shadow/libmisc/failure.c

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/*
* Copyright (c) 1989 - 1994, Julianne Frances Haugh
* Copyright (c) 1996 - 1998, Marek Michałkiewicz
* Copyright (c) 2002 - 2005, Tomasz Kłoczko
* 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.
* 3. The name of the copyright holders or contributors may not be used to
* endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``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 COPYRIGHT
* HOLDERS OR CONTRIBUTORS 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.
*/
#include <config.h>
#ident "$Id$"
#include <fcntl.h>
#include <stdio.h>
#include "defines.h"
#include "faillog.h"
#include "getdef.h"
#include "failure.h"
#define YEAR (365L*DAY)
/*
* failure - make failure entry
*
* failure() creates a new (struct faillog) entry or updates an
* existing one with the current failed login information.
*/
void failure (uid_t uid, const char *tty, struct faillog *fl)
{
int fd;
/*
* Don't do anything if failure logging isn't set up.
*/
if ((fd = open (FAILLOG_FILE, O_RDWR)) < 0)
return;
/*
* The file is indexed by UID value meaning that shared UID's
* share failure log records. That's OK since they really
* share just about everything else ...
*/
lseek (fd, (off_t) (sizeof *fl) * uid, SEEK_SET);
if (read (fd, (char *) fl, sizeof *fl) != sizeof *fl)
memzero (fl, sizeof *fl);
/*
* Update the record. We increment the failure count to log the
* latest failure. The only concern here is overflow, and we'll
* check for that. The line name and time of day are both
* updated as well.
*/
if (fl->fail_cnt + 1 > 0)
fl->fail_cnt++;
strncpy (fl->fail_line, tty, sizeof fl->fail_line);
time (&fl->fail_time);
/*
* Seek back to the correct position in the file and write the
* record out. Ideally we should lock the file in case the same
* account is being logged simultaneously. But the risk doesn't
* seem that great.
*/
lseek (fd, (off_t) (sizeof *fl) * uid, SEEK_SET);
write (fd, (char *) fl, sizeof *fl);
close (fd);
}
static int too_many_failures (const struct faillog *fl)
{
time_t now;
if (fl->fail_max == 0 || fl->fail_cnt < fl->fail_max)
return 0;
if (fl->fail_locktime == 0)
return 1; /* locked until reset manually */
time (&now);
if (fl->fail_time + fl->fail_locktime < now)
return 0; /* enough time since last failure */
return 1;
}
/*
* failcheck - check for failures > allowable
*
* failcheck() is called AFTER the password has been validated. If the
* account has been "attacked" with too many login failures, failcheck()
* returns FALSE to indicate that the login should be denied even though
* the password is valid.
*/
int failcheck (uid_t uid, struct faillog *fl, int failed)
{
int fd;
struct faillog fail;
/*
* Suppress the check if the log file isn't there.
*/
if ((fd = open (FAILLOG_FILE, O_RDWR)) < 0)
return 1;
/*
* Get the record from the file and determine if the user has
* exceeded the failure limit. If "max" is zero, any number
* of failures are permitted. Only when "max" is non-zero and
* "cnt" is greater than or equal to "max" is the account
* considered to be locked.
*
* If read fails, there is no record for this user yet (the
* file is initially zero length and extended by writes), so
* no need to reset the count.
*/
lseek (fd, (off_t) (sizeof *fl) * uid, SEEK_SET);
if (read (fd, (char *) fl, sizeof *fl) != sizeof *fl) {
close (fd);
return 1;
}
if (too_many_failures (fl)) {
close (fd);
return 0;
}
/*
* The record is updated if this is not a failure. The count will
* be reset to zero, but the rest of the information will be left
* in the record in case someone wants to see where the failed
* login originated.
*/
if (!failed) {
fail = *fl;
fail.fail_cnt = 0;
lseek (fd, (off_t) sizeof fail * uid, SEEK_SET);
write (fd, (char *) &fail, sizeof fail);
}
close (fd);
return 1;
}
/*
* failprint - print line of failure information
*
* failprint takes a (struct faillog) entry and formats it into a
* message which is displayed at login time.
*/
void failprint (const struct faillog *fail)
{
struct tm *tp;
#if HAVE_STRFTIME
char lasttimeb[256];
char *lasttime = lasttimeb;
#else
char *lasttime;
#endif
time_t NOW;
if (fail->fail_cnt == 0)
return;
tp = localtime (&(fail->fail_time));
time (&NOW);
#if HAVE_STRFTIME
/*
* Print all information we have.
*/
strftime (lasttimeb, sizeof lasttimeb, "%c", tp);
#else
/*
* Do the same thing, but don't use strftime since it
* probably doesn't exist on this system
*/
lasttime = asctime (tp);
lasttime[24] = '\0';
if (NOW - fail->fail_time < YEAR)
lasttime[19] = '\0';
if (NOW - fail->fail_time < DAY)
lasttime = lasttime + 11;
if (*lasttime == ' ')
lasttime++;
#endif
printf (ngettext ("%d failure since last login.\n"
"Last was %s on %s.\n",
"%d failures since last login.\n"
"Last was %s on %s.\n",
fail->fail_cnt),
fail->fail_cnt, lasttime, fail->fail_line);
}
/*
* failtmp - update the cummulative failure log
*
* failtmp updates the (struct utmp) formatted failure log which
* maintains a record of all login failures.
*/
void failtmp (
#ifdef HAVE_UTMPX_H
const struct utmpx *failent
#else
const struct utmp *failent
#endif
)
{
char *ftmp;
int fd;
/*
* Get the name of the failure file. If no file has been defined
* in login.defs, don't do this.
*/
if (!(ftmp = getdef_str ("FTMP_FILE")))
return;
/*
* Open the file for append. It must already exist for this
* feature to be used.
*/
if ((fd = open (ftmp, O_WRONLY | O_APPEND)) == -1)
return;
/*
* Output the new failure record and close the log file.
*/
write (fd, (const char *) failent, sizeof *failent);
close (fd);
}