main: don't require root privileges with -Q option

If the -Q option is specified, disable by default pidfile, ntpport,
cmdport, Unix domain command socket, and clock control, in order to
allow starting chronyd without root privileges and/or when another
chronyd instance is already running.

conf.c

@@ -323,7 +323,7 @@ check_number_of_args(char *line, int num)
 /* ================================================== */
 
 void
-CNF_Initialise(int r)
+CNF_Initialise(int r, int client_only)
 {
   restarted = r;
 
@@ -339,11 +339,18 @@ CNF_Initialise(int r)
 
   dumpdir = Strdup("");
   logdir = Strdup("");
-  bind_cmd_path = Strdup(DEFAULT_COMMAND_SOCKET);
-  pidfile = Strdup(DEFAULT_PID_FILE);
   rtc_device = Strdup(DEFAULT_RTC_DEVICE);
   hwclock_file = Strdup(DEFAULT_HWCLOCK_FILE);
   user = Strdup(DEFAULT_USER);
+
+  if (client_only) {
+    cmd_port = ntp_port = 0;
+    bind_cmd_path = Strdup("");
+    pidfile = Strdup("");
+  } else {
+    bind_cmd_path = Strdup(DEFAULT_COMMAND_SOCKET);
+    pidfile = Strdup(DEFAULT_PID_FILE);
+  }
 }
 
 /* ================================================== */

conf.h

@@ -31,7 +31,7 @@
 #include "addressing.h"
 #include "reference.h"
 
-extern void CNF_Initialise(int restarted);
+extern void CNF_Initialise(int restarted, int client_only);
 extern void CNF_Finalise(void);
 
 extern char *CNF_GetRtcDevice(void);

doc/chronyd.adoc

@@ -75,8 +75,9 @@ When run in this mode, *chronyd* will set the system clock once and exit. It
 will not detach from the terminal.
 
 *-Q*::
-This option is similar to *-q*, but it will only print the offset without any
+This option is similar to the *-q* option, except it only prints the offset
-corrections of the clock.
+without making any corrections of the clock and it allows *chronyd* to be
+started without root privileges.
 
 *-r*::
 This option will try to reload and then delete files containing sample

main.c

@@ -86,6 +86,10 @@ static void
 delete_pidfile(void)
 {
   const char *pidfile = CNF_GetPidFile();
+
+  if (!pidfile[0])
+    return;
+
   /* Don't care if this fails, there's not a lot we can do */
   unlink(pidfile);
 }
@@ -274,6 +278,9 @@ write_pidfile(void)
   const char *pidfile = CNF_GetPidFile();
   FILE *out;
 
+  if (!pidfile[0])
+    return;
+
   out = fopen(pidfile, "w");
   if (!out) {
     LOG_FATAL("Could not open %s : %s", pidfile, strerror(errno));
@@ -388,7 +395,7 @@ int main
   char *user = NULL, *log_file = NULL;
   struct passwd *pw;
   int opt, debug = 0, nofork = 0, address_family = IPADDR_UNSPEC;
-  int do_init_rtc = 0, restarted = 0, timeout = 0;
+  int do_init_rtc = 0, restarted = 0, client_only = 0, timeout = 0;
   int scfilter_level = 0, lock_memory = 0, sched_priority = 0;
   int clock_control = 1, system_log = 1;
   int config_args = 0;
@@ -444,6 +451,8 @@ int main
       case 'Q':
         ref_mode = opt == 'q' ? REF_ModeUpdateOnce : REF_ModePrintOnce;
         nofork = 1;
+        client_only = 1;
+        clock_control = 0;
         system_log = 0;
         break;
       case 'r':
@@ -473,9 +482,8 @@ int main
     }
   }
 
-  if (getuid() != 0) {
+  if (getuid() && !client_only)
     LOG_FATAL("Not superuser");
-  }
 
   /* Turn into a daemon */
   if (!nofork) {
@@ -494,7 +502,7 @@ int main
 
   DNS_SetAddressFamily(address_family);
 
-  CNF_Initialise(restarted);
+  CNF_Initialise(restarted, client_only);
 
   /* Parse the config file or the remaining command line arguments */
   config_args = argc - optind;
@@ -548,8 +556,8 @@ int main
   /* Create all directories before dropping root */
   CNF_CreateDirs(pw->pw_uid, pw->pw_gid);
 
-  /* Drop root privileges if the user has non-zero uid or gid */
+  /* Drop root privileges if the specified user has a non-zero UID */
-  if (pw->pw_uid || pw->pw_gid)
+  if (!geteuid() && (pw->pw_uid || pw->pw_gid))
     SYS_DropRoot(pw->pw_uid, pw->pw_gid);
 
   REF_Initialise();

test/unit/clientlog.c

@@ -33,7 +33,7 @@ test_unit(void)
     "cmdratelimit interval 3 burst 4 leak 3",
   };
 
-  CNF_Initialise(0);
+  CNF_Initialise(0, 0);
   for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
     CNF_ParseLine(NULL, i + 1, conf[i]);
 

test/unit/keys.c

@@ -90,7 +90,7 @@ test_unit(void)
     "keyfile "KEYFILE
   };
 
-  CNF_Initialise(0);
+  CNF_Initialise(0, 0);
   for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
     CNF_ParseLine(NULL, i + 1, conf[i]);
 

test/unit/ntp_core.c

@@ -218,7 +218,7 @@ test_unit(void)
   CPS_NTP_Source source;
   NTP_Remote_Address remote_addr;
 
-  CNF_Initialise(0);
+  CNF_Initialise(0, 0);
   for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
     CNF_ParseLine(NULL, i + 1, conf[i]);
 

test/unit/ntp_sources.c

@@ -34,7 +34,7 @@ test_unit(void)
 
   memset(&params, 0, sizeof (params));
 
-  CNF_Initialise(0);
+  CNF_Initialise(0, 0);
   CNF_ParseLine(NULL, 1, conf);
 
   LCL_Initialise();

test/unit/smooth.c

@@ -29,7 +29,7 @@ test_unit(void)
   double offset, freq, wander;
   char conf[] = "smoothtime 300 0.01";
 
-  CNF_Initialise(0);
+  CNF_Initialise(0, 0);
   CNF_ParseLine(NULL, 1, conf);
 
   LCL_Initialise();

test/unit/sources.c

@@ -31,7 +31,7 @@ test_unit(void)
   double offset, delay, disp;
   struct timespec ts;
 
-  CNF_Initialise(0);
+  CNF_Initialise(0, 0);
   LCL_Initialise();
   TST_RegisterDummyDrivers();
   SCH_Initialise();