/*- * 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("$FreeBSD$"); #define DEB(x) #define DDB(x) x /* * Dynamic rule support for ipfw */ #include "opt_ipfw.h" #include "opt_inet.h" #ifndef INET #error IPFIREWALL requires INET. #endif /* INET */ #include "opt_inet6.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 /* IN6_ARE_ADDR_EQUAL */ #ifdef INET6 #include #include #endif #include #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 equal to UMA zone items 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!!! */ struct ipfw_dyn_bucket { struct mtx mtx; /* Bucket protecting lock */ ipfw_dyn_rule *head; /* Pointer to first rule */ }; /* * Static variables followed by global ones */ static VNET_DEFINE(struct ipfw_dyn_bucket *, ipfw_dyn_v); static VNET_DEFINE(u_int32_t, dyn_buckets_max); 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_max VNET(dyn_buckets_max) #define V_curr_dyn_buckets VNET(curr_dyn_buckets) #define V_ipfw_timeout VNET(ipfw_timeout) static VNET_DEFINE(uma_zone_t, ipfw_dyn_rule_zone); #define V_ipfw_dyn_rule_zone VNET(ipfw_dyn_rule_zone) #define IPFW_BUCK_LOCK_INIT(b) \ mtx_init(&(b)->mtx, "IPFW dynamic bucket", NULL, MTX_DEF) #define IPFW_BUCK_LOCK_DESTROY(b) \ mtx_destroy(&(b)->mtx) #define IPFW_BUCK_LOCK(i) mtx_lock(&V_ipfw_dyn_v[(i)].mtx) #define IPFW_BUCK_UNLOCK(i) mtx_unlock(&V_ipfw_dyn_v[(i)].mtx) #define IPFW_BUCK_ASSERT(i) mtx_assert(&V_ipfw_dyn_v[(i)].mtx, MA_OWNED) /* * 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); static VNET_DEFINE(time_t, dyn_keepalive_last); #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) #define V_dyn_keepalive_last VNET(dyn_keepalive_last) static VNET_DEFINE(u_int32_t, dyn_max); /* max # of dynamic rules */ #define DYN_COUNT uma_zone_get_cur(V_ipfw_dyn_rule_zone) #define V_dyn_max VNET(dyn_max) static int last_log; /* Log ratelimiting */ static void ipfw_dyn_tick(void *vnetx); static void check_dyn_rules(struct ip_fw_chain *, struct ip_fw *, int, int, int); #ifdef SYSCTL_NODE static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS); static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS); SYSBEGIN(f2) SYSCTL_DECL(_net_inet_ip_fw); SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW, &VNET_NAME(dyn_buckets_max), 0, "Max number of dyn. buckets"); SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD, &VNET_NAME(curr_dyn_buckets), 0, "Current Number of dyn. buckets"); SYSCTL_VNET_PROC(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLTYPE_UINT|CTLFLAG_RD, 0, 0, sysctl_ipfw_dyn_count, "IU", "Number of dyn. rules"); SYSCTL_VNET_PROC(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLTYPE_UINT|CTLFLAG_RW, 0, 0, sysctl_ipfw_dyn_max, "IU", "Max number of dyn. rules"); SYSCTL_VNET_UINT(_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_UINT(_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_UINT(_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_UINT(_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_UINT(_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_UINT(_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_UINT(_net_inet_ip_fw, OID_AUTO, dyn_keepalive, CTLFLAG_RW, &VNET_NAME(dyn_keepalive), 0, "Enable keepalives for dyn. rules"); SYSEND #endif /* SYSCTL_NODE */ #ifdef INET6 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; } #endif /* * 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, int buckets) { 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 &= (buckets - 1); return i; } /** * Print customizable flow id description via log(9) facility. */ static void print_dyn_rule_flags(struct ipfw_flow_id *id, int dyn_type, int log_flags, char *prefix, char *postfix) { 