1 files changed, 201 insertions, 120 deletions

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index a634c72b1ffc..656631083177 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -47,6 +47,12 @@ static const char *const tcp_conntrack_names[] = {
 	"SYN_SENT2",
 };
 
+enum nf_ct_tcp_action {
+	NFCT_TCP_IGNORE,
+	NFCT_TCP_INVALID,
+	NFCT_TCP_ACCEPT,
+};
+
 #define SECS * HZ
 #define MINS * 60 SECS
 #define HOURS * 60 MINS
@@ -472,23 +478,45 @@ static void tcp_init_sender(struct ip_ct_tcp_state *sender,
 	}
 }
 
-static bool tcp_in_window(struct nf_conn *ct,
-			  enum ip_conntrack_dir dir,
-			  unsigned int index,
-			  const struct sk_buff *skb,
-			  unsigned int dataoff,
-			  const struct tcphdr *tcph,
-			  const struct nf_hook_state *hook_state)
+__printf(6, 7)
+static enum nf_ct_tcp_action nf_tcp_log_invalid(const struct sk_buff *skb,
+						const struct nf_conn *ct,
+						const struct nf_hook_state *state,
+						const struct ip_ct_tcp_state *sender,
+						enum nf_ct_tcp_action ret,
+						const char *fmt, ...)
+{
+	const struct nf_tcp_net *tn = nf_tcp_pernet(nf_ct_net(ct));
+	struct va_format vaf;
+	va_list args;
+	bool be_liberal;
+
+	be_liberal = sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL || tn->tcp_be_liberal;
+	if (be_liberal)
+		return NFCT_TCP_ACCEPT;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	nf_ct_l4proto_log_invalid(skb, ct, state, "%pV", &vaf);
+	va_end(args);
+
+	return ret;
+}
+
+static enum nf_ct_tcp_action
+tcp_in_window(struct nf_conn *ct, enum ip_conntrack_dir dir,
+	      unsigned int index, const struct sk_buff *skb,
+	      unsigned int dataoff, const struct tcphdr *tcph,
+	      const struct nf_hook_state *hook_state)
 {
 	struct ip_ct_tcp *state = &ct->proto.tcp;
-	struct net *net = nf_ct_net(ct);
-	struct nf_tcp_net *tn = nf_tcp_pernet(net);
 	struct ip_ct_tcp_state *sender = &state->seen[dir];
 	struct ip_ct_tcp_state *receiver = &state->seen[!dir];
 	__u32 seq, ack, sack, end, win, swin;
-	u16 win_raw;
+	bool in_recv_win, seq_ok;
 	s32 receiver_offset;
-	bool res, in_recv_win;
+	u16 win_raw;
 
 	/*
 	 * Get the required data from the packet.
@@ -517,7 +545,7 @@ static bool tcp_in_window(struct nf_conn *ct,
 					end, win);
 			if (!tcph->ack)
 				/* Simultaneous open */
-				return true;
+				return NFCT_TCP_ACCEPT;
 		} else {
 			/*
 			 * We are in the middle of a connection,
@@ -560,7 +588,7 @@ static bool tcp_in_window(struct nf_conn *ct,
 				end, win);
 
 		if (dir == IP_CT_DIR_REPLY && !tcph->ack)
-			return true;
+			return NFCT_TCP_ACCEPT;
 	}
 
 	if (!(tcph->ack)) {
@@ -584,122 +612,166 @@ static bool tcp_in_window(struct nf_conn *ct,
 		 */
 		seq = end = sender->td_end;
 
-	/* Is the ending sequence in the receive window (if available)? */
-	in_recv_win = !receiver->td_maxwin ||
-		      after(end, sender->td_end - receiver->td_maxwin - 1);
-
-	if (before(seq, sender->td_maxend + 1) &&
-	    in_recv_win &&
-	    before(sack, receiver->td_end + 1) &&
-	    after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1)) {
-		/*
-		 * Take into account window scaling (RFC 1323).
-		 */
-		if (!tcph->syn)
-			win <<= sender->td_scale;
-
-		/*
-		 * Update sender data.
-		 */
-		swin = win + (sack - ack);
-		if (sender->td_maxwin < swin)
-			sender->td_maxwin = swin;
-		if (after(end, sender->td_end)) {
+	seq_ok = before(seq, sender->td_maxend + 1);
+	if (!seq_ok) {
+		u32 overshot = end - sender->td_maxend + 1;
+		bool ack_ok;
+
+		ack_ok = after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1);
+		in_recv_win = receiver->td_maxwin &&
+			      after(end, sender->td_end - receiver->td_maxwin - 1);
+
+		if (in_recv_win &&
+		    ack_ok &&
+		    overshot <= receiver->td_maxwin &&
+		    before(sack, receiver->td_end + 1)) {
+			/* Work around TCPs that send more bytes than allowed by
+			 * the receive window.
+			 *
+			 * If the (marked as invalid) packet is allowed to pass by
+			 * the ruleset and the peer acks this data, then its possible
+			 * all future packets will trigger 'ACK is over upper bound' check.
+			 *
+			 * Thus if only the sequence check fails then do update td_end so
+			 * possible ACK for this data can update internal state.
+			 */
 			sender->td_end = end;
 			sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
-		}
-		if (tcph->ack) {
-			if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
-				sender->td_maxack = ack;
-				sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
-			} else if (after(ack, sender->td_maxack))
-				sender->td_maxack = ack;
+
+			return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
+						  "%u bytes more than expected", overshot);
 		}
 
