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freebsd-skq/sys/netinet/ip_fw2.c
mckusick 0dd6703d54 Malloc buckets of size 128 have been having their 64-byte offset 
trashed after being freed. This has caused several panics including
kern/42277 related to soft updates. Jim Kuhn tracked the problem
down to ipfw limit rule processing.  In the expiry of dynamic rules,
it is possible for an O_LIMIT_PARENT rule to be removed when it still
has live children.  When the children eventually do expire, a pointer
to the (long gone) parent is dereferenced and a count decremented.
Since this memory can, and is, allocated for other purposes (in the
case of kern/42277 an inodedep structure), chaos ensues. The offset
in question in inodedep is the offset of the 16 bit count field in
the ipfw2 ipfw_dyn_rule.

Submitted by:	Jim Kuhn <jkuhn@sandvine.com>
Reviewed by:	"Evgueni V. Gavrilov" <aquatique@rusunix.org>
Reviewed by:	Ben Pfountz <netprince@vt.edu>
MFC after:	1 week
2003-10-16 02:00:12 +00:00

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/*
* Copyright (c) 2002 Luigi Rizzo, Universita` di Pisa
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#define DEB(x)
#define DDB(x) x
/*
* Implement IP packet firewall (new version)
*/
#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
#define IPFW2 1
#if IPFW2
#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>
#include <netinet/ip_dummynet.h>
#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>
#ifdef IPSEC
#include <netinet6/ipsec.h>
#endif
#include <netinet/if_ether.h> /* XXX for ETHERTYPE_IP */
#include <machine/in_cksum.h> /* XXX for in_cksum */
/*
* XXX This one should go in sys/mbuf.h. It is used to avoid that
* a firewall-generated packet loops forever through the firewall.
*/
#ifndef M_SKIP_FIREWALL
#define M_SKIP_FIREWALL 0x4000
#endif
/*
* set_disable contains one bit per set value (0..31).
* If the bit is set, all rules with the corresponding set
* are disabled. Set RESVD_SET(31) is reserved for the default rule
* and rules that are not deleted by the flush command,
* and CANNOT be disabled.
* Rules in set RESVD_SET can only be deleted explicitly.
*/
static u_int32_t set_disable;
static int fw_verbose;
static int verbose_limit;
static struct callout ipfw_timeout;
#define IPFW_DEFAULT_RULE 65535
struct ip_fw_chain {
struct ip_fw *rules; /* list of rules */
struct ip_fw *reap; /* list of rules to reap */
struct mtx mtx; /* lock guarding rule list */
};
#define IPFW_LOCK_INIT(_chain) \
mtx_init(&(_chain)->mtx, "IPFW static rules", NULL, \
MTX_DEF | MTX_RECURSE)
#define IPFW_LOCK_DESTROY(_chain) mtx_destroy(&(_chain)->mtx)
#define IPFW_LOCK(_chain) mtx_lock(&(_chain)->mtx)
#define IPFW_UNLOCK(_chain) mtx_unlock(&(_chain)->mtx)
#define IPFW_LOCK_ASSERT(_chain) mtx_assert(&(_chain)->mtx, MA_OWNED)
/*
* list of rules for layer 3
*/
static struct ip_fw_chain layer3_chain;
MALLOC_DEFINE(M_IPFW, "IpFw/IpAcct", "IpFw/IpAcct chain's");
static int fw_debug = 1;
static int autoinc_step = 100; /* bounded to 1..1000 in add_rule() */
#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 | CTLFLAG_SECURE3,
&fw_enable, 0, "Enable ipfw");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, autoinc_step, CTLFLAG_RW,
&autoinc_step, 0, "Rule number autincrement step");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, one_pass,
CTLFLAG_RW | CTLFLAG_SECURE3,
&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 | CTLFLAG_SECURE3,
&fw_verbose, 0, "Log matches to ipfw rules");
SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW,
&verbose_limit, 0, "Set upper limit of matches of ipfw rules logged");
/*
* Description of dynamic rules.
*
* Dynamic rules are stored in lists accessed through a hash table
* (ipfw_dyn_v) whose size is curr_dyn_buckets. This value can
* be modified through the sysctl variable dyn_buckets which is
* updated when the table becomes empty.
*
* XXX currently there is only one list, ipfw_dyn.
*
* When a packet is received, its address fields are first masked
* with the mask defined for the rule, then hashed, then matched
* against the entries in the corresponding list.
* Dynamic rules can be used for different purposes:
* + stateful rules;
* + enforcing limits on the number of sessions;
* + in-kernel NAT (not implemented yet)
*
* The lifetime of dynamic rules is regulated by dyn_*_lifetime,
* measured in seconds and depending on the flags.
*
* The total number of dynamic rules is stored in dyn_count.
* The max number of dynamic rules is dyn_max. When we reach
* the maximum number of rules we do not create anymore. This is
* done to avoid consuming too much memory, but also too much
* time when searching on each packet (ideally, we should try instead
* to put a limit on the length of the list on each bucket...).
*
* Each dynamic rule holds a pointer to the parent ipfw rule so
* we know what action to perform. Dynamic rules are removed when
* the parent rule is deleted. XXX we should make them survive.
*
* There are some limitations with dynamic rules -- we do not
* obey the 'randomized match', and we do not do multiple
* passes through the firewall. XXX check the latter!!!
*/
static 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 */
static struct mtx ipfw_dyn_mtx; /* mutex guarding dynamic rules */
#define IPFW_DYN_LOCK_INIT() \
mtx_init(&ipfw_dyn_mtx, "IPFW dynamic rules", NULL, MTX_DEF)
#define IPFW_DYN_LOCK_DESTROY() mtx_destroy(&ipfw_dyn_mtx)
#define IPFW_DYN_LOCK() mtx_lock(&ipfw_dyn_mtx)
#define IPFW_DYN_UNLOCK() mtx_unlock(&ipfw_dyn_mtx)
#define IPFW_DYN_LOCK_ASSERT() mtx_assert(&ipfw_dyn_mtx, MA_OWNED)
/*
* 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;
/*
* Keepalives are sent if dyn_keepalive is set. They are sent every
* dyn_keepalive_period seconds, in the last dyn_keepalive_interval
* seconds of lifetime of a rule.
* dyn_rst_lifetime and dyn_fin_lifetime should be strictly lower
* than dyn_keepalive_period.
*/
static u_int32_t dyn_keepalive_interval = 20;
static u_int32_t dyn_keepalive_period = 5;
static u_int32_t dyn_keepalive = 1; /* do send keepalives */
static u_int32_t static_count; /* # of static rules */
static u_int32_t static_len; /* size in bytes of static rules */
static u_int32_t dyn_count; /* # of dynamic rules */
static u_int32_t dyn_max = 4096; /* 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_keepalive, CTLFLAG_RW,
&dyn_keepalive, 0, "Enable keepalives for dyn. rules");
#endif /* SYSCTL_NODE */
static ip_fw_chk_t ipfw_chk;
ip_dn_ruledel_t *ip_dn_ruledel_ptr = NULL; /* hook into dummynet */
/*
* This macro maps an ip pointer into a layer3 header pointer of type T
*/
#define L3HDR(T, ip) ((T *)((u_int32_t *)(ip) + (ip)->ip_hl))
static __inline int
icmptype_match(struct ip *ip, ipfw_insn_u32 *cmd)
{
int type = L3HDR(struct icmp,ip)->icmp_type;
return (type <= ICMP_MAXTYPE && (cmd->d[0] & (1<<type)) );
}
#define TT ( (1 << ICMP_ECHO) | (1 << ICMP_ROUTERSOLICIT) | \
(1 << ICMP_TSTAMP) | (1 << ICMP_IREQ) | (1 << ICMP_MASKREQ) )
static int
is_icmp_query(struct ip *ip)
{
int type = L3HDR(struct icmp, ip)->icmp_type;
return (type <= ICMP_MAXTYPE && (TT & (1<<type)) );
}
#undef TT
/*
* The following checks use two arrays of 8 or 16 bits to store the
* bits that we want set or clear, respectively. They are in the
* low and high half of cmd->arg1 or cmd->d[0].
*
* We scan options and store the bits we find set. We succeed if
*
* (want_set & ~bits) == 0 && (want_clear & ~bits) == want_clear
*
* The code is sometimes optimized not to store additional variables.
*/
static int
flags_match(ipfw_insn *cmd, u_int8_t bits)
{
u_char want_clear;
bits = ~bits;
if ( ((cmd->arg1 & 0xff) & bits) != 0)
return 0; /* some bits we want set were clear */
want_clear = (cmd->arg1 >> 8) & 0xff;
if ( (want_clear & bits) != want_clear)
return 0; /* some bits we want clear were set */
return 1;
}
static int
ipopts_match(struct ip *ip, ipfw_insn *cmd)
{
int optlen, bits = 0;
u_char *cp = (u_char *)(ip + 1);
int x = (ip->ip_hl << 2) - sizeof (struct ip);
for (; x > 0; x -= optlen, cp += optlen) {
int opt = cp[IPOPT_OPTVAL];
if (opt == IPOPT_EOL)
break;
if (opt == IPOPT_NOP)
optlen = 1;
else {
optlen = cp[IPOPT_OLEN];
if (optlen <= 0 || optlen > x)
return 0; /* invalid or truncated */
}
switch (opt) {
default:
break;
case IPOPT_LSRR:
bits |= IP_FW_IPOPT_LSRR;
break;
case IPOPT_SSRR:
bits |= IP_FW_IPOPT_SSRR;
break;
case IPOPT_RR:
bits |= IP_FW_IPOPT_RR;
break;
case IPOPT_TS:
bits |= IP_FW_IPOPT_TS;
break;
}
}
return (flags_match(cmd, bits));
}
static int
tcpopts_match(struct ip *ip, ipfw_insn *cmd)
{
int optlen, bits = 0;
struct tcphdr *tcp = L3HDR(struct tcphdr,ip);
u_char *cp = (u_char *)(tcp + 1);
int x = (tcp->th_off << 2) - sizeof(struct tcphdr);
for (; x > 0; x -= optlen, cp += optlen) {
int 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:
bits |= IP_FW_TCPOPT_MSS;
break;
case TCPOPT_WINDOW:
bits |= IP_FW_TCPOPT_WINDOW;
break;
case TCPOPT_SACK_PERMITTED:
case TCPOPT_SACK:
bits |= IP_FW_TCPOPT_SACK;
break;
case TCPOPT_TIMESTAMP:
bits |= IP_FW_TCPOPT_TS;
break;
case TCPOPT_CC:
case TCPOPT_CCNEW:
case TCPOPT_CCECHO:
bits |= IP_FW_TCPOPT_CC;
break;
}
}
return (flags_match(cmd, bits));
}
static int
iface_match(struct ifnet *ifp, ipfw_insn_if *cmd)
{
if (ifp == NULL) /* no iface with this packet, match fails */
return 0;
/* Check by name or by IP address */
if (cmd->name[0] != '\0') { /* match by name */
/* Check unit number (-1 is wildcard) */
if (cmd->p.unit != -1 && cmd->p.unit != ifp->if_unit)
return(0);
/* Check name */
if (!strncmp(ifp->if_name, cmd->name, IFNAMSIZ))
return(1);
} else {
struct ifaddr *ia;
/* XXX lock? */
TAILQ_FOREACH(ia, &ifp->if_addrhead, ifa_link) {
if (ia->ifa_addr == NULL)
continue;
if (ia->ifa_addr->sa_family != AF_INET)
continue;
if (cmd->p.ip.s_addr == ((struct sockaddr_in *)
(ia->ifa_addr))->sin_addr.s_addr)
return(1); /* match */
}
}
return(0); /* no match, fail ... */
}
/*
* The 'verrevpath' option checks that the interface that an IP packet
* arrives on is the same interface that traffic destined for the
* packet's source address would be routed out of. This is a measure
* to block forged packets. This is also commonly known as "anti-spoofing"
* or Unicast Reverse Path Forwarding (Unicast RFP) in Cisco-ese. The
* name of the knob is purposely reminisent of the Cisco IOS command,
*
* ip verify unicast reverse-path
*
* which implements the same functionality. But note that syntax is
* misleading. The check may be performed on all IP packets whether unicast,
* multicast, or broadcast.
