netfilter: ctnetlink: deliver events for conntracks changed from userspace

As for now, the creation and update of conntracks via ctnetlink do not
propagate an event to userspace. This can result in inconsistent situations
if several userspace processes modify the connection tracking table by means
of ctnetlink at the same time. Specifically, using the conntrack command
line tool and conntrackd at the same time can trigger unconsistencies.

This patch also modifies the event cache infrastructure to pass the
process PID and the ECHO flag to nfnetlink_send() to report back
to userspace if the process that triggered the change needs so.
Based on a suggestion from Patrick McHardy.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 73 insertions, 15 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 4f6486cfd337..ccc5ef1d7573 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -410,7 +410,8 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
 	struct nlmsghdr *nlh;
 	struct nfgenmsg *nfmsg;
 	struct nlattr *nest_parms;
-	struct nf_conn *ct = (struct nf_conn *)ptr;
+	struct nf_ct_event *item = (struct nf_ct_event *)ptr;
+	struct nf_conn *ct = item->ct;
 	struct sk_buff *skb;
 	unsigned int type;
 	sk_buff_data_t b;
@@ -443,7 +444,7 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
 	b = skb->tail;
 
 	type |= NFNL_SUBSYS_CTNETLINK << 8;
-	nlh   = NLMSG_PUT(skb, 0, 0, type, sizeof(struct nfgenmsg));
+	nlh   = NLMSG_PUT(skb, item->pid, 0, type, sizeof(struct nfgenmsg));
 	nfmsg = NLMSG_DATA(nlh);
 
 	nlh->nlmsg_flags    = flags;
@@ -511,7 +512,7 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
 	rcu_read_unlock();
 
 	nlh->nlmsg_len = skb->tail - b;
-	nfnetlink_send(skb, 0, group, 0);
+	nfnetlink_send(skb, item->pid, group, item->report);
 	return NOTIFY_DONE;
 
 nla_put_failure:
@@ -722,7 +723,9 @@ ctnetlink_del_conntrack(struct sock *ctnl, struct sk_buff *skb,
 		err = ctnetlink_parse_tuple(cda, &tuple, CTA_TUPLE_REPLY, u3);
 	else {
 		/* Flush the whole table */
-		nf_conntrack_flush(&init_net);
+		nf_conntrack_flush(&init_net, 
+				   NETLINK_CB(skb).pid, 
+				   nlmsg_report(nlh));
 		return 0;
 	}
 
@@ -743,6 +746,14 @@ ctnetlink_del_conntrack(struct sock *ctnl, struct sk_buff *skb,
 		}
 	}
 
+	nf_conntrack_event_report(IPCT_DESTROY,
+				  ct,
+				  NETLINK_CB(skb).pid,
+				  nlmsg_report(nlh));
+
+	/* death_by_timeout would report the event again */
+	set_bit(IPS_DYING_BIT, &ct->status);
+
 	nf_ct_kill(ct);
 	nf_ct_put(ct);
 
@@ -1088,11 +1099,35 @@ ctnetlink_change_conntrack(struct nf_conn *ct, struct nlattr *cda[])
 	return 0;
 }
 
+static inline void
+ctnetlink_event_report(struct nf_conn *ct, u32 pid, int report)
+{
+	unsigned int events = 0;
+
+	if (test_bit(IPS_EXPECTED_BIT, &ct->status))
+		events |= IPCT_RELATED;
+	else
+		events |= IPCT_NEW;
+
+	nf_conntrack_event_report(IPCT_STATUS |
+				  IPCT_HELPER |
+				  IPCT_REFRESH |
+				  IPCT_PROTOINFO |
+				  IPCT_NATSEQADJ |
+				  IPCT_MARK |
+				  events,
+				  ct,
+				  pid,
+				  report);
+}
+
 static int
 ctnetlink_create_conntrack(struct nlattr *cda[],
 			   struct nf_conntrack_tuple *otuple,
 			   struct nf_conntrack_tuple *rtuple,
-			   struct nf_conn *master_ct)
+			   struct nf_conn *master_ct,
+			   u32 pid,
+			   int report)
 {
 	struct nf_conn *ct;
 	int err = -EINVAL;
@@ -1198,9 +1233,12 @@ ctnetlink_create_conntrack(struct nlattr *cda[],
 		ct->master = master_ct;
 	}
 
+	nf_conntrack_get(&ct->ct_general);
 	add_timer(&ct->timeout);
 	nf_conntrack_hash_insert(ct);
 	rcu_read_unlock();
+	ctnetlink_event_report(ct, pid, report);
+	nf_ct_put(ct);
 
 	return 0;
 
