/*
* pam_limits - impose resource limits when opening a user session
*
* 1.6 - modified for PLD (added process priority settings)
* by Marcin Korzonek <mkorz@shadow.eu.org>
* 1.5 - Elliot Lee's "max system logins patch"
* 1.4 - addressed bug in configuration file parser
* 1.3 - modified the configuration file format
* 1.2 - added 'debug' and 'conf=' arguments
* 1.1 - added @group support
* 1.0 - initial release - Linux ONLY
*
* See end for Copyright information
*/
#if !(defined(linux))
#error THIS CODE IS KNOWN TO WORK ONLY ON LINUX !!!
#endif
#include "config.h"
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <errno.h>
#include <syslog.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/resource.h>
#include <limits.h>
#include <utmp.h>
#ifndef UT_USER /* some systems have ut_name instead of ut_user */
#define UT_USER ut_user
#endif
#include <grp.h>
#include <pwd.h>
/* Module defines */
#define LINE_LENGTH 1024
#define LIMITS_DEF_USER 0 /* limit was set by an user entry */
#define LIMITS_DEF_GROUP 1 /* limit was set by a group entry */
#define LIMITS_DEF_ALLGROUP 2 /* limit was set by a group entry */
#define LIMITS_DEF_ALL 3 /* limit was set by an default entry */
#define LIMITS_DEF_DEFAULT 4 /* limit was set by an default entry */
#define LIMITS_DEF_NONE 5 /* this limit was not set yet */
static const char *limits_def_names[] = {
"USER",
"GROUP",
"ALLGROUP",
"ALL",
"DEFAULT",
"NONE",
NULL
};
struct user_limits_struct {
int supported;
int src_soft;
int src_hard;
struct rlimit limit;
};
/* internal data */
struct pam_limit_s {
int login_limit; /* the max logins limit */
int login_limit_def; /* which entry set the login limit */
int flag_numsyslogins; /* whether to limit logins only for a
specific user or to count all logins */
int priority; /* the priority to run user process with */
struct user_limits_struct limits[RLIM_NLIMITS];
char conf_file[BUFSIZ];
int utmp_after_pam_call;
char login_group[LINE_LENGTH];
};
#define LIMIT_LOGIN RLIM_NLIMITS+1
#define LIMIT_NUMSYSLOGINS RLIM_NLIMITS+2
#define LIMIT_PRI RLIM_NLIMITS+3
#define LIMIT_SOFT 1
#define LIMIT_HARD 2
#define PAM_SM_SESSION
#include <security/pam_modules.h>
#include <security/_pam_macros.h>
#include <security/pam_modutil.h>
#include <security/pam_ext.h>
/* argument parsing */
#define PAM_DEBUG_ARG 0x0001
#define PAM_DO_SETREUID 0x0002
#define PAM_UTMP_EARLY 0x0004
static int
_pam_parse (const pam_handle_t *pamh, int argc, const char **argv,
struct pam_limit_s *pl)
{
int ctrl=0;
/* step through arguments */
for (ctrl=0; argc-- > 0; ++argv) {
/* generic options */
if (!strcmp(*argv,"debug")) {
ctrl |= PAM_DEBUG_ARG;
} else if (!strncmp(*argv,"conf=",5)) {
strncpy(pl->conf_file,*argv+5,sizeof(pl->conf_file)-1);
} else if (!strncmp(*argv,"change_uid",10)) {
ctrl |= PAM_DO_SETREUID;
} else if (!strcmp(*argv,"utmp_early")) {
ctrl |= PAM_UTMP_EARLY;
} else {
pam_syslog(pamh, LOG_ERR, "unknown option: %s", *argv);
}
}
pl->conf_file[sizeof(pl->conf_file) - 1] = '\0';
return ctrl;
}
#define LIMITED_OK 0 /* limit setting appeared to work */
#define LIMIT_ERR 1 /* error setting a limit */
#define LOGIN_ERR 2 /* too many logins err */
/* Counts the number of user logins and check against the limit*/
static int
check_logins (pam_handle_t *pamh, const char *name, int limit, int ctrl,
struct pam_limit_s *pl)
{
struct utmp *ut;
int count;
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG,
