From a858eae93b4e020c5edabf092161ae9b791cef0d Mon Sep 17 00:00:00 2001 From: djm Date: Tue, 26 Jan 2010 02:26:22 +0000 Subject: [PATCH] - djm@cvs.openbsd.org 2010/01/26 01:28:35 [channels.c channels.h clientloop.c clientloop.h mux.c nchan.c ssh.c] rewrite ssh(1) multiplexing code to a more sensible protocol. The new multiplexing code uses channels for the listener and accepted control sockets to make the mux master non-blocking, so no stalls when processing messages from a slave. avoid use of fatal() in mux master protocol parsing so an errant slave process cannot take down a running master. implement requesting of port-forwards over multiplexed sessions. Any port forwards requested by the slave are added to those the master has established. add support for stdio forwarding ("ssh -W host:port ...") in mux slaves. document master/slave mux protocol so that other tools can use it to control a running ssh(1). Note: there are no guarantees that this protocol won't be incompatibly changed (though it is versioned). feedback Salvador Fandino, dtucker@ channel changes ok markus@ --- ChangeLog | 23 + channels.c | 214 ++++-- channels.h | 18 +- clientloop.c | 35 +- clientloop.h | 12 +- mux.c | 1938 ++++++++++++++++++++++++++++++++++++++------------ nchan.c | 21 +- ssh.c | 22 +- 8 files changed, 1725 insertions(+), 558 deletions(-) diff --git a/ChangeLog b/ChangeLog index 4334f676..b8535045 100644 --- a/ChangeLog +++ b/ChangeLog @@ -8,6 +8,29 @@ [roaming_client.c] s/long long unsigned/unsigned long long/, from tim via portable (Id sync only, change already in portable) + - djm@cvs.openbsd.org 2010/01/26 01:28:35 + [channels.c channels.h clientloop.c clientloop.h mux.c nchan.c ssh.c] + rewrite ssh(1) multiplexing code to a more sensible protocol. + + The new multiplexing code uses channels for the listener and + accepted control sockets to make the mux master non-blocking, so + no stalls when processing messages from a slave. + + avoid use of fatal() in mux master protocol parsing so an errant slave + process cannot take down a running master. + + implement requesting of port-forwards over multiplexed sessions. Any + port forwards requested by the slave are added to those the master has + established. + + add support for stdio forwarding ("ssh -W host:port ...") in mux slaves. + + document master/slave mux protocol so that other tools can use it to + control a running ssh(1). Note: there are no guarantees that this + protocol won't be incompatibly changed (though it is versioned). + + feedback Salvador Fandino, dtucker@ + channel changes ok markus@ 20100122 - (tim) [configure.ac] Due to constraints in Windows Sockets in terms of diff --git a/channels.c b/channels.c index e8589d8c..81261679 100644 --- a/channels.c +++ b/channels.c @@ -1,4 +1,4 @@ -/* $OpenBSD: channels.c,v 1.301 2010/01/11 01:39:46 dtucker Exp $ */ +/* $OpenBSD: channels.c,v 1.302 2010/01/26 01:28:35 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -239,7 +239,6 @@ channel_register_fds(Channel *c, int rfd, int wfd, int efd, c->rfd = rfd; c->wfd = wfd; c->sock = (rfd == wfd) ? rfd : -1; - c->ctl_fd = -1; /* XXX: set elsewhere */ c->efd = efd; c->extended_usage = extusage; @@ -328,6 +327,9 @@ channel_new(char *ctype, int type, int rfd, int wfd, int efd, c->output_filter = NULL; c->filter_ctx = NULL; c->filter_cleanup = NULL; + c->ctl_chan = -1; + c->mux_rcb = NULL; + c->mux_ctx = NULL; c->delayed = 1; /* prevent call to channel_post handler */ TAILQ_INIT(&c->status_confirms); debug("channel %d: new [%s]", found, remote_name); @@ -370,11 +372,10 @@ channel_close_fd(int *fdp) static void channel_close_fds(Channel *c) { - debug3("channel %d: close_fds r %d w %d e %d c %d", - c->self, c->rfd, c->wfd, c->efd, c->ctl_fd); + debug3("channel %d: close_fds r %d w %d e %d", + c->self, c->rfd, c->wfd, c->efd); channel_close_fd(&c->sock); - channel_close_fd(&c->ctl_fd); channel_close_fd(&c->rfd); channel_close_fd(&c->wfd); channel_close_fd(&c->efd); @@ -400,8 +401,6 @@ channel_free(Channel *c) if (c->sock != -1) shutdown(c->sock, SHUT_RDWR); - if (c->ctl_fd != -1) - shutdown(c->ctl_fd, SHUT_RDWR); channel_close_fds(c); buffer_free(&c->input); buffer_free(&c->output); @@ -523,6 +522,7 @@ channel_still_open(void) case SSH_CHANNEL_X11_LISTENER: case SSH_CHANNEL_PORT_LISTENER: case SSH_CHANNEL_RPORT_LISTENER: + case SSH_CHANNEL_MUX_LISTENER: case SSH_CHANNEL_CLOSED: case SSH_CHANNEL_AUTH_SOCKET: case SSH_CHANNEL_DYNAMIC: @@ -536,6 +536,7 @@ channel_still_open(void) case SSH_CHANNEL_OPENING: case SSH_CHANNEL_OPEN: case SSH_CHANNEL_X11_OPEN: + case SSH_CHANNEL_MUX_CLIENT: return 1; case SSH_CHANNEL_INPUT_DRAINING: case SSH_CHANNEL_OUTPUT_DRAINING: @@ -567,6 +568,8 @@ channel_find_open(void) case SSH_CHANNEL_X11_LISTENER: case SSH_CHANNEL_PORT_LISTENER: case SSH_CHANNEL_RPORT_LISTENER: + case SSH_CHANNEL_MUX_LISTENER: + case SSH_CHANNEL_MUX_CLIENT: case SSH_CHANNEL_OPENING: case SSH_CHANNEL_CONNECTING: case SSH_CHANNEL_ZOMBIE: @@ -617,6 +620,8 @@ channel_open_message(void) case SSH_CHANNEL_CLOSED: case SSH_CHANNEL_AUTH_SOCKET: case SSH_CHANNEL_ZOMBIE: + case SSH_CHANNEL_MUX_CLIENT: + case SSH_CHANNEL_MUX_LISTENER: continue; case SSH_CHANNEL_LARVAL: case SSH_CHANNEL_OPENING: @@ -627,12 +632,12 @@ channel_open_message(void) case SSH_CHANNEL_INPUT_DRAINING: case SSH_CHANNEL_OUTPUT_DRAINING: snprintf(buf, sizeof buf, - " #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %d)\r\n", + " #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cc %d)\r\n", c->self, c->remote_name, c->type, c->remote_id, c->istate, buffer_len(&c->input), c->ostate, buffer_len(&c->output), - c->rfd, c->wfd, c->ctl_fd); + c->rfd, c->wfd, c->ctl_chan); buffer_append(&buffer, buf, strlen(buf)); continue; default: @@ -839,9 +844,6 @@ channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset) FD_SET(c->efd, readset); } /* XXX: What about efd? races? */ - if (compat20 && c->ctl_fd != -1 && - c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN) - FD_SET(c->ctl_fd, readset); } /* ARGSUSED */ @@ -986,6 +988,28 @@ channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset) } } +static void +channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset) +{ + if (c->istate == CHAN_INPUT_OPEN && + buffer_check_alloc(&c->input, CHAN_RBUF)) + FD_SET(c->rfd, readset); + if (c->istate == CHAN_INPUT_WAIT_DRAIN) { + /* clear buffer immediately (discard any partial packet) */ + buffer_clear(&c->input); + chan_ibuf_empty(c); + /* Start output drain. XXX just kill chan? */ + chan_rcvd_oclose(c); + } + if (c->ostate == CHAN_OUTPUT_OPEN || + c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { + if (buffer_len(&c->output) > 0) + FD_SET(c->wfd, writeset); + else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) + chan_obuf_empty(c); + } +} + /* try to decode a socks4 header */ /* ARGSUSED */ static int @@ -1218,19 +1242,14 @@ channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset) } Channel * -channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect) +channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect, + int in, int out) { Channel *c; - int in, out; debug("channel_connect_stdio_fwd %s:%d", host_to_connect, port_to_connect); - in = dup(STDIN_FILENO); - out = dup(STDOUT_FILENO); - if (in < 0 || out < 0) - fatal("channel_connect_stdio_fwd: dup() in/out failed"); - c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "stdio-forward", /*nonblock*/0); @@ -1749,36 +1768,6 @@ channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset) return 1; } -/* ARGSUSED */ -static int -channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset) -{ - char buf[16]; - int len; - - /* Monitor control fd to detect if the slave client exits */ - if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) { - len = read(c->ctl_fd, buf, sizeof(buf)); - if (len < 0 && - (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) - return 1; - if (len <= 0) { - debug2("channel %d: ctl read<=0", c->self); - if (c->type != SSH_CHANNEL_OPEN) { - debug2("channel %d: not open", c->self); - chan_mark_dead(c); - return -1; - } else { - chan_read_failed(c); - chan_write_failed(c); - } - return -1; - } else - fatal("%s: unexpected data on ctl fd", __func__); - } - return 1; -} - static int channel_check_window(Channel *c) { @@ -1809,10 +1798,131 @@ channel_post_open(Channel *c, fd_set *readset, fd_set *writeset) if (!compat20) return; channel_handle_efd(c, readset, writeset); - channel_handle_ctl(c, readset, writeset); channel_check_window(c); } +static u_int +read_mux(Channel *c, u_int need) +{ + char buf[CHAN_RBUF]; + int len; + u_int rlen; + + if (buffer_len(&c->input) < need) { + rlen = need - buffer_len(&c->input); + len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF)); + if (len <= 0) { + if (errno != EINTR && errno != EAGAIN) { + debug2("channel %d: ctl read<=0 rfd %d len %d", + c->self, c->rfd, len); + chan_read_failed(c); + return 0; + } + } else + buffer_append(&c->input, buf, len); + } + return buffer_len(&c->input); +} + +static void +channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset) +{ + u_int need; + ssize_t len; + + if (!compat20) + fatal("%s: entered with !compat20", __func__); + + if (c->rfd != -1 && FD_ISSET(c->rfd, readset) && + (c->istate == CHAN_INPUT_OPEN || + c->istate == CHAN_INPUT_WAIT_DRAIN)) { + /* + * Don't not read past the precise end of packets to + * avoid disrupting fd passing. + */ + if (read_mux(c, 4) < 4) /* read header */ + return; + need = get_u32(buffer_ptr(&c->input)); +#define CHANNEL_MUX_MAX_PACKET (256 * 1024) + if (need > CHANNEL_MUX_MAX_PACKET) { + debug2("channel %d: packet too big %u > %u", + c->self, CHANNEL_MUX_MAX_PACKET, need); + chan_rcvd_oclose(c); + return; + } + if (read_mux(c, need + 4) < need + 4) /* read body */ + return; + if (c->mux_rcb(c) != 0) { + debug("channel %d: mux_rcb failed", c->self); + chan_mark_dead(c); + return; + } + } + + if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) && + buffer_len(&c->output) > 0) { + len = write(c->wfd, buffer_ptr(&c->output), + buffer_len(&c->output)); + if (len < 0 && (errno == EINTR || errno == EAGAIN)) + return; + if (len <= 