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freebsd/usr.sbin/ppp/ip.c
Brian Somers 28149effa7 Support GRE packets 
Submitted by: Harry Starr <starr@gccs.com.au>
1999-09-30 07:23:13 +00:00

605 lines
17 KiB
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/*
* PPP IP Protocol Interface
*
* Written by Toshiharu OHNO (tony-o@iij.ad.jp)
*
* Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the Internet Initiative Japan. The name of the
* IIJ may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* $FreeBSD$
*
* TODO:
* o Return ICMP message for filterd packet
* and optionaly record it into log.
*/
#include <sys/param.h>
#if defined(__OpenBSD__) || defined(__NetBSD__)
#include <sys/socket.h>
#endif
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netinet/udp.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <sys/un.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include "layer.h"
#include "proto.h"
#include "mbuf.h"
#include "log.h"
#include "defs.h"
#include "timer.h"
#include "fsm.h"
#include "lqr.h"
#include "hdlc.h"
#include "throughput.h"
#include "iplist.h"
#include "slcompress.h"
#include "ipcp.h"
#include "filter.h"
#include "descriptor.h"
#include "lcp.h"
#include "ccp.h"
#include "link.h"
#include "mp.h"
#ifndef NORADIUS
#include "radius.h"
#endif
#include "bundle.h"
#include "tun.h"
#include "ip.h"
static const char *TcpFlags[] = { "FIN", "SYN", "RST", "PSH", "ACK", "URG" };
static __inline int
PortMatch(int op, u_short pport, u_short rport)
{
switch (op) {
case OP_EQ:
return (pport == rport);
case OP_GT:
return (pport > rport);
case OP_LT:
return (pport < rport);
default:
return (0);
}
}
/*
* Check a packet against a defined filter
* Returns 0 to accept the packet, non-zero to drop the packet
*
* If filtering is enabled, the initial fragment of a datagram must
* contain the complete protocol header, and subsequent fragments
* must not attempt to over-write it.
*/
static int
FilterCheck(const struct ip *pip, const struct filter *filter)
{
int gotinfo; /* true if IP payload decoded */
int cproto; /* P_* protocol type if (gotinfo) */
int estab, syn, finrst; /* TCP state flags if (gotinfo) */
u_short sport, dport; /* src, dest port from packet if (gotinfo) */
int n; /* filter rule to process */
int len; /* bytes used in dbuff */
int didname; /* true if filter header printed */
int match; /* true if condition matched */
const struct filterent *fp = filter->rule;
char dbuff[100];
if (fp->f_action == A_NONE)
return (0); /* No rule is given. Permit this packet */
/* Deny any packet fragment that tries to over-write the header.
* Since we no longer have the real header available, punt on the
* largest normal header - 20 bytes for TCP without options, rounded
* up to the next possible fragment boundary. Since the smallest
* `legal' MTU is 576, and the smallest recommended MTU is 296, any
* fragmentation within this range is dubious at best */
len = ntohs(pip->ip_off) & IP_OFFMASK; /* fragment offset */
if (len > 0) { /* Not first fragment within datagram */
if (len < (24 >> 3)) /* don't allow fragment to over-write header */
return (1);
/* permit fragments on in and out filter */
return (!filter->fragok);
}
cproto = gotinfo = estab = syn = finrst = didname = 0;
sport = dport = 0;
for (n = 0; n < MAXFILTERS; ) {
if (fp->f_action == A_NONE) {
n++;
fp++;
continue;
}
if (!didname) {
log_Printf(LogDEBUG, "%s filter:\n", filter->name);
didname = 1;
}
match = 0;
if (!((pip->ip_src.s_addr ^ fp->f_src.ipaddr.s_addr) &
fp->f_src.mask.s_addr) &&
!((pip->ip_dst.s_addr ^ fp->f_dst.ipaddr.s_addr) &
fp->f_dst.mask.s_addr)) {
if (fp->f_proto != P_NONE) {
if (!gotinfo) {
const char *ptop = (const char *) pip + (pip->ip_hl << 2);
const struct tcphdr *th;
const struct udphdr *uh;
