conntrackd: move ctnetlink code to ctnl.c (removed from run.c)

This patch moves the specific ctnetlink code to ctnl.c to prepare
the introduction of the cthelper infrastructure.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 522 insertions, 0 deletions

diff --git a/src/ctnl.c b/src/ctnl.c
new file mode 100644
index 0000000..107cd5d
--- /dev/null
+++ b/src/ctnl.c
@@ -0,0 +1,522 @@
+/*
+ * (C) 2006-2012 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * Part of this code has been sponsored by Vyatta Inc. <http://www.vyatta.com>
+ */
+
+#include "conntrackd.h"
+#include "netlink.h"
+#include "filter.h"
+#include "log.h"
+#include "alarm.h"
+#include "fds.h"
+#include "traffic_stats.h"
+#include "process.h"
+#include "origin.h"
+#include "date.h"
+#include "internal.h"
+
+#include <errno.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <string.h>
+#include <time.h>
+#include <fcntl.h>
+
+void ctnl_kill(void)
+{
+	if (!(CONFIG(flags) & CTD_POLL))
+		nfct_close(STATE(event));
+
+	nfct_close(STATE(resync));
+	nfct_close(STATE(get));
+	origin_unregister(STATE(flush));
+	nfct_close(STATE(flush));
+
+	if (STATE(us_filter))
+		ct_filter_destroy(STATE(us_filter));
+	STATE(mode)->kill();
+
+	if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) {
+		nfct_close(STATE(dump));
+	}
+}
+
+static void local_flush_master(void)
+{
+	STATE(stats).nl_kernel_table_flush++;
+	dlog(LOG_NOTICE, "flushing kernel conntrack table");
+
+	/* fork a child process that performs the flush operation,
+	 * meanwhile the parent process handles events. */
+	if (fork_process_new(CTD_PROC_FLUSH, CTD_PROC_F_EXCL,
+			     NULL, NULL) == 0) {
+		nl_flush_conntrack_table_selective();
+		exit(EXIT_SUCCESS);
+	}
+}
+
+static void local_resync_master(void)
+{
+	if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) {
+		STATE(stats).nl_kernel_table_resync++;
+		dlog(LOG_NOTICE, "resync with master conntrack table");
+		nl_dump_conntrack_table(STATE(dump));
+	} else {
+		dlog(LOG_NOTICE, "resync is unsupported in this mode");
+	}
+}
+
+static void local_exp_flush_master(void)
+{
+	if (!(CONFIG(flags) & CTD_EXPECT))
+		return;
+
+	STATE(stats).nl_kernel_table_flush++;
+	dlog(LOG_NOTICE, "flushing kernel expect table");
+
+	/* fork a child process that performs the flush operation,
+	 * meanwhile the parent process handles events. */
+	if (fork_process_new(CTD_PROC_FLUSH, CTD_PROC_F_EXCL,
+			     NULL, NULL) == 0) {
+		nl_flush_expect_table(STATE(flush));
+		exit(EXIT_SUCCESS);
+	}
+}
+
+static void local_exp_resync_master(void)
+{
+	if (!(CONFIG(flags) & CTD_EXPECT))
+		return;
+
+	if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) {
+		STATE(stats).nl_kernel_table_resync++;
+		dlog(LOG_NOTICE, "resync with master expect table");
+		nl_dump_expect_table(STATE(dump));
+	} else {
+		dlog(LOG_NOTICE, "resync is unsupported in this mode");
+	}
+}
+
+int ctnl_local(int fd, int type, void *data)
+{
+	int ret = LOCAL_RET_OK;
+
+	switch(type) {
+	case CT_FLUSH_MASTER:
+		local_flush_master();
+		break;
+	case CT_RESYNC_MASTER:
+		local_resync_master();
+		break;
+	case EXP_FLUSH_MASTER:
+		local_exp_flush_master();
+		break;
+	case EXP_RESYNC_MASTER:
+		local_exp_resync_master();
+		break;
+	case ALL_FLUSH_MASTER:
+		local_flush_master();
+		local_exp_flush_master();
+		break;
+	case ALL_RESYNC_MASTER:
+		local_resync_master();
+		local_exp_resync_master();
+		break;
+	}
+
+	ret = STATE(mode)->local(fd, type, data);