"checking logins for '%s' (maximum of %d)", name, limit);
}
if (limit < 0)
return 0; /* no limits imposed */
if (limit == 0) /* maximum 0 logins ? */ {
pam_syslog(pamh, LOG_WARNING, "No logins allowed for '%s'", name);
return LOGIN_ERR;
}
setutent();
/* Because there is no definition about when an application
actually adds a utmp entry, some applications bizarrely do the
utmp call before the have PAM authenticate them to the system:
you're logged it, sort of...? Anyway, you can use the
"utmp_early" module argument in your PAM config file to make
allowances for this sort of problem. (There should be a PAM
standard for this, since if a module wants to actually map a
username then any early utmp entry will be for the unmapped
name = broken.) */
if (ctrl & PAM_UTMP_EARLY) {
count = 0;
} else {
count = 1;
}
while((ut = getutent())) {
#ifdef USER_PROCESS
if (ut->ut_type != USER_PROCESS) {
continue;
}
#endif
if (ut->UT_USER[0] == '\0') {
continue;
}
if (!pl->flag_numsyslogins) {
if (((pl->login_limit_def == LIMITS_DEF_USER)
|| (pl->login_limit_def == LIMITS_DEF_GROUP)
|| (pl->login_limit_def == LIMITS_DEF_DEFAULT))
&& strncmp(name, ut->UT_USER, sizeof(ut->UT_USER)) != 0) {
continue;
}
if ((pl->login_limit_def == LIMITS_DEF_ALLGROUP)
&& !pam_modutil_user_in_group_nam_nam(pamh, ut->UT_USER, pl->login_group)) {
continue;
}
}
if (++count > limit) {
break;
}
}
endutent();
if (count > limit) {
if (name) {
pam_syslog(pamh, LOG_WARNING,
"Too many logins (max %d) for %s", limit, name);
} else {
pam_syslog(pamh, LOG_WARNING, "Too many system logins (max %d)", limit);
}
return LOGIN_ERR;
}
return 0;
}
static int init_limits(struct pam_limit_s *pl)
{
int i;
int retval = PAM_SUCCESS;
D(("called."));
for(i = 0; i < RLIM_NLIMITS; i++) {
int r = getrlimit(i, &pl->limits[i].limit);
if (r == -1) {
pl->limits[i].supported = 0;
if (errno != EINVAL) {
retval = !PAM_SUCCESS;
}
} else {
pl->limits[i].supported = 1;
pl->limits[i].src_soft = LIMITS_DEF_NONE;
pl->limits[i].src_hard = LIMITS_DEF_NONE;
}
}
errno = 0;
pl->priority = getpriority (PRIO_PROCESS, 0);
if (pl->priority == -1 && errno != 0)
retval = !PAM_SUCCESS;
pl->login_limit = -2;
pl->login_limit_def = LIMITS_DEF_NONE;
return retval;
}
static void
process_limit (const pam_handle_t *pamh, int source, const char *lim_type,
const char *lim_item, const char *lim_value,
int ctrl, struct pam_limit_s *pl)
{
int limit_item;
int limit_type = 0;
int int_value = 0;
rlim_t rlimit_value = 0;
char *endptr;
const char *value_orig = lim_value;
if (ctrl & PAM_DEBUG_ARG)
pam_syslog(pamh, LOG_DEBUG, "%s: processing %s %s %s for %s",
__FUNCTION__, lim_type, lim_item, lim_value,
limits_def_names[source]);
if (strcmp(lim_item, "cpu") == 0)
limit_item = RLIMIT_CPU;
else if (strcmp(lim_item, "fsize") == 0)
limit_item = RLIMIT_FSIZE;
else if (strcmp(lim_item, "data") == 0)
limit_item = RLIMIT_DATA;
else if (strcmp(lim_item, "stack") == 0)
limit_item = RLIMIT_STACK;
else if (strcmp(lim_item, "core") == 0)
limit_item = RLIMIT_CORE;
else if (strcmp(lim_item, "rss") == 0)
limit_item = RLIMIT_RSS;
else if (strcmp(lim_item, "nproc") == 0)
limit_item = RLIMIT_NPROC;
else if (strcmp(lim_item, "nofile") == 0)
limit_item = RLIMIT_NOFILE;
else if (strcmp(lim_item, "memlock") == 0)
limit_item = RLIMIT_MEMLOCK;
else if (strcmp(lim_item, "as") == 0)
limit_item = RLIMIT_AS;
#ifdef RLIMIT_LOCKS
