7f20bb88ad
Avoid checking if the file exists before opening it. Resolves a CodeQL report of Time-of-check time-of-use filesystem race condition.
422 lines
9.8 KiB
C
422 lines
9.8 KiB
C
/*
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* SPDX-FileCopyrightText: 1989 - 1994, Julianne Frances Haugh
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* SPDX-FileCopyrightText: 1996 - 1999, Marek Michałkiewicz
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* SPDX-FileCopyrightText: 2001 - 2005, Tomasz Kłoczko
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* SPDX-FileCopyrightText: 2008 - 2009, Nicolas François
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <config.h>
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#include "defines.h"
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#include "prototypes.h"
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#include "getdef.h"
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#include <utmp.h>
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#include <assert.h>
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include "alloc.h"
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#include "sizeof.h"
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#include "string/strncpy.h"
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#include "string/strtcpy.h"
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#include "string/zustr2stp.h"
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#ident "$Id$"
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/*
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* is_my_tty -- determine if "tty" is the same TTY stdin is using
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*/
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static bool is_my_tty (const char tty[UT_LINESIZE])
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{
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char full_tty[STRLEN("/dev/") + UT_LINESIZE + 1];
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/* tmptty shall be bigger than full_tty */
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static char tmptty[sizeof(full_tty) + 1];
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full_tty[0] = '\0';
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if (tty[0] != '/')
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strcpy (full_tty, "/dev/");
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strncat (full_tty, tty, UT_LINESIZE);
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if ('\0' == tmptty[0]) {
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const char *tname = ttyname (STDIN_FILENO);
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if (NULL != tname)
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STRTCPY(tmptty, tname);
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}
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if ('\0' == tmptty[0]) {
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(void) puts (_("Unable to determine your tty name."));
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exit (EXIT_FAILURE);
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}
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return strcmp (full_tty, tmptty) == 0;
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}
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/*
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* failtmp - update the cumulative failure log
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*
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* failtmp updates the (struct utmp) formatted failure log which
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* maintains a record of all login failures.
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*/
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static void failtmp (const char *username, const struct utmp *failent)
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{
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const char *ftmp;
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int fd;
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/*
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* Get the name of the failure file. If no file has been defined
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* in login.defs, don't do this.
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*/
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ftmp = getdef_str ("FTMP_FILE");
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if (NULL == ftmp) {
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return;
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}
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/*
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* Open the file for append. It must already exist for this
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* feature to be used.
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*/
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fd = open (ftmp, O_WRONLY | O_APPEND);
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if (-1 == fd) {
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if (errno != ENOENT) {
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SYSLOG ((LOG_WARN,
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"Can't append failure of user %s to %s: %m",
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username, ftmp));
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}
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return;
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}
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/*
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* Append the new failure record and close the log file.
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*/
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if ( (write_full(fd, failent, sizeof *failent) == -1)
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|| (close (fd) != 0)) {
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SYSLOG ((LOG_WARN,
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"Can't append failure of user %s to %s.",
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username, ftmp));
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(void) close (fd);
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}
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}
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/*
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* get_current_utmp - return the most probable utmp entry for the current
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* session
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*
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* The utmp file is scanned for an entry with the same process ID.
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* The line entered by the *getty / telnetd, etc. should also match
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* the current terminal.
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*
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* When an entry is returned by get_current_utmp, and if the utmp
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* structure has a ut_id field, this field should be used to update
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* the entry information.
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*
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* Return NULL if no entries exist in utmp for the current process.
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*/
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static
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/*@null@*/ /*@only@*/struct utmp *get_current_utmp (void)
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{
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struct utmp *ut;
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struct utmp *ret = NULL;
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setutent ();
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/* First, try to find a valid utmp entry for this process. */
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while ((ut = getutent ()) != NULL) {
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if ( (ut->ut_pid == getpid ())
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#ifdef HAVE_STRUCT_UTMP_UT_ID
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&& ('\0' != ut->ut_id[0])
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#endif
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#ifdef HAVE_STRUCT_UTMP_UT_TYPE
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&& ( (LOGIN_PROCESS == ut->ut_type)
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|| (USER_PROCESS == ut->ut_type))
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#endif
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/* A process may have failed to close an entry
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* Check if this entry refers to the current tty */
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&& is_my_tty (ut->ut_line)) {
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break;
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}
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}
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if (NULL != ut) {
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ret = XMALLOC(1, struct utmp);
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memcpy (ret, ut, sizeof (*ret));
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}
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endutent ();
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return ret;
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}
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int get_session_host (char **out)
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{
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char *hostname = NULL;
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struct utmp *ut = NULL;
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int ret = 0;
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ut = get_current_utmp();
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#ifdef HAVE_STRUCT_UTMP_UT_HOST
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if ((ut != NULL) && (ut->ut_host[0] != '\0')) {
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hostname = XMALLOC(sizeof(ut->ut_host) + 1, char);
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ZUSTR2STP(hostname, ut->ut_host);
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*out = hostname;
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free (ut);
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} else {
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*out = NULL;
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ret = -2;
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}
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#else
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*out = NULL;
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ret = -2;
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#endif /* HAVE_STRUCT_UTMP_UT_HOST */
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return ret;
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}
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#ifndef USE_PAM
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/*
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* Some systems already have updwtmp() and possibly updwtmpx(). Others
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* don't, so we re-implement these functions if necessary.
