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Make remote channel ID a u_int

Previously we tracked the remote channel IDs in an int, but this is
strictly incorrect: the wire protocol uses uint32 and there is nothing
in-principle stopping a SSH implementation from sending, say, 0xffff0000.

In practice everyone numbers their channels sequentially, so this has
never been a problem.

ok markus@

Upstream-ID: b9f4cd3dc53155b4a5c995c0adba7da760d03e73
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@djmdjm
djmdjm committed Sep 12, 2017
1 parent dbee411 commit 9f53229
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Showing 6 changed files with 65 additions and 24 deletions.
40 channels.c
View file
@@ -1,4 +1,4 @@
/* $OpenBSD: channels.c,v 1.366 2017/08/30 03:59:08 djm Exp $ */
/* $OpenBSD: channels.c,v 1.368 2017/09/12 06:35:31 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -252,14 +252,14 @@ channel_by_id(struct ssh *ssh, int id)
}

Channel *
channel_by_remote_id(struct ssh *ssh, int remote_id)
channel_by_remote_id(struct ssh *ssh, u_int remote_id)
{
Channel *c;
u_int i;

for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->channels[i];
if (c != NULL && c->remote_id == remote_id)
if (c != NULL && c->have_remote_id && c->remote_id == remote_id)
return c;
}
return NULL;
@@ -387,7 +387,6 @@ channel_new(struct ssh *ssh, char *ctype, int type, int rfd, int wfd, int efd,
c->local_window = window;
c->local_window_max = window;
c->local_maxpacket = maxpack;
c->remote_id = -1;
c->remote_name = xstrdup(remote_name);
c->ctl_chan = -1;
c->delayed = 1; /* prevent call to channel_post handler */
@@ -703,7 +702,7 @@ channel_find_open(struct ssh *ssh)

for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->channels[i];
if (c == NULL || c->remote_id < 0)
if (c == NULL || !c->have_remote_id)
continue;
switch (c->type) {
case SSH_CHANNEL_CLOSED:
@@ -778,9 +777,10 @@ channel_open_message(struct ssh *ssh)
case SSH_CHANNEL_MUX_PROXY:
case SSH_CHANNEL_MUX_CLIENT:
if ((r = sshbuf_putf(buf, " #%d %.300s "
"(t%d r%d i%u/%zu o%u/%zu fd %d/%d cc %d)\r\n",
"(t%d %s%u i%u/%zu o%u/%zu fd %d/%d cc %d)\r\n",
c->self, c->remote_name,
c->type, c->remote_id,
c->type,
c->have_remote_id ? "r" : "nr", c->remote_id,
c->istate, sshbuf_len(c->input),
c->ostate, sshbuf_len(c->output),
c->rfd, c->wfd, c->ctl_chan)) != 0)
@@ -838,6 +838,9 @@ channel_request_start(struct ssh *ssh, int id, char *service, int wantconfirm)
logit("%s: %d: unknown channel id", __func__, id);
return;
}
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);

debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
@@ -930,6 +933,9 @@ channel_set_fds(struct ssh *ssh, int id, int rfd, int wfd, int efd,

if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
fatal("channel_activate for non-larval channel %d.", id);
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);

channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, is_tty);
c->type = SSH_CHANNEL_OPEN;
c->local_window = c->local_window_max = window_max;
@@ -1698,6 +1704,8 @@ channel_post_connecting(struct ssh *ssh, Channel *c,

if (!FD_ISSET(c->sock, writeset))
return;
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);

if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
err = errno;
@@ -1983,6 +1991,9 @@ channel_check_window(struct ssh *ssh, Channel *c)
c->local_maxpacket*3) ||
c->local_window < c->local_window_max/2) &&
c->local_consumed > 0) {
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id",
__func__, c->self);
if ((r = sshpkt_start(ssh,
SSH2_MSG_CHANNEL_WINDOW_ADJUST)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
@@ -2338,6 +2349,9 @@ channel_output_poll_input_open(struct ssh *ssh, Channel *c)
return;
}

if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);

