2 * Copyright (c) 2003-2004 Networks Associates Technology, Inc.
3 * Copyright (c) 2006 SPARTA, Inc.
6 * This software was developed for the FreeBSD Project by Network
7 * Associates Laboratories, the Security Research Division of Network
8 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
9 * as part of the DARPA CHATS research program.
11 * This software was enhanced by SPARTA ISSO under SPAWAR contract
12 * N66001-04-C-6019 ("SEFOS").
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * Developed by the TrustedBSD Project.
41 * Administratively limit access to local UDP/TCP ports for binding purposes.
42 * Intended to be combined with net.inet.ip.portrange.reservedhigh to allow
43 * specific uids and gids to bind specific ports for specific purposes,
44 * while not opening the door to any user replacing an "official" service
45 * while you're restarting it. This only affects ports explicitly bound by
46 * the user process (either for listen/outgoing socket for TCP, or send/
47 * receive for UDP). This module will not limit ports bound implicitly for
48 * out-going connections where the process hasn't explicitly selected a port:
49 * these are automatically selected by the IP stack.
51 * To use this module, security.mac.enforce_socket must be enabled, and you
52 * will probably want to twiddle the net.inet sysctl listed above. Then use
53 * sysctl(8) to modify the rules string:
55 * # sysctl security.mac.portacl.rules="uid:425:tcp:80,uid:425:tcp:79"
57 * This ruleset, for example, permits uid 425 to bind TCP ports 80 (http) and
58 * 79 (finger). User names and group names can't be used directly because
59 * the kernel only knows about uids and gids.
62 #include <sys/param.h>
63 #include <sys/domain.h>
64 #include <sys/kernel.h>
66 #include <sys/malloc.h>
67 #include <sys/module.h>
68 #include <sys/mutex.h>
71 #include <sys/protosw.h>
72 #include <sys/queue.h>
73 #include <sys/systm.h>
75 #include <sys/socket.h>
76 #include <sys/socketvar.h>
77 #include <sys/sysctl.h>
79 #include <netinet/in.h>
80 #include <netinet/in_pcb.h>
82 #include <security/mac/mac_policy.h>
84 SYSCTL_DECL(_security_mac);
86 SYSCTL_NODE(_security_mac, OID_AUTO, portacl, CTLFLAG_RW, 0,
87 "TrustedBSD mac_portacl policy controls");
89 static int portacl_enabled = 1;
90 SYSCTL_INT(_security_mac_portacl, OID_AUTO, enabled, CTLFLAG_RW,
91 &portacl_enabled, 0, "Enforce portacl policy");
92 TUNABLE_INT("security.mac.portacl.enabled", &portacl_enabled);
94 static int portacl_suser_exempt = 1;
95 SYSCTL_INT(_security_mac_portacl, OID_AUTO, suser_exempt, CTLFLAG_RW,
96 &portacl_suser_exempt, 0, "Privilege permits binding of any port");
97 TUNABLE_INT("security.mac.portacl.suser_exempt",
98 &portacl_suser_exempt);
100 static int portacl_autoport_exempt = 1;
101 SYSCTL_INT(_security_mac_portacl, OID_AUTO, autoport_exempt, CTLFLAG_RW,
102 &portacl_autoport_exempt, 0, "Allow automatic allocation through "
103 "binding port 0 if not IP_PORTRANGELOW");
104 TUNABLE_INT("security.mac.portacl.autoport_exempt",
105 &portacl_autoport_exempt);
107 static int portacl_port_high = 1023;
108 SYSCTL_INT(_security_mac_portacl, OID_AUTO, port_high, CTLFLAG_RW,
109 &portacl_port_high, 0, "Highest port to enforce for");
110 TUNABLE_INT("security.mac.portacl.port_high", &portacl_port_high);
112 MALLOC_DEFINE(M_PORTACL, "portacl_rule", "Rules for mac_portacl");
114 #define MAC_RULE_STRING_LEN 1024
118 #define RULE_PROTO_TCP 1
119 #define RULE_PROTO_UDP 2
126 TAILQ_ENTRY(rule) r_entries;
129 #define GID_STRING "gid"
130 #define TCP_STRING "tcp"
131 #define UID_STRING "uid"
132 #define UDP_STRING "udp"
135 * Text format for the rule string is that a rule consists of a
136 * comma-separated list of elements. Each element is in the form
137 * idtype:id:protocol:portnumber, and constitutes granting of permission
138 * for the specified binding.