else if (strcmp(lim_item, "locks") == 0)
limit_item = RLIMIT_LOCKS;
#endif
#ifdef RLIMIT_SIGPENDING
else if (strcmp(lim_item, "sigpending") == 0)
limit_item = RLIMIT_SIGPENDING;
#endif
#ifdef RLIMIT_MSGQUEUE
else if (strcmp(lim_item, "msgqueue") == 0)
limit_item = RLIMIT_MSGQUEUE;
#endif
#ifdef RLIMIT_NICE
else if (strcmp(lim_item, "nice") == 0)
limit_item = RLIMIT_NICE;
#endif
#ifdef RLIMIT_RTPRIO
else if (strcmp(lim_item, "rtprio") == 0)
limit_item = RLIMIT_RTPRIO;
#endif
else if (strcmp(lim_item, "maxlogins") == 0) {
limit_item = LIMIT_LOGIN;
pl->flag_numsyslogins = 0;
} else if (strcmp(lim_item, "maxsyslogins") == 0) {
limit_item = LIMIT_NUMSYSLOGINS;
pl->flag_numsyslogins = 1;
} else if (strcmp(lim_item, "priority") == 0) {
limit_item = LIMIT_PRI;
} else {
pam_syslog(pamh, LOG_DEBUG, "unknown limit item '%s'", lim_item);
return;
}
if (strcmp(lim_type,"soft")==0)
limit_type=LIMIT_SOFT;
else if (strcmp(lim_type, "hard")==0)
limit_type=LIMIT_HARD;
else if (strcmp(lim_type,"-")==0)
limit_type=LIMIT_SOFT | LIMIT_HARD;
else if (limit_item != LIMIT_LOGIN && limit_item != LIMIT_NUMSYSLOGINS) {
pam_syslog(pamh, LOG_DEBUG, "unknown limit type '%s'", lim_type);
return;
}
if (limit_item != LIMIT_PRI
#ifdef RLIMIT_NICE
&& limit_item != RLIMIT_NICE
#endif
&& (strcmp(lim_value, "-1") == 0
|| strcmp(lim_value, "-") == 0 || strcmp(lim_value, "unlimited") == 0
|| strcmp(lim_value, "infinity") == 0)) {
int_value = -1;
rlimit_value = RLIM_INFINITY;
} else if (limit_item == LIMIT_PRI || limit_item == LIMIT_LOGIN ||
#ifdef RLIMIT_NICE
limit_item == RLIMIT_NICE ||
#endif
limit_item == LIMIT_NUMSYSLOGINS) {
long temp;
temp = strtol (lim_value, &endptr, 10);
temp = temp < INT_MAX ? temp : INT_MAX;
int_value = temp > INT_MIN ? temp : INT_MIN;
if (int_value == 0 && value_orig == endptr) {
pam_syslog(pamh, LOG_DEBUG,
"wrong limit value '%s' for limit type '%s'",
lim_value, lim_type);
return;
}
} else {
#ifdef __USE_FILE_OFFSET64
rlimit_value = strtoull (lim_value, &endptr, 10);
#else
rlimit_value = strtoul (lim_value, &endptr, 10);
#endif
if (rlimit_value == 0 && value_orig == endptr) {
pam_syslog(pamh, LOG_DEBUG,
"wrong limit value '%s' for limit type '%s'",
lim_value, lim_type);
return;
}
}
/* one more special case when limiting logins */
if ((source == LIMITS_DEF_ALL || source == LIMITS_DEF_ALLGROUP)
&& (limit_item != LIMIT_LOGIN)) {
if (ctrl & PAM_DEBUG_ARG)
pam_syslog(pamh, LOG_DEBUG,
"'%%' domain valid for maxlogins type only");
return;
}
switch(limit_item) {
case RLIMIT_CPU:
if (rlimit_value != RLIM_INFINITY)
rlimit_value *= 60;
break;
case RLIMIT_FSIZE:
case RLIMIT_DATA:
case RLIMIT_STACK:
case RLIMIT_CORE:
case RLIMIT_RSS:
case RLIMIT_MEMLOCK:
case RLIMIT_AS:
if (rlimit_value != RLIM_INFINITY)
rlimit_value *= 1024;
break;
#ifdef RLIMIT_NICE
case RLIMIT_NICE:
if (int_value > 19)
int_value = 19;
rlimit_value = 19 - int_value;
#endif
break;
}
if ( (limit_item != LIMIT_LOGIN)
&& (limit_item != LIMIT_NUMSYSLOGINS)
&& (limit_item != LIMIT_PRI) ) {
if (limit_type & LIMIT_SOFT) {
if (pl->limits[limit_item].src_soft < source) {
return;
} else {
pl->limits[limit_item].limit.rlim_cur = rlimit_value;
pl->limits[limit_item].src_soft = source;
}
}
if (limit_type & LIMIT_HARD) {
if (pl->limits[limit_item].src_hard < source) {
return;
} else {
pl->limits[limit_item].limit.rlim_max = rlimit_value;
pl->limits[limit_item].src_hard = source;
}
}
} else {