*/
static int
verify_rev_path(struct in_addr src, struct ifnet *ifp)
{
static struct route ro;
struct sockaddr_in *dst;
dst = (struct sockaddr_in *)&(ro.ro_dst);
/* Check if we've cached the route from the previous call. */
if (src.s_addr != dst->sin_addr.s_addr) {
ro.ro_rt = NULL;
bzero(dst, sizeof(*dst));
dst->sin_family = AF_INET;
dst->sin_len = sizeof(*dst);
dst->sin_addr = src;
rtalloc_ign(&ro, RTF_CLONING|RTF_PRCLONING);
}
if ((ro.ro_rt == NULL) || (ifp == NULL) ||
(ro.ro_rt->rt_ifp->if_index != ifp->if_index))
return 0;
return 1;
}
static u_int64_t norule_counter; /* counter for ipfw_log(NULL...) */
#define SNPARGS(buf, len) buf + len, sizeof(buf) > len ? sizeof(buf) - len : 0
#define SNP(buf) buf, sizeof(buf)
/*
* We enter here when we have a rule with O_LOG.
* XXX this function alone takes about 2Kbytes of code!
*/
static void
ipfw_log(struct ip_fw *f, u_int hlen, struct ether_header *eh,
struct mbuf *m, struct ifnet *oif)
{
char *action;
int limit_reached = 0;
char action2[40], proto[48], fragment[28];
fragment[0] = '\0';
proto[0] = '\0';
if (f == NULL) { /* bogus pkt */
if (verbose_limit != 0 && norule_counter >= verbose_limit)
return;
norule_counter++;
if (norule_counter == verbose_limit)
limit_reached = verbose_limit;
action = "Refuse";
} else { /* O_LOG is the first action, find the real one */
ipfw_insn *cmd = ACTION_PTR(f);
ipfw_insn_log *l = (ipfw_insn_log *)cmd;
if (l->max_log != 0 && l->log_left == 0)
return;
l->log_left--;
if (l->log_left == 0)
limit_reached = l->max_log;
cmd += F_LEN(cmd); /* point to first action */
if (cmd->opcode == O_PROB)
cmd += F_LEN(cmd);
action = action2;
switch (cmd->opcode) {
case O_DENY:
action = "Deny";
break;
case O_REJECT:
if (cmd->arg1==ICMP_REJECT_RST)
action = "Reset";
else if (cmd->arg1==ICMP_UNREACH_HOST)
action = "Reject";
else
snprintf(SNPARGS(action2, 0), "Unreach %d",
cmd->arg1);
break;
case O_ACCEPT:
action = "Accept";
break;
case O_COUNT:
action = "Count";
break;
case O_DIVERT:
snprintf(SNPARGS(action2, 0), "Divert %d",
cmd->arg1);
break;
case O_TEE:
snprintf(SNPARGS(action2, 0), "Tee %d",
cmd->arg1);
break;
case O_SKIPTO:
snprintf(SNPARGS(action2, 0), "SkipTo %d",
cmd->arg1);
break;
case O_PIPE:
snprintf(SNPARGS(action2, 0), "Pipe %d",
cmd->arg1);
break;
case O_QUEUE:
snprintf(SNPARGS(action2, 0), "Queue %d",
cmd->arg1);
break;
case O_FORWARD_IP: {
ipfw_insn_sa *sa = (ipfw_insn_sa *)cmd;
int len;
len = snprintf(SNPARGS(action2, 0), "Forward to %s",
inet_ntoa(sa->sa.sin_addr));
if (sa->sa.sin_port)
snprintf(SNPARGS(action2, len), ":%d",
sa->sa.sin_port);
}
break;
default:
action = "UNKNOWN";
break;
}
}
if (hlen == 0) { /* non-ip */
snprintf(SNPARGS(proto, 0), "MAC");
} else {
struct ip *ip = mtod(m, struct ip *);
/* these three are all aliases to the same thing */
struct icmp *const icmp = L3HDR(struct icmp, ip);
struct tcphdr *const tcp = (struct tcphdr *)icmp;
struct udphdr *const udp = (struct udphdr *)icmp;
int ip_off, offset, ip_len;
int len;
if (eh != NULL) { /* layer 2 packets are as on the wire */
ip_off = ntohs(ip->ip_off);
ip_len = ntohs(ip->ip_len);
} else {
ip_off = ip->ip_off;
ip_len = ip->ip_len;
}
offset = ip_off & IP_OFFMASK;
switch (ip->ip_p) {
case IPPROTO_TCP:
len = snprintf(SNPARGS(proto, 0), "TCP %s",
inet_ntoa(ip->ip_src));
if (offset == 0)
snprintf(SNPARGS(proto, len), ":%d %s:%d",
ntohs(tcp->th_sport),
inet_ntoa(ip->ip_dst),
ntohs(tcp->th_dport));
else
snprintf(SNPARGS(proto, len), " %s",
inet_ntoa(ip->ip_dst));
break;
case IPPROTO_UDP:
len = snprintf(SNPARGS(proto, 0), "UDP %s",
inet_ntoa(ip->ip_src));
if (offset == 0)
snprintf(SNPARGS(proto, len), ":%d %s:%d",
ntohs(udp->uh_sport),
inet_ntoa(ip->ip_dst),
ntohs(udp->uh_dport));
else
snprintf(SNPARGS(proto, len), " %s",
inet_ntoa(ip->ip_dst));
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_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_off & IP_MF) ? "+" : "");
}
if (oif || m->m_pkthdr.rcvif)
log(LOG_SECURITY | LOG_INFO,
"ipfw: %d %s %s %s via %s%d%s\n",
f ? f->rulenum : -1,
action, proto, oif ? "out" : "in",
oif ? oif->if_name : m->m_pkthdr.rcvif->if_name,
oif ? oif->if_unit : m->m_pkthdr.rcvif->if_unit,
fragment);
else
log(LOG_SECURITY | LOG_INFO,
"ipfw: %d %s %s [no if info]%s\n",
f ? f->rulenum : -1,
action, proto, fragment);
if (limit_reached)
log(LOG_SECURITY | LOG_NOTICE,
"ipfw: limit %d reached on entry %d\n",
limit_reached, f ? f->rulenum : -1);
}
/*
* IMPORTANT: the hash function for dynamic rules must be commutative
* in source and destination (ip,port), because rules are bidirectional
* and we want to find both in the same bucket.
*/
static __inline int
hash_packet(struct ipfw_flow_id *id)
{
u_int32_t i;
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) { \
ipfw_dyn_rule *old_q = q; \
\
/* remove a refcount to the parent */ \
if (q->dyn_type == O_LIMIT) \
q->parent->count--; \
DEB(printf("ipfw: 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 \
head = q = q->next; \
dyn_count--; \
free(old_q, M_IPFW); }
#define TIME_LEQ(a,b) ((int)((a)-(b)) <= 0)
/**
* Remove dynamic rules pointing to "rule", or all of them if rule == NULL.
*
* If keep_me == NULL, rules are deleted even if not expired,
* otherwise only expired rules are removed.
*
* The value of the second parameter is also used to point to identify
* a rule we absolutely do not want to remove (e.g. because we are
* holding a reference to it -- this is the case with O_LIMIT_PARENT
* rules). The pointer is only used for comparison, so any non-null
* value will do.
*/
static void
remove_dyn_rule(struct ip_fw *rule, ipfw_dyn_rule *keep_me)
{
static u_int32_t last_remove = 0;
#define FORCE (keep_me == NULL)
ipfw_dyn_rule *prev, *q;
int i, pass = 0, max_pass = 0;
IPFW_DYN_LOCK_ASSERT();
if (ipfw_dyn_v == NULL || dyn_count == 0)
return;
/* do not expire more than once per second, it is useless */
if (!FORCE && last_remove == time_second)
return;
last_remove = time_second;
/*
* because O_LIMIT refer to parent rules, during the first pass only
* remove child and mark any pending LIMIT_PARENT, and remove
* them in a second pass.
*/
next_pass:
for (i = 0 ; i < curr_dyn_buckets ; i++) {
for (prev=NULL, q = ipfw_dyn_v[i] ; q ; ) {
/*
* Logic can become complex here, so we split tests.
*/
if (q == keep_me)
goto next;
if (rule != NULL && rule != q->rule)
goto next; /* not the one we are looking for */
if (q->dyn_type == O_LIMIT_PARENT) {
/*
* handle parent in the second pass,
* record we need one.
*/
max_pass = 1;
if (pass == 0)
goto next;
if (FORCE && q->count != 0 ) {
/* XXX should not happen! */
printf("ipfw: OUCH! cannot remove rule,"
" count %d\n", q->count);
}
} else {
if (!FORCE &&
!TIME_LEQ( q->expire, time_second ))
goto next;
}
if (q->dyn_type != O_LIMIT_PARENT || !q->count) {
UNLINK_DYN_RULE(prev, ipfw_dyn_v[i], q);
continue;
}
next:
prev=q;
q=q->next;
}
}
if (pass++ < max_pass)
goto next_pass;
}
/**
* lookup a dynamic rule.
