--- /dev/null
+/*-
+ * Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD: head/sys/netinet/ipfw/ip_fw_dynamic.c 200601 2009-12-16 10:48:40Z luigi $");
+
+#define DEB(x)
+#define DDB(x) x
+
+/*
+ * Dynamic rule support for ipfw
+ */
+
+#if !defined(KLD_MODULE)
+#include "opt_ipfw.h"
+#include "opt_ipdivert.h"
+#include "opt_ipdn.h"
+#include "opt_inet.h"
+#ifndef INET
+#error IPFIREWALL requires INET.
+#endif /* INET */
+#endif
+#include "opt_inet6.h"
+#include "opt_ipsec.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+#include <sys/syslog.h>
+#include <net/ethernet.h> /* for ETHERTYPE_IP */
+#include <net/if.h>
+#include <net/vnet.h>
+
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip_var.h> /* ip_defttl */
+#include <netinet/ip_fw.h>
+#include <netinet/ipfw/ip_fw_private.h>
+#include <netinet/tcp_var.h>
+#include <netinet/udp.h>
+
+#include <netinet/ip6.h> /* IN6_ARE_ADDR_EQUAL */
+#ifdef INET6
+#include <netinet6/in6_var.h>
+#include <netinet6/ip6_var.h>
+#endif
+
+#include <machine/in_cksum.h> /* XXX for in_cksum */
+
+#ifdef MAC
+#include <security/mac/mac_framework.h>
+#endif
+
+/*
+ * Description of dynamic rules.
+ *
+ * Dynamic rules are stored in lists accessed through a hash table
+ * (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
+ * be modified through the sysctl variable dyn_buckets which is
+ * updated when the table becomes empty.
+ *
+ * XXX currently there is only one list, ipfw_dyn.
+ *
+ * When a packet is received, its address fields are first masked
+ * with the mask defined for the rule, then hashed, then matched
+ * against the entries in the corresponding list.
+ * Dynamic rules can be used for different purposes:
+ * + stateful rules;
+ * + enforcing limits on the number of sessions;
+ * + in-kernel NAT (not implemented yet)
+ *
+ * The lifetime of dynamic rules is regulated by dyn_*_lifetime,
+ * measured in seconds and depending on the flags.
+ *
+ * The total number of dynamic rules is stored in dyn_count.
+ * The max number of dynamic rules is dyn_max. When we reach
+ * the maximum number of rules we do not create anymore. This is
+ * done to avoid consuming too much memory, but also too much
+ * time when searching on each packet (ideally, we should try instead
+ * to put a limit on the length of the list on each bucket...).
+ *
+ * Each dynamic rule holds a pointer to the parent ipfw rule so
+ * we know what action to perform. Dynamic rules are removed when
+ * the parent rule is deleted. XXX we should make them survive.
+ *
+ * There are some limitations with dynamic rules -- we do not
+ * obey the 'randomized match', and we do not do multiple
+ * passes through the firewall. XXX check the latter!!!
+ */
+
+/*
+ * Static variables followed by global ones
+ */
+static VNET_DEFINE(ipfw_dyn_rule **, ipfw_dyn_v);
+static VNET_DEFINE(u_int32_t, dyn_buckets);
+static VNET_DEFINE(u_int32_t, curr_dyn_buckets);
+static VNET_DEFINE(struct callout, ipfw_timeout);
+#define V_ipfw_dyn_v VNET(ipfw_dyn_v)
+#define V_dyn_buckets VNET(dyn_buckets)
+#define V_curr_dyn_buckets VNET(curr_dyn_buckets)
+#define V_ipfw_timeout VNET(ipfw_timeout)
+
+static uma_zone_t ipfw_dyn_rule_zone;
+#if defined( __linux__ ) || defined( _WIN32 )
+DEFINE_SPINLOCK(ipfw_dyn_mtx);
+#else
+static struct mtx ipfw_dyn_mtx; /* mutex guarding dynamic rules */
+#endif
+
+#define IPFW_DYN_LOCK_INIT() \
+ mtx_init(&ipfw_dyn_mtx, "IPFW dynamic rules", NULL, MTX_DEF)
+#define IPFW_DYN_LOCK_DESTROY() mtx_destroy(&ipfw_dyn_mtx)
+#define IPFW_DYN_LOCK() mtx_lock(&ipfw_dyn_mtx)
+#define IPFW_DYN_UNLOCK() mtx_unlock(&ipfw_dyn_mtx)
+#define IPFW_DYN_LOCK_ASSERT() mtx_assert(&ipfw_dyn_mtx, MA_OWNED)
+
+void
+ipfw_dyn_unlock(void)
+{
+ IPFW_DYN_UNLOCK();
+}
+
+/*
+ * Timeouts for various events in handing dynamic rules.
+ */
+static VNET_DEFINE(u_int32_t, dyn_ack_lifetime);
+static VNET_DEFINE(u_int32_t, dyn_syn_lifetime);
+static VNET_DEFINE(u_int32_t, dyn_fin_lifetime);
+static VNET_DEFINE(u_int32_t, dyn_rst_lifetime);
+static VNET_DEFINE(u_int32_t, dyn_udp_lifetime);
+static VNET_DEFINE(u_int32_t, dyn_short_lifetime);
+
+#define V_dyn_ack_lifetime VNET(dyn_ack_lifetime)
+#define V_dyn_syn_lifetime VNET(dyn_syn_lifetime)
+#define V_dyn_fin_lifetime VNET(dyn_fin_lifetime)
+#define V_dyn_rst_lifetime VNET(dyn_rst_lifetime)
+#define V_dyn_udp_lifetime VNET(dyn_udp_lifetime)
+#define V_dyn_short_lifetime VNET(dyn_short_lifetime)
+
+/*
+ * Keepalives are sent if dyn_keepalive is set. They are sent every
+ * dyn_keepalive_period seconds, in the last dyn_keepalive_interval
+ * seconds of lifetime of a rule.
+ * dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
+ * than dyn_keepalive_period.
+ */
+
+static VNET_DEFINE(u_int32_t, dyn_keepalive_interval);
+static VNET_DEFINE(u_int32_t, dyn_keepalive_period);
+static VNET_DEFINE(u_int32_t, dyn_keepalive);
+
+#define V_dyn_keepalive_interval VNET(dyn_keepalive_interval)
+#define V_dyn_keepalive_period VNET(dyn_keepalive_period)
+#define V_dyn_keepalive VNET(dyn_keepalive)
+
+static VNET_DEFINE(u_int32_t, dyn_count); /* # of dynamic rules */
+static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */
+
+#define V_dyn_count VNET(dyn_count)
+#define V_dyn_max VNET(dyn_max)
+
+#ifdef SYSCTL_NODE
+SYSCTL_DECL(_net_inet_ip_fw);
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets,
+ CTLFLAG_RW, &VNET_NAME(dyn_buckets), 0,
+ "Number of dyn. buckets");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets,
+ CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0,
+ "Current Number of dyn. buckets");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_count,
+ CTLFLAG_RD, &VNET_NAME(dyn_count), 0,
+ "Number of dyn. rules");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_max,
+ CTLFLAG_RW, &VNET_NAME(dyn_max), 0,
+ "Max number of dyn. rules");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime,
+ CTLFLAG_RW, &VNET_NAME(dyn_ack_lifetime), 0,
+ "Lifetime of dyn. rules for acks");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime,
+ CTLFLAG_RW, &VNET_NAME(dyn_syn_lifetime), 0,
+ "Lifetime of dyn. rules for syn");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime,
+ CTLFLAG_RW, &VNET_NAME(dyn_fin_lifetime), 0,
+ "Lifetime of dyn. rules for fin");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime,
+ CTLFLAG_RW, &VNET_NAME(dyn_rst_lifetime), 0,
+ "Lifetime of dyn. rules for rst");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime,
+ CTLFLAG_RW, &VNET_NAME(dyn_udp_lifetime), 0,
+ "Lifetime of dyn. rules for UDP");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime,
+ CTLFLAG_RW, &VNET_NAME(dyn_short_lifetime), 0,
+ "Lifetime of dyn. rules for other situations");
+SYSCTL_VNET_INT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive,
+ CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0,
+ "Enable keepalives for dyn. rules");
+#endif /* SYSCTL_NODE */
+
+
+static __inline int
+hash_packet6(struct ipfw_flow_id *id)
+{
+ u_int32_t i;
+ i = (id->dst_ip6.__u6_addr.__u6_addr32[2]) ^
+ (id->dst_ip6.__u6_addr.__u6_addr32[3]) ^
+ (id->src_ip6.__u6_addr.__u6_addr32[2]) ^
+ (id->src_ip6.__u6_addr.__u6_addr32[3]) ^
+ (id->dst_port) ^ (id->src_port);
+ return i;
+}
+
+/*
+ * IMPORTANT: the hash function for dynamic rules must be commutative
+ * in source and destination (ip,port), because rules are bidirectional
+ * and we want to find both in the same bucket.
+ */
+static __inline int
+hash_packet(struct ipfw_flow_id *id)
+{
+ u_int32_t i;
+
+#ifdef INET6
+ if (IS_IP6_FLOW_ID(id))
+ i = hash_packet6(id);
+ else
+#endif /* INET6 */
+ i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
+ i &= (V_curr_dyn_buckets - 1);
+ return i;
+}
+
+static __inline void
+unlink_dyn_rule_print(struct ipfw_flow_id *id)
+{
+ struct in_addr da;
+#ifdef INET6
+ char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
+#else
+ char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
+#endif
+
+#ifdef INET6
+ if (IS_IP6_FLOW_ID(id)) {
+ ip6_sprintf(src, &id->src_ip6);
+ ip6_sprintf(dst, &id->dst_ip6);
+ } else
+#endif
+ {
+ da.s_addr = htonl(id->src_ip);
+ inet_ntoa_r(da, src);
+ da.s_addr = htonl(id->dst_ip);
+ inet_ntoa_r(da, dst);
+ }
+ printf("ipfw: unlink entry %s %d -> %s %d, %d left\n",
+ src, id->src_port, dst, id->dst_port, V_dyn_count - 1);
+}
+
+/**
+ * unlink a dynamic rule from a chain. prev is a pointer to
+ * the previous one, q is a pointer to the rule to delete,
+ * head is a pointer to the head of the queue.
+ * Modifies q and potentially also head.
+ */
+#define UNLINK_DYN_RULE(prev, head, q) { \
+ ipfw_dyn_rule *old_q = q; \
+ \
+ /* remove a refcount to the parent */ \
+ if (q->dyn_type == O_LIMIT) \
+ q->parent->count--; \
+ DEB(unlink_dyn_rule_print(&q->id);) \
+ if (prev != NULL) \
+ prev->next = q = q->next; \
+ else \
+ head = q = q->next; \
+ V_dyn_count--; \
+ uma_zfree(ipfw_dyn_rule_zone, old_q); }
+
+#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
+
+/**
+ * Remove dynamic rules pointing to "rule", or all of them if rule == NULL.