+	if (ret == LOCAL_RET_ERROR) {
+		STATE(stats).local_unknown_request++;
+		return LOCAL_RET_ERROR;
+	}
+	return ret;
+}
+
+static void do_overrun_resync_alarm(struct alarm_block *a, void *data)
+{
+	nl_send_resync(STATE(resync));
+	STATE(stats).nl_kernel_table_resync++;
+}
+
+static void do_polling_alarm(struct alarm_block *a, void *data)
+{
+	if (STATE(mode)->internal->ct.purge)
+		STATE(mode)->internal->ct.purge();
+
+	if (STATE(mode)->internal->exp.purge)
+		STATE(mode)->internal->exp.purge();
+
+	nl_send_resync(STATE(resync));
+	nl_send_expect_resync(STATE(resync));
+	add_alarm(&STATE(polling_alarm), CONFIG(poll_kernel_secs), 0);
+}
+
+static int event_handler(const struct nlmsghdr *nlh,
+			 enum nf_conntrack_msg_type type,
+			 struct nf_conntrack *ct,
+			 void *data)
+{
+	int origin_type;
+
+	STATE(stats).nl_events_received++;
+
+	/* skip user-space filtering if already do it in the kernel */
+	if (ct_filter_conntrack(ct, !CONFIG(filter_from_kernelspace))) {
+		STATE(stats).nl_events_filtered++;
+		goto out;
+	}
+
+	origin_type = origin_find(nlh);
+
+	switch(type) {
+	case NFCT_T_NEW:
+		STATE(mode)->internal->ct.new(ct, origin_type);
+		break;
+	case NFCT_T_UPDATE:
+		STATE(mode)->internal->ct.upd(ct, origin_type);
+		break;
+	case NFCT_T_DESTROY:
+		if (STATE(mode)->internal->ct.del(ct, origin_type))
+			update_traffic_stats(ct);
+		break;
+	default:
+		STATE(stats).nl_events_unknown_type++;
+		break;
+	}
+
+out:
+	/* we reset the iteration limiter in the main select loop. */
+	if (STATE(event_iterations_limit)-- <= 0)
+		return NFCT_CB_STOP;
+	else
+		return NFCT_CB_CONTINUE;
+}
+
+static int exp_event_handler(const struct nlmsghdr *nlh,
+			     enum nf_conntrack_msg_type type,
+			     struct nf_expect *exp,
+			     void *data)
+{
+	int origin_type;
+	const struct nf_conntrack *master =
+		nfexp_get_attr(exp, ATTR_EXP_MASTER);
+
+	STATE(stats).nl_events_received++;
+
+	if (!exp_filter_find(STATE(exp_filter), exp)) {
+		STATE(stats).nl_events_filtered++;
+		goto out;
+	}
+	if (ct_filter_conntrack(master, 1))
+		return NFCT_CB_CONTINUE;
+
+	origin_type = origin_find(nlh);
+
+	switch(type) {
+	case NFCT_T_NEW:
+		STATE(mode)->internal->exp.new(exp, origin_type);
+		break;
+	case NFCT_T_UPDATE:
+		STATE(mode)->internal->exp.upd(exp, origin_type);
+		break;
+	case NFCT_T_DESTROY:
+		STATE(mode)->internal->exp.del(exp, origin_type);
+		break;
+	default:
+		STATE(stats).nl_events_unknown_type++;
+		break;
+	}
+
+out:
+	/* we reset the iteration limiter in the main select loop. */
+	if (STATE(event_iterations_limit)-- <= 0)
+		return NFCT_CB_STOP;
+	else
+		return NFCT_CB_CONTINUE;
+}
+
+static int dump_handler(enum nf_conntrack_msg_type type,
+			struct nf_conntrack *ct,
+			void *data)
+{
+	if (ct_filter_conntrack(ct, 1))
+		return NFCT_CB_CONTINUE;
+
+	switch(type) {
+	case NFCT_T_UPDATE:
+		STATE(mode)->internal->ct.populate(ct);
+		break;
+	default:
+		STATE(stats).nl_dump_unknown_type++;
+		break;
+	}
+	return NFCT_CB_CONTINUE;
+}
+
+static int exp_dump_handler(enum nf_conntrack_msg_type type,
+			    struct nf_expect *exp, void *data)
+{
+	const struct nf_conntrack *master =
+		nfexp_get_attr(exp, ATTR_EXP_MASTER);
+
+	if (!exp_filter_find(STATE(exp_filter), exp))
+		return NFCT_CB_CONTINUE;
+
+	if (ct_filter_conntrack(master, 1))
+		return NFCT_CB_CONTINUE;
+
+	switch(type) {
+	case NFCT_T_UPDATE:
+		STATE(mode)->internal->exp.populate(exp);
