main: add option to disable check for root

The -U option can be used to start chronyd under a non-root user if it
is provided with all capabilities and access to files, directories, and
devices, needed to operate correctly in the specified configuration. It
is not recommended in cases where the configuration is unknown.

diff --git a/doc/chronyd.adoc b/doc/chronyd.adoc
index 739950b9cad4f39ebf4a9d4f5b3f9e4cc1e46a3e..c9f51b307e66a3d87c1d581ee939243660956606 100644 (file)
--- a/doc/chronyd.adoc
+++ b/doc/chronyd.adoc
@@ -145,6 +145,16 @@ On macOS, FreeBSD, NetBSD and Solaris *chronyd* forks into two processes.
 The child process retains root privileges, but can only perform a very limited
 range of privileged system calls on behalf of the parent.
 
+*-U*::
+This option disables a check for root privileges to allow *chronyd* to be
+started under a non-root user, assuming the process will have all capabilities
+(e.g. provided by the service manager) and access to all files, directories,
+and devices, needed to operate correctly in the specified configuration. Note
+that different capabilities might be needed with different configurations and
+different Linux kernel versions. Starting *chronyd* under a non-root user is
+not recommended when the configuration is not known, or at least limited to
+specific directives.
+
 *-F* _level_::
 This option configures a system call filter when *chronyd* is compiled with
 support for the Linux secure computing (seccomp) facility. In level 1 the

diff --git a/main.c b/main.c
index 0c9be367feb199f5e601887bbab608a8f2d82799..958d04700513519488e5fe11c344405286b5b28b 100644 (file)
--- a/main.c
+++ b/main.c
@@ -411,7 +411,7 @@ int main
   int do_init_rtc = 0, restarted = 0, client_only = 0, timeout = -1;
   int scfilter_level = 0, lock_memory = 0, sched_priority = 0;
   int clock_control = 1, system_log = 1, log_severity = LOGS_INFO;
-  int config_args = 0, print_config = 0;
+  int user_check = 1, config_args = 0, print_config = 0;
 
   do_platform_checks();
 
@@ -431,7 +431,7 @@ int main
   optind = 1;
 
   /* Parse short command-line options */
-  while ((opt = getopt(argc, argv, "46df:F:hl:L:mnpP:qQrRst:u:vx")) != -1) {
+  while ((opt = getopt(argc, argv, "46df:F:hl:L:mnpP:qQrRst:u:Uvx")) != -1) {
     switch (opt) {
       case '4':
       case '6':
@@ -462,7 +462,7 @@ int main
         break;
       case 'p':
         print_config = 1;
-        client_only = 1;
+        user_check = 0;
         nofork = 1;
         system_log = 0;
         break;
@@ -479,6 +479,7 @@ int main
         ref_mode = REF_ModePrintOnce;
         nofork = 1;
         client_only = 1;
+        user_check = 0;
         clock_control = 0;
         system_log = 0;
         break;
@@ -497,6 +498,9 @@ int main
       case 'u':
         user = optarg;
         break;
+      case 'U':
+        user_check = 0;
+        break;
       case 'v':
         print_version();
         return 0;
@@ -509,7 +513,7 @@ int main
     }
   }
 
-  if (getuid() && !client_only)
+  if (user_check && getuid() != 0)
     LOG_FATAL("Not superuser");
 
   /* Turn into a daemon */