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freebsd-skq/sys/netinet/ip_fw.c
luigi 0fb106cc3f Two main changes here: 
+ implement "limit" rules, which permit to limit the number of sessions
   between certain host pairs (according to masks). These are a special
   type of stateful rules, which might be of interest in some cases.
   See the ipfw manpage for details.

 + merge the list pointers and ipfw rule descriptors in the kernel, so
   the code is smaller, faster and more readable. This patch basically
   consists in replacing "foo->rule->bar" with "rule->bar" all over
   the place.
   I have been willing to do this for ages!

MFC after: 1 week
2001-09-27 23:44:27 +00:00

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/*
* Copyright (c) 1993 Daniel Boulet
* Copyright (c) 1994 Ugen J.S.Antsilevich
* Copyright (c) 1996 Alex Nash
* Copyright (c) 2000-2001 Luigi Rizzo
*
* Redistribution and use in source forms, with and without modification,
* are permitted provided that this entire comment appears intact.
*
* Redistribution in binary form may occur without any restrictions.
* Obviously, it would be nice if you gave credit where credit is due
* but requiring it would be too onerous.
*
* This software is provided ``AS IS'' without any warranties of any kind.
*
* $FreeBSD$
*/
#define DEB(x)
#define DDB(x) x
/*
* Implement IP packet firewall
*/
#if !defined(KLD_MODULE)
#include "opt_ipfw.h"
#include "opt_ipdn.h"
#include "opt_ipdivert.h"
#include "opt_inet.h"
#ifndef INET
#error IPFIREWALL requires INET.
#endif /* INET */
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/ucred.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/in_pcb.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_fw.h>
#ifdef DUMMYNET
#include <netinet/ip_dummynet.h>
#endif
#include <netinet/tcp.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/if_ether.h> /* XXX ethertype_ip */
static int fw_debug = 1;
#ifdef IPFIREWALL_VERBOSE
static int fw_verbose = 1;
#else
static int fw_verbose = 0;
#endif
int fw_one_pass = 1 ;
#ifdef IPFIREWALL_VERBOSE_LIMIT
static int fw_verbose_limit = IPFIREWALL_VERBOSE_LIMIT;
#else
static int fw_verbose_limit = 0;
#endif
static int fw_permanent_rules = 0;
/*
* Right now, two fields in the IP header are changed to host format
* by the IP layer before calling the firewall. Ideally, we would like
* to have them in network format so that the packet can be
* used as it comes from the device driver (and is thus readonly).
*/
static u_int64_t counter; /* counter for ipfw_report(NULL...) */
struct ipfw_flow_id last_pkt ;
#define IPFW_DEFAULT_RULE ((u_int)(u_short)~0)
LIST_HEAD (ip_fw_head, ip_fw) ip_fw_chain_head;
MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's");
#ifdef SYSCTL_NODE
SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, enable, CTLFLAG_RW,
&fw_enable, 0, "Enable ipfw");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO,one_pass,CTLFLAG_RW,
&fw_one_pass, 0,
"Only do a single pass through ipfw when using dummynet(4)");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW,
&fw_debug, 0, "Enable printing of debug ip_fw statements");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW,
&fw_verbose, 0, "Log matches to ipfw rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW,
&fw_verbose_limit, 0, "Set upper limit of matches of ipfw rules logged");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, permanent_rules, CTLFLAG_RW,
&fw_permanent_rules, 0, "Set rule number, below which rules are permanent");
/*
* Extension for stateful ipfw.
*
* 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, it is first hashed, then matched
* against the entries in the corresponding list.
* Matching occurs according to the rule type. The default is to
* match the four fields and the protocol, and rules are bidirectional.
*
* For a busy proxy/web server we will have lots of connections to
* the server. We could decide for a rule type where we ignore
* ports (different hashing) and avoid special SYN/RST/FIN handling.
*
* XXX when we decide to support more than one rule type, we should
* repeat the hashing multiple times uing only the useful fields.
* Or, we could run the various tests in parallel, because the
* 'move to front' technique should shorten the average search.
*
* 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 rules 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.
* 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 struct ipfw_dyn_rule **ipfw_dyn_v = NULL ;
static u_int32_t dyn_buckets = 256 ; /* must be power of 2 */
static u_int32_t curr_dyn_buckets = 256 ; /* must be power of 2 */
/**
* timeouts for various events in handing dynamic rules.
*/
static u_int32_t dyn_ack_lifetime = 300 ;
static u_int32_t dyn_syn_lifetime = 20 ;
static u_int32_t dyn_fin_lifetime = 1 ;
static u_int32_t dyn_rst_lifetime = 1 ;
static u_int32_t dyn_udp_lifetime = 10 ;
static u_int32_t dyn_short_lifetime = 5 ;
/*
* after reaching 0, dynamic rules are considered still valid for
* an additional grace time, unless there is lack of resources.
*/
static u_int32_t dyn_grace_time = 10 ;
static u_int32_t static_count = 0 ; /* # of static rules */
static u_int32_t dyn_count = 0 ; /* # of dynamic rules */
static u_int32_t dyn_max = 1000 ; /* max # of dynamic rules */
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_buckets, CTLFLAG_RW,
&dyn_buckets, 0, "Number of dyn. buckets");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, curr_dyn_buckets, CTLFLAG_RD,
&curr_dyn_buckets, 0, "Current Number of dyn. buckets");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_count, CTLFLAG_RD,
&dyn_count, 0, "Number of dyn. rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_max, CTLFLAG_RW,
&dyn_max, 0, "Max number of dyn. rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, static_count, CTLFLAG_RD,
&static_count, 0, "Number of static rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_ack_lifetime, CTLFLAG_RW,
&dyn_ack_lifetime, 0, "Lifetime of dyn. rules for acks");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_syn_lifetime, CTLFLAG_RW,
&dyn_syn_lifetime, 0, "Lifetime of dyn. rules for syn");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_fin_lifetime, CTLFLAG_RW,
&dyn_fin_lifetime, 0, "Lifetime of dyn. rules for fin");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_rst_lifetime, CTLFLAG_RW,
&dyn_rst_lifetime, 0, "Lifetime of dyn. rules for rst");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_udp_lifetime, CTLFLAG_RW,
&dyn_udp_lifetime, 0, "Lifetime of dyn. rules for UDP");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_short_lifetime, CTLFLAG_RW,
&dyn_short_lifetime, 0, "Lifetime of dyn. rules for other situations");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, dyn_grace_time, CTLFLAG_RD,
&dyn_grace_time, 0, "Grace time for dyn. rules");
#endif
#define dprintf(a) do { \
if (fw_debug) \
printf a; \
} while (0)
#define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0
static int add_entry (struct ip_fw_head *chainptr, struct ip_fw *frwl);
static int del_entry (struct ip_fw_head *chainptr, u_short number);
static int zero_entry (struct ip_fw *, int);
static int check_ipfw_struct (struct ip_fw *m);
static int iface_match (struct ifnet *ifp, union ip_fw_if *ifu,
int byname);
static int ipopts_match (struct ip *ip, struct ip_fw *f);
static int iptos_match (struct ip *ip, struct ip_fw *f);
static __inline int
port_match (u_short *portptr, int nports, u_short port,
int range_flag, int mask);
static int tcpflg_match (struct tcphdr *tcp, struct ip_fw *f);
static int icmptype_match (struct icmp * icmp, struct ip_fw * f);
static void ipfw_report (struct ip_fw *f, struct ip *ip, int offset,
int ip_len, struct ifnet *rif,
struct ifnet *oif);
static void flush_rule_ptrs(void);
static int ip_fw_chk (struct ip **pip, int hlen,
struct ifnet *oif, u_int16_t *cookie, struct mbuf **m,
struct ip_fw **flow_id,
struct sockaddr_in **next_hop);
static int ip_fw_ctl (struct sockopt *sopt);
static char err_prefix[] = "ip_fw_ctl:";
/*
* Returns 1 if the port is matched by the vector, 0 otherwise
*/
static __inline int
port_match(u_short *portptr, int nports, u_short port, int range_flag, int mask)
{
if (!nports)
return 1;
if (mask) {
if ( 0 == ((portptr[0] ^ port) & portptr[1]) )
return 1;
nports -= 2;
portptr += 2;
}
if (range_flag) {
if (portptr[0] <= port && port <= portptr[1])
return 1;
nports -= 2;
portptr += 2;
}
while (nports-- > 0)
if (*portptr++ == port)
return 1;
return 0;
}
static int
tcpflg_match(struct tcphdr *tcp, struct ip_fw *f)
{
u_char flg_set, flg_clr;
/*
* If an established connection is required, reject packets that
* have only SYN of RST|ACK|SYN set. Otherwise, fall through to
* other flag requirements.
