Implement FAST from draft-ietf-krb-wg-preauth-framework

Merge fast branch at 22146 onto trunk

Implement the kerberos pre-authentication framework FAST feature per
Projects/FAST on the wiki.

ticket: 6436
Target_Version: 1.7

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@22149 dc483132-0cff-0310-8789-dd5450dbe970

4 files changed, 452 insertions, 0 deletions

diff --git a/src/plugins/preauth/encrypted_challenge/Makefile.in b/src/plugins/preauth/encrypted_challenge/Makefile.in
new file mode 100644
index 0000000000..8f6a8a640b
--- /dev/null
+++ b/src/plugins/preauth/encrypted_challenge/Makefile.in
@@ -0,0 +1,41 @@
+thisconfigdir=../../..
+myfulldir=plugins/preauth/encrypted_challenge
+mydir=plugins/preauth/encrypted_challenge
+BUILDTOP=$(REL)..$(S)..$(S)..
+KRB5_RUN_ENV = @KRB5_RUN_ENV@
+KRB5_CONFIG_SETUP = KRB5_CONFIG=$(SRCTOP)/config-files/krb5.conf ; export KRB5_CONFIG ;
+PROG_LIBPATH=-L$(TOPLIBD)
+PROG_RPATH=$(KRB5_LIBDIR)
+MODULE_INSTALL_DIR = $(KRB5_PA_MODULE_DIR)
+DEFS=@DEFS@
+
+LOCALINCLUDES = -I../../../include/krb5 -I.
+
+LIBBASE=encrypted_challenge
+LIBMAJOR=0
+LIBMINOR=0
+SO_EXT=.so
+RELDIR=../plugins/preauth/encrypted_challenge
+# Depends on libk5crypto and libkrb5
+SHLIB_EXPDEPS = \
+	$(TOPLIBD)/libk5crypto$(SHLIBEXT) \
+	$(TOPLIBD)/libkrb5$(SHLIBEXT)
+SHLIB_EXPLIBS= -lkrb5 -lcom_err -lk5crypto $(SUPPORT_LIB) $(LIBS)
+
+SHLIB_DIRS=-L$(TOPLIBD)
+SHLIB_RDIRS=$(KRB5_LIBDIR)
+STOBJLISTS=OBJS.ST
+STLIBOBJS=encrypted_challenge_main.o
+
+SRCS= $(srcdir)/encrypted_challenge_main.c
+
+all-unix:: $(LIBBASE)$(SO_EXT)
+install-unix:: install-libs
+clean-unix:: clean-libs clean-libobjs
+
+clean::
+	$(RM) lib$(LIBBASE)$(SO_EXT)
+
+@libnover_frag@
+@libobj_frag@
+
diff --git a/src/plugins/preauth/encrypted_challenge/deps b/src/plugins/preauth/encrypted_challenge/deps
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/src/plugins/preauth/encrypted_challenge/deps
diff --git a/src/plugins/preauth/encrypted_challenge/encrypted_challenge.exports b/src/plugins/preauth/encrypted_challenge/encrypted_challenge.exports
new file mode 100644
index 0000000000..98e96c399b
--- /dev/null
+++ b/src/plugins/preauth/encrypted_challenge/encrypted_challenge.exports
@@ -0,0 +1,2 @@
+preauthentication_client_1
+preauthentication_server_1
diff --git a/src/plugins/preauth/encrypted_challenge/encrypted_challenge_main.c b/src/plugins/preauth/encrypted_challenge/encrypted_challenge_main.c
new file mode 100644
index 0000000000..3fad7ccd3a
--- /dev/null
+++ b/src/plugins/preauth/encrypted_challenge/encrypted_challenge_main.c
@@ -0,0 +1,409 @@
+/*
+ * plugins/preauth/encrypted_challenge/encrypted_challenge.c
+ *
+ * Copyright (C) 2009 by the Massachusetts Institute of Technology.
+ * All rights reserved.