141 static struct mtx rule_mtx;
142 static TAILQ_HEAD(rulehead, rule) rule_head;
143 static char rule_string[MAC_RULE_STRING_LEN];
146 toast_rules(struct rulehead *head)
150 while ((rule = TAILQ_FIRST(head)) != NULL) {
151 TAILQ_REMOVE(head, rule, r_entries);
152 free(rule, M_PORTACL);
157 * Note that there is an inherent race condition in the unload of modules
158 * and access via sysctl.
161 destroy(struct mac_policy_conf *mpc)
164 mtx_destroy(&rule_mtx);
165 toast_rules(&rule_head);
169 init(struct mac_policy_conf *mpc)
172 mtx_init(&rule_mtx, "rule_mtx", NULL, MTX_DEF);
173 TAILQ_INIT(&rule_head);
177 * Note: parsing routines are destructive on the passed string.
180 parse_rule_element(char *element, struct rule **rule)
182 char *idtype, *id, *protocol, *portnumber, *p;
187 new = malloc(sizeof(*new), M_PORTACL, M_ZERO | M_WAITOK);
189 idtype = strsep(&element, ":");
190 if (idtype == NULL) {
194 id = strsep(&element, ":");
199 new->r_id = strtol(id, &p, 10);
204 if (strcmp(idtype, UID_STRING) == 0)
205 new->r_idtype = RULE_UID;
206 else if (strcmp(idtype, GID_STRING) == 0)
207 new->r_idtype = RULE_GID;
212 protocol = strsep(&element, ":");
213 if (protocol == NULL) {
217 if (strcmp(protocol, TCP_STRING) == 0)
218 new->r_protocol = RULE_PROTO_TCP;
219 else if (strcmp(protocol, UDP_STRING) == 0)
220 new->r_protocol = RULE_PROTO_UDP;
225 portnumber = element;
226 if (portnumber == NULL) {
230 new->r_port = strtol(portnumber, &p, 10);
238 free(new, M_PORTACL);
246 parse_rules(char *string, struct rulehead *head)
253 while ((element = strsep(&string, ",")) != NULL) {
254 if (strlen(element) == 0)
256 error = parse_rule_element(element, &new);
259 TAILQ_INSERT_TAIL(head, new, r_entries);
268 * rule_printf() and rules_to_string() are unused currently because they rely
269 * on sbufs with auto-extension, which may sleep while holding a mutex.
270 * Instead, the non-canonical user-generated rule string is returned to the
271 * user when the rules are queried, which is faster anyway.
275 rule_printf(struct sbuf *sb, struct rule *rule)
277 const char *idtype, *protocol;
279 switch(rule->r_idtype) {
287 panic("rule_printf: unknown idtype (%d)\n", rule->r_idtype);
290 switch (rule->r_protocol) {
292 protocol = TCP_STRING;
295 protocol = UDP_STRING;
298 panic("rule_printf: unknown protocol (%d)\n",
301 sbuf_printf(sb, "%s:%jd:%s:%d", idtype, (intmax_t)rule->r_id,
302 protocol, rule->r_port);
306 rules_to_string(void)
313 sb = sbuf_new_auto();
316 for (rule = TAILQ_FIRST(&rule_head); rule != NULL;
317 rule = TAILQ_NEXT(rule, r_entries)) {
321 sbuf_printf(sb, ",");
322 rule_printf(sb, rule);
324 mtx_unlock(&rule_mtx);
326 temp = strdup(sbuf_data(sb), M_PORTACL);
333 * Note: due to races, there is not a single serializable order
334 * between parallel calls to the sysctl.
