channels.h

   1 /* $OpenBSD: channels.h,v 1.154 2023/12/18 14:47:20 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, 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         int     restore_flags[3];/* flags to restore */
 157         struct sshbuf *input;   /* data read from socket, to be sent over
 158                                  * encrypted connection */
 159         struct sshbuf *output;  /* data received over encrypted connection for
 160                                  * send on socket */
 161         struct sshbuf *extended;
 162
 163         char    *path;
 164                 /* path for unix domain sockets, or host name for forwards */
 165         int     listening_port; /* port being listened for forwards */
 166         char   *listening_addr; /* addr being listened for forwards */
 167         int     host_port;      /* remote port to connect for forwards */
 168         char   *remote_name;    /* remote hostname */
 169
 170         u_int   remote_window;
 171         u_int   remote_maxpacket;
 172         u_int   local_window;
 173         u_int   local_window_exceeded;
 174         u_int   local_window_max;
 175         u_int   local_consumed;
 176         u_int   local_maxpacket;
 177         int     extended_usage;
 178         int     single_connection;
 179
 180         char   *ctype;          /* const type - NB. not freed on channel_free */
 181         char   *xctype;         /* extended type */
 182
 183         /* callback */
 184         channel_open_fn         *open_confirm;
 185         void                    *open_confirm_ctx;
 186         channel_callback_fn     *detach_user;
 187         int                     detach_close;
 188         struct channel_confirms status_confirms;
 189
 190         /* filter */
 191         channel_infilter_fn     *input_filter;
 192         channel_outfilter_fn    *output_filter;
 193         void                    *filter_ctx;
 194         channel_filter_cleanup_fn *filter_cleanup;
 195
 196         /* keep boundaries */
 197         int                     datagram;
 198
 199         /* non-blocking connect */
 200         /* XXX make this a pointer so the structure can be opaque */
 201         struct channel_connect  connect_ctx;
 202
 203         /* multiplexing protocol hook, called for each packet received */
 204         mux_callback_fn         *mux_rcb;
 205         void                    *mux_ctx;
 206         int                     mux_pause;
 207         int                     mux_downstream_id;
 208
 209         /* Inactivity timeouts */
 210
 211         /* Last traffic seen for OPEN channels */
 212         time_t                  lastused;
 213         /* Inactivity timeout deadline in seconds (0 = no timeout) */
 214         int                     inactive_deadline;
 215 };
 216
 217 #define CHAN_EXTENDED_IGNORE            0
 218 #define CHAN_EXTENDED_READ              1
 219 #define CHAN_EXTENDED_WRITE             2
 220
 221 /* default window/packet sizes for tcp/x11-fwd-channel */
 222 #define CHAN_SES_PACKET_DEFAULT (32*1024)
 223 #define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT)
 224 #define CHAN_TCP_PACKET_DEFAULT (32*1024)
 225 #define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT)
 226 #define CHAN_X11_PACKET_DEFAULT (16*1024)
 227 #define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT)
 228
 229 /* possible input states */
 230 #define CHAN_INPUT_OPEN                 0
 231 #define CHAN_INPUT_WAIT_DRAIN           1
 232 #define CHAN_INPUT_WAIT_OCLOSE          2
 233 #define CHAN_INPUT_CLOSED               3
 234
 235 /* possible output states */
 236 #define CHAN_OUTPUT_OPEN                0
 237 #define CHAN_OUTPUT_WAIT_DRAIN          1
 238 #define CHAN_OUTPUT_WAIT_IEOF           2
