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sshserver.c
468 lines (386 loc) · 14 KB
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sshserver.c
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/*
* Top-level code for SSH server implementation.
*/
#include <assert.h>
#include <stddef.h>
#include "putty.h"
#include "ssh.h"
#include "sshbpp.h"
#include "sshppl.h"
#include "sshserver.h"
#ifndef NO_GSSAPI
#include "sshgssc.h"
#include "sshgss.h"
#endif
struct Ssh { int dummy; };
typedef struct server server;
struct server {
bufchain in_raw, out_raw;
IdempotentCallback ic_out_raw;
bufchain dummy_user_input; /* we never put anything on this */
PacketLogSettings pls;
LogContext *logctx;
struct DataTransferStats stats;
int remote_bugs;
Socket *socket;
Plug plug;
int conn_throttle_count;
bool frozen;
Conf *conf;
ssh_key *const *hostkeys;
int nhostkeys;
struct RSAKey *hostkey1;
AuthPolicy *authpolicy;
const SftpServerVtable *sftpserver_vt;
Seat seat;
Ssh ssh;
struct ssh_version_receiver version_receiver;
BinaryPacketProtocol *bpp;
PacketProtocolLayer *base_layer;
ConnectionLayer *cl;
struct ssh_connection_shared_gss_state gss_state;
};
static void ssh_server_free_callback(void *vsrv);
static void server_got_ssh_version(struct ssh_version_receiver *rcv,
int major_version);
static void server_connect_bpp(server *srv);
static void server_bpp_output_raw_data_callback(void *vctx);
void share_activate(ssh_sharing_state *sharestate,
const char *server_verstring) {}
void ssh_connshare_provide_connlayer(ssh_sharing_state *sharestate,
ConnectionLayer *cl) {}
int share_ndownstreams(ssh_sharing_state *sharestate) { return 0; }
void share_got_pkt_from_server(ssh_sharing_connstate *cs, int type,
const void *vpkt, int pktlen) {}
void share_setup_x11_channel(ssh_sharing_connstate *cs, share_channel *chan,
unsigned upstream_id, unsigned server_id,
unsigned server_currwin, unsigned server_maxpkt,
unsigned client_adjusted_window,
const char *peer_addr, int peer_port, int endian,
int protomajor, int protominor,
const void *initial_data, int initial_len) {}
Channel *agentf_new(SshChannel *c) { return NULL; }
bool agent_exists(void) { return false; }
void ssh_got_exitcode(Ssh *ssh, int exitcode) {}
mainchan *mainchan_new(
PacketProtocolLayer *ppl, ConnectionLayer *cl, Conf *conf,
int term_width, int term_height, int is_simple, SshChannel **sc_out)
{ return NULL; }
void mainchan_get_specials(
mainchan *mc, add_special_fn_t add_special, void *ctx) {}
void mainchan_special_cmd(mainchan *mc, SessionSpecialCode code, int arg) {}
void mainchan_terminal_size(mainchan *mc, int width, int height) {}
/* Seat functions to ensure we don't get choosy about crypto - as the
* server, it's not up to us to give user warnings */
static int server_confirm_weak_crypto_primitive(
Seat *seat, const char *algtype, const char *algname,
void (*callback)(void *ctx, int result), void *ctx) { return 1; }
static int server_confirm_weak_cached_hostkey(
Seat *seat, const char *algname, const char *betteralgs,
void (*callback)(void *ctx, int result), void *ctx) { return 1; }
static const SeatVtable server_seat_vt = {
nullseat_output,
nullseat_eof,