+ *
+ * If keep_me == NULL, rules are deleted even if not expired,
+ * otherwise only expired rules are removed.
+ *
+ * The value of the second parameter is also used to point to identify
+ * a rule we absolutely do not want to remove (e.g. because we are
+ * holding a reference to it -- this is the case with O_LIMIT_PARENT
+ * rules). The pointer is only used for comparison, so any non-null
+ * value will do.
+ */
+static void
+remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me)
+{
+ static u_int32_t last_remove = 0;
+
+#define FORCE (keep_me == NULL)
+
+ ipfw_dyn_rule *prev, *q;
+ int i, pass = 0, max_pass = 0;
+
+ IPFW_DYN_LOCK_ASSERT();
+
+ if (V_ipfw_dyn_v == NULL || V_dyn_count == 0)
+ return;
+ /* do not expire more than once per second, it is useless */
+ if (!FORCE && last_remove == time_uptime)
+ return;
+ last_remove = time_uptime;
+
+ /*
+ * because O_LIMIT refer to parent rules, during the first pass only
+ * remove child and mark any pending LIMIT_PARENT, and remove
+ * them in a second pass.
+ */
+next_pass:
+ for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
+ for (prev=NULL, q = V_ipfw_dyn_v[i] ; q ; ) {
+ /*
+ * Logic can become complex here, so we split tests.
+ */
+ if (q == keep_me)
+ goto next;
+ if (rule != NULL && rule != q->rule)
+ goto next; /* not the one we are looking for */
+ if (q->dyn_type == O_LIMIT_PARENT) {
+ /*
+ * handle parent in the second pass,
+ * record we need one.
+ */
+ max_pass = 1;
+ if (pass == 0)
+ goto next;
+ if (FORCE && q->count != 0 ) {
+ /* XXX should not happen! */
+ printf("ipfw: OUCH! cannot remove rule,"
+ " count %d\n", q->count);
+ }
+ } else {
+ if (!FORCE &&
+ !TIME_LEQ( q->expire, time_uptime ))
+ goto next;
+ }
+ if (q->dyn_type != O_LIMIT_PARENT || !q->count) {
+ UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q);
+ continue;
+ }
+next:
+ prev=q;
+ q=q->next;
+ }
+ }
+ if (pass++ < max_pass)
+ goto next_pass;
+}
+
+void
+ipfw_remove_dyn_children(struct ip_fw *rule)
+{
+ IPFW_DYN_LOCK();
+ remove_dyn_rule(rule, NULL /* force removal */);
+ IPFW_DYN_UNLOCK();
+}
+
+/**
+ * lookup a dynamic rule, locked version
+ */
+static ipfw_dyn_rule *
+lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int *match_direction,
+ struct tcphdr *tcp)
+{
+ /*
+ * stateful ipfw extensions.
+ * Lookup into dynamic session queue
+ */
+#define MATCH_REVERSE 0
+#define MATCH_FORWARD 1
+#define MATCH_NONE 2
+#define MATCH_UNKNOWN 3
+ int i, dir = MATCH_NONE;
+ ipfw_dyn_rule *prev, *q=NULL;
+
+ IPFW_DYN_LOCK_ASSERT();
+
+ if (V_ipfw_dyn_v == NULL)
+ goto done; /* not found */
+ i = hash_packet( pkt );
+ for (prev=NULL, q = V_ipfw_dyn_v[i] ; q != NULL ; ) {
+ if (q->dyn_type == O_LIMIT_PARENT && q->count)
+ goto next;
+ if (TIME_LEQ( q->expire, time_uptime)) { /* expire entry */
+ UNLINK_DYN_RULE(prev, V_ipfw_dyn_v[i], q);
+ continue;
+ }
+ if (pkt->proto == q->id.proto &&
+ q->dyn_type != O_LIMIT_PARENT) {
+ if (IS_IP6_FLOW_ID(pkt)) {
+ if (IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
+ &(q->id.src_ip6)) &&
+ IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
+ &(q->id.dst_ip6)) &&
+ pkt->src_port == q->id.src_port &&
+ pkt->dst_port == q->id.dst_port ) {
+ dir = MATCH_FORWARD;
+ break;
+ }
+ if (IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
+ &(q->id.dst_ip6)) &&
+ IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
+ &(q->id.src_ip6)) &&
+ pkt->src_port == q->id.dst_port &&
+ pkt->dst_port == q->id.src_port ) {
+ dir = MATCH_REVERSE;
+ break;
+ }
+ } else {
+ if (pkt->src_ip == q->id.src_ip &&
+ pkt->dst_ip == q->id.dst_ip &&
+ pkt->src_port == q->id.src_port &&
+ pkt->dst_port == q->id.dst_port ) {
+ dir = MATCH_FORWARD;
+ break;
+ }