0) { + chan_mark_dead(c); + return; + } + buffer_consume(&c->output, len); + } +} + +static void +channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset) +{ + Channel *nc; + struct sockaddr_storage addr; + socklen_t addrlen; + int newsock; + uid_t euid; + gid_t egid; + + if (!FD_ISSET(c->sock, readset)) + return; + + debug("multiplexing control connection"); + + /* + * Accept connection on control socket + */ + memset(&addr, 0, sizeof(addr)); + addrlen = sizeof(addr); + if ((newsock = accept(c->sock, (struct sockaddr*)&addr, + &addrlen)) == -1) { + error("%s accept: %s", __func__, strerror(errno)); + return; + } + + if (getpeereid(newsock, &euid, &egid) < 0) { + error("%s getpeereid failed: %s", __func__, + strerror(errno)); + close(newsock); + return; + } + if ((euid != 0) && (getuid() != euid)) { + error("multiplex uid mismatch: peer euid %u != uid %u", + (u_int)euid, (u_int)getuid()); + close(newsock); + return; + } + nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT, + newsock, newsock, -1, c->local_window_max, + c->local_maxpacket, 0, "mux-control", 1); + nc->mux_rcb = c->mux_rcb; + debug3("%s: new mux channel %d fd %d", __func__, + nc->self, nc->sock); + /* establish state */ + nc->mux_rcb(nc); + /* mux state transitions must not elicit protocol messages */ + nc->flags |= CHAN_LOCAL; +} + /* ARGSUSED */ static void channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset) @@ -1841,6 +1951,8 @@ channel_handler_init_20(void) channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener; channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting; channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic; + channel_pre[SSH_CHANNEL_MUX_LISTENER] = &channel_pre_listener; + channel_pre[SSH_CHANNEL_MUX_CLIENT] = &channel_pre_mux_client; channel_post[SSH_CHANNEL_OPEN] = &channel_post_open; channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener; @@ -1849,6 +1961,8 @@ channel_handler_init_20(void) channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener; channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting; channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open; + channel_post[SSH_CHANNEL_MUX_LISTENER] = &channel_post_mux_listener; + channel_post[SSH_CHANNEL_MUX_CLIENT] = &channel_post_mux_client; } static void diff --git a/channels.h b/channels.h index 79ebe047..cc71885f 100644 --- a/channels.h +++ b/channels.h @@ -1,4 +1,4 @@ -/* $OpenBSD: channels.h,v 1.102 2010/01/11 01:39:46 dtucker Exp $ */ +/* $OpenBSD: channels.h,v 1.103 2010/01/26 01:28:35 djm Exp $ */ /* * Author: Tatu Ylonen @@ -53,7 +53,9 @@ #define SSH_CHANNEL_CONNECTING 12 #define SSH_CHANNEL_DYNAMIC 13 #define SSH_CHANNEL_ZOMBIE 14 /* Almost dead. */ -#define SSH_CHANNEL_MAX_TYPE 15 +#define SSH_CHANNEL_MUX_LISTENER 15 /* Listener for mux conn. */ +#define SSH_CHANNEL_MUX_CLIENT 16 /* Conn. to mux slave */ +#define SSH_CHANNEL_MAX_TYPE 17 struct Channel; typedef struct Channel Channel; @@ -81,6 +83,9 @@ struct channel_connect { struct addrinfo *ai, *aitop; }; +/* Callbacks for mux channels back into client-specific code */ +typedef int mux_callback_fn(struct Channel *); + struct Channel { int type; /* channel type/state */ int self; /* my own channel identifier */ @@ -92,7 +97,7 @@ struct Channel { int wfd; /* write fd */ int efd; /* extended fd */ int sock; /* sock fd */ - int ctl_fd; /* control fd (client sharing) */ + int ctl_chan; /* control channel (multiplexed connections) */ int isatty; /* rfd is a tty */ int wfd_isatty; /* wfd is a tty */ int client_tty; /* (client) TTY has been requested */ @@ -142,6 +147,10 @@ struct Channel { /* non-blocking connect */ struct channel_connect connect_ctx; + + /* multiplexing protocol hook, called for each packet received */ + mux_callback_fn *mux_rcb; + void *mux_ctx; }; #define CHAN_EXTENDED_IGNORE 0 @@ -172,6 +181,7 @@ struct Channel { #define CHAN_CLOSE_RCVD 0x02 #define CHAN_EOF_SENT 0x04 #define CHAN_EOF_RCVD 0x08 +#define CHAN_LOCAL 0x10 #define CHAN_RBUF 16*1024 @@ -243,7 +253,7 @@ void channel_clear_adm_permitted_opens(void); void channel_print_adm_permitted_opens(void); int channel_input_port_forward_request(int, int); Channel *channel_connect_to(const char *, u_short, char *, char *); -Channel *channel_connect_stdio_fwd(const char*, u_short); +Channel *channel_connect_stdio_fwd(const char*, u_short, int, int); Channel *channel_connect_by_listen_address(u_short, char *, char *); int channel_request_remote_forwarding(const char *, u_short, const char *, u_short); diff --git a/clientloop.c b/clientloop.c index 5793a6e9..05f4720a 100644 --- a/clientloop.c +++ b/clientloop.c @@ -1,4 +1,4 @@ -/* $OpenBSD: clientloop.c,v 1.216 2010/01/09 05:04:24 djm Exp $ */ +/* $OpenBSD: clientloop.c,v 1.217 2010/01/26 01:28:35 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -121,7 +121,7 @@ extern int stdin_null_flag; extern int no_shell_flag; /* Control socket */ -extern int muxserver_sock; +extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */ /* * Name of the host we are connecting to. This is the name given on the @@ -146,7 +146,7 @@ static volatile sig_atomic_t received_signal = 0; static int in_non_blocking_mode = 0; /* Common data for the client loop code. */ -static volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */ +volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */ static int escape_char1; /* Escape character. (proto1 only) */ static int escape_pending1; /* Last character was an escape (proto1 only) */ static int last_was_cr; /* Last character was a newline. */ @@ -564,9 +564,6 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, if (packet_have_data_to_write()) FD_SET(connection_out, *writesetp); - if (muxserver_sock != -1) - FD_SET(muxserver_sock, *readsetp); - /* * Wait for something to happen. This will suspend the process until * some selected descriptor can be read, written, or has some other @@ -695,7 +692,7 @@ client_status_confirm(int type, Channel *c, void *ctx) /* XXX supress on mux _client_ quietmode */ tochan = options.log_level >= SYSLOG_LEVEL_ERROR && - c->ctl_fd != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; + c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; if (type == SSH2_MSG_CHANNEL_SUCCESS) { debug2("%s request accepted on channel %d", @@ -839,6 +836,7 @@ process_cmdline(void) while (isspace(*++s)) ; + /* XXX update list of forwards in options */ if (delete) { cancel_port = 0; cancel_host = hpdelim(&s); /* may be NULL */ @@ -936,7 +934,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr, escape_char); buffer_append(berr, string, strlen(string)); - if (c && c->ctl_fd != -1) { + if (c && c->ctl_chan != -1) { chan_read_failed(c); chan_write_failed(c); return 0; @@ -946,7 +944,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr, case 'Z' - 64: /* XXX support this for mux clients */ - if (c && c->ctl_fd != -1) { + if (c && c->ctl_chan != -1) { noescape: snprintf(string, sizeof string, "%c%c escape not available to " @@ -991,7 +989,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr, continue; case '&': - if (c && c->ctl_fd != -1) + if (c && c->ctl_chan != -1) goto noescape; /* * Detach the program (continue to serve @@ -1042,7 +1040,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr, continue; case '?': - if (c && c->ctl_fd != -1) { + if (c && c->ctl_chan != -1) { snprintf(string, sizeof string, "%c?\r\n\ Supported escape sequences:\r\n\ @@ -1091,7 +1089,7 @@ Supported escape sequences:\r\n\ continue; case 'C': - if (c && c->ctl_fd != -1) + if (c && c->ctl_chan != -1) goto noescape; process_cmdline(); continue; @@ -1327,8 +1325,6 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id) connection_in = packet_get_connection_in(); connection_out = packet_get_connection_out(); max_fd = MAX(connection_in, connection_out); - if (muxserver_sock != -1) - max_fd = MAX(max_fd, muxserver_sock); if (!compat20) { /* enable nonblocking unless tty */ @@ -1446,12 +1442,6 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id) /* Buffer input from the connection. */ client_process_net_input(readset); - /* Accept control connections. */ - if (muxserver_sock != -1 &&FD_ISSET(muxserver_sock, readset)) { - if (muxserver_accept_control()) - quit_pending = 1; - } - if (quit_pending) break; @@ -1859,9 +1849,8 @@ client_input_channel_req(int type, u_int32_t seq, void *ctxt) chan_rcvd_eow(c); } else if (strcmp(rtype, "exit-status") == 0) { exitval = packet_get_int(); - if (c->ctl_fd != -1) { - /* Dispatch to mux client */ - atomicio(vwrite, c->ctl_fd, &exitval, sizeof(exitval)); + if (c->ctl_chan != -1) { + mux_exit_message(c, exitval); success = 1; } else if (id == session_ident) { /* Record exit value of local session */ diff --git a/clientloop.h b/clientloop.h index 8bb874b3..0b8257b9 100644 --- a/clientloop.h +++ b/clientloop.h @@ -1,4 +1,4 @@ -/* $OpenBSD: clientloop.h,v 1.22 2008/06/12 15:19:17 djm Exp $ */ +/* $OpenBSD: clientloop.h,v 1.23 2010/01/26 01:28:35 djm Exp $ */ /* * Author: Tatu Ylonen @@ -56,18 +56,14 @@ typedef void global_confirm_cb(int, u_int32_t seq, void *); void client_register_global_confirm(global_confirm_cb *, void *); /* Multiplexing protocol version */ -#define SSHMUX_VER 2 +#define SSHMUX_VER 4 /* Multiplexing control protocol flags */ #define SSHMUX_COMMAND_OPEN 1 /* Open new connection */ #define SSHMUX_COMMAND_ALIVE_CHECK 2 /* Check master is alive */ #define SSHMUX_COMMAND_TERMINATE 3 /* Ask master to exit */ - -#define SSHMUX_FLAG_TTY (1) /* Request tty on open */ -#define SSHMUX_FLAG_SUBSYS (1<<1) /* Subsystem request on open */ -#define SSHMUX_FLAG_X11_FWD (1<<2) /* Request X11 forwarding */ -#define SSHMUX_FLAG_AGENT_FWD (1<<3) /* Request agent forwarding */ +#define SSHMUX_COMMAND_STDIO_FWD 4 /* Open stdio fwd (ssh -W) */ void muxserver_listen(void); -int muxserver_accept_control(void); void muxclient(const char *); +void mux_exit_message(Channel *, int); diff --git a/mux.c b/mux.c index 239edd5f..dcd6dc02 100644 --- a/mux.c +++ b/mux.c @@ -1,4 +1,4 @@ -/* $OpenBSD: mux.c,v 1.9 2010/01/09 05:04:24 djm Exp $ */ +/* $OpenBSD: mux.c,v 1.10 2010/01/26 01:28:35 djm Exp $ */ /* * Copyright (c) 2002-2008 Damien Miller * @@ -17,25 +17,21 @@ /* ssh