Merge branch 'check-caps'

Plugins may now ensure the process has all the required capabilities.
Some minor changes to UID/GID handling are also included.

man/strongswan.conf.5.in

@@ -174,6 +174,9 @@ used certificates.
 Maximum size (in bytes) of a sent fragment when using the proprietary IKEv1
 fragmentation extension.
 .TP
+.BR charon.group
+Name of the group the daemon changes to after startup
+.TP
 .BR charon.half_open_timeout " [30]"
 Timeout in seconds for connecting IKE_SAs (also see IKE_SA_INIT DROPPING).
 .TP
@@ -317,6 +320,9 @@ Section to define syslog loggers, see LOGGER CONFIGURATION
 .TP
 .BR charon.threads " [16]"
 Number of worker threads in charon
+.TP
+.BR charon.user
+Name of the user the daemon changes to after startup
 .SS charon.plugins subsection
 .TP
 .BR charon.plugins.android_log.loglevel " [1]"

src/charon-cmd/charon-cmd.c

@@ -169,13 +169,13 @@ static int run()
 static bool lookup_uid_gid()
 {
 #ifdef IPSEC_USER
-	if (!charon->caps->resolve_uid(charon->caps, IPSEC_USER))
+	if (!lib->caps->resolve_uid(lib->caps, IPSEC_USER))
 	{
 		return FALSE;
 	}
 #endif
 #ifdef IPSEC_GROUP
-	if (!charon->caps->resolve_gid(charon->caps, IPSEC_GROUP))
+	if (!lib->caps->resolve_gid(lib->caps, IPSEC_GROUP))
 	{
 		return FALSE;
 	}
@@ -360,7 +360,7 @@ int main(int argc, char *argv[])
 	{
 		exit(SS_RC_INITIALIZATION_FAILED);
 	}
-	if (!charon->caps->drop(charon->caps))
+	if (!lib->caps->drop(lib->caps))
 	{
 		exit(SS_RC_INITIALIZATION_FAILED);
 	}

src/charon-nm/charon-nm.c

@@ -28,6 +28,17 @@
 
 #include <nm/nm_backend.h>
 
+/**
+ * Default user and group
+ */
+#ifndef IPSEC_USER
+#define IPSEC_USER NULL
+#endif
+
+#ifndef IPSEC_GROUP
+#define IPSEC_GROUP NULL
+#endif
+
 /**
  * Hook in library for debugging messages
  */
@@ -121,18 +132,20 @@ static void segv_handler(int signal)
  */
 static bool lookup_uid_gid()
 {
-#ifdef IPSEC_USER
-	if (!charon->caps->resolve_uid(charon->caps, IPSEC_USER))
+	char *name;
+
+	name = lib->settings->get_str(lib->settings, "charon-nm.user",
+								  IPSEC_USER);
+	if (name && !lib->caps->resolve_uid(lib->caps, name))
 	{
 		return FALSE;
 	}
-#endif
-#ifdef IPSEC_GROUP
-	if (!charon->caps->resolve_gid(charon->caps, IPSEC_GROUP))
+	name = lib->settings->get_str(lib->settings, "charon-nm.group",
+								  IPSEC_GROUP);
+	if (name && !lib->caps->resolve_gid(lib->caps, name))
 	{
 		return FALSE;
 	}
-#endif
 	return TRUE;
 }
 
@@ -214,7 +227,7 @@ int main(int argc, char *argv[])
 	}
 	lib->plugins->status(lib->plugins, LEVEL_CTRL);
 
