| /* |
| * |
| * channels.c |
| * |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * |
| * Created: Fri Mar 24 16:35:24 1995 ylo |
| * |
| * 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. |
| * |
| */ |
| |
| #include "includes.h" |
| RCSID("$Id: channels.c,v 1.9 1999/12/06 00:47:29 damien Exp $"); |
| |
| #include "ssh.h" |
| #include "packet.h" |
| #include "xmalloc.h" |
| #include "buffer.h" |
| #include "authfd.h" |
| #include "uidswap.h" |
| #include "readconf.h" |
| #include "servconf.h" |
| |
| #include "channels.h" |
| #include "nchan.h" |
| #include "compat.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; /* Host name. */ |
| u_short port; /* 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; |
| } |
| |
| /* |
| * Allocate a new channel object and set its type and socket. This will cause |
| * remote_name to be freed. |
| */ |
| |
| int |
| channel_allocate(int type, int sock, char *remote_name) |
| { |
| int i, found; |
| Channel *c; |
| |
| /* Update the maximum file descriptor value. */ |
| if (sock > channel_max_fd_value) |
| channel_max_fd_value = sock; |
| /* XXX set close-on-exec -markus */ |
| |
| /* 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].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; |
| debug("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); |
| chan_init_iostates(c); |
| c->self = found; |
| c->type = type; |
| c->sock = sock; |
| c->remote_id = -1; |
| c->remote_name = remote_name; |
| debug("channel %d: new [%s]", found, remote_name); |
| return found; |
| } |
| |
| /* Free the channel and close its socket. */ |
| |
| void |
| channel_free(int channel) |
| { |
| if (channel < 0 || channel >= channels_alloc || |
| channels[channel].type == SSH_CHANNEL_FREE) |
| packet_disconnect("channel free: bad local channel %d", channel); |
| |
| if (compat13) |
| shutdown(channels[channel].sock, SHUT_RDWR); |
| close(channels[channel].sock); |
| buffer_free(&channels[channel].input); |
| buffer_free(&channels[channel].output); |
| channels[channel].type = SSH_CHANNEL_FREE; |
| if (channels[channel].remote_name) { |
| xfree(channels[channel].remote_name); |
| channels[channel].remote_name = NULL; |
| } |
| } |
| |
| /* |
| * This is called just before select() to add any bits relevant to channels |
| * in the select bitmasks. |
| */ |
| |
| void |
| channel_prepare_select(fd_set * readset, fd_set * writeset) |
| { |
| int i; |
| Channel *ch; |
| unsigned char *ucp; |
| unsigned int proto_len, data_len; |
| |
| for (i = 0; i < channels_alloc; i++) { |
| ch = &channels[i]; |
| redo: |
| switch (ch->type) { |
| case SSH_CHANNEL_X11_LISTENER: |
| case SSH_CHANNEL_PORT_LISTENER: |
| case SSH_CHANNEL_AUTH_SOCKET: |
| FD_SET(ch->sock, readset); |
| break; |
| |
| case SSH_CHANNEL_OPEN: |
| if (compat13) { |
| if (buffer_len(&ch->input) < packet_get_maxsize()) |
| FD_SET(ch->sock, readset); |
| if (buffer_len(&ch->output) > 0) |
| FD_SET(ch->sock, writeset); |
| break; |
| } |
| /* test whether sockets are 'alive' for read/write */ |
| if (ch->istate == CHAN_INPUT_OPEN) |
| if (buffer_len(&ch->input) < packet_get_maxsize()) |
| FD_SET(ch->sock, readset); |
| if (ch->ostate == CHAN_OUTPUT_OPEN || |
| ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) { |
| if (buffer_len(&ch->output) > 0) { |
| FD_SET(ch->sock, writeset); |
| } else if (ch->ostate == CHAN_OUTPUT_WAIT_DRAIN) { |
| chan_obuf_empty(ch); |
| } |
| } |
| break; |
| |
| case SSH_CHANNEL_INPUT_DRAINING: |
| if (!compat13) |
| fatal("cannot happen: IN_DRAIN"); |
| if (buffer_len(&ch->input) == 0) { |
| packet_start(SSH_MSG_CHANNEL_CLOSE); |
| packet_put_int(ch->remote_id); |
| packet_send(); |
| ch->type = SSH_CHANNEL_CLOSED; |
| debug("Closing channel %d after input drain.", i); |
| break; |
| } |
| break; |
| |
