1 /* $OpenBSD: channels.h,v 1.138 2021/05/19 01:24:05 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 client */ 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-client */ 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 /* nonblocking flags for channel_new */ 67 #define CHANNEL_NONBLOCK_LEAVE 0 /* don't modify non-blocking state */ 68 #define CHANNEL_NONBLOCK_SET 1 /* set non-blocking state */ 69 #define CHANNEL_NONBLOCK_STDIO 2 /* set non-blocking and restore on close */ 70 71 /* c->restore_block mask flags */ 72 #define CHANNEL_RESTORE_RFD 0x01 73 #define CHANNEL_RESTORE_WFD 0x02 74 #define CHANNEL_RESTORE_EFD 0x04 75 76 /* TCP forwarding */ 77 #define FORWARD_DENY 0 78 #define FORWARD_REMOTE (1) 79 #define FORWARD_LOCAL (1<<1) 80 #define FORWARD_ALLOW (FORWARD_REMOTE|FORWARD_LOCAL) 81 82 #define FORWARD_ADM 0x100 83 #define FORWARD_USER 0x101 84 85 struct ssh; 86 struct Channel; 87 typedef struct Channel Channel; 88 struct fwd_perm_list; 89 90 typedef void channel_open_fn(struct ssh *, int, int, void *); 91 typedef void channel_callback_fn(struct ssh *, int, void *); 92 typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int); 93 typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 94 typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 95 u_char **, size_t *); 96 97 /* Channel success/failure callbacks */ 98 typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 99 typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 100 struct channel_confirm { 101 TAILQ_ENTRY(channel_confirm) entry; 102 channel_confirm_cb *cb; 103 channel_confirm_abandon_cb *abandon_cb; 104 void *ctx; 105 }; 106 TAILQ_HEAD(channel_confirms, channel_confirm); 107 108 /* Context for non-blocking connects */ 109 struct channel_connect { 110 char *host; 111 int port; 112 struct addrinfo *ai, *aitop; 113 }; 114 115 /* Callbacks for mux channels back into client-specific code */ 116 typedef int mux_callback_fn(struct ssh *, struct Channel *); 117 118 /* 119 * NB. channel IDs on the wire and in c->remote_id are uint32, but local 120 * channel IDs (e.g. c->self) only ever use the int32 subset of this range, 121 * because we use local channel ID -1 for housekeeping. Remote channels have 122 * a dedicated "have_remote_id" flag to indicate their validity. 123 */ 124 125 struct Channel { 126 int type; /* channel type/state */ 127 128 int self; /* my own channel identifier */ 129 uint32_t remote_id; /* channel identifier for remote peer */ 130 int have_remote_id; /* non-zero if remote_id is valid */ 131 132 u_int istate; /* input from channel (state of receive half) */ 133 u_int ostate; /* output to channel (state of transmit half) */ 134 int flags; /* close sent/rcvd */ 135 int rfd; /* read fd */ 136 int wfd; /* write fd */ 137 int efd; /* extended fd */ 138 int sock; /* sock fd */ 139 int ctl_chan; /* control channel (multiplexed connections) */ 140 int isatty; /* rfd is a tty */ 141 #ifdef _AIX 142 int wfd_isatty; /* wfd is a tty */ 143 #endif 144 int client_tty; /* (client) TTY has been requested */ 145 int force_drain; /* force close on iEOF */ 146 time_t notbefore; /* Pause IO until deadline (time_t) */ 147 int delayed; /* post-select handlers for newly created 148 * channels are delayed until the first call 149 * to a matching pre-select handler. 