-	if (!charon->caps->drop(charon->caps))
+	if (!lib->caps->drop(lib->caps))
 	{
 		DBG1(DBG_DMN, "capability dropping failed - aborting charon-nm");
 		goto deinit;

src/charon-nm/nm/nm_backend.c

@@ -142,7 +142,12 @@ static bool nm_backend_init()
 	}
 
 	/* bypass file permissions to read from users ssh-agent */
-	charon->caps->keep(charon->caps, CAP_DAC_OVERRIDE);
+	if (!lib->caps->keep(lib->caps, CAP_DAC_OVERRIDE))
+	{
+		DBG1(DBG_CFG, "NM backend requires CAP_DAC_OVERRIDE capability");
+		nm_backend_deinit();
+		return FALSE;
+	}
 
 	lib->processor->queue_job(lib->processor,
 		(job_t*)callback_job_create_with_prio((callback_job_cb_t)run, this,

src/charon-tkm/src/charon-tkm.c

@@ -151,13 +151,13 @@ static void segv_handler(int signal)
 static bool lookup_uid_gid()
 {
 #ifdef IPSEC_USER
-	if (!charon->caps->resolve_uid(charon->caps, IPSEC_USER))
+	if (!lib->caps->resolve_uid(lib->caps, IPSEC_USER))
 	{
 		return FALSE;
 	}
 #endif
 #ifdef IPSEC_GROUP
-	if (!charon->caps->resolve_gid(charon->caps, IPSEC_GROUP))
+	if (!lib->caps->resolve_gid(lib->caps, IPSEC_GROUP))
 	{
 		return FALSE;
 	}
@@ -201,8 +201,8 @@ static bool check_pidfile()
 	if (pidfile)
 	{
 		ignore_result(fchown(fileno(pidfile),
-							 charon->caps->get_uid(charon->caps),
-							 charon->caps->get_gid(charon->caps)));
+							 lib->caps->get_uid(lib->caps),
+							 lib->caps->get_gid(lib->caps)));
 		fprintf(pidfile, "%d\n", getpid());
 		fflush(pidfile);
 	}
@@ -327,7 +327,7 @@ int main(int argc, char *argv[])
 		goto deinit;
 	}
 
-	if (!charon->caps->drop(charon->caps))
+	if (!lib->caps->drop(lib->caps))
 	{
 		DBG1(DBG_DMN, "capability dropping failed - aborting %s", dmn_name);
 		goto deinit;

src/charon/charon.c

@@ -43,6 +43,17 @@
  */
 #define PID_FILE IPSEC_PIDDIR "/charon.pid"
 
+/**
+ * Default user and group
+ */
+#ifndef IPSEC_USER
+#define IPSEC_USER NULL
+#endif
+
+#ifndef IPSEC_GROUP
+#define IPSEC_GROUP NULL
+#endif
+
 /**
  * Global reference to PID file (required to truncate, if undeletable)
  */
@@ -148,20 +159,20 @@ static void run()
  */
 static bool lookup_uid_gid()
 {
-#ifdef IPSEC_USER
-	if (!charon->caps->resolve_uid(charon->caps, IPSEC_USER))
+	char *name;
+
+	name = lib->settings->get_str(lib->settings, "charon.user", IPSEC_USER);
+	if (name && !lib->caps->resolve_uid(lib->caps, name))
 	{
 		return FALSE;
 	}
-#endif
-#ifdef IPSEC_GROUP
-	if (!charon->caps->resolve_gid(charon->caps, IPSEC_GROUP))
+	name = lib->settings->get_str(lib->settings, "charon.group", IPSEC_GROUP);
+	if (name && !lib->caps->resolve_gid(lib->caps, name))
 	{
 		return FALSE;
 	}
-#endif
 #ifdef ANDROID
-	charon->caps->set_uid(charon->caps, AID_VPN);
+	lib->caps->set_uid(lib->caps, AID_VPN);
 #endif
 	return TRUE;
 }
@@ -219,8 +230,8 @@ static bool check_pidfile()
 	if (pidfile)
 	{
 		ignore_result(fchown(fileno(pidfile),
-							 charon->caps->get_uid(charon->caps),
-							 charon->caps->get_gid(charon->caps)));
+							 lib->caps->get_uid(lib->caps),
+							 lib->caps->get_gid(lib->caps)));
 		fprintf(pidfile, "%d\n", getpid());
 		fflush(pidfile);
 	}
@@ -406,7 +417,7 @@ int main(int argc, char *argv[])
 		goto deinit;
 	}
 
