+/* $OpenBSD: auth1.c,v 1.73 2008/07/04 23:30:16 djm Exp $ */
/*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*/
#include "includes.h"
-RCSID("$OpenBSD: auth1.c,v 1.43 2002/09/09 06:48:06 itojun Exp $");
+#include <sys/types.h>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <pwd.h>
+
+#include "openbsd-compat/sys-queue.h"
#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 "key.h"
+#include "hostfile.h"
#include "auth.h"
#include "channels.h"
#include "session.h"
#include "uidswap.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
#include "monitor_wrap.h"
+#include "buffer.h"
/* import */
extern ServerOptions options;
+extern Buffer loginmsg;
+
+static int auth1_process_password(Authctxt *, char *, size_t);
+static int auth1_process_rsa(Authctxt *, char *, size_t);
+static int auth1_process_rhosts_rsa(Authctxt *, char *, size_t);
+static int auth1_process_tis_challenge(Authctxt *, char *, size_t);
+static int auth1_process_tis_response(Authctxt *, char *, size_t);
+
+static char *client_user = NULL; /* Used to fill in remote user for PAM */
+
+struct AuthMethod1 {
+ int type;
+ char *name;
+ int *enabled;
+ int (*method)(Authctxt *, char *, size_t);
+};
+
+const struct AuthMethod1 auth1_methods[] = {
+ {
+ SSH_CMSG_AUTH_PASSWORD, "password",
+ &options.password_authentication, auth1_process_password
+ },
+ {
+ SSH_CMSG_AUTH_RSA, "rsa",
+ &options.rsa_authentication, auth1_process_rsa
+ },
+ {
+ SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
+ &options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
+ },
+ {
+ SSH_CMSG_AUTH_TIS, "challenge-response",
+ &options.challenge_response_authentication,
+ auth1_process_tis_challenge
+ },
+ {
+ SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
+ &options.challenge_response_authentication,
+ auth1_process_tis_response
+ },
+ { -1, NULL, NULL, NULL}
+};
+
+static const struct AuthMethod1
+*lookup_authmethod1(int type)
+{
+ int i;
+
+ for (i = 0; auth1_methods[i].name != NULL; i++)
+ if (auth1_methods[i].type == type)
+ return (&(auth1_methods[i]));
+
+ return (NULL);
+}
-/*
- * 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
+ const struct AuthMethod1 *a;
+ static char buf[64];
+
+ if ((a = lookup_authmethod1(type)) != NULL)
+ return (a->name);
+ snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
+ return (buf);
+}
+
+/*ARGSUSED*/
+static int
+auth1_process_password(Authctxt *authctxt, char *info, size_t infolen)
+{
+ int authenticated = 0;
+ char *password;
+ u_int dlen;
+
+ /*
+ * 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, dlen);
+ xfree(password);
+
+ return (authenticated);
+}
+
+/*ARGSUSED*/
+static int
+auth1_process_rsa(Authctxt *authctxt, char *info, size_t infolen)
+{
+ int authenticated = 0;
+ BIGNUM *n;
+
+ /* 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);
+
+ return (authenticated);
+}
+
+/*ARGSUSED*/
+static int
+auth1_process_rhosts_rsa(Authctxt *authctxt, char *info, size_t infolen)
+{
+ int keybits, authenticated = 0;
+ u_int bits;
+ Key *client_host_key;
+ u_int ulen;
+
+ /*
+ * 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);
+
+ keybits = BN_num_bits(client_host_key->rsa->n);
+ if (keybits < 0 || bits != (u_int)keybits) {
+ verbose("Warning: keysize mismatch for client_host_key: "
+ "actual %d, announced %d",
+ BN_num_bits(client_host_key->rsa->n), bits);
}
- snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
- return buf;
+ packet_check_eom();
+
+ authenticated = auth_rhosts_rsa(authctxt, client_user,
+ client_host_key);
+ key_free(client_host_key);
+
+ snprintf(info, infolen, " ruser %.100s", client_user);
+
+ return (authenticated);
+}
+
+/*ARGSUSED*/
+static int
+auth1_process_tis_challenge(Authctxt *authctxt, char *info, size_t infolen)
+{
+ char *challenge;
+
+ if ((challenge = get_challenge(authctxt)) == NULL)
+ return (0);
+
+ debug("sending challenge '%s'", challenge);
+ packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
+ packet_put_cstring(challenge);
+ xfree(challenge);
+ packet_send();
+ packet_write_wait();
+
+ return (-1);
+}
+
+/*ARGSUSED*/
+static int
+auth1_process_tis_response(Authctxt *authctxt, char *info, size_t infolen)
+{
+ int authenticated = 0;
+ char *response;
+ u_int dlen;
+
+ response = packet_get_string(&dlen);
+ packet_check_eom();