 239 #define CHAN_OUTPUT_CLOSED              3
 240
 241 #define CHAN_CLOSE_SENT                 0x01
 242 #define CHAN_CLOSE_RCVD                 0x02
 243 #define CHAN_EOF_SENT                   0x04
 244 #define CHAN_EOF_RCVD                   0x08
 245 #define CHAN_LOCAL                      0x10
 246
 247 /* file descriptor events */
 248 #define SSH_CHAN_IO_RFD                 0x01
 249 #define SSH_CHAN_IO_WFD                 0x02
 250 #define SSH_CHAN_IO_EFD_R               0x04
 251 #define SSH_CHAN_IO_EFD_W               0x08
 252 #define SSH_CHAN_IO_EFD                 (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W)
 253 #define SSH_CHAN_IO_SOCK_R              0x10
 254 #define SSH_CHAN_IO_SOCK_W              0x20
 255 #define SSH_CHAN_IO_SOCK                (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W)
 256
 257 /* Read buffer size */
 258 #define CHAN_RBUF       (16*1024)
 259
 260 /* Maximum size for direct reads to buffers */
 261 #define CHANNEL_MAX_READ        CHAN_SES_PACKET_DEFAULT
 262
 263 /* Maximum channel input buffer size */
 264 #define CHAN_INPUT_MAX  (16*1024*1024)
 265
 266 /* Hard limit on number of channels */
 267 #define CHANNELS_MAX_CHANNELS   (16*1024)
 268
 269 /* check whether 'efd' is still in use */
 270 #define CHANNEL_EFD_INPUT_ACTIVE(c) \
 271         (c->extended_usage == CHAN_EXTENDED_READ && \
 272         (c->efd != -1 || \
 273         sshbuf_len(c->extended) > 0))
 274 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \
 275         (c->extended_usage == CHAN_EXTENDED_WRITE && \
 276         c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \
 277         sshbuf_len(c->extended) > 0))
 278
 279 /* Add channel management structures to SSH transport instance */
 280 void channel_init_channels(struct ssh *ssh);
 281
 282 /* channel management */
 283
 284 Channel *channel_by_id(struct ssh *, int);
 285 Channel *channel_by_remote_id(struct ssh *, u_int);
 286 Channel *channel_lookup(struct ssh *, int);
 287 Channel *channel_new(struct ssh *, char *, int, int, int, int,
 288             u_int, u_int, int, const char *, int);
 289 void     channel_set_fds(struct ssh *, int, int, int, int, int,
 290             int, int, u_int);
 291 void     channel_free(struct ssh *, Channel *);
 292 void     channel_free_all(struct ssh *);
 293 void     channel_stop_listening(struct ssh *);
 294 void     channel_force_close(struct ssh *, Channel *, int);
 295 void     channel_set_xtype(struct ssh *, int, const char *);
 296
 297 void     channel_send_open(struct ssh *, int);
 298 void     channel_request_start(struct ssh *, int, char *, int);
 299 void     channel_register_cleanup(struct ssh *, int,
 300             channel_callback_fn *, int);
 301 void     channel_register_open_confirm(struct ssh *, int,
 302             channel_open_fn *, void *);
 303 void     channel_register_filter(struct ssh *, int, channel_infilter_fn *,
 304             channel_outfilter_fn *, channel_filter_cleanup_fn *, void *);
 305 void     channel_register_status_confirm(struct ssh *, int,
 306             channel_confirm_cb *, channel_confirm_abandon_cb *, void *);
 307 void     channel_cancel_cleanup(struct ssh *, int);
 308 int      channel_close_fd(struct ssh *, Channel *, int *);
 309 void     channel_send_window_changes(struct ssh *);
 310
 311 /* channel inactivity timeouts */
 312 void channel_add_timeout(struct ssh *, const char *, int);
 313 void channel_clear_timeouts(struct ssh *);
 314
 315 /* mux proxy support */
 316
 317 int      channel_proxy_downstream(struct ssh *, Channel *mc);
 318 int      channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *);
 319
 320 /* protocol handler */
 321
 322 int      channel_input_data(int, u_int32_t, struct ssh *);
 323 int      channel_input_extended_data(int, u_int32_t, struct ssh *);
