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0cb50eefdd
openssh/channels.h
djm@openbsd.org 0cb50eefdd
upstream: stricter handling of channel window limits 
This makes ssh/sshd more strict in handling non-compliant peers that
send more data than the advertised channel window allows. Previously
the additional data would be silently discarded. This change will
cause ssh/sshd to terminate the connection if the channel window is
exceeded by more than a small grace allowance.

ok markus@

OpenBSD-Commit-ID: 811e21b41831eba3dd7f67b3d409a438f20d3037
2023-12-19 01:52:55 +11:00

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15 KiB
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/* $OpenBSD: channels.h,v 1.154 2023/12/18 14:47:20 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*/
/*
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CHANNEL_H
#define CHANNEL_H
/* Definitions for channel types. */
#define SSH_CHANNEL_X11_LISTENER 1 /* Listening for inet X11 conn. */
#define SSH_CHANNEL_PORT_LISTENER 2 /* Listening on a port. */
#define SSH_CHANNEL_OPENING 3 /* waiting for confirmation */
#define SSH_CHANNEL_OPEN 4 /* normal open two-way channel */
#define SSH_CHANNEL_CLOSED 5 /* waiting for close confirmation */
#define SSH_CHANNEL_AUTH_SOCKET 6 /* authentication socket */
#define SSH_CHANNEL_X11_OPEN 7 /* reading first X11 packet */
#define SSH_CHANNEL_LARVAL 10 /* larval session */
#define SSH_CHANNEL_RPORT_LISTENER 11 /* Listening to a R-style port */
#define SSH_CHANNEL_CONNECTING 12
#define SSH_CHANNEL_DYNAMIC 13
#define SSH_CHANNEL_ZOMBIE 14 /* Almost dead. */
#define SSH_CHANNEL_MUX_LISTENER 15 /* Listener for mux conn. */
#define SSH_CHANNEL_MUX_CLIENT 16 /* Conn. to mux client */
#define SSH_CHANNEL_ABANDONED 17 /* Abandoned session, eg mux */
#define SSH_CHANNEL_UNIX_LISTENER 18 /* Listening on a domain socket. */
#define SSH_CHANNEL_RUNIX_LISTENER 19 /* Listening to a R-style domain socket. */
#define SSH_CHANNEL_MUX_PROXY 20 /* proxy channel for mux-client */
#define SSH_CHANNEL_RDYNAMIC_OPEN 21 /* reverse SOCKS, parsing request */
#define SSH_CHANNEL_RDYNAMIC_FINISH 22 /* reverse SOCKS, finishing connect */
#define SSH_CHANNEL_MAX_TYPE 23
#define CHANNEL_CANCEL_PORT_STATIC -1
/* nonblocking flags for channel_new */
#define CHANNEL_NONBLOCK_LEAVE 0 /* don't modify non-blocking state */
#define CHANNEL_NONBLOCK_SET 1 /* set non-blocking state */
#define CHANNEL_NONBLOCK_STDIO 2 /* set non-blocking and restore on close */
/* c->restore_block mask flags */
#define CHANNEL_RESTORE_RFD 0x01
#define CHANNEL_RESTORE_WFD 0x02
#define CHANNEL_RESTORE_EFD 0x04
/* TCP forwarding */
#define FORWARD_DENY 0
#define FORWARD_REMOTE (1)
#define FORWARD_LOCAL (1<<1)
#define FORWARD_ALLOW (FORWARD_REMOTE|FORWARD_LOCAL)
#define FORWARD_ADM 0x100
#define FORWARD_USER 0x101
struct ssh;
struct Channel;
typedef struct Channel Channel;
struct fwd_perm_list;
typedef void channel_open_fn(struct ssh *, int, int, void *);
typedef void channel_callback_fn(struct ssh *, int, int, void *);
typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int);
typedef void channel_filter_cleanup_fn(struct ssh *, int, void *);
typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *,
u_char **, size_t *);
/* Channel success/failure callbacks */
typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *);
typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *);
struct channel_confirm {
TAILQ_ENTRY(channel_confirm) entry;
channel_confirm_cb *cb;
channel_confirm_abandon_cb *abandon_cb;
void *ctx;
};
TAILQ_HEAD(channel_confirms, channel_confirm);
/* Context for non-blocking connects */
struct channel_connect {
char *host;
int port;
struct addrinfo *ai, *aitop;
};
/* Callbacks for mux channels back into client-specific code */
typedef int mux_callback_fn(struct ssh *, struct Channel *);
/*
* NB. channel IDs on the wire and in c->remote_id are uint32, but local
* channel IDs (e.g. c->self) only ever use the int32 subset of this range,
* because we use local channel ID -1 for housekeeping. Remote channels have
* a dedicated "have_remote_id" flag to indicate their validity.
