diff options
Diffstat (limited to 'crypto/openssh/mux.c')
| -rw-r--r-- | crypto/openssh/mux.c | 2102 |
1 files changed, 2102 insertions, 0 deletions
diff --git a/crypto/openssh/mux.c b/crypto/openssh/mux.c new file mode 100644 index 0000000..f4edf55 --- /dev/null +++ b/crypto/openssh/mux.c @@ -0,0 +1,2102 @@ +/* $OpenBSD: mux.c,v 1.44 2013/07/12 00:19:58 djm Exp $ */ +/* + * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* ssh session multiplexing support */ + +/* + * TODO: + * - Better signalling from master to slave, especially passing of + * error messages + * - 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 <sys/types.h> +#include <sys/param.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <sys/un.h> + +#include <errno.h> +#include <fcntl.h> +#include <signal.h> +#include <stdarg.h> +#include <stddef.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#ifdef HAVE_PATHS_H +#include <paths.h> +#endif + +#ifdef HAVE_POLL_H +#include <poll.h> +#else +# ifdef HAVE_SYS_POLL_H +# include <sys/poll.h> +# endif +#endif + +#ifdef HAVE_UTIL_H +# include <util.h> +#endif + +#include "openbsd-compat/sys-queue.h" +#include "xmalloc.h" +#include "log.h" +#include "ssh.h" +#include "ssh2.h" +#include "pathnames.h" +#include "misc.h" +#include "match.h" +#include "buffer.h" +#include "channels.h" +#include "msg.h" +#include "packet.h" +#include "monitor_fdpass.h" +#include "sshpty.h" +#include "key.h" +#include "readconf.h" +#include "clientloop.h" + +/* from ssh.c */ +extern int tty_flag; +extern Options options; +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 { + 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; + char **env; + u_int rid; +}; + +/* Context for global channel callback */ +struct mux_channel_confirm_ctx { + u_int cid; /* channel id */ + u_int rid; /* request id */ + int fid; /* forward id */ +}; + +/* 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; + +/* Set when signalled. */ +static volatile sig_atomic_t muxclient_terminate = 0; + +/* PID of multiplex server */ +static u_int muxserver_pid = 0; + +static Channel *mux_listener_channel = NULL; + +struct mux_master_state { + int hello_rcvd; +}; + +/* 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_C_STOP_LISTENING 0x10000009 +#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 +#define MUX_S_REMOTE_PORT 0x80000007 +#define MUX_S_TTY_ALLOC_FAIL 0x80000008 + +/* 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, 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 int process_mux_stop_listening(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 }, + { MUX_C_STOP_LISTENING, process_mux_stop_listening }, + { 0, NULL } +}; + +/* 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); + } + channel_cancel_cleanup(c->self); +} + +/* Cleanup callback fired on closure of mux slave _control_ channel */ +/* ARGSUSED */ +static void +mux_master_control_cleanup_cb(int cid, void *unused) +{ + 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) + fatal("%s: channel %d missing session channel %d", + __func__, c->self, c->remote_id); + c->remote_id = -1; + sc->ctl_chan = -1; + if (sc->type != SSH_CHANNEL_OPEN && + sc->type != SSH_CHANNEL_OPENING) { + debug2("%s: channel %d: not open", __func__, sc->self); + chan_mark_dead(sc); + } else { + if (sc->istate == CHAN_INPUT_OPEN) + chan_read_failed(sc); + if (sc->ostate == CHAN_OUTPUT_OPEN) + chan_write_failed(sc); + } + } + channel_cancel_cleanup(c->self); +} + +/* Check mux client environment variables before passing them to mux master. */ +static int +env_permitted(char *env) +{ + 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)) { + error("env_permitted: name '%.100s...' too long", env); + return 0; + } + + 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 */ + +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 (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); + + /* 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); + + if (name == NULL || value == NULL) { + free(name); + free(value); + goto malf; + } + debug2("Unrecognised slave extension \"%s\"", name); + free(name); + free(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 */ + cctx = xcalloc(1, sizeof(*cctx)); + cctx->term = NULL; + cctx->rid = rid; + cmd = reserved = NULL; + cctx->env = NULL; + env_len = 0; + 