*/
if ((f->fw_ipflg & IP_FW_IF_TCPEST) &&
((tcp->th_flags & (IP_FW_TCPF_RST | IP_FW_TCPF_ACK |
IP_FW_TCPF_SYN)) == IP_FW_TCPF_SYN))
return 0;
flg_set = tcp->th_flags & f->fw_tcpf;
flg_clr = tcp->th_flags & f->fw_tcpnf;
if (flg_set != f->fw_tcpf)
return 0;
if (flg_clr)
return 0;
return 1;
}
static int
icmptype_match(struct icmp *icmp, struct ip_fw *f)
{
int type;
if (!(f->fw_flg & IP_FW_F_ICMPBIT))
return(1);
type = icmp->icmp_type;
/* check for matching type in the bitmap */
if (type < IP_FW_ICMPTYPES_MAX &&
(f->fw_uar.fw_icmptypes[type / (sizeof(unsigned) * NBBY)] &
(1U << (type % (sizeof(unsigned) * NBBY)))))
return(1);
return(0); /* no match */
}
static int
is_icmp_query(struct ip *ip)
{
const struct icmp *icmp;
int icmp_type;
icmp = (struct icmp *)((u_int32_t *)ip + ip->ip_hl);
icmp_type = icmp->icmp_type;
if (icmp_type == ICMP_ECHO || icmp_type == ICMP_ROUTERSOLICIT ||
icmp_type == ICMP_TSTAMP || icmp_type == ICMP_IREQ ||
icmp_type == ICMP_MASKREQ)
return(1);
return(0);
}
static int
ipopts_match(struct ip *ip, struct ip_fw *f)
{
register u_char *cp;
int opt, optlen, cnt;
u_char opts, nopts, nopts_sve;
cp = (u_char *)(ip + 1);
cnt = (ip->ip_hl << 2) - sizeof (struct ip);
opts = f->fw_ipopt;
nopts = nopts_sve = f->fw_ipnopt;
for (; cnt > 0; cnt -= optlen, cp += optlen) {
opt = cp[IPOPT_OPTVAL];
if (opt == IPOPT_EOL)
break;
if (opt == IPOPT_NOP)
optlen = 1;
else {
optlen = cp[IPOPT_OLEN];
if (optlen <= 0 || optlen > cnt) {
return 0; /*XXX*/
}
}
switch (opt) {
default:
break;
case IPOPT_LSRR:
opts &= ~IP_FW_IPOPT_LSRR;
nopts &= ~IP_FW_IPOPT_LSRR;
break;
case IPOPT_SSRR:
opts &= ~IP_FW_IPOPT_SSRR;
nopts &= ~IP_FW_IPOPT_SSRR;
break;
case IPOPT_RR:
opts &= ~IP_FW_IPOPT_RR;
nopts &= ~IP_FW_IPOPT_RR;
break;
case IPOPT_TS:
opts &= ~IP_FW_IPOPT_TS;
nopts &= ~IP_FW_IPOPT_TS;
break;
}
if (opts == nopts)
break;
}
if (opts == 0 && nopts == nopts_sve)
return 1;
else
return 0;
}
static int
iptos_match(struct ip *ip, struct ip_fw *f)
{
u_int flags = (ip->ip_tos & 0x1f);
u_char opts, nopts, nopts_sve;
opts = f->fw_iptos;
nopts = nopts_sve = f->fw_ipntos;
while (flags != 0) {
u_int flag;
flag = 1 << (ffs(flags) -1);
opts &= ~flag;
nopts &= ~flag;
flags &= ~flag;
}
if (opts == 0 && nopts == nopts_sve)
return 1;
else
return 0;
}
static int
tcpopts_match(struct tcphdr *tcp, struct ip_fw *f)
{
register u_char *cp;
int opt, optlen, cnt;
u_char opts, nopts, nopts_sve;
cp = (u_char *)(tcp + 1);
cnt = (tcp->th_off << 2) - sizeof (struct tcphdr);
opts = f->fw_tcpopt;
nopts = nopts_sve = f->fw_tcpnopt;
for (; cnt > 0; cnt -= optlen, cp += optlen) {
opt = cp[0];
if (opt == TCPOPT_EOL)
break;
if (opt == TCPOPT_NOP)
optlen = 1;
else {
optlen = cp[1];
if (optlen <= 0)
break;
}
switch (opt) {
default:
break;
case TCPOPT_MAXSEG:
opts &= ~IP_FW_TCPOPT_MSS;
nopts &= ~IP_FW_TCPOPT_MSS;
break;
case TCPOPT_WINDOW:
opts &= ~IP_FW_TCPOPT_WINDOW;
nopts &= ~IP_FW_TCPOPT_WINDOW;
break;
case TCPOPT_SACK_PERMITTED:
case TCPOPT_SACK:
opts &= ~IP_FW_TCPOPT_SACK;
nopts &= ~IP_FW_TCPOPT_SACK;
break;
case TCPOPT_TIMESTAMP:
opts &= ~IP_FW_TCPOPT_TS;
nopts &= ~IP_FW_TCPOPT_TS;
break;
case TCPOPT_CC:
case TCPOPT_CCNEW:
case TCPOPT_CCECHO:
opts &= ~IP_FW_TCPOPT_CC;
nopts &= ~IP_FW_TCPOPT_CC;
break;
}
if (opts == nopts)
break;
}
if (opts == 0 && nopts == nopts_sve)
return 1;
else
return 0;
}
static int
iface_match(struct ifnet *ifp, union ip_fw_if *ifu, int byname)
{
/* Check by name or by IP address */
if (byname) {
/* Check unit number (-1 is wildcard) */
if (ifu->fu_via_if.unit != -1
&& ifp->if_unit != ifu->fu_via_if.unit)
return(0);
/* Check name */
if (strncmp(ifp->if_name, ifu->fu_via_if.name, FW_IFNLEN))
return(0);
return(1);
} else if (ifu->fu_via_ip.s_addr != 0) { /* Zero == wildcard */
struct ifaddr *ia;
TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) {
if (ia->ifa_addr == NULL)
continue;
if (ia->ifa_addr->sa_family != AF_INET)
continue;
if (ifu->fu_via_ip.s_addr != ((struct sockaddr_in *)
(ia->ifa_addr))->sin_addr.s_addr)
continue;
return(1);
}
return(0);
}
return(1);
}
static void
ipfw_report(struct ip_fw *f, struct ip *ip, int offset, int ip_len,
struct ifnet *rif, struct ifnet *oif)
{
struct tcphdr *const tcp = (struct tcphdr *) ((u_int32_t *) ip+ ip->ip_hl);
struct udphdr *const udp = (struct udphdr *) ((u_int32_t *) ip+ ip->ip_hl);
struct icmp *const icmp = (struct icmp *) ((u_int32_t *) ip + ip->ip_hl);
u_int64_t count;
char *action;
char action2[32], proto[47], name[18], fragment[27];
int len;
count = f ? f->fw_pcnt : ++counter;
if ((f == NULL && fw_verbose_limit != 0 && count > fw_verbose_limit) ||
(f && f->fw_logamount != 0 && count > f->fw_loghighest))
return;
/* Print command name */
snprintf(SNPARGS(name, 0), "ipfw: %d", f ? f->fw_number : -1);
action = action2;
if (!f)
action = "Refuse";
else {
switch (f->fw_flg & IP_FW_F_COMMAND) {
case IP_FW_F_DENY:
action = "Deny";
break;
case IP_FW_F_REJECT:
if (f->fw_reject_code == IP_FW_REJECT_RST)
action = "Reset";
else
action = "Unreach";
break;
case IP_FW_F_ACCEPT:
action = "Accept";
break;
case IP_FW_F_COUNT:
action = "Count";
break;
#ifdef IPDIVERT
case IP_FW_F_DIVERT:
snprintf(SNPARGS(action2, 0), "Divert %d",
f->fw_divert_port);
break;
case IP_FW_F_TEE:
snprintf(SNPARGS(action2, 0), "Tee %d",
f->fw_divert_port);
break;
#endif
case IP_FW_F_SKIPTO:
snprintf(SNPARGS(action2, 0), "SkipTo %d",
f->fw_skipto_rule);
break;
#ifdef DUMMYNET
case IP_FW_F_PIPE:
snprintf(SNPARGS(action2, 0), "Pipe %d",
f->fw_skipto_rule);
break;
case IP_FW_F_QUEUE:
snprintf(SNPARGS(action2, 0), "Queue %d",
f->fw_skipto_rule);
break;
#endif
#ifdef IPFIREWALL_FORWARD
case IP_FW_F_FWD:
if (f->fw_fwd_ip.sin_port)
snprintf(SNPARGS(action2, 0),
"Forward to %s:%d",
inet_ntoa(f->fw_fwd_ip.sin_addr),
f->fw_fwd_ip.sin_port);
else
snprintf(SNPARGS(action2, 0), "Forward to %s",
inet_ntoa(f->fw_fwd_ip.sin_addr));
break;
#endif
default:
action = "UNKNOWN";
break;
}
}
switch (ip->ip_p) {
case IPPROTO_TCP:
len = snprintf(SNPARGS(proto, 0), "TCP %s",
inet_ntoa(ip->ip_src));
if (offset == 0)
len += snprintf(SNPARGS(proto, len), ":%d ",
ntohs(tcp->th_sport));
else
len += snprintf(SNPARGS(proto, len), " ");
len += snprintf(SNPARGS(proto, len), "%s",
