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8f134647ca
freebsd-dev/sys/netinet/ip_input.c
Gleb Smirnoff 8f134647ca Switch the entire IPv4 stack to keep the IP packet header 
in network byte order. Any host byte order processing is
done in local variables and host byte order values are
never[1] written to a packet.

  After this change a packet processed by the stack isn't
modified at all[2] except for TTL.

  After this change a network stack hacker doesn't need to
scratch his head trying to figure out what is the byte order
at the given place in the stack.

[1] One exception still remains. The raw sockets convert host
byte order before pass a packet to an application. Probably
this would remain for ages for compatibility.

[2] The ip_input() still subtructs header len from ip->ip_len,
but this is planned to be fixed soon.

Reviewed by:	luigi, Maxim Dounin <mdounin mdounin.ru>
Tested by:	ray, Olivier Cochard-Labbe <olivier cochard.me>
2012-10-22 21:09:03 +00:00

1767 lines
45 KiB
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Raw Blame History

/*-
* 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;
#ifdef IPFIREWALL_FORWARD
if (m->m_flags & M_FASTFWD_OURS) {
m->m_flags &= ~M_FASTFWD_OURS;
goto ours;
}
if ((dchg = (m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL)) != 0) {
/*
* Directly ship the packet on. This allows forwarding
* packets originally destined to us to some other directly
* connected host.
*/
ip_forward(m, dchg);
return;
}
#endif /* IPFIREWALL_FORWARD */
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;
ip_len = ntohs(ip->ip_len);
}
/*
* Further protocols expect the packet length to be w/o the
* IP header.
*/
ip->ip_len = htons(ip_len - hlen);
#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 (ntohs(ip->ip_len) == 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) {
if (i >= ntohs(ip->ip_len))
goto dropfrag;
m_adj(m, i);
m->m_pkthdr.csum_flags = 0;
ip->ip_off = htons(ntohs(ip->ip_off) + i);
ip->ip_len = htons(ntohs(ip->ip_len) - i);
}
m->m_nextpkt = p->m_nextpkt;
p->m_nextpkt = m;
} else {
m->m_nextpkt = fp->ipq_frags;
fp->ipq_frags = m;
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
for (; q != NULL && ntohs(ip->ip_off) + ntohs(ip->ip_len) >
ntohs(GETIP(q)->ip_off); q = nq) {
i = (ntohs(ip->ip_off) + ntohs(ip->ip_len)) -
ntohs(GETIP(q)->ip_off);
if (i < ntohs(GETIP(q)->ip_len)) {
GETIP(q)->ip_len = htons(ntohs(GETIP(q)->ip_len) - i);
GETIP(q)->ip_off = htons(ntohs(GETIP(q)->ip_off) + i);
m_adj(q, i);
q->m_pkthdr.csum_flags = 0;
break;
}
nq = q->m_nextpkt;
m->m_nextpkt = nq;
IPSTAT_INC(ips_fragdropped);
fp->ipq_nfrags--;
m_freem(q);
}
/*
* Check for complete reassembly and perform frag per packet
* limiting.
*
* Frag limiting is performed here so that the nth frag has
* a chance to complete the packet before we drop the packet.
* As a result, n+1 frags are actually allowed per packet, but
* only n will ever be stored. (n = maxfragsperpacket.)
*
*/
next = 0;
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) {
if (ntohs(GETIP(q)->ip_off) != next) {
if (fp->ipq_nfrags > V_maxfragsperpacket) {
IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
ip_freef(head, fp);
}
goto done;
}
next += ntohs(GETIP(q)->ip_len);
}
/* Make sure the last packet didn't have the IP_MF flag */
if (p->m_flags & M_FRAG) {
if (fp->ipq_nfrags > V_maxfragsperpacket) {
IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
ip_freef(head, fp);
}
goto done;
}
/*
* Reassembly is complete. Make sure the packet is a sane size.
