upstream: Add channel_force_close()

This will forcibly close an open channel by simulating read/write errors,
draining the IO buffers and calling the detach function.

Previously the detach function was only ever called during channel garbage
collection, but there was no way to signal the user of a channel (e.g.
session.c) that its channel was being closed deliberately (vs. by the
usual state-machine logic). So this adds an extra "force" argument to the
channel cleanup callback to indicate this condition.

ok markus dtucker

OpenBSD-Commit-ID: 23052707a42bdc62fda2508636e624afd466324b

1 files changed, 29 insertions, 14 deletions

diff --git a/channels.c b/channels.c
index 5541e904..84d902bd 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.422 2023/01/06 02:38:23 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.423 2023/01/06 02:39:59 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1222,6 +1222,29 @@ x11_open_helper(struct ssh *ssh, struct sshbuf *b)
 	return 1;
 }
 
+void
+channel_force_close(struct ssh *ssh, Channel *c, int abandon)
+{
+	debug3_f("channel %d: forcibly closing", c->self);
+	if (c->istate == CHAN_INPUT_OPEN)
+		chan_read_failed(ssh, c);
+	if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
+		sshbuf_reset(c->input);
+		chan_ibuf_empty(ssh, c);
+	}
+	if (c->ostate == CHAN_OUTPUT_OPEN ||
+	    c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
+		sshbuf_reset(c->output);
+		chan_write_failed(ssh, c);
+	}
+	if (c->detach_user)
+		c->detach_user(ssh, c->self, 1, NULL);
+	if (c->efd != -1)
+		channel_close_fd(ssh, c, &c->efd);
+	if (abandon)
+		c->type = SSH_CHANNEL_ABANDONED;
+}
+
 static void
 channel_pre_x11_open(struct ssh *ssh, Channel *c)
 {
@@ -1233,15 +1256,11 @@ channel_pre_x11_open(struct ssh *ssh, Channel *c)
 		c->type = SSH_CHANNEL_OPEN;
 		channel_pre_open(ssh, c);
 	} else if (ret == -1) {
-		logit("X11 connection rejected because of wrong authentication.");
+		logit("X11 connection rejected because of wrong "
+		    "authentication.");
 		debug2("X11 rejected %d i%d/o%d",
 		    c->self, c->istate, c->ostate);
-		chan_read_failed(ssh, c);
-		sshbuf_reset(c->input);
-		chan_ibuf_empty(ssh, c);
-		sshbuf_reset(c->output);
-		chan_write_failed(ssh, c);
-		debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
+		channel_force_close(ssh, c, 0);
 	}
 }
 
@@ -1591,11 +1610,7 @@ static void
 rdynamic_close(struct ssh *ssh, Channel *c)
 {
 	c->type = SSH_CHANNEL_OPEN;
-	chan_read_failed(ssh, c);
-	sshbuf_reset(c->input);
-	chan_ibuf_empty(ssh, c);
-	sshbuf_reset(c->output);
-	chan_write_failed(ssh, c);
+	channel_force_close(ssh, c, 0);
 }
 
 /* reverse dynamic port forwarding */
@@ -2395,7 +2410,7 @@ channel_garbage_collect(struct ssh *ssh, Channel *c)
 			return;
 
 		debug2("channel %d: gc: notify user", c->self);
-		c->detach_user(ssh, c->self, NULL);
+		c->detach_user(ssh, c->self, 0, NULL);
 		/* if we still have a callback */
 		if (c->detach_user != NULL)
 			return;