From: fatbob313 <martin@fatbob.nu>
Date: Sun, 23 Jan 2011 11:58:12 +0000 (+0000)
Subject: Issue 15 - Patch by tilman2: Drop privileges optionally
X-Git-Url: http://git.code-monkey.de/?p=umurmur.git;a=commitdiff_plain;h=454ad122eb158b4391e2690fe6a7e127d24c525b

Issue 15 - Patch by tilman2: Drop privileges optionally
---

diff --git a/src/conf.c b/src/conf.c
index 72fd8f1..3592647 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -136,6 +136,28 @@ const char *getStrConf(param_t param)
 			return "";
 		}
 		break;
+	case USERNAME:
+		setting = config_lookup(&configuration, "username");
+		if (!setting)
+			return "";
+		else {
+			if ((strsetting = config_setting_get_string(setting)) != NULL)
+				return strsetting;
+			else
+			return "";
+		}
+		break;
+	case GROUPNAME:
+		setting = config_lookup(&configuration, "groupname");
+		if (!setting)
+			return "";
+		else {
+			if ((strsetting = config_setting_get_string(setting)) != NULL)
+				return strsetting;
+			else
+			return "";
+		}
+		break;
 	default:
 		doAssert(false);
 		break;
diff --git a/src/conf.h b/src/conf.h
index 1b9b21e..6e0a666 100644
--- a/src/conf.h
+++ b/src/conf.h
@@ -43,6 +43,8 @@ typedef enum param {
 	MAX_BANDWIDTH,
 	MAX_CLIENTS,
 	DEFAULT_CHANNEL,
+	USERNAME,
+	GROUPNAME,
 } param_t;
 
 typedef struct {
diff --git a/src/main.c b/src/main.c
index 7bd8a0b..36c5f88 100644
--- a/src/main.c
+++ b/src/main.c
@@ -36,6 +36,8 @@
 #include <sys/stat.h>
 #include <sys/utsname.h>
 #include <fcntl.h>
+#include <pwd.h>
+#include <grp.h>
 #include <signal.h>
 #include <errno.h>
 #include <string.h>
@@ -70,6 +72,59 @@ void lockfile(const char *pidfile)
 	Log_info("PID-file: %s", pidfile);
 }
 
+/* Drops privileges (if configured to do so). */
+static void switch_user(void)
+{
+	struct passwd *pwd;
+	struct group *grp = NULL;
+	const char *username, *groupname;
+	gid_t gid;
+
+	username = getStrConf(USERNAME);
+	groupname = getStrConf(GROUPNAME);
+
+	if (!*username) {
+		/* It's an error to specify groupname
+		 * but leave username empty.
+		 */
+		if (*groupname)
+			Log_fatal("username missing");
+
+		/* Nothing to do. */
+		return;
+	}
+
+	pwd = getpwnam(username);
+	if (!pwd)
+		Log_fatal("Unknown user '%s'", username);
+
+	if (!*groupname)
+		gid = pwd->pw_gid;
+	else {
+		grp = getgrnam(groupname);
+
+		if (!grp)
+			Log_fatal("Unknown group '%s'", groupname);
+
+		gid = grp->gr_gid;
+	}
+
+	if (initgroups(pwd->pw_name, gid))
+		Log_fatal("initgroups() failed: %s", strerror(errno));
+
+	if (setgid(gid))
+		Log_fatal("setgid() failed: %s", strerror(errno));
+
+	if (setuid(pwd->pw_uid))
+		Log_fatal("setuid() failed: %s", strerror(errno));
+	
+	if (!grp)
+		grp = getgrgid(gid);
+	if (!grp)
+		Log_fatal("getgrgid() failed: %s", strerror(errno));
+	
+	Log_info("Switch to user '%s' group '%s'", pwd->pw_name, grp->gr_name);
+}
 
 void signal_handler(int sig)
 {
@@ -189,18 +244,28 @@ int main(int argc, char **argv)
 			break;
 		}
 	}
+
+	/* Logging to terminal if not daemonizing, otherwise to syslog.
+	 * Need to initialize logging before calling Conf_init()
+	 */
+	if (!nodaemon)
+		Log_init(false);
+	else
+		Log_init(true);
 	
+	/* Initialize the config subsystem early;
+	 * switch_user() will need to read some config variables.
+	 */
+	Conf_init(conffile);
+
 	if (!nodaemon) {
-		Log_init(false);
 		daemonize();
 		if (pidfile != NULL)
 			lockfile(pidfile);
+
+		switch_user();
 	}
-	else
-		Log_init(true);
 
-	Conf_init(conffile);
-			
 	signal(SIGCHLD, SIG_IGN); /* ignore child */
 	signal(SIGTSTP, SIG_IGN); /* ignore tty signals */
 	signal(SIGTTOU, SIG_IGN);
diff --git a/umurmur.conf.example b/umurmur.conf.example
index 47c0dea..09b49c5 100644
--- a/umurmur.conf.example
+++ b/umurmur.conf.example
@@ -4,6 +4,8 @@ certificate = "/etc/umurmur/cert.crt";
 private_key = "/etc/umurmur/key.key";
 password = "";
 max_users = 10;
+username = "";
+groupname = "";
 
 # Root channel must always be defined first.
 # If a channel has a parent, the parent must be defined before the child channel(s).