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/*
* 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 1.23 2001/05/18 14:13:28 markus 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 "session.h"
#include "misc.h"
/* import */
extern ServerOptions options;
#ifdef WITH_AIXAUTHENTICATE
extern char *aixloginmsg;
#endif /* WITH_AIXAUTHENTICATE */
/*
* convert ssh auth msg type into description
*/
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";
#ifdef KRB4
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
*/
void
do_authloop(Authctxt *authctxt)
{
int authenticated = 0;
u_int bits;
RSA *client_host_key;
BIGNUM *n;
char *client_user, *password;
char info[1024];
u_int dlen;
int plen, nlen, elen;
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 &&
#ifdef KRB4
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
#ifdef USE_PAM
auth_pam_password(pw, "")) {
#elif defined(HAVE_OSF_SIA)
0) {
#else
auth_password(authctxt, "")) {
#endif
auth_log(authctxt, 1, "without authentication", "");
return;
}
/* Indicate that authentication is needed. */
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
client_user = NULL;
for (;;) {
/* default to fail */
authenticated = 0;
info[0] = '\0';
/* Get a packet from the client. */
type = packet_read(&plen);
/* Process the packet. */
switch (type) {
#ifdef AFS
case SSH_CMSG_HAVE_KERBEROS_TGT:
if (!options.kerberos_tgt_passing) {
verbose("Kerberos tgt passing disabled.");
break;
} else {
/* Accept Kerberos tgt. */
char *tgt = packet_get_string(&dlen);
packet_integrity_check(plen, 4 + dlen, type);
if (!auth_kerberos_tgt(pw, tgt))
verbose("Kerberos tgt REFUSED for %.100s", authctxt->user);
xfree(tgt);
}
continue;
case SSH_CMSG_HAVE_AFS_TOKEN:
if (!options.afs_token_passing || !k_hasafs()) {
verbose("AFS token passing disabled.");
break;
} else {
/* Accept AFS token. */
char *token_string = packet_get_string(&dlen);
packet_integrity_check(plen, 4 + dlen, type);
if (!auth_afs_token(pw, token_string))
verbose("AFS token REFUSED for %.100s", authctxt->user);
xfree(token_string);
}
continue;
#endif /* AFS */
#ifdef KRB4
case SSH_CMSG_AUTH_KERBEROS:
if (!options.kerberos_authentication) {
verbose("Kerberos authentication disabled.");
break;
} else {
/* Try Kerberos v4 authentication. */
KTEXT_ST auth;
char *tkt_user = NULL;
char *kdata = packet_get_string((u_int *) &auth.length);
packet_integrity_check(plen, 4 + auth.length, type);
if (authctxt->valid) {
if (auth.length < MAX_KTXT_LEN)
memcpy(auth.dat, kdata, auth.length);
authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user);
if (authenticated) {
snprintf(info, sizeof info,
" tktuser %.100s", tkt_user);
xfree(tkt_user);
}
}
xfree(kdata);
}
break;
#endif /* KRB4 */
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_integrity_check(plen, 4 + ulen, type);
/* Try to authenticate using /etc/hosts.equiv and .rhosts. */
authenticated = auth_rhosts(pw, client_user);
snprintf(info, sizeof info, " ruser %.100s", 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 = RSA_new();
if (client_host_key == NULL)
fatal("RSA_new failed");
client_host_key->e = BN_new();
client_host_key->n = BN_new();
if (client_host_key->e == NULL || client_host_key->n == NULL)
fatal("BN_new failed");
bits = packet_get_int();
packet_get_bignum(client_host_key->e, &elen);
packet_get_bignum(client_host_key->n, &nlen);
if (bits != BN_num_bits(client_host_key->n))
verbose("Warning: keysize mismatch for client_host_key: "
"actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
RSA_free(client_host_key);
snprintf(info, sizeof info, " ruser %.100s", client_user);
break;
case SSH_CMSG_AUTH_RSA:
if (!options.rsa_authentication) {
verbose("RSA authentication disabled.");
break;
}
/* RSA authentication requested. */
n = BN_new();
packet_get_bignum(n, &nlen);
packet_integrity_check(plen, nlen, type);
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_integrity_check(plen, 4 + dlen, type);
#ifdef USE_PAM
/* Do PAM auth with password */
authenticated = auth_pam_password(pw, password);
#elif defined(HAVE_OSF_SIA)
/* Do SIA auth with password */
authenticated = auth_sia_password(authctxt->user,
password);
#else /* !USE_PAM && !HAVE_OSF_SIA */
/* Try authentication with the password. */
authenticated = auth_password(authctxt, password);
#endif /* USE_PAM */
memset(password, 0, strlen(password));
xfree(password);
break;
case SSH_CMSG_AUTH_TIS:
debug("rcvd SSH_CMSG_AUTH_TIS");
if
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