/* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , 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" RCSID("$OpenBSD: channels.c,v 1.171 2002/03/04 19:37:58 markus Exp $"); #include "ssh.h" #include "ssh1.h" #include "ssh2.h" #include "packet.h" #include "xmalloc.h" #include "uidswap.h" #include "log.h" #include "misc.h" #include "channels.h" #include "compat.h" #include "canohost.h" #include "key.h" #include "authfd.h" #include "pathnames.h" /* -- channel core */ /* * Pointer to an array containing all allocated channels. The array is * dynamically extended as needed. */ static Channel **channels = NULL; /* * Size of the channel array. All slots of the array must always be * initialized (at least the type field); unused slots set to NULL */ static int channels_alloc = 0; /* * Maximum file descriptor value used in any of the channels. This is * updated in channel_new. */ static int channel_max_fd = 0; /* -- tcp forwarding */ /* * 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). */ typedef struct { char *host_to_connect; /* Connect to 'host'. */ u_short port_to_connect; /* Connect to 'port'. */ u_short listen_port; /* Remote side should listen port number. */ } ForwardPermission; /* List of all permitted host/port pairs to connect. */ static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION]; /* Number of permitted host/port pairs in the array. */ static int num_permitted_opens = 0; /* * If this is true, all opens 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 anyway. */ static int all_opens_permitted = 0; /* -- X11 forwarding */ /* Maximum number of fake X11 displays to try. */ #define MAX_DISPLAYS 1000 /* Saved X11 authentication protocol name. */ static char *x11_saved_proto = NULL; /* Saved X11 authentication data. This is the real data. */ static char *x11_saved_data = NULL; static u_int x11_saved_data_len = 0; /* * Fake X11 authentication data. This is what the server will be sending us; * we should replace any occurrences of this by the real data. */ static char *x11_fake_data = NULL; static u_int x11_fake_data_len; /* -- agent forwarding */ #define NUM_SOCKS 10 /* Name and directory of socket for authentication agent forwarding. */ static char *auth_sock_name = NULL; static char *auth_sock_dir = NULL; /* AF_UNSPEC or AF_INET or AF_INET6 */ static int IPv4or6 = AF_UNSPEC; /* helper */ static void port_open_helper(Channel *c, char *rtype); /* -- channel core */ Channel * channel_lookup(int id) { Channel *c; if (id < 0 || id >= channels_alloc) { log("channel_lookup: %d: bad id", id); return NULL; } c = channels[id]; if (c == NULL) { log("channel_lookup: %d: bad id: channel free", id); return NULL; } return c; } /* * 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(Channel *c, int rfd, int wfd, int efd, int extusage, int nonblock) { /* Update the maximum file descriptor value. */ channel_max_fd = MAX(channel_max_fd, rfd); channel_max_fd = MAX(channel_max_fd, wfd); channel_max_fd = MAX(channel_max_fd, efd); /* XXX set close-on-exec -markus */ c->rfd = rfd; c->wfd = wfd; c->sock = (rfd == wfd) ? rfd : -1; c->efd = efd; c->extended_usage = extusage; /* XXX ugly hack: nonblock is only set by the server */ if (nonblock && isatty(c->rfd)) { debug("channel %d: rfd %d isatty", c->self, c->rfd); c->isatty = 1; if (!isatty(c->wfd)) { error("channel %d: wfd %d is not a tty?", c->self, c->wfd); } } else { c->isatty = 0; } /* 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(char *ctype, int type, int rfd, int wfd, int efd, int window, int maxpack, int extusage, char *remote_name, int nonblock) { int i, found; Channel *c; /* Do initial allocation if this is the first call. */ if (channels_alloc == 0) { channels_alloc = 10; channels = xmalloc(channels_alloc * sizeof(Channel *)); for (i = 0; i < channels_alloc; i++) channels[i] = NULL; fatal_add_cleanup((void (*) (void *)) channel_free_all, NULL); } /* Try to find a free slot where to put the new channel. */ for (found = -1, i = 0; i < channels_alloc; i++) if (channels[i] == NULL) { /* Found a free slot. */ found = i; break; } if (found == -1) { /* There are no free slots. Take last+1 slot and expand the array. */ found = channels_alloc; channels_alloc += 10; debug2("channel: expanding %d", channels_alloc); channels = xrealloc(channels, channels_alloc * sizeof(Channel *)); for (i = found; i < channels_alloc; i++) channels[i] = NULL; } /* Initialize and return new channel. */ c = channels[found] = xmalloc(sizeof(Channel)); memset(c, 0, sizeof(Channel)); buffer_init(&c->input); buffer_init(&c->output); buffer_init(&c->extended); c->ostate = CHAN_OUTPUT_OPEN; c->istate = CHAN_INPUT_OPEN; c->flags = 0; channel_register_fds(c, rfd, wfd, efd, extusage, nonblock); c->self = found; c->type = type; c->ctype = ctype; c->local_window = window; c->local_window_max = window; c->local_consumed = 0; c->local_maxpacket = maxpack; c->remote_id = -1; c->remote_name = remote_name; c->remote_window = 0; c->remote_maxpacket = 0; c->force_drain = 0; c->single_connection = 0; c->detach_user = NULL; c->confirm = NULL; c->input_filter = NULL; debug("channel %d: new [%s]", found, remote_name); return c; } static int channel_find_maxfd(void) { int i, max = 0; Channel *c; for (i = 0; i < channels_alloc; i++) { c = channels[i]; if (c != NULL) { max = MAX(max, c->rfd); max = MAX(max, c->wfd); max = MAX(max, c->efd); } } return max; } int channel_close_fd(int *fdp) { int ret = 0, fd = *fdp; if (fd != -1) { ret = close(fd); *fdp = -1; if (fd == channel_max_fd) channel_max_fd = channel_find_maxfd(); } return ret; } /* Close all channel fd/socket. */ static void channel_close_fds(Channel *c) { debug3("channel_close_fds: channel %d: r %d w %d e %d", c->self, c->rfd, c->wfd, c->efd); channel_close_fd(&c->sock); channel_close_fd(&c->rfd); channel_close_fd(&c->wfd); channel_close_fd(&c->efd); } /* Free the channel and close its fd/socket. */ void channel_free(Channel *c) { char *s; int i, n; for (n = 0, i = 0; i < channels_alloc; i++) if (channels[i]) n++; debug("channel_free: channel %d: %s, nchannels %d", c->self, c->remote_name ? c->remote_name : "???", n); s = channel_open_message(); debug3("channel_free: status: %s", s); xfree(s); if (c->sock != -1) shutdown(c->sock, SHUT_RDWR); channel_close_fds(c); buffer_free(&c->input); buffer_free(&c->output); buffer_free(&c->extended); if (c->remote_name) { xfree(c->remote_name); c->remote_name = NULL; } channels[c->self] = NULL; xfree(c); } void channel_free_all(void) { int i; for (i = 0; i < channels_alloc; i++) if (channels[i] != NULL) channel_free(channels[i]); } /* * Closes the sockets/fds of all channels. This is used to close extra file * descriptors after a fork. */ void channel_close_all(void) { int i; for (i = 0; i < channels_alloc; i++) if (channels[i] != NULL) channel_close_fds(channels[i]); } /* * Stop listening to channels. */ void channel_stop_listening(void) { int i; Channel *c; for (i = 0; i < channels_alloc; i++) { c = 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: channel_close_fd(&c->sock); channel_free(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(void) { u_int i; Channel *c; for (i = 0; i < channels_alloc; i++) { c = channels[i]; if (c != NULL && c->type == SSH_CHANNEL_OPEN) { #if 0 if (!compat20 && buffer_len(&c->input) > packet_get_maxsize()) { debug("channel %d: big input buffer %d", c->self, buffer_len(&c->input)); return 0; } #endif if (buffer_len(&c->output) > packet_get_maxsize()) { debug("channel %d: big output buffer %d > %d", c->self, buffer_len(&c->output), packet_get_maxsize()); return 