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Allow new_connection to take an optional Seat. (NFC)

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This is working towards allowing the subsidiary SSH connection in an
SshProxy to share the main user-facing Seat, so as to be able to pass
through interactive prompts.

This is more difficult than the similar change with LogPolicy, because
Seats are stateful. In particular, the trust-sigil status will need to
be controlled by the SshProxy until it's ready to pass over control to
the main SSH (or whatever) connection.

To make this work, I've introduced a thing called a TempSeat, which is
(yet) another Seat implementation. When a backend hands its Seat to
new_connection(), it does it in a way that allows new_connection() to
borrow it completely, and replace it in the main backend structure
with a TempSeat, which acts as a temporary placeholder. If the main
backend tries to do things like changing trust status or sending
output, the TempSeat will buffer them; later on, when the connection
is established, TempSeat will replay the changes into the real Seat.

So, in each backend, I've made the following changes:
 - pass &foo->seat to new_connection, which may overwrite it with a
   TempSeat.
 - if it has done so (which we can tell via the is_tempseat() query
   function), then we have to free the TempSeat and reinstate our main
   Seat. The signal that we can do so is the PLUGLOG_CONNECT_SUCCESS
   notification, which indicates that SshProxy has finished all its
   connection setup work.
 - we also have to remember to free the TempSeat if our backend is
   disposed of without that having happened (e.g. because the
   connection _doesn't_ succeed).
 - in backends which have no local auth phase to worry about, ensure
   we don't call seat_set_trust_status on the main Seat _before_ it
   gets potentially replaced with a TempSeat. Moved some calls of
   seat_set_trust_status to just after new_connection(), so that now
   the initial trust status setup will go into the TempSeat (if
   appropriate) and be buffered until that seat is relinquished.

In all other uses of new_connection, where we don't have a Seat
available at all, we just pass NULL.

This is NFC, because neither new_connection() nor any of its delegates
will _actually_ do this replacement yet. We're just setting up the
framework to enable it to do so in the next commit.
This commit is contained in:
Simon Tatham
2021-09-13 17:17:20 +01:00
parent a08f953bd6
commit 6d272ee007
14 changed files with 465 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
ssh/portfwd.c
View File

@ -1161,7 +1161,7 @@ char *portfwdmgr_connect(PortFwdManager *mgr, Channel **chan_ret,
pf->s = new_connection(addr, dummy_realhost, port,
false, true, false, false, &pf->plug, mgr->conf,
NULL);
NULL, NULL);
sfree(dummy_realhost);
if ((err = sk_socket_error(pf->s)) != NULL) {
char *err_ret = dupstr(err);

14
ssh/ssh.c
View File

@ -598,6 +598,15 @@ static void ssh_socket_log(Plug *plug, PlugLogType type, SockAddr *addr,
backend_socket_log(ssh->seat, ssh->logctx, type, addr, port,
error_msg, error_code, ssh->conf,
ssh->session_started);
if (type == PLUGLOG_CONNECT_SUCCESS) {
if (is_tempseat(ssh->seat)) {
Seat *ts = ssh->seat;
tempseat_flush(ts);
ssh->seat = tempseat_get_real(ts);
tempseat_free(ts);
}
}
}
static void ssh_closing(Plug *plug, const char *error_msg, int error_code,
@ -790,7 +799,7 @@ static char *connect_to_host(
ssh->s = new_connection(addr, *realhost, port,
false, true, nodelay, keepalive,
&ssh->plug, ssh->conf,
log_get_policy(ssh->logctx));
log_get_policy(ssh->logctx), &ssh->seat);
if ((err = sk_socket_error(ssh->s)) != NULL) {
ssh->s = NULL;
seat_notify_remote_exit(ssh->seat);
@ -955,6 +964,9 @@ static void ssh_free(Backend *be)
ssh_shutdown(ssh);
if (is_tempseat(ssh->seat))
tempseat_free(ssh->seat);
conf_free(ssh->conf);
if (ssh->connshare)
sharestate_free(ssh->connshare);

2
ssh/x11fwd.c
View File

@ -564,7 +564,7 @@ static size_t x11_send(
xconn->s = new_connection(sk_addr_dup(xconn->disp->addr),
xconn->disp->realhost, xconn->disp->port,
false, true, false, false, &xconn->plug,
sshfwd_get_conf(xconn->c), NULL);
sshfwd_get_conf(xconn->c), NULL, NULL);
if ((err = sk_socket_error(xconn->s)) != NULL) {
char *err_message = dupprintf("unable to connect to"
" forwarded X server: %s", err);