session multiplexing support */ -#include "includes.h" - /* * TODO: - * 1. partial reads in muxserver_accept_control (maybe make channels - * from accepted connections) - * 2. Better signalling from master to slave, especially passing of + * - Better signalling from master to slave, especially passing of * error messages - * 3. Better fall-back from mux slave error to new connection. - * 3. Add/delete forwardings via slave - * 4. ExitOnForwardingFailure (after #3 obviously) - * 5. Maybe extension mechanisms for multi-X11/multi-agent forwarding - * 6. Document the mux mini-protocol somewhere. - * 7. Support ~^Z in mux slaves. - * 8. Inspect or control sessions in master. - * 9. If we ever support the "signal" channel request, send signals on - * sessions in master. + * - Better fall-back from mux slave error to new connection. + * - ExitOnForwardingFailure + * - Maybe extension mechanisms for multi-X11/multi-agent forwarding + * - Support ~^Z in mux slaves. + * - Inspect or control sessions in master. + * - If we ever support the "signal" channel request, send signals on + * sessions in master. */ +#include "includes.h" + #include #include #include @@ -55,6 +51,14 @@ #include #endif +#ifdef HAVE_POLL_H +#include +#else +# ifdef HAVE_SYS_POLL_H +# include +# endif +#endif + #ifdef HAVE_UTIL_H # include #endif @@ -88,13 +92,16 @@ extern int stdin_null_flag; extern char *host; extern int subsystem_flag; extern Buffer command; +extern volatile sig_atomic_t quit_pending; +extern char *stdio_forward_host; +extern int stdio_forward_port; /* Context for session open confirmation callback */ struct mux_session_confirm_ctx { - int want_tty; - int want_subsys; - int want_x_fwd; - int want_agent_fwd; + u_int want_tty; + u_int want_subsys; + u_int want_x_fwd; + u_int want_agent_fwd; Buffer cmd; char *term; struct termios tio; @@ -104,6 +111,9 @@ struct mux_session_confirm_ctx { /* fd to control socket */ int muxserver_sock = -1; +/* client request id */ +u_int muxclient_request_id = 0; + /* Multiplexing control command */ u_int muxclient_command = 0; @@ -113,269 +123,234 @@ static volatile sig_atomic_t muxclient_terminate = 0; /* PID of multiplex server */ static u_int muxserver_pid = 0; +static Channel *mux_listener_channel = NULL; -/* ** Multiplexing master support */ - -/* Prepare a mux master to listen on a Unix domain socket. */ -void -muxserver_listen(void) -{ - struct sockaddr_un addr; - mode_t old_umask; - int addr_len; - - if (options.control_path == NULL || - options.control_master == SSHCTL_MASTER_NO) - return; - - debug("setting up multiplex master socket"); - - memset(&addr, '\0', sizeof(addr)); - addr.sun_family = AF_UNIX; - addr_len = offsetof(struct sockaddr_un, sun_path) + - strlen(options.control_path) + 1; - - if (strlcpy(addr.sun_path, options.control_path, - sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) - fatal("ControlPath too long"); +struct mux_master_state { + int hello_rcvd; +}; - if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) - fatal("%s socket(): %s", __func__, strerror(errno)); +/* mux protocol messages */ +#define MUX_MSG_HELLO 0x00000001 +#define MUX_C_NEW_SESSION 0x10000002 +#define MUX_C_ALIVE_CHECK 0x10000004 +#define MUX_C_TERMINATE 0x10000005 +#define MUX_C_OPEN_FWD 0x10000006 +#define MUX_C_CLOSE_FWD 0x10000007 +#define MUX_C_NEW_STDIO_FWD 0x10000008 +#define MUX_S_OK 0x80000001 +#define MUX_S_PERMISSION_DENIED 0x80000002 +#define MUX_S_FAILURE 0x80000003 +#define MUX_S_EXIT_MESSAGE 0x80000004 +#define MUX_S_ALIVE 0x80000005 +#define MUX_S_SESSION_OPENED 0x80000006 + +/* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ +#define MUX_FWD_LOCAL 1 +#define MUX_FWD_REMOTE 2 +#define MUX_FWD_DYNAMIC 3 + +static void mux_session_confirm(int, void *); + +static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *); +static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *); +static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *); +static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *); +static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *); +static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *); +static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *); + +static const struct { + u_int type; + int (*handler)(u_int, Channel *, Buffer *, Buffer *); +} mux_master_handlers[] = { + { MUX_MSG_HELLO, process_mux_master_hello }, + { MUX_C_NEW_SESSION, process_mux_new_session }, + { MUX_C_ALIVE_CHECK, process_mux_alive_check }, + { MUX_C_TERMINATE, process_mux_terminate }, + { MUX_C_OPEN_FWD, process_mux_open_fwd }, + { MUX_C_CLOSE_FWD, process_mux_close_fwd }, + { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, + { 0, NULL } +}; - old_umask = umask(0177); - if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) { - muxserver_sock = -1; - if (errno == EINVAL || errno == EADDRINUSE) { - error("ControlSocket %s already exists, " - "disabling multiplexing", options.control_path); - close(muxserver_sock); - muxserver_sock = -1; - xfree(options.control_path); - options.control_path = NULL; - options.control_master = SSHCTL_MASTER_NO; - return; - } else - fatal("%s bind(): %s", __func__, strerror(errno)); +/* Cleanup callback fired on closure of mux slave _session_ channel */ +/* ARGSUSED */ +static void +mux_master_session_cleanup_cb(int cid, void *unused) +{ + Channel *cc, *c = channel_by_id(cid); + + debug3("%s: entering for channel %d", __func__, cid); + if (c == NULL) + fatal("%s: channel_by_id(%i) == NULL", __func__, cid); + if (c->ctl_chan != -1) { + if ((cc = channel_by_id(c->ctl_chan)) == NULL) + fatal("%s: channel %d missing control channel %d", + __func__, c->self, c->ctl_chan); + c->ctl_chan = -1; + cc->remote_id = -1; + chan_rcvd_oclose(cc); } - umask(old_umask); - - if (listen(muxserver_sock, 64) == -1) - fatal("%s listen(): %s", __func__, strerror(errno)); - - set_nonblock(muxserver_sock); + channel_cancel_cleanup(c->self); } -/* Callback on open confirmation in mux master for a mux client session. */ +/* Cleanup callback fired on closure of mux slave _control_ channel */ +/* ARGSUSED */ static void -mux_session_confirm(int id, void *arg) +mux_master_control_cleanup_cb(int cid, void *unused) { - struct mux_session_confirm_ctx *cctx = arg; - const char *display; - Channel *c; - int i; - - if (cctx == NULL) - fatal("%s: cctx == NULL", __func__); - if ((c = channel_lookup(id)) == NULL) - fatal("%s: no channel for id %d", __func__, id); - - display = getenv("DISPLAY"); - if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { - char *proto, *data; - /* Get reasonable local authentication information. */ - client_x11_get_proto(display, options.xauth_location, - options.forward_x11_trusted, &proto, &data); - /* Request forwarding with authentication spoofing. */ - debug("Requesting X11 forwarding with authentication spoofing."); - x11_request_forwarding_with_spoofing(id, display, proto, data); - /* XXX wait for reply */ - } - - if (cctx->want_agent_fwd && options.forward_agent) { - debug("Requesting authentication agent forwarding."); - channel_request_start(id, "auth-agent-req@openssh.com", 0); - packet_send(); + Channel *sc, *c = channel_by_id(cid); + + debug3("%s: entering for channel %d", __func__, cid); + if (c == NULL) + fatal("%s: channel_by_id(%i) == NULL", __func__, cid); + if (c->remote_id != -1) { + if ((sc = channel_by_id(c->remote_id)) == NULL) + debug2("%s: channel %d n session channel %d", + __func__, c->self, c->remote_id); + c->remote_id = -1; + sc->ctl_chan = -1; + chan_mark_dead(sc); } - - client_session2_setup(id, cctx->want_tty, cctx->want_subsys, - cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); - - c->open_confirm_ctx = NULL; - buffer_free(&cctx->cmd); - xfree(cctx->term); - if (cctx->env != NULL) { - for (i = 0; cctx->env[i] != NULL; i++) - xfree(cctx->env[i]); - xfree(cctx->env); - } - xfree(cctx); + channel_cancel_cleanup(c->self); } -/* - * Accept a connection on the mux master socket and process the - * client's request. Returns flag indicating whether mux master should - * begin graceful close. - */ -int -muxserver_accept_control(void) +/* Check mux client environment variables before passing them to mux master. */ +static int +env_permitted(char *env) { - Buffer m; - Channel *c; - int client_fd, new_fd[3], ver, allowed, window, packetmax; - socklen_t addrlen; - struct sockaddr_storage addr; - struct mux_session_confirm_ctx *cctx; - char *cmd; - u_int i, j, len, env_len, mux_command, flags, escape_char; - uid_t euid; - gid_t egid; - int start_close = 0; - - /* - * Accept connection on control socket - */ - memset(&addr, 0, sizeof(addr)); - addrlen = sizeof(addr); - if ((client_fd = accept(muxserver_sock, - (struct sockaddr*)&addr, &addrlen)) == -1) { - error("%s accept: %s", __func__, strerror(errno)); - return 0; - } + int i, ret; + char name[1024], *cp; - if (getpeereid(client_fd, &euid, &egid) < 0) { - error("%s getpeereid failed: %s", __func__, strerror(errno)); - close(client_fd); + if ((cp = strchr(env, '=')) == NULL || cp == env) return 0; - } - if ((euid != 0) && (getuid() != euid)) { - error("control mode uid mismatch: peer euid %u != uid %u", - (u_int) euid, (u_int) getuid()); - close(client_fd); + ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); + if (ret <= 0 || (size_t)ret >= sizeof(name)) { + error("env_permitted: name '%.100s...' too long", env); return 0; } - /* XXX handle asynchronously */ - unset_nonblock(client_fd); + for (i = 0; i < options.num_send_env; i++) + if (match_pattern(name, options.send_env[i])) + return 1; + + return 0; +} + +/* Mux master protocol message handlers */ - /* Read command */ - buffer_init(&m); - if (ssh_msg_recv(client_fd, &m) == -1) { - error("%s: client msg_recv failed", __func__); - close(client_fd); - buffer_free(&m); - return 0; +static int +process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + u_int ver; + struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; + + if (state == NULL) + fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); + if (state->hello_rcvd) { + error("%s: HELLO received twice", __func__); + return -1; } - if ((ver = buffer_get_char(&m)) != SSHMUX_VER) { - error("%s: wrong client version %d", __func__, ver); - buffer_free(&m); - close(client_fd); - return 0; + if (buffer_get_int_ret(&ver, m) != 0) { + malf: + error("%s: malformed message", __func__); + return -1; } + if (ver != SSHMUX_VER) { + error("Unsupported multiplexing protocol version %d " + "(expected %d)", ver, SSHMUX_VER); + return -1; + } + debug2("%s: channel %d slave version %u", __func__, c->self, ver); - allowed = 1; - mux_command = buffer_get_int(&m); - flags = buffer_get_int(&m); - - buffer_clear(&m); + /* No extensions are presently defined */ + while (buffer_len(m) > 0) { + char *name = buffer_get_string_ret(m, NULL); + char *value = buffer_get_string_ret(m, NULL); - switch (mux_command) { - case SSHMUX_COMMAND_OPEN: - if (options.control_master == SSHCTL_MASTER_ASK || - options.control_master == SSHCTL_MASTER_AUTO_ASK) - allowed = ask_permission("Allow shared connection " - "to %s? ", host); - /* continue below */ - break; - case SSHMUX_COMMAND_TERMINATE: - if (options.control_master == SSHCTL_MASTER_ASK || - options.control_master == SSHCTL_MASTER_AUTO_ASK) - allowed = ask_permission("Terminate shared connection " - "to %s? ", host); - if (allowed) - start_close = 1; - /* FALLTHROUGH */ - case SSHMUX_COMMAND_ALIVE_CHECK: - /* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */ - buffer_clear(&m); - buffer_put_int(&m, allowed); - buffer_put_int(&m, getpid()); - if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) { - error("%s: client msg_send failed", __func__); - close(client_fd); - buffer_free(&m); - return start_close; + if (name == NULL || value == NULL) { + if (name != NULL) + xfree(name); + goto malf; } - buffer_free(&m); - close(client_fd); - return start_close; - default: - error("Unsupported command %d", mux_command); - buffer_free(&m); - close(client_fd); - return 0; + debug2("Unrecognised slave extension \"%s\"", name); + xfree(name); + xfree(value); } + state->hello_rcvd = 1; + return 0; +} + +static int +process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + Channel *nc; + struct mux_session_confirm_ctx *cctx; + char *reserved, *cmd, *cp; + u_int i, j, len, env_len, escape_char, window, packetmax; + int new_fd[3]; /* Reply for SSHMUX_COMMAND_OPEN */ - buffer_clear(&m); - buffer_put_int(&m, allowed); - buffer_put_int(&m, getpid()); - if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) { - error("%s: client msg_send failed", __func__); - close(client_fd); - buffer_free(&m); - return 0; + cctx = xcalloc(1, sizeof(*cctx)); + cctx->term = NULL; + cmd = reserved = NULL; + if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&cctx->want_tty, m) != 0 || + buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || + buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || + buffer_get_int_ret(&cctx->want_subsys, m) != 0 || + buffer_get_int_ret(&escape_char, m) != 0 || + (cctx->term = buffer_get_string_ret(m, &len)) == NULL || + (cmd = buffer_get_string_ret(m, &len)) == NULL) { + malf: + if (cmd != NULL) + xfree(cmd); + if (reserved != NULL) + xfree(reserved); + if (cctx->term != NULL) + xfree(cctx->term); + error("%s: malformed message", __func__); + return -1; } - - if (!allowed) { - error("Refused control connection"); - close(client_fd); - buffer_free(&m); - return 0; + xfree(reserved); + reserved = NULL; + + cctx->env = NULL; + env_len = 0; + while (buffer_len(m) > 0) { +#define MUX_MAX_ENV_VARS 4096 + if ((cp = buffer_get_string_ret(m, &len)) == NULL) { + xfree(cmd); + goto malf; + } + if (!env_permitted(cp)) { + xfree(cp); + continue; + } + cctx->env = xrealloc(cctx->env, env_len + 2, + sizeof(*cctx->env)); + cctx->env[env_len++] = cp; + cctx->env[env_len] = NULL; + if (env_len > MUX_MAX_ENV_VARS) { + error(">%d environment variables received, ignoring " + "additional", MUX_MAX_ENV_VARS); + break; + } } - buffer_clear(&m); - if (ssh_msg_recv(client_fd, &m) == -1) { - error("%s: client msg_recv failed", __func__); - close(client_fd); - buffer_free(&m); - return 0; - } - if ((ver = buffer_get_char(&m)) != SSHMUX_VER) { - error("%s: wrong client version %d", __func__, ver); - buffer_free(&m); - close(client_fd); - return 0; - } + debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " + "term \"%s\", cmd \"%s\", env %u", __func__, c->self, + cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, + cctx->want_subsys, cctx->term, cmd, env_len); - cctx = xcalloc(1, sizeof(*cctx)); - cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0; - cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0; - cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0; - cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0; - cctx->term = buffer_get_string(&m, &len); - escape_char = buffer_get_int(&m); - - cmd = buffer_get_string(&m, &len); buffer_init(&cctx->cmd); buffer_append(&cctx->cmd, cmd, strlen(cmd)); - - env_len = buffer_get_int(&m); - env_len = MIN(env_len, 4096); - debug3("%s: receiving %d env vars", __func__, env_len); - if (env_len != 0) { - cctx->env = xcalloc(env_len + 1, sizeof(*cctx->env)); - for (i = 0; i < env_len; i++) - cctx->env[i] = buffer_get_string(&m, &len); - cctx->env[i] = NULL; - } - - debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__, - cctx->want_tty, cctx->want_subsys, cmd); xfree(cmd); + cmd = NULL; /* Gather fds from client */ for(i = 0; i < 3; i++) { - if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) { + if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { error("%s: failed to receive fd %d from slave", __func__, i); for (j = 0; j < i; j++) @@ -386,37 +361,56 @@ muxserver_accept_control(void) xfree(cctx->env); xfree(cctx->term); buffer_free(&cctx->cmd); - close(client_fd); xfree(cctx); - return 0; + + /* prepare reply */ + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, + "did not receive file descriptors"); + return -1; } } - debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__, + debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, new_fd[0], new_fd[1], new_fd[2]); - /* Try to pick up ttymodes from client before it goes raw */ - if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) - error("%s: tcgetattr: %s", __func__, strerror(errno)); - - /* This roundtrip is just for synchronisation of ttymodes */ - buffer_clear(&m); - if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) { - error("%s: client msg_send failed", __func__); - close(client_fd); + /* XXX support multiple child sessions in future */ + if (c->remote_id != -1) { + debug2("%s: session already open", __func__); + /* prepare reply */ + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Multiple sessions not supported"); + cleanup: close(new_fd[0]); close(new_fd[1]); close(new_fd[2]); - buffer_free(&m); xfree(cctx->term); if (env_len != 0) { for (i = 0; i < env_len; i++) xfree(cctx->env[i]); xfree(cctx->env); } + buffer_free(&cctx->cmd); return 0; } - buffer_free(&m); + + if (options.control_master == SSHCTL_MASTER_ASK || + options.control_master == SSHCTL_MASTER_AUTO_ASK) { + if (!ask_permission("Allow shared connection to %s? ", host)) { + debug2("%s: session refused by user", __func__); + /* prepare reply */ + buffer_put_int(r, MUX_S_PERMISSION_DENIED); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Permission denied"); + goto cleanup; + } + } + + /* Try to pick up ttymodes from client before it goes raw */ + if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) + error("%s: tcgetattr: %s", __func__, strerror(errno)); /* enable nonblocking unless tty */ if (!isatty(new_fd[0])) @@ -426,257 +420,1084 @@ muxserver_accept_control(void) if (!isatty(new_fd[2])) set_nonblock(new_fd[2]); - set_nonblock(client_fd); - window = CHAN_SES_WINDOW_DEFAULT; packetmax = CHAN_SES_PACKET_DEFAULT; if (cctx->want_tty) { window >>= 1; packetmax >>= 1; } - - c = channel_new("session", SSH_CHANNEL_OPENING, + + nc = channel_new("session", SSH_CHANNEL_OPENING, new_fd[0], new_fd[1], new_fd[2], window, packetmax, CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); - c->ctl_fd = client_fd; + nc->ctl_chan = c->self; /* link session -> control channel */ + c->remote_id = nc->self; /* link control -> session channel */ + if (cctx->want_tty && escape_char != 0xffffffff) { - channel_register_filter(c->self, + channel_register_filter(nc->self, client_simple_escape_filter, NULL, client_filter_cleanup, client_new_escape_filter_ctx((int)escape_char)); } - debug3("%s: channel_new: %d", __func__, c->self); + debug2("%s: channel_new: %d linked to control channel %d", + __func__, nc->self, nc->ctl_chan); - channel_send_open(c->self); - channel_register_open_confirm(c->self, mux_session_confirm, cctx); - return 0; -} + channel_send_open(nc->self); + channel_register_open_confirm(nc->self, mux_session_confirm, cctx); + channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 0); -/* ** Multiplexing client support */ + /* prepare reply */ + /* XXX defer until mux_session_confirm() fires */ + buffer_put_int(r, MUX_S_SESSION_OPENED); + buffer_put_int(r, rid); + buffer_put_int(r, nc->self); -/* Exit signal handler */ -static void -control_client_sighandler(int signo) -{ - muxclient_terminate = signo; + return 0; } -/* - * Relay signal handler - used to pass some signals from mux client to - * mux master. - */ -static void -control_client_sigrelay(int signo) +static int +process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) { - int save_errno = errno; + debug2("%s: channel %d: alive check", __func__, c->self); - if (muxserver_pid > 1) - kill(muxserver_pid, signo); + /* prepare reply */ + buffer_put_int(r, MUX_S_ALIVE); + buffer_put_int(r, rid); + buffer_put_int(r, (u_int)getpid()); - errno = save_errno; + return 0; } -/* Check mux client environment variables before passing them to mux master. */ static int -env_permitted(char *env) +process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) { - int i, ret; - char name[1024], *cp; - - if ((cp = strchr(env, '=')) == NULL || cp == env) - return (0); - ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); - if (ret <= 0 || (size_t)ret >= sizeof(name)) - fatal("env_permitted: name '%.100s...' too long", env); - - for (i = 0; i < options.num_send_env; i++) - if (match_pattern(name, options.send_env[i])) - return (1); + debug2("%s: channel %d: terminate request", __func__, c->self); + + if (options.control_master == SSHCTL_MASTER_ASK || + options.control_master == SSHCTL_MASTER_AUTO_ASK) { + if (!ask_permission("Terminate shared connection to %s? ", + host)) { + debug2("%s: termination refused by user", __func__); + buffer_put_int(r, MUX_S_PERMISSION_DENIED); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Permission denied"); + return 0; + } + } - return (0); + quit_pending = 1; + buffer_put_int(r, MUX_S_OK); + buffer_put_int(r, rid); + /* XXX exit happens too soon - message never makes it to client */ + return 0; } -/* Multiplex client main loop. */ -void -muxclient(const char *path) +static char * +format_forward(u_int ftype, Forward *fwd) { - struct sockaddr_un addr; - int i, r, fd, sock, exitval[2], num_env, addr_len; - Buffer m; - char *term; - extern char **environ; - u_int allowed, flags; - - if (muxclient_command == 0) - muxclient_command = SSHMUX_COMMAND_OPEN; - - switch (options.control_master) { - case SSHCTL_MASTER_AUTO: - case SSHCTL_MASTER_AUTO_ASK: - debug("auto-mux: Trying existing master"); - /* FALLTHROUGH */ - case SSHCTL_MASTER_NO: + char *ret; + + switch (ftype) { + case MUX_FWD_LOCAL: + xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", + (fwd->listen_host == NULL) ? + (options.gateway_ports ? "*" : "LOCALHOST") : + fwd->listen_host, fwd->listen_port, + fwd->connect_host, fwd->connect_port); + break; + case MUX_FWD_DYNAMIC: + xasprintf(&ret, "dynamic forward %.200s:%d -> *", + (fwd->listen_host == NULL) ? + (options.gateway_ports ? "*" : "LOCALHOST") : + fwd->listen_host, fwd->listen_port); + break; + case MUX_FWD_REMOTE: + xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", + (fwd->listen_host == NULL) ? + "LOCALHOST" : fwd->listen_host, + fwd->listen_port, + fwd->connect_host, fwd->connect_port); break; default: - return; + fatal("%s: unknown forward type %u", __func__, ftype); } + return ret; +} - memset(&addr, '\0', sizeof(addr)); - addr.sun_family = AF_UNIX; - addr_len = offsetof(struct sockaddr_un, sun_path) + - strlen(path) + 1; +static int +compare_host(const char *a, const char *b) +{ + if (a == NULL && b == NULL) + return 1; + if (a == NULL || b == NULL) + return 0; + return strcmp(a, b) == 0; +} - if (strlcpy(addr.sun_path, path, - sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) - fatal("ControlPath too long"); +static int +compare_forward(Forward *a, Forward *b) +{ + if (!compare_host(a->listen_host, b->listen_host)) + return 0; + if (a->listen_port != b->listen_port) + return 0; + if (!compare_host(a->connect_host, b->connect_host)) + return 0; + if (a->connect_port != b->connect_port) + return 0; - if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) - fatal("%s socket(): %s", __func__, strerror(errno)); + return 1; +} - if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) { - if (muxclient_command != SSHMUX_COMMAND_OPEN) { - fatal("Control socket connect(%.100s): %s", path, - strerror(errno)); +static int +process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + Forward fwd; + char *fwd_desc = NULL; + u_int ftype; + int i, ret = 0, freefwd = 1; + + fwd.listen_host = fwd.connect_host = NULL; + if (buffer_get_int_ret(&ftype, m) != 0 || + (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&fwd.listen_port, m) != 0 || + (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&fwd.connect_port, m) != 0) { + error("%s: malformed message", __func__); + ret = -1; + goto out; + } + + if (*fwd.listen_host == '\0') { + xfree(fwd.listen_host); + fwd.listen_host = NULL; + } + if (*fwd.connect_host == '\0') { + xfree(fwd.connect_host); + fwd.connect_host = NULL; + } + + debug2("%s: channel %d: request %s", __func__, c->self, + (fwd_desc = format_forward(ftype, &fwd))); + + if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && + ftype != MUX_FWD_DYNAMIC) { + logit("%s: invalid forwarding type %u", __func__, ftype); + invalid: + xfree(fwd.listen_host); + xfree(fwd.connect_host); + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Invalid forwarding request"); + return 0; + } + /* XXX support rport0 forwarding with reply of port assigned */ + if (fwd.listen_port == 0 || fwd.listen_port >= 65536) { + logit("%s: invalid listen port %u", __func__, + fwd.listen_port); + goto invalid; + } + if (fwd.connect_port >= 65536 || (ftype != MUX_FWD_DYNAMIC && + ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { + logit("%s: invalid connect port %u", __func__, + fwd.connect_port); + goto invalid; + } + if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL) { + logit("%s: missing connect host", __func__); + goto invalid; + } + + /* Skip forwards that have already been requested */ + switch (ftype) { + case MUX_FWD_LOCAL: + case MUX_FWD_DYNAMIC: + for (i = 0; i < options.num_local_forwards; i++) { + if (compare_forward(&fwd, + options.local_forwards + i)) { + exists: + debug2("%s: found existing forwarding", + __func__); + buffer_put_int(r, MUX_S_OK); + buffer_put_int(r, rid); + goto out; + } } - if (errno == ENOENT) - debug("Control socket \"%.100s\" does not exist", path); - else { - error("Control socket connect(%.100s): %s", path, - strerror(errno)); + break; + case MUX_FWD_REMOTE: + for (i = 0; i < options.num_remote_forwards; i++) { + if (compare_forward(&fwd, + options.remote_forwards + i)) + goto exists; } - close(sock); - return; + break; } - if (stdin_null_flag) { - if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1) - fatal("open(/dev/null): %s", strerror(errno)); - if (dup2(fd, STDIN_FILENO) == -1) - fatal("dup2: %s", strerror(errno)); - if (fd > STDERR_FILENO) - close(fd); + if (options.control_master == SSHCTL_MASTER_ASK || + options.control_master == SSHCTL_MASTER_AUTO_ASK) { + if (!ask_permission("Open %s on %s?", fwd_desc, host)) { + debug2("%s: forwarding refused by user", __func__); + buffer_put_int(r, MUX_S_PERMISSION_DENIED); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Permission denied"); + goto out; + } } - term = getenv("TERM"); + if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { + if (options.num_local_forwards + 1 >= + SSH_MAX_FORWARDS_PER_DIRECTION || + channel_setup_local_fwd_listener(fwd.listen_host, + fwd.listen_port, fwd.connect_host, fwd.connect_port, + options.gateway_ports) < 0) { + fail: + logit("slave-requested %s failed", fwd_desc); + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Port forwarding failed"); + goto out; + } + add_local_forward(&options, &fwd); + freefwd = 0; + } else { + /* XXX wait for remote to confirm */ + if (options.num_remote_forwards + 1 >= + SSH_MAX_FORWARDS_PER_DIRECTION || + channel_request_remote_forwarding(fwd.listen_host, + fwd.listen_port, fwd.connect_host, fwd.connect_port) < 0) + goto fail; + add_remote_forward(&options, &fwd); + freefwd = 0; + } + buffer_put_int(r, MUX_S_OK); + buffer_put_int(r, rid); + out: + if (fwd_desc != NULL) + xfree(fwd_desc); + if (freefwd) { + if (fwd.listen_host != NULL) + xfree(fwd.listen_host); + if (fwd.connect_host != NULL) + xfree(fwd.connect_host); + } + return ret; +} - flags = 0; - if (tty_flag) - flags |= SSHMUX_FLAG_TTY; - if (subsystem_flag) - flags |= SSHMUX_FLAG_SUBSYS; - if (options.forward_x11) - flags |= SSHMUX_FLAG_X11_FWD; - if (options.forward_agent) - flags |= SSHMUX_FLAG_AGENT_FWD; +static int +process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + Forward fwd; + char *fwd_desc = NULL; + u_int ftype; + int ret = 0; + + fwd.listen_host = fwd.connect_host = NULL; + if (buffer_get_int_ret(&ftype, m) != 0 || + (fwd.listen_host = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&fwd.listen_port, m) != 0 || + (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&fwd.connect_port, m) != 0) { + error("%s: malformed message", __func__); + ret = -1; + goto out; + } - signal(SIGPIPE, SIG_IGN); + if (*fwd.listen_host == '\0') { + xfree(fwd.listen_host); + fwd.listen_host = NULL; + } + if (*fwd.connect_host == '\0') { + xfree(fwd.connect_host); + fwd.connect_host = NULL; + } + + debug2("%s: channel %d: request %s", __func__, c->self, + (fwd_desc = format_forward(ftype, &fwd))); + + /* XXX implement this */ + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, "unimplemented"); + + out: + if (fwd_desc != NULL) + xfree(fwd_desc); + if (fwd.listen_host != NULL) + xfree(fwd.listen_host); + if (fwd.connect_host != NULL) + xfree(fwd.connect_host); + + return ret; +} + +static int +process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + Channel *nc; + char *reserved, *chost; + u_int cport, i, j; + int new_fd[2]; + + chost = reserved = NULL; + if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || + (chost = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&cport, m) != 0) { + if (reserved != NULL) + xfree(reserved); + if (chost != NULL) + xfree(chost); + error("%s: malformed message", __func__); + return -1; + } + xfree(reserved); + + debug2("%s: channel %d: request stdio fwd to %s:%u", + __func__, c->self, chost, cport); + + /* Gather fds from client */ + for(i = 0; i < 2; i++) { + if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { + error("%s: failed to receive fd %d from slave", + __func__, i); + for (j = 0; j < i; j++) + close(new_fd[j]); + xfree(chost); + + /* prepare reply */ + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, + "did not receive file descriptors"); + return -1; + } + } + debug3("%s: got fds stdin %d, stdout %d", __func__, + new_fd[0], new_fd[1]); + + /* XXX support multiple child sessions in future */ + if (c->remote_id != -1) { + debug2("%s: session already open", __func__); + /* prepare reply */ + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Multiple sessions not supported"); + cleanup: + close(new_fd[0]); + close(new_fd[1]); + xfree(chost); + return 0; + } + + if (options.control_master == SSHCTL_MASTER_ASK || + options.control_master == SSHCTL_MASTER_AUTO_ASK) { + if (!ask_permission("Allow forward to to %s:%u? ", + chost, cport)) { + debug2("%s: stdio fwd refused by user", __func__); + /* prepare reply */ + buffer_put_int(r, MUX_S_PERMISSION_DENIED); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Permission