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Diffstat (limited to 'crypto/openssh/channels.c')
| -rw-r--r-- | crypto/openssh/channels.c | 2334 |
1 files changed, 2334 insertions, 0 deletions
diff --git a/crypto/openssh/channels.c b/crypto/openssh/channels.c new file mode 100644 index 0000000..81bd715 --- /dev/null +++ b/crypto/openssh/channels.c @@ -0,0 +1,2334 @@ +/* + * 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 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 1.72 2000/10/27 07:48:22 markus Exp $"); + +#include "ssh.h" +#include "packet.h" +#include "xmalloc.h" +#include "buffer.h" +#include "uidswap.h" +#include "readconf.h" +#include "servconf.h" + +#include "channels.h" +#include "nchan.h" +#include "compat.h" + +#include "ssh2.h" + +#include <openssl/rsa.h> +#include <openssl/dsa.h> +#include "key.h" +#include "authfd.h" + +/* Maximum number of fake X11 displays to try. */ +#define MAX_DISPLAYS 1000 + +/* Max len of agent socket */ +#define MAX_SOCKET_NAME 100 + +/* + * 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 are marked with type + * SSH_CHANNEL_FREE. + */ +static int channels_alloc = 0; + +/* + * Maximum file descriptor value used in any of the channels. This is + * updated in channel_allocate. + */ +static int channel_max_fd_value = 0; + +/* Name and directory of socket for authentication agent forwarding. */ +static char *channel_forwarded_auth_socket_name = NULL; +static char *channel_forwarded_auth_socket_dir = NULL; + +/* Saved X11 authentication protocol name. */ +char *x11_saved_proto = NULL; + +/* Saved X11 authentication data. This is the real data. */ +char *x11_saved_data = NULL; +unsigned 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. + */ +char *x11_fake_data = NULL; +unsigned int x11_fake_data_len; + +/* + * 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; + +/* This is set to true if both sides support SSH_PROTOFLAG_HOST_IN_FWD_OPEN. */ +static int have_hostname_in_open = 0; + +/* Sets specific protocol options. */ + +void +channel_set_options(int hostname_in_open) +{ + have_hostname_in_open = hostname_in_open; +} + +/* + * Permits opening to any host/port in SSH_MSG_PORT_OPEN. 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() +{ + all_opens_permitted = 1; +} + +/* lookup channel by id */ + +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->type == SSH_CHANNEL_FREE) { + 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 + */ + +void +channel_register_fds(Channel *c, int rfd, int wfd, int efd, + int extusage, int nonblock) +{ + /* Update the maximum file descriptor value. */ + if (rfd > channel_max_fd_value) + channel_max_fd_value = rfd; + if (wfd > channel_max_fd_value) + channel_max_fd_value = wfd; + if (efd > channel_max_fd_value) + channel_max_fd_value = 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; + + /* 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. + */ + +int +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) { + chan_init(); + channels_alloc = 10; + channels = xmalloc(channels_alloc * sizeof(Channel)); + for (i = 0; i < channels_alloc; i++) + channels[i].type = SSH_CHANNEL_FREE; + /* + * Kludge: arrange a call to channel_stop_listening if we + * terminate with fatal(). + */ + fatal_add_cleanup((void (*) (void *)) channel_stop_listening, 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].type == SSH_CHANNEL_FREE) { + /* 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].type = SSH_CHANNEL_FREE; + } + /* Initialize and return new channel number. */ + c = &channels[found]; + buffer_init(&c->input); + buffer_init(&c->output); + buffer_init(&c->extended); + chan_init_iostates(c); + 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->cb_fn = NULL; + c->cb_arg = NULL; + c->cb_event = 0; + c->dettach_user = NULL; + c->input_filter = NULL; + debug("channel %d: new [%s]", found, remote_name); + return found; +} +/* old interface XXX */ +int +channel_allocate(int type, int sock, char *remote_name) +{ + return channel_new("", type, sock, sock, -1, 0, 0, 0, remote_name, 1); +} + + +/* Close all channel fd/socket. */ + +void +channel_close_fds(Channel *c) +{ + if (c->sock != -1) { + close(c->sock); + c->sock = -1; + } + if (c->rfd != -1) { + close(c->rfd); + c->rfd = -1; + } + if (c->wfd != -1) { + close(c->wfd); + c->wfd = -1; + } + if (c->efd != -1) { + close(c->efd); + c->efd = -1; + } +} + +/* Free the channel and close its fd/socket. */ + +void +channel_free(int id) +{ + Channel *c = channel_lookup(id); + if (c == NULL) + packet_disconnect("channel free: bad local channel %d", id); + debug("channel_free: channel %d: status: %s", id, channel_open_message()); + if (c->dettach_user != NULL) { + debug("channel_free: channel %d: dettaching channel user", id); + c->dettach_user(c->self, NULL); + } + 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); + c->type = SSH_CHANNEL_FREE; + if (c->remote_name) { + xfree(c->remote_name); + c->remote_name = NULL; + } +} + +/* + * '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]; + +void +channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset) +{ + FD_SET(c->sock, readset); +} + +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); +} + +void +channel_pre_open_15(Channel *c, fd_set * readset, fd_set * writeset) +{ + /* test whether sockets are 'alive' for read/write */ + if (c->istate == CHAN_INPUT_OPEN) + if (buffer_len(&c->input) < packet_get_maxsize()) + FD_SET(c->sock, readset); + if (c->ostate == CHAN_OUTPUT_OPEN || + c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { + if (buffer_len(&c->output) > 0) { + FD_SET(c->sock, writeset); + } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { + chan_obuf_empty(c); + } + } +} + +void +channel_pre_open_20(Channel *c, fd_set * readset, fd_set * writeset) +{ + if (c->istate == CHAN_INPUT_OPEN && + c->remote_window > 0 && + buffer_len(&c->input) < c->remote_window) + 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 (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); + } +} + +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("Closing channel %d after input drain.", c->self); + } +} + +void +channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset) +{ + if (buffer_len(&c->output) == 0) + channel_free(c->self); + 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. + */ +int +x11_open_helper(Channel *c) +{ + unsigned char *ucp; + unsigned int proto_len, data_len; + + /* Check if the fixed size part of the packet is in buffer. */ + if (buffer_len(&c->output) < 12) + return 0; + + /* Parse the lengths of variable-length fields. */ + ucp = (unsigned char *) buffer_ptr(&c->output); + 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(&c->output) < + 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; +} + +void +channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset) +{ + int ret = x11_open_helper(c); + 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.\r\n"); + buffer_clear(&c->input); + buffer_clear(&c->output); + close(c->sock); + c->sock = -1; + c->type = SSH_CHANNEL_CLOSED; + packet_start(SSH_MSG_CHANNEL_CLOSE); + packet_put_int(c->remote_id); + packet_send(); + } +} + +void +channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset) +{ + int ret = x11_open_helper(c); + if (ret == 1) { + c->type = SSH_CHANNEL_OPEN; + if (compat20) + channel_pre_open_20(c, readset, writeset); + else + channel_pre_open_15(c, readset, writeset); + } else if (ret == -1) { + debug("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate); + chan_read_failed(c); /** force close? */ + chan_write_failed(c); + debug("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate); + } +} + +/* This is our fake X11 server socket. */ +void +channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset) +{ + struct sockaddr addr; + int newsock, newch; + socklen_t addrlen; + char buf[16384], *remote_hostname; + int remote_port; + + if (FD_ISSET(c->sock, readset)) { + debug("X11 connection requested."); + addrlen = sizeof(addr); + newsock = accept(c->sock, &addr, &addrlen); + if (newsock < 0) { + error("accept: %.100s", strerror(errno)); + return; + } + remote_hostname = get_remote_hostname(newsock); + remote_port = get_peer_port(newsock); + snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", + remote_hostname, remote_port); + + newch = channel_new("x11", + 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(newch); + packet_put_int(c->local_window_max); + packet_put_int(c->local_maxpacket); + /* originator host and port */ + packet_put_cstring(remote_hostname); + 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(newch); + if (have_hostname_in_open) + packet_put_string(buf, strlen(buf)); + packet_send(); + } + xfree(remote_hostname); + } +} + +/* + * This