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upstream: make channel_output_poll() return a flag indicating 

whether channel data was enqueued. Will be used to improve keystroke timing
obfuscation. Problem spotted by / tested by naddy@

OpenBSD-Commit-ID: f9776c7b0065ba7c3bbe50431fd3b629f44314d0
This commit is contained in:
djm@openbsd.org 2023-09-04 00:01:46 +00:00 committed by Damien Miller
parent 43254b326a
commit ccf7d913db
No known key found for this signature in database
2 changed files with 24 additions and 15 deletions
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35
channels.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: channels.c,v 1.432 2023/07/04 03:59:21 dlg Exp $ */ /* $OpenBSD: channels.c,v 1.433 2023/09/04 00:01:46 djm Exp $ */
/* /*
* Author: Tatu Ylonen <ylo@cs.hut.fi> * Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -2890,8 +2890,9 @@ channel_after_poll(struct ssh *ssh, struct pollfd *pfd, u_int npfd)
/* /*
* Enqueue data for channels with open or draining c->input. * Enqueue data for channels with open or draining c->input.
* Returns non-zero if a packet was enqueued.
*/ */
static void static int
channel_output_poll_input_open(struct ssh *ssh, Channel *c) channel_output_poll_input_open(struct ssh *ssh, Channel *c)
{ {
size_t len, plen; size_t len, plen;
@ -2914,7 +2915,7 @@ channel_output_poll_input_open(struct ssh *ssh, Channel *c)
else else
chan_ibuf_empty(ssh, c); chan_ibuf_empty(ssh, c);
} }
return; return 0;
} }
if (!c->have_remote_id) if (!c->have_remote_id)
@ -2931,7 +2932,7 @@ channel_output_poll_input_open(struct ssh *ssh, Channel *c)
*/ */
if (plen > c->remote_window || plen > c->remote_maxpacket) { if (plen > c->remote_window || plen > c->remote_maxpacket) {
debug("channel %d: datagram too big", c->self); debug("channel %d: datagram too big", c->self);
return; return 0;
} }
/* Enqueue it */ /* Enqueue it */
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 || if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
@ -2940,7 +2941,7 @@ channel_output_poll_input_open(struct ssh *ssh, Channel *c)
(r = sshpkt_send(ssh)) != 0) (r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "channel %i: send datagram", c->self); fatal_fr(r, "channel %i: send datagram", c->self);
c->remote_window -= plen; c->remote_window -= plen;
return; return 1;
} }
/* Enqueue packet for buffered data. */ /* Enqueue packet for buffered data. */
@ -2949,7 +2950,7 @@ channel_output_poll_input_open(struct ssh *ssh, Channel *c)
if (len > c->remote_maxpacket) if (len > c->remote_maxpacket)
len = c->remote_maxpacket; len = c->remote_maxpacket;
if (len == 0) if (len == 0)
return; return 0;
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 || if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_string(ssh, sshbuf_ptr(c->input), len)) != 0 || (r = sshpkt_put_string(ssh, sshbuf_ptr(c->input), len)) != 0 ||
@ -2958,19 +2959,21 @@ channel_output_poll_input_open(struct ssh *ssh, Channel *c)
if ((r = sshbuf_consume(c->input, len)) != 0) if ((r = sshbuf_consume(c->input, len)) != 0)
fatal_fr(r, "channel %i: consume", c->self); fatal_fr(r, "channel %i: consume", c->self);
c->remote_window -= len; c->remote_window -= len;
return 1;
} }
/* /*
* Enqueue data for channels with open c->extended in read mode. * Enqueue data for channels with open c->extended in read mode.
* Returns non-zero if a packet was enqueued.
*/ */
static void static int
channel_output_poll_extended_read(struct ssh *ssh, Channel *c) channel_output_poll_extended_read(struct ssh *ssh, Channel *c)