+ if (pkt->src_ip == q->id.dst_ip &&
+ pkt->dst_ip == q->id.src_ip &&
+ pkt->src_port == q->id.dst_port &&
+ pkt->dst_port == q->id.src_port ) {
+ dir = MATCH_REVERSE;
+ break;
+ }
+ }
+ }
+next:
+ prev = q;
+ q = q->next;
+ }
+ if (q == NULL)
+ goto done; /* q = NULL, not found */
+
+ if ( prev != NULL) { /* found and not in front */
+ prev->next = q->next;
+ q->next = V_ipfw_dyn_v[i];
+ V_ipfw_dyn_v[i] = q;
+ }
+ if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */
+ u_char flags = pkt->flags & (TH_FIN|TH_SYN|TH_RST);
+
+#define BOTH_SYN (TH_SYN | (TH_SYN << 8))
+#define BOTH_FIN (TH_FIN | (TH_FIN << 8))
+ q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8);
+ switch (q->state) {
+ case TH_SYN: /* opening */
+ q->expire = time_uptime + V_dyn_syn_lifetime;
+ break;
+
+ case BOTH_SYN: /* move to established */
+ case BOTH_SYN | TH_FIN : /* one side tries to close */
+ case BOTH_SYN | (TH_FIN << 8) :
+ if (tcp) {
+#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
+ u_int32_t ack = ntohl(tcp->th_ack);
+ if (dir == MATCH_FORWARD) {
+ if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd))
+ q->ack_fwd = ack;
+ else { /* ignore out-of-sequence */
+ break;
+ }
+ } else {
+ if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev))
+ q->ack_rev = ack;
+ else { /* ignore out-of-sequence */
+ break;
+ }
+ }
+ }
+ q->expire = time_uptime + V_dyn_ack_lifetime;
+ break;
+
+ case BOTH_SYN | BOTH_FIN: /* both sides closed */
+ if (V_dyn_fin_lifetime >= V_dyn_keepalive_period)
+ V_dyn_fin_lifetime = V_dyn_keepalive_period - 1;
+ q->expire = time_uptime + V_dyn_fin_lifetime;
+ break;
+
+ default:
+#if 0
+ /*
+ * reset or some invalid combination, but can also
+ * occur if we use keep-state the wrong way.
+ */
+ if ( (q->state & ((TH_RST << 8)|TH_RST)) == 0)
+ printf("invalid state: 0x%x\n", q->state);
+#endif
+ if (V_dyn_rst_lifetime >= V_dyn_keepalive_period)
+ V_dyn_rst_lifetime = V_dyn_keepalive_period - 1;
+ q->expire = time_uptime + V_dyn_rst_lifetime;
+ break;
+ }
+ } else if (pkt->proto == IPPROTO_UDP) {
+ q->expire = time_uptime + V_dyn_udp_lifetime;
+ } else {
+ /* other protocols */
+ q->expire = time_uptime + V_dyn_short_lifetime;
+ }
+done:
+ if (match_direction)
+ *match_direction = dir;
+ return q;
+}
+
+ipfw_dyn_rule *
+ipfw_lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
+ struct tcphdr *tcp)
+{
+ ipfw_dyn_rule *q;
+
+ IPFW_DYN_LOCK();
+ q = lookup_dyn_rule_locked(pkt, match_direction, tcp);
+ if (q == NULL)
+ IPFW_DYN_UNLOCK();
+ /* NB: return table locked when q is not NULL */
+ return q;
+}
+
+static void
+realloc_dynamic_table(void)
+{
+ IPFW_DYN_LOCK_ASSERT();
+
+ /*
+ * Try reallocation, make sure we have a power of 2 and do
+ * not allow more than 64k entries. In case of overflow,
+ * default to 1024.
+ */
+
+ if (V_dyn_buckets > 65536)
+ V_dyn_buckets = 1024;
+ if ((V_dyn_buckets & (V_dyn_buckets-1)) != 0) { /* not a power of 2 */
+ V_dyn_buckets = V_curr_dyn_buckets; /* reset */
+ return;
+ }
+ V_curr_dyn_buckets = V_dyn_buckets;
+ if (V_ipfw_dyn_v != NULL)
+ free(V_ipfw_dyn_v, M_IPFW);
+ for (;;) {
+ V_ipfw_dyn_v = malloc(V_curr_dyn_buckets * sizeof(ipfw_dyn_rule *),
+ M_IPFW, M_NOWAIT | M_ZERO);
+ if (V_ipfw_dyn_v != NULL || V_curr_dyn_buckets <= 2)
+ break;
+ V_curr_dyn_buckets /= 2;
+ }
+}
+
+/**
+ * Install state of type 'type' for a dynamic session.
+ * The hash table contains two type of rules:
+ * - regular rules (O_KEEP_STATE)
+ * - rules for sessions with limited number of sess per user
+ * (O_LIMIT). When they are created, the parent is
+ * increased by 1, and decreased on delete. In this case,
+ * the third parameter is the parent rule and not the chain.
+ * - "parent" rules for the above (O_LIMIT_PARENT).
