+/* $OpenBSD: auth2-gss.c,v 1.16 2007/10/29 00:52:45 dtucker Exp $ */
+
/*
- * Copyright (c) 2001,2002 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
#include "includes.h"
#ifdef GSSAPI
+
+#include <sys/types.h>
+
+#include <stdarg.h>
+
+#include "xmalloc.h"
+#include "key.h"
+#include "hostfile.h"
#include "auth.h"
#include "ssh2.h"
-#include "ssh1.h"
-#include "xmalloc.h"
#include "log.h"
#include "dispatch.h"
+#include "buffer.h"
#include "servconf.h"
-#include "compat.h"
#include "packet.h"
-#include "monitor_wrap.h"
-
#include "ssh-gss.h"
+#include "monitor_wrap.h"
extern ServerOptions options;
-extern unsigned char ssh1_key_digest[16];
+static void ssh_gssapi_userauth_error(Gssctxt *ctxt);
+static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
+static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
+static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
+static void input_gssapi_errtok(int, u_int32_t, void *);
+
+/*
+ * The 'gssapi_keyex' userauth mechanism.
+ */
static int
-userauth_external(Authctxt *authctxt)
+userauth_gsskeyex(Authctxt *authctxt)
{
- packet_check_eom();
+ int authenticated = 0;
+ Buffer b, b2;
+ gss_buffer_desc mic, gssbuf, gssbuf2;
+ u_int len;
- return(PRIVSEP(ssh_gssapi_userok(authctxt->user)));
-}
+ mic.value = packet_get_string(&len);
+ mic.length = len;
-static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
-static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
+ packet_check_eom();
+
+ ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
+ "gssapi-keyex");
+
+ gssbuf.value = buffer_ptr(&b);
+ gssbuf.length = buffer_len(&b);
+
+ /* client may have used empty username to determine target
+ name from GSSAPI context */
+ ssh_gssapi_buildmic(&b2, "", authctxt->service, "gssapi-keyex");
-/* We only support those mechanisms that we know about (ie ones that we know
- * how to check local user kuserok and the like
+ gssbuf2.value = buffer_ptr(&b2);
+ gssbuf2.length = buffer_len(&b2);
+
+ /* gss_kex_context is NULL with privsep, so we can't check it here */
+ if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
+ &gssbuf, &mic))) ||
+ !GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
+ &gssbuf2, &mic)))) {
+ if (authctxt->valid && authctxt->user && authctxt->user[0]) {
+ authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
+ authctxt->pw,
+ 1 /* gssapi-keyex */));
+ }
+ }
+
+ buffer_free(&b);
+ buffer_free(&b2);
+ xfree(mic.value);
+
+ return (authenticated);
+}
+
+/*
+ * We only support those mechanisms that we know about (ie ones that we know
+ * how to check local user kuserok and the like)
*/
static int
userauth_gssapi(Authctxt *authctxt)
{
- gss_OID_desc oid= {0,NULL};
- Gssctxt *ctxt = NULL;
- int mechs;
- gss_OID_set supported;
- int present;
- OM_uint32 ms;
- u_int len;
-
- if (!authctxt->valid || authctxt->user == NULL)
- return 0;
-
- if (datafellows & SSH_OLD_GSSAPI) {
- debug("Early drafts of GSSAPI userauth not supported");
- return 0;
- }
-
- mechs=packet_get_int();
- if (mechs==0) {
- debug("Mechanism negotiation is not supported");
- return 0;
- }
+ gss_OID_desc goid = {0, NULL};
+ Gssctxt *ctxt = NULL;
+ int mechs;
+ gss_OID_set supported;
+ int present;
+ OM_uint32 ms;
+ u_int len;
+ u_char *doid = NULL;
- ssh_gssapi_supported_oids(&supported);
- do {
- if (oid.elements)
- xfree(oid.elements);
- oid.elements = packet_get_string(&len);
- oid.length = len;
- gss_test_oid_set_member(&ms, &oid, supported, &present);