| case SSH_CHANNEL_OUTPUT_DRAINING: |
| if (!compat13) |
| fatal("cannot happen: OUT_DRAIN"); |
| if (buffer_len(&ch->output) == 0) { |
| channel_free(i); |
| break; |
| } |
| FD_SET(ch->sock, writeset); |
| break; |
| |
| case SSH_CHANNEL_X11_OPEN: |
| /* |
| * 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. |
| */ |
| /* Check if the fixed size part of the packet is in buffer. */ |
| if (buffer_len(&ch->output) < 12) |
| break; |
| |
| /* Parse the lengths of variable-length fields. */ |
| ucp = (unsigned char *) buffer_ptr(&ch->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]); |
| ch->type = SSH_CHANNEL_OPEN; |
| goto reject; |
| } |
| |
| /* Check if the whole packet is in buffer. */ |
| if (buffer_len(&ch->output) < |
| 12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3)) |
| break; |
| |
| /* 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."); |
| ch->type = SSH_CHANNEL_OPEN; |
| goto reject; |
| } |
| /* 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."); |
| ch->type = SSH_CHANNEL_OPEN; |
| goto reject; |
| } |
| /* 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); |
| ch->type = SSH_CHANNEL_OPEN; |
| goto reject; |
| } |
| /* |
| * 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); |
| |
| /* Start normal processing for the channel. */ |
| ch->type = SSH_CHANNEL_OPEN; |
| goto redo; |
| |
| reject: |
| /* |
| * We have received an X11 connection that has bad |
| * authentication information. |
| */ |
| log("X11 connection rejected because of wrong authentication.\r\n"); |
| buffer_clear(&ch->input); |
| buffer_clear(&ch->output); |
| if (compat13) { |
| close(ch->sock); |
| ch->sock = -1; |
| ch->type = SSH_CHANNEL_CLOSED; |
| packet_start(SSH_MSG_CHANNEL_CLOSE); |
| packet_put_int(ch->remote_id); |
| packet_send(); |
| } else { |
| debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); |
| chan_read_failed(ch); |
| chan_write_failed(ch); |
| debug("X11 rejected %d i%d/o%d", ch->self, ch->istate, ch->ostate); |
| } |
| break; |
| |
| case SSH_CHANNEL_FREE: |
| default: |
| continue; |
| } |
| } |
| } |
| |
| /* |
| * After select, perform any appropriate operations for channels which have |
| * events pending. |
| */ |
| |
| void |
| channel_after_select(fd_set * readset, fd_set * writeset) |
| { |
| struct sockaddr addr; |
| int addrlen, newsock, i, newch, len; |
| Channel *ch; |
| char buf[16384], *remote_hostname; |
| |
| /* Loop over all channels... */ |
| for (i = 0; i < channels_alloc; i++) { |
| ch = &channels[i]; |
| switch (ch->type) { |
| case SSH_CHANNEL_X11_LISTENER: |
| /* This is our fake X11 server socket. */ |
| if (FD_ISSET(ch->sock, readset)) { |
| debug("X11 connection requested."); |
| addrlen = sizeof(addr); |
| newsock = accept(ch->sock, &addr, &addrlen); |
| if (newsock < 0) { |
| error("accept: %.100s", strerror(errno)); |
| break; |
| } |
| remote_hostname = get_remote_hostname(newsock); |
| snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", |
| remote_hostname, get_peer_port(newsock)); |
| xfree(remote_hostname); |
| newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, |
| xstrdup(buf)); |
| packet_start(SSH_SMSG_X11_OPEN); |
| packet_put_int(newch); |
| if (have_hostname_in_open) |
| packet_put_string(buf, strlen(buf)); |
| packet_send(); |
| } |
| break; |
| |
| case SSH_CHANNEL_PORT_LISTENER: |
| /* |
| * This socket is listening for connections to a |
| * forwarded TCP/IP port. |
| */ |
| if (FD_ISSET(ch->sock, readset)) { |
| debug("Connection to port %d forwarding to %.100s:%d requested.", |
| ch->listening_port, ch->path, ch->host_port); |
| addrlen = sizeof(addr); |
| newsock = accept(ch->sock, &addr, &addrlen); |
| if (newsock < 0) { |
| error("accept: %.100s", strerror(errno)); |
| break; |
| } |
| remote_hostname = get_remote_hostname(newsock); |