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*/
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#ifndef HAVE_UPDWTMP
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static void updwtmp (const char *filename, const struct utmp *ut)
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{
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int fd;
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fd = open (filename, O_APPEND | O_WRONLY, 0);
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if (fd >= 0) {
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write_full(fd, ut, sizeof(*ut));
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close (fd);
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}
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}
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#endif /* ! HAVE_UPDWTMP */
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#endif /* ! USE_PAM */
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/*
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* prepare_utmp - prepare an utmp entry so that it can be logged in a
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* utmp/wtmp file.
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*
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* It accepts an utmp entry in input (ut) to return an entry with
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* the right ut_id. This is typically an entry returned by
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* get_current_utmp
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* If ut is NULL, ut_id will be forged based on the line argument.
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*
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* The ut_host field of the input structure may also be kept, and is
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* used to define the ut_addr/ut_addr_v6 fields. (if these fields
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* exist)
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*
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* Other fields are discarded and filed with new values (if they
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* exist).
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*
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* The returned structure shall be freed by the caller.
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*/
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static
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/*@only@*/struct utmp *prepare_utmp (const char *name,
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const char *line,
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const char *host,
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/*@null@*/const struct utmp *ut)
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{
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struct timeval tv;
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char *hostname = NULL;
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struct utmp *utent;
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assert (NULL != name);
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assert (NULL != line);
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if ( (NULL != host)
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&& ('\0' != host[0])) {
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hostname = XMALLOC(strlen(host) + 1, char);
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strcpy (hostname, host);
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#ifdef HAVE_STRUCT_UTMP_UT_HOST
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} else if ( (NULL != ut)
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&& ('\0' != ut->ut_host[0])) {
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hostname = XMALLOC(NITEMS(ut->ut_host) + 1, char);
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ZUSTR2STP(hostname, ut->ut_host);
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#endif /* HAVE_STRUCT_UTMP_UT_HOST */
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}
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if (strncmp(line, "/dev/", 5) == 0) {
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line += 5;
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}
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utent = XCALLOC (1, struct utmp);
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#ifdef HAVE_STRUCT_UTMP_UT_TYPE
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utent->ut_type = USER_PROCESS;
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#endif /* HAVE_STRUCT_UTMP_UT_TYPE */
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utent->ut_pid = getpid ();
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STRNCPY(utent->ut_line, line);
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#ifdef HAVE_STRUCT_UTMP_UT_ID
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if (NULL != ut) {
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STRNCPY(utent->ut_id, ut->ut_id);
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} else {
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/* XXX - assumes /dev/tty?? */
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STRNCPY(utent->ut_id, line + 3);
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}
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#endif /* HAVE_STRUCT_UTMP_UT_ID */
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#ifdef HAVE_STRUCT_UTMP_UT_NAME
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STRNCPY(utent->ut_name, name);
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#endif /* HAVE_STRUCT_UTMP_UT_NAME */
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#ifdef HAVE_STRUCT_UTMP_UT_USER
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STRNCPY(utent->ut_user, name);
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#endif /* HAVE_STRUCT_UTMP_UT_USER */
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if (NULL != hostname) {
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struct addrinfo *info = NULL;
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#ifdef HAVE_STRUCT_UTMP_UT_HOST
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STRNCPY(utent->ut_host, hostname);
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#endif /* HAVE_STRUCT_UTMP_UT_HOST */
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#ifdef HAVE_STRUCT_UTMP_UT_SYSLEN
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utent->ut_syslen = MIN (strlen (hostname),
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sizeof (utent->ut_host));
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#endif /* HAVE_STRUCT_UTMP_UT_SYSLEN */
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#if defined(HAVE_STRUCT_UTMP_UT_ADDR) || defined(HAVE_STRUCT_UTMP_UT_ADDR_V6)
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if (getaddrinfo (hostname, NULL, NULL, &info) == 0) {
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/* getaddrinfo might not be reliable.
