88ec7d3792
note that official openssh distribution have already dropped kerberosIV support, therefore maintenance cost needs to be paid by us. and have no intent to help.
403 lines
10 KiB
C
403 lines
10 KiB
C
/* $NetBSD: auth1.c,v 1.25 2003/07/24 15:31:53 itojun Exp $ */
|
|
/*
|
|
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
* All rights reserved
|
|
*
|
|
* As far as I am concerned, the code I have written for this software
|
|
* can be used freely for any purpose. Any derived versions of this
|
|
* software must be clearly marked as such, and if the derived work is
|
|
* incompatible with the protocol description in the RFC file, it must be
|
|
* called by a name other than "ssh" or "Secure Shell".
|
|
*/
|
|
|
|
#include "includes.h"
|
|
RCSID("$OpenBSD: auth1.c,v 1.47 2003/02/06 21:22:42 markus Exp $");
|
|
__RCSID("$NetBSD: auth1.c,v 1.25 2003/07/24 15:31:53 itojun Exp $");
|
|
|
|
#include "xmalloc.h"
|
|
#include "rsa.h"
|
|
#include "ssh1.h"
|
|
#include "packet.h"
|
|
#include "buffer.h"
|
|
#include "mpaux.h"
|
|
#include "log.h"
|
|
#include "servconf.h"
|
|
#include "compat.h"
|
|
#include "auth.h"
|
|
#include "channels.h"
|
|
#include "session.h"
|
|
#include "uidswap.h"
|
|
#include "monitor_wrap.h"
|
|
|
|
/* import */
|
|
extern ServerOptions options;
|
|
|
|
/*
|
|
* convert ssh auth msg type into description
|
|
*/
|
|
static char *
|
|
get_authname(int type)
|
|
{
|
|
static char buf[1024];
|
|
switch (type) {
|
|
case SSH_CMSG_AUTH_PASSWORD:
|
|
return "password";
|
|
case SSH_CMSG_AUTH_RSA:
|
|
return "rsa";
|
|
case SSH_CMSG_AUTH_RHOSTS_RSA:
|
|
return "rhosts-rsa";
|
|
case SSH_CMSG_AUTH_RHOSTS:
|
|
return "rhosts";
|
|
case SSH_CMSG_AUTH_TIS:
|
|
case SSH_CMSG_AUTH_TIS_RESPONSE:
|
|
return "challenge-response";
|
|
#if defined(KRB4) || defined(KRB5)
|
|
case SSH_CMSG_AUTH_KERBEROS:
|
|
return "kerberos";
|
|
#endif
|
|
}
|
|
snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
|
|
return buf;
|
|
}
|
|
|
|
/*
|
|
* read packets, try to authenticate the user and
|
|
* return only if authentication is successful
|
|
*/
|
|
static void
|
|
do_authloop(Authctxt *authctxt)
|
|
{
|
|
int authenticated = 0;
|
|
u_int bits;
|
|
Key *client_host_key;
|
|
BIGNUM *n;
|
|
char *client_user, *password;
|
|
char info[1024];
|
|
u_int dlen;
|
|
u_int ulen;
|
|
int type = 0;
|
|
struct passwd *pw = authctxt->pw;
|
|
|
|
debug("Attempting authentication for %s%.100s.",
|
|
authctxt->valid ? "" : "illegal user ", authctxt->user);
|
|
|
|
/* If the user has no password, accept authentication immediately. */
|
|
if (options.password_authentication &&
|
|
#if defined(KRB4) || defined(KRB5)
|
|
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
|
|
#endif
|
|
PRIVSEP(auth_password(authctxt, ""))) {
|
|
auth_log(authctxt, 1, "without authentication", "");
|
|
return;
|
|
}
|
|
|
|
/* Indicate that authentication is needed. */
|
|
packet_start(SSH_SMSG_FAILURE);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
for (;;) {
|
|
/* default to fail */
|
|
authenticated = 0;
|
|
|
|
info[0] = '\0';
|
|
|
|
/* Get a packet from the client. */
|
|
type = packet_read();
|
|
|
|
/* Process the packet. */
|
|
switch (type) {
|
|
|
|
#if defined(KRB4) || defined(KRB5)
|
|
case SSH_CMSG_AUTH_KERBEROS:
|
|
if (!options.kerberos_authentication) {
|
|
verbose("Kerberos authentication disabled.");
|
|
} else {
|
|
char *kdata = packet_get_string(&dlen);
|
|
packet_check_eom();
|
|
|
|
if (kdata[0] == 4) { /* KRB_PROT_VERSION */
|
|
#ifdef KRB4
|
|
KTEXT_ST tkt, reply;
|
|
tkt.length = dlen;
|
|
if (tkt.length < MAX_KTXT_LEN)
|
|
memcpy(tkt.dat, kdata, tkt.length);
|
|
|
|
if (PRIVSEP(auth_krb4(authctxt, &tkt,
|
|
