auth2-chall.c - third_party/openssh-portable - Git at Google

 /*
  * 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"
 RCSID("$OpenBSD: auth2-chall.c,v 1.20 2002/06/30 21:59:45 deraadt Exp $");

 #include "ssh2.h"
 #include "auth.h"
 #include "buffer.h"
 #include "packet.h"
 #include "xmalloc.h"
 #include "dispatch.h"
 #include "auth.h"
 #include "log.h"

 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 SKEY
 extern KbdintDevice skey_device;
 #endif
 #endif

 KbdintDevice *devices[] = {
 #ifdef BSD_AUTH
 	&bsdauth_device,
 #else
 #ifdef SKEY
 	&skey_device,
 #endif
 #endif
 	NULL
 };

 typedef struct KbdintAuthctxt KbdintAuthctxt;
 struct KbdintAuthctxt
 {
 	char *devices;
 	void *ctxt;
 	KbdintDevice *device;
 	u_int nreq;
 };

 static KbdintAuthctxt *
 kbdint_alloc(const char *devs)
 {
 	KbdintAuthctxt *kbdintctxt;
 	Buffer b;
 	int i;

 	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;
 	int i;
 	u_int *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 i, authenticated = 0, res, len;
 	u_int 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 = xmalloc(nresp * sizeof(char *));
 		for (i = 0; i < nresp; i++)
 			response[i] = packet_get_string(NULL);
 	}
 	packet_check_eom();

 	if (authctxt->valid) {
 		res = kbdintctxt->device->respond(kbdintctxt->ctxt,
 		    nresp, response);
 	} else {
 		res = -1;
 	}

 	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 = 1;
 		break;
 	case 1:
 		/* Authentication needs further interaction */
 		if (send_userauth_info_request(authctxt) == 1)
 			authctxt->postponed = 1;
 		break;
 	default:
 		/* Failure! */
 		break;
 	}

 	len = strlen("keyboard-interactive") + 2 +
 		strlen(kbdintctxt->device->name);
 	method = xmalloc(len);
 	snprintf(method, len, "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)
 {
 #ifdef BSD_AUTH
 	extern KbdintDevice mm_bsdauth_device;
 #endif
 #ifdef SKEY
 	extern KbdintDevice mm_skey_device;
 #endif
 	/* As long as SSHv1 has devices[0] hard coded this is fine */
 #ifdef BSD_AUTH
 	devices[0] = &mm_bsdauth_device;
 #else
 #ifdef SKEY
 	devices[0] = &mm_skey_device;
 #endif
 #endif
 }
	/*
	* 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"
	RCSID("$OpenBSD: auth2-chall.c,v 1.20 2002/06/30 21:59:45 deraadt Exp $");

	#include "ssh2.h"
	#include "auth.h"
	#include "buffer.h"
	#include "packet.h"
	#include "xmalloc.h"
	#include "dispatch.h"
	#include "auth.h"
	#include "log.h"

	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 SKEY
	extern KbdintDevice skey_device;
	#endif
	#endif

	KbdintDevice *devices[] = {
	#ifdef BSD_AUTH
	&bsdauth_device,
	#else
	#ifdef SKEY
	&skey_device,
	#endif
	#endif
	NULL
	};

	typedef struct KbdintAuthctxt KbdintAuthctxt;
	struct KbdintAuthctxt
	{
	char *devices;
	void *ctxt;
	KbdintDevice *device;
	u_int nreq;
	};

	static KbdintAuthctxt *
	kbdint_alloc(const char *devs)
	{
	KbdintAuthctxt *kbdintctxt;
	Buffer b;
	int i;

	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;
	int i;
	u_int *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 i, authenticated = 0, res, len;
	u_int 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 = xmalloc(nresp * sizeof(char *));
	for (i = 0; i < nresp; i++)
	response[i] = packet_get_string(NULL);
	}
	packet_check_eom();

	if (authctxt->valid) {
	res = kbdintctxt->device->respond(kbdintctxt->ctxt,
	nresp, response);
	} else {
	res = -1;
	}

	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 = 1;
	break;
	case 1:
	/* Authentication needs further interaction */
	if (send_userauth_info_request(authctxt) == 1)
	authctxt->postponed = 1;
	break;
	default:
	/* Failure! */
	break;
	}

	len = strlen("keyboard-interactive") + 2 +
	strlen(kbdintctxt->device->name);
	method = xmalloc(len);
	snprintf(method, len, "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)
	{
	#ifdef BSD_AUTH
	extern KbdintDevice mm_bsdauth_device;
	#endif
	#ifdef SKEY
	extern KbdintDevice mm_skey_device;
	#endif
	/* As long as SSHv1 has devices[0] hard coded this is fine */
	#ifdef BSD_AUTH
	devices[0] = &mm_bsdauth_device;
	#else
	#ifdef SKEY
	devices[0] = &mm_skey_device;
	#endif
	#endif
	}