r7978: A start again on PAC verification. I have noticed that the kerberos

keys appear at the end of the PAC, which I feel is deliberate (it
makes this much easier).

I still can't make it work, but I'm sure we are closer.

Andrew Bartlett
(This used to be commit 6f0e1c80ae7b1e31e7a3fbff84f07442ee5a31cf)

3 files changed, 43 insertions, 52 deletions

diff --git a/source4/auth/gensec/gensec_gssapi.c b/source4/auth/gensec/gensec_gssapi.c
index a95805f9fa..2b7c4ca2cc 100644
--- a/source4/auth/gensec/gensec_gssapi.c
+++ b/source4/auth/gensec/gensec_gssapi.c
@@ -737,6 +737,7 @@ static NTSTATUS gensec_gssapi_session_info(struct gensec_security *gensec_securi
 	OM_uint32 maj_stat, min_stat;
 	gss_buffer_desc name_token;
 	gss_buffer_desc pac;
+	krb5_keyblock *keyblock;
 	
 	mem_ctx = talloc_named(gensec_gssapi_state, 0, "gensec_gssapi_session_info context"); 
 	NT_STATUS_HAVE_NO_MEMORY(mem_ctx);
@@ -768,9 +769,13 @@ static NTSTATUS gensec_gssapi_session_info(struct gensec_security *gensec_securi
 	}
 	account_name = principal;
 	
+	maj_stat = gss_krb5_copy_service_keyblock(&min_stat, 
+						  gensec_gssapi_state->gssapi_context, 
+						  &keyblock);
+
 	maj_stat = gsskrb5_extract_authz_data_from_sec_context(&min_stat, 
 							       gensec_gssapi_state->gssapi_context, 
-							       1,
+							       KRB5_AUTHDATA_IF_RELEVANT,
 							       &pac);
 	
 	if (maj_stat == 0) {
@@ -780,7 +785,8 @@ static NTSTATUS gensec_gssapi_session_info(struct gensec_security *gensec_securi
 		
 		/* decode and verify the pac */
 		nt_status = kerberos_decode_pac(mem_ctx, &logon_info, pac_blob,
-						gensec_gssapi_state->smb_krb5_context);
+						gensec_gssapi_state->smb_krb5_context,
+						keyblock);
 
 		if (NT_STATUS_IS_OK(nt_status)) {
 			union netr_Validation validation;
diff --git a/source4/auth/kerberos/kerberos.h b/source4/auth/kerberos/kerberos.h
index 0f8fd28155..ca0bbbed0e 100644
--- a/source4/auth/kerberos/kerberos.h
+++ b/source4/auth/kerberos/kerberos.h
@@ -101,6 +101,9 @@ NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx,
 int kerberos_kinit_password_cc(krb5_context ctx, krb5_ccache cc, 
 			       const char *principal, const char *password, 
 			       time_t *expire_time, time_t *kdc_time);
+int kerberos_kinit_keyblock_cc(krb5_context ctx, krb5_ccache cc, 
+			       const char *principal, krb5_keyblock *keyblock,
+			       time_t *expire_time, time_t *kdc_time);
 krb5_principal kerberos_fetch_salt_princ_for_host_princ(krb5_context context,
 							krb5_principal host_princ,
 							int enctype);
@@ -124,5 +127,10 @@ NTSTATUS create_memory_keytab(TALLOC_CTX *parent_ctx,
 			      struct cli_credentials *machine_account,
 			      struct smb_krb5_context *smb_krb5_context,
 			      krb5_keytab *keytab);
+NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
+			     struct PAC_LOGON_INFO **logon_info_out,
+			     DATA_BLOB blob,
+			     struct smb_krb5_context *smb_krb5_context,
+			     krb5_keyblock *keyblock);
 #endif /* HAVE_KRB5 */
 
diff --git a/source4/auth/kerberos/kerberos_pac.c b/source4/auth/kerberos/kerberos_pac.c
index 8f3d2cd72c..84a7c56cc9 100644
--- a/source4/auth/kerberos/kerberos_pac.c
+++ b/source4/auth/kerberos/kerberos_pac.c
@@ -32,11 +32,12 @@
 #include "librpc/gen_ndr/ndr_krb5pac.h"
 #include "auth/auth.h"
 
-#ifdef KRB5_DO_VERIFY_PAC
-static NTSTATUS kerberos_pac_checksum(DATA_BLOB pac_data,
-					 struct PAC_SIGNATURE_DATA *sig,
-					 struct smb_krb5_context *smb_krb5_context,
-					 uint32 keyusage)
+static NTSTATUS kerberos_pac_checksum(TALLOC_CTX *mem_ctx, 
+				      DATA_BLOB pac_data,
+				      struct PAC_SIGNATURE_DATA *sig,
+				      struct smb_krb5_context *smb_krb5_context,
+				      krb5_keyblock *keyblock,
+				      uint32_t keyusage)
 {
 	krb5_error_code ret;
 	krb5_crypto crypto;
@@ -49,9 +50,9 @@ static NTSTATUS kerberos_pac_checksum(DATA_BLOB pac_data,
 