-	if (!charon->caps->drop(charon->caps))
+	if (!lib->caps->drop(lib->caps))
 	{
 		DBG1(DBG_DMN, "capability dropping failed - aborting charon");
 		goto deinit;

src/libcharon/daemon.c

@@ -33,10 +33,6 @@
 #include <processing/jobs/start_action_job.h>
 #include <threading/mutex.h>
 
-#ifndef CAP_NET_ADMIN
-#define CAP_NET_ADMIN 12
-#endif
-
 #ifndef LOG_AUTHPRIV /* not defined on OpenSolaris */
 #define LOG_AUTHPRIV LOG_AUTH
 #endif
@@ -471,7 +467,6 @@ static void destroy(private_daemon_t *this)
 	DESTROY_IF(this->public.xauth);
 	DESTROY_IF(this->public.backends);
 	DESTROY_IF(this->public.socket);
-	DESTROY_IF(this->public.caps);
 
 	/* rehook library logging, shutdown logging */
 	dbg = dbg_old;
@@ -581,7 +576,6 @@ private_daemon_t *daemon_create(const char *name)
 		.ref = 1,
 	);
 	charon = &this->public;
-	this->public.caps = capabilities_create();
 	this->public.controller = controller_create();
 	this->public.eap = eap_manager_create();
 	this->public.xauth = xauth_manager_create();
@@ -591,8 +585,6 @@ private_daemon_t *daemon_create(const char *name)
 	this->public.shunts = shunt_manager_create();
 	this->kernel_handler = kernel_handler_create();
 
-	this->public.caps->keep(this->public.caps, CAP_NET_ADMIN);
-
 	return this;
 }
 

src/libcharon/daemon.h

@@ -163,7 +163,6 @@ typedef struct daemon_t daemon_t;
 #include <config/backend_manager.h>
 #include <sa/eap/eap_manager.h>
 #include <sa/xauth/xauth_manager.h>
-#include <utils/capabilities.h>
 
 #ifdef ME
 #include <sa/ikev2/connect_manager.h>
@@ -272,11 +271,6 @@ struct daemon_t {
 	mediation_manager_t *mediation_manager;
 #endif /* ME */
 
-	/**
-	 * POSIX capability dropping
-	 */
-	capabilities_t *caps;
-
 	/**
 	 * Name of the binary that uses the library (used for settings etc.)
 	 */

src/libcharon/plugins/dhcp/dhcp_plugin.c

@@ -107,6 +107,17 @@ plugin_t *dhcp_plugin_create()
 {
 	private_dhcp_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_NET_BIND_SERVICE))
+	{	/* required to bind DHCP socket (port 68) */
+		DBG1(DBG_NET, "dhcp plugin requires CAP_NET_BIND_SERVICE capability");
+		return NULL;
+	}
+	else if (!lib->caps->keep(lib->caps, CAP_NET_RAW))
+	{	/* required to open DHCP receive socket (AF_PACKET) */
+		DBG1(DBG_NET, "dhcp plugin requires CAP_NET_RAW capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/duplicheck/duplicheck_notify.c

@@ -84,8 +84,8 @@ static bool open_socket(private_duplicheck_notify_t *this)
 		return FALSE;
 	}
 	umask(old);
-	if (chown(addr.sun_path, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(addr.sun_path, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing duplicheck socket permissions failed: %s",
 			 strerror(errno));

src/libcharon/plugins/duplicheck/duplicheck_plugin.c

@@ -98,6 +98,12 @@ plugin_t *duplicheck_plugin_create()
 		return NULL;
 	}
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) notify socket */
+		DBG1(DBG_CFG, "duplicheck plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/error_notify/error_notify_plugin.c

@@ -92,6 +92,12 @@ plugin_t *error_notify_plugin_create()
 {
 	private_error_notify_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) notify socket */
+		DBG1(DBG_CFG, "error-notify plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/error_notify/error_notify_socket.c

@@ -84,8 +84,8 @@ static bool open_socket(private_error_notify_socket_t *this)
 		return FALSE;
 	}
 	umask(old);
-	if (chown(addr.sun_path, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(addr.sun_path, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing notify socket permissions failed: %s",
 			 strerror(errno));

src/libcharon/plugins/farp/farp_plugin.c

@@ -92,6 +92,12 @@ plugin_t *farp_plugin_create()
 {
 	private_farp_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_NET_RAW))
+	{	/* required to open ARP socket (AF_PACKET) */
+		DBG1(DBG_NET, "farp plugin requires CAP_NET_RAW capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/ha/ha_ctl.c