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* Just try to log what may be useful.
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*/
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if (info->ai_family == AF_INET) {
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struct sockaddr_in *sa =
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(struct sockaddr_in *) info->ai_addr;
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#ifdef HAVE_STRUCT_UTMP_UT_ADDR
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memcpy (&(utent->ut_addr),
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&(sa->sin_addr),
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MIN (sizeof (utent->ut_addr),
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sizeof (sa->sin_addr)));
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#endif /* HAVE_STRUCT_UTMP_UT_ADDR */
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#ifdef HAVE_STRUCT_UTMP_UT_ADDR_V6
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memcpy (utent->ut_addr_v6,
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&(sa->sin_addr),
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MIN (sizeof (utent->ut_addr_v6),
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sizeof (sa->sin_addr)));
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} else if (info->ai_family == AF_INET6) {
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struct sockaddr_in6 *sa =
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(struct sockaddr_in6 *) info->ai_addr;
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memcpy (utent->ut_addr_v6,
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&(sa->sin6_addr),
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MIN (sizeof (utent->ut_addr_v6),
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sizeof (sa->sin6_addr)));
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#endif /* HAVE_STRUCT_UTMP_UT_ADDR_V6 */
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}
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freeaddrinfo (info);
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}
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#endif /* HAVE_STRUCT_UTMP_UT_ADDR || HAVE_STRUCT_UTMP_UT_ADDR_V6 */
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free (hostname);
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}
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/* ut_exit is only for DEAD_PROCESS */
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utent->ut_session = getsid (0);
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if (gettimeofday (&tv, NULL) == 0) {
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#ifdef HAVE_STRUCT_UTMP_UT_TIME
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utent->ut_time = tv.tv_sec;
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#endif /* HAVE_STRUCT_UTMP_UT_TIME */
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#ifdef HAVE_STRUCT_UTMP_UT_XTIME
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utent->ut_xtime = tv.tv_usec;
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#endif /* HAVE_STRUCT_UTMP_UT_XTIME */
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#ifdef HAVE_STRUCT_UTMP_UT_TV
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utent->ut_tv.tv_sec = tv.tv_sec;
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utent->ut_tv.tv_usec = tv.tv_usec;
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#endif /* HAVE_STRUCT_UTMP_UT_TV */
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}
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return utent;
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}
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/*
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* setutmp - Update an entry in utmp and log an entry in wtmp
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*
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* Return 1 on failure and 0 on success.
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*/
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static int setutmp (struct utmp *ut)
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{
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int err = 0;
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assert (NULL != ut);
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setutent ();
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if (pututline (ut) == NULL) {
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err = 1;
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}
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endutent ();
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#ifndef USE_PAM
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/* This is done by pam_lastlog */
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updwtmp (_WTMP_FILE, ut);
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#endif /* ! USE_PAM */
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return err;
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}
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int update_utmp (const char *user,
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const char *tty,
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const char *host)
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{
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struct utmp *utent, *ut;
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utent = get_current_utmp ();
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ut = prepare_utmp (user, tty, host, utent);
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(void) setutmp (ut); /* make entry in the utmp & wtmp files */
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free(utent);
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free(ut);
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return 0;
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}
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void record_failure(const char *failent_user,
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const char *tty,
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const char *hostname)
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{
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struct utmp *utent, *failent;
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if (getdef_str ("FTMP_FILE") != NULL) {
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utent = get_current_utmp ();
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failent = prepare_utmp (failent_user, tty, hostname, utent);
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failtmp (failent_user, failent);
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free (utent);
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free (failent);
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}
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}
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unsigned long active_sessions_count(const char *name, unsigned long limit)
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{
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struct utmp *ut;
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unsigned long count = 0;
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setutent ();
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while ((ut = getutent ()))
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{
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if (USER_PROCESS != ut->ut_type) {
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continue;
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}
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if ('\0' == ut->ut_user[0]) {
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continue;
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}
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if (strncmp (name, ut->ut_user, sizeof (ut->ut_user)) != 0) {
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continue;
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}
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count++;
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if (count > limit) {
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break;
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}
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}
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endutent ();
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return count;
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}
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