socket is listening for connections to a forwarded TCP/IP port. + */ +void +channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset) +{ + struct sockaddr addr; + int newsock, newch; + socklen_t addrlen; + char buf[1024], *remote_hostname; + int remote_port; + + 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); + addrlen = sizeof(addr); + newsock = accept(c->sock, &addr, &addrlen); + if (newsock < 0) { + error("accept: %.100s", strerror(errno)); + return; + } + remote_hostname = get_remote_hostname(newsock); + remote_port = get_peer_port(newsock); + snprintf(buf, sizeof buf, + "listen port %d for %.100s port %d, " + "connect from %.200s port %d", + c->listening_port, c->path, c->host_port, + remote_hostname, remote_port); + newch = channel_new("direct-tcpip", + 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("direct-tcpip"); + packet_put_int(newch); + packet_put_int(c->local_window_max); + packet_put_int(c->local_maxpacket); + /* target host and port */ + packet_put_string(c->path, strlen(c->path)); + packet_put_int(c->host_port); + /* originator host and port */ + packet_put_cstring(remote_hostname); + packet_put_int(remote_port); + packet_send(); + } else { + packet_start(SSH_MSG_PORT_OPEN); + packet_put_int(newch); + packet_put_string(c->path, strlen(c->path)); + packet_put_int(c->host_port); + if (have_hostname_in_open) { + packet_put_string(buf, strlen(buf)); + } + packet_send(); + } + xfree(remote_hostname); + } +} + +/* + * This is the authentication agent socket listening for connections from + * clients. + */ +void +channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset) +{ + struct sockaddr addr; + int newsock, newch; + 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; + } + newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, + xstrdup("accepted auth socket")); + packet_start(SSH_SMSG_AGENT_OPEN); + packet_put_int(newch); + packet_send(); + } +} + +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 (compat13) { + buffer_consume(&c->output, buffer_len(&c->output)); + c->type = SSH_CHANNEL_INPUT_DRAINING; + debug("Channel %d status set to 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("filter stops channel %d", c->self); + chan_read_failed(c); + } + } else { + buffer_append(&c->input, buf, len); + } + } + return 1; +} +int +channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset) +{ + int len; + + /* Send buffered output data to the socket. */ + if (c->wfd != -1 && + FD_ISSET(c->wfd, writeset) && + buffer_len(&c->output) > 0) { + len = write(c->wfd, buffer_ptr(&c->output), + buffer_len(&c->output)); + if (len < 0 && (errno == EINTR || errno == EAGAIN)) + return 1; + if (len <= 0) { + if (compat13) { + buffer_consume(&c->output, buffer_len(&c->output)); + debug("Channel %d status set to input draining.", c->self); + c->type = SSH_CHANNEL_INPUT_DRAINING; + } else { + chan_write_failed(c); + } + return -1; + } + buffer_consume(&c->output, len); + if (compat20 && len > 0) { + c->local_consumed += len; + } + } + return 1; +} +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) { + 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) { + debug("channel %d: closing efd %d", + c->self, c->efd); + close(c->efd); + c->efd = -1; + } else if (len > 0) + buffer_append(&c->extended, buf, len); + } + } + return 1; +} +int +channel_check_window(Channel *c, fd_set * readset, fd_set * writeset) +{ + if (!(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; +} + +void +channel_post_open_1(Channel *c, fd_set * readset, fd_set * writeset) +{ + channel_handle_rfd(c, readset, writeset); + channel_handle_wfd(c, readset, writeset); +} + +void +channel_post_open_2(Channel *c, fd_set * readset, fd_set * writeset) +{ + channel_handle_rfd(c, readset, writeset); + channel_handle_wfd(c, readset, writeset); + channel_handle_efd(c, readset, writeset); + channel_check_window(c, readset, writeset); +} + +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_consume(&c->output, buffer_len(&c->output)); + else + buffer_consume(&c->output, len); + } +} + +void +channel_handler_init_20(void) +{ + channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open_20; + channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open; + channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener; + channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener; + + channel_post[SSH_CHANNEL_OPEN] = &channel_post_open_2; + channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener; + channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener; +} + +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_post[SSH_CHANNEL_OPEN] = &channel_post_open_1; + 