diff options
Diffstat (limited to 'crypto/openssh/mux.c')
| -rw-r--r-- | crypto/openssh/mux.c | 1851 |
1 files changed, 1435 insertions, 416 deletions
diff --git a/crypto/openssh/mux.c b/crypto/openssh/mux.c index 79f8376..825fb7a 100644 --- a/crypto/openssh/mux.c +++ b/crypto/openssh/mux.c @@ -1,4 +1,4 @@ -/* $OpenBSD: mux.c,v 1.7 2008/06/13 17:21:20 dtucker Exp $ */ +/* $OpenBSD: mux.c,v 1.14 2010/01/30 02:54:53 djm Exp $ */ /* * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org> * @@ -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 <sys/types.h> #include <sys/param.h> #include <sys/stat.h> @@ -55,6 +51,14 @@ #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 @@ -82,18 +86,22 @@ /* from ssh.c */ extern int tty_flag; +extern int force_tty_flag; extern Options options; extern int stdin_null_flag; extern char *host; -int subsystem_flag; +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; @@ -103,6 +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; @@ -112,16 +123,831 @@ 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_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 } +}; + +/* 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) + debug2("%s: channel %d n session channel %d", + __func__, c->self, c->remote_id); + c->remote_id = -1; + sc->ctl_chan = -1; + if (sc->type != SSH_CHANNEL_OPEN) { + 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) { + if (name != NULL) + xfree(name); + goto malf; + } + 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 */ + 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; + } + 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; + } + } + + 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)); + xfree(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++) + xfree(cctx->env[j]); + if (env_len > 0) + xfree(cctx->env); + xfree(cctx->term); + buffer_free(&cctx->cmd); + xfree(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]); + 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; + } + + 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); + channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 0); + + /* 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); + + 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 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; + } + } + break; + case MUX_FWD_REMOTE: + for (i = 0; i < options.num_remote_forwards; i++) { + if (compare_forward(&fwd, + options.remote_forwards + i)) + goto exists; + } + 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 (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; +} + +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; + } + + 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]); -/* ** Multiplexing master support */ + 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); + + 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; - int addr_len; if (options.control_path == NULL || options.control_master == SSHCTL_MASTER_NO) @@ -131,7 +957,7 @@ muxserver_listen(void) memset(&addr, '\0', sizeof(addr)); addr.sun_family = AF_UNIX; - addr_len = offsetof(struct sockaddr_un, sun_path) + + sun_len = offsetof(struct sockaddr_un, sun_path) + strlen(options.control_path) + 1; if (strlcpy(addr.sun_path, options.control_path, @@ -142,7 +968,7 @@ muxserver_listen(void) fatal("%s socket(): %s", __func__, strerror(errno)); old_umask = umask(0177); - if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) { + if (bind(muxserver_sock, (struct sockaddr *)&addr, sun_len) == -1) { muxserver_sock = -1; if (errno == EINVAL || errno == EADDRINUSE) { error("ControlSocket %s already exists, " @@ -162,6 +988,14 @@ muxserver_listen(void) 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. */ @@ -175,7 +1009,7 @@ mux_session_confirm(int id, void *arg) if (cctx == NULL) fatal("%s: cctx == NULL", __func__); - if ((c = channel_lookup(id)) == NULL) + if ((c = channel_by_id(id)) == NULL) fatal("%s: no channel for id %d", __func__, id); display = getenv("DISPLAY"); @@ -210,291 +1044,616 @@ mux_session_confirm(int id, void *arg) xfree(cctx); } +/* ** Multiplexing client support */ + +/* Exit signal handler */ +static void +control_client_sighandler(int signo) +{ + muxclient_terminate = signo; +} + /* - * Accept a connection on the mux master socket and process the - * client's request. Returns flag indicating whether mux master should - * begin graceful close. + * Relay signal handler - used to pass some signals from mux client to + * mux master. */ -int -muxserver_accept_control(void) +static void +control_client_sigrelay(int signo) { - 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; + int save_errno = errno; - /* - * 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; + 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; +} - if (getpeereid(client_fd, &euid, &egid) < 0) { - error("%s getpeereid failed: %s", __func__, strerror(errno)); - close(client_fd); - 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; } - if ((euid != 0) && (getuid() != euid)) { - error("control mode uid mismatch: peer euid %u != uid %u", - (u_int) euid, (u_int) getuid()); - close(client_fd); - return 0; + 