idmap: Handle uid->SID mapping
authorKai Blin <kai@samba.org>
Mon, 18 Feb 2008 13:33:58 +0000 (14:33 +0100)
committerKai Blin <kai@samba.org>
Thu, 21 Feb 2008 10:21:59 +0000 (11:21 +0100)
.gitignore
source/scripting/libjs/provision.js
source/scripting/python/samba/provision.py
source/setup/idmap_init.ldif [new file with mode: 0644]
source/winbind/config.mk
source/winbind/idmap.c [new file with mode: 0644]
source/winbind/idmap.h [new file with mode: 0644]
source/winbind/wb_server.c
source/winbind/wb_server.h
source/winbind/wb_uid2sid.c

index 6076ddc9cd3280d0b1c563007934135580e4eab0..f75f698c6565e05a39a721afcc5d8bb3bc062516 100644 (file)
@@ -129,6 +129,7 @@ source/utils/net/net_proto.h
 source/web_server/proto.h
 source/winbind/wb_helper.h
 source/winbind/wb_proto.h
+source/winbind/idmap_proto.h
 source/wrepl_server/wrepl_server_proto.h
 tags
 source/auth/credentials/credentials_krb5_proto.h
index dc9eae8e7286ddf1de24fe8de2dfa5af8c40c12e..3ba93debf98100da234e425fbdd84025c5ba80b4 100644 (file)
@@ -389,6 +389,7 @@ function provision_default_paths(subobj)
        paths.smbconf = lp.filename()
        paths.shareconf = lp.get("private dir") + "/" + "share.ldb";
        paths.samdb = lp.get("sam database");
+       paths.idmapdb = lp.get("idmap database");
        paths.secrets = lp.get("secrets database");
        paths.templates = lp.get("private dir") + "/" + "templates.ldb";
        paths.keytab = "secrets.keytab";
@@ -679,6 +680,9 @@ function provision(subobj, message, blank, paths, session_info, credentials, lda
        message("Setting up templates into " + paths.templates + "\n");
        setup_ldb("provision_templates.ldif", info, paths.templates);
 
+       message("Setting up " + paths.idmapdb +"\n");
+       setup_ldb("idmap_init.ldif", info, paths.idmapdb);
+
        message("Setting up sam.ldb partitions\n");
        /* Also wipes the database */
        setup_ldb("provision_partitions.ldif", info, paths.samdb);
index 3e88b68509c9370d04da52b411a6c75fcb62f9f2..e3c47ff4a2c902e07be025047d56e96bbab7c075 100644 (file)
@@ -59,6 +59,7 @@ class ProvisionPaths:
         self.hkpd = None
         self.hkpt = None
         self.samdb = None
+        self.idmapdb = None
         self.secrets = None
         self.keytab = None
         self.dns_keytab = None
@@ -202,6 +203,7 @@ def provision_paths_from_lp(lp, dnsdomain):
 
     paths.shareconf = os.path.join(private_dir, "share.ldb")
     paths.samdb = os.path.join(private_dir, lp.get("sam database") or "samdb.ldb")
+    paths.idmapdb = os.path.join(private_dir, lp.get("idmap database") or "idmap.ldb")
     paths.secrets = os.path.join(private_dir, lp.get("secrets database") or "secrets.ldb")
     paths.templates = os.path.join(private_dir, "templates.ldb")
     paths.dns = os.path.join(private_dir, dnsdomain + ".zone")
@@ -471,6 +473,24 @@ def setup_registry(path, setup_path, session_info, credentials, lp):
     assert os.path.exists(provision_reg)
     reg.diff_apply(provision_reg)
 
