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/* This is copied from portmap 4.0-29 in RedHat. */
/*
* pmap_check - additional portmap security.
*
* Always reject non-local requests to update the portmapper tables.
*
* Refuse to forward mount requests to the nfs mount daemon. Otherwise, the
* requests would appear to come from the local system, and nfs export
* restrictions could be bypassed.
*
* Refuse to forward requests to the nfsd process.
*
* Refuse to forward requests to NIS (YP) daemons; The only exception is the
* YPPROC_DOMAIN_NONACK broadcast rpc call that is used to establish initial
* contact with the NIS server.
*
* Always allocate an unprivileged port when forwarding a request.
*
* If compiled with -DCHECK_PORT, require that requests to register or
* unregister a privileged port come from a privileged port. This makes it
* more difficult to replace a critical service by a trojan.
*
* If compiled with -DHOSTS_ACCESS, reject requests from hosts that are not
* authorized by the /etc/hosts.{allow,deny} files. The local system is
* always treated as an authorized host. The access control tables are never
* consulted for requests from the local system, and are always consulted
* for requests from other hosts.
*
* Author: Wietse Venema (wietse@wzv.win.tue.nl), dept. of Mathematics and
* Computing Science, Eindhoven University of Technology, The Netherlands.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_LIBWRAP
#include <unistd.h>
#include <string.h>
#include <rpc/rpc.h>
#include <rpc/pmap_prot.h>
#include <netdb.h>
#include <pwd.h>
#include <sys/types.h>
#include <sys/signal.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <tcpd.h>
#include "tcpwrapper.h"
#include "xlog.h"
#ifdef SYSV40
#include <netinet/in.h>
#include <rpc/rpcent.h>
#endif
static int check_files(void);
#define ALLOW 1
#define DENY 0
typedef struct _haccess_t {
TAILQ_ENTRY(_haccess_t) list;
int allowed;
struct in_addr addr;
} haccess_t;
#define HASH_TABLE_SIZE 1021
typedef struct _hash_head {
TAILQ_HEAD(host_list, _haccess_t) h_head;
} hash_head;
hash_head haccess_tbl[HASH_TABLE_SIZE];
static haccess_t *haccess_lookup(struct sockaddr_in *addr, u_long);
static unsigned long
strtoint(const char *str)
{
unsigned long i, n = 0;
size_t len = strlen(str);
for (i = 0; i < len; i++)
n += (unsigned char)str[i] * i;
return n;
}
static unsigned int
hashint(const unsigned long num)
{
return (unsigned int)(num % HASH_TABLE_SIZE);
}
static unsigned int
HASH(const char *addr, const unsigned long program)
{
return hashint(strtoint(addr) + program);
}
static void
haccess_add(struct sockaddr_in *addr, u_long prog, int allowed)
{
hash_head *head;
haccess_t *hptr;
unsigned int hash;
hptr = (haccess_t *)malloc(sizeof(haccess_t));
if (hptr == NULL)
return;
hash = HASH(inet_ntoa(addr->sin_addr), prog);
head = &(haccess_tbl[hash]);
hptr->allowed = allowed;
hptr->addr.s_addr = addr->sin_addr.s_addr;
if (TAILQ_EMPTY(&head->h_head))
TAILQ_INSERT_HEAD(&head->h_head, hptr, list);
else
TAILQ_INSERT_TAIL(&head->h_head, hptr, list);
}
haccess_t *haccess_lookup(struct sockaddr_in *addr, u_long prog)
{
hash_head *head;
haccess_t *hptr;
unsigned int hash;
hash = HASH(inet_ntoa(addr->sin_addr), prog);
head = &(haccess_tbl[hash]);
TAILQ_FOREACH(hptr, &head->h_head, list) {
if (hptr->addr.s_addr == addr->sin_addr.s_addr)
return hptr;
}
return NULL;
}
static void
logit(const struct sockaddr_in *sin)
{
char buf[INET_ADDRSTRLEN];
xlog_warn("connect from %s denied: request from unauthorized host",
inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)));
}
static int
good_client(char *name, struct sockaddr_in *addr)
{
struct request_info req;
request_init(&req, RQ_DAEMON, name, RQ_CLIENT_SIN, addr, 0);
sock_methods(&req);
if (hosts_access(&req))
return ALLOW;
return DENY;
}
/* check_files - check to see if either access files have changed */
static int check_files()
{
static time_t allow_mtime, deny_mtime;
struct stat astat, dstat;
int changed = 0;
if (stat("/etc/hosts.allow", &astat) < 0)
astat.st_mtime = 0;
if (stat("/etc/hosts.deny", &dstat) < 0)
dstat.st_mtime = 0;
if(!astat.st_mtime || !dstat.st_mtime)
return changed;
if (astat.st_mtime != allow_mtime)
changed = 1;
else if (dstat.st_mtime != deny_mtime)
changed = 1;
allow_mtime = astat.st_mtime;
deny_mtime = dstat.st_mtime;
return changed;
}
/**
* check_default - additional checks for NULL, DUMP, GETPORT and unknown
* @name: pointer to '\0'-terminated ASCII string containing name of the
* daemon requesting the access check
* @addr: pointer to socket address containing address of caller
* @prog: RPC program number caller is attempting to access
*
* Returns TRUE if the caller is allowed access; otherwise FALSE is returned.
*/
int
check_default(char *name, struct sockaddr_in *addr, u_long prog)
{
haccess_t *acc = NULL;
int changed = check_files();
acc = haccess_lookup(addr, prog);
if (acc && changed == 0)
return acc->allowed;
if (!(from_local((struct sockaddr *)addr) || good_client(name, addr))) {
logit(addr);
if (acc)
acc->allowed = FALSE;
else
haccess_add(addr, prog, FALSE);
return (FALSE);
}
if (acc)
acc->allowed = TRUE;
else
haccess_add(addr, prog, TRUE);
return (TRUE);
}
#endif /* HAVE_LIBWRAP */
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