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ip_input.c
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ip_input.c
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/*-
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)ip_input.c 8.2 (Berkeley) 1/4/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_bootp.h"
#include "opt_ipfw.h"
#include "opt_ipstealth.h"
#include "opt_ipsec.h"
#include "opt_route.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>
#include <net/pfil.h>
#include <net/if.h>
#include <net/if_types.h>
#include <net/if_var.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/vnet.h>
#include <net/flowtable.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet/ip_fw.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_options.h>
#include <machine/in_cksum.h>
#include <netinet/ip_carp.h>
#ifdef IPSEC
#include <netinet/ip_ipsec.h>
#endif /* IPSEC */
#include <sys/socketvar.h>
#include <security/mac/mac_framework.h>
#ifdef CTASSERT
CTASSERT(sizeof(struct ip) == 20);
#endif
struct rwlock in_ifaddr_lock;
RW_SYSINIT(in_ifaddr_lock, &in_ifaddr_lock, "in_ifaddr_lock");
VNET_DEFINE(int, rsvp_on);
VNET_DEFINE(int, ipforwarding);
SYSCTL_VNET_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
&VNET_NAME(ipforwarding), 0,
"Enable IP forwarding between interfaces");
static VNET_DEFINE(int, ipsendredirects) = 1; /* XXX */
#define V_ipsendredirects VNET(ipsendredirects)
SYSCTL_VNET_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
&VNET_NAME(ipsendredirects), 0,
"Enable sending IP redirects");
static VNET_DEFINE(int, ip_keepfaith);
#define V_ip_keepfaith VNET(ip_keepfaith)
SYSCTL_VNET_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW,
&VNET_NAME(ip_keepfaith), 0,
"Enable packet capture for FAITH IPv4->IPv6 translater daemon");
static VNET_DEFINE(int, ip_sendsourcequench);
#define V_ip_sendsourcequench VNET(ip_sendsourcequench)
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW,
&VNET_NAME(ip_sendsourcequench), 0,
"Enable the transmission of source quench packets");
VNET_DEFINE(int, ip_do_randomid);
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, random_id, CTLFLAG_RW,
&VNET_NAME(ip_do_randomid), 0,
"Assign random ip_id values");
/*
* XXX - Setting ip_checkinterface mostly implements the receive side of
* the Strong ES model described in RFC 1122, but since the routing table
* and transmit implementation do not implement the Strong ES model,
* setting this to 1 results in an odd hybrid.
*
* XXX - ip_checkinterface currently must be disabled if you use ipnat
* to translate the destination address to another local interface.
*
* XXX - ip_checkinterface must be disabled if you add IP aliases
* to the loopback interface instead of the interface where the
* packets for those addresses are received.
*/
static VNET_DEFINE(int, ip_checkinterface);
#define V_ip_checkinterface VNET(ip_checkinterface)
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW,
&VNET_NAME(ip_checkinterface), 0,
"Verify packet arrives on correct interface");
VNET_DEFINE(struct pfil_head, inet_pfil_hook); /* Packet filter hooks */
static struct netisr_handler ip_nh = {
.nh_name = "ip",
.nh_handler = ip_input,
.nh_proto = NETISR_IP,
.nh_policy = NETISR_POLICY_FLOW,
};
extern struct domain inetdomain;
extern struct protosw inetsw[];
u_char ip_protox[IPPROTO_MAX];
VNET_DEFINE(struct in_ifaddrhead, in_ifaddrhead); /* first inet address */
VNET_DEFINE(struct in_ifaddrhashhead *, in_ifaddrhashtbl); /* inet addr hash table */
VNET_DEFINE(u_long, in_ifaddrhmask); /* mask for hash table */
VNET_DEFINE(struct ipstat, ipstat);