*/
static ipfw_dyn_rule *
lookup_dyn_rule_locked(struct ipfw_flow_id *pkt, int *match_direction,
struct tcphdr *tcp)
{
/*
* stateful ipfw extensions.
* Lookup into dynamic session queue
*/
#define MATCH_REVERSE 0
#define MATCH_FORWARD 1
#define MATCH_NONE 2
#define MATCH_UNKNOWN 3
int i, dir = MATCH_NONE;
ipfw_dyn_rule *prev, *q=NULL;
IPFW_DYN_LOCK_ASSERT();
if (ipfw_dyn_v == NULL)
goto done; /* not found */
i = hash_packet( pkt );
for (prev=NULL, q = ipfw_dyn_v[i] ; q != NULL ; ) {
if (q->dyn_type == O_LIMIT_PARENT && q->count)
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 &&
q->dyn_type != O_LIMIT_PARENT) {
if (pkt->src_ip == q->id.src_ip &&
pkt->dst_ip == q->id.dst_ip &&
pkt->src_port == q->id.src_port &&
pkt->dst_port == q->id.dst_port ) {
dir = MATCH_FORWARD;
break;
}
if (pkt->src_ip == q->id.dst_ip &&
pkt->dst_ip == q->id.src_ip &&
pkt->src_port == q->id.dst_port &&
pkt->dst_port == q->id.src_port ) {
dir = MATCH_REVERSE;
break;
}
}
next:
prev = q;
q = q->next;
}
if (q == NULL)
goto done; /* q = NULL, not found */
if ( prev != NULL) { /* found and not in front */
prev->next = q->next;
q->next = 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);
#define BOTH_SYN (TH_SYN | (TH_SYN << 8))
#define BOTH_FIN (TH_FIN | (TH_FIN << 8))
q->state |= (dir == MATCH_FORWARD ) ? flags : (flags << 8);
switch (q->state) {
case TH_SYN: /* opening */
q->expire = time_second + dyn_syn_lifetime;
break;
case BOTH_SYN: /* move to established */
case BOTH_SYN | TH_FIN : /* one side tries to close */
case BOTH_SYN | (TH_FIN << 8) :
if (tcp) {
#define _SEQ_GE(a,b) ((int)(a) - (int)(b) >= 0)
u_int32_t ack = ntohl(tcp->th_ack);
if (dir == MATCH_FORWARD) {
if (q->ack_fwd == 0 || _SEQ_GE(ack, q->ack_fwd))
q->ack_fwd = ack;
else { /* ignore out-of-sequence */
break;
}
} else {
if (q->ack_rev == 0 || _SEQ_GE(ack, q->ack_rev))
q->ack_rev = ack;
else { /* ignore out-of-sequence */
break;
}
}
}
q->expire = time_second + dyn_ack_lifetime;
break;
case BOTH_SYN | BOTH_FIN: /* both sides closed */
if (dyn_fin_lifetime >= dyn_keepalive_period)
dyn_fin_lifetime = dyn_keepalive_period - 1;
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
if (dyn_rst_lifetime >= dyn_keepalive_period)
dyn_rst_lifetime = dyn_keepalive_period - 1;
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;
}
done:
if (match_direction)
*match_direction = dir;
return q;
}
static ipfw_dyn_rule *
lookup_dyn_rule(struct ipfw_flow_id *pkt, int *match_direction,
struct tcphdr *tcp)
{
ipfw_dyn_rule *q;
IPFW_DYN_LOCK();
q = lookup_dyn_rule_locked(pkt, match_direction, tcp);
if (q == NULL)
IPFW_DYN_UNLOCK();
/* NB: return table locked when q is not NULL */
return q;
}
static void
realloc_dynamic_table(void)
{
IPFW_DYN_LOCK_ASSERT();
/*
* Try reallocation, make sure we have a power of 2 and do
* not allow more than 64k entries. In case of overflow,
* default to 1024.
*/
if (dyn_buckets > 65536)
dyn_buckets = 1024;
if ((dyn_buckets & (dyn_buckets-1)) != 0) { /* not a power of 2 */
dyn_buckets = curr_dyn_buckets; /* reset */
return;
}
curr_dyn_buckets = dyn_buckets;
if (ipfw_dyn_v != NULL)
free(ipfw_dyn_v, M_IPFW);
for (;;) {
ipfw_dyn_v = malloc(curr_dyn_buckets * sizeof(ipfw_dyn_rule *),
M_IPFW, M_NOWAIT | M_ZERO);
if (ipfw_dyn_v != NULL || curr_dyn_buckets <= 2)
break;
curr_dyn_buckets /= 2;
}
}
/**
* Install state of type 'type' for a dynamic session.
* The hash table contains two type of rules:
* - regular rules (O_KEEP_STATE)
* - rules for sessions with limited number of sess per user
* (O_LIMIT). When they are created, the parent is
* increased by 1, and decreased on delete. In this case,
* the third parameter is the parent rule and not the chain.
* - "parent" rules for the above (O_LIMIT_PARENT).
*/
static ipfw_dyn_rule *
add_dyn_rule(struct ipfw_flow_id *id, u_int8_t dyn_type, struct ip_fw *rule)
{
ipfw_dyn_rule *r;
int i;
IPFW_DYN_LOCK_ASSERT();
if (ipfw_dyn_v == NULL ||
(dyn_count == 0 && dyn_buckets != curr_dyn_buckets)) {
realloc_dynamic_table();
if (ipfw_dyn_v == NULL)
return NULL; /* failed ! */
}
i = hash_packet(id);
r = malloc(sizeof *r, M_IPFW, M_NOWAIT | M_ZERO);
if (r == NULL) {
printf ("ipfw: sorry cannot allocate state\n");
return NULL;
}
/* increase refcount on parent, and set pointer */
if (dyn_type == O_LIMIT) {
ipfw_dyn_rule *parent = (ipfw_dyn_rule *)rule;
if ( parent->dyn_type != O_LIMIT_PARENT)
panic("invalid parent");
parent->count++;
r->parent = parent;
rule = parent->rule;
}
r->id = *id;
r->expire = time_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("ipfw: add dyn entry ty %d 0x%08x %d -> 0x%08x %d, total %d\n",
dyn_type,
(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 rule as search keys.
* If the lookup fails, then install one.
*/
static ipfw_dyn_rule *
lookup_dyn_parent(struct ipfw_flow_id *pkt, struct ip_fw *rule)
{
ipfw_dyn_rule *q;
int i;
IPFW_DYN_LOCK_ASSERT();
if (ipfw_dyn_v) {
i = hash_packet( pkt );
for (q = ipfw_dyn_v[i] ; q != NULL ; q=q->next)
if (q->dyn_type == O_LIMIT_PARENT &&
rule== q->rule &&
pkt->proto == q->id.proto &&
pkt->src_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("ipfw: lookup_dyn_parent found 0x%p\n",q);)
return q;
}
}
return add_dyn_rule(pkt, O_LIMIT_PARENT, rule);
}
/**
* Install dynamic state for rule type cmd->o.opcode
*
* Returns 1 (failure) if state is not installed because of errors or because
* session limitations are enforced.
*/
static int
install_state(struct ip_fw *rule, ipfw_insn_limit *cmd,
struct ip_fw_args *args)
{
static int last_log;
ipfw_dyn_rule *q;
DEB(printf("ipfw: install state type %d 0x%08x %u -> 0x%08x %u\n",
cmd->o.opcode,
(args->f_id.src_ip), (args->f_id.src_port),
(args->f_id.dst_ip), (args->f_id.dst_port) );)
IPFW_DYN_LOCK();
q = lookup_dyn_rule_locked(&args->f_id, NULL, NULL);
if (q != NULL) { /* should never occur */
if (last_log != time_second) {
last_log = time_second;
printf("ipfw: install_state: entry already present, done\n");
}
IPFW_DYN_UNLOCK();
return 0;
}
if (dyn_count >= dyn_max)
/*
* Run out of slots, try to remove any expired rule.
*/
remove_dyn_rule(NULL, (ipfw_dyn_rule *)1);
if (dyn_count >= dyn_max) {
if (last_log != time_second) {
last_log = time_second;
printf("ipfw: install_state: Too many dynamic rules\n");
}
IPFW_DYN_UNLOCK();
return 1; /* cannot install, notify caller */
}
switch (cmd->o.opcode) {
case O_KEEP_STATE: /* bidir rule */
add_dyn_rule(&args->f_id, O_KEEP_STATE, rule);
break;
case O_LIMIT: /* limit number of sessions */
{
u_int16_t limit_mask = cmd->limit_mask;
struct ipfw_flow_id id;
ipfw_dyn_rule *parent;
DEB(printf("ipfw: installing dyn-limit rule %d\n",
cmd->conn_limit);)
id.dst_ip = id.src_ip = 0;
id.dst_port = id.src_port = 0;
id.proto = args->f_id.proto;
if (limit_mask & DYN_SRC_ADDR)
id.src_ip = args->f_id.src_ip;
if (limit_mask & DYN_DST_ADDR)
id.dst_ip = args->f_id.dst_ip;
if (limit_mask & DYN_SRC_PORT)
id.src_port = args->f_id.src_port;
if (limit_mask & DYN_DST_PORT)
id.dst_port = args->f_id.dst_port;
parent = lookup_dyn_parent(&id, rule);
if (parent == NULL) {
printf("ipfw: add parent failed\n");
return 1;
}
if (parent->count >= cmd->conn_limit) {
/*
* See if we can remove some expired rule.
*/
remove_dyn_rule(rule, parent);
if (parent->count >= cmd->conn_limit) {
if (fw_verbose && last_log != time_second) {
last_log = time_second;
log(LOG_SECURITY | LOG_DEBUG,
"drop session, too many entries\n");
}
IPFW_DYN_UNLOCK();
return 1;
}
}
add_dyn_rule(&args->f_id, O_LIMIT, (struct ip_fw *)parent);
}
break;
default:
printf("ipfw: unknown dynamic rule type %u\n", cmd->o.opcode);
IPFW_DYN_UNLOCK();
return 1;
}
lookup_dyn_rule_locked(&args->f_id, NULL, NULL); /* XXX just set lifetime */
IPFW_DYN_UNLOCK();
return 0;
}
/*
* Transmit a TCP packet, containing either a RST or a keepalive.