+ */
+static ipfw_dyn_rule *
+add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule)
+{
+ ipfw_dyn_rule *r;
+ int i;
+
+ IPFW_DYN_LOCK_ASSERT();
+
+ if (V_ipfw_dyn_v == NULL ||
+ (V_dyn_count == 0 && V_dyn_buckets != V_curr_dyn_buckets)) {
+ realloc_dynamic_table();
+ if (V_ipfw_dyn_v == NULL)
+ return NULL; /* failed ! */
+ }
+ i = hash_packet(id);
+
+ r = uma_zalloc(ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO);
+ if (r == NULL) {
+ printf ("ipfw: sorry cannot allocate state\n");
+ return NULL;
+ }
+
+ /* increase refcount on parent, and set pointer */
+ if (dyn_type == O_LIMIT) {
+ ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
+ if ( parent->dyn_type != O_LIMIT_PARENT)
+ panic("invalid parent");
+ parent->count++;
+ r->parent = parent;
+ rule = parent->rule;
+ }
+
+ r->id = *id;
+ r->expire = time_uptime + V_dyn_syn_lifetime;
+ r->rule = rule;
+ r->dyn_type = dyn_type;
+ r->pcnt = r->bcnt = 0;
+ r->count = 0;
+
+ r->bucket = i;
+ r->next = V_ipfw_dyn_v[i];
+ V_ipfw_dyn_v[i] = r;
+ V_dyn_count++;
+ DEB({
+ struct in_addr da;
+#ifdef INET6
+ char src[INET6_ADDRSTRLEN];
+ char dst[INET6_ADDRSTRLEN];
+#else
+ char src[INET_ADDRSTRLEN];
+ char dst[INET_ADDRSTRLEN];
+#endif
+
+#ifdef INET6
+ if (IS_IP6_FLOW_ID(&(r->id))) {
+ ip6_sprintf(src, &r->id.src_ip6);
+ ip6_sprintf(dst, &r->id.dst_ip6);
+ } else
+#endif
+ {
+ da.s_addr = htonl(r->id.src_ip);
+ inet_ntoa_r(da, src);
+ da.s_addr = htonl(r->id.dst_ip);
+ inet_ntoa_r(da, dst);
+ }
+ printf("ipfw: add dyn entry ty %d %s %d -> %s %d, total %d\n",
+ dyn_type, src, r->id.src_port, dst, r->id.dst_port,
+ V_dyn_count);
+ })
+ return r;
+}
+
+/**
+ * lookup dynamic parent rule using pkt and rule as search keys.
+ * If the lookup fails, then install one.
+ */
+static ipfw_dyn_rule *
+lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule)
+{
+ ipfw_dyn_rule *q;
+ int i;
+
+ IPFW_DYN_LOCK_ASSERT();
+
+ if (V_ipfw_dyn_v) {
+ int is_v6 = IS_IP6_FLOW_ID(pkt);
+ i = hash_packet( pkt );
+ for (q = V_ipfw_dyn_v[i] ; q != NULL ; q=q->next)
+ if (q->dyn_type == O_LIMIT_PARENT &&
+ rule== q->rule &&
+ pkt->proto == q->id.proto &&
+ pkt->src_port == q->id.src_port &&
+ pkt->dst_port == q->id.dst_port &&
+ (
+ (is_v6 &&
+ IN6_ARE_ADDR_EQUAL(&(pkt->src_ip6),
+ &(q->id.src_ip6)) &&
+ IN6_ARE_ADDR_EQUAL(&(pkt->dst_ip6),
+ &(q->id.dst_ip6))) ||
+ (!is_v6 &&
+ pkt->src_ip == q->id.src_ip &&
+ pkt->dst_ip == q->id.dst_ip)
+ )
+ ) {
+ q->expire = time_uptime + V_dyn_short_lifetime;
+ DEB(printf("ipfw: lookup_dyn_parent found 0x%p\n",q);)
+ return q;
+ }
+ }
+ return add_dyn_rule(pkt, O_LIMIT_PARENT, rule);
+}
+
+/**
+ * Install dynamic state for rule type cmd->o.opcode
+ *
+ * Returns 1 (failure) if state is not installed because of errors or because
+ * session limitations are enforced.
+ */
+int
+ipfw_install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
+ struct ip_fw_args *args, uint32_t tablearg)
+{
+ static int last_log;
+ ipfw_dyn_rule *q;
+ struct in_addr da;
+#ifdef INET6
+ char src[INET6_ADDRSTRLEN + 2], dst[INET6_ADDRSTRLEN + 2];
+#else
+ char src[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
+#endif
+
+ src[0] = '\0';
+ dst[0] = '\0';
+
+ IPFW_DYN_LOCK();
+
+ DEB(
+#ifdef INET6
+ if (IS_IP6_FLOW_ID(&(args->f_id))) {
+ ip6_sprintf(src, &args->f_id.src_ip6);
+ ip6_sprintf(dst, &args->f_id.dst_ip6);
+ } else
+#endif
+ {
+ da.s_addr = htonl(args->f_id.src_ip);
+ inet_ntoa_r(da, src);
+ da.s_addr = htonl(args->f_id.dst_ip);
+ inet_ntoa_r(da, dst);
+ }
+ printf("ipfw: %s: type %d %s %u -> %s %u\n",
+ __func__, cmd->o.opcode, src, args->f_id.src_port,
+ dst, args->f_id.dst_port);
+ src[0] = '\0';
+ dst[0] = '\0';
+ )
+
+ q = lookup_dyn_rule_locked(&args->f_id, NULL, NULL);
+
+ if (q != NULL) { /* should never occur */
+ if (last_log != time_uptime) {
+ last_log = time_uptime;
+ printf("ipfw: %s: entry already present, done\n",
+ __func__);
+ }
+ IPFW_DYN_UNLOCK();
+ return (0);
+ }
+
+ if (V_dyn_count >= V_dyn_max)
+ /* Run out of slots, try to remove any expired rule. */
+ remove_dyn_rule(NULL, (ipfw_dyn_rule *)1);
+
+ if (V_dyn_count >= V_dyn_max) {
+ if (last_log != time_uptime) {
+ last_log = time_uptime;
+ printf("ipfw: %s: Too many dynamic rules\n", __func__);
+ }
+ IPFW_DYN_UNLOCK();
+ return (1); /* cannot install, notify caller */
+ }
+
+ switch (cmd->o.opcode) {
+ case O_KEEP_STATE: /* bidir rule */
+ add_dyn_rule(&args->f_id, O_KEEP_STATE, rule);
+ break;
+
+ case O_LIMIT: { /* limit number of sessions */
+ struct ipfw_flow_id id;
+ ipfw_dyn_rule *parent;
+ uint32_t conn_limit;
+ uint16_t limit_mask = cmd->limit_mask;
+
+ conn_limit = (cmd->conn_limit == IP_FW_TABLEARG) ?