| snprintf(buf, sizeof buf, "listen port %d:%.100s:%d, connect from %.200s:%d", |
| ch->listening_port, ch->path, ch->host_port, |
| remote_hostname, get_peer_port(newsock)); |
| xfree(remote_hostname); |
| newch = channel_allocate(SSH_CHANNEL_OPENING, newsock, |
| xstrdup(buf)); |
| packet_start(SSH_MSG_PORT_OPEN); |
| packet_put_int(newch); |
| packet_put_string(ch->path, strlen(ch->path)); |
| packet_put_int(ch->host_port); |
| if (have_hostname_in_open) |
| packet_put_string(buf, strlen(buf)); |
| packet_send(); |
| } |
| break; |
| |
| case SSH_CHANNEL_AUTH_SOCKET: |
| /* |
| * This is the authentication agent socket listening |
| * for connections from clients. |
| */ |
| if (FD_ISSET(ch->sock, readset)) { |
| int nchan; |
| len = sizeof(addr); |
| newsock = accept(ch->sock, &addr, &len); |
| if (newsock < 0) { |
| error("accept from auth socket: %.100s", strerror(errno)); |
| break; |
| } |
| nchan = channel_allocate(SSH_CHANNEL_OPENING, newsock, |
| xstrdup("accepted auth socket")); |
| packet_start(SSH_SMSG_AGENT_OPEN); |
| packet_put_int(nchan); |
| packet_send(); |
| } |
| break; |
| |
| case SSH_CHANNEL_OPEN: |
| /* |
| * This is an open two-way communication channel. It |
| * is not of interest to us at this point what kind |
| * of data is being transmitted. |
| */ |
| |
| /* |
| * Read available incoming data and append it to |
| * buffer; shutdown socket, if read or write failes |
| */ |
| if (FD_ISSET(ch->sock, readset)) { |
| len = read(ch->sock, buf, sizeof(buf)); |
| if (len <= 0) { |
| if (compat13) { |
| buffer_consume(&ch->output, buffer_len(&ch->output)); |
| ch->type = SSH_CHANNEL_INPUT_DRAINING; |
| debug("Channel %d status set to input draining.", i); |
| } else { |
| chan_read_failed(ch); |
| } |
| break; |
| } |
| buffer_append(&ch->input, buf, len); |
| } |
| /* Send buffered output data to the socket. */ |
| if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) { |
| len = write(ch->sock, buffer_ptr(&ch->output), |
| buffer_len(&ch->output)); |
| if (len <= 0) { |
| if (compat13) { |
| buffer_consume(&ch->output, buffer_len(&ch->output)); |
| debug("Channel %d status set to input draining.", i); |
| ch->type = SSH_CHANNEL_INPUT_DRAINING; |
| } else { |
| chan_write_failed(ch); |
| } |
| break; |
| } |
| buffer_consume(&ch->output, len); |
| } |
| break; |
| |
| case SSH_CHANNEL_OUTPUT_DRAINING: |
| if (!compat13) |
| fatal("cannot happen: OUT_DRAIN"); |
| /* Send buffered output data to the socket. */ |
| if (FD_ISSET(ch->sock, writeset) && buffer_len(&ch->output) > 0) { |
| len = write(ch->sock, buffer_ptr(&ch->output), |
| buffer_len(&ch->output)); |
| if (len <= 0) |
| buffer_consume(&ch->output, buffer_len(&ch->output)); |
| else |
| buffer_consume(&ch->output, len); |
| } |
| break; |
| |
| case SSH_CHANNEL_X11_OPEN: |
| case SSH_CHANNEL_FREE: |
| default: |
| continue; |
| } |
| } |
| } |
| |
| /* If there is data to send to the connection, send some of it now. */ |
| |
| void |
| channel_output_poll() |
| { |
| int len, i; |
| Channel *ch; |
| |
| for (i = 0; i < channels_alloc; i++) { |
| ch = &channels[i]; |
| /* We are only interested in channels that can have buffered incoming data. */ |
| if (ch->type != SSH_CHANNEL_OPEN && |
| ch->type != SSH_CHANNEL_INPUT_DRAINING) |
| continue; |
| |
| /* Get the amount of buffered data for this channel. */ |
| len = buffer_len(&ch->input); |
| if (len > 0) { |
| /* Send some data for the other side over the secure connection. */ |
| if (packet_is_interactive()) { |
| if (len > 1024) |
| len = 512; |
| } else { |
| /* Keep the packets at reasonable size. */ |
| if (len > 16384) |
| len = 16384; |
| } |
| packet_start(SSH_MSG_CHANNEL_DATA); |
| packet_put_int(ch->remote_id); |
| packet_put_string(buffer_ptr(&ch->input), len); |
