diff options
Diffstat (limited to 'svr-tcpfwd.c')
| -rw-r--r-- | svr-tcpfwd.c | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/svr-tcpfwd.c b/svr-tcpfwd.c new file mode 100644 index 0000000..d4dca6b --- /dev/null +++ b/svr-tcpfwd.c @@ -0,0 +1,290 @@ +/* + * Dropbear SSH + * + * Copyright (c) 2002,2003 Matt Johnston + * Copyright (c) 2004 by Mihnea Stoenescu + * All rights reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. */ + +#include "includes.h" +#include "ssh.h" +#include "tcpfwd.h" +#include "dbutil.h" +#include "session.h" +#include "buffer.h" +#include "packet.h" +#include "listener.h" +#include "runopts.h" + +#ifdef ENABLE_SVR_REMOTETCPFWD + +static void send_msg_request_success(); +static void send_msg_request_failure(); +static int svr_cancelremotetcp(); +static int svr_remotetcpreq(); +static int newtcpdirect(struct Channel * channel); + + +const struct ChanType svr_chan_tcpdirect = { + 1, /* sepfds */ + "direct-tcpip", + newtcpdirect, /* init */ + NULL, /* checkclose */ + NULL, /* reqhandler */ + NULL /* closehandler */ +}; + +static const struct ChanType svr_chan_tcpremote = { + 1, /* sepfds */ + "forwarded-tcpip", + NULL, + NULL, + NULL, + NULL +}; + +/* At the moment this is completely used for tcp code (with the name reflecting + * that). If new request types are added, this should be replaced with code + * similar to the request-switching in chansession.c */ +void recv_msg_global_request_remotetcp() { + + unsigned char* reqname = NULL; + unsigned int namelen; + unsigned int wantreply = 0; + int ret = DROPBEAR_FAILURE; + + TRACE(("enter recv_msg_global_request_remotetcp")) + + if (svr_opts.noremotetcp) { + TRACE(("leave recv_msg_global_request_remotetcp: remote tcp forwarding disabled")) + goto out; + } + + reqname = buf_getstring(ses.payload, &namelen); + wantreply = buf_getbool(ses.payload); + + if (namelen > MAX_NAME_LEN) { + TRACE(("name len is wrong: %d", namelen)) + goto out; + } + + if (strcmp("tcpip-forward", reqname) == 0) { + ret = svr_remotetcpreq(); + } else if (strcmp("cancel-tcpip-forward", reqname) == 0) { + ret = svr_cancelremotetcp(); + } else { + TRACE(("reqname isn't tcpip-forward: '%s'", reqname)) + } + +out: + if (wantreply) { + if (ret == DROPBEAR_SUCCESS) { + send_msg_request_success(); + } else { + send_msg_request_failure(); + } + } + + m_free(reqname); + + TRACE(("leave recv_msg_global_request")) +} + + +static void send_msg_request_success() { + + CHECKCLEARTOWRITE(); + buf_putbyte(ses.writepayload, SSH_MSG_REQUEST_SUCCESS); + encrypt_packet(); + +} + +static void send_msg_request_failure() { + + CHECKCLEARTOWRITE(); + buf_putbyte(ses.writepayload, SSH_MSG_REQUEST_FAILURE); + encrypt_packet(); + +} + +static int matchtcp(void* typedata1, void* typedata2) { + + const struct TCPListener *info1 = (struct TCPListener*)typedata1; + const struct TCPListener *info2 = (struct TCPListener*)typedata2; + + return (info1->listenport == info2->listenport) + && (info1->chantype == info2->chantype) + && (strcmp(info1->listenaddr, info2->listenaddr) == 0); +} + +static int svr_cancelremotetcp() { + + int ret = DROPBEAR_FAILURE; + unsigned char * bindaddr = NULL; + unsigned int addrlen; + unsigned int port; + struct Listener * listener = NULL; + struct TCPListener tcpinfo; + + TRACE(("enter cancelremotetcp")) + + bindaddr = buf_getstring(ses.payload, &addrlen); + if (addrlen > MAX_IP_LEN) { + TRACE(("addr len too long: %d", addrlen)) + goto out; + } + + port = buf_getint(ses.payload); + + tcpinfo.sendaddr = NULL; + tcpinfo.sendport = 0; + tcpinfo.listenaddr = bindaddr; + tcpinfo.listenport = port; + listener = get_listener(CHANNEL_ID_TCPFORWARDED, &tcpinfo, matchtcp); + if (listener) { + remove_listener( listener ); + ret = DROPBEAR_SUCCESS; + } + +out: + m_free(bindaddr); + TRACE(("leave cancelremotetcp")) + return ret; +} + +static int svr_remotetcpreq() { + + int ret = DROPBEAR_FAILURE; + unsigned char * bindaddr = NULL; + unsigned int addrlen; + struct TCPListener *tcpinfo = NULL; + unsigned int port; + + TRACE(("enter remotetcpreq")) + + bindaddr = buf_getstring(ses.payload, &addrlen); + if (addrlen > MAX_IP_LEN) { + TRACE(("addr len too long: %d", addrlen)) + goto out; + } + + port = buf_getint(ses.payload); + + if (port == 0) { + dropbear_log(LOG_INFO, "Server chosen tcpfwd ports are unsupported"); + goto out; + } + + if (port < 1 || port > 65535) { + TRACE(("invalid port: %d", port)) + goto out; + } + + if (!ses.allowprivport && port < IPPORT_RESERVED) { + TRACE(("can't assign port < 1024 for non-root")) + goto out; + } + + tcpinfo = (struct TCPListener*)m_malloc(sizeof(struct TCPListener)); + tcpinfo->sendaddr = NULL; + tcpinfo->sendport = 0; + tcpinfo->listenaddr = bindaddr; + tcpinfo->listenport = port; + tcpinfo->chantype = &svr_chan_tcpremote; + tcpinfo->tcp_type = forwarded; + + ret = listen_tcpfwd(tcpinfo); + +out: + if (ret == DROPBEAR_FAILURE) { + /* we only free it if a listener wasn't created, since the listener + * has to remember it if it's to be cancelled */ + m_free(bindaddr); + m_free(tcpinfo); + } + TRACE(("leave remotetcpreq")) + return ret; +} + +/* Called upon creating a new direct tcp channel (ie we connect out to an + * address */ +static int newtcpdirect(struct Channel * channel) { + + unsigned char* desthost = NULL; + unsigned int destport; + unsigned char* orighost = NULL; + unsigned int origport; + char portstring[NI_MAXSERV]; + int sock; + int len; + int err = SSH_OPEN_ADMINISTRATIVELY_PROHIBITED; + + if (svr_opts.nolocaltcp) { + TRACE(("leave newtcpdirect: local tcp forwarding disabled")) + goto out; + } + + desthost = buf_getstring(ses.payload, &len); + if (len > MAX_HOST_LEN) { + TRACE(("leave newtcpdirect: desthost too long")) + goto out; + } + + destport = buf_getint(ses.payload); + + orighost = buf_getstring(ses.payload, &len); + if (len > MAX_HOST_LEN) { + TRACE(("leave newtcpdirect: orighost too long")) + goto out; + } + + origport = buf_getint(ses.payload); + + /* best be sure */ + if (origport > 65535 || destport > 65535) { + TRACE(("leave newtcpdirect: port > 65535")) + goto out; + } + + snprintf(portstring, sizeof(portstring), "%d", destport); + sock = connect_remote(desthost, portstring, 1, NULL); + if (sock < 0) { + err = SSH_OPEN_CONNECT_FAILED; + TRACE(("leave newtcpdirect: sock failed")) + goto out; + } + + ses.maxfd = MAX(ses.maxfd, sock); + + /* We don't set readfd, that will get set after the connection's + * progress succeeds */ + channel->writefd = sock; + channel->initconn = 1; + + err = SSH_OPEN_IN_PROGRESS; + +out: + m_free(desthost); + m_free(orighost); + TRACE(("leave newtcpdirect: err %d", err)) + return err; +} + +#endif |