mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-01-09 17:38:00 +00:00
ae1148267d
Historically, because of the way Windows Pageant's IPC works, PuTTY's agent forwarding has always been message-oriented. The channel implementation in agentf.c deals with receiving a data stream from the remote agent client and breaking it up into messages, and then it passes each message individually to agent_query(). On Unix, this is more work than is really needed, and I've always meant to get round to doing the more obvious thing: making an agent forwarding channel into simply a stream-oriented proxy, passing raw data back and forth between the SSH channel and the local AF_UNIX socket without having to know or care about the message boundaries in the stream. The portfwdmgr_connect_socket() facility introduced by the previous commit is the missing piece of infrastructure to make that possible. Now, the agent client module provides an API that includes a callback you can pass to portfwdmgr_connect_socket() to open a streamed agent connection, and the agent forwarding setup function tries to use that where possible, only falling back to the message-based agentf.c system if it can't be done. On Windows, the new piece of agent-client API returns failure, so we still fall back to agentf.c there. There are two benefits to doing it this way. One is that it's just simpler and more robust: if PuTTY isn't trying to parse the agent connection, then it has less work to do and fewer places to introduce bugs. The other is that it's futureproof against changes in the agent protocol: if any kind of extension is ever introduced that requires keeping state within a single agent connection, or that changes the protocol itself so that agentf's message-boundary detection stops working, then this forwarding system will still work.
506 lines
16 KiB
C
506 lines
16 KiB
C
/*
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* Client-specific parts of the SSH-2 connection layer.
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*/
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#include <assert.h>
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#include "putty.h"
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#include "ssh.h"
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#include "sshbpp.h"
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#include "sshppl.h"
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#include "sshchan.h"
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#include "sshcr.h"
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#include "ssh2connection.h"
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static ChanopenResult chan_open_x11(
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struct ssh2_connection_state *s, SshChannel *sc,
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ptrlen peeraddr, int peerport)
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{
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PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
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char *peeraddr_str;
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Channel *ch;
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ppl_logevent("Received X11 connect request from %.*s:%d",
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PTRLEN_PRINTF(peeraddr), peerport);
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if (!s->X11_fwd_enabled && !s->connshare) {
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CHANOPEN_RETURN_FAILURE(
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SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED,
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("X11 forwarding is not enabled"));
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}
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peeraddr_str = peeraddr.ptr ? mkstr(peeraddr) : NULL;
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ch = x11_new_channel(
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s->x11authtree, sc, peeraddr_str, peerport, s->connshare != NULL);
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sfree(peeraddr_str);
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ppl_logevent("Opened X11 forward channel");
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CHANOPEN_RETURN_SUCCESS(ch);
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}
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static ChanopenResult chan_open_forwarded_tcpip(
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struct ssh2_connection_state *s, SshChannel *sc,
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ptrlen fwdaddr, int fwdport, ptrlen peeraddr, int peerport)
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{
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PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
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struct ssh_rportfwd pf, *realpf;
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Channel *ch;
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char *err;
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ppl_logevent("Received remote port %.*s:%d open request from %.*s:%d",
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PTRLEN_PRINTF(fwdaddr), fwdport,
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PTRLEN_PRINTF(peeraddr), peerport);
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pf.shost = mkstr(fwdaddr);
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pf.sport = fwdport;
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realpf = find234(s->rportfwds, &pf, NULL);
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sfree(pf.shost);
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if (realpf == NULL) {
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CHANOPEN_RETURN_FAILURE(
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SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED,
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("Remote port is not recognised"));
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}
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if (realpf->share_ctx) {
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/*
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* This port forwarding is on behalf of a connection-sharing
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* downstream.
