1 /* $OpenBSD: channels.h,v 1.133 2020/01/25 22:49:38 djm Exp $ */ 2 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 */ 14 /* 15 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #ifndef CHANNEL_H 39 #define CHANNEL_H 40 41 /* Definitions for channel types. */ 42 #define SSH_CHANNEL_X11_LISTENER 1 /* Listening for inet X11 conn. */ 43 #define SSH_CHANNEL_PORT_LISTENER 2 /* Listening on a port. */ 44 #define SSH_CHANNEL_OPENING 3 /* waiting for confirmation */ 45 #define SSH_CHANNEL_OPEN 4 /* normal open two-way channel */ 46 #define SSH_CHANNEL_CLOSED 5 /* waiting for close confirmation */ 47 #define SSH_CHANNEL_AUTH_SOCKET 6 /* authentication socket */ 48 #define SSH_CHANNEL_X11_OPEN 7 /* reading first X11 packet */ 49 #define SSH_CHANNEL_LARVAL 10 /* larval session */ 50 #define SSH_CHANNEL_RPORT_LISTENER 11 /* Listening to a R-style port */ 51 #define SSH_CHANNEL_CONNECTING 12 52 #define SSH_CHANNEL_DYNAMIC 13 53 #define SSH_CHANNEL_ZOMBIE 14 /* Almost dead. */ 54 #define SSH_CHANNEL_MUX_LISTENER 15 /* Listener for mux conn. */ 55 #define SSH_CHANNEL_MUX_CLIENT 16 /* Conn. to mux slave */ 56 #define SSH_CHANNEL_ABANDONED 17 /* Abandoned session, eg mux */ 57 #define SSH_CHANNEL_UNIX_LISTENER 18 /* Listening on a domain socket. */ 58 #define SSH_CHANNEL_RUNIX_LISTENER 19 /* Listening to a R-style domain socket. */ 59 #define SSH_CHANNEL_MUX_PROXY 20 /* proxy channel for mux-slave */ 60 #define SSH_CHANNEL_RDYNAMIC_OPEN 21 /* reverse SOCKS, parsing request */ 61 #define SSH_CHANNEL_RDYNAMIC_FINISH 22 /* reverse SOCKS, finishing connect */ 62 #define SSH_CHANNEL_MAX_TYPE 23 63 64 #define CHANNEL_CANCEL_PORT_STATIC -1 65 66 /* TCP forwarding */ 67 #define FORWARD_DENY 0 68 #define FORWARD_REMOTE (1) 69 #define FORWARD_LOCAL (1<<1) 70 #define FORWARD_ALLOW (FORWARD_REMOTE|FORWARD_LOCAL) 71 72 #define FORWARD_ADM 0x100 73 #define FORWARD_USER 0x101 74 75 struct ssh; 76 struct Channel; 77 typedef struct Channel Channel; 78 struct fwd_perm_list; 79 80 typedef void channel_open_fn(struct ssh *, int, int, void *); 81 typedef void channel_callback_fn(struct ssh *, int, void *); 82 typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int); 83 typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 84 typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 85 u_char **, size_t *); 86 87 /* Channel success/failure callbacks */ 88 typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 89 typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 90 struct channel_confirm { 91 TAILQ_ENTRY(channel_confirm) entry; 92 channel_confirm_cb *cb; 93 channel_confirm_abandon_cb *abandon_cb; 94 void *ctx; 95 }; 96 TAILQ_HEAD(channel_confirms, channel_confirm); 97 98 /* Context for non-blocking connects */ 99 struct channel_connect { 100 char *host; 101 int port; 102 struct addrinfo *ai, *aitop; 103 }; 104 105 /* Callbacks for mux channels back into client-specific code */ 106 typedef int mux_callback_fn(struct ssh *, struct Channel *); 107 108 /* 109 * NB. channel IDs on the wire and in c->remote_id are uint32, but local 110 * channel IDs (e.g. c->self) only ever use the int32 subset of this range, 111 * because we use local channel ID -1 for housekeeping. Remote channels have 112 * a dedicated "have_remote_id" flag to indicate their validity. 113 */ 114 115 struct Channel { 116 int type; /* channel type/state */ 117 118 int self; /* my own channel identifier */ 119 uint32_t remote_id; /* channel identifier for remote peer */ 120 int have_remote_id; /* non-zero if remote_id is valid */ 121 122 u_int istate; /* input from channel (state of receive half) */ 123 u_int ostate; /* output to channel (state of transmit half) */ 124 int flags; /* close sent/rcvd */ 125 int rfd; /* read fd */ 126 int wfd; /* write fd */ 127 int efd; /* extended fd */ 128 int sock; /* sock fd */ 129 int ctl_chan; /* control channel (multiplexed connections) */ 130 int isatty; /* rfd is a tty */ 131 #ifdef _AIX 132 int wfd_isatty; /* wfd is a tty */ 133 #endif 134 int client_tty; /* (client) TTY has been requested */ 135 int force_drain; /* force close on iEOF */ 136 time_t notbefore; /* Pause IO until deadline (time_t) */ 137 int delayed; /* post-select handlers for newly created 138 * channels are delayed until the first call 139 * to a matching pre-select handler. 