+ *
+ * Export of this software from the United States of America may
+ *   require a specific license from the United States Government.
+ *   It is the responsibility of any person or organization contemplating
+ *   export to obtain such a license before exporting.
+ * 
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ * 
+ * 
+ *
+ * Implement EncryptedChallenge fast factor from draft-ietf-krb-wg-preauth-framework
+ */
+
+#include <k5-int.h>
+#include "../fast_factor.h"
+
+#include <krb5/preauth_plugin.h>
+
+static int preauth_flags
+(krb5_context context, krb5_preauthtype pa_type)
+{
+    return PA_REAL;
+}
+
+static krb5_error_code process_preauth
+(krb5_context context,
+			       void *plugin_context,
+			       void *request_context,
+			       krb5_get_init_creds_opt *opt,
+			       preauth_get_client_data_proc get_data_proc,
+			       struct _krb5_preauth_client_rock *rock,
+			       krb5_kdc_req *request,
+			       krb5_data *encoded_request_body,
+			       krb5_data *encoded_previous_request,
+			       krb5_pa_data *padata,
+			       krb5_prompter_fct prompter,
+			       void *prompter_data,
+			       preauth_get_as_key_proc gak_fct,
+			       void *gak_data,
+			       krb5_data *salt,
+			       krb5_data *s2kparams,
+			       krb5_keyblock *as_key,
+			       krb5_pa_data ***out_padata)
+{
+    krb5_error_code retval = 0;
+    krb5_enctype enctype = 0;
+    krb5_keyblock *challenge_key = NULL, *armor_key = NULL;
+    krb5_data *etype_data = NULL;
+    krb5int_access kaccess;
+    
+    if (krb5int_accessor(&kaccess, KRB5INT_ACCESS_VERSION) != 0)
+	return 0;
+    retval = fast_get_armor_key(context, get_data_proc, rock, &armor_key);
+    if (retval || armor_key == NULL)
+	return 0;
+        retval = get_data_proc(context, rock, krb5plugin_preauth_client_get_etype, &etype_data);
+    if (retval == 0) {
+	enctype = *((krb5_enctype *)etype_data->data);
+	if (as_key->length == 0 ||as_key->enctype != enctype)
+	    retval = gak_fct(context, request->client,
+			     enctype, prompter, prompter_data,
+			     salt, s2kparams,
+			     as_key, gak_data);
+    }
+    if (padata->length) {
+	krb5_enc_data *enc = NULL;
+	krb5_data scratch;
+	scratch.length = padata->length;
+	scratch.data = (char *) padata->contents;
+		if (retval == 0)
+	    retval = krb5_c_fx_cf2_simple(context,armor_key, "kdcchallengearmor",
+					  as_key, "challengelongterm", &challenge_key);
+	if (retval == 0)
+	    retval =kaccess.decode_enc_data(&scratch, &enc);
+	scratch.data = NULL;
+	if (retval == 0) {
+	    scratch.data = malloc(enc->ciphertext.length);
+	    scratch.length = enc->ciphertext.length;
+	    if (scratch.data == NULL)
+		retval = ENOMEM;
+	}
+	if (retval == 0)
+	    retval = krb5_c_decrypt(context, challenge_key,
+				    KRB5_KEYUSAGE_ENC_CHALLENGE_KDC, NULL,
+				    enc, &scratch);
+/*Per draft 11 of the preauth framework, the client MAY but
+ * is not required  to actually check the timestamp from the KDC other than
+ * to confirm it decrypts. This code does not perform that check.