{ {
size_t len; size_t len;
int r; int r;
if ((len = sshbuf_len(c->extended)) == 0) if ((len = sshbuf_len(c->extended)) == 0)
return; return 0;
debug2("channel %d: rwin %u elen %zu euse %d", c->self, debug2("channel %d: rwin %u elen %zu euse %d", c->self,
c->remote_window, sshbuf_len(c->extended), c->extended_usage); c->remote_window, sshbuf_len(c->extended), c->extended_usage);
@ -2979,7 +2982,7 @@ channel_output_poll_extended_read(struct ssh *ssh, Channel *c)
if (len > c->remote_maxpacket) if (len > c->remote_maxpacket)
len = c->remote_maxpacket; len = c->remote_maxpacket;
if (len == 0) if (len == 0)
return; return 0;
if (!c->have_remote_id) if (!c->have_remote_id)
fatal_f("channel %d: no remote id", c->self); fatal_f("channel %d: no remote id", c->self);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA)) != 0 || if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA)) != 0 ||
@ -2992,15 +2995,20 @@ channel_output_poll_extended_read(struct ssh *ssh, Channel *c)
fatal_fr(r, "channel %i: consume", c->self); fatal_fr(r, "channel %i: consume", c->self);
c->remote_window -= len; c->remote_window -= len;
debug2("channel %d: sent ext data %zu", c->self, len); debug2("channel %d: sent ext data %zu", c->self, len);
return 1;
} }
/* If there is data to send to the connection, enqueue some of it now. */ /*
void * If there is data to send to the connection, enqueue some of it now.
* Returns non-zero if data was enqueued.
*/
int
channel_output_poll(struct ssh *ssh) channel_output_poll(struct ssh *ssh)
{ {
struct ssh_channels *sc = ssh->chanctxt; struct ssh_channels *sc = ssh->chanctxt;
Channel *c; Channel *c;
u_int i; u_int i;
int ret = 0;
for (i = 0; i < sc->channels_alloc; i++) { for (i = 0; i < sc->channels_alloc; i++) {
c = sc->channels[i]; c = sc->channels[i];
@ -3023,12 +3031,13 @@ channel_output_poll(struct ssh *ssh)
/* Get the amount of buffered data for this channel. */ /* Get the amount of buffered data for this channel. */
if (c->istate == CHAN_INPUT_OPEN || if (c->istate == CHAN_INPUT_OPEN ||
c->istate == CHAN_INPUT_WAIT_DRAIN) c->istate == CHAN_INPUT_WAIT_DRAIN)
channel_output_poll_input_open(ssh, c); ret |= channel_output_poll_input_open(ssh, c);
/* Send extended data, i.e. stderr */ /* Send extended data, i.e. stderr */
if (!(c->flags & CHAN_EOF_SENT) && if (!(c->flags & CHAN_EOF_SENT) &&
c->extended_usage == CHAN_EXTENDED_READ) c->extended_usage == CHAN_EXTENDED_READ)
channel_output_poll_extended_read(ssh, c); ret |= channel_output_poll_extended_read(ssh, c);
} }
return ret;
} }
/* -- mux proxy support */ /* -- mux proxy support */

4
channels.h
View File

@ -1,4 +1,4 @@
/* $OpenBSD: channels.h,v 1.151 2023/07/04 03:59:21 dlg Exp $ */ /* $OpenBSD: channels.h,v 1.152 2023/09/04 00:01:46 djm Exp $ */
/* /*
* Author: Tatu Ylonen <ylo@cs.hut.fi> * Author: Tatu Ylonen <ylo@cs.hut.fi>
@ -335,7 +335,7 @@ struct timespec;
void channel_prepare_poll(struct ssh *, struct pollfd **, void channel_prepare_poll(struct ssh *, struct pollfd **,
u_int *, u_int *, u_int, struct timespec *); u_int *, u_int *, u_int, struct timespec *);
void channel_after_poll(struct ssh *, struct pollfd *, u_int); void channel_after_poll(struct ssh *, struct pollfd *, u_int);
void channel_output_poll(struct ssh *); int channel_output_poll(struct ssh *);
int channel_not_very_much_buffered_data(struct ssh *); int channel_not_very_much_buffered_data(struct ssh *);
void channel_close_all(struct ssh *); void channel_close_all(struct ssh *);