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/* Copyright (c) 2004-2018 Dovecot authors, see the included COPYING file */
#include "login-common.h"
#include "ioloop.h"
#include "istream.h"
#include "ostream.h"
#include "base64.h"
#include "safe-memset.h"
#include "str.h"
#include "str-sanitize.h"
#include "strescape.h"
#include "dsasl-client.h"
#include "client.h"
#include "pop3-proxy.h"
static const char *pop3_proxy_state_names[POP3_PROXY_STATE_COUNT] = {
"banner", "starttls", "xclient", "login1", "login2"
};
static int proxy_send_login(struct pop3_client *client, struct ostream *output)
{
struct dsasl_client_settings sasl_set;
const unsigned char *sasl_output;
size_t len;
const char *mech_name, *error;
string_t *str = t_str_new(128);
i_assert(client->common.proxy_ttl > 1);
if (client->proxy_xclient &&
!client->common.proxy_not_trusted) {
string_t *fwd = t_str_new(128);
for(const char *const *ptr = client->common.auth_passdb_args;*ptr != NULL; ptr++) {
if (strncasecmp(*ptr, "forward_", 8) == 0) {
if (str_len(fwd) > 0)
str_append_c(fwd, '\t');
str_append_tabescaped(fwd, (*ptr)+8);
}
}
str_printfa(str, "XCLIENT ADDR=%s PORT=%u SESSION=%s TTL=%u",
net_ip2addr(&client->common.ip),
client->common.remote_port,
client_get_session_id(&client->common),
client->common.proxy_ttl - 1);
if (str_len(fwd) > 0) {
str_append(str, " FORWARD=");
base64_encode(str_data(fwd), str_len(fwd), str);
}
str_append(str, "\r\n");
/* remote supports XCLIENT, send it */
o_stream_nsend(output, str_data(str), str_len(str));
client->proxy_state = POP3_PROXY_XCLIENT;
} else {
client->proxy_state = POP3_PROXY_LOGIN1;
}
str_truncate(str, 0);
if (client->common.proxy_mech == NULL) {
/* send USER command */
str_append(str, "USER ");
str_append(str, client->common.proxy_user);
str_append(str, "\r\n");
o_stream_nsend(output, str_data(str), str_len(str));
return 0;
}
i_assert(client->common.proxy_sasl_client == NULL);
i_zero(&sasl_set);
sasl_set.authid = client->common.proxy_master_user != NULL ?
client->common.proxy_master_user : client->common.proxy_user;
sasl_set.authzid = client->common.proxy_user;
sasl_set.password = client->common.proxy_password;
client->common.proxy_sasl_client =
dsasl_client_new(client->common.proxy_mech, &sasl_set);
mech_name = dsasl_client_mech_get_name(client->common.proxy_mech);
str_printfa(str, "AUTH %s ", mech_name);
if (dsasl_client_output(client->common.proxy_sasl_client,
&sasl_output, &len, &error) < 0) {
const char *reason = t_strdup_printf(
"SASL mechanism %s init failed: %s",
mech_name, error);
login_proxy_failed(client->common.login_proxy,
login_proxy_get_event(client->common.login_proxy),
LOGIN_PROXY_FAILURE_TYPE_INTERNAL, reason);
return -1;
}
if (len == 0)
str_append_c(str, '=');
else
base64_encode(sasl_output, len, str);
str_append(str, "\r\n");
o_stream_nsend(output, str_data(str), str_len(str));
if (client->proxy_state != POP3_PROXY_XCLIENT)
client->proxy_state = POP3_PROXY_LOGIN2;
return 0;
}
static int
pop3_proxy_continue_sasl_auth(struct client *client, struct ostream *output,
const char *line)
{
string_t *str;
const unsigned char *data;
size_t data_len;
const char *error;
int ret;
str = t_str_new(128);
if (base64_decode(line, strlen(line), NULL, str) < 0) {
const char *reason = t_strdup_printf(
"Invalid base64 data in AUTH response");
login_proxy_failed(client->login_proxy,
login_proxy_get_event(client->login_proxy),
LOGIN_PROXY_FAILURE_TYPE_PROTOCOL, reason);
return -1;
}
ret = dsasl_client_input(client->proxy_sasl_client,
str_data(str), str_len(str), &error);
if (ret == 0) {
ret = dsasl_client_output(client->proxy_sasl_client,
&data, &data_len, &error);
}
if (ret < 0) {
const char *reason = t_strdup_printf(
"Invalid authentication data: %s", error);
login_proxy_failed(client->login_proxy,
login_proxy_get_event(client->login_proxy),
LOGIN_PROXY_FAILURE_TYPE_PROTOCOL, reason);
return -1;
}
i_assert(ret == 0);
str_truncate(str, 0);
base64_encode(data, data_len, str);
str_append(str, "\r\n");
o_stream_nsend(output, str_data(str), str_len(str));
return 0;
}
int pop3_proxy_parse_line(struct client *client, const char *line)
{
struct pop3_client *pop3_client = (struct pop3_client *)client;
struct ostream *output;
enum login_proxy_ssl_flags ssl_flags;
i_assert(!client->destroyed);
output = login_proxy_get_ostream(client->login_proxy);
switch (pop3_client->proxy_state) {
case POP3_PROXY_BANNER:
/* this is a banner */
if (!str_begins(line, "+OK")) {
const char *reason = t_strdup_printf(
"Invalid banner: %s", str_sanitize(line, 160));
login_proxy_failed(client->login_proxy,
login_proxy_get_event(client->login_proxy),
LOGIN_PROXY_FAILURE_TYPE_PROTOCOL, reason);
return -1;
}
pop3_client->proxy_xclient =
str_begins(line+3, " [XCLIENT]");
ssl_flags = login_proxy_get_ssl_flags(client->login_proxy);
if ((ssl_flags & PROXY_SSL_FLAG_STARTTLS) == 0) {
if (proxy_send_login(pop3_client, output) < 0)
return -1;
} else {
o_stream_nsend_str(output, "STLS\r\n");
pop3_client->proxy_state = POP3_PROXY_STARTTLS;
}
return 0;
case POP3_PROXY_STARTTLS:
if (!str_begins(line, "+OK")) {
const char *reason = t_strdup_printf(
"STLS failed: %s", str_sanitize(line, 160));
login_proxy_failed(client->login_proxy,
login_proxy_get_event(client->login_proxy),
LOGIN_PROXY_FAILURE_TYPE_REMOTE, reason);
return -1;
}
if (login_proxy_starttls(client->login_proxy) < 0)
return -1;
/* i/ostreams changed. */
output = login_proxy_get_ostream(client->login_proxy);
if (proxy_send_login(pop3_client, output) < 0)
return -1;
return 1;
case POP3_PROXY_XCLIENT:
if (!str_begins(line, "+OK")) {
const char *reason = t_strdup_printf(
"XCLIENT failed: %s", str_sanitize(line, 160));
login_proxy_failed(client->login_proxy,
login_proxy_get_event(client->login_proxy),
LOGIN_PROXY_FAILURE_TYPE_REMOTE, reason);
return -1;
}
pop3_client->proxy_state = client->proxy_sasl_client == NULL ?
