[v2] char: don't skip client cleanup if 'connected' flag is unset

[Qemu-devel] [PATCH v2] char: don't skip client cleanup if 'connected' flag is unset

Posted by Daniel P. Berrange 6 years, 6 months ago

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 <berrange@redhat.com>
---

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(-)

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index e65148fe97..53eda8ef00 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -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

Re: [Qemu-devel] [PATCH v2] char: don't skip client cleanup if 'connected' flag is unset

Posted by Eric Blake 6 years, 6 months ago

On 10/05/2017 10:50 AM, Daniel P. Berrange wrote:
> 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 <berrange@redhat.com>
> ---
> 
> Changed in v2:
> 
>  - Remove conditional checks for NULL (Marc-André)
>  - Don't use camelCase variable name (Marc-André)

Reviewed-by: Eric Blake <eblake@redhat.com>

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

Re: [Qemu-devel] [PATCH v2] char: don't skip client cleanup if 'connected' flag is unset

Posted by Marc-André Lureau 6 years, 6 months ago

On Thu, Oct 5, 2017 at 5:50 PM, Daniel P. Berrange <berrange@redhat.com> wrote:
> 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 <berrange@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


> ---
>
> 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(-)
>
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index e65148fe97..53eda8ef00 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -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
>
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v2] char: don't skip client cleanup if 'connected' flag is unset

Posted by Paolo Bonzini 6 years, 6 months ago

On 05/10/2017 17:50, Daniel P. Berrange wrote:
> 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 <berrange@redhat.com>
> ---
> 
> 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(-)
> 
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index e65148fe97..53eda8ef00 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -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);
>      }
> 

Queued, thanks.

Paolo