freebsd-dev/lib/libc/gen/getutxent.c
Gleb Smirnoff a173916590 Make getutxent(3) more robust against bad utx.log files. Whenever we read
zeroes, don't stop processing the file, but read until its end or valid
data.

In collaboration with:	ed
2013-10-15 13:32:01 +00:00

247 lines
4.9 KiB
C

/*-
* Copyright (c) 2010 Ed Schouten <ed@FreeBSD.org>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/endian.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <utmpx.h>
#include "utxdb.h"
#include "un-namespace.h"
#ifdef __NO_TLS
static FILE *uf = NULL;
static int udb;
#else
static _Thread_local FILE *uf = NULL;
static _Thread_local int udb;
#endif
int
setutxdb(int db, const char *file)
{
struct stat sb;
switch (db) {
case UTXDB_ACTIVE:
if (file == NULL)
file = _PATH_UTX_ACTIVE;
break;
case UTXDB_LASTLOGIN:
if (file == NULL)
file = _PATH_UTX_LASTLOGIN;
break;
case UTXDB_LOG:
if (file == NULL)
file = _PATH_UTX_LOG;
break;
default:
errno = EINVAL;
return (-1);
}
if (uf != NULL)
fclose(uf);
uf = fopen(file, "re");
if (uf == NULL)
return (-1);
if (db != UTXDB_LOG) {
/* Safety check: never use broken files. */
if (_fstat(fileno(uf), &sb) != -1 &&
sb.st_size % sizeof(struct futx) != 0) {
fclose(uf);
uf = NULL;
errno = EFTYPE;
return (-1);
}
/* Prevent reading of partial records. */
(void)setvbuf(uf, NULL, _IOFBF,
rounddown(BUFSIZ, sizeof(struct futx)));
}
udb = db;
return (0);
}
void
setutxent(void)
{
setutxdb(UTXDB_ACTIVE, NULL);
}
void
endutxent(void)
{
if (uf != NULL) {
fclose(uf);
uf = NULL;
}
}
static int
getfutxent(struct futx *fu)
{
if (uf == NULL)
setutxent();
if (uf == NULL)
return (-1);
if (udb == UTXDB_LOG) {
uint16_t len;
retry:
if (fread(&len, sizeof(len), 1, uf) != 1)
return (-1);
len = be16toh(len);
if (len == 0) {
/*
* XXX: Though zero-size records are valid in theory,
* they can never occur in practice. Zero-size records
* indicate file corruption. Seek one byte forward, to
* see if we can find a record there.
*/
ungetc('\0', uf);
goto retry;
}
if (len > sizeof *fu) {
/* Forward compatibility. */
if (fread(fu, sizeof(*fu), 1, uf) != 1)
return (-1);
fseek(uf, len - sizeof(*fu), SEEK_CUR);
} else {
/* Partial record. */
memset(fu, 0, sizeof(*fu));
if (fread(fu, len, 1, uf) != 1)
return (-1);
}
} else {
if (fread(fu, sizeof(*fu), 1, uf) != 1)
return (-1);
}
return (0);
}
struct utmpx *
getutxent(void)
{
struct futx fu;
if (getfutxent(&fu) != 0)
return (NULL);
return (futx_to_utx(&fu));
}
struct utmpx *
getutxid(const struct utmpx *id)
{
struct futx fu;
for (;;) {
if (getfutxent(&fu) != 0)
return (NULL);
switch (fu.fu_type) {
case USER_PROCESS:
case INIT_PROCESS:
case LOGIN_PROCESS:
case DEAD_PROCESS:
switch (id->ut_type) {
case USER_PROCESS:
case INIT_PROCESS:
case LOGIN_PROCESS:
case DEAD_PROCESS:
if (memcmp(fu.fu_id, id->ut_id,
MIN(sizeof(fu.fu_id), sizeof(id->ut_id))) ==
0)
goto found;
}
break;
default:
if (fu.fu_type == id->ut_type)
goto found;
break;
}
}
found:
return (futx_to_utx(&fu));
}
struct utmpx *
getutxline(const struct utmpx *line)
{
struct futx fu;
for (;;) {
if (getfutxent(&fu) != 0)
return (NULL);
switch (fu.fu_type) {
case USER_PROCESS:
case LOGIN_PROCESS:
if (strncmp(fu.fu_line, line->ut_line,
MIN(sizeof(fu.fu_line), sizeof(line->ut_line))) ==
0)
goto found;
break;
}
}
found:
return (futx_to_utx(&fu));
}
struct utmpx *
getutxuser(const char *user)
{
struct futx fu;
for (;;) {
if (getfutxent(&fu) != 0)
return (NULL);
switch (fu.fu_type) {
case USER_PROCESS:
if (strncmp(fu.fu_user, user, sizeof(fu.fu_user)) == 0)
goto found;
break;
}
}
found:
return (futx_to_utx(&fu));
}