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323 lines
8.6 KiB
C
323 lines
8.6 KiB
C
/*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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RCSID("$OpenBSD: auth2.c,v 1.107 2004/07/28 09:40:29 markus Exp $");
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#include "ssh2.h"
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#include "xmalloc.h"
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#include "packet.h"
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#include "log.h"
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#include "servconf.h"
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#include "compat.h"
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#include "auth.h"
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#include "dispatch.h"
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#include "pathnames.h"
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#include "monitor_wrap.h"
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#include "buffer.h"
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#ifdef GSSAPI
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#include "ssh-gss.h"
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#endif
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/* import */
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extern ServerOptions options;
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extern u_char *session_id2;
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extern u_int session_id2_len;
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extern Buffer loginmsg;
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/* methods */
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extern Authmethod method_none;
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extern Authmethod method_pubkey;
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extern Authmethod method_passwd;
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extern Authmethod method_kbdint;
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extern Authmethod method_hostbased;
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#ifdef GSSAPI
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extern Authmethod method_gssapi;
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#endif
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Authmethod *authmethods[] = {
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&method_none,
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&method_pubkey,
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#ifdef GSSAPI
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&method_gssapi,
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#endif
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&method_passwd,
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&method_kbdint,
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&method_hostbased,
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NULL
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};
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/* protocol */
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static void input_service_request(int, u_int32_t, void *);
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static void input_userauth_request(int, u_int32_t, void *);
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/* helper */
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static Authmethod *authmethod_lookup(const char *);
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static char *authmethods_get(void);
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int user_key_allowed(struct passwd *, Key *);
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/*
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* loop until authctxt->success == TRUE
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*/
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void
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do_authentication2(Authctxt *authctxt)
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{
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/* challenge-response is implemented via keyboard interactive */
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if (options.challenge_response_authentication)
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options.kbd_interactive_authentication = 1;
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dispatch_init(&dispatch_protocol_error);
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dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
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dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
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}
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static void
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input_service_request(int type, u_int32_t seq, void *ctxt)
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{
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Authctxt *authctxt = ctxt;
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u_int len;
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int acceptit = 0;
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char *service = packet_get_string(&len);
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packet_check_eom();
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if (authctxt == NULL)
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fatal("input_service_request: no authctxt");
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if (strcmp(service, "ssh-userauth") == 0) {
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if (!authctxt->success) {
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acceptit = 1;
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/* now we can handle user-auth requests */
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dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
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}
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}
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/* XXX all other service requests are denied */
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if (acceptit) {
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packet_start(SSH2_MSG_SERVICE_ACCEPT);
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packet_put_cstring(service);
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packet_send();
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packet_write_wait();
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} else {
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debug("bad service request %s", service);
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packet_disconnect("bad service request %s", service);
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}
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xfree(service);
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}
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static void
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input_userauth_request(int type, u_int32_t seq, void *ctxt)
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{
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Authctxt *authctxt = ctxt;
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Authmethod *m = NULL;
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char *user, *service, *method, *style = NULL;
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int authenticated = 0;
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if (authctxt == NULL)
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fatal("input_userauth_request: no authctxt");
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user = packet_get_string(NULL);
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service = packet_get_string(NULL);
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method = packet_get_string(NULL);
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debug("userauth-request for user %s service %s method %s", user, service, method);
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debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
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if ((style = strchr(user, ':')) != NULL)
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*style++ = 0;
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if (authctxt->attempt++ == 0) {
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/* setup auth context */
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authctxt->pw = PRIVSEP(getpwnamallow(user));
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authctxt->user = xstrdup(user);
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if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
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authctxt->valid = 1;
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debug2("input_userauth_request: setting up authctxt for %s", user);
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#ifdef USE_PAM
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if (options.use_pam)
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PRIVSEP(start_pam(authctxt));
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#endif
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} else {
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logit("input_userauth_request: invalid user %s", user);
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authctxt->pw = fakepw();
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#ifdef USE_PAM
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if (options.use_pam)
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PRIVSEP(start_pam(authctxt));
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#endif
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#ifdef SSH_AUDIT_EVENTS
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PRIVSEP(audit_event(SSH_INVALID_USER));
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#endif
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}
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setproctitle("%s%s", authctxt->valid ? user : "unknown",