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; +} + +void +channel_handler_init_15(void) +{ + channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open_15; + 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_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_1; +} + +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(); +} + +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->type == SSH_CHANNEL_FREE) + continue; + if (ftab[c->type] == NULL) + continue; + (*ftab[c->type])(c, readset, writeset); + chan_delete_if_full_closed(c); + } +} + +void +channel_prepare_select(fd_set * readset, fd_set * writeset) +{ + channel_handler(channel_pre, readset, writeset); +} + +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, send some of it now. */ + +void +channel_output_poll() +{ + int len, i; + Channel *c; + + for (i = 0; i < channels_alloc; i++) { + c = &channels[i]; + + /* 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 (c->istate != CHAN_INPUT_OPEN && + c->istate != CHAN_INPUT_WAIT_DRAIN) + continue; + } + if (compat20 && + (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) { + debug("channel: %d: no data after CLOSE", c->self); + continue; + } + + /* Get the amount of buffered data for this channel. */ + len = buffer_len(&c->input); + if (len > 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) { + 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; + } + } +} + +/* + * This is called when a packet of type CHANNEL_DATA has just been received. + * The message type has already been consumed, but channel number and data is + * still there. + */ + +void +channel_input_data(int type, int plen, void *ctxt) +{ + int id; + char *data; + unsigned 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); + packet_done(); + + 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; + }else{ + packet_integrity_check(plen, 4 + 4 + data_len, type); + } + buffer_append(&c->output, data, data_len); + xfree(data); +} +void +channel_input_extended_data(int type, int plen, void *ctxt) +{ + int id; + int tcode; + char *data; + unsigned 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_done(); + 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); +} + + +/* + * 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() +{ + unsigned int i; + Channel *c; + + for (i = 0; i < channels_alloc; i++) { + c = &channels[i]; + if (c->type == SSH_CHANNEL_OPEN) { + if (!compat20 && buffer_len(&c->input) > packet_get_maxsize()) { + debug("channel %d: big input buffer %d", + c->self, buffer_len(&c->input)); + return 0; + } + if (buffer_len(&c->output) > packet_get_maxsize()) { + debug("channel %d: big output buffer %d", + c->self, buffer_len(&c->output)); + return 0; + } + } + } + return 1; +} + +void +channel_input_ieof(int type, int plen, void *ctxt) +{ + int id; + Channel *c; + + packet_integrity_check(plen, 4, type); + + id = packet_get_int(); + c = channel_lookup(id); + if (c == NULL) + packet_disconnect("Received ieof for nonexistent channel %d.", id); + chan_rcvd_ieof(c); +} + +void +channel_input_close(int type, int plen, void *ctxt) +{ + int id; + Channel *c; + + packet_integrity_check(plen, 4, type); + + id = packet_get_int(); + 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_consume(&c->input, buffer_len(&c->input)); + c->type = SSH_CHANNEL_OUTPUT_DRAINING; + } +} + +/* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ +void +channel_input_oclose(int type, int plen, void *ctxt) +{ + int id = packet_get_int(); + Channel *c = channel_lookup(id); + packet_integrity_check(plen, 4, type); + if (c == NULL) + packet_disconnect("Received oclose for nonexistent channel %d.", id); + chan_rcvd_oclose(c); +} + +void +channel_input_close_confirmation(int type, int plen, void *ctxt) +{ + int id = packet_get_int(); + Channel *c = channel_lookup(id); + + packet_done(); + 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->self); +} + +void +channel_input_open_confirmation(int type, int plen, void *ctxt) +{ + int id, remote_id; + Channel *c; + + if (!compat20) + packet_integrity_check(plen, 4 + 4, type); + + 