if (c->datagram) {
/* Check datagram will fit; drop if not */
if ((r = sshbuf_peek_string_direct(c->input, NULL, &dlen)) != 0)
@@ -2404,6 +2418,8 @@ channel_output_poll_extended_read(struct ssh *ssh, Channel *c)
len = c->remote_maxpacket;
if (len == 0)
return;
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh, SSH2_EXTENDED_DATA_STDERR)) != 0 ||
@@ -2570,6 +2586,7 @@ channel_proxy_downstream(struct ssh *ssh, Channel *downstream)
c->mux_ctx = downstream; /* point to mux client */
c->mux_downstream_id = id;
c->remote_id = remote_id;
c->have_remote_id = 1;
if ((r = sshbuf_put_u32(modified, remote_id)) != 0 ||
(r = sshbuf_put_u32(modified, c->self)) != 0 ||
(r = sshbuf_putb(modified, original)) != 0) {
@@ -2713,8 +2730,10 @@ channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh)
switch (type) {
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
/* record remote_id for SSH2_MSG_CHANNEL_CLOSE */
if (cp && len > 4)
if (cp && len > 4) {
c->remote_id = PEEK_U32(cp);
c->have_remote_id = 1;
}
break;
case SSH2_MSG_CHANNEL_CLOSE:
if (c->flags & CHAN_CLOSE_SENT)
@@ -2923,14 +2942,15 @@ channel_input_open_confirmation(int type, u_int32_t seq, struct ssh *ssh)
* Record the remote channel number and mark that the channel
* is now open.
*/
c->remote_id = channel_parse_id(ssh, __func__, "open confirmation");
if ((r = sshpkt_get_u32(ssh, &remote_window)) != 0 ||
if ((r = sshpkt_get_u32(ssh, &c->remote_id)) != 0 ||
(r = sshpkt_get_u32(ssh, &remote_window)) != 0 ||
(r = sshpkt_get_u32(ssh, &remote_maxpacket)) != 0) {
error("%s: window/maxpacket: %s", __func__, ssh_err(r));
packet_disconnect("Invalid open confirmation message");
}
ssh_packet_check_eom(ssh);

c->have_remote_id = 1;
c->remote_window = remote_window;
c->remote_maxpacket = remote_maxpacket;
c->type = SSH_CHANNEL_OPEN;
9 channels.h
View file
@@ -1,4 +1,4 @@
/* $OpenBSD: channels.h,v 1.128 2017/09/12 06:32:07 djm Exp $ */
/* $OpenBSD: channels.h,v 1.129 2017/09/12 06:35:32 djm Exp $ */

/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -97,8 +97,9 @@ typedef int mux_callback_fn(struct ssh *, struct Channel *);
struct Channel {
int type; /* channel type/state */
int self; /* my own channel identifier */
int remote_id; /* channel identifier for remote peer */
/* XXX should be uint32_t */
uint32_t remote_id; /* channel identifier for remote peer */
int have_remote_id; /* non-zero if remote_id is valid */

u_int istate; /* input from channel (state of receive half) */
u_int ostate; /* output to channel (state of transmit half) */
int flags; /* close sent/rcvd */
@@ -222,7 +223,7 @@ void channel_init_channels(struct ssh *ssh);
/* channel management */

Channel *channel_by_id(struct ssh *, int);
Channel *channel_by_remote_id(struct ssh *, int);
Channel *channel_by_remote_id(struct ssh *, u_int);
Channel *channel_lookup(struct ssh *, int);
Channel *channel_new(struct ssh *, char *, int, int, int, int,
u_int, u_int, int, char *, int);
6 clientloop.c
View file
@@ -1,4 +1,4 @@
/* $OpenBSD: clientloop.c,v 1.303 2017/09/12 06:32:07 djm Exp $ */
/* $OpenBSD: clientloop.c,v 1.304 2017/09/12 06:35:32 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1682,6 +1682,7 @@ client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
} else if (c != NULL) {
debug("confirm %s", ctype);
c->remote_id = rchan;
c->have_remote_id = 1;
c->remote_window = rwindow;
c->remote_maxpacket = rmaxpack;
if (c->type != SSH_CHANNEL_CONNECTING) {
@@ -1749,6 +1750,9 @@ client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
packet_check_eom();
}
if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
if (!c->have_remote_id)
fatal("%s: channel %d: no remote_id",
__func__, c->self);
packet_start(success ?
SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
packet_put_int(c->remote_id);
18 mux.c
View file
@@ -1,4 +1,4 @@
/* $OpenBSD: mux.c,v 1.66 2017/09/12 06:32:07 djm Exp $ */
/* $OpenBSD: mux.c,v 1.67 2017/09/12 06:35:32 djm Exp $ */
/*
* Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
*
@@ -215,7 +215,8 @@ mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused)
fatal("%s: channel %d missing control channel %d",
__func__, c->self, c->ctl_chan);
c->ctl_chan = -1;
cc->remote_id = -1;
cc->remote_id = 0;
cc->have_remote_id = 0;
chan_rcvd_oclose(ssh, cc);
}
channel_cancel_cleanup(ssh, c->self);
@@ -231,11 +232,12 @@ mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused)
debug3("%s: entering for channel %d", __func__, cid);
if (c == NULL)
fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
if (c->remote_id != -1) {
if (c->have_remote_id) {
if ((sc = channel_by_id(ssh, c->remote_id)) == NULL)
fatal("%s: channel %d missing session channel %d",
fatal("%s: channel %d missing session channel %u",
__func__, c->self, c->remote_id);
c->remote_id = -1;
c->remote_id = 0;
c->have_remote_id = 0;
sc->ctl_chan = -1;
if (sc->type != SSH_CHANNEL_OPEN &&
sc->type != SSH_CHANNEL_OPENING) {
@@ -413,7 +415,7 @@ process_mux_new_session(struct ssh *ssh, u_int rid,
new_fd[0], new_fd[1], new_fd[2]);

