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[Qemu-devel] [PULL 01/25] filter-rewriter: Add TCP state machine and fix
From: |
Jason Wang |
Subject: |
[Qemu-devel] [PULL 01/25] filter-rewriter: Add TCP state machine and fix memory leak in connection_track_table |
Date: |
Wed, 26 Sep 2018 11:16:26 +0800 |
From: Zhang Chen <address@hidden>
We add almost full TCP state machine in filter-rewriter, except
TCPS_LISTEN and some simplify in VM active close FIN states.
The reason for this simplify job is because guest kernel will track
the TCP status and wait 2MSL time too, if client resend the FIN packet,
guest will resend the last ACK, so we needn't wait 2MSL time in filter-rewriter.
After a net connection is closed, we didn't clear its related resources
in connection_track_table, which will lead to memory leak.
Let's track the state of net connection, if it is closed, its related
resources will be cleared up.
Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Zhang Chen <address@hidden>
Signed-off-by: Zhang Chen <address@hidden>
Signed-off-by: Jason Wang <address@hidden>
---
net/colo.c | 2 +-
net/colo.h | 9 ++--
net/filter-rewriter.c | 109 ++++++++++++++++++++++++++++++++++++++----
3 files changed, 104 insertions(+), 16 deletions(-)
diff --git a/net/colo.c b/net/colo.c
index 6dda4ed66e..97c8fc928f 100644
--- a/net/colo.c
+++ b/net/colo.c
@@ -137,7 +137,7 @@ Connection *connection_new(ConnectionKey *key)
conn->ip_proto = key->ip_proto;
conn->processing = false;
conn->offset = 0;
- conn->syn_flag = 0;
+ conn->tcp_state = TCPS_CLOSED;
conn->pack = 0;
conn->sack = 0;
g_queue_init(&conn->primary_list);
diff --git a/net/colo.h b/net/colo.h
index da6c36dcf7..0277e0e9ba 100644
--- a/net/colo.h
+++ b/net/colo.h
@@ -18,6 +18,7 @@
#include "slirp/slirp.h"
#include "qemu/jhash.h"
#include "qemu/timer.h"
+#include "slirp/tcp.h"
#define HASHTABLE_MAX_SIZE 16384
@@ -81,11 +82,9 @@ typedef struct Connection {
uint32_t sack;
/* offset = secondary_seq - primary_seq */
tcp_seq offset;
- /*
- * we use this flag update offset func
- * run once in independent tcp connection
- */
- int syn_flag;
+
+ int tcp_state; /* TCP FSM state */
+ tcp_seq fin_ack_seq; /* the seq of 'fin=1,ack=1' */
} Connection;
uint32_t connection_key_hash(const void *opaque);
diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
index f584e4eba4..dd323faf61 100644
--- a/net/filter-rewriter.c
+++ b/net/filter-rewriter.c
@@ -59,9 +59,9 @@ static int is_tcp_packet(Packet *pkt)
}
/* handle tcp packet from primary guest */
-static int handle_primary_tcp_pkt(NetFilterState *nf,
+static int handle_primary_tcp_pkt(RewriterState *rf,
Connection *conn,
- Packet *pkt)
+ Packet *pkt, ConnectionKey *key)
{
struct tcphdr *tcp_pkt;
@@ -74,23 +74,28 @@ static int handle_primary_tcp_pkt(NetFilterState *nf,
trace_colo_filter_rewriter_conn_offset(conn->offset);
}
+ if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN)) &&
+ conn->tcp_state == TCPS_SYN_SENT) {
+ conn->tcp_state = TCPS_ESTABLISHED;
+ }
+
if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
/*
* we use this flag update offset func
* run once in independent tcp connection
*/
- conn->syn_flag = 1;
+ conn->tcp_state = TCPS_SYN_RECEIVED;
}
if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK)) {
- if (conn->syn_flag) {
+ if (conn->tcp_state == TCPS_SYN_RECEIVED) {
/*
* offset = secondary_seq - primary seq
* ack packet sent by guest from primary node,
* so we use th_ack - 1 get primary_seq
*/
conn->offset -= (ntohl(tcp_pkt->th_ack) - 1);
- conn->syn_flag = 0;
+ conn->tcp_state = TCPS_ESTABLISHED;
}
if (conn->offset) {
/* handle packets to the secondary from the primary */
@@ -99,15 +104,66 @@ static int handle_primary_tcp_pkt(NetFilterState *nf,
net_checksum_calculate((uint8_t *)pkt->data + pkt->vnet_hdr_len,
pkt->size - pkt->vnet_hdr_len);
}
+
+ /*
+ * Passive close step 3
+ */
+ if ((conn->tcp_state == TCPS_LAST_ACK) &&
+ (ntohl(tcp_pkt->th_ack) == (conn->fin_ack_seq + 1))) {
+ conn->tcp_state = TCPS_CLOSED;
+ g_hash_table_remove(rf->connection_track_table, key);
+ }
+ }
+
+ if ((tcp_pkt->th_flags & TH_FIN) == TH_FIN) {
+ /*
+ * Passive close.
+ * Step 1:
+ * The *server* side of this connect is VM, *client* tries to close
+ * the connection. We will into CLOSE_WAIT status.
+ *
+ * Step 2:
+ * In this step we will into LAST_ACK status.
+ *
+ * We got 'fin=1, ack=1' packet from server side, we need to
+ * record the seq of 'fin=1, ack=1' packet.