@@ -129,8 +129,8 @@ ha_ctl_t *ha_ctl_create(ha_segments_t *segments, ha_cache_t *cache)
 		}
 		umask(old);
 	}
-	if (chown(HA_FIFO, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(HA_FIFO, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing HA FIFO permissions failed: %s",
 			 strerror(errno));

src/libcharon/plugins/ha/ha_kernel.c

@@ -316,8 +316,8 @@ static void disable_all(private_ha_kernel_t *this)
 	{
 		while (enumerator->enumerate(enumerator, NULL, &file, NULL))
 		{
-			if (chown(file, charon->caps->get_uid(charon->caps),
-					  charon->caps->get_gid(charon->caps)) != 0)
+			if (chown(file, lib->caps->get_uid(lib->caps),
+					  lib->caps->get_gid(lib->caps)) != 0)
 			{
 				DBG1(DBG_CFG, "changing ClusterIP permissions failed: %s",
 					 strerror(errno));

src/libcharon/plugins/ha/ha_plugin.c

@@ -179,6 +179,12 @@ plugin_t *ha_plugin_create()
 		return NULL;
 	}
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "ha plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/kernel_libipsec/kernel_libipsec_plugin.c

@@ -102,6 +102,13 @@ plugin_t *kernel_libipsec_plugin_create()
 {
 	private_kernel_libipsec_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_NET_ADMIN))
+	{	/* required to create TUN devices */
+		DBG1(DBG_KNL, "kernel-libipsec plugin requires CAP_NET_ADMIN "
+			 "capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/load_tester/load_tester_control.c

@@ -110,8 +110,8 @@ static bool open_socket(private_load_tester_control_t *this)
 		return FALSE;
 	}
 	umask(old);
-	if (chown(addr.sun_path, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(addr.sun_path, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing load-tester socket permissions failed: %s",
 			 strerror(errno));

src/libcharon/plugins/load_tester/load_tester_plugin.c

@@ -269,6 +269,12 @@ plugin_t *load_tester_plugin_create()
 		return NULL;
 	}
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "load-tester plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/lookip/lookip_plugin.c

@@ -92,6 +92,12 @@ plugin_t *lookip_plugin_create()
 {
 	private_lookip_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "lookip plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/lookip/lookip_socket.c

@@ -94,8 +94,8 @@ static bool open_socket(private_lookip_socket_t *this)
 		return FALSE;
 	}
 	umask(old);
-	if (chown(addr.sun_path, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(addr.sun_path, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing lookip socket permissions failed: %s",
 			 strerror(errno));

src/libcharon/plugins/smp/smp.c

@@ -739,6 +739,12 @@ plugin_t *smp_plugin_create()
 	private_smp_t *this;
 	mode_t old;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "smp plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {
@@ -768,8 +774,8 @@ plugin_t *smp_plugin_create()
 		return NULL;
 	}
 	umask(old);
-	if (chown(unix_addr.sun_path, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(unix_addr.sun_path, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing XML socket permissions failed: %s", strerror(errno));
 	}

src/libcharon/plugins/socket_default/socket_default_socket.c

@@ -692,6 +692,18 @@ socket_default_socket_t *socket_default_socket_create()
 		this->natt = 0;
 	}
 
+	if ((this->port && this->port < 1024) || (this->natt && this->natt < 1024))
+	{
+		if (!lib->caps->keep(lib->caps, CAP_NET_BIND_SERVICE))
+		{
+			/* required to bind ports < 1024 */
+			DBG1(DBG_NET, "socket-default plugin requires CAP_NET_BIND_SERVICE "
+				 "capability");
+			destroy(this);
+			return NULL;
+		}
+	}
+
 	/* we allocate IPv6 sockets first as that will reserve randomly allocated
 	 * ports also for IPv4. On OS X, we have to do it the other way round
 	 * for the same effect. */

src/libcharon/plugins/stroke/stroke_plugin.c

@@ -91,6 +91,12 @@ plugin_t *stroke_plugin_create()
 {
 	private_stroke_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) stroke socket */
+		DBG1(DBG_CFG, "stroke plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/stroke/stroke_socket.c