| packet_send(); |
| buffer_consume(&ch->input, len); |
| } else if (ch->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(ch); |
| } |
| } |
| } |
| |
| /* |
| * 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 payload_len) |
| { |
| int channel; |
| char *data; |
| unsigned int data_len; |
| |
| /* Get the channel number and verify it. */ |
| channel = packet_get_int(); |
| if (channel < 0 || channel >= channels_alloc || |
| channels[channel].type == SSH_CHANNEL_FREE) |
| packet_disconnect("Received data for nonexistent channel %d.", channel); |
| |
| /* Ignore any data for non-open channels (might happen on close) */ |
| if (channels[channel].type != SSH_CHANNEL_OPEN && |
| channels[channel].type != SSH_CHANNEL_X11_OPEN) |
| return; |
| |
| /* Get the data. */ |
| data = packet_get_string(&data_len); |
| packet_integrity_check(payload_len, 4 + 4 + data_len, SSH_MSG_CHANNEL_DATA); |
| buffer_append(&channels[channel].output, 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 *ch; |
| |
| for (i = 0; i < channels_alloc; i++) { |
| ch = &channels[i]; |
| switch (ch->type) { |
| case SSH_CHANNEL_X11_LISTENER: |
| case SSH_CHANNEL_PORT_LISTENER: |
| case SSH_CHANNEL_AUTH_SOCKET: |
| continue; |
| case SSH_CHANNEL_OPEN: |
| if (buffer_len(&ch->input) > packet_get_maxsize()) |
| return 0; |
| if (buffer_len(&ch->output) > packet_get_maxsize()) |
| return 0; |
| continue; |
| case SSH_CHANNEL_INPUT_DRAINING: |
| case SSH_CHANNEL_OUTPUT_DRAINING: |
| case SSH_CHANNEL_X11_OPEN: |
| case SSH_CHANNEL_FREE: |
| default: |
| continue; |
| } |
| } |
| return 1; |
| } |
| |
| /* This is called after receiving CHANNEL_CLOSE/IEOF. */ |
| |
| void |
| channel_input_close() |
| { |
| int channel; |
| |
| /* Get the channel number and verify it. */ |
| channel = packet_get_int(); |
| if (channel < 0 || channel >= channels_alloc || |
| channels[channel].type == SSH_CHANNEL_FREE) |
| packet_disconnect("Received data for nonexistent channel %d.", channel); |
| |
| if (!compat13) { |
| /* proto version 1.5 overloads CLOSE with IEOF */ |
| chan_rcvd_ieof(&channels[channel]); |
| return; |
| } |
| |
| /* |
| * 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(channels[channel].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 (channels[channel].type != SSH_CHANNEL_CLOSED) { |
| /* |
| * Not a closed channel - mark it as draining, which will |
| * cause it to be freed later. |
| */ |
| buffer_consume(&channels[channel].input, |
| buffer_len(&channels[channel].input)); |
| channels[channel].type = SSH_CHANNEL_OUTPUT_DRAINING; |
| } |
| } |
| |
| /* This is called after receiving CHANNEL_CLOSE_CONFIRMATION/OCLOSE. */ |
| |
| void |
| channel_input_close_confirmation() |
| { |
| int channel; |
| |
| /* Get the channel number and verify it. */ |
| channel = packet_get_int(); |
| if (channel < 0 || channel >= channels_alloc) |
| packet_disconnect("Received close confirmation for out-of-range channel %d.", |
| channel); |
| |
| if (!compat13) { |
| /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ |
| chan_rcvd_oclose(&channels[channel]); |
| return; |
| } |
| if (channels[channel].type != SSH_CHANNEL_CLOSED) |
| packet_disconnect("Received close confirmation for non-closed channel %d (type %d).", |
| channel, channels[channel].type); |
| |
| /* Free the channel. */ |
| channel_free(channel); |
| } |
| |
| /* This is called after receiving CHANNEL_OPEN_CONFIRMATION. */ |
| |
| void |
| channel_input_open_confirmation() |
| { |
| int channel, remote_channel; |
| |
| /* Get the channel number and verify it. */ |
| channel = packet_get_int(); |
| if (channel < 0 || channel >= channels_alloc || |
| channels[channel].type != SSH_CHANNEL_OPENING) |
| packet_disconnect("Received open confirmation for non-opening channel %d.", |
| channel); |
| |