150 * this way post-select handlers are not 151 * accidentally called if a FD gets reused */ 152 int restore_block; /* fd mask to restore blocking status */ 153 struct sshbuf *input; /* data read from socket, to be sent over 154 * encrypted connection */ 155 struct sshbuf *output; /* data received over encrypted connection for 156 * send on socket */ 157 struct sshbuf *extended; 158 159 char *path; 160 /* path for unix domain sockets, or host name for forwards */ 161 int listening_port; /* port being listened for forwards */ 162 char *listening_addr; /* addr being listened for forwards */ 163 int host_port; /* remote port to connect for forwards */ 164 char *remote_name; /* remote hostname */ 165 166 u_int remote_window; 167 u_int remote_maxpacket; 168 u_int local_window; 169 u_int local_window_max; 170 u_int local_consumed; 171 u_int local_maxpacket; 172 int extended_usage; 173 int single_connection; 174 175 char *ctype; /* type */ 176 177 /* callback */ 178 channel_open_fn *open_confirm; 179 void *open_confirm_ctx; 180 channel_callback_fn *detach_user; 181 int detach_close; 182 struct channel_confirms status_confirms; 183 184 /* filter */ 185 channel_infilter_fn *input_filter; 186 channel_outfilter_fn *output_filter; 187 void *filter_ctx; 188 channel_filter_cleanup_fn *filter_cleanup; 189 190 /* keep boundaries */ 191 int datagram; 192 193 /* non-blocking connect */ 194 /* XXX make this a pointer so the structure can be opaque */ 195 struct channel_connect connect_ctx; 196 197 /* multiplexing protocol hook, called for each packet received */ 198 mux_callback_fn *mux_rcb; 199 void *mux_ctx; 200 int mux_pause; 201 int mux_downstream_id; 202 }; 203 204 #define CHAN_EXTENDED_IGNORE 0 205 #define CHAN_EXTENDED_READ 1 206 #define CHAN_EXTENDED_WRITE 2 207 208 /* default window/packet sizes for tcp/x11-fwd-channel */ 209 #define CHAN_SES_PACKET_DEFAULT (32*1024) 210 #define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT) 211 #define CHAN_TCP_PACKET_DEFAULT (32*1024) 212 #define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT) 213 #define CHAN_X11_PACKET_DEFAULT (16*1024) 214 #define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 215 216 /* possible input states */ 217 #define CHAN_INPUT_OPEN 0 218 #define CHAN_INPUT_WAIT_DRAIN 1 219 #define CHAN_INPUT_WAIT_OCLOSE 2 220 #define CHAN_INPUT_CLOSED 3 221 222 /* possible output states */ 223 #define CHAN_OUTPUT_OPEN 0 224 #define CHAN_OUTPUT_WAIT_DRAIN 1 225 #define CHAN_OUTPUT_WAIT_IEOF 2 226 #define CHAN_OUTPUT_CLOSED 3 227 228 #define CHAN_CLOSE_SENT 0x01 229 #define CHAN_CLOSE_RCVD 0x02 230 #define CHAN_EOF_SENT 0x04 231 #define CHAN_EOF_RCVD 0x08 232 #define CHAN_LOCAL 0x10 233 234 /* Read buffer size */ 235 #define CHAN_RBUF (16*1024) 236 237 /* Maximum channel input buffer size */ 238 #define CHAN_INPUT_MAX (16*1024*1024) 239 240 /* Hard limit on number of channels */ 241 #define CHANNELS_MAX_CHANNELS (16*1024) 242 243 /* check whether 'efd' is still in use */ 244 #define CHANNEL_EFD_INPUT_ACTIVE(c) \ 245 (c->extended_usage == CHAN_EXTENDED_READ && \ 246 (c->efd != -1 || \ 247 sshbuf_len(c->extended) > 0)) 248 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 249 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 250 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 251 sshbuf_len(c->extended) > 0)) 252 253 /* Add channel management structures to SSH transport instance */ 254 void channel_init_channels(struct ssh *ssh); 255 256 /* channel management */ 257 258 Channel *channel_by_id(struct ssh *, int); 259 Channel *channel_by_remote_id(struct ssh *, u_int); 260 Channel *channel_lookup(struct ssh *, int); 261 Channel *channel_new(struct ssh *, char *, int, int, int, int, 262 u_int, u_int, int, char *, int); 263 void channel_set_fds(struct ssh *, int, int, int, int, int, 264 int, int, u_int); 265 void channel_free(struct ssh *, Channel *); 266 void channel_free_all(struct ssh *); 267 void channel_stop_listening(struct ssh *); 268 269 void channel_send_open(struct ssh *, int); 270 void channel_request_start(struct ssh *, int, char *, int); 271 void channel_register_cleanup(struct ssh *, int, 272 channel_callback_fn *, int); 273 void channel_register_open_confirm(struct ssh *, int, 274 channel_open_fn *, void *); 275 void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 276 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 277 void