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/*
nsswitch.c - functions for parsing /etc/nsswitch.conf
Copyright (C) 2011-2015 Arthur de Jong
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "config.h"
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <sys/stat.h>
#include <unistd.h>
#include <time.h>
#include "common.h"
#include "log.h"
/* the cached value of whether shadow lookups use LDAP in nsswitch.conf */
#define NSSWITCH_FILE "/etc/nsswitch.conf"
#define CACHED_UNKNOWN 22
static int cached_shadow_uses_ldap = CACHED_UNKNOWN;
static time_t cached_shadow_lastcheck = 0;
#define CACHED_SHADOW_TIMEOUT (60)
static time_t nsswitch_mtime = 0;
/* the maximum line length supported of nsswitch.conf */
#define MAX_LINE_LENGTH 4096
/* check whether /etc/nsswitch.conf should be related to update
cached_shadow_uses_ldap */
void nsswitch_check_reload(void)
{
struct stat buf;
time_t t;
if ((cached_shadow_uses_ldap != CACHED_UNKNOWN) &&
((t = time(NULL)) > (cached_shadow_lastcheck + CACHED_SHADOW_TIMEOUT)))
{
cached_shadow_lastcheck = t;
if (stat(NSSWITCH_FILE, &buf))
{
log_log(LOG_ERR, "stat(%s) failed: %s", NSSWITCH_FILE, strerror(errno));
/* trigger a recheck anyway */
cached_shadow_uses_ldap = CACHED_UNKNOWN;
return;
}
/* trigger a recheck if file changed */
if (buf.st_mtime != nsswitch_mtime)
{
nsswitch_mtime = buf.st_mtime;
cached_shadow_uses_ldap = CACHED_UNKNOWN;
}
}
}
/* see if the line is a service definition for db and return a pointer to
the beginning of the services list if it is */
static const char *find_db(const char *line, const char *db)
{
int i;
i = strlen(db);
/* the line should begin with the db we're looking for */
if (strncmp(line, db, i) != 0)
return NULL;
/* followed by a : */
while (isspace(line[i]))
i++;
if (line[i] != ':')
return NULL;
i++;
while (isspace(line[i]))
i++;
return line + i;
}
/* check to see if the list of services contains the specified service */
static int has_service(const char *services, const char *service,
const char *filename, int lnr)
{
int i = 0, l;
if (services == NULL)
return 0;
l = strlen(service);
while (services[i] != '\0')
{
/* skip spaces */
while (isspace(services[i]))
i++;
/* check if this is the service */
if ((strncmp(services + i, service, l) == 0) && (!isalnum(services[i + l])))
return 1;
/* skip service name and spaces */
i++;
while (isalnum(services[i]))
i++;
while (isspace(services[i]))
i++;
/* skip action mappings */
if (services[i] == '[')
{
i++; /* skip [ */
while ((services[i] != ']') && (services[i] != '\0'))
i++;
if (services[i] != ']')
{
log_log(LOG_WARNING, "%s: error parsing line %d", filename, lnr);
return 0; /* parse error */
}
i++; /* skip ] */
}
}
return 0;
}
static int shadow_uses_ldap(void)
{
FILE *fp;
int lnr = 0;
char linebuf[MAX_LINE_LENGTH];
const char *services;
int shadow_found = 0;
int passwd_has_ldap = 0;
/* open config file */
if ((fp = fopen(NSSWITCH_FILE, "r")) == NULL)
{
log_log(LOG_ERR, "cannot open %s: %s", NSSWITCH_FILE, strerror(errno));
return 0;
}
/* read file and parse lines */
while (fgets(linebuf, sizeof(linebuf), fp) != NULL)
{
lnr++;
/* see if we have a shadow line */
services = find_db(linebuf, "shadow");
if (services != NULL)
{
shadow_found = 1;
if (has_service(services, MODULE_NAME, NSSWITCH_FILE, lnr))
{
fclose(fp);
return 1;
}
}
/* see if we have a passwd line */
services = find_db(linebuf, "passwd");
if (services != NULL)
passwd_has_ldap = has_service(services, MODULE_NAME, NSSWITCH_FILE, lnr);
}
fclose(fp);
if (shadow_found)
return 0;
return passwd_has_ldap;
}
/* check whether shadow lookups are configured to use ldap */
int nsswitch_shadow_uses_ldap(void)
{
if (cached_shadow_uses_ldap == CACHED_UNKNOWN)
{
log_log(LOG_INFO, "(re)loading %s", NSSWITCH_FILE);
cached_shadow_uses_ldap = shadow_uses_ldap();
cached_shadow_lastcheck = time(NULL);
}
return cached_shadow_uses_ldap;
}
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