*/
q = fp->ipq_frags;
ip = GETIP(q);
if (next + (ip->ip_hl << 2) > IP_MAXPACKET) {
IPSTAT_INC(ips_toolong);
IPSTAT_ADD(ips_fragdropped, fp->ipq_nfrags);
ip_freef(head, fp);
goto done;
}
/*
* Concatenate fragments.
*/
m = q;
t = m->m_next;
m->m_next = NULL;
m_cat(m, t);
nq = q->m_nextpkt;
q->m_nextpkt = NULL;
for (q = nq; q != NULL; q = nq) {
nq = q->m_nextpkt;
q->m_nextpkt = NULL;
m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags;
m->m_pkthdr.csum_data += q->m_pkthdr.csum_data;
m_cat(m, q);
}
/*
* In order to do checksumming faster we do 'end-around carry' here
* (and not in for{} loop), though it implies we are not going to
* reassemble more than 64k fragments.
*/
m->m_pkthdr.csum_data =
(m->m_pkthdr.csum_data & 0xffff) + (m->m_pkthdr.csum_data >> 16);
#ifdef MAC
mac_ipq_reassemble(fp, m);
mac_ipq_destroy(fp);
#endif
/*
* Create header for new ip packet by modifying header of first
* packet; dequeue and discard fragment reassembly header.
* Make header visible.
*/
ip->ip_len = htons((ip->ip_hl << 2) + next);
ip->ip_src = fp->ipq_src;
ip->ip_dst = fp->ipq_dst;
TAILQ_REMOVE(head, fp, ipq_list);
V_nipq--;
uma_zfree(V_ipq_zone, fp);
m->m_len += (ip->ip_hl << 2);
m->m_data -= (ip->ip_hl << 2);
/* some debugging cruft by sklower, below, will go away soon */
if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */
m_fixhdr(m);
IPSTAT_INC(ips_reassembled);
IPQ_UNLOCK();
return (m);
dropfrag:
IPSTAT_INC(ips_fragdropped);
if (fp != NULL)
fp->ipq_nfrags--;
m_freem(m);
done:
IPQ_UNLOCK();
return (NULL);
#undef GETIP
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
static void
ip_freef(struct ipqhead *fhp, struct ipq *fp)
{
struct mbuf *q;
IPQ_LOCK_ASSERT();
while (fp->ipq_frags) {
q = fp->ipq_frags;
fp->ipq_frags = q->m_nextpkt;
m_freem(q);
}
TAILQ_REMOVE(fhp, fp, ipq_list);
uma_zfree(V_ipq_zone, fp);
V_nipq--;
}
/*
* IP timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
void
ip_slowtimo(void)
{
VNET_ITERATOR_DECL(vnet_iter);
struct ipq *fp;
int i;
VNET_LIST_RLOCK_NOSLEEP();
IPQ_LOCK();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
for (i = 0; i < IPREASS_NHASH; i++) {
for(fp = TAILQ_FIRST(&V_ipq[i]); fp;) {
struct ipq *fpp;
fpp = fp;
fp = TAILQ_NEXT(fp, ipq_list);
if(--fpp->ipq_ttl == 0) {
IPSTAT_ADD(ips_fragtimeout,
fpp->ipq_nfrags);
ip_freef(&V_ipq[i], fpp);
}
}
}
/*
* If we are over the maximum number of fragments
* (due to the limit being lowered), drain off
* enough to get down to the new limit.
*/
if (V_maxnipq >= 0 && V_nipq > V_maxnipq) {
for (i = 0; i < IPREASS_NHASH; i++) {
while (V_nipq > V_maxnipq &&
!TAILQ_EMPTY(&V_ipq[i])) {
IPSTAT_ADD(ips_fragdropped,
TAILQ_FIRST(&V_ipq[i])->ipq_nfrags);
ip_freef(&V_ipq[i],
TAILQ_FIRST(&V_ipq[i]));
}
}
}
CURVNET_RESTORE();
}
IPQ_UNLOCK();
VNET_LIST_RUNLOCK_NOSLEEP();
}
/*
* Drain off all datagram fragments.