const struct icmp *ih;
int datalen; /* IP datagram length */
datalen = ntohs(pip->ip_len) - (pip->ip_hl << 2);
switch (pip->ip_p) {
case IPPROTO_ICMP:
cproto = P_ICMP;
if (datalen < 8) /* ICMP must be at least 8 octets */
return (1);
ih = (const struct icmp *) ptop;
sport = ih->icmp_type;
estab = syn = finrst = -1;
if (log_IsKept(LogDEBUG))
snprintf(dbuff, sizeof dbuff, "sport = %d", sport);
break;
case IPPROTO_IGMP:
cproto = P_IGMP;
if (datalen < 8) /* IGMP uses 8-octet messages */
return (1);
estab = syn = finrst = -1;
sport = ntohs(0);
break;
#ifdef IPPROTO_GRE
case IPPROTO_GRE:
cproto = P_GRE;
if (datalen < 2) /* GRE uses 2-octet+ messages */
return (1);
estab = syn = finrst = -1;
sport = ntohs(0);
break;
#endif
#ifdef IPPROTO_OSPFIGP
case IPPROTO_OSPFIGP:
cproto = P_OSPF;
if (datalen < 8) /* IGMP uses 8-octet messages */
return (1);
estab = syn = finrst = -1;
sport = ntohs(0);
break;
#endif
case IPPROTO_UDP:
case IPPROTO_IPIP:
cproto = P_UDP;
if (datalen < 8) /* UDP header is 8 octets */
return (1);
uh = (const struct udphdr *) ptop;
sport = ntohs(uh->uh_sport);
dport = ntohs(uh->uh_dport);
estab = syn = finrst = -1;
if (log_IsKept(LogDEBUG))
snprintf(dbuff, sizeof dbuff, "sport = %d, dport = %d",
sport, dport);
break;
case IPPROTO_TCP:
cproto = P_TCP;
th = (const struct tcphdr *) ptop;
/* TCP headers are variable length. The following code
* ensures that the TCP header length isn't de-referenced if
* the datagram is too short
*/
if (datalen < 20 || datalen < (th->th_off << 2))
return (1);
sport = ntohs(th->th_sport);
dport = ntohs(th->th_dport);
estab = (th->th_flags & TH_ACK);
syn = (th->th_flags & TH_SYN);
finrst = (th->th_flags & (TH_FIN|TH_RST));
if (log_IsKept(LogDEBUG)) {
if (!estab)
snprintf(dbuff, sizeof dbuff,
"flags = %02x, sport = %d, dport = %d",
th->th_flags, sport, dport);
else
*dbuff = '\0';
}
break;
default:
return (1); /* We'll block unknown type of packet */
}
if (log_IsKept(LogDEBUG)) {
if (estab != -1) {
len = strlen(dbuff);
snprintf(dbuff + len, sizeof dbuff - len,
", estab = %d, syn = %d, finrst = %d",
estab, syn, finrst);
}
log_Printf(LogDEBUG, " Filter: proto = %s, %s\n",
filter_Proto2Nam(cproto), dbuff);
}
gotinfo = 1;
}
if (log_IsKept(LogDEBUG)) {
if (fp->f_srcop != OP_NONE) {
snprintf(dbuff, sizeof dbuff, ", src %s %d",
filter_Op2Nam(fp->f_srcop), fp->f_srcport);
len = strlen(dbuff);
} else
len = 0;
if (fp->f_dstop != OP_NONE) {
snprintf(dbuff + len, sizeof dbuff - len,
", dst %s %d", filter_Op2Nam(fp->f_dstop),
fp->f_dstport);
} else if (!len)
*dbuff = '\0';
log_Printf(LogDEBUG, " rule = %d: Address match, "
"check against proto %s%s, action = %s\n",
n, filter_Proto2Nam(fp->f_proto),
dbuff, filter_Action2Nam(fp->f_action));
}
if (cproto == fp->f_proto) {
if ((fp->f_srcop == OP_NONE ||
PortMatch(fp->f_srcop, sport, fp->f_srcport)) &&
(fp->f_dstop == OP_NONE ||
PortMatch(fp->f_dstop, dport, fp->f_dstport)) &&
(fp->f_estab == 0 || estab) &&
(fp->f_syn == 0 || syn) &&
(fp->f_finrst == 0 || finrst)) {
match = 1;
}
}
} else {
/* Address is matched and no protocol specified. Make a decision. */
log_Printf(LogDEBUG, " rule = %d: Address match, action = %s\n", n,
filter_Action2Nam(fp->f_action));
match = 1;
}
} else
log_Printf(LogDEBUG, " rule = %d: Address mismatch\n", n);
if (match != fp->f_invert) {
/* Take specified action */
if (fp->f_action < A_NONE)
fp = &filter->rule[n = fp->f_action];
else
return (fp->f_action != A_PERMIT);
} else {
n++;
fp++;
}
}
return (1); /* No rule is mached. Deny this packet */
}
#ifdef notdef
static void
IcmpError(struct ip *pip, int code)
{
struct mbuf *bp;
if (pip->ip_p != IPPROTO_ICMP) {
bp = mbuf_Alloc(cnt, MB_IPIN);
memcpy(MBUF_CTOP(bp), ptr, cnt);
vj_SendFrame(bp);
ipcp_AddOutOctets(cnt);
}
}
#endif
/*
* For debugging aid.