0; } } } return 1; } /* Returns true if any channel is still open. */ int channel_still_open(void) { int i; Channel *c; for (i = 0; i < channels_alloc; i++) { c = 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_DYNAMIC: case SSH_CHANNEL_CONNECTING: case SSH_CHANNEL_ZOMBIE: continue; case SSH_CHANNEL_LARVAL: if (!compat20) fatal("cannot happen: SSH_CHANNEL_LARVAL"); continue; case SSH_CHANNEL_OPENING: case SSH_CHANNEL_OPEN: case SSH_CHANNEL_X11_OPEN: return 1; case SSH_CHANNEL_INPUT_DRAINING: case SSH_CHANNEL_OUTPUT_DRAINING: if (!compat13) fatal("cannot happen: OUT_DRAIN"); return 1; default: fatal("channel_still_open: bad channel type %d", c->type); /* NOTREACHED */ } } return 0; } /* Returns the id of an open channel suitable for keepaliving */ int channel_find_open(void) { int i; Channel *c; for (i = 0; i < channels_alloc; i++) { c = channels[i]; if (c == NULL) continue; switch (c->type) { case SSH_CHANNEL_CLOSED: case SSH_CHANNEL_DYNAMIC: case SSH_CHANNEL_X11_LISTENER: case SSH_CHANNEL_PORT_LISTENER: case SSH_CHANNEL_RPORT_LISTENER: case SSH_CHANNEL_OPENING: case SSH_CHANNEL_CONNECTING: case SSH_CHANNEL_ZOMBIE: continue; case SSH_CHANNEL_LARVAL: case SSH_CHANNEL_AUTH_SOCKET: case SSH_CHANNEL_OPEN: case SSH_CHANNEL_X11_OPEN: return i; case SSH_CHANNEL_INPUT_DRAINING: case SSH_CHANNEL_OUTPUT_DRAINING: if (!compat13) fatal("cannot happen: OUT_DRAIN"); return i; default: fatal("channel_find_open: bad channel type %d", c->type); /* NOTREACHED */ } } return -1; } /* * 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(void) { Buffer buffer; Channel *c; char buf[1024], *cp; int i; buffer_init(&buffer); snprintf(buf, sizeof buf, "The following connections are open:\r\n"); buffer_append(&buffer, buf, strlen(buf)); for (i = 0; i < channels_alloc; i++) { c = 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: continue; case SSH_CHANNEL_LARVAL: case SSH_CHANNEL_OPENING: case SSH_CHANNEL_CONNECTING: case SSH_CHANNEL_DYNAMIC: case SSH_CHANNEL_OPEN: case SSH_CHANNEL_X11_OPEN: case SSH_CHANNEL_INPUT_DRAINING: case SSH_CHANNEL_OUTPUT_DRAINING: snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n", c->self, c->remote_name, c->type, c->remote_id, c->istate, buffer_len(&c->input), c->ostate, buffer_len(&c->output), c->rfd, c->wfd); buffer_append(&buffer, buf, strlen(buf)); continue; default: fatal("channel_open_message: bad channel type %d", c->type); /* NOTREACHED */ } } buffer_append(&buffer, "\0", 1); cp = xstrdup(buffer_ptr(&buffer)); buffer_free(&buffer); return cp; } void channel_send_open(int id) { Channel *c = channel_lookup(id); if (c == NULL) { log("channel_send_open: %d: bad id", id); return; } debug("send channel open %d", id); packet_start(SSH2_MSG_CHANNEL_OPEN); packet_put_cstring(c->ctype); packet_put_int(c->self); packet_put_int(c->local_window); packet_put_int(c->local_maxpacket); packet_send(); } void channel_request_start(int local_id, char *service, int wantconfirm) { Channel *c = channel_lookup(local_id); if (c == NULL) { log("channel_request_start: %d: unknown channel id", local_id); return; } debug("channel request %d: %s", local_id, service) ; packet_start(SSH2_MSG_CHANNEL_REQUEST); packet_put_int(c->remote_id); packet_put_cstring(service); packet_put_char(wantconfirm); } void channel_register_confirm(int id, channel_callback_fn *fn) { Channel *c = channel_lookup(id); if (c == NULL) { log("channel_register_comfirm: %d: bad id", id); return; } c->confirm = fn; } void channel_register_cleanup(int id, channel_callback_fn *fn) { Channel *c = channel_lookup(id); if (c == NULL) { log("channel_register_cleanup: %d: bad id", id); return; } c->detach_user = fn; } void channel_cancel_cleanup(int id) { Channel *c = channel_lookup(id); if (c == NULL) { log("channel_cancel_cleanup: %d: bad id", id); return; } c->detach_user = NULL; } void channel_register_filter(int id, channel_filter_fn *fn) { Channel *c = channel_lookup(id); if (c == NULL) { log("channel_register_filter: %d: bad id", id); return; } c->input_filter = fn; } void channel_set_fds(int id, int rfd, int wfd, int efd, int extusage, int nonblock, u_int window_max) { Channel *c = channel_lookup(id); if (c == NULL || c->type != SSH_CHANNEL_LARVAL) fatal("channel_activate for non-larval channel %d.", id); channel_register_fds(c, rfd, wfd, efd, extusage, nonblock); c->type = SSH_CHANNEL_OPEN; c->local_window = c->local_window_max = window_max; packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST); packet_put_int(c->remote_id); packet_put_int(c->local_window); packet_send(); } /* * '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. */ typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset); chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE]; chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE]; static void channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset) { FD_SET(c->sock, readset); } static void channel_pre_connecting(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_13(Channel *c, fd_set * readset, fd_set * writeset) { if (buffer_len(&c->input) < packet_get_maxsize()) FD_SET(c->sock, readset); if (buffer_len(&c->output) > 0) FD_SET(c->sock, writeset); } static void channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset) { u_int limit = compat20 ? c->remote_window : packet_get_maxsize(); if (c->istate == CHAN_INPUT_OPEN && limit > 0 && buffer_len(&c->input) < limit) FD_SET(c->rfd, readset); if (c->ostate == CHAN_OUTPUT_OPEN || c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { if (buffer_len(&c->output) > 0) { FD_SET(c->wfd, writeset); } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { chan_obuf_empty(c); } } /** XXX check close conditions, too */ if (compat20 && c->efd != -1) { if (c->extended_usage == CHAN_EXTENDED_WRITE && buffer_len(&c->extended) > 0) FD_SET(c->efd, writeset); else if (c->extended_usage == CHAN_EXTENDED_READ && buffer_len(&c->extended) < c->remote_window) FD_SET(c->efd, readset); } } static void channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset) { if (buffer_len(&c->input) == 0) { packet_start(SSH_MSG_CHANNEL_CLOSE); packet_put_int(c->remote_id); packet_send(); c->type = SSH_CHANNEL_CLOSED; debug("channel %d: closing after input drain.", c->self); } } static void channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset) { if (buffer_len(&c->output) == 0) chan_mark_dead(c); else FD_SET(c->sock, writeset); } /* * 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(Buffer *b) { u_char *ucp; u_int proto_len, data_len; /* Check if the fixed size part of the packet is in buffer. */ if (buffer_len(b) < 12) return 0; /* Parse the lengths of variable-length fields. */ ucp = buffer_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 { debug("Initial X11 packet contains bad byte order byte: 0x%x", ucp[0]); return -1; } /* Check if the whole packet is in buffer. */ if (buffer_len(b) < 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3)) return 0; /* Check if authentication protocol matches. */ if (proto_len != strlen(x11_saved_proto) || memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) { debug("X11 connection uses different authentication protocol."); return -1; } /* Check if authentication data matches our fake data. */ if (data_len != x11_fake_data_len || memcmp(ucp + 12 + ((proto_len + 3) & ~3), x11_fake_data, x11_fake_data_len) != 0) { debug("X11 auth data does not match fake data."); return -1; } /* Check fake data length */ if (x11_fake_data_len != x11_saved_data_len) { error("X11 fake_data_len %d != saved_data_len %d", x11_fake_data_len, 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), x11_saved_data, x11_saved_data_len); return 1; } static void channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset) { int ret = x11_open_helper(&c->output); if (ret == 1) { /* Start normal processing for the channel. */ c->type = SSH_CHANNEL_OPEN; channel_pre_open_13(c, readset, writeset); } else if (ret == -1) { /* * We have received an X11 connection that has bad * authentication information. */ log("X11 connection rejected because of wrong authentication."); buffer_clear(&c->input); buffer_clear(&c->output); channel_close_fd(&c->sock); c->sock = -1; c->type = SSH_CHANNEL_CLOSED; packet_start(SSH_MSG_CHANNEL_CLOSE); packet_put_int(c->remote_id); packet_send(); } } static void channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset) { int ret = x11_open_helper(&c->output); /* c->force_drain = 1; */ if (ret == 1) { c->type = SSH_CHANNEL_OPEN; channel_pre_open(c, readset, writeset); } else if (ret == -1) { log("X11 connection rejected because of wrong authentication."); debug("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate); chan_read_failed(c); buffer_clear(&c->input); chan_ibuf_empty(c); buffer_clear(&c->output); /* for proto v1, the peer will send an IEOF */ if (compat20) chan_write_failed(c); else c->type = SSH_CHANNEL_OPEN; debug("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate); } } /* try to decode a socks4 header */ static int channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset) { u_char *p, *host; int len, have, i, found; 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; debug2("channel %d: decode socks4", c->self); have = buffer_len(&c->input); len = sizeof(s4_req); if (have < len) return 0; p = buffer_ptr(&c->input); for (found = 0, i = len; i < have; i++) { if (p[i] == '\0') { found = 1; break; } if (i > 1024) { /* the peer is probably sending garbage */ debug("channel %d: decode socks4: too long", c->self); return -1; } } if (!found) return 0; buffer_get(&c->input, (char *)&s4_req.version, 1); buffer_get(&c->input, (char *)&s4_req.command, 1); buffer_get(&c->input, (char *)&s4_req.dest_port, 2); buffer_get(&c->input, (char *)&s4_req.dest_addr, 4); have = buffer_len(&c->input); p = buffer_ptr(&c->input); len = strlen(p); debug2("channel %d: decode socks4: user %s/%d", c->self, p, len); if (len > have) fatal("channel %d: decode socks4: len %d > have %d", c->self, len, have); strlcpy(username, p, sizeof(username)); buffer_consume(&c->input, len); buffer_consume(&c->input, 1); /* trailing '\0' */ host = inet_ntoa(s4_req.dest_addr); strlcpy(c->path, host, sizeof(c->path)); c->host_port = ntohs(s4_req.dest_port); debug("channel %d: dynamic request: socks4 host %s port %u command %u", c->self, host, c->host_port, s4_req.command); if (s4_req.command != 1) { debug("channel %d: cannot handle: socks4 cn %d", c->self, 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 */ buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp)); return 1; } /* dynamic port forwarding */ static void channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset) { u_char *p; int have, ret; have = buffer_len(&c->input); c->delayed = 0; debug2("channel %d: pre_dynamic: have %d", c->self, have); /* buffer_dump(&c->input); */ /* check if the fixed size part of the packet is in buffer. */ if (have < 4) { /* need more */ FD_SET(c->sock, readset); return; } /* try to guess the protocol */ p = buffer_ptr(&c->input); switch (p[0]) { case 0x04: ret = channel_decode_socks4(c, readset, writeset); break; default: ret = -1; break; } if (ret < 0) { chan_mark_dead(c); } else if (ret == 0) { debug2("channel %d: pre_dynamic: need more", c->self); /* need more */ FD_SET(c->sock, readset); } else { /* switch to the next state */ c->type = SSH_CHANNEL_OPENING; port_open_helper(c, "direct-tcpip"); } } /* This is our fake X11 server socket. */ static void channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset) { Channel *nc; struct sockaddr addr; int newsock; socklen_t addrlen; char buf[16384], *remote_ipaddr; int remote_port; if (FD_ISSET(c->sock, readset)) { debug("X11 connection requested."); addrlen = sizeof(addr); newsock = accept(c->sock, &addr, &addrlen); if (c->single_connection) { debug("single_connection: closing X11 listener."); channel_close_fd(&c->sock); chan_mark_dead(c); } if (newsock < 0) { error("accept: %.100s", strerror(errno)); 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("accepted x11 socket", SSH_CHANNEL_OPENING, newsock, newsock, -1, c->local_window_max, c->local_maxpacket, 0, xstrdup(buf), 1); if (compat20) { packet_start(SSH2_MSG_CHANNEL_OPEN); packet_put_cstring("x11"); packet_put_int(nc->self); packet_put_int(nc->local_window_max); packet_put_int(nc->local_maxpacket); /* originator ipaddr and port */ packet_put_cstring(remote_ipaddr); if (datafellows & SSH_BUG_X11FWD) { debug("ssh2 x11 bug compat mode"); } else { packet_put_int(remote_port); } packet_send(); } else { packet_start(SSH_SMSG_X11_OPEN); packet_put_int(nc->self); if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) packet_put_cstring(buf); packet_send(); } xfree(remote_ipaddr); } } static void port_open_helper(Channel *c, char *rtype) { int direct; char buf[1024]; char *remote_ipaddr = get_peer_ipaddr(c->sock); u_short remote_port = get_peer_port(c->sock); direct = (strcmp(rtype, "direct-tcpip") == 0); snprintf(buf, sizeof buf, "%s: listening port %d for %.100s port %d, " "connect from %.200s port %d", rtype, c->listening_port, c->path, c->host_port, remote_ipaddr, remote_port); xfree(c->remote_name); c->remote_name = xstrdup(buf); if (compat20) { packet_start(SSH2_MSG_CHANNEL_OPEN); packet_put_cstring(rtype); packet_put_int(c->self); packet_put_int(c->local_window_max); packet_put_int(c->local_maxpacket); if (direct) { /* target host, port */ packet_put_cstring(c->path); packet_put_int(c->host_port); } else { /* listen address, port */ packet_put_cstring(c->path); packet_put_int(c->listening_port); } /* originator host and port */ packet_put_cstring(remote_ipaddr); packet_put_int(remote_port); packet_send(); } else { packet_start(SSH_MSG_PORT_OPEN); packet_put_int(c->self); packet_put_cstring(c->path); packet_put_int(c->host_port); if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) packet_put_cstring(c->remote_name); packet_send(); } xfree(remote_ipaddr); } /* * This socket is listening for connections to a forwarded TCP/IP port. */ static void channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset) { Channel *nc; struct sockaddr addr; int newsock, nextstate; socklen_t addrlen; char *rtype; if (FD_ISSET(c->sock, readset)) { 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->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, &addr, &addrlen); if (newsock < 0) { error("accept: %.100s", strerror(errno)); return; } set_nodelay(newsock); nc = channel_new(rtype, nextstate, newsock, newsock, -1, c->local_window_max, c->local_maxpacket, 0, xstrdup(rtype), 1); nc->listening_port = c->listening_port; nc->host_port = c->host_port; strlcpy(nc->path, c->path, sizeof(nc->path)); if (nextstate == SSH_CHANNEL_DYNAMIC) { /* * do not call the channel_post handler until * this flag has been reset by a pre-handler. * otherwise the FD_ISSET calls might overflow */ nc->delayed = 1; } else { port_open_helper(nc, rtype); } } } /* * This is the authentication agent socket listening for connections from * clients. */ static void channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset) { Channel *nc; char *name; int newsock; struct sockaddr addr; socklen_t addrlen; if (FD_ISSET(c->sock, readset)) { addrlen = sizeof(addr); newsock = accept(c->sock, &addr, &addrlen); if (newsock < 0) { error("accept from auth socket: %.100s", strerror(errno)); return; } name = xstrdup("accepted auth socket"); nc = channel_new("accepted auth socket", SSH_CHANNEL_OPENING, newsock, newsock, -1, c->local_window_max, c->local_maxpacket, 0, name, 1); if (compat20) { packet_start(SSH2_MSG_CHANNEL_OPEN); packet_put_cstring("auth-agent@openssh.com"); packet_put_int(nc->self); packet_put_int(c->local_window_max); packet_put_int(c->local_maxpacket); } else { packet_start(SSH_SMSG_AGENT_OPEN); packet_put_int(nc->self); } packet_send(); } } static void channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset) { int err = 0; socklen_t sz = sizeof(err); if (FD_ISSET(c->sock, writeset)) { 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", c->self); c->type = SSH_CHANNEL_OPEN; if (compat20) { packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); packet_put_int(c->remote_id); packet_put_int(c->self); packet_put_int(c->local_window); packet_put_int(c->local_maxpacket); } else { packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); packet_put_int(c->remote_id); packet_put_int(c->self); } } else { debug("channel %d: not connected: %s", c->self, strerror(err)); if (compat20) { packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); packet_put_int(c->remote_id); packet_put_int(SSH2_OPEN_CONNECT_FAILED); if (!(datafellows & SSH_BUG_OPENFAILURE)) { packet_put_cstring(strerror(err)); packet_put_cstring(""); } } else { packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); packet_put_int(c->remote_id); } chan_mark_dead(c); } packet_send(); } } static int channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset) { char buf[16*1024]; int len; if (c->rfd != -1 && FD_ISSET(c->rfd, readset)) { len = read(c->rfd, buf, sizeof(buf)); if (len < 0 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) { debug("channel %d: read<=0 rfd %d len %d", c->self, c->rfd, len); if (c->type != SSH_CHANNEL_OPEN) { debug("channel %d: not open", c->self); chan_mark_dead(c); return -1; } else if (compat13) { buffer_clear(&c->output); c->type = SSH_CHANNEL_INPUT_DRAINING; debug("channel %d: input draining.", c->self); } else { chan_read_failed(c); } return -1; } if (c->input_filter != NULL) { if (c->input_filter(c, buf, len) == -1) { debug("channel %d: filter stops", c->self); chan_read_failed(c); } } else { buffer_append(&c->input, buf, len); } } return 1; } static int channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset) { struct termios tio; u_char *data; u_int dlen; int len; /* Send buffered output data to the socket. */ if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) && buffer_len(&c->output) > 0) { data = buffer_ptr(&c->output); dlen = buffer_len(&c->output); len = write(c->wfd, data, dlen); if (len < 0 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) { if (c->type != SSH_CHANNEL_OPEN) { debug("channel %d: not open", c->self); chan_mark_dead(c); return -1; } else if (compat13) { buffer_clear(&c->output); debug("channel %d: input draining.", c->self); c->type = SSH_CHANNEL_INPUT_DRAINING; } else { chan_write_failed(c); } return -1; } if (compat20 && c->isatty && dlen >= 1 && data[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 + data) */ packet_send_ignore(4 + len); packet_send(); } } buffer_consume(&c->output, len); if (compat20 && len > 0) { c->local_consumed += len; } } return 1; } static int channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset) { char buf[16*1024]; int len; /** XXX handle drain efd, too */ if (c->efd != -1) { if (c->extended_usage == CHAN_EXTENDED_WRITE && FD_ISSET(c->efd, writeset) && buffer_len(&c->extended) > 0) { len = write(c->efd, buffer_ptr(&c->extended), buffer_len(&c->extended)); debug2("channel %d: written %d to efd %d", c->self, len, c->efd); if (len < 0 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) { debug2("channel %d: closing write-efd %d", c->self, c->efd); channel_close_fd(&c->efd); } else { buffer_consume(&c->extended, len); c->local_consumed += len; } } else if (c->extended_usage == CHAN_EXTENDED_READ && FD_ISSET(c->efd, readset)) { len = read(c->efd, buf, sizeof(buf)); debug2("channel %d: read %d from efd %d", c->self, len, c->efd); if (len < 0 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) { debug2("channel %d: closing read-efd %d", c->self, c->efd); channel_close_fd(&c->efd); } else { buffer_append(&c->extended, buf, len); } } } return 1; } static int channel_check_window(Channel *c) { if (c->type == SSH_CHANNEL_OPEN && !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) && c->local_window < c->local_window_max/2 && c->local_consumed > 0) { packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST); packet_put_int(c->remote_id); packet_put_int(c->local_consumed); packet_send(); 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(Channel *c, fd_set * readset, fd_set * writeset) { if (c->delayed) return; channel_handle_rfd(c, readset, writeset); channel_handle_wfd(c, readset, writeset); if (!compat20) return; channel_handle_efd(c, readset, writeset); channel_check_window(c); } static void channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset) { int len; /* Send buffered output data to the socket. */ if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) { len = write(c->sock, buffer_ptr(&c->output), buffer_len(&c->output)); if (len <= 0) buffer_clear(&c->output); else buffer_consume(&c->output, len); } } static void channel_handler_init_20(void) { channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open; channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open; channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener; channel_pre[SSH_CHANNEL_RPORT_LISTENER] = &channel_pre_listener; channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener; channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener; channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting; channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic; channel_post[SSH_CHANNEL_OPEN] = &channel_post_open; channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener; channel_post[SSH_CHANNEL_RPORT_LISTENER] = &channel_post_port_listener; channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener; channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener; channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting; channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open; } static void channel_handler_init_13(void) { channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open_13; channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open_13; channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener; channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener; channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener; channel_pre[SSH_CHANNEL_INPUT_DRAINING] = &channel_pre_input_draining; channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_pre_output_draining; channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting; channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic; channel_post[SSH_CHANNEL_OPEN] = &channel_post_open; channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener; channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener; channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener; channel_post[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_post_output_drain_13; channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting; channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open; } static