*/
static void
ip_drain_locked(void)
{
int i;
IPQ_LOCK_ASSERT();
for (i = 0; i < IPREASS_NHASH; i++) {
while(!TAILQ_EMPTY(&V_ipq[i])) {
IPSTAT_ADD(ips_fragdropped,
TAILQ_FIRST(&V_ipq[i])->ipq_nfrags);
ip_freef(&V_ipq[i], TAILQ_FIRST(&V_ipq[i]));
}
}
}
void
ip_drain(void)
{
VNET_ITERATOR_DECL(vnet_iter);
VNET_LIST_RLOCK_NOSLEEP();
IPQ_LOCK();
VNET_FOREACH(vnet_iter) {
CURVNET_SET(vnet_iter);
ip_drain_locked();
CURVNET_RESTORE();
}
IPQ_UNLOCK();
VNET_LIST_RUNLOCK_NOSLEEP();
in_rtqdrain();
}
/*
* The protocol to be inserted into ip_protox[] must be already registered
* in inetsw[], either statically or through pf_proto_register().
*/
int
ipproto_register(short ipproto)
{
struct protosw *pr;
/* Sanity checks. */
if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
return (EPROTONOSUPPORT);
/*
* The protocol slot must not be occupied by another protocol
* already. An index pointing to IPPROTO_RAW is unused.
*/
pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
if (pr == NULL)
return (EPFNOSUPPORT);
if (ip_protox[ipproto] != pr - inetsw) /* IPPROTO_RAW */
return (EEXIST);
/* Find the protocol position in inetsw[] and set the index. */
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) {
ip_protox[pr->pr_protocol] = pr - inetsw;
return (0);
}
}
return (EPROTONOSUPPORT);
}
int
ipproto_unregister(short ipproto)
{
struct protosw *pr;
/* Sanity checks. */
if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
return (EPROTONOSUPPORT);
/* Check if the protocol was indeed registered. */
pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
if (pr == NULL)
return (EPFNOSUPPORT);
if (ip_protox[ipproto] == pr - inetsw) /* IPPROTO_RAW */
return (ENOENT);
/* Reset the protocol slot to IPPROTO_RAW. */
ip_protox[ipproto] = pr - inetsw;
return (0);
}
/*
* Given address of next destination (final or next hop), return (referenced)
* internet address info of interface to be used to get there.
*/
struct in_ifaddr *
ip_rtaddr(struct in_addr dst, u_int fibnum)
{
struct route sro;
struct sockaddr_in *sin;
struct in_ifaddr *ia;
bzero(&sro, sizeof(sro));
sin = (struct sockaddr_in *)&sro.ro_dst;
sin->sin_family = AF_INET;
sin->sin_len = sizeof(*sin);
sin->sin_addr = dst;
in_rtalloc_ign(&sro, 0, fibnum);
if (sro.ro_rt == NULL)
return (NULL);
ia = ifatoia(sro.ro_rt->rt_ifa);
ifa_ref(&ia->ia_ifa);
RTFREE(sro.ro_rt);
return (ia);
}
u_char inetctlerrmap[PRC_NCMDS] = {
0, 0, 0, 0,
0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
EMSGSIZE, EHOSTUNREACH, 0, 0,
0, 0, EHOSTUNREACH, 0,
ENOPROTOOPT, ECONNREFUSED
};
/*
* Forward a packet. If some error occurs return the sender
* an icmp packet. Note we can't always generate a meaningful
* icmp message because icmp doesn't have a large enough repertoire
* of codes and types.
*
* If not forwarding, just drop the packet. This could be confusing
* if ipforwarding was zero but some routing protocol was advancing
* us as a gateway to somewhere. However, we must let the routing
* protocol deal with that.