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_ntop(AF_INET, &da, src, sizeof(src)); da.s_addr = htonl(id->dst_ip); inet_ntop(AF_INET, &da, dst, sizeof(dst)); } log(log_flags, "ipfw: %s type %d %s %d -> %s %d, %d %s\n", prefix, dyn_type, src, id->src_port, dst, id->dst_port, DYN_COUNT, postfix); } #define print_dyn_rule(id, dtype, prefix, postfix) \ print_dyn_rule_flags(id, dtype, LOG_DEBUG, prefix, postfix) #define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0) /* * Lookup a dynamic rule, locked version. */ static ipfw_dyn_rule * lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int i, 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 dir = MATCH_NONE; ipfw_dyn_rule *prev, *q = NULL; IPFW_BUCK_ASSERT(i); for (prev = NULL, q = V_ipfw_dyn_v[i].head; q; prev = q, q = q->next) { if (q->dyn_type == O_LIMIT_PARENT && q->count) continue; if (pkt->proto != q->id.proto || q->dyn_type == O_LIMIT_PARENT) continue; 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; } } } 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].head; V_ipfw_dyn_v[i].head = q; } if (pkt->proto == IPPROTO_TCP) { /* update state according to flags */ uint32_t ack; 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)) #define TCP_FLAGS (TH_FLAGS | (TH_FLAGS << 8)) #define ACK_FWD 0x10000 /* fwd ack seen */ #define ACK_REV 0x20000 /* rev ack seen */ q->state |= (dir == MATCH_FORWARD) ? flags : (flags << 8); switch (q->state & TCP_FLAGS) { 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): #define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0) if (tcp == NULL) break; ack = ntohl(tcp->th_ack); if (dir == MATCH_FORWARD) { if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd)) { q->ack_fwd = ack; q->state |= ACK_FWD; } } else { if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev)) { q->ack_rev = ack; q->state |= ACK_REV; } } if ((q->state & (ACK_FWD | ACK_REV)) == (ACK_FWD | ACK_REV)) { q->expire = time_uptime + V_dyn_ack_lifetime; q->state &= ~(ACK_FWD | ACK_REV); } 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 != NULL) *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; int i; i = hash_packet(pkt, V_curr_dyn_buckets); IPFW_BUCK_LOCK(i); q = lookup_dyn_rule_locked(pkt, i, match_direction, tcp); if (q == NULL) IPFW_BUCK_UNLOCK(i); /* NB: return table locked when q is not NULL */ return q; } /* * Unlock bucket mtx * @p - pointer to dynamic rule */ void ipfw_dyn_unlock(ipfw_dyn_rule *q) { IPFW_BUCK_UNLOCK(q->bucket); } static int resize_dynamic_table(struct ip_fw_chain *chain, int nbuckets) { int i, k, nbuckets_old; ipfw_dyn_rule *q; struct ipfw_dyn_bucket *dyn_v, *dyn_v_old; /* Check if given number is power of 2 and less than 64k */ if ((nbuckets > 65536) || (!powerof2(nbuckets))) return 1; CTR3(KTR_NET, "%s: resize dynamic hash: %d -> %d", __func__, V_curr_dyn_buckets, nbuckets); /* Allocate and initialize new hash */ dyn_v = malloc(nbuckets * sizeof(ipfw_dyn_rule), M_IPFW, M_WAITOK | M_ZERO); for (i = 0 ; i < nbuckets; i++) IPFW_BUCK_LOCK_INIT(&dyn_v[i]); /* * Call upper half lock, as get_map() do to ease * read-only access to dynamic rules hash from sysctl */ IPFW_UH_WLOCK(chain); /* * Acquire chain write lock to permit hash access * for main traffic path without additional locks */ IPFW_WLOCK(chain); /* Save old values */ nbuckets_old = V_curr_dyn_buckets; dyn_v_old = V_ipfw_dyn_v; /* Skip relinking if array is not set up */ if (V_ipfw_dyn_v == NULL) V_curr_dyn_buckets = 0; /* Re-link all dynamic states */ for (i = 0 ; i < V_curr_dyn_buckets ; i++) { while (V_ipfw_dyn_v[i].head != NULL) { /* Remove from current chain */ q = V_ipfw_dyn_v[i].head; V_ipfw_dyn_v[i].head = q->next; /* Get new hash value */ k = hash_packet(&q->id, nbuckets); q->bucket = k; /* Add to the new head */ q->next = dyn_v[k].head; dyn_v[k].head = q; } } /* Update current pointers/buckets values */ V_curr_dyn_buckets = nbuckets; V_ipfw_dyn_v = dyn_v; IPFW_WUNLOCK(chain); IPFW_UH_WUNLOCK(chain); /* Start periodic callout on initial creation */ if (dyn_v_old == NULL) { callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, curvnet, 0); return (0); } /* Destroy all mutexes */ for (i = 0 ; i < nbuckets_old ; i++) IPFW_BUCK_LOCK_DESTROY(&dyn_v_old[i]); /* Free old hash */ free(dyn_v_old, M_IPFW); return 0; } /** * 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, int i, u_int8_t dyn_type, struct ip_fw *rule) { ipfw_dyn_rule *r; IPFW_BUCK_ASSERT(i); r = uma_zalloc(V_ipfw_dyn_rule_zone, M_NOWAIT | M_ZERO); if (r == NULL) { if (last_log != time_uptime) { last_log = time_uptime; log(LOG_DEBUG, "ipfw: %s: Cannot allocate rule\n", __func__); } return NULL; } /* * refcount on parent is already incremented, so * it is safe to use parent unlocked. */ if (dyn_type == O_LIMIT) { ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule; if ( parent->dyn_type != O_LIMIT_PARENT) panic("invalid parent"); 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; IPFW_ZERO_DYN_COUNTER(r); r->count = 0; r->bucket = i; r->next = V_ipfw_dyn_v[i].head; V_ipfw_dyn_v[i].head = r; DEB(print_dyn_rule(id, dyn_type, "add dyn entry", "total");) 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, int *pindex, struct ip_fw *rule) { ipfw_dyn_rule *q; int i, is_v6; is_v6 = IS_IP6_FLOW_ID(pkt); i = hash_packet( pkt, V_curr_dyn_buckets ); *pindex = i; IPFW_BUCK_LOCK(i); for (q = V_ipfw_dyn_v[i].head ; 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(print_dyn_rule(pkt, q->dyn_type, "lookup_dyn_parent found", "");) return q; } /* Add virtual limiting rule */ return add_dyn_rule(pkt, i, 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) { ipfw_dyn_rule *q; int i; DEB(print_dyn_rule(&args->f_id, cmd->o.opcode, "install_state", "");) i = hash_packet(&args->f_id, V_curr_dyn_buckets); IPFW_BUCK_LOCK(i); q = lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL); if (q != NULL) { /* should never occur */ DEB( if (last_log != time_uptime) { last_log = time_uptime; printf("ipfw: %s: entry already present, done\n", __func__); }) IPFW_BUCK_UNLOCK(i); return (0); } /* * State limiting is done via uma(9) zone limiting. * Save pointer to newly-installed rule and reject * packet if add_dyn_rule() returned NULL. * Note q is currently set to NULL. */ switch (cmd->o.opcode) { case O_KEEP_STATE: /* bidir rule */ q = add_dyn_rule(&args->f_id, i, 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; int pindex; conn_limit = IP_FW_ARG_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; /* * We have to release lock for previous bucket to * avoid possible deadlock */ IPFW_BUCK_UNLOCK(i); if ((parent = lookup_dyn_parent(&id, &pindex, rule)) == NULL) { printf("ipfw: %s: add parent failed\n", __func__); IPFW_BUCK_UNLOCK(pindex); return (1); } if (parent->count >= conn_limit) { if (V_fw_verbose && last_log != time_uptime) { last_log = time_uptime; char sbuf[24]; last_log = time_uptime; snprintf(sbuf, sizeof(sbuf), "%d drop session", parent->rule->rulenum); print_dyn_rule_flags(&args->f_id, cmd->o.opcode, LOG_SECURITY | LOG_DEBUG, sbuf, "too many entries"); } IPFW_BUCK_UNLOCK(pindex); return (1); } /* Increment counter on parent */ parent->count++; IPFW_BUCK_UNLOCK(pindex); IPFW_BUCK_LOCK(i); q = add_dyn_rule(&args->f_id, i, O_LIMIT, (struct ip_fw *)parent); if (q == NULL) { /* Decrement index and notify caller */ IPFW_BUCK_UNLOCK(i); IPFW_BUCK_LOCK(pindex); parent->count--; IPFW_BUCK_UNLOCK(pindex); return (1); } break; } default: printf("ipfw: %s: unknown dynamic rule type %u\n", __func__, cmd->o.opcode); } if (q == NULL) { IPFW_BUCK_UNLOCK(i); return (1); /* Notify caller about failure */ } /* XXX just set lifetime */ lookup_dyn_rule_locked(&args->f_id, i, NULL, NULL); IPFW_BUCK_UNLOCK(i); 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_NOWAIT, 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 = htons(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); } /* * Queue keepalive packets for given dynamic rule */ static struct mbuf ** ipfw_dyn_send_ka(struct mbuf **mtailp, ipfw_dyn_rule *q) { struct mbuf *m_rev, *m_fwd; m_rev = (q->state & ACK_REV) ? NULL : ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN); m_fwd = (q->state & ACK_FWD) ? NULL : ipfw_send_pkt(NULL, &(q->id), q->ack_fwd - 1, q->ack_rev, 0); if (m_rev != NULL) { *mtailp = m_rev; mtailp = &(*mtailp)->m_nextpkt; } if (m_fwd != NULL) { *mtailp = m_fwd; mtailp = &(*mtailp)->m_nextpkt; } return (mtailp); } /* * This procedure is used to perform various maintance * on dynamic hash list. Currently it is called every second. */ static void ipfw_dyn_tick(void * vnetx) { struct ip_fw_chain *chain; int check_ka = 0; #ifdef VIMAGE struct vnet *vp = vnetx; #endif CURVNET_SET(vp); chain = &V_layer3_chain; /* Run keepalive checks every keepalive_period iff ka is enabled */ if ((V_dyn_keepalive_last + V_dyn_keepalive_period <= time_uptime) && (V_dyn_keepalive != 0)) { V_dyn_keepalive_last = time_uptime; check_ka = 1; } check_dyn_rules(chain, NULL, RESVD_SET, check_ka, 1); callout_reset_on(&V_ipfw_timeout, hz, ipfw_dyn_tick, vnetx, 0); CURVNET_RESTORE(); } /* * Walk thru all dynamic states doing generic maintance: * 1) free expired states * 2) free all states based on deleted rule / set * 3) send keepalives for states if needed * * @chain - pointer to current ipfw rules chain * @rule - delete all states originated by given rule if != NULL * @set - delete all states originated by any rule in set @set if != RESVD_SET * @check_ka - perform checking/sending keepalives * @timer - indicate call from timer routine. * * Timer routine must call this function unlocked to permit * sending keepalives/resizing table. * * Others has to call function with IPFW_UH_WLOCK held. * Additionally, function assume that dynamic rule/set is * ALREADY deleted so no new states can be generated by * 'deleted' rules. * * Write lock is needed to ensure that unused parent rules * are not freed by other instance (see stage 2, 3) */ static void check_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule, int set, int check_ka, int timer) { struct mbuf *m0, *m, *mnext, **mtailp; struct ip *h; int i, dyn_count, new_buckets = 0, max_buckets; int expired = 0, expired_limits = 0, parents = 0, total = 0; ipfw_dyn_rule *q, *q_prev, *q_next; ipfw_dyn_rule *exp_head, **exptailp; ipfw_dyn_rule *exp_lhead, **expltailp; KASSERT(V_ipfw_dyn_v != NULL, ("%s: dynamic table not allocated", __func__)); /* Avoid possible LOR */ KASSERT(!check_ka || timer, ("%s: keepalive check with lock held", __func__)); /* * Do not perform any checks if we currently have no dynamic states */ if (DYN_COUNT == 0) return; /* Expired states */ exp_head = NULL; exptailp = &exp_head; /* Expired limit states */ exp_lhead = NULL; expltailp = &exp_lhead; /* * 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; /* Protect from hash resizing */ if (timer != 0) IPFW_UH_WLOCK(chain); else IPFW_UH_WLOCK_ASSERT(chain); #define NEXT_RULE() { q_prev = q; q = q->next ; continue; } /* Stage 1: perform requested deletion */ for (i = 0 ; i < V_curr_dyn_buckets ; i++) { IPFW_BUCK_LOCK(i); for (q = V_ipfw_dyn_v[i].head, q_prev = q; q ; ) { /* account