inet_ntoa(ip->ip_dst));
if (offset == 0)
snprintf(SNPARGS(proto, len), ":%d",
ntohs(tcp->th_dport));
break;
case IPPROTO_UDP:
len = snprintf(SNPARGS(proto, 0), "UDP %s",
inet_ntoa(ip->ip_src));
if (offset == 0)
len += snprintf(SNPARGS(proto, len), ":%d ",
ntohs(udp->uh_sport));
else
len += snprintf(SNPARGS(proto, len), " ");
len += snprintf(SNPARGS(proto, len), "%s",
inet_ntoa(ip->ip_dst));
if (offset == 0)
snprintf(SNPARGS(proto, len), ":%d",
ntohs(udp->uh_dport));
break;
case IPPROTO_ICMP:
if (offset == 0)
len = snprintf(SNPARGS(proto, 0), "ICMP:%u.%u ",
icmp->icmp_type, icmp->icmp_code);
else
len = snprintf(SNPARGS(proto, 0), "ICMP ");
len += snprintf(SNPARGS(proto, len), "%s",
inet_ntoa(ip->ip_src));
snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst));
break;
default:
len = snprintf(SNPARGS(proto, 0), "P:%d %s", ip->ip_p,
inet_ntoa(ip->ip_src));
snprintf(SNPARGS(proto, len), " %s", inet_ntoa(ip->ip_dst));
break;
}
if (ip->ip_off & (IP_MF | IP_OFFMASK))
snprintf(SNPARGS(fragment, 0), " (frag %d:%d@%d%s)",
ntohs(ip->ip_id), ip_len - (ip->ip_hl << 2),
offset << 3,
(ip->ip_off & IP_MF) ? "+" : "");
else
fragment[0] = '\0';
if (oif)
log(LOG_SECURITY | LOG_INFO, "%s %s %s out via %s%d%s\n",
name, action, proto, oif->if_name, oif->if_unit, fragment);
else if (rif)
log(LOG_SECURITY | LOG_INFO, "%s %s %s in via %s%d%s\n", name,
action, proto, rif->if_name, rif->if_unit, fragment);
else
log(LOG_SECURITY | LOG_INFO, "%s %s %s%s\n", name, action,
proto, fragment);
if ((f ? f->fw_logamount != 0 : 1) &&
count == (f ? f->fw_loghighest : fw_verbose_limit))
log(LOG_SECURITY | LOG_NOTICE,
"ipfw: limit %d reached on entry %d\n",
f ? f->fw_logamount : fw_verbose_limit,
f ? f->fw_number : -1);
}
static __inline int
hash_packet(struct ipfw_flow_id *id)
{
u_int32_t i ;
i = (id->dst_ip) ^ (id->src_ip) ^ (id->dst_port) ^ (id->src_port);
i &= (curr_dyn_buckets - 1) ;
return i ;
}
/**
* 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) { \
struct ipfw_dyn_rule *old_q = q; \
\
/* remove a refcount to the parent */ \
if (q->dyn_type == DYN_LIMIT) \
q->parent->count--; \
DEB(printf("-- unlink entry 0x%08x %d -> 0x%08x %d, %d left\n", \
(q->id.src_ip), (q->id.src_port), \
(q->id.dst_ip), (q->id.dst_port), dyn_count-1 ); ) \
if (prev != NULL) \
prev->next = q = q->next ; \
else \
ipfw_dyn_v[i] = q = q->next ; \
dyn_count-- ; \
free(old_q, M_IPFW); }
#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
/**
* Remove all dynamic rules pointing to a given rule, or all
* rules if rule == NULL. Second parameter is 1 if we want to
* delete unconditionally, otherwise only expired rules are removed.
*/
static void
remove_dyn_rule(struct ip_fw *rule, int force)
{
struct ipfw_dyn_rule *prev, *q;
int i, pass, max_pass ;
static u_int32_t last_remove = 0 ;
if (ipfw_dyn_v == NULL || dyn_count == 0)
return ;
/* do not expire more than once per second, it is useless */
if (force == 0 && last_remove == time_second)
return ;
last_remove = time_second ;
/*
* because DYN_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.
*/
for (pass = max_pass = 0; pass <= max_pass ; pass++ ) {
for (i = 0 ; i < curr_dyn_buckets ; i++) {
for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) {
/*
* logic can become complex here, so we split tests.
* First, test if we match any rule,
* then make sure the rule is expired or we want to kill it,
* and possibly more in the future.
*/
int zap = ( rule == NULL || rule == q->rule);
if (zap)
zap = force || TIME_LEQ( q->expire , time_second );
/* do not zap parent in first pass, record we need a second pass */
if (q->dyn_type == DYN_LIMIT_PARENT) {
max_pass = 1; /* we need a second pass */
if (zap == 1 && (pass == 0 || q->count != 0) ) {
zap = 0 ;
if (q->count != 0)
printf("cannot remove parent, count %d\n", q->count);
}
}
if (zap) {
UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
} else {
prev = q ;
q = q->next ;
}
}
}
}
}
#define EXPIRE_DYN_CHAIN(rule) remove_dyn_rule(rule, 0 /* expired ones */)
#define EXPIRE_DYN_CHAINS() remove_dyn_rule(NULL, 0 /* expired ones */)
#define DELETE_DYN_CHAIN(rule) remove_dyn_rule(rule, 1 /* force removal */)
#define DELETE_DYN_CHAINS() remove_dyn_rule(NULL, 1 /* force removal */)
/**
* lookup a dynamic rule.
*/
static struct ipfw_dyn_rule *
lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction)
{
/*
* stateful ipfw extensions.
* Lookup into dynamic session queue
*/
struct ipfw_dyn_rule *prev, *q ;
int i, dir = 0;
#define MATCH_FORWARD 1
if (ipfw_dyn_v == NULL)
return NULL ;
i = hash_packet( pkt );
for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) {
if (q->dyn_type == DYN_LIMIT_PARENT)
goto next;
if (TIME_LEQ( q->expire , time_second ) ) { /* expire entry */
UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
continue ;
}
if ( pkt->proto == q->id.proto) {
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 ;
goto found ;
}
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 = 0 ; /* reverse match */
goto found ;
}
}
next:
prev = q ;
q = q->next ;
}
return NULL ; /* clearly not found */
found:
if ( prev != NULL) { /* found and not in front */
prev->next = q->next ;
q->next = ipfw_dyn_v[i] ;
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);
q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8);
switch (q->state) {
case TH_SYN :
/* opening */
q->expire = time_second + dyn_syn_lifetime ;
break ;
case TH_SYN | (TH_SYN << 8) :
/* move to established */
q->expire = time_second + dyn_ack_lifetime ;
break ;
case TH_SYN | (TH_SYN << 8) | TH_FIN :
case TH_SYN | (TH_SYN << 8) | (TH_FIN << 8) :
/* one side tries to close */
q->expire = time_second + dyn_ack_lifetime ;
break ;
case TH_SYN | (TH_SYN << 8) | TH_FIN | (TH_FIN << 8) :
/* both sides closed */
q->expire = time_second + 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
q->expire = time_second + dyn_rst_lifetime ;
break ;
}
} else if (pkt->proto == IPPROTO_UDP) {
q->expire = time_second + dyn_udp_lifetime ;
} else {
/* other protocols */
q->expire = time_second + dyn_short_lifetime ;
}
if (match_direction)
*match_direction = dir ;
return q ;
}
/**
* Install state of type 'type' for a dynamic session.
