1 /* This is copied from portmap 4.0-29 in RedHat. */
4 * pmap_check - additional portmap security.
6 * Always reject non-local requests to update the portmapper tables.
8 * Refuse to forward mount requests to the nfs mount daemon. Otherwise, the
9 * requests would appear to come from the local system, and nfs export
10 * restrictions could be bypassed.
12 * Refuse to forward requests to the nfsd process.
14 * Refuse to forward requests to NIS (YP) daemons; The only exception is the
15 * YPPROC_DOMAIN_NONACK broadcast rpc call that is used to establish initial
16 * contact with the NIS server.
18 * Always allocate an unprivileged port when forwarding a request.
20 * If compiled with -DCHECK_PORT, require that requests to register or
21 * unregister a privileged port come from a privileged port. This makes it
22 * more difficult to replace a critical service by a trojan.
24 * If compiled with -DHOSTS_ACCESS, reject requests from hosts that are not
25 * authorized by the /etc/hosts.{allow,deny} files. The local system is
26 * always treated as an authorized host. The access control tables are never
27 * consulted for requests from the local system, and are always consulted
28 * for requests from other hosts.
30 * Author: Wietse Venema (wietse@wzv.win.tue.nl), dept. of Mathematics and
31 * Computing Science, Eindhoven University of Technology, The Netherlands.
37 #include <tcpwrapper.h>
41 #include <rpc/pmap_prot.h>
45 #include <sys/types.h>
46 #include <sys/signal.h>
47 #include <sys/queue.h>
52 #include <netinet/in.h>
53 #include <rpc/rpcent.h>
56 static void logit(int severity, struct sockaddr_in *addr,
57 u_long procnum, u_long prognum, char *text);
58 static void toggle_verboselog(int sig);
59 static int check_files(void);
62 int allow_severity = LOG_INFO;
63 int deny_severity = LOG_WARNING;
65 /* A handful of macros for "readability". */
68 /* coming from libwrap.a (tcp_wrappers) */
69 extern int hosts_ctl(char *daemon, char *name, char *addr, char *user);
71 int hosts_ctl(char *daemon, char *name, char *addr, char *user)
77 #define legal_port(a,p) \
78 (ntohs((a)->sin_port) < IPPORT_RESERVED || (p) >= IPPORT_RESERVED)
80 #define log_bad_port(addr, proc, prog) \
81 logit(deny_severity, addr, proc, prog, ": request from unprivileged port")
83 #define log_bad_host(addr, proc, prog) \
84 logit(deny_severity, addr, proc, prog, ": request from unauthorized host")
86 #define log_bad_owner(addr, proc, prog) \
87 logit(deny_severity, addr, proc, prog, ": request from non-local host")
89 #define log_no_forward(addr, proc, prog) \
90 logit(deny_severity, addr, proc, prog, ": request not forwarded")
92 #define log_client(addr, proc, prog) \
93 logit(allow_severity, addr, proc, prog, "")
98 typedef struct _haccess_t {
99 TAILQ_ENTRY(_haccess_t) list;
104 #define HASH_TABLE_SIZE 1021
105 typedef struct _hash_head {
106 TAILQ_HEAD(host_list, _haccess_t) h_head;
108 hash_head haccess_tbl[HASH_TABLE_SIZE];
109 static haccess_t *haccess_lookup(struct sockaddr_in *addr, u_long, u_long);
110 static void haccess_add(struct sockaddr_in *addr, u_long, u_long, int);
112 inline unsigned int strtoint(char *str)
115 int len = strlen(str);
118 for (i=0; i < len; i++)
123 inline int hashint(unsigned int num)
125 return num % HASH_TABLE_SIZE;
127 #define HASH(_addr, _proc, _prog) \
128 hashint((strtoint((_addr))+(_proc)+(_prog)))
130 void haccess_add(struct sockaddr_in *addr, u_long proc,
131 u_long prog, int access)
137 hptr = (haccess_t *)malloc(sizeof(haccess_t));
141 hash = HASH(inet_ntoa(addr->sin_addr), proc, prog);
142 head = &(haccess_tbl[hash]);
144 hptr->access = access;
145 hptr->addr.s_addr = addr->sin_addr.s_addr;
147 if (TAILQ_EMPTY(&head->h_head))
148 TAILQ_INSERT_HEAD(&head->h_head, hptr, list);
150 TAILQ_INSERT_TAIL(&head->h_head, hptr, list);
152 haccess_t *haccess_lookup(struct sockaddr_in *addr, u_long proc, u_long prog)
158 hash = HASH(inet_ntoa(addr->sin_addr), proc, prog);
159 head = &(haccess_tbl[hash]);
161 TAILQ_FOREACH(hptr, &head->h_head, list) {
162 if (hptr->addr.s_addr == addr->sin_addr.s_addr)
169 good_client(daemon, addr)
171 struct sockaddr_in *addr;
177 /* First check the address. */
178 if (hosts_ctl(daemon, "", inet_ntoa(addr->sin_addr), "") == DENY)
181 /* Now do the hostname lookup */
182 hp = gethostbyaddr ((const char *) &(addr->sin_addr),
183 sizeof (addr->sin_addr), AF_INET);
185 return DENY; /* never heard of it. misconfigured DNS? */
187 /* Make sure the hostent is authorative. */
188 tmpname = strdup(hp->h_name);
191 hp = gethostbyname(tmpname);
194 return DENY; /* never heard of it. misconfigured DNS? */
196 /* Now make sure the address is on the list */
197 for (sp = hp->h_addr_list ; *sp ; sp++) {
198 if (memcmp(*sp, &(addr->sin_addr), hp->h_length) == 0)
202 return DENY; /* it was a FAKE. */
204 /* Check the official name and address. */
205 if (hosts_ctl(daemon, hp->h_name, inet_ntoa(addr->sin_addr), "") == DENY)
208 /* Now check aliases. */
209 for (sp = hp->h_aliases; *sp ; sp++) {
210 if (hosts_ctl(daemon, *sp, inet_ntoa(addr->sin_addr), "") == DENY)
217 /* check_startup - additional startup code */
219 void check_startup(void)
223 * Give up root privileges so that we can never allocate a privileged
224 * port when forwarding an rpc request.