SYSCTL_VNET_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW,
&VNET_NAME(ipstat), ipstat,
"IP statistics (struct ipstat, netinet/ip_var.h)");
static VNET_DEFINE(uma_zone_t, ipq_zone);
static VNET_DEFINE(TAILQ_HEAD(ipqhead, ipq), ipq[IPREASS_NHASH]);
static struct mtx ipqlock;
#define V_ipq_zone VNET(ipq_zone)
#define V_ipq VNET(ipq)
#define IPQ_LOCK() mtx_lock(&ipqlock)
#define IPQ_UNLOCK() mtx_unlock(&ipqlock)
#define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF)
#define IPQ_LOCK_ASSERT() mtx_assert(&ipqlock, MA_OWNED)
static void maxnipq_update(void);
static void ipq_zone_change(void *);
static void ip_drain_locked(void);
static VNET_DEFINE(int, maxnipq); /* Administrative limit on # reass queues. */
static VNET_DEFINE(int, nipq); /* Total # of reass queues */
#define V_maxnipq VNET(maxnipq)
#define V_nipq VNET(nipq)
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, fragpackets, CTLFLAG_RD,
&VNET_NAME(nipq), 0,
"Current number of IPv4 fragment reassembly queue entries");
static VNET_DEFINE(int, maxfragsperpacket);
#define V_maxfragsperpacket VNET(maxfragsperpacket)
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW,
&VNET_NAME(maxfragsperpacket), 0,
"Maximum number of IPv4 fragments allowed per packet");
#ifdef IPCTL_DEFMTU
SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
&ip_mtu, 0, "Default MTU");
#endif
#ifdef IPSTEALTH
VNET_DEFINE(int, ipstealth);
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW,
&VNET_NAME(ipstealth), 0,
"IP stealth mode, no TTL decrementation on forwarding");
#endif
#ifdef FLOWTABLE
static VNET_DEFINE(int, ip_output_flowtable_size) = 2048;
VNET_DEFINE(struct flowtable *, ip_ft);
#define V_ip_output_flowtable_size VNET(ip_output_flowtable_size)
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, output_flowtable_size, CTLFLAG_RDTUN,
&VNET_NAME(ip_output_flowtable_size), 2048,
"number of entries in the per-cpu output flow caches");
#endif
static void ip_freef(struct ipqhead *, struct ipq *);
/*
* Kernel module interface for updating ipstat. The argument is an index
* into ipstat treated as an array of u_long. While this encodes the general
* layout of ipstat into the caller, it doesn't encode its location, so that
* future changes to add, for example, per-CPU stats support won't cause
* binary compatibility problems for kernel modules.
*/
void
kmod_ipstat_inc(int statnum)
{
(*((u_long *)&V_ipstat + statnum))++;
}
void
kmod_ipstat_dec(int statnum)
{
(*((u_long *)&V_ipstat + statnum))--;
}
static int
sysctl_netinet_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)
{
int error, qlimit;
netisr_getqlimit(&ip_nh, &qlimit);
error = sysctl_handle_int(oidp, &qlimit, 0, req);
if (error || !req->newptr)
return (error);
if (qlimit < 1)
return (EINVAL);
return (netisr_setqlimit(&ip_nh, qlimit));
}
SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen,
CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet_intr_queue_maxlen, "I",
"Maximum size of the IP input queue");
static int
sysctl_netinet_intr_queue_drops(SYSCTL_HANDLER_ARGS)
{
u_int64_t qdrops_long;
int error, qdrops;
netisr_getqdrops(&ip_nh, &qdrops_long);
qdrops = qdrops_long;
error = sysctl_handle_int(oidp, &qdrops, 0, req);
if (error || !req->newptr)
return (error);
if (qdrops != 0)
return (EINVAL);
netisr_clearqdrops(&ip_nh);
return (0);
}
SYSCTL_PROC(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops,
CTLTYPE_INT|CTLFLAG_RD, 0, 0, sysctl_netinet_intr_queue_drops, "I",
"Number of packets dropped from the IP input queue");
/*
* IP initialization: fill in IP protocol switch table.
* All protocols not implemented in kernel go to raw IP protocol handler.
