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upstream: Explicitly check for and start time-based rekeying in the 

client and server mainloops.

Previously the rekey timeout could expire but rekeying would not start
until a packet was sent or received. This could cause us to spin in
select() on the rekey timeout if the connection was quiet.

ok markus@

OpenBSD-Commit-ID: 4356cf50d7900f3df0a8f2117d9e07c91b9ff987
This commit is contained in:
djm@openbsd.org 2021-07-16 09:00:23 +00:00 committed by Damien Miller
parent ef7c4e52d5
commit 073f45c236
4 changed files with 24 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
clientloop.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: clientloop.c,v 1.366 2021/07/13 23:48:36 djm Exp $ */
/* $OpenBSD: clientloop.c,v 1.367 2021/07/16 09:00:23 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -1358,6 +1358,10 @@ client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
if (quit_pending)
break;
/* A timeout may have triggered rekeying */
if ((r = ssh_packet_check_rekey(ssh)) != 0)
fatal_fr(r, "cannot start rekeying");
/*
* Send as much buffered packet data as possible to the
* sender.

19
packet.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: packet.c,v 1.300 2021/04/03 06:18:40 djm Exp $ */
/* $OpenBSD: packet.c,v 1.301 2021/07/16 09:00:23 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -1002,6 +1002,15 @@ ssh_packet_need_rekeying(struct ssh *ssh, u_int outbound_packet_len)
(state->p_read.blocks > state->max_blocks_in));
}
int
ssh_packet_check_rekey(struct ssh *ssh)
{
if (!ssh_packet_need_rekeying(ssh, 0))
return 0;
debug3_f("rekex triggered");
return kex_start_rekex(ssh);
}
/*
* Delayed compression for SSH2 is enabled after authentication:
* This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
@ -1695,12 +1704,8 @@ ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
/* reset for next packet */
state->packlen = 0;
/* do we need to rekey? */
if (ssh_packet_need_rekeying(ssh, 0)) {
debug3_f("rekex triggered");
if ((r = kex_start_rekex(ssh)) != 0)
return r;
}
if ((r = ssh_packet_check_rekey(ssh)) != 0)
return r;
out:
return r;
}

3
packet.h
View File

@ -1,4 +1,4 @@
/* $OpenBSD: packet.h,v 1.92 2020/03/06 18:11:10 markus Exp $ */
/* $OpenBSD: packet.h,v 1.93 2021/07/16 09:00:23 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
@ -105,6 +105,7 @@ void ssh_packet_clear_keys(struct ssh *);
void ssh_clear_newkeys(struct ssh *, int);
int ssh_packet_is_rekeying(struct ssh *);
int ssh_packet_check_rekey(struct ssh *);
void ssh_packet_set_protocol_flags(struct ssh *, u_int);
u_int ssh_packet_get_protocol_flags(struct ssh *);
void ssh_packet_set_tos(struct ssh *, int);

7
serverloop.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: serverloop.c,v 1.227 2021/06/25 03:38:17 dtucker Exp $ */
/* $OpenBSD: serverloop.c,v 1.228 2021/07/16 09:00:23 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -334,7 +334,7 @@ void
server_loop2(struct ssh *ssh, Authctxt *authctxt)
{
fd_set *readset = NULL, *writeset = NULL;
int max_fd;
int r, max_fd;
u_int nalloc = 0, connection_in, connection_out;
u_int64_t rekey_timeout_ms = 0;
sigset_t bsigset, osigset;
@ -396,6 +396,9 @@ server_loop2(struct ssh *ssh, Authctxt *authctxt)
channel_after_select(ssh, readset, writeset);
if (process_input(ssh, readset, connection_in) < 0)
break;
/* A timeout may have triggered rekeying */
if ((r = ssh_packet_check_rekey(ssh)) != 0)
fatal_fr(r, "cannot start rekeying");
process_output(ssh, writeset, connection_out);
}
collect_children(ssh);