nullseat_get_userpass_input,
nullseat_notify_remote_exit,
nullseat_connection_fatal,
nullseat_update_specials_menu,
nullseat_get_ttymode,
nullseat_set_busy_status,
nullseat_verify_ssh_host_key,
server_confirm_weak_crypto_primitive,
server_confirm_weak_cached_hostkey,
nullseat_is_never_utf8,
nullseat_echoedit_update,
nullseat_get_x_display,
nullseat_get_windowid,
nullseat_get_window_pixel_size,
};
static void server_socket_log(Plug *plug, int type, SockAddr *addr, int port,
const char *error_msg, int error_code)
{
/* server *srv = container_of(plug, server, plug); */
/* FIXME */
}
static void server_closing(Plug *plug, const char *error_msg, int error_code,
bool calling_back)
{
server *srv = container_of(plug, server, plug);
if (error_msg) {
ssh_remote_error(&srv->ssh, "Network error: %s", error_msg);
} else if (srv->bpp) {
srv->bpp->input_eof = true;
queue_idempotent_callback(&srv->bpp->ic_in_raw);
}
}
static void server_receive(Plug *plug, int urgent, char *data, int len)
{
server *srv = container_of(plug, server, plug);
/* Log raw data, if we're in that mode. */
if (srv->logctx)
log_packet(srv->logctx, PKT_INCOMING, -1, NULL, data, len,
0, NULL, NULL, 0, NULL);
bufchain_add(&srv->in_raw, data, len);
if (!srv->frozen && srv->bpp)
queue_idempotent_callback(&srv->bpp->ic_in_raw);
}
static void server_sent(Plug *plug, int bufsize)
{
#ifdef FIXME
server *srv = container_of(plug, server, plug);
/*
* If the send backlog on the SSH socket itself clears, we should
* unthrottle the whole world if it was throttled. Also trigger an
* extra call to the consumer of the BPP's output, to try to send
* some more data off its bufchain.
*/
if (bufsize < SSH_MAX_BACKLOG) {
srv_throttle_all(srv, 0, bufsize);
queue_idempotent_callback(&srv->ic_out_raw);
}
#endif
}
LogContext *ssh_get_logctx(Ssh *ssh)
{
server *srv = container_of(ssh, server, ssh);
return srv->logctx;
}
void ssh_throttle_conn(Ssh *ssh, int adjust)
{
server *srv = container_of(ssh, server, ssh);
int old_count = srv->conn_throttle_count;
bool frozen;
srv->conn_throttle_count += adjust;
assert(srv->conn_throttle_count >= 0);
if (srv->conn_throttle_count && !old_count) {
frozen = true;
} else if (!srv->conn_throttle_count && old_count) {
frozen = false;
} else {
return; /* don't change current frozen state */
}
srv->frozen = frozen;
if (srv->socket) {
sk_set_frozen(srv->socket, frozen);
/*
* Now process any SSH connection data that was stashed in our
* queue while we were frozen.
*/
queue_idempotent_callback(&srv->bpp->ic_in_raw);
}
}
static const PlugVtable ssh_server_plugvt = {
server_socket_log,
server_closing,
server_receive,
server_sent,
NULL
};
Plug *ssh_server_plug(
Conf *conf, ssh_key *const *hostkeys, int nhostkeys,
struct RSAKey *hostkey1, AuthPolicy *authpolicy, LogPolicy *logpolicy,
const SftpServerVtable *sftpserver_vt)
{
server *srv = snew(server);
memset(srv, 0, sizeof(server));
srv->plug.vt = &ssh_server_plugvt;
srv->conf = conf_copy(conf);
srv->logctx = log_init(logpolicy, conf);
conf_set_bool(srv->conf, CONF_ssh_no_shell, true);
srv->nhostkeys = nhostkeys;
srv->hostkeys = hostkeys;
srv->hostkey1 = hostkey1;
srv->authpolicy = authpolicy;