+ *
+ * Step 3:
+ * We got 'ack=1' packets from client side, it acks 'fin=1, ack=1'
+ * packet from server side. From this point, we can ensure that there
+ * will be no packets in the connection, except that, some errors
+ * happen between the path of 'filter object' and vNIC, if this rare
+ * case really happen, we can still create a new connection,
+ * So it is safe to remove the connection from connection_track_table.
+ *
+ */
+ if (conn->tcp_state == TCPS_ESTABLISHED) {
+ conn->tcp_state = TCPS_CLOSE_WAIT;
+ }
+
+ /*
+ * Active close step 2.
+ */
+ if (conn->tcp_state == TCPS_FIN_WAIT_1) {
+ conn->tcp_state = TCPS_TIME_WAIT;
+ /*
+ * For simplify implementation, we needn't wait 2MSL time
+ * in filter rewriter. Because guest kernel will track the
+ * TCP status and wait 2MSL time, if client resend the FIN
+ * packet, guest will apply the last ACK too.
+ */
+ conn->tcp_state = TCPS_CLOSED;
+ g_hash_table_remove(rf->connection_track_table, key);
+ }
}
return 0;
}
/* handle tcp packet from secondary guest */
-static int handle_secondary_tcp_pkt(NetFilterState *nf,
+static int handle_secondary_tcp_pkt(RewriterState *rf,
Connection *conn,
- Packet *pkt)
+ Packet *pkt, ConnectionKey *key)
{
struct tcphdr *tcp_pkt;
@@ -121,7 +177,8 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf,
trace_colo_filter_rewriter_conn_offset(conn->offset);
}
- if (((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
+ if (conn->tcp_state == TCPS_SYN_RECEIVED &&
+ ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == (TH_ACK | TH_SYN))) {
/*
* save offset = secondary_seq and then
* in handle_primary_tcp_pkt make offset
@@ -130,6 +187,12 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf,
conn->offset = ntohl(tcp_pkt->th_seq);
}
+ /* VM active connect */
+ if (conn->tcp_state == TCPS_CLOSED &&
+ ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_SYN)) {
+ conn->tcp_state = TCPS_SYN_SENT;
+ }
+
if ((tcp_pkt->th_flags & (TH_ACK | TH_SYN)) == TH_ACK) {
/* Only need to adjust seq while offset is Non-zero */
if (conn->offset) {
@@ -141,6 +204,32 @@ static int handle_secondary_tcp_pkt(NetFilterState *nf,
}
}
+ /*
+ * Passive close step 2:
+ */
+ if (conn->tcp_state == TCPS_CLOSE_WAIT &&
+ (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == (TH_ACK | TH_FIN)) {
+ conn->fin_ack_seq = ntohl(tcp_pkt->th_seq);
+ conn->tcp_state = TCPS_LAST_ACK;
+ }
+
+ /*
+ * Active close
+ *
+ * Step 1:
+ * The *server* side of this connect is VM, *server* tries to close
+ * the connection.
+ *
+ * Step 2:
+ * We will into CLOSE_WAIT status.
+ * We simplify the TCPS_FIN_WAIT_2, TCPS_TIME_WAIT and
+ * CLOSING status.
+ */
+ if (conn->tcp_state == TCPS_ESTABLISHED &&
+ (tcp_pkt->th_flags & (TH_ACK | TH_FIN)) == TH_FIN) {
+ conn->tcp_state = TCPS_FIN_WAIT_1;
+ }
+
return 0;
}
@@ -190,7 +279,7 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
if (sender == nf->netdev) {
/* NET_FILTER_DIRECTION_TX */
- if (!handle_primary_tcp_pkt(nf, conn, pkt)) {
+ if (!handle_primary_tcp_pkt(s, conn, pkt, &key)) {
qemu_net_queue_send(s->incoming_queue, sender, 0,
(const uint8_t *)pkt->data, pkt->size, NULL);
packet_destroy(pkt, NULL);
@@ -203,7 +292,7 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
}
} else {
/* NET_FILTER_DIRECTION_RX */
- if (!handle_secondary_tcp_pkt(nf, conn, pkt)) {
+ if (!handle_secondary_tcp_pkt(s, conn, pkt, &key)) {
qemu_net_queue_send(s->incoming_queue, sender, 0,
(const uint8_t *)pkt->data, pkt->size, NULL);
packet_destroy(pkt, NULL);
--
2.17.1
- [Qemu-devel] [PULL 13/25] savevm: split the process of different stages for loadvm/savevm, (continued)
- [Qemu-devel] [PULL 13/25] savevm: split the process of different stages for loadvm/savevm, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 15/25] filter: Add handle_event method for NetFilterClass, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 11/25] qapi/migration.json: Rename COLO unknown mode to none mode., Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 05/25] COLO: Add block replication into colo process, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 07/25] COLO: Load dirty pages into SVM's RAM cache firstly, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 16/25] filter-rewriter: handle checkpoint and failover event, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 12/25] qapi: Add new command to query colo status, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 10/25] qmp event: Add COLO_EXIT event to notify users while exited COLO, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 09/25] COLO: Flush memory data from ram cache, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 08/25] ram/COLO: Record the dirty pages that SVM received, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 01/25] filter-rewriter: Add TCP state machine and fix memory leak in connection_track_table,
Jason Wang <=
- [Qemu-devel] [PULL 04/25] COLO: integrate colo compare with colo frame, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 03/25] colo-compare: use notifier to notify packets comparing result, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 02/25] colo-compare: implement the process of checkpoint, Jason Wang, 2018/09/25
- [Qemu-devel] [PULL 06/25] COLO: Remove colo_state migration struct, Jason Wang, 2018/09/25