PR: Added support for user/group settings.

README.md

@@ -59,6 +59,10 @@ use the provided `init_script` file as a starting point.
 For systems running systemd, there is a spacenavd.service file under
 `contrib/systemd`. Follow your system documentation for how to use it.
 
+Spacenavd (in daemonmode) can drop root privileges and run under an other user or
+group. For this, start spacenavd with -u <username> / -g <group> or specify the
+user / group in `/etc/spnavrc`.
+
 Configuration
 -------------
 The spacenavd daemon reads a number of options from `/etc/spnavrc`. If

doc/example-spnavrc

@@ -136,3 +136,12 @@
 # Combine multiple options by listing them on the same line.
 #
 #log = file, syslog
+
+
+# User and group settings
+#
+# When a user or a group is specified, spacenavd drops for serveral functions
+# the root privileges and run this codeparts under the given user- and groupname. 
+#
+#user = <valid-username>
+#group = <valid-groupname>

src/cfgfile.c

@@ -25,6 +25,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "cfgfile.h"
 #include "logger.h"
 #include "spnavd.h"
+#include "userpriv.h"
 
 enum {TX, TY, TZ, RX, RY, RZ};
 
@@ -84,6 +85,8 @@ int read_cfg(const char *fname, struct cfg *cfg)
 	int num_devid = 0;
 	/*int num_devnames = 0;*/
 
+        int username_from_cfg = 0, groupname_from_cfg = 0;
+
 	default_cfg(cfg);
 
 	logmsg(LOG_INFO, "reading config file: %s\n", fname);
@@ -313,7 +316,23 @@ int read_cfg(const char *fname, struct cfg *cfg)
 				continue;
 			}
 
-		} else {
+		} else if(strcmp(key_str, "user") == 0) {
+                    if(user_set_by_cmdline() == 1) {
+                        logmsg(LOG_WARNING, "started with -u option - ignoring user setting in configfile\n");
+                    } else if(set_runas_uid (val_str) == 0) {
+                        logmsg(LOG_WARNING, "invalid configuration value for %s, expected a valid username (%s doesn't exists) - resuming with invoked user\n", key_str, val_str);
+                    } else {
+                        username_from_cfg = 1;
+                    }
+                } else if(strcmp(key_str, "group") == 0) {
+                    if(group_set_by_cmdline() == 1) {
+                        logmsg(LOG_WARNING, "started with -g option - ignoring group setting in configfile\n");
+                    } else if(set_runas_gid (val_str) == 0) {
+                        logmsg(LOG_WARNING, "invalid configuration value for %s, expected a valid groupname (%s doesn't exists) - resuming with invoked group\n", key_str, val_str);
+                    } else {
+                        groupname_from_cfg = 1;
+                    }
+                } else {
 			logmsg(LOG_WARNING, "unrecognized config option: %s\n", key_str);
 		}
 	}
@@ -325,6 +344,12 @@ int read_cfg(const char *fname, struct cfg *cfg)
 	fcntl(fileno(fp), F_SETLK, &flk);
 
 	fclose(fp);
+
+        if(username_from_cfg || groupname_from_cfg) {
+            test_initial_user_privileges();
+            start_daemon_privileges();
+        }
+
 	return 0;
 }
 

src/dev.c

@@ -20,6 +20,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include "userpriv.h"
 #include "dev.h"
 #include "dev_usb.h"
 #include "dev_serial.h"
@@ -42,6 +43,9 @@ int init_devices(void)
 	int i, device_added = 0;
 	struct usb_device_info *usblist, *usbdev;
 
+        /* restore initial uid / gid */
+        stop_daemon_privileges();
+
 	/* try to open a serial device if specified in the config file */
 	if(cfg.serial_dev[0]) {
 		if(!dev_path_in_use(cfg.serial_dev)) {
@@ -86,6 +90,9 @@ int init_devices(void)
 
 	free_usb_devices_list(usblist);
 
+        /* use daemon uid / gid again */
+        start_daemon_privileges();
+
 	if(!usblist) {
 		logmsg(LOG_ERR, "failed to find any supported devices\n");
 		return -1;

src/proto_unix.c

@@ -26,6 +26,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <sys/stat.h>
 #include <sys/un.h>
 #include "proto_unix.h"
+#include "userpriv.h"
 #include "spnavd.h"
 
 enum {
@@ -44,8 +45,11 @@ int init_unix(void)
 
 	if(lsock >= 0) return 0;
 
+        stop_daemon_privileges();
+
 	if((s = socket(PF_UNIX, SOCK_STREAM, 0)) == -1) {
 		logmsg(LOG_ERR, "failed to create socket: %s\n", strerror(errno));
+                start_daemon_privileges();
 		return -1;
 	}
 