| /* Get remote side's id for this channel. */ |
| remote_channel = packet_get_int(); |
| |
| /* Record the remote channel number and mark that the channel is now open. */ |
| channels[channel].remote_id = remote_channel; |
| channels[channel].type = SSH_CHANNEL_OPEN; |
| } |
| |
| /* This is called after receiving CHANNEL_OPEN_FAILURE from the other side. */ |
| |
| void |
| channel_input_open_failure() |
| { |
| int channel; |
| |
| /* Get the channel number and verify it. */ |
| channel = packet_get_int(); |
| if (channel < 0 || channel >= channels_alloc || |
| channels[channel].type != SSH_CHANNEL_OPENING) |
| packet_disconnect("Received open failure for non-opening channel %d.", |
| channel); |
| |
| /* Free the channel. This will also close the socket. */ |
| channel_free(channel); |
| } |
| |
| /* |
| * 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 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) |
| close(channels[i].sock); |
| } |
| } |
| |
| /* 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_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_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 o%d)\r\n", |
| c->self, c->remote_name, |
| c->type, c->remote_id, c->istate, c->ostate); |
| buffer_append(&buffer, buf, strlen(buf)); |
| continue; |
| default: |
| fatal("channel_still_open: 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 ch, sock, on = 1; |
| struct sockaddr_in sin; |
| extern Options options; |
| struct linger linger; |
| |
| if (strlen(host) > sizeof(channels[0].path) - 1) |
| packet_disconnect("Forward host name too long."); |
| |
| /* Create a port to listen for the host. */ |
| sock = socket(AF_INET, SOCK_STREAM, 0); |
| if (sock < 0) |
| packet_disconnect("socket: %.100s", strerror(errno)); |
| |
| /* Initialize socket address. */ |
| memset(&sin, 0, sizeof(sin)); |
| sin.sin_family = AF_INET; |
| if (options.gateway_ports == 1) |
| sin.sin_addr.s_addr = htonl(INADDR_ANY); |
| else |
| sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK); |
| sin.sin_port = htons(port); |
| |
| /* |
| * 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)); |
| |
| /* Bind the socket to the address. */ |
| if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) |
| packet_disconnect("bind: %.100s", strerror(errno)); |
| |
| /* Start listening for connections on the socket. */ |
| if (listen(sock, 5) < 0) |
| packet_disconnect("listen: %.100s", strerror(errno)); |
| |
| /* Allocate a channel number for the socket. */ |
| ch = channel_allocate(SSH_CHANNEL_PORT_LISTENER, sock, |
| xstrdup("port listener")); |
| strcpy(channels[ch].path, host); |
| channels[ch].host_port = host_port; |
| channels[ch].listening_port = port; |
| } |
| |
| /* |
| * 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 port, const char *host, |
| u_short remote_port) |
| { |
| 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 = xstrdup(host); |
| permitted_opens[num_permitted_opens].port = remote_port; |
| num_permitted_opens++; |
| |
| /* Send the forward request to the remote side. */ |
| packet_start(SSH_CMSG_PORT_FORWARD_REQUEST); |
| packet_put_int(port); |
| packet_put_string(host, strlen(host)); |
| packet_put_int(remote_port); |
| 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) |
| { |
| 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); |
| |
| /* Free the argument string. */ |
| xfree(hostname); |
| } |
| |
| /* |
| * 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 payload_len) |
| { |
| int remote_channel, sock, newch, i; |
| u_short host_port; |
| struct sockaddr_in sin; |
| char *host, *originator_string; |
| struct hostent *hp; |
| 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(payload_len, |
| 4 + 4 + host_len + 4 + originator_len, |
| SSH_MSG_PORT_OPEN); |
| |