*/
void
ip_init(void)
{
struct protosw *pr;
int i;
V_ip_id = time_second & 0xffff;
TAILQ_INIT(&V_in_ifaddrhead);
V_in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &V_in_ifaddrhmask);
/* Initialize IP reassembly queue. */
for (i = 0; i < IPREASS_NHASH; i++)
TAILQ_INIT(&V_ipq[i]);
V_maxnipq = nmbclusters / 32;
V_maxfragsperpacket = 16;
V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
NULL, UMA_ALIGN_PTR, 0);
maxnipq_update();
/* Initialize packet filter hooks. */
V_inet_pfil_hook.ph_type = PFIL_TYPE_AF;
V_inet_pfil_hook.ph_af = AF_INET;
if ((i = pfil_head_register(&V_inet_pfil_hook)) != 0)
printf("%s: WARNING: unable to register pfil hook, "
"error %d\n", __func__, i);
#ifdef FLOWTABLE
if (TUNABLE_INT_FETCH("net.inet.ip.output_flowtable_size",
&V_ip_output_flowtable_size)) {
if (V_ip_output_flowtable_size < 256)
V_ip_output_flowtable_size = 256;
if (!powerof2(V_ip_output_flowtable_size)) {
printf("flowtable must be power of 2 size\n");
V_ip_output_flowtable_size = 2048;
}
} else {
/*
* round up to the next power of 2
*/
V_ip_output_flowtable_size = 1 << fls((1024 + maxusers * 64)-1);
}
V_ip_ft = flowtable_alloc("ipv4", V_ip_output_flowtable_size, FL_PCPU);
#endif
/* Skip initialization of globals for non-default instances. */
if (!IS_DEFAULT_VNET(curvnet))
return;
pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
if (pr == NULL)
panic("ip_init: PF_INET not found");
/* Initialize the entire ip_protox[] array to IPPROTO_RAW. */
for (i = 0; i < IPPROTO_MAX; i++)
ip_protox[i] = pr - inetsw;
/*
* Cycle through IP protocols and put them into the appropriate place
* in ip_protox[].
*/
for (pr = inetdomain.dom_protosw;
pr < inetdomain.dom_protoswNPROTOSW; pr++)
if (pr->pr_domain->dom_family == PF_INET &&
pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
/* Be careful to only index valid IP protocols. */
if (pr->pr_protocol < IPPROTO_MAX)
ip_protox[pr->pr_protocol] = pr - inetsw;
}
EVENTHANDLER_REGISTER(nmbclusters_change, ipq_zone_change,
NULL, EVENTHANDLER_PRI_ANY);
/* Initialize various other remaining things. */
IPQ_LOCK_INIT();
netisr_register(&ip_nh);
}
#ifdef VIMAGE
void
ip_destroy(void)
{
/* Cleanup in_ifaddr hash table; should be empty. */
hashdestroy(V_in_ifaddrhashtbl, M_IFADDR, V_in_ifaddrhmask);
IPQ_LOCK();
ip_drain_locked();
IPQ_UNLOCK();
uma_zdestroy(V_ipq_zone);
}
#endif
/*
* Ip input routine. Checksum and byte swap header. If fragmented
* try to reassemble. Process options. Pass to next level.
*/
void
ip_input(struct mbuf *m)
{
struct ip *ip = NULL;
struct in_ifaddr *ia = NULL;
struct ifaddr *ifa;
struct ifnet *ifp;
int checkif, hlen = 0;
uint16_t sum, ip_len;
int dchg = 0; /* dest changed after fw */
struct in_addr odst; /* original dst address */
M_ASSERTPKTHDR(m);
if (m->m_flags & M_FASTFWD_OURS) {
m->m_flags &= ~M_FASTFWD_OURS;
/* Set up some basics that will be used later. */
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
ip_len = ntohs(ip->ip_len);
goto ours;
}
IPSTAT_INC(ips_total);
if (m->m_pkthdr.len < sizeof(struct ip))
goto tooshort;
if (m->m_len < sizeof (struct ip) &&
(m = m_pullup(m, sizeof (struct ip))) == NULL) {
IPSTAT_INC(ips_toosmall);
return;
}
ip = mtod(m, struct ip *);
if (ip->ip_v != IPVERSION) {
IPSTAT_INC(ips_badvers);
goto bad;
}
hlen = ip->ip_hl << 2;
if (hlen < sizeof(struct ip)) { /* minimum header length */
IPSTAT_INC(ips_badhlen);
goto bad;
}
if (hlen > m->m_len) {
if ((m = m_pullup(m, hlen)) == NULL) {
IPSTAT_INC(ips_badhlen);
return;
}
ip = mtod(m, struct ip *);
}
/* 127/8 must not appear on wire - RFC1122 */
ifp = m->m_pkthdr.rcvif;
if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
(ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
IPSTAT_INC(ips_badaddr);
goto bad;
}
}
if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) {
sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
} else {
if (hlen == sizeof(struct ip)) {
sum = in_cksum_hdr(ip);
} else {
sum = in_cksum(m, hlen);
}
}
if (sum) {
IPSTAT_INC(ips_badsum);
goto bad;
}
#ifdef ALTQ
if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
/* packet is dropped by traffic conditioner */
return;
#endif
ip_len = ntohs(ip->ip_len);
if (ip_len < hlen) {
IPSTAT_INC(ips_badlen);
goto bad;
}
/*
* Check that the amount of data in the buffers
* is as at least much as the IP header would have us expect.