/* XXX support multiple child sessions in future */
if (c->remote_id != -1) {
if (c->have_remote_id) {
debug2("%s: session already open", __func__);
/* prepare reply */
buffer_put_int(r, MUX_S_FAILURE);
@@ -471,6 +473,7 @@ process_mux_new_session(struct ssh *ssh, u_int rid,

nc->ctl_chan = c->self; /* link session -> control channel */
c->remote_id = nc->self; /* link control -> session channel */
c->have_remote_id = 1;

if (cctx->want_tty && escape_char != 0xffffffff) {
channel_register_filter(ssh, nc->self,
@@ -1007,7 +1010,7 @@ process_mux_stdio_fwd(struct ssh *ssh, u_int rid,
new_fd[0], new_fd[1]);

/* XXX support multiple child sessions in future */
if (c->remote_id != -1) {
if (c->have_remote_id) {
debug2("%s: session already open", __func__);
/* prepare reply */
buffer_put_int(r, MUX_S_FAILURE);
@@ -1043,6 +1046,7 @@ process_mux_stdio_fwd(struct ssh *ssh, u_int rid,

nc->ctl_chan = c->self; /* link session -> control channel */
c->remote_id = nc->self; /* link control -> session channel */
c->have_remote_id = 1;

debug2("%s: channel_new: %d linked to control channel %d",
__func__, nc->self, nc->ctl_chan);
10 nchan.c
View file
@@ -1,4 +1,4 @@
/* $OpenBSD: nchan.c,v 1.66 2017/09/12 06:32:07 djm Exp $ */
/* $OpenBSD: nchan.c,v 1.67 2017/09/12 06:35:32 djm Exp $ */
/*
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
*
@@ -183,6 +183,9 @@ chan_send_eof2(struct ssh *ssh, Channel *c)
debug2("channel %d: send eof", c->self);
switch (c->istate) {
case CHAN_INPUT_WAIT_DRAIN:
if (!c->have_remote_id)
fatal("%s: channel %d: no remote_id",
__func__, c->self);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EOF)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
@@ -209,6 +212,9 @@ chan_send_close2(struct ssh *ssh, Channel *c)
} else if (c->flags & CHAN_CLOSE_SENT) {
error("channel %d: already sent close", c->self);
} else {
if (!c->have_remote_id)
fatal("%s: channel %d: no remote_id",
__func__, c->self);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_CLOSE)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
@@ -230,6 +236,8 @@ chan_send_eow2(struct ssh *ssh, Channel *c)
}
if (!(datafellows & SSH_NEW_OPENSSH))
return;
if (!c->have_remote_id)
fatal("%s: channel %d: no remote_id", __func__, c->self);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_cstring(ssh, "eow@openssh.com")) != 0 ||
6 serverloop.c
View file
@@ -1,4 +1,4 @@
/* $OpenBSD: serverloop.c,v 1.197 2017/09/12 06:32:07 djm Exp $ */
/* $OpenBSD: serverloop.c,v 1.198 2017/09/12 06:35:32 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -619,6 +619,7 @@ server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
if (c != NULL) {
debug("server_input_channel_open: confirm %s", ctype);
c->remote_id = rchan;
c->have_remote_id = 1;
c->remote_window = rwindow;
c->remote_maxpacket = rmaxpack;
if (c->type != SSH_CHANNEL_CONNECTING) {
@@ -844,6 +845,9 @@ server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
success = session_input_channel_req(ssh, c, rtype);
if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
if (!c->have_remote_id)
fatal("%s: channel %d: no remote_id",
__func__, c->self);
packet_start(success ?
SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
packet_put_int(c->remote_id);

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