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/*
 * 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) && !defined(__linux)
#error THIS CODE IS KNOWN TO WORK ONLY ON LINUX !!!
#endif

#include <glib.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 */
#ifndef LIMITS_FILE
#define LIMITS_FILE "/etc/security/limits.conf"
#endif

#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 */

struct user_limits_struct {
	int supported;
	int src_soft;
	int src_hard;
	struct rlimit limit;
};

/* internal data */
struct pam_limit_s {
	int priority;	 /* the priority to run user process with */
	struct user_limits_struct limits[RLIM_NLIMITS];
	struct passwd *pwd;
};

#define LIMIT_PRI RLIM_NLIMITS+1

#define LIMIT_SOFT  1
#define LIMIT_HARD  2

#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 */

typedef enum {
	LIMHANDLE_OK = 0,
	LIMHANDLE_ERROR = -1,
	LIMHANDLE_IGNORE = 1
} limhandle_t;

static limhandle_t init_limits(struct pam_limit_s *pl) {
	int i, r;

	for(i = 0; i < RLIM_NLIMITS; i++) {
		errno = 0;
		r = getrlimit(i, &pl->limits[i].limit);
		if (r == -1) {
			pl->limits[i].supported = 0;
			if (errno != EINVAL) {
				g_printerr("Couldn't getrlimit: %s\n", g_strerror(errno));
				return LIMHANDLE_ERROR;
			}
		} 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) {
		g_printerr("Couldn't getpriority: %s\n", g_strerror(errno));
		return LIMHANDLE_ERROR;
	}

	return LIMHANDLE_OK;
}

static void
process_limit (int source, const char *lim_type,
               const char *lim_item, const char *lim_value,
               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, "priority") == 0) {
		limit_item = LIMIT_PRI;
	} else {
		g_printerr("unknown limit item '%s'\n", 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 {
		g_printerr("unknown limit type '%s'\n", 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
#ifdef RLIMIT_NICE
		|| limit_item == RLIMIT_NICE
#endif
		) {
		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) {
			g_printerr("wrong limit value '%s' for limit type '%s'\n",
				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) {
			g_printerr("wrong limit value '%s' for limit type '%s'",
				lim_value, lim_type);
			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;
		break;
#endif
	}

	if (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;
		}
	}
	return;
}

static gboolean pam_modutil_user_in_group_nam_nam(struct passwd *pwd, const char *group) {
	struct group *grp;
	size_t i;
	grp = getgrnam(group);

	if (pwd == NULL || grp == NULL) return FALSE;
	if (pwd->pw_gid == grp->gr_gid) return TRUE;

	for (i = 0; (grp->gr_mem != NULL) && (grp->gr_mem[i] != NULL); i++) {
		if (strcmp(pwd->pw_name, grp->gr_mem[i]) == 0) {
			return TRUE;
		}
	}

	return FALSE;
}

static int parse_config_file(const char *conf_file, struct passwd *pwd, struct pam_limit_s *pl) {
	FILE *fil;
	char buf[LINE_LENGTH];

	fil = fopen(conf_file, "r");
	if (fil == NULL) {
		g_printerr("cannot read settings from '%s': %s", conf_file, g_strerror(errno));
		return -1;
	}

	/* 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(pwd->pw_name, domain) == 0) /* this user have a limit */
				process_limit(LIMITS_DEF_USER, ltype, item, value, pl);
			else if (domain[0]=='@') {
				if (pam_modutil_user_in_group_nam_nam(pwd, domain+1))
					process_limit(LIMITS_DEF_GROUP, ltype, item, value, pl);
			} else if (domain[0]=='%') {
				if (strcmp(domain,"%") == 0)
					process_limit(LIMITS_DEF_ALL, ltype, item, value, pl);
				else if (pam_modutil_user_in_group_nam_nam(pwd, domain+1)) {
					process_limit(LIMITS_DEF_ALLGROUP, ltype, item, value, pl);
				}
			} else if (strcmp(domain, "*") == 0) {
				process_limit(LIMITS_DEF_DEFAULT, ltype, item, value, pl);
			}
		} else if (i == 2 && ltype[0] == '-') { /* Probably a no-limit line */
			if (strcmp(pwd->pw_name, domain) == 0) {
				fclose(fil);
				return LIMHANDLE_IGNORE;
			} else if (domain[0] == '@' && pam_modutil_user_in_group_nam_nam(pwd, domain+1)) {
				fclose(fil);
				return LIMHANDLE_IGNORE;
			}
		} else {
			g_printerr("invalid line '%s' - skipped\n", buf);
		}
	}
	fclose(fil);
	return LIMHANDLE_OK;
}

static int setup_limits(struct pam_limit_s *pl) {
	int i;
	int status;
	int retval = LIMHANDLE_OK;

	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 = LIMHANDLE_ERROR;
	}

	status = setpriority(PRIO_PROCESS, 0, pl->priority);
	if (status != 0) {
		retval = LIMHANDLE_ERROR;
	}

	return retval;
}

/* now the session stuff */
int pam_set_limits(const char *conf_file, const char *username);
int pam_set_limits(const char *conf_file, const char *username) {
	int retval;
	struct pam_limit_s pl;
	struct passwd *pwd;

	pwd = getpwnam(username);
	if (NULL == pwd) return LIMHANDLE_ERROR;

	if (!conf_file) conf_file = LIMITS_FILE;
	memset(&pl, 0, sizeof(pl));

	retval = init_limits(&pl);
	if (retval != LIMHANDLE_OK) {
		g_printerr("cannot initialize\n");
		return retval;
	}

	retval = parse_config_file(conf_file, pwd, &pl);
	if (retval == LIMHANDLE_IGNORE) {
		return LIMHANDLE_OK;
	}
	if (retval != LIMHANDLE_OK) {
		g_printerr("error parsing the configuration file\n");
		return retval;
	}

	retval = setup_limits(&pl);
	if (retval != LIMHANDLE_OK) {
		return retval;
	}

	return LIMHANDLE_OK;
}

/*
 * 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.
 */