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userauth: refactor banner handling.

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No functional change: I've just pulled out into separate subroutines
the piece of code that process a USERAUTH_BANNER message and append
it to our banner bufchain, and the piece that prints the contents of
the bufchain as user output. This will enable them to be called from
additional places easily.

(cherry picked from commit 99bbbd8d32)
This commit is contained in:
Simon Tatham 2023-04-29 11:36:13 +01:00
parent 44272b5355
commit 0dee089252
1 changed files with 61 additions and 49 deletions
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110
ssh/userauth2-client.c
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@ -133,6 +133,8 @@ static bool ssh2_userauth_ki_run_prompts(struct ssh2_userauth_state *s);
static void ssh2_userauth_ki_write_responses(
struct ssh2_userauth_state *s, BinarySink *bs);
static void ssh2_userauth_print_banner(struct ssh2_userauth_state *s);
static const PacketProtocolLayerVtable ssh2_userauth_vtable = {
.free = ssh2_userauth_free,
.process_queue = ssh2_userauth_process_queue,
@ -241,33 +243,38 @@ static void ssh2_userauth_free(PacketProtocolLayer *ppl)
sfree(s);
}
static void ssh2_userauth_handle_banner_packet(struct ssh2_userauth_state *s,
PktIn *pktin)
{
if (!s->show_banner)
return;
ptrlen string = get_string(pktin);
if (string.len > BANNER_LIMIT - bufchain_size(&s->banner))
string.len = BANNER_LIMIT - bufchain_size(&s->banner);
if (!s->banner_scc_initialised) {
s->banner_scc = seat_stripctrl_new(
s->ppl.seat, BinarySink_UPCAST(&s->banner_bs), SIC_BANNER);
if (s->banner_scc)
stripctrl_enable_line_limiting(s->banner_scc);
s->banner_scc_initialised = true;
}
if (s->banner_scc)
put_datapl(s->banner_scc, string);
else
put_datapl(&s->banner_bs, string);
}
static void ssh2_userauth_filter_queue(struct ssh2_userauth_state *s)
{
PktIn *pktin;
ptrlen string;
while ((pktin = pq_peek(s->ppl.in_pq)) != NULL) {
switch (pktin->type) {
case SSH2_MSG_USERAUTH_BANNER:
if (!s->show_banner) {
pq_pop(s->ppl.in_pq);
break;
}
string = get_string(pktin);
if (string.len > BANNER_LIMIT - bufchain_size(&s->banner))
string.len = BANNER_LIMIT - bufchain_size(&s->banner);
if (!s->banner_scc_initialised) {
s->banner_scc = seat_stripctrl_new(
s->ppl.seat, BinarySink_UPCAST(&s->banner_bs), SIC_BANNER);
if (s->banner_scc)
stripctrl_enable_line_limiting(s->banner_scc);
s->banner_scc_initialised = true;
}
if (s->banner_scc)
put_datapl(s->banner_scc, string);
else
put_datapl(&s->banner_bs, string);
ssh2_userauth_handle_banner_packet(s, pktin);
pq_pop(s->ppl.in_pq);
break;
@ -832,35 +839,7 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
* point, but we still need to precede and follow it with
* anti-spoofing header lines.
*/
if (bufchain_size(&s->banner) &&
(seat_verbose(s->ppl.seat) || seat_interactive(s->ppl.seat))) {
if (s->banner_scc) {
seat_antispoof_msg(
ppl_get_iseat(&s->ppl),
"Pre-authentication banner message from server:");
seat_set_trust_status(s->ppl.seat, false);
}
bool mid_line = false;
while (bufchain_size(&s->banner) > 0) {
ptrlen data = bufchain_prefix(&s->banner);
seat_banner_pl(ppl_get_iseat(&s->ppl), data);
mid_line =
(((const char *)data.ptr)[data.len-1] != '\n');
bufchain_consume(&s->banner, data.len);
}
bufchain_clear(&s->banner);
if (mid_line)
seat_banner_pl(ppl_get_iseat(&s->ppl),
PTRLEN_LITERAL("\r\n"));
if (s->banner_scc) {
seat_set_trust_status(s->ppl.seat, true);
seat_antispoof_msg(ppl_get_iseat(&s->ppl),
"End of banner message from server");
}
}
ssh2_userauth_print_banner(s);
if (pktin && pktin->type == SSH2_MSG_USERAUTH_SUCCESS) {
ppl_logevent("Access granted");
@ -2082,6 +2061,39 @@ static void ssh2_userauth_process_queue(PacketProtocolLayer *ppl)
crFinishV;
}
static void ssh2_userauth_print_banner(struct ssh2_userauth_state *s)
{
if (bufchain_size(&s->banner) &&
(seat_verbose(s->ppl.seat) || seat_interactive(s->ppl.seat))) {
if (s->banner_scc) {
seat_antispoof_msg(
ppl_get_iseat(&s->ppl),
"Pre-authentication banner message from server:");
seat_set_trust_status(s->ppl.seat, false);
}
bool mid_line = false;
while (bufchain_size(&s->banner) > 0) {
ptrlen data = bufchain_prefix(&s->banner);
seat_banner_pl(ppl_get_iseat(&s->ppl), data);
mid_line =
(((const char *)data.ptr)[data.len-1] != '\n');
bufchain_consume(&s->banner, data.len);
}
bufchain_clear(&s->banner);
if (mid_line)
seat_banner_pl(ppl_get_iseat(&s->ppl),
PTRLEN_LITERAL("\r\n"));
if (s->banner_scc) {
seat_set_trust_status(s->ppl.seat, true);
seat_antispoof_msg(ppl_get_iseat(&s->ppl),
"End of banner message from server");
}
}
}
static bool ssh2_userauth_ki_setup_prompts(
struct ssh2_userauth_state *s, BinarySource *src, bool plugin)
{