/*- * 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 __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 #include #include #include #include #include #include #include #include #include /* for ETHERTYPE_IP */ #include #include #include #include #include /* ip_defttl */ #include #include #include #include #include /* IN6_ARE_ADDR_EQUAL */ #ifdef INET6 #include #include #endif #include /* XXX for in_cksum */ #ifdef MAC #include #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; #ifndef __FreeBSD__ 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 SYSBEGIN(f2) 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"); SYSEND #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) { struct mbuf *m = NULL; /* stupid compiler */ 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; /* ip_len must be in host format for ip_output */ h->ip_len = 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); } /* * This procedure is only used to handle keepalives. It is invoked * every dyn_keepalive_period */ /* dummynet() and ipfw_tick() can't be static in windows */ 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_on(&V_ipfw_timeout, V_dyn_keepalive_period * hz, ipfw_tick, vnetx, 0); 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_on(&V_ipfw_timeout, hz, ipfw_tick, curvnet, 0); } 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 */