| /* Check if opening that port is permitted. */ |
| if (!all_opens_permitted) { |
| /* Go trough all permitted ports. */ |
| for (i = 0; i < num_permitted_opens; i++) |
| if (permitted_opens[i].port == host_port && |
| strcmp(permitted_opens[i].host, 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); |
| packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); |
| packet_put_int(remote_channel); |
| packet_send(); |
| } |
| } |
| memset(&sin, 0, sizeof(sin)); |
| sin.sin_addr.s_addr = inet_addr(host); |
| if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) { |
| /* It was a valid numeric host address. */ |
| sin.sin_family = AF_INET; |
| } else { |
| /* Look up the host address from the name servers. */ |
| hp = gethostbyname(host); |
| if (!hp) { |
| error("%.100s: unknown host.", host); |
| goto fail; |
| } |
| if (!hp->h_addr_list[0]) { |
| error("%.100s: host has no IP address.", host); |
| goto fail; |
| } |
| sin.sin_family = hp->h_addrtype; |
| memcpy(&sin.sin_addr, hp->h_addr_list[0], |
| sizeof(sin.sin_addr)); |
| } |
| sin.sin_port = htons(host_port); |
| |
| /* Create the socket. */ |
| sock = socket(sin.sin_family, SOCK_STREAM, 0); |
| if (sock < 0) { |
| error("socket: %.100s", strerror(errno)); |
| goto fail; |
| } |
| /* Connect to the host/port. */ |
| if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { |
| error("connect %.100s:%d: %.100s", host, host_port, |
| strerror(errno)); |
| close(sock); |
| goto fail; |
| } |
| /* Successful connection. */ |
| |
| /* Allocate a channel for this connection. */ |
| newch = channel_allocate(SSH_CHANNEL_OPEN, sock, originator_string); |
| 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(); |
| |
| /* Free the argument string. */ |
| xfree(host); |
| |
| return; |
| |
| fail: |
| /* Free the argument string. */ |
| xfree(host); |
| |
| /* Send refusal to the remote host. */ |
| packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); |
| packet_put_int(remote_channel); |
| packet_send(); |
| } |
| |
| /* |
| * Creates an internet domain socket for listening for X11 connections. |
| * Returns a suitable value for the DISPLAY variable, or NULL if an error |
| * occurs. |
| */ |
| |
| char * |
| x11_create_display_inet(int screen_number) |
| { |
| extern ServerOptions options; |
| int display_number, sock; |
| u_short port; |
| struct sockaddr_in sin; |
| char buf[512]; |
| char hostname[MAXHOSTNAMELEN]; |
| |
| for (display_number = options.x11_display_offset; |
| display_number < MAX_DISPLAYS; |
| display_number++) { |
| port = 6000 + display_number; |
| memset(&sin, 0, sizeof(sin)); |
| sin.sin_family = AF_INET; |
| sin.sin_addr.s_addr = htonl(INADDR_ANY); |
| sin.sin_port = htons(port); |
| |
| sock = socket(AF_INET, SOCK_STREAM, 0); |
| if (sock < 0) { |
| error("socket: %.100s", strerror(errno)); |
| return NULL; |
| } |
| if (bind(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { |
| debug("bind port %d: %.100s", port, strerror(errno)); |
| shutdown(sock, SHUT_RDWR); |
| close(sock); |
| continue; |
| } |
| break; |
| } |
| if (display_number >= MAX_DISPLAYS) { |
| error("Failed to allocate internet-domain X11 display socket."); |
| return NULL; |
| } |
| /* Start listening for connections on the socket. */ |
| 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(buf, sizeof buf, "%.400s:%d.%d", hostname, |
| display_number, screen_number); |
| |
| /* Allocate a channel for the socket. */ |
| (void) channel_allocate(SSH_CHANNEL_X11_LISTENER, sock, |
| xstrdup("X11 inet listener")); |
| |
| /* Return a suitable value for the DISPLAY environment variable. */ |
| return xstrdup(buf); |
| } |
| |
| #ifndef X_UNIX_PATH |
| #define X_UNIX_PATH "/tmp/.X11-unix/X" |
| #endif |
| |
| static |
| int |
| connect_local_xsocket(unsigned 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; |
