use libcap for capability dropping

optional, must be enabled --with-capabilities=libcap will be extended to support --with-capabilities=libcap2
2008-08-29 09:24:14 +00:00 · 2008-08-29 09:24:14 +00:00 · eb3e27059b
parent 8fa6f2dc66
commit eb3e27059b
7 changed files with 71 additions and 60 deletions
--- a/configure.in
+++ b/configure.in
@ -138,6 +138,14 @@ AC_ARG_WITH(
 	[AC_SUBST(ipsecgroup, "root")]
 )

+dnl Will be extended to --with-capabilities=libcap|libcap2
+AC_ARG_WITH(
+	[capabilities],
+	AS_HELP_STRING([--with-capabilities=libcap],[capability dropping using libcap. Currenlty only the value "libcap" is supported (default is NO).]),
+	[capabilities="$withval"],
+	[capabilities=no]
+)
+
 AC_ARG_ENABLE(
 	[curl],
 	AS_HELP_STRING([--enable-curl],[enable CURL fetcher plugin to fetch files via libcurl (default is NO). Requires libcurl.]),
@ -628,15 +636,6 @@ AC_HAVE_LIBRARY(dl)
 AC_CHECK_FUNCS(backtrace)
 AC_CHECK_FUNCS(dladdr)

-AC_MSG_CHECKING([capset() definition])
-AC_TRY_COMPILE(
-	[#include <linux/capset.h>],
-	[
-		void *test = capset;
-	], 
-	[AC_MSG_RESULT([yes])], [AC_MSG_RESULT([no]); AC_DEFINE_UNQUOTED(NO_CAPSET_DEFINED, 1)]
-)
-
 if test x$gmp = xtrue; then
 	AC_HAVE_LIBRARY([gmp],[LIBS="$LIBS"],[AC_MSG_ERROR([GNU Multi Precision library gmp not found])])
 	AC_MSG_CHECKING([gmp.h version >= 4.1.4])
@ -732,6 +731,11 @@ if test x$eap_gtc = xtrue; then
 	AC_CHECK_HEADER([security/pam_appl.h],,[AC_MSG_ERROR([PAM header security/pam_appl.h not found!])])
 fi

+if test x$capabilities = xlibcap; then
+	AC_HAVE_LIBRARY([cap],[LIBS="$LIBS"],[AC_MSG_ERROR([libcap library not found])])
+	AC_CHECK_HEADER([sys/capability.h],,[AC_MSG_ERROR([libcap header sys/capability.h not found!])])
+fi
+
 dnl ======================================
 dnl  collect all plugins for libstrongswan
 dnl ======================================
@ -850,6 +854,7 @@ AM_CONDITIONAL(USE_MANAGER, test x$manager = xtrue)
 AM_CONDITIONAL(USE_ME, test x$me = xtrue)
 AM_CONDITIONAL(USE_INTEGRITY_TEST, test x$integrity_test = xtrue)
 AM_CONDITIONAL(USE_SELF_TEST, test x$self_test = xtrue)
+AM_CONDITIONAL(USE_CAPABILITIES, test x$capabilities = xlibcap)
 AM_CONDITIONAL(USE_PLUTO, test x$pluto = xtrue)
 AM_CONDITIONAL(USE_CHARON, test x$charon = xtrue)
 AM_CONDITIONAL(USE_TOOLS, test x$tools = xtrue)
@ -864,6 +869,9 @@ dnl ==============================
 if test x$me = xtrue; then
 	AC_DEFINE(ME)
 fi
+if test x$capabilities = xlibcap; then
+	AC_DEFINE(CAPABILITIES)
+fi

 dnl ==============================
 dnl  build Makefiles
--- a/scripts/cfg-leak
+++ b/scripts/cfg-leak
@ -1,4 +1,4 @@
 #!/bin/bash
 CFLAGS="-Wall -Wno-format -Wno-pointer-sign -Wno-strict-aliasing -g -O2" ./configure \
--sysconfdir=/etc --disable-tools --disable-pluto --enable-leak-detective --enable-dumm \
+--sysconfdir=/etc --disable-tools --disable-pluto --enable-leak-detective --enable-dumm --with-capabilities=libcap \
 $1 $2 $3 $4 $5
--- a/src/charon/Makefile.am
+++ b/src/charon/Makefile.am
@ -129,6 +129,11 @@ if USE_SELF_TEST
  AM_CFLAGS += -DSELF_TEST
 endif