+		break;
+	default:
+		STATE(stats).nl_dump_unknown_type++;
+		break;
+	}
+	return NFCT_CB_CONTINUE;
+}
+
+static int get_handler(enum nf_conntrack_msg_type type,
+		       struct nf_conntrack *ct,
+		       void *data)
+{
+	if (ct_filter_conntrack(ct, 1))
+		return NFCT_CB_CONTINUE;
+
+	STATE(get_retval) = 1;
+	return NFCT_CB_CONTINUE;
+}
+
+static int exp_get_handler(enum nf_conntrack_msg_type type,
+			   struct nf_expect *exp, void *data)
+{
+	const struct nf_conntrack *master =
+		nfexp_get_attr(exp, ATTR_EXP_MASTER);
+
+	if (!exp_filter_find(STATE(exp_filter), exp))
+		return NFCT_CB_CONTINUE;
+
+	if (ct_filter_conntrack(master, 1))
+		return NFCT_CB_CONTINUE;
+
+	STATE(get_retval) = 1;
+	return NFCT_CB_CONTINUE;
+}
+
+/* we have received an event from ctnetlink */
+static void event_cb(void *data)
+{
+	int ret;
+
+	ret = nfct_catch(STATE(event));
+	/* reset event iteration limit counter */
+	STATE(event_iterations_limit) = CONFIG(event_iterations_limit);
+	if (ret == -1) {
+		switch(errno) {
+		case ENOBUFS:
+			/* We have hit ENOBUFS, it's likely that we are
+			 * losing events. Two possible situations may
+			 * trigger this error:
+			 *
+			 * 1) The netlink receiver buffer is too small:
+			 *    increasing the netlink buffer size should
+			 *    be enough. However, some event messages
+			 *    got lost. We have to resync ourselves
+			 *    with the kernel table conntrack table to
+			 *    resolve the inconsistency.
+			 *
+			 * 2) The receiver is too slow to process the
+			 *    netlink messages so that the queue gets
+			 *    full quickly. This generally happens
+			 *    if the system is under heavy workload
+			 *    (busy CPU). In this case, increasing the
+			 *    size of the netlink receiver buffer
+			 *    would not help anymore since we would
+			 *    be delaying the overrun. Moreover, we
+			 *    should avoid resynchronizations. We
+			 *    should do our best here and keep
+			 *    replicating as much states as possible.
+			 *    If workload lowers at some point,
+			 *    we resync ourselves.
+			 */
+			nl_resize_socket_buffer(STATE(event));
+			if (CONFIG(nl_overrun_resync) > 0 &&
+			    STATE(mode)->internal->flags & INTERNAL_F_RESYNC) {
+				add_alarm(&STATE(resync_alarm),
+					  CONFIG(nl_overrun_resync),0);
+			}
+			STATE(stats).nl_catch_event_failed++;
+			STATE(stats).nl_overrun++;
+			break;
+		case ENOENT:
+			/*
+			 * We received a message from another
+			 * netfilter subsystem that we are not
+			 * interested in. Just ignore it.
+			 */
+		break;
+		case EAGAIN:
+			/* No more events to receive, try later. */
+			break;
+		default:
+			STATE(stats).nl_catch_event_failed++;
+			break;
+		}
+	}
+}
+
+/* we previously requested a resync due to buffer overrun. */
+static void resync_cb(void *data)
+{
+	nfct_catch(STATE(resync));
+	if (STATE(mode)->internal->ct.purge)
+		STATE(mode)->internal->ct.purge();
+}
+
+static void poll_cb(void *data)
+{
+	nfct_catch(STATE(resync));
+}
+
+int ctnl_init(void)
+{
+	if (CONFIG(flags) & CTD_STATS_MODE)
+		STATE(mode) = &stats_mode;
+	else if (CONFIG(flags) & CTD_SYNC_MODE)
+		STATE(mode) = &sync_mode;
+	else {
+		fprintf(stderr, "WARNING: No running mode specified. "
+				"Defaulting to statistics mode.\n");
+		CONFIG(flags) |= CTD_STATS_MODE;
+		STATE(mode) = &stats_mode;
+	}
+
+	/* Initialization */
+	if (STATE(mode)->init() == -1) {
+		dlog(LOG_ERR, "initialization failed");
