char: don't skip client cleanup if 'connected' flag is unset

PATCH Applied Daniel P. Berrange 4 participants 4 messages Oct 5, 2017 – Oct 10, 2017

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Daniel P. Berrange

author

2017-10-05 15:51 UTC #0 lore raw

PATCH v2 1/1 char: don't skip client cleanup if 'connected' flag is unset

The tcp_chr_free_connection & tcp_chr_disconnect methods both skip all of their cleanup work unless the 's->connected' flag is set. This flag is set when the incoming client connection is ready to use. Crucially this is *after* the TLS handshake has been completed. So if the TLS handshake fails and we try to cleanup the failed client, all the cleanup is skipped as 's->connected' is still false.

The only important thing that should be skipped in this case is sending of the CHR_EVENT_CLOSED, because we never got as far as sending the corresponding CHR_EVENT_OPENED. Every other bit of cleanup can be robust against being called even when s->connected is false.

Signed-off-by Daniel P. Berrange <[email protected]>

---

Changed in v2:

- Remove conditional checks for NULL (Marc-André)
- Don't use camelCase variable name (Marc-André)

 chardev/char-socket.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

chardev/char-socket.c +9 ~~-10~~

index e65148fe97..53eda8ef00 100644
@@ -332,10 +332,6 @@ static void tcp_chr_free_connection(Chardev *chr)
     SocketChardev *s = SOCKET_CHARDEV(chr);
     int i;
 
-    if (!s->connected) {
-        return;
-    }
-
     if (s->read_msgfds_num) {
         for (i = 0; i < s->read_msgfds_num; i++) {
             close(s->read_msgfds[i]);

@@ -394,22 +390,25 @@ static void update_disconnected_filename(SocketChardev *s)
                                          s->is_listen, s->is_telnet);
 }
 
+/* NB may be called even if tcp_chr_connect has not been
+ * reached, due to TLS or telnet initialization failure,
+ * so can *not* assume s->connected == true
+ */
 static void tcp_chr_disconnect(Chardev *chr)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);
-
-    if (!s->connected) {
-        return;
-    }
+    bool emit_close = s->connected;
 
     tcp_chr_free_connection(chr);
 
-    if (s->listen_ioc) {
+    if (s->listen_ioc && s->listen_tag == 0) {
         s->listen_tag = qio_channel_add_watch(
             QIO_CHANNEL(s->listen_ioc), G_IO_IN, tcp_chr_accept, chr, NULL);
     }
     update_disconnected_filename(s);
-    qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    if (emit_close) {
+        qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    }
     if (s->reconnect_time) {
         qemu_chr_socket_restart_timer(chr);
     }

Signature · 1 line

2.13.5

Eric Blake

Reviewed-by on v2 1/1

2017-10-05 15:55 UTC #1 lore raw

Quoted 14 lines · Daniel P. Berrange

The tcp_chr_free_connection & tcp_chr_disconnect methods both skip all of their cleanup work unless the 's->connected' flag is set. This flag is set when the incoming client connection is ready to use. Crucially this is *after* the TLS handshake has been completed. So if the TLS handshake fails and we try to cleanup the failed client, all the cleanup is skipped as 's->connected' is still false.
The only important thing that should be skipped in this case is sending of the CHR_EVENT_CLOSED, because we never got as far as sending the corresponding CHR_EVENT_OPENED. Every other bit of cleanup can be robust against being called even when s->connected is false.

Quoted 7 lines

Signed-off-by Daniel P. Berrange <[email protected]>
---
Changed in v2:
- Remove conditional checks for NULL (Marc-André)
- Don't use camelCase variable name (Marc-André)

Reviewed-by Eric Blake <[email protected]>

Signature · 3 lines

Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Marc-André Lureau

Reviewed-by on v2 1/1

2017-10-05 16:00 UTC #2 lore raw

In reply to Daniel P. Berrange

Quoted 8 lines · Daniel P. Berrange

The tcp_chr_free_connection & tcp_chr_disconnect methods both skip all of their cleanup work unless the 's->connected' flag is set. This flag is set when the incoming client connection is ready to use. Crucially this is *after* the TLS handshake has been completed. So if the TLS handshake fails and we try to cleanup the failed client, all the cleanup is skipped as 's->connected' is still false.