* The hash table contains two type of rules:
* - regular rules (DYN_KEEP_STATE)
* - rules for sessions with limited number of sess per user
* (DYN_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 (DYN_LIMIT_PARENT).
*/
static struct ipfw_dyn_rule *
add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule)
{
struct ipfw_dyn_rule *r ;
int i ;
if (ipfw_dyn_v == NULL ||
(dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) {
/* try reallocation, make sure we have a power of 2 */
u_int32_t i = dyn_buckets ;
while ( i > 0 && (i & 1) == 0 )
i >>= 1 ;
if (i != 1) /* not a power of 2 */
dyn_buckets = curr_dyn_buckets ; /* reset */
else {
curr_dyn_buckets = dyn_buckets ;
if (ipfw_dyn_v != NULL)
free(ipfw_dyn_v, M_IPFW);
ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof r,
M_IPFW, M_DONTWAIT | M_ZERO);
if (ipfw_dyn_v == NULL)
return NULL; /* failed ! */
}
}
i = hash_packet(id);
r = malloc(sizeof *r, M_IPFW, M_DONTWAIT | M_ZERO);
if (r == NULL) {
printf ("sorry cannot allocate state\n");
return NULL ;
}
/* increase refcount on parent, and set pointer */
if (dyn_type == DYN_LIMIT) {
struct ipfw_dyn_rule *parent = (struct ipfw_dyn_rule *)rule;
if ( parent->dyn_type != DYN_LIMIT_PARENT)
panic("invalid parent");
parent->count++ ;
r->parent = parent ;
rule = parent->rule;
}
r->id = *id ;
r->expire = time_second + dyn_syn_lifetime ;
r->rule = rule ;
r->dyn_type = dyn_type ;
r->pcnt = r->bcnt = 0 ;
r->count = 0 ;
r->bucket = i ;
r->next = ipfw_dyn_v[i] ;
ipfw_dyn_v[i] = r ;
dyn_count++ ;
DEB(printf("-- add entry 0x%08x %d -> 0x%08x %d, total %d\n",
(r->id.src_ip), (r->id.src_port),
(r->id.dst_ip), (r->id.dst_port),
dyn_count ); )
return r;
}
/**
* lookup dynamic parent rule using pkt and chain as search keys.
* If the lookup fails, then install one.
*/
static struct ipfw_dyn_rule *
lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule)
{
struct ipfw_dyn_rule *q;
int i;
if (ipfw_dyn_v) {
i = hash_packet( pkt );
for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next)
if (q->dyn_type == DYN_LIMIT_PARENT && rule == q->rule &&
pkt->proto == q->id.proto &&
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) {
q->expire = time_second + dyn_short_lifetime ;
DEB(printf("lookup_dyn_parent found 0x%p\n", q);)
return q;
}
}
return add_dyn_rule(pkt, DYN_LIMIT_PARENT, rule);
}
/*
* Install dynamic state.
* There are different types of dynamic rules which can be installed.
* The type is in rule->dyn_type.
* Type 0 (default) is a bidirectional rule
*
* Returns 1 (failure) if state is not installed because of errors or because
* session limitations are enforced.
*/
static int
install_state(struct ip_fw *rule)
{
struct ipfw_dyn_rule *q ;
static int last_log ;
u_int8_t type = rule->dyn_type ;
DEB(printf("-- install state type %d 0x%08x %u -> 0x%08x %u\n",
type,
(last_pkt.src_ip), (last_pkt.src_port),
(last_pkt.dst_ip), (last_pkt.dst_port) );)
q = lookup_dyn_rule(&last_pkt, NULL) ;
if (q != NULL) { /* should never occur */
if (last_log != time_second) {
last_log = time_second ;
printf(" entry already present, done\n");
}
return 0 ;
}
if (dyn_count >= dyn_max) /* try remove old ones... */
EXPIRE_DYN_CHAINS();
if (dyn_count >= dyn_max) {
if (last_log != time_second) {
last_log = time_second ;
printf(" Too many dynamic rules, sorry\n");
}
return 1; /* cannot install, notify caller */
}
switch (type) {
case DYN_KEEP_STATE: /* bidir rule */
add_dyn_rule(&last_pkt, DYN_KEEP_STATE, rule);
break ;
case DYN_LIMIT: /* limit number of sessions */
{
u_int16_t limit_mask = rule->limit_mask ;
u_int16_t conn_limit = rule->conn_limit ;
struct ipfw_flow_id id;
struct ipfw_dyn_rule *parent;
DEB(printf("installing dyn-limit rule %d\n", conn_limit);)
id.dst_ip = id.src_ip = 0;
id.dst_port = id.src_port = 0 ;
id.proto = last_pkt.proto ;
if (limit_mask & DYN_SRC_ADDR)
id.src_ip = last_pkt.src_ip;
if (limit_mask & DYN_DST_ADDR)
id.dst_ip = last_pkt.dst_ip;
if (limit_mask & DYN_SRC_PORT)
id.src_port = last_pkt.src_port;
if (limit_mask & DYN_DST_PORT)
id.dst_port = last_pkt.dst_port;
parent = lookup_dyn_parent(&id, rule);
if (parent == NULL) {
printf("add parent failed\n");
return 1;
}
if (parent->count >= conn_limit) {
EXPIRE_DYN_CHAIN(rule); /* try to expire some */
if (parent->count >= conn_limit) {
printf("drop session, too many entries\n");
return 1;
}
}
add_dyn_rule(&last_pkt, DYN_LIMIT, (struct ip_fw *)parent);
}
break ;
default:
printf("unknown dynamic rule type %u\n", type);
return 1 ;
}
lookup_dyn_rule(&last_pkt, NULL) ; /* XXX just set the lifetime */
return 0;
}
/*
* given an ip_fw *, lookup_next_rule will return a pointer
* of the same type to the next one. This can be either the jump
* target (for skipto instructions) or the next one in the chain (in
* all other cases including a missing jump target).
* Backward jumps are not allowed, so start looking from the next
* rule...
*/
static struct ip_fw * lookup_next_rule(struct ip_fw *me);
static struct ip_fw *
lookup_next_rule(struct ip_fw *me)
{
struct ip_fw *rule ;
int rulenum = me->fw_skipto_rule ; /* guess... */
if ( (me->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_SKIPTO )
for (rule = LIST_NEXT(me,next); rule ; rule = LIST_NEXT(rule,next))
if (rule->fw_number >= rulenum)
return rule ;
return LIST_NEXT(me,next) ; /* failure or not a skipto */
}
/*
* Parameters:
*
* pip Pointer to packet header (struct ip **)
* hlen Packet header length
* oif Outgoing interface, or NULL if packet is incoming
* *cookie Skip up to the first rule past this rule number;
* upon return, non-zero port number for divert or tee.
* Special case: cookie == NULL on input for bridging.
* *m The packet; we set to NULL when/if we nuke it.
* *flow_id pointer to the last matching rule (in/out)
* *next_hop socket we are forwarding to (in/out).
*
* Return value:
*
* IP_FW_PORT_DENY_FLAG the packet must be dropped.
* 0 The packet is to be accepted and routed normally OR
* the packet was denied/rejected and has been dropped;
* in the latter case, *m is equal to NULL upon return.
* port Divert the packet to port, with these caveats:
*
* - If IP_FW_PORT_TEE_FLAG is set, tee the packet instead
* of diverting it (ie, 'ipfw tee').
*
* - If IP_FW_PORT_DYNT_FLAG is set, interpret the lower
* 16 bits as a dummynet pipe number instead of diverting
*/
static int
ip_fw_chk(struct ip **pip, int hlen,
struct ifnet *oif, u_int16_t *cookie, struct mbuf **m,
struct ip_fw **flow_id,
struct sockaddr_in **next_hop)
{
struct ip_fw *f = NULL; /* matching rule */
struct ip *ip = *pip;
struct ifnet *const rif = (*m)->m_pkthdr.rcvif;
struct ifnet *tif;
u_short offset = 0 ;
u_short src_port = 0, dst_port = 0;
struct in_addr src_ip, dst_ip; /* XXX */
u_int8_t proto= 0, flags = 0 ; /* XXX */
u_int16_t skipto, bridgeCookie;
u_int16_t ip_len;
int dyn_checked = 0 ; /* set after dyn.rules have been checked. */
int direction = MATCH_FORWARD ; /* dirty trick... */
struct ipfw_dyn_rule *q = NULL ;
/* Special hack for bridging (as usual) */
if (cookie == NULL) {
bridgeCookie = 0;
cookie = &bridgeCookie;
#define BRIDGED (cookie == &bridgeCookie)
hlen = ip->ip_hl << 2;
}
/* Grab and reset cookie */
skipto = *cookie;
*cookie = 0;
#define PULLUP_TO(len) do { \
if ((*m)->m_len < (len)) { \
ip = NULL ; \
if ((*m = m_pullup(*m, (len))) == 0) \
goto bogusfrag; \
ip = mtod(*m, struct ip *); \
*pip = ip; \
} \
} while (0)
/*
* Collect parameters into local variables for faster matching.
