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freebsd-skq/sys/netinet/ip_fw.c
Luigi Rizzo 32f967a3c0 A bunch of minor changes to the code (see below) for readability, code size 
and speed. No new functionality added (yet) apart from a bugfix.
MFC will occur in due time and probably in stages.

BUGFIX: fix a problem in old code which prevented reallocation of
the hash table for dynamic rules (there is a PR on this).

OTHER CHANGES: minor changes to the internal struct for static and dynamic rules.
Requires rebuild of ipfw binary.

Add comments to show how data structures are linked together.
(It probably makes no sense to keep the chain pointers separate
from actual rule descriptors. They will be hopefully merged soon.

keep a (sysctl-readable) counter for the number of static rules,
to speed up IP_FW_GET operations

initial support for a "grace time" for expired connections, so we
can set timeouts for closing connections to much shorter times.

merge zero_entry() and resetlog_entry(), they use basically the
same code.

clean up and reduce replication of code for removing rules,
both for readability and code size.

introduce a separate lifetime for dynamic UDP rules.

fix a problem in old code which prevented reallocation of
the hash table for dynamic rules (PR ...)

restructure dynamic rule descriptors

introduce some local variables to avoid multiple dereferencing of
pointer chains (reduces code size and hopefully increases speed).
2001-09-20 13:52:49 +00:00