+if USE_CAPABILITIES
+  charon_LDADD += -lcap
+endif
+
+
 # build optional plugins
 ########################

--- a/src/charon/daemon.c
+++ b/src/charon/daemon.c
@ -22,7 +22,6 @@
 #endif /* HAVE_DLADDR */

 #include <stdio.h>
-#include <linux/capability.h>
 #include <sys/prctl.h>
 #include <signal.h>
 #include <pthread.h>
@ -38,6 +37,9 @@
 #ifdef HAVE_BACKTRACE
 # include <execinfo.h>
 #endif /* HAVE_BACKTRACE */
+#ifdef CAPABILITIES
+#include <sys/capability.h>
+#endif /* CAPABILITIES */

 #include "daemon.h"

@ -45,16 +47,6 @@
 #include <config/traffic_selector.h>
 #include <config/proposal.h>

-/* on some distros, a capset definition is missing */
-#ifdef NO_CAPSET_DEFINED
-extern int capset(cap_user_header_t hdrp, const cap_user_data_t datap);
-#endif /* NO_CAPSET_DEFINED */
-
-/* missing on older kernel headers */
-#ifndef CAP_AUDIT_WRITE
-#define CAP_AUDIT_WRITE 29
-#endif /* CAP_AUDIT_WRITE */
-
 #ifdef INTEGRITY_TEST
 #include <fips/fips.h>
 #include <fips/fips_signature.h>
@ -80,11 +72,13 @@ struct private_daemon_t {
 	 * The thread_id of main-thread.
 	 */
 	pthread_t main_thread_id;
-	
+
+#ifdef CAPABILITIES
 	/**
 	 * capabilities to keep
 	 */
-	u_int32_t keep;
+	cap_t caps;
+#endif /* CAPABILITIES */
 };

 /**
@ -193,6 +187,9 @@ static void destroy(private_daemon_t *this)
 	}
 	/* unload plugins to release threads */
 	lib->plugins->unload(lib->plugins);
+#ifdef CAPABILITIES
+	cap_free(this->caps);
+#endif /* CAPABILITIES */
 	DESTROY_IF(this->public.ike_sa_manager);
 	DESTROY_IF(this->public.kernel_interface);
 	DESTROY_IF(this->public.scheduler);
@ -253,10 +250,7 @@ static void kill_daemon(private_daemon_t *this, char *reason)
 * drop daemon capabilities
 */
 static void drop_capabilities(private_daemon_t *this)
-{
-	struct __user_cap_header_struct hdr;
-	struct __user_cap_data_struct data;
-	
+{	
 	prctl(PR_SET_KEEPCAPS, 1);

 	if (setgid(charon->gid) != 0)
@ -267,21 +261,13 @@ static void drop_capabilities(private_daemon_t *this)
 	{
 		kill_daemon(this, "change to unprivileged user failed");	
 	}
-
-	/* we use the old capset version for now. For systems with version 2
-	 * available, we specifiy version 1 excplicitly. */
-#ifdef _LINUX_CAPABILITY_VERSION_1
-	hdr.version = _LINUX_CAPABILITY_VERSION_1;
-#else
-	hdr.version = _LINUX_CAPABILITY_VERSION;
-#endif
-	hdr.pid = 0;
-	data.inheritable = data.effective = data.permitted = this->keep;
 	
-	if (capset(&hdr, &data))
+#ifdef CAPABILITIES
+	if (cap_set_proc(this->caps) != 0)
 	{
 		kill_daemon(this, "unable to drop daemon capabilities");
 	}
+#endif /* CAPABILITIES */
 }

 /**
@ -289,7 +275,11 @@ static void drop_capabilities(private_daemon_t *this)
 */
 static void keep_cap(private_daemon_t *this, u_int cap)
 {
-	this->keep |= 1 << cap;
+#ifdef CAPABILITIES
+	cap_set_flag(this->caps, CAP_EFFECTIVE, 1, &cap, CAP_SET);
+	cap_set_flag(this->caps, CAP_INHERITABLE, 1, &cap, CAP_SET);
+	cap_set_flag(this->caps, CAP_PERMITTED, 1, &cap, CAP_SET);
+#endif /* CAPABILITIES */
 }