*/
proto = ip->ip_p;
src_ip = ip->ip_src;
dst_ip = ip->ip_dst;
if (0 && BRIDGED) { /* not yet... */
offset = (ntohs(ip->ip_off) & IP_OFFMASK);
ip_len = ntohs(ip->ip_len);
} else {
offset = (ip->ip_off & IP_OFFMASK);
ip_len = ip->ip_len;
}
if (offset == 0) {
switch (proto) {
case IPPROTO_TCP : {
struct tcphdr *tcp;
PULLUP_TO(hlen + sizeof(struct tcphdr));
tcp =(struct tcphdr *)((u_int32_t *)ip + ip->ip_hl);
dst_port = tcp->th_dport ;
src_port = tcp->th_sport ;
flags = tcp->th_flags ;
}
break ;
case IPPROTO_UDP : {
struct udphdr *udp;
PULLUP_TO(hlen + sizeof(struct udphdr));
udp =(struct udphdr *)((u_int32_t *)ip + ip->ip_hl);
dst_port = udp->uh_dport ;
src_port = udp->uh_sport ;
}
break;
case IPPROTO_ICMP:
PULLUP_TO(hlen + 4); /* type, code and checksum. */
flags = ((struct icmp *)
((u_int32_t *)ip + ip->ip_hl))->icmp_type ;
break ;
default :
break;
}
}
#undef PULLUP_TO
last_pkt.src_ip = ntohl(src_ip.s_addr);
last_pkt.dst_ip = ntohl(dst_ip.s_addr);
last_pkt.proto = proto;
last_pkt.src_port = ntohs(src_port);
last_pkt.dst_port = ntohs(dst_port);
last_pkt.flags = flags;
if (*flow_id) {
/*
* Packet has already been tagged. Look for the next rule
* to restart processing.
*/
if (fw_one_pass) /* just accept if fw_one_pass is set */
return 0;
f = (*flow_id)->next_rule_ptr ;
if (f == NULL)
f = (*flow_id)->next_rule_ptr = lookup_next_rule(*flow_id);
if (f == NULL)
goto dropit;
} else {
/*
* Go down the chain, looking for enlightment.
* If we've been asked to start at a given rule, do so.
*/
f = LIST_FIRST(&ip_fw_chain_head);
if (skipto != 0) {
if (skipto >= IPFW_DEFAULT_RULE)
goto dropit;
while (f && f->fw_number <= skipto)
f = LIST_NEXT(f, next);
if (f == NULL)
goto dropit;
}
}
for (; f; f = LIST_NEXT(f, next)) {
again:
if (f->fw_number == IPFW_DEFAULT_RULE)
goto got_match ;
/*
* dynamic rules are checked at the first keep-state or
* check-state occurrence.
*/
if (f->fw_flg & (IP_FW_F_KEEP_S|IP_FW_F_CHECK_S) &&
dyn_checked == 0 ) {
dyn_checked = 1 ;
q = lookup_dyn_rule(&last_pkt, &direction);
if (q != NULL) {
DEB(printf("-- dynamic match 0x%08x %d %s 0x%08x %d\n",
(q->id.src_ip), (q->id.src_port),
(direction == MATCH_FORWARD ? "-->" : "<--"),
(q->id.dst_ip), (q->id.dst_port) ); )
f = q->rule ;
q->pcnt++ ;
q->bcnt += ip_len;
goto got_match ; /* random not allowed here */
}
/* if this was a check-only rule, continue with next */
if (f->fw_flg & IP_FW_F_CHECK_S)
continue ;
}
/* Check if rule only valid for bridged packets */
if ((f->fw_flg & IP_FW_BRIDGED) != 0 && !(BRIDGED))
continue;
if (oif) {
/* Check direction outbound */
if (!(f->fw_flg & IP_FW_F_OUT))
continue;
} else {
/* Check direction inbound */
if (!(f->fw_flg & IP_FW_F_IN))
continue;
}
/* Fragments */
if ((f->fw_flg & IP_FW_F_FRAG) && offset == 0 )
continue;
if (f->fw_flg & IP_FW_F_SME) {
INADDR_TO_IFP(src_ip, tif);
if (tif == NULL)
continue;
}
if (f->fw_flg & IP_FW_F_DME) {
INADDR_TO_IFP(dst_ip, tif);
if (tif == NULL)
continue;
}
/* If src-addr doesn't match, not this rule. */
if (((f->fw_flg & IP_FW_F_INVSRC) != 0) ^ ((src_ip.s_addr
& f->fw_smsk.s_addr) != f->fw_src.s_addr))
continue;
/* If dest-addr doesn't match, not this rule. */
if (((f->fw_flg & IP_FW_F_INVDST) != 0) ^ ((dst_ip.s_addr
& f->fw_dmsk.s_addr) != f->fw_dst.s_addr))
continue;
/* Interface check */
if ((f->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) {
struct ifnet *const iface = oif ? oif : rif;
/* Backwards compatibility hack for "via" */
if (!iface || !iface_match(iface,
&f->fw_in_if, f->fw_flg & IP_FW_F_OIFNAME))
continue;
} else {
/* Check receive interface */
if ((f->fw_flg & IP_FW_F_IIFACE)
&& (!rif || !iface_match(rif,
&f->fw_in_if, f->fw_flg & IP_FW_F_IIFNAME)))
continue;
/* Check outgoing interface */
if ((f->fw_flg & IP_FW_F_OIFACE)
&& (!oif || !iface_match(oif,
&f->fw_out_if, f->fw_flg & IP_FW_F_OIFNAME)))
continue;
}
/* Check IP header values */
if (f->fw_ipflg & IP_FW_IF_IPOPT && !ipopts_match(ip, f))
continue;
if (f->fw_ipflg & IP_FW_IF_IPLEN && f->fw_iplen != ip_len)
continue;
if (f->fw_ipflg & IP_FW_IF_IPID && f->fw_ipid != ntohs(ip->ip_id))
continue;
if (f->fw_ipflg & IP_FW_IF_IPTOS && !iptos_match(ip, f))
continue;
if (f->fw_ipflg & IP_FW_IF_IPTTL && f->fw_ipttl != ip->ip_ttl)
continue;
if (f->fw_ipflg & IP_FW_IF_IPVER && f->fw_ipver != ip->ip_v)
continue;
/* Check protocol; if wildcard, and no [ug]id, match */
if (f->fw_prot == IPPROTO_IP) {
if (!(f->fw_flg & (IP_FW_F_UID|IP_FW_F_GID)))
goto rnd_then_got_match;
} else
/* If different, don't match */
if (proto != f->fw_prot)
continue;
/* Protocol specific checks for uid only */
if (f->fw_flg & (IP_FW_F_UID|IP_FW_F_GID)) {
switch (proto) {
case IPPROTO_TCP:
{
struct inpcb *P;
if (offset == 1) /* cf. RFC 1858 */
goto bogusfrag;
if (offset != 0)
continue;
if (oif)
P = in_pcblookup_hash(&tcbinfo, dst_ip,
dst_port, src_ip, src_port, 0,
oif);
else
P = in_pcblookup_hash(&tcbinfo, src_ip,
src_port, dst_ip, dst_port, 0,
NULL);
if (P && P->inp_socket) {
if (f->fw_flg & IP_FW_F_UID) {
if (P->inp_socket->so_cred->cr_uid !=
f->fw_uid)
continue;
} else if (!groupmember(f->fw_gid,
P->inp_socket->so_cred))
continue;
} else
continue;
break;
}
case IPPROTO_UDP:
{
struct inpcb *P;
if (offset != 0)
continue;
if (oif)
P = in_pcblookup_hash(&udbinfo, dst_ip,
dst_port, src_ip, src_port, 1,
oif);
else
P = in_pcblookup_hash(&udbinfo, src_ip,
src_port, dst_ip, dst_port, 1,
NULL);
if (P && P->inp_socket) {
if (f->fw_flg & IP_FW_F_UID) {
if (P->inp_socket->so_cred->cr_uid !=
f->fw_uid)
continue;
} else if (!groupmember(f->fw_gid,
P->inp_socket->so_cred))
continue;
} else
continue;
break;
}
default:
continue;
}
}
/* Protocol specific checks */
switch (proto) {
case IPPROTO_TCP:
{
struct tcphdr *tcp;
if (offset == 1) /* cf. RFC 1858 */
goto bogusfrag;
if (offset != 0) {
/*
* TCP flags and ports aren't available in this
* packet -- if this rule specified either one,
* we consider the rule a non-match.