* Trim mbufs if longer than we expect.
* Drop packet if shorter than we expect.
*/
if (m->m_pkthdr.len < ip_len) {
tooshort:
IPSTAT_INC(ips_tooshort);
goto bad;
}
if (m->m_pkthdr.len > ip_len) {
if (m->m_len == m->m_pkthdr.len) {
m->m_len = ip_len;
m->m_pkthdr.len = ip_len;
} else
m_adj(m, ip_len - m->m_pkthdr.len);
}
#ifdef IPSEC
/*
* Bypass packet filtering for packets previously handled by IPsec.
*/
if (ip_ipsec_filtertunnel(m))
goto passin;
#endif /* IPSEC */
/*
* Run through list of hooks for input packets.
*
* NB: Beware of the destination address changing (e.g.
* by NAT rewriting). When this happens, tell
* ip_forward to do the right thing.
*/
/* Jump over all PFIL processing if hooks are not active. */
if (!PFIL_HOOKED(&V_inet_pfil_hook))
goto passin;
odst = ip->ip_dst;
if (pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_IN, NULL) != 0)
return;
if (m == NULL) /* consumed by filter */
return;
ip = mtod(m, struct ip *);
dchg = (odst.s_addr != ip->ip_dst.s_addr);
ifp = m->m_pkthdr.rcvif;
if (m->m_flags & M_FASTFWD_OURS) {
m->m_flags &= ~M_FASTFWD_OURS;
goto ours;
}
if (m->m_flags & M_IP_NEXTHOP) {
dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL);
if (dchg != 0) {
/*
* Directly ship the packet on. This allows
* forwarding packets originally destined to us
* to some other directly connected host.
*/
ip_forward(m, 1);
return;
}
}
passin:
/*
* Process options and, if not destined for us,
* ship it on. ip_dooptions returns 1 when an
* error was detected (causing an icmp message
* to be sent and the original packet to be freed).
*/
if (hlen > sizeof (struct ip) && ip_dooptions(m, 0))
return;
/* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
* matter if it is destined to another node, or whether it is
* a multicast one, RSVP wants it! and prevents it from being forwarded
* anywhere else. Also checks if the rsvp daemon is running before
* grabbing the packet.
*/
if (V_rsvp_on && ip->ip_p==IPPROTO_RSVP)
goto ours;
/*
* Check our list of addresses, to see if the packet is for us.
* If we don't have any addresses, assume any unicast packet
* we receive might be for us (and let the upper layers deal
* with it).
*/
if (TAILQ_EMPTY(&V_in_ifaddrhead) &&
(m->m_flags & (M_MCAST|M_BCAST)) == 0)
goto ours;
/*
* Enable a consistency check between the destination address
* and the arrival interface for a unicast packet (the RFC 1122
* strong ES model) if IP forwarding is disabled and the packet
* is not locally generated and the packet is not subject to
* 'ipfw fwd'.
*
* XXX - Checking also should be disabled if the destination
* address is ipnat'ed to a different interface.
