1 /* $OpenBSD: channels.h,v 1.143 2022/05/05 00:56:58 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 u_int io_want; /* bitmask of SSH_CHAN_IO_* */ 140 u_int io_ready; /* bitmask of SSH_CHAN_IO_* */ 141 int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */ 142 int ctl_chan; /* control channel (multiplexed connections) */ 143 int isatty; /* rfd is a tty */ 144 #ifdef _AIX 145 int wfd_isatty; /* wfd is a tty */ 146 #endif 147 int client_tty; /* (client) TTY has been requested */ 148 int force_drain; /* force close on iEOF */ 149 time_t notbefore; /* Pause IO until deadline (time_t) */ 150 int delayed; /* post-IO handlers for newly created 151 * channels are delayed until the first call 152 * to a matching pre-IO handler. 153 * this way post-IO handlers are not 154 * accidentally called if a FD gets reused */ 155 int restore_block; /* fd mask to restore blocking status */ 156 struct sshbuf *input; /* data read from socket, to be sent over 157 * encrypted connection */ 158 struct sshbuf *output; /* data received over encrypted connection for 159 * send on socket */ 160 struct sshbuf *extended; 161 162 char *path; 163 /* path for unix domain sockets, or host name for forwards */ 164 int listening_port; /* port being listened for forwards */ 165 char *listening_addr; /* addr being listened for forwards */ 166 int host_port; /* remote port to connect for forwards */ 167 char *remote_name; /* remote hostname */ 168 169 u_int remote_window; 170 u_int remote_maxpacket; 171 u_int local_window; 172 u_int local_window_max; 173 u_int local_consumed; 174 u_int local_maxpacket; 175 int extended_usage; 176 int single_connection; 177 178 char *ctype; /* type */ 179 180 /* callback */ 181 channel_open_fn *open_confirm; 182 void *open_confirm_ctx; 183 channel_callback_fn *detach_user; 184 int detach_close; 185 struct channel_confirms status_confirms; 186 187 /* filter */ 188 channel_infilter_fn *input_filter; 189 channel_outfilter_fn *output_filter; 190 void *filter_ctx; 191 channel_filter_cleanup_fn *filter_cleanup; 192 193 /* keep boundaries */ 194 int datagram; 195 196 /* non-blocking connect */ 197 /* XXX make this a pointer so the structure can be opaque */ 198 struct channel_connect connect_ctx; 199 200 /* multiplexing protocol hook, called for each packet received */ 201 mux_callback_fn *mux_rcb; 202 void *mux_ctx; 203 int mux_pause; 204 int mux_downstream_id; 205 }; 206 207 #define CHAN_EXTENDED_IGNORE 0 208 #define CHAN_EXTENDED_READ 1 209 #define CHAN_EXTENDED_WRITE 2 210 211 /* default window/packet sizes for tcp/x11-fwd-channel */ 212 #define CHAN_SES_PACKET_DEFAULT (32*1024) 213 #define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT) 214 #define CHAN_TCP_PACKET_DEFAULT (32*1024) 215 #define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT) 216 #define CHAN_X11_PACKET_DEFAULT (16*1024) 217 #define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 218 219 /* possible input states */ 220 #define CHAN_INPUT_OPEN 0 221 #define CHAN_INPUT_WAIT_DRAIN 1 222 #define CHAN_INPUT_WAIT_OCLOSE 2 223 #define CHAN_INPUT_CLOSED 3 224 225 /* possible output states */ 226 #define CHAN_OUTPUT_OPEN 0 227 #define CHAN_OUTPUT_WAIT_DRAIN 1 228 #define CHAN_OUTPUT_WAIT_IEOF 2 229 #define CHAN_OUTPUT_CLOSED 3 230 231 #define CHAN_CLOSE_SENT 0x01 232 #define CHAN_CLOSE_RCVD 0x02 233 #define CHAN_EOF_SENT 0x04 234 #define CHAN_EOF_RCVD 0x08 235 #define CHAN_LOCAL 0x10 236 237 /* file descriptor events */ 238 #define SSH_CHAN_IO_RFD 0x01 239 #define SSH_CHAN_IO_WFD 0x02 240 #define SSH_CHAN_IO_EFD_R 0x04 241 #define SSH_CHAN_IO_EFD_W 0x08 242 #define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W) 243 #define SSH_CHAN_IO_SOCK_R 0x10 244 #define SSH_CHAN_IO_SOCK_W 0x20 245 #define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W) 246 247 /* Read buffer size */ 248 #define CHAN_RBUF (16*1024) 249 250 /* Maximum size for direct reads to buffers */ 251 #define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT 252 253 /* Maximum channel input buffer size */ 254 #define CHAN_INPUT_MAX (16*1024*1024) 255 256 /* Hard limit on number of channels */ 257 #define CHANNELS_MAX_CHANNELS (16*1024) 258 259 /* check whether 'efd' is still in use */ 260 #define CHANNEL_EFD_INPUT_ACTIVE(c) \ 261 (c->extended_usage == CHAN_EXTENDED_READ && \ 262 (c->efd != -1 || \ 263 sshbuf_len(c->extended) > 0)) 264 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 265 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 266 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 267 sshbuf_len(c->extended) > 0)) 268 269 /* Add channel management structures to SSH transport instance */ 270 void channel_init_channels(struct ssh *ssh); 271 272 /* channel management */ 273 274 Channel *channel_by_id(struct