+		return -1;
+	}
+
+	/* resynchronize (like 'dump' socket) but it also purges old entries */
+	STATE(resync) = nfct_open(CONFIG(netlink).subsys_id, 0);
+	if (STATE(resync)== NULL) {
+		dlog(LOG_ERR, "can't open netlink handler: %s",
+		     strerror(errno));
+		dlog(LOG_ERR, "no ctnetlink kernel support?");
+		return -1;
+	}
+	nfct_callback_register(STATE(resync),
+			       NFCT_T_ALL,
+			       STATE(mode)->internal->ct.resync,
+			       NULL);
+	if (CONFIG(flags) & CTD_POLL) {
+		register_fd(nfct_fd(STATE(resync)), poll_cb,
+				NULL, STATE(fds));
+	} else {
+		register_fd(nfct_fd(STATE(resync)), resync_cb,
+				NULL, STATE(fds));
+	}
+	fcntl(nfct_fd(STATE(resync)), F_SETFL, O_NONBLOCK);
+
+	if (STATE(mode)->internal->flags & INTERNAL_F_POPULATE) {
+		STATE(dump) = nfct_open(CONFIG(netlink).subsys_id, 0);
+		if (STATE(dump) == NULL) {
+			dlog(LOG_ERR, "can't open netlink handler: %s",
+			     strerror(errno));
+			dlog(LOG_ERR, "no ctnetlink kernel support?");
+			return -1;
+		}
+		nfct_callback_register(STATE(dump), NFCT_T_ALL,
+				       dump_handler, NULL);
+
+		if (CONFIG(flags) & CTD_EXPECT) {
+			nfexp_callback_register(STATE(dump), NFCT_T_ALL,
+						exp_dump_handler, NULL);
+		}
+
+		if (nl_dump_conntrack_table(STATE(dump)) == -1) {
+			dlog(LOG_ERR, "can't get kernel conntrack table");
+			return -1;
+		}
+
+		if (CONFIG(flags) & CTD_EXPECT) {
+			if (nl_dump_expect_table(STATE(dump)) == -1) {
+				dlog(LOG_ERR, "can't get kernel "
+					      "expect table");
+				return -1;
+			}
+		}
+	}
+
+	STATE(get) = nfct_open(CONFIG(netlink).subsys_id, 0);
+	if (STATE(get) == NULL) {
+		dlog(LOG_ERR, "can't open netlink handler: %s",
+		     strerror(errno));
+		dlog(LOG_ERR, "no ctnetlink kernel support?");
+		return -1;
+	}
+	nfct_callback_register(STATE(get), NFCT_T_ALL, get_handler, NULL);
+
+	if (CONFIG(flags) & CTD_EXPECT) {
+		nfexp_callback_register(STATE(get), NFCT_T_ALL,
+					exp_get_handler, NULL);
+	}
+
+	STATE(flush) = nfct_open(CONFIG(netlink).subsys_id, 0);
+	if (STATE(flush) == NULL) {
+		dlog(LOG_ERR, "cannot open flusher handler");
+		return -1;
+	}
+	/* register this handler as the origin of a flush operation */
+	origin_register(STATE(flush), CTD_ORIGIN_FLUSH);
+
+	if (CONFIG(flags) & CTD_POLL) {
+		init_alarm(&STATE(polling_alarm), NULL, do_polling_alarm);
+		add_alarm(&STATE(polling_alarm), CONFIG(poll_kernel_secs), 0);
+		dlog(LOG_NOTICE, "running in polling mode");
+	} else {
+		init_alarm(&STATE(resync_alarm), NULL, do_overrun_resync_alarm);
+		/*
+		 * The last nfct handler that we register is the event handler.
+		 * The reason to do this is that we may receive events while
+		 * populating the internal cache. Thus, we hit ENOBUFS
+		 * prematurely. However, if we open the event handler before
+		 * populating the internal cache, we may still lose events
+		 * that have occured during the population.
+		 */
+		STATE(event) = nl_init_event_handler();
+		if (STATE(event) == NULL) {
+			dlog(LOG_ERR, "can't open netlink handler: %s",
+			     strerror(errno));
+			dlog(LOG_ERR, "no ctnetlink kernel support?");
+			return -1;
+		}
+		nfct_callback_register2(STATE(event), NFCT_T_ALL,
+				        event_handler, NULL);
+
+		if (CONFIG(flags) & CTD_EXPECT) {
+			nfexp_callback_register2(STATE(event), NFCT_T_ALL,
+						 exp_event_handler, NULL);
+		}
+		register_fd(nfct_fd(STATE(event)), event_cb, NULL, STATE(fds));
+	}
+
+	return 0;
+}