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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.
*/
#include "tcpwrapper.h"
#include <unistd.h>
#include <string.h>
#include <rpc/rpc.h>
#include <rpc/pmap_prot.h>
#include <syslog.h>
#include <netdb.h>
#include <pwd.h>
#include <sys/types.h>
#include <sys/signal.h>
#ifdef SYSV40
#include <netinet/in.h>
#include <rpc/rpcent.h>
#endif
static void logit();
static void toggle_verboselog();
int verboselog = 0;
int allow_severity = LOG_INFO;
int deny_severity = LOG_WARNING;
/* A handful of macros for "readability". */
/* coming from libwrap.a (tcp_wrappers) */
extern int hosts_ctl(char *daemon, char *name, char *addr, char *user);
#define legal_port(a,p) \
(ntohs((a)->sin_port) < IPPORT_RESERVED || (p) >= IPPORT_RESERVED)
#define log_bad_port(addr, proc, prog) \
logit(deny_severity, addr, proc, prog, ": request from unprivileged port")
#define log_bad_host(addr, proc, prog) \
logit(deny_severity, addr, proc, prog, ": request from unauthorized host")
#define log_bad_owner(addr, proc, prog) \
logit(deny_severity, addr, proc, prog, ": request from non-local host")
#define log_no_forward(addr, proc, prog) \
logit(deny_severity, addr, proc, prog, ": request not forwarded")
#define log_client(addr, proc, prog) \
logit(allow_severity, addr, proc, prog, "")
int
good_client(daemon, addr)
char *daemon;
struct sockaddr_in *addr;
{
struct hostent *hp;
char **sp;
char *tmpname;
/* Check the IP address first. */
if (hosts_ctl(daemon, "", inet_ntoa(addr->sin_addr), ""))
return 1;
/* Check the hostname. */
hp = gethostbyaddr ((const char *) &(addr->sin_addr),
sizeof (addr->sin_addr), AF_INET);
if (!hp)
return 0;
/* must make sure the hostent is authorative. */
tmpname = alloca (strlen (hp->h_name) + 1);
strcpy (tmpname, hp->h_name);
hp = gethostbyname(tmpname);
if (hp) {
/* now make sure the "addr->sin_addr" is on the list */
for (sp = hp->h_addr_list ; *sp ; sp++) {
if (memcmp(*sp, &(addr->sin_addr), hp->h_length)==0)
break;
}
if (!*sp)
/* it was a FAKE. */
return 0;
}
else
/* never heard of it. misconfigured DNS? */
return 0;
/* Check the official name first. */
if (hosts_ctl(daemon, "", hp->h_name, ""))
return 1;
/* Check aliases. */
for (sp = hp->h_aliases; *sp ; sp++) {
if (hosts_ctl(daemon, "", *sp, ""))
return 1;
}
/* No match */
return 0;
}
/* check_startup - additional startup code */
void check_startup()
{
/*
* Give up root privileges so that we can never allocate a privileged
* port when forwarding an rpc request.
*
* Fix 8/3/00 Philipp Knirsch: First lookup our rpc user. If we find it,
* switch to that uid, otherwise simply resue the old bin user and print
* out a warning in syslog.
*/
struct passwd *pwent;
pwent = getpwnam("rpc");
if (pwent == NULL) {
syslog(LOG_WARNING, "user rpc not found, reverting to user bin");
if (setuid(1) == -1) {
syslog(LOG_ERR, "setuid(1) failed: %m");
exit(1);
}
}
else {
if (setuid(pwent->pw_uid) == -1) {
syslog(LOG_WARNING, "setuid() to rpc user failed: %m");
if (setuid(1) == -1) {
syslog(LOG_ERR, "setuid(1) failed: %m");
exit(1);
}
}
}
(void) signal(SIGINT, toggle_verboselog);
}
/* check_default - additional checks for NULL, DUMP, GETPORT and unknown */
int
check_default(daemon, addr, proc, prog)
char *daemon;
struct sockaddr_in *addr;
u_long proc;
u_long prog;
{
if (!(from_local(addr) || good_client(daemon, addr))) {
log_bad_host(addr, proc, prog);
return (FALSE);
}
if (verboselog)
log_client(addr, proc, prog);
return (TRUE);
}
/* check_privileged_port - additional checks for privileged-port updates */
int
check_privileged_port(addr, proc, prog, port)
struct sockaddr_in *addr;
u_long proc;
u_long prog;
u_long port;
{
#ifdef CHECK_PORT
if (!legal_port(addr, port)) {
log_bad_port(addr, proc, prog);
return (FALSE);
}
#endif
return (TRUE);
}
/* toggle_verboselog - toggle verbose logging flag */
static void toggle_verboselog(sig)
int sig;
{
(void) signal(sig, toggle_verboselog);
verboselog = !verboselog;
}
/* logit - report events of interest via the syslog daemon */
static void logit(severity, addr, procnum, prognum, text)
int severity;
struct sockaddr_in *addr;
u_long procnum;
u_long prognum;
char *text;
{
char *procname;
char procbuf[16 + 4 * sizeof(u_long)];
char *progname;
char progbuf[16 + 4 * sizeof(u_long)];
struct rpcent *rpc;
/*
* Fork off a process or the portmap daemon might hang while
* getrpcbynumber() or syslog() does its thing.
*
* Don't forget to wait for the children, too...
*/
if (fork() == 0) {
/* Try to map program number to name. */
if (prognum == 0) {
progname = "";
} else if ((rpc = getrpcbynumber((int) prognum))) {
progname = rpc->r_name;
} else {
snprintf(progname = progbuf, sizeof (progbuf),
"prog (%lu)", prognum);
}
/* Try to map procedure number to name. */
snprintf(procname = procbuf, sizeof (procbuf),
"proc (%lu)", (u_long) procnum);
/* Write syslog record. */
syslog(severity, "connect from %s to %s in %s%s",
inet_ntoa(addr->sin_addr), procname, progname, text);
exit(0);
}
}
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