denied"); + goto cleanup; + } + } + + /* enable nonblocking unless tty */ + if (!isatty(new_fd[0])) + set_nonblock(new_fd[0]); + if (!isatty(new_fd[1])) + set_nonblock(new_fd[1]); + + nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]); + + nc->ctl_chan = c->self; /* link session -> control channel */ + c->remote_id = nc->self; /* link control -> session channel */ + + debug2("%s: channel_new: %d linked to control channel %d", + __func__, nc->self, nc->ctl_chan); + + channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 0); + + /* prepare reply */ + /* XXX defer until channel confirmed */ + buffer_put_int(r, MUX_S_SESSION_OPENED); + buffer_put_int(r, rid); + buffer_put_int(r, nc->self); + + return 0; +} + +/* Channel callbacks fired on read/write from mux slave fd */ +static int +mux_master_read_cb(Channel *c) +{ + struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; + Buffer in, out; + void *ptr; + u_int type, rid, have, i; + int ret = -1; + + /* Setup ctx and */ + if (c->mux_ctx == NULL) { + state = xcalloc(1, sizeof(state)); + c->mux_ctx = state; + channel_register_cleanup(c->self, + mux_master_control_cleanup_cb, 0); + + /* Send hello */ + buffer_init(&out); + buffer_put_int(&out, MUX_MSG_HELLO); + buffer_put_int(&out, SSHMUX_VER); + /* no extensions */ + buffer_put_string(&c->output, buffer_ptr(&out), + buffer_len(&out)); + buffer_free(&out); + debug3("%s: channel %d: hello sent", __func__, c->self); + return 0; + } + + buffer_init(&in); + buffer_init(&out); + + /* Channel code ensures that we receive whole packets */ + if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) { + malf: + error("%s: malformed message", __func__); + goto out; + } + buffer_append(&in, ptr, have); + + if (buffer_get_int_ret(&type, &in) != 0) + goto malf; + debug3("%s: channel %d packet type 0x%08x len %u", + __func__, c->self, type, buffer_len(&in)); + + if (type == MUX_MSG_HELLO) + rid = 0; + else { + if (!state->hello_rcvd) { + error("%s: expected MUX_MSG_HELLO(0x%08x), " + "received 0x%08x", __func__, MUX_MSG_HELLO, type); + goto out; + } + if (buffer_get_int_ret(&rid, &in) != 0) + goto malf; + } + + for (i = 0; mux_master_handlers[i].handler != NULL; i++) { + if (type == mux_master_handlers[i].type) { + ret = mux_master_handlers[i].handler(rid, c, &in, &out); + break; + } + } + if (mux_master_handlers[i].handler == NULL) { + error("%s: unsupported mux message 0x%08x", __func__, type); + buffer_put_int(&out, MUX_S_FAILURE); + buffer_put_int(&out, rid); + buffer_put_cstring(&out, "unsupported request"); + ret = 0; + } + /* Enqueue reply packet */ + if (buffer_len(&out) != 0) { + buffer_put_string(&c->output, buffer_ptr(&out), + buffer_len(&out)); + } + out: + buffer_free(&in); + buffer_free(&out); + return ret; +} + +void +mux_exit_message(Channel *c, int exitval) +{ + Buffer m; + Channel *mux_chan; + + debug3("%s: channel %d: exit message, evitval %d", __func__, c->self, + exitval); + + if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL) + fatal("%s: channel %d missing mux channel %d", + __func__, c->self, c->ctl_chan); + + /* Append exit message packet to control socket output queue */ buffer_init(&m); + buffer_put_int(&m, MUX_S_EXIT_MESSAGE); + buffer_put_int(&m, c->self); + buffer_put_int(&m, exitval); - /* Send our command to server */ - buffer_put_int(&m, muxclient_command); - buffer_put_int(&m, flags); - if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) { - error("%s: msg_send", __func__); - muxerr: - close(sock); - buffer_free(&m); - if (muxclient_command != SSHMUX_COMMAND_OPEN) - cleanup_exit(255); - logit("Falling back to non-multiplexed connection"); - xfree(options.control_path); - options.control_path = NULL; - options.control_master = SSHCTL_MASTER_NO; + buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); + buffer_free(&m); +} + +/* Prepare a mux master to listen on a Unix domain socket. */ +void +muxserver_listen(void) +{ + struct sockaddr_un addr; + socklen_t sun_len; + mode_t old_umask; + + if (options.control_path == NULL || + options.control_master == SSHCTL_MASTER_NO) return; + + debug("setting up multiplex master socket"); + + memset(&addr, '\0', sizeof(addr)); + addr.sun_family = AF_UNIX; + sun_len = offsetof(struct sockaddr_un, sun_path) + + strlen(options.control_path) + 1; + + if (strlcpy(addr.sun_path, options.control_path, + sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) + fatal("ControlPath too long"); + + if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) + fatal("%s socket(): %s", __func__, strerror(errno)); + + old_umask = umask(0177); + if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) { + muxserver_sock = -1; + if (errno == EINVAL || errno == EADDRINUSE) { + error("ControlSocket %s already exists, " + "disabling multiplexing", options.control_path); + close(muxserver_sock); + muxserver_sock = -1; + xfree(options.control_path); + options.control_path = NULL; + options.control_master = SSHCTL_MASTER_NO; + return; + } else + fatal("%s bind(): %s", __func__, strerror(errno)); + } + umask(old_umask); + + if (listen(muxserver_sock, 64) == -1) + fatal("%s listen(): %s", __func__, strerror(errno)); + + set_nonblock(muxserver_sock); + + mux_listener_channel = channel_new("mux listener", + SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, + CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, + 0, addr.sun_path, 1); + mux_listener_channel->mux_rcb = mux_master_read_cb; + debug3("%s: mux listener channel %d fd %d", __func__, + mux_listener_channel->self, mux_listener_channel->sock); +} + +/* Callback on open confirmation in mux master for a mux client session. */ +static void +mux_session_confirm(int id, void *arg) +{ + struct mux_session_confirm_ctx *cctx = arg; + const char *display; + Channel *c; + int i; + + if (cctx == NULL) + fatal("%s: cctx == NULL", __func__); + if ((c = channel_by_id(id)) == NULL) + fatal("%s: no channel for id %d", __func__, id); + + display = getenv("DISPLAY"); + if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { + char *proto, *data; + /* Get reasonable local authentication information. */ + client_x11_get_proto(display, options.xauth_location, + options.forward_x11_trusted, &proto, &data); + /* Request forwarding with authentication spoofing. */ + debug("Requesting X11 forwarding with authentication spoofing."); + x11_request_forwarding_with_spoofing(id, display, proto, data); + /* XXX wait for reply */ + } + + if (cctx->want_agent_fwd && options.forward_agent) { + debug("Requesting authentication agent forwarding."); + channel_request_start(id, "auth-agent-req@openssh.com", 0); + packet_send(); + } + + client_session2_setup(id, cctx->want_tty, cctx->want_subsys, + cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); + + c->open_confirm_ctx = NULL; + buffer_free(&cctx->cmd); + xfree(cctx->term); + if (cctx->env != NULL) { + for (i = 0; cctx->env[i] != NULL; i++) + xfree(cctx->env[i]); + xfree(cctx->env); + } + xfree(cctx); +} + +/* ** Multiplexing client support */ + +/* Exit signal handler */ +static void +control_client_sighandler(int signo) +{ + muxclient_terminate = signo; +} + +/* + * Relay signal handler - used to pass some signals from mux client to + * mux master. + */ +static void +control_client_sigrelay(int signo) +{ + int save_errno = errno; + + if (muxserver_pid > 1) + kill(muxserver_pid, signo); + + errno = save_errno; +} + +static int +mux_client_read(int fd, Buffer *b, u_int need) +{ + u_int have; + ssize_t len; + u_char *p; + struct pollfd pfd; + + pfd.fd = fd; + pfd.events = POLLIN; + p = buffer_append_space(b, need); + for (have = 0; have < need; ) { + if (muxclient_terminate) { + errno = EINTR; + return -1; + } + len = read(fd, p + have, need - have); + if (len < 0) { + switch (errno) { +#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) + case EWOULDBLOCK: +#endif + case EAGAIN: + (void)poll(&pfd, 1, -1); + /* FALLTHROUGH */ + case EINTR: + continue; + default: + return -1; + } + } + if (len == 0) { + errno = EPIPE; + return -1; + } + have += (u_int)len; + } + return 0; +} + +static int +mux_client_write_packet(int fd, Buffer *m) +{ + Buffer queue; + u_int have, need; + int oerrno, len; + u_char *ptr; + struct pollfd pfd; + + pfd.fd = fd; + pfd.events = POLLOUT; + buffer_init(&queue); + buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); + + need = buffer_len(&queue); + ptr = buffer_ptr(&queue); + + for (have = 0; have < need; ) { + if (muxclient_terminate) { + buffer_free(&queue); + errno = EINTR; + return -1; + } + len = write(fd, ptr + have, need - have); + if (len < 0) { + switch (errno) { +#if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) + case EWOULDBLOCK: +#endif + case EAGAIN: + (void)poll(&pfd, 1, -1); + /* FALLTHROUGH */ + case EINTR: + continue; + default: + oerrno = errno; + buffer_free(&queue); + errno = oerrno; + return -1; + } + } + if (len == 0) { + buffer_free(&queue); + errno = EPIPE; + return -1; + } + have += (u_int)len; + } + buffer_free(&queue); + return 0; +} + +static int +mux_client_read_packet(int fd, Buffer *m) +{ + Buffer queue; + u_int need, have; + void *ptr; + int oerrno; + + buffer_init(&queue); + if (mux_client_read(fd, &queue, 4) != 0) { + if ((oerrno = errno) == EPIPE) + debug3("%s: read header failed: %s", __func__, strerror(errno)); + errno = oerrno; + return -1; } + need = get_u32(buffer_ptr(&queue)); + if (mux_client_read(fd, &queue, need) != 0) { + oerrno = errno; + debug3("%s: read body failed: %s", __func__, strerror(errno)); + errno = oerrno; + return -1; + } + ptr = buffer_get_string_ptr(&queue, &have); + buffer_append(m, ptr, have); + buffer_free(&queue); + return 0; +} + +static int +mux_client_hello_exchange(int fd) +{ + Buffer m; + u_int type, ver; + + buffer_init(&m); + buffer_put_int(&m, MUX_MSG_HELLO); + buffer_put_int(&m, SSHMUX_VER); + /* no extensions */ + + if (mux_client_write_packet(fd, &m) != 0) + fatal("%s: write packet: %s", __func__, strerror(errno)); + buffer_clear(&m); - /* Get authorisation status and PID of controlee */ - if (ssh_msg_recv(sock, &m) == -1) { - error("%s: Did not receive reply from master", __func__); - goto