-		/*
-		 * Update receiver data.
-		 */
-		if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
-			receiver->td_maxwin += end - sender->td_maxend;
-		if (after(sack + win, receiver->td_maxend - 1)) {
-			receiver->td_maxend = sack + win;
-			if (win == 0)
-				receiver->td_maxend++;
+		return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
+					  "SEQ is over upper bound %u (over the window of the receiver)",
+					  sender->td_maxend + 1);
+	}
+
+	if (!before(sack, receiver->td_end + 1))
+		return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_INVALID,
+					  "ACK is over upper bound %u (ACKed data not seen yet)",
+					  receiver->td_end + 1);
+
+	/* Is the ending sequence in the receive window (if available)? */
+	in_recv_win = !receiver->td_maxwin ||
+		      after(end, sender->td_end - receiver->td_maxwin - 1);
+	if (!in_recv_win)
+		return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
+					  "SEQ is under lower bound %u (already ACKed data retransmitted)",
+					  sender->td_end - receiver->td_maxwin - 1);
+	if (!after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1))
+		return nf_tcp_log_invalid(skb, ct, hook_state, sender, NFCT_TCP_IGNORE,
+					  "ignored ACK under lower bound %u (possible overly delayed)",
+					  receiver->td_end - MAXACKWINDOW(sender) - 1);
+
+	/* Take into account window scaling (RFC 1323). */
+	if (!tcph->syn)
+		win <<= sender->td_scale;
+
+	/* Update sender data. */
+	swin = win + (sack - ack);
+	if (sender->td_maxwin < swin)
+		sender->td_maxwin = swin;
+	if (after(end, sender->td_end)) {
+		sender->td_end = end;
+		sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
+	}
+	if (tcph->ack) {
+		if (!(sender->flags & IP_CT_TCP_FLAG_MAXACK_SET)) {
+			sender->td_maxack = ack;
+			sender->flags |= IP_CT_TCP_FLAG_MAXACK_SET;
+		} else if (after(ack, sender->td_maxack)) {
+			sender->td_maxack = ack;
 		}
-		if (ack == receiver->td_end)
-			receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
+	}
 
