1 /* $OpenBSD: sshlogin.c,v 1.28 2014/01/31 16:39:19 tedu 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 <sys/types.h> 43 #include <sys/param.h> 44 #include <sys/socket.h> 45 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <stdio.h> 49 #include <string.h> 50 #include <time.h> 51 #include <unistd.h> 52 #include <util.h> 53 #include <utmp.h> 54 #include <stdarg.h> 55 56 #include "sshlogin.h" 57 #include "log.h" 58 #include "buffer.h" 59 #include "servconf.h" 60 61 extern Buffer loginmsg; 62 extern ServerOptions options; 63 64 /* 65 * Returns the time when the user last logged in. Returns 0 if the 66 * information is not available. This must be called before record_login. 67 * The host the user logged in from will be returned in buf. 68 */ 69 time_t 70 get_last_login_time(uid_t uid, const char *logname, 71 char *buf, size_t bufsize) 72 { 73 struct lastlog ll; 74 char *lastlog; 75 int fd; 76 off_t pos, r; 77 78 lastlog = _PATH_LASTLOG; 79 buf[0] = '\0'; 80 81 fd = open(lastlog, O_RDONLY); 82 if (fd < 0) 83 return 0; 84 85 pos = (long) uid * sizeof(ll); 86 r = lseek(fd, pos, SEEK_SET); 87 if (r == -1) { 88 error("%s: lseek: %s", __func__, strerror(errno)); 89 close(fd); 90 return (0); 91 } 92 if (r != pos) { 93 debug("%s: truncated lastlog", __func__); 94 close(fd); 95 return (0); 96 } 97 if (read(fd, &ll, sizeof(ll)) != sizeof(ll)) { 98 close(fd); 99 return 0; 100 } 101 close(fd); 102 if (bufsize > sizeof(ll.ll_host) + 1) 103 bufsize = sizeof(ll.ll_host) + 1; 104 strncpy(buf, ll.ll_host, bufsize - 1); 105 buf[bufsize - 1] = '\0'; 106 return (time_t)ll.ll_time; 107 } 108 109 /* 110 * Generate and store last login message. This must be done before 111 * login_login() is called and lastlog is updated. 112 */ 113 static void 114 store_lastlog_message(const char *user, uid_t uid) 115 { 116 char *time_string, hostname[MAXHOSTNAMELEN] = "", buf[512]; 117 time_t last_login_time; 118 119 if (!options.print_lastlog) 120 return; 121 122 last_login_time = get_last_login_time(uid, user, hostname, 123 sizeof(hostname)); 124 125 if (last_login_time != 0) { 126 time_string = ctime(&last_login_time); 127 time_string[strcspn(time_string, "\n")] = '\0'; 128 if (strcmp(hostname, "") == 0) 129 snprintf(buf, sizeof(buf), "Last login: %s\r\n", 130 time_string); 131 else 132 snprintf(buf, sizeof(buf), "Last login: %s from %s\r\n", 133 time_string, hostname); 134 buffer_append(&loginmsg, buf, strlen(buf)); 135 } 136 } 137 138 /* 139 * Records that the user has logged in. I wish these parts of operating 140 * systems were more standardized. 141 */ 142 void 143 record_login(pid_t pid, const char *tty, const char *user, uid_t uid, 144 const char *host, struct sockaddr *addr, socklen_t addrlen) 145 { 146 int fd; 147 struct lastlog ll; 148 char *lastlog; 149 struct utmp u; 150 151 /* save previous login details before writing new */ 152 store_lastlog_message(user, uid); 153 154 /* Construct an utmp/wtmp entry. */ 155 memset(&u, 0, sizeof(u)); 156 strncpy(u.ut_line, tty + 5, sizeof(u.ut_line)); 157 u.ut_time = time(NULL); 158 strncpy(u.ut_name, user, sizeof(u.ut_name)); 159 strncpy(u.ut_host, host, sizeof(u.ut_host)); 160 161 login(&u); 162 lastlog = _PATH_LASTLOG; 163 164 /* Update lastlog unless actually recording a logout. */ 165 if (strcmp(user, "") != 0) { 166 /* 167 * It is safer to memset the lastlog structure first because 168 * some systems might have some extra fields in it (e.g. SGI) 169 */ 170 memset(&ll, 0, sizeof(ll)); 171 172 /* Update lastlog. */ 173 ll.ll_time = time(NULL); 174 strncpy(ll.ll_line, tty + 5, sizeof(ll.ll_line)); 175 strncpy(ll.ll_host, host, sizeof(ll.ll_host)); 176 fd = open(lastlog, O_RDWR); 177 if (fd >= 0) { 178 lseek(fd, (off_t) ((long) uid * sizeof(ll)), SEEK_SET); 179 if (write(fd, &ll, sizeof(ll)) != sizeof(ll)) 180 logit("Could not write %.100s: %.100s", lastlog, strerror(errno)); 181 close(fd); 182 } 183 } 184 } 185 186 /* Records that the user has logged out. */ 187 void 188 record_logout(pid_t pid, const char *tty) 189 { 190 const char *line = tty + 5; /* /dev/ttyq8 -> ttyq8 */ 191 if (logout(line)) 192 logwtmp(line, "", ""); 193 } 194