[PATCH] Mutual authentication, keytabs, and SMB session keys
Luke Howard
lukeh at PADL.COM
Sun Feb 23 02:06:46 GMT 2003
The attach patch contains the following enhancements to HEAD:
1. Support for using Kerberos keytabs (configure with --enable-keytab)
instead of the secrets database, for the local machine password.
2. Mutual Kerberos GSS-API SPNEGO authentication.
3. Support for extracting the SMB session key from ticket session keys
(useful for named pipe services that might need access to the session
key)
Caveats: I haven't tested for MIT compat (although I have tried to avoid
any obvious breakage), and because ENCTYPE_ARCFOUR_HMAC_MD5 is an enum
in Heimdal, it should really be tested for in configure...
I have tested this patch with Windows 2000 and Windows XP clients. One
thing I didn't test is NTLMSSP over SPNEGO: hopefully I haven't broken
anything.
cheers,
-- Luke
-------------- next part --------------
Index: configure.in
===================================================================
RCS file: /cvsroot/samba/source/configure.in,v
retrieving revision 1.408
diff -u -r1.408 configure.in
--- configure.in 19 Feb 2003 13:24:06 -0000 1.408
+++ configure.in 23 Feb 2003 01:51:11 -0000
@@ -624,6 +624,15 @@
fi
############################################
+# support for using Kerberos keytab instead of secrets database
+
+AC_ARG_ENABLE(keytab,
+[ --enable-keytab Turn on support for Kerberos keytabs in lieu of secrets DB (default=no)],
+ [if eval "test x$enable_keytab = xyes"; then
+ AC_DEFINE(USE_KEYTAB,1,[Use Kerberos keytab])
+ fi])
+
+############################################
# we need dlopen/dlclose/dlsym/dlerror for PAM, the password database plugins and the plugin loading code
AC_SEARCH_LIBS(dlopen, [dl])
# dlopen/dlclose/dlsym/dlerror will be checked again later and defines will be set then
Index: libads/kerberos_verify.c
===================================================================
RCS file: /cvsroot/samba/source/libads/kerberos_verify.c,v
retrieving revision 1.6
diff -u -r1.6 kerberos_verify.c
--- libads/kerberos_verify.c 19 Feb 2003 01:16:40 -0000 1.6
+++ libads/kerberos_verify.c 23 Feb 2003 01:51:12 -0000
@@ -3,7 +3,7 @@
kerberos utility library
Copyright (C) Andrew Tridgell 2001
Copyright (C) Remus Koos 2001
-
+ Copyright (C) Luke Howard 2003
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -29,14 +29,18 @@
authorization_data if available
*/
NTSTATUS ads_verify_ticket(ADS_STRUCT *ads, const DATA_BLOB *ticket,
- char **principal, DATA_BLOB *auth_data)
+ char **principal, DATA_BLOB *auth_data,
+ DATA_BLOB *ap_rep,
+ uint8 session_key[16])
{
krb5_context context;
krb5_auth_context auth_context = NULL;
krb5_keytab keytab = NULL;
krb5_data packet;
krb5_ticket *tkt = NULL;
- int ret, i;
+ int ret;
+#ifndef USE_KEYTAB
+ int i;
krb5_keyblock * key;
krb5_principal host_princ;