 /**
@ -498,11 +488,14 @@ private_daemon_t *daemon_create(void)
 	this->public.gid = 0;
 	
 	this->main_thread_id = pthread_self();
-	this->keep = 1<<CAP_NET_ADMIN;
+#ifdef CAPABILITIES
+	this->caps = cap_init();
+	keep_cap(this, CAP_NET_ADMIN);
 	if (lib->leak_detective)
 	{
-		this->keep = 1<<CAP_SYS_NICE;
+		keep_cap(this, CAP_SYS_NICE);
 	}
+#endif /* CAPABILITIES */
 	
 	/* add handler for SEGV and ILL,
 	 * add handler for USR1 (cancellation).
--- a/src/charon/plugins/eap_gtc/eap_gtc_plugin.c
+++ b/src/charon/plugins/eap_gtc/eap_gtc_plugin.c
@ -21,7 +21,8 @@

 #include <daemon.h>

-#include <linux/capability.h>
+/* missing in cababilities.h */
+#define CAP_AUDIT_WRITE 29

 /**
 * Implementation of plugin_t.destroy
--- a/src/pluto/Makefile.am
+++ b/src/pluto/Makefile.am
@ -139,3 +139,7 @@ if USE_SMARTCARD
  AM_CFLAGS += -DSMARTCARD
 endif

+if USE_CAPABILITIES
+  pluto_LDADD += -lcap
+endif
+
--- a/src/pluto/plutomain.c
+++ b/src/pluto/plutomain.c
@ -29,11 +29,14 @@
 #include <resolv.h>
 #include <arpa/nameser.h>	/* missing from <resolv.h> on old systems */
 #include <sys/queue.h>
-#include <linux/capability.h>
 #include <sys/prctl.h>
 #include <pwd.h>
 #include <grp.h>

+#ifdef CAPABILITIES
+#include <sys/capability.h>
+#endif /* CAPABILITIES */
+
 #include <freeswan.h>

 #include <pfkeyv2.h>
@ -68,11 +71,6 @@
 #include "nat_traversal.h"
 #include "virtual.h"

-/* on some distros, a capset() definition is missing */
-#ifdef NO_CAPSET_DEFINED
-extern int capset(cap_user_header_t hdrp, const cap_user_data_t datap);
-#endif /* NO_CAPSET_DEFINED */
-
 static void
 usage(const char *mess)
 {
@ -236,8 +234,10 @@ main(int argc, char **argv)
    bool force_keepalive = FALSE;
    char *virtual_private = NULL;
    int lockfd;
-    struct __user_cap_header_struct hdr;
-    struct __user_cap_data_struct data;
+#ifdef CAPABILITIES
+    cap_t caps;
+    int keep[] = { CAP_NET_ADMIN, CAP_NET_BIND_SERVICE };
+#endif /* CAPABILITIES */

    /* handle arguments */
    for (;;)
@ -619,14 +619,6 @@ main(int argc, char **argv)
    init_fetch();

    /* drop unneeded capabilities and change UID/GID */
-#ifdef _LINUX_CAPABILITY_VERSION_1
-    hdr.version = _LINUX_CAPABILITY_VERSION_1;
-#else
-    hdr.version = _LINUX_CAPABILITY_VERSION;
-#endif
-    hdr.pid = 0;
-    data.inheritable = data.effective = data.permitted = 
-				1<<CAP_NET_ADMIN | 1<<CAP_NET_BIND_SERVICE;

    prctl(PR_SET_KEEPCAPS, 1);
 	
@ -656,11 +648,19 @@ main(int argc, char **argv)
 	}
 	}
 #endif
-    if (capset(&hdr, &data))
+
+#ifdef CAPABILITIES
+    caps = cap_init();
+    cap_set_flag(caps, CAP_EFFECTIVE, 2, keep, CAP_SET);
+    cap_set_flag(caps, CAP_INHERITABLE, 2, keep, CAP_SET);
+    cap_set_flag(caps, CAP_PERMITTED, 2, keep, CAP_SET);
+    if (cap_set_proc(caps) != 0)
    {
-	plog("unable to drop root privileges");
+	plog("unable to drop daemon capabilities");
 	abort();
    }
+    cap_free(caps);
+#endif /* CAPABILITIES */

    /* loading X.509 CA certificates */
    load_authcerts("CA cert", CA_CERT_PATH, AUTH_CA);