view loginrec.h @ 1788:1fc0012b9c38

Fix handling of replies to global requests (#112) The current code assumes that all global requests want / need a reply. This isn't always true and the request itself indicates if it wants a reply or not. It causes a specific problem with [email protected] messages. These are sent by OpenSSH after authentication to inform the client of potential other host keys for the host. This can be used to add a new type of host key or to rotate host keys. The initial information message from the server is sent as a global request, but with want_reply set to false. This means that the server doesn't expect an answer to this message. Instead the client needs to send a prove request as a reply if it wants to receive proof of ownership for the host keys. The bug doesn't cause any current problems with due to how OpenSSH treats receiving the failure message. It instead treats it as a keepalive message and further ignores it. Arguably this is a protocol violation though of Dropbear and it is only accidental that it doesn't cause a problem with OpenSSH. The bug was found when adding host keys support to libssh, which is more strict protocol wise and treats the unexpected failure message an error, also see https://gitlab.com/libssh/libssh-mirror/-/merge_requests/145 for more information. The fix here is to honor the want_reply flag in the global request and to only send a reply if the other side expects a reply.
author Dirkjan Bussink <d.bussink@gmail.com>
date Thu, 10 Dec 2020 16:13:13 +0100
parents 1ed6f39e8aa4
children
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#ifndef DROPBEAR_HAVE_LOGINREC_H_
#define DROPBEAR_HAVE_LOGINREC_H_

/*
 * Copyright (c) 2000 Andre Lucas.  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.
 */

/**
 ** loginrec.h:  platform-independent login recording and lastlog retrieval
 **/

#include "includes.h"

/* RCSID("Id: loginrec.h,v 1.2 2004/05/04 10:17:43 matt Exp "); */

/* The following #defines are from OpenSSH's defines.h, required for loginrec */

/* FIXME: put default paths back in */
#ifndef UTMP_FILE
#  ifdef _PATH_UTMP
#    define UTMP_FILE _PATH_UTMP
#  else
#    ifdef CONF_UTMP_FILE
#      define UTMP_FILE CONF_UTMP_FILE
#    endif
#  endif
#endif
#ifndef WTMP_FILE
#  ifdef _PATH_WTMP
#    define WTMP_FILE _PATH_WTMP
#  else
#    ifdef CONF_WTMP_FILE
#      define WTMP_FILE CONF_WTMP_FILE
#    endif
#  endif
#endif
/* pick up the user's location for lastlog if given */
#ifndef LASTLOG_FILE
#  ifdef _PATH_LASTLOG
#    define LASTLOG_FILE _PATH_LASTLOG
#  else
#    ifdef CONF_LASTLOG_FILE
#      define LASTLOG_FILE CONF_LASTLOG_FILE
#    endif
#  endif
#endif


/* The login() library function in libutil is first choice */
#if defined(HAVE_LOGIN) && !defined(DISABLE_LOGIN)
#  define USE_LOGIN

#else
/* Simply select your favourite login types. */
/* Can't do if-else because some systems use several... <sigh> */
#  if defined(HAVE_UTMPX_H) && defined(UTMPX_FILE) && !defined(DISABLE_UTMPX)
#    define USE_UTMPX
#  endif
#  if defined(HAVE_UTMP_H) && defined(UTMP_FILE) && !defined(DISABLE_UTMP)
#    define USE_UTMP
#  endif
#  if defined(WTMPX_FILE) && !defined(DISABLE_WTMPX)
#    define USE_WTMPX
#  endif
#  if defined(WTMP_FILE) && !defined(DISABLE_WTMP)
#    define USE_WTMP
#  endif

#endif

/* I hope that the presence of LASTLOG_FILE is enough to detect this */
#if defined(LASTLOG_FILE) && !defined(DISABLE_LASTLOG)
#  define USE_LASTLOG
#endif


/**
 ** you should use the login_* calls to work around platform dependencies
 **/

/*
 * login_netinfo structure
 */

union login_netinfo {
	struct sockaddr sa;
	struct sockaddr_in sa_in;
#ifdef HAVE_STRUCT_SOCKADDR_STORAGE
	struct sockaddr_storage sa_storage;
#endif
};

/*
 *   * logininfo structure  *
 */
/* types - different to utmp.h 'type' macros */
/* (though set to the same value as linux, openbsd and others...) */
#define LTYPE_LOGIN    7
#define LTYPE_LOGOUT   8

/* string lengths - set very long */
#define LINFO_PROGSIZE 64
#define LINFO_LINESIZE 64
#define LINFO_NAMESIZE 64
#define LINFO_HOSTSIZE 256

struct logininfo {
	char       progname[LINFO_PROGSIZE];     /* name of program (for PAM) */
	int        progname_null;
	short int  type;                         /* type of login (LTYPE_*) */
	int        pid;                          /* PID of login process */
	int        uid;                          /* UID of this user */
	char       line[LINFO_LINESIZE];         /* tty/pty name */
	char       username[LINFO_NAMESIZE];     /* login username */
	char       hostname[LINFO_HOSTSIZE];     /* remote hostname */
	/* 'exit_status' structure components */
	int        exit;                        /* process exit status */
	int        termination;                 /* process termination status */
	/* struct timeval (sys/time.h) isn't always available, if it isn't we'll
	 * use time_t's value as tv_sec and set tv_usec to 0
	 */
	unsigned int tv_sec;
	unsigned int tv_usec;
	union login_netinfo hostaddr;       /* caller's host address(es) */
}; /* struct logininfo */

/*
 * login recording functions
 */

/** 'public' functions */

struct logininfo *login_alloc_entry(int pid, const char *username,
				    const char *hostname, const char *line);
/* free a structure */
void login_free_entry(struct logininfo *li);
/* fill out a pre-allocated structure with useful information */
int login_init_entry(struct logininfo *li, int pid, const char *username,
		     const char *hostname, const char *line);
/* place the current time in a logininfo struct */
void login_set_current_time(struct logininfo *li);

/* record the entry */
int login_login (struct logininfo *li);
int login_logout(struct logininfo *li);
#ifdef LOGIN_NEEDS_UTMPX
int login_utmp_only(struct logininfo *li);
#endif

/** End of public functions */

/* record the entry */
int login_write (struct logininfo *li);
int login_log_entry(struct logininfo *li);

/* produce various forms of the line filename */
char *line_fullname(char *dst, const char *src, size_t dstsize);
char *line_stripname(char *dst, const char *src, size_t dstsize);
char *line_abbrevname(char *dst, const char *src, size_t dstsize);

#endif /* DROPBEAR_HAVE_LOGINREC_H_ */