every rule */ total++; /* Skip parent rules at all */ if (q->dyn_type == O_LIMIT_PARENT) { parents++; NEXT_RULE(); } /* * Remove rules which are: * 1) expired * 2) created by given rule * 3) created by any rule in given set */ if ((TIME_LEQ(q->expire, time_uptime)) || ((rule != NULL) && (q->rule == rule)) || ((set != RESVD_SET) && (q->rule->set == set))) { /* Unlink q from current list */ q_next = q->next; if (q == V_ipfw_dyn_v[i].head) V_ipfw_dyn_v[i].head = q_next; else q_prev->next = q_next; q->next = NULL; /* queue q to expire list */ if (q->dyn_type != O_LIMIT) { *exptailp = q; exptailp = &(*exptailp)->next; DEB(print_dyn_rule(&q->id, q->dyn_type, "unlink entry", "left"); ) } else { /* Separate list for limit rules */ *expltailp = q; expltailp = &(*expltailp)->next; expired_limits++; DEB(print_dyn_rule(&q->id, q->dyn_type, "unlink limit entry", "left"); ) } q = q_next; expired++; continue; } /* * Check if we need to send keepalive: * we need to ensure if is time to do KA, * this is established TCP session, and * expire time is within keepalive interval */ if ((check_ka != 0) && (q->id.proto == IPPROTO_TCP) && ((q->state & BOTH_SYN) == BOTH_SYN) && (TIME_LEQ(q->expire, time_uptime + V_dyn_keepalive_interval))) mtailp = ipfw_dyn_send_ka(mtailp, q); NEXT_RULE(); } IPFW_BUCK_UNLOCK(i); } /* Stage 2: decrement counters from O_LIMIT parents */ if (expired_limits != 0) { /* * XXX: Note that deleting set with more than one * heavily-used LIMIT rules can result in overwhelming * locking due to lack of per-hash value sorting * * We should probably think about: * 1) pre-allocating hash of size, say, * MAX(16, V_curr_dyn_buckets / 1024) * 2) checking if expired_limits is large enough * 3) If yes, init hash (or its part), re-link * current list and start decrementing procedure in * each bucket separately */ /* * Small optimization: do not unlock bucket until * we see the next item resides in different bucket */ if (exp_lhead != NULL) { i = exp_lhead->parent->bucket; IPFW_BUCK_LOCK(i); } for (q = exp_lhead; q != NULL; q = q->next) { if (i != q->parent->bucket) { IPFW_BUCK_UNLOCK(i); i = q->parent->bucket; IPFW_BUCK_LOCK(i); } /* Decrease parent refcount */ q->parent->count--; } if (exp_lhead != NULL) IPFW_BUCK_UNLOCK(i); } /* * We protectet ourselves from unused parent deletion * (from the timer function) by holding UH write lock. */ /* Stage 3: remove unused parent rules */ if ((parents != 0) && (expired != 0)) { for (i = 0 ; i < V_curr_dyn_buckets ; i++) { IPFW_BUCK_LOCK(i); for (q = V_ipfw_dyn_v[i].head, q_prev = q ; q ; ) { if (q->dyn_type != O_LIMIT_PARENT) NEXT_RULE(); if (q->count != 0) NEXT_RULE(); /* Parent rule without consumers */ /* Unlink q from current list */ q_next = q->next; if (q == V_ipfw_dyn_v[i].head) V_ipfw_dyn_v[i].head = q_next; else q_prev->next = q_next; q->next = NULL; /* Add to expired list */ *exptailp = q; exptailp = &(*exptailp)->next; DEB(print_dyn_rule(&q->id, q->dyn_type, "unlink parent entry", "left"); ) expired++; q = q_next; } IPFW_BUCK_UNLOCK(i); } } #undef NEXT_RULE if (timer != 0) { /* * Check if we need to resize hash: * if current number of states exceeds number of buckes in hash, * grow hash size to the minimum power of 2 which is bigger than * current states count. Limit hash size by 64k. */ max_buckets = (V_dyn_buckets_max > 65536) ? 