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: + free(cmd); + free(reserved); + for (j = 0; j < env_len; j++) + free(cctx->env[j]); + free(cctx->env); + free(cctx->term); + free(cctx); + error("%s: malformed message", __func__); + return -1; + } + free(reserved); + reserved = NULL; + + while (buffer_len(m) > 0) { +#define MUX_MAX_ENV_VARS 4096 + if ((cp = buffer_get_string_ret(m, &len)) == NULL) + goto malf; + if (!env_permitted(cp)) { + free(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; + } + } + + 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); + + buffer_init(&cctx->cmd); + buffer_append(&cctx->cmd, cmd, strlen(cmd)); + free(cmd); + cmd = NULL; + + /* Gather fds from client */ + for(i = 0; i < 3; 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]); + for (j = 0; j < env_len; j++) + free(cctx->env[j]); + free(cctx->env); + free(cctx->term); + buffer_free(&cctx->cmd); + free(cctx); + + /* 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, stderr %d", __func__, + new_fd[0], new_fd[1], new_fd[2]); + + /* 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]); + free(cctx->term); + if (env_len != 0) { + for (i = 0; i < env_len; i++) + free(cctx->env[i]); + free(cctx->env); + } + buffer_free(&cctx->cmd); + free(cctx); + return 0; + } + + 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])) + set_nonblock(new_fd[0]); + if (!isatty(new_fd[1])) + set_nonblock(new_fd[1]); + if (!isatty(new_fd[2])) + set_nonblock(new_fd[2]); + + window = CHAN_SES_WINDOW_DEFAULT; + packetmax = CHAN_SES_PACKET_DEFAULT; + if (cctx->want_tty) { + window >>= 1; + packetmax >>= 1; + } + + 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); + + 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(nc->self, + client_simple_escape_filter, NULL, + client_filter_cleanup, + client_new_escape_filter_ctx((int)escape_char)); + } + + debug2("%s: channel_new: %d linked to control channel %d", + __func__, nc->self, nc->ctl_chan); + + channel_send_open(nc->self); + channel_register_open_confirm(nc->self, mux_session_confirm, cctx); + c->mux_pause = 1; /* stop handling messages until open_confirm done */ + channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1); + + /* reply is deferred, sent by mux_session_confirm */ + return 0; +} + +static int +process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + debug2("%s: channel %d: alive check", __func__, c->self); + + /* prepare reply */ + buffer_put_int(r, MUX_S_ALIVE); + buffer_put_int(r, rid); + buffer_put_int(r, (u_int)getpid()); + + return 0; +} + +static int +process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + 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; + } + } + + 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; +} + +static char * +format_forward(u_int ftype, Forward *fwd) +{ + 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: + fatal("%s: unknown forward type %u", __func__, ftype); + } + return ret; +} + +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; +} + +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; + + return 1; +} + +static void +mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) +{ + struct mux_channel_confirm_ctx *fctx = ctxt; + char *failmsg = NULL; + Forward *rfwd; + Channel *c; + Buffer out; + + if ((c = channel_by_id(fctx->cid)) == NULL) { + /* no channel for reply */ + error("%s: unknown channel", __func__); + return; + } + buffer_init(&out); + if (fctx->fid >= options.num_remote_forwards) { + xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); + goto fail; + } + rfwd = &options.remote_forwards[fctx->fid]; + debug("%s: %s for: listen %d, connect %s:%d", __func__, + type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", + rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); + if (type == SSH2_MSG_REQUEST_SUCCESS) { + if (rfwd->listen_port == 0) { + rfwd->allocated_port = packet_get_int(); + logit("Allocated port %u for mux remote forward" + " to %s:%d", rfwd->allocated_port, + rfwd->connect_host, rfwd->connect_port); + buffer_put_int(&out, MUX_S_REMOTE_PORT); + buffer_put_int(&out, fctx->rid); + buffer_put_int(&out, rfwd->allocated_port); + channel_update_permitted_opens(rfwd->handle, + rfwd->allocated_port); + } else { + buffer_put_int(&out, MUX_S_OK); + buffer_put_int(&out, fctx->rid); + } + goto