channel_register_status_confirm(struct ssh *, int, 278 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 279 void channel_cancel_cleanup(struct ssh *, int); 280 int channel_close_fd(struct ssh *, Channel *, int *); 281 void channel_send_window_changes(struct ssh *); 282 283 /* mux proxy support */ 284 285 int channel_proxy_downstream(struct ssh *, Channel *mc); 286 int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 287 288 /* protocol handler */ 289 290 int channel_input_data(int, u_int32_t, struct ssh *); 291 int channel_input_extended_data(int, u_int32_t, struct ssh *); 292 int channel_input_ieof(int, u_int32_t, struct ssh *); 293 int channel_input_oclose(int, u_int32_t, struct ssh *); 294 int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 295 int channel_input_open_failure(int, u_int32_t, struct ssh *); 296 int channel_input_port_open(int, u_int32_t, struct ssh *); 297 int channel_input_window_adjust(int, u_int32_t, struct ssh *); 298 int channel_input_status_confirm(int, u_int32_t, struct ssh *); 299 300 /* file descriptor handling (read/write) */ 301 302 void channel_prepare_select(struct ssh *, fd_set **, fd_set **, int *, 303 u_int*, time_t*); 304 void channel_after_select(struct ssh *, fd_set *, fd_set *); 305 void channel_output_poll(struct ssh *); 306 307 int channel_not_very_much_buffered_data(struct ssh *); 308 void channel_close_all(struct ssh *); 309 int channel_still_open(struct ssh *); 310 const char *channel_format_extended_usage(const Channel *); 311 char *channel_open_message(struct ssh *); 312 int channel_find_open(struct ssh *); 313 314 /* tcp forwarding */ 315 struct Forward; 316 struct ForwardOptions; 317 void channel_set_af(struct ssh *, int af); 318 void channel_permit_all(struct ssh *, int); 319 void channel_add_permission(struct ssh *, int, int, char *, int); 320 void channel_clear_permission(struct ssh *, int, int); 321 void channel_disable_admin(struct ssh *, int); 322 void channel_update_permission(struct ssh *, int, int); 323 Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 324 char *, char *, int *, const char **); 325 Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *); 326 Channel *channel_connect_stdio_fwd(struct ssh *, const char*, 327 u_short, int, int, int); 328 Channel *channel_connect_by_listen_address(struct ssh *, const char *, 329 u_short, char *, char *); 330 Channel *channel_connect_by_listen_path(struct ssh *, const char *, 331 char *, char *); 332 int channel_request_remote_forwarding(struct ssh *, struct Forward *); 333 int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 334 struct ForwardOptions *); 335 int channel_request_rforward_cancel(struct ssh *, struct Forward *); 336 int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 337 int *, struct ForwardOptions *); 338 int channel_cancel_rport_listener(struct ssh *, struct Forward *); 339 int channel_cancel_lport_listener(struct ssh *, struct Forward *, 340 int, struct ForwardOptions *); 341 int permitopen_port(const char *); 342 343 /* x11 forwarding */ 344 345 void channel_set_x11_refuse_time(struct ssh *, u_int); 346 int x11_connect_display(struct ssh *); 347 int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 348 void x11_request_forwarding_with_spoofing(struct ssh *, int, 349 const char *, const char *, const char *, int); 350 351 /* channel close */ 352 353 int chan_is_dead(struct ssh *, Channel *, int); 354 void chan_mark_dead(struct ssh *, Channel *); 355 356 /* channel events */ 357 358 void chan_rcvd_oclose(struct ssh *, Channel *); 359 void chan_rcvd_eow(struct ssh *, Channel *); 360 void chan_read_failed(struct ssh *, Channel *); 361 void chan_ibuf_empty(struct ssh *, Channel *); 362 void chan_rcvd_ieof(struct ssh *, Channel *); 363 void chan_write_failed(struct ssh *, Channel *); 364 void chan_obuf_empty(struct ssh *, Channel *); 365 366 #endif 367