*
* The srcrt parameter indicates whether the packet is being forwarded
* via a source route.
*/
void
ip_forward(struct mbuf *m, int srcrt)
{
struct ip *ip = mtod(m, struct ip *);
struct in_ifaddr *ia;
struct mbuf *mcopy;
struct in_addr dest;
struct route ro;
int error, type = 0, code = 0, mtu = 0;
if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
IPSTAT_INC(ips_cantforward);
m_freem(m);
return;
}
#ifdef IPSTEALTH
if (!V_ipstealth) {
#endif
if (ip->ip_ttl <= IPTTLDEC) {
icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS,
0, 0);
return;
}
#ifdef IPSTEALTH
}
#endif
ia = ip_rtaddr(ip->ip_dst, M_GETFIB(m));
#ifndef IPSEC
/*
* 'ia' may be NULL if there is no route for this destination.
* In case of IPsec, Don't discard it just yet, but pass it to
* ip_output in case of outgoing IPsec policy.
*/
if (!srcrt && ia == NULL) {
icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
return;
}
#endif
/*
* Save the IP header and at most 8 bytes of the payload,
* in case we need to generate an ICMP message to the src.
*
* XXX this can be optimized a lot by saving the data in a local
* buffer on the stack (72 bytes at most), and only allocating the
* mbuf if really necessary. The vast majority of the packets
* are forwarded without having to send an ICMP back (either
* because unnecessary, or because rate limited), so we are
* really we are wasting a lot of work here.
*
* We don't use m_copy() because it might return a reference
* to a shared cluster. Both this function and ip_output()
* assume exclusive access to the IP header in `m', so any
* data in a cluster may change before we reach icmp_error().
*/
MGETHDR(mcopy, M_DONTWAIT, m->m_type);
if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) {
/*
* It's probably ok if the pkthdr dup fails (because
* the deep copy of the tag chain failed), but for now
* be conservative and just discard the copy since
* code below may some day want the tags.
*/
m_free(mcopy);
mcopy = NULL;
}
if (mcopy != NULL) {
mcopy->m_len = min(ntohs(ip->ip_len), M_TRAILINGSPACE(mcopy));
mcopy->m_pkthdr.len = mcopy->m_len;
m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t));
}
#ifdef IPSTEALTH
if (!V_ipstealth) {
#endif
ip->ip_ttl -= IPTTLDEC;
#ifdef IPSTEALTH
}
#endif
/*
* If forwarding packet using same interface that it came in on,
* perhaps should send a redirect to sender to shortcut a hop.
* Only send redirect if source is sending directly to us,
* and if packet was not source routed (or has any options).
* Also, don't send redirect if forwarding using a default route
* or a route modified by a redirect.
*/
dest.s_addr = 0;
if (!srcrt && V_ipsendredirects &&
ia != NULL && ia->ia_ifp == m->m_pkthdr.rcvif) {
struct sockaddr_in *sin;
struct rtentry *rt;
bzero(&ro, sizeof(ro));
sin = (struct sockaddr_in *)&ro.ro_dst;
sin->sin_family = AF_INET;
sin->sin_len = sizeof(*sin);
sin->sin_addr = ip->ip_dst;
in_rtalloc_ign(&ro, 0, M_GETFIB(m));
rt = ro.ro_rt;
if (rt && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
satosin(rt_key(rt))->sin_addr.s_addr != 0) {
#define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
u_long src = ntohl(ip->ip_src.s_addr);
if (RTA(rt) &&
(src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
if (rt->rt_flags & RTF_GATEWAY)
dest.s_addr = satosin(rt->rt_gateway)->sin_addr.s_addr;
else
dest.s_addr = ip->ip_dst.s_addr;
/* Router requirements says to only send host redirects */
type = ICMP_REDIRECT;
code = ICMP_REDIRECT_HOST;
}
}
if (rt)
RTFREE(rt);
}
/*
* Try to cache the route MTU from ip_output so we can consider it for
* the ICMP_UNREACH_NEEDFRAG "Next-Hop MTU" field described in RFC1191.