*/
struct Channel {
int type; /* channel type/state */
int self; /* my own channel identifier */
uint32_t remote_id; /* channel identifier for remote peer */
int have_remote_id; /* non-zero if remote_id is valid */
u_int istate; /* input from channel (state of receive half) */
u_int ostate; /* output to channel (state of transmit half) */
int flags; /* close sent/rcvd */
int rfd; /* read fd */
int wfd; /* write fd */
int efd; /* extended fd */
int sock; /* sock fd */
u_int io_want; /* bitmask of SSH_CHAN_IO_* */
u_int io_ready; /* bitmask of SSH_CHAN_IO_* */
int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */
int ctl_chan; /* control channel (multiplexed connections) */
int isatty; /* rfd is a tty */
#ifdef _AIX
int wfd_isatty; /* wfd is a tty */
#endif
int client_tty; /* (client) TTY has been requested */
int force_drain; /* force close on iEOF */
time_t notbefore; /* Pause IO until deadline (time_t) */
int delayed; /* post-IO handlers for newly created
* channels are delayed until the first call
* to a matching pre-IO handler.
* this way post-IO handlers are not
* accidentally called if a FD gets reused */
int restore_block; /* fd mask to restore blocking status */
int restore_flags[3];/* flags to restore */
struct sshbuf *input; /* data read from socket, to be sent over
* encrypted connection */
struct sshbuf *output; /* data received over encrypted connection for
* send on socket */
struct sshbuf *extended;
char *path;
/* path for unix domain sockets, or host name for forwards */
int listening_port; /* port being listened for forwards */
char *listening_addr; /* addr being listened for forwards */
int host_port; /* remote port to connect for forwards */
char *remote_name; /* remote hostname */
u_int remote_window;
u_int remote_maxpacket;
u_int local_window;
u_int local_window_exceeded;
u_int local_window_max;
u_int local_consumed;
u_int local_maxpacket;
int extended_usage;
int single_connection;
char *ctype; /* const type - NB. not freed on channel_free */
char *xctype; /* extended type */
/* callback */
channel_open_fn *open_confirm;
void *open_confirm_ctx;
channel_callback_fn *detach_user;
int detach_close;
struct channel_confirms status_confirms;
/* filter */
channel_infilter_fn *input_filter;
channel_outfilter_fn *output_filter;
void *filter_ctx;
channel_filter_cleanup_fn *filter_cleanup;
/* keep boundaries */
int datagram;
/* non-blocking connect */
/* XXX make this a pointer so the structure can be opaque */
struct channel_connect connect_ctx;
/* multiplexing protocol hook, called for each packet received */
mux_callback_fn *mux_rcb;
void *mux_ctx;
int mux_pause;
int mux_downstream_id;
/* Inactivity timeouts */
/* Last traffic seen for OPEN channels */
time_t lastused;
/* Inactivity timeout deadline in seconds (0 = no timeout) */
int inactive_deadline;
};
#define CHAN_EXTENDED_IGNORE 0
#define CHAN_EXTENDED_READ 1
#define CHAN_EXTENDED_WRITE 2
/* default window/packet sizes for tcp/x11-fwd-channel */
#define CHAN_SES_PACKET_DEFAULT (32*1024)
#define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT)
#define CHAN_TCP_PACKET_DEFAULT (32*1024)
#define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT)
#define CHAN_X11_PACKET_DEFAULT (16*1024)
#define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT)
/* possible input states */
#define CHAN_INPUT_OPEN 0
#define CHAN_INPUT_WAIT_DRAIN 1
#define CHAN_INPUT_WAIT_OCLOSE 2
#define CHAN_INPUT_CLOSED 3
/* possible output states */
#define CHAN_OUTPUT_OPEN 0
#define CHAN_OUTPUT_WAIT_DRAIN 1
#define CHAN_OUTPUT_WAIT_IEOF 2
#define CHAN_OUTPUT_CLOSED 3
#define CHAN_CLOSE_SENT 0x01
#define CHAN_CLOSE_RCVD 0x02
#define CHAN_EOF_SENT 0x04
#define CHAN_EOF_RCVD 0x08
#define CHAN_LOCAL 0x10
/* file descriptor events */
#define SSH_CHAN_IO_RFD 0x01
#define SSH_CHAN_IO_WFD 0x02
#define SSH_CHAN_IO_EFD_R 0x04
#define SSH_CHAN_IO_EFD_W 0x08
#define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W)
#define SSH_CHAN_IO_SOCK_R 0x10
#define SSH_CHAN_IO_SOCK_W 0x20
#define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W)
/* Read buffer size */
#define CHAN_RBUF (16*1024)
/* Maximum size for direct reads to buffers */
#define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT
/* Maximum channel input buffer size */
#define CHAN_INPUT_MAX (16*1024*1024)
/* Hard limit on number of channels */
#define CHANNELS_MAX_CHANNELS (16*1024)
/* check whether 'efd' is still in use */
#define CHANNEL_EFD_INPUT_ACTIVE(c) \
(c->extended_usage == CHAN_EXTENDED_READ && \
(c->efd != -1 || \
sshbuf_len(c->extended) > 0))
#define CHANNEL_EFD_OUTPUT_ACTIVE(c) \
(c->extended_usage == CHAN_EXTENDED_WRITE && \
c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \
sshbuf_len(c->extended) > 0))
/* Add channel management structures to SSH transport instance */
void channel_init_channels(struct ssh *ssh);