+def setup_idmapdb(path, setup_path, session_info, credentials, lp):
+    """Setup the idmap database.
+
+    :param path: path to the idmap database
+    :param setup_path: Function that returns a path to a setup file
+    :param session_info: Session information
+    :param credentials: Credentials
+    :param lp: Loadparm context
+    """
+    if os.path.exists(path):
+        os.unlink(path)
+
+    idmap_ldb = Ldb(path, session_info=session_info, credentials=credentials,
+                    lp=lp)
+
+    idmap_ldb.erase()
+    idmap_ldb.load_ldif_file_add(setup_path("idmap_init.ldif"))
+    return idmap_ldb
 
 def setup_samdb_rootdse(samdb, setup_path, schemadn, domaindn, hostname, 
                         dnsdomain, realm, rootdn, configdn, netbiosname,
@@ -844,6 +864,10 @@ def provision(lp, setup_dir, message, paths, session_info,
     setup_templatesdb(paths.templates, setup_path, session_info=session_info, 
                       credentials=credentials, lp=lp)
 
+    message("Setting up idmap db")
+    setup_idmapdb(paths.idmapdb, setup_path, session_info=session_info,
+                  credentials=credentials, lp=lp)
+
     samdb = setup_samdb(paths.samdb, setup_path, session_info=session_info, 
                         credentials=credentials, lp=lp, schemadn=schemadn, 
                         configdn=configdn, domaindn=domaindn,
diff --git a/source/setup/idmap_init.ldif b/source/setup/idmap_init.ldif
new file mode 100644 (file)
index 0000000..a397cfd
--- /dev/null
@@ -0,0 +1,5 @@
+dn: CN=CONFIG
+cn: CONFIG
+lowerBound: 10000
+upperBound: 20000
+
index da5b71f2ae85a780296ae498e09493c5e4b3b818..2567d617da946e29fe50bf0e619605b1b766bd13 100644 (file)
@@ -37,6 +37,7 @@ OBJ_FILES = \
                wb_sam_logon.o
 PRIVATE_DEPENDENCIES = \
                WB_HELPER \
+               IDMAP \
                NDR_WINBIND \
                process_model \
                RPC_NDR_LSA \
@@ -56,3 +57,13 @@ OBJ_FILES = \
 PUBLIC_DEPENDENCIES = RPC_NDR_LSA dcerpc_samr
 # End SUBSYSTEM WB_HELPER
 ################################################
+
+################################################
+# Start SUBYSTEM IDMAP
+[SUBSYSTEM::IDMAP]
+PRIVATE_PROTO_HEADER = idmap_proto.h
+OBJ_FILES = \
+               idmap.o
+PUBLIC_DEPENDENCIES = SAMDB_COMMON
+# End SUBSYSTEM IDMAP
+################################################
diff --git a/source/winbind/idmap.c b/source/winbind/idmap.c
new file mode 100644 (file)
index 0000000..b148852
--- /dev/null
@@ -0,0 +1,415 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   Map SIDs to uids/gids and back
+
+   Copyright (C) Kai Blin 2008
+
+   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
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "auth/auth.h"
+#include "librpc/gen_ndr/lsa.h"
+#include "librpc/gen_ndr/samr.h"
+#include "librpc/gen_ndr/ndr_security.h"
+#include "lib/ldb/include/ldb.h"
+#include "lib/ldb/include/ldb_errors.h"
+#include "lib/ldb_wrap.h"
+#include "param/param.h"
+#include "winbind/idmap.h"
+#include "libcli/security/proto.h"
+#include "libcli/ldap/ldap_ndr.h"
+
+/**
+ * Get uid/gid bounds from idmap database
+ *
+ * \param idmap_ctx idmap context to use
+ * \param low lower uid/gid bound is stored here
+ * \param high upper uid/gid bound is stored here
+ * \return 0 on success, nonzero on failure
+ */
+static int idmap_get_bounds(struct idmap_context *idmap_ctx, uint32_t *low,
+               uint32_t *high)
+{
+       int ret = -1;
+       struct ldb_context *ldb = idmap_ctx->ldb_ctx;
+       struct ldb_dn *dn;
+       struct ldb_result *res = NULL;
+       TALLOC_CTX *tmp_ctx = talloc_new(idmap_ctx);
+       uint32_t lower_bound = (uint32_t) -1;
+       uint32_t upper_bound = (uint32_t) -1;
+
+       dn = ldb_dn_new(tmp_ctx, ldb, "CN=CONFIG");
+       if (dn == NULL) goto failed;
+
+       ret = ldb_search(ldb, dn, LDB_SCOPE_BASE, NULL, NULL, &res);
+       if (ret != LDB_SUCCESS) goto failed;
+
+       talloc_steal(tmp_ctx, res);
+
+       if (res->count != 1) {