*/
bzero(&ro, sizeof(ro));
error = ip_output(m, NULL, &ro, IP_FORWARDING, NULL, NULL);
if (error == EMSGSIZE && ro.ro_rt)
mtu = ro.ro_rt->rt_rmx.rmx_mtu;
RO_RTFREE(&ro);
if (error)
IPSTAT_INC(ips_cantforward);
else {
IPSTAT_INC(ips_forward);
if (type)
IPSTAT_INC(ips_redirectsent);
else {
if (mcopy)
m_freem(mcopy);
if (ia != NULL)
ifa_free(&ia->ia_ifa);
return;
}
}
if (mcopy == NULL) {
if (ia != NULL)
ifa_free(&ia->ia_ifa);
return;
}
switch (error) {
case 0: /* forwarded, but need redirect */
/* type, code set above */
break;
case ENETUNREACH:
case EHOSTUNREACH:
case ENETDOWN:
case EHOSTDOWN:
default:
type = ICMP_UNREACH;
code = ICMP_UNREACH_HOST;
break;
case EMSGSIZE:
type = ICMP_UNREACH;
code = ICMP_UNREACH_NEEDFRAG;
#ifdef IPSEC
/*
* If IPsec is configured for this path,
* override any possibly mtu value set by ip_output.
*/
mtu = ip_ipsec_mtu(mcopy, mtu);
#endif /* IPSEC */
/*
* If the MTU was set before make sure we are below the
* interface MTU.
* If the MTU wasn't set before use the interface mtu or
* fall back to the next smaller mtu step compared to the
* current packet size.
*/
if (mtu != 0) {
if (ia != NULL)
mtu = min(mtu, ia->ia_ifp->if_mtu);
} else {
if (ia != NULL)
mtu = ia->ia_ifp->if_mtu;
else
mtu = ip_next_mtu(ntohs(ip->ip_len), 0);
}
IPSTAT_INC(ips_cantfrag);
break;
case ENOBUFS:
/*
* A router should not generate ICMP_SOURCEQUENCH as
* required in RFC1812 Requirements for IP Version 4 Routers.
* Source quench could be a big problem under DoS attacks,
* or if the underlying interface is rate-limited.
* Those who need source quench packets may re-enable them
* via the net.inet.ip.sendsourcequench sysctl.
*/
if (V_ip_sendsourcequench == 0) {
m_freem(mcopy);
if (ia != NULL)
ifa_free(&ia->ia_ifa);
return;
} else {
type = ICMP_SOURCEQUENCH;
code = 0;
}
break;
case EACCES: /* ipfw denied packet */
m_freem(mcopy);
if (ia != NULL)
ifa_free(&ia->ia_ifa);
return;
}
if (ia != NULL)
ifa_free(&ia->ia_ifa);
icmp_error(mcopy, type, code, dest.s_addr, mtu);
}
void
ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
struct mbuf *m)
{
if (inp->inp_socket->so_options & (SO_BINTIME | SO_TIMESTAMP)) {
struct bintime bt;
bintime(&bt);
if (inp->inp_socket->so_options & SO_BINTIME) {
*mp = sbcreatecontrol((caddr_t) &bt, sizeof(bt),
SCM_BINTIME, SOL_SOCKET);
if (*mp)
mp = &(*mp)->m_next;
}
if (inp->inp_socket->so_options & SO_TIMESTAMP) {
struct timeval tv;
bintime2timeval(&bt, &tv);
*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
SCM_TIMESTAMP, SOL_SOCKET);
if (*mp)
mp = &(*mp)->m_next;
}
}
if (inp->inp_flags & INP_RECVDSTADDR) {
*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
if (inp->inp_flags & INP_RECVTTL) {
*mp = sbcreatecontrol((caddr_t) &ip->ip_ttl,
sizeof(u_char), IP_RECVTTL, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
#ifdef notyet
/* XXX
* Moving these out of udp_input() made them even more broken
* than they already were.