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; +} - /* XXX handle asynchronously */ - unset_nonblock(client_fd); +static int +mux_client_hello_exchange(int fd) +{ + Buffer m; + u_int type, ver; - /* Read command */ buffer_init(&m); - if (ssh_msg_recv(client_fd, &m) == -1) { - error("%s: client msg_recv failed", __func__); - close(client_fd); + 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 0; + 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); + xfree(name); + xfree(value); } - if ((ver = buffer_get_char(&m)) != SSHMUX_VER) { - error("%s: wrong client version %d", __func__, ver); + 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); - close(client_fd); return 0; } - allowed = 1; - mux_command = buffer_get_int(&m); - flags = buffer_get_int(&m); + 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); - 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); + /* Read their reply */ + if (mux_client_read_packet(fd, &m) != 0) { + /* Remote end exited already */ + if (errno == EPIPE) { buffer_free(&m); - return start_close; + return; } - buffer_free(&m); - close(client_fd); - return start_close; + 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: - error("Unsupported command %d", mux_command); - buffer_free(&m); - close(client_fd); - return 0; + 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)); - /* 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); + + /* Read their reply */ + if (mux_client_read_packet(fd, &m) != 0) { buffer_free(&m); - return 0; + return -1; } - if (!allowed) { - error("Refused control connection"); - close(client_fd); + 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); - return 0; + 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); - 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; + muxclient_request_id++; + return 0; +} + +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; } - if ((ver = buffer_get_char(&m)) != SSHMUX_VER) { - error("%s: wrong client version %d", __func__, ver); - buffer_free(&m); - close(client_fd); - return 0; + 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; +} - 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)); +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__); - 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; + if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { + error("%s: master alive request failed", __func__); + return -1; } - debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__, - cctx->want_tty, cctx->want_subsys, cmd); - xfree(cmd); + signal(SIGPIPE, SIG_IGN); - /* Gather fds from client */ - for(i = 0; i < 3; i++) { - if ((new_fd[i] = mm_receive_fd(client_fd)) == -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++) - xfree(cctx->env[j]); - if (env_len > 0) - xfree(cctx->env); - xfree(cctx->term); - buffer_free(&cctx->cmd); - close(client_fd); - xfree(cctx); - return 0; + 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]); + } } } - debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__, - new_fd[0], new_fd[1], new_fd[2]); + if (mux_client_write_packet(fd, &m) != 0) + fatal("%s: write packet: %s", __func__, strerror(errno)); - /* 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)); + /* 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__); - /* This roundtrip is just for synchronisation of ttymodes */ + /* Read their reply */ buffer_clear(&m); - if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) { - error("%s: client msg_send failed", __func__); - close(client_fd); - close(new_fd[0]); - close(new_fd[1]); - close(new_fd[2]); + if (mux_client_read_packet(fd, &m) != 0) { + error("%s: read from master failed: %s", + __func__, strerror(errno)); buffer_free(&m); - xfree(cctx->term); - if (env_len != 0) { - for (i = 0; i < env_len; i++) - xfree(cctx->env[i]); - xfree(cctx->env); - } - return 0; + return -1; } - buffer_free(&m); - /* 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]); + 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++; - set_nonblock(client_fd); + signal(SIGHUP, control_client_sighandler); + signal(SIGINT, control_client_sighandler); + signal(SIGTERM, control_client_sighandler); + signal(SIGWINCH, control_client_sigrelay); - 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, - new_fd[0], new_fd[1], new_fd[2], window, packetmax, - CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); + if (tty_flag) + enter_raw_mode(force_tty_flag); - c->ctl_fd = client_fd; - if (cctx->want_tty && escape_char != 0xffffffff) { - channel_register_filter(c->self, - client_simple_escape_filter, NULL, - client_filter_cleanup, - client_new_escape_filter_ctx((int)escape_char)); + /* + * 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); + if (type != MUX_S_EXIT_MESSAGE) { + e = buffer_get_string(&m, NULL); + fatal("%s: master returned error: %s", __func__, e); + } + 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; } - debug3("%s: channel_new: %d", __func__, c->self); + close(fd); + leave_raw_mode(force_tty_flag); - channel_send_open(c->self); - channel_register_open_confirm(c->self, mux_session_confirm, cctx); - return 0; -} + if (muxclient_terminate) { + debug2("Exiting on signal %d", muxclient_terminate); + exitval = 255; + } else if (!exitval_seen) { + debug2("Control master terminated unexpectedly"); + exitval = 255; + } else + debug2("Received exit status from master %d", exitval); -/* ** Multiplexing client support */ + if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) + fprintf(stderr, "Shared connection to %s closed.