CONFIG: Use default config when none provided

This patch makes SSSD possibly useful "out of the box" by allowing
packagers to provide a default config file located in $LIBDIR/sssd/conf
that will be copied by the monitor to /etc/sssd if no file already
exists in that location. This will make it possible to have SSSD set up
to have distribution-specific default configuration, such as enabling
the proxy provider to cache /etc/passwd (such as in the provided
example in this patch).

Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>

2 files changed, 37 insertions, 4 deletions

diff --git a/src/confdb/confdb.h b/src/confdb/confdb.h
index b90ced2bb..a9b1c4362 100644
--- a/src/confdb/confdb.h
+++ b/src/confdb/confdb.h
@@ -40,6 +40,7 @@
 
 #define CONFDB_DEFAULT_CFG_FILE_VER 2
 #define CONFDB_FILE "config.ldb"
+#define SSSD_DEFAULT_CONFIG_FILE SSSD_DEFAULT_CONF_DIR"/sssd.conf"
 #define SSSD_CONFIG_FILE SSSD_CONF_DIR"/sssd.conf"
 #define SSSD_MIN_ID 1
 #define SSSD_LOCAL_MINID 1000
diff --git a/src/confdb/confdb_setup.c b/src/confdb/confdb_setup.c
index 694a7f016..dfdcae566 100644
--- a/src/confdb/confdb_setup.c
+++ b/src/confdb/confdb_setup.c
@@ -21,12 +21,14 @@
 
 #include "config.h"
 #include <sys/stat.h>
+#include <unistd.h>
 #include "util/util.h"
 #include "db/sysdb.h"
 #include "confdb.h"
 #include "confdb_private.h"
 #include "confdb_setup.h"
 #include "util/sss_ini.h"
+#include "tools/tools_util.h"
 
 
 int confdb_test(struct confdb_ctx *cdb)
@@ -159,11 +161,41 @@ int confdb_init_db(const char *config_file, struct confdb_ctx *cdb)
         DEBUG(SSSDBG_TRACE_FUNC,
               "sss_ini_config_file_open failed: %s [%d]\n", strerror(ret),
                ret);
-        if (ret == ENOENT) {
-            /* sss specific error denoting missing configuration file */
-            ret = ERR_MISSING_CONF;
+        if (ret != ENOENT) {
+            /* Anything other than ENOENT is unrecoverable */
+            goto done;
+        } else {
+            /* Copy the default configuration file to the standard location
+             * and then retry
+             */
+             ret = copy_file_secure(SSSD_DEFAULT_CONFIG_FILE,
+                                    SSSD_CONFIG_FILE,
+                                    0600,
+                                    getuid(),
+                                    getgid(),
+                                    false);
+             if (ret != EOK) {
+                 DEBUG(SSSDBG_FATAL_FAILURE,
+                       "Could not copy default configuration: %s",
+                       sss_strerror(ret));
+                 /* sss specific error denoting missing configuration file */
+                 ret = ERR_MISSING_CONF;
+                 goto done;
+             }
+
+             /* Try again */
+             ret = sss_ini_config_file_open(init_data, config_file);
+            if (ret != EOK) {
+                DEBUG(SSSDBG_TRACE_FUNC,
+                      "sss_ini_config_file_open(default) failed: %s [%d]\n",
+                      strerror(ret), ret);
+                if (ret == ENOENT) {
+                    /* sss specific error denoting missing configuration file */
+                    ret = ERR_MISSING_CONF;
+                }
+                goto done;
+            }
         }
-        goto done;
     }
 
     ret = sss_ini_config_access_check(init_data);