* When flags & TH_RST, we are sending a RST packet, because of a
* "reset" action matched the packet.
* Otherwise we are sending a keepalive, and flags & TH_
*/
static void
send_pkt(struct ipfw_flow_id *id, u_int32_t seq, u_int32_t ack, int flags)
{
struct mbuf *m;
struct ip *ip;
struct tcphdr *tcp;
struct route sro; /* fake route */
MGETHDR(m, M_DONTWAIT, MT_HEADER);
if (m == 0)
return;
m->m_pkthdr.rcvif = (struct ifnet *)0;
m->m_pkthdr.len = m->m_len = sizeof(struct ip) + sizeof(struct tcphdr);
m->m_data += max_linkhdr;
ip = mtod(m, struct ip *);
bzero(ip, m->m_len);
tcp = (struct tcphdr *)(ip + 1); /* no IP options */
ip->ip_p = IPPROTO_TCP;
tcp->th_off = 5;
/*
* Assume we are sending a RST (or a keepalive in the reverse
* direction), swap src and destination addresses and ports.
*/
ip->ip_src.s_addr = htonl(id->dst_ip);
ip->ip_dst.s_addr = htonl(id->src_ip);
tcp->th_sport = htons(id->dst_port);
tcp->th_dport = htons(id->src_port);
if (flags & TH_RST) { /* we are sending a RST */
if (flags & TH_ACK) {
tcp->th_seq = htonl(ack);
tcp->th_ack = htonl(0);
tcp->th_flags = TH_RST;
} else {
if (flags & TH_SYN)
seq++;
tcp->th_seq = htonl(0);
tcp->th_ack = htonl(seq);
tcp->th_flags = TH_RST | TH_ACK;
}
} else {
/*
* We are sending a keepalive. flags & TH_SYN determines
* the direction, forward if set, reverse if clear.
* NOTE: seq and ack are always assumed to be correct
* as set by the caller. This may be confusing...
*/
if (flags & TH_SYN) {
/*
* we have to rewrite the correct addresses!
*/
ip->ip_dst.s_addr = htonl(id->dst_ip);
ip->ip_src.s_addr = htonl(id->src_ip);
tcp->th_dport = htons(id->dst_port);
tcp->th_sport = htons(id->src_port);
}
tcp->th_seq = htonl(seq);
tcp->th_ack = htonl(ack);
tcp->th_flags = TH_ACK;
}
/*
* set ip_len to the payload size so we can compute
* the tcp checksum on the pseudoheader
* XXX check this, could save a couple of words ?
*/
ip->ip_len = htons(sizeof(struct tcphdr));
tcp->th_sum = in_cksum(m, m->m_pkthdr.len);
/*
* now fill fields left out earlier
*/
ip->ip_ttl = ip_defttl;
ip->ip_len = m->m_pkthdr.len;
bzero (&sro, sizeof (sro));
ip_rtaddr(ip->ip_dst, &sro);
m->m_flags |= M_SKIP_FIREWALL;
ip_output(m, NULL, &sro, 0, NULL, NULL);
if (sro.ro_rt)
RTFREE(sro.ro_rt);
}
/*
* sends a reject message, consuming the mbuf passed as an argument.
*/
static void
send_reject(struct ip_fw_args *args, int code, int offset, int ip_len)
{
if (code != ICMP_REJECT_RST) { /* Send an ICMP unreach */
/* We need the IP header in host order for icmp_error(). */
if (args->eh != NULL) {
struct ip *ip = mtod(args->m, struct ip *);
ip->ip_len = ntohs(ip->ip_len);
ip->ip_off = ntohs(ip->ip_off);
}
icmp_error(args->m, ICMP_UNREACH, code, 0L, 0);
} else if (offset == 0 && args->f_id.proto == IPPROTO_TCP) {
struct tcphdr *const tcp =
L3HDR(struct tcphdr, mtod(args->m, struct ip *));
if ( (tcp->th_flags & TH_RST) == 0)
send_pkt(&(args->f_id), ntohl(tcp->th_seq),
ntohl(tcp->th_ack),
tcp->th_flags | TH_RST);
m_freem(args->m);
} else
m_freem(args->m);
args->m = NULL;
}
/**
*
* Given an ip_fw *, lookup_next_rule will return a pointer
* to the next rule, which can be either the jump
* target (for skipto instructions) or the next one in the list (in
* all other cases including a missing jump target).
* The result is also written in the "next_rule" field of the rule.
* Backward jumps are not allowed, so start looking from the next
* rule...
*
* This never returns NULL -- in case we do not have an exact match,
* the next rule is returned. When the ruleset is changed,
* pointers are flushed so we are always correct.
*/
static struct ip_fw *
lookup_next_rule(struct ip_fw *me)
{
struct ip_fw *rule = NULL;
ipfw_insn *cmd;
/* look for action, in case it is a skipto */
cmd = ACTION_PTR(me);
if (cmd->opcode == O_LOG)
cmd += F_LEN(cmd);
if ( cmd->opcode == O_SKIPTO )
for (rule = me->next; rule ; rule = rule->next)
if (rule->rulenum >= cmd->arg1)
break;
if (rule == NULL) /* failure or not a skipto */
rule = me->next;
me->next_rule = rule;
return rule;
}
/*
* The main check routine for the firewall.
*
* All arguments are in args so we can modify them and return them
* back to the caller.
*
* Parameters:
*
* args->m (in/out) The packet; we set to NULL when/if we nuke it.
* Starts with the IP header.
* args->eh (in) Mac header if present, or NULL for layer3 packet.
* args->oif Outgoing interface, or NULL if packet is incoming.
* The incoming interface is in the mbuf. (in)
* args->divert_rule (in/out)
* Skip up to the first rule past this rule number;
* upon return, non-zero port number for divert or tee.
*
* args->rule Pointer to the last matching rule (in/out)
* args->next_hop Socket we are forwarding to (out).
* args->f_id Addresses grabbed from the packet (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
ipfw_chk(struct ip_fw_args *args)
{
/*
* Local variables hold state during the processing of a packet.
*
* IMPORTANT NOTE: to speed up the processing of rules, there
* are some assumption on the values of the variables, which
* are documented here. Should you change them, please check
* the implementation of the various instructions to make sure
* that they still work.
*
* args->eh The MAC header. It is non-null for a layer2
* packet, it is NULL for a layer-3 packet.
*
* m | args->m Pointer to the mbuf, as received from the caller.
* It may change if ipfw_chk() does an m_pullup, or if it
* consumes the packet because it calls send_reject().
* XXX This has to change, so that ipfw_chk() never modifies
* or consumes the buffer.
* ip is simply an alias of the value of m, and it is kept
* in sync with it (the packet is supposed to start with
* the ip header).
*/
struct mbuf *m = args->m;
struct ip *ip = mtod(m, struct ip *);
/*
* oif | args->oif If NULL, ipfw_chk has been called on the
* inbound path (ether_input, bdg_forward, ip_input).
* If non-NULL, ipfw_chk has been called on the outbound path
* (ether_output, ip_output).
*/
struct ifnet *oif = args->oif;
struct ip_fw *f = NULL; /* matching rule */
int retval = 0;
/*
* hlen The length of the IPv4 header.
* hlen >0 means we have an IPv4 packet.
*/
u_int hlen = 0; /* hlen >0 means we have an IP pkt */
/*
* offset The offset of a fragment. offset != 0 means that
* we have a fragment at this offset of an IPv4 packet.
* offset == 0 means that (if this is an IPv4 packet)
* this is the first or only fragment.
*/
u_short offset = 0;
/*
* Local copies of addresses. They are only valid if we have
* an IP packet.
*
* proto The protocol. Set to 0 for non-ip packets,
* or to the protocol read from the packet otherwise.
* proto != 0 means that we have an IPv4 packet.
*
* src_port, dst_port port numbers, in HOST format. Only
* valid for TCP and UDP packets.
*
* src_ip, dst_ip ip addresses, in NETWORK format.
* Only valid for IPv4 packets.
*/
u_int8_t proto;
u_int16_t src_port = 0, dst_port = 0; /* NOTE: host format */
struct in_addr src_ip, dst_ip; /* NOTE: network format */
u_int16_t ip_len=0;
int pktlen;
int dyn_dir = MATCH_UNKNOWN;
ipfw_dyn_rule *q = NULL;
struct ip_fw_chain *chain = &layer3_chain;
if (m->m_flags & M_SKIP_FIREWALL)
return 0; /* accept */
/*
* dyn_dir = MATCH_UNKNOWN when rules unchecked,
* MATCH_NONE when checked and not matched (q = NULL),
* MATCH_FORWARD or MATCH_REVERSE otherwise (q != NULL)
*/
pktlen = m->m_pkthdr.len;
if (args->eh == NULL || /* layer 3 packet */
( m->m_pkthdr.len >= sizeof(struct ip) &&
ntohs(args->eh->ether_type) == ETHERTYPE_IP))
hlen = ip->ip_hl << 2;
/*
* Collect parameters into local variables for faster matching.
*/
if (hlen == 0) { /* do not grab addresses for non-ip pkts */
proto = args->f_id.proto = 0; /* mark f_id invalid */
goto after_ip_checks;
}
proto = args->f_id.proto = ip->ip_p;
src_ip = ip->ip_src;
dst_ip = ip->ip_dst;
if (args->eh != NULL) { /* layer 2 packets are as on the wire */
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;
}
pktlen = ip_len < pktlen ? ip_len : pktlen;
#define PULLUP_TO(len) \
do { \
if ((m)->m_len < (len)) { \
args->m = m = m_pullup(m, (len)); \
if (m == 0) \
goto pullup_failed; \
ip = mtod(m, struct ip *); \
} \
} while (0)
if (offset == 0) {
switch (proto) {
case IPPROTO_TCP:
{
struct tcphdr *tcp;
PULLUP_TO(hlen + sizeof(struct tcphdr));
tcp = L3HDR(struct tcphdr, ip);
dst_port = tcp->th_dport;
src_port = tcp->th_sport;
args->f_id.flags = tcp->th_flags;
}
break;
case IPPROTO_UDP:
{
struct udphdr *udp;
PULLUP_TO(hlen + sizeof(struct udphdr));
udp = L3HDR(struct udphdr, ip);
dst_port = udp->uh_dport;
src_port = udp->uh_sport;
}
break;
case IPPROTO_ICMP:
PULLUP_TO(hlen + 4); /* type, code and checksum. */
args->f_id.flags = L3HDR(struct icmp, ip)->icmp_type;
break;
default:
break;
}
#undef PULLUP_TO
}
args->f_id.src_ip = ntohl(src_ip.s_addr);
args->f_id.dst_ip = ntohl(dst_ip.s_addr);
args->f_id.src_port = src_port = ntohs(src_port);
args->f_id.dst_port = dst_port = ntohs(dst_port);
after_ip_checks:
IPFW_LOCK(chain); /* XXX expensive? can we run lock free? */
if (args->rule) {
/*
* Packet has already been tagged. Look for the next rule
* to restart processing.
