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freebsd-nq/lib/libalias/alias_nbt.c
Matthew Dillon 374fad8b17 Reviewed by: freebsd-current 
Add bounds checking to netbios NS packet resolving code.  This should
    prevent natd from crashing on badly formed netbios packets (as might be
    heard when the machine is sitting on a cable modem or certain DSL
    networks), and also closes potential security holes that might have
    exploited the lack of bounds checking in the previous version of the
    code.
1998-12-14 02:25:32 +00:00

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/*
* Written by Atsushi Murai <amurai@spec.co.jp>
*
* Copyright (C) 1998, System Planning and Engineering Co. 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 System Planning and Engineering Co. The name of the
* SPEC 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.
*
* $Id: alias_nbt.c,v 1.1 1998/05/24 03:03:10 amurai Exp $
*
* TODO:
* oClean up.
* oConsidering for word alignment for other platform.
*/
/*
alias_nbt.c performs special processing for NetBios over TCP/IP
sessions by UDP.
Initial version: May, 1998 (Atsushi Murai <amurai@spec.co.jp>)
See HISTORY file for record of revisions.
*/
/* Includes */
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <netinet/tcp.h>
#include "alias_local.h"
#define ADJUST_CHECKSUM(acc, cksum) { \
acc += cksum; \
if (acc < 0) \
{ \
acc = -acc; \
acc = (acc >> 16) + (acc & 0xffff); \
acc += acc >> 16; \
cksum = (u_short) ~acc; \
} \
else \
{ \
acc = (acc >> 16) + (acc & 0xffff); \
acc += acc >> 16; \
cksum = (u_short) acc; \
} \
}
typedef struct {
struct in_addr oldaddr;
u_short oldport;
struct in_addr newaddr;
u_short newport;
u_short *uh_sum;
} NBTArguments;
typedef struct {
unsigned char type;
unsigned char flags;
u_short id;
struct in_addr source_ip;
u_short source_port;
u_short len;
u_short offset;
} NbtDataHeader;
#define OpQuery 0
#define OpUnknown 4
#define OpRegist 5
#define OpRelease 6
#define OpWACK 7
#define OpRefresh 8
typedef struct {
u_short nametrid;
u_short dir:1, opcode:4, nmflags:7, rcode:4;
u_short qdcount;
u_short ancount;
u_short nscount;
u_short arcount;
} NbtNSHeader;
#define FMT_ERR 0x1
#define SRV_ERR 0x2
#define IMP_ERR 0x4
#define RFS_ERR 0x5
#define ACT_ERR 0x6
#define CFT_ERR 0x7
/*******************************************************************
* copy an IP address from one buffer to another *
*******************************************************************/
void putip(void *dest,void *src)
{
memcpy(dest,src,4);
}
void PrintRcode( u_char rcode ) {
switch (rcode) {
case FMT_ERR:
printf("\nFormat Error.");
case SRV_ERR:
printf("\nSever failure.");
case IMP_ERR:
printf("\nUnsupported request error.\n");
case RFS_ERR:
printf("\nRefused error.\n");
case ACT_ERR:
printf("\nActive error.\n");
case CFT_ERR:
printf("\nName in conflict error.\n");
default:
printf("\n???=%0x\n", rcode );
}
}
/* Handling Name field */
u_char *AliasHandleName ( u_char *p, char *pmax ) {
u_char *s;
u_char c;
int compress;
/* Following length field */
if (p == NULL || (char *)p >= pmax)
return(NULL);
if (*p & 0xc0 ) {
p = p + 2;
if ((char *)p > pmax)
return(NULL);
return ((u_char *)p);
}
while ( ( *p & 0x3f) != 0x00 ) {
s = p + 1;
if ( *p == 0x20 )
compress = 1;
else
compress = 0;
/* Get next length field */
p = (u_char *)(p + (*p & 0x3f) + 1);
if ((char *)p > pmax) {
p = NULL;
break;
}
#ifdef DEBUG
printf(":");
#endif
while (s < p) {
if ( compress == 1 ) {
c = (u_char )(((((*s & 0x0f) << 4) | (*(s+1) & 0x0f)) - 0x11));
#ifdef DEBUG
if (isprint( c ) )
printf("%c", c );
else
printf("<0x%02x>", c );
#endif
s +=2;
} else {
#ifdef DEBUG
printf("%c", *s);
#endif
s++;
}
}
#ifdef DEBUG
printf(":");
#endif
fflush(stdout);
}
/* Set up to out of Name field */
if (p == NULL || (char *)p >= pmax)
p = NULL;
else
p++;
return ((u_char *)p);
}
/*
* NetBios Datagram Handler (IP/UDP)
*/