337 sysctl_rules(SYSCTL_HANDLER_ARGS)
339 char *string, *copy_string, *new_string;
340 struct rulehead head, save_head;
344 if (req->newptr != NULL) {
345 new_string = malloc(MAC_RULE_STRING_LEN, M_PORTACL,
348 strcpy(new_string, rule_string);
349 mtx_unlock(&rule_mtx);
352 string = rule_string;
354 error = sysctl_handle_string(oidp, string, MAC_RULE_STRING_LEN, req);
358 if (req->newptr != NULL) {
359 copy_string = strdup(string, M_PORTACL);
361 error = parse_rules(copy_string, &head);
362 free(copy_string, M_PORTACL);
366 TAILQ_INIT(&save_head);
368 TAILQ_CONCAT(&save_head, &rule_head, r_entries);
369 TAILQ_CONCAT(&rule_head, &head, r_entries);
370 strcpy(rule_string, string);
371 mtx_unlock(&rule_mtx);
372 toast_rules(&save_head);
375 if (new_string != NULL)
376 free(new_string, M_PORTACL);
380 SYSCTL_PROC(_security_mac_portacl, OID_AUTO, rules,
381 CTLTYPE_STRING|CTLFLAG_RW, 0, 0, sysctl_rules, "A", "Rules");
384 rules_check(struct ucred *cred, int family, int type, u_int16_t port)
390 printf("Check requested for euid %d, family %d, type %d, port %d\n",
391 cred->cr_uid, family, type, port);
394 if (port > portacl_port_high)
399 for (rule = TAILQ_FIRST(&rule_head);
401 rule = TAILQ_NEXT(rule, r_entries)) {
402 if (type == SOCK_DGRAM && rule->r_protocol != RULE_PROTO_UDP)
404 if (type == SOCK_STREAM && rule->r_protocol != RULE_PROTO_TCP)
406 if (port != rule->r_port)
408 if (rule->r_idtype == RULE_UID) {
409 if (cred->cr_uid == rule->r_id) {
413 } else if (rule->r_idtype == RULE_GID) {
414 if (cred->cr_gid == rule->r_id) {
417 } else if (groupmember(rule->r_id, cred)) {
422 panic("rules_check: unknown rule type %d",
425 mtx_unlock(&rule_mtx);
427 if (error != 0 && portacl_suser_exempt != 0)
428 error = priv_check_cred(cred, PRIV_NETINET_RESERVEDPORT, 0);
434 * Note, this only limits the ability to explicitly bind a port, it
435 * doesn't limit implicitly bound ports for outgoing connections where
436 * the source port is left up to the IP stack to determine automatically.
439 socket_check_bind(struct ucred *cred, struct socket *so,
440 struct label *solabel, struct sockaddr *sa)
442 struct sockaddr_in *sin;
447 /* Only run if we are enabled. */
448 if (portacl_enabled == 0)
451 /* Only interested in IPv4 and IPv6 sockets. */
452 if (so->so_proto->pr_domain->dom_family != PF_INET &&
453 so->so_proto->pr_domain->dom_family != PF_INET6)
456 /* Currently, we don't attempt to deal with SOCK_RAW, etc. */
457 if (so->so_type != SOCK_DGRAM &&
458 so->so_type != SOCK_STREAM)
461 /* Reject addresses we don't understand; fail closed. */
462 if (sa->sa_family != AF_INET && sa->sa_family != AF_INET6)
465 family = so->so_proto->pr_domain->dom_family;
467 sin = (struct sockaddr_in *) sa;
468 port = ntohs(sin->sin_port);
471 * Sockets are frequently bound with a specific IP address but a port
472 * number of '0' to request automatic port allocation. This is often
473 * desirable as long as IP_PORTRANGELOW isn't set, which might permit
474 * automatic allocation of a "privileged" port. The autoport exempt
475 * flag exempts port 0 allocation from rule checking as long as a low
476 * port isn't required.
478 if (portacl_autoport_exempt && port == 0) {
480 if ((inp->inp_flags & INP_LOWPORT) == 0)
484 return (rules_check(cred, family, type, port));
487 static struct mac_policy_ops portacl_ops =
489 .mpo_destroy = destroy,
491 .mpo_socket_check_bind = socket_check_bind,
494 MAC_POLICY_SET(&portacl_ops, mac_portacl, "TrustedBSD MAC/portacl",
495 MPC_LOADTIME_FLAG_UNLOADOK, NULL);