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(); + packet_done(); + if (c->cb_fn != NULL && c->cb_event == type) { + debug2("callback start"); + c->cb_fn(c->self, c->cb_arg); + debug2("callback done"); + } + debug("channel %d: open confirm rwindow %d rmax %d", c->self, + c->remote_window, c->remote_maxpacket); + } +} + +void +channel_input_open_failure(int type, int plen, void *ctxt) +{ + int id; + Channel *c; + + if (!compat20) + packet_integrity_check(plen, 4, type); + + 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) { + int reason = packet_get_int(); + char *msg = packet_get_string(NULL); + char *lang = packet_get_string(NULL); + log("channel_open_failure: %d: reason %d: %s", id, reason, msg); + packet_done(); + xfree(msg); + xfree(lang); + } + /* Free the channel. This will also close the socket. */ + channel_free(id); +} + +void +channel_input_channel_request(int type, int plen, void *ctxt) +{ + int id; + Channel *c; + + id = packet_get_int(); + c = channel_lookup(id); + + if (c == NULL || + (c->type != SSH_CHANNEL_OPEN && c->type != SSH_CHANNEL_LARVAL)) + packet_disconnect("Received request for " + "non-open channel %d.", id); + if (c->cb_fn != NULL && c->cb_event == type) { + debug2("callback start"); + c->cb_fn(c->self, c->cb_arg); + debug2("callback done"); + } else { + char *service = packet_get_string(NULL); + debug("channel: %d rcvd request for %s", c->self, service); + debug("cb_fn %p cb_event %d", c->cb_fn , c->cb_event); + xfree(service); + } +} + +void +channel_input_window_adjust(int type, int plen, 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_done(); + debug2("channel %d: rcvd adjust %d", id, adjust); + c->remote_window += adjust; +} + +/* + * Stops listening for channels, and removes any unix domain sockets that we + * might have. + */ + +void +channel_stop_listening() +{ + int i; + for (i = 0; i < channels_alloc; i++) { + switch (channels[i].type) { + case SSH_CHANNEL_AUTH_SOCKET: + close(channels[i].sock); + remove(channels[i].path); + channel_free(i); + break; + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_X11_LISTENER: + close(channels[i].sock); + channel_free(i); + break; + default: + break; + } + } +} + +/* + * Closes the sockets/fds of all channels. This is used to close extra file + * descriptors after a fork. + */ + +void +channel_close_all() +{ + int i; + for (i = 0; i < channels_alloc; i++) + if (channels[i].type != SSH_CHANNEL_FREE) + channel_close_fds(&channels[i]); +} + +/* Returns the maximum file descriptor number used by the channels. */ + +int +channel_max_fd() +{ + return channel_max_fd_value; +} + +/* Returns true if any channel is still open. */ + +int +channel_still_open() +{ + unsigned int i; + for (i = 0; i < channels_alloc; i++) + switch (channels[i].type) { + case SSH_CHANNEL_FREE: + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_CLOSED: + case SSH_CHANNEL_AUTH_SOCKET: + 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", channels[i].type); + /* NOTREACHED */ + } + return 0; +} + +/* + * 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() +{ + Buffer buffer; + int i; + char buf[512], *cp; + + 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++) { + Channel *c = &channels[i]; + switch (c->type) { + case SSH_CHANNEL_FREE: + case SSH_CHANNEL_X11_LISTENER: + case SSH_CHANNEL_PORT_LISTENER: + case SSH_CHANNEL_CLOSED: + case SSH_CHANNEL_AUTH_SOCKET: + continue; + case SSH_CHANNEL_LARVAL: + case SSH_CHANNEL_OPENING: + 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; +} + +/* + * Initiate forwarding of connections to local port "port" through the secure + * channel to host:port from remote side. + */ + +void +channel_request_local_forwarding(u_short port, const char *host, + u_short host_port, int gateway_ports) +{ + int success, ch, sock, on = 1; + struct addrinfo hints, *ai, *aitop; + char ntop[NI_MAXHOST], strport[NI_MAXSERV]; + struct linger linger; + + if (strlen(host) > sizeof(channels[0].path) - 1) + packet_disconnect("Forward host name too long."); + + /* + * 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", port); + if (getaddrinfo(NULL, strport, &hints, &aitop) != 0) + packet_disconnect("getaddrinfo: fatal error"); + + success = 0; + 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_request_local_forwarding: 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, (void *)&on, sizeof(on)); + linger.l_onoff = 1; + linger.l_linger = 5; + setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&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. */ + ch = channel_new( + "port listener", SSH_CHANNEL_PORT_LISTENER, + sock, sock, -1, + CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, + 0, xstrdup("port listener"), 1); + strlcpy(channels[ch].path, host, sizeof(channels[ch].path)); + channels[ch].host_port = host_port; + channels[ch].listening_port = port; + success = 1; + } + if (success == 0) + packet_disconnect("cannot listen port: %d", port); + freeaddrinfo(aitop); +} + +/* + * 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 payload_len; + /* 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"); + + 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++; + + /* 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); + } 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. It will send a disconnect + * message on failure, and we will never see it here. + */ + packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); + } +} + +/* + * 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_request_local_forwarding(port, hostname, host_port, gateway_ports); + + /* Free the argument string. */ + xfree(hostname); +} + +/* XXX move to aux.c */ +int +channel_connect_to(const char *host, u_short host_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", host_port); + if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) { + error("%.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("channel_connect_to: getnameinfo failed"); + continue; + } + /* Create the socket. */ + sock = socket(ai->ai_family, SOCK_STREAM, 0); + if (sock < 0) { + error("socket: %.100s", strerror(errno)); + continue; + } + /* Connect to the host/port. */ + if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) { + error("connect %.100s port %s: %.100s", ntop, strport, + strerror(errno)); + close(sock); + continue; /* fail -- try next */ + } + break; /* success */ + + } + freeaddrinfo(aitop); + if (!ai) { + error("connect %.100s port %d: failed.", host, host_port); + return -1; + } + /* success */ + return sock; +} +/* + * This is called after receiving PORT_OPEN message. This attempts to + * connect to the given host:port, and sends back CHANNEL_OPEN_CONFIRMATION + * or CHANNEL_OPEN_FAILURE. + */ + +void +channel_input_port_open(int type, int plen, void *ctxt) +{ + u_short host_port; + char *host, *originator_string; + int remote_channel, sock = -1, newch, i, denied; + unsigned int host_len, originator_len; + + /* Get remote channel number. */ + remote_channel = packet_get_int(); + + /* Get host name to connect to. */ + host = packet_get_string(&host_len); + + /* Get port to connect to. */ + host_port = packet_get_int(); + + /* Get remote originator name. */ + if (have_hostname_in_open) { + originator_string = packet_get_string(&originator_len); + originator_len += 4; /* size of packet_int */ + } else { + originator_string = xstrdup("unknown (remote did not supply name)"); + originator_len = 0; /* no originator supplied */ + } + + packet_integrity_check(plen, + 4 + 4 + host_len + 4 + originator_len, SSH_MSG_PORT_OPEN); + + /* Check if opening that port is permitted. */ + denied = 0; + if (!all_opens_permitted) { + /* Go trough all permitted ports. */ + for (i = 0; i < num_permitted_opens; i++) + if (permitted_opens[i].port_to_connect == host_port && + strcmp(permitted_opens[i].host_to_connect, host) == 0) + break; + + /* Check if we found the requested port among those permitted. */ + if (i >= num_permitted_opens) { + /* The port is not permitted. */ + log("Received request to connect to %.100s:%d, but the request was denied.", + host, host_port); + denied = 1; + } + } + sock = denied ? -1 : channel_connect_to(host, host_port); + if (sock > 0) { + /* Allocate a channel for this connection. */ + newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string); + channels[newch].remote_id = remote_channel; + + packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); + packet_put_int(remote_channel); + packet_put_int(newch); + packet_send(); + } else { + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(remote_channel); + packet_send(); + } + xfree(host); +} + +/* + * Creates an internet domain socket for listening for X11 connections. + * Returns a suitable value for the DISPLAY variable, or NULL if an