muxerr; + /* Read their HELLO */ + if (mux_client_read_packet(fd, &m) != 0) { + buffer_free(&m); + return -1; } - if (buffer_get_char(&m) != SSHMUX_VER) { - error("%s: Master replied with wrong version", __func__); - goto muxerr; + + type = buffer_get_int(&m); + if (type != MUX_MSG_HELLO) + fatal("%s: expected HELLO (%u) received %u", + __func__, MUX_MSG_HELLO, type); + ver = buffer_get_int(&m); + if (ver != SSHMUX_VER) + fatal("Unsupported multiplexing protocol version %d " + "(expected %d)", ver, SSHMUX_VER); + debug2("%s: master version %u", __func__, ver); + /* No extensions are presently defined */ + while (buffer_len(&m) > 0) { + char *name = buffer_get_string(&m, NULL); + char *value = buffer_get_string(&m, NULL); + + debug2("Unrecognised master extension \"%s\"", name); + xfree(name); + xfree(value); } - if (buffer_get_int_ret(&allowed, &m) != 0) { - error("%s: bad server reply", __func__); - goto muxerr; + buffer_free(&m); + return 0; +} + +static u_int +mux_client_request_alive(int fd) +{ + Buffer m; + char *e; + u_int pid, type, rid; + + debug3("%s: entering", __func__); + + buffer_init(&m); + buffer_put_int(&m, MUX_C_ALIVE_CHECK); + buffer_put_int(&m, muxclient_request_id); + + if (mux_client_write_packet(fd, &m) != 0) + fatal("%s: write packet: %s", __func__, strerror(errno)); + + buffer_clear(&m); + + /* Read their reply */ + if (mux_client_read_packet(fd, &m) != 0) { + buffer_free(&m); + return 0; } - if (allowed != 1) { - error("Connection to master denied"); - goto muxerr; + + type = buffer_get_int(&m); + if (type != MUX_S_ALIVE) { + e = buffer_get_string(&m, NULL); + fatal("%s: master returned error: %s", __func__, e); } - muxserver_pid = buffer_get_int(&m); + + if ((rid = buffer_get_int(&m)) != muxclient_request_id) + fatal("%s: out of sequence reply: my id %u theirs %u", + __func__, muxclient_request_id, rid); + pid = buffer_get_int(&m); + buffer_free(&m); + + debug3("%s: done pid = %u", __func__, pid); + + muxclient_request_id++; + + return pid; +} + +static void +mux_client_request_terminate(int fd) +{ + Buffer m; + char *e; + u_int type, rid; + + debug3("%s: entering", __func__); + + buffer_init(&m); + buffer_put_int(&m, MUX_C_TERMINATE); + buffer_put_int(&m, muxclient_request_id); + + if (mux_client_write_packet(fd, &m) != 0) + fatal("%s: write packet: %s", __func__, strerror(errno)); buffer_clear(&m); - switch (muxclient_command) { - case SSHMUX_COMMAND_ALIVE_CHECK: - fprintf(stderr, "Master running (pid=%d)\r\n", - muxserver_pid); - exit(0); - case SSHMUX_COMMAND_TERMINATE: - fprintf(stderr, "Exit request sent.\r\n"); - exit(0); - case SSHMUX_COMMAND_OPEN: - buffer_put_cstring(&m, term ? term : ""); - if (options.escape_char == SSH_ESCAPECHAR_NONE) - buffer_put_int(&m, 0xffffffff); - else - buffer_put_int(&m, options.escape_char); - buffer_append(&command, "\0", 1); - buffer_put_cstring(&m, buffer_ptr(&command)); - - if (options.num_send_env == 0 || environ == NULL) { - buffer_put_int(&m, 0); - } else { - /* Pass environment */ - num_env = 0; - for (i = 0; environ[i] != NULL; i++) { - if (env_permitted(environ[i])) - num_env++; /* Count */ - } - buffer_put_int(&m, num_env); - for (i = 0; environ[i] != NULL && num_env >= 0; i++) { - if (env_permitted(environ[i])) { - num_env--; - buffer_put_cstring(&m, environ[i]); - } - } + /* Read their reply */ + if (mux_client_read_packet(fd, &m) != 0) { + /* Remote end exited already */ + if (errno == EPIPE) { + buffer_free(&m); + return; } + fatal("%s: read from master failed: %s", + __func__, strerror(errno)); + } + + type = buffer_get_int(&m); + if ((rid = buffer_get_int(&m)) != muxclient_request_id) + fatal("%s: out of sequence reply: my id %u theirs %u", + __func__, muxclient_request_id, rid); + switch (type) { + case MUX_S_OK: break; + case MUX_S_PERMISSION_DENIED: + e = buffer_get_string(&m, NULL); + fatal("Master refused termination request: %s", e); + case MUX_S_FAILURE: + e = buffer_get_string(&m, NULL); + fatal("%s: termination request failed: %s", __func__, e); default: - fatal("unrecognised muxclient_command %d", muxclient_command); + fatal("%s: unexpected response from master 0x%08x", + __func__, type); } + buffer_free(&m); + muxclient_request_id++; +} + +static int +mux_client_request_forward(int fd, u_int ftype, Forward *fwd) +{ + Buffer m; + char *e, *fwd_desc; + u_int type, rid; + + fwd_desc = format_forward(ftype, fwd); + debug("Requesting %s", fwd_desc); + xfree(fwd_desc); + + buffer_init(&m); + buffer_put_int(&m, MUX_C_OPEN_FWD); + buffer_put_int(&m, muxclient_request_id); + buffer_put_int(&m, ftype); + buffer_put_cstring(&m, + fwd->listen_host == NULL ? "" : fwd->listen_host); + buffer_put_int(&m, fwd->listen_port); + buffer_put_cstring(&m, + fwd->connect_host == NULL ? "" : fwd->connect_host); + buffer_put_int(&m, fwd->connect_port); + + if (mux_client_write_packet(fd, &m) != 0) + fatal("%s: write packet: %s", __func__, strerror(errno)); + + buffer_clear(&m); - if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) { - error("%s: msg_send", __func__); - goto muxerr; + /* Read their reply */ + if (mux_client_read_packet(fd, &m) != 0) { + buffer_free(&m); + return -1; } - if (mm_send_fd(sock, STDIN_FILENO) == -1 || - mm_send_fd(sock, STDOUT_FILENO) == -1 || - mm_send_fd(sock, STDERR_FILENO) == -1) { - error("%s: send fds failed", __func__); - goto muxerr; + type = buffer_get_int(&m); + if ((rid = buffer_get_int(&m)) != muxclient_request_id) + fatal("%s: out of sequence reply: my id %u theirs %u", + __func__, muxclient_request_id, rid); + switch (type) { + case MUX_S_OK: + break; + case MUX_S_PERMISSION_DENIED: + e = buffer_get_string(&m, NULL); + buffer_free(&m); + error("Master refused forwarding request: %s", e); + return -1; + case MUX_S_FAILURE: + e = buffer_get_string(&m, NULL); + buffer_free(&m); + error("%s: session request failed: %s", __func__, e); + return -1; + default: + fatal("%s: unexpected response from master 0x%08x", + __func__, type); } + buffer_free(&m); - /* - * Mux errors are non-recoverable from this point as the master - * has ownership of the session now. - */ + muxclient_request_id++; + return 0; +} - /* Wait for reply, so master has a chance to gather ttymodes */ +static int +mux_client_request_forwards(int fd) +{ + int i; + + debug3("%s: requesting forwardings: %d local, %d remote", __func__, + options.num_local_forwards, options.num_remote_forwards); + + /* XXX ExitOnForwardingFailure */ + for (i = 0; i < options.num_local_forwards; i++) { + if (mux_client_request_forward(fd, + options.local_forwards[i].connect_port == 0 ? + MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, + options.local_forwards + i) != 0) + return -1; + } + for (i = 0; i < options.num_remote_forwards; i++) { + if (mux_client_request_forward(fd, MUX_FWD_REMOTE, + options.remote_forwards + i) != 0) + return -1; + } + return 0; +} + +static int +mux_client_request_session(int fd) +{ + Buffer m; + char *e, *term; + u_int i, rid, sid, esid, exitval, type, exitval_seen; + extern char **environ; + int devnull; + + debug3("%s: entering", __func__); + + if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { + error("%s: master alive request failed", __func__); + return -1; + } + + signal(SIGPIPE, SIG_IGN); + + if (stdin_null_flag) { + if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) + fatal("open(/dev/null): %s", strerror(errno)); + if (dup2(devnull, STDIN_FILENO) == -1) + fatal("dup2: %s", strerror(errno)); + if (devnull > STDERR_FILENO) + close(devnull); + } + + term = getenv("TERM"); + + buffer_init(&m); + buffer_put_int(&m, MUX_C_NEW_SESSION); + buffer_put_int(&m, muxclient_request_id); + buffer_put_cstring(&m, ""); /* reserved */ + buffer_put_int(&m, tty_flag); + buffer_put_int(&m, options.forward_x11); + buffer_put_int(&m, options.forward_agent); + buffer_put_int(&m, subsystem_flag); + buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? + 0xffffffff : (u_int)options.escape_char); + buffer_put_cstring(&m, term == NULL ? "" : term); + buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); + + if (options.num_send_env > 0 && environ != NULL) { + /* Pass environment */ + for (i = 0; environ[i] != NULL; i++) { + if (env_permitted(environ[i])) { + buffer_put_cstring(&m, environ[i]); + } + } + } + + if (mux_client_write_packet(fd, &m) != 0) + fatal("%s: write packet: %s", __func__, strerror(errno)); + + /* Send the stdio file descriptors */ + if (mm_send_fd(fd, STDIN_FILENO) == -1 || + mm_send_fd(fd, STDOUT_FILENO) == -1 || + mm_send_fd(fd, STDERR_FILENO) == -1) + fatal("%s: send fds failed", __func__); + + debug3("%s: session request sent", __func__); + + /* Read their reply */ buffer_clear(&m); - if (ssh_msg_recv(sock, &m) == -1) - fatal("%s: msg_recv", __func__); - if (buffer_get_char(&m) != SSHMUX_VER) - fatal("%s: wrong version", __func__); - buffer_free(&m); + if (mux_client_read_packet(fd, &m) != 0) { + error("%s: read from master failed: %s", + __func__, strerror(errno)); + buffer_free(&m); + return -1; + } + + type = buffer_get_int(&m); + if ((rid = buffer_get_int(&m)) != muxclient_request_id) + fatal("%s: out of sequence reply: my id %u theirs %u", + __func__, muxclient_request_id, rid); + switch (type) { + case MUX_S_SESSION_OPENED: + sid = buffer_get_int(&m); + debug("%s: master session id: %u", __func__, sid); + break; + case MUX_S_PERMISSION_DENIED: + e = buffer_get_string(&m, NULL); + buffer_free(&m); + error("Master refused forwarding request: %s", e); + return -1; + case MUX_S_FAILURE: + e = buffer_get_string(&m, NULL); + buffer_free(&m); + error("%s: forwarding request failed: %s", __func__, e); + return -1; + default: + buffer_free(&m); + error("%s: unexpected response from master 0x%08x", + __func__, type); + return -1; + } + muxclient_request_id++; signal(SIGHUP, control_client_sighandler); signal(SIGINT, control_client_sighandler); @@ -688,42 +1509,231 @@ muxclient(const char *path) /* * Stick around until the controlee closes the client_fd. - * Before it does, it is expected to write this process' exit - * value (one int). This process must read the value and wait for - * the closure of the client_fd; if this one closes early, the - * multiplex