char *host_princ_s;
@@ -44,8 +48,10 @@
char *password_s;
krb5_data password;
krb5_enctype *enctypes = NULL;
+#endif /* USE_KEYTAB */
BOOL auth_ok = False;
+#ifndef USE_KEYTAB
if (!secrets_init()) {
DEBUG(1,("secrets_init failed\n"));
return NT_STATUS_LOGON_FAILURE;
@@ -59,6 +65,7 @@
password.data = password_s;
password.length = strlen(password_s);
+#endif /* USE_KEYTAB */
ret = krb5_init_context(&context);
if (ret) {
@@ -81,6 +88,16 @@
return NT_STATUS_LOGON_FAILURE;
}
+#ifdef USE_KEYTAB
+ packet.length = ticket->length;
+ packet.data = (krb5_pointer)ticket->data;
+
+ if (!(ret = krb5_rd_req(context, &auth_context, &packet,
+ NULL, keytab, NULL, &tkt))) {
+ auth_ok = True;
+ }
+
+#else
fstrcpy(myname, global_myname());
strlower(myname);
asprintf(&host_princ_s, "HOST/%s@%s", myname, lp_realm());
@@ -119,13 +136,30 @@
}
}
+ SAFE_FREE(key);
+#endif /* USE_KEYTAB */
+
if (!auth_ok) {
DEBUG(3,("krb5_rd_req with auth failed (%s)\n",
error_message(ret)));
- SAFE_FREE(key);
return NT_STATUS_LOGON_FAILURE;
}
+ ret = krb5_mk_rep(context, auth_context, &packet);
+ if (ret) {
+ DEBUG(3,("Failed to generate mutual authentication reply (%s)\n",
+ error_message(ret)));
+ krb5_auth_con_free(context, auth_context);
+ return NT_STATUS_LOGON_FAILURE;
+ }
+
+ *ap_rep = data_blob(packet.data, packet.length);
+ free(packet.data);
+
+ krb5_get_smb_session_key(context, auth_context, session_key);
+ DEBUG(0,("SMB session key (from ticket) follows:\n"));
+ dump_data(0, session_key, 16);
+
#if 0
file_save("/tmp/ticket.dat", ticket->data, ticket->length);
#endif
@@ -134,20 +168,24 @@
#if 0
if (tkt->enc_part2) {
- file_save("/tmp/authdata.dat",
+ file_save("/tmp/authdata.dat",
tkt->enc_part2->authorization_data[0]->contents,
tkt->enc_part2->authorization_data[0]->length);
- }
#endif
if ((ret = krb5_unparse_name(context, get_principal_from_tkt(tkt),
principal))) {
DEBUG(3,("krb5_unparse_name failed (%s)\n",
error_message(ret)));
+ data_blob_free(auth_data);
+ data_blob_free(ap_rep);
+ krb5_auth_con_free(context, auth_context);
return NT_STATUS_LOGON_FAILURE;
}
+ krb5_auth_con_free(context, auth_context);
+
return NT_STATUS_OK;
}
-#endif
+#endif /* HAVE_KRB5 */
Index: libads/krb5_setpw.c
===================================================================
RCS file: /cvsroot/samba/source/libads/krb5_setpw.c,v
retrieving revision 1.13
diff -u -r1.13 krb5_setpw.c
--- libads/krb5_setpw.c 19 Feb 2003 20:37:34 -0000 1.13
+++ libads/krb5_setpw.c 23 Feb 2003 01:51:12 -0000
@@ -326,10 +326,12 @@
case KRB5_KPASSWD_ACCESSDENIED:
return KRB5KDC_ERR_BADOPTION;
break;
+#ifdef KV5M_ALT_METHOD
case KRB5_KPASSWD_INITIAL_FLAG_NEEDED:
return KRB5KDC_ERR_BADOPTION;
/* return KV5M_ALT_METHOD; MIT-only define */
break;
+#endif
case KRB5_KPASSWD_ETYPE_NOSUPP:
return KRB5KDC_ERR_ETYPE_NOSUPP;
break;
Index: libsmb/clikrb5.c