+ */
+	if (scratch.data)
+	    krb5_free_data_contents(context, &scratch);
+	if (retval == 0)
+	    fast_set_kdc_verified(context, get_data_proc, rock);
+	if (enc)
+	    kaccess.free_enc_data(context, enc);
+    } else { /*No padata; we send*/
+	krb5_enc_data enc;
+	krb5_pa_data *pa = NULL;
+	krb5_pa_data **pa_array = NULL;
+	krb5_data *encoded_ts = NULL;
+	krb5_pa_enc_ts ts;
+	if (retval == 0)
+	retval = krb5_us_timeofday(context, &ts.patimestamp, &ts.pausec);
+	if (retval == 0)
+	    retval = kaccess.encode_enc_ts(&ts, &encoded_ts);
+	if (retval == 0)
+	    retval = krb5_c_fx_cf2_simple(context,
+					  armor_key, "clientchallengearmor",
+					  as_key, "challengelongterm",
+					  &challenge_key);
+	if (retval == 0)
+	    retval = kaccess.encrypt_helper(context, challenge_key,
+					    KRB5_KEYUSAGE_ENC_CHALLENGE_CLIENT,
+					    encoded_ts, &enc);
+	if (encoded_ts)
+	    krb5_free_data(context, encoded_ts);
+	encoded_ts = NULL;
+	if (retval == 0) {
+	    retval = kaccess.encode_enc_data(&enc, &encoded_ts);
+	    krb5_free_data_contents(context, &enc.ciphertext);
+	}
+	if (retval == 0) {
+	    pa = calloc(1, sizeof(krb5_pa_data));
+	    if (pa == NULL)
+		retval = ENOMEM;
+	}
+	if (retval == 0) {
+	    pa_array = calloc(2, sizeof(krb5_pa_data *));
+	    if (pa_array == NULL)
+		retval = ENOMEM;
+	}
+	if (retval == 0) {
+	    pa->length = encoded_ts->length;
+	    pa->contents = (unsigned char *) encoded_ts->data;
+	    pa->pa_type = KRB5_PADATA_ENCRYPTED_CHALLENGE;
+	    free(encoded_ts);
+	    encoded_ts = NULL;
+	    pa_array[0] = pa;
+	    pa = NULL;
+	    *out_padata = pa_array;
+	    pa_array = NULL;
+	}
+	if (pa)
+	    free(pa);
+	if (encoded_ts)
+	    krb5_free_data(context, encoded_ts);
+	if (pa_array)
+	    free(pa_array);
+    }
+    if (challenge_key)
+	krb5_free_keyblock(context, challenge_key);
+    if (armor_key)
+	krb5_free_keyblock(context, armor_key);
+    if (etype_data != NULL)
+	get_data_proc(context, rock, krb5plugin_preauth_client_free_etype,
+		      &etype_data);
+    return retval;
+}
+    
+	
+					  
+				      
+static krb5_error_code kdc_include_padata
+(krb5_context context,
+			     krb5_kdc_req *request,
+			     struct _krb5_db_entry_new *client,
+			     struct _krb5_db_entry_new *server,
+			     preauth_get_entry_data_proc get_entry_proc,
+			     void *pa_module_context,
+			     krb5_pa_data *data)
+{
+    krb5_error_code retval = 0;
+    krb5_keyblock *armor_key = NULL;
+    retval = fast_kdc_get_armor_key(context, get_entry_proc, request, client, &armor_key);
+    if (retval)
+	return retval;
+    if (armor_key == 0)
+	return ENOENT;
+    krb5_free_keyblock(context, armor_key);
+    return 0;
+}
+
+static krb5_error_code kdc_verify_preauth
+(krb5_context context,
+			      struct _krb5_db_entry_new *client,
+			      krb5_data *req_pkt,
+			      krb5_kdc_req *request,
+			      krb5_enc_tkt_part *enc_tkt_reply,
+			      krb5_pa_data *data,
+			      preauth_get_entry_data_proc get_entry_proc,
+			      void *pa_module_context,
+			      void **pa_request_context,
+			      krb5_data **e_data,
+			      krb5_authdata ***authz_data)
+{
+    krb5_error_code retval = 0;
+    krb5_timestamp now;