*
* If fw_one_pass != 0 then just accept it.
* XXX should not happen here, but optimized out in
* the caller.
*/
if (fw_one_pass) {
IPFW_UNLOCK(chain); /* XXX optimize */
return 0;
}
f = args->rule->next_rule;
if (f == NULL)
f = lookup_next_rule(args->rule);
} else {
/*
* Find the starting rule. It can be either the first
* one, or the one after divert_rule if asked so.
*/
int skipto = args->divert_rule;
f = chain->rules;
if (args->eh == NULL && skipto != 0) {
if (skipto >= IPFW_DEFAULT_RULE) {
IPFW_UNLOCK(chain);
return(IP_FW_PORT_DENY_FLAG); /* invalid */
}
while (f && f->rulenum <= skipto)
f = f->next;
if (f == NULL) { /* drop packet */
IPFW_UNLOCK(chain);
return(IP_FW_PORT_DENY_FLAG);
}
}
}
args->divert_rule = 0; /* reset to avoid confusion later */
/*
* Now scan the rules, and parse microinstructions for each rule.
*/
for (; f; f = f->next) {
int l, cmdlen;
ipfw_insn *cmd;
int skip_or; /* skip rest of OR block */
again:
if (set_disable & (1 << f->set) )
continue;
skip_or = 0;
for (l = f->cmd_len, cmd = f->cmd ; l > 0 ;
l -= cmdlen, cmd += cmdlen) {
int match;
/*
* check_body is a jump target used when we find a
* CHECK_STATE, and need to jump to the body of
* the target rule.
*/
check_body:
cmdlen = F_LEN(cmd);
/*
* An OR block (insn_1 || .. || insn_n) has the
* F_OR bit set in all but the last instruction.
* The first match will set "skip_or", and cause
* the following instructions to be skipped until
* past the one with the F_OR bit clear.
*/
if (skip_or) { /* skip this instruction */
if ((cmd->len & F_OR) == 0)
skip_or = 0; /* next one is good */
continue;
}
match = 0; /* set to 1 if we succeed */
switch (cmd->opcode) {
/*
* The first set of opcodes compares the packet's
* fields with some pattern, setting 'match' if a
* match is found. At the end of the loop there is
* logic to deal with F_NOT and F_OR flags associated
* with the opcode.
*/
case O_NOP:
match = 1;
break;
case O_FORWARD_MAC:
printf("ipfw: opcode %d unimplemented\n",
cmd->opcode);
break;
case O_GID:
case O_UID:
/*
* We only check offset == 0 && proto != 0,
* as this ensures that we have an IPv4
* packet with the ports info.
*/
if (offset!=0)
break;
{
struct inpcbinfo *pi;
int wildcard;
struct inpcb *pcb;
if (proto == IPPROTO_TCP) {
wildcard = 0;
pi = &tcbinfo;
} else if (proto == IPPROTO_UDP) {
wildcard = 1;
pi = &udbinfo;
} else
break;
/* XXX locking? */
pcb = (oif) ?
in_pcblookup_hash(pi,
dst_ip, htons(dst_port),
src_ip, htons(src_port),
wildcard, oif) :
in_pcblookup_hash(pi,
src_ip, htons(src_port),
dst_ip, htons(dst_port),
wildcard, NULL);
if (pcb == NULL || pcb->inp_socket == NULL)
break;
#if __FreeBSD_version < 500034
#define socheckuid(a,b) ((a)->so_cred->cr_uid != (b))
#endif
if (cmd->opcode == O_UID) {
match =
!socheckuid(pcb->inp_socket,
(uid_t)((ipfw_insn_u32 *)cmd)->d[0]);
} else {
match = groupmember(
(uid_t)((ipfw_insn_u32 *)cmd)->d[0],
pcb->inp_socket->so_cred);
}
}
break;
case O_RECV:
match = iface_match(m->m_pkthdr.rcvif,
(ipfw_insn_if *)cmd);
break;
case O_XMIT:
match = iface_match(oif, (ipfw_insn_if *)cmd);
break;
case O_VIA:
match = iface_match(oif ? oif :
m->m_pkthdr.rcvif, (ipfw_insn_if *)cmd);
break;
case O_MACADDR2:
if (args->eh != NULL) { /* have MAC header */
u_int32_t *want = (u_int32_t *)
((ipfw_insn_mac *)cmd)->addr;
u_int32_t *mask = (u_int32_t *)
((ipfw_insn_mac *)cmd)->mask;
u_int32_t *hdr = (u_int32_t *)args->eh;
match =
( want[0] == (hdr[0] & mask[0]) &&
want[1] == (hdr[1] & mask[1]) &&
want[2] == (hdr[2] & mask[2]) );
}
break;
case O_MAC_TYPE:
if (args->eh != NULL) {
u_int16_t t =
ntohs(args->eh->ether_type);
u_int16_t *p =
((ipfw_insn_u16 *)cmd)->ports;
int i;
for (i = cmdlen - 1; !match && i>0;
i--, p += 2)
match = (t>=p[0] && t<=p[1]);
}
break;
case O_FRAG:
match = (hlen > 0 && offset != 0);
break;
case O_IN: /* "out" is "not in" */
match = (oif == NULL);
break;
case O_LAYER2:
match = (args->eh != NULL);
break;
case O_PROTO:
/*
* We do not allow an arg of 0 so the
* check of "proto" only suffices.
*/
match = (proto == cmd->arg1);
break;
case O_IP_SRC:
match = (hlen > 0 &&
((ipfw_insn_ip *)cmd)->addr.s_addr ==
src_ip.s_addr);
break;
case O_IP_SRC_MASK:
case O_IP_DST_MASK:
if (hlen > 0) {
uint32_t a =
(cmd->opcode == O_IP_DST_MASK) ?
dst_ip.s_addr : src_ip.s_addr;
uint32_t *p = ((ipfw_insn_u32 *)cmd)->d;
int i = cmdlen-1;
for (; !match && i>0; i-= 2, p+= 2)
match = (p[0] == (a & p[1]));
}
break;
case O_IP_SRC_ME:
if (hlen > 0) {
struct ifnet *tif;
INADDR_TO_IFP(src_ip, tif);
match = (tif != NULL);
}
break;
case O_IP_DST_SET:
case O_IP_SRC_SET:
if (hlen > 0) {
u_int32_t *d = (u_int32_t *)(cmd+1);
u_int32_t addr =
cmd->opcode == O_IP_DST_SET ?
args->f_id.dst_ip :
args->f_id.src_ip;
if (addr < d[0])
break;
addr -= d[0]; /* subtract base */
match = (addr < cmd->arg1) &&
( d[ 1 + (addr>>5)] &
(1<<(addr & 0x1f)) );
}
break;
case O_IP_DST:
match = (hlen > 0 &&
((ipfw_insn_ip *)cmd)->addr.s_addr ==
dst_ip.s_addr);
break;
case O_IP_DST_ME:
if (hlen > 0) {
struct ifnet *tif;
INADDR_TO_IFP(dst_ip, tif);
match = (tif != NULL);
}
break;
case O_IP_SRCPORT:
case O_IP_DSTPORT:
/*
* offset == 0 && proto != 0 is enough
* to guarantee that we have an IPv4
* packet with port info.
*/
if ((proto==IPPROTO_UDP || proto==IPPROTO_TCP)
&& offset == 0) {
u_int16_t x =
(cmd->opcode == O_IP_SRCPORT) ?
src_port : dst_port ;
u_int16_t *p =
((ipfw_insn_u16 *)cmd)->ports;
int i;
for (i = cmdlen - 1; !match && i>0;
i--, p += 2)
match = (x>=p[0] && x<=p[1]);
}
break;
case O_ICMPTYPE:
match = (offset == 0 && proto==IPPROTO_ICMP &&
icmptype_match(ip, (ipfw_insn_u32 *)cmd) );
break;
case O_IPOPT:
match = (hlen > 0 && ipopts_match(ip, cmd) );
break;
case O_IPVER:
match = (hlen > 0 && cmd->arg1 == ip->ip_v);
break;
case O_IPID:
case O_IPLEN:
case O_IPTTL:
if (hlen > 0) { /* only for IP packets */
uint16_t x;
uint16_t *p;
int i;
if (cmd->opcode == O_IPLEN)
x = ip_len;
else if (cmd->opcode == O_IPTTL)
x = ip->ip_ttl;
else /* must be IPID */
x = ntohs(ip->ip_id);
if (cmdlen == 1) {
match = (cmd->arg1 == x);
break;
}
/* otherwise we have ranges */
p = ((ipfw_insn_u16 *)cmd)->ports;
i = cmdlen - 1;
for (; !match && i>0; i--, p += 2)
match = (x >= p[0] && x <= p[1]);
}
break;
case O_IPPRECEDENCE:
match = (hlen > 0 &&
(cmd->arg1 == (ip->ip_tos & 0xe0)) );
break;
case O_IPTOS:
match = (hlen > 0 &&
flags_match(cmd, ip->ip_tos));
break;
case O_TCPFLAGS:
match = (proto == IPPROTO_TCP && offset == 0 &&
flags_match(cmd,
L3HDR(struct tcphdr,ip)->th_flags));
break;
case O_TCPOPTS:
match = (proto == IPPROTO_TCP && offset == 0 &&
tcpopts_match(ip, cmd));
break;
case O_TCPSEQ:
match = (proto == IPPROTO_TCP && offset == 0 &&
((ipfw_insn_u32 *)cmd)->d[0] ==
L3HDR(struct tcphdr,ip)->th_seq);
break;
case O_TCPACK:
match = (proto == IPPROTO_TCP && offset == 0 &&
((ipfw_insn_u32 *)cmd)->d[0] ==
L3HDR(struct tcphdr,ip)->th_ack);
break;
case O_TCPWIN:
match = (proto == IPPROTO_TCP && offset == 0 &&
cmd->arg1 ==
L3HDR(struct tcphdr,ip)->th_win);
break;
case O_ESTAB:
/* reject packets which have SYN only */
/* XXX should i also check for TH_ACK ? */
match = (proto == IPPROTO_TCP && offset == 0 &&
(L3HDR(struct tcphdr,ip)->th_flags &
(TH_RST | TH_ACK | TH_SYN)) != TH_SYN);
break;
case O_LOG:
if (fw_verbose)
ipfw_log(f, hlen, args->eh, m, oif);
match = 1;
break;
case O_PROB:
match = (random()<((ipfw_insn_u32 *)cmd)->d[0]);
break;
case O_VERREVPATH:
/* Outgoing packets automatically pass/match */
match = ((oif != NULL) ||
(m->m_pkthdr.rcvif == NULL) ||
verify_rev_path(src_ip, m->m_pkthdr.rcvif));
break;
case O_IPSEC:
#ifdef FAST_IPSEC
match = (m_tag_find(m,
PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL);
#endif
#ifdef IPSEC
match = (ipsec_gethist(m, NULL) != NULL);
#endif
/* otherwise no match */
break;
/*
* The second set of opcodes represents 'actions',
* i.e. the terminal part of a rule once the packet
* matches all previous patterns.