===================================================================
RCS file: /cvsroot/samba/source/libsmb/clikrb5.c,v
retrieving revision 1.32
diff -u -r1.32 clikrb5.c
--- libsmb/clikrb5.c 19 Feb 2003 15:46:15 -0000 1.32
+++ libsmb/clikrb5.c 23 Feb 2003 01:51:12 -0000
@@ -52,6 +52,10 @@
#if defined(HAVE_ADDR_TYPE_IN_KRB5_ADDRESS)
/* HEIMDAL */
+#define KRB5_KEY_TYPE(k) ((k)->keytype)
+#define KRB5_KEY_LENGTH(k) ((k)->keyvalue.length)
+#define KRB5_KEY_DATA(k) ((k)->keyvalue.data)
+
void setup_kaddr( krb5_address *pkaddr, struct sockaddr *paddr)
{
pkaddr->addr_type = KRB5_ADDRESS_INET;
@@ -60,6 +64,10 @@
}
#elif defined(HAVE_ADDRTYPE_IN_KRB5_ADDRESS)
/* MIT */
+#define KRB5_KEY_TYPE(k) ((k)->enctype)
+#define KRB5_KEY_LENGTH(k) ((k)->length)
+#define KRB5_KEY_DATA(k) ((k)->contents)
+
void setup_kaddr( krb5_address *pkaddr, struct sockaddr *paddr)
{
pkaddr->addrtype = ADDRTYPE_INET;
@@ -304,8 +312,8 @@
DATA_BLOB ret;
krb5_enctype enc_types[] = {
#ifdef ENCTYPE_ARCFOUR_HMAC
- ENCTYPE_ARCFOUR_HMAC,
-#endif
+ ENCTYPE_ARCFOUR_HMAC,
+#endif
ENCTYPE_DES_CBC_MD5,
ENCTYPE_DES_CBC_CRC,
ENCTYPE_NULL};
@@ -354,11 +362,39 @@
return data_blob(NULL, 0);
}
+ BOOL krb5_get_smb_session_key(krb5_context context, krb5_auth_context auth_context, uint8 session_key[16])
+ {
+ krb5_keyblock *skey;
+ BOOL ret = FALSE;
+
+ memset(session_key, 0, 16);
+
+#ifdef ENCTYPE_ARCFOUR_HMAC
+ /* NB: for this to work with Heimdal, -DENCTYPE_ARCFOUR_HMAC=ENCTYPE_ARCFOUR_HMAC_MD5 */
+ if (krb5_auth_con_getremotesubkey(context, auth_context, &skey) == 0 && skey != NULL) {
+ if (KRB5_KEY_TYPE(skey) == ENCTYPE_ARCFOUR_HMAC &&
+ KRB5_KEY_LENGTH(skey) == 16) {
+ memcpy(session_key, KRB5_KEY_DATA(skey), KRB5_KEY_LENGTH(skey));
+ ret = TRUE;
+ }
+ krb5_free_keyblock(context, skey);
+ }
+#endif /* ENCTYPE_ARCFOUR_HMAC */
+
+ return ret;
+ }
#else /* HAVE_KRB5 */
/* this saves a few linking headaches */
DATA_BLOB krb5_get_ticket(const char *principal, time_t time_offset)
{
DEBUG(0,("NO KERBEROS SUPPORT\n"));
return data_blob(NULL, 0);
+ }
+
+ BOOL krb5_get_smb_session_key(krb5_context context, krb5_auth_context ac, uint8 session_key[16])
+ {
+ DEBUG(0,("NO KERBEROS SUPPORT\n"));
+ memset(session_key, 0, 16);
+ return FALSE;
}
#endif
Index: libsmb/clispnego.c
===================================================================
RCS file: /cvsroot/samba/source/libsmb/clispnego.c,v
retrieving revision 1.28
diff -u -r1.28 clispnego.c
--- libsmb/clispnego.c 15 Feb 2003 12:20:22 -0000 1.28
+++ libsmb/clispnego.c 23 Feb 2003 01:51:12 -0000
@@ -3,6 +3,7 @@
simple kerberos5/SPNEGO routines
Copyright (C) Andrew Tridgell 2001
Copyright (C) Jim McDonough 2002
+ Copyright (C) Luke Howard 2003
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -259,16 +260,19 @@
/*
generate a krb5 GSS-API wrapper packet given a ticket
*/
-DATA_BLOB spnego_gen_krb5_wrap(DATA_BLOB ticket)
