diff options
Diffstat (limited to 'channels.c')
| -rw-r--r-- | channels.c | 4876 |
1 files changed, 4876 insertions, 0 deletions
diff --git a/channels.c b/channels.c new file mode 100644 index 0000000..c85d46a --- /dev/null +++ b/channels.c @@ -0,0 +1,4876 @@ +/* $OpenBSD: channels.c,v 1.386 2018/10/04 01:04:52 djm Exp $ */ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * This file contains functions for generic socket connection forwarding. + * There is also code for initiating connection forwarding for X11 connections, + * arbitrary tcp/ip connections, and the authentication agent connection. + * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". + * + * SSH2 support added by Markus Friedl. + * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. + * Copyright (c) 1999 Dug Song. All rights reserved. + * Copyright (c) 1999 Theo de Raadt. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "includes.h" + +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/ioctl.h> +#include <sys/un.h> +#include <sys/socket.h> +#ifdef HAVE_SYS_TIME_H +# include <sys/time.h> +#endif + +#include <netinet/in.h> +#include <arpa/inet.h> + +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <netdb.h> +#include <stdarg.h> +#ifdef HAVE_STDINT_H + #include <stdint.h> +#endif +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <termios.h> +#include <unistd.h> + +#include "openbsd-compat/sys-queue.h" +#include "xmalloc.h" +#include "ssh.h" +#include "ssh2.h" +#include "ssherr.h" +#include "sshbuf.h" +#include "packet.h" +#include "log.h" +#include "misc.h" +#include "channels.h" +#include "compat.h" +#include "canohost.h" +#include "sshkey.h" +#include "authfd.h" +#include "pathnames.h" +#include "match.h" + +/* -- agent forwarding */ +#define NUM_SOCKS 10 + +/* -- tcp forwarding */ +/* special-case port number meaning allow any port */ +#define FWD_PERMIT_ANY_PORT 0 + +/* special-case wildcard meaning allow any host */ +#define FWD_PERMIT_ANY_HOST "*" + +/* -- X11 forwarding */ +/* Maximum number of fake X11 displays to try. */ +#define MAX_DISPLAYS 1000 + +/* Per-channel callback for pre/post select() actions */ +typedef void chan_fn(struct ssh *, Channel *c, + fd_set *readset, fd_set *writeset); + +/* + * Data structure for storing which hosts are permitted for forward requests. + * The local sides of any remote forwards are stored in this array to prevent + * a corrupt remote server from accessing arbitrary TCP/IP ports on our local + * network (which might be behind a firewall). + */ +/* XXX: streamlocal wants a path instead of host:port */ +/* Overload host_to_connect; we could just make this match Forward */ +/* XXX - can we use listen_host instead of listen_path? */ +struct permission { + char *host_to_connect; /* Connect to 'host'. */ + int port_to_connect; /* Connect to 'port'. */ + char *listen_host; /* Remote side should listen address. */ + char *listen_path; /* Remote side should listen path. */ + int listen_port; /* Remote side should listen port. */ + Channel *downstream; /* Downstream mux*/ +}; + +/* + * Stores the forwarding permission state for a single direction (local or + * remote). + */ +struct permission_set { + /* + * List of all local permitted host/port pairs to allow for the + * user. + */ + u_int num_permitted_user; + struct permission *permitted_user; + + /* + * List of all permitted host/port pairs to allow for the admin. + */ + u_int num_permitted_admin; + struct permission *permitted_admin; + + /* + * If this is true, all opens/listens are permitted. This is the + * case on the server on which we have to trust the client anyway, + * and the user could do anything after logging in. + */ + int all_permitted; +}; + +/* Master structure for channels state */ +struct ssh_channels { + /* + * Pointer to an array containing all allocated channels. The array + * is dynamically extended as needed. + */ + Channel **channels; + + /* + * Size of the channel array. All slots of the array must always be + * initialized (at least the type field); unused slots set to NULL + */ + u_int channels_alloc; + + /* + * Maximum file descriptor value used in any of the channels. This is + * updated in channel_new. + */ + int channel_max_fd; + + /* + * 'channel_pre*' are called just before select() to add any bits + * relevant to channels in the select bitmasks. + * + * 'channel_post*': perform any appropriate operations for + * channels which have events pending. + */ + chan_fn **channel_pre; + chan_fn **channel_post; + + /* -- tcp forwarding */ + struct permission_set local_perms; + struct permission_set remote_perms; + + /* -- X11 forwarding */ + + /* Saved X11 local (client) display. */ + char *x11_saved_display; + + /* Saved X11 authentication protocol name. */ + char *x11_saved_proto; + + /* Saved X11 authentication data. This is the real data. */ + char *x11_saved_data; + u_int x11_saved_data_len; + + /* Deadline after which all X11 connections are refused */ + u_int x11_refuse_time; + + /* + * Fake X11 authentication data. This is what the server will be + * sending us; we should replace any occurrences of this by the + * real data. + */ + u_char *x11_fake_data; + u_int x11_fake_data_len; + + /* AF_UNSPEC or AF_INET or AF_INET6 */ + int IPv4or6; +}; + +/* helper */ +static void port_open_helper(struct ssh *ssh, Channel *c, char *rtype); +static const char *channel_rfwd_bind_host(const char *listen_host); + +/* non-blocking connect helpers */ +static int connect_next(struct channel_connect *); +static void channel_connect_ctx_free(struct channel_connect *); +static Channel *rdynamic_connect_prepare(struct ssh *, char *, char *); +static int rdynamic_connect_finish(struct ssh *, Channel *); + +/* Setup helper */ +static void channel_handler_init(struct ssh_channels *sc); + +/* -- channel core */ + +void +channel_init_channels(struct ssh *ssh) +{ + struct ssh_channels *sc; + + if ((sc = calloc(1, sizeof(*sc))) == NULL || + (sc->channel_pre = calloc(SSH_CHANNEL_MAX_TYPE, + sizeof(*sc->channel_pre))) == NULL || + (sc->channel_post = calloc(SSH_CHANNEL_MAX_TYPE, + sizeof(*sc->channel_post))) == NULL) + fatal("%s: allocation failed", __func__); + sc->channels_alloc = 10; + sc->channels = xcalloc(sc->channels_alloc, sizeof(*sc->channels)); + sc->IPv4or6 = AF_UNSPEC; + channel_handler_init(sc); + + ssh->chanctxt = sc; +} + +Channel * +channel_by_id(struct ssh *ssh, int id) +{ + Channel *c; + + if (id < 0 || (u_int)id >= ssh->chanctxt->channels_alloc) { + logit("%s: %d: bad id", __func__, id); + return NULL; + } + c = ssh->chanctxt->channels[id]; + if (c == NULL) { + logit("%s: %d: bad id: channel free", __func__, id); + return NULL; + } + return c; +} + +Channel * +channel_by_remote_id(struct ssh *ssh, u_int remote_id) +{ + Channel *c; + u_int i; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + c = ssh->chanctxt->channels[i]; + if (c != NULL && c->have_remote_id && c->remote_id == remote_id) + return c; + } + return NULL; +} + +/* + * Returns the channel if it is allowed to receive protocol messages. + * Private channels, like listening sockets, may not receive messages. + */ +Channel * +channel_lookup(struct ssh *ssh, int id) +{ + Channel *c; + + if ((c = channel_by_id(ssh, id)) == NULL) + return NULL; + + switch (c->type) { + case SSH_CHANNEL_X11_OPEN: + case SSH_CHANNEL_LARVAL: + case SSH_CHANNEL_CONNECTING: + case SSH_CHANNEL_DYNAMIC: + case SSH_CHANNEL_RDYNAMIC_OPEN: + case SSH_CHANNEL_RDYNAMIC_FINISH: + case SSH_CHANNEL_OPENING: + case SSH_CHANNEL_OPEN: + case SSH_CHANNEL_ABANDONED: + case SSH_CHANNEL_MUX_PROXY: + return c; + } + logit("Non-public channel %d, type %d.", id, c->type); + return NULL; +} + +/* + * Register filedescriptors for a channel, used when allocating a channel or + * when the channel consumer/producer is ready, e.g. shell exec'd + */ +static void +channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd, + int extusage, int nonblock, int is_tty) +{ + struct ssh_channels *sc = ssh->chanctxt; + + /* Update the maximum file descriptor value. */ + sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, rfd); + sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, wfd); + sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, efd); + + if (rfd != -1) + fcntl(rfd, F_SETFD, FD_CLOEXEC); + if (wfd != -1 && wfd != rfd) + fcntl(wfd, F_SETFD, FD_CLOEXEC); + if (efd != -1 && efd != rfd && efd != wfd) + fcntl(efd, F_SETFD, FD_CLOEXEC); + + c->rfd = rfd; + c->wfd = wfd; + c->sock = (rfd == wfd) ? rfd : -1; + c->efd = efd; + c->extended_usage = extusage; + + if ((c->isatty = is_tty) != 0) + debug2("channel %d: rfd %d isatty", c->self, c->rfd); +#ifdef _AIX + /* XXX: Later AIX versions can't push as much data to tty */ + c->wfd_isatty = is_tty || isatty(c->wfd); +#endif + + /* enable nonblocking mode */ + if (nonblock) { + if (rfd != -1) + set_nonblock(rfd); + if (wfd != -1) + set_nonblock(wfd); + if (efd != -1) + set_nonblock(efd); + } +} + +/* + * Allocate a new channel object and set its type and socket. This will cause + * remote_name to be freed. + */ +Channel * +channel_new(struct ssh *ssh, char *ctype, int type, int rfd, int wfd, int efd, + u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock) +{ + struct ssh_channels *sc = ssh->chanctxt; + u_int i, found; + Channel *c; + + /* Try to find a free slot where to put the new channel. */ + for (i = 0; i < sc->channels_alloc; i++) { + if (sc->channels[i] == NULL) { + /* Found a free slot. */ + found = i; + break; + } + } + if (i >= sc->channels_alloc) { + /* + * There are no free slots. Take last+1 slot and expand + * the array. + */ + found = sc->channels_alloc; + if (sc->channels_alloc > CHANNELS_MAX_CHANNELS) + fatal("%s: internal error: channels_alloc %d too big", + __func__, sc->channels_alloc); + sc->channels = xrecallocarray(sc->channels, sc->channels_alloc, + sc->channels_alloc + 10, sizeof(*sc->channels)); + sc->channels_alloc += 10; + debug2("channel: expanding %d", sc->channels_alloc); + } + /* Initialize and return new channel. */ + c = sc->channels[found] = xcalloc(1, sizeof(Channel)); + if ((c->input = sshbuf_new()) == NULL || + (c->output = sshbuf_new()) == NULL || + (c->extended = sshbuf_new()) == NULL) + fatal("%s: sshbuf_new failed", __func__); + c->ostate = CHAN_OUTPUT_OPEN; + c->istate = CHAN_INPUT_OPEN; + channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, 0); + c->self = found; + c->type = type; + c->ctype = ctype; + c->local_window = window; + c->local_window_max = window; + c->local_maxpacket = maxpack; + c->remote_name = xstrdup(remote_name); + c->ctl_chan = -1; + c->delayed = 1; /* prevent call to channel_post handler */ + TAILQ_INIT(&c->status_confirms); + debug("channel %d: new [%s]", found, remote_name); + return c; +} + +static void +channel_find_maxfd(struct ssh_channels *sc) +{ + u_int i; + int max = 0; + Channel *c; + + for (i = 0; i < sc->channels_alloc; i++) { + c = sc->channels[i]; + if (c != NULL) { + max = MAXIMUM(max, c->rfd); + max = MAXIMUM(max, c->wfd); + max = MAXIMUM(max, c->efd); + } + } + sc->channel_max_fd = max; +} + +int +channel_close_fd(struct ssh *ssh, int *fdp) +{ + struct ssh_channels *sc = ssh->chanctxt; + int ret = 0, fd = *fdp; + + if (fd != -1) { + ret = close(fd); + *fdp = -1; + if (fd == sc->channel_max_fd) + channel_find_maxfd(sc); + } + return ret; +} + +/* Close all channel fd/socket. */ +static void +channel_close_fds(struct ssh *ssh, Channel *c) +{ + int sock = c->sock, rfd = c->rfd, wfd = c->wfd, efd = c->efd; + + channel_close_fd(ssh, &c->sock); + if (rfd != sock) + channel_close_fd(ssh, &c->rfd); + if (wfd != sock && wfd != rfd) + channel_close_fd(ssh, &c->wfd); + if (efd != sock && efd != rfd && efd != wfd) + channel_close_fd(ssh, &c->efd); +} + +static void +fwd_perm_clear(struct permission *perm) +{ + free(perm->host_to_connect); + free(perm->listen_host); + free(perm->listen_path); + bzero(perm, sizeof(*perm)); +} + +/* Returns an printable name for the specified forwarding permission list */ +static const char * +fwd_ident(int who, int where) +{ + if (who == FORWARD_ADM) { + if (where == FORWARD_LOCAL) + return "admin local"; + else if (where == FORWARD_REMOTE) + return "admin remote"; + } else if (who == FORWARD_USER) { + if (where == FORWARD_LOCAL) + return "user local"; + else if (where == FORWARD_REMOTE) + return "user remote"; + } + fatal("Unknown forward permission list %d/%d", who, where); +} + +/* Returns the forwarding permission list for the specified direction */ +static struct permission_set * +permission_set_get(struct ssh *ssh, int where) +{ + struct ssh_channels *sc = ssh->chanctxt; + + switch (where) { + case FORWARD_LOCAL: + return &sc->local_perms; + break; + case FORWARD_REMOTE: + return &sc->remote_perms; + break; + default: + fatal("%s: invalid forwarding direction %d", __func__, where); + } +} + +/* Reutrns pointers to the specified forwarding list and its element count */ +static void +permission_set_get_array(struct ssh *ssh, int who, int where, + struct permission ***permpp, u_int **npermpp) +{ + struct permission_set *pset = permission_set_get(ssh, where); + + switch (who) { + case FORWARD_USER: + *permpp = &pset->permitted_user; + *npermpp = &pset->num_permitted_user; + break; + case FORWARD_ADM: + *permpp = &pset->permitted_admin; + *npermpp = &pset->num_permitted_admin; + break; + default: + fatal("%s: invalid forwarding client %d", __func__, who); + } +} + +/* Adds an entry to the spcified forwarding list */ +static int +permission_set_add(struct ssh *ssh, int who, int where, + const char *host_to_connect, int port_to_connect, + const char *listen_host, const char *listen_path, int listen_port, + Channel *downstream) +{ + struct permission **permp; + u_int n, *npermp; + + permission_set_get_array(ssh, who, where, &permp, &npermp); + + if (*npermp >= INT_MAX) + fatal("%s: %s overflow", __func__, fwd_ident(who, where)); + + *permp = xrecallocarray(*permp, *npermp, *npermp + 1, sizeof(**permp)); + n = (*npermp)++; +#define MAYBE_DUP(s) ((s == NULL) ? NULL : xstrdup(s)) + (*permp)[n].host_to_connect = MAYBE_DUP(host_to_connect); + (*permp)[n].port_to_connect = port_to_connect; + (*permp)[n].listen_host = MAYBE_DUP(listen_host); + (*permp)[n].listen_path = MAYBE_DUP(listen_path); + (*permp)[n].listen_port = listen_port; + (*permp)[n].downstream = downstream; +#undef MAYBE_DUP + return (int)n; +} + +static void +mux_remove_remote_forwardings(struct ssh *ssh, Channel *c) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->local_perms; + struct permission *perm; + int r; + u_int i; + + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (perm->downstream != c) + continue; + + /* cancel on the server, since mux client is gone */ + debug("channel %d: cleanup remote forward for %s:%u", + c->self, perm->listen_host, perm->listen_port); + if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || + (r = sshpkt_put_cstring(ssh, + "cancel-tcpip-forward")) != 0 || + (r = sshpkt_put_u8(ssh, 0)) != 0 || + (r = sshpkt_put_cstring(ssh, + channel_rfwd_bind_host(perm->listen_host))) != 0 || + (r = sshpkt_put_u32(ssh, perm->listen_port)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + fatal("%s: channel %i: %s", __func__, + c->self, ssh_err(r)); + } + fwd_perm_clear(perm); /* unregister */ + } +} + +/* Free the channel and close its fd/socket. */ +void +channel_free(struct ssh *ssh, Channel *c) +{ + struct ssh_channels *sc = ssh->chanctxt; + char *s; + u_int i, n; + Channel *other; + struct channel_confirm *cc; + + for (n = 0, i = 0; i < sc->channels_alloc; i++) { + if ((other = sc->channels[i]) == NULL) + continue; + n++; + /* detach from mux client and prepare for closing */ + if (c->type == SSH_CHANNEL_MUX_CLIENT && + other->type == SSH_CHANNEL_MUX_PROXY && + other->mux_ctx == c) { + other->mux_ctx = NULL; + other->type = SSH_CHANNEL_OPEN; + other->istate = CHAN_INPUT_CLOSED; + other->ostate = CHAN_OUTPUT_CLOSED; + } + } + debug("channel %d: free: %s, nchannels %u", c->self, + c->remote_name ? c->remote_name : "???", n); + + if (c->type == SSH_CHANNEL_MUX_CLIENT) + mux_remove_remote_forwardings(ssh, c); + + if (log_level_get() >= SYSLOG_LEVEL_DEBUG3) { + s = channel_open_message(ssh); + debug3("channel %d: status: %s", c->self, s); + free(s); + } + + channel_close_fds(ssh, c); + sshbuf_free(c->input); + sshbuf_free(c->output); + sshbuf_free(c->extended); + c->input = c->output = c->extended = NULL; + free(c->remote_name); + c->remote_name = NULL; + free(c->path); + c->path = NULL; + free(c->listening_addr); + c->listening_addr = NULL; + while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) { + if (cc->abandon_cb != NULL) + cc->abandon_cb(ssh, c, cc->ctx); + TAILQ_REMOVE(&c->status_confirms, cc, entry); + explicit_bzero(cc, sizeof(*cc)); + free(cc); + } + if (c->filter_cleanup != NULL && c->filter_ctx != NULL) + c->filter_cleanup(ssh, c->self, c->filter_ctx); + sc->channels[c->self] = NULL; + explicit_bzero(c, sizeof(*c)); + free(c); +} + +void +channel_free_all(struct ssh *ssh) +{ + u_int i; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) + if (ssh->chanctxt->channels[i] != NULL) + channel_free(ssh, ssh->chanctxt->channels[i]); +} + +/* + * Closes the sockets/fds of all channels. This is used to close extra file + * descriptors after a fork. + */ +void +channel_close_all(struct ssh *ssh) +{ + u_int i; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) + if (ssh->chanctxt->channels[i] != NULL) + channel_close_fds(ssh, ssh->chanctxt->channels[i]); +} + +/* + * Stop listening to channels. + */ +void +channel_stop_listening(struct ssh *ssh) +{ + u_int i; + Channel *c; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + c = ssh->chanctxt->channels[i]; + if (c != NULL) { + switch (c->type) { + case SSH_CHANNEL_AUTH_SOCKET: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_RPORT_LISTENER: + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_UNIX_LISTENER: + case SSH_CHANNEL_RUNIX_LISTENER: + channel_close_fd(ssh, &c->sock); + channel_free(ssh, c); + break; + } + } + } +} + +/* + * Returns true if no channel has too much buffered data, and false if one or + * more channel is overfull. + */ +int +channel_not_very_much_buffered_data(struct ssh *ssh) +{ + u_int i; + u_int maxsize = ssh_packet_get_maxsize(ssh); + Channel *c; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + c = ssh->chanctxt->channels[i]; + if (c == NULL || c->type != SSH_CHANNEL_OPEN) + continue; + if (sshbuf_len(c->output) > maxsize) { + debug2("channel %d: big output buffer %zu > %u", + c->self, sshbuf_len(c->output), maxsize); + return 0; + } + } + return 1; +} + +/* Returns true if any channel is still open. */ +int +channel_still_open(struct ssh *ssh) +{ + u_int i; + Channel *c; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + c = ssh->chanctxt->channels[i]; + if (c == NULL) + continue; + switch (c->type) { + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_RPORT_LISTENER: + case SSH_CHANNEL_MUX_LISTENER: + case SSH_CHANNEL_CLOSED: + case SSH_CHANNEL_AUTH_SOCKET: + case SSH_CHANNEL_DYNAMIC: + case SSH_CHANNEL_RDYNAMIC_OPEN: + case SSH_CHANNEL_CONNECTING: + case SSH_CHANNEL_ZOMBIE: + case SSH_CHANNEL_ABANDONED: + case SSH_CHANNEL_UNIX_LISTENER: + case SSH_CHANNEL_RUNIX_LISTENER: + continue; + case SSH_CHANNEL_LARVAL: + continue; + case SSH_CHANNEL_OPENING: + case SSH_CHANNEL_OPEN: + case SSH_CHANNEL_RDYNAMIC_FINISH: + case SSH_CHANNEL_X11_OPEN: + case SSH_CHANNEL_MUX_CLIENT: + case SSH_CHANNEL_MUX_PROXY: + return 1; + default: + fatal("%s: bad channel type %d", __func__, c->type); + /* NOTREACHED */ + } + } + return 0; +} + +/* Returns the id of an open channel suitable for keepaliving */ +int +channel_find_open(struct ssh *ssh) +{ + u_int i; + Channel *c; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + c = ssh->chanctxt->channels[i]; + if (c == NULL || !c->have_remote_id) + continue; + switch (c->type) { + case SSH_CHANNEL_CLOSED: + case SSH_CHANNEL_DYNAMIC: + case SSH_CHANNEL_RDYNAMIC_OPEN: + case SSH_CHANNEL_RDYNAMIC_FINISH: + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_RPORT_LISTENER: + case SSH_CHANNEL_MUX_LISTENER: + case SSH_CHANNEL_MUX_CLIENT: + case SSH_CHANNEL_MUX_PROXY: + case SSH_CHANNEL_OPENING: + case SSH_CHANNEL_CONNECTING: + case SSH_CHANNEL_ZOMBIE: + case SSH_CHANNEL_ABANDONED: + case SSH_CHANNEL_UNIX_LISTENER: + case SSH_CHANNEL_RUNIX_LISTENER: + continue; + case SSH_CHANNEL_LARVAL: + case SSH_CHANNEL_AUTH_SOCKET: + case SSH_CHANNEL_OPEN: + case SSH_CHANNEL_X11_OPEN: + return i; + default: + fatal("%s: bad channel type %d", __func__, c->type); + /* NOTREACHED */ + } + } + return -1; +} + +/* Returns the state of the channel's extended usage flag */ +const char * +channel_format_extended_usage(const Channel *c) +{ + if (c->efd == -1) + return "closed"; + + switch (c->extended_usage) { + case CHAN_EXTENDED_WRITE: + return "write"; + case CHAN_EXTENDED_READ: + return "read"; + case CHAN_EXTENDED_IGNORE: + return "ignore"; + default: + return "UNKNOWN"; + } +} + +static char * +channel_format_status(const Channel *c) +{ + char *ret = NULL; + + xasprintf(&ret, "t%d %s%u i%u/%zu o%u/%zu e[%s]/%zu " + "fd %d/%d/%d sock %d cc %d", + c->type, + c->have_remote_id ? "r" : "nr", c->remote_id, + c->istate, sshbuf_len(c->input), + c->ostate, sshbuf_len(c->output), + channel_format_extended_usage(c), sshbuf_len(c->extended), + c->rfd, c->wfd, c->efd, c->sock, c->ctl_chan); + return ret; +} + +/* + * Returns a message describing the currently open forwarded connections, + * suitable for sending to the client. The message contains crlf pairs for + * newlines. + */ +char * +channel_open_message(struct ssh *ssh) +{ + struct sshbuf *buf; + Channel *c; + u_int i; + int r; + char *cp, *ret; + + if ((buf = sshbuf_new()) == NULL) + fatal("%s: sshbuf_new", __func__); + if ((r = sshbuf_putf(buf, + "The following connections are open:\r\n")) != 0) + fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + c = ssh->chanctxt->channels[i]; + if (c == NULL) + continue; + switch (c->type) { + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_RPORT_LISTENER: + case SSH_CHANNEL_CLOSED: + case SSH_CHANNEL_AUTH_SOCKET: + case SSH_CHANNEL_ZOMBIE: + case SSH_CHANNEL_ABANDONED: + case SSH_CHANNEL_MUX_LISTENER: + case SSH_CHANNEL_UNIX_LISTENER: + case SSH_CHANNEL_RUNIX_LISTENER: + continue; + case SSH_CHANNEL_LARVAL: + case SSH_CHANNEL_OPENING: + case SSH_CHANNEL_CONNECTING: + case SSH_CHANNEL_DYNAMIC: + case SSH_CHANNEL_RDYNAMIC_OPEN: + case SSH_CHANNEL_RDYNAMIC_FINISH: + case SSH_CHANNEL_OPEN: + case SSH_CHANNEL_X11_OPEN: + case SSH_CHANNEL_MUX_PROXY: + case SSH_CHANNEL_MUX_CLIENT: + cp = channel_format_status(c); + if ((r = sshbuf_putf(buf, " #%d %.300s (%s)\r\n", + c->self, c->remote_name, cp)) != 0) { + free(cp); + fatal("%s: sshbuf_putf: %s", + __func__, ssh_err(r)); + } + free(cp); + continue; + default: + fatal("%s: bad channel type %d", __func__, c->type); + /* NOTREACHED */ + } + } + if ((ret = sshbuf_dup_string(buf)) == NULL) + fatal("%s: sshbuf_dup_string", __func__); + sshbuf_free(buf); + return ret; +} + +static void +open_preamble(struct ssh *ssh, const char *where, Channel *c, const char *type) +{ + int r; + + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 || + (r = sshpkt_put_cstring(ssh, type)) != 0 || + (r = sshpkt_put_u32(ssh, c->self)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0) { + fatal("%s: channel %i: open: %s", where, c->self, ssh_err(r)); + } +} + +void +channel_send_open(struct ssh *ssh, int id) +{ + Channel *c = channel_lookup(ssh, id); + int r; + + if (c == NULL) { + logit("channel_send_open: %d: bad id", id); + return; + } + debug2("channel %d: send open", id); + open_preamble(ssh, __func__, c, c->ctype); + if ((r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r)); +} + +void +channel_request_start(struct ssh *ssh, int id, char *service, int wantconfirm) +{ + Channel *c = channel_lookup(ssh, id); + int r; + + if (c == NULL) { + logit("%s: %d: unknown channel id", __func__, id); + return; + } + if (!c->have_remote_id) + fatal(":%s: channel %d: no remote id", __func__, c->self); + + debug2("channel %d: request %s confirm %d", id, service, wantconfirm); + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_cstring(ssh, service)) != 0 || + (r = sshpkt_put_u8(ssh, wantconfirm)) != 0) { + fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r)); + } +} + +void +channel_register_status_confirm(struct ssh *ssh, int id, + channel_confirm_cb *cb, channel_confirm_abandon_cb *abandon_cb, void *ctx) +{ + struct channel_confirm *cc; + Channel *c; + + if ((c = channel_lookup(ssh, id)) == NULL) + fatal("%s: %d: bad id", __func__, id); + + cc = xcalloc(1, sizeof(*cc)); + cc->cb = cb; + cc->abandon_cb = abandon_cb; + cc->ctx = ctx; + TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry); +} + +void +channel_register_open_confirm(struct ssh *ssh, int id, + channel_open_fn *fn, void *ctx) +{ + Channel *c = channel_lookup(ssh, id); + + if (c == NULL) { + logit("%s: %d: bad id", __func__, id); + return; + } + c->open_confirm = fn; + c->open_confirm_ctx = ctx; +} + +void +channel_register_cleanup(struct ssh *ssh, int id, + channel_callback_fn *fn, int do_close) +{ + Channel *c = channel_by_id(ssh, id); + + if (c == NULL) { + logit("%s: %d: bad id", __func__, id); + return; + } + c->detach_user = fn; + c->detach_close = do_close; +} + +void +channel_cancel_cleanup(struct ssh *ssh, int id) +{ + Channel *c = channel_by_id(ssh, id); + + if (c == NULL) { + logit("%s: %d: bad id", __func__, id); + return; + } + c->detach_user = NULL; + c->detach_close = 0; +} + +void +channel_register_filter(struct ssh *ssh, int id, channel_infilter_fn *ifn, + channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx) +{ + Channel *c = channel_lookup(ssh, id); + + if (c == NULL) { + logit("%s: %d: bad id", __func__, id); + return; + } + c->input_filter = ifn; + c->output_filter = ofn; + c->filter_ctx = ctx; + c->filter_cleanup = cfn; +} + +void +channel_set_fds(struct ssh *ssh, int id, int rfd, int wfd, int efd, + int extusage, int nonblock, int is_tty, u_int window_max) +{ + Channel *c = channel_lookup(ssh, id); + int r; + + if (c == NULL || c->type != SSH_CHANNEL_LARVAL) + fatal("channel_activate for non-larval channel %d.", id); + if (!c->have_remote_id) + fatal(":%s: channel %d: no remote id", __func__, c->self); + + channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, is_tty); + c->type = SSH_CHANNEL_OPEN; + c->local_window = c->local_window_max = window_max; + + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r)); +} + +static void +channel_pre_listener(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + FD_SET(c->sock, readset); +} + +static void +channel_pre_connecting(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + debug3("channel %d: waiting for connection", c->self); + FD_SET(c->sock, writeset); +} + +static void +channel_pre_open(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + if (c->istate == CHAN_INPUT_OPEN && + c->remote_window > 0 && + sshbuf_len(c->input) < c->remote_window && + sshbuf_check_reserve(c->input, CHAN_RBUF) == 0) + FD_SET(c->rfd, readset); + if (c->ostate == CHAN_OUTPUT_OPEN || + c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { + if (sshbuf_len(c->output) > 0) { + FD_SET(c->wfd, writeset); + } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { + if (CHANNEL_EFD_OUTPUT_ACTIVE(c)) + debug2("channel %d: " + "obuf_empty delayed efd %d/(%zu)", c->self, + c->efd, sshbuf_len(c->extended)); + else + chan_obuf_empty(ssh, c); + } + } + /** XXX check close conditions, too */ + if (c->efd != -1 && !(c->istate == CHAN_INPUT_CLOSED && + c->ostate == CHAN_OUTPUT_CLOSED)) { + if (c->extended_usage == CHAN_EXTENDED_WRITE && + sshbuf_len(c->extended) > 0) + FD_SET(c->efd, writeset); + else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) && + (c->extended_usage == CHAN_EXTENDED_READ || + c->extended_usage == CHAN_EXTENDED_IGNORE) && + sshbuf_len(c->extended) < c->remote_window) + FD_SET(c->efd, readset); + } + /* XXX: What about efd? races? */ +} + +/* + * This is a special state for X11 authentication spoofing. An opened X11 + * connection (when authentication spoofing is being done) remains in this + * state until the first packet has been completely read. The authentication + * data in that packet is then substituted by the real data if it matches the + * fake data, and the channel is put into normal mode. + * XXX All this happens at the client side. + * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok + */ +static int +x11_open_helper(struct ssh *ssh, struct sshbuf *b) +{ + struct ssh_channels *sc = ssh->chanctxt; + u_char *ucp; + u_int proto_len, data_len; + + /* Is this being called after the refusal deadline? */ + if (sc->x11_refuse_time != 0 && + (u_int)monotime() >= sc->x11_refuse_time) { + verbose("Rejected X11 connection after ForwardX11Timeout " + "expired"); + return -1; + } + + /* Check if the fixed size part of the packet is in buffer. */ + if (sshbuf_len(b) < 12) + return 0; + + /* Parse the lengths of variable-length fields. */ + ucp = sshbuf_mutable_ptr(b); + if (ucp[0] == 0x42) { /* Byte order MSB first. */ + proto_len = 256 * ucp[6] + ucp[7]; + data_len = 256 * ucp[8] + ucp[9]; + } else if (ucp[0] == 0x6c) { /* Byte order LSB first. */ + proto_len = ucp[6] + 256 * ucp[7]; + data_len = ucp[8] + 256 * ucp[9]; + } else { + debug2("Initial X11 packet contains bad byte order byte: 0x%x", + ucp[0]); + return -1; + } + + /* Check if the whole packet is in buffer. */ + if (sshbuf_len(b) < + 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3)) + return 0; + + /* Check if authentication protocol matches. */ + if (proto_len != strlen(sc->x11_saved_proto) || + memcmp(ucp + 12, sc->x11_saved_proto, proto_len) != 0) { + debug2("X11 connection uses different authentication protocol."); + return -1; + } + /* Check if authentication data matches our fake data. */ + if (data_len != sc->x11_fake_data_len || + timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3), + sc->x11_fake_data, sc->x11_fake_data_len) != 0) { + debug2("X11 auth data does not match fake data."); + return -1; + } + /* Check fake data length */ + if (sc->x11_fake_data_len != sc->x11_saved_data_len) { + error("X11 fake_data_len %d != saved_data_len %d", + sc->x11_fake_data_len, sc->x11_saved_data_len); + return -1; + } + /* + * Received authentication protocol and data match + * our fake data. Substitute the fake data with real + * data. + */ + memcpy(ucp + 12 + ((proto_len + 3) & ~3), + sc->x11_saved_data, sc->x11_saved_data_len); + return 1; +} + +static void +channel_pre_x11_open(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + int ret = x11_open_helper(ssh, c->output); + + /* c->force_drain = 1; */ + + if (ret == 1) { + c->type = SSH_CHANNEL_OPEN; + channel_pre_open(ssh, c, readset, writeset); + } else if (ret == -1) { + logit("X11 connection rejected because of wrong authentication."); + debug2("X11 rejected %d i%d/o%d", + c->self, c->istate, c->ostate); + chan_read_failed(ssh, c); + sshbuf_reset(c->input); + chan_ibuf_empty(ssh, c); + sshbuf_reset(c->output); + chan_write_failed(ssh, c); + debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate); + } +} + +static void +channel_pre_mux_client(struct ssh *ssh, + Channel *c, fd_set *readset, fd_set *writeset) +{ + if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause && + sshbuf_check_reserve(c->input, CHAN_RBUF) == 0) + FD_SET(c->rfd, readset); + if (c->istate == CHAN_INPUT_WAIT_DRAIN) { + /* clear buffer immediately (discard any partial packet) */ + sshbuf_reset(c->input); + chan_ibuf_empty(ssh, c); + /* Start output drain. XXX just kill chan? */ + chan_rcvd_oclose(ssh, c); + } + if (c->ostate == CHAN_OUTPUT_OPEN || + c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { + if (sshbuf_len(c->output) > 0) + FD_SET(c->wfd, writeset); + else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) + chan_obuf_empty(ssh, c); + } +} + +/* try to decode a socks4 header */ +static int +channel_decode_socks4(Channel *c, struct sshbuf *input, struct sshbuf *output) +{ + const u_char *p; + char *host; + u_int len, have, i, found, need; + char username[256]; + struct { + u_int8_t version; + u_int8_t command; + u_int16_t dest_port; + struct in_addr dest_addr; + } s4_req, s4_rsp; + int r; + + debug2("channel %d: decode socks4", c->self); + + have = sshbuf_len(input); + len = sizeof(s4_req); + if (have < len) + return 0; + p = sshbuf_ptr(input); + + need = 1; + /* SOCKS4A uses an invalid IP address 0.0.0.x */ + if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) { + debug2("channel %d: socks4a request", c->self); + /* ... and needs an extra string (the hostname) */ + need = 2; + } + /* Check for terminating NUL on the string(s) */ + for (found = 0, i = len; i < have; i++) { + if (p[i] == '\0') { + found++; + if (found == need) + break; + } + if (i > 1024) { + /* the peer is probably sending garbage */ + debug("channel %d: decode socks4: too long", + c->self); + return -1; + } + } + if (found < need) + return 0; + if ((r = sshbuf_get(input, &s4_req.version, 1)) != 0 || + (r = sshbuf_get(input, &s4_req.command, 1)) != 0 || + (r = sshbuf_get(input, &s4_req.dest_port, 2)) != 0 || + (r = sshbuf_get(input, &s4_req.dest_addr, 4)) != 0) { + debug("channels %d: decode socks4: %s", c->self, ssh_err(r)); + return -1; + } + have = sshbuf_len(input); + p = sshbuf_ptr(input); + if (memchr(p, '\0', have) == NULL) { + error("channel %d: decode socks4: user not nul terminated", + c->self); + return -1; + } + len = strlen(p); + debug2("channel %d: decode socks4: user %s/%d", c->self, p, len); + len++; /* trailing '\0' */ + strlcpy(username, p, sizeof(username)); + if ((r = sshbuf_consume(input, len)) != 0) { + fatal("%s: channel %d: consume: %s", __func__, + c->self, ssh_err(r)); + } + free(c->path); + c->path = NULL; + if (need == 1) { /* SOCKS4: one string */ + host = inet_ntoa(s4_req.dest_addr); + c->path = xstrdup(host); + } else { /* SOCKS4A: two strings */ + have = sshbuf_len(input); + p = sshbuf_ptr(input); + if (memchr(p, '\0', have) == NULL) { + error("channel %d: decode socks4a: host not nul " + "terminated", c->self); + return -1; + } + len = strlen(p); + debug2("channel %d: decode socks4a: host %s/%d", + c->self, p, len); + len++; /* trailing '\0' */ + if (len > NI_MAXHOST) { + error("channel %d: hostname \"%.100s\" too long", + c->self, p); + return -1; + } + c->path = xstrdup(p); + if ((r = sshbuf_consume(input, len)) != 0) { + fatal("%s: channel %d: consume: %s", __func__, + c->self, ssh_err(r)); + } + } + c->host_port = ntohs(s4_req.dest_port); + + debug2("channel %d: dynamic request: socks4 host %s port %u command %u", + c->self, c->path, c->host_port, s4_req.command); + + if (s4_req.command != 1) { + debug("channel %d: cannot handle: %s cn %d", + c->self, need == 1 ? "SOCKS4" : "SOCKS4A", s4_req.command); + return -1; + } + s4_rsp.version = 0; /* vn: 0 for reply */ + s4_rsp.command = 90; /* cd: req granted */ + s4_rsp.dest_port = 0; /* ignored */ + s4_rsp.dest_addr.s_addr = INADDR_ANY; /* ignored */ + if ((r = sshbuf_put(output, &s4_rsp, sizeof(s4_rsp))) != 0) { + fatal("%s: channel %d: append reply: %s", __func__, + c->self, ssh_err(r)); + } + return 1; +} + +/* try to decode a socks5 header */ +#define SSH_SOCKS5_AUTHDONE 0x1000 +#define SSH_SOCKS5_NOAUTH 0x00 +#define SSH_SOCKS5_IPV4 0x01 +#define SSH_SOCKS5_DOMAIN 0x03 +#define SSH_SOCKS5_IPV6 0x04 +#define SSH_SOCKS5_CONNECT 0x01 +#define SSH_SOCKS5_SUCCESS 0x00 + +static int +channel_decode_socks5(Channel *c, struct sshbuf *input, struct sshbuf *output) +{ + /* XXX use get/put_u8 instead of trusting struct padding */ + struct { + u_int8_t version; + u_int8_t command; + u_int8_t reserved; + u_int8_t atyp; + } s5_req, s5_rsp; + u_int16_t dest_port; + char dest_addr[255+1], ntop[INET6_ADDRSTRLEN]; + const u_char *p; + u_int have, need, i, found, nmethods, addrlen, af; + int r; + + debug2("channel %d: decode socks5", c->self); + p = sshbuf_ptr(input); + if (p[0] != 0x05) + return -1; + have = sshbuf_len(input); + if (!(c->flags & SSH_SOCKS5_AUTHDONE)) { + /* format: ver | nmethods | methods */ + if (have < 2) + return 0; + nmethods = p[1]; + if (have < nmethods + 2) + return 0; + /* look for method: "NO AUTHENTICATION REQUIRED" */ + for (found = 0, i = 2; i < nmethods + 2; i++) { + if (p[i] == SSH_SOCKS5_NOAUTH) { + found = 1; + break; + } + } + if (!found) { + debug("channel %d: method SSH_SOCKS5_NOAUTH not found", + c->self); + return -1; + } + if ((r = sshbuf_consume(input, nmethods + 2)) != 0) { + fatal("%s: channel %d: consume: %s", __func__, + c->self, ssh_err(r)); + } + /* version, method */ + if ((r = sshbuf_put_u8(output, 0x05)) != 0 || + (r = sshbuf_put_u8(output, SSH_SOCKS5_NOAUTH)) != 0) { + fatal("%s: channel %d: append reply: %s", __func__, + c->self, ssh_err(r)); + } + c->flags |= SSH_SOCKS5_AUTHDONE; + debug2("channel %d: socks5 auth done", c->self); + return 0; /* need more */ + } + debug2("channel %d: socks5 post auth", c->self); + if (have < sizeof(s5_req)+1) + return 0; /* need more */ + memcpy(&s5_req, p, sizeof(s5_req)); + if (s5_req.version != 0x05 || + s5_req.command != SSH_SOCKS5_CONNECT || + s5_req.reserved != 0x00) { + debug2("channel %d: only socks5 connect supported", c->self); + return -1; + } + switch (s5_req.atyp){ + case SSH_SOCKS5_IPV4: + addrlen = 4; + af = AF_INET; + break; + case SSH_SOCKS5_DOMAIN: + addrlen = p[sizeof(s5_req)]; + af = -1; + break; + case SSH_SOCKS5_IPV6: + addrlen = 16; + af = AF_INET6; + break; + default: + debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp); + return -1; + } + need = sizeof(s5_req) + addrlen + 2; + if (s5_req.atyp == SSH_SOCKS5_DOMAIN) + need++; + if (have < need) + return 0; + if ((r = sshbuf_consume(input, sizeof(s5_req))) != 0) { + fatal("%s: channel %d: consume: %s", __func__, + c->self, ssh_err(r)); + } + if (s5_req.atyp == SSH_SOCKS5_DOMAIN) { + /* host string length */ + if ((r = sshbuf_consume(input, 1)) != 0) { + fatal("%s: channel %d: consume: %s", __func__, + c->self, ssh_err(r)); + } + } + if ((r = sshbuf_get(input, &dest_addr, addrlen)) != 0 || + (r = sshbuf_get(input, &dest_port, 2)) != 0) { + debug("channel %d: parse addr/port: %s", c->self, ssh_err(r)); + return -1; + } + dest_addr[addrlen] = '\0'; + free(c->path); + c->path = NULL; + if (s5_req.atyp == SSH_SOCKS5_DOMAIN) { + if (addrlen >= NI_MAXHOST) { + error("channel %d: dynamic request: socks5 hostname " + "\"%.100s\" too long", c->self, dest_addr); + return -1; + } + c->path = xstrdup(dest_addr); + } else { + if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL) + return -1; + c->path = xstrdup(ntop); + } + c->host_port = ntohs(dest_port); + + debug2("channel %d: dynamic request: socks5 host %s port %u command %u", + c->self, c->path, c->host_port, s5_req.command); + + s5_rsp.version = 0x05; + s5_rsp.command = SSH_SOCKS5_SUCCESS; + s5_rsp.reserved = 0; /* ignored */ + s5_rsp.atyp = SSH_SOCKS5_IPV4; + dest_port = 0; /* ignored */ + + if ((r = sshbuf_put(output, &s5_rsp, sizeof(s5_rsp))) != 0 || + (r = sshbuf_put_u32(output, ntohl(INADDR_ANY))) != 0 || + (r = sshbuf_put(output, &dest_port, sizeof(dest_port))) != 0) + fatal("%s: channel %d: append reply: %s", __func__, + c->self, ssh_err(r)); + return 1; +} + +Channel * +channel_connect_stdio_fwd(struct ssh *ssh, + const char *host_to_connect, u_short port_to_connect, int in, int out) +{ + Channel *c; + + debug("%s %s:%d", __func__, host_to_connect, port_to_connect); + + c = channel_new(ssh, "stdio-forward", SSH_CHANNEL_OPENING, in, out, + -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, + 0, "stdio-forward", /*nonblock*/0); + + c->path = xstrdup(host_to_connect); + c->host_port = port_to_connect; + c->listening_port = 0; + c->force_drain = 1; + + channel_register_fds(ssh, c, in, out, -1, 0, 1, 0); + port_open_helper(ssh, c, "direct-tcpip"); + + return c; +} + +/* dynamic port forwarding */ +static void +channel_pre_dynamic(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + const u_char *p; + u_int have; + int ret; + + have = sshbuf_len(c->input); + debug2("channel %d: pre_dynamic: have %d", c->self, have); + /* sshbuf_dump(c->input, stderr); */ + /* check if the fixed size part of the packet is in buffer. */ + if (have < 3) { + /* need more */ + FD_SET(c->sock, readset); + return; + } + /* try to guess the protocol */ + p = sshbuf_ptr(c->input); + /* XXX sshbuf_peek_u8? */ + switch (p[0]) { + case 0x04: + ret = channel_decode_socks4(c, c->input, c->output); + break; + case 0x05: + ret = channel_decode_socks5(c, c->input, c->output); + break; + default: + ret = -1; + break; + } + if (ret < 0) { + chan_mark_dead(ssh, c); + } else if (ret == 0) { + debug2("channel %d: pre_dynamic: need more", c->self); + /* need more */ + FD_SET(c->sock, readset); + if (sshbuf_len(c->output)) + FD_SET(c->sock, writeset); + } else { + /* switch to the next state */ + c->type = SSH_CHANNEL_OPENING; + port_open_helper(ssh, c, "direct-tcpip"); + } +} + +/* simulate read-error */ +static void +rdynamic_close(struct ssh *ssh, Channel *c) +{ + c->type = SSH_CHANNEL_OPEN; + chan_read_failed(ssh, c); + sshbuf_reset(c->input); + chan_ibuf_empty(ssh, c); + sshbuf_reset(c->output); + chan_write_failed(ssh, c); +} + +/* reverse dynamic port forwarding */ +static void +channel_before_prepare_select_rdynamic(struct ssh *ssh, Channel *c) +{ + const u_char *p; + u_int have, len; + int r, ret; + + have = sshbuf_len(c->output); + debug2("channel %d: pre_rdynamic: have %d", c->self, have); + /* sshbuf_dump(c->output, stderr); */ + /* EOF received */ + if (c->flags & CHAN_EOF_RCVD) { + if ((r = sshbuf_consume(c->output, have)) != 0) { + fatal("%s: channel %d: consume: %s", + __func__, c->self, ssh_err(r)); + } + rdynamic_close(ssh, c); + return; + } + /* check if the fixed size part of the packet is in buffer. */ + if (have < 3) + return; + /* try to guess the protocol */ + p = sshbuf_ptr(c->output); + switch (p[0]) { + case 0x04: + /* switch input/output for reverse forwarding */ + ret = channel_decode_socks4(c, c->output, c->input); + break; + case 0x05: + ret = channel_decode_socks5(c, c->output, c->input); + break; + default: + ret = -1; + break; + } + if (ret < 0) { + rdynamic_close(ssh, c); + } else if (ret == 0) { + debug2("channel %d: pre_rdynamic: need more", c->self); + /* send socks request to peer */ + len = sshbuf_len(c->input); + if (len > 0 && len < c->remote_window) { + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_stringb(ssh, c->input)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + fatal("%s: channel %i: rdynamic: %s", __func__, + c->self, ssh_err(r)); + } + if ((r = sshbuf_consume(c->input, len)) != 0) { + fatal("%s: channel %d: consume: %s", + __func__, c->self, ssh_err(r)); + } + c->remote_window -= len; + } + } else if (rdynamic_connect_finish(ssh, c) < 0) { + /* the connect failed */ + rdynamic_close(ssh, c); + } +} + +/* This is our fake X11 server socket. */ +static void +channel_post_x11_listener(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + Channel *nc; + struct sockaddr_storage addr; + int r, newsock, oerrno, remote_port; + socklen_t addrlen; + char buf[16384], *remote_ipaddr; + + if (!FD_ISSET(c->sock, readset)) + return; + + debug("X11 connection requested."); + addrlen = sizeof(addr); + newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen); + if (c->single_connection) { + oerrno = errno; + debug2("single_connection: closing X11 listener."); + channel_close_fd(ssh, &c->sock); + chan_mark_dead(ssh, c); + errno = oerrno; + } + if (newsock < 0) { + if (errno != EINTR && errno != EWOULDBLOCK && + errno != ECONNABORTED) + error("accept: %.100s", strerror(errno)); + if (errno == EMFILE || errno == ENFILE) + c->notbefore = monotime() + 1; + return; + } + set_nodelay(newsock); + remote_ipaddr = get_peer_ipaddr(newsock); + remote_port = get_peer_port(newsock); + snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", + remote_ipaddr, remote_port); + + nc = channel_new(ssh, "accepted x11 socket", + SSH_CHANNEL_OPENING, newsock, newsock, -1, + c->local_window_max, c->local_maxpacket, 0, buf, 1); + open_preamble(ssh, __func__, nc, "x11"); + if ((r = sshpkt_put_cstring(ssh, remote_ipaddr)) != 0 || + (r = sshpkt_put_u32(ssh, remote_port)) != 0) { + fatal("%s: channel %i: reply %s", __func__, + c->self, ssh_err(r)); + } + if ((r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r)); + free(remote_ipaddr); +} + +static void +port_open_helper(struct ssh *ssh, Channel *c, char *rtype) +{ + char *local_ipaddr = get_local_ipaddr(c->sock); + int local_port = c->sock == -1 ? 65536 : get_local_port(c->sock); + char *remote_ipaddr = get_peer_ipaddr(c->sock); + int remote_port = get_peer_port(c->sock); + int r; + + if (remote_port == -1) { + /* Fake addr/port to appease peers that validate it (Tectia) */ + free(remote_ipaddr); + remote_ipaddr = xstrdup("127.0.0.1"); + remote_port = 65535; + } + + free(c->remote_name); + xasprintf(&c->remote_name, + "%s: listening port %d for %.100s port %d, " + "connect from %.200s port %d to %.100s port %d", + rtype, c->listening_port, c->path, c->host_port, + remote_ipaddr, remote_port, local_ipaddr, local_port); + + open_preamble(ssh, __func__, c, rtype); + if (strcmp(rtype, "direct-tcpip") == 0) { + /* target host, port */ + if ((r = sshpkt_put_cstring(ssh, c->path)) != 0 || + (r = sshpkt_put_u32(ssh, c->host_port)) != 0) { + fatal("%s: channel %i: reply %s", __func__, + c->self, ssh_err(r)); + } + } else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) { + /* target path */ + if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) { + fatal("%s: channel %i: reply %s", __func__, + c->self, ssh_err(r)); + } + } else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) { + /* listen path */ + if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) { + fatal("%s: channel %i: reply %s", __func__, + c->self, ssh_err(r)); + } + } else { + /* listen address, port */ + if ((r = sshpkt_put_cstring(ssh, c->path)) != 0 || + (r = sshpkt_put_u32(ssh, local_port)) != 0) { + fatal("%s: channel %i: reply %s", __func__, + c->self, ssh_err(r)); + } + } + if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) { + /* reserved for future owner/mode info */ + if ((r = sshpkt_put_cstring(ssh, "")) != 0) { + fatal("%s: channel %i: reply %s", __func__, + c->self, ssh_err(r)); + } + } else { + /* originator host and port */ + if ((r = sshpkt_put_cstring(ssh, remote_ipaddr)) != 0 || + (r = sshpkt_put_u32(ssh, (u_int)remote_port)) != 0) { + fatal("%s: channel %i: reply %s", __func__, + c->self, ssh_err(r)); + } + } + if ((r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r)); + free(remote_ipaddr); + free(local_ipaddr); +} + +void +channel_set_x11_refuse_time(struct ssh *ssh, u_int refuse_time) +{ + ssh->chanctxt->x11_refuse_time = refuse_time; +} + +/* + * This socket is listening for connections to a forwarded TCP/IP port. + */ +static void +channel_post_port_listener(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + Channel *nc; + struct sockaddr_storage addr; + int newsock, nextstate; + socklen_t addrlen; + char *rtype; + + if (!FD_ISSET(c->sock, readset)) + return; + + debug("Connection to port %d forwarding to %.100s port %d requested.", + c->listening_port, c->path, c->host_port); + + if (c->type == SSH_CHANNEL_RPORT_LISTENER) { + nextstate = SSH_CHANNEL_OPENING; + rtype = "forwarded-tcpip"; + } else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) { + nextstate = SSH_CHANNEL_OPENING; + rtype = "forwarded-streamlocal@openssh.com"; + } else if (c->host_port == PORT_STREAMLOCAL) { + nextstate = SSH_CHANNEL_OPENING; + rtype = "direct-streamlocal@openssh.com"; + } else if (c->host_port == 0) { + nextstate = SSH_CHANNEL_DYNAMIC; + rtype = "dynamic-tcpip"; + } else { + nextstate = SSH_CHANNEL_OPENING; + rtype = "direct-tcpip"; + } + + addrlen = sizeof(addr); + newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen); + if (newsock < 0) { + if (errno != EINTR && errno != EWOULDBLOCK && + errno != ECONNABORTED) + error("accept: %.100s", strerror(errno)); + if (errno == EMFILE || errno == ENFILE) + c->notbefore = monotime() + 1; + return; + } + if (c->host_port != PORT_STREAMLOCAL) + set_nodelay(newsock); + nc = channel_new(ssh, rtype, nextstate, newsock, newsock, -1, + c->local_window_max, c->local_maxpacket, 0, rtype, 1); + nc->listening_port = c->listening_port; + nc->host_port = c->host_port; + if (c->path != NULL) + nc->path = xstrdup(c->path); + + if (nextstate != SSH_CHANNEL_DYNAMIC) + port_open_helper(ssh, nc, rtype); +} + +/* + * This is the authentication agent socket listening for connections from + * clients. + */ +static void +channel_post_auth_listener(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + Channel *nc; + int r, newsock; + struct sockaddr_storage addr; + socklen_t addrlen; + + if (!FD_ISSET(c->sock, readset)) + return; + + addrlen = sizeof(addr); + newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen); + if (newsock < 0) { + error("accept from auth socket: %.100s", strerror(errno)); + if (errno == EMFILE || errno == ENFILE) + c->notbefore = monotime() + 1; + return; + } + nc = channel_new(ssh, "accepted auth socket", + SSH_CHANNEL_OPENING, newsock, newsock, -1, + c->local_window_max, c->local_maxpacket, + 0, "accepted auth socket", 1); + open_preamble(ssh, __func__, nc, "auth-agent@openssh.com"); + if ((r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r)); +} + +static void +channel_post_connecting(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + int err = 0, sock, isopen, r; + socklen_t sz = sizeof(err); + + if (!FD_ISSET(c->sock, writeset)) + return; + if (!c->have_remote_id) + fatal(":%s: channel %d: no remote id", __func__, c->self); + /* for rdynamic the OPEN_CONFIRMATION has been sent already */ + isopen = (c->type == SSH_CHANNEL_RDYNAMIC_FINISH); + if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) { + err = errno; + error("getsockopt SO_ERROR failed"); + } + if (err == 0) { + debug("channel %d: connected to %s port %d", + c->self, c->connect_ctx.host, c->connect_ctx.port); + channel_connect_ctx_free(&c->connect_ctx); + c->type = SSH_CHANNEL_OPEN; + if (isopen) { + /* no message necessary */ + } else { + if ((r = sshpkt_start(ssh, + SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_u32(ssh, c->self)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_maxpacket)) + != 0) + fatal("%s: channel %i: confirm: %s", __func__, + c->self, ssh_err(r)); + if ((r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %i: %s", __func__, c->self, + ssh_err(r)); + } + } else { + debug("channel %d: connection failed: %s", + c->self, strerror(err)); + /* Try next address, if any */ + if ((sock = connect_next(&c->connect_ctx)) > 0) { + close(c->sock); + c->sock = c->rfd = c->wfd = sock; + channel_find_maxfd(ssh->chanctxt); + return; + } + /* Exhausted all addresses */ + error("connect_to %.100s port %d: failed.", + c->connect_ctx.host, c->connect_ctx.port); + channel_connect_ctx_free(&c->connect_ctx); + if (isopen) { + rdynamic_close(ssh, c); + } else { + if ((r = sshpkt_start(ssh, + SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_u32(ssh, + SSH2_OPEN_CONNECT_FAILED)) != 0 || + (r = sshpkt_put_cstring(ssh, strerror(err))) != 0 || + (r = sshpkt_put_cstring(ssh, "")) != 0) { + fatal("%s: channel %i: failure: %s", __func__, + c->self, ssh_err(r)); + } + if ((r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %i: %s", __func__, c->self, + ssh_err(r)); + chan_mark_dead(ssh, c); + } + } +} + +static int +channel_handle_rfd(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + char buf[CHAN_RBUF]; + ssize_t len; + int r, force; + + force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED; + + if (c->rfd == -1 || (!force && !FD_ISSET(c->rfd, readset))) + return 1; + + errno = 0; + len = read(c->rfd, buf, sizeof(buf)); + if (len < 0 && (errno == EINTR || + ((errno == EAGAIN || errno == EWOULDBLOCK) && !force))) + return 1; +#ifndef PTY_ZEROREAD + if (len <= 0) { +#else + if ((!c->isatty && len <= 0) || + (c->isatty && (len < 0 || (len == 0 && errno != 0)))) { +#endif + debug2("channel %d: read<=0 rfd %d len %zd", + c->self, c->rfd, len); + if (c->type != SSH_CHANNEL_OPEN) { + debug2("channel %d: not open", c->self); + chan_mark_dead(ssh, c); + return -1; + } else { + chan_read_failed(ssh, c); + } + return -1; + } + if (c->input_filter != NULL) { + if (c->input_filter(ssh, c, buf, len) == -1) { + debug2("channel %d: filter stops", c->self); + chan_read_failed(ssh, c); + } + } else if (c->datagram) { + if ((r = sshbuf_put_string(c->input, buf, len)) != 0) + fatal("%s: channel %d: put datagram: %s", __func__, + c->self, ssh_err(r)); + } else if ((r = sshbuf_put(c->input, buf, len)) != 0) { + fatal("%s: channel %d: put data: %s", __func__, + c->self, ssh_err(r)); + } + return 1; +} + +static int +channel_handle_wfd(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + struct termios tio; + u_char *data = NULL, *buf; /* XXX const; need filter API change */ + size_t dlen, olen = 0; + int r, len; + + if (c->wfd == -1 || !FD_ISSET(c->wfd, writeset) || + sshbuf_len(c->output) == 0) + return 1; + + /* Send buffered output data to the socket. */ + olen = sshbuf_len(c->output); + if (c->output_filter != NULL) { + if ((buf = c->output_filter(ssh, c, &data, &dlen)) == NULL) { + debug2("channel %d: filter stops", c->self); + if (c->type != SSH_CHANNEL_OPEN) + chan_mark_dead(ssh, c); + else + chan_write_failed(ssh, c); + return -1; + } + } else if (c->datagram) { + if ((r = sshbuf_get_string(c->output, &data, &dlen)) != 0) + fatal("%s: channel %d: get datagram: %s", __func__, + c->self, ssh_err(r)); + buf = data; + } else { + buf = data = sshbuf_mutable_ptr(c->output); + dlen = sshbuf_len(c->output); + } + + if (c->datagram) { + /* ignore truncated writes, datagrams might get lost */ + len = write(c->wfd, buf, dlen); + free(data); + if (len < 0 && (errno == EINTR || errno == EAGAIN || + errno == EWOULDBLOCK)) + return 1; + if (len <= 0) + goto write_fail; + goto out; + } + +#ifdef _AIX + /* XXX: Later AIX versions can't push as much data to tty */ + if (c->wfd_isatty) + dlen = MIN(dlen, 8*1024); +#endif + + len = write(c->wfd, buf, dlen); + if (len < 0 && + (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) + return 1; + if (len <= 0) { + write_fail: + if (c->type != SSH_CHANNEL_OPEN) { + debug2("channel %d: not open", c->self); + chan_mark_dead(ssh, c); + return -1; + } else { + chan_write_failed(ssh, c); + } + return -1; + } +#ifndef BROKEN_TCGETATTR_ICANON + if (c->isatty && dlen >= 1 && buf[0] != '\r') { + if (tcgetattr(c->wfd, &tio) == 0 && + !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { + /* + * Simulate echo to reduce the impact of + * traffic analysis. We need to match the + * size of a SSH2_MSG_CHANNEL_DATA message + * (4 byte channel id + buf) + */ + if ((r = sshpkt_msg_ignore(ssh, 4+len)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %d: ignore: %s", + __func__, c->self, ssh_err(r)); + } + } +#endif /* BROKEN_TCGETATTR_ICANON */ + if ((r = sshbuf_consume(c->output, len)) != 0) { + fatal("%s: channel %d: consume: %s", + __func__, c->self, ssh_err(r)); + } + out: + c->local_consumed += olen - sshbuf_len(c->output); + + return 1; +} + +static int +channel_handle_efd_write(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + int r; + ssize_t len; + + if (!FD_ISSET(c->efd, writeset) || sshbuf_len(c->extended) == 0) + return 1; + + len = write(c->efd, sshbuf_ptr(c->extended), + sshbuf_len(c->extended)); + debug2("channel %d: written %zd to efd %d", c->self, len, c->efd); + if (len < 0 && (errno == EINTR || errno == EAGAIN || + errno == EWOULDBLOCK)) + return 1; + if (len <= 0) { + debug2("channel %d: closing write-efd %d", c->self, c->efd); + channel_close_fd(ssh, &c->efd); + } else { + if ((r = sshbuf_consume(c->extended, len)) != 0) { + fatal("%s: channel %d: consume: %s", + __func__, c->self, ssh_err(r)); + } + c->local_consumed += len; + } + return 1; +} + +static int +channel_handle_efd_read(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + char buf[CHAN_RBUF]; + int r; + ssize_t len; + + if (!c->detach_close && !FD_ISSET(c->efd, readset)) + return 1; + + len = read(c->efd, buf, sizeof(buf)); + debug2("channel %d: read %zd from efd %d", c->self, len, c->efd); + if (len < 0 && (errno == EINTR || ((errno == EAGAIN || + errno == EWOULDBLOCK) && !c->detach_close))) + return 1; + if (len <= 0) { + debug2("channel %d: closing read-efd %d", + c->self, c->efd); + channel_close_fd(ssh, &c->efd); + } else { + if (c->extended_usage == CHAN_EXTENDED_IGNORE) { + debug3("channel %d: discard efd", + c->self); + } else if ((r = sshbuf_put(c->extended, buf, len)) != 0) { + fatal("%s: channel %d: append: %s", + __func__, c->self, ssh_err(r)); + } + } + return 1; +} + +static int +channel_handle_efd(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + if (c->efd == -1) + return 1; + + /** XXX handle drain efd, too */ + + if (c->extended_usage == CHAN_EXTENDED_WRITE) + return channel_handle_efd_write(ssh, c, readset, writeset); + else if (c->extended_usage == CHAN_EXTENDED_READ || + c->extended_usage == CHAN_EXTENDED_IGNORE) + return channel_handle_efd_read(ssh, c, readset, writeset); + + return 1; +} + +static int +channel_check_window(struct ssh *ssh, Channel *c) +{ + int r; + + if (c->type == SSH_CHANNEL_OPEN && + !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) && + ((c->local_window_max - c->local_window > + c->local_maxpacket*3) || + c->local_window < c->local_window_max/2) && + c->local_consumed > 0) { + if (!c->have_remote_id) + fatal(":%s: channel %d: no remote id", + __func__, c->self); + if ((r = sshpkt_start(ssh, + SSH2_MSG_CHANNEL_WINDOW_ADJUST)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_consumed)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + fatal("%s: channel %i: %s", __func__, + c->self, ssh_err(r)); + } + debug2("channel %d: window %d sent adjust %d", + c->self, c->local_window, + c->local_consumed); + c->local_window += c->local_consumed; + c->local_consumed = 0; + } + return 1; +} + +static void +channel_post_open(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + channel_handle_rfd(ssh, c, readset, writeset); + channel_handle_wfd(ssh, c, readset, writeset); + channel_handle_efd(ssh, c, readset, writeset); + channel_check_window(ssh, c); +} + +static u_int +read_mux(struct ssh *ssh, Channel *c, u_int need) +{ + char buf[CHAN_RBUF]; + ssize_t len; + u_int rlen; + int r; + + if (sshbuf_len(c->input) < need) { + rlen = need - sshbuf_len(c->input); + len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF)); + if (len < 0 && (errno == EINTR || errno == EAGAIN)) + return sshbuf_len(c->input); + if (len <= 0) { + debug2("channel %d: ctl read<=0 rfd %d len %zd", + c->self, c->rfd, len); + chan_read_failed(ssh, c); + return 0; + } else if ((r = sshbuf_put(c->input, buf, len)) != 0) { + fatal("%s: channel %d: append: %s", + __func__, c->self, ssh_err(r)); + } + } + return sshbuf_len(c->input); +} + +static void +channel_post_mux_client_read(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + u_int need; + + if (c->rfd == -1 || !FD_ISSET(c->rfd, readset)) + return; + if (c->istate != CHAN_INPUT_OPEN && c->istate != CHAN_INPUT_WAIT_DRAIN) + return; + if (c->mux_pause) + return; + + /* + * Don't not read past the precise end of packets to + * avoid disrupting fd passing. + */ + if (read_mux(ssh, c, 4) < 4) /* read header */ + return; + /* XXX sshbuf_peek_u32 */ + need = PEEK_U32(sshbuf_ptr(c->input)); +#define CHANNEL_MUX_MAX_PACKET (256 * 1024) + if (need > CHANNEL_MUX_MAX_PACKET) { + debug2("channel %d: packet too big %u > %u", + c->self, CHANNEL_MUX_MAX_PACKET, need); + chan_rcvd_oclose(ssh, c); + return; + } + if (read_mux(ssh, c, need + 4) < need + 4) /* read body */ + return; + if (c->mux_rcb(ssh, c) != 0) { + debug("channel %d: mux_rcb failed", c->self); + chan_mark_dead(ssh, c); + return; + } +} + +static void +channel_post_mux_client_write(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + ssize_t len; + int r; + + if (c->wfd == -1 || !FD_ISSET(c->wfd, writeset) || + sshbuf_len(c->output) == 0) + return; + + len = write(c->wfd, sshbuf_ptr(c->output), sshbuf_len(c->output)); + if (len < 0 && (errno == EINTR || errno == EAGAIN)) + return; + if (len <= 0) { + chan_mark_dead(ssh, c); + return; + } + if ((r = sshbuf_consume(c->output, len)) != 0) + fatal("%s: channel %d: consume: %s", __func__, + c->self, ssh_err(r)); +} + +static void +channel_post_mux_client(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + channel_post_mux_client_read(ssh, c, readset, writeset); + channel_post_mux_client_write(ssh, c, readset, writeset); +} + +static void +channel_post_mux_listener(struct ssh *ssh, Channel *c, + fd_set *readset, fd_set *writeset) +{ + Channel *nc; + struct sockaddr_storage addr; + socklen_t addrlen; + int newsock; + uid_t euid; + gid_t egid; + + if (!FD_ISSET(c->sock, readset)) + return; + + debug("multiplexing control connection"); + + /* + * Accept connection on control socket + */ + memset(&addr, 0, sizeof(addr)); + addrlen = sizeof(addr); + if ((newsock = accept(c->sock, (struct sockaddr*)&addr, + &addrlen)) == -1) { + error("%s accept: %s", __func__, strerror(errno)); + if (errno == EMFILE || errno == ENFILE) + c->notbefore = monotime() + 1; + return; + } + + if (getpeereid(newsock, &euid, &egid) < 0) { + error("%s getpeereid failed: %s", __func__, + strerror(errno)); + close(newsock); + return; + } + if ((euid != 0) && (getuid() != euid)) { + error("multiplex uid mismatch: peer euid %u != uid %u", + (u_int)euid, (u_int)getuid()); + close(newsock); + return; + } + nc = channel_new(ssh, "multiplex client", SSH_CHANNEL_MUX_CLIENT, + newsock, newsock, -1, c->local_window_max, + c->local_maxpacket, 0, "mux-control", 1); + nc->mux_rcb = c->mux_rcb; + debug3("%s: new mux channel %d fd %d", __func__, nc->self, nc->sock); + /* establish state */ + nc->mux_rcb(ssh, nc); + /* mux state transitions must not elicit protocol messages */ + nc->flags |= CHAN_LOCAL; +} + +static void +channel_handler_init(struct ssh_channels *sc) +{ + chan_fn **pre, **post; + + if ((pre = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*pre))) == NULL || + (post = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*post))) == NULL) + fatal("%s: allocation failed", __func__); + + pre[SSH_CHANNEL_OPEN] = &channel_pre_open; + pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open; + pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener; + pre[SSH_CHANNEL_RPORT_LISTENER] = &channel_pre_listener; + pre[SSH_CHANNEL_UNIX_LISTENER] = &channel_pre_listener; + pre[SSH_CHANNEL_RUNIX_LISTENER] = &channel_pre_listener; + pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener; + pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener; + pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting; + pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic; + pre[SSH_CHANNEL_RDYNAMIC_FINISH] = &channel_pre_connecting; + pre[SSH_CHANNEL_MUX_LISTENER] = &channel_pre_listener; + pre[SSH_CHANNEL_MUX_CLIENT] = &channel_pre_mux_client; + + post[SSH_CHANNEL_OPEN] = &channel_post_open; + post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener; + post[SSH_CHANNEL_RPORT_LISTENER] = &channel_post_port_listener; + post[SSH_CHANNEL_UNIX_LISTENER] = &channel_post_port_listener; + post[SSH_CHANNEL_RUNIX_LISTENER] = &channel_post_port_listener; + post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener; + post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener; + post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting; + post[SSH_CHANNEL_DYNAMIC] = &channel_post_open; + post[SSH_CHANNEL_RDYNAMIC_FINISH] = &channel_post_connecting; + post[SSH_CHANNEL_MUX_LISTENER] = &channel_post_mux_listener; + post[SSH_CHANNEL_MUX_CLIENT] = &channel_post_mux_client; + + sc->channel_pre = pre; + sc->channel_post = post; +} + +/* gc dead channels */ +static void +channel_garbage_collect(struct ssh *ssh, Channel *c) +{ + if (c == NULL) + return; + if (c->detach_user != NULL) { + if (!chan_is_dead(ssh, c, c->detach_close)) + return; + + debug2("channel %d: gc: notify user", c->self); + c->detach_user(ssh, c->self, NULL); + /* if we still have a callback */ + if (c->detach_user != NULL) + return; + debug2("channel %d: gc: user detached", c->self); + } + if (!chan_is_dead(ssh, c, 1)) + return; + debug2("channel %d: garbage collecting", c->self); + channel_free(ssh, c); +} + +enum channel_table { CHAN_PRE, CHAN_POST }; + +static void +channel_handler(struct ssh *ssh, int table, + fd_set *readset, fd_set *writeset, time_t *unpause_secs) +{ + struct ssh_channels *sc = ssh->chanctxt; + chan_fn **ftab = table == CHAN_PRE ? sc->channel_pre : sc->channel_post; + u_int i, oalloc; + Channel *c; + time_t now; + + now = monotime(); + if (unpause_secs != NULL) + *unpause_secs = 0; + for (i = 0, oalloc = sc->channels_alloc; i < oalloc; i++) { + c = sc->channels[i]; + if (c == NULL) + continue; + if (c->delayed) { + if (table == CHAN_PRE) + c->delayed = 0; + else + continue; + } + if (ftab[c->type] != NULL) { + /* + * Run handlers that are not paused. + */ + if (c->notbefore <= now) + (*ftab[c->type])(ssh, c, readset, writeset); + else if (unpause_secs != NULL) { + /* + * Collect the time that the earliest + * channel comes off pause. + */ + debug3("%s: chan %d: skip for %d more seconds", + __func__, c->self, + (int)(c->notbefore - now)); + if (*unpause_secs == 0 || + (c->notbefore - now) < *unpause_secs) + *unpause_secs = c->notbefore - now; + } + } + channel_garbage_collect(ssh, c); + } + if (unpause_secs != NULL && *unpause_secs != 0) + debug3("%s: first channel unpauses in %d seconds", + __func__, (int)*unpause_secs); +} + +/* + * Create sockets before allocating the select bitmasks. + * This is necessary for things that need to happen after reading + * the network-input but before channel_prepare_select(). + */ +static void +channel_before_prepare_select(struct ssh *ssh) +{ + struct ssh_channels *sc = ssh->chanctxt; + Channel *c; + u_int i, oalloc; + + for (i = 0, oalloc = sc->channels_alloc; i < oalloc; i++) { + c = sc->channels[i]; + if (c == NULL) + continue; + if (c->type == SSH_CHANNEL_RDYNAMIC_OPEN) + channel_before_prepare_select_rdynamic(ssh, c); + } +} + +/* + * Allocate/update select bitmasks and add any bits relevant to channels in + * select bitmasks. + */ +void +channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp, + int *maxfdp, u_int *nallocp, time_t *minwait_secs) +{ + u_int n, sz, nfdset; + + channel_before_prepare_select(ssh); /* might update channel_max_fd */ + + n = MAXIMUM(*maxfdp, ssh->chanctxt->channel_max_fd); + + nfdset = howmany(n+1, NFDBITS); + /* Explicitly test here, because xrealloc isn't always called */ + if (nfdset && SIZE_MAX / nfdset < sizeof(fd_mask)) + fatal("channel_prepare_select: max_fd (%d) is too large", n); + sz = nfdset * sizeof(fd_mask); + + /* perhaps check sz < nalloc/2 and shrink? */ + if (*readsetp == NULL || sz > *nallocp) { + *readsetp = xreallocarray(*readsetp, nfdset, sizeof(fd_mask)); + *writesetp = xreallocarray(*writesetp, nfdset, sizeof(fd_mask)); + *nallocp = sz; + } + *maxfdp = n; + memset(*readsetp, 0, sz); + memset(*writesetp, 0, sz); + + if (!ssh_packet_is_rekeying(ssh)) + channel_handler(ssh, CHAN_PRE, *readsetp, *writesetp, + minwait_secs); +} + +/* + * After select, perform any appropriate operations for channels which have + * events pending. + */ +void +channel_after_select(struct ssh *ssh, fd_set *readset, fd_set *writeset) +{ + channel_handler(ssh, CHAN_POST, readset, writeset, NULL); +} + +/* + * Enqueue data for channels with open or draining c->input. + */ +static void +channel_output_poll_input_open(struct ssh *ssh, Channel *c) +{ + size_t len, plen; + const u_char *pkt; + int r; + + if ((len = sshbuf_len(c->input)) == 0) { + if (c->istate == CHAN_INPUT_WAIT_DRAIN) { + /* + * input-buffer is empty and read-socket shutdown: + * tell peer, that we will not send more data: + * send IEOF. + * hack for extended data: delay EOF if EFD still + * in use. + */ + if (CHANNEL_EFD_INPUT_ACTIVE(c)) + debug2("channel %d: " + "ibuf_empty delayed efd %d/(%zu)", + c->self, c->efd, sshbuf_len(c->extended)); + else + chan_ibuf_empty(ssh, c); + } + return; + } + + if (!c->have_remote_id) + fatal(":%s: channel %d: no remote id", __func__, c->self); + + if (c->datagram) { + /* Check datagram will fit; drop if not */ + if ((r = sshbuf_get_string_direct(c->input, &pkt, &plen)) != 0) + fatal("%s: channel %d: get datagram: %s", __func__, + c->self, ssh_err(r)); + /* + * XXX this does tail-drop on the datagram queue which is + * usually suboptimal compared to head-drop. Better to have + * backpressure at read time? (i.e. read + discard) + */ + if (plen > c->remote_window || plen > c->remote_maxpacket) { + debug("channel %d: datagram too big", c->self); + return; + } + /* Enqueue it */ + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_string(ssh, pkt, plen)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + fatal("%s: channel %i: datagram: %s", __func__, + c->self, ssh_err(r)); + } + c->remote_window -= plen; + return; + } + + /* Enqueue packet for buffered data. */ + if (len > c->remote_window) + len = c->remote_window; + if (len > c->remote_maxpacket) + len = c->remote_maxpacket; + if (len == 0) + return; + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_string(ssh, sshbuf_ptr(c->input), len)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + fatal("%s: channel %i: data: %s", __func__, + c->self, ssh_err(r)); + } + if ((r = sshbuf_consume(c->input, len)) != 0) + fatal("%s: channel %i: consume: %s", __func__, + c->self, ssh_err(r)); + c->remote_window -= len; +} + +/* + * Enqueue data for channels with open c->extended in read mode. + */ +static void +channel_output_poll_extended_read(struct ssh *ssh, Channel *c) +{ + size_t len; + int r; + + if ((len = sshbuf_len(c->extended)) == 0) + return; + + debug2("channel %d: rwin %u elen %zu euse %d", c->self, + c->remote_window, sshbuf_len(c->extended), c->extended_usage); + if (len > c->remote_window) + len = c->remote_window; + if (len > c->remote_maxpacket) + len = c->remote_maxpacket; + if (len == 0) + return; + if (!c->have_remote_id) + fatal(":%s: channel %d: no remote id", __func__, c->self); + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_u32(ssh, SSH2_EXTENDED_DATA_STDERR)) != 0 || + (r = sshpkt_put_string(ssh, sshbuf_ptr(c->extended), len)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + fatal("%s: channel %i: data: %s", __func__, + c->self, ssh_err(r)); + } + if ((r = sshbuf_consume(c->extended, len)) != 0) + fatal("%s: channel %i: consume: %s", __func__, + c->self, ssh_err(r)); + c->remote_window -= len; + debug2("channel %d: sent ext data %zu", c->self, len); +} + +/* If there is data to send to the connection, enqueue some of it now. */ +void +channel_output_poll(struct ssh *ssh) +{ + struct ssh_channels *sc = ssh->chanctxt; + Channel *c; + u_int i; + + for (i = 0; i < sc->channels_alloc; i++) { + c = sc->channels[i]; + if (c == NULL) + continue; + + /* + * We are only interested in channels that can have buffered + * incoming data. + */ + if (c->type != SSH_CHANNEL_OPEN) + continue; + if ((c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) { + /* XXX is this true? */ + debug3("channel %d: will not send data after close", + c->self); + continue; + } + + /* Get the amount of buffered data for this channel. */ + if (c->istate == CHAN_INPUT_OPEN || + c->istate == CHAN_INPUT_WAIT_DRAIN) + channel_output_poll_input_open(ssh, c); + /* Send extended data, i.e. stderr */ + if (!(c->flags & CHAN_EOF_SENT) && + c->extended_usage == CHAN_EXTENDED_READ) + channel_output_poll_extended_read(ssh, c); + } +} + +/* -- mux proxy support */ + +/* + * When multiplexing channel messages for mux clients we have to deal + * with downstream messages from the mux client and upstream messages + * from the ssh server: + * 1) Handling downstream messages is straightforward and happens + * in channel_proxy_downstream(): + * - We forward all messages (mostly) unmodified to the server. + * - However, in order to route messages from upstream to the correct + * downstream client, we have to replace the channel IDs used by the + * mux clients with a unique channel ID because the mux clients might + * use conflicting channel IDs. + * - so we inspect and change both SSH2_MSG_CHANNEL_OPEN and + * SSH2_MSG_CHANNEL_OPEN_CONFIRMATION messages, create a local + * SSH_CHANNEL_MUX_PROXY channel and replace the mux clients ID + * with the newly allocated channel ID. + * 2) Upstream messages are received by matching SSH_CHANNEL_MUX_PROXY + * channels and processed by channel_proxy_upstream(). The local channel ID + * is then translated back to the original mux client ID. + * 3) In both cases we need to keep track of matching SSH2_MSG_CHANNEL_CLOSE + * messages so we can clean up SSH_CHANNEL_MUX_PROXY channels. + * 4) The SSH_CHANNEL_MUX_PROXY channels also need to closed when the + * downstream mux client are removed. + * 5) Handling SSH2_MSG_CHANNEL_OPEN messages from the upstream server + * requires more work, because they are not addressed to a specific + * channel. E.g. client_request_forwarded_tcpip() needs to figure + * out whether the request is addressed to the local client or a + * specific downstream client based on the listen-address/port. + * 6) Agent and X11-Forwarding have a similar problem and are currently + * not supported as the matching session/channel cannot be identified + * easily. + */ + +/* + * receive packets from downstream mux clients: + * channel callback fired on read from mux client, creates + * SSH_CHANNEL_MUX_PROXY channels and translates channel IDs + * on channel creation. + */ +int +channel_proxy_downstream(struct ssh *ssh, Channel *downstream) +{ + Channel *c = NULL; + struct sshbuf *original = NULL, *modified = NULL; + const u_char *cp; + char *ctype = NULL, *listen_host = NULL; + u_char type; + size_t have; + int ret = -1, r; + u_int id, remote_id, listen_port; + + /* sshbuf_dump(downstream->input, stderr); */ + if ((r = sshbuf_get_string_direct(downstream->input, &cp, &have)) + != 0) { + error("%s: malformed message: %s", __func__, ssh_err(r)); + return -1; + } + if (have < 2) { + error("%s: short message", __func__); + return -1; + } + type = cp[1]; + /* skip padlen + type */ + cp += 2; + have -= 2; + if (ssh_packet_log_type(type)) + debug3("%s: channel %u: down->up: type %u", __func__, + downstream->self, type); + + switch (type) { + case SSH2_MSG_CHANNEL_OPEN: + if ((original = sshbuf_from(cp, have)) == NULL || + (modified = sshbuf_new()) == NULL) { + error("%s: alloc", __func__); + goto out; + } + if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0 || + (r = sshbuf_get_u32(original, &id)) != 0) { + error("%s: parse error %s", __func__, ssh_err(r)); + goto out; + } + c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY, + -1, -1, -1, 0, 0, 0, ctype, 1); + c->mux_ctx = downstream; /* point to mux client */ + c->mux_downstream_id = id; /* original downstream id */ + if ((r = sshbuf_put_cstring(modified, ctype)) != 0 || + (r = sshbuf_put_u32(modified, c->self)) != 0 || + (r = sshbuf_putb(modified, original)) != 0) { + error("%s: compose error %s", __func__, ssh_err(r)); + channel_free(ssh, c); + goto out; + } + break; + case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION: + /* + * Almost the same as SSH2_MSG_CHANNEL_OPEN, except then we + * need to parse 'remote_id' instead of 'ctype'. + */ + if ((original = sshbuf_from(cp, have)) == NULL || + (modified = sshbuf_new()) == NULL) { + error("%s: alloc", __func__); + goto out; + } + if ((r = sshbuf_get_u32(original, &remote_id)) != 0 || + (r = sshbuf_get_u32(original, &id)) != 0) { + error("%s: parse error %s", __func__, ssh_err(r)); + goto out; + } + c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY, + -1, -1, -1, 0, 0, 0, "mux-down-connect", 1); + c->mux_ctx = downstream; /* point to mux client */ + c->mux_downstream_id = id; + c->remote_id = remote_id; + c->have_remote_id = 1; + if ((r = sshbuf_put_u32(modified, remote_id)) != 0 || + (r = sshbuf_put_u32(modified, c->self)) != 0 || + (r = sshbuf_putb(modified, original)) != 0) { + error("%s: compose error %s", __func__, ssh_err(r)); + channel_free(ssh, c); + goto out; + } + break; + case SSH2_MSG_GLOBAL_REQUEST: + if ((original = sshbuf_from(cp, have)) == NULL) { + error("%s: alloc", __func__); + goto out; + } + if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0) { + error("%s: parse error %s", __func__, ssh_err(r)); + goto out; + } + if (strcmp(ctype, "tcpip-forward") != 0) { + error("%s: unsupported request %s", __func__, ctype); + goto out; + } + if ((r = sshbuf_get_u8(original, NULL)) != 0 || + (r = sshbuf_get_cstring(original, &listen_host, NULL)) != 0 || + (r = sshbuf_get_u32(original, &listen_port)) != 0) { + error("%s: parse error %s", __func__, ssh_err(r)); + goto out; + } + if (listen_port > 65535) { + error("%s: tcpip-forward for %s: bad port %u", + __func__, listen_host, listen_port); + goto out; + } + /* Record that connection to this host/port is permitted. */ + permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL, "<mux>", -1, + listen_host, NULL, (int)listen_port, downstream); + listen_host = NULL; + break; + case SSH2_MSG_CHANNEL_CLOSE: + if (have < 4) + break; + remote_id = PEEK_U32(cp); + if ((c = channel_by_remote_id(ssh, remote_id)) != NULL) { + if (c->flags & CHAN_CLOSE_RCVD) + channel_free(ssh, c); + else + c->flags |= CHAN_CLOSE_SENT; + } + break; + } + if (modified) { + if ((r = sshpkt_start(ssh, type)) != 0 || + (r = sshpkt_putb(ssh, modified)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + error("%s: send %s", __func__, ssh_err(r)); + goto out; + } + } else { + if ((r = sshpkt_start(ssh, type)) != 0 || + (r = sshpkt_put(ssh, cp, have)) != 0 || + (r = sshpkt_send(ssh)) != 0) { + error("%s: send %s", __func__, ssh_err(r)); + goto out; + } + } + ret = 0; + out: + free(ctype); + free(listen_host); + sshbuf_free(original); + sshbuf_free(modified); + return ret; +} + +/* + * receive packets from upstream server and de-multiplex packets + * to correct downstream: + * implemented as a helper for channel input handlers, + * replaces local (proxy) channel ID with downstream channel ID. + */ +int +channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh) +{ + struct sshbuf *b = NULL; + Channel *downstream; + const u_char *cp = NULL; + size_t len; + int r; + + /* + * When receiving packets from the peer we need to check whether we + * need to forward the packets to the mux client. In this case we + * restore the original channel id and keep track of CLOSE messages, + * so we can cleanup the channel. + */ + if (c == NULL || c->type != SSH_CHANNEL_MUX_PROXY) + return 0; + if ((downstream = c->mux_ctx) == NULL) + return 0; + switch (type) { + case SSH2_MSG_CHANNEL_CLOSE: + case SSH2_MSG_CHANNEL_DATA: + case SSH2_MSG_CHANNEL_EOF: + case SSH2_MSG_CHANNEL_EXTENDED_DATA: + case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION: + case SSH2_MSG_CHANNEL_OPEN_FAILURE: + case SSH2_MSG_CHANNEL_WINDOW_ADJUST: + case SSH2_MSG_CHANNEL_SUCCESS: + case SSH2_MSG_CHANNEL_FAILURE: + case SSH2_MSG_CHANNEL_REQUEST: + break; + default: + debug2("%s: channel %u: unsupported type %u", __func__, + c->self, type); + return 0; + } + if ((b = sshbuf_new()) == NULL) { + error("%s: alloc reply", __func__); + goto out; + } + /* get remaining payload (after id) */ + cp = sshpkt_ptr(ssh, &len); + if (cp == NULL) { + error("%s: no packet", __func__); + goto out; + } + /* translate id and send to muxclient */ + if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ + (r = sshbuf_put_u8(b, type)) != 0 || + (r = sshbuf_put_u32(b, c->mux_downstream_id)) != 0 || + (r = sshbuf_put(b, cp, len)) != 0 || + (r = sshbuf_put_stringb(downstream->output, b)) != 0) { + error("%s: compose for muxclient %s", __func__, ssh_err(r)); + goto out; + } + /* sshbuf_dump(b, stderr); */ + if (ssh_packet_log_type(type)) + debug3("%s: channel %u: up->down: type %u", __func__, c->self, + type); + out: + /* update state */ + switch (type) { + case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION: + /* record remote_id for SSH2_MSG_CHANNEL_CLOSE */ + if (cp && len > 4) { + c->remote_id = PEEK_U32(cp); + c->have_remote_id = 1; + } + break; + case SSH2_MSG_CHANNEL_CLOSE: + if (c->flags & CHAN_CLOSE_SENT) + channel_free(ssh, c); + else + c->flags |= CHAN_CLOSE_RCVD; + break; + } + sshbuf_free(b); + return 1; +} + +/* -- protocol input */ + +/* Parse a channel ID from the current packet */ +static int +channel_parse_id(struct ssh *ssh, const char *where, const char *what) +{ + u_int32_t id; + int r; + + if ((r = sshpkt_get_u32(ssh, &id)) != 0) { + error("%s: parse id: %s", where, ssh_err(r)); + ssh_packet_disconnect(ssh, "Invalid %s message", what); + } + if (id > INT_MAX) { + error("%s: bad channel id %u: %s", where, id, ssh_err(r)); + ssh_packet_disconnect(ssh, "Invalid %s channel id", what); + } + return (int)id; +} + +/* Lookup a channel from an ID in the current packet */ +static Channel * +channel_from_packet_id(struct ssh *ssh, const char *where, const char *what) +{ + int id = channel_parse_id(ssh, where, what); + Channel *c; + + if ((c = channel_lookup(ssh, id)) == NULL) { + ssh_packet_disconnect(ssh, + "%s packet referred to nonexistent channel %d", what, id); + } + return c; +} + +int +channel_input_data(int type, u_int32_t seq, struct ssh *ssh) +{ + const u_char *data; + size_t data_len, win_len; + Channel *c = channel_from_packet_id(ssh, __func__, "data"); + int r; + + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + + /* Ignore any data for non-open channels (might happen on close) */ + if (c->type != SSH_CHANNEL_OPEN && + c->type != SSH_CHANNEL_RDYNAMIC_OPEN && + c->type != SSH_CHANNEL_RDYNAMIC_FINISH && + c->type != SSH_CHANNEL_X11_OPEN) + return 0; + + /* Get the data. */ + if ((r = sshpkt_get_string_direct(ssh, &data, &data_len)) != 0) + fatal("%s: channel %d: get data: %s", __func__, + c->self, ssh_err(r)); + ssh_packet_check_eom(ssh); + + win_len = data_len; + if (c->datagram) + win_len += 4; /* string length header */ + + /* + * The sending side reduces its window as it sends data, so we + * must 'fake' consumption of the data in order to ensure that window + * updates are sent back. Otherwise the connection might deadlock. + */ + if (c->ostate != CHAN_OUTPUT_OPEN) { + c->local_window -= win_len; + c->local_consumed += win_len; + return 0; + } + + if (win_len > c->local_maxpacket) { + logit("channel %d: rcvd big packet %zu, maxpack %u", + c->self, win_len, c->local_maxpacket); + return 0; + } + if (win_len > c->local_window) { + logit("channel %d: rcvd too much data %zu, win %u", + c->self, win_len, c->local_window); + return 0; + } + c->local_window -= win_len; + + if (c->datagram) { + if ((r = sshbuf_put_string(c->output, data, data_len)) != 0) + fatal("%s: channel %d: append datagram: %s", + __func__, c->self, ssh_err(r)); + } else if ((r = sshbuf_put(c->output, data, data_len)) != 0) + fatal("%s: channel %d: append data: %s", + __func__, c->self, ssh_err(r)); + + return 0; +} + +int +channel_input_extended_data(int type, u_int32_t seq, struct ssh *ssh) +{ + const u_char *data; + size_t data_len; + u_int32_t tcode; + Channel *c = channel_from_packet_id(ssh, __func__, "extended data"); + int r; + + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + if (c->type != SSH_CHANNEL_OPEN) { + logit("channel %d: ext data for