140 * this way post-select handlers are not 141 * accidentally called if a FD gets reused */ 142 struct sshbuf *input; /* data read from socket, to be sent over 143 * encrypted connection */ 144 struct sshbuf *output; /* data received over encrypted connection for 145 * send on socket */ 146 struct sshbuf *extended; 147 148 char *path; 149 /* path for unix domain sockets, or host name for forwards */ 150 int listening_port; /* port being listened for forwards */ 151 char *listening_addr; /* addr being listened for forwards */ 152 int host_port; /* remote port to connect for forwards */ 153 char *remote_name; /* remote hostname */ 154 155 u_int remote_window; 156 u_int remote_maxpacket; 157 u_int local_window; 158 u_int local_window_max; 159 u_int local_consumed; 160 u_int local_maxpacket; 161 int extended_usage; 162 int single_connection; 163 164 char *ctype; /* type */ 165 166 /* callback */ 167 channel_open_fn *open_confirm; 168 void *open_confirm_ctx; 169 channel_callback_fn *detach_user; 170 int detach_close; 171 struct channel_confirms status_confirms; 172 173 /* filter */ 174 channel_infilter_fn *input_filter; 175 channel_outfilter_fn *output_filter; 176 void *filter_ctx; 177 channel_filter_cleanup_fn *filter_cleanup; 178 179 /* keep boundaries */ 180 int datagram; 181 182 /* non-blocking connect */ 183 /* XXX make this a pointer so the structure can be opaque */ 184 struct channel_connect connect_ctx; 185 186 /* multiplexing protocol hook, called for each packet received */ 187 mux_callback_fn *mux_rcb; 188 void *mux_ctx; 189 int mux_pause; 190 int mux_downstream_id; 191 }; 192 193 #define CHAN_EXTENDED_IGNORE 0 194 #define CHAN_EXTENDED_READ 1 195 #define CHAN_EXTENDED_WRITE 2 196 197 /* default window/packet sizes for tcp/x11-fwd-channel */ 198 #define CHAN_SES_PACKET_DEFAULT (32*1024) 199 #define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT) 200 #define CHAN_TCP_PACKET_DEFAULT (32*1024) 201 #define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT) 202 #define CHAN_X11_PACKET_DEFAULT (16*1024) 203 #define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 204 205 /* possible input states */ 206 #define CHAN_INPUT_OPEN 0 207 #define CHAN_INPUT_WAIT_DRAIN 1 208 #define CHAN_INPUT_WAIT_OCLOSE 2 209 #define CHAN_INPUT_CLOSED 3 210 211 /* possible output states */ 212 #define CHAN_OUTPUT_OPEN 0 213 #define CHAN_OUTPUT_WAIT_DRAIN 1 214 #define CHAN_OUTPUT_WAIT_IEOF 2 215 #define CHAN_OUTPUT_CLOSED 3 216 217 #define CHAN_CLOSE_SENT 0x01 218 #define CHAN_CLOSE_RCVD 0x02 219 #define CHAN_EOF_SENT 0x04 220 #define CHAN_EOF_RCVD 0x08 221 #define CHAN_LOCAL 0x10 222 223 /* Read buffer size */ 224 #define CHAN_RBUF (16*1024) 225 226 /* Hard limit on number of channels */ 227 #define CHANNELS_MAX_CHANNELS (16*1024) 228 229 /* check whether 'efd' is still in use */ 230 #define CHANNEL_EFD_INPUT_ACTIVE(c) \ 231 (c->extended_usage == CHAN_EXTENDED_READ && \ 232 (c->efd != -1 || \ 233 sshbuf_len(c->extended) > 0)) 234 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 235 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 236 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 237 sshbuf_len(c->extended) > 0)) 238 239 /* Add channel management structures to SSH transport instance */ 240 void channel_init_channels(struct ssh *ssh); 241 242 /* channel management */ 243 244 Channel *channel_by_id(struct ssh *, int); 245 Channel *channel_by_remote_id(struct ssh *, u_int); 246 Channel *channel_lookup(struct ssh *, int); 247 Channel *channel_new(struct ssh *, char *, int, int, int, int, 248 u_int, u_int, int, char *, int); 249 void channel_set_fds(struct ssh *, int, int, int, int, int, 250 int, int, u_int); 251 void channel_free(struct ssh *, Channel *); 252 void channel_free_all(struct ssh *); 253 void channel_stop_listening(struct ssh *); 254 255 void channel_send_open(struct ssh *, int); 256 void channel_request_start(struct ssh *, int, char *, int); 257 void