-		/*
-		 * Check retransmissions.
-		 */
-		if (index == TCP_ACK_SET) {
-			if (state->last_dir == dir
-			    && state->last_seq == seq
-			    && state->last_ack == ack
-			    && state->last_end == end
-			    && state->last_win == win_raw)
-				state->retrans++;
-			else {
-				state->last_dir = dir;
-				state->last_seq = seq;
-				state->last_ack = ack;
-				state->last_end = end;
-				state->last_win = win_raw;
-				state->retrans = 0;
-			}
+	/* Update receiver data. */
+	if (receiver->td_maxwin != 0 && after(end, sender->td_maxend))
+		receiver->td_maxwin += end - sender->td_maxend;
+	if (after(sack + win, receiver->td_maxend - 1)) {
+		receiver->td_maxend = sack + win;
+		if (win == 0)
+			receiver->td_maxend++;
+	}
+	if (ack == receiver->td_end)
+		receiver->flags &= ~IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
+
+	/* Check retransmissions. */
+	if (index == TCP_ACK_SET) {
+		if (state->last_dir == dir &&
+		    state->last_seq == seq &&
+		    state->last_ack == ack &&
+		    state->last_end == end &&
+		    state->last_win == win_raw) {
+			state->retrans++;
+		} else {
+			state->last_dir = dir;
+			state->last_seq = seq;
+			state->last_ack = ack;
+			state->last_end = end;
+			state->last_win = win_raw;
+			state->retrans = 0;
 		}
-		res = true;
-	} else {
-		res = false;
-		if (sender->flags & IP_CT_TCP_FLAG_BE_LIBERAL ||
-		    tn->tcp_be_liberal)
-			res = true;
-		if (!res) {
-			bool seq_ok = before(seq, sender->td_maxend + 1);
-
-			if (!seq_ok) {
-				u32 overshot = end - sender->td_maxend + 1;
-				bool ack_ok;
-
-				ack_ok = after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1);
-
-				if (in_recv_win &&
-				    ack_ok &&
-				    overshot <= receiver->td_maxwin &&
-				    before(sack, receiver->td_end + 1)) {
-					/* Work around TCPs that send more bytes than allowed by
-					 * the receive window.
-					 *
-					 * If the (marked as invalid) packet is allowed to pass by
-					 * the ruleset and the peer acks this data, then its possible
-					 * all future packets will trigger 'ACK is over upper bound' check.
-					 *
-					 * Thus if only the sequence check fails then do update td_end so
-					 * possible ACK for this data can update internal state.
-					 */
-					sender->td_end = end;
-					sender->flags |= IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED;
-
-					nf_ct_l4proto_log_invalid(skb, ct, hook_state,
-								  "%u bytes more than expected", overshot);
-					return res;
-				}
-			}
+	}
+
+	return NFCT_TCP_ACCEPT;
+}
+
+static void __cold nf_tcp_handle_invalid(struct nf_conn *ct,
+					 enum ip_conntrack_dir dir,
+					 int index,
+					 const struct sk_buff *skb,
+					 const struct nf_hook_state *hook_state)
+{
+	const unsigned int *timeouts;
+	const struct nf_tcp_net *tn;
+	unsigned int timeout;
+	u32 expires;
+
+	if (!test_bit(IPS_ASSURED_BIT, &ct->status) ||
+	    test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
+		return;
+
+	/* We don't want to have connections hanging around in ESTABLISHED
+	 * state for long time 'just because' conntrack deemed a FIN/RST
+	 * out-of-window.
+	 *
+	 * Shrink the timeout just like when there is unacked data.
+	 * This speeds up eviction of 'dead' connections where the
+	 * connection and conntracks internal state are out of sync.
+	 */
+	switch (index) {
+	case TCP_RST_SET:
+	case TCP_FIN_SET:
+		break;
+	default:
+		return;
+	}
+
+	if (ct->proto.tcp.last_dir != dir &&
+	    (ct->proto.tcp.last_index == TCP_FIN_SET ||
+	     ct->proto.tcp.last_index == TCP_RST_SET)) {
+		expires = nf_ct_expires(ct);
+		if (expires < 120 * HZ)
+			return;
+
+		tn = nf_tcp_pernet(nf_ct_net(ct));
+		timeouts = nf_ct_timeout_lookup(ct);
+		if (!timeouts)
+			timeouts = tn->timeouts;
 
+		timeout = READ_ONCE(timeouts[TCP_CONNTRACK_UNACK]);
+		if (expires > timeout) {
 			nf_ct_l4proto_log_invalid(skb, ct, hook_state,
-			"%s",
-			before(seq, sender->td_maxend + 1) ?
-			in_recv_win ?
-			before(sack, receiver->td_end + 1) ?
-			after(sack, receiver->td_end - MAXACKWINDOW(sender) - 1) ? "BUG"
-			: "ACK is under the lower bound (possible overly delayed ACK)"
-			: "ACK is over the upper bound (ACKed data not seen yet)"
-			: "SEQ is under the lower bound (already ACKed data retransmitted)"
-			: "SEQ is over the upper bound (over the window of the receiver)");
+					  "packet (index %d, dir %d) response for index %d lower timeout to %u",
+					  index, dir, ct->proto.tcp.last_index, timeout);
+
+			WRITE_ONCE(ct->timeout, timeout + nfct_time_stamp);
 		}
+	} else {
+		ct->proto.tcp.last_index = index;
+		ct->proto.tcp.last_dir = dir;
 	}
-
-	return res;
 }
 
 /* table of valid flag combinations - PUSH, ECE and CWR are always valid */
@@ -861,6 +933,7 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct,
 	struct nf_conntrack_tuple *tuple;
 	enum tcp_conntrack new_state, old_state;
 	unsigned int index, *timeouts;
+	enum nf_ct_tcp_action res;
 	enum ip_conntrack_dir dir;
 	const struct tcphdr *th;
 	struct tcphdr _tcph;
@@ -1126,10 +1199,18 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct,
 		break;
 	}
 
-	if (!tcp_in_window(ct, dir, index,
-			   skb, dataoff, th, state)) {
+	res = tcp_in_window(ct, dir, index,
+			    skb, dataoff, th, state);
+	switch (res) {
+	case NFCT_TCP_IGNORE:
+		spin_unlock_bh(&ct->lock);
+		return NF_ACCEPT;
+	case NFCT_TCP_INVALID:
+		nf_tcp_handle_invalid(ct, dir, index, skb, state);
 		spin_unlock_bh(&ct->lock);
 		return -NF_ACCEPT;
+	case NFCT_TCP_ACCEPT:
+		break;
 	}
      in_window:
 	/* From now on we have got in-window packets */