226 * Fix 8/3/00 Philipp Knirsch: First lookup our rpc user. If we find it,
227 * switch to that uid, otherwise simply resue the old bin user and print
228 * out a warning in syslog.
231 struct passwd *pwent;
233 pwent = getpwnam("rpc");
235 syslog(LOG_WARNING, "user rpc not found, reverting to user bin");
236 if (setuid(1) == -1) {
237 syslog(LOG_ERR, "setuid(1) failed: %m");
242 if (setuid(pwent->pw_uid) == -1) {
243 syslog(LOG_WARNING, "setuid() to rpc user failed: %m");
244 if (setuid(1) == -1) {
245 syslog(LOG_ERR, "setuid(1) failed: %m");
251 (void) signal(SIGINT, toggle_verboselog);
254 /* check_files - check to see if either access files have changed */
256 static int check_files()
258 static time_t allow_mtime, deny_mtime;
259 struct stat astat, dstat;
262 if (stat("/etc/hosts.allow", &astat) < 0)
264 if (stat("/etc/hosts.deny", &dstat) < 0)
267 if(!astat.st_mtime || !dstat.st_mtime)
270 if (astat.st_mtime != allow_mtime)
272 else if (dstat.st_mtime != deny_mtime)
275 allow_mtime = astat.st_mtime;
276 deny_mtime = dstat.st_mtime;
281 /* check_default - additional checks for NULL, DUMP, GETPORT and unknown */
284 check_default(daemon, addr, proc, prog)
286 struct sockaddr_in *addr;
290 haccess_t *acc = NULL;
291 int changed = check_files();
293 acc = haccess_lookup(addr, proc, prog);
294 if (acc && changed == 0)
295 return (acc->access);
297 if (!(from_local(addr) || good_client(daemon, addr))) {
298 log_bad_host(addr, proc, prog);
302 haccess_add(addr, proc, prog, FALSE);
306 log_client(addr, proc, prog);
311 haccess_add(addr, proc, prog, TRUE);
315 /* check_privileged_port - additional checks for privileged-port updates */
317 check_privileged_port(struct sockaddr_in *addr,
318 u_long proc, u_long prog, u_long port)
321 if (!legal_port(addr, port)) {
322 log_bad_port(addr, proc, prog);
329 /* toggle_verboselog - toggle verbose logging flag */
331 static void toggle_verboselog(int sig)
333 (void) signal(sig, toggle_verboselog);
334 verboselog = !verboselog;
337 /* logit - report events of interest via the syslog daemon */
339 static void logit(int severity, struct sockaddr_in *addr,
340 u_long procnum, u_long prognum, char *text)
343 char procbuf[16 + 4 * sizeof(u_long)];
345 char progbuf[16 + 4 * sizeof(u_long)];
349 * Fork off a process or the portmap daemon might hang while
350 * getrpcbynumber() or syslog() does its thing.
352 * Don't forget to wait for the children, too...
357 /* Try to map program number to name. */
361 } else if ((rpc = getrpcbynumber((int) prognum))) {
362 progname = rpc->r_name;
364 snprintf(progname = progbuf, sizeof (progbuf),
365 "prog (%lu)", prognum);
368 /* Try to map procedure number to name. */
370 snprintf(procname = procbuf, sizeof (procbuf),
371 "proc (%lu)", (u_long) procnum);
373 /* Write syslog record. */
375 syslog(severity, "connect from %s to %s in %s%s",
376 inet_ntoa(addr->sin_addr), procname, progname, text);