srv->sftpserver_vt = sftpserver_vt;
srv->seat.vt = &server_seat_vt;
bufchain_init(&srv->in_raw);
bufchain_init(&srv->out_raw);
bufchain_init(&srv->dummy_user_input);
/* FIXME: replace with sensible */
srv->gss_state.libs = snew(struct ssh_gss_liblist);
srv->gss_state.libs->nlibraries = 0;
return &srv->plug;
}
void ssh_server_start(Plug *plug, Socket *socket)
{
server *srv = container_of(plug, server, plug);
const char *our_protoversion;
if (srv->hostkey1 && srv->nhostkeys) {
our_protoversion = "1.99"; /* offer both SSH-1 and SSH-2 */
} else if (srv->hostkey1) {
our_protoversion = "1.5"; /* SSH-1 only */
} else {
assert(srv->nhostkeys);
our_protoversion = "2.0"; /* SSH-2 only */
}
srv->socket = socket;
srv->ic_out_raw.fn = server_bpp_output_raw_data_callback;
srv->ic_out_raw.ctx = srv;
srv->version_receiver.got_ssh_version = server_got_ssh_version;
srv->bpp = ssh_verstring_new(
srv->conf, srv->logctx, false /* bare_connection */,
our_protoversion, &srv->version_receiver,
true, "Uppity");
server_connect_bpp(srv);
queue_idempotent_callback(&srv->bpp->ic_in_raw);
}
static void ssh_server_free_callback(void *vsrv)
{
server *srv = (server *)vsrv;
bufchain_clear(&srv->in_raw);
bufchain_clear(&srv->out_raw);
bufchain_clear(&srv->dummy_user_input);
sk_close(srv->socket);
if (srv->bpp)
ssh_bpp_free(srv->bpp);
delete_callbacks_for_context(srv);
conf_free(srv->conf);
log_free(srv->logctx);
sfree(srv->gss_state.libs); /* FIXME: replace with sensible */
sfree(srv);
server_instance_terminated();
}
static void server_connect_bpp(server *srv)
{
srv->bpp->ssh = &srv->ssh;
srv->bpp->in_raw = &srv->in_raw;
srv->bpp->out_raw = &srv->out_raw;
srv->bpp->out_raw->ic = &srv->ic_out_raw;
srv->bpp->pls = &srv->pls;
srv->bpp->logctx = srv->logctx;
srv->bpp->remote_bugs = srv->remote_bugs;
/* Servers don't really have a notion of 'unexpected' connection
* closure. The client is free to close if it likes. */
srv->bpp->expect_close = true;
}
static void server_connect_ppl(server *srv, PacketProtocolLayer *ppl)
{
ppl->bpp = srv->bpp;
ppl->user_input = &srv->dummy_user_input;
ppl->logctx = srv->logctx;
ppl->ssh = &srv->ssh;
ppl->seat = &srv->seat;
ppl->remote_bugs = srv->remote_bugs;
}
static void server_bpp_output_raw_data_callback(void *vctx)
{
server *srv = (server *)vctx;
if (!srv->socket)
return;
while (bufchain_size(&srv->out_raw) > 0) {
void *data;
int len, backlog;
bufchain_prefix(&srv->out_raw, &data, &len);
if (srv->logctx)
log_packet(srv->logctx, PKT_OUTGOING, -1, NULL, data, len,
0, NULL, NULL, 0, NULL);
backlog = sk_write(srv->socket, data, len);
bufchain_consume(&srv->out_raw, len);
if (backlog > SSH_MAX_BACKLOG) {
#ifdef FIXME
ssh_throttle_all(ssh, 1, backlog);
#endif
return;
}
}
#ifdef FIXME
if (ssh->pending_close) {
sk_close(ssh->s);
ssh->s = NULL;
}
#endif
}
#define LOG_FORMATTED_MSG(logctx, fmt) do \
{ \
va_list ap; \
va_start(ap, fmt); \
logeventvf(logctx, fmt, ap); \
va_end(ap); \
} while (0)
void ssh_remote_error(Ssh *ssh, const char *fmt, ...)
{
server *srv = container_of(ssh, server, ssh);
LOG_FORMATTED_MSG(srv->logctx, fmt);
queue_toplevel_callback(ssh_server_free_callback, srv);
}
void ssh_remote_eof(Ssh *ssh, const char *fmt, ...)