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*/
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CHANOPEN_RETURN_DOWNSTREAM(realpf->share_ctx);
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}
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err = portfwdmgr_connect(
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s->portfwdmgr, &ch, realpf->dhost, realpf->dport,
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sc, realpf->addressfamily);
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ppl_logevent("Attempting to forward remote port to %s:%d",
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realpf->dhost, realpf->dport);
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if (err != NULL) {
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ppl_logevent("Port open failed: %s", err);
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sfree(err);
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CHANOPEN_RETURN_FAILURE(
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SSH2_OPEN_CONNECT_FAILED,
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("Port open failed"));
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}
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ppl_logevent("Forwarded port opened successfully");
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CHANOPEN_RETURN_SUCCESS(ch);
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}
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static ChanopenResult chan_open_auth_agent(
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struct ssh2_connection_state *s, SshChannel *sc)
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{
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if (!s->agent_fwd_enabled) {
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CHANOPEN_RETURN_FAILURE(
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SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED,
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("Agent forwarding is not enabled"));
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}
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/*
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* If possible, make a stream-oriented connection to the agent and
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* set up an ordinary port-forwarding type channel over it.
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*/
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agent_connect_ctx *ctx = agent_get_connect_ctx();
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if (ctx) {
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Channel *ch;
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char *err = portfwdmgr_connect_socket(
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s->portfwdmgr, &ch, agent_connect, ctx, sc);
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agent_free_connect_ctx(ctx);
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if (err == NULL) {
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CHANOPEN_RETURN_SUCCESS(ch);
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} else {
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sfree(err);
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/* now continue to the fallback case below */
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}
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}
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/*
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* Otherwise, fall back to the old-fashioned system of parsing the
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* forwarded data stream ourselves for message boundaries, and
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* passing each individual message to the one-off agent_query().
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*/
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CHANOPEN_RETURN_SUCCESS(agentf_new(sc));
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}
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ChanopenResult ssh2_connection_parse_channel_open(
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struct ssh2_connection_state *s, ptrlen type,
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PktIn *pktin, SshChannel *sc)
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{
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if (ptrlen_eq_string(type, "x11")) {
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ptrlen peeraddr = get_string(pktin);
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int peerport = get_uint32(pktin);
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return chan_open_x11(s, sc, peeraddr, peerport);
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} else if (ptrlen_eq_string(type, "forwarded-tcpip")) {
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ptrlen fwdaddr = get_string(pktin);
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int fwdport = toint(get_uint32(pktin));
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ptrlen peeraddr = get_string(pktin);
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int peerport = toint(get_uint32(pktin));
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return chan_open_forwarded_tcpip(
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s, sc, fwdaddr, fwdport, peeraddr, peerport);
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} else if (ptrlen_eq_string(type, "auth-agent@openssh.com")) {
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return chan_open_auth_agent(s, sc);
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} else {
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CHANOPEN_RETURN_FAILURE(
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SSH2_OPEN_UNKNOWN_CHANNEL_TYPE,
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("Unsupported channel type requested"));
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}
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}
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bool ssh2_connection_parse_global_request(
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struct ssh2_connection_state *s, ptrlen type, PktIn *pktin)
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{
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/*
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* We don't know of any global requests that an SSH client needs
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* to honour.
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*/
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return false;
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}
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PktOut *ssh2_portfwd_chanopen(
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struct ssh2_connection_state *s, struct ssh2_channel *c,
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const char *hostname, int port,
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const char *description, const SocketPeerInfo *peerinfo)
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{
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PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
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PktOut *pktout;
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/*
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* In client mode, this function is called by portfwdmgr in
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* response to PortListeners that were set up in
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* portfwdmgr_config, which means that the hostname and port
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* parameters will indicate the host we want to tell the server to
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* connect _to_.
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*/
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ppl_logevent("Opening connection to %s:%d for %s",
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hostname, port, description);
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pktout = ssh2_chanopen_init(c, "direct-tcpip");
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{
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char *trimmed_host = host_strduptrim(hostname);
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put_stringz(pktout, trimmed_host);
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sfree(trimmed_host);
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}
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put_uint32(pktout, port);
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/*
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* We make up values for the originator data; partly it's too much
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* hassle to keep track, and partly I'm not convinced the server
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* should be told details like that about my local network
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* configuration. The "originator IP address" is syntactically a
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* numeric IP address, and some servers (e.g., Tectia) get upset
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* if it doesn't match this syntax.
