IABSD.fr/src/usr.bin/ssh/monitor.h

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• Author : djm
  Date : 2026-03-02 02:40:15
  Hash : 3d462a97
  Message : Move banner exchange to sshd-auth process Previously, exchange of the initial SSH- banners was performed by the privileged sshd-session monitor. This moves it to the unprivileged sshd-auth subprocess, removing ~200 LoC from the monitor's privileged attack surface. The monitor gains a new "setcompat" RPC to allow sshd-auth to inform it of bug compat flags picked up from the client's banner. feedback dtucker@, ok markus@ deraadt@

• usr.bin/ssh/monitor.h

• /* $OpenBSD: monitor.h,v 1.28 2026/03/02 02:40:15 djm Exp $ */
  
  /*
   * Copyright 2002 Niels Provos <provos@citi.umich.edu>
   * 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 _MONITOR_H_
  #define _MONITOR_H_
  
  /* Please keep *_REQ_* values on even numbers and *_ANS_* on odd numbers */
  enum monitor_reqtype {
  	MONITOR_REQ_MODULI = 0, MONITOR_ANS_MODULI = 1,
  	MONITOR_REQ_FREE = 2,
  	MONITOR_REQ_AUTHSERV = 4,
  	MONITOR_REQ_SIGN = 6, MONITOR_ANS_SIGN = 7,
  	MONITOR_REQ_PWNAM = 8, MONITOR_ANS_PWNAM = 9,
  	MONITOR_REQ_AUTH2_READ_BANNER = 10, MONITOR_ANS_AUTH2_READ_BANNER = 11,
  	MONITOR_REQ_AUTHPASSWORD = 12, MONITOR_ANS_AUTHPASSWORD = 13,
  	MONITOR_REQ_BSDAUTHQUERY = 14, MONITOR_ANS_BSDAUTHQUERY = 15,
  	MONITOR_REQ_BSDAUTHRESPOND = 16, MONITOR_ANS_BSDAUTHRESPOND = 17,
  	MONITOR_REQ_SETCOMPAT = 18,
  	MONITOR_REQ_KEYALLOWED = 22, MONITOR_ANS_KEYALLOWED = 23,
  	MONITOR_REQ_KEYVERIFY = 24, MONITOR_ANS_KEYVERIFY = 25,
  	MONITOR_REQ_KEYEXPORT = 26,
  	MONITOR_REQ_PTY = 28, MONITOR_ANS_PTY = 29,
  	MONITOR_REQ_PTYCLEANUP = 30,
  	MONITOR_REQ_SESSKEY = 32, MONITOR_ANS_SESSKEY = 33,
  	MONITOR_REQ_SESSID = 34,
  	MONITOR_REQ_RSAKEYALLOWED = 36, MONITOR_ANS_RSAKEYALLOWED = 37,
  	MONITOR_REQ_RSACHALLENGE = 38, MONITOR_ANS_RSACHALLENGE = 39,
  	MONITOR_REQ_RSARESPONSE = 40, MONITOR_ANS_RSARESPONSE = 41,
  	MONITOR_REQ_GSSSETUP = 42, MONITOR_ANS_GSSSETUP = 43,
  	MONITOR_REQ_GSSSTEP = 44, MONITOR_ANS_GSSSTEP = 45,
  	MONITOR_REQ_GSSUSEROK = 46, MONITOR_ANS_GSSUSEROK = 47,
  	MONITOR_REQ_GSSCHECKMIC = 48, MONITOR_ANS_GSSCHECKMIC = 49,
  	MONITOR_REQ_TERM = 50,
  	MONITOR_REQ_STATE = 51, MONITOR_ANS_STATE = 52
  };
  
  struct ssh;
  struct sshbuf;
  
  struct monitor {
  	int			 m_recvfd;
  	int			 m_sendfd;
  	int			 m_log_recvfd;
  	int			 m_log_sendfd;
  	struct kex		**m_pkex;
  	pid_t			 m_pid;
  };
  
  struct monitor *monitor_init(void);
  void monitor_reinit(struct monitor *);
  
  struct Authctxt;
  void monitor_child_preauth(struct ssh *, struct monitor *);
  void monitor_child_postauth(struct ssh *, struct monitor *);
  
  void monitor_clear_keystate(struct ssh *, struct monitor *);
  void monitor_apply_keystate(struct ssh *, struct monitor *);
  
  int  monitor_auth_attempted(void);
  int  monitor_invalid_user(void);
  
  /* Prototypes for request sending and receiving */
  void mm_request_send(int, enum monitor_reqtype, struct sshbuf *);
  void mm_request_receive(int, struct sshbuf *);
  void mm_request_receive_expect(int, enum monitor_reqtype, struct sshbuf *);
  void mm_get_keystate(struct ssh *, struct monitor *);
  
  /* XXX: should be returned via a monitor call rather than config_fd */
  void mm_encode_server_options(struct sshbuf *);
  
  struct sshbuf *pack_hostkeys(void);
  
  #endif /* _MONITOR_H_ */