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
get_last_login_time(uid_t uid,const char * logname,char * buf,size_t bufsize)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
store_lastlog_message(const char * user,uid_t uid)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
record_login(pid_t pid,const char * tty,const char * user,uid_t uid,const char * host,struct sockaddr * addr,socklen_t addrlen)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
record_logout(pid_t pid,const char * tty)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