POP3_PROXY_LOGIN1 : POP3_PROXY_LOGIN2;
return 0;
case POP3_PROXY_LOGIN1:
i_assert(client->proxy_sasl_client == NULL);
if (!str_begins(line, "+OK"))
break;
/* USER successful, send PASS */
o_stream_nsend_str(output, t_strdup_printf(
"PASS %s\r\n", client->proxy_password));
pop3_client->proxy_state = POP3_PROXY_LOGIN2;
return 0;
case POP3_PROXY_LOGIN2:
if (str_begins(line, "+ ") &&
client->proxy_sasl_client != NULL) {
/* continue SASL authentication */
if (pop3_proxy_continue_sasl_auth(client, output,
line+2) < 0)
return -1;
return 0;
}
if (!str_begins(line, "+OK"))
break;
/* Login successful. Send this line to client. */
line = t_strconcat(line, "\r\n", NULL);
o_stream_nsend_str(client->output, line);
client_proxy_finish_destroy_client(client);
return 1;
case POP3_PROXY_STATE_COUNT:
i_unreached();
}
/* Login failed. Pass through the error message to client.
If the backend server isn't Dovecot, the error message may
be different from Dovecot's "user doesn't exist" error. This
would allow an attacker to find out what users exist in the
system.
The optimal way to handle this would be to replace the
backend's "password failed" error message with Dovecot's
AUTH_FAILED_MSG, but this would require a new setting and
the sysadmin to actually bother setting it properly.
So for now we'll just forward the error message. This
shouldn't be a real problem since of course everyone will
be using only Dovecot as their backend :) */
enum login_proxy_failure_type failure_type =
LOGIN_PROXY_FAILURE_TYPE_AUTH;
if (!str_begins(line, "-ERR ")) {
client_send_reply(client, POP3_CMD_REPLY_ERROR,
AUTH_FAILED_MSG);
} else if (str_begins(line, "-ERR [SYS/TEMP]")) {
/* delay sending the reply until we know if we reconnect */
failure_type = LOGIN_PROXY_FAILURE_TYPE_AUTH_TEMPFAIL;
line += 5;
} else {
client_send_raw(client, t_strconcat(line, "\r\n", NULL));
line += 5;
}
login_proxy_failed(client->login_proxy,
login_proxy_get_event(client->login_proxy),
failure_type, line);
return -1;
}
void pop3_proxy_reset(struct client *client)
{
struct pop3_client *pop3_client = (struct pop3_client *)client;
pop3_client->proxy_state = POP3_PROXY_BANNER;
}
static void
pop3_proxy_send_failure_reply(struct client *client,
enum login_proxy_failure_type type,
const char *reason)
{
switch (type) {
case LOGIN_PROXY_FAILURE_TYPE_CONNECT:
case LOGIN_PROXY_FAILURE_TYPE_INTERNAL:
case LOGIN_PROXY_FAILURE_TYPE_REMOTE:
case LOGIN_PROXY_FAILURE_TYPE_PROTOCOL:
client_send_reply(client, POP3_CMD_REPLY_TEMPFAIL,
LOGIN_PROXY_FAILURE_MSG);
break;
case LOGIN_PROXY_FAILURE_TYPE_INTERNAL_CONFIG:
case LOGIN_PROXY_FAILURE_TYPE_REMOTE_CONFIG:
client_send_reply(client, POP3_CMD_REPLY_ERROR,
LOGIN_PROXY_FAILURE_MSG);
break;
case LOGIN_PROXY_FAILURE_TYPE_AUTH_TEMPFAIL:
/* [SYS/TEMP] prefix is already in the reason string */
client_send_reply(client, POP3_CMD_REPLY_ERROR, reason);
break;
case LOGIN_PROXY_FAILURE_TYPE_AUTH:
/* reply was already sent */
break;
}
}
void pop3_proxy_failed(struct client *client,
enum login_proxy_failure_type type,
const char *reason, bool reconnecting)
{
if (!reconnecting)
pop3_proxy_send_failure_reply(client, type, reason);
client_common_proxy_failed(client, type, reason, reconnecting);
}
const char *pop3_proxy_get_state(struct client *client)
{
struct pop3_client *pop3_client = (struct pop3_client *)client;
return pop3_proxy_state_names[pop3_client->proxy_state];
}
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