\r\n", host); -/* Exit signal handler */ -static void -control_client_sighandler(int signo) -{ - muxclient_terminate = signo; + exit(exitval); } -/* - * Relay signal handler - used to pass some signals from mux client to - * mux master. - */ -static void -control_client_sigrelay(int signo) +static int +mux_client_request_stdio_fwd(int fd) { - int save_errno = errno; + Buffer m; + char *e; + u_int type, rid, sid; + int devnull; - if (muxserver_pid > 1) - kill(muxserver_pid, signo); + debug3("%s: entering", __func__); - errno = save_errno; -} + if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { + error("%s: master alive request failed", __func__); + return -1; + } -/* Check mux client environment variables before passing them to mux master. */ -static int -env_permitted(char *env) -{ - int i, ret; - char name[1024], *cp; + signal(SIGPIPE, SIG_IGN); - 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); + 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); + } - for (i = 0; i < options.num_send_env; i++) - if (match_pattern(name, options.send_env[i])) - return (1); + 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); - return (0); + /* + * 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. */ @@ -502,14 +1661,16 @@ void muxclient(const char *path) { 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; + socklen_t sun_len; + int sock; + u_int pid; - if (muxclient_command == 0) - muxclient_command = SSHMUX_COMMAND_OPEN; + 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: @@ -524,7 +1685,7 @@ muxclient(const char *path) memset(&addr, '\0', sizeof(addr)); addr.sun_family = AF_UNIX; - addr_len = offsetof(struct sockaddr_un, sun_path) + + sun_len = offsetof(struct sockaddr_un, sun_path) + strlen(path) + 1; if (strlcpy(addr.sun_path, path, @@ -534,8 +1695,12 @@ muxclient(const char *path) if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) fatal("%s socket(): %s", __func__, strerror(errno)); - if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) { - if (muxclient_command != SSHMUX_COMMAND_OPEN) { + 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)); } @@ -548,181 +1713,35 @@ muxclient(const char *path) close(sock); return; } + set_nonblock(sock); - 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); - } - - term = getenv("TERM"); - - 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; - - signal(SIGPIPE, SIG_IGN); - - buffer_init(&m); - - /* 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: + if (mux_client_hello_exchange(sock) != 0) { + error("%s: master hello exchange failed", __func__); 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; return; } - 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; - } - if (buffer_get_char(&m) != SSHMUX_VER) { - error("%s: Master replied with wrong version", __func__); - goto muxerr; - } - if (buffer_get_int_ret(&allowed, &m) != 0) { - error("%s: bad server reply", __func__); - goto muxerr; - } - if (allowed != 1) { - error("Connection to master denied"); - goto muxerr; - } - muxserver_pid = buffer_get_int(&m); - - buffer_clear(&m); switch (muxclient_command) { case SSHMUX_COMMAND_ALIVE_CHECK: - fprintf(stderr, "Master running (pid=%d)\r\n", - muxserver_pid); + 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: - 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]); - } - } + if (mux_client_request_forwards(sock) != 0) { + error("%s: master forward request failed", __func__); + return; } - break; + 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); } - - if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1) { - error("%s: msg_send", __func__); - goto muxerr; - } - - 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; - } - - /* - * Mux errors are non-recoverable from this point as the master - * has ownership of the session now. - */ - - /* Wait for reply, so master has a chance to gather ttymodes */ - 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); - - signal(SIGHUP, control_client_sighandler); - signal(SIGINT, control_client_sighandler); - signal(SIGTERM, control_client_sighandler); - signal(SIGWINCH, control_client_sigrelay); - - if (tty_flag) - enter_raw_mode(); - - /* - * 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). - */ - 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"); - break; - } - if (r == -1) { - if (errno == EINTR) - continue; - fatal("%s: read %s", __func__, strerror(errno)); - } - i += r; - } - - close(sock); - leave_raw_mode(); - 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)) { - debug2("Control master terminated unexpectedly"); - exitval[0] = 255; - } else - debug2("Received exit status from master %d", exitval[0]); - - if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) - fprintf(stderr, "Shared connection to %s closed.\r\n", host); - - exit(exitval[0]); } |
