From d1885e549d16103f57df5306f3dd53c626a10d05 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Mon, 11 Feb 2019 18:24:39 +0000 Subject: [PATCH] chardev: disallow TLS/telnet/websocket with tcp_chr_wait_connected MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit In the previous commit commit 1dc8a6695c731abb7461c637b2512c3670d82be4 Author: Marc-André Lureau 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. Reviewed-by: Marc-André Lureau Signed-off-by: Daniel P. Berrangé Message-Id: <20190211182442.8542-14-berrange@redhat.com> Signed-off-by: Marc-André Lureau --- 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 7db20ff0a0..86c1f502d6 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 completion", opts[i]); + return -1; + } + } + while (!s->ioc) { if (s->is_listen) { tcp_chr_accept_server_sync(chr); -- 2.11.4.GIT