+               ret = -1;
+               goto failed;
+       }
+
+       lower_bound = ldb_msg_find_attr_as_uint(res->msgs[0], "lowerBound", -1);
+       if (lower_bound != (uint32_t) -1) {
+               ret = LDB_SUCCESS;
+       } else {
+               ret = -1;
+               goto failed;
+       }
+
+       upper_bound = ldb_msg_find_attr_as_uint(res->msgs[0], "upperBound", -1);
+       if (upper_bound != (uint32_t) -1) {
+               ret = LDB_SUCCESS;
+       } else {
+               ret = -1;
+       }
+
+failed:
+       talloc_free(tmp_ctx);
+       *low  = lower_bound;
+       *high = upper_bound;
+       return ret;
+}
+
+/**
+ * Add a dom_sid structure to a ldb_message
+ * \param idmap_ctx idmap context to use
+ * \param mem_ctx talloc context to use
+ * \param ldb_message ldb message to add dom_sid to
+ * \param attr_name name of the attribute to store the dom_sid in
+ * \param sid dom_sid to store
+ * \return 0 on success, an ldb error code on failure.
+ */
+static int idmap_msg_add_dom_sid(struct idmap_context *idmap_ctx,
+               TALLOC_CTX *mem_ctx, struct ldb_message *msg,
+               const char *attr_name, const struct dom_sid *sid)
+{
+       struct ldb_val val;
+       enum ndr_err_code ndr_err;
+
+       ndr_err = ndr_push_struct_blob(&val, mem_ctx,
+                                      lp_iconv_convenience(idmap_ctx->lp_ctx),
+                                      sid,
+                                      (ndr_push_flags_fn_t)ndr_push_dom_sid);
+
+       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+               return -1;
+       }
+
+       return ldb_msg_add_value(msg, attr_name, &val, NULL);
+}
+
+/**
+ * Get a dom_sid structure from a ldb message.
+ *
+ * \param mem_ctx talloc context to allocate dom_sid memory in
+ * \param msg ldb_message to get dom_sid from
+ * \param attr_name key that has the dom_sid as data
+ * \return dom_sid structure on success, NULL on failure
+ */
+static struct dom_sid *idmap_msg_get_dom_sid(TALLOC_CTX *mem_ctx,
+               struct ldb_message *msg, const char *attr_name)
+{
+       struct dom_sid *sid;
+       const struct ldb_val *val;
+       enum ndr_err_code ndr_err;
+
+       val = ldb_msg_find_ldb_val(msg, attr_name);
+       if (val == NULL) {
+               return NULL;
+       }
+
+       sid = talloc(mem_ctx, struct dom_sid);
+       if (sid == NULL) {
+               return NULL;
+       }
+
+       ndr_err = ndr_pull_struct_blob(val, sid, NULL, sid,
+                                      (ndr_pull_flags_fn_t)ndr_pull_dom_sid);
+       if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
+               talloc_free(sid);
+               return NULL;
+       }
+
+       return sid;
+}
+
+/**
+ * Initialize idmap context
+ *
+ * talloc_free to close.
+ *
+ * \param mem_ctx talloc context to use.
+ * \return allocated idmap_context on success, NULL on error
+ */
+struct idmap_context *idmap_init(TALLOC_CTX *mem_ctx,
+               struct loadparm_context *lp_ctx)
+{
+       struct idmap_context *idmap_ctx;
+
+       idmap_ctx = talloc(mem_ctx, struct idmap_context);
+       if (idmap_ctx == NULL) {
+               return NULL;
+       }
+
+       idmap_ctx->lp_ctx = lp_ctx;
+
+       idmap_ctx->ldb_ctx = ldb_wrap_connect(mem_ctx, lp_ctx,
+                                             lp_idmap_url(lp_ctx),
+                                             system_session(mem_ctx, lp_ctx),
+                                             NULL, 0, NULL);
+       if (idmap_ctx->ldb_ctx == NULL) {
+               return NULL;
+       }
+
+       return idmap_ctx;
+}
+
+/**
+ * Convert a uid to the corresponding SID
+ *
+ * \param idmap_ctx idmap context to use
+ * \param mem_ctx talloc context the memory for the struct dom_sid is allocated
+ * from.
+ * \param uid Unix uid to map to a SID
+ * \param sid Pointer that will take the struct dom_sid pointer if the mapping
+ * succeeds.
+ * \return NT_STATUS_OK on success, NT_STATUS_NONE_MAPPED if mapping not