+DATA_BLOB spnego_gen_krb5_wrap(DATA_BLOB ticket, uint16 tok_id)
{
ASN1_DATA data;
DATA_BLOB ret;
+ char tok_id_data[2];
memset(&data, 0, sizeof(data));
asn1_push_tag(&data, ASN1_APPLICATION(0));
asn1_write_OID(&data, OID_KERBEROS5);
- asn1_write_BOOLEAN(&data, 0);
+
+ SSVAL(tok_id_data, 0, tok_id);
+ asn1_write(&data, tok_id_data, sizeof(tok_id_data));
asn1_write(&data, ticket.data, ticket.length);
asn1_pop_tag(&data);
@@ -286,24 +290,26 @@
/*
parse a krb5 GSS-API wrapper packet giving a ticket
*/
-BOOL spnego_parse_krb5_wrap(DATA_BLOB blob, DATA_BLOB *ticket)
+BOOL spnego_parse_krb5_wrap(DATA_BLOB blob, DATA_BLOB *ticket, uint16 *tok_id)
{
BOOL ret;
ASN1_DATA data;
int data_remaining;
+ char tok_id_data[2];
asn1_load(&data, blob);
asn1_start_tag(&data, ASN1_APPLICATION(0));
asn1_check_OID(&data, OID_KERBEROS5);
- asn1_check_BOOLEAN(&data, 0);
data_remaining = asn1_tag_remaining(&data);
- if (data_remaining < 1) {
+ if (data_remaining < 3) {
data.has_error = True;
} else {
-
- *ticket = data_blob(data.data, data_remaining);
+ asn1_read(&data, tok_id_data, 2);
+ *tok_id = SVAL(tok_id_data, 0);
+ data_remaining -= 2;
+ *ticket = data_blob(NULL, data_remaining);
asn1_read(&data, ticket->data, ticket->length);
}
@@ -330,7 +336,7 @@
tkt = krb5_get_ticket(principal, time_offset);
/* wrap that up in a nice GSS-API wrapping */
- tkt_wrapped = spnego_gen_krb5_wrap(tkt);
+ tkt_wrapped = spnego_gen_krb5_wrap(tkt, 0x0001);
/* and wrap that in a shiny SPNEGO wrapper */
targ = gen_negTokenTarg(krb_mechs, tkt_wrapped);
@@ -438,9 +444,10 @@
}
/*
- generate a minimal SPNEGO NTLMSSP response packet. Doesn't contain much.
+ generate a minimal SPNEGO response packet. Doesn't contain much.
*/
-DATA_BLOB spnego_gen_auth_response(DATA_BLOB *ntlmssp_reply, NTSTATUS nt_status)
+DATA_BLOB spnego_gen_auth_response(DATA_BLOB *reply, NTSTATUS nt_status,
+ const char *mechOID)
{
ASN1_DATA data;
DATA_BLOB ret;
@@ -462,13 +469,13 @@
asn1_write_enumerated(&data, negResult);
asn1_pop_tag(&data);
- if (negResult == SPNEGO_NEG_RESULT_INCOMPLETE) {
+ if (reply->data != NULL) {
asn1_push_tag(&data,ASN1_CONTEXT(1));
- asn1_write_OID(&data, OID_NTLMSSP);
+ asn1_write_OID(&data, mechOID);
asn1_pop_tag(&data);
asn1_push_tag(&data,ASN1_CONTEXT(2));
- asn1_write_OctetString(&data, ntlmssp_reply->data, ntlmssp_reply->length);
+ asn1_write_OctetString(&data, reply->data, reply->length);
asn1_pop_tag(&data);
}
Index: passdb/secrets.c
===================================================================
RCS file: /cvsroot/samba/source/passdb/secrets.c,v
retrieving revision 1.54
diff -u -r1.54 secrets.c
--- passdb/secrets.c 1 Feb 2003 04:39:15 -0000 1.54
+++ passdb/secrets.c 23 Feb 2003 01:51:13 -0000
@@ -221,6 +221,66 @@
return True;
}
+#ifdef USE_KEYTAB
+/************************************************************************