@@ -847,8 +847,8 @@ static bool open_socket(private_stroke_socket_t *this)
 		return FALSE;
 	}
 	umask(old);
-	if (chown(socket_addr.sun_path, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(socket_addr.sun_path, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing stroke socket permissions failed: %s",
 			 strerror(errno));

src/libcharon/plugins/whitelist/whitelist_control.c

@@ -77,8 +77,8 @@ static bool open_socket(private_whitelist_control_t *this)
 		return FALSE;
 	}
 	umask(old);
-	if (chown(addr.sun_path, charon->caps->get_uid(charon->caps),
-			  charon->caps->get_gid(charon->caps)) != 0)
+	if (chown(addr.sun_path, lib->caps->get_uid(lib->caps),
+			  lib->caps->get_gid(lib->caps)) != 0)
 	{
 		DBG1(DBG_CFG, "changing whitelist socket permissions failed: %s",
 			 strerror(errno));

src/libcharon/plugins/whitelist/whitelist_plugin.c

@@ -92,6 +92,12 @@ plugin_t *whitelist_plugin_create()
 {
 	private_whitelist_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_CHOWN))
+	{	/* required to chown(2) control socket */
+		DBG1(DBG_CFG, "whitelist plugin requires CAP_CHOWN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libcharon/plugins/xauth_pam/xauth_pam_plugin.c

@@ -52,6 +52,13 @@ plugin_t *xauth_pam_plugin_create()
 {
 	xauth_pam_plugin_t *this;
 
+	/* required for PAM authentication */
+	if (!lib->caps->keep(lib->caps, CAP_AUDIT_WRITE))
+	{
+		DBG1(DBG_DMN, "xauth-pam plugin requires CAP_AUDIT_WRITE capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.plugin = {
 			.get_name = _get_name,
@@ -60,8 +67,5 @@ plugin_t *xauth_pam_plugin_create()
 		},
 	);
 
-	/* required for PAM authentication */
-	charon->caps->keep(charon->caps, CAP_AUDIT_WRITE);
-
 	return &this->plugin;
 }

src/libhydra/hydra.c

@@ -97,4 +97,3 @@ bool libhydra_init(const char *daemon)
 	}
 	return !this->integrity_failed;
 }
-

src/libhydra/plugins/kernel_netlink/kernel_netlink_plugin.c

@@ -65,6 +65,14 @@ plugin_t *kernel_netlink_plugin_create()
 {
 	private_kernel_netlink_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_NET_ADMIN))
+	{	/* required to bind/use XFRM sockets / create/modify routing tables, but
+		 * not if only the read-only parts of kernel-netlink-net are used, so
+		 * we don't fail here */
+		DBG1(DBG_KNL, "kernel-netlink plugin might require CAP_NET_ADMIN "
+			 "capability");
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libhydra/plugins/kernel_pfkey/kernel_pfkey_plugin.c

@@ -62,6 +62,12 @@ plugin_t *kernel_pfkey_plugin_create()
 {
 	private_kernel_pfkey_plugin_t *this;
 
+	if (!lib->caps->keep(lib->caps, CAP_NET_ADMIN))
+	{	/* required to open PF_KEY sockets */
+		DBG1(DBG_KNL, "kernel-pfkey plugin requires CAP_NET_ADMIN capability");
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.plugin = {

src/libstrongswan/library.c

@@ -89,6 +89,7 @@ void library_deinit()
 	this->public.creds->destroy(this->public.creds);
 	this->public.encoding->destroy(this->public.encoding);
 	this->public.crypto->destroy(this->public.crypto);
+	this->public.caps->destroy(this->public.caps);
 	this->public.proposal->destroy(this->public.proposal);
 	this->public.fetcher->destroy(this->public.fetcher);
 	this->public.resolver->destroy(this->public.resolver);
@@ -255,6 +256,7 @@ bool library_init(char *settings)
 	this->public.settings = settings_create(settings);
 	this->public.hosts = host_resolver_create();
 	this->public.proposal = proposal_keywords_create();
+	this->public.caps = capabilities_create();
 	this->public.crypto = crypto_factory_create();
 	this->public.creds = credential_factory_create();
 	this->public.credmgr = credential_manager_create();