* Typically there is only one action for each rule,
* and the opcode is stored at the end of the rule
* (but there are exceptions -- see below).
*
* In general, here we set retval and terminate the
* outer loop (would be a 'break 3' in some language,
* but we need to do a 'goto done').
*
* Exceptions:
* O_COUNT and O_SKIPTO actions:
* instead of terminating, we jump to the next rule
* ('goto next_rule', equivalent to a 'break 2'),
* or to the SKIPTO target ('goto again' after
* having set f, cmd and l), respectively.
*
* O_LIMIT and O_KEEP_STATE: these opcodes are
* not real 'actions', and are stored right
* before the 'action' part of the rule.
* These opcodes try to install an entry in the
* state tables; if successful, we continue with
* the next opcode (match=1; break;), otherwise
* the packet * must be dropped
* ('goto done' after setting retval);
*
* O_PROBE_STATE and O_CHECK_STATE: these opcodes
* cause a lookup of the state table, and a jump
* to the 'action' part of the parent rule
* ('goto check_body') if an entry is found, or
* (CHECK_STATE only) a jump to the next rule if
* the entry is not found ('goto next_rule').
* The result of the lookup is cached to make
* further instances of these opcodes are
* effectively NOPs.
*/
case O_LIMIT:
case O_KEEP_STATE:
if (install_state(f,
(ipfw_insn_limit *)cmd, args)) {
retval = IP_FW_PORT_DENY_FLAG;
goto done; /* error/limit violation */
}
match = 1;
break;
case O_PROBE_STATE:
case O_CHECK_STATE:
/*
* dynamic rules are checked at the first
* keep-state or check-state occurrence,
* with the result being stored in dyn_dir.
* The compiler introduces a PROBE_STATE
* instruction for us when we have a
* KEEP_STATE (because PROBE_STATE needs
* to be run first).
*/
if (dyn_dir == MATCH_UNKNOWN &&
(q = lookup_dyn_rule(&args->f_id,
&dyn_dir, proto == IPPROTO_TCP ?
L3HDR(struct tcphdr, ip) : NULL))
!= NULL) {
/*
* Found dynamic entry, update stats
* and jump to the 'action' part of
* the parent rule.
*/
q->pcnt++;
q->bcnt += pktlen;
f = q->rule;
cmd = ACTION_PTR(f);
l = f->cmd_len - f->act_ofs;
IPFW_DYN_UNLOCK();
goto check_body;
}
/*
* Dynamic entry not found. If CHECK_STATE,
* skip to next rule, if PROBE_STATE just
* ignore and continue with next opcode.
*/
if (cmd->opcode == O_CHECK_STATE)
goto next_rule;
match = 1;
break;
case O_ACCEPT:
retval = 0; /* accept */
goto done;
case O_PIPE:
case O_QUEUE:
args->rule = f; /* report matching rule */
retval = cmd->arg1 | IP_FW_PORT_DYNT_FLAG;
goto done;
case O_DIVERT:
case O_TEE:
if (args->eh) /* not on layer 2 */
break;
args->divert_rule = f->rulenum;
retval = (cmd->opcode == O_DIVERT) ?
cmd->arg1 :
cmd->arg1 | IP_FW_PORT_TEE_FLAG;
goto done;
case O_COUNT:
case O_SKIPTO:
f->pcnt++; /* update stats */
f->bcnt += pktlen;
f->timestamp = time_second;
if (cmd->opcode == O_COUNT)
goto next_rule;
/* handle skipto */
if (f->next_rule == NULL)
lookup_next_rule(f);
f = f->next_rule;
goto again;
case O_REJECT:
/*
* Drop the packet and send a reject notice
* if the packet is not ICMP (or is an ICMP
* query), and it is not multicast/broadcast.
*/
if (hlen > 0 &&
(proto != IPPROTO_ICMP ||
is_icmp_query(ip)) &&
!(m->m_flags & (M_BCAST|M_MCAST)) &&
!IN_MULTICAST(dst_ip.s_addr)) {
send_reject(args, cmd->arg1,
offset,ip_len);
m = args->m;
}
/* FALLTHROUGH */
case O_DENY:
retval = IP_FW_PORT_DENY_FLAG;
goto done;
case O_FORWARD_IP:
if (args->eh) /* not valid on layer2 pkts */
break;
if (!q || dyn_dir == MATCH_FORWARD)
args->next_hop =
&((ipfw_insn_sa *)cmd)->sa;
retval = 0;
goto done;
default:
panic("-- unknown opcode %d\n", cmd->opcode);
} /* end of switch() on opcodes */
if (cmd->len & F_NOT)
match = !match;
if (match) {
if (cmd->len & F_OR)
skip_or = 1;
} else {
if (!(cmd->len & F_OR)) /* not an OR block, */
break; /* try next rule */
}
} /* end of inner for, scan opcodes */
next_rule:; /* try next rule */
} /* end of outer for, scan rules */
printf("ipfw: ouch!, skip past end of rules, denying packet\n");
IPFW_UNLOCK(chain);
return(IP_FW_PORT_DENY_FLAG);
done:
/* Update statistics */
f->pcnt++;
f->bcnt += pktlen;
f->timestamp = time_second;
IPFW_UNLOCK(chain);
return retval;
pullup_failed:
if (fw_verbose)
printf("ipfw: pullup failed\n");
return(IP_FW_PORT_DENY_FLAG);
}
/*
* When a rule is added/deleted, clear the next_rule pointers in all rules.
* These will be reconstructed on the fly as packets are matched.
*/
static void
flush_rule_ptrs(struct ip_fw_chain *chain)
{
struct ip_fw *rule;
IPFW_LOCK_ASSERT(chain);
for (rule = chain->rules; rule; rule = rule->next)
rule->next_rule = NULL;
}
/*
* When pipes/queues are deleted, clear the "pipe_ptr" pointer to a given
* pipe/queue, or to all of them (match == NULL).
*/
void
flush_pipe_ptrs(struct dn_flow_set *match)
{
struct ip_fw *rule;
IPFW_LOCK(&layer3_chain);
for (rule = layer3_chain.rules; rule; rule = rule->next) {
ipfw_insn_pipe *cmd = (ipfw_insn_pipe *)ACTION_PTR(rule);
if (cmd->o.opcode != O_PIPE && cmd->o.opcode != O_QUEUE)
continue;
/*
* XXX Use bcmp/bzero to handle pipe_ptr to overcome
* possible alignment problems on 64-bit architectures.
* This code is seldom used so we do not worry too
* much about efficiency.
*/
if (match == NULL ||
!bcmp(&cmd->pipe_ptr, &match, sizeof(match)) )
bzero(&cmd->pipe_ptr, sizeof(cmd->pipe_ptr));
}
IPFW_UNLOCK(&layer3_chain);
}
/*
* Add a new rule to the list. Copy the rule into a malloc'ed area, then
* possibly create a rule number and add the rule to the list.
* Update the rule_number in the input struct so the caller knows it as well.
*/
static int
add_rule(struct ip_fw_chain *chain, struct ip_fw *input_rule)
{
struct ip_fw *rule, *f, *prev;
int l = RULESIZE(input_rule);
if (chain->rules == NULL && input_rule->rulenum != IPFW_DEFAULT_RULE)
return (EINVAL);
rule = malloc(l, M_IPFW, M_NOWAIT | M_ZERO);
if (rule == NULL)
return (ENOSPC);
bcopy(input_rule, rule, l);
rule->next = NULL;
rule->next_rule = NULL;
rule->pcnt = 0;
rule->bcnt = 0;
rule->timestamp = 0;
IPFW_LOCK(chain);
if (chain->rules == NULL) { /* default rule */
chain->rules = rule;
goto done;
}
/*
* If rulenum is 0, find highest numbered rule before the
* default rule, and add autoinc_step
*/
if (autoinc_step < 1)
autoinc_step = 1;
else if (autoinc_step > 1000)
autoinc_step = 1000;
if (rule->rulenum == 0) {
/*
* locate the highest numbered rule before default
*/
for (f = chain->rules; f; f = f->next) {
if (f->rulenum == IPFW_DEFAULT_RULE)
break;
rule->rulenum = f->rulenum;
}
if (rule->rulenum < IPFW_DEFAULT_RULE - autoinc_step)
rule->rulenum += autoinc_step;
input_rule->rulenum = rule->rulenum;
}
/*
* Now insert the new rule in the right place in the sorted list.
*/
for (prev = NULL, f = chain->rules; f; prev = f, f = f->next) {
if (f->rulenum > rule->rulenum) { /* found the location */
if (prev) {
rule->next = f;
prev->next = rule;
} else { /* head insert */
rule->next = chain->rules;
chain->rules = rule;
}
break;
}
}
flush_rule_ptrs(chain);
done:
static_count++;
static_len += l;
IPFW_UNLOCK(chain);
DEB(printf("ipfw: installed rule %d, static count now %d\n",
rule->rulenum, static_count);)
return (0);
}
/**
* Remove a static rule (including derived * dynamic rules)
* and place it on the ``reap list'' for later reclamation.
* The caller is in charge of clearing rule pointers to avoid
* dangling pointers.
* @return a pointer to the next entry.
* Arguments are not checked, so they better be correct.
*/
static struct ip_fw *
remove_rule(struct ip_fw_chain *chain, struct ip_fw *rule, struct ip_fw *prev)
{
struct ip_fw *n;
int l = RULESIZE(rule);
IPFW_LOCK_ASSERT(chain);
n = rule->next;
IPFW_DYN_LOCK();
remove_dyn_rule(rule, NULL /* force removal */);
IPFW_DYN_UNLOCK();
if (prev == NULL)
chain->rules = n;
else
prev->next = n;
static_count--;
static_len -= l;
rule->next = chain->reap;
chain->reap = rule;
return n;
}
/**
* Reclaim storage associated with a list of rules. This is
* typically the list created using remove_rule.