+ authenticated = verify_response(authctxt, response);
+ memset(response, 'r', dlen);
+ xfree(response);
+
+ return (authenticated);
}
/*
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;
+ int prev = 0, type = 0;
+ const struct AuthMethod1 *meth;
debug("Attempting authentication for %s%.100s.",
- authctxt->valid ? "" : "illegal user ", authctxt->user);
+ authctxt->valid ? "" : "invalid user ", authctxt->user);
/* If the user has no password, accept authentication immediately. */
if (options.password_authentication &&
-#if defined(KRB4) || defined(KRB5)
+#ifdef KRB5
(!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
PRIVSEP(auth_password(authctxt, ""))) {
- auth_log(authctxt, 1, "without authentication", "");
- return;
+#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_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();
- /* 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;
-
- tkt.length = dlen;
- if (tkt.length < MAX_KTXT_LEN)
- memcpy(tkt.dat, kdata, tkt.length);
-
- if (auth_krb4(authctxt, &tkt, &client_user)) {
- authenticated = 1;
- snprintf(info, sizeof(info),
- " tktuser %.100s",
- 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);
- }
-#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);
- 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);
- 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);
- debug("got response '%s'", response);
- 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.
- */
- log("Unknown message during authentication: type %d", type);
- break;
+ /*
+ * 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);
+
+ if (authctxt->failures >= options.max_authtries)
+ goto skip;
+ if ((meth = lookup_authmethod1(type)) == NULL) {
+ logit("Unknown message during authentication: "
+ "type %d", type);
+ goto skip;
+ }
+
+ if (!*(meth->enabled)) {
+ verbose("%s authentication disabled.", meth->name);
+ goto skip;
}
+
+ authenticated = meth->method(authctxt, info, sizeof(info));
+ if (authenticated == -1)
+ continue; /* "postponed" */
+
#ifdef BSD_AUTH
if (authctxt->as) {
auth_close(authctxt->as);
fatal("INTERNAL ERROR: authenticated invalid user %s",
authctxt->user);
-#ifdef HAVE_CYGWIN
- if (authenticated &&
- !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
- packet_disconnect("Authentication rejected for uid %d.",
- pw == NULL ? -1 : pw->pw_uid);
+#ifdef _UNICOS
+ if (authenticated && cray_access_denied(authctxt->user)) {
authenticated = 0;
+ fatal("Access denied for user %s.",authctxt->user);
}
-#else
+#endif /* _UNICOS */
+
+#ifndef HAVE_CYGWIN
/* Special handling for root */
- if (!use_privsep &&
- authenticated && authctxt->pw->pw_uid == 0 &&
- !auth_root_allowed(get_authname(type)))
- authenticated = 0;
+ if (authenticated && authctxt->pw->pw_uid == 0 &&
+ !auth_root_allowed(meth->name)) {
+ authenticated = 0;
+# ifdef SSH_AUDIT_EVENTS
+ PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
+# endif
+ }
#endif
+
#ifdef USE_PAM
- if (!use_privsep && authenticated &&
- !do_pam_account(pw->pw_name, client_user))
- authenticated = 0;
+ 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("%s", msg);
+ }
#endif
+ skip:
/* Log before sending the reply */
auth_log(authctxt, authenticated, get_authname(type), info);
if (authenticated)
return;
- if (authctxt->failures++ > AUTH_FAIL_MAX) {
+ 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);
}
* Performs authentication of an incoming connection. Session key has already
* been exchanged and encryption is enabled.
*/
-Authctxt *
-do_authentication(void)
+void
+do_authentication(Authctxt *authctxt)
{
- Authctxt *authctxt;
u_int ulen;
char *user, *style = NULL;
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);
+ else {
+ debug("do_authentication: invalid user %s", user);
+ authctxt->pw = fakepw();
+ }
- setproctitle("%s%s", authctxt->pw ? user : "unknown",
+ setproctitle("%s%s", authctxt->valid ? user : "unknown",
use_privsep ? " [net]" : "");
#ifdef USE_PAM
- PRIVSEP(start_pam(authctxt->pw == NULL ? "NOUSER" : user));
+ 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)
+ * the server.
*/
#ifndef HAVE_CYGWIN
if (!use_privsep && getuid() != 0 && authctxt->pw &&
packet_start(SSH_SMSG_SUCCESS);
packet_send();
packet_write_wait();
-
- return (authctxt);
}
andersk / openssh.git / blobdiff