+ tablearg : cmd->conn_limit;
+
+ DEB(
+ if (cmd->conn_limit == IP_FW_TABLEARG)
+ printf("ipfw: %s: O_LIMIT rule, conn_limit: %u "
+ "(tablearg)\n", __func__, conn_limit);
+ else
+ printf("ipfw: %s: O_LIMIT rule, conn_limit: %u\n",
+ __func__, conn_limit);
+ )
+
+ id.dst_ip = id.src_ip = id.dst_port = id.src_port = 0;
+ id.proto = args->f_id.proto;
+ id.addr_type = args->f_id.addr_type;
+ id.fib = M_GETFIB(args->m);
+
+ if (IS_IP6_FLOW_ID (&(args->f_id))) {
+ if (limit_mask & DYN_SRC_ADDR)
+ id.src_ip6 = args->f_id.src_ip6;
+ if (limit_mask & DYN_DST_ADDR)
+ id.dst_ip6 = args->f_id.dst_ip6;
+ } else {
+ if (limit_mask & DYN_SRC_ADDR)
+ id.src_ip = args->f_id.src_ip;
+ if (limit_mask & DYN_DST_ADDR)
+ id.dst_ip = args->f_id.dst_ip;
+ }
+ if (limit_mask & DYN_SRC_PORT)
+ id.src_port = args->f_id.src_port;
+ if (limit_mask & DYN_DST_PORT)
+ id.dst_port = args->f_id.dst_port;
+ if ((parent = lookup_dyn_parent(&id, rule)) == NULL) {
+ printf("ipfw: %s: add parent failed\n", __func__);
+ IPFW_DYN_UNLOCK();
+ return (1);
+ }
+
+ if (parent->count >= conn_limit) {
+ /* See if we can remove some expired rule. */
+ remove_dyn_rule(rule, parent);
+ if (parent->count >= conn_limit) {
+ if (V_fw_verbose && last_log != time_uptime) {
+ last_log = time_uptime;
+#ifdef INET6
+ /*
+ * XXX IPv6 flows are not
+ * supported yet.
+ */
+ if (IS_IP6_FLOW_ID(&(args->f_id))) {
+ char ip6buf[INET6_ADDRSTRLEN];
+ snprintf(src, sizeof(src),
+ "[%s]", ip6_sprintf(ip6buf,
+ &args->f_id.src_ip6));
+ snprintf(dst, sizeof(dst),
+ "[%s]", ip6_sprintf(ip6buf,
+ &args->f_id.dst_ip6));
+ } else
+#endif
+ {
+ da.s_addr =
+ htonl(args->f_id.src_ip);
+ inet_ntoa_r(da, src);
+ da.s_addr =
+ htonl(args->f_id.dst_ip);
+ inet_ntoa_r(da, dst);
+ }
+ log(LOG_SECURITY | LOG_DEBUG,
+ "ipfw: %d %s %s:%u -> %s:%u, %s\n",
+ parent->rule->rulenum,
+ "drop session",
+ src, (args->f_id.src_port),
+ dst, (args->f_id.dst_port),
+ "too many entries");
+ }
+ IPFW_DYN_UNLOCK();
+ return (1);
+ }
+ }
+ add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent);
+ break;
+ }
+ default:
+ printf("ipfw: %s: unknown dynamic rule type %u\n",
+ __func__, cmd->o.opcode);
+ IPFW_DYN_UNLOCK();
+ return (1);
+ }
+
+ /* XXX just set lifetime */
+ lookup_dyn_rule_locked(&args->f_id, NULL, NULL);
+
+ IPFW_DYN_UNLOCK();
+ return (0);
+}
+
+/*
+ * Generate a TCP packet, containing either a RST or a keepalive.
+ * When flags & TH_RST, we are sending a RST packet, because of a
+ * "reset" action matched the packet.
+ * Otherwise we are sending a keepalive, and flags & TH_
+ * The 'replyto' mbuf is the mbuf being replied to, if any, and is required
+ * so that MAC can label the reply appropriately.