- mechs--;
- } while (mechs>0 && !present);
-
- if (!present) {
- xfree(oid.elements);
- return(0);
- }
-
- if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt,&oid))))
- return(0);
-
- authctxt->methoddata=(void *)ctxt;
+ /* authctxt->valid may be 0 if we haven't yet determined
+ username from gssapi context. */
- /* Send SSH_MSG_USERAUTH_GSSAPI_RESPONSE */
+ if (authctxt->user == NULL)
+ return (0);
+
+ mechs = packet_get_int();
+ if (mechs == 0) {
+ debug("Mechanism negotiation is not supported");
+ return (0);
+ }
+
+ ssh_gssapi_supported_oids(&supported);
+ do {
+ mechs--;
+
+ if (doid)
+ xfree(doid);
+
+ present = 0;
+ doid = packet_get_string(&len);
+
+ if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
+ doid[1] == len - 2) {
+ goid.elements = doid + 2;
+ goid.length = len - 2;
+ gss_test_oid_set_member(&ms, &goid, supported,
+ &present);
+ } else {
+ logit("Badly formed OID received");
+ }
+ } while (mechs > 0 && !present);
+
+ gss_release_oid_set(&ms, &supported);
+
+ if (!present) {
+ xfree(doid);
+ authctxt->server_caused_failure = 1;
+ return (0);
+ }
+
+ if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
+ if (ctxt != NULL)
+ ssh_gssapi_delete_ctx(&ctxt);
+ xfree(doid);
+ authctxt->server_caused_failure = 1;
+ return (0);
+ }
+
+ authctxt->methoddata = (void *)ctxt;
- if (!compat20)
- packet_start(SSH_SMSG_AUTH_GSSAPI_RESPONSE);
- else
packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
- packet_put_string(oid.elements,oid.length);
- packet_send();
- packet_write_wait();
- xfree(oid.elements);
-
- if (!compat20)
- dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN,
- &input_gssapi_token);
- else
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN,
- &input_gssapi_token);
- authctxt->postponed = 1;
-
- return 0;
+
+ /* Return the OID that we received */
+ packet_put_string(doid, len);
+
+ packet_send();
+ xfree(doid);
+
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
+ authctxt->postponed = 1;
+
+ return (0);
}
static void
input_gssapi_token(int type, u_int32_t plen, void *ctxt)
{
- Authctxt *authctxt = ctxt;
- Gssctxt *gssctxt;
- gss_buffer_desc send_tok,recv_tok;
- OM_uint32 maj_status, min_status;
- int len;
-
- if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
- fatal("No authentication or GSSAPI context");
-
- gssctxt=authctxt->methoddata;
- recv_tok.value=packet_get_string(&len);
- recv_tok.length=len; /* int vs. size_t */
-
- maj_status=PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
- &send_tok, NULL));
- packet_check_eom();
-
- if (send_tok.length != 0) {
- /* Send a packet back to the client */
- if (!compat20)
- packet_start(SSH_MSG_AUTH_GSSAPI_TOKEN);
- else
- packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
- packet_put_string(send_tok.value,send_tok.length);
- packet_send();
- packet_write_wait();
- gss_release_buffer(&min_status, &send_tok);
- }
-
- if (GSS_ERROR(maj_status)) {
- /* Failure <sniff> */
- ssh_gssapi_send_error(gssctxt->oid,maj_status,min_status);
- authctxt->postponed = 0;
- dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, NULL);
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
- userauth_finish(authctxt, 0, "gssapi");
- }
-
- if (maj_status == GSS_S_COMPLETE) {
- dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, NULL);
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN,NULL);
- /* ssh1 does not have an extra message here */
- if (!compat20)
- input_gssapi_exchange_complete(0, 0, ctxt);