*/
if (IP_FW_HAVEPORTS(f) != 0 ||
f->fw_ipflg & IP_FW_IF_TCPMSK)
continue;
break;
}
tcp = (struct tcphdr *) ((u_int32_t *)ip + ip->ip_hl);
if (f->fw_ipflg & IP_FW_IF_TCPOPT && !tcpopts_match(tcp, f))
continue;
if (((f->fw_ipflg & IP_FW_IF_TCPFLG) ||
(f->fw_ipflg & IP_FW_IF_TCPEST)) &&
!tcpflg_match(tcp, f))
continue;
if (f->fw_ipflg & IP_FW_IF_TCPSEQ && tcp->th_seq != f->fw_tcpseq)
continue;
if (f->fw_ipflg & IP_FW_IF_TCPACK && tcp->th_ack != f->fw_tcpack)
continue;
if (f->fw_ipflg & IP_FW_IF_TCPWIN && tcp->th_win != f->fw_tcpwin)
continue;
goto check_ports;
}
case IPPROTO_UDP:
if (offset != 0) {
/*
* Port specification is unavailable -- if this
* rule specifies a port, we consider the rule
* a non-match.
*/
if (IP_FW_HAVEPORTS(f) )
continue;
break;
}
check_ports:
if (!port_match(&f->fw_uar.fw_pts[0],
IP_FW_GETNSRCP(f), ntohs(src_port),
f->fw_flg & IP_FW_F_SRNG,
f->fw_flg & IP_FW_F_SMSK))
continue;
if (!port_match(&f->fw_uar.fw_pts[IP_FW_GETNSRCP(f)],
IP_FW_GETNDSTP(f), ntohs(dst_port),
f->fw_flg & IP_FW_F_DRNG,
f->fw_flg & IP_FW_F_DMSK))
continue;
break;
case IPPROTO_ICMP:
{
struct icmp *icmp;
if (offset != 0) /* Type isn't valid */
break;
icmp = (struct icmp *) ((u_int32_t *)ip + ip->ip_hl);
if (!icmptype_match(icmp, f))
continue;
break;
}
default:
break;
bogusfrag:
if (fw_verbose && ip != NULL)
ipfw_report(NULL, ip, offset, ip_len, rif, oif);
goto dropit;
}
rnd_then_got_match:
if ( f->dont_match_prob && random() < f->dont_match_prob )
continue ;
got_match:
/*
* If not a dynamic match (q == NULL) and keep-state, install
* a new dynamic entry.
*/
if (q == NULL && f->fw_flg & IP_FW_F_KEEP_S) {
if (install_state(f)) /* error or limit violation */
goto dropit;
}
/* Update statistics */
f->fw_pcnt += 1;
f->fw_bcnt += ip_len;
f->timestamp = time_second;
/* Log to console if desired */
if ((f->fw_flg & IP_FW_F_PRN) && fw_verbose)
ipfw_report(f, ip, offset, ip_len, rif, oif);
/* Take appropriate action */
switch (f->fw_flg & IP_FW_F_COMMAND) {
case IP_FW_F_ACCEPT:
return(0);
case IP_FW_F_COUNT:
continue;
#ifdef IPDIVERT
case IP_FW_F_DIVERT:
*cookie = f->fw_number;
return(f->fw_divert_port);
case IP_FW_F_TEE:
*cookie = f->fw_number;
return(f->fw_divert_port | IP_FW_PORT_TEE_FLAG);
#endif
case IP_FW_F_SKIPTO: /* XXX check */
f = f->next_rule_ptr ? f->next_rule_ptr :
lookup_next_rule(f) ;
if (!f)
goto dropit;
goto again ;
#ifdef DUMMYNET
case IP_FW_F_PIPE:
case IP_FW_F_QUEUE:
*flow_id = f;
return(f->fw_pipe_nr | IP_FW_PORT_DYNT_FLAG);
#endif
#ifdef IPFIREWALL_FORWARD
case IP_FW_F_FWD:
/* Change the next-hop address for this packet.
* Initially we'll only worry about directly
* reachable next-hop's, but ultimately
* we will work out for next-hops that aren't
* direct the route we would take for it. We
* [cs]ould leave this latter problem to
* ip_output.c. We hope to high [name the abode of
* your favourite deity] that ip_output doesn't modify
* the new value of next_hop (which is dst there)
* XXX warning-- there is a dangerous reference here
* from next_hop to a field within the rule. If the
* rule is deleted, weird things might occur.
*/
if (next_hop != NULL /* Make sure, first... */
&& (q == NULL || direction == MATCH_FORWARD) )
*next_hop = &(f->fw_fwd_ip);
return(0); /* Allow the packet */
#endif
}
/* Deny/reject this packet using this rule */
break;
}
/* Rule IPFW_DEFAULT_RULE should always be there and match */
KASSERT(f != NULL, ("ip_fw: no chain"));
/*
* At this point, we're going to drop the packet.
* Send a reject notice if all of the following are true:
*
* - The packet matched a reject rule
* - The packet is not an ICMP packet, or is an ICMP query packet
* - The packet is not a multicast or broadcast packet
*/
if ((f->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_REJECT
&& (proto != IPPROTO_ICMP || is_icmp_query(ip))
&& !((*m)->m_flags & (M_BCAST|M_MCAST))
&& !IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
switch (f->fw_reject_code) {
case IP_FW_REJECT_RST:
{
/* XXX warning, this code writes into the mbuf */
struct tcphdr *const tcp =
(struct tcphdr *) ((u_int32_t *)ip + ip->ip_hl);
struct tcpiphdr ti, *const tip = (struct tcpiphdr *) ip;
if (offset != 0 || (tcp->th_flags & TH_RST))
break;
ti.ti_i = *((struct ipovly *) ip);
ti.ti_t = *tcp;
bcopy(&ti, ip, sizeof(ti));
NTOHL(tip->ti_seq);
NTOHL(tip->ti_ack);
tip->ti_len = ip_len - hlen - (tip->ti_off << 2);
if (tcp->th_flags & TH_ACK) {
tcp_respond(NULL, (void *)ip, tcp, *m,
(tcp_seq)0, tcp->th_ack, TH_RST);
} else {
if (tcp->th_flags & TH_SYN)
tip->ti_len++;
tcp_respond(NULL, (void *)ip, tcp, *m,
tip->ti_seq + tip->ti_len,
(tcp_seq)0, TH_RST|TH_ACK);
}
*m = NULL;
break;
}
default: /* Send an ICMP unreachable using code */
icmp_error(*m, ICMP_UNREACH,
f->fw_reject_code, 0L, 0);
*m = NULL;
break;
}
}
dropit:
/*
* Finally, drop the packet.
*/
return(IP_FW_PORT_DENY_FLAG);
#undef BRIDGED
}
/*
* when a rule is added/deleted, zero the direct pointers within
* all firewall rules. These will be reconstructed on the fly
* as packets are matched.
* Must be called at splnet().