*
* XXX - Checking is incompatible with IP aliases added
* to the loopback interface instead of the interface where
* the packets are received.
*
* XXX - This is the case for carp vhost IPs as well so we
* insert a workaround. If the packet got here, we already
* checked with carp_iamatch() and carp_forus().
*/
checkif = V_ip_checkinterface && (V_ipforwarding == 0) &&
ifp != NULL && ((ifp->if_flags & IFF_LOOPBACK) == 0) &&
ifp->if_carp == NULL && (dchg == 0);
/*
* Check for exact addresses in the hash bucket.
*/
/* IN_IFADDR_RLOCK(); */
LIST_FOREACH(ia, INADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
/*
* If the address matches, verify that the packet
* arrived via the correct interface if checking is
* enabled.
*/
if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr &&
(!checkif || ia->ia_ifp == ifp)) {
ifa_ref(&ia->ia_ifa);
/* IN_IFADDR_RUNLOCK(); */
goto ours;
}
}
/* IN_IFADDR_RUNLOCK(); */
/*
* Check for broadcast addresses.
*
* Only accept broadcast packets that arrive via the matching
* interface. Reception of forwarded directed broadcasts would
* be handled via ip_forward() and ether_output() with the loopback
* into the stack for SIMPLEX interfaces handled by ether_output().
*/
if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
IF_ADDR_RLOCK(ifp);
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
ia = ifatoia(ifa);
if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
ip->ip_dst.s_addr) {
ifa_ref(ifa);
IF_ADDR_RUNLOCK(ifp);
goto ours;
}
#ifdef BOOTP_COMPAT
if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) {
ifa_ref(ifa);
IF_ADDR_RUNLOCK(ifp);
goto ours;
}
#endif
}
IF_ADDR_RUNLOCK(ifp);
ia = NULL;
}
/* RFC 3927 2.7: Do not forward datagrams for 169.254.0.0/16. */
if (IN_LINKLOCAL(ntohl(ip->ip_dst.s_addr))) {
IPSTAT_INC(ips_cantforward);
m_freem(m);
return;
}
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
if (V_ip_mrouter) {
/*
* If we are acting as a multicast router, all
* incoming multicast packets are passed to the
* kernel-level multicast forwarding function.
* The packet is returned (relatively) intact; if
* ip_mforward() returns a non-zero value, the packet
* must be discarded, else it may be accepted below.
*/
if (ip_mforward && ip_mforward(ip, ifp, m, 0) != 0) {
IPSTAT_INC(ips_cantforward);
m_freem(m);
return;
}
/*
* The process-level routing daemon needs to receive
* all multicast IGMP packets, whether or not this
* host belongs to their destination groups.
*/
if (ip->ip_p == IPPROTO_IGMP)
goto ours;
IPSTAT_INC(ips_forward);
}
/*
* Assume the packet is for us, to avoid prematurely taking
* a lock on the in_multi hash. Protocols must perform
* their own filtering and update statistics accordingly.
*/
goto ours;
}
if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
goto ours;
if (ip->ip_dst.s_addr == INADDR_ANY)
goto ours;
/*
* FAITH(Firewall Aided Internet Translator)
*/
if (ifp && ifp->if_type == IFT_FAITH) {
if (V_ip_keepfaith) {
if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP)
goto ours;
}
m_freem(m);
return;
}
/*
* Not for us; forward if possible and desirable.
*/
if (V_ipforwarding == 0) {
IPSTAT_INC(ips_cantforward);
m_freem(m);
} else {
#ifdef IPSEC
if (ip_ipsec_fwd(m))
goto bad;
#endif /* IPSEC */
ip_forward(m, dchg);
}
return;
ours:
#ifdef IPSTEALTH
/*
* IPSTEALTH: Process non-routing options only
* if the packet is destined for us.
*/
if (V_ipstealth && hlen > sizeof (struct ip) && ip_dooptions(m, 1)) {
if (ia != NULL)
ifa_free(&ia->ia_ifa);
return;
}
#endif /* IPSTEALTH */
/* Count the packet in the ip address stats */
if (ia != NULL) {
ia->ia_ifa.if_ipackets++;
ia->ia_ifa.if_ibytes += m->m_pkthdr.len;
ifa_free(&ia->ia_ifa);
}
/*
* Attempt reassembly; if it succeeds, proceed.
