crypto/openssh/channels.h

   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