*/
static void
flush_rule_ptrs()
{
struct ip_fw *fcp ;
LIST_FOREACH(fcp, &ip_fw_chain_head, next) {
fcp->next_rule_ptr = NULL ;
}
}
static int
add_entry(struct ip_fw_head *head, struct ip_fw *rule)
{
struct ip_fw *ftmp, *fcp, *fcpl;
u_short nbr = 0;
int s;
ftmp = malloc(sizeof *ftmp, M_IPFW, M_DONTWAIT | M_ZERO);
if (!ftmp)
return (ENOSPC);
bcopy(rule, ftmp, sizeof(*ftmp));
ftmp->fw_in_if.fu_via_if.name[FW_IFNLEN - 1] = '\0';
ftmp->fw_pcnt = 0L;
ftmp->fw_bcnt = 0L;
ftmp->next_rule_ptr = NULL ;
ftmp->pipe_ptr = NULL ;
s = splnet();
if (LIST_FIRST(head) == 0) {
LIST_INSERT_HEAD(head, ftmp, next);
goto done;
}
/* If entry number is 0, find highest numbered rule and add 100 */
if (ftmp->fw_number == 0) {
LIST_FOREACH(ftmp, head, next) {
if (ftmp->fw_number != IPFW_DEFAULT_RULE)
nbr = ftmp->fw_number;
else
break;
}
if (nbr < IPFW_DEFAULT_RULE - 100)
nbr += 100;
ftmp->fw_number = rule->fw_number = nbr;
}
/* Got a valid number; now insert it, keeping the list ordered */
fcpl = NULL ;
LIST_FOREACH(fcp, head, next) {
if (fcp->fw_number > ftmp->fw_number) {
if (fcpl) {
LIST_INSERT_AFTER(fcpl, ftmp, next);
} else {
LIST_INSERT_HEAD(head, ftmp, next);
}
break;
} else {
fcpl = fcp;
}
}
flush_rule_ptrs();
done:
static_count++;
splx(s);
DEB(printf("++ installed rule %d, static count now %d\n",
ftmp->fw_number, static_count);)
return (0);
}
/**
* free storage associated with a static chain entry (including
* dependent dynamic rules), and zeroes rule pointers to avoid
* dangling pointer dereferences.
* @return a pointer to the next entry.
* Must be called at splnet() and with a non-null argument.
*/
static struct ip_fw *
free_chain(struct ip_fw *fcp)
{
struct ip_fw *n;
n = LIST_NEXT(fcp, next);
DELETE_DYN_CHAIN(fcp);
LIST_REMOVE(fcp, next);
static_count--;
#ifdef DUMMYNET
dn_rule_delete(fcp) ;
#endif
flush_rule_ptrs(); /* more efficient to do outside the loop */
free(fcp, M_IPFW);
return n;
}
/**
* remove all rules with given number.
*/
static int
del_entry(struct ip_fw_head *chainptr, u_short number)
{
struct ip_fw *rule;
if (number != IPFW_DEFAULT_RULE) {
LIST_FOREACH(rule, chainptr, next) {
if (rule->fw_number == number) {
int s ;
s = splnet(); /* prevent access to rules while removing */
while (rule && rule->fw_number == number)
rule = free_chain(rule);
/* XXX could move flush_rule_ptrs() here */
splx(s);
return 0 ;
}
}
}
return (EINVAL);
}
/**
* Reset some or all counters on firewall rules.
* @arg frwl is null to clear all entries, or contains a specific
* rule number.
* @arg log_only is 1 if we only want to reset logs, zero otherwise.
*/
static int
zero_entry(struct ip_fw *frwl, int log_only)
{
struct ip_fw *rule;
int s;
u_short number = 0 ;
char *msg ;
if (frwl == 0) {
s = splnet();
LIST_FOREACH(rule, &ip_fw_chain_head, next) {
if (log_only == 0) {
rule->fw_bcnt = rule->fw_pcnt = 0;
rule->timestamp = 0;
}
rule->fw_loghighest = rule->fw_pcnt+rule->fw_logamount;
}
splx(s);
msg = log_only ? "ipfw: All logging counts cleared.\n" :
"ipfw: Accounting cleared.\n";
} else {
int cleared = 0;
number = frwl->fw_number ;
/*
* It's possible to insert multiple chain entries with the
* same number, so we don't stop after finding the first
* match if zeroing a specific entry.
*/
LIST_FOREACH(rule, &ip_fw_chain_head, next)
if (number == rule->fw_number) {
s = splnet();
while (rule && number == rule->fw_number) {
if (log_only == 0) {
rule->fw_bcnt = rule->fw_pcnt = 0;
rule->timestamp = 0;
}
rule->fw_loghighest = rule->fw_pcnt+ rule->fw_logamount;
rule = LIST_NEXT(rule, next);
}
splx(s);
cleared = 1;
break;
}
if (!cleared) /* we didn't find any matching rules */
return (EINVAL);
msg = log_only ? "Entry %d logging count reset.\n" :
"ipfw: Entry %d cleared.\n";
}
if (fw_verbose)
log(LOG_SECURITY | LOG_NOTICE, msg, number);
return (0);
}
static int
check_ipfw_struct(struct ip_fw *frwl)
{
/* Check for invalid flag bits */
if ((frwl->fw_flg & ~IP_FW_F_MASK) != 0) {
dprintf(("%s undefined flag bits set (flags=%x)\n",
err_prefix, frwl->fw_flg));
return (EINVAL);
}
if (frwl->fw_flg == IP_FW_F_CHECK_S) {
/* check-state */
return 0 ;
}
/* Must apply to incoming or outgoing (or both) */
if (!(frwl->fw_flg & (IP_FW_F_IN | IP_FW_F_OUT))) {
dprintf(("%s neither in nor out\n", err_prefix));
return (EINVAL);
}
/* Empty interface name is no good */
if (((frwl->fw_flg & IP_FW_F_IIFNAME)
&& !*frwl->fw_in_if.fu_via_if.name)
|| ((frwl->fw_flg & IP_FW_F_OIFNAME)
&& !*frwl->fw_out_if.fu_via_if.name)) {
dprintf(("%s empty interface name\n", err_prefix));
return (EINVAL);
}
/* Sanity check interface matching */
if ((frwl->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) {
; /* allow "via" backwards compatibility */
} else if ((frwl->fw_flg & IP_FW_F_IN)
&& (frwl->fw_flg & IP_FW_F_OIFACE)) {
dprintf(("%s outgoing interface check on incoming\n",
err_prefix));
return (EINVAL);
}
/* Sanity check port ranges */
if ((frwl->fw_flg & IP_FW_F_SRNG) && IP_FW_GETNSRCP(frwl) < 2) {
dprintf(("%s src range set but n_src_p=%d\n",
err_prefix, IP_FW_GETNSRCP(frwl)));
return (EINVAL);
}
if ((frwl->fw_flg & IP_FW_F_DRNG) && IP_FW_GETNDSTP(frwl) < 2) {
dprintf(("%s dst range set but n_dst_p=%d\n",
err_prefix, IP_FW_GETNDSTP(frwl)));
return (EINVAL);
}
if (IP_FW_GETNSRCP(frwl) + IP_FW_GETNDSTP(frwl) > IP_FW_MAX_PORTS) {
dprintf(("%s too many ports (%d+%d)\n",
err_prefix, IP_FW_GETNSRCP(frwl), IP_FW_GETNDSTP(frwl)));
return (EINVAL);
}
/*
* Protocols other than TCP/UDP don't use port range
*/
if ((frwl->fw_prot != IPPROTO_TCP) &&
(frwl->fw_prot != IPPROTO_UDP) &&
(IP_FW_GETNSRCP(frwl) || IP_FW_GETNDSTP(frwl))) {
dprintf(("%s port(s) specified for non TCP/UDP rule\n",
err_prefix));
return (EINVAL);
}
/*
* Rather than modify the entry to make such entries work,
* we reject this rule and require user level utilities
* to enforce whatever policy they deem appropriate.