* ip_reass() will return a different mbuf.
*/
if (ip->ip_off & htons(IP_MF | IP_OFFMASK)) {
m = ip_reass(m);
if (m == NULL)
return;
ip = mtod(m, struct ip *);
/* Get the header length of the reassembled packet */
hlen = ip->ip_hl << 2;
}
#ifdef IPSEC
/*
* enforce IPsec policy checking if we are seeing last header.
* note that we do not visit this with protocols with pcb layer
* code - like udp/tcp/raw ip.
*/
if (ip_ipsec_input(m))
goto bad;
#endif /* IPSEC */
/*
* Switch out to protocol's input routine.
*/
IPSTAT_INC(ips_delivered);
(*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
return;
bad:
m_freem(m);
}
/*
* After maxnipq has been updated, propagate the change to UMA. The UMA zone
* max has slightly different semantics than the sysctl, for historical
* reasons.
*/
static void
maxnipq_update(void)
{
/*
* -1 for unlimited allocation.
*/
if (V_maxnipq < 0)
uma_zone_set_max(V_ipq_zone, 0);
/*
* Positive number for specific bound.
*/
if (V_maxnipq > 0)
uma_zone_set_max(V_ipq_zone, V_maxnipq);
/*
* Zero specifies no further fragment queue allocation -- set the
* bound very low, but rely on implementation elsewhere to actually
* prevent allocation and reclaim current queues.
*/
if (V_maxnipq == 0)
uma_zone_set_max(V_ipq_zone, 1);
}
static void
ipq_zone_change(void *tag)
{
if (V_maxnipq > 0 && V_maxnipq < (nmbclusters / 32)) {
V_maxnipq = nmbclusters / 32;
maxnipq_update();
}
}
static int
sysctl_maxnipq(SYSCTL_HANDLER_ARGS)
{
int error, i;
i = V_maxnipq;
error = sysctl_handle_int(oidp, &i, 0, req);
if (error || !req->newptr)
return (error);
/*
* XXXRW: Might be a good idea to sanity check the argument and place
* an extreme upper bound.
*/
if (i < -1)
return (EINVAL);
V_maxnipq = i;
maxnipq_update();
return (0);
}
SYSCTL_PROC(_net_inet_ip, OID_AUTO, maxfragpackets, CTLTYPE_INT|CTLFLAG_RW,
NULL, 0, sysctl_maxnipq, "I",
"Maximum number of IPv4 fragment reassembly queue entries");
/*
* Take incoming datagram fragment and try to reassemble it into
* whole datagram. If the argument is the first fragment or one
* in between the function will return NULL and store the mbuf
* in the fragment chain. If the argument is the last fragment
* the packet will be reassembled and the pointer to the new
* mbuf returned for further processing. Only m_tags attached
* to the first packet/fragment are preserved.
* The IP header is *NOT* adjusted out of iplen.
*/
struct mbuf *
ip_reass(struct mbuf *m)
{
struct ip *ip;
struct mbuf *p, *q, *nq, *t;
struct ipq *fp = NULL;
struct ipqhead *head;
int i, hlen, next;
u_int8_t ecn, ecn0;
u_short hash;
/* If maxnipq or maxfragsperpacket are 0, never accept fragments. */
if (V_maxnipq == 0 || V_maxfragsperpacket == 0) {
IPSTAT_INC(ips_fragments);
IPSTAT_INC(ips_fragdropped);
m_freem(m);
return (NULL);
}
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
head = &V_ipq[hash];
IPQ_LOCK();
/*
* Look for queue of fragments
* of this datagram.
*/
TAILQ_FOREACH(fp, head, ipq_list)
if (ip->ip_id == fp->ipq_id &&
ip->ip_src.s_addr == fp->ipq_src.s_addr &&
ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
#ifdef MAC
mac_ipq_match(m, fp) &&
#endif
ip->ip_p == fp->ipq_p)
goto found;
fp = NULL;
/*
* Attempt to trim the number of allocated fragment queues if it
* exceeds the administrative limit.