src/libstrongswan/library.h

@@ -101,6 +101,7 @@
 #include "credentials/credential_manager.h"
 #include "credentials/cred_encoding.h"
 #include "utils/chunk.h"
+#include "utils/capabilities.h"
 #include "utils/integrity_checker.h"
 #include "utils/leak_detective.h"
 #include "utils/settings.h"
@@ -140,6 +141,11 @@ struct library_t {
 	 */
 	proposal_keywords_t *proposal;
 
+	/**
+	 * POSIX capability dropping
+	 */
+	capabilities_t *caps;
+
 	/**
 	 * crypto algorithm registry and factory
 	 */

src/libstrongswan/utils/capabilities.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012-2013 Tobias Brunner
  * Hochschule fuer Technik Rapperswil
  * Copyright (C) 2012 Martin Willi
  * Copyright (C) 2012 revosec AG
@@ -76,9 +76,63 @@ struct private_capabilities_t {
 #endif
 };
 
-METHOD(capabilities_t, keep, void,
-	private_capabilities_t *this, u_int cap)
+/**
+ * Verify that the current process has the given capability
+ */
+static bool has_capability(u_int cap)
 {
+#ifndef CAPABILITIES
+	/* if we can't check the actual capabilities assume only root has it */
+	return geteuid() == 0;
+#endif /* !CAPABILITIES */
+#ifdef CAPABILITIES_LIBCAP
+	cap_flag_value_t val;
+	cap_t caps;
+	bool ok;
+
+	caps = cap_get_proc();
+	if (!caps)
+	{
+		return FALSE;
+	}
+	ok = cap_get_flag(caps, cap, CAP_PERMITTED, &val) == 0 && val == CAP_SET;
+	cap_free(caps);
+	return ok;
+#endif /* CAPABILITIES_LIBCAP */
+#ifdef CAPABILITIES_NATIVE
+	struct __user_cap_header_struct header = {
+#if defined(_LINUX_CAPABILITY_VERSION_3)
+		.version = _LINUX_CAPABILITY_VERSION_3,
+#elif defined(_LINUX_CAPABILITY_VERSION_2)
+		.version = _LINUX_CAPABILITY_VERSION_2,
+#elif defined(_LINUX_CAPABILITY_VERSION_1)
+		.version = _LINUX_CAPABILITY_VERSION_1,
+#else
+		.version = _LINUX_CAPABILITY_VERSION,
+#endif
+	};
+	struct __user_cap_data_struct caps[2];
+	int i = 0;
+
+	if (cap >= 32)
+	{
+		i++;
+		cap -= 32;
+	}
+	return capget(&header, caps) == 0 && caps[i].permitted & (1 << cap);
+#endif /* CAPABILITIES_NATIVE */
+}
+
+/**
+ * Keep the given capability if it is held by the current process.  Returns
+ * FALSE, if this is not the case.
+ */
+static bool keep_capability(private_capabilities_t *this, u_int cap)
+{
+	if (!has_capability(cap))
+	{
+		return FALSE;
+	}
 #ifdef CAPABILITIES_LIBCAP
 	cap_set_flag(this->caps, CAP_EFFECTIVE, 1, &cap, CAP_SET);
 	cap_set_flag(this->caps, CAP_INHERITABLE, 1, &cap, CAP_SET);
@@ -96,18 +150,71 @@ METHOD(capabilities_t, keep, void,
 	this->caps[i].permitted |= 1 << cap;
 	this->caps[i].inheritable |= 1 << cap;
 #endif /* CAPABILITIES_NATIVE */
+	return TRUE;
+}
+
+/**
+ * Returns TRUE if the current process/user is member of the given group
+ */
+static bool has_group(gid_t group)
+{
+	gid_t *groups;
+	long ngroups, i;
+	bool found = FALSE;
+
+	if (group == getegid())
+	{	/* it's unspecified if this is part of the list below or not */
+		return TRUE;
+	}
+	ngroups = sysconf(_SC_NGROUPS_MAX);
+	groups = calloc(ngroups, sizeof(gid_t));
+	ngroups = getgroups(ngroups, groups);
+	if (ngroups == -1)
+	{
+		DBG1(DBG_LIB, "getting groups for current process failed: %s",
+			 strerror(errno));
+		return FALSE;
+	}
+	for (i = 0; i < ngroups; i++)
+	{
+		if (group == groups[i])
+		{
+			found = TRUE;
+			break;
+		}
+	}
+	free(groups);
+	return found;
+}
+
+METHOD(capabilities_t, keep, bool,
+	private_capabilities_t *this, u_int cap)
+{
+	if (cap == CAP_CHOWN)
+	{	/* if new files/UNIX sockets are created they should be owned by the
+		 * configured user and group.  This requires a call to chown(2).  But
+		 * CAP_CHOWN is not always required. */
+		if (!this->uid || geteuid() == this->uid)
+		{	/* if the owner does not change CAP_CHOWN is not needed */
+			if (!this->gid || has_group(this->gid))
+			{	/* the same applies if the owner is a member of the group */
+				return TRUE;
+			}
+		}
+	}
+	return keep_capability(this, cap);
 }
 
