shadow/libmisc/limits.c
nekral-guest 10396f9536 * libmisc/limits.c: Parse the limits, umask, nice, maxlogin, file
limit with getlog() / getulong(). This also means, in case of
	non-PAM enabled systems, that the umask specified on the GECOS
	fields should start with a 0 if specified in octal. (it used to be
	force to octal). Do the appropriate cast and range checking.
2009-04-24 22:56:42 +00:00

499 lines
12 KiB
C

/*
* Copyright (c) 1989 - 1994, Julianne Frances Haugh
* Copyright (c) 1996 - 1999, Marek Michałkiewicz
* Copyright (c) 2003 - 2006, Tomasz Kłoczko
* Copyright (c) 2007 - 2008, Nicolas François
* 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.
*/
/*
* Separated from setup.c. --marekm
* Resource limits thanks to Cristian Gafton.
*/
#include <config.h>
#ifndef USE_PAM
#ident "$Id$"
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include "prototypes.h"
#include "defines.h"
#include <pwd.h>
#include "getdef.h"
#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#define LIMITS
#endif
#ifdef LIMITS
#ifndef LIMITS_FILE
#define LIMITS_FILE "/etc/limits"
#endif
#define LOGIN_ERROR_RLIMIT 1
#define LOGIN_ERROR_LOGIN 2
/* Set a limit on a resource */
/*
* rlimit - RLIMIT_XXXX
* value - string value to be read
* multiplier - value*multiplier is the actual limit
*/
static int
setrlimit_value (unsigned int resource, const char *value,
unsigned int multiplier)
{
struct rlimit rlim;
long limit;
if (getlong (value, &limit) == 0) {
return 0;
}
limit *= multiplier;
if (limit != (rlim_t) limit) {
return 0;
}
rlim.rlim_cur = (rlim_t) limit;
rlim.rlim_max = (rlim_t) limit;
if (setrlimit (resource, &rlim) != 0) {
return LOGIN_ERROR_RLIMIT;
}
return 0;
}
static int set_prio (const char *value)
{
int prio;
char **endptr = (char **) &value;
prio = strtol (value, endptr, 10);
if ((0 == prio) && (value == *endptr)) {
return 0;
}
if (setpriority (PRIO_PROCESS, 0, prio) != 0) {
return LOGIN_ERROR_RLIMIT;
}
return 0;
}
static int set_umask (const char *value)
{
unsigned long int mask;
if ( (getulong (value, &mask) == 0)
|| (mask != (mode_t) mask)) {
return 0;
}
(void) umask ((mode_t) mask);
return 0;
}
/* Counts the number of user logins and check against the limit */
static int check_logins (const char *name, const char *maxlogins)
{
#if HAVE_UTMPX_H
struct utmpx *ut;
#else
struct utmp *ut;
#endif
unsigned long limit, count;
if (getulong (maxlogins, &limit) == 0) {
return 0;
}
if (0 == limit) { /* maximum 0 logins ? */
SYSLOG ((LOG_WARN, "No logins allowed for `%s'\n", name));
return LOGIN_ERROR_LOGIN;
}
count = 0;
#if HAVE_UTMPX_H
setutxent ();
while ((ut = getutxent ())) {
#else
setutent ();
while ((ut = getutent ())) {
#endif
if (USER_PROCESS != ut->ut_type) {
continue;
}
if ('\0' == ut->ut_user[0]) {
continue;
}
if (strncmp (name, ut->ut_user, sizeof (ut->ut_user)) != 0) {
continue;
}
count++;
if (count > limit) {
break;
}
}
#if HAVE_UTMPX_H
endutxent ();
#else
endutent ();
#endif
/*
* This is called after setutmp(), so the number of logins counted
* includes the user who is currently trying to log in.