 
 	ret = krb5_crypto_init(smb_krb5_context->krb5_context,
-				&gensec_krb5_state->keyblock,
-				0,
-				&crypto);
+			       keyblock,
+			       0,
+			       &crypto);
 	if (ret) {
 		DEBUG(0,("krb5_crypto_init() failed\n"));
 		return NT_STATUS_FOOBAR;
@@ -65,10 +66,14 @@ static NTSTATUS kerberos_pac_checksum(DATA_BLOB pac_data,
 					   pac_data.length,
 					   &cksum);
 		if (!ret) {
-			DEBUG(0,("PAC Verified: keyusage: %d\n", keyusage));
+			DEBUG(0, ("PAC Verified: keyusage: %d\n", keyusage));
 			break;
+		} else {
+			DEBUG(2, ("PAC Verification failed: %s\n", 
+				  smb_get_krb5_error_message(smb_krb5_context->krb5_context, ret, mem_ctx)));
 		}
 	}
+
 	krb5_crypto_destroy(smb_krb5_context->krb5_context, crypto);
 
 	if (ret) {
@@ -80,23 +85,22 @@ static NTSTATUS kerberos_pac_checksum(DATA_BLOB pac_data,
 
 	return NT_STATUS_OK;
 }
-#endif
 
-NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
+ NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
 			     struct PAC_LOGON_INFO **logon_info_out,
 			     DATA_BLOB blob,
-			     struct smb_krb5_context *smb_krb5_context)
+			     struct smb_krb5_context *smb_krb5_context,
+			     krb5_keyblock *keyblock)
 {
 	NTSTATUS status;
 	struct PAC_SIGNATURE_DATA srv_sig;
-	struct PAC_SIGNATURE_DATA *srv_sig_ptr;
+	struct PAC_SIGNATURE_DATA *srv_sig_ptr = NULL;
 	struct PAC_SIGNATURE_DATA kdc_sig;
-	struct PAC_SIGNATURE_DATA *kdc_sig_ptr;
+	struct PAC_SIGNATURE_DATA *kdc_sig_ptr = NULL;
 	struct PAC_LOGON_INFO *logon_info = NULL;
 	struct PAC_DATA pac_data;
-#ifdef KRB5_DO_VERIFY_PAC
-	DATA_BLOB tmp_blob = data_blob(NULL, 0);
-#endif
+	DATA_BLOB modified_pac_blob = data_blob_talloc(mem_ctx, blob.data, blob.length);
+	DATA_BLOB tmp_blob;
 	int i;
 
 	status = ndr_pull_struct_blob(&blob, mem_ctx, &pac_data,
@@ -156,39 +160,11 @@ NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
 		DEBUG(0,("PAC no kdc_key\n"));
 		return NT_STATUS_FOOBAR;
 	}
-#ifdef KRB5_DO_VERIFY_PAC
-	/* clear the kdc_key */
-/*	memset((void *)kdc_sig_ptr , '\0', sizeof(*kdc_sig_ptr));*/
-
-	status = ndr_push_struct_blob(&tmp_blob, mem_ctx, &pac_data,
-					      (ndr_push_flags_fn_t)ndr_push_PAC_DATA);
-	if (!NT_STATUS_IS_OK(status)) {
-		return status;
-	}
-	status = ndr_pull_struct_blob(&tmp_blob, mem_ctx, &pac_data,
-					(ndr_pull_flags_fn_t)ndr_pull_PAC_DATA);
-	if (!NT_STATUS_IS_OK(status)) {
-		DEBUG(0,("can't parse the PAC\n"));
-		return status;
-	}
-	/*NDR_PRINT_DEBUG(PAC_DATA, &pac_data);*/
-
-	/* verify by kdc_key */
-	status = kerberos_pac_checksum(tmp_blob, &kdc_sig, smb_krb5_context, 0);
 
-	if (!NT_STATUS_IS_OK(status)) {
-		return status;
-	}
+	memset(&modified_pac_blob.data[modified_pac_blob.length - 48],
+	       '\0', 48);
 
-	/* clear the service_key */
-/*	memset((void *)srv_sig_ptr , '\0', sizeof(*srv_sig_ptr));*/
-
-	status = ndr_push_struct_blob(&tmp_blob, mem_ctx, &pac_data,
-					      (ndr_push_flags_fn_t)ndr_push_PAC_DATA);
-	if (!NT_STATUS_IS_OK(status)) {
-		return status;
-	}
-	status = ndr_pull_struct_blob(&tmp_blob, mem_ctx, &pac_data,
+	status = ndr_pull_struct_blob(&modified_pac_blob, mem_ctx, &pac_data,
 					(ndr_pull_flags_fn_t)ndr_pull_PAC_DATA);
 	if (!NT_STATUS_IS_OK(status)) {
 		DEBUG(0,("can't parse the PAC\n"));
@@ -197,12 +173,13 @@ NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
 	NDR_PRINT_DEBUG(PAC_DATA, &pac_data);
 
 	/* verify by servie_key */
-	status = kerberos_pac_checksum(tmp_blob, &srv_sig, smb_krb5_context, 0);
+	status = kerberos_pac_checksum(mem_ctx, 
+				       modified_pac_blob, &srv_sig, 
+				       smb_krb5_context, keyblock, 0);
 
 	if (!NT_STATUS_IS_OK(status)) {
 		return status;
 	}
-#endif
 	DEBUG(0,("account_name: %s [%s]\n",
 		 logon_info->info3.base.account_name.string, 
 		 logon_info->info3.base.full_name.string));