 324 int      channel_input_ieof(int, u_int32_t, struct ssh *);
 325 int      channel_input_oclose(int, u_int32_t, struct ssh *);
 326 int      channel_input_open_confirmation(int, u_int32_t, struct ssh *);
 327 int      channel_input_open_failure(int, u_int32_t, struct ssh *);
 328 int      channel_input_port_open(int, u_int32_t, struct ssh *);
 329 int      channel_input_window_adjust(int, u_int32_t, struct ssh *);
 330 int      channel_input_status_confirm(int, u_int32_t, struct ssh *);
 331
 332 /* file descriptor handling (read/write) */
 333 struct pollfd;
 334 struct timespec;
 335
 336 void     channel_prepare_poll(struct ssh *, struct pollfd **,
 337             u_int *, u_int *, u_int, struct timespec *);
 338 void     channel_after_poll(struct ssh *, struct pollfd *, u_int);
 339 int      channel_output_poll(struct ssh *);
 340
 341 int      channel_not_very_much_buffered_data(struct ssh *);
 342 void     channel_close_all(struct ssh *);
 343 int      channel_still_open(struct ssh *);
 344 int      channel_tty_open(struct ssh *);
 345 const char *channel_format_extended_usage(const Channel *);
 346 char    *channel_open_message(struct ssh *);
 347 int      channel_find_open(struct ssh *);
 348
 349 /* tcp forwarding */
 350 struct Forward;
 351 struct ForwardOptions;
 352 void     channel_set_af(struct ssh *, int af);
 353 void     channel_permit_all(struct ssh *, int);
 354 void     channel_add_permission(struct ssh *, int, int, char *, int);
 355 void     channel_clear_permission(struct ssh *, int, int);
 356 void     channel_disable_admin(struct ssh *, int);
 357 void     channel_update_permission(struct ssh *, int, int);
 358 Channel *channel_connect_to_port(struct ssh *, const char *, u_short,
 359             char *, char *, int *, const char **);
 360 Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *);
 361 Channel *channel_connect_stdio_fwd(struct ssh *, const char*,
 362             int, int, int, int);
 363 Channel *channel_connect_by_listen_address(struct ssh *, const char *,
 364             u_short, char *, char *);
 365 Channel *channel_connect_by_listen_path(struct ssh *, const char *,
 366             char *, char *);
 367 int      channel_request_remote_forwarding(struct ssh *, struct Forward *);
 368 int      channel_setup_local_fwd_listener(struct ssh *, struct Forward *,
 369             struct ForwardOptions *);
 370 int      channel_request_rforward_cancel(struct ssh *, struct Forward *);
 371 int      channel_setup_remote_fwd_listener(struct ssh *, struct Forward *,
 372             int *, struct ForwardOptions *);
 373 int      channel_cancel_rport_listener(struct ssh *, struct Forward *);
 374 int      channel_cancel_lport_listener(struct ssh *, struct Forward *,
 375             int, struct ForwardOptions *);
 376 int      permitopen_port(const char *);
 377
 378 /* x11 forwarding */
 379
 380 void     channel_set_x11_refuse_time(struct ssh *, time_t);
 381 int      x11_connect_display(struct ssh *);
 382 int      x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **);
 383 void     x11_request_forwarding_with_spoofing(struct ssh *, int,
 384             const char *, const char *, const char *, int);
 385
 386 /* channel close */
 387
 388 int      chan_is_dead(struct ssh *, Channel *, int);
 389 void     chan_mark_dead(struct ssh *, Channel *);
 390
 391 /* channel events */
 392
 393 void     chan_rcvd_oclose(struct ssh *, Channel *);
 394 void     chan_rcvd_eow(struct ssh *, Channel *);
 395 void     chan_read_failed(struct ssh *, Channel *);
 396 void     chan_ibuf_empty(struct ssh *, Channel *);
 397 void     chan_rcvd_ieof(struct ssh *, Channel *);
 398 void     chan_write_failed(struct ssh *, Channel *);
 399 void     chan_obuf_empty(struct ssh *, Channel *);
 400
 401 #endif