+ * possible or some other NTSTATUS that is more descriptive on failure.
+ */
+
+NTSTATUS idmap_uid_to_sid(struct idmap_context *idmap_ctx, TALLOC_CTX *mem_ctx,
+               const uid_t uid, struct dom_sid **sid)
+{
+       int ret;
+       NTSTATUS status = NT_STATUS_NONE_MAPPED;
+       struct ldb_context *ldb = idmap_ctx->ldb_ctx;
+       struct ldb_message *msg;
+       struct ldb_result *res = NULL;
+       int trans = -1;
+       uid_t low, high;
+       char *sid_string, *uid_string;
+       struct dom_sid *unix_users_sid, *new_sid;
+       TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
+
+       ret = ldb_search_exp_fmt(ldb, tmp_ctx, &res, NULL, LDB_SCOPE_SUBTREE,
+                                NULL, "(&(objectClass=sidMap)(uidNumber=%u))",
+                                uid);
+       if (ret != LDB_SUCCESS) {
+               DEBUG(1, ("Search failed: %s\n", ldb_errstring(ldb)));
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       if (res->count == 1) {
+               *sid = idmap_msg_get_dom_sid(mem_ctx, res->msgs[0],
+                                            "objectSid");
+               if (*sid == NULL) {
+                       DEBUG(1, ("Failed to get sid from db: %u\n", ret));
+                       status = NT_STATUS_NONE_MAPPED;
+                       goto failed;
+               }
+               talloc_free(tmp_ctx);
+               return NT_STATUS_OK;
+       }
+
+       DEBUG(6, ("uid not found in idmap db, trying to allocate SID.\n"));
+
+       trans = ldb_transaction_start(ldb);
+       if (trans != LDB_SUCCESS) {
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       /* Now redo the search to make sure noone added a mapping for that SID
+        * while we weren't looking.*/
+       ret = ldb_search_exp_fmt(ldb, tmp_ctx, &res, NULL, LDB_SCOPE_SUBTREE,
+                                NULL, "(&(objectClass=sidMap)(uidNumber=%u))",
+                                uid);
+       if (ret != LDB_SUCCESS) {
+               DEBUG(1, ("Search failed: %s\n", ldb_errstring(ldb)));
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       if (res->count > 0) {
+               DEBUG(1, ("sidMap modified while trying to add a mapping.\n"));
+               status = NT_STATUS_RETRY;
+               goto failed;
+       }
+
+       ret = idmap_get_bounds(idmap_ctx, &low, &high);
+       if (ret != LDB_SUCCESS) {
+               DEBUG(1, ("Failed to get id bounds from db: %u\n", ret));
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       if (uid >= low && uid <= high) {
+               /* An existing user would have been mapped before */
+               status = NT_STATUS_NO_SUCH_USER;
+               goto failed;
+       }
+
+       /* For local users, we just create a rid = uid +1, so root doesn't end
+        * up with a 0 rid */
+       unix_users_sid = dom_sid_parse_talloc(tmp_ctx, "S-1-22-1");
+       if (unix_users_sid == NULL) {
+               status = NT_STATUS_NO_MEMORY;
+               goto failed;
+       }
+
+       new_sid = dom_sid_add_rid(mem_ctx, unix_users_sid, uid + 1);
+       if (new_sid == NULL) {
+               status = NT_STATUS_NO_MEMORY;
+               goto failed;
+       }
+
+       sid_string = dom_sid_string(tmp_ctx, new_sid);
+       if (sid_string == NULL) {
+               status = NT_STATUS_NO_MEMORY;
+               goto failed;
+       }
+
+       uid_string = talloc_asprintf(tmp_ctx, "%u", uid);
+       if (uid_string == NULL) {
+               status = NT_STATUS_NO_MEMORY;
+               goto failed;
+       }
+
+       msg = ldb_msg_new(tmp_ctx);
+       if (msg == NULL) {
+               status = NT_STATUS_NO_MEMORY;
+               goto failed;
+       }
+
+       msg->dn = ldb_dn_new_fmt(tmp_ctx, ldb, "CN=%s", sid_string);
+       if (msg->dn == NULL) {
+               status = NT_STATUS_NO_MEMORY;
+               goto failed;
+       }
+
+       ret = ldb_msg_add_string(msg, "uidNumber", uid_string);