error + * occurs. + */ + +#define NUM_SOCKS 10 + +char * +x11_create_display_inet(int screen_number, int x11_display_offset) +{ + 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]; + char display[512]; + char hostname[MAXHOSTNAMELEN]; + + 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 = AI_PASSIVE; /* XXX loopback only ? */ + 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 NULL; + } + 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 NULL; + } + if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) { + debug("bind port %d: %.100s", port, strerror(errno)); + shutdown(sock, SHUT_RDWR); + close(sock); + for (n = 0; n < num_socks; n++) { + shutdown(socks[n], SHUT_RDWR); + close(socks[n]); + } + num_socks = 0; + break; + } + socks[num_socks++] = sock; + if (num_socks == NUM_SOCKS) + break; + } + if (num_socks > 0) + break; + } + if (display_number >= MAX_DISPLAYS) { + error("Failed to allocate internet-domain X11 display socket."); + return NULL; + } + /* 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)); + shutdown(sock, SHUT_RDWR); + close(sock); + return NULL; + } + } + + /* Set up a suitable value for the DISPLAY variable. */ + if (gethostname(hostname, sizeof(hostname)) < 0) + fatal("gethostname: %.100s", strerror(errno)); + snprintf(display, sizeof display, "%.400s:%d.%d", hostname, + display_number, screen_number); + + /* Allocate a channel for each socket. */ + for (n = 0; n < num_socks; n++) { + sock = socks[n]; + (void) 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); + } + + /* Return a suitable value for the DISPLAY environment variable. */ + return xstrdup(display); +} + +#ifndef X_UNIX_PATH +#define X_UNIX_PATH "/tmp/.X11-unix/X" +#endif + +static +int +connect_local_xsocket(unsigned int dnr) +{ + static const char *const x_sockets[] = { + X_UNIX_PATH "%u", + "/var/X/.X11-unix/X" "%u", + "/usr/spool/sockets/X11/" "%u", + NULL + }; + int sock; + struct sockaddr_un addr; + const char *const * path; + + for (path = x_sockets; *path; ++path) { + 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, 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. + */ + strncpy(buf, display, sizeof(buf)); + buf[sizeof(buf) - 1] = 0; + 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; + } + 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, int plen, void *ctxt) +{ + int remote_channel, sock = 0, newch; + char *remote_host; + unsigned int remote_len; + + /* Get remote channel number. */ + remote_channel = packet_get_int(); + + /* Get remote originator name. */ + if (have_hostname_in_open) { + remote_host = packet_get_string(&remote_len); + remote_len += 4; + } else { + remote_host = xstrdup("unknown (remote did not supply name)"); + remote_len = 0; + } + + debug("Received X11 open request."); + packet_integrity_check(plen, 4 + remote_len, SSH_SMSG_X11_OPEN); + + /* Obtain a connection to the real X display. */ + sock = x11_connect_display(); + if (sock == -1) { + /* Send refusal to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(remote_channel); + packet_send(); + } else { + /* Allocate a channel for this connection. */ + newch = channel_allocate( + (x11_saved_proto == NULL) ? + SSH_CHANNEL_OPEN : SSH_CHANNEL_X11_OPEN, + sock, remote_host); + channels[newch].remote_id = remote_channel; + + /* Send a confirmation to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); + packet_put_int(remote_channel); + packet_put_int(newch); + packet_send(); + } +} + +/* dummy protocol handler that denies SSH-1 requests (agent/x11) */ +void +deny_input_open(int type, int plen, 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 plen %d", type, plen); + 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. + */ + +void +x11_request_forwarding_with_spoofing(int client_session_id, + const char *proto, const char *data) +{ + unsigned int data_len = (unsigned int) strlen(data) / 2; + unsigned int i, value; + 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. */ + new_data = xmalloc(2 * data_len + 1); + for (i = 0; i < data_len; i++) + sprintf(new_data + 2 * i, "%02x", (unsigned 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); +} + +/* Sends a message to the server to request authentication fd forwarding. */ + +void +auth_request_forwarding() +{ + 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() +{ + return channel_forwarded_auth_socket_name; +} + +/* removes