* Added autotool check for getresuid (and related functions) necessary for lowering of priviliges for backend and restconf

* If getresuid is not available, CLICON_RESTCONF_PRIVILEGES must be set to 'none'

CHANGELOG.md

@@ -77,6 +77,8 @@ Users may have to change how they access the system
 
 ### Minor features
 
+* Added autotool check for getresuid (+ related functions) necessary for lowering of priviliges for backend and restconf
+  * If getresuid is not available, CLICON_RESTCONF_PRIVILEGES must be set to 'none'
 * Added new startup-mode: `running-startup`: First try running db, if it is empty try startup db.
   * See [Can startup mode to be extended to support running-startup mode? #234](https://github.com/clicon/clixon/issues/234)
 * Restconf: added inline configuration using `-R <xml>` command line as an alternative to making advanced restconf configuration

configure

@@ -5564,7 +5564,7 @@ fi
 fi
 
 #
-for ac_func in inet_aton sigaction sigvec strlcpy strsep strndup alphasort versionsort getpeereid setns
+for ac_func in inet_aton sigaction sigvec strlcpy strsep strndup alphasort versionsort getpeereid setns getresuid
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"

configure.ac

@@ -296,7 +296,7 @@ if test "${with_libxml2}"; then
 fi 
 
 #
-AC_CHECK_FUNCS(inet_aton sigaction sigvec strlcpy strsep strndup alphasort versionsort getpeereid setns)
+AC_CHECK_FUNCS(inet_aton sigaction sigvec strlcpy strsep strndup alphasort versionsort getpeereid setns getresuid)
 
 # Checks for getsockopt options for getting unix socket peer credentials on
 # Linux

include/clixon_config.h.in

@@ -30,6 +30,9 @@
 /* Define to 1 if you have the `getpeereid' function. */
 #undef HAVE_GETPEEREID
 
+/* Define to 1 if you have the `getresuid' function. */
+#undef HAVE_GETRESUID
+
 /* Define to 1 if you have the `inet_aton' function. */
 #undef HAVE_INET_ATON
 

lib/src/clixon_uid.c

@@ -170,6 +170,7 @@ uid2name(const uid_t uid,
 int
 drop_priv_temp(uid_t new_uid)
 {
+#ifdef HAVE_GETRESUID
     int retval = -1;
     
     /* XXX: implicit declaration of function 'setresuid' on travis */
@@ -184,6 +185,10 @@ drop_priv_temp(uid_t new_uid)
     retval = 0;
  done:
     return retval;
+#else
+    clicon_debug(1, "%s Drop privileges not implemented on this platform since getresuid is not available", __FUNCTION__);
+    return 0;
+#endif
 }
 
 /*! Permanently drop privileges 
@@ -192,6 +197,7 @@ drop_priv_temp(uid_t new_uid)
 int
 drop_priv_perm(uid_t new_uid)
 {
+#ifdef HAVE_GETRESUID
     int retval = -1;
     uid_t ruid;
     uid_t euid;
@@ -214,12 +220,17 @@ drop_priv_perm(uid_t new_uid)
     retval = 0;
  done:
     return retval;
+#else
+    clicon_debug(1, "%s Drop privileges not implemented on this platform since getresuid is not available", __FUNCTION__);
+    return 0;
+#endif
 }
 
 /*! Restore privileges to saved level */
 int
 restore_priv(void)
 {
+#ifdef HAVE_GETRESUID
     int retval = -1;
     uid_t ruid;
     uid_t euid;
@@ -240,4 +251,8 @@ restore_priv(void)
     retval = 0;
  done:
     return retval;
+#else
+    clicon_debug(1, "%s Drop privileges not implemented on this platform since getresuid is not available", __FUNCTION__);
+    return 0;
+#endif
 }

yang/clixon/clixon-config@2021-05-20.yang

@@ -536,7 +536,10 @@ module clixon-config {
 	    default drop_perm;
 	    description 
 		"Restconf privileges mode. 
-                 If drop_perm or drop_temp then drop privileges to CLICON_RESTCONF_USER.";
+                 If drop_perm or drop_temp then drop privileges to CLICON_RESTCONF_USER.
+                 If the platform does not support getresuid and accompanying functions, the mode
+                 must be set to 'none'.
+                 ";
 	}
 	leaf CLICON_CLI_DIR {
 	    type string;