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use_privsep ? " [net]" : "");
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authctxt->service = xstrdup(service);
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authctxt->style = style ? xstrdup(style) : NULL;
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if (use_privsep)
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mm_inform_authserv(service, style);
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} else if (strcmp(user, authctxt->user) != 0 ||
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strcmp(service, authctxt->service) != 0) {
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packet_disconnect("Change of username or service not allowed: "
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"(%s,%s) -> (%s,%s)",
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authctxt->user, authctxt->service, user, service);
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}
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/* reset state */
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auth2_challenge_stop(authctxt);
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#ifdef GSSAPI
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
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#endif
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authctxt->postponed = 0;
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/* try to authenticate user */
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m = authmethod_lookup(method);
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if (m != NULL) {
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debug2("input_userauth_request: try method %s", method);
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authenticated = m->userauth(authctxt);
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}
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userauth_finish(authctxt, authenticated, method);
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xfree(service);
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xfree(user);
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xfree(method);
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}
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void
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userauth_finish(Authctxt *authctxt, int authenticated, char *method)
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{
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char *methods;
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if (!authctxt->valid && authenticated)
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fatal("INTERNAL ERROR: authenticated invalid user %s",
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authctxt->user);
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/* Special handling for root */
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if (authenticated && authctxt->pw->pw_uid == 0 &&
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!auth_root_allowed(method)) {
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authenticated = 0;
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#ifdef SSH_AUDIT_EVENTS
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PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
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#endif
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}
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#ifdef USE_PAM
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if (options.use_pam && authenticated) {
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if (!PRIVSEP(do_pam_account())) {
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/* if PAM returned a message, send it to the user */
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if (buffer_len(&loginmsg) > 0) {
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buffer_append(&loginmsg, "\0", 1);
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userauth_send_banner(buffer_ptr(&loginmsg));
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packet_write_wait();
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}
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fatal("Access denied for user %s by PAM account "
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"configuration", authctxt->user);
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}
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}
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#endif
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#ifdef _UNICOS
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if (authenticated && cray_access_denied(authctxt->user)) {
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authenticated = 0;
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fatal("Access denied for user %s.",authctxt->user);
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}
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#endif /* _UNICOS */
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/* Log before sending the reply */
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auth_log(authctxt, authenticated, method, " ssh2");
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if (authctxt->postponed)
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return;
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/* XXX todo: check if multiple auth methods are needed */
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if (authenticated == 1) {
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/* turn off userauth */
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dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
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packet_start(SSH2_MSG_USERAUTH_SUCCESS);
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packet_send();
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packet_write_wait();
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/* now we can break out */
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authctxt->success = 1;
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} else {
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if (authctxt->failures++ > options.max_authtries) {
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#ifdef SSH_AUDIT_EVENTS
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PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
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#endif
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packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
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}
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methods = authmethods_get();
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packet_start(SSH2_MSG_USERAUTH_FAILURE);
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packet_put_cstring(methods);
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packet_put_char(0); /* XXX partial success, unused */
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packet_send();
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packet_write_wait();
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xfree(methods);
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}
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}
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#define DELIM ","
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static char *
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authmethods_get(void)
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{
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Buffer b;
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char *list;
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int i;
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buffer_init(&b);
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for (i = 0; authmethods[i] != NULL; i++) {
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if (strcmp(authmethods[i]->name, "none") == 0)
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continue;
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if (authmethods[i]->enabled != NULL &&
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*(authmethods[i]->enabled) != 0) {
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if (buffer_len(&b) > 0)
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buffer_append(&b, ",", 1);
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buffer_append(&b, authmethods[i]->name,
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strlen(authmethods[i]->name));
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}
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}
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buffer_append(&b, "\0", 1);
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list = xstrdup(buffer_ptr(&b));
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buffer_free(&b);
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return list;
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}
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static Authmethod *
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authmethod_lookup(const char *name)
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{
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int i;
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if (name != NULL)
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for (i = 0; authmethods[i] != NULL; i++)
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if (authmethods[i]->enabled != NULL &&
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*(authmethods[i]->enabled) != 0 &&
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strcmp(name, authmethods[i]->name) == 0)
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return authmethods[i];
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debug2("Unrecognized authentication method name: %s",
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name ? name : "NULL");
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return NULL;
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}
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