/** * 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, uint8_t dyn_type, struct ip_fw *rule, uint16_t kidx) { 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: Cannot allocate dynamic state, " "consider increasing net.inet.ip.fw.dyn_max\n"); } return NULL; } ipfw_dyn_count++; /* * 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->kidx = kidx; 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 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); }
/* * 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. */ ipfw_dyn_rule *prev, *q = NULL; int dir; IPFW_BUCK_ASSERT(i); dir = MATCH_NONE; 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; } /* update state according to flags */ dyn_update_proto_state(q, pkt, tcp, dir); done: if (match_direction != NULL) *match_direction = dir; return (q); }