| } |
| |
| |
| /* |
| * 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 payload_len) |
| { |
| int remote_channel, display_number, sock, newch; |
| const char *display; |
| struct sockaddr_in sin; |
| char buf[1024], *cp, *remote_host; |
| struct hostent *hp; |
| 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(payload_len, 4 + remote_len, SSH_SMSG_X11_OPEN); |
| |
| /* Try to open a socket for the local X server. */ |
| display = getenv("DISPLAY"); |
| if (!display) { |
| error("DISPLAY not set."); |
| goto fail; |
| } |
| /* |
| * 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); |
| goto fail; |
| } |
| /* Create a socket. */ |
| sock = connect_local_xsocket(display_number); |
| if (sock < 0) |
| goto fail; |
| |
| /* OK, we now have a connection to the display. */ |
| goto success; |
| } |
| /* |
| * 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); |
| goto fail; |
| } |
| *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); |
| goto fail; |
| } |
| /* Try to parse the host name as a numeric IP address. */ |
| memset(&sin, 0, sizeof(sin)); |
| sin.sin_addr.s_addr = inet_addr(buf); |
| if ((sin.sin_addr.s_addr & 0xffffffff) != 0xffffffff) { |
| /* It was a valid numeric host address. */ |
| sin.sin_family = AF_INET; |
| } else { |
| /* Not a numeric IP address. */ |
| /* Look up the host address from the name servers. */ |
| hp = gethostbyname(buf); |
| if (!hp) { |
| error("%.100s: unknown host.", buf); |
| goto fail; |
| } |
| if (!hp->h_addr_list[0]) { |
| error("%.100s: host has no IP address.", buf); |
| goto fail; |
| } |
| sin.sin_family = hp->h_addrtype; |
| memcpy(&sin.sin_addr, hp->h_addr_list[0], |
| sizeof(sin.sin_addr)); |
| } |
| /* Set port number. */ |
| sin.sin_port = htons(6000 + display_number); |
| |
| /* Create a socket. */ |
| sock = socket(sin.sin_family, SOCK_STREAM, 0); |
| if (sock < 0) { |
| error("socket: %.100s", strerror(errno)); |
| goto fail; |
| } |
| /* Connect it to the display. */ |
| if (connect(sock, (struct sockaddr *) & sin, sizeof(sin)) < 0) { |
| error("connect %.100s:%d: %.100s", buf, 6000 + display_number, |
| strerror(errno)); |
| close(sock); |
| goto fail; |
| } |
| success: |
| /* We have successfully obtained a connection to the real X display. */ |
| |
| /* Allocate a channel for this connection. */ |
| if (x11_saved_proto == NULL) |
| newch = channel_allocate(SSH_CHANNEL_OPEN, sock, remote_host); |
| else |
| newch = channel_allocate(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(); |
| |
| return; |
| |
| fail: |
| /* Send refusal to the remote host. */ |
| packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); |
| packet_put_int(remote_channel); |
| packet_send(); |
| } |
| |
| /* |
| * Requests forwarding of X11 connections, generates fake authentication |
| * data, and enables authentication spoofing. |
| */ |
| |
| void |
| x11_request_forwarding_with_spoofing(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. */ |
| packet_start(SSH_CMSG_X11_REQUEST_FORWARDING); |
| packet_put_string(proto, strlen(proto)); |
| packet_put_string(new_data, strlen(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 if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. |
| * This starts forwarding authentication requests. |
| */ |
| |
| void |
| 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_disconnect("mkdtemp: %.100s", strerror(errno)); |
| 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")); |
| strcpy(channels[newch].path, channel_forwarded_auth_socket_name); |
| } |
| |
| /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ |
| |
| void |
| auth_input_open_request() |
| { |
| int remch, sock, newch; |
| char *dummyname; |
| |
| /* 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(); |
| } |