*/
static void
reap_rules(struct ip_fw *head)
{
struct ip_fw *rule;
while ((rule = head) != NULL) {
head = head->next;
if (DUMMYNET_LOADED)
ip_dn_ruledel_ptr(rule);
free(rule, M_IPFW);
}
}
/*
* Remove all rules from a chain (except rules in set RESVD_SET
* unless kill_default = 1). The caller is responsible for
* reclaiming storage for the rules left in chain->reap.
*/
static void
free_chain(struct ip_fw_chain *chain, int kill_default)
{
struct ip_fw *prev, *rule;
IPFW_LOCK_ASSERT(chain);
flush_rule_ptrs(chain); /* more efficient to do outside the loop */
for (prev = NULL, rule = chain->rules; rule ; )
if (kill_default || rule->set != RESVD_SET)
rule = remove_rule(chain, rule, prev);
else {
prev = rule;
rule = rule->next;
}
}
/**
* Remove all rules with given number, and also do set manipulation.
* Assumes chain != NULL && *chain != NULL.
*
* The argument is an u_int32_t. The low 16 bit are the rule or set number,
* the next 8 bits are the new set, the top 8 bits are the command:
*
* 0 delete rules with given number
* 1 delete rules with given set number
* 2 move rules with given number to new set
* 3 move rules with given set number to new set
* 4 swap sets with given numbers
*/
static int
del_entry(struct ip_fw_chain *chain, u_int32_t arg)
{
struct ip_fw *prev = NULL, *rule;
u_int16_t rulenum; /* rule or old_set */
u_int8_t cmd, new_set;
rulenum = arg & 0xffff;
cmd = (arg >> 24) & 0xff;
new_set = (arg >> 16) & 0xff;
if (cmd > 4)
return EINVAL;
if (new_set > RESVD_SET)
return EINVAL;
if (cmd == 0 || cmd == 2) {
if (rulenum >= IPFW_DEFAULT_RULE)
return EINVAL;
} else {
if (rulenum > RESVD_SET) /* old_set */
return EINVAL;
}
IPFW_LOCK(chain);
rule = chain->rules;
chain->reap = NULL;
switch (cmd) {
case 0: /* delete rules with given number */
/*
* locate first rule to delete
*/
for (; rule->rulenum < rulenum; prev = rule, rule = rule->next)
;
if (rule->rulenum != rulenum) {
IPFW_UNLOCK(chain);
return EINVAL;
}
/*
* flush pointers outside the loop, then delete all matching
* rules. prev remains the same throughout the cycle.
*/
flush_rule_ptrs(chain);
while (rule->rulenum == rulenum)
rule = remove_rule(chain, rule, prev);
break;
case 1: /* delete all rules with given set number */
flush_rule_ptrs(chain);
rule = chain->rules;
while (rule->rulenum < IPFW_DEFAULT_RULE)
if (rule->set == rulenum)
rule = remove_rule(chain, rule, prev);
else {
prev = rule;
rule = rule->next;
}
break;
case 2: /* move rules with given number to new set */
rule = chain->rules;
for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next)
if (rule->rulenum == rulenum)
rule->set = new_set;
break;
case 3: /* move rules with given set number to new set */
for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next)
if (rule->set == rulenum)
rule->set = new_set;
break;
case 4: /* swap two sets */
for (; rule->rulenum < IPFW_DEFAULT_RULE; rule = rule->next)
if (rule->set == rulenum)
rule->set = new_set;
else if (rule->set == new_set)
rule->set = rulenum;
break;
}
/*
* Look for rules to reclaim. We grab the list before
* releasing the lock then reclaim them w/o the lock to
* avoid a LOR with dummynet.
*/
rule = chain->reap;
chain->reap = NULL;
IPFW_UNLOCK(chain);
if (rule)
reap_rules(rule);
return 0;
}
/*
* Clear counters for a specific rule.
* The enclosing "table" is assumed locked.
*/
static void
clear_counters(struct ip_fw *rule, int log_only)
{
ipfw_insn_log *l = (ipfw_insn_log *)ACTION_PTR(rule);
if (log_only == 0) {
rule->bcnt = rule->pcnt = 0;
rule->timestamp = 0;
}
if (l->o.opcode == O_LOG)
l->log_left = l->max_log;
}
/**
* 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_chain *chain, int rulenum, int log_only)
{
struct ip_fw *rule;
char *msg;
IPFW_LOCK(chain);
if (rulenum == 0) {
norule_counter = 0;
for (rule = chain->rules; rule; rule = rule->next)
clear_counters(rule, log_only);
msg = log_only ? "ipfw: All logging counts reset.\n" :
"ipfw: Accounting cleared.\n";
} else {
int cleared = 0;
/*
* We can have multiple rules with the same number, so we
* need to clear them all.
*/
for (rule = chain->rules; rule; rule = rule->next)
if (rule->rulenum == rulenum) {
while (rule && rule->rulenum == rulenum) {
clear_counters(rule, log_only);
rule = rule->next;
}
cleared = 1;
break;
}
if (!cleared) { /* we did not find any matching rules */
IPFW_UNLOCK(chain);
return (EINVAL);
}
msg = log_only ? "ipfw: Entry %d logging count reset.\n" :
"ipfw: Entry %d cleared.\n";
}
IPFW_UNLOCK(chain);
if (fw_verbose)
log(LOG_SECURITY | LOG_NOTICE, msg, rulenum);
return (0);
}
/*
* Check validity of the structure before insert.
* Fortunately rules are simple, so this mostly need to check rule sizes.
*/
static int
check_ipfw_struct(struct ip_fw *rule, int size)
{
int l, cmdlen = 0;
int have_action=0;
ipfw_insn *cmd;
if (size < sizeof(*rule)) {
printf("ipfw: rule too short\n");
return (EINVAL);
}
/* first, check for valid size */
l = RULESIZE(rule);
if (l != size) {
printf("ipfw: size mismatch (have %d want %d)\n", size, l);
return (EINVAL);
}
/*
* Now go for the individual checks. Very simple ones, basically only
* instruction sizes.
*/
for (l = rule->cmd_len, cmd = rule->cmd ;
l > 0 ; l -= cmdlen, cmd += cmdlen) {
cmdlen = F_LEN(cmd);
if (cmdlen > l) {
printf("ipfw: opcode %d size truncated\n",
cmd->opcode);
return EINVAL;
}
DEB(printf("ipfw: opcode %d\n", cmd->opcode);)
switch (cmd->opcode) {
case O_PROBE_STATE:
case O_KEEP_STATE:
case O_PROTO:
case O_IP_SRC_ME:
case O_IP_DST_ME:
case O_LAYER2:
case O_IN:
case O_FRAG:
case O_IPOPT:
case O_IPTOS:
case O_IPPRECEDENCE:
case O_IPVER:
case O_TCPWIN:
case O_TCPFLAGS:
case O_TCPOPTS:
case O_ESTAB:
case O_VERREVPATH:
case O_IPSEC:
if (cmdlen != F_INSN_SIZE(ipfw_insn))
goto bad_size;
break;
case O_UID:
case O_GID:
case O_IP_SRC:
case O_IP_DST:
case O_TCPSEQ:
case O_TCPACK:
case O_PROB:
case O_ICMPTYPE:
if (cmdlen != F_INSN_SIZE(ipfw_insn_u32))
goto bad_size;
break;
case O_LIMIT:
if (cmdlen != F_INSN_SIZE(ipfw_insn_limit))
goto bad_size;
break;
case O_LOG:
if (cmdlen != F_INSN_SIZE(ipfw_insn_log))
goto bad_size;
((ipfw_insn_log *)cmd)->log_left =
((ipfw_insn_log *)cmd)->max_log;
break;
case O_IP_SRC_MASK:
case O_IP_DST_MASK:
/* only odd command lengths */
if ( !(cmdlen & 1) || cmdlen > 31)
goto bad_size;
break;
case O_IP_SRC_SET:
case O_IP_DST_SET:
if (cmd->arg1 == 0 || cmd->arg1 > 256) {
printf("ipfw: invalid set size %d\n",
cmd->arg1);
return EINVAL;
}
if (cmdlen != F_INSN_SIZE(ipfw_insn_u32) +
(cmd->arg1+31)/32 )
goto bad_size;
break;
case O_MACADDR2:
if (cmdlen != F_INSN_SIZE(ipfw_insn_mac))
goto bad_size;
break;
case O_NOP:
case O_IPID:
case O_IPTTL:
case O_IPLEN:
if (cmdlen < 1 || cmdlen > 31)
goto bad_size;
break;
case O_MAC_TYPE:
case O_IP_SRCPORT:
case O_IP_DSTPORT: /* XXX artificial limit, 30 port pairs */
if (cmdlen < 2 || cmdlen > 31)
goto bad_size;
break;
case O_RECV:
case O_XMIT:
case O_VIA:
if (cmdlen != F_INSN_SIZE(ipfw_insn_if))
goto bad_size;
break;
case O_PIPE:
case O_QUEUE:
if (cmdlen != F_INSN_SIZE(ipfw_insn_pipe))
goto bad_size;
goto check_action;
case O_FORWARD_IP:
if (cmdlen != F_INSN_SIZE(ipfw_insn_sa))
goto bad_size;
goto check_action;
case O_FORWARD_MAC: /* XXX not implemented yet */
case O_CHECK_STATE:
case O_COUNT:
case O_ACCEPT:
case O_DENY:
case O_REJECT:
case O_SKIPTO:
case O_DIVERT:
case O_TEE:
if (cmdlen != F_INSN_SIZE(ipfw_insn))
goto bad_size;
check_action:
if (have_action) {
printf("ipfw: opcode %d, multiple actions"
" not allowed\n",
cmd->opcode);
return EINVAL;
}
have_action = 1;
if (l != cmdlen) {
printf("ipfw: opcode %d, action must be"
" last opcode\n",
cmd->opcode);
return EINVAL;
}
break;
default:
printf("ipfw: opcode %d, unknown opcode\n",
cmd->opcode);
return EINVAL;
}
}
if (have_action == 0) {
printf("ipfw: missing action\n");
return EINVAL;
}
return 0;
bad_size:
printf("ipfw: opcode %d size %d wrong\n",
cmd->opcode, cmdlen);
return EINVAL;
}
/*
* Copy the static and dynamic rules to the supplied buffer
* and return the amount of space actually used.