+ Read local secret from the keytab
+************************************************************************/
+
+static BOOL secrets_fetch_keytab_password(uint8 ret_pwd[16], time_t *pass_last_set_time)
+{
+ char spn[MAXHOSTNAMELEN + 2], *p;
+ krb5_context context;
+ krb5_error_code ret;
+ krb5_principal princ;
+ krb5_keyblock *key;
+
+ ret = krb5_init_context(&context);
+ if (ret) {
+ DEBUG(1, ("secrets_fetch_keytab_password: failed to initialize Kerberos context\n"));
+ return FALSE;
+ }
+
+ spn[sizeof(spn) - 1] = '\0';
+ if (gethostname(spn, sizeof(spn) - 2) < 0) {
+ DEBUG(1, ("secrets_fetch_keytab_password: could not determine local hostname\n"));
+ krb5_free_context(context);
+ return FALSE;
+ }
+
+ for (p = spn; *p && *p != '.'; p++)
+ *p = toupper(*p);
+ *p++ = '$';
+ *p = '\0';
+
+ ret = krb5_parse_name(context, spn, &princ);
+ if (ret) {
+ DEBUG(1, ("secrets_fetch_keytab_password: failed to parse name %s\n", spn));
+ krb5_free_context(context);
+ return FALSE;
+ }
+
+ ret = krb5_kt_read_service_key(context, NULL, princ, 0, ENCTYPE_ARCFOUR_HMAC, &key);
+ if (ret) {
+ DEBUG(1, ("secrets_fetch_keytab_password: failed to read secret for %s\n", spn));
+ krb5_free_context(context);
+ return FALSE;
+ }
+ if (key->keyvalue.length != 16) {
+ DEBUG(1, ("secrets_fetch_keytab_password: key is incorrect length\n"));
+ krb5_free_context(context);
+ return FALSE;
+ }
+
+ memcpy(ret_pwd, key->keyvalue.data, key->keyvalue.length);
+ time(pass_last_set_time); /* XXX */
+
+ krb5_free_keyblock(context, key);
+ krb5_free_context(context);
+
+ return TRUE;
+}
+#endif /* USE_KEYTAB */
+
/************************************************************************
Routine to get the trust account password for a domain.
The user of this function must have locked the trust password file using
@@ -243,6 +303,12 @@
pass_last_set_time = 0;
return True;
}
+
+#ifdef USE_KEYTAB
+ if (is_myworkgroup(domain)) {
+ return secrets_fetch_keytab_password(ret_pwd, pass_last_set_time);
+ }
+#endif /* USE_KEYTAB */
if (!(pass = secrets_fetch(trust_keystr(domain), &size))) {
DEBUG(5, ("secrets_fetch failed!\n"));
Index: smbd/sesssetup.c
===================================================================
RCS file: /cvsroot/samba/source/smbd/sesssetup.c,v
retrieving revision 1.87
diff -u -r1.87 sesssetup.c
--- smbd/sesssetup.c 10 Feb 2003 09:16:05 -0000 1.87
+++ smbd/sesssetup.c 23 Feb 2003 01:51:14 -0000
@@ -4,6 +4,7 @@
Copyright (C) Andrew Tridgell 1998-2001
Copyright (C) Andrew Bartlett 2001
Copyright (C) Jim McDonough 2002
+ Copyright (C) Luke Howard 2003
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -146,10 +147,13 @@
int sess_vuid;
NTSTATUS ret;
DATA_BLOB auth_data;
+ DATA_BLOB ap_rep, ap_rep_wrapped, response;
auth_serversupplied_info *server_info = NULL;
ADS_STRUCT *ads;
+ uint8 session_key[16];
+ uint16 tok_id;
