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[Qemu-devel] [PATCH 11/12] chardev: disallow TLS/telnet/websocket with t
From: |
Daniel P . Berrangé |
Subject: |
[Qemu-devel] [PATCH 11/12] chardev: disallow TLS/telnet/websocket with tcp_chr_wait_connected |
Date: |
Tue, 15 Jan 2019 14:52:55 +0000 |
In the previous commit
commit 1dc8a6695c731abb7461c637b2512c3670d82be4
Author: Marc-André Lureau <address@hidden>
Date: Tue Aug 16 12:33:32 2016 +0400
char: fix waiting for TLS and telnet connection
the tcp_chr_wait_connected() method was changed to check for a non-NULL
's->ioc' as a sign that there is already a connection present, as
opposed to checking the "connected" flag to supposedly fix handling of
TLS/telnet connections.
The original code would repeatedly call tcp_chr_wait_connected creating
many connections as 'connected' would never become true. The changed
code would still repeatedly call tcp_chr_wait_connected busy waiting
because s->ioc is set but the chardev will never see CHR_EVENT_OPENED.
IOW, the code is still broken with TLS/telnet, but in a different way.
Checking for a non-NULL 's->ioc' does not mean that a CHR_EVENT_OPENED
will be ready for a TLS/telnet connection. These protocols (and the
websocket protocol) all require the main loop to be running in order
to complete the protocol handshake before emitting CHR_EVENT_OPENED.
The tcp_chr_wait_connected() method is only used during early startup
before a main loop is running, so TLS/telnet/websock connections can
never complete initialization.
Making this work would require changing tcp_chr_wait_connected to run
a main loop. This is quite complex since we must not allow GSource's
that other parts of QEMU have registered to run yet. The current callers
of tcp_chr_wait_connected do not require use of the TLS/telnet/websocket
protocols, so the simplest option is to just forbid this combination
completely for now.
Signed-off-by: Daniel P. Berrangé <address@hidden>
---
chardev/char-socket.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 91d775e9c5..7e98a95bbd 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -951,8 +951,20 @@ static void tcp_chr_accept_server_sync(Chardev *chr)
static int tcp_chr_wait_connected(Chardev *chr, Error **errp)
{
SocketChardev *s = SOCKET_CHARDEV(chr);
- /* It can't wait on s->connected, since it is set asynchronously
- * in TLS and telnet cases, only wait for an accepted socket */
+ const char *opts[] = { "telnet", "tn3270", "websock", "tls-creds" };
+ bool optset[] = { s->is_telnet, s->is_tn3270, s->is_websock, s->tls_creds
};
+ size_t i;
+
+ QEMU_BUILD_BUG_ON(G_N_ELEMENTS(opts) != G_N_ELEMENTS(optset));
+ for (i = 0; i < G_N_ELEMENTS(opts); i++) {
+ if (optset[i]) {
+ error_setg(errp,
+ "'%s' option is incompatible with waiting for "
+ "connection during early startup", opts[i]);
+ return -1;
+ }
+ }
+
while (!s->ioc) {
if (s->is_listen) {
tcp_chr_accept_server_sync(chr);
--
2.20.1
- Re: [Qemu-devel] [PATCH 06/12] chardev: remove unused 'sioc' variable & cleanup paths, (continued)
- [Qemu-devel] [PATCH 07/12] chardev: split tcp_chr_wait_connected into two methods, Daniel P . Berrangé, 2019/01/15
- [Qemu-devel] [PATCH 08/12] chardev: split up qmp_chardev_open_socket connection code, Daniel P . Berrangé, 2019/01/15
- [Qemu-devel] [PATCH 09/12] chardev: use a state machine for socket connection state, Daniel P . Berrangé, 2019/01/15
- [Qemu-devel] [PATCH 10/12] chardev: honour the reconnect setting in tcp_chr_wait_connected, Daniel P . Berrangé, 2019/01/15
- [Qemu-devel] [PATCH 11/12] chardev: disallow TLS/telnet/websocket with tcp_chr_wait_connected,
Daniel P . Berrangé <=
- [Qemu-devel] [PATCH 12/12] chardev: fix race with client connections in tcp_chr_wait_connected, Daniel P . Berrangé, 2019/01/15
- [Qemu-devel] [PATCH 02/12] chardev: forbid 'reconnect' option with server sockets, Daniel P . Berrangé, 2019/01/15
- [Qemu-devel] [PATCH 05/12] chardev: ensure qemu_chr_parse_compat reports missing driver error, Daniel P . Berrangé, 2019/01/15
- [Qemu-devel] [PATCH 01/12] chardev: fix validation of options for QMP created chardevs, Daniel P . Berrangé, 2019/01/15