*/
int
PacketCheck(struct bundle *bundle, char *cp, int nb, struct filter *filter)
{
struct ip *pip;
struct tcphdr *th;
struct udphdr *uh;
struct icmp *icmph;
char *ptop;
int mask, len, n;
int pri = 0;
int logit, loglen;
char logbuf[200];
logit = log_IsKept(LogTCPIP) && filter->logok;
loglen = 0;
pip = (struct ip *) cp;
if (logit && loglen < sizeof logbuf) {
snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s ", filter->name);
loglen += strlen(logbuf + loglen);
}
ptop = (cp + (pip->ip_hl << 2));
switch (pip->ip_p) {
case IPPROTO_ICMP:
if (logit && loglen < sizeof logbuf) {
icmph = (struct icmp *) ptop;
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"ICMP: %s:%d ---> ", inet_ntoa(pip->ip_src), icmph->icmp_type);
loglen += strlen(logbuf + loglen);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"%s:%d", inet_ntoa(pip->ip_dst), icmph->icmp_type);
loglen += strlen(logbuf + loglen);
}
break;
case IPPROTO_UDP:
uh = (struct udphdr *) ptop;
if (pip->ip_tos == IPTOS_LOWDELAY)
pri++;
if ((ntohs(pip->ip_off) & IP_OFFMASK) == 0 &&
ipcp_IsUrgentUdpPort(&bundle->ncp.ipcp, ntohs(uh->uh_sport),
ntohs(uh->uh_dport)))
pri++;
if (logit && loglen < sizeof logbuf) {
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"UDP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport));
loglen += strlen(logbuf + loglen);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport));
loglen += strlen(logbuf + loglen);
}
break;
#ifdef IPPROTO_GRE
case IPPROTO_GRE:
if (logit && loglen < sizeof logbuf) {
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"GRE: %s ---> ", inet_ntoa(pip->ip_src));
loglen += strlen(logbuf + loglen);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"%s", inet_ntoa(pip->ip_dst));
loglen += strlen(logbuf + loglen);
}
break;
#endif
#ifdef IPPROTO_OSPFIGP
case IPPROTO_OSPFIGP:
if (logit && loglen < sizeof logbuf) {
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"OSPF: %s ---> ", inet_ntoa(pip->ip_src));
loglen += strlen(logbuf + loglen);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"%s", inet_ntoa(pip->ip_dst));
loglen += strlen(logbuf + loglen);
}
break;
#endif
case IPPROTO_IPIP:
if (logit && loglen < sizeof logbuf) {
uh = (struct udphdr *) ptop;
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"IPIP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport));
loglen += strlen(logbuf + loglen);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport));
loglen += strlen(logbuf + loglen);
}
break;
case IPPROTO_IGMP:
if (logit && loglen < sizeof logbuf) {
uh = (struct udphdr *) ptop;
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"IGMP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport));
loglen += strlen(logbuf + loglen);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport));
loglen += strlen(logbuf + loglen);
}
break;
case IPPROTO_TCP:
th = (struct tcphdr *) ptop;
if (pip->ip_tos == IPTOS_LOWDELAY)
pri++;
if ((ntohs(pip->ip_off) & IP_OFFMASK) == 0 &&
ipcp_IsUrgentTcpPort(&bundle->ncp.ipcp, ntohs(th->th_sport),
ntohs(th->th_dport)))
pri++;
if (logit && loglen < sizeof logbuf) {
len = ntohs(pip->ip_len) - (pip->ip_hl << 2) - (th->th_off << 2);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"TCP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(th->th_sport));
loglen += strlen(logbuf + loglen);
snprintf(logbuf + loglen, sizeof logbuf - loglen,
"%s:%d", inet_ntoa(pip->ip_dst), ntohs(th->th_dport));
loglen += strlen(logbuf + loglen);
n = 0;
for (mask = TH_FIN; mask != 0x40; mask <<= 1) {
if (th->th_flags & mask) {