void channel_handler_init_15(void) { channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open; channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open; channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener; channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener; channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener; channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting; channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic; channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener; channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener; channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener; channel_post[SSH_CHANNEL_OPEN] = &channel_post_open; channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting; channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open; } static void channel_handler_init(void) { int i; for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) { channel_pre[i] = NULL; channel_post[i] = NULL; } if (compat20) channel_handler_init_20(); else if (compat13) channel_handler_init_13(); else channel_handler_init_15(); } /* gc dead channels */ static void channel_garbage_collect(Channel *c) { if (c == NULL) return; if (c->detach_user != NULL) { if (!chan_is_dead(c, 0)) return; debug("channel %d: gc: notify user", c->self); c->detach_user(c->self, NULL); /* if we still have a callback */ if (c->detach_user != NULL) return; debug("channel %d: gc: user detached", c->self); } if (!chan_is_dead(c, 1)) return; debug("channel %d: garbage collecting", c->self); channel_free(c); } static void channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset) { static int did_init = 0; int i; Channel *c; if (!did_init) { channel_handler_init(); did_init = 1; } for (i = 0; i < channels_alloc; i++) { c = channels[i]; if (c == NULL) continue; if (ftab[c->type] != NULL) (*ftab[c->type])(c, readset, writeset); channel_garbage_collect(c); } } /* * Allocate/update select bitmasks and add any bits relevant to channels in * select bitmasks. */ void channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp, int *nallocp, int rekeying) { int n; u_int sz; n = MAX(*maxfdp, channel_max_fd); sz = howmany(n+1, NFDBITS) * sizeof(fd_mask); /* perhaps check sz < nalloc/2 and shrink? */ if (*readsetp == NULL || sz > *nallocp) { *readsetp = xrealloc(*readsetp, sz); *writesetp = xrealloc(*writesetp, sz); *nallocp = sz; } *maxfdp = n; memset(*readsetp, 0, sz); memset(*writesetp, 0, sz); if (!rekeying) channel_handler(channel_pre, *readsetp, *writesetp); } /* * After select, perform any appropriate operations for channels which have * events pending. */ void channel_after_select(fd_set * readset, fd_set * writeset) { channel_handler(channel_post, readset, writeset); } /* If there is data to send to the connection, enqueue some of it now. */ void channel_output_poll(void) { int len, i; Channel *c; for (i = 0; i < channels_alloc; i++) { c = channels[i]; if (c == NULL) continue; /* * We are only interested in channels that can have buffered * incoming data. */ if (compat13) { if (c->type != SSH_CHANNEL_OPEN && c->type != SSH_CHANNEL_INPUT_DRAINING) continue; } else { if (c->type != SSH_CHANNEL_OPEN) continue; } if (compat20 && (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) && (len = buffer_len(&c->input)) > 0) { /* * Send some data for the other side over the secure * connection. */ if (compat20) { if (len > c->remote_window) len = c->remote_window; if (len > c->remote_maxpacket) len = c->remote_maxpacket; } else { if (packet_is_interactive()) { if (len > 1024) len = 512; } else { /* Keep the packets at reasonable size. */ if (len > packet_get_maxsize()/2) len = packet_get_maxsize()/2; } } if (len > 0) { packet_start(compat20 ? SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA); packet_put_int(c->remote_id); packet_put_string(buffer_ptr(&c->input), len); packet_send(); buffer_consume(&c->input, len); c->remote_window -= len; } } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) { if (compat13) fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3"); /* * input-buffer is empty and read-socket shutdown: * tell peer, that we will not send more data: send IEOF */ chan_ibuf_empty(c); } /* Send extended data, i.e. stderr */ if (compat20 && c->remote_window > 0 && (len = buffer_len(&c->extended)) > 0 && c->extended_usage == CHAN_EXTENDED_READ) { debug2("channel %d: rwin %d elen %d euse %d", c->self, c->remote_window, buffer_len(&c->extended), c->extended_usage); if (len > c->remote_window) len = c->remote_window; if (len > c->remote_maxpacket) len = c->remote_maxpacket; packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA); packet_put_int(c->remote_id); packet_put_int(SSH2_EXTENDED_DATA_STDERR); packet_put_string(buffer_ptr(&c->extended), len); packet_send(); buffer_consume(&c->extended, len); c->remote_window -= len; debug2("channel %d: sent ext data %d", c->self, len); } } } /* -- protocol input */ void channel_input_data(int type, u_int32_t seq, void *ctxt) { int id; char *data; u_int data_len; Channel *c; /* Get the channel number and verify it. */ id = packet_get_int(); c = channel_lookup(id); if (c == NULL) packet_disconnect("Received data for nonexistent channel %d.", id); /* Ignore any data for non-open channels (might happen on close) */ if (c->type != SSH_CHANNEL_OPEN && c->type != SSH_CHANNEL_X11_OPEN) return; /* same for protocol 1.5 if output end is no longer open */ if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) return; /* Get the data. */ data = packet_get_string(&data_len); if (compat20) { if (data_len > c->local_maxpacket) { log("channel %d: rcvd big packet %d, maxpack %d", c->self, data_len, c->local_maxpacket); } if (data_len > c->local_window) { log("channel %d: rcvd too much data %d, win %d", c->self, data_len, c->local_window); xfree(data); return; } c->local_window -= data_len; } packet_check_eom(); buffer_append(&c->output, data, data_len); xfree(data); } void channel_input_extended_data(int type, u_int32_t seq, void *ctxt) { int id; int tcode; char *data; u_int data_len; Channel *c; /* Get the channel number and verify it. */ id = packet_get_int(); c = channel_lookup(id); if (c == NULL) packet_disconnect("Received extended_data for bad channel %d.", id); if (c->type != SSH_CHANNEL_OPEN) { log("channel %d: ext data for non open", id); return; } tcode = packet_get_int(); if (c->efd == -1 || c->extended_usage != CHAN_EXTENDED_WRITE || tcode != SSH2_EXTENDED_DATA_STDERR) { log("channel %d: bad ext data", c->self); return; } data = packet_get_string(&data_len); packet_check_eom(); if (data_len > c->local_window) { log("channel %d: rcvd too much extended_data %d, win %d", c->self, data_len, c->local_window); xfree(data); return; } debug2("channel %d: rcvd ext data %d", c->self, data_len); c->local_window -= data_len; buffer_append(&c->extended, data, data_len); xfree(data); } void channel_input_ieof(int type, u_int32_t seq, void *ctxt) { int id; Channel *c; id = packet_get_int(); packet_check_eom(); c = channel_lookup(id); if (c == NULL) packet_disconnect("Received ieof for nonexistent channel %d.", id); chan_rcvd_ieof(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 (buffer_len(&c->input) == 0) chan_ibuf_empty(c); } } void channel_input_close(int type, u_int32_t seq, void *ctxt) { int id; Channel *c; id = packet_get_int(); packet_check_eom(); c = channel_lookup(id); if (c == NULL) packet_disconnect("Received close for nonexistent channel %d.", id); /* * Send a confirmation that we have closed the channel and no more * data is coming for it. */ packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION); packet_put_int(c->remote_id); packet_send(); /* * If the channel is in closed state, we have sent a close request, * and the other side will eventually respond with a confirmation. * Thus, we cannot free the channel here, because then there would be * no-one to receive the confirmation. The channel gets freed when * the confirmation arrives. */ if (c->type != SSH_CHANNEL_CLOSED) { /* * Not a closed channel - mark it as draining, which will * cause it to be freed later. */ buffer_clear(&c->input); c->type = SSH_CHANNEL_OUTPUT_DRAINING; } } /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ void channel_input_oclose(int type, u_int32_t seq, void *ctxt) { int id = packet_get_int(); Channel *c = channel_lookup(id); packet_check_eom(); if (c == NULL) packet_disconnect("Received oclose for nonexistent channel %d.", id); chan_rcvd_oclose(c); } void channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt) { int id = packet_get_int(); Channel *c = channel_lookup(id); packet_check_eom(); if (c == NULL) packet_disconnect("Received close confirmation for " "out-of-range channel %d.", id); if (c->type != SSH_CHANNEL_CLOSED) packet_disconnect("Received close confirmation for " "non-closed channel %d (type %d).", id, c->type); channel_free(c); } void channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt) { int id, remote_id; Channel *c; id = packet_get_int(); c = channel_lookup(id); if (c==NULL || c->type != SSH_CHANNEL_OPENING) packet_disconnect("Received open confirmation for " "non-opening channel %d.", id); remote_id = packet_get_int(); /* Record the remote channel number and mark that the channel is now open. */ c->remote_id = remote_id; c->type = SSH_CHANNEL_OPEN; if (compat20) { c->remote_window = packet_get_int(); c->remote_maxpacket = packet_get_int(); if (c->confirm) { debug2("callback start"); c->confirm(c->self, NULL); debug2("callback done"); } debug("channel %d: open confirm rwindow %d rmax %d", c->self, c->remote_window, c->remote_maxpacket); } packet_check_eom(); } 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"; } void channel_input_open_failure(int type, u_int32_t seq, void *ctxt) { int id, reason; char *msg = NULL, *lang = NULL; Channel *c; id = packet_get_int(); c = channel_lookup(id); if (c==NULL || c->type != SSH_CHANNEL_OPENING) packet_disconnect("Received open failure for " "non-opening channel %d.", id); if (compat20) { reason = packet_get_int(); if (!(datafellows & SSH_BUG_OPENFAILURE)) { msg = packet_get_string(NULL); lang = packet_get_string(NULL); } log("channel %d: open failed: %s%s%s", id, reason2txt(reason), msg ? ": ": "", msg ? msg : ""); if (msg != NULL) xfree(msg); if (lang != NULL) xfree(lang); } packet_check_eom(); /* Free the channel. This will also close the socket. */ channel_free(c); } void channel_input_window_adjust(int type, u_int32_t seq, void *ctxt) { Channel *c; int id, adjust; if (!compat20) return; /* Get the channel number and verify it. */ id = packet_get_int(); c = channel_lookup(id); if (c == NULL || c->type != SSH_CHANNEL_OPEN) { log("Received window adjust for " "non-open channel %d.", id); return; } adjust = packet_get_int(); packet_check_eom(); debug2("channel %d: rcvd adjust %d", id, adjust); c->remote_window += adjust; } void channel_input_port_open(int type, u_int32_t seq, void *ctxt) { Channel *c = NULL; u_short host_port; char *host, *originator_string; int remote_id, sock = -1; remote_id = packet_get_int(); host = packet_get_string(NULL); host_port = packet_get_int(); if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) { originator_string = packet_get_string(NULL); } else { originator_string = xstrdup("unknown (remote did not supply name)"); } packet_check_eom(); sock = channel_connect_to(host, host_port); if (sock != -1) { c = channel_new("connected socket", SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0, originator_string, 1); c->remote_id = remote_id; } if (c == NULL) { packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); packet_put_int(remote_id); packet_send(); } xfree(host); } /* -- tcp forwarding */ void channel_set_af(int af) { IPv4or6 = af; } static int channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port, const char *host_to_connect, u_short port_to_connect, int gateway_ports) { Channel *c; int success, sock, on = 1; struct addrinfo hints, *ai, *aitop; const char *host; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; struct linger linger; success = 0; host = (type == SSH_CHANNEL_RPORT_LISTENER) ? listen_addr : host_to_connect; if (host == NULL) { error("No forward host name."); return success; } if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) { error("Forward host name too long."); return success; } /* * 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 = IPv4or6; hints.ai_flags = gateway_ports ? AI_PASSIVE : 0; hints.ai_socktype = SOCK_STREAM; snprintf(strport, sizeof strport, "%d", listen_port); if (getaddrinfo(NULL, strport, &hints, &aitop) != 0) packet_disconnect("getaddrinfo: fatal error"); for (ai = aitop; ai; ai = ai->ai_next) { if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) continue; if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop), strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) { error("channel_setup_fwd_listener: getnameinfo failed"); continue; } /* Create a port to listen for the host. */ sock = socket(ai->ai_family, SOCK_STREAM, 0); if (sock < 0) { /* this is no error since kernel may not support ipv6 */ verbose("socket: %.100s", strerror(errno)); continue; } /* * Set socket options. We would like the socket to disappear * as soon as it has been closed for whatever reason. */ setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); linger.l_onoff = 1; linger.l_linger = 5; setsockopt(sock, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger)); 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 use ipv6 address is already bound */ verbose("bind: %.100s", strerror(errno)); close(sock); continue; } /* Start listening for connections on the socket. */ if (listen(sock, 5) < 0) { error("listen: %.100s", strerror(errno)); close(sock); continue; } /* Allocate a channel number for the socket. */ c = channel_new("port listener", type, sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("port listener"), 1); strlcpy(c->path, host, sizeof(c->path)); c->host_port = port_to_connect; c->listening_port = listen_port; success = 1; } if (success == 0) error("channel_setup_fwd_listener: cannot listen to port: %d", listen_port); freeaddrinfo(aitop); return success; } /* protocol local port fwd, used by ssh (and sshd in v1) */ int channel_setup_local_fwd_listener(u_short listen_port, const char *host_to_connect, u_short port_to_connect, int gateway_ports) { return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER, NULL, listen_port, host_to_connect, port_to_connect, gateway_ports); } /* protocol v2 remote port fwd, used by sshd */ int channel_setup_remote_fwd_listener(const char *listen_address, u_short listen_port, int gateway_ports) { return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER, listen_address, listen_port, NULL, 0, gateway_ports); } /* * Initiate forwarding of connections to port "port" on remote