mirror of
git://anongit.mindrot.org/openssh.git
synced 2024-12-28 21:22:07 +00:00
2e0cf0dca2
monitor_wrap.c monitor_wrap.h session.c sshd.c]: Prepend all of the audit defines and enums with SSH_ to prevent namespace collisions on some platforms (eg AIX).
363 lines
9.0 KiB
C
363 lines
9.0 KiB
C
/*
|
|
* 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 1.59 2004/07/28 09:40:29 markus Exp $");
|
|
|
|
#include "xmalloc.h"
|
|
#include "rsa.h"
|
|
#include "ssh1.h"
|
|
#include "packet.h"
|
|
#include "buffer.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"
|
|
#include "buffer.h"
|
|
|
|
/* import */
|
|
extern ServerOptions options;
|
|
extern Buffer loginmsg;
|
|
|
|
/*
|
|
* 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";
|
|
}
|
|
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 prev, type = 0;
|
|
|
|
debug("Attempting authentication for %s%.100s.",
|
|
authctxt->valid ? "" : "invalid user ", authctxt->user);
|
|
|
|
/* If the user has no password, accept authentication immediately. */
|
|
if (options.password_authentication &&
|
|
#ifdef KRB5
|
|
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
|
|
#endif
|
|
PRIVSEP(auth_password(authctxt, ""))) {
|
|
#ifdef USE_PAM
|
|
if (options.use_pam && (PRIVSEP(do_pam_account())))
|
|
#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. */
|
|
prev = type;
|
|
type = packet_read();
|
|
|
|
/*
|
|
* If we started challenge-response authentication but the
|
|
* next packet is not a response to our challenge, release
|
|
* the resources allocated by get_challenge() (which would
|
|
* normally have been released by verify_response() had we
|
|
* received such a response)
|
|
*/
|
|
if (prev == SSH_CMSG_AUTH_TIS &&
|
|
type != SSH_CMSG_AUTH_TIS_RESPONSE)
|
|
abandon_challenge_response(authctxt);
|
|
|
|
/* Process the packet. */
|
|
switch (type) {
|
|
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(authctxt, client_user,
|
|
client_host_key);
|
|
key_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. */
|
|
if ((n = BN_new()) == NULL)
|
|
fatal("do_authloop: BN_new failed");
|
|
packet_get_bignum(n);
|
|
packet_check_eom();
|
|
authenticated = auth_rsa(authctxt, 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);
|
|
|
|
#ifdef _UNICOS
|
|
if (authenticated && cray_access_denied(authctxt->user)) {
|
|
authenticated = 0;
|
|
fatal("Access denied for user %s.",authctxt->user);
|
|
}
|
|
#endif /* _UNICOS */
|
|
|
|
#ifdef HAVE_CYGWIN
|
|
if (authenticated &&
|
|
!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,
|
|
authctxt->pw)) {
|
|
packet_disconnect("Authentication rejected for uid %d.",
|
|
authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid);
|
|
authenticated = 0;
|
|
}
|
|
#else
|
|
/* Special handling for root */
|
|
if (authenticated && authctxt->pw->pw_uid == 0 &&
|
|
!auth_root_allowed(get_authname(type))) {
|
|
authenticated = 0;
|
|
# ifdef SSH_AUDIT_EVENTS
|
|
PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
|
|
# endif
|
|
}
|
|
#endif
|
|
|
|
#ifdef USE_PAM
|
|
if (options.use_pam && authenticated &&
|
|
!PRIVSEP(do_pam_account())) {
|
|
char *msg;
|
|
size_t len;
|
|
|
|
error("Access denied for user %s by PAM account "
|
|
"configuration", authctxt->user);
|
|
len = buffer_len(&loginmsg);
|
|
buffer_append(&loginmsg, "\0", 1);
|
|
msg = buffer_ptr(&loginmsg);
|
|
/* strip trailing newlines */
|
|
if (len > 0)
|
|
while (len > 0 && msg[--len] == '\n')
|
|
msg[len] = '\0';
|
|
else
|
|
msg = "Access denied.";
|
|
packet_disconnect(msg);
|
|
}
|
|
#endif
|
|
|
|
/* Log before sending the reply */
|
|
auth_log(authctxt, authenticated, get_authname(type), info);
|
|
|
|
if (client_user != NULL) {
|
|
xfree(client_user);
|
|
client_user = NULL;
|
|
}
|
|
|
|
if (authenticated)
|
|
return;
|
|
|
|
if (authctxt->failures++ > options.max_authtries) {
|
|
#ifdef SSH_AUDIT_EVENTS
|
|
PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
|
|
#endif
|
|
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.
|
|
*/
|
|
void
|
|
do_authentication(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';
|
|
|
|
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: invalid user %s", user);
|
|
authctxt->pw = fakepw();
|
|
}
|
|
|
|
setproctitle("%s%s", authctxt->valid ? user : "unknown",
|
|
use_privsep ? " [net]" : "");
|
|
|
|
#ifdef USE_PAM
|
|
if (options.use_pam)
|
|
PRIVSEP(start_pam(authctxt));
|
|
#endif
|
|
|
|
/*
|
|
* If we are not running as root, the user must have the same uid as
|
|
* the server. (Unless you are running Windows)
|
|
*/
|
|
#ifndef HAVE_CYGWIN
|
|
if (!use_privsep && getuid() != 0 && authctxt->pw &&
|
|
authctxt->pw->pw_uid != getuid())
|
|
packet_disconnect("Cannot change user when server not running as root.");
|
|
#endif
|
|
|
|
/*
|
|
* 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();
|
|
}
|