snprintf(logbuf + loglen, sizeof logbuf - loglen, " %s", TcpFlags[n]);
loglen += strlen(logbuf + loglen);
}
n++;
}
snprintf(logbuf + loglen, sizeof logbuf - loglen,
" seq:%lx ack:%lx (%d/%d)",
(u_long)ntohl(th->th_seq), (u_long)ntohl(th->th_ack), len, nb);
loglen += strlen(logbuf + loglen);
if ((th->th_flags & TH_SYN) && nb > 40) {
u_short *sp;
ptop += 20;
sp = (u_short *) ptop;
if (ntohs(sp[0]) == 0x0204) {
snprintf(logbuf + loglen, sizeof logbuf - loglen,
" MSS = %d", ntohs(sp[1]));
loglen += strlen(logbuf + loglen);
}
}
}
break;
}
if (FilterCheck(pip, filter)) {
if (logit)
log_Printf(LogTCPIP, "%s - BLOCKED\n", logbuf);
#ifdef notdef
if (direction == 0)
IcmpError(pip, pri);
#endif
return (-1);
} else {
/* Check Keep Alive filter */
if (logit) {
if (FilterCheck(pip, &bundle->filter.alive))
log_Printf(LogTCPIP, "%s - NO KEEPALIVE\n", logbuf);
else
log_Printf(LogTCPIP, "%s\n", logbuf);
}
return (pri);
}
}
struct mbuf *
ip_Input(struct bundle *bundle, struct link *l, struct mbuf *bp)
{
int nb, nw;
struct tun_data tun;
struct ip *pip;
if (bundle->ncp.ipcp.fsm.state != ST_OPENED) {
log_Printf(LogWARN, "ip_Input: IPCP not open - packet dropped\n");
mbuf_Free(bp);
return NULL;
}
mbuf_SetType(bp, MB_IPIN);
tun_fill_header(tun, AF_INET);
nb = mbuf_Length(bp);
if (nb > sizeof tun.data) {
log_Printf(LogWARN, "ip_Input: %s: Packet too large (got %d, max %d)\n",
l->name, nb, (int)(sizeof tun.data));
mbuf_Free(bp);
return NULL;
}
mbuf_Read(bp, tun.data, nb);
if (PacketCheck(bundle, tun.data, nb, &bundle->filter.in) < 0)
return NULL;
pip = (struct ip *)tun.data;
if (!FilterCheck(pip, &bundle->filter.alive))
bundle_StartIdleTimer(bundle);
ipcp_AddInOctets(&bundle->ncp.ipcp, nb);
nb += sizeof tun - sizeof tun.data;
nw = write(bundle->dev.fd, &tun, nb);
if (nw != nb) {
if (nw == -1)
log_Printf(LogERROR, "ip_Input: %s: wrote %d, got %s\n",
l->name, nb, strerror(errno));
else
log_Printf(LogERROR, "ip_Input: %s: wrote %d, got %d\n", l->name, nb, nw);
}
return NULL;
}
void
ip_Enqueue(struct ipcp *ipcp, int pri, char *ptr, int count)
{
struct mbuf *bp;
if (pri < 0 || pri >= IPCP_QUEUES(ipcp))
log_Printf(LogERROR, "Can't store in ip queue %d\n", pri);
else {
/*
* We allocate an extra 6 bytes, four at the front and two at the end.
* This is an optimisation so that we need to do less work in
* mbuf_Prepend() in acf_LayerPush() and proto_LayerPush() and
* appending in hdlc_LayerPush().
*/
bp = mbuf_Alloc(count + 6, MB_IPOUT);
bp->offset += 4;
bp->cnt -= 6;
memcpy(MBUF_CTOP(bp), ptr, count);
mbuf_Enqueue(ipcp->Queue + pri, bp);
}
}
void
ip_DeleteQueue(struct ipcp *ipcp)
{
struct mqueue *queue;
for (queue = ipcp->Queue; queue < ipcp->Queue + IPCP_QUEUES(ipcp); queue++)
while (queue->top)
mbuf_Free(mbuf_Dequeue(queue));
}
int
ip_QueueLen(struct ipcp *ipcp)
{
struct mqueue *queue;
int result = 0;
for (queue = ipcp->Queue; queue < ipcp->Queue + IPCP_QUEUES(ipcp); queue++)
result += queue->qlen;
return result;
}
int
ip_PushPacket(struct link *l, struct bundle *bundle)
{
struct ipcp *ipcp = &bundle->ncp.ipcp;
struct mqueue *queue;
struct mbuf *bp;
struct ip *pip;
int cnt;
if (ipcp->fsm.state != ST_OPENED)
return 0;
queue = ipcp->Queue + IPCP_QUEUES(ipcp) - 1;
do {
if (queue->top) {
bp = mbuf_Contiguous(mbuf_Dequeue(queue));
cnt = mbuf_Length(bp);
pip = (struct ip *)MBUF_CTOP(bp);
if (!FilterCheck(pip, &bundle->filter.alive))
bundle_StartIdleTimer(bundle);
link_PushPacket(l, bp, bundle, 0, PROTO_IP);
ipcp_AddOutOctets(ipcp, cnt);
return 1;
}
} while (queue-- != ipcp->Queue);
return 0;
}
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