*/
/* options were tossed already */
if (inp->inp_flags & INP_RECVOPTS) {
*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
/* ip_srcroute doesn't do what we want here, need to fix */
if (inp->inp_flags & INP_RECVRETOPTS) {
*mp = sbcreatecontrol((caddr_t) ip_srcroute(m),
sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
#endif
if (inp->inp_flags & INP_RECVIF) {
struct ifnet *ifp;
struct sdlbuf {
struct sockaddr_dl sdl;
u_char pad[32];
} sdlbuf;
struct sockaddr_dl *sdp;
struct sockaddr_dl *sdl2 = &sdlbuf.sdl;
if (((ifp = m->m_pkthdr.rcvif))
&& ( ifp->if_index && (ifp->if_index <= V_if_index))) {
sdp = (struct sockaddr_dl *)ifp->if_addr->ifa_addr;
/*
* Change our mind and don't try copy.
*/
if ((sdp->sdl_family != AF_LINK)
|| (sdp->sdl_len > sizeof(sdlbuf))) {
goto makedummy;
}
bcopy(sdp, sdl2, sdp->sdl_len);
} else {
makedummy:
sdl2->sdl_len
= offsetof(struct sockaddr_dl, sdl_data[0]);
sdl2->sdl_family = AF_LINK;
sdl2->sdl_index = 0;
sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0;
}
*mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len,
IP_RECVIF, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
if (inp->inp_flags & INP_RECVTOS) {
*mp = sbcreatecontrol((caddr_t) &ip->ip_tos,
sizeof(u_char), IP_RECVTOS, IPPROTO_IP);
if (*mp)
mp = &(*mp)->m_next;
}
}
/*
* XXXRW: Multicast routing code in ip_mroute.c is generally MPSAFE, but the
* ip_rsvp and ip_rsvp_on variables need to be interlocked with rsvp_on
* locking. This code remains in ip_input.c as ip_mroute.c is optionally
* compiled.
*/
static VNET_DEFINE(int, ip_rsvp_on);
VNET_DEFINE(struct socket *, ip_rsvpd);
#define V_ip_rsvp_on VNET(ip_rsvp_on)
int
ip_rsvp_init(struct socket *so)
{
if (so->so_type != SOCK_RAW ||
so->so_proto->pr_protocol != IPPROTO_RSVP)
return EOPNOTSUPP;
if (V_ip_rsvpd != NULL)
return EADDRINUSE;
V_ip_rsvpd = so;
/*
* This may seem silly, but we need to be sure we don't over-increment
* the RSVP counter, in case something slips up.
*/
if (!V_ip_rsvp_on) {
V_ip_rsvp_on = 1;
V_rsvp_on++;
}
return 0;
}
int
ip_rsvp_done(void)
{
V_ip_rsvpd = NULL;
/*
* This may seem silly, but we need to be sure we don't over-decrement
* the RSVP counter, in case something slips up.
*/
if (V_ip_rsvp_on) {
V_ip_rsvp_on = 0;
V_rsvp_on--;
}
return 0;
}
void
rsvp_input(struct mbuf *m, int off) /* XXX must fixup manually */
{
if (rsvp_input_p) { /* call the real one if loaded */
rsvp_input_p(m, off);
return;
}
/* Can still get packets with rsvp_on = 0 if there is a local member
* of the group to which the RSVP packet is addressed. But in this
* case we want to throw the packet away.
*/
if (!V_rsvp_on) {
m_freem(m);
return;
}
if (V_ip_rsvpd != NULL) {
rip_input(m, off);
return;
}
/* Drop the packet */
m_freem(m);
}
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