out; + } else { + if (rfwd->listen_port == 0) + channel_update_permitted_opens(rfwd->handle, -1); + xasprintf(&failmsg, "remote port forwarding failed for " + "listen port %d", rfwd->listen_port); + } + fail: + error("%s: %s", __func__, failmsg); + buffer_put_int(&out, MUX_S_FAILURE); + buffer_put_int(&out, fctx->rid); + buffer_put_cstring(&out, failmsg); + free(failmsg); + out: + buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out)); + buffer_free(&out); + if (c->mux_pause <= 0) + fatal("%s: mux_pause %d", __func__, c->mux_pause); + c->mux_pause = 0; /* start processing messages again */ +} + +static int +process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + Forward fwd; + char *fwd_desc = NULL; + u_int ftype; + u_int lport, cport; + 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(&lport, m) != 0 || + (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&cport, m) != 0 || + lport > 65535 || cport > 65535) { + error("%s: malformed message", __func__); + ret = -1; + goto out; + } + fwd.listen_port = lport; + fwd.connect_port = cport; + if (*fwd.listen_host == '\0') { + free(fwd.listen_host); + fwd.listen_host = NULL; + } + if (*fwd.connect_host == '\0') { + free(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: + free(fwd.listen_host); + free(fwd.connect_host); + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, "Invalid forwarding request"); + return 0; + } + if (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; + } + } + break; + case MUX_FWD_REMOTE: + for (i = 0; i < options.num_remote_forwards; i++) { + if (compare_forward(&fwd, + options.remote_forwards + i)) { + if (fwd.listen_port != 0) + goto exists; + debug2("%s: found allocated port", + __func__); + buffer_put_int(r, MUX_S_REMOTE_PORT); + buffer_put_int(r, rid); + buffer_put_int(r, + options.remote_forwards[i].allocated_port); + goto out; + } + } + break; + } + + 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; + } + } + + if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { + if (!channel_setup_local_fwd_listener(fwd.listen_host, + fwd.listen_port, fwd.connect_host, fwd.connect_port, + options.gateway_ports)) { + 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 { + struct mux_channel_confirm_ctx *fctx; + + fwd.handle = channel_request_remote_forwarding(fwd.listen_host, + fwd.listen_port, fwd.connect_host, fwd.connect_port); + if (fwd.handle < 0) + goto fail; + add_remote_forward(&options, &fwd); + fctx = xcalloc(1, sizeof(*fctx)); + fctx->cid = c->self; + fctx->rid = rid; + fctx->fid = options.num_remote_forwards - 1; + client_register_global_confirm(mux_confirm_remote_forward, + fctx); + freefwd = 0; + c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ + /* delayed reply in mux_confirm_remote_forward */ + goto out; + } + buffer_put_int(r, MUX_S_OK); + buffer_put_int(r, rid); + out: + free(fwd_desc); + if (freefwd) { + free(fwd.listen_host); + free(fwd.connect_host); + } + return ret; +} + +static int +process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + Forward fwd, *found_fwd; + char *fwd_desc = NULL; + const char *error_reason = NULL; + u_int ftype; + int i, listen_port, ret = 0; + u_int lport, cport; + + 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(&lport, m) != 0 || + (fwd.connect_host = buffer_get_string_ret(m, NULL)) == NULL || + buffer_get_int_ret(&cport, m) != 0 || + lport > 65535 || cport > 65535) { + error("%s: malformed message", __func__); + ret = -1; + goto out; + } + fwd.listen_port = lport; + fwd.connect_port = cport; + + if (*fwd.listen_host == '\0') { + free(fwd.listen_host); + fwd.listen_host = NULL; + } + if (*fwd.connect_host == '\0') { + free(fwd.connect_host); + fwd.connect_host = NULL; + } + + debug2("%s: channel %d: request cancel %s", __func__, c->self, + (fwd_desc = format_forward(ftype, &fwd))); + + /* make sure this has been requested */ + found_fwd = NULL; + 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)) { + found_fwd = options.local_forwards + i; + break; + } + } + break; + case MUX_FWD_REMOTE: + for (i = 0; i < options.num_remote_forwards; i++) { + if (compare_forward(&fwd, + options.remote_forwards + i)) { + found_fwd = options.remote_forwards + i; + break; + } + } + break; + } + + if (found_fwd == NULL) + error_reason = "port not forwarded"; + else