyright (c) 2001 Per Allansson.  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"

#include <sys/types.h>

#include <stdarg.h>

#include <stdio.h>

#include <string.h>

#include "xmalloc.h"

#include "ssh2.h"

#include "key.h"

#include "hostfile.h"

#include "auth.h"

#include "buffer.h"

#include "packet.h"

#include "dispatch.h"

#include "log.h"

#include "servconf.h"

/* import */

extern ServerOptions options;

static int auth2_challenge_start(Authctxt *);

static int send_userauth_info_request(Authctxt *);

static void input_userauth_info_response(int, u_int32_t, void *);

#ifdef BSD_AUTH

extern KbdintDevice bsdauth_device;

#else

#ifdef USE_PAM

extern KbdintDevice sshpam_device;

#endif

#ifdef SKEY

extern KbdintDevice skey_device;

#endif

#endif

KbdintDevice *devices[] = {

#ifdef BSD_AUTH

	&bsdauth_device,

#else

#ifdef USE_PAM

	&sshpam_device,

#endif

#ifdef SKEY

	&skey_device,

#endif

#endif

	NULL

};

typedef struct KbdintAuthctxt KbdintAuthctxt;

struct KbdintAuthctxt

{

	char *devices;

	void *ctxt;

	KbdintDevice *device;

	u_int nreq;

};

#ifdef USE_PAM

void

remove_kbdint_device(const char *devname)

{

	int i, j;

	for (i = 0; devices[i] != NULL; i++)

		if (strcmp(devices[i]->name, devname) == 0) {

			for (j = i; devices[j] != NULL; j++)

				devices[j] = devices[j+1];

			i--;

		}

}

#endif

static KbdintAuthctxt *

kbdint_alloc(const char *devs)

{

	KbdintAuthctxt *kbdintctxt;

	Buffer b;

	int i;

#ifdef USE_PAM

	if (!options.use_pam)

		remove_kbdint_device("pam");

#endif

	kbdintctxt = xmalloc(sizeof(KbdintAuthctxt));

	if (strcmp(devs, "") == 0) {

		buffer_init(&b);

		for (i = 0; devices[i]; i++) {

			if (buffer_len(&b) > 0)

				buffer_append(&b, ",", 1);

			buffer_append(&b, devices[i]->name,

			    strlen(devices[i]->name));

		}

		buffer_append(&b, "\0", 1);

		kbdintctxt->devices = xstrdup(buffer_ptr(&b));

		buffer_free(&b);

	} else {

		kbdintctxt->devices = xstrdup(devs);

	}

	debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);

	kbdintctxt->ctxt = NULL;

	kbdintctxt->device = NULL;

	kbdintctxt->nreq = 0;

	return kbdintctxt;

}

static void

kbdint_reset_device(KbdintAuthctxt *kbdintctxt)

{

	if (kbdintctxt->ctxt) {

		kbdintctxt->device->free_ctx(kbdintctxt->ctxt);

		kbdintctxt->ctxt = NULL;

	}

	kbdintctxt->device = NULL;

}

static void

kbdint_free(KbdintAuthctxt *kbdintctxt)

{

	if (kbdintctxt->device)

		kbdint_reset_device(kbdintctxt);

	if (kbdintctxt->devices) {

		xfree(kbdintctxt->devices);

		kbdintctxt->devices = NULL;

	}

	xfree(kbdintctxt);

}

/* get next device */

static int

kbdint_next_device(KbdintAuthctxt *kbdintctxt)

{

	size_t len;

	char *t;

	int i;

	if (kbdintctxt->device)

		kbdint_reset_device(kbdintctxt);

	do {

		len = kbdintctxt->devices ?

		    strcspn(kbdintctxt->devices, ",") : 0;

		if (len == 0)

			break;

		for (i = 0; devices[i]; i++)

			if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)

				kbdintctxt->device = devices[i];

		t = kbdintctxt->devices;

		kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;

		xfree(t);

		debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?

		    kbdintctxt->devices : "<empty>");

	} while (kbdintctxt->devices && !kbdintctxt->device);

	return kbdintctxt->device ? 1 : 0;

}

/*

 * try challenge-response, set authctxt->postponed if we have to

 * wait for the response.