/* recent kernels support negative priority limits (=raise priority) */
if (limit_item == LIMIT_PRI) {
pl->priority = int_value;
} else {
if (pl->login_limit_def < source) {
return;
} else {
pl->login_limit = int_value;
pl->login_limit_def = source;
}
}
}
return;
}
static int parse_config_file(pam_handle_t *pamh, const char *uname, int ctrl,
struct pam_limit_s *pl)
{
FILE *fil;
char buf[LINE_LENGTH];
#define CONF_FILE (pl->conf_file[0])?pl->conf_file:LIMITS_FILE
/* check for the LIMITS_FILE */
if (ctrl & PAM_DEBUG_ARG)
pam_syslog(pamh, LOG_DEBUG, "reading settings from '%s'", CONF_FILE);
fil = fopen(CONF_FILE, "r");
if (fil == NULL) {
pam_syslog (pamh, LOG_WARNING,
"cannot read settings from %s: %m", CONF_FILE);
return PAM_SERVICE_ERR;
}
#undef CONF_FILE
/* init things */
memset(buf, 0, sizeof(buf));
/* start the show */
while (fgets(buf, LINE_LENGTH, fil) != NULL) {
char domain[LINE_LENGTH];
char ltype[LINE_LENGTH];
char item[LINE_LENGTH];
char value[LINE_LENGTH];
int i;
size_t j;
char *tptr;
tptr = buf;
/* skip the leading white space */
while (*tptr && isspace(*tptr))
tptr++;
strncpy(buf, tptr, sizeof(buf)-1);
buf[sizeof(buf)-1] = '\0';
/* Rip off the comments */
tptr = strchr(buf,'#');
if (tptr)
*tptr = '\0';
/* Rip off the newline char */
tptr = strchr(buf,'\n');
if (tptr)
*tptr = '\0';
/* Anything left ? */
if (!strlen(buf)) {
memset(buf, 0, sizeof(buf));
continue;
}
memset(domain, 0, sizeof(domain));
memset(ltype, 0, sizeof(ltype));
memset(item, 0, sizeof(item));
memset(value, 0, sizeof(value));
i = sscanf(buf,"%s%s%s%s", domain, ltype, item, value);
D(("scanned line[%d]: domain[%s], ltype[%s], item[%s], value[%s]",
i, domain, ltype, item, value));
for(j=0; j < strlen(ltype); j++)
ltype[j]=tolower(ltype[j]);
for(j=0; j < strlen(item); j++)
item[j]=tolower(item[j]);
for(j=0; j < strlen(value); j++)
value[j]=tolower(value[j]);
if (i == 4) { /* a complete line */
if (strcmp(uname, domain) == 0) /* this user have a limit */
process_limit(pamh, LIMITS_DEF_USER, ltype, item, value, ctrl, pl);
else if (domain[0]=='@') {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG,
"checking if %s is in group %s",
uname, domain + 1);
}
if (pam_modutil_user_in_group_nam_nam(pamh, uname, domain+1))
process_limit(pamh, LIMITS_DEF_GROUP, ltype, item, value, ctrl,
pl);
} else if (domain[0]=='%') {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG,
"checking if %s is in group %s",
uname, domain + 1);
}
if (strcmp(domain,"%") == 0)
process_limit(pamh, LIMITS_DEF_ALL, ltype, item, value, ctrl,
pl);
else if (pam_modutil_user_in_group_nam_nam(pamh, uname, domain+1)) {
strcpy(pl->login_group, domain+1);
process_limit(pamh, LIMITS_DEF_ALLGROUP, ltype, item, value, ctrl,
pl);
}
} else if (strcmp(domain, "*") == 0)
process_limit(pamh, LIMITS_DEF_DEFAULT, ltype, item, value, ctrl,
pl);
} else if (i == 2 && ltype[0] == '-') { /* Probably a no-limit line */
if (strcmp(uname, domain) == 0) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG, "no limits for '%s'", uname);
}
fclose(fil);
return PAM_IGNORE;
} else if (domain[0] == '@' && pam_modutil_user_in_group_nam_nam(pamh, uname, domain+1)) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG,
"no limits for '%s' in group '%s'",
uname, domain+1);
}
fclose(fil);
return PAM_IGNORE;
}
} else {
pam_syslog(pamh, LOG_WARNING, "invalid line '%s' - skipped", buf);
}
}
fclose(fil);
return PAM_SUCCESS;
}