channel_register_cleanup(struct ssh *, int, 258 channel_callback_fn *, int); 259 void channel_register_open_confirm(struct ssh *, int, 260 channel_open_fn *, void *); 261 void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 262 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 263 void channel_register_status_confirm(struct ssh *, int, 264 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 265 void channel_cancel_cleanup(struct ssh *, int); 266 int channel_close_fd(struct ssh *, int *); 267 void channel_send_window_changes(struct ssh *); 268 269 /* mux proxy support */ 270 271 int channel_proxy_downstream(struct ssh *, Channel *mc); 272 int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 273 274 /* protocol handler */ 275 276 int channel_input_data(int, u_int32_t, struct ssh *); 277 int channel_input_extended_data(int, u_int32_t, struct ssh *); 278 int channel_input_ieof(int, u_int32_t, struct ssh *); 279 int channel_input_oclose(int, u_int32_t, struct ssh *); 280 int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 281 int channel_input_open_failure(int, u_int32_t, struct ssh *); 282 int channel_input_port_open(int, u_int32_t, struct ssh *); 283 int channel_input_window_adjust(int, u_int32_t, struct ssh *); 284 int channel_input_status_confirm(int, u_int32_t, struct ssh *); 285 286 /* file descriptor handling (read/write) */ 287 288 void channel_prepare_select(struct ssh *, fd_set **, fd_set **, int *, 289 u_int*, time_t*); 290 void channel_after_select(struct ssh *, fd_set *, fd_set *); 291 void channel_output_poll(struct ssh *); 292 293 int channel_not_very_much_buffered_data(struct ssh *); 294 void channel_close_all(struct ssh *); 295 int channel_still_open(struct ssh *); 296 const char *channel_format_extended_usage(const Channel *); 297 char *channel_open_message(struct ssh *); 298 int channel_find_open(struct ssh *); 299 300 /* tcp forwarding */ 301 struct Forward; 302 struct ForwardOptions; 303 void channel_set_af(struct ssh *, int af); 304 void channel_permit_all(struct ssh *, int); 305 void channel_add_permission(struct ssh *, int, int, char *, int); 306 void channel_clear_permission(struct ssh *, int, int); 307 void channel_disable_admin(struct ssh *, int); 308 void channel_update_permission(struct ssh *, int, int); 309 Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 310 char *, char *, int *, const char **); 311 Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *); 312 Channel *channel_connect_stdio_fwd(struct ssh *, const char*, 313 u_short, int, int); 314 Channel *channel_connect_by_listen_address(struct ssh *, const char *, 315 u_short, char *, char *); 316 Channel *channel_connect_by_listen_path(struct ssh *, const char *, 317 char *, char *); 318 int channel_request_remote_forwarding(struct ssh *, struct Forward *); 319 int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 320 struct ForwardOptions *); 321 int channel_request_rforward_cancel(struct ssh *, struct Forward *); 322 int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 323 int *, struct ForwardOptions *); 324 int channel_cancel_rport_listener(struct ssh *, struct Forward *); 325 int channel_cancel_lport_listener(struct ssh *, struct Forward *, 326 int, struct ForwardOptions *); 327 int permitopen_port(const char *); 328 329 /* x11 forwarding */ 330 331 void channel_set_x11_refuse_time(struct ssh *, u_int); 332 int x11_connect_display(struct ssh *); 333 int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 334 void x11_request_forwarding_with_spoofing(struct ssh *, int, 335 const char *, const char *, const char *, int); 336 337 /* channel close */ 338 339 int chan_is_dead(struct ssh *, Channel *, int); 340 void chan_mark_dead(struct ssh *, Channel *); 341 342 /* channel events */ 343 344 void chan_rcvd_oclose(struct ssh *, Channel *); 345 void chan_rcvd_eow(struct ssh *, Channel *); 346 void chan_read_failed(struct ssh *, Channel *); 347 void chan_ibuf_empty(struct ssh *, Channel *); 348 void chan_rcvd_ieof(struct ssh *, Channel *); 349 void chan_write_failed(struct ssh *, Channel *); 350 void chan_obuf_empty(struct ssh *, Channel *); 351 352 #endif 353