*/
if (count > limit) {
SYSLOG ((LOG_WARN, "Too many logins (max %d) for %s\n",
limit, name));
return LOGIN_ERROR_LOGIN;
}
return 0;
}
/* Function setup_user_limits - checks/set limits for the curent login
* Original idea from Joel Katz's lshell. Ported to shadow-login
* by Cristian Gafton - gafton@sorosis.ro
*
* We are passed a string of the form ('BASH' constants for ulimit)
* [Aa][Cc][Dd][Ff][Mm][Nn][Rr][Ss][Tt][Uu][Ll][Pp][Ii][Oo]
* (eg. 'C2F256D2048N5' or 'C2 F256 D2048 N5')
* where:
* [Aa]: a = RLIMIT_AS max address space (KB)
* [Cc]: c = RLIMIT_CORE max core file size (KB)
* [Dd]: d = RLIMIT_DATA max data size (KB)
* [Ff]: f = RLIMIT_FSIZE max file size (KB)
* [Mm]: m = RLIMIT_MEMLOCK max locked-in-memory address space (KB)
* [Nn]: n = RLIMIT_NOFILE max number of open files
* [Rr]: r = RLIMIT_RSS max resident set size (KB)
* [Ss]: s = RLIMIT_STACK max stack size (KB)
* [Tt]: t = RLIMIT_CPU max CPU time (MIN)
* [Uu]: u = RLIMIT_NPROC max number of processes
* [Kk]: k = file creation masK (umask)
* [Ll]: l = max number of logins for this user
* [Pp]: p = process priority -20..20 (negative = high, positive = low)
* [Ii]: i = RLIMIT_NICE max nice value (0..39 translates to 20..-19)
* [Oo]: o = RLIMIT_RTPRIO max real time priority (linux/sched.h 0..MAX_RT_PRIO)
*
* Return value:
* 0 = okay, of course
* LOGIN_ERROR_RLIMIT = error setting some RLIMIT
* LOGIN_ERROR_LOGIN = error - too many logins for this user
*
* buf - the limits string
* name - the username
*/
static int do_user_limits (const char *buf, const char *name)
{
const char *pp;
int retval = 0;
bool reported = false;
pp = buf;
while ('\0' != *pp) {
switch (*pp++) {
#ifdef RLIMIT_AS
case 'a':
case 'A':
/* RLIMIT_AS - max address space (KB) */
retval |= setrlimit_value (RLIMIT_AS, pp, 1024);
break;
#endif
#ifdef RLIMIT_CPU
case 't':
case 'T':
/* RLIMIT_CPU - max CPU time (MIN) */
retval |= setrlimit_value (RLIMIT_CPU, pp, 60);
break;
#endif
#ifdef RLIMIT_DATA
case 'd':
case 'D':
/* RLIMIT_DATA - max data size (KB) */
retval |= setrlimit_value (RLIMIT_DATA, pp, 1024);
break;
#endif
#ifdef RLIMIT_FSIZE
case 'f':
case 'F':
/* RLIMIT_FSIZE - Maximum filesize (KB) */
retval |= setrlimit_value (RLIMIT_FSIZE, pp, 1024);
break;
#endif
#ifdef RLIMIT_NPROC
case 'u':
case 'U':
/* RLIMIT_NPROC - max number of processes */
retval |= setrlimit_value (RLIMIT_NPROC, pp, 1);
break;
#endif
#ifdef RLIMIT_CORE
case 'c':
case 'C':
/* RLIMIT_CORE - max core file size (KB) */
retval |= setrlimit_value (RLIMIT_CORE, pp, 1024);
break;
#endif
#ifdef RLIMIT_MEMLOCK
case 'm':
case 'M':
/* RLIMIT_MEMLOCK - max locked-in-memory address space (KB) */
retval |= setrlimit_value (RLIMIT_MEMLOCK, pp, 1024);
break;
#endif
#ifdef RLIMIT_NOFILE
case 'n':
case 'N':
/* RLIMIT_NOFILE - max number of open files */
retval |= setrlimit_value (RLIMIT_NOFILE, pp, 1);
break;
#endif
#ifdef RLIMIT_RSS
case 'r':
case 'R':
/* RLIMIT_RSS - max resident set size (KB) */
retval |= setrlimit_value (RLIMIT_RSS, pp, 1024);
break;
#endif
#ifdef RLIMIT_STACK
case 's':
case 'S':
/* RLIMIT_STACK - max stack size (KB) */
retval |= setrlimit_value (RLIMIT_STACK, pp, 1024);
break;
#endif
#ifdef RLIMIT_NICE
case 'i':
case 'I':
/* RLIMIT_NICE - max scheduling priority (0..39) */
retval |= setrlimit_value (RLIMIT_NICE, pp, 1);
break;
#endif
#ifdef RLIMIT_RTPRIO
case 'o':
case 'O':
/* RLIMIT_RTPRIO - max real time priority (0..MAX_RT_PRIO) */
retval |= setrlimit_value (RLIMIT_RTPRIO, pp, 1);
break;
#endif
case 'k':
case 'K':
retval |= set_umask (pp);
break;
case 'l':
case 'L':
/* LIMIT the number of concurrent logins */
retval |= check_logins (name, pp);
break;
case 'p':
case 'P':
retval |= set_prio (pp);
break;
default:
/* Only report invalid strings once */
if (!reported) {
SYSLOG ((LOG_WARN,
"Invalid limit string: '%s'",
pp-1));
reported = true;
retval |= LOGIN_ERROR_RLIMIT;
}
}
}
return retval;
}
static int setup_user_limits (const char *uname)
{
/* TODO: allow and use @group syntax --cristiang */
FILE *fil;
char buf[1024];
char name[1024];
char limits[1024];
char deflimits[1024];
char tempbuf[1024];
/* init things */
memzero (buf, sizeof (buf));
memzero (name, sizeof (name));
memzero (limits, sizeof (limits));
memzero (deflimits, sizeof (deflimits));
memzero (tempbuf, sizeof (tempbuf));
/* start the checks */
fil = fopen (LIMITS_FILE, "r");
if (fil == NULL) {
return 0;
}
/* The limits file have the following format:
* - '#' (comment) chars only as first chars on a line;
* - username must start on first column
* A better (smarter) checking should be done --cristiang */
while (fgets (buf, 1024, fil) != NULL) {
if (('#' == buf[0]) || ('\n' == buf[0])) {
continue;
}
memzero (tempbuf, sizeof (tempbuf));
/* a valid line should have a username, then spaces,
* then limits
* we allow the format:
* username L2 D2048 R4096
* where spaces={' ',\t}. Also, we reject invalid limits.