+    krb5_enc_data *enc = NULL;
+    krb5_data scratch, plain;
+    krb5_keyblock *armor_key = NULL;
+    krb5_pa_enc_ts *ts = NULL;
+    krb5int_access kaccess;
+    krb5_keyblock *client_keys = NULL;
+    krb5_data *client_data = NULL;
+    krb5_keyblock *challenge_key = NULL;
+    int i;
+    
+    plain.data = NULL;
+    if (krb5int_accessor(&kaccess, KRB5INT_ACCESS_VERSION) != 0)
+	return 0; 
+
+    retval = fast_kdc_get_armor_key(context, get_entry_proc, request, client, &armor_key);
+    if (retval == 0 &&armor_key == NULL) {
+	retval = ENOENT;
+	krb5_set_error_message(context, ENOENT, "Encrypted Challenge used outside of FAST tunnel");
+    }
+    scratch.data = (char *) data->contents;
+    scratch.length = data->length;
+    if (retval == 0)
+	retval = kaccess.decode_enc_data(&scratch, &enc);
+    if (retval == 0) {
+	plain.data =  malloc(enc->ciphertext.length);
+	plain.length = enc->ciphertext.length;
+	if (plain.data == NULL)
+	    retval = ENOMEM;
+    }
+    if (retval == 0)
+	retval = get_entry_proc(context, request, client, 
+			       krb5plugin_preauth_keys, &client_data);
+    if (retval == 0) {
+	client_keys = (krb5_keyblock *) client_data->data;
+	for (i = 0; client_keys[i].enctype&& (retval == 0); i++ ) {
+	    retval = krb5_c_fx_cf2_simple(context,
+					  armor_key, "clientchallengearmor",
+					  &client_keys[i], "challengelongterm",
+					  &challenge_key);
+	    if (retval == 0)
+		retval  = krb5_c_decrypt(context, challenge_key,
+					 KRB5_KEYUSAGE_ENC_CHALLENGE_CLIENT,
+					 NULL, enc, &plain);
+	    if (challenge_key)
+		krb5_free_keyblock(context, challenge_key);
+	    challenge_key = NULL;
+	    if (retval == 0)
+		break;
+	    /*We failed to decrypt. Try next key*/
+	    retval = 0;
+	    krb5_free_keyblock_contents(context, &client_keys[i]);
+	    	}
+	if (client_keys[i].enctype == 0) {
+	    retval = KRB5KDC_ERR_PREAUTH_FAILED;
+	    krb5_set_error_message(context, retval, "Incorrect password  in encrypted challenge");
+	} else { /*not run out of keys*/
+	    int j;
+	    assert (retval == 0);
+	    for (j = i+1; client_keys[j].enctype; j++)
+		krb5_free_keyblock_contents(context, &client_keys[j]);
+	}
+	
+    }
+    if (retval == 0)
+	retval = kaccess.decode_enc_ts(&plain, &ts);
+    if (retval == 0)
+	retval = krb5_timeofday(context, &now);
+    if (retval == 0) {
+	if (labs(now-ts->patimestamp) < context->clockskew) {
+	    enc_tkt_reply->flags |= TKT_FLG_PRE_AUTH;
+/*If this fails, we won't generate a reply to the client.  That may
+ * cause the client to fail, but at this point the KDC has considered
+ this a success, so the return value is ignored. */
+	    fast_kdc_replace_reply_key(context, get_entry_proc, request);
+	    krb5_c_fx_cf2_simple(context, armor_key, "kdcchallengearmor",
+				 &client_keys[i], "challengelongterm",
+				 (krb5_keyblock **) pa_request_context);
+	} else { /*skew*/
+	    retval = KRB5KRB_AP_ERR_SKEW;
+	}
+    }
+    if (client_keys) {
+	if (client_keys[i].enctype)
+	    krb5_free_keyblock_contents(context, &client_keys[i]);
+	krb5_free_data(context, client_data);
+    }
+    if (armor_key)
+	krb5_free_keyblock(context, armor_key);