 */

int

auth2_challenge(Authctxt *authctxt, char *devs)

{

	debug("auth2_challenge: user=%s devs=%s",

	    authctxt->user ? authctxt->user : "<nouser>",

	    devs ? devs : "<no devs>");

	if (authctxt->user == NULL || !devs)

		return 0;

	if (authctxt->kbdintctxt == NULL)

		authctxt->kbdintctxt = kbdint_alloc(devs);

	return auth2_challenge_start(authctxt);

}

/* unregister kbd-int callbacks and context */

void

auth2_challenge_stop(Authctxt *authctxt)

{

	/* unregister callback */

	dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);

	if (authctxt->kbdintctxt != NULL) {

		kbdint_free(authctxt->kbdintctxt);

		authctxt->kbdintctxt = NULL;

	}

}

/* side effect: sets authctxt->postponed if a reply was sent*/

static int

auth2_challenge_start(Authctxt *authctxt)

{

	KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt;

	debug2("auth2_challenge_start: devices %s",

	    kbdintctxt->devices ?  kbdintctxt->devices : "<empty>");

	if (kbdint_next_device(kbdintctxt) == 0) {

		auth2_challenge_stop(authctxt);

		return 0;

	}

	debug("auth2_challenge_start: trying authentication method '%s'",

	    kbdintctxt->device->name);

	if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {

		auth2_challenge_stop(authctxt);

		return 0;

	}

	if (send_userauth_info_request(authctxt) == 0) {

		auth2_challenge_stop(authctxt);

		return 0;

	}

	dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,

	    &input_userauth_info_response);

	authctxt->postponed = 1;

	return 0;

}

static int

send_userauth_info_request(Authctxt *authctxt)

{

	KbdintAuthctxt *kbdintctxt;

	char *name, *instr, **prompts;

	u_int i, *echo_on;

	kbdintctxt = authctxt->kbdintctxt;

	if (kbdintctxt->device->query(kbdintctxt->ctxt,

	    &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))

		return 0;

	packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);

	packet_put_cstring(name);

	packet_put_cstring(instr);

	packet_put_cstring("");		/* language not used */

	packet_put_int(kbdintctxt->nreq);

	for (i = 0; i < kbdintctxt->nreq; i++) {

		packet_put_cstring(prompts[i]);

		packet_put_char(echo_on[i]);

	}

	packet_send();

	packet_write_wait();

	for (i = 0; i < kbdintctxt->nreq; i++)

		xfree(prompts[i]);

	xfree(prompts);

	xfree(echo_on);

	xfree(name);

	xfree(instr);

	return 1;

}

static void

input_userauth_info_response(int type, u_int32_t seq, void *ctxt)

{

	Authctxt *authctxt = ctxt;

	KbdintAuthctxt *kbdintctxt;

	int authenticated = 0, res;

	u_int i, nresp;

	char **response = NULL, *method;

	if (authctxt == NULL)

		fatal("input_userauth_info_response: no authctxt");

	kbdintctxt = authctxt->kbdintctxt;

	if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)

		fatal("input_userauth_info_response: no kbdintctxt");

	if (kbdintctxt->device == NULL)

		fatal("input_userauth_info_response: no device");

	authctxt->postponed = 0;	/* reset */

	nresp = packet_get_int();

	if (nresp != kbdintctxt->nreq)

		fatal("input_userauth_info_response: wrong number of replies");

	if (nresp > 100)

		fatal("input_userauth_info_response: too many replies");

	if (nresp > 0) {

		response = xcalloc(nresp, sizeof(char *));

		for (i = 0; i < nresp; i++)

			response[i] = packet_get_string(NULL);

	}

	packet_check_eom();

	res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response);

	for (i = 0; i < nresp; i++) {

		memset(response[i], 'r', strlen(response[i]));

		xfree(response[i]);

	}

	if (response)

		xfree(response);

	switch (res) {

	case 0:

		/* Success! */

		authenticated = authctxt->valid ? 1 : 0;

		break;

	case 1:

		/* Authentication needs further interaction */

		if (send_userauth_info_request(authctxt) == 1)

			authctxt->postponed = 1;

		break;

	default:

		/* Failure! */

		break;

	}

	xasprintf(&method, "keyboard-interactive/%s", kbdintctxt->device->name);

	if (!authctxt->postponed) {

		if (authenticated) {

			auth2_challenge_stop(authctxt);

		} else {

			/* start next device */

			/* may set authctxt->postponed */

			auth2_challenge_start(authctxt);

		}

	}

	userauth_finish(authctxt, authenticated, method);

	xfree(method);

}

void

privsep_challenge_enable(void)

{

#if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY)

	int n = 0;

#endif

#ifdef BSD_AUTH

	extern KbdintDevice mm_bsdauth_device;

#endif

#ifdef USE_PAM

	extern KbdintDevice mm_sshpam_device;

#endif

#ifdef SKEY

	extern KbdintDevice mm_skey_device;

#endif

#ifdef BSD_AUTH

	devices[n++] = &mm_bsdauth_device;

#else

#ifdef USE_PAM

	devices[n++] = &mm_sshpam_device;

#endif

#ifdef SKEY

	devices[n++] = &mm_skey_device;

#endif

#endif

}