*/
if ((frwl->fw_src.s_addr & (~frwl->fw_smsk.s_addr)) ||
(frwl->fw_dst.s_addr & (~frwl->fw_dmsk.s_addr))) {
dprintf(("%s rule never matches\n", err_prefix));
return (EINVAL);
}
if ((frwl->fw_flg & IP_FW_F_FRAG) &&
(frwl->fw_prot == IPPROTO_UDP || frwl->fw_prot == IPPROTO_TCP)) {
if (IP_FW_HAVEPORTS(frwl)) {
dprintf(("%s cannot mix 'frag' and ports\n", err_prefix));
return (EINVAL);
}
if (frwl->fw_prot == IPPROTO_TCP &&
frwl->fw_tcpf != frwl->fw_tcpnf) {
dprintf(("%s cannot mix 'frag' and TCP flags\n", err_prefix));
return (EINVAL);
}
}
if (frwl->fw_flg & (IP_FW_F_UID | IP_FW_F_GID)) {
if ((frwl->fw_prot != IPPROTO_TCP) &&
(frwl->fw_prot != IPPROTO_UDP) &&
(frwl->fw_prot != IPPROTO_IP)) {
dprintf(("%s cannot use uid/gid logic on non-TCP/UDP\n", err_prefix));
return (EINVAL);
}
}
/* Check command specific stuff */
switch (frwl->fw_flg & IP_FW_F_COMMAND) {
case IP_FW_F_REJECT:
if (frwl->fw_reject_code >= 0x100
&& !(frwl->fw_prot == IPPROTO_TCP
&& frwl->fw_reject_code == IP_FW_REJECT_RST)) {
dprintf(("%s unknown reject code\n", err_prefix));
return (EINVAL);
}
break;
#if defined(IPDIVERT) || defined(DUMMYNET)
#ifdef IPDIVERT
case IP_FW_F_DIVERT: /* Diverting to port zero is invalid */
case IP_FW_F_TEE:
#endif
#ifdef DUMMYNET
case IP_FW_F_PIPE: /* pipe 0 is invalid */
case IP_FW_F_QUEUE: /* queue 0 is invalid */
#endif
if (frwl->fw_divert_port == 0) {
dprintf(("%s 0 is an invalid argument\n", err_prefix));
return (EINVAL);
}
break;
#endif /* IPDIVERT || DUMMYNET */
case IP_FW_F_DENY:
case IP_FW_F_ACCEPT:
case IP_FW_F_COUNT:
case IP_FW_F_SKIPTO:
#ifdef IPFIREWALL_FORWARD
case IP_FW_F_FWD:
#endif
break;
default:
dprintf(("%s invalid command\n", err_prefix));
return (EINVAL);
}
return 0;
}
static int
ip_fw_ctl(struct sockopt *sopt)
{
int error, s;
size_t size;
struct ip_fw *fcp;
struct ip_fw frwl, *bp , *buf;
/*
* Disallow modifications in really-really secure mode, but still allow
* the logging counters to be reset.
*/
if (sopt->sopt_name == IP_FW_ADD ||
(sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)) {
error = securelevel_ge(sopt->sopt_td->td_proc->p_ucred, 3);
if (error)
return (error);
}
error = 0;
switch (sopt->sopt_name) {
case IP_FW_GET:
s = splnet();
/* size of static rules */
size = static_count * sizeof(struct ip_fw) ;
if (ipfw_dyn_v) /* add size of dyn.rules */
size += (dyn_count * sizeof(struct ipfw_dyn_rule));
/*
* XXX todo: if the user passes a short length to know how
* much room is needed, do not
* bother filling up the buffer, just jump to the
* sooptcopyout.
*/
buf = malloc(size, M_TEMP, M_WAITOK);
if (buf == 0) {
splx(s);
error = ENOBUFS;
break;
}
bp = buf ;
LIST_FOREACH(fcp, &ip_fw_chain_head, next) {
bcopy(fcp, bp, sizeof *fcp);
bp++;
}
if (ipfw_dyn_v) {
int i ;
struct ipfw_dyn_rule *p, *dst, *last = NULL ;
dst = (struct ipfw_dyn_rule *)bp ;
for (i = 0 ; i < curr_dyn_buckets ; i++ )
for ( p = ipfw_dyn_v[i] ; p != NULL ; p = p->next, dst++ ) {
bcopy(p, dst, sizeof *p);
(int)dst->rule = p->rule->fw_number ;
dst->next = dst ; /* fake non-null pointer... */
last = dst ;
if (TIME_LEQ(dst->expire, time_second) )
dst->expire = 0 ;
else
dst->expire -= time_second ;
}
if (last != NULL)
last->next = NULL ;
}
splx(s);
error = sooptcopyout(sopt, buf, size);
FREE(buf, M_TEMP);
break;
case IP_FW_FLUSH:
/*
* Normally we cannot release the lock on each iteration.
* We could do it here only because we start from the head all
* the times so there is no risk of missing some entries.
* On the other hand, the risk is that we end up with
* a very inconsistent ruleset, so better keep the lock
* around the whole cycle.
*
* XXX this code can be improved by resetting the head of
* the list to point to the default rule, and then freeing
* the old list without the need for a lock.
*/
s = splnet();
while ( (fcp = LIST_FIRST(&ip_fw_chain_head)) &&
fcp->fw_number != IPFW_DEFAULT_RULE )
free_chain(fcp);
splx(s);
break;
case IP_FW_ADD:
error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl);
if (error || (error = check_ipfw_struct(&frwl)))
break;
if (frwl.fw_number == IPFW_DEFAULT_RULE) {
dprintf(("%s can't add rule %u\n", err_prefix,
(unsigned)IPFW_DEFAULT_RULE));
error = EINVAL;
} else {
error = add_entry(&ip_fw_chain_head, &frwl);
if (!error && sopt->sopt_dir == SOPT_GET)
error = sooptcopyout(sopt, &frwl, sizeof frwl);
}
break;
case IP_FW_DEL:
error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl);
if (error)
break;
if (frwl.fw_number == IPFW_DEFAULT_RULE) {
dprintf(("%s can't delete rule %u\n", err_prefix,
(unsigned)IPFW_DEFAULT_RULE));
error = EINVAL;
} else {
error = del_entry(&ip_fw_chain_head, frwl.fw_number);
}
break;
case IP_FW_ZERO:
case IP_FW_RESETLOG:
{
int cmd = (sopt->sopt_name == IP_FW_RESETLOG );
void *arg = NULL ;
if (sopt->sopt_val != 0) {
error = sooptcopyin(sopt, &frwl, sizeof frwl, sizeof frwl);
if (error)
break ;
arg = &frwl ;
}
error = zero_entry(arg, cmd);
}
break;
default:
printf("ip_fw_ctl invalid option %d\n", sopt->sopt_name);
error = EINVAL ;
}
return (error);
}
/**
* dummynet needs a reference to the default rule, because rules can
* be deleted while packets hold a reference to them (e.g. to resume
* processing at the next rule). When this happens, dummynet changes
* the reference to the default rule (probably it could well be a
* NULL pointer, but this way we do not need to check for the special
* case, plus here he have info on the default behaviour.
*/
struct ip_fw *ip_fw_default_rule ;
void
ip_fw_init(void)
{
struct ip_fw default_rule;
ip_fw_chk_ptr = ip_fw_chk;
ip_fw_ctl_ptr = ip_fw_ctl;
LIST_INIT(&ip_fw_chain_head);
bzero(&default_rule, sizeof default_rule);
default_rule.fw_prot = IPPROTO_IP;
default_rule.fw_number = IPFW_DEFAULT_RULE;
#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
default_rule.fw_flg |= IP_FW_F_ACCEPT;
#else
default_rule.fw_flg |= IP_FW_F_DENY;
#endif
default_rule.fw_flg |= IP_FW_F_IN | IP_FW_F_OUT;
if (check_ipfw_struct(&default_rule) != 0 ||
add_entry(&ip_fw_chain_head, &default_rule))
panic("ip_fw_init");
ip_fw_default_rule = LIST_FIRST(&ip_fw_chain_head) ;
printf("IP packet filtering initialized, "
#ifdef IPDIVERT
"divert enabled, "
#else
"divert disabled, "
#endif
#ifdef IPFIREWALL_FORWARD
"rule-based forwarding enabled, "
#else
"rule-based forwarding disabled, "
#endif
#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
"default to accept, ");
#else
"default to deny, " );
#endif
#ifndef IPFIREWALL_VERBOSE
printf("logging disabled\n");
#else
if (fw_verbose_limit == 0)
printf("unlimited logging\n");
else
printf("logging limited to %d packets/entry by default\n",
fw_verbose_limit);
#endif
}
static ip_fw_chk_t *old_chk_ptr;
static ip_fw_ctl_t *old_ctl_ptr;
static int
ipfw_modevent(module_t mod, int type, void *unused)
{
int s;
struct ip_fw *fcp;
switch (type) {
case MOD_LOAD:
s = splnet();
old_chk_ptr = ip_fw_chk_ptr;
old_ctl_ptr = ip_fw_ctl_ptr;
ip_fw_init();
splx(s);
return 0;
case MOD_UNLOAD:
s = splnet();
ip_fw_chk_ptr = old_chk_ptr;
ip_fw_ctl_ptr = old_ctl_ptr;
while ( (fcp = LIST_FIRST(&ip_fw_chain_head)) != NULL)
free_chain(fcp);
splx(s);
printf("IP firewall unloaded\n");
return 0;
default:
break;
}
return 0;
}
static moduledata_t ipfwmod = {
"ipfw",
ipfw_modevent,
0
};
DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY);
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