+       if (ret != LDB_SUCCESS) {
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       ret = idmap_msg_add_dom_sid(idmap_ctx, tmp_ctx, msg, "objectSid",
+                                   new_sid);
+       if (ret != LDB_SUCCESS) {
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       ret = ldb_msg_add_string(msg, "objectClass", "sidMap");
+       if (ret != LDB_SUCCESS) {
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       ret = ldb_msg_add_string(msg, "cn", sid_string);
+       if (ret != LDB_SUCCESS) {
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       ret = ldb_add(ldb, msg);
+       if (ret != LDB_SUCCESS) {
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       trans = ldb_transaction_commit(ldb);
+       if (trans != LDB_SUCCESS) {
+               status = NT_STATUS_NONE_MAPPED;
+               goto failed;
+       }
+
+       *sid = new_sid;
+       talloc_free(tmp_ctx);
+       return NT_STATUS_OK;
+
+failed:
+       if (trans == LDB_SUCCESS) ldb_transaction_cancel(ldb);
+       talloc_free(tmp_ctx);
+       return status;
+}
+
+/**
+ * Map a Unix gid to the corresponding SID
+ *
+ * \todo Create a SID from the S-1-22-2 range for unmapped groups
+ *
+ * \param idmap_ctx idmap context to use
+ * \param mem_ctx talloc context the memory for the struct dom_sid is allocated
+ * from.
+ * \param gid Unix gid to map to a SID
+ * \param sid Pointer that will take the struct dom_sid pointer if mapping
+ * succeeds.
+ * \return NT_STATUS_OK on success, NT_STATUS_NONE_MAPPED if mapping not
+ * possible or some other NTSTATUS that is more descriptive on failure.
+ */
+NTSTATUS idmap_gid_to_sid(struct idmap_context *idmap_ctx, TALLOC_CTX *mem_ctx,
+               const gid_t gid, struct dom_sid **sid)
+{
+       return NT_STATUS_NONE_MAPPED;
+}
+
+/**
+ * Map a SID to a Unix uid.
+ *
+ * If no mapping exists, a new mapping will be created.
+ *
+ * \todo Create mappings for users not from our primary domain.
+ *
+ * \param idmap_ctx idmap context to use
+ * \param mem_ctx talloc context to use
+ * \param sid SID to map to a Unix uid
+ * \param uid pointer to receive the mapped uid
+ * \return NT_STATUS_OK on success, NT_STATUS_INVALID_SID if the sid is not from
+ * a trusted domain and idmap trusted only = true, NT_STATUS_NONE_MAPPED if the
+ * mapping failed.
+ */
+NTSTATUS idmap_sid_to_uid(struct idmap_context *idmap_ctx, TALLOC_CTX *mem_ctx,
+               const struct dom_sid *sid, uid_t *uid)
+{
+       return NT_STATUS_NONE_MAPPED;
+}
+
+/**
+ * Map a SID to a Unix gid.
+ *
+ * If no mapping exist, a new mapping will be created.
+ *
+ * \todo Create mappings for groups not from our primary domain.
+ *
+ * \param idmap_ctx idmap context to use
+ * \param mem_ctx talloc context to use
+ * \param sid SID to map to a Unix gid
+ * \param gid pointer to receive the mapped gid
+ * \return NT_STATUS_OK on success, NT_STATUS_INVALID_SID if the sid is not from
+ * a trusted domain and idmap trusted only = true, NT_STATUS_NONE_MAPPED if the
+ * mapping failed.
+ */
+NTSTATUS idmap_sid_to_gid(struct idmap_context *idmap_ctx, TALLOC_CTX *mem_ctx,
+               const struct dom_sid *sid, gid_t *gid)
+{
+       return NT_STATUS_NONE_MAPPED;
+}
+
diff --git a/source/winbind/idmap.h b/source/winbind/idmap.h
new file mode 100644 (file)
index 0000000..8781819
--- /dev/null
@@ -0,0 +1,33 @@
+/*
+   Unix SMB/CIFS implementation.
+
+   Map SIDs to uids/gids and back
+
+   Copyright (C) Kai Blin 2008
+
+   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
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _IDMAP_H_
+#define _IDMAP_H_
+
+struct idmap_context {
+       struct loadparm_context *lp_ctx;
+       struct ldb_context *ldb_ctx;
+};
+
+#include "winbind/idmap_proto.h"
+
+#endif
+
index 9b303f36158f32507e69ef5d3bbad7b07cb588c1..99191f3c6ce6a957398ec1ec3b0b397d33b1457f 100644 (file)
@@ -149,6 +149,12 @@ static void winbind_task_init(struct task_server *task)
                return;
        }
 