+ */
+struct mbuf *
+ipfw_send_pkt(struct mbuf *replyto, struct ipfw_flow_id *id, u_int32_t seq,
+ u_int32_t ack, int flags)
+{
+#ifdef __linux__ // XXX to be revised
+ return NULL;
+#else
+ struct mbuf *m;
+ int len, dir;
+ struct ip *h = NULL; /* stupid compiler */
+#ifdef INET6
+ struct ip6_hdr *h6 = NULL;
+#endif
+ struct tcphdr *th = NULL;
+
+ MGETHDR(m, M_DONTWAIT, MT_DATA);
+ if (m == NULL)
+ return (NULL);
+
+ M_SETFIB(m, id->fib);
+#ifdef MAC
+ if (replyto != NULL)
+ mac_netinet_firewall_reply(replyto, m);
+ else
+ mac_netinet_firewall_send(m);
+#else
+ (void)replyto; /* don't warn about unused arg */
+#endif
+
+ switch (id->addr_type) {
+ case 4:
+ len = sizeof(struct ip) + sizeof(struct tcphdr);
+ break;
+#ifdef INET6
+ case 6:
+ len = sizeof(struct ip6_hdr) + sizeof(struct tcphdr);
+ break;
+#endif
+ default:
+ /* XXX: log me?!? */
+ FREE_PKT(m);
+ return (NULL);
+ }
+ dir = ((flags & (TH_SYN | TH_RST)) == TH_SYN);
+
+ m->m_data += max_linkhdr;
+ m->m_flags |= M_SKIP_FIREWALL;
+ m->m_pkthdr.len = m->m_len = len;
+ m->m_pkthdr.rcvif = NULL;
+ bzero(m->m_data, len);
+
+ switch (id->addr_type) {
+ case 4:
+ h = mtod(m, struct ip *);
+
+ /* prepare for checksum */
+ h->ip_p = IPPROTO_TCP;
+ h->ip_len = htons(sizeof(struct tcphdr));
+ if (dir) {
+ h->ip_src.s_addr = htonl(id->src_ip);
+ h->ip_dst.s_addr = htonl(id->dst_ip);
+ } else {
+ h->ip_src.s_addr = htonl(id->dst_ip);
+ h->ip_dst.s_addr = htonl(id->src_ip);
+ }
+
+ th = (struct tcphdr *)(h + 1);
+ break;
+#ifdef INET6
+ case 6:
+ h6 = mtod(m, struct ip6_hdr *);
+
+ /* prepare for checksum */
+ h6->ip6_nxt = IPPROTO_TCP;
+ h6->ip6_plen = htons(sizeof(struct tcphdr));
+ if (dir) {
+ h6->ip6_src = id->src_ip6;
+ h6->ip6_dst = id->dst_ip6;
+ } else {
+ h6->ip6_src = id->dst_ip6;
+ h6->ip6_dst = id->src_ip6;
+ }
+
+ th = (struct tcphdr *)(h6 + 1);
+ break;
+#endif
+ }
+
+ if (dir) {
+ th->th_sport = htons(id->src_port);
+ th->th_dport = htons(id->dst_port);
+ } else {
+ th->th_sport = htons(id->dst_port);
+ th->th_dport = htons(id->src_port);
+ }
+ th->th_off = sizeof(struct tcphdr) >> 2;
+
+ if (flags & TH_RST) {
+ if (flags & TH_ACK) {
+ th->th_seq = htonl(ack);
+ th->th_flags = TH_RST;
+ } else {
+ if (flags & TH_SYN)
+ seq++;
+ th->th_ack = htonl(seq);
+ th->th_flags = TH_RST | TH_ACK;
+ }
+ } else {
+ /*
+ * Keepalive - use caller provided sequence numbers
+ */
+ th->th_seq = htonl(seq);
+ th->th_ack = htonl(ack);
+ th->th_flags = TH_ACK;
+ }
+
+ switch (id->addr_type) {
+ case 4:
+ th->th_sum = in_cksum(m, len);
+
+ /* finish the ip header */
+ h->ip_v = 4;
+ h->ip_hl = sizeof(*h) >> 2;
+ h->ip_tos = IPTOS_LOWDELAY;
+ h->ip_off = 0;
+ h->ip_len = htons(len);
+ h->ip_ttl = V_ip_defttl;
+ h->ip_sum = 0;
+ break;
+#ifdef INET6
+ case 6:
+ th->th_sum = in6_cksum(m, IPPROTO_TCP, sizeof(*h6),
+ sizeof(struct tcphdr));
+
+ /* finish the ip6 header */
+ h6->ip6_vfc |= IPV6_VERSION;
+ h6->ip6_hlim = IPV6_DEFHLIM;
+ break;
+#endif
+ }
+
+ return (m);
+#endif /* !__linux__ */
+}
+
+/*
+ * This procedure is only used to handle keepalives. It is invoked
+ * every dyn_keepalive_period
+ */
+static void
+ipfw_tick(void * vnetx)
+{
+ struct mbuf *m0, *m, *mnext, **mtailp;
+#ifdef INET6
+ struct mbuf *m6, **m6_tailp;
+#endif
+ int i;
+ ipfw_dyn_rule *q;
+#ifdef VIMAGE
+ struct vnet *vp = vnetx;
+#endif
+
+ CURVNET_SET(vp);
+ if (V_dyn_keepalive == 0 || V_ipfw_dyn_v == NULL || V_dyn_count == 0)
+ goto done;
+
+ /*
+ * We make a chain of packets to go out here -- not deferring
+ * until after we drop the IPFW dynamic rule lock would result
+ * in a lock order reversal with the normal packet input -> ipfw
+ * call stack.