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*/
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put_stringz(pktout, "0.0.0.0");
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put_uint32(pktout, 0);
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return pktout;
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}
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static int ssh2_rportfwd_cmp(void *av, void *bv)
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{
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struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
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struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
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int i;
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if ( (i = strcmp(a->shost, b->shost)) != 0)
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return i < 0 ? -1 : +1;
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if (a->sport > b->sport)
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return +1;
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if (a->sport < b->sport)
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return -1;
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return 0;
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}
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static void ssh2_rportfwd_globreq_response(struct ssh2_connection_state *s,
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PktIn *pktin, void *ctx)
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{
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PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
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struct ssh_rportfwd *rpf = (struct ssh_rportfwd *)ctx;
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if (pktin->type == SSH2_MSG_REQUEST_SUCCESS) {
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ppl_logevent("Remote port forwarding from %s enabled",
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rpf->log_description);
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} else {
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ppl_logevent("Remote port forwarding from %s refused",
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rpf->log_description);
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struct ssh_rportfwd *realpf = del234(s->rportfwds, rpf);
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assert(realpf == rpf);
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portfwdmgr_close(s->portfwdmgr, rpf->pfr);
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free_rportfwd(rpf);
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}
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}
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struct ssh_rportfwd *ssh2_rportfwd_alloc(
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ConnectionLayer *cl,
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const char *shost, int sport, const char *dhost, int dport,
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int addressfamily, const char *log_description, PortFwdRecord *pfr,
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ssh_sharing_connstate *share_ctx)
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{
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struct ssh2_connection_state *s =
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container_of(cl, struct ssh2_connection_state, cl);
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struct ssh_rportfwd *rpf = snew(struct ssh_rportfwd);
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if (!s->rportfwds)
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s->rportfwds = newtree234(ssh2_rportfwd_cmp);
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rpf->shost = dupstr(shost);
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rpf->sport = sport;
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rpf->dhost = dupstr(dhost);
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rpf->dport = dport;
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rpf->addressfamily = addressfamily;
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rpf->log_description = dupstr(log_description);
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rpf->pfr = pfr;
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rpf->share_ctx = share_ctx;
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if (add234(s->rportfwds, rpf) != rpf) {
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free_rportfwd(rpf);
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return NULL;
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}
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if (!rpf->share_ctx) {
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PktOut *pktout = ssh_bpp_new_pktout(
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s->ppl.bpp, SSH2_MSG_GLOBAL_REQUEST);
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put_stringz(pktout, "tcpip-forward");
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put_bool(pktout, true); /* want reply */
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put_stringz(pktout, rpf->shost);
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put_uint32(pktout, rpf->sport);
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pq_push(s->ppl.out_pq, pktout);
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ssh2_queue_global_request_handler(
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s, ssh2_rportfwd_globreq_response, rpf);
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}
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return rpf;
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}
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void ssh2_rportfwd_remove(ConnectionLayer *cl, struct ssh_rportfwd *rpf)
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{
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struct ssh2_connection_state *s =
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container_of(cl, struct ssh2_connection_state, cl);
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if (rpf->share_ctx) {
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/*
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* We don't manufacture a cancel-tcpip-forward message for
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* remote port forwardings being removed on behalf of a
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* downstream; we just pass through the one the downstream
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* sent to us.