&client_user, &reply))) {
|
|
authenticated = 1;
|
|
snprintf(info, sizeof(info),
|
|
" tktuser %.100s",
|
|
client_user);
|
|
|
|
packet_start(
|
|
SSH_SMSG_AUTH_KERBEROS_RESPONSE);
|
|
packet_put_string((char *)
|
|
reply.dat, reply.length);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
xfree(client_user);
|
|
}
|
|
#endif /* KRB4 */
|
|
} else {
|
|
#ifdef KRB5
|
|
krb5_data tkt, reply;
|
|
tkt.length = dlen;
|
|
tkt.data = kdata;
|
|
|
|
if (PRIVSEP(auth_krb5(authctxt, &tkt,
|
|
&client_user, &reply))) {
|
|
authenticated = 1;
|
|
snprintf(info, sizeof(info),
|
|
" tktuser %.100s",
|
|
client_user);
|
|
|
|
/* Send response to client */
|
|
packet_start(
|
|
SSH_SMSG_AUTH_KERBEROS_RESPONSE);
|
|
packet_put_string((char *)
|
|
reply.data, reply.length);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
if (reply.length)
|
|
xfree(reply.data);
|
|
xfree(client_user);
|
|
}
|
|
#endif /* KRB5 */
|
|
}
|
|
xfree(kdata);
|
|
}
|
|
break;
|
|
#endif /* KRB4 || KRB5 */
|
|
|
|
#if defined(AFS) || defined(KRB5)
|
|
/* XXX - punt on backward compatibility here. */
|
|
case SSH_CMSG_HAVE_KERBEROS_TGT:
|
|
packet_send_debug("Kerberos TGT passing disabled before authentication.");
|
|
break;
|
|
#ifdef AFS
|
|
case SSH_CMSG_HAVE_AFS_TOKEN:
|
|
packet_send_debug("AFS token passing disabled before authentication.");
|
|
break;
|
|
#endif /* AFS */
|
|
#endif /* AFS || KRB5 */
|
|
|
|
case SSH_CMSG_AUTH_RHOSTS:
|
|
if (!options.rhosts_authentication) {
|
|
verbose("Rhosts authentication disabled.");
|
|
break;
|
|
}
|
|
/*
|
|
* Get client user name. Note that we just have to
|
|
* trust the client; this is one reason why rhosts
|
|
* authentication is insecure. (Another is
|
|
* IP-spoofing on a local network.)
|
|
*/
|
|
client_user = packet_get_string(&ulen);
|
|
packet_check_eom();
|
|
|
|
/* Try to authenticate using /etc/hosts.equiv and .rhosts. */
|
|
authenticated = auth_rhosts(pw, client_user);
|
|
|
|
snprintf(info, sizeof info, " ruser %.100s", client_user);
|
|
xfree(client_user);
|
|
break;
|
|
|
|
case SSH_CMSG_AUTH_RHOSTS_RSA:
|
|
if (!options.rhosts_rsa_authentication) {
|
|
verbose("Rhosts with RSA authentication disabled.");
|
|
break;
|
|
}
|
|
/*
|
|
* Get client user name. Note that we just have to
|
|
* trust the client; root on the client machine can
|
|
* claim to be any user.
|
|
*/
|
|
client_user = packet_get_string(&ulen);
|
|
|
|
/* Get the client host key. */
|
|
client_host_key = key_new(KEY_RSA1);
|
|
bits = packet_get_int();
|
|
packet_get_bignum(client_host_key->rsa->e);
|
|
packet_get_bignum(client_host_key->rsa->n);
|
|
|
|
if (bits != BN_num_bits(client_host_key->rsa->n))
|
|
verbose("Warning: keysize mismatch for client_host_key: "
|
|
"actual %d, announced %d",
|
|
BN_num_bits(client_host_key->rsa->n), bits);
|
|
packet_check_eom();
|
|
|
|
authenticated = auth_rhosts_rsa(pw, client_user,
|
|
client_host_key);
|
|
key_free(client_host_key);
|
|
|
|
snprintf(info, sizeof info, " ruser %.100s", client_user);
|
|
xfree(client_user);
|
|
break;
|
|
|
|
case SSH_CMSG_AUTH_RSA:
|
|
if (!options.rsa_authentication) {
|
|
verbose("RSA authentication disabled.");
|
|
break;
|
|
}
|
|
/* RSA authentication requested. */
|
|
if ((n = BN_new()) == NULL)
|
|
fatal("do_authloop: BN_new failed");
|
|
packet_get_bignum(n);
|
|
packet_check_eom();
|
|
authenticated = auth_rsa(pw, n);
|
|
BN_clear_free(n);
|
|
break;
|
|
|
|
case SSH_CMSG_AUTH_PASSWORD:
|
|
if (!options.password_authentication) {
|
|
verbose("Password authentication disabled.");
|
|
break;
|
|
}
|
|
/*
|
|
* Read user password. It is in plain text, but was
|
|
* transmitted over the encrypted channel so it is
|
|
* not visible to an outside observer.