- if (!spnego_parse_krb5_wrap(*secblob, &ticket)) {
+ if (!spnego_parse_krb5_wrap(*secblob, &ticket, &tok_id)) {
return ERROR_NT(NT_STATUS_LOGON_FAILURE);
}
@@ -161,7 +165,7 @@
ads->auth.realm = strdup(lp_realm());
- ret = ads_verify_ticket(ads, &ticket, &client, &auth_data);
+ ret = ads_verify_ticket(ads, &ticket, &client, &auth_data, &ap_rep, session_key);
if (!NT_STATUS_IS_OK(ret)) {
DEBUG(1,("Failed to verify incoming ticket!\n"));
ads_destroy(&ads);
@@ -176,6 +180,7 @@
if (!p) {
DEBUG(3,("Doesn't look like a valid principal\n"));
ads_destroy(&ads);
+ data_blob_free(&ap_rep);
return ERROR_NT(NT_STATUS_LOGON_FAILURE);
}
@@ -183,6 +188,7 @@
if (strcasecmp(p+1, ads->auth.realm) != 0) {
DEBUG(3,("Ticket for foreign realm %s@%s\n", client, p+1));
if (!lp_allow_trusted_domains()) {
+ data_blob_free(&ap_rep);
return ERROR_NT(NT_STATUS_LOGON_FAILURE);
}
/* this gives a fully qualified user name (ie. with full realm).
@@ -213,31 +219,51 @@
if (!pw) {
DEBUG(1,("Username %s is invalid on this system\n",user));
+ data_blob_free(&ap_rep);
return ERROR_NT(NT_STATUS_NO_SUCH_USER);
}
if (!NT_STATUS_IS_OK(ret = make_server_info_pw(&server_info,pw))) {
DEBUG(1,("make_server_info_from_pw failed!\n"));
+ data_blob_free(&ap_rep);
return ERROR_NT(ret);
}
-
+
+ /* Copy out the session key from the AP_REP. */
+ memcpy(server_info->session_key, session_key, sizeof(session_key));
+
/* register_vuid keeps the server info */
sess_vuid = register_vuid(server_info, user);
free(user);
if (sess_vuid == -1) {
- return ERROR_NT(NT_STATUS_LOGON_FAILURE);
+ ret = NT_STATUS_LOGON_FAILURE;
+ } else {
+ set_message(outbuf,4,0,True);
+ SSVAL(outbuf, smb_vwv3, 0);
+
+ if (server_info->guest) {
+ SSVAL(outbuf,smb_vwv2,1);
+ }
+
+ SSVAL(outbuf, smb_uid, sess_vuid);
}
- set_message(outbuf,4,0,True);
- SSVAL(outbuf, smb_vwv3, 0);
- add_signature(outbuf);
-
- SSVAL(outbuf,smb_uid,sess_vuid);
- SSVAL(inbuf,smb_uid,sess_vuid);
-
- return chain_reply(inbuf,outbuf,length,bufsize);
+ /* wrap that up in a nice GSS-API wrapping */
+ if (NT_STATUS_IS_OK(ret)) {
+ ap_rep_wrapped = spnego_gen_krb5_wrap(ap_rep, 0x0002);
+ } else {
+ ap_rep_wrapped = data_blob(NULL, 0);
+ }
+ response = spnego_gen_auth_response(&ap_rep_wrapped, ret, OID_KERBEROS5_OLD);
+ reply_sesssetup_blob(conn, outbuf, response, ret);
+
+ data_blob_free(&ap_rep);
+ data_blob_free(&ap_rep_wrapped);
+ data_blob_free(&response);
+
+ return -1; /* already replied */
}
#endif
@@ -284,7 +310,7 @@
}
}
- response = spnego_gen_auth_response(ntlmssp_blob, nt_status);
+ response = spnego_gen_auth_response(ntlmssp_blob, nt_status, OID_NTLMSSP);
ret = reply_sesssetup_blob(conn, outbuf, response, nt_status);
data_blob_free(&response);
-------------- next part --------------
--
Luke Howard | PADL Software Pty Ltd | www.padl.com
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