sshlogin.c

   1 /* $OpenBSD: sshlogin.c,v 1.35 2020/10/18 11:32:02 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * This file performs some of the things login(1) normally does.  We cannot
   7  * easily use something like login -p -h host -f user, because there are
   8  * several different logins around, and it is hard to determined what kind of
   9  * login the current system has.  Also, we want to be able to execute commands
  10  * on a tty.
  11  *
  12  * As far as I am concerned, the code I have written for this software
  13  * can be used freely for any purpose.  Any derived versions of this
  14  * software must be clearly marked as such, and if the derived work is
  15  * incompatible with the protocol description in the RFC file, it must be
  16  * called by a name other than "ssh" or "Secure Shell".
  17  *
  18  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
  19  * Copyright (c) 1999 Markus Friedl.  All rights reserved.
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43
  44 #include <sys/types.h>
  45 #include <sys/socket.h>
  46
  47 #include <netinet/in.h>
  48
  49 #include <errno.h>
  50 #include <fcntl.h>
  51 #include <stdarg.h>
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55 #include <time.h>
  56 #include <unistd.h>
  57 #include <limits.h>
  58
  59 #include "sshlogin.h"
  60 #include "ssherr.h"
  61 #include "loginrec.h"
  62 #include "log.h"
  63 #include "sshbuf.h"
  64 #include "misc.h"
  65 #include "servconf.h"
  66
  67 extern struct sshbuf *loginmsg;
  68 extern ServerOptions options;
  69
  70 /*
  71  * Returns the time when the user last logged in.  Returns 0 if the
  72  * information is not available.  This must be called before record_login.
  73  * The host the user logged in from will be returned in buf.
  74  */
  75 time_t
  76 get_last_login_time(uid_t uid, const char *logname,
  77     char *buf, size_t bufsize)
  78 {
  79         struct logininfo li;
  80
  81         login_get_lastlog(&li, uid);
  82         strlcpy(buf, li.hostname, bufsize);
  83         return (time_t)li.tv_sec;
  84 }
  85
  86 /*
  87  * Generate and store last login message.  This must be done before
  88  * login_login() is called and lastlog is updated.
  89  */
  90 static void
  91 store_lastlog_message(const char *user, uid_t uid)
  92 {
  93 #ifndef NO_SSH_LASTLOG
  94 # ifndef CUSTOM_SYS_AUTH_GET_LASTLOGIN_MSG
  95         char hostname[HOST_NAME_MAX+1] = "";
  96         time_t last_login_time;
  97 # endif
  98         char *time_string;
  99         int r;
 100
 101         if (!options.print_lastlog)
 102                 return;
 103
 104 # ifdef CUSTOM_SYS_AUTH_GET_LASTLOGIN_MSG
 105         time_string = sys_auth_get_lastlogin_msg(user, uid);
 106         if (time_string != NULL) {
 107                 if ((r = sshbuf_put(loginmsg,
 108                     time_string, strlen(time_string))) != 0)
 109                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
 110                 free(time_string);
 111         }
 112 # else
 113         last_login_time = get_last_login_time(uid, user, hostname,
 114             sizeof(hostname));
 115
 116         if (last_login_time != 0) {
 117                 time_string = ctime(&last_login_time);
 118                 time_string[strcspn(time_string, "\n")] = '\0';
 119                 if (strcmp(hostname, "") == 0)
 120                         r = sshbuf_putf(loginmsg, "Last login: %s\r\n",
 121                             time_string);
 122                 else
 123                         r = sshbuf_putf(loginmsg, "Last login: %s from %s\r\n",
 124                             time_string, hostname);
 125                 if (r != 0)
 126                         fatal_fr(r, "sshbuf_putf");
 127         }
 128 # endif /* CUSTOM_SYS_AUTH_GET_LASTLOGIN_MSG */
 129 #endif /* NO_SSH_LASTLOG */
 130 }
 131
 132 /*
 133  * Records that the user has logged in.  I wish these parts of operating
 134  * systems were more standardized.
 135  */
 136 void
 137 record_login(pid_t pid, const char *tty, const char *user, uid_t uid,
 138     const char *host, struct sockaddr *addr, socklen_t addrlen)
 139 {
 140         struct logininfo *li;
 141
 142         /* save previous login details before writing new */
 143         store_lastlog_message(user, uid);
 144
 145         li = login_alloc_entry(pid, user, host, tty);
 146         login_set_addr(li, addr, addrlen);
 147         login_login(li);
 148         login_free_entry(li);
 149 }
 150
 151 #ifdef LOGIN_NEEDS_UTMPX
 152 void
 153 record_utmp_only(pid_t pid, const char *ttyname, const char *user,
 154                  const char *host, struct sockaddr *addr, socklen_t addrlen)
 155 {
 156         struct logininfo *li;
 157
 158         li = login_alloc_entry(pid, user, host, ttyname);
 159         login_set_addr(li, addr, addrlen);
 160         login_utmp_only(li);
 161         login_free_entry(li);
 162 }
 163 #endif
 164
 165 /* Records that the user has logged out. */
 166 void
 167 record_logout(pid_t pid, const char *tty, const char *user)
 168 {
 169         struct logininfo *li;
 170
 171         li = login_alloc_entry(pid, user, NULL, tty);
 172         login_logout(li);
 173         login_free_entry(li);
 174 }