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*/
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} else {
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PktOut *pktout = ssh_bpp_new_pktout(
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s->ppl.bpp, SSH2_MSG_GLOBAL_REQUEST);
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put_stringz(pktout, "cancel-tcpip-forward");
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put_bool(pktout, false); /* _don't_ want reply */
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put_stringz(pktout, rpf->shost);
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put_uint32(pktout, rpf->sport);
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pq_push(s->ppl.out_pq, pktout);
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}
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assert(s->rportfwds);
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struct ssh_rportfwd *realpf = del234(s->rportfwds, rpf);
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assert(realpf == rpf);
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free_rportfwd(rpf);
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}
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SshChannel *ssh2_session_open(ConnectionLayer *cl, Channel *chan)
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{
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struct ssh2_connection_state *s =
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container_of(cl, struct ssh2_connection_state, cl);
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PacketProtocolLayer *ppl = &s->ppl; /* for ppl_logevent */
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struct ssh2_channel *c = snew(struct ssh2_channel);
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PktOut *pktout;
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c->connlayer = s;
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ssh2_channel_init(c);
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c->halfopen = true;
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c->chan = chan;
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ppl_logevent("Opening main session channel");
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pktout = ssh2_chanopen_init(c, "session");
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pq_push(s->ppl.out_pq, pktout);
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return &c->sc;
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}
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SshChannel *ssh2_serverside_x11_open(
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ConnectionLayer *cl, Channel *chan, const SocketPeerInfo *pi)
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{
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unreachable("Should never be called in the client");
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}
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SshChannel *ssh2_serverside_agent_open(ConnectionLayer *cl, Channel *chan)
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{
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unreachable("Should never be called in the client");
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}
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static void ssh2_channel_response(
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struct ssh2_channel *c, PktIn *pkt, void *ctx)
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{
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chan_request_response(c->chan, pkt->type == SSH2_MSG_CHANNEL_SUCCESS);
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}
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void ssh2channel_start_shell(SshChannel *sc, bool want_reply)
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{
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struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
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struct ssh2_connection_state *s = c->connlayer;
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PktOut *pktout = ssh2_chanreq_init(
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c, "shell", want_reply ? ssh2_channel_response : NULL, NULL);
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pq_push(s->ppl.out_pq, pktout);
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}
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void ssh2channel_start_command(
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SshChannel *sc, bool want_reply, const char *command)
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{
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struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
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struct ssh2_connection_state *s = c->connlayer;
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PktOut *pktout = ssh2_chanreq_init(
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c, "exec", want_reply ? ssh2_channel_response : NULL, NULL);
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put_stringz(pktout, command);
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pq_push(s->ppl.out_pq, pktout);
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}
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bool ssh2channel_start_subsystem(
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SshChannel *sc, bool want_reply, const char *subsystem)
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{
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struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
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struct ssh2_connection_state *s = c->connlayer;
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PktOut *pktout = ssh2_chanreq_init(
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c, "subsystem", want_reply ? ssh2_channel_response : NULL, NULL);
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put_stringz(pktout, subsystem);
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pq_push(s->ppl.out_pq, pktout);
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return true;
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}
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void ssh2channel_send_exit_status(SshChannel *sc, int status)
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{
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unreachable("Should never be called in the client");
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}
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void ssh2channel_send_exit_signal(
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SshChannel *sc, ptrlen signame, bool core_dumped, ptrlen msg)