{
server *srv = container_of(ssh, server, ssh);
LOG_FORMATTED_MSG(srv->logctx, fmt);
queue_toplevel_callback(ssh_server_free_callback, srv);
}
void ssh_proto_error(Ssh *ssh, const char *fmt, ...)
{
server *srv = container_of(ssh, server, ssh);
LOG_FORMATTED_MSG(srv->logctx, fmt);
queue_toplevel_callback(ssh_server_free_callback, srv);
}
void ssh_sw_abort(Ssh *ssh, const char *fmt, ...)
{
server *srv = container_of(ssh, server, ssh);
LOG_FORMATTED_MSG(srv->logctx, fmt);
queue_toplevel_callback(ssh_server_free_callback, srv);
}
void ssh_user_close(Ssh *ssh, const char *fmt, ...)
{
server *srv = container_of(ssh, server, ssh);
LOG_FORMATTED_MSG(srv->logctx, fmt);
queue_toplevel_callback(ssh_server_free_callback, srv);
}
static void server_got_ssh_version(struct ssh_version_receiver *rcv,
int major_version)
{
server *srv = container_of(rcv, server, version_receiver);
BinaryPacketProtocol *old_bpp;
PacketProtocolLayer *connection_layer;
old_bpp = srv->bpp;
srv->remote_bugs = ssh_verstring_get_bugs(old_bpp);
if (major_version == 2) {
PacketProtocolLayer *userauth_layer, *transport_child_layer;
srv->bpp = ssh2_bpp_new(srv->logctx, &srv->stats, true);
server_connect_bpp(srv);
connection_layer = ssh2_connection_new(
&srv->ssh, NULL, false, srv->conf,
ssh_verstring_get_local(old_bpp), &srv->cl);
ssh2connection_server_configure(connection_layer, srv->sftpserver_vt);
server_connect_ppl(srv, connection_layer);
if (conf_get_bool(srv->conf, CONF_ssh_no_userauth)) {
userauth_layer = NULL;
transport_child_layer = connection_layer;
} else {
userauth_layer = ssh2_userauth_server_new(
connection_layer, srv->authpolicy);
server_connect_ppl(srv, userauth_layer);
transport_child_layer = userauth_layer;
}
srv->base_layer = ssh2_transport_new(
srv->conf, NULL, 0, NULL,
ssh_verstring_get_remote(old_bpp),
ssh_verstring_get_local(old_bpp),
&srv->gss_state, &srv->stats, transport_child_layer, true);
ssh2_transport_provide_hostkeys(
srv->base_layer, srv->hostkeys, srv->nhostkeys);
if (userauth_layer)
ssh2_userauth_server_set_transport_layer(
userauth_layer, srv->base_layer);
server_connect_ppl(srv, srv->base_layer);
} else {
srv->bpp = ssh1_bpp_new(srv->logctx);
server_connect_bpp(srv);
connection_layer = ssh1_connection_new(&srv->ssh, srv->conf, &srv->cl);
server_connect_ppl(srv, connection_layer);
srv->base_layer = ssh1_login_server_new(
connection_layer, srv->hostkey1, srv->authpolicy);
server_connect_ppl(srv, srv->base_layer);
}
/* Connect the base layer - whichever it is - to the BPP, and set
* up its selfptr. */
srv->base_layer->selfptr = &srv->base_layer;
ssh_ppl_setup_queues(srv->base_layer, &srv->bpp->in_pq, &srv->bpp->out_pq);
#ifdef FIXME // we probably will want one of these, in the end
srv->pinger = pinger_new(srv->conf, &srv->backend);
#endif
queue_idempotent_callback(&srv->bpp->ic_in_raw);
ssh_ppl_process_queue(srv->base_layer);
ssh_bpp_free(old_bpp);
}