*/
static size_t
ipfw_getrules(struct ip_fw_chain *chain, void *buf, size_t space)
{
char *bp = buf;
char *ep = bp + space;
struct ip_fw *rule;
int i;
/* XXX this can take a long time and locking will block packet flow */
IPFW_LOCK(chain);
for (rule = chain->rules; rule ; rule = rule->next) {
/*
* Verify the entry fits in the buffer in case the
* rules changed between calculating buffer space and
* now. This would be better done using a generation
* number but should suffice for now.
*/
i = RULESIZE(rule);
if (bp + i <= ep) {
bcopy(rule, bp, i);
bcopy(&set_disable, &(((struct ip_fw *)bp)->next_rule),
sizeof(set_disable));
bp += i;
}
}
IPFW_UNLOCK(chain);
if (ipfw_dyn_v) {
ipfw_dyn_rule *p, *last = NULL;
IPFW_DYN_LOCK();
for (i = 0 ; i < curr_dyn_buckets; i++)
for (p = ipfw_dyn_v[i] ; p != NULL; p = p->next) {
if (bp + sizeof *p <= ep) {
ipfw_dyn_rule *dst =
(ipfw_dyn_rule *)bp;
bcopy(p, dst, sizeof *p);
bcopy(&(p->rule->rulenum), &(dst->rule),
sizeof(p->rule->rulenum));
/*
* store a non-null value in "next".
* The userland code will interpret a
* NULL here as a marker
* for the last dynamic rule.
*/
bcopy(&dst, &dst->next, sizeof(dst));
last = dst;
dst->expire =
TIME_LEQ(dst->expire, time_second) ?
0 : dst->expire - time_second ;
bp += sizeof(ipfw_dyn_rule);
}
}
IPFW_DYN_UNLOCK();
if (last != NULL) /* mark last dynamic rule */
bzero(&last->next, sizeof(last));
}
return (bp - (char *)buf);
}
/**
* {set|get}sockopt parser.
*/
static int
ipfw_ctl(struct sockopt *sopt)
{
#define RULE_MAXSIZE (256*sizeof(u_int32_t))
int error, rule_num;
size_t size;
struct ip_fw *buf, *rule;
u_int32_t rulenum[2];
/*
* 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)) {
#if __FreeBSD_version >= 500034
error = securelevel_ge(sopt->sopt_td->td_ucred, 3);
if (error)
return (error);
#else /* FreeBSD 4.x */
if (securelevel >= 3)
return (EPERM);
#endif
}
error = 0;
switch (sopt->sopt_name) {
case IP_FW_GET:
/*
* pass up a copy of the current rules. Static rules
* come first (the last of which has number IPFW_DEFAULT_RULE),
* followed by a possibly empty list of dynamic rule.
* The last dynamic rule has NULL in the "next" field.
*
* Note that the calculated size is used to bound the
* amount of data returned to the user. The rule set may
* change between calculating the size and returning the
* data in which case we'll just return what fits.
*/
size = static_len; /* size of static rules */
if (ipfw_dyn_v) /* add size of dyn.rules */
size += (dyn_count * sizeof(ipfw_dyn_rule));
/*
* XXX todo: if the user passes a short length just 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);
error = sooptcopyout(sopt, buf,
ipfw_getrules(&layer3_chain, 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.
*/
IPFW_LOCK(&layer3_chain);
layer3_chain.reap = NULL;
free_chain(&layer3_chain, 0 /* keep default rule */);
rule = layer3_chain.reap, layer3_chain.reap = NULL;
IPFW_UNLOCK(&layer3_chain);
if (layer3_chain.reap != NULL)
reap_rules(rule);
break;
case IP_FW_ADD:
rule = malloc(RULE_MAXSIZE, M_TEMP, M_WAITOK);
error = sooptcopyin(sopt, rule, RULE_MAXSIZE,
sizeof(struct ip_fw) );
if (error == 0)
error = check_ipfw_struct(rule, sopt->sopt_valsize);
if (error == 0) {
error = add_rule(&layer3_chain, rule);
size = RULESIZE(rule);
if (!error && sopt->sopt_dir == SOPT_GET)
error = sooptcopyout(sopt, rule, size);
}
free(rule, M_TEMP);
break;
case IP_FW_DEL:
/*
* IP_FW_DEL is used for deleting single rules or sets,
* and (ab)used to atomically manipulate sets. Argument size
* is used to distinguish between the two:
* sizeof(u_int32_t)
* delete single rule or set of rules,
* or reassign rules (or sets) to a different set.
* 2*sizeof(u_int32_t)
* atomic disable/enable sets.
* first u_int32_t contains sets to be disabled,
* second u_int32_t contains sets to be enabled.
*/
error = sooptcopyin(sopt, rulenum,
2*sizeof(u_int32_t), sizeof(u_int32_t));
if (error)
break;
size = sopt->sopt_valsize;
if (size == sizeof(u_int32_t)) /* delete or reassign */
error = del_entry(&layer3_chain, rulenum[0]);
else if (size == 2*sizeof(u_int32_t)) /* set enable/disable */
set_disable =
(set_disable | rulenum[0]) & ~rulenum[1] &
~(1<<RESVD_SET); /* set RESVD_SET always enabled */
else
error = EINVAL;
break;
case IP_FW_ZERO:
case IP_FW_RESETLOG: /* argument is an int, the rule number */
rule_num = 0;
if (sopt->sopt_val != 0) {
error = sooptcopyin(sopt, &rule_num,
sizeof(int), sizeof(int));
if (error)
break;
}
error = zero_entry(&layer3_chain, rule_num,
sopt->sopt_name == IP_FW_RESETLOG);
break;
default:
printf("ipfw: ipfw_ctl invalid option %d\n", sopt->sopt_name);
error = EINVAL;
}
return (error);
#undef RULE_MAXSIZE
}
/**
* dummynet needs a reference to the default rule, because rules can be
* deleted while packets hold a reference to them. When this happens,
* dummynet changes the reference to the default rule (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;
/*
* This procedure is only used to handle keepalives. It is invoked
* every dyn_keepalive_period
*/
static void
ipfw_tick(void * __unused unused)
{
int i;
ipfw_dyn_rule *q;
if (dyn_keepalive == 0 || ipfw_dyn_v == NULL || dyn_count == 0)
goto done;
IPFW_DYN_LOCK();
for (i = 0 ; i < curr_dyn_buckets ; i++) {
for (q = ipfw_dyn_v[i] ; q ; q = q->next ) {
if (q->dyn_type == O_LIMIT_PARENT)
continue;
if (q->id.proto != IPPROTO_TCP)
continue;
if ( (q->state & BOTH_SYN) != BOTH_SYN)
continue;
if (TIME_LEQ( time_second+dyn_keepalive_interval,
q->expire))
continue; /* too early */
if (TIME_LEQ(q->expire, time_second))
continue; /* too late, rule expired */
send_pkt(&(q->id), q->ack_rev - 1, q->ack_fwd, TH_SYN);
send_pkt(&(q->id), q->ack_fwd - 1, q->ack_rev, 0);
}
}
IPFW_DYN_UNLOCK();
done:
callout_reset(&ipfw_timeout, dyn_keepalive_period*hz, ipfw_tick, NULL);
}
static int
ipfw_init(void)
{
struct ip_fw default_rule;
int error;
layer3_chain.rules = NULL;
IPFW_LOCK_INIT(&layer3_chain);
IPFW_DYN_LOCK_INIT();
callout_init(&ipfw_timeout, CALLOUT_MPSAFE);
bzero(&default_rule, sizeof default_rule);
default_rule.act_ofs = 0;
default_rule.rulenum = IPFW_DEFAULT_RULE;
default_rule.cmd_len = 1;
default_rule.set = RESVD_SET;
default_rule.cmd[0].len = 1;
default_rule.cmd[0].opcode =
#ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
1 ? O_ACCEPT :
#endif
O_DENY;
error = add_rule(&layer3_chain, &default_rule);
if (error != 0) {
printf("ipfw2: error %u initializing default rule "
"(support disabled)\n", error);
IPFW_DYN_LOCK_DESTROY();
IPFW_LOCK_DESTROY(&layer3_chain);
return (error);
}
ip_fw_default_rule = layer3_chain.rules;
printf("ipfw2 initialized, divert %s, "
"rule-based forwarding enabled, default to %s, logging ",
#ifdef IPDIVERT
"enabled",
#else
"disabled",
#endif
default_rule.cmd[0].opcode == O_ACCEPT ? "accept" : "deny");
#ifdef IPFIREWALL_VERBOSE
fw_verbose = 1;
#endif
#ifdef IPFIREWALL_VERBOSE_LIMIT
verbose_limit = IPFIREWALL_VERBOSE_LIMIT;
#endif
if (fw_verbose == 0)
printf("disabled\n");
else if (verbose_limit == 0)
printf("unlimited\n");
else
printf("limited to %d packets/entry by default\n",
verbose_limit);
ip_fw_chk_ptr = ipfw_chk;
ip_fw_ctl_ptr = ipfw_ctl;
callout_reset(&ipfw_timeout, hz, ipfw_tick, NULL);
return (0);
}
static void
ipfw_destroy(void)
{
struct ip_fw *reap;
IPFW_LOCK(&layer3_chain);
callout_stop(&ipfw_timeout);
ip_fw_chk_ptr = NULL;
ip_fw_ctl_ptr = NULL;
layer3_chain.reap = NULL;
free_chain(&layer3_chain, 1 /* kill default rule */);
reap = layer3_chain.reap, layer3_chain.reap = NULL;
IPFW_UNLOCK(&layer3_chain);
if (reap != NULL)
reap_rules(reap);
IPFW_DYN_LOCK_DESTROY();
IPFW_LOCK_DESTROY(&layer3_chain);
printf("IP firewall unloaded\n");
}
static int
ipfw_modevent(module_t mod, int type, void *unused)
{
int err = 0;
switch (type) {
case MOD_LOAD:
if (IPFW_LOADED) {
printf("IP firewall already loaded\n");
err = EEXIST;
} else {
err = ipfw_init();
}
break;
case MOD_UNLOAD:
ipfw_destroy();
err = 0;
break;
default:
break;
}
return err;
}
static moduledata_t ipfwmod = {
"ipfw",
ipfw_modevent,
0
};
DECLARE_MODULE(ipfw, ipfwmod, SI_SUB_PSEUDO, SI_ORDER_ANY);
MODULE_VERSION(ipfw, 1);
#endif /* IPFW2 */
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