+       service->idmap_ctx = idmap_init(service, task->lp_ctx);
+       if (service->idmap_ctx == NULL) {
+               task_server_terminate(task, "Failed to load idmap database");
+               return;
+       }
+
        /* setup the unprivileged samba3 socket */
        listen_socket = talloc(service, struct wbsrv_listen_socket);
        if (!listen_socket) goto nomem;
index f3cfc185654b1c3bc2bd974b48b8544abdc1ea1e..ce972932f5378135b6569e98c1b44ab3ddcf58c6 100644 (file)
@@ -21,6 +21,7 @@
 
 #include "nsswitch/winbind_nss_config.h"
 #include "nsswitch/winbind_struct_protocol.h"
+#include "winbind/idmap.h"
 #include "libnet/libnet.h"
 
 #define WINBINDD_SAMBA3_SOCKET "pipe"
@@ -33,6 +34,7 @@ struct wbsrv_service {
 
        const struct dom_sid *primary_sid;
        struct wbsrv_domain *domains;
+       struct idmap_context *idmap_ctx;
 };
 
 struct wbsrv_samconn {
index d7a909fda2993c2a590516410bef77c20fcfde52..e81d2e46717e4ad168fa4f4c0ab14325ab7ed409 100644 (file)
@@ -3,7 +3,7 @@
 
    Command backend for wbinfo -U
 
-   Copyright (C) Kai Blin 2007
+   Copyright (C) Kai Blin 2007-2008
 
    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
@@ -25,6 +25,7 @@
 #include "smbd/service_task.h"
 #include "winbind/wb_helper.h"
 #include "libcli/security/proto.h"
+#include "winbind/idmap.h"
 
 struct uid2sid_state {
        struct composite_context *ctx;
@@ -50,10 +51,14 @@ struct composite_context *wb_uid2sid_send(TALLOC_CTX *mem_ctx,
        result->private_data = state;
        state->service = service;
 
-       /* FIXME: This is a stub so far.
-        * We cheat by just using the uid as RID with the domain SID.*/
-       state->sid = dom_sid_add_rid(result, service->primary_sid, uid);
-       if (composite_nomem(state->sid, state->ctx)) return result;
+       state->ctx->status = idmap_uid_to_sid(service->idmap_ctx, mem_ctx, uid,
+                                             &state->sid);
+       if (NT_STATUS_EQUAL(state->ctx->status, NT_STATUS_RETRY)) {
+               state->ctx->status = idmap_uid_to_sid(service->idmap_ctx,
+                                                     mem_ctx, uid,
+                                                     &state->sid);
+       }
+       if (!composite_is_ok(state->ctx)) return result;
 
        composite_done(state->ctx);
        return result;