|
|
*/
|
|
password = packet_get_string(&dlen);
|
|
packet_check_eom();
|
|
|
|
/* Try authentication with the password. */
|
|
authenticated = PRIVSEP(auth_password(authctxt, password));
|
|
|
|
memset(password, 0, strlen(password));
|
|
xfree(password);
|
|
break;
|
|
|
|
case SSH_CMSG_AUTH_TIS:
|
|
debug("rcvd SSH_CMSG_AUTH_TIS");
|
|
if (options.challenge_response_authentication == 1) {
|
|
char *challenge = get_challenge(authctxt);
|
|
if (challenge != NULL) {
|
|
debug("sending challenge '%s'", challenge);
|
|
packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
|
|
packet_put_cstring(challenge);
|
|
xfree(challenge);
|
|
packet_send();
|
|
packet_write_wait();
|
|
continue;
|
|
}
|
|
}
|
|
break;
|
|
case SSH_CMSG_AUTH_TIS_RESPONSE:
|
|
debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
|
|
if (options.challenge_response_authentication == 1) {
|
|
char *response = packet_get_string(&dlen);
|
|
packet_check_eom();
|
|
authenticated = verify_response(authctxt, response);
|
|
memset(response, 'r', dlen);
|
|
xfree(response);
|
|
}
|
|
break;
|
|
|
|
default:
|
|
/*
|
|
* Any unknown messages will be ignored (and failure
|
|
* returned) during authentication.
|
|
*/
|
|
logit("Unknown message during authentication: type %d", type);
|
|
break;
|
|
}
|
|
#ifdef BSD_AUTH
|
|
if (authctxt->as) {
|
|
auth_close(authctxt->as);
|
|
authctxt->as = NULL;
|
|
}
|
|
#endif
|
|
if (!authctxt->valid && authenticated)
|
|
fatal("INTERNAL ERROR: authenticated invalid user %s",
|
|
authctxt->user);
|
|
|
|
/* Special handling for root */
|
|
if (authenticated && authctxt->pw->pw_uid == 0 &&
|
|
!auth_root_allowed(get_authname(type)))
|
|
authenticated = 0;
|
|
|
|
/* Log before sending the reply */
|
|
auth_log(authctxt, authenticated, get_authname(type), info);
|
|
|
|
if (authenticated)
|
|
return;
|
|
|
|
if (authctxt->failures++ > AUTH_FAIL_MAX)
|
|
packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
|
|
|
|
packet_start(SSH_SMSG_FAILURE);
|
|
packet_send();
|
|
packet_write_wait();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Performs authentication of an incoming connection. Session key has already
|
|
* been exchanged and encryption is enabled.
|
|
*/
|
|
Authctxt *
|
|
do_authentication(void)
|
|
{
|
|
Authctxt *authctxt;
|
|
u_int ulen;
|
|
char *user, *style = NULL;
|
|
|
|
/* Get the name of the user that we wish to log in as. */
|
|
packet_read_expect(SSH_CMSG_USER);
|
|
|
|
/* Get the user name. */
|
|
user = packet_get_string(&ulen);
|
|
packet_check_eom();
|
|
|
|
if ((style = strchr(user, ':')) != NULL)
|
|
*style++ = '\0';
|
|
|
|
#ifdef KRB5
|
|
/* XXX - SSH.com Kerberos v5 braindeath. */
|
|
if ((datafellows & SSH_BUG_K5USER) &&
|
|
options.kerberos_authentication) {
|
|
char *p;
|
|
if ((p = strchr(user, '@')) != NULL)
|
|
*p = '\0';
|
|
}
|
|
#endif
|
|
|
|
authctxt = authctxt_new();
|
|
authctxt->user = user;
|
|
authctxt->style = style;
|
|
|
|
/* Verify that the user is a valid user. */
|
|
if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
|
|
authctxt->valid = 1;
|
|
else
|
|
debug("do_authentication: illegal user %s", user);
|
|
|
|
setproctitle("%s%s", authctxt->pw ? user : "unknown",
|
|
use_privsep ? " [net]" : "");
|
|
|
|
/*
|
|
* If we are not running as root, the user must have the same uid as
|
|
* the server.
|
|
*/
|
|
if (!use_privsep && getuid() != 0 && authctxt->pw &&
|
|
authctxt->pw->pw_uid != getuid())
|
|
packet_disconnect("Cannot change user when server not running as root.");
|
|
|
|
/*
|
|
* Loop until the user has been authenticated or the connection is
|
|
* closed, do_authloop() returns only if authentication is successful
|
|
*/
|
|
do_authloop(authctxt);
|
|
|
|
/* The user has been authenticated and accepted. */
|
|
packet_start(SSH_SMSG_SUCCESS);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
return (authctxt);
|
|
}
|