host through * the secure channel to host:port from local side. */ void channel_request_remote_forwarding(u_short listen_port, const char *host_to_connect, u_short port_to_connect) { int type, success = 0; /* Record locally that connection to this host/port is permitted. */ if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION) fatal("channel_request_remote_forwarding: too many forwards"); /* Send the forward request to the remote side. */ if (compat20) { const char *address_to_bind = "0.0.0.0"; packet_start(SSH2_MSG_GLOBAL_REQUEST); packet_put_cstring("tcpip-forward"); packet_put_char(0); /* boolean: want reply */ packet_put_cstring(address_to_bind); packet_put_int(listen_port); packet_send(); packet_write_wait(); /* Assume that server accepts the request */ success = 1; } else { packet_start(SSH_CMSG_PORT_FORWARD_REQUEST); packet_put_int(listen_port); packet_put_cstring(host_to_connect); packet_put_int(port_to_connect); packet_send(); packet_write_wait(); /* Wait for response from the remote side. */ type = packet_read(); switch (type) { case SSH_SMSG_SUCCESS: success = 1; break; case SSH_SMSG_FAILURE: log("Warning: Server denied remote port forwarding."); break; default: /* Unknown packet */ packet_disconnect("Protocol error for port forward request:" "received packet type %d.", type); } } if (success) { permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect); permitted_opens[num_permitted_opens].port_to_connect = port_to_connect; permitted_opens[num_permitted_opens].listen_port = listen_port; num_permitted_opens++; } } /* * This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates * listening for the port, and sends back a success reply (or disconnect * message if there was an error). This never returns if there was an error. */ void channel_input_port_forward_request(int is_root, int gateway_ports) { u_short port, host_port; char *hostname; /* Get arguments from the packet. */ port = packet_get_int(); hostname = packet_get_string(NULL); host_port = packet_get_int(); /* * Check that an unprivileged user is not trying to forward a * privileged port. */ if (port < IPPORT_RESERVED && !is_root) packet_disconnect("Requested forwarding of port %d but user is not root.", port); /* Initiate forwarding */ channel_setup_local_fwd_listener(port, hostname, host_port, gateway_ports); /* Free the argument string. */ xfree(hostname); } /* * Permits opening to any host/port if permitted_opens[] 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_opens(void) { if (num_permitted_opens == 0) all_opens_permitted = 1; } void channel_add_permitted_opens(char *host, int port) { if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION) fatal("channel_request_remote_forwarding: too many forwards"); debug("allow port forwarding to host %s port %d", host, port); permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host); permitted_opens[num_permitted_opens].port_to_connect = port; num_permitted_opens++; all_opens_permitted = 0; } void channel_clear_permitted_opens(void) { int i; for (i = 0; i < num_permitted_opens; i++) xfree(permitted_opens[i].host_to_connect); num_permitted_opens = 0; } /* return socket to remote host, port */ static int connect_to(const char *host, u_short port) { struct addrinfo hints, *ai, *aitop; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; int gaierr; int sock = -1; memset(&hints, 0, sizeof(hints)); hints.ai_family = IPv4or6; hints.ai_socktype = SOCK_STREAM; snprintf(strport, sizeof strport, "%d", port); if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) { error("connect_to %.100s: unknown host (%s)", host, 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; if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop), strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) { error("connect_to: getnameinfo failed"); continue; } sock = socket(ai->ai_family, SOCK_STREAM, 0); if (sock < 0) { error("socket: %.100s", strerror(errno)); continue; } if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0) fatal("connect_to: F_SETFL: %s", strerror(errno)); if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 && errno != EINPROGRESS) { error("connect_to %.100s port %s: %.100s", ntop, strport, strerror(errno)); close(sock); continue; /* fail -- try next */ } break; /* success */ } freeaddrinfo(aitop); if (!ai) { error("connect_to %.100s port %d: failed.", host, port); return -1; } /* success */ set_nodelay(sock); return sock; } int channel_connect_by_listen_address(u_short listen_port) { int i; for (i = 0; i < num_permitted_opens; i++) if (permitted_opens[i].listen_port == listen_port) return connect_to( permitted_opens[i].host_to_connect, permitted_opens[i].port_to_connect); error("WARNING: Server requests forwarding for unknown listen_port %d", listen_port); return -1; } /* Check if connecting to that port is permitted and connect. */ int channel_connect_to(const char *host, u_short port) { int i, permit; permit = all_opens_permitted; if (!permit) { for (i = 0; i < num_permitted_opens; i++) if (permitted_opens[i].port_to_connect == port && strcmp(permitted_opens[i].host_to_connect, host) == 0) permit = 1; } if (!permit) { log("Received request to connect to host %.100s port %d, " "but the request was denied.", host, port); return -1; } return connect_to(host, port); } /* -- X11 forwarding */ /* * Creates an internet domain socket for listening for X11 connections. * Returns a suitable display number for the DISPLAY variable, or -1 if * an error occurs. */ int x11_create_display_inet(int x11_display_offset, int x11_use_localhost, int single_connection) { 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]; for (display_number = x11_display_offset; display_number < MAX_DISPLAYS; display_number++) { port = 6000 + display_number; memset(&hints, 0, sizeof(hints)); hints.ai_family = 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", 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, SOCK_STREAM, 0); if (sock < 0) { error("socket: %.100s", strerror(errno)); return -1; } if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) { debug("bind port %d: %.100s", 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, 5) < 0) { error("listen: %.100s", strerror(errno)); close(sock); return -1; } } /* Allocate a channel for each socket. */ for (n = 0; n < num_socks; n++) { sock = socks[n]; nc = channel_new("x11 listener", SSH_CHANNEL_X11_LISTENER, sock, sock, -1, CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, xstrdup("X11 inet listener"), 1); nc->single_connection = single_connection; } /* Return the display number for the DISPLAY environment variable. */ return display_number; } static int connect_local_xsocket(u_int dnr) { 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; snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr); if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0) return sock; close(sock); error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); return -1; } int x11_connect_display(void) { int display_number, sock = 0; const char *display; char buf[1024], *cp; struct addrinfo hints, *ai, *aitop; char strport[NI_MAXSERV]; int gaierr; /* 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. */ /* * 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, "%d", &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, "%d", &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 = IPv4or6; hints.ai_socktype = SOCK_STREAM; snprintf(strport, sizeof strport, "%d", 6000 + display_number); if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) { error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr)); return -1; } for (ai = aitop; ai; ai = ai->ai_next) { /* Create a socket. */ sock = socket(ai->ai_family, SOCK_STREAM, 0); if (sock < 0) { debug("socket: %.100s", strerror(errno)); continue; } /* Connect it to the display. */ if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) { debug("connect %.100s port %d: %.100s", buf, 6000 + display_number, strerror(errno)); close(sock); continue; } /* Success */ break; } freeaddrinfo(aitop); if (!ai) { error("connect %.100s port %d: %.100s", buf, 6000 + display_number, strerror(errno)); return -1; } set_nodelay(sock); return sock; } /* * This is called when SSH_SMSG_X11_OPEN is received. The packet contains * the remote channel number. We should do whatever we want, and respond * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE. */ void x11_input_open(int type, u_int32_t seq, void *ctxt) { Channel *c = NULL; int remote_id, sock = 0; char *remote_host; debug("Received X11 open request."); remote_id = packet_get_int(); if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) { remote_host = packet_get_string(NULL); } else { remote_host = xstrdup("unknown (remote did not supply name)"); } packet_check_eom(); /* Obtain a connection to the real X display. */ sock = x11_connect_display(); if (sock != -1) { /* Allocate a channel for this connection. */ c = channel_new("connected x11 socket", SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0, remote_host, 1); c->remote_id = remote_id; c->force_drain = 1; } if (c == NULL) { /* Send refusal to the remote host. */ packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); packet_put_int(remote_id); } else { /* Send a confirmation to the remote host. */ packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); packet_put_int(remote_id); packet_put_int(c->self); } packet_send(); } /* dummy protocol handler that denies SSH-1 requests (agent/x11) */ void deny_input_open(int type, u_int32_t seq, void *ctxt) { int rchan = packet_get_int(); switch (type) { case SSH_SMSG_AGENT_OPEN: error("Warning: ssh server tried agent forwarding."); break; case SSH_SMSG_X11_OPEN: error("Warning: ssh server tried X11 forwarding."); break; default: error("deny_input_open: type %d", type); break; } error("Warning: this is probably a break in attempt by a malicious server."); packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); packet_put_int(rchan); packet_send(); } /* * 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(int client_session_id, const char *proto, const char *data) { u_int data_len = (u_int) strlen(data) / 2; u_int i, value, len; char *new_data; int screen_number; const char *cp; u_int32_t rand = 0; cp = getenv("DISPLAY"); if (cp) cp = strchr(cp, ':'); if (cp) cp = strchr(cp, '.'); if (cp) screen_number = atoi(cp + 1); else screen_number = 0; /* Save protocol name. */ x11_saved_proto = xstrdup(proto); /* * Extract real authentication data and generate fake data of the * same length. */ x11_saved_data = xmalloc(data_len); x11_fake_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); if (i % 4 == 0) rand = arc4random(); x11_saved_data[i] = value; x11_fake_data[i] = rand & 0xff; rand >>= 8; } x11_saved_data_len = data_len; x11_fake_data_len = data_len; /* Convert the fake data into hex. */ len = 2 * data_len + 1; new_data = xmalloc(len); for (i = 0; i < data_len; i++) snprintf(new_data + 2 * i, len - 2 * i, "%02x", (u_char) x11_fake_data[i]); /* Send the request packet. */ if (compat20) { channel_request_start(client_session_id, "x11-req", 0); packet_put_char(0); /* XXX bool single connection */ } else { packet_start(SSH_CMSG_X11_REQUEST_FORWARDING); } packet_put_cstring(proto); packet_put_cstring(new_data); packet_put_int(screen_number); packet_send(); packet_write_wait(); xfree(new_data); } /* -- agent forwarding */ /* Sends a message to the server to request authentication fd forwarding. */ void auth_request_forwarding(void) { packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING); packet_send(); packet_write_wait(); } /* * Returns the name of the forwarded authentication socket. Returns NULL if * there is no forwarded authentication socket. The returned value points to * a static buffer. */ char * auth_get_socket_name(void) { return auth_sock_name; } /* removes the agent forwarding socket */ void auth_sock_cleanup_proc(void *_pw) { struct passwd *pw = _pw; if (auth_sock_name) { temporarily_use_uid(pw); unlink(auth_sock_name); rmdir(auth_sock_dir); auth_sock_name = NULL; restore_uid(); } } /* * This is called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. * This starts forwarding authentication requests. */ int auth_input_request_forwarding(struct passwd * pw) { Channel *nc; int sock; struct sockaddr_un sunaddr; if (auth_get_socket_name() != NULL) { error("authentication forwarding requested twice."); return 0; } /* Temporarily drop privileged uid for mkdir/bind. */ temporarily_use_uid(pw); /* Allocate a buffer for the socket name, and format the name. */ auth_sock_name = xmalloc(MAXPATHLEN); auth_sock_dir = xmalloc(MAXPATHLEN); strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); /* Create private directory for socket */ if (mkdtemp(auth_sock_dir) == NULL) { packet_send_debug("Agent forwarding disabled: " "mkdtemp() failed: %.100s", strerror(errno)); restore_uid(); xfree(auth_sock_name); xfree(auth_sock_dir); auth_sock_name = NULL; auth_sock_dir = NULL; return 0; } snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%d", auth_sock_dir, (int) getpid()); /* delete agent socket on fatal() */ fatal_add_cleanup(auth_sock_cleanup_proc, pw); /* Create the socket. */ sock = socket(AF_UNIX, SOCK_STREAM, 0); if (sock < 0) packet_disconnect("socket: %.100s", strerror(errno)); /* Bind it to the name. */ memset(&sunaddr, 0, sizeof(sunaddr)); sunaddr.sun_family = AF_UNIX; strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) packet_disconnect("bind: %.100s", strerror(errno)); /* Restore the privileged uid. */ restore_uid(); /* Start listening on the socket. */ if (listen(sock, 5) < 0) packet_disconnect("listen: %.100s", strerror(errno)); /* Allocate a channel for the authentication agent socket. */ nc = channel_new("auth socket", SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, xstrdup("auth socket"), 1); strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); return 1; } /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ void auth_input_open_request(int type, u_int32_t seq, void *ctxt) { Channel *c = NULL; int remote_id, sock; char *name; /* Read the remote channel number from the message. */ remote_id = packet_get_int(); packet_check_eom(); /* * Get a connection to the local authentication agent (this may again * get forwarded). */ sock = ssh_get_authentication_socket(); /* * If we could not connect the agent, send an error message back to * the server. This should never happen unless the agent dies, * because authentication forwarding is only enabled if we have an * agent. */ if (sock >= 0) { name = xstrdup("authentication agent connection"); c = channel_new("", SSH_CHANNEL_OPEN, sock, sock, -1, 0, 0, 0, name, 1); c->remote_id = remote_id; c->force_drain = 1; } if (c == NULL) { packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); packet_put_int(remote_id); } else { /* Send a confirmation to the remote host. */ debug("Forwarding authentication connection."); packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); packet_put_int(remote_id); packet_put_int(c->self); } packet_send(); }