s4:auth/credentials: pass 'self_service' to cli_credentials_set_impersonate_principal()

This also adds a cli_credentials_get_self_service() helper function.

In order to support S4U2Proxy we need to be able to set
the service principal for the S4U2Self step independent of the
target principal.

metze

4 files changed, 32 insertions, 7 deletions

diff --git a/source4/auth/credentials/credentials.c b/source4/auth/credentials/credentials.c
index 015c549693..83e90344bf 100644
--- a/source4/auth/credentials/credentials.c
+++ b/source4/auth/credentials/credentials.c
@@ -64,6 +64,7 @@ _PUBLIC_ struct cli_credentials *cli_credentials_init(TALLOC_CTX *mem_ctx)
 	cred->principal = NULL;
 	cred->salt_principal = NULL;
 	cred->impersonate_principal = NULL;
+	cred->self_service = NULL;
 	cred->target_service = NULL;
 
 	cred->bind_dn = NULL;
diff --git a/source4/auth/credentials/credentials.h b/source4/auth/credentials/credentials.h
index 0b0de59752..f8fa2f864b 100644
--- a/source4/auth/credentials/credentials.h
+++ b/source4/auth/credentials/credentials.h
@@ -84,6 +84,7 @@ struct cli_credentials {
 	const char *principal;
 	char *salt_principal;
 	char *impersonate_principal;
+	char *self_service;
 	char *target_service;
 
 	const char *bind_dn;
@@ -277,10 +278,13 @@ bool cli_credentials_parse_password_fd(struct cli_credentials *credentials,
 void cli_credentials_invalidate_ccache(struct cli_credentials *cred, 
 				       enum credentials_obtained obtained);
 void cli_credentials_set_salt_principal(struct cli_credentials *cred, const char *principal);
-void cli_credentials_set_impersonate_principal(struct cli_credentials *cred, const char *principal);
+void cli_credentials_set_impersonate_principal(struct cli_credentials *cred,
+					       const char *principal,
+					       const char *self_service);
 void cli_credentials_set_target_service(struct cli_credentials *cred, const char *principal);
 const char *cli_credentials_get_salt_principal(struct cli_credentials *cred);
 const char *cli_credentials_get_impersonate_principal(struct cli_credentials *cred);
+const char *cli_credentials_get_self_service(struct cli_credentials *cred);
 const char *cli_credentials_get_target_service(struct cli_credentials *cred);
 enum credentials_use_kerberos cli_credentials_get_kerberos_state(struct cli_credentials *creds);
 enum credentials_krb_forwardable cli_credentials_get_krb_forwardable(struct cli_credentials *creds);
diff --git a/source4/auth/credentials/credentials_krb5.c b/source4/auth/credentials/credentials_krb5.c
index d3925a01f6..5883282c25 100644
--- a/source4/auth/credentials/credentials_krb5.c
+++ b/source4/auth/credentials/credentials_krb5.c
@@ -788,19 +788,35 @@ _PUBLIC_ void cli_credentials_set_salt_principal(struct cli_credentials *cred, c
  * member of the domain to get the groups of a user.  This is also
  * known as S4U2Self */
 
-const char *cli_credentials_get_impersonate_principal(struct cli_credentials *cred)
+_PUBLIC_ const char *cli_credentials_get_impersonate_principal(struct cli_credentials *cred)
 {
 	return cred->impersonate_principal;
 }
 
-_PUBLIC_ void cli_credentials_set_impersonate_principal(struct cli_credentials *cred, const char *principal)
+/*
+ * The 'self_service' is the service principal that
+ * represents the same object (by its objectSid)
+ * as the client principal (typically our machine account).
+ * When trying to impersonate 'impersonate_principal' with
+ * S4U2Self.
+ */
+_PUBLIC_ const char *cli_credentials_get_self_service(struct cli_credentials *cred)
+{
+	return cred->self_service;
+}
+
+_PUBLIC_ void cli_credentials_set_impersonate_principal(struct cli_credentials *cred,
+							const char *principal,
+							const char *self_service)
 {
 	talloc_free(cred->impersonate_principal);
 	cred->impersonate_principal = talloc_strdup(cred, principal);
+	talloc_free(cred->self_service);
+	cred->self_service = talloc_strdup(cred, self_service);
 }
 
-/* when impersonating for S4U2Self we need to set the target principal
- * to ourself, as otherwise we would need additional rights.
+/*
+ * when impersonating for S4U2proxy we need to set the target principal.
  * Similarly, we may only be authorized to do general impersonation to
  * some particular services.
  *
diff --git a/source4/auth/kerberos/kerberos_util.c b/source4/auth/kerberos/kerberos_util.c
index 45b0b07e13..f05016b873 100644
--- a/source4/auth/kerberos/kerberos_util.c
+++ b/source4/auth/kerberos/kerberos_util.c
@@ -338,7 +338,9 @@ krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 				 const char **error_string)
 {
 	krb5_error_code ret;
-	const char *password, *target_service;
+	const char *password;
+	const char *self_service;
+	const char *target_service;
 	time_t kdc_time = 0;
 	krb5_principal princ;
 	krb5_principal impersonate_principal;
@@ -363,6 +365,7 @@ krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 		return ret;
 	}
 
+	self_service = cli_credentials_get_self_service(credentials);
 	target_service = cli_credentials_get_target_service(credentials);
 
 	password = cli_credentials_get_password(credentials);
@@ -403,7 +406,8 @@ krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
 		if (password) {
 			ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache, 
 							 princ, password,
-							 impersonate_principal, target_service,
+							 impersonate_principal,
+							 self_service,
 							 krb_options,
 							 NULL, &kdc_time);
 		} else if (impersonate_principal) {