 METHOD(capabilities_t, get_uid, uid_t,
 	private_capabilities_t *this)
 {
-	return this->uid;
+	return this->uid ?: geteuid();
 }
 
 METHOD(capabilities_t, get_gid, gid_t,
 	private_capabilities_t *this)
 {
-	return this->gid;
+	return this->gid ?: getegid();
 }
 
 METHOD(capabilities_t, set_uid, void,
@@ -271,7 +378,7 @@ METHOD(capabilities_t, drop, bool,
 #endif /* CAPABILITIES_NATIVE */
 #ifdef CAPABILITIES
 	DBG1(DBG_LIB, "dropped capabilities, running as uid %u, gid %u",
-		 this->uid, this->gid);
+		 geteuid(), getegid());
 #endif /* CAPABILITIES */
 	return TRUE;
 }

src/libstrongswan/utils/capabilities.h

@@ -1,4 +1,6 @@
 /*
+ * Copyright (C) 2013 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
  * Copyright (C) 2012 Martin Willi
  * Copyright (C) 2012 revosec AG
  *
@@ -21,6 +23,8 @@
 #ifndef CAPABILITIES_H_
 #define CAPABILITIES_H_
 
+typedef struct capabilities_t capabilities_t;
+
 #include <library.h>
 #ifdef HAVE_SYS_CAPABILITY_H
 # include <sys/capability.h>
@@ -28,7 +32,18 @@
 # include <linux/capability.h>
 #endif
 
-typedef struct capabilities_t capabilities_t;
+#ifndef CAP_CHOWN
+# define CAP_CHOWN 0
+#endif
+#ifndef CAP_NET_BIND_SERVICE
+# define CAP_NET_BIND_SERVICE 10
+#endif
+#ifndef CAP_NET_ADMIN
+# define CAP_NET_ADMIN 12
+#endif
+#ifndef CAP_NET_RAW
+# define CAP_NET_RAW 13
+#endif
 
 /**
  * POSIX capability dropping abstraction layer.
@@ -36,11 +51,14 @@ typedef struct capabilities_t capabilities_t;
 struct capabilities_t {
 
 	/**
-	 * Register a capability to keep while calling drop().
+	 * Register a capability to keep while calling drop(). Verifies that the
+	 * capability is currently held.
 	 *
 	 * @param cap		capability to keep
+	 * @return			FALSE if the capability is currently not held
 	 */
-	void (*keep)(capabilities_t *this, u_int cap);
+	bool (*keep)(capabilities_t *this,
+				 u_int cap) __attribute__((warn_unused_result));
 
 	/**
 	 * Get the user ID set through set_uid/resolve_uid.