capability API to allow plugin-controlled capability set

src/charon/daemon.c

@@ -80,6 +80,11 @@ struct private_daemon_t {
 	 * The thread_id of main-thread.
 	 */
 	pthread_t main_thread_id;
+	
+	/**
+	 * capabilities to keep
+	 */
+	u_int32_t keep;
 };
 
 /**
@@ -247,41 +252,20 @@ static void kill_daemon(private_daemon_t *this, char *reason)
 /**
  * drop daemon capabilities
  */
-static void drop_capabilities(private_daemon_t *this, bool full)
+static void drop_capabilities(private_daemon_t *this)
 {
 	struct __user_cap_header_struct hdr;
 	struct __user_cap_data_struct data;
 	
-	/* CAP_NET_ADMIN is needed to use netlink,
-	 * CAP_AUDIT_WRITE for PAM authentication in EAP-GTC */
-	u_int32_t keep = (1<<CAP_NET_ADMIN) | (1<<CAP_SYS_NICE) |
-					 (1<<CAP_AUDIT_WRITE);
-	
-	if (full)
+	prctl(PR_SET_KEEPCAPS, 1);
+
+	if (setgid(charon->gid) != 0)
 	{
-		if (setgid(charon->gid) != 0)
-		{
-			kill_daemon(this, "change to unprivileged group failed");	
-		}
-		if (setuid(charon->uid) != 0)
-		{
-			kill_daemon(this, "change to unprivileged user failed");	
-		}
+		kill_daemon(this, "change to unprivileged group failed");	
 	}
-	else
+	if (setuid(charon->uid) != 0)
 	{
-		/* CAP_NET_BIND_SERVICE to bind services below port 1024 */
-		keep |= (1<<CAP_NET_BIND_SERVICE);
-		/* CAP_NET_RAW to create RAW sockets */
-		keep |= (1<<CAP_NET_RAW);
-		/* CAP_DAC_READ_SEARCH to read ipsec.secrets */
-		keep |= (1<<CAP_DAC_READ_SEARCH);
-		/* CAP_CHOWN to change file permissions (socket permissions) */
-		keep |= (1<<CAP_CHOWN);
-		/* CAP_SETUID to call setuid()  */
-		keep |= (1<<CAP_SETUID);
-		/* CAP_SETGID to call setgid() */
-		keep |= (1<<CAP_SETGID);
+		kill_daemon(this, "change to unprivileged user failed");	
 	}
 
 	/* we use the old capset version for now. For systems with version 2
@@ -292,7 +276,7 @@ static void drop_capabilities(private_daemon_t *this, bool full)
 	hdr.version = _LINUX_CAPABILITY_VERSION;
 #endif
 	hdr.pid = 0;
-	data.inheritable = data.effective = data.permitted = keep;
+	data.inheritable = data.effective = data.permitted = this->keep;
 	
 	if (capset(&hdr, &data))
 	{
@@ -300,6 +284,14 @@ static void drop_capabilities(private_daemon_t *this, bool full)
 	}
 }
 
+/**
+ * Implementation of daemon_t.keep_cap
+ */
+static void keep_cap(private_daemon_t *this, u_int cap)
+{
+	this->keep |= 1 << cap;
+}
+
 /**
  * lookup UID and GID 
  */
@@ -479,6 +471,7 @@ private_daemon_t *daemon_create(void)
 		
 	/* assign methods */
 	this->public.kill = (void (*) (daemon_t*,char*))kill_daemon;
+	this->public.keep_cap = (void(*)(daemon_t*, u_int cap))keep_cap;
 	
 	/* NULL members for clean destruction */
 	this->public.socket = NULL;
@@ -505,6 +498,11 @@ private_daemon_t *daemon_create(void)
 	this->public.gid = 0;
 	
 	this->main_thread_id = pthread_self();
+	this->keep = 1<<CAP_NET_ADMIN;
+	if (lib->leak_detective)
+	{
+		this->keep = 1<<CAP_SYS_NICE;
+	}
 	
 	/* add handler for SEGV and ILL,
 	 * add handler for USR1 (cancellation).
@@ -574,10 +572,6 @@ int main(int argc, char *argv[])
 	
 	lookup_uid_gid(private_charon);
 	
-	/* drop the capabilities we won't need for initialization */
-	prctl(PR_SET_KEEPCAPS, 1);
-	drop_capabilities(private_charon, FALSE);
-	
 	/* use CTRL loglevel for default */
 	for (signal = 0; signal < DBG_MAX; signal++)
 	{
@@ -653,8 +647,8 @@ int main(int argc, char *argv[])
 		fclose(pid_file);
 	}
 	
-	/* drop additional capabilites (bind & root) */
-	drop_capabilities(private_charon, TRUE);
+	/* drop the capabilities we won't need */
+	drop_capabilities(private_charon);
 	
 	/* start the engine, go multithreaded */
 	charon->processor->set_threads(charon->processor,

src/charon/daemon.h

@@ -302,6 +302,15 @@ struct daemon_t {
 	 */
 	gid_t gid;
 	
+	/**
+	 * Do not drop a given capability after initialization.
+	 *
+	 * Some plugins might need additional capabilites. They tell the daemon
+	 * during plugin initialization which one they need, the daemon won't
+	 * drop these.
+	 */
+	void (*keep_cap)(daemon_t *this, u_int cap);
+	
 	/**
 	 * Shut down the daemon.
 	 * 

src/charon/plugins/eap_gtc/eap_gtc_plugin.c

@@ -21,6 +21,8 @@
 
 #include <daemon.h>
 
+#include <linux/capability.h>
+
 /**
  * Implementation of plugin_t.destroy
  */
@@ -42,6 +44,9 @@ plugin_t *plugin_create()
 	
 	this->plugin.destroy = (void(*)(plugin_t*))destroy;
 	
+	/* required for PAM authentication */
+	charon->keep_cap(charon, CAP_AUDIT_WRITE);
+	
 	charon->eap->add_method(charon->eap, EAP_GTC, 0, EAP_SERVER,
 							(eap_constructor_t)eap_gtc_create_server);
 	charon->eap->add_method(charon->eap, EAP_GTC, 0, EAP_PEER,

src/libstrongswan/library.c

@@ -86,6 +86,8 @@ void library_init(char *settings)
 	private_library_t *this = malloc_thing(private_library_t);
 	lib = &this->public;
 	
+	lib->leak_detective = FALSE;
+	
 #ifdef LEAK_DETECTIVE
 	this->detective = leak_detective_create();
 #endif /* LEAK_DETECTIVE */

src/libstrongswan/library.h

@@ -108,6 +108,11 @@ struct library_t {
 	 * various settings loaded from settings file
 	 */
 	settings_t *settings;
+	
+	/**
+	 * is leak detective running?
+	 */
+	bool leak_detective;
 };
 
 /**

src/libstrongswan/utils/leak_detective.c

@@ -560,6 +560,7 @@ leak_detective_t *leak_detective_create()
 	
 	if (getenv("LEAK_DETECTIVE_DISABLE") == NULL)
 	{
+		lib->leak_detective = TRUE;
 		install_hooks();
 	}
 	return &this->public;