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{
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unreachable("Should never be called in the client");
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}
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void ssh2channel_send_exit_signal_numeric(
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SshChannel *sc, int signum, bool core_dumped, ptrlen msg)
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{
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unreachable("Should never be called in the client");
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}
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void ssh2channel_request_x11_forwarding(
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SshChannel *sc, bool want_reply, const char *authproto,
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const char *authdata, int screen_number, bool oneshot)
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{
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struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
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struct ssh2_connection_state *s = c->connlayer;
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PktOut *pktout = ssh2_chanreq_init(
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c, "x11-req", want_reply ? ssh2_channel_response : NULL, NULL);
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put_bool(pktout, oneshot);
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put_stringz(pktout, authproto);
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put_stringz(pktout, authdata);
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put_uint32(pktout, screen_number);
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pq_push(s->ppl.out_pq, pktout);
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}
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void ssh2channel_request_agent_forwarding(SshChannel *sc, bool want_reply)
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{
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struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
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struct ssh2_connection_state *s = c->connlayer;
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PktOut *pktout = ssh2_chanreq_init(
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c, "auth-agent-req@openssh.com",
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want_reply ? ssh2_channel_response : NULL, NULL);
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pq_push(s->ppl.out_pq, pktout);
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}
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void ssh2channel_request_pty(
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SshChannel *sc, bool want_reply, Conf *conf, int w, int h)
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{
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struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
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struct ssh2_connection_state *s = c->connlayer;
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strbuf *modebuf;
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PktOut *pktout = ssh2_chanreq_init(
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c, "pty-req", want_reply ? ssh2_channel_response : NULL, NULL);
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put_stringz(pktout, conf_get_str(conf, CONF_termtype));
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put_uint32(pktout, w);
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put_uint32(pktout, h);
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put_uint32(pktout, 0); /* pixel width */
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put_uint32(pktout, 0); /* pixel height */
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modebuf = strbuf_new();
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write_ttymodes_to_packet(
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BinarySink_UPCAST(modebuf), 2,
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get_ttymodes_from_conf(s->ppl.seat, conf));
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put_stringsb(pktout, modebuf);
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pq_push(s->ppl.out_pq, pktout);
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}
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bool ssh2channel_send_env_var(
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SshChannel *sc, bool want_reply, const char *var, const char *value)
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{
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struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
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struct ssh2_connection_state *s = c->connlayer;
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PktOut *pktout = ssh2_chanreq_init(
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|
c, "env", want_reply ? ssh2_channel_response : NULL, NULL);
|
|
put_stringz(pktout, var);
|
|
put_stringz(pktout, value);
|
|
pq_push(s->ppl.out_pq, pktout);
|
|
|
|
return true;
|
|
}
|
|
|
|
bool ssh2channel_send_serial_break(SshChannel *sc, bool want_reply, int length)
|
|
{
|
|
struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
|
|
struct ssh2_connection_state *s = c->connlayer;
|
|
|
|
PktOut *pktout = ssh2_chanreq_init(
|
|
c, "break", want_reply ? ssh2_channel_response : NULL, NULL);
|
|
put_uint32(pktout, length);
|
|
pq_push(s->ppl.out_pq, pktout);
|
|
|
|
return true;
|
|
}
|
|
|
|
bool ssh2channel_send_signal(
|
|
SshChannel *sc, bool want_reply, const char *signame)
|
|
{
|
|
struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
|
|
struct ssh2_connection_state *s = c->connlayer;
|
|
|
|
PktOut *pktout = ssh2_chanreq_init(
|
|
c, "signal", want_reply ? ssh2_channel_response : NULL, NULL);
|
|
put_stringz(pktout, signame);
|
|
pq_push(s->ppl.out_pq, pktout);
|
|
|
|
return true;
|
|
}
|
|
|
|
void ssh2channel_send_terminal_size_change(SshChannel *sc, int w, int h)
|
|
{
|
|
struct ssh2_channel *c = container_of(sc, struct ssh2_channel, sc);
|
|
struct ssh2_connection_state *s = c->connlayer;
|
|
|
|
PktOut *pktout = ssh2_chanreq_init(c, "window-change", NULL, NULL);
|
|
put_uint32(pktout, w);
|
|
put_uint32(pktout, h);
|
|
put_uint32(pktout, 0); /* pixel width */
|
|
put_uint32(pktout, 0); /* pixel height */
|
|
pq_push(s->ppl.out_pq, pktout);
|
|
}
|
|
|
|
bool ssh2_connection_need_antispoof_prompt(struct ssh2_connection_state *s)
|
|
{
|
|
return !seat_set_trust_status(s->ppl.seat, false);
|
|
}
|