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freebsd-skq/crypto/openssh/auth2-chall.c
Dag-Erling Smørgrav d4af9e693f Upgrade to OpenSSH 5.1p1. 
I have worked hard to reduce diffs against the vendor branch.  One
notable change in that respect is that we no longer prefer DSA over
RSA - the reasons for doing so went away years ago.  This may cause
some surprises, as ssh will warn about unknown host keys even for
hosts whose keys haven't changed.

MFC after:	6 weeks
2008-08-01 02:48:36 +00:00

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/* $OpenBSD: auth2-chall.c,v 1.33 2007/09/21 08:15:29 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, len;
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;
}
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)
{
#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
}
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