NSS: Add fallback_homedir option

This option is similar to override_homedir, except that it will
take effect only for users that do not have an explicit home
directory specified in LDAP.

https://fedorahosted.org/sssd/ticket/1250

3 files changed, 27 insertions, 2 deletions

diff --git a/src/responder/nss/nsssrv.c b/src/responder/nss/nsssrv.c
index 1a0dcf43..c8ee444a 100644
--- a/src/responder/nss/nsssrv.c
+++ b/src/responder/nss/nsssrv.c
@@ -178,6 +178,11 @@ static int nss_get_config(struct nss_ctx *nctx,
                             &nctx->override_homedir);
     if (ret != EOK) goto done;
 
+    ret = confdb_get_string(cdb, nctx, CONFDB_NSS_CONF_ENTRY,
+                            CONFDB_NSS_FALLBACK_HOMEDIR, NULL,
+                            &nctx->fallback_homedir);
+    if (ret != EOK) goto done;
+
     ret = confdb_get_string_as_list(cdb, nctx, CONFDB_NSS_CONF_ENTRY,
                                     CONFDB_NSS_ALLOWED_SHELL,
                                     &nctx->allowed_shells);
diff --git a/src/responder/nss/nsssrv.h b/src/responder/nss/nsssrv.h
index 2871c2bf..5b5ae50b 100644
--- a/src/responder/nss/nsssrv.h
+++ b/src/responder/nss/nsssrv.h
@@ -61,6 +61,7 @@ struct nss_ctx {
     char *pwfield;
 
     char *override_homedir;
+    char *fallback_homedir;
     char **allowed_shells;
     char **vetoed_shells;
     char **etc_shells;
diff --git a/src/responder/nss/nsssrv_cmd.c b/src/responder/nss/nsssrv_cmd.c
index 508db556..d448fa85 100644
--- a/src/responder/nss/nsssrv_cmd.c
+++ b/src/responder/nss/nsssrv_cmd.c
@@ -122,6 +122,11 @@ static const char *get_homedir_override(TALLOC_CTX *mem_ctx,
                                         const char *name,
                                         uint32_t uid)
 {
+    const char *homedir;
+
+    /* Check whether we are unconditionally overriding the server
+     * for home directory locations.
+     */
     if (dom->override_homedir) {
         return expand_homedir_template(mem_ctx, dom->override_homedir,
                                        name, uid, dom->name);
@@ -130,8 +135,22 @@ static const char *get_homedir_override(TALLOC_CTX *mem_ctx,
                                        name, uid, dom->name);
     }
 
-    return talloc_strdup(mem_ctx,
-            ldb_msg_find_attr_as_string(msg, SYSDB_HOMEDIR, NULL));
+    homedir = ldb_msg_find_attr_as_string(msg, SYSDB_HOMEDIR, NULL);
+    if (!homedir || *homedir == '\0') {
+        /* In the case of a NULL or empty homedir, check to see if
+         * we have a fallback homedir to use.
+         */
+        if (dom->fallback_homedir) {
+            return expand_homedir_template(mem_ctx, dom->fallback_homedir,
+                                           name, uid, dom->name);
+        } else if (nctx->fallback_homedir) {
+            return expand_homedir_template(mem_ctx, nctx->fallback_homedir,
+                                           name, uid, dom->name);
+        }
+    }
+
+    /* Return the value we got from the provider */
+    return talloc_strdup(mem_ctx, homedir);
 }
 
 static const char *get_shell_override(TALLOC_CTX *mem_ctx,