65536 : V_dyn_buckets_max; dyn_count = DYN_COUNT; if ((dyn_count > V_curr_dyn_buckets * 2) && (dyn_count < max_buckets)) { new_buckets = V_curr_dyn_buckets; while (new_buckets < dyn_count) { new_buckets *= 2; if (new_buckets >= max_buckets) break; } } IPFW_UH_WUNLOCK(chain); } /* Finally delete old states ad limits if any */ for (q = exp_head; q != NULL; q = q_next) { q_next = q->next; uma_zfree(V_ipfw_dyn_rule_zone, q); } for (q = exp_lhead; q != NULL; q = q_next) { q_next = q->next; uma_zfree(V_ipfw_dyn_rule_zone, q); } /* * The rest code MUST be called from timer routine only * without holding any locks */ if (timer == 0) return; /* Send keepalive packets if any */ for (m = m0; m != NULL; m = mnext) { mnext = m->m_nextpkt; m->m_nextpkt = NULL; h = mtod(m, struct ip *); if (h->ip_v == 4) ip_output(m, NULL, NULL, 0, NULL, NULL); #ifdef INET6 else ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL); #endif } /* Run table resize without holding any locks */ if (new_buckets != 0) resize_dynamic_table(chain, new_buckets); } /* * Deletes all dynamic rules originated by given rule or all rules in * given set. Specify RESVD_SET to indicate set should not be used. * @chain - pointer to current ipfw rules chain * @rule - delete all states originated by given rule if != NULL * @set - delete all states originated by any rule in set @set if != RESVD_SET * * Function has to be called with IPFW_UH_WLOCK held. * Additionally, function assume that dynamic rule/set is * ALREADY deleted so no new states can be generated by * 'deleted' rules. */ void ipfw_expire_dyn_rules(struct ip_fw_chain *chain, struct ip_fw *rule, int set) { check_dyn_rules(chain, rule, set, 0, 0); } void ipfw_dyn_init(struct ip_fw_chain *chain) { V_ipfw_dyn_v = NULL; V_dyn_buckets_max = 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_keepalive_last = time_uptime; V_dyn_max = 4096; /* max # of dynamic rules */ V_ipfw_dyn_rule_zone = uma_zcreate("IPFW dynamic rule", sizeof(ipfw_dyn_rule), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); /* Enforce limit on dynamic rules */ uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max); callout_init(&V_ipfw_timeout, CALLOUT_MPSAFE); /* * This can potentially be done on first dynamic rule * being added to chain. */ resize_dynamic_table(chain, V_curr_dyn_buckets); } void ipfw_dyn_uninit(int pass) { int i; if (pass == 0) { callout_drain(&V_ipfw_timeout); return; } if (V_ipfw_dyn_v != NULL) { /* * Skip deleting all dynamic states - * uma_zdestroy() does this more efficiently; */ /* Destroy all mutexes */ for (i = 0 ; i < V_curr_dyn_buckets ; i++) IPFW_BUCK_LOCK_DESTROY(&V_ipfw_dyn_v[i]); free(V_ipfw_dyn_v, M_IPFW); V_ipfw_dyn_v = NULL; } uma_zdestroy(V_ipfw_dyn_rule_zone); } #ifdef SYSCTL_NODE /* * Get/set maximum number of dynamic states in given VNET instance. */ static int sysctl_ipfw_dyn_max(SYSCTL_HANDLER_ARGS) { int error; unsigned int nstates; nstates = V_dyn_max; error = sysctl_handle_int(oidp, &nstates, 0, req); /* Read operation or some error */ if ((error != 0) || (req->newptr == NULL)) return (error); V_dyn_max = nstates; uma_zone_set_max(V_ipfw_dyn_rule_zone, V_dyn_max); return (0); } /* * Get current number of dynamic states in given VNET instance. */ static int sysctl_ipfw_dyn_count(SYSCTL_HANDLER_ARGS) { int error; unsigned int nstates; nstates = DYN_COUNT; error = sysctl_handle_int(oidp, &nstates, 0, req); return (error); } #endif /* * Returns number of dynamic rules. */ int ipfw_dyn_len(void) { return (V_ipfw_dyn_v == NULL) ? 0 : (DYN_COUNT * sizeof(ipfw_dyn_rule)); } /* * Fill given buffer with dynamic states. * IPFW_UH_RLOCK has to be held while calling. */ void ipfw_get_dynamic(struct ip_fw_chain *chain, 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_UH_RLOCK_ASSERT(chain); for (i = 0 ; i < V_curr_dyn_buckets; i++) { IPFW_BUCK_LOCK(i); for (p = V_ipfw_dyn_v[i].head ; 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_BUCK_UNLOCK(i); } if (last != NULL) /* mark last dynamic rule */ bzero(&last->next, sizeof(last)); *pbp = bp; } /* end of file */