ssh *, int); 275 Channel *channel_by_remote_id(struct ssh *, u_int); 276 Channel *channel_lookup(struct ssh *, int); 277 Channel *channel_new(struct ssh *, char *, int, int, int, int, 278 u_int, u_int, int, const char *, int); 279 void channel_set_fds(struct ssh *, int, int, int, int, int, 280 int, int, u_int); 281 void channel_free(struct ssh *, Channel *); 282 void channel_free_all(struct ssh *); 283 void channel_stop_listening(struct ssh *); 284 285 void channel_send_open(struct ssh *, int); 286 void channel_request_start(struct ssh *, int, char *, int); 287 void channel_register_cleanup(struct ssh *, int, 288 channel_callback_fn *, int); 289 void channel_register_open_confirm(struct ssh *, int, 290 channel_open_fn *, void *); 291 void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 292 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 293 void channel_register_status_confirm(struct ssh *, int, 294 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 295 void channel_cancel_cleanup(struct ssh *, int); 296 int channel_close_fd(struct ssh *, Channel *, int *); 297 void channel_send_window_changes(struct ssh *); 298 299 /* mux proxy support */ 300 301 int channel_proxy_downstream(struct ssh *, Channel *mc); 302 int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 303 304 /* protocol handler */ 305 306 int channel_input_data(int, u_int32_t, struct ssh *); 307 int channel_input_extended_data(int, u_int32_t, struct ssh *); 308 int channel_input_ieof(int, u_int32_t, struct ssh *); 309 int channel_input_oclose(int, u_int32_t, struct ssh *); 310 int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 311 int channel_input_open_failure(int, u_int32_t, struct ssh *); 312 int channel_input_port_open(int, u_int32_t, struct ssh *); 313 int channel_input_window_adjust(int, u_int32_t, struct ssh *); 314 int channel_input_status_confirm(int, u_int32_t, struct ssh *); 315 316 /* file descriptor handling (read/write) */ 317 struct pollfd; 318 319 void channel_prepare_poll(struct ssh *, struct pollfd **, 320 u_int *, u_int *, u_int, time_t *); 321 void channel_after_poll(struct ssh *, struct pollfd *, u_int); 322 void channel_output_poll(struct ssh *); 323 324 int channel_not_very_much_buffered_data(struct ssh *); 325 void channel_close_all(struct ssh *); 326 int channel_still_open(struct ssh *); 327 const char *channel_format_extended_usage(const Channel *); 328 char *channel_open_message(struct ssh *); 329 int channel_find_open(struct ssh *); 330 331 /* tcp forwarding */ 332 struct Forward; 333 struct ForwardOptions; 334 void channel_set_af(struct ssh *, int af); 335 void channel_permit_all(struct ssh *, int); 336 void channel_add_permission(struct ssh *, int, int, char *, int); 337 void channel_clear_permission(struct ssh *, int, int); 338 void channel_disable_admin(struct ssh *, int); 339 void channel_update_permission(struct ssh *, int, int); 340 Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 341 char *, char *, int *, const char **); 342 Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *); 343 Channel *channel_connect_stdio_fwd(struct ssh *, const char*, 344 u_short, int, int, int); 345 Channel *channel_connect_by_listen_address(struct ssh *, const char *, 346 u_short, char *, char *); 347 Channel *channel_connect_by_listen_path(struct ssh *, const char *, 348 char *, char *); 349 int channel_request_remote_forwarding(struct ssh *, struct Forward *); 350 int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 351 struct ForwardOptions *); 352 int channel_request_rforward_cancel(struct ssh *, struct Forward *); 353 int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 354 int *, struct ForwardOptions *); 355 int channel_cancel_rport_listener(struct ssh *, struct Forward *); 356 int channel_cancel_lport_listener(struct ssh *, struct Forward *, 357 int, struct ForwardOptions *); 358 int permitopen_port(const char *); 359 360 /* x11 forwarding */ 361 362 void channel_set_x11_refuse_time(struct ssh *, u_int); 363 int x11_connect_display(struct ssh *); 364 int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 365 void x11_request_forwarding_with_spoofing(struct ssh *, int, 366 const char *, const char *, const char *, int); 367 368 /* channel close */ 369 370 int chan_is_dead(struct ssh *, Channel *, int); 371 void chan_mark_dead(struct ssh *, Channel *); 372 373 /* channel events */ 374 375 void chan_rcvd_oclose(struct ssh *, Channel *); 376 void chan_rcvd_eow(struct ssh *, Channel *); 377 void chan_read_failed(struct ssh *, Channel *); 378 void chan_ibuf_empty(struct ssh *, Channel *); 379 void chan_rcvd_ieof(struct ssh *, Channel *); 380 void chan_write_failed(struct ssh *, Channel *); 381 void chan_obuf_empty(struct ssh *, Channel *); 382 383 #endif 384