/* channel management */
Channel *channel_by_id(struct ssh *, int);
Channel *channel_by_remote_id(struct ssh *, u_int);
Channel *channel_lookup(struct ssh *, int);
Channel *channel_new(struct ssh *, char *, int, int, int, int,
u_int, u_int, int, const char *, int);
void channel_set_fds(struct ssh *, int, int, int, int, int,
int, int, u_int);
void channel_free(struct ssh *, Channel *);
void channel_free_all(struct ssh *);
void channel_stop_listening(struct ssh *);
void channel_force_close(struct ssh *, Channel *, int);
void channel_set_xtype(struct ssh *, int, const char *);
void channel_send_open(struct ssh *, int);
void channel_request_start(struct ssh *, int, char *, int);
void channel_register_cleanup(struct ssh *, int,
channel_callback_fn *, int);
void channel_register_open_confirm(struct ssh *, int,
channel_open_fn *, void *);
void channel_register_filter(struct ssh *, int, channel_infilter_fn *,
channel_outfilter_fn *, channel_filter_cleanup_fn *, void *);
void channel_register_status_confirm(struct ssh *, int,
channel_confirm_cb *, channel_confirm_abandon_cb *, void *);
void channel_cancel_cleanup(struct ssh *, int);
int channel_close_fd(struct ssh *, Channel *, int *);
void channel_send_window_changes(struct ssh *);
/* channel inactivity timeouts */
void channel_add_timeout(struct ssh *, const char *, int);
void channel_clear_timeouts(struct ssh *);
/* mux proxy support */
int channel_proxy_downstream(struct ssh *, Channel *mc);
int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *);
/* protocol handler */
int channel_input_data(int, u_int32_t, struct ssh *);
int channel_input_extended_data(int, u_int32_t, struct ssh *);
int channel_input_ieof(int, u_int32_t, struct ssh *);
int channel_input_oclose(int, u_int32_t, struct ssh *);
int channel_input_open_confirmation(int, u_int32_t, struct ssh *);
int channel_input_open_failure(int, u_int32_t, struct ssh *);
int channel_input_port_open(int, u_int32_t, struct ssh *);
int channel_input_window_adjust(int, u_int32_t, struct ssh *);
int channel_input_status_confirm(int, u_int32_t, struct ssh *);
/* file descriptor handling (read/write) */
struct pollfd;
struct timespec;
void channel_prepare_poll(struct ssh *, struct pollfd **,
u_int *, u_int *, u_int, struct timespec *);
void channel_after_poll(struct ssh *, struct pollfd *, u_int);
int channel_output_poll(struct ssh *);
int channel_not_very_much_buffered_data(struct ssh *);
void channel_close_all(struct ssh *);
int channel_still_open(struct ssh *);
int channel_tty_open(struct ssh *);
const char *channel_format_extended_usage(const Channel *);
char *channel_open_message(struct ssh *);
int channel_find_open(struct ssh *);
/* tcp forwarding */
struct Forward;
struct ForwardOptions;
void channel_set_af(struct ssh *, int af);
void channel_permit_all(struct ssh *, int);
void channel_add_permission(struct ssh *, int, int, char *, int);
void channel_clear_permission(struct ssh *, int, int);
void channel_disable_admin(struct ssh *, int);
void channel_update_permission(struct ssh *, int, int);
Channel *channel_connect_to_port(struct ssh *, const char *, u_short,
char *, char *, int *, const char **);
Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *);
Channel *channel_connect_stdio_fwd(struct ssh *, const char*,
int, int, int, int);
Channel *channel_connect_by_listen_address(struct ssh *, const char *,
u_short, char *, char *);
Channel *channel_connect_by_listen_path(struct ssh *, const char *,
char *, char *);
int channel_request_remote_forwarding(struct ssh *, struct Forward *);
int channel_setup_local_fwd_listener(struct ssh *, struct Forward *,
struct ForwardOptions *);
int channel_request_rforward_cancel(struct ssh *, struct Forward *);
int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *,
int *, struct ForwardOptions *);
int channel_cancel_rport_listener(struct ssh *, struct Forward *);
int channel_cancel_lport_listener(struct ssh *, struct Forward *,
int, struct ForwardOptions *);
int permitopen_port(const char *);
/* x11 forwarding */
void channel_set_x11_refuse_time(struct ssh *, time_t);
int x11_connect_display(struct ssh *);
int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **);
void x11_request_forwarding_with_spoofing(struct ssh *, int,
const char *, const char *, const char *, int);
/* channel close */
int chan_is_dead(struct ssh *, Channel *, int);
void chan_mark_dead(struct ssh *, Channel *);
/* channel events */
void chan_rcvd_oclose(struct ssh *, Channel *);
void chan_rcvd_eow(struct ssh *, Channel *);
void chan_read_failed(struct ssh *, Channel *);
void chan_ibuf_empty(struct ssh *, Channel *);
void chan_rcvd_ieof(struct ssh *, Channel *);
void chan_write_failed(struct ssh *, Channel *);
void chan_obuf_empty(struct ssh *, Channel *);
#endif
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