non open", c->self); + return 0; + } + if (c->flags & CHAN_EOF_RCVD) { + if (datafellows & SSH_BUG_EXTEOF) + debug("channel %d: accepting ext data after eof", + c->self); + else + ssh_packet_disconnect(ssh, "Received extended_data " + "after EOF on channel %d.", c->self); + } + + if ((r = sshpkt_get_u32(ssh, &tcode)) != 0) { + error("%s: parse tcode: %s", __func__, ssh_err(r)); + ssh_packet_disconnect(ssh, "Invalid extended_data message"); + } + if (c->efd == -1 || + c->extended_usage != CHAN_EXTENDED_WRITE || + tcode != SSH2_EXTENDED_DATA_STDERR) { + logit("channel %d: bad ext data", c->self); + return 0; + } + if ((r = sshpkt_get_string_direct(ssh, &data, &data_len)) != 0) { + error("%s: parse data: %s", __func__, ssh_err(r)); + ssh_packet_disconnect(ssh, "Invalid extended_data message"); + } + ssh_packet_check_eom(ssh); + + if (data_len > c->local_window) { + logit("channel %d: rcvd too much extended_data %zu, win %u", + c->self, data_len, c->local_window); + return 0; + } + debug2("channel %d: rcvd ext data %zu", c->self, data_len); + /* XXX sshpkt_getb? */ + if ((r = sshbuf_put(c->extended, data, data_len)) != 0) + error("%s: append: %s", __func__, ssh_err(r)); + c->local_window -= data_len; + return 0; +} + +int +channel_input_ieof(int type, u_int32_t seq, struct ssh *ssh) +{ + Channel *c = channel_from_packet_id(ssh, __func__, "ieof"); + + ssh_packet_check_eom(ssh); + + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + chan_rcvd_ieof(ssh, c); + + /* XXX force input close */ + if (c->force_drain && c->istate == CHAN_INPUT_OPEN) { + debug("channel %d: FORCE input drain", c->self); + c->istate = CHAN_INPUT_WAIT_DRAIN; + if (sshbuf_len(c->input) == 0) + chan_ibuf_empty(ssh, c); + } + return 0; +} + +int +channel_input_oclose(int type, u_int32_t seq, struct ssh *ssh) +{ + Channel *c = channel_from_packet_id(ssh, __func__, "oclose"); + + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + ssh_packet_check_eom(ssh); + chan_rcvd_oclose(ssh, c); + return 0; +} + +int +channel_input_open_confirmation(int type, u_int32_t seq, struct ssh *ssh) +{ + Channel *c = channel_from_packet_id(ssh, __func__, "open confirmation"); + u_int32_t remote_window, remote_maxpacket; + int r; + + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + if (c->type != SSH_CHANNEL_OPENING) + packet_disconnect("Received open confirmation for " + "non-opening channel %d.", c->self); + /* + * Record the remote channel number and mark that the channel + * is now open. + */ + if ((r = sshpkt_get_u32(ssh, &c->remote_id)) != 0 || + (r = sshpkt_get_u32(ssh, &remote_window)) != 0 || + (r = sshpkt_get_u32(ssh, &remote_maxpacket)) != 0) { + error("%s: window/maxpacket: %s", __func__, ssh_err(r)); + packet_disconnect("Invalid open confirmation message"); + } + ssh_packet_check_eom(ssh); + + c->have_remote_id = 1; + c->remote_window = remote_window; + c->remote_maxpacket = remote_maxpacket; + c->type = SSH_CHANNEL_OPEN; + if (c->open_confirm) { + debug2("%s: channel %d: callback start", __func__, c->self); + c->open_confirm(ssh, c->self, 1, c->open_confirm_ctx); + debug2("%s: channel %d: callback done", __func__, c->self); + } + debug2("channel %d: open confirm rwindow %u rmax %u", c->self, + c->remote_window, c->remote_maxpacket); + return 0; +} + +static char * +reason2txt(int reason) +{ + switch (reason) { + case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED: + return "administratively prohibited"; + case SSH2_OPEN_CONNECT_FAILED: + return "connect failed"; + case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE: + return "unknown channel type"; + case SSH2_OPEN_RESOURCE_SHORTAGE: + return "resource shortage"; + } + return "unknown reason"; +} + +int +channel_input_open_failure(int type, u_int32_t seq, struct ssh *ssh) +{ + Channel *c = channel_from_packet_id(ssh, __func__, "open failure"); + u_int32_t reason; + char *msg = NULL; + int r; + + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + if (c->type != SSH_CHANNEL_OPENING) + packet_disconnect("Received open failure for " + "non-opening channel %d.", c->self); + if ((r = sshpkt_get_u32(ssh, &reason)) != 0) { + error("%s: reason: %s", __func__, ssh_err(r)); + packet_disconnect("Invalid open failure message"); + } + /* skip language */ + if ((r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 || + (r = sshpkt_get_string_direct(ssh, NULL, NULL)) != 0) { + error("%s: message/lang: %s", __func__, ssh_err(r)); + packet_disconnect("Invalid open failure message"); + } + ssh_packet_check_eom(ssh); + logit("channel %d: open failed: %s%s%s", c->self, + reason2txt(reason), msg ? ": ": "", msg ? msg : ""); + free(msg); + if (c->open_confirm) { + debug2("%s: channel %d: callback start", __func__, c->self); + c->open_confirm(ssh, c->self, 0, c->open_confirm_ctx); + debug2("%s: channel %d: callback done", __func__, c->self); + } + /* Schedule the channel for cleanup/deletion. */ + chan_mark_dead(ssh, c); + return 0; +} + +int +channel_input_window_adjust(int type, u_int32_t seq, struct ssh *ssh) +{ + int id = channel_parse_id(ssh, __func__, "window adjust"); + Channel *c; + u_int32_t adjust; + u_int new_rwin; + int r; + + if ((c = channel_lookup(ssh, id)) == NULL) { + logit("Received window adjust for non-open channel %d.", id); + return 0; + } + + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + if ((r = sshpkt_get_u32(ssh, &adjust)) != 0) { + error("%s: adjust: %s", __func__, ssh_err(r)); + packet_disconnect("Invalid window adjust message"); + } + ssh_packet_check_eom(ssh); + debug2("channel %d: rcvd adjust %u", c->self, adjust); + if ((new_rwin = c->remote_window + adjust) < c->remote_window) { + fatal("channel %d: adjust %u overflows remote window %u", + c->self, adjust, c->remote_window); + } + c->remote_window = new_rwin; + return 0; +} + +int +channel_input_status_confirm(int type, u_int32_t seq, struct ssh *ssh) +{ + int id = channel_parse_id(ssh, __func__, "status confirm"); + Channel *c; + struct channel_confirm *cc; + + /* Reset keepalive timeout */ + packet_set_alive_timeouts(0); + + debug2("%s: type %d id %d", __func__, type, id); + + if ((c = channel_lookup(ssh, id)) == NULL) { + logit("%s: %d: unknown", __func__, id); + return 0; + } + if (channel_proxy_upstream(c, type, seq, ssh)) + return 0; + ssh_packet_check_eom(ssh); + if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL) + return 0; + cc->cb(ssh, type, c, cc->ctx); + TAILQ_REMOVE(&c->status_confirms, cc, entry); + explicit_bzero(cc, sizeof(*cc)); + free(cc); + return 0; +} + +/* -- tcp forwarding */ + +void +channel_set_af(struct ssh *ssh, int af) +{ + ssh->chanctxt->IPv4or6 = af; +} + + +/* + * Determine whether or not a port forward listens to loopback, the + * specified address or wildcard. On the client, a specified bind + * address will always override gateway_ports. On the server, a + * gateway_ports of 1 (``yes'') will override the client's specification + * and force a wildcard bind, whereas a value of 2 (``clientspecified'') + * will bind to whatever address the client asked for. + * + * Special-case listen_addrs are: + * + * "0.0.0.0" -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR + * "" (empty string), "*" -> wildcard v4/v6 + * "localhost" -> loopback v4/v6 + * "127.0.0.1" / "::1" -> accepted even if gateway_ports isn't set + */ +static const char * +channel_fwd_bind_addr(const char *listen_addr, int *wildcardp, + int is_client, struct ForwardOptions *fwd_opts) +{ + const char *addr = NULL; + int wildcard = 0; + + if (listen_addr == NULL) { + /* No address specified: default to gateway_ports setting */ + if (fwd_opts->gateway_ports) + wildcard = 1; + } else if (fwd_opts->gateway_ports || is_client) { + if (((datafellows & SSH_OLD_FORWARD_ADDR) && + strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) || + *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 || + (!is_client && fwd_opts->gateway_ports == 1)) { + wildcard = 1; + /* + * Notify client if they requested a specific listen + * address and it was overridden. + */ + if (*listen_addr != '\0' && + strcmp(listen_addr, "0.0.0.0") != 0 && + strcmp(listen_addr, "*") != 0) { + packet_send_debug("Forwarding listen address " + "\"%s\" overridden by server " + "GatewayPorts", listen_addr); + } + } else if (strcmp(listen_addr, "localhost") != 0 || + strcmp(listen_addr, "127.0.0.1") == 0 || + strcmp(listen_addr, "::1") == 0) { + /* Accept localhost address when GatewayPorts=yes */ + addr = listen_addr; + } + } else if (strcmp(listen_addr, "127.0.0.1") == 0 || + strcmp(listen_addr, "::1") == 0) { + /* + * If a specific IPv4/IPv6 localhost address has been + * requested then accept it even if gateway_ports is in + * effect. This allows the client to prefer IPv4 or IPv6. + */ + addr = listen_addr; + } + if (wildcardp != NULL) + *wildcardp = wildcard; + return addr; +} + +static int +channel_setup_fwd_listener_tcpip(struct ssh *ssh, int type, + struct Forward *fwd, int *allocated_listen_port, + struct ForwardOptions *fwd_opts) +{ + Channel *c; + int sock, r, success = 0, wildcard = 0, is_client; + struct addrinfo hints, *ai, *aitop; + const char *host, *addr; + char ntop[NI_MAXHOST], strport[NI_MAXSERV]; + in_port_t *lport_p; + + is_client = (type == SSH_CHANNEL_PORT_LISTENER); + + if (is_client && fwd->connect_path != NULL) { + host = fwd->connect_path; + } else { + host = (type == SSH_CHANNEL_RPORT_LISTENER) ? + fwd->listen_host : fwd->connect_host; + if (host == NULL) { + error("No forward host name."); + return 0; + } + if (strlen(host) >= NI_MAXHOST) { + error("Forward host name too long."); + return 0; + } + } + + /* Determine the bind address, cf. channel_fwd_bind_addr() comment */ + addr = channel_fwd_bind_addr(fwd->listen_host, &wildcard, + is_client, fwd_opts); + debug3("%s: type %d wildcard %d addr %s", __func__, + type, wildcard, (addr == NULL) ? "NULL" : addr); + + /* + * getaddrinfo returns a loopback address if the hostname is + * set to NULL and hints.ai_flags is not AI_PASSIVE + */ + memset(&hints, 0, sizeof(hints)); + hints.ai_family = ssh->chanctxt->IPv4or6; + hints.ai_flags = wildcard ? AI_PASSIVE : 0; + hints.ai_socktype = SOCK_STREAM; + snprintf(strport, sizeof strport, "%d", fwd->listen_port); + if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) { + if (addr == NULL) { + /* This really shouldn't happen */ + packet_disconnect("getaddrinfo: fatal error: %s", + ssh_gai_strerror(r)); + } else { + error("%s: getaddrinfo(%.64s): %s", __func__, addr, + ssh_gai_strerror(r)); + } + return 0; + } + if (allocated_listen_port != NULL) + *allocated_listen_port = 0; + for (ai = aitop; ai; ai = ai->ai_next) { + switch (ai->ai_family) { + case AF_INET: + lport_p = &((struct sockaddr_in *)ai->ai_addr)-> + sin_port; + break; + case AF_INET6: + lport_p = &((struct sockaddr_in6 *)ai->ai_addr)-> + sin6_port; + break; + default: + continue; + } + /* + * If allocating a port for -R forwards, then use the + * same port for all address families. + */ + if (type == SSH_CHANNEL_RPORT_LISTENER && + fwd->listen_port == 0 && allocated_listen_port != NULL && + *allocated_listen_port > 0) + *lport_p = htons(*allocated_listen_port); + + if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop), + strport, sizeof(strport), + NI_NUMERICHOST|NI_NUMERICSERV) != 0) { + error("%s: getnameinfo failed", __func__); + continue; + } + /* Create a port to listen for the host. */ + sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); + if (sock < 0) { + /* this is no error since kernel may not support ipv6 */ + verbose("socket [%s]:%s: %.100s", ntop, strport, + strerror(errno)); + continue; + } + + set_reuseaddr(sock); + if (ai->ai_family == AF_INET6) + sock_set_v6only(sock); + + debug("Local forwarding listening on %s port %s.", + ntop, strport); + + /* Bind the socket to the address. */ + if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) { + /* + * address can be in if use ipv6 address is + * already bound + */ + if (!ai->ai_next) + error("bind [%s]:%s: %.100s", + ntop, strport, strerror(errno)); + else + verbose("bind [%s]:%s: %.100s", + ntop, strport, strerror(errno)); + + close(sock); + continue; + } + /* Start listening for connections on the socket. */ + if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { + error("listen: %.100s", strerror(errno)); + error("listen [%s]:%s: %.100s", ntop, strport, + strerror(errno)); + close(sock); + continue; + } + + /* + * fwd->listen_port == 0 requests a dynamically allocated port - + * record what we got. + */ + if (type == SSH_CHANNEL_RPORT_LISTENER && + fwd->listen_port == 0 && + allocated_listen_port != NULL && + *allocated_listen_port == 0) { + *allocated_listen_port = get_local_port(sock); + debug("Allocated listen port %d", + *allocated_listen_port); + } + + /* Allocate a channel number for the socket. */ + c = channel_new(ssh, "port listener", type, sock, sock, -1, + CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, + 0, "port listener", 1); + c->path = xstrdup(host); + c->host_port = fwd->connect_port; + c->listening_addr = addr == NULL ? NULL : xstrdup(addr); + if (fwd->listen_port == 0 && allocated_listen_port != NULL && + !(datafellows & SSH_BUG_DYNAMIC_RPORT)) + c->listening_port = *allocated_listen_port; + else + c->listening_port = fwd->listen_port; + success = 1; + } + if (success == 0) + error("%s: cannot listen to port: %d", __func__, + fwd->listen_port); + freeaddrinfo(aitop); + return success; +} + +static int +channel_setup_fwd_listener_streamlocal(struct ssh *ssh, int type, + struct Forward *fwd, struct ForwardOptions *fwd_opts) +{ + struct sockaddr_un sunaddr; + const char *path; + Channel *c; + int port, sock; + mode_t omask; + + switch (type) { + case SSH_CHANNEL_UNIX_LISTENER: + if (fwd->connect_path != NULL) { + if (strlen(fwd->connect_path) > sizeof(sunaddr.sun_path)) { + error("Local connecting path too long: %s", + fwd->connect_path); + return 0; + } + path = fwd->connect_path; + port = PORT_STREAMLOCAL; + } else { + if (fwd->connect_host == NULL) { + error("No forward host name."); + return 0; + } + if (strlen(fwd->connect_host) >= NI_MAXHOST) { + error("Forward host name too long."); + return 0; + } + path = fwd->connect_host; + port = fwd->connect_port; + } + break; + case SSH_CHANNEL_RUNIX_LISTENER: + path = fwd->listen_path; + port = PORT_STREAMLOCAL; + break; + default: + error("%s: unexpected channel type %d", __func__, type); + return 0; + } + + if (fwd->listen_path == NULL) { + error("No forward path name."); + return 0; + } + if (strlen(fwd->listen_path) > sizeof(sunaddr.sun_path)) { + error("Local listening path too long: %s", fwd->listen_path); + return 0; + } + + debug3("%s: type %d path %s", __func__, type, fwd->listen_path); + + /* Start a Unix domain listener. */ + omask = umask(fwd_opts->streamlocal_bind_mask); + sock = unix_listener(fwd->listen_path, SSH_LISTEN_BACKLOG, + fwd_opts->streamlocal_bind_unlink); + umask(omask); + if (sock < 0) + return 0; + + debug("Local forwarding listening on path %s.", fwd->listen_path); + + /* Allocate a channel number for the socket. */ + c = channel_new(ssh, "unix listener", type, sock, sock, -1, + CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, + 0, "unix listener", 1); + c->path = xstrdup(path); + c->host_port = port; + c->listening_port = PORT_STREAMLOCAL; + c->listening_addr = xstrdup(fwd->listen_path); + return 1; +} + +static int +channel_cancel_rport_listener_tcpip(struct ssh *ssh, + const char *host, u_short port) +{ + u_int i; + int found = 0; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + Channel *c = ssh->chanctxt->channels[i]; + if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER) + continue; + if (strcmp(c->path, host) == 0 && c->listening_port == port) { + debug2("%s: close channel %d", __func__, i); + channel_free(ssh, c); + found = 1; + } + } + + return found; +} + +static int +channel_cancel_rport_listener_streamlocal(struct ssh *ssh, const char *path) +{ + u_int i; + int found = 0; + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + Channel *c = ssh->chanctxt->channels[i]; + if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER) + continue; + if (c->path == NULL) + continue; + if (strcmp(c->path, path) == 0) { + debug2("%s: close channel %d", __func__, i); + channel_free(ssh, c); + found = 1; + } + } + + return found; +} + +int +channel_cancel_rport_listener(struct ssh *ssh, struct Forward *fwd) +{ + if (fwd->listen_path != NULL) { + return channel_cancel_rport_listener_streamlocal(ssh, + fwd->listen_path); + } else { + return channel_cancel_rport_listener_tcpip(ssh, + fwd->listen_host, fwd->listen_port); + } +} + +static int +channel_cancel_lport_listener_tcpip(struct ssh *ssh, + const char *lhost, u_short lport, int cport, + struct