* Imposing a limit should be done with care, so a wrong
* entry means no care anyway :-). A '-' as a limits
* strings means no limits --cristiang */
if (sscanf (buf, "%s%[ACDFMNRSTULPIOacdfmnrstulpio0-9 \t-]",
name, tempbuf) == 2) {
if (strcmp (name, uname) == 0) {
strcpy (limits, tempbuf);
break;
} else if (strcmp (name, "*") == 0) {
strcpy (deflimits, tempbuf);
}
}
}
(void) fclose (fil);
if (limits[0] == '\0') {
/* no user specific limits */
if (deflimits[0] == '\0') { /* no default limits */
return 0;
}
strcpy (limits, deflimits); /* use the default limits */
}
return do_user_limits (limits, uname);
}
#endif /* LIMITS */
static void setup_usergroups (const struct passwd *info)
{
const struct group *grp;
mode_t tmpmask;
/*
* if not root, and UID == GID, and username is the same as primary
* group name, set umask group bits to be the same as owner bits
* (examples: 022 -> 002, 077 -> 007).
*/
if ((0 != info->pw_uid) && (info->pw_uid == info->pw_gid)) {
/* local, no need for xgetgrgid */
grp = getgrgid (info->pw_gid);
if ( (NULL != grp)
&& (strcmp (info->pw_name, grp->gr_name) == 0)) {
tmpmask = umask (0777);
tmpmask = (tmpmask & ~070) | ((tmpmask >> 3) & 070);
(void) umask (tmpmask);
}
}
}
/*
* set the process nice, ulimit, and umask from the password file entry
*/
void setup_limits (const struct passwd *info)
{
char *cp;
if (getdef_bool ("USERGROUPS_ENAB")) {
setup_usergroups (info);
}
/*
* See if the GECOS field contains values for NICE, UMASK or ULIMIT.
* If this feature is enabled in /etc/login.defs, we make those
* values the defaults for this login session.
*/
if (getdef_bool ("QUOTAS_ENAB")) {
#ifdef LIMITS
if (info->pw_uid != 0) {
if (setup_user_limits (info->pw_name) &
LOGIN_ERROR_LOGIN) {
(void) fputs (_("Too many logins.\n"), stderr);
(void) sleep (2); /* XXX: Should be FAIL_DELAY */
exit (1);
}
}
#endif
for (cp = info->pw_gecos; cp != NULL; cp = strchr (cp, ',')) {
if (',' == *cp) {
cp++;
}
if (strncmp (cp, "pri=", 4) == 0) {
long int inc;
if ( (getlong (cp + 4, &inc) == 1)
&& (inc >= -20) && (inc <= 20)) {
errno = 0;
if ( (nice ((int) inc) != -1)
|| (0 != errno)) {
continue;
}
}
/* Failed to parse or failed to nice() */
SYSLOG ((LOG_WARN,
"Can't set the nice value for user %s",
info->pw_name));
continue;
}
if (strncmp (cp, "ulimit=", 7) == 0) {
long int blocks;
if ( (getlong (cp + 7, &blocks) == 0)
|| (blocks != (int) blocks)
|| (set_filesize_limit ((int) blocks) != 0)) {
SYSLOG ((LOG_WARN,
"Can't set the ulimit for user %s",
info->pw_name));
}
continue;
}
if (strncmp (cp, "umask=", 6) == 0) {
unsigned long int mask;
if ( (getulong (cp + 6, &mask) == 0)
|| (mask != (mode_t) mask)) {
SYSLOG ((LOG_WARN,
"Can't set umask value for user %s",
info->pw_name));
} else {
(void) umask ((mode_t) mask);
}
continue;
}
}
}
}
#else /* !USE_PAM */
extern int errno; /* warning: ANSI C forbids an empty source file */
#endif /* !USE_PAM */