- else
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
- &input_gssapi_exchange_complete);
+ Authctxt *authctxt = ctxt;
+ Gssctxt *gssctxt;
+ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+ gss_buffer_desc recv_tok;
+ OM_uint32 maj_status, min_status, flags=0;
+ u_int len;
+
+ if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
+ fatal("No authentication or GSSAPI context");
+
+ gssctxt = authctxt->methoddata;
+ recv_tok.value = packet_get_string(&len);
+ recv_tok.length = len; /* u_int vs. size_t */
+
+ packet_check_eom();
+
+ maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
+ &send_tok, &flags));
+
+ xfree(recv_tok.value);
+
+ if (GSS_ERROR(maj_status)) {
+ ssh_gssapi_userauth_error(gssctxt);
+ if (send_tok.length != 0) {
+ packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
+ packet_put_string(send_tok.value, send_tok.length);
+ packet_send();
+ }
+ authctxt->postponed = 0;
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ userauth_finish(authctxt, 0, "gssapi-with-mic");
+ } else {
+ if (send_tok.length != 0) {
+ packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
+ packet_put_string(send_tok.value, send_tok.length);
+ packet_send();
+ }
+ if (maj_status == GSS_S_COMPLETE) {
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ if (flags & GSS_C_INTEG_FLAG)
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
+ &input_gssapi_mic);
+ else
+ dispatch_set(
+ SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
+ &input_gssapi_exchange_complete);
+ }
+ }
+
+ gss_release_buffer(&min_status, &send_tok);
+}
+
+static void
+input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
+{
+ Authctxt *authctxt = ctxt;
+ Gssctxt *gssctxt;
+ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+ gss_buffer_desc recv_tok;
+ OM_uint32 maj_status;
+ u_int len;
+
+ if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
+ fatal("No authentication or GSSAPI context");
+
+ gssctxt = authctxt->methoddata;
+ recv_tok.value = packet_get_string(&len);
+ recv_tok.length = len;
+
+ packet_check_eom();
+
+ /* Push the error token into GSSAPI to see what it says */
+ maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
+ &send_tok, NULL));
+
+ xfree(recv_tok.value);
+
+ /* We can't return anything to the client, even if we wanted to */
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
+
+ /* The client will have already moved on to the next auth */
+
+ gss_release_buffer(&maj_status, &send_tok);
+}
+
+static void
+gssapi_set_username(Authctxt *authctxt)
+{
+ char *lname = NULL;
+
+ if ((authctxt->user == NULL) || (authctxt->user[0] == '\0')) {
+ PRIVSEP(ssh_gssapi_localname(&lname));
+ if (lname && lname[0] != '\0') {
+ if (authctxt->user) xfree(authctxt->user);
+ authctxt->user = lname;
+ debug("set username to %s from gssapi context", lname);
+ authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user));
+ if (authctxt->pw) {
+ authctxt->valid = 1;
+#ifdef USE_PAM
+ if (options.use_pam)
+ PRIVSEP(start_pam(authctxt));
+#endif
+ }
+ } else {
+ debug("failed to set username from gssapi context");
+ packet_send_debug("failed to set username from gssapi context");
}
+ }
}
-/* This is called when the client thinks we've completed authentication.
+/*
+ * This is called when the client thinks we've completed authentication.
* It should only be enabled in the dispatch handler by the function above,
* which only enables it once the GSSAPI exchange is complete.