+ */
+ m0 = NULL;
+ mtailp = &m0;
+#ifdef INET6
+ m6 = NULL;
+ m6_tailp = &m6;
+#endif
+ IPFW_DYN_LOCK();
+ for (i = 0 ; i < V_curr_dyn_buckets ; i++) {
+ for (q = V_ipfw_dyn_v[i] ; q ; q = q->next ) {
+ if (q->dyn_type == O_LIMIT_PARENT)
+ continue;
+ if (q->id.proto != IPPROTO_TCP)
+ continue;
+ if ( (q->state & BOTH_SYN) != BOTH_SYN)
+ continue;
+ if (TIME_LEQ(time_uptime + V_dyn_keepalive_interval,
+ q->expire))
+ continue; /* too early */
+ if (TIME_LEQ(q->expire, time_uptime))
+ continue; /* too late, rule expired */
+
+ m = ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1,
+ q->ack_fwd, TH_SYN);
+ mnext = ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1,
+ q->ack_rev, 0);
+
+ switch (q->id.addr_type) {
+ case 4:
+ if (m != NULL) {
+ *mtailp = m;
+ mtailp = &(*mtailp)->m_nextpkt;
+ }
+ if (mnext != NULL) {
+ *mtailp = mnext;
+ mtailp = &(*mtailp)->m_nextpkt;
+ }
+ break;
+#ifdef INET6
+ case 6:
+ if (m != NULL) {
+ *m6_tailp = m;
+ m6_tailp = &(*m6_tailp)->m_nextpkt;
+ }
+ if (mnext != NULL) {
+ *m6_tailp = mnext;
+ m6_tailp = &(*m6_tailp)->m_nextpkt;
+ }
+ break;
+#endif
+ }
+
+ m = mnext = NULL;
+ }
+ }
+ IPFW_DYN_UNLOCK();
+ for (m = mnext = m0; m != NULL; m = mnext) {
+ mnext = m->m_nextpkt;
+ m->m_nextpkt = NULL;
+ ip_output(m, NULL, NULL, 0, NULL, NULL);
+ }
+#ifdef INET6
+ for (m = mnext = m6; m != NULL; m = mnext) {
+ mnext = m->m_nextpkt;
+ m->m_nextpkt = NULL;
+ ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
+ }
+#endif
+done:
+ callout_reset(&V_ipfw_timeout, V_dyn_keepalive_period * hz,
+ ipfw_tick, vnetx);
+ CURVNET_RESTORE();
+}
+
+void
+ipfw_dyn_attach(void)
+{
+ ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule",
+ sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL,
+ UMA_ALIGN_PTR, 0);
+
+ IPFW_DYN_LOCK_INIT();
+}
+
+void
+ipfw_dyn_detach(void)
+{
+ uma_zdestroy(ipfw_dyn_rule_zone);
+ IPFW_DYN_LOCK_DESTROY();
+}
+
+void
+ipfw_dyn_init(void)
+{
+ V_ipfw_dyn_v = NULL;
+ V_dyn_buckets = 256; /* must be power of 2 */
+ V_curr_dyn_buckets = 256; /* must be power of 2 */
+
+ V_dyn_ack_lifetime = 300;
+ V_dyn_syn_lifetime = 20;
+ V_dyn_fin_lifetime = 1;
+ V_dyn_rst_lifetime = 1;
+ V_dyn_udp_lifetime = 10;
+ V_dyn_short_lifetime = 5;
+
+ V_dyn_keepalive_interval = 20;
+ V_dyn_keepalive_period = 5;
+ V_dyn_keepalive = 1; /* do send keepalives */
+
+ V_dyn_max = 4096; /* max # of dynamic rules */
+ callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE);
+ callout_reset(&V_ipfw_timeout, hz, ipfw_tick, curvnet);
+}
+
+void
+ipfw_dyn_uninit(int pass)
+{
+ if (pass == 0)
+ callout_drain(&V_ipfw_timeout);
+ else {
+ if (V_ipfw_dyn_v != NULL)
+ free(V_ipfw_dyn_v, M_IPFW);
+ }
+}
+
+int
+ipfw_dyn_len(void)
+{
+ return (V_ipfw_dyn_v == NULL) ? 0 :
+ (V_dyn_count * sizeof(ipfw_dyn_rule));
+}
+
+void
+ipfw_get_dynamic(char **pbp, const char *ep)
+{
+ ipfw_dyn_rule *p, *last = NULL;
+ char *bp;
+ int i;
+
+ if (V_ipfw_dyn_v == NULL)
+ return;
+ bp = *pbp;
+
+ IPFW_DYN_LOCK();
+ for (i = 0 ; i < V_curr_dyn_buckets; i++)
+ for (p = V_ipfw_dyn_v[i] ; p != NULL; p = p->next) {
+ if (bp + sizeof *p <= ep) {
+ ipfw_dyn_rule *dst =
+ (ipfw_dyn_rule *)bp;
+ bcopy(p, dst, sizeof *p);
+ bcopy(&(p->rule->rulenum), &(dst->rule),
+ sizeof(p->rule->rulenum));
+ /*
+ * store set number into high word of
+ * dst->rule pointer.
+ */
+ bcopy(&(p->rule->set),
+ (char *)&dst->rule +
+ sizeof(p->rule->rulenum),
+ sizeof(p->rule->set));
+ /*
+ * store a non-null value in "next".
+ * The userland code will interpret a
+ * NULL here as a marker
+ * for the last dynamic rule.
+ */
+ bcopy(&dst, &dst->next, sizeof(dst));
+ last = dst;
+ dst->expire =
+ TIME_LEQ(dst->expire, time_uptime) ?
+ 0 : dst->expire - time_uptime ;
+ bp += sizeof(ipfw_dyn_rule);
+ }
+ }
+ IPFW_DYN_UNLOCK();
+ if (last != NULL) /* mark last dynamic rule */
+ bzero(&last->next, sizeof(last));
+ *pbp = bp;
+}
+/* end of file */
git://git.onelab.eu / ipfw.git / blobdiff