the agent forwarding socket */ + +void +cleanup_socket(void) +{ + remove(channel_forwarded_auth_socket_name); + rmdir(channel_forwarded_auth_socket_dir); +} + +/* + * 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) +{ + int sock, newch; + struct sockaddr_un sunaddr; + + if (auth_get_socket_name() != NULL) + fatal("Protocol error: authentication forwarding requested twice."); + + /* Temporarily drop privileged uid for mkdir/bind. */ + temporarily_use_uid(pw->pw_uid); + + /* Allocate a buffer for the socket name, and format the name. */ + channel_forwarded_auth_socket_name = xmalloc(MAX_SOCKET_NAME); + channel_forwarded_auth_socket_dir = xmalloc(MAX_SOCKET_NAME); + strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME); + + /* Create private directory for socket */ + if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) { + packet_send_debug("Agent forwarding disabled: mkdtemp() failed: %.100s", + strerror(errno)); + restore_uid(); + xfree(channel_forwarded_auth_socket_name); + xfree(channel_forwarded_auth_socket_dir); + channel_forwarded_auth_socket_name = NULL; + channel_forwarded_auth_socket_dir = NULL; + return 0; + } + snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d", + channel_forwarded_auth_socket_dir, (int) getpid()); + + if (atexit(cleanup_socket) < 0) { + int saved = errno; + cleanup_socket(); + packet_disconnect("socket: %.100s", strerror(saved)); + } + /* 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; + strncpy(sunaddr.sun_path, channel_forwarded_auth_socket_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. */ + newch = channel_allocate(SSH_CHANNEL_AUTH_SOCKET, sock, + xstrdup("auth socket")); + strlcpy(channels[newch].path, channel_forwarded_auth_socket_name, + sizeof(channels[newch].path)); + return 1; +} + +/* This is called to process an SSH_SMSG_AGENT_OPEN message. */ + +void +auth_input_open_request(int type, int plen, void *ctxt) +{ + int remch, sock, newch; + char *dummyname; + + packet_integrity_check(plen, 4, type); + + /* Read the remote channel number from the message. */ + remch = packet_get_int(); + + /* + * 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) { + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(remch); + packet_send(); + return; + } + debug("Forwarding authentication connection."); + + /* + * Dummy host name. This will be freed when the channel is freed; it + * will still be valid in the packet_put_string below since the + * channel cannot yet be freed at that point. + */ + dummyname = xstrdup("authentication agent connection"); + + newch = channel_allocate(SSH_CHANNEL_OPEN, sock, dummyname); + channels[newch].remote_id = remch; + + /* Send a confirmation to the remote host. */ + packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION); + packet_put_int(remch); + packet_put_int(newch); + packet_send(); +} + +void +channel_start_open(int id) +{ + Channel *c = channel_lookup(id); + if (c == NULL) { + log("channel_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); +} +void +channel_open(int id) +{ + /* XXX REMOVE ME */ + channel_start_open(id); + packet_send(); +} +void +channel_request(int id, char *service, int wantconfirm) +{ + channel_request_start(id, service, wantconfirm); + packet_send(); + debug("channel request %d: %s", id, service) ; +} +void +channel_request_start(int id, char *service, int wantconfirm) +{ + Channel *c = channel_lookup(id); + if (c == NULL) { + log("channel_request: %d: bad id", id); + return; + } + packet_start(SSH2_MSG_CHANNEL_REQUEST); + packet_put_int(c->remote_id); + packet_put_cstring(service); + packet_put_char(wantconfirm); +} +void +channel_register_callback(int id, int mtype, channel_callback_fn *fn, void *arg) +{ + Channel *c = channel_lookup(id); + if (c == NULL) { + log("channel_register_callback: %d: bad id", id); + return; + } + c->cb_event = mtype; + c->cb_fn = fn; + c->cb_arg = arg; +} +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->dettach_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->dettach_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) +{ + 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; + /* XXX window size? */ + c->local_window = c->local_window_max = c->local_maxpacket * 2; + packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST); + packet_put_int(c->remote_id); + packet_put_int(c->local_window); + packet_send(); +} |