@@ -1265,7 +1303,9 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
 			err = ctnetlink_create_conntrack(cda,
 							 &otuple,
 							 &rtuple,
-							 master_ct);
+							 master_ct,
+							 NETLINK_CB(skb).pid,
+							 nlmsg_report(nlh));
 		if (err < 0 && master_ct)
 			nf_ct_put(master_ct);
 
@@ -1277,6 +1317,8 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
 	 * so there's no need to increase the refcount */
 	err = -EEXIST;
 	if (!(nlh->nlmsg_flags & NLM_F_EXCL)) {
+		struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
+
 		/* we only allow nat config for new conntracks */
 		if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST]) {
 			err = -EOPNOTSUPP;
@@ -1287,8 +1329,19 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
 			err = -EOPNOTSUPP;
 			goto out_unlock;
 		}
-		err = ctnetlink_change_conntrack(nf_ct_tuplehash_to_ctrack(h),
-						 cda);
+
+		err = ctnetlink_change_conntrack(ct, cda);
+		if (err == 0) {
+			nf_conntrack_get(&ct->ct_general);
+			spin_unlock_bh(&nf_conntrack_lock);
+			ctnetlink_event_report(ct,
+					       NETLINK_CB(skb).pid,
+					       nlmsg_report(nlh));
+			nf_ct_put(ct);
+		} else
+			spin_unlock_bh(&nf_conntrack_lock);
+
+		return err;
 	}
 
 out_unlock:
@@ -1423,7 +1476,8 @@ static int ctnetlink_expect_event(struct notifier_block *this,
 {
 	struct nlmsghdr *nlh;
 	struct nfgenmsg *nfmsg;
-	struct nf_conntrack_expect *exp = (struct nf_conntrack_expect *)ptr;
+	struct nf_exp_event *item = (struct nf_exp_event *)ptr;
+	struct nf_conntrack_expect *exp = item->exp;
 	struct sk_buff *skb;
 	unsigned int type;
 	sk_buff_data_t b;
@@ -1445,7 +1499,7 @@ static int ctnetlink_expect_event(struct notifier_block *this,
 	b = skb->tail;
 
 	type |= NFNL_SUBSYS_CTNETLINK_EXP << 8;
-	nlh   = NLMSG_PUT(skb, 0, 0, type, sizeof(struct nfgenmsg));
+	nlh   = NLMSG_PUT(skb, item->pid, 0, type, sizeof(struct nfgenmsg));
 	nfmsg = NLMSG_DATA(nlh);
 
 	nlh->nlmsg_flags    = flags;
@@ -1459,7 +1513,7 @@ static int ctnetlink_expect_event(struct notifier_block *this,
 	rcu_read_unlock();
 
 	nlh->nlmsg_len = skb->tail - b;
-	nfnetlink_send(skb, 0, NFNLGRP_CONNTRACK_EXP_NEW, 0);
+	nfnetlink_send(skb, item->pid, NFNLGRP_CONNTRACK_EXP_NEW, item->report);
 	return NOTIFY_DONE;
 
 nla_put_failure:
@@ -1673,7 +1727,7 @@ ctnetlink_change_expect(struct nf_conntrack_expect *x, struct nlattr *cda[])
 }
 
 static int
-ctnetlink_create_expect(struct nlattr *cda[], u_int8_t u3)
+ctnetlink_create_expect(struct nlattr *cda[], u_int8_t u3, u32 pid, int report)
 {
 	struct nf_conntrack_tuple tuple, mask, master_tuple;
 	struct nf_conntrack_tuple_hash *h = NULL;
@@ -1720,7 +1774,7 @@ ctnetlink_create_expect(struct nlattr *cda[], u_int8_t u3)
 	memcpy(&exp->mask.src.u3, &mask.src.u3, sizeof(exp->mask.src.u3));
 	exp->mask.src.u.all = mask.src.u.all;
 
-	err = nf_ct_expect_related(exp);
+	err = nf_ct_expect_related_report(exp, pid, report);
 	nf_ct_expect_put(exp);
 
 out:
@@ -1753,8 +1807,12 @@ ctnetlink_new_expect(struct sock *ctnl, struct sk_buff *skb,
 	if (!exp) {
 		spin_unlock_bh(&nf_conntrack_lock);
 		err = -ENOENT;
-		if (nlh->nlmsg_flags & NLM_F_CREATE)
-			err = ctnetlink_create_expect(cda, u3);
+		if (nlh->nlmsg_flags & NLM_F_CREATE) {
+			err = ctnetlink_create_expect(cda,
+						      u3,
+						      NETLINK_CB(skb).pid,
+						      nlmsg_report(nlh));
+		}
 		return err;
 	}