@@ -60,9 +64,12 @@ int init_unix(void)
 	if(bind(s, (struct sockaddr*)&addr, sizeof addr) == -1) {
 		logmsg(LOG_ERR, "failed to bind unix socket: %s: %s\n", SOCK_NAME, strerror(errno));
 		close(s);
+                start_daemon_privileges();
 		return -1;
 	}
 
+	start_daemon_privileges();
+
 	umask(prev_umask);
 
 	if(listen(s, 8) == -1) {
@@ -79,10 +86,14 @@ int init_unix(void)
 void close_unix(void)
 {
 	if(lsock != -1) {
+                stop_daemon_privileges();
+
 		close(lsock);
 		lsock = -1;
 
 		unlink(SOCK_NAME);
+
+                start_daemon_privileges();
 	}
 }
 

src/spnavd.c

@@ -29,6 +29,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <sys/un.h>
 #include "spnavd.h"
 #include "logger.h"
+#include "userpriv.h"
 #include "dev.h"
 #include "hotplug.h"
 #include "client.h"
@@ -48,9 +49,20 @@ static char *fix_path(char *str);
 static char *cfgfile = DEF_CFGFILE;
 static char *logfile = DEF_LOGFILE;
 
+/* struct for privilege changes */
+userid_struct *userids = NULL;
+
 int main(int argc, char **argv)
 {
 	int i, pid, ret, become_daemon = 1;
+        int use_username = 0;
+        int use_groupname = 0;
+
+        /* allocate memory the userprivilege struct */
+        userids = malloc(sizeof(userid_struct));
+
+        /* prefill the userid struct */
+        set_initial_user_privileges();
 
 	for(i=1; i<argc; i++) {
 		if(argv[i][0] == '-') {
@@ -87,6 +99,34 @@ int main(int argc, char **argv)
 					verbose = 1;
 					break;
 
+                                case 'u':
+                                        /* optional username for daemonize */
+                                        use_username = 1;
+					if(!argv[++i]) {
+						fprintf(stderr, "-u must be followed by a username\n");
+						return 1;
+					}
+					if(set_runas_uid(argv[i]) == 0)
+                                        {
+                                            fprintf(stderr, "Invalid username: %s\n", argv[i]);
+                                            return 1;
+                                        }
+                                        break;
+
+                                case 'g':
+                                        /* optional groupname for daemonize */
+                                        use_groupname = 1;
+					if(!argv[++i]) {
+						fprintf(stderr, "-g must be followed by a groupname\n");
+						return 1;
+					}
+					if(set_runas_gid(argv[i]) == 0)
+                                        {
+                                            fprintf(stderr, "Invalid groupname: %s\n", argv[i]);
+                                            return 1;
+                                        }
+                                        break;
+
 				case 'V':
 					printf("spacenavd " VERSION "\n");
 					return 0;
@@ -98,6 +138,8 @@ int main(int argc, char **argv)
 					printf(" -c <file>: config file path (default: " DEF_CFGFILE ")\n");
 					printf(" -l <file>|syslog: log file path or log to syslog (default: " DEF_LOGFILE ")\n");
 					printf(" -v: verbose output\n");
+                                        printf(" -u <username>: username for daemonize (optional)\n");
+                                        printf(" -g <groupname>: groupname for daemonize (optional)\n");
 					printf(" -V,-version: print version number and exit\n");
 					printf(" -h: print usage information and exit\n");
 					return 0;
@@ -121,6 +163,20 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if ((use_username || use_groupname) && !become_daemon) {
+            fprintf(stderr, "-u / -g needs daemonmode (omit -d option) - not valid in standalone mode\n");
+            free(userids);
+            return 1;
+        }
+
+        if(userids != NULL) {
+            userids->runas_daemon = become_daemon;
+            userids->has_cmd_user = use_username;
+            userids->has_cmd_group = use_groupname;
+        }
+
+        test_initial_user_privileges();
+
 	if((pid = find_running_daemon()) != -1) {
 		fprintf(stderr, "Spacenav daemon already running (pid: %d). Aborting.\n", pid);
 		return 1;
@@ -129,7 +185,10 @@ int main(int argc, char **argv)
 	if(become_daemon) {
 		daemonize();
 	}
-	write_pid_file();
+        write_pid_file();
+
+        /* change uid / gid */
+        start_daemon_privileges();
 
 	logmsg(LOG_INFO, "Spacenav daemon " VERSION "\n");
 
@@ -257,7 +316,11 @@ static void cleanup(void)
 		remove_device(tmp);
 	}
 
+	stop_daemon_privileges();
 	remove(PIDFILE);
+        start_daemon_privileges();
+
+        free(userids);
 }
 
 static void daemonize(void)

src/spnavd.h

@@ -48,7 +48,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #endif
 
 
-
 struct cfg cfg;
 int verbose;