diff options
Diffstat (limited to 'sys/netpfil/ipfw/ip_fw_dynamic.c')
| -rw-r--r-- | sys/netpfil/ipfw/ip_fw_dynamic.c | 1245 |
1 files changed, 1245 insertions, 0 deletions
diff --git a/sys/netpfil/ipfw/ip_fw_dynamic.c b/sys/netpfil/ipfw/ip_fw_dynamic.c new file mode 100644 index 0000000..28d2d51 --- /dev/null +++ b/sys/netpfil/ipfw/ip_fw_dynamic.c @@ -0,0 +1,1245 @@ +/*- + * 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("$FreeBSD$"); + +#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 <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/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 <netpfil/ipfw/ip_fw_private.h> + +#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; +#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_UINT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, + CTLFLAG_RW, &VNET_NAME(dyn_buckets), 0, + "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_UINT(_net_inet_ip_fw, OID_AUTO, dyn_count, + CTLFLAG_RD, &VNET_NAME(dyn_count), 0, + "Number of dyn. rules"); +SYSCTL_VNET_UINT(_net_inet_ip_fw, OID_AUTO, dyn_max, + CTLFLAG_RW, &VNET_NAME(dyn_max), 0, + "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 */ + + +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_ntop(AF_INET, &da, src, sizeof(src)); + da.s_addr = htonl(id->dst_ip); + inet_ntop(AF_INET, &da, dst, sizeof(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) + goto next; + + 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 */ + 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; + + 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_ntop(AF_INET, &da, src, sizeof(src)); + da.s_addr = htonl(r->id.dst_ip); + inet_ntop(AF_INET, &da, dst, sizeof(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_ntop(AF_INET, &da, src, sizeof(src)); + da.s_addr = htonl(args->f_id.dst_ip); + inet_ntop(AF_INET, &da, dst, sizeof(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 */ + DEB( + 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_ntop(AF_INET, &da, src, + sizeof(src)); + da.s_addr = + htonl(args->f_id.dst_ip); + inet_ntop(AF_INET, &da, dst, + sizeof(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 + */ +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 = (q->state & ACK_REV) ? NULL : + ipfw_send_pkt(NULL, &(q->id), q->ack_rev - 1, + q->ack_fwd, TH_SYN); + mnext = (q->state & ACK_FWD) ? NULL : + 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 + } + } + } + IPFW_DYN_UNLOCK(); + for (m = 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 = 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 */ |