ForwardOptions *fwd_opts) +{ + u_int i; + int found = 0; + const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, fwd_opts); + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + Channel *c = ssh->chanctxt->channels[i]; + if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER) + continue; + if (c->listening_port != lport) + continue; + if (cport == CHANNEL_CANCEL_PORT_STATIC) { + /* skip dynamic forwardings */ + if (c->host_port == 0) + continue; + } else { + if (c->host_port != cport) + continue; + } + if ((c->listening_addr == NULL && addr != NULL) || + (c->listening_addr != NULL && addr == NULL)) + continue; + if (addr == NULL || strcmp(c->listening_addr, addr) == 0) { + debug2("%s: close channel %d", __func__, i); + channel_free(ssh, c); + found = 1; + } + } + + return found; +} + +static int +channel_cancel_lport_listener_streamlocal(struct ssh *ssh, const char *path) +{ + u_int i; + int found = 0; + + if (path == NULL) { + error("%s: no path specified.", __func__); + return 0; + } + + for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { + Channel *c = ssh->chanctxt->channels[i]; + if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER) + continue; + if (c->listening_addr == NULL) + continue; + if (strcmp(c->listening_addr, path) == 0) { + debug2("%s: close channel %d", __func__, i); + channel_free(ssh, c); + found = 1; + } + } + + return found; +} + +int +channel_cancel_lport_listener(struct ssh *ssh, + struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts) +{ + if (fwd->listen_path != NULL) { + return channel_cancel_lport_listener_streamlocal(ssh, + fwd->listen_path); + } else { + return channel_cancel_lport_listener_tcpip(ssh, + fwd->listen_host, fwd->listen_port, cport, fwd_opts); + } +} + +/* protocol local port fwd, used by ssh */ +int +channel_setup_local_fwd_listener(struct ssh *ssh, + struct Forward *fwd, struct ForwardOptions *fwd_opts) +{ + if (fwd->listen_path != NULL) { + return channel_setup_fwd_listener_streamlocal(ssh, + SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts); + } else { + return channel_setup_fwd_listener_tcpip(ssh, + SSH_CHANNEL_PORT_LISTENER, fwd, NULL, fwd_opts); + } +} + +/* Matches a remote forwarding permission against a requested forwarding */ +static int +remote_open_match(struct permission *allowed_open, struct Forward *fwd) +{ + int ret; + char *lhost; + + /* XXX add ACLs for streamlocal */ + if (fwd->listen_path != NULL) + return 1; + + if (fwd->listen_host == NULL || allowed_open->listen_host == NULL) + return 0; + + if (allowed_open->listen_port != FWD_PERMIT_ANY_PORT && + allowed_open->listen_port != fwd->listen_port) + return 0; + + /* Match hostnames case-insensitively */ + lhost = xstrdup(fwd->listen_host); + lowercase(lhost); + ret = match_pattern(lhost, allowed_open->listen_host); + free(lhost); + + return ret; +} + +/* Checks whether a requested remote forwarding is permitted */ +static int +check_rfwd_permission(struct ssh *ssh, struct Forward *fwd) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->remote_perms; + u_int i, permit, permit_adm = 1; + struct permission *perm; + + /* XXX apply GatewayPorts override before checking? */ + + permit = pset->all_permitted; + if (!permit) { + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (remote_open_match(perm, fwd)) { + permit = 1; + break; + } + } + } + + if (pset->num_permitted_admin > 0) { + permit_adm = 0; + for (i = 0; i < pset->num_permitted_admin; i++) { + perm = &pset->permitted_admin[i]; + if (remote_open_match(perm, fwd)) { + permit_adm = 1; + break; + } + } + } + + return permit && permit_adm; +} + +/* protocol v2 remote port fwd, used by sshd */ +int +channel_setup_remote_fwd_listener(struct ssh *ssh, struct Forward *fwd, + int *allocated_listen_port, struct ForwardOptions *fwd_opts) +{ + if (!check_rfwd_permission(ssh, fwd)) { + packet_send_debug("port forwarding refused"); + return 0; + } + if (fwd->listen_path != NULL) { + return channel_setup_fwd_listener_streamlocal(ssh, + SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts); + } else { + return channel_setup_fwd_listener_tcpip(ssh, + SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port, + fwd_opts); + } +} + +/* + * Translate the requested rfwd listen host to something usable for + * this server. + */ +static const char * +channel_rfwd_bind_host(const char *listen_host) +{ + if (listen_host == NULL) { + return "localhost"; + } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) { + return ""; + } else + return listen_host; +} + +/* + * Initiate forwarding of connections to port "port" on remote host through + * the secure channel to host:port from local side. + * Returns handle (index) for updating the dynamic listen port with + * channel_update_permission(). + */ +int +channel_request_remote_forwarding(struct ssh *ssh, struct Forward *fwd) +{ + int r, success = 0, idx = -1; + char *host_to_connect, *listen_host, *listen_path; + int port_to_connect, listen_port; + + /* Send the forward request to the remote side. */ + if (fwd->listen_path != NULL) { + if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || + (r = sshpkt_put_cstring(ssh, + "streamlocal-forward@openssh.com")) != 0 || + (r = sshpkt_put_u8(ssh, 1)) != 0 || /* want reply */ + (r = sshpkt_put_cstring(ssh, fwd->listen_path)) != 0 || + (r = sshpkt_send(ssh)) != 0 || + (r = ssh_packet_write_wait(ssh)) != 0) + fatal("%s: request streamlocal: %s", + __func__, ssh_err(r)); + } else { + if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || + (r = sshpkt_put_cstring(ssh, "tcpip-forward")) != 0 || + (r = sshpkt_put_u8(ssh, 1)) != 0 || /* want reply */ + (r = sshpkt_put_cstring(ssh, + channel_rfwd_bind_host(fwd->listen_host))) != 0 || + (r = sshpkt_put_u32(ssh, fwd->listen_port)) != 0 || + (r = sshpkt_send(ssh)) != 0 || + (r = ssh_packet_write_wait(ssh)) != 0) + fatal("%s: request tcpip-forward: %s", + __func__, ssh_err(r)); + } + /* Assume that server accepts the request */ + success = 1; + if (success) { + /* Record that connection to this host/port is permitted. */ + host_to_connect = listen_host = listen_path = NULL; + port_to_connect = listen_port = 0; + if (fwd->connect_path != NULL) { + host_to_connect = xstrdup(fwd->connect_path); + port_to_connect = PORT_STREAMLOCAL; + } else { + host_to_connect = xstrdup(fwd->connect_host); + port_to_connect = fwd->connect_port; + } + if (fwd->listen_path != NULL) { + listen_path = xstrdup(fwd->listen_path); + listen_port = PORT_STREAMLOCAL; + } else { + if (fwd->listen_host != NULL) + listen_host = xstrdup(fwd->listen_host); + listen_port = fwd->listen_port; + } + idx = permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL, + host_to_connect, port_to_connect, + listen_host, listen_path, listen_port, NULL); + } + return idx; +} + +static int +open_match(struct permission *allowed_open, const char *requestedhost, + int requestedport) +{ + if (allowed_open->host_to_connect == NULL) + return 0; + if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT && + allowed_open->port_to_connect != requestedport) + return 0; + if (strcmp(allowed_open->host_to_connect, FWD_PERMIT_ANY_HOST) != 0 && + strcmp(allowed_open->host_to_connect, requestedhost) != 0) + return 0; + return 1; +} + +/* + * Note that in the listen host/port case + * we don't support FWD_PERMIT_ANY_PORT and + * need to translate between the configured-host (listen_host) + * and what we've sent to the remote server (channel_rfwd_bind_host) + */ +static int +open_listen_match_tcpip(struct permission *allowed_open, + const char *requestedhost, u_short requestedport, int translate) +{ + const char *allowed_host; + + if (allowed_open->host_to_connect == NULL) + return 0; + if (allowed_open->listen_port != requestedport) + return 0; + if (!translate && allowed_open->listen_host == NULL && + requestedhost == NULL) + return 1; + allowed_host = translate ? + channel_rfwd_bind_host(allowed_open->listen_host) : + allowed_open->listen_host; + if (allowed_host == NULL || requestedhost == NULL || + strcmp(allowed_host, requestedhost) != 0) + return 0; + return 1; +} + +static int +open_listen_match_streamlocal(struct permission *allowed_open, + const char *requestedpath) +{ + if (allowed_open->host_to_connect == NULL) + return 0; + if (allowed_open->listen_port != PORT_STREAMLOCAL) + return 0; + if (allowed_open->listen_path == NULL || + strcmp(allowed_open->listen_path, requestedpath) != 0) + return 0; + return 1; +} + +/* + * Request cancellation of remote forwarding of connection host:port from + * local side. + */ +static int +channel_request_rforward_cancel_tcpip(struct ssh *ssh, + const char *host, u_short port) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->local_perms; + int r; + u_int i; + struct permission *perm; + + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (open_listen_match_tcpip(perm, host, port, 0)) + break; + perm = NULL; + } + if (perm == NULL) { + debug("%s: requested forward not found", __func__); + return -1; + } + if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || + (r = sshpkt_put_cstring(ssh, "cancel-tcpip-forward")) != 0 || + (r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */ + (r = sshpkt_put_cstring(ssh, channel_rfwd_bind_host(host))) != 0 || + (r = sshpkt_put_u32(ssh, port)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("%s: send cancel: %s", __func__, ssh_err(r)); + + fwd_perm_clear(perm); /* unregister */ + + return 0; +} + +/* + * Request cancellation of remote forwarding of Unix domain socket + * path from local side. + */ +static int +channel_request_rforward_cancel_streamlocal(struct ssh *ssh, const char *path) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->local_perms; + int r; + u_int i; + struct permission *perm; + + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (open_listen_match_streamlocal(perm, path)) + break; + perm = NULL; + } + if (perm == NULL) { + debug("%s: requested forward not found", __func__); + return -1; + } + if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || + (r = sshpkt_put_cstring(ssh, + "cancel-streamlocal-forward@openssh.com")) != 0 || + (r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */ + (r = sshpkt_put_cstring(ssh, path)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("%s: send cancel: %s", __func__, ssh_err(r)); + + fwd_perm_clear(perm); /* unregister */ + + return 0; +} + +/* + * Request cancellation of remote forwarding of a connection from local side. + */ +int +channel_request_rforward_cancel(struct ssh *ssh, struct Forward *fwd) +{ + if (fwd->listen_path != NULL) { + return channel_request_rforward_cancel_streamlocal(ssh, + fwd->listen_path); + } else { + return channel_request_rforward_cancel_tcpip(ssh, + fwd->listen_host, + fwd->listen_port ? fwd->listen_port : fwd->allocated_port); + } +} + +/* + * Permits opening to any host/port if permitted_user[] is empty. This is + * usually called by the server, because the user could connect to any port + * anyway, and the server has no way to know but to trust the client anyway. + */ +void +channel_permit_all(struct ssh *ssh, int where) +{ + struct permission_set *pset = permission_set_get(ssh, where); + + if (pset->num_permitted_user == 0) + pset->all_permitted = 1; +} + +/* + * Permit the specified host/port for forwarding. + */ +void +channel_add_permission(struct ssh *ssh, int who, int where, + char *host, int port) +{ + int local = where == FORWARD_LOCAL; + struct permission_set *pset = permission_set_get(ssh, where); + + debug("allow %s forwarding to host %s port %d", + fwd_ident(who, where), host, port); + /* + * Remote forwards set listen_host/port, local forwards set + * host/port_to_connect. + */ + permission_set_add(ssh, who, where, + local ? host : 0, local ? port : 0, + local ? NULL : host, NULL, local ? 0 : port, NULL); + pset->all_permitted = 0; +} + +/* + * Administratively disable forwarding. + */ +void +channel_disable_admin(struct ssh *ssh, int where) +{ + channel_clear_permission(ssh, FORWARD_ADM, where); + permission_set_add(ssh, FORWARD_ADM, where, + NULL, 0, NULL, NULL, 0, NULL); +} + +/* + * Clear a list of permitted opens. + */ +void +channel_clear_permission(struct ssh *ssh, int who, int where) +{ + struct permission **permp; + u_int *npermp; + + permission_set_get_array(ssh, who, where, &permp, &npermp); + *permp = xrecallocarray(*permp, *npermp, 0, sizeof(**permp)); + *npermp = 0; +} + +/* + * Update the listen port for a dynamic remote forward, after + * the actual 'newport' has been allocated. If 'newport' < 0 is + * passed then they entry will be invalidated. + */ +void +channel_update_permission(struct ssh *ssh, int idx, int newport) +{ + struct permission_set *pset = &ssh->chanctxt->local_perms; + + if (idx < 0 || (u_int)idx >= pset->num_permitted_user) { + debug("%s: index out of range: %d num_permitted_user %d", + __func__, idx, pset->num_permitted_user); + return; + } + debug("%s allowed port %d for forwarding to host %s port %d", + newport > 0 ? "Updating" : "Removing", + newport, + pset->permitted_user[idx].host_to_connect, + pset->permitted_user[idx].port_to_connect); + if (newport <= 0) + fwd_perm_clear(&pset->permitted_user[idx]); + else { + pset->permitted_user[idx].listen_port = + (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport; + } +} + +/* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */ +int +permitopen_port(const char *p) +{ + int port; + + if (strcmp(p, "*") == 0) + return FWD_PERMIT_ANY_PORT; + if ((port = a2port(p)) > 0) + return port; + return -1; +} + +/* Try to start non-blocking connect to next host in cctx list */ +static int +connect_next(struct channel_connect *cctx) +{ + int sock, saved_errno; + struct sockaddr_un *sunaddr; + char ntop[NI_MAXHOST]; + char strport[MAXIMUM(NI_MAXSERV, sizeof(sunaddr->sun_path))]; + + for (; cctx->ai; cctx->ai = cctx->ai->ai_next) { + switch (cctx->ai->ai_family) { + case AF_UNIX: + /* unix:pathname instead of host:port */ + sunaddr = (struct sockaddr_un *)cctx->ai->ai_addr; + strlcpy(ntop, "unix", sizeof(ntop)); + strlcpy(strport, sunaddr->sun_path, sizeof(strport)); + break; + case AF_INET: + case AF_INET6: + if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen, + ntop, sizeof(ntop), strport, sizeof(strport), + NI_NUMERICHOST|NI_NUMERICSERV) != 0) { + error("connect_next: getnameinfo failed"); + continue; + } + break; + default: + continue; + } + if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype, + cctx->ai->ai_protocol)) == -1) { + if (cctx->ai->ai_next == NULL) + error("socket: %.100s", strerror(errno)); + else + verbose("socket: %.100s", strerror(errno)); + continue; + } + if (set_nonblock(sock) == -1) + fatal("%s: set_nonblock(%d)", __func__, sock); + if (connect(sock, cctx->ai->ai_addr, + cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) { + debug("connect_next: host %.100s ([%.100s]:%s): " + "%.100s", cctx->host, ntop, strport, + strerror(errno)); + saved_errno = errno; + close(sock); + errno = saved_errno; + continue; /* fail -- try next */ + } + if (cctx->ai->ai_family != AF_UNIX) + set_nodelay(sock); + debug("connect_next: host %.100s ([%.100s]:%s) " + "in progress, fd=%d", cctx->host, ntop, strport, sock); + cctx->ai = cctx->ai->ai_next; + return sock; + } + return -1; +} + +static void +channel_connect_ctx_free(struct channel_connect *cctx) +{ + free(cctx->host); + if (cctx->aitop) { + if (cctx->aitop->ai_family == AF_UNIX) + free(cctx->aitop); + else + freeaddrinfo(cctx->aitop); + } + memset(cctx, 0, sizeof(*cctx)); +} + +/* + * Return connecting socket to remote host:port or local socket path, + * passing back the failure reason if appropriate. + */ +static int +connect_to_helper(struct ssh *ssh, const char *name, int port, int socktype, + char *ctype, char *rname, struct channel_connect *cctx, + int *reason, const char **errmsg) +{ + struct addrinfo hints; + int gaierr; + int sock = -1; + char strport[NI_MAXSERV]; + + if (port == PORT_STREAMLOCAL) { + struct sockaddr_un *sunaddr; + struct addrinfo *ai; + + if (strlen(name) > sizeof(sunaddr->sun_path)) { + error("%.100s: %.100s", name, strerror(ENAMETOOLONG)); + return -1; + } + + /* + * Fake up a struct addrinfo for AF_UNIX connections. + * channel_connect_ctx_free() must check ai_family + * and use free() not freeaddirinfo() for AF_UNIX. + */ + ai = xmalloc(sizeof(*ai) + sizeof(*sunaddr)); + memset(ai, 0, sizeof(*ai) + sizeof(*sunaddr)); + ai->ai_addr = (struct sockaddr *)(ai + 1); + ai->ai_addrlen = sizeof(*sunaddr); + ai->ai_family = AF_UNIX; + ai->ai_socktype = socktype; + ai->ai_protocol = PF_UNSPEC; + sunaddr = (struct sockaddr_un *)ai->ai_addr; + sunaddr->sun_family = AF_UNIX; + strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path)); + cctx->aitop = ai; + } else { + memset(&hints, 0, sizeof(hints)); + hints.ai_family = ssh->chanctxt->IPv4or6; + hints.ai_socktype = socktype; + snprintf(strport, sizeof strport, "%d", port); + if ((gaierr = getaddrinfo(name, strport, &hints, &cctx->aitop)) + != 0) { + if (errmsg != NULL) + *errmsg = ssh_gai_strerror(gaierr); + if (reason != NULL) + *reason = SSH2_OPEN_CONNECT_FAILED; + error("connect_to %.100s: unknown host (%s)", name, + ssh_gai_strerror(gaierr)); + return -1; + } + } + + cctx->host = xstrdup(name); + cctx->port = port; + cctx->ai = cctx->aitop; + + if ((sock = connect_next(cctx)) == -1) { + error("connect to %.100s port %d failed: %s", + name, port, strerror(errno)); + return -1; + } + + return sock; +} + +/* Return CONNECTING channel to remote host:port or local socket path */ +static Channel * +connect_to(struct ssh *ssh, const char *host, int port, + char *ctype, char *rname) +{ + struct channel_connect cctx; + Channel *c; + int sock; + + memset(&cctx, 0, sizeof(cctx)); + sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname, + &cctx, NULL, NULL); + if (sock == -1) { + channel_connect_ctx_free(&cctx); + return NULL; + } + c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1, + CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1); + c->host_port = port; + c->path = xstrdup(host); + c->connect_ctx = cctx; + + return c; +} + +/* + * returns either the newly connected channel or the downstream channel + * that needs to deal with this connection. + */ +Channel * +channel_connect_by_listen_address(struct ssh *ssh, const char *listen_host, + u_short listen_port, char *ctype, char *rname) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->local_perms; + u_int i; + struct permission *perm; + + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (open_listen_match_tcpip(perm, + listen_host, listen_port, 1)) { + if (perm->downstream) + return perm->downstream; + if (perm->port_to_connect == 0) + return rdynamic_connect_prepare(ssh, + ctype, rname); + return connect_to(ssh, + perm->host_to_connect, perm->port_to_connect, + ctype, rname); + } + } + error("WARNING: Server requests forwarding for unknown listen_port %d", + listen_port); + return NULL; +} + +Channel * +channel_connect_by_listen_path(struct ssh *ssh, const char *path, + char *ctype, char *rname) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->local_perms; + u_int i; + struct permission *perm; + + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (open_listen_match_streamlocal(perm, path)) { + return connect_to(ssh, + perm->host_to_connect, perm->port_to_connect, + ctype, rname); + } + } + error("WARNING: Server requests forwarding for unknown path %.100s", + path); + return NULL; +} + +/* Check if connecting to that port is permitted and connect. */ +Channel * +channel_connect_to_port(struct ssh *ssh, const char *host, u_short port, + char *ctype, char *rname, int *reason, const char **errmsg) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->local_perms; + struct channel_connect cctx; + Channel *c; + u_int i, permit, permit_adm = 1; + int sock; + struct permission *perm; + + permit = pset->all_permitted; + if (!permit) { + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (open_match(perm, host, port)) { + permit = 1; + break; + } + } + } + + if (pset->num_permitted_admin > 0) { + permit_adm = 0; + for (i = 0; i < pset->num_permitted_admin; i++) { + perm = &pset->permitted_admin[i]; + if (open_match(perm, host, port)) { + permit_adm = 1; + break; + } + } + } + + if (!permit || !permit_adm) { + logit("Received request to connect to host %.100s port %d, " + "but the request was denied.", host, port); + if (reason != NULL) + *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; + return NULL; + } + + memset(&cctx, 0, sizeof(cctx)); + sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname, + &cctx, reason, errmsg); + if (sock == -1) { + channel_connect_ctx_free(&cctx); + return NULL; + } + + c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1, + CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1); + c->host_port = port; + c->path = xstrdup(host); + c->connect_ctx = cctx; + + return c; +} + +/* Check if connecting to that path is permitted and connect. */ +Channel * +channel_connect_to_path(struct ssh *ssh, const char *path, + char *ctype, char *rname) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct permission_set *pset = &sc->local_perms; + u_int i, permit, permit_adm = 1; + struct permission *perm; + + permit = pset->all_permitted; + if (!permit) { + for (i = 0; i < pset->num_permitted_user; i++) { + perm = &pset->permitted_user[i]; + if (open_match(perm, path, PORT_STREAMLOCAL)) { + permit = 1; + break; + } + } + } + + if (pset->num_permitted_admin > 0) { + permit_adm = 0; + for (i = 0; i < pset->num_permitted_admin; i++) { + perm = &pset->permitted_admin[i]; + if (open_match(perm, path, PORT_STREAMLOCAL)) { + permit_adm = 1; + break; + } + } + } + + if (!permit || !permit_adm) { + logit("Received request to connect to path %.100s, " + "but the request was denied.", path); + return NULL; + } + return connect_to(ssh, path, PORT_STREAMLOCAL, ctype, rname); +} + +void +channel_send_window_changes(struct ssh *ssh) +{ + struct ssh_channels *sc = ssh->chanctxt; + struct winsize ws; + int r; + u_int i; + + for (i = 0; i < sc->channels_alloc; i++) { + if (sc->channels[i] == NULL || !sc->channels[i]->client_tty || + sc->channels[i]->type != SSH_CHANNEL_OPEN) + continue; + if (ioctl(sc->channels[i]->rfd, TIOCGWINSZ, &ws) < 0) + continue; + channel_request_start(ssh, i, "window-change", 0); + if ((r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || + (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || + (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || + (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0 || + (r = sshpkt_send(ssh)) != 0) + fatal("%s: channel %u: send window-change: %s", + __func__, i, ssh_err(r)); + } +} + +/* Return RDYNAMIC_OPEN channel: channel allows SOCKS, but is not connected */ +static Channel * +rdynamic_connect_prepare(struct ssh *ssh, char *ctype, char *rname) +{ + Channel *c; + int r; + + c = channel_new(ssh, ctype, SSH_CHANNEL_RDYNAMIC_OPEN, -1, -1, -1, + CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1); + c->host_port = 0; + c->path = NULL; + + /* + * We need to open the channel before we have a FD, + * so that we can get SOCKS header from peer. + */ + if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 || + (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || + (r = sshpkt_put_u32(ssh, c->self)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_window)) != 0 || + (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0) { + fatal("%s: channel %i: confirm: %s", __func__, + c->self, ssh_err(r)); + } + return c; +} + +/* Return CONNECTING socket to remote host:port or local socket path */ +static int +rdynamic_connect_finish(struct ssh *ssh, Channel *c) +{ + struct channel_connect cctx; + int sock; + + memset(&cctx, 0, sizeof(cctx)); + sock = connect_to_helper(ssh, c->path, c->host_port, SOCK_STREAM, NULL, + NULL, &cctx, NULL, NULL); + if (sock == -1) + channel_connect_ctx_free(&cctx); + else { + /* similar to SSH_CHANNEL_CONNECTING but we've already sent the open */ + c->type = SSH_CHANNEL_RDYNAMIC_FINISH; + c->connect_ctx = cctx; + channel_register_fds(ssh, c, sock, sock, -1, 0, 1, 0); + } + return sock; +} + +/* -- X11 forwarding */ + +/* + * Creates an internet domain socket for listening for X11 connections. + * Returns 0 and a suitable display number for the DISPLAY variable + * stored in display_numberp , or -1 if an error occurs. + */ +int +x11_create_display_inet(struct ssh *ssh, int x11_display_offset, + int x11_use_localhost, int single_connection, + u_int *display_numberp, int **chanids) +{ + Channel *nc = NULL; + int display_number, sock; + u_short port; + struct addrinfo hints, *ai, *aitop; + char strport[NI_MAXSERV]; + int gaierr, n, num_socks = 0, socks[NUM_SOCKS]; + + if (chanids == NULL) + return -1; + + for (display_number = x11_display_offset; + display_number < MAX_DISPLAYS; + display_number++) { + port = 6000 + display_number; + memset(&hints, 0, sizeof(hints)); + hints.ai_family = ssh->chanctxt->IPv4or6; + hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE; + hints.ai_socktype = SOCK_STREAM; + snprintf(strport, sizeof strport, "%d", port); + if ((gaierr = getaddrinfo(NULL, strport, + &hints, &aitop)) != 0) { + error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr)); + return -1; + } + for (ai = aitop; ai; ai = ai->ai_next) { + if (ai->ai_family != AF_INET && + ai->ai_family != AF_INET6) + continue; + sock = socket(ai->ai_family, ai->ai_socktype, + ai->ai_protocol); + if (sock < 0) { + if ((errno != EINVAL) && (errno != EAFNOSUPPORT) +#ifdef EPFNOSUPPORT + && (errno != EPFNOSUPPORT) +#endif + ) { + error("socket: %.100s", strerror(errno)); + freeaddrinfo(aitop); + return -1; + } else { + debug("x11_create_display_inet: Socket family %d not supported", + ai->ai_family); + continue; + } + } + if (ai->ai_family == AF_INET6) + sock_set_v6only(sock); + if (x11_use_localhost) + set_reuseaddr(sock); + if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) { + debug2("%s: bind port %d: %.100s", __func__, + port, strerror(errno)); + close(sock); + for (n = 0; n < num_socks; n++) + close(socks[n]); + num_socks = 0; + break; + } + socks[num_socks++] = sock; + if (num_socks == NUM_SOCKS) + break; + } + freeaddrinfo(aitop); + if (num_socks > 0) + break; + } + if (display_number >= MAX_DISPLAYS) { + error("Failed to allocate internet-domain X11 display socket."); + return -1; + } + /* Start listening for connections on the socket. */ + for (n = 0; n < num_socks; n++) { + sock = socks[n]; + if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { + error("listen: %.100s", strerror(errno)); + close(sock); + return -1; + } + } + + /* Allocate a channel for each socket. */ + *chanids = xcalloc(num_socks + 1, sizeof(**chanids)); + for (n = 0; n < num_socks; n++) { + sock = socks[n]; + nc = channel_new(ssh, "x11 listener", + SSH_CHANNEL_X11_LISTENER, sock, sock, -1, + CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, + 0, "X11 inet listener", 1); + nc->single_connection = single_connection; + (*chanids)[n] = nc->self; + } + (*chanids)[n] = -1; + + /* Return the display number for the DISPLAY environment variable. */ + *display_numberp = display_number; + return 0; +} + +static int +connect_local_xsocket_path(const char *pathname) +{ + int sock; + struct sockaddr_un addr; + + sock = socket(AF_UNIX, SOCK_STREAM, 0); + if (sock < 0) + error("socket: %.100s", strerror(errno)); + memset(&addr, 0, sizeof(addr)); + addr.sun_family = AF_UNIX; + strlcpy(addr.sun_path, pathname, sizeof addr.sun_path); + if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0) + return sock; + close(sock); + error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); + return -1; +} + +static int +connect_local_xsocket(u_int dnr) +{ + char buf[1024]; + snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr); + return connect_local_xsocket_path(buf); +} + +#ifdef __APPLE__ +static int +is_path_to_xsocket(const char *display, char *path, size_t pathlen) +{ + struct stat sbuf; + + if (strlcpy(path, display, pathlen) >= pathlen) { + error("%s: display path too long", __func__); + return 0; + } + if (display[0] != '/') + return 0; + if (stat(path, &sbuf) == 0) { + return 1; + } else { + char *dot = strrchr(path, '.'); + if (dot != NULL) { + *dot = '\0'; + if (stat(path, &sbuf) == 0) { + return 1; + } + } + } + return 0; +} +#endif + +int +x11_connect_display(struct ssh *ssh) +{ + u_int display_number; + const char *display; + char buf[1024], *cp; + struct addrinfo hints, *ai, *aitop; + char strport[NI_MAXSERV]; + int gaierr, sock = 0; + + /* Try to open a socket for the local X server. */ + display = getenv("DISPLAY"); + if (!display) { + error("DISPLAY not set."); + return -1; + } + /* + * Now we decode the value of the DISPLAY variable and make a + * connection to the real X server. + */ + +#ifdef __APPLE__ + /* Check if display is a path to a socket (as set by launchd). */ + { + char path[PATH_MAX]; + + if (is_path_to_xsocket(display, path, sizeof(path))) { + debug("x11_connect_display: $DISPLAY is launchd"); + + /* Create a socket. */ + sock = connect_local_xsocket_path(path); + if (sock < 0) + return -1; + + /* OK, we now have a connection to the display. */ + return sock; + } + } +#endif + /* + * Check if it is a unix domain socket. Unix domain displays are in + * one of the following formats: unix:d[.s], :d[.s], ::d[.s] + */ + if (strncmp(display, "unix:", 5) == 0 || + display[0] == ':') { + /* Connect to the unix domain socket. */ + if (sscanf(strrchr(display, ':') + 1, "%u", + &display_number) != 1) { + error("Could not parse display number from DISPLAY: " + "%.100s", display); + return -1; + } + /* Create a socket. */ + sock = connect_local_xsocket(display_number); + if (sock < 0) + return -1; + + /* OK, we now have a connection to the display. */ + return sock; + } + /* + * Connect to an inet socket. The DISPLAY value is supposedly + * hostname:d[.s], where hostname may also be numeric IP address. + */ + strlcpy(buf, display, sizeof(buf)); + cp = strchr(buf, ':'); + if (!cp) { + error("Could not find ':' in DISPLAY: %.100s", display); + return -1; + } + *cp = 0; + /* + * buf now contains the host name. But first we parse the + * display number. + */ + if (sscanf(cp + 1, "%u", &display_number) != 1) { + error("Could not parse display number from DISPLAY: %.100s", + display); + return -1; + } + + /* Look up the host address */ + memset(&hints, 0, sizeof(hints)); + hints.ai_family = ssh->chanctxt->IPv4or6; + hints.ai_socktype = SOCK_STREAM; + snprintf(strport, sizeof strport, "%u", 6000 + display_number); + if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) { + error("%.100s: unknown host. (%s)", buf, + ssh_gai_strerror(gaierr)); + return -1; + } + for (ai = aitop; ai; ai = ai->ai_next) { + /* Create a socket. */ + sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); + if (sock < 0) { + debug2("socket: %.100s", strerror(errno)); + continue; + } + /* Connect it to the display. */ + if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) { + debug2("connect %.100s port %u: %.100s", buf, + 6000 + display_number, strerror(errno)); + close(sock); + continue; + } + /* Success */ + break; + } + freeaddrinfo(aitop); + if (!ai) { + error("connect %.100s port %u: %.100s", buf, + 6000 + display_number, strerror(errno)); + return -1; + } + set_nodelay(sock); + return sock; +} + +/* + * Requests forwarding of X11 connections, generates fake authentication + * data, and enables authentication spoofing. + * This should be called in the client only. + */ +void +x11_request_forwarding_with_spoofing(struct ssh *ssh, int client_session_id, + const char *disp, const char *proto, const char *data, int want_reply) +{ + struct ssh_channels *sc = ssh->chanctxt; + u_int data_len = (u_int) strlen(data) / 2; + u_int i, value; + const char *cp; + char *new_data; + int r, screen_number; + + if (sc->x11_saved_display == NULL) + sc->x11_saved_display = xstrdup(disp); + else if (strcmp(disp, sc->x11_saved_display) != 0) { + error("x11_request_forwarding_with_spoofing: different " + "$DISPLAY already forwarded"); + return; + } + + cp = strchr(disp, ':'); + if (cp) + cp = strchr(cp, '.'); + if (cp) + screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL); + else + screen_number = 0; + + if (sc->x11_saved_proto == NULL) { + /* Save protocol name. */ + sc->x11_saved_proto = xstrdup(proto); + + /* Extract real authentication data. */ + sc->x11_saved_data = xmalloc(data_len); + for (i = 0; i < data_len; i++) { + if (sscanf(data + 2 * i, "%2x", &value) != 1) + fatal("x11_request_forwarding: bad " + "authentication data: %.100s", data); + sc->x11_saved_data[i] = value; + } + sc->x11_saved_data_len = data_len; + + /* Generate fake data of the same length. */ + sc->x11_fake_data = xmalloc(data_len); + arc4random_buf(sc->x11_fake_data, data_len); + sc->x11_fake_data_len = data_len; + } + + /* Convert the fake data into hex. */ + new_data = tohex(sc->x11_fake_data, data_len); + + /* Send the request packet. */ + channel_request_start(ssh, client_session_id, "x11-req", want_reply); + if ((r = sshpkt_put_u8(ssh, 0)) != 0 || /* bool: single connection */ + (r = sshpkt_put_cstring(ssh, proto)) != 0 || + (r = sshpkt_put_cstring(ssh, new_data)) != 0 || + (r = sshpkt_put_u32(ssh, screen_number)) != 0 || + (r = sshpkt_send(ssh)) != 0 || + (r = ssh_packet_write_wait(ssh)) != 0) + fatal("%s: send x11-req: %s", __func__, ssh_err(r)); + free(new_data); +} |