2103 lines
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/*
* Copyright (c) 1993 Daniel Boulet
* Copyright (c) 1994 Ugen J.S.Antsilevich
* Copyright (c) 1996 Alex Nash
* Copyright (c) 2000 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/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_chain) 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 __P((struct ip_fw_head *chainptr, struct ip_fw *frwl));
static int del_entry __P((struct ip_fw_head *chainptr, u_short number));
static int zero_entry __P((struct ip_fw *, int));
static int check_ipfw_struct __P((struct ip_fw *m));
static __inline int
iface_match __P((struct ifnet *ifp, union ip_fw_if *ifu,
int byname));
static int ipopts_match __P((struct ip *ip, struct ip_fw *f));
static int iptos_match __P((struct ip *ip, struct ip_fw *f));
static __inline int
port_match __P((u_short *portptr, int nports, u_short port,
int range_flag, int mask));
static int tcpflg_match __P((struct tcphdr *tcp, struct ip_fw *f));
static int icmptype_match __P((struct icmp * icmp, struct ip_fw * f));
static void ipfw_report __P((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 __P((struct ip **pip, int hlen,
struct ifnet *oif, u_int16_t *cookie, struct mbuf **m,
struct ip_fw_chain **flow_id,
struct sockaddr_in **next_hop));
static int ip_fw_ctl __P((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 __inline 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; \
\
DEB(printf("-- unlink 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 chain, or all
* rules if chain == 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_chain *chain, int force)
{
struct ipfw_dyn_rule *prev, *q;
int i ;
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 ;
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 chain,
* then make sure the rule is expired or we want to kill it,
* and possibly more in the future.
*/
int zap = ( chain == NULL || chain == q->chain);
if (zap)
zap = force || TIME_LEQ( q->expire , time_second );
if (zap) {
UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
} else {
prev = q ;
q = q->next ;
}
}
}
}
#define EXPIRE_DYN_CHAIN(chain) remove_dyn_rule(chain, 0 /* expired ones */)
#define EXPIRE_DYN_CHAINS() remove_dyn_rule(NULL, 0 /* expired ones */)
#define DELETE_DYN_CHAIN(chain) remove_dyn_rule(chain, 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 (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 ;
}
}
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 for a dynamic session.
*/
static struct ipfw_dyn_rule *
add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type,
struct ip_fw_chain *chain)
{
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 ;
}
r->id = *id ;
r->expire = time_second + dyn_syn_lifetime ;
r->chain = chain ;
r->dyn_type = dyn_type ;
r->pcnt = r->bcnt = 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, %d left\n",
(r->id.src_ip), (r->id.src_port),
(r->id.dst_ip), (r->id.dst_port),
dyn_count ); )
return r;
}
/*
* Install dynamic state.
* There are different types of dynamic rules which can be installed.
* The type is in chain->dyn_type.
* Type 0 (default) is a bidirectional rule
*
* Returns 1 (failure) if state is not installed.
*/
static int
install_state(struct ip_fw_chain *chain)
{
struct ipfw_dyn_rule *q ;
static int last_log ;
u_int8_t type = ((struct ip_fw_ext *)chain->rule)->dyn_type ;
DEB(printf("-- install state type %d 0x%08lx %u -> 0x%08lx %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) {
default: /* bidir rule */
add_dyn_rule(&last_pkt, DYN_KEEP_STATE, chain);
break ;
}
lookup_dyn_rule(&last_pkt, NULL) ; /* XXX just set the lifetime */
return 0;
}
/*
* given an ip_fw_chain *, 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_chain * lookup_next_rule(struct ip_fw_chain *me);
static struct ip_fw_chain *
lookup_next_rule(struct ip_fw_chain *me)
{
struct ip_fw_chain *chain ;
int rule = me->rule->fw_skipto_rule ; /* guess... */
if ( (me->rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_SKIPTO )
for (chain = LIST_NEXT(me,next); chain ; chain = LIST_NEXT(chain,next))
if (chain->rule->fw_number >= rule)
return chain ;
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_chain **flow_id,
struct sockaddr_in **next_hop)
{
struct ip_fw_chain *chain;
struct ip_fw *f = NULL, *rule = NULL;
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) {
/* Accept if passed first test */
if (fw_one_pass)
return 0;
/*
* Packet has already been tagged. Look for the next rule
* to restart processing.
*/
chain = LIST_NEXT(*flow_id, next);
if ((chain = (*flow_id)->rule->next_rule_ptr) == NULL)
chain = (*flow_id)->rule->next_rule_ptr =
lookup_next_rule(*flow_id);
if (chain == NULL)
goto dropit;
} else {
/*
* Go down the chain, looking for enlightment.
* If we've been asked to start at a given rule, do so.
*/
chain = LIST_FIRST(&ip_fw_chain_head);
if (skipto != 0) {
if (skipto >= IPFW_DEFAULT_RULE)
goto dropit;
while (chain && chain->rule->fw_number <= skipto)
chain = LIST_NEXT(chain, next);
if (chain == NULL)
goto dropit;
}
}
for (; chain; chain = LIST_NEXT(chain, next)) {
again:
f = chain->rule;
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) ); )
chain = q->chain ;
f = chain->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 (f->fw_nports != 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 (f->fw_nports != 0)
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 ( ((struct ip_fw_ext *)f)->dont_match_prob &&
random() < ((struct ip_fw_ext *)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(chain)) /* 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 */
if ( (chain = f->next_rule_ptr) == NULL )
chain = lookup_next_rule(chain) ;
if (! chain)
goto dropit;
goto again ;
#ifdef DUMMYNET
case IP_FW_F_PIPE:
case IP_FW_F_QUEUE:
*flow_id = chain;
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)
*/
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 */
rule = f;
break;
}
/* Rule IPFW_DEFAULT_RULE should always be there and match */
KASSERT(chain != 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 ((rule->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 (rule->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,
rule->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_chain *fcp ;
LIST_FOREACH(fcp, &ip_fw_chain_head, next) {
fcp->rule->next_rule_ptr = NULL ;
}
}
static int
add_entry(struct ip_fw_head *head, struct ip_fw *rule)
{
struct ip_fw *ftmp = 0;
struct ip_fw_ext *ftmp_ext = 0 ;
struct ip_fw_chain *fwc, *fcp, *fcpl;
u_short nbr = 0;
int s;
fwc = malloc(sizeof *fwc, M_IPFW, M_DONTWAIT);
if (!fwc)
return (ENOSPC);
ftmp_ext = malloc(sizeof *ftmp_ext, M_IPFW, M_DONTWAIT | M_ZERO);
if (!ftmp_ext) {
free(fwc, M_IPFW);
return (ENOSPC);
}
fwc->rule = ftmp = &ftmp_ext->rule ;
bcopy(rule, ftmp, sizeof(*ftmp));
if (ftmp->fw_flg & IP_FW_F_RND_MATCH)
ftmp_ext->dont_match_prob = (intptr_t)ftmp->pipe_ptr;
if (ftmp->fw_flg & IP_FW_F_KEEP_S) {
u_long type = (u_long)(ftmp->next_rule_ptr) ;
ftmp_ext->dyn_type = type & 0xff;
}
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, fwc, next);
goto done;
}
/* If entry number is 0, find highest numbered rule and add 100 */
if (ftmp->fw_number == 0) {
LIST_FOREACH(fcp, head, next) {
if (fcp->rule->fw_number != IPFW_DEFAULT_RULE)
nbr = fcp->rule->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->rule->fw_number > ftmp->fw_number) {
if (fcpl) {
LIST_INSERT_AFTER(fcpl, fwc, next);
} else {
LIST_INSERT_HEAD(head, fwc, 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_chain *
free_chain(struct ip_fw_chain *fcp)
{
struct ip_fw_chain *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->rule, M_IPFW);
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_chain *fcp;
if (number != IPFW_DEFAULT_RULE) {
LIST_FOREACH(fcp, chainptr, next) {
if (fcp->rule->fw_number == number) {
int s ;
s = splnet(); /* prevent access to rules while removing */
while (fcp && fcp->rule->fw_number == number)
fcp = free_chain(fcp);
/* 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_chain *fcp;
struct ip_fw *rule;
int s;
u_short number = 0 ;
char *msg ;
if (frwl == 0) {
s = splnet();
LIST_FOREACH(fcp, &ip_fw_chain_head, next) {
rule = fcp->rule;
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(fcp, &ip_fw_chain_head, next)
if (number == fcp->rule->fw_number) {
s = splnet();
while (fcp && number == (rule=fcp->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;
fcp = LIST_NEXT(fcp, 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 (frwl->fw_nports) {
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_chain *fcp;
struct ip_fw frwl, *bp , *buf;
/*
* Disallow modifications in really-really secure mode, but still allow
* the logging counters to be reset.
*/
if (securelevel >= 3 && (sopt->sopt_name == IP_FW_ADD ||
(sopt->sopt_dir == SOPT_SET && sopt->sopt_name != IP_FW_RESETLOG)))
return (EPERM);
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) {
struct ip_fw_ext *e = (struct ip_fw_ext *)fcp->rule;
bcopy(e, bp, sizeof *fcp->rule);
bp->pipe_ptr = (void *)(intptr_t) e->dont_match_prob;
bp->next_rule_ptr = (void *)(intptr_t) (e->dyn_type);
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->chain = p->chain->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->rule->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_chain *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_chain *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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