*/
-
+
static void
input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
{
- Authctxt *authctxt = ctxt;
- Gssctxt *gssctxt;
- int authenticated;
-
+ Authctxt *authctxt = ctxt;
+ Gssctxt *gssctxt;
+ int authenticated;
+
if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
- fatal("No authentication or GSSAPI context");
-
- if ((strcmp(authctxt->user, "") == 0) && (authctxt->pw == NULL)) {
- char *lname = NULL;
- PRIVSEP(ssh_gssapi_localname(&lname));
- if (lname && lname[0] != '\0') {
- xfree(authctxt->user);
- authctxt->user = lname;
- debug("set username to %s from gssapi context", lname);
- authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user));
- } else {
- debug("failed to set username from gssapi context");
- }
- }
- if (authctxt->pw) {
-#ifdef USE_PAM
- PRIVSEP(start_pam(authctxt->pw->pw_name));
-#endif
+ fatal("No authentication or GSSAPI context");
+
+ gssapi_set_username(authctxt);
+
+ gssctxt = authctxt->methoddata;
+
+ /*
+ * We don't need to check the status, because we're only enabled in
+ * the dispatcher once the exchange is complete
+ */
+
+ packet_check_eom();
+
+ /* user should be set if valid but we double-check here */
+ if (authctxt->valid && authctxt->user && authctxt->user[0]) {
+ authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
+ authctxt->pw, 0 /* !gssapi-keyex */));
} else {
- authctxt->valid = 0;
authenticated = 0;
- goto finish;
}
- gssctxt=authctxt->methoddata;
+ authctxt->postponed = 0;
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
+ userauth_finish(authctxt, authenticated, "gssapi-with-mic");
+}
- /* ssh1 needs to exchange the hash of the keys */
- if (!compat20) {
+static void
+input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
+{
+ Authctxt *authctxt = ctxt;
+ Gssctxt *gssctxt;
+ int authenticated = 0;
+ Buffer b;
+ gss_buffer_desc mic, gssbuf;
+ u_int len;
- OM_uint32 min_status;
- gss_buffer_desc dummy, msg_tok;
+ if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
+ fatal("No authentication or GSSAPI context");
- /* ssh1 wraps the keys, in the monitor */
+ gssctxt = authctxt->methoddata;
- dummy.value=malloc(sizeof(ssh1_key_digest));
- memcpy(dummy.value,ssh1_key_digest,sizeof(ssh1_key_digest));
- dummy.length=sizeof(ssh1_key_digest);
- if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(gssctxt,&dummy,&msg_tok))))
- fatal("Couldn't wrap keys");
-
- packet_start(SSH_SMSG_AUTH_GSSAPI_HASH);
- packet_put_string((char *)msg_tok.value,msg_tok.length);
- packet_send();
- packet_write_wait();
- gss_release_buffer(&min_status,&msg_tok);
- }
+ mic.value = packet_get_string(&len);
+ mic.length = len;
-
- /* We don't need to check the status, because the stored credentials
- * which userok uses are only populated once the context init step
- * has returned complete.
- */
+ ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
+ "gssapi-with-mic");
+
+ gssbuf.value = buffer_ptr(&b);
+ gssbuf.length = buffer_len(&b);
- authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
+ gssapi_set_username(authctxt);
-finish:
- authctxt->postponed = 0;
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
- dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
- userauth_finish(authctxt, authenticated, "gssapi");
+ if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
+ if (authctxt->valid && authctxt->user && authctxt->user[0]) {
+ authenticated =
+ PRIVSEP(ssh_gssapi_userok(authctxt->user, authctxt->pw,
+ 0 /* !gssapi-keyex */));
+ } else {
+ authenticated = 0;
+ }
+ else
+ logit("GSSAPI MIC check failed");
+
+ buffer_free(&b);
+ xfree(mic.value);
+
+ authctxt->postponed = 0;
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
+ dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
+ userauth_finish(authctxt, authenticated, "gssapi-with-mic");
+}
+
+static void ssh_gssapi_userauth_error(Gssctxt *ctxt) {
+ char *errstr;
+ OM_uint32 maj,min;
+
+ errstr=PRIVSEP(ssh_gssapi_last_error(ctxt,&maj,&min));
+ if (errstr) {
+ packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERROR);
+ packet_put_int(maj);
+ packet_put_int(min);
+ packet_put_cstring(errstr);
+ packet_put_cstring("");
+ packet_send();
+ packet_write_wait();
+ xfree(errstr);
+ }
}
-Authmethod method_external = {
- "external-keyx",
- userauth_external,
+Authmethod method_gsskeyex = {
+ "gssapi-keyex",
+ userauth_gsskeyex,
&options.gss_authentication
};
-
+
Authmethod method_gssapi = {
- "gssapi",
- userauth_gssapi,
- &options.gss_authentication
+ "gssapi-with-mic",
+ userauth_gssapi,
+ &options.gss_authentication
};
#endif /* GSSAPI */
andersk / gssapi-openssh.git / blobdiff