if (ftype == MUX_FWD_REMOTE) { + /* + * This shouldn't fail unless we confused the host/port + * between options.remote_forwards and permitted_opens. + * However, for dynamic allocated listen ports we need + * to lookup the actual listen port. + */ + listen_port = (fwd.listen_port == 0) ? + found_fwd->allocated_port : fwd.listen_port; + if (channel_request_rforward_cancel(fwd.listen_host, + listen_port) == -1) + error_reason = "port not in permitted opens"; + } else { /* local and dynamic forwards */ + /* Ditto */ + if (channel_cancel_lport_listener(fwd.listen_host, + fwd.listen_port, fwd.connect_port, + options.gateway_ports) == -1) + error_reason = "port not found"; + } + + if (error_reason == NULL) { + buffer_put_int(r, MUX_S_OK); + buffer_put_int(r, rid); + + free(found_fwd->listen_host); + free(found_fwd->connect_host); + found_fwd->listen_host = found_fwd->connect_host = NULL; + found_fwd->listen_port = found_fwd->connect_port = 0; + } else { + buffer_put_int(r, MUX_S_FAILURE); + buffer_put_int(r, rid); + buffer_put_cstring(r, error_reason); + } + out: + free(fwd_desc); + free(fwd.listen_host); + free(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) { + free(reserved); + free(chost); + error("%s: malformed message", __func__); + return -1; + } + free(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]); + free(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]); + free(chost); + return 0; + } + + if (options.control_master == SSHCTL_MASTER_ASK || + options.control_master == SSHCTL_MASTER_AUTO_ASK) { + if (!ask_permission("Allow forward 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, 1); + + /* 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; +} + +static int +process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r) +{ + debug("%s: channel %d: stop listening", __func__, c->self); + + if (options.control_master == SSHCTL_MASTER_ASK || + options.control_master == SSHCTL_MASTER_AUTO_ASK) { + if (!ask_permission("Disable further multiplexing on shared " + "connection to %s? ", host)) { + debug2("%s: stop listen 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; + } + } + + if (mux_listener_channel != NULL) { + channel_free(mux_listener_channel); + client_stop_mux(); + free(options.control_path); + options.control_path = NULL; + mux_listener_channel = NULL; + muxserver_sock = -1; + } + + /* prepare reply */ + buffer_put_int(r, MUX_S_OK); + buffer_put_int(r, rid); + + 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, exitval %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); + + buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m)); + buffer_free(&m); +} + +void +mux_tty_alloc_failed(Channel *c) +{ + Buffer m; + Channel *mux_chan; + + debug3("%s: channel %d: TTY alloc failed", __func__, c->self); + + 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_TTY_ALLOC_FAIL); + buffer_put_int(&m, c->self); + + 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; + char *orig_control_path = options.control_path; + char rbuf[16+1]; + u_int i, r; + + if (options.control_path == NULL || + options.control_master == SSHCTL_MASTER_NO) + return; + + debug("setting up multiplex master socket"); + + /* + * Use a temporary path before listen so we can pseudo-atomically + * establish the listening socket in its final location to avoid + * other processes racing in between bind() and listen() and hitting + * an unready socket. + */ + for (i = 0; i < sizeof(rbuf) - 1; i++) { + r = arc4random_uniform(26+26+10); + rbuf[i] = (r < 26) ? 'a' + r : + (r < 26*2) ? 'A' + r - 26 : + '0' + r - 26 - 26; + } + rbuf[sizeof(rbuf) - 1] = '\0'; + options.control_path = NULL; + xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); + debug3("%s: temporary control path %s", __func__, options.control_path); + + 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)) { + error("ControlPath \"%s\" too long for Unix domain socket", + options.control_path); + goto disable_mux_master; + } + + 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) { + if (errno == EINVAL || errno == EADDRINUSE) { + error("ControlSocket %s already exists, " + "disabling multiplexing", options.control_path); + disable_mux_master: + if (muxserver_sock != -1) { + close(muxserver_sock); + muxserver_sock = -1; + } + free(orig_control_path); + free(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)); + + /* Now atomically "move" the mux socket into position */ + if (link(options.control_path, orig_control_path) != 0) { + if (errno != EEXIST) { + fatal("%s: link mux listener %s => %s: %s", __func__, + options.control_path, orig_control_path, + strerror(errno)); + } + error("ControlSocket %s already exists, disabling multiplexing", + orig_control_path); + unlink(options.control_path); + goto disable_mux_master; + } + unlink(options.control_path); + free(options.control_path); + options.control_path = orig_control_path; + + 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, options.control_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, int success, void *arg) +{ + struct mux_session_confirm_ctx *cctx = arg; + const char *display; + Channel *c, *cc; + int i; + Buffer reply; + + if (cctx == NULL) + fatal("%s: cctx == NULL", __func__); + if ((c = channel_by_id(id)) == NULL) + fatal("%s: no channel for id %d", __func__, id); + if ((cc = channel_by_id(c->ctl_chan)) == NULL) + fatal("%s: channel %d lacks control channel %d", __func__, + id, c->ctl_chan); + + if (!success) { + debug3("%s: sending failure reply", __func__); + /* prepare reply */ + buffer_init(&reply); + buffer_put_int(&reply, MUX_S_FAILURE); + buffer_put_int(&reply, cctx->rid); + buffer_put_cstring(&reply, "Session open refused by peer"); + goto done; + } + + 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, options.forward_x11_timeout, + &proto, &data); + /* Request forwarding with authentication spoofing. */ + debug("Requesting X11 forwarding with authentication " + "spoofing."); + x11_request_forwarding_with_spoofing(id, display, proto, + data, 1); + client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); + /* XXX exit_on_forward_failure */ + } + + 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); + + debug3("%s: sending success reply", __func__); + /* prepare reply */ + buffer_init(&reply); + buffer_put_int(&reply, MUX_S_SESSION_OPENED); + buffer_put_int(&reply, cctx->rid); + buffer_put_int(&reply, c->self); + + done: + /* Send reply */ + buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply)); + buffer_free(&reply); + + if (cc->mux_pause <= 0) + fatal("%s: mux_pause %d", __func__, cc->mux_pause); + cc->mux_pause = 0; /* start processing messages again */ + c->open_confirm_ctx = NULL; + buffer_free(&cctx->cmd); + free(cctx->term); + if (cctx->env != NULL) { + for (i = 0; cctx->env[i] != NULL; i++) + free(cctx->env[i]); + free(cctx->env); + } + free(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)); + buffer_free(&queue); + 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)); + buffer_free(&queue); + 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); + + /* Read their HELLO */ + if (mux_client_read_packet(fd, &m) != 0) { + buffer_free(&m); + return -1; + } + + 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); + free(name); + free(value); + } + 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; + } + + type = buffer_get_int(&m); + if (type != MUX_S_ALIVE) { + e = buffer_get_string(&m, NULL); + fatal("%s: master returned error: %s", __func__, e); + } + + 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); + + /* 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("%s: unexpected response from master 0x%08x", + __func__, type); + } + buffer_free(&m); + muxclient_request_id++; +} + +static int +mux_client_forward(int fd, int cancel_flag, u_int ftype, Forward *fwd) +{ + Buffer m; + char *e, *fwd_desc; + u_int type, rid; + + fwd_desc = format_forward(ftype, fwd); + debug("Requesting %s %s", + cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); + free(fwd_desc); + + buffer_init(&m); + buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : 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); + + /* Read their reply */ + if (mux_client_read_packet(fd, &m) != 0) { + 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_OK: + break; + case MUX_S_REMOTE_PORT: + if (cancel_flag) + fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); + fwd->allocated_port = buffer_get_int(&m); + logit("Allocated port %u for remote forward to %s:%d", + fwd->allocated_port, + fwd->connect_host ? fwd->connect_host : "", + fwd->connect_port); + if (muxclient_command == SSHMUX_COMMAND_FORWARD) + fprintf(stdout, "%u\n", fwd->allocated_port); + 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: + fatal("%s: unexpected response from master 0x%08x", + __func__, type); + } + buffer_free(&m); + + muxclient_request_id++; + return 0; +} + +static int +mux_client_forwards(int fd, int cancel_flag) +{ + int i, ret = 0; + + debug3("%s: %s forwardings: %d local, %d remote", __func__, + cancel_flag ? "cancel" : "request", + options.num_local_forwards, options.num_remote_forwards); + + /* XXX ExitOnForwardingFailure */ + for (i = 0; i < options.num_local_forwards; i++) { + if (mux_client_forward(fd, cancel_flag, + options.local_forwards[i].connect_port == 0 ? + MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, + options.local_forwards + i) != 0) + ret = -1; + } + for (i = 0; i < options.num_remote_forwards; i++) { + if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, + options.remote_forwards + i) != 0) + ret = -1; + } + return ret; +} + +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, rawmode; + + 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 (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 session 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: + 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); + + rawmode = tty_flag; + if (tty_flag) + enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); + + /* + * Stick around until the controlee closes the client_fd. + * 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). + */ + for (exitval = 255, exitval_seen = 0;;) { + buffer_clear(&m); + if (mux_client_read_packet(fd, &m) != 0) + break; + type = buffer_get_int(&m); + switch (type) { + case MUX_S_TTY_ALLOC_FAIL: + if ((esid = buffer_get_int(&m)) != sid) + fatal("%s: tty alloc fail on unknown session: " + "my id %u theirs %u", + __func__, sid, esid); + leave_raw_mode(options.request_tty == + REQUEST_TTY_FORCE); + rawmode = 0; + continue; + case MUX_S_EXIT_MESSAGE: + if ((esid = buffer_get_int(&m)) != sid) + fatal("%s: exit on unknown session: " + "my id %u theirs %u", + __func__, sid, esid); + if (exitval_seen) + fatal("%s: exitval sent twice", __func__); + exitval = buffer_get_int(&m); + exitval_seen = 1; + continue; + default: + e = buffer_get_string(&m, NULL); + fatal("%s: master returned error: %s", __func__, e); + } + } + + close(fd); + if (rawmode) + leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); + + if (muxclient_terminate) { + debug2("Exiting on signal %ld", (long)muxclient_terminate); + exitval = 255; + } else if (!exitval_seen) { + debug2("Control master terminated unexpectedly"); + exitval = 255; + } else + 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); +} + +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 stdio 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); +} + +static void +mux_client_request_stop_listening(int fd) +{ + Buffer m; + char *e; + u_int type, rid; + + debug3("%s: entering", __func__); + + buffer_init(&m); + buffer_put_int(&m, MUX_C_STOP_LISTENING); + 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) + 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 stop listening request: %s", e); + case MUX_S_FAILURE: + e = buffer_get_string(&m, NULL); + fatal("%s: stop listening request failed: %s", __func__, e); + default: + fatal("%s: unexpected response from master 0x%08x", + __func__, type); + } + buffer_free(&m); + muxclient_request_id++; +} + +/* 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 == ECONNREFUSED && + options.control_master != SSHCTL_MASTER_NO) { + debug("Stale control socket %.100s, unlinking", path); + unlink(path); + } else 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_FORWARD: + if (mux_client_forwards(sock, 0) != 0) + fatal("%s: master forward request failed", __func__); + exit(0); + case SSHMUX_COMMAND_OPEN: + if (mux_client_forwards(sock, 0) != 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); + case SSHMUX_COMMAND_STOP: + mux_client_request_stop_listening(sock); + fprintf(stderr, "Stop listening request sent.\r\n"); + exit(0); + case SSHMUX_COMMAND_CANCEL_FWD: + if (mux_client_forwards(sock, 1) != 0) + error("%s: master cancel forward request failed", + __func__); + exit(0); + default: + fatal("unrecognised muxclient_command %d", muxclient_command); + } +} |