master will terminate early too (possibly losing data). + * Before it does, it is expected to write an exit message. + * This process must read the value and wait for the closure of + * the client_fd; if this one closes early, the multiplex master will + * terminate early too (possibly losing data). */ - exitval[0] = 0; - for (i = 0; !muxclient_terminate && i < (int)sizeof(exitval);) { - r = read(sock, (char *)exitval + i, sizeof(exitval) - i); - if (r == 0) { - debug2("Received EOF from master"); + for (exitval = 255, exitval_seen = 0;;) { + buffer_clear(&m); + if (mux_client_read_packet(fd, &m) != 0) break; + type = buffer_get_int(&m); + if (type != MUX_S_EXIT_MESSAGE) { + e = buffer_get_string(&m, NULL); + fatal("%s: master returned error: %s", __func__, e); } - if (r == -1) { - if (errno == EINTR) - continue; - fatal("%s: read %s", __func__, strerror(errno)); - } - i += r; + if ((esid = buffer_get_int(&m)) != sid) + fatal("%s: exit on unknown session: my id %u theirs %u", + __func__, sid, esid); + debug("%s: master session id: %u", __func__, sid); + if (exitval_seen) + fatal("%s: exitval sent twice", __func__); + exitval = buffer_get_int(&m); + exitval_seen = 1; } - close(sock); + close(fd); leave_raw_mode(force_tty_flag); - if (i > (int)sizeof(int)) - fatal("%s: master returned too much data (%d > %lu)", - __func__, i, (u_long)sizeof(int)); + if (muxclient_terminate) { debug2("Exiting on signal %d", muxclient_terminate); - exitval[0] = 255; - } else if (i < (int)sizeof(int)) { + exitval = 255; + } else if (!exitval_seen) { debug2("Control master terminated unexpectedly"); - exitval[0] = 255; + exitval = 255; } else - debug2("Received exit status from master %d", exitval[0]); + debug2("Received exit status from master %d", exitval); if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) fprintf(stderr, "Shared connection to %s closed.\r\n", host); - exit(exitval[0]); + exit(exitval); +} + +static int +mux_client_request_stdio_fwd(int fd) +{ + Buffer m; + char *e; + u_int type, rid, sid; + int devnull; + + debug3("%s: entering", __func__); + + if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { + error("%s: master alive request failed", __func__); + return -1; + } + + signal(SIGPIPE, SIG_IGN); + + if (stdin_null_flag) { + if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) + fatal("open(/dev/null): %s", strerror(errno)); + if (dup2(devnull, STDIN_FILENO) == -1) + fatal("dup2: %s", strerror(errno)); + if (devnull > STDERR_FILENO) + close(devnull); + } + + buffer_init(&m); + buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); + buffer_put_int(&m, muxclient_request_id); + buffer_put_cstring(&m, ""); /* reserved */ + buffer_put_cstring(&m, stdio_forward_host); + buffer_put_int(&m, stdio_forward_port); + + if (mux_client_write_packet(fd, &m) != 0) + fatal("%s: write packet: %s", __func__, strerror(errno)); + + /* Send the stdio file descriptors */ + if (mm_send_fd(fd, STDIN_FILENO) == -1 || + mm_send_fd(fd, STDOUT_FILENO) == -1) + fatal("%s: send fds failed", __func__); + + debug3("%s: stdio forward request sent", __func__); + + /* Read their reply */ + buffer_clear(&m); + + if (mux_client_read_packet(fd, &m) != 0) { + error("%s: read from master failed: %s", + __func__, strerror(errno)); + buffer_free(&m); + return -1; + } + + type = buffer_get_int(&m); + if ((rid = buffer_get_int(&m)) != muxclient_request_id) + fatal("%s: out of sequence reply: my id %u theirs %u", + __func__, muxclient_request_id, rid); + switch (type) { + case MUX_S_SESSION_OPENED: + sid = buffer_get_int(&m); + debug("%s: master session id: %u", __func__, sid); + break; + case MUX_S_PERMISSION_DENIED: + e = buffer_get_string(&m, NULL); + buffer_free(&m); + fatal("Master refused forwarding request: %s", e); + case MUX_S_FAILURE: + e = buffer_get_string(&m, NULL); + buffer_free(&m); + fatal("%s: stdio forwarding request failed: %s", __func__, e); + default: + buffer_free(&m); + error("%s: unexpected response from master 0x%08x", + __func__, type); + return -1; + } + muxclient_request_id++; + + signal(SIGHUP, control_client_sighandler); + signal(SIGINT, control_client_sighandler); + signal(SIGTERM, control_client_sighandler); + signal(SIGWINCH, control_client_sigrelay); + + /* + * Stick around until the controlee closes the client_fd. + */ + buffer_clear(&m); + if (mux_client_read_packet(fd, &m) != 0) { + if (errno == EPIPE || + (errno == EINTR && muxclient_terminate != 0)) + return 0; + fatal("%s: mux_client_read_packet: %s", + __func__, strerror(errno)); + } + fatal("%s: master returned unexpected message %u", __func__, type); +} + +/* Multiplex client main loop. */ +void +muxclient(const char *path) +{ + struct sockaddr_un addr; + socklen_t sun_len; + int sock; + u_int pid; + + if (muxclient_command == 0) { + if (stdio_forward_host != NULL) + muxclient_command = SSHMUX_COMMAND_STDIO_FWD; + else + muxclient_command = SSHMUX_COMMAND_OPEN; + } + + switch (options.control_master) { + case SSHCTL_MASTER_AUTO: + case SSHCTL_MASTER_AUTO_ASK: + debug("auto-mux: Trying existing master"); + /* FALLTHROUGH */ + case SSHCTL_MASTER_NO: + break; + default: + return; + } + + memset(&addr, '\0', sizeof(addr)); + addr.sun_family = AF_UNIX; + sun_len = offsetof(struct sockaddr_un, sun_path) + + strlen(path) + 1; + + if (strlcpy(addr.sun_path, path, + sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) + fatal("ControlPath too long"); + + if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) + fatal("%s socket(): %s", __func__, strerror(errno)); + + if (connect(sock, (struct sockaddr *)&addr, sun_len) == -1) { + switch (muxclient_command) { + case SSHMUX_COMMAND_OPEN: + case SSHMUX_COMMAND_STDIO_FWD: + break; + default: + fatal("Control socket connect(%.100s): %s", path, + strerror(errno)); + } + if (errno == ENOENT) + debug("Control socket \"%.100s\" does not exist", path); + else { + error("Control socket connect(%.100s): %s", path, + strerror(errno)); + } + close(sock); + return; + } + set_nonblock(sock); + + if (mux_client_hello_exchange(sock) != 0) { + error("%s: master hello exchange failed", __func__); + close(sock); + return; + } + + switch (muxclient_command) { + case SSHMUX_COMMAND_ALIVE_CHECK: + if ((pid = mux_client_request_alive(sock)) == 0) + fatal("%s: master alive check failed", __func__); + fprintf(stderr, "Master running (pid=%d)\r\n", pid); + exit(0); + case SSHMUX_COMMAND_TERMINATE: + mux_client_request_terminate(sock); + fprintf(stderr, "Exit request sent.\r\n"); + exit(0); + case SSHMUX_COMMAND_OPEN: + if (mux_client_request_forwards(sock) != 0) { + error("%s: master forward request failed", __func__); + return; + } + mux_client_request_session(sock); + return; + case SSHMUX_COMMAND_STDIO_FWD: + mux_client_request_stdio_fwd(sock); + exit(0); + default: + fatal("unrecognised muxclient_command %d", muxclient_command); + } } diff --git a/nchan.c b/nchan.c index 160445e5..20f6a2f4 100644 --- a/nchan.c +++ b/nchan.c @@ -1,4 +1,4 @@ -/* $OpenBSD: nchan.c,v 1.62 2008/11/07 18:50:18 stevesk Exp $ */ +/* $OpenBSD: nchan.c,v 1.63 2010/01/26 01:28:35 djm Exp $ */ /* * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. * @@ -161,7 +161,7 @@ chan_ibuf_empty(Channel *c) switch (c->istate) { case CHAN_INPUT_WAIT_DRAIN: if (compat20) { - if (!(c->flags & CHAN_CLOSE_SENT)) + if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_LOCAL))) chan_send_eof2(c); chan_set_istate(c, CHAN_INPUT_CLOSED); } else { @@ -278,9 +278,12 @@ static void chan_rcvd_close2(Channel *c) { debug2("channel %d: rcvd close", c->self); - if (c->flags & CHAN_CLOSE_RCVD) - error("channel %d: protocol error: close rcvd twice", c->self); - c->flags |= CHAN_CLOSE_RCVD; + if (!(c->flags & CHAN_LOCAL)) { + if (c->flags & CHAN_CLOSE_RCVD) + error("channel %d: protocol error: close rcvd twice", + c->self); + c->flags |= CHAN_CLOSE_RCVD; + } if (c->type == SSH_CHANNEL_LARVAL) { /* tear down larval channels immediately */ chan_set_ostate(c, CHAN_OUTPUT_CLOSED); @@ -302,11 +305,13 @@ chan_rcvd_close2(Channel *c) chan_set_istate(c, CHAN_INPUT_CLOSED); break; case CHAN_INPUT_WAIT_DRAIN: - chan_send_eof2(c); + if (!(c->flags & CHAN_LOCAL)) + chan_send_eof2(c); chan_set_istate(c, CHAN_INPUT_CLOSED); break; } } + void chan_rcvd_eow(Channel *c) { @@ -454,6 +459,10 @@ chan_is_dead(Channel *c, int do_send) c->self, c->efd, buffer_len(&c->extended)); return 0; } + if (c->flags & CHAN_LOCAL) { + debug2("channel %d: is dead (local)", c->self); + return 1; + } if (!(c->flags & CHAN_CLOSE_SENT)) { if (do_send) { chan_send_close2(c); diff --git a/ssh.c b/ssh.c index b86a764f..97afdcfe 100644 --- a/ssh.c +++ b/ssh.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ssh.c,v 1.331 2010/01/11 01:39:46 dtucker Exp $ */ +/* $OpenBSD: ssh.c,v 1.332 2010/01/26 01:28:35 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -319,6 +319,11 @@ main(int ac, char **av) options.gateway_ports = 1; break; case 'O': + if (stdio_forward_host != NULL) + fatal("Cannot specify multiplexing " + "command with -W"); + else if (muxclient_command != 0) + fatal("Multiplexing command already specified"); if (strcmp(optarg, "check") == 0) muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK; else if (strcmp(optarg, "exit") == 0) @@ -395,6 +400,10 @@ main(int ac, char **av) } break; case 'W': + if (stdio_forward_host != NULL) + fatal("stdio forward already specified"); + if (muxclient_command != 0) + fatal("Cannot specify stdio forward with -O"); if (parse_forward(&fwd, optarg, 1, 0)) { stdio_forward_host = fwd.listen_host; stdio_forward_port = fwd.listen_port; @@ -902,11 +911,18 @@ static int client_setup_stdio_fwd(const char *host_to_connect, u_short port_to_connect) { Channel *c; + int in, out; debug3("client_setup_stdio_fwd %s:%d", host_to_connect, port_to_connect); - if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect)) - == NULL) + + in = dup(STDIN_FILENO); + out = dup(STDOUT_FILENO); + if (in < 0 || out < 0) + fatal("channel_connect_stdio_fwd: dup() in/out failed"); + + if ((c = channel_connect_stdio_fwd(host_to_connect, port_to_connect, + in, out)) == NULL) return 0; channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0); return 1; -- 2.45.2