*/
if ((V_nipq > V_maxnipq) && (V_maxnipq > 0)) {
/*
* drop something from the tail of the current queue
* before proceeding further
*/
struct ipq *q = TAILQ_LAST(head, ipqhead);
if (q == NULL) { /* gak */
for (i = 0; i < IPREASS_NHASH; i++) {
struct ipq *r = TAILQ_LAST(&V_ipq[i], ipqhead);
if (r) {
IPSTAT_ADD(ips_fragtimeout,
r->ipq_nfrags);
ip_freef(&V_ipq[i], r);
break;
}
}
} else {
IPSTAT_ADD(ips_fragtimeout, q->ipq_nfrags);
ip_freef(head, q);
}
}
found:
/*
* Adjust ip_len to not reflect header,
* convert offset of this to bytes.
*/
ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
if (ip->ip_off & htons(IP_MF)) {
/*
* Make sure that fragments have a data length
* that's a non-zero multiple of 8 bytes.
*/
if (ip->ip_len == htons(0) || (ntohs(ip->ip_len) & 0x7) != 0) {
IPSTAT_INC(ips_toosmall); /* XXX */
goto dropfrag;
}
m->m_flags |= M_FRAG;
} else
m->m_flags &= ~M_FRAG;
ip->ip_off = htons(ntohs(ip->ip_off) << 3);
/*
* Attempt reassembly; if it succeeds, proceed.
* ip_reass() will return a different mbuf.
*/
IPSTAT_INC(ips_fragments);
m->m_pkthdr.header = ip;
/* Previous ip_reass() started here. */
/*
* Presence of header sizes in mbufs
* would confuse code below.
*/
m->m_data += hlen;
m->m_len -= hlen;
/*
* If first fragment to arrive, create a reassembly queue.
*/
if (fp == NULL) {
fp = uma_zalloc(V_ipq_zone, M_NOWAIT);
if (fp == NULL)
goto dropfrag;
#ifdef MAC
if (mac_ipq_init(fp, M_NOWAIT) != 0) {
uma_zfree(V_ipq_zone, fp);
fp = NULL;
goto dropfrag;
}
mac_ipq_create(m, fp);
#endif
TAILQ_INSERT_HEAD(head, fp, ipq_list);
V_nipq++;
fp->ipq_nfrags = 1;
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ip->ip_p;
fp->ipq_id = ip->ip_id;
fp->ipq_src = ip->ip_src;
fp->ipq_dst = ip->ip_dst;
fp->ipq_frags = m;
m->m_nextpkt = NULL;
goto done;
} else {
fp->ipq_nfrags++;
#ifdef MAC
mac_ipq_update(m, fp);
#endif
}
#define GETIP(m) ((struct ip*)((m)->m_pkthdr.header))
/*
* Handle ECN by comparing this segment with the first one;
* if CE is set, do not lose CE.
* drop if CE and not-ECT are mixed for the same packet.
*/
ecn = ip->ip_tos & IPTOS_ECN_MASK;
ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK;
if (ecn == IPTOS_ECN_CE) {
if (ecn0 == IPTOS_ECN_NOTECT)
goto dropfrag;
if (ecn0 != IPTOS_ECN_CE)
GETIP(fp->ipq_frags)->ip_tos |= IPTOS_ECN_CE;
}
if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT)
goto dropfrag;
/*
* Find a segment which begins after this one does.
*/
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
if (ntohs(GETIP(q)->ip_off) > ntohs(ip->ip_off))
break;
/*
* If there is a preceding segment, it may provide some of
* our data already. If so, drop the data from the incoming
* segment. If it provides all of our data, drop us, otherwise
* stick new segment in the proper place.
*
* If some of the data is dropped from the preceding
* segment, then it's checksum is invalidated.
*/
if (p) {
i = ntohs(GETIP(p)->ip_off) + ntohs(GETIP(p)->ip_len) -
ntohs(ip->ip_off);
if (i > 0) {