+    if (challenge_key)
+	krb5_free_keyblock(context, challenge_key);
+    if (plain.data) 
+	free(plain.data);
+    if (enc)
+	kaccess.free_enc_data(context, enc);
+    if (ts)
+	kaccess.free_enc_ts(context, ts);
+    return retval;
+}
+
+static krb5_error_code kdc_return_preauth
+(krb5_context context,
+			      krb5_pa_data * padata,
+			      struct _krb5_db_entry_new *client,
+			      krb5_data *req_pkt,
+			      krb5_kdc_req *request,
+			      krb5_kdc_rep *reply,
+			      struct _krb5_key_data *client_keys,
+			      krb5_keyblock *encrypting_key,
+			      krb5_pa_data **send_pa,
+			      preauth_get_entry_data_proc get_entry_proc,
+			      void *pa_module_context,
+			      void **pa_request_context)
+{
+    krb5_error_code retval = 0;
+    krb5_keyblock *challenge_key = *pa_request_context;
+    krb5_pa_enc_ts ts;
+    krb5_data *plain = NULL;
+    krb5_enc_data enc;
+    krb5_data *encoded = NULL;
+    krb5_pa_data *pa = NULL;
+    krb5int_access kaccess;
+   
+    if (krb5int_accessor(&kaccess, KRB5INT_ACCESS_VERSION) != 0)
+	return 0;
+    if (challenge_key == NULL)
+	return 0;
+    * pa_request_context = NULL; /*this function will free the
+				  * challenge key*/
+    retval = krb5_us_timeofday(context, &ts.patimestamp, &ts.pausec);
+    if (retval == 0)
+	retval = kaccess.encode_enc_ts(&ts, &plain);
+    if (retval == 0)
+	retval = kaccess.encrypt_helper(context, challenge_key,
+					KRB5_KEYUSAGE_ENC_CHALLENGE_KDC,
+					plain, &enc);
+    if (retval == 0)
+	retval = kaccess.encode_enc_data(&enc, &encoded);
+    if (retval == 0) {
+	pa = calloc(1, sizeof(krb5_pa_data));
+	if (pa == NULL)
+	    retval = ENOMEM;
+    }
+    if (retval == 0) {
+	pa->pa_type = KRB5_PADATA_ENCRYPTED_CHALLENGE;
+	pa->contents = (unsigned char *) encoded->data;
+	pa->length = encoded->length;
+	encoded->data = NULL;
+	*send_pa = pa;
+	pa = NULL;
+    }
+    if (challenge_key)
+	krb5_free_keyblock(context, challenge_key);
+    if (encoded)
+	krb5_free_data(context, encoded);
+    if (plain)
+	krb5_free_data(context, plain);
+    if (enc.ciphertext.data)
+	krb5_free_data_contents(context, &enc.ciphertext);
+    return retval;
+}
+
+static int kdc_preauth_flags
+(krb5_context context, krb5_preauthtype  patype)
+{
+    return 0;
+}
+
+krb5_preauthtype supported_pa_types[] = {
+    KRB5_PADATA_ENCRYPTED_CHALLENGE, 0};
+
+struct krb5plugin_preauth_server_ftable_v1 preauthentication_server_1 = {
+    "Encrypted challenge",
+    &supported_pa_types[0],
+NULL,
+NULL,
+kdc_preauth_flags,
+    kdc_include_padata,
+    kdc_verify_preauth,
+    kdc_return_preauth,
+NULL
+};
+
+struct krb5plugin_preauth_client_ftable_v1 preauthentication_client_1 = {
+    "Encrypted Challenge",			    /* name */
+    &supported_pa_types[0],	    /* pa_type_list */
+    NULL,				    /* enctype_list */
+    NULL,				    /* plugin init function */
+    NULL,				    /* plugin fini function */
+    preauth_flags,			    /* get flags function */
+    NULL,				    /* request init function */
+    NULL,				    /* request fini function */
+    process_preauth,			    /* process function */
+    NULL,				    /* try_again function */
+NULL			    /* get init creds opt function */
+};