Quoted 7 lines

The only important thing that should be skipped in this case is sending of the CHR_EVENT_CLOSED, because we never got as far as sending the corresponding CHR_EVENT_OPENED. Every other bit of cleanup can be robust against being called even when s->connected is false.
Signed-off-by Daniel P. Berrange <[email protected]>

Reviewed-by Marc-André Lureau <[email protected]>

Quoted 61 lines

---

Changed in v2:

- Remove conditional checks for NULL (Marc-André)
- Don't use camelCase variable name (Marc-André)

 chardev/char-socket.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

chardev/char-socket.c +9 ~~-11~~

index e65148fe97..53eda8ef00 100644
@@ -332,10 +332,6 @@ static void tcp_chr_free_connection(Chardev *chr)
     SocketChardev *s = SOCKET_CHARDEV(chr);
     int i;
 
-    if (!s->connected) {
-        return;
-    }
-
     if (s->read_msgfds_num) {
         for (i = 0; i < s->read_msgfds_num; i++) {
             close(s->read_msgfds[i]);

@@ -394,22 +390,25 @@ static void update_disconnected_filename(SocketChardev *s)
                                          s->is_listen, s->is_telnet);
 }
 
+/* NB may be called even if tcp_chr_connect has not been
+ * reached, due to TLS or telnet initialization failure,
+ * so can *not* assume s->connected == true
+ */
 static void tcp_chr_disconnect(Chardev *chr)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);
-
-    if (!s->connected) {
-        return;
-    }
+    bool emit_close = s->connected;
 
     tcp_chr_free_connection(chr);
 
-    if (s->listen_ioc) {
+    if (s->listen_ioc && s->listen_tag == 0) {
         s->listen_tag = qio_channel_add_watch(
             QIO_CHANNEL(s->listen_ioc), G_IO_IN, tcp_chr_accept, chr, NULL);
     }
     update_disconnected_filename(s);
-    qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    if (emit_close) {
+        qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    }
     if (s->reconnect_time) {
         qemu_chr_socket_restart_timer(chr);
     }
--

2.13.5

Signature · 1 line

Marc-André Lureau

Paolo Bonzini

Applied

2017-10-10 10:19 UTC #3 lore raw

In reply to Daniel P. Berrange

Quoted 63 lines · Daniel P. Berrange

The tcp_chr_free_connection & tcp_chr_disconnect methods both skip all of their cleanup work unless the 's->connected' flag is set. This flag is set when the incoming client connection is ready to use. Crucially this is *after* the TLS handshake has been completed. So if the TLS handshake fails and we try to cleanup the failed client, all the cleanup is skipped as 's->connected' is still false.
The only important thing that should be skipped in this case is sending of the CHR_EVENT_CLOSED, because we never got as far as sending the corresponding CHR_EVENT_OPENED. Every other bit of cleanup can be robust against being called even when s->connected is false.
Signed-off-by Daniel P. Berrange <[email protected]>
---
Changed in v2:
- Remove conditional checks for NULL (Marc-André)
- Don't use camelCase variable name (Marc-André)
 chardev/char-socket.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)
chardev/char-socket.c +6 -9
index e65148fe97..53eda8ef00 100644
@@ -332,10 +332,6 @@ static void tcp_chr_free_connection(Chardev *chr)
     SocketChardev *s = SOCKET_CHARDEV(chr);
     int i;
 
-    if (!s->connected) {
-        return;
-    }
-
     if (s->read_msgfds_num) {
         for (i = 0; i < s->read_msgfds_num; i++) {
             close(s->read_msgfds[i]);
@@ -394,22 +390,25 @@ static void update_disconnected_filename(SocketChardev *s)
                                          s->is_listen, s->is_telnet);
 }
 
+/* NB may be called even if tcp_chr_connect has not been
+ * reached, due to TLS or telnet initialization failure,
+ * so can *not* assume s->connected == true
+ */
 static void tcp_chr_disconnect(Chardev *chr)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);
-
-    if (!s->connected) {
-        return;
-    }
+    bool emit_close = s->connected;
 
     tcp_chr_free_connection(chr);
 
-    if (s->listen_ioc) {
+    if (s->listen_ioc && s->listen_tag == 0) {
         s->listen_tag = qio_channel_add_watch(

chardev/char-socket.c static void update_disconnected_filename(SocketChardev *s) · line 414

Quoted 10 lines

chardev/char-socket.c +3 -1

             QIO_CHANNEL(s->listen_ioc), G_IO_IN, tcp_chr_accept, chr, NULL);
     }
     update_disconnected_filename(s);
-    qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    if (emit_close) {
+        qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    }
     if (s->reconnect_time) {
         qemu_chr_socket_restart_timer(chr);
     }

Queued, thanks.

Paolo