static int setup_limits(pam_handle_t *pamh,
const char *uname, uid_t uid, int ctrl,
struct pam_limit_s *pl)
{
int i;
int status;
int retval = LIMITED_OK;
if (uid == 0) {
/* do not impose limits (+ve limits anyway) on the superuser */
if (pl->priority > 0) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG,
"user '%s' has UID 0 - no limits imposed", uname);
}
pl->priority = 0;
}
}
for (i=0, status=LIMITED_OK; i<RLIM_NLIMITS; i++) {
if (!pl->limits[i].supported) {
/* skip it if its not known to the system */
continue;
}
if (pl->limits[i].src_soft == LIMITS_DEF_NONE &&
pl->limits[i].src_hard == LIMITS_DEF_NONE) {
/* skip it if its not initialized */
continue;
}
if (pl->limits[i].limit.rlim_cur > pl->limits[i].limit.rlim_max)
pl->limits[i].limit.rlim_cur = pl->limits[i].limit.rlim_max;
status |= setrlimit(i, &pl->limits[i].limit);
}
if (status) {
retval = LIMIT_ERR;
}
status = setpriority(PRIO_PROCESS, 0, pl->priority);
if (status != 0) {
retval = LIMIT_ERR;
}
if (uid == 0) {
D(("skip login limit check for uid=0"));
} else if (pl->login_limit > 0) {
if (check_logins(pamh, uname, pl->login_limit, ctrl, pl) == LOGIN_ERR) {
retval |= LOGIN_ERR;
}
} else if (pl->login_limit == 0) {
retval |= LOGIN_ERR;
}
return retval;
}
/* now the session stuff */
PAM_EXTERN int
pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
int argc, const char **argv)
{
int retval;
char *user_name;
struct passwd *pwd;
int ctrl;
struct pam_limit_s pl;
D(("called."));
memset(&pl, 0, sizeof(pl));
ctrl = _pam_parse(pamh, argc, argv, &pl);
retval = pam_get_item( pamh, PAM_USER, (void*) &user_name );
if ( user_name == NULL || retval != PAM_SUCCESS ) {
pam_syslog(pamh, LOG_CRIT, "open_session - error recovering username");
return PAM_SESSION_ERR;
}
pwd = getpwnam(user_name);
if (!pwd) {
if (ctrl & PAM_DEBUG_ARG)
pam_syslog(pamh, LOG_WARNING,
"open_session username '%s' does not exist", user_name);
return PAM_SESSION_ERR;
}
retval = init_limits(&pl);
if (retval != PAM_SUCCESS) {
pam_syslog(pamh, LOG_WARNING, "cannot initialize");
return PAM_ABORT;
}
retval = parse_config_file(pamh, pwd->pw_name, ctrl, &pl);
if (retval == PAM_IGNORE) {
D(("the configuration file has an applicable '<domain> -' entry"));
return PAM_SUCCESS;
}
if (retval != PAM_SUCCESS) {
pam_syslog(pamh, LOG_WARNING, "error parsing the configuration file");
return retval;
}
if (ctrl & PAM_DO_SETREUID) {
setreuid(pwd->pw_uid, -1);
}
retval = setup_limits(pamh, pwd->pw_name, pwd->pw_uid, ctrl, &pl);
if (retval & LOGIN_ERR)
pam_error(pamh, _("Too many logins for '%s'."), pwd->pw_name);
if (retval != LIMITED_OK) {
return PAM_PERM_DENIED;
}
return PAM_SUCCESS;
}
PAM_EXTERN int
pam_sm_close_session (pam_handle_t *pamh UNUSED, int flags UNUSED,
int argc UNUSED, const char **argv UNUSED)
{
/* nothing to do */
return PAM_SUCCESS;
}
#ifdef PAM_STATIC
/* static module data */
struct pam_module _pam_limits_modstruct = {
"pam_limits",
NULL,
NULL,
NULL,
pam_sm_open_session,
pam_sm_close_session,
NULL
};
#endif
/*
* Copyright (c) Cristian Gafton, 1996-1997, <gafton@redhat.com>
* 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, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 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 author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``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 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.
*/