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 <sys/types.h> 43 #include <sys/socket.h> 44 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <time.h> 50 #include <unistd.h> 51 #include <util.h> 52 #include <utmp.h> 53 #include <stdarg.h> 54 #include <limits.h> 55 56 #include "sshlogin.h" 57 #include "ssherr.h" 58 #include "log.h" 59 #include "sshbuf.h" 60 #include "misc.h" 61 #include "servconf.h" 62 63 extern struct sshbuf *loginmsg; 64 extern ServerOptions options; 65 66 /* 67 * Returns the time when the user last logged in. Returns 0 if the 68 * information is not available. This must be called before record_login. 69 * The host the user logged in from will be returned in buf. 70 */ 71 time_t 72 get_last_login_time(uid_t uid, const char *logname, 73 char *buf, size_t bufsize) 74 { 75 struct lastlog ll; 76 char *lastlog; 77 int fd; 78 off_t pos, r; 79 80 lastlog = _PATH_LASTLOG; 81 buf[0] = '\0'; 82 83 fd = open(lastlog, O_RDONLY); 84 if (fd == -1) 85 return 0; 86 87 pos = (off_t)uid * sizeof(ll); 88 r = lseek(fd, pos, SEEK_SET); 89 if (r == -1) { 90 error_f("lseek: %s", strerror(errno)); 91 close(fd); 92 return (0); 93 } 94 if (r != pos) { 95 debug_f("truncated lastlog"); 96 close(fd); 97 return (0); 98 } 99 if (read(fd, &ll, sizeof(ll)) != sizeof(ll)) { 100 close(fd); 101 return 0; 102 } 103 close(fd); 104 if (bufsize > sizeof(ll.ll_host) + 1) 105 bufsize = sizeof(ll.ll_host) + 1; 106 strncpy(buf, ll.ll_host, bufsize - 1); 107 buf[bufsize - 1] = '\0'; 108 return (time_t)ll.ll_time; 109 } 110 111 /* 112 * Generate and store last login message. This must be done before 113 * login_login() is called and lastlog is updated. 114 */ 115 static void 116 store_lastlog_message(const char *user, uid_t uid) 117 { 118 char *time_string, hostname[HOST_NAME_MAX+1] = ""; 119 time_t last_login_time; 120 int r; 121 122 if (!options.print_lastlog) 123 return; 124 125 last_login_time = get_last_login_time(uid, user, hostname, 126 sizeof(hostname)); 127 128 if (last_login_time != 0) { 129 time_string = ctime(&last_login_time); 130 time_string[strcspn(time_string, "\n")] = '\0'; 131 if (strcmp(hostname, "") == 0) 132 r = sshbuf_putf(loginmsg, "Last login: %s\r\n", 133 time_string); 134 else 135 r = sshbuf_putf(loginmsg, "Last login: %s from %s\r\n", 136 time_string, hostname); 137 if (r != 0) 138 fatal_fr(r, "sshbuf_putf"); 139 } 140 } 141 142 /* 143 * Records that the user has logged in. I wish these parts of operating 144 * systems were more standardized. 145 */ 146 void 147 record_login(pid_t pid, const char *tty, const char *user, uid_t uid, 148 const char *host, struct sockaddr *addr, socklen_t addrlen) 149 { 150 int fd; 151 struct lastlog ll; 152 char *lastlog; 153 struct utmp u; 154 155 /* save previous login details before writing new */ 156 store_lastlog_message(user, uid); 157 158 /* Construct an utmp/wtmp entry. */ 159 memset(&u, 0, sizeof(u)); 160 strncpy(u.ut_line, tty + 5, sizeof(u.ut_line)); 161 u.ut_time = time(NULL); 162 strncpy(u.ut_name, user, sizeof(u.ut_name)); 163 strncpy(u.ut_host, host, sizeof(u.ut_host)); 164 165 login(&u); 166 lastlog = _PATH_LASTLOG; 167 168 /* Update lastlog unless actually recording a logout. */ 169 if (strcmp(user, "") != 0) { 170 /* 171 * It is safer to memset the lastlog structure first because 172 * some systems might have some extra fields in it (e.g. SGI) 173 */ 174 memset(&ll, 0, sizeof(ll)); 175 176 /* Update lastlog. */ 177 ll.ll_time = time(NULL); 178 strncpy(ll.ll_line, tty + 5, sizeof(ll.ll_line)); 179 strncpy(ll.ll_host, host, sizeof(ll.ll_host)); 180 fd = open(lastlog, O_RDWR); 181 if (fd >= 0) { 182 lseek(fd, (off_t)uid * sizeof(ll), SEEK_SET); 183 if (write(fd, &ll, sizeof(ll)) != sizeof(ll)) 184 logit("Could not write %.100s: %.100s", lastlog, strerror(errno)); 185 close(fd); 186 } 187 } 188 } 189 190 /* Records that the user has logged out. */ 191 void 192 record_logout(pid_t pid, const char *tty) 193 { 194 const char *line = tty + 5; /* /dev/ttyq8 -> ttyq8 */ 195 if (logout(line)) 196 logwtmp(line, "", ""); 197 } 198