#define DGM_DIRECT_UNIQ 0x10
#define DGM_DIRECT_GROUP 0x11
#define DGM_BROADCAST 0x12
#define DGM_ERROR 0x13
#define DGM_QUERY 0x14
#define DGM_POSITIVE_RES 0x15
#define DGM_NEGATIVE_RES 0x16
int AliasHandleUdpNbt(
struct ip *pip, /* IP packet to examine/patch */
struct alias_link *link,
struct in_addr *alias_address,
u_short alias_port
) {
struct udphdr * uh;
NbtDataHeader *ndh;
u_char *p = NULL;
char *pmax;
/* Calculate data length of UDP packet */
uh = (struct udphdr *) ((char *) pip + (pip->ip_hl << 2));
pmax = (char *)uh + ntohs( uh->uh_ulen );
ndh = (NbtDataHeader *)((char *)uh + (sizeof (struct udphdr)));
if ((char *)(ndh + 1) > pmax)
return(-1);
#ifdef DEBUG
printf("\nType=%02x,", ndh->type );
#endif
switch ( ndh->type ) {
case DGM_DIRECT_UNIQ:
case DGM_DIRECT_GROUP:
case DGM_BROADCAST:
p = (u_char *)ndh + 14;
p = AliasHandleName ( p, pmax ); /* Source Name */
p = AliasHandleName ( p, pmax ); /* Destination Name */
break;
case DGM_ERROR:
p = (u_char *)ndh + 11;
break;
case DGM_QUERY:
case DGM_POSITIVE_RES:
case DGM_NEGATIVE_RES:
p = (u_char *)ndh + 10;
p = AliasHandleName ( p, pmax ); /* Destination Name */
break;
}
if (p == NULL || (char *)p > pmax)
p = NULL;
#ifdef DEBUG
printf("%s:%d-->", inet_ntoa(ndh->source_ip), ntohs(ndh->source_port) );
#endif
/* Doing a IP address and Port number Translation */
if ( uh->uh_sum != 0 ) {
int acc;
u_short *sptr;
acc = ndh->source_port;
acc -= alias_port;
sptr = (u_short *) &(ndh->source_ip);
acc += *sptr++;
acc += *sptr;
sptr = (u_short *) alias_address;
acc -= *sptr++;
acc -= *sptr;
ADJUST_CHECKSUM(acc, uh->uh_sum)
}
ndh->source_ip = *alias_address;
ndh->source_port = alias_port;
#ifdef DEBUG
printf("%s:%d\n", inet_ntoa(ndh->source_ip), ntohs(ndh->source_port) );
fflush(stdout);
#endif
return((p == NULL) ? -1 : 0);
}
/* Question Section */
#define QS_TYPE_NB 0x0020
#define QS_TYPE_NBSTAT 0x0021
#define QS_CLAS_IN 0x0001
typedef struct {
u_short type; /* The type of Request */
u_short class; /* The class of Request */
} NBTNsQuestion;
u_char *
AliasHandleQuestion(
u_short count,
NBTNsQuestion *q,
char *pmax,
NBTArguments *nbtarg)
{
while ( count != 0 ) {
/* Name Filed */
q = (NBTNsQuestion *)AliasHandleName((u_char *)q, pmax);
if (q == NULL || (char *)(q + 1) > pmax) {
q = NULL;
break;
}
/* Type and Class filed */
switch ( ntohs(q->type) ) {
case QS_TYPE_NB:
case QS_TYPE_NBSTAT:
q= q+1;
break;
default:
printf("\nUnknown Type on Question %0x\n", ntohs(q->type) );
break;
}
count--;
}
/* Set up to out of Question Section */
return ((u_char *)q);
}
/* Resource Record */
#define RR_TYPE_A 0x0001
#define RR_TYPE_NS 0x0002
#define RR_TYPE_NULL 0x000a
#define RR_TYPE_NB 0x0020
#define RR_TYPE_NBSTAT 0x0021
#define RR_CLAS_IN 0x0001
#define SizeOfNsResource 8
typedef struct {
u_short type;
u_short class;
unsigned int ttl;
u_short rdlen;
} NBTNsResource;
#define SizeOfNsRNB 6
typedef struct {
u_short g:1, ont:2, resv:13;
struct in_addr addr;
} NBTNsRNB;
u_char *
AliasHandleResourceNB(
NBTNsResource *q,
char *pmax,
NBTArguments *nbtarg)
{
NBTNsRNB *nb;
u_short bcount;
if (q == NULL || (char *)(q + 1) > pmax)
return(NULL);
/* Check out a length */
bcount = ntohs(q->rdlen);
/* Forward to Resource NB position */
nb = (NBTNsRNB *)((u_char *)q + SizeOfNsResource);
/* Processing all in_addr array */
#ifdef DEBUG
printf("NB rec[%s", inet_ntoa(nbtarg->oldaddr));
printf("->%s, %dbytes] ",inet_ntoa(nbtarg->newaddr ), bcount);
#endif
while ( nb != NULL && bcount != 0 ) {
if ((char *)(nb + 1) > pmax) {
nb = NULL;
break;
}
#ifdef DEBUG
printf("<%s>", inet_ntoa(nb->addr) );
#endif
if (!bcmp(&nbtarg->oldaddr,&nb->addr, sizeof(struct in_addr) ) ) {
if ( *nbtarg->uh_sum != 0 ) {
int acc;
u_short *sptr;
sptr = (u_short *) &(nb->addr);
acc = *sptr++;
acc += *sptr;
sptr = (u_short *) &(nbtarg->newaddr);
acc -= *sptr++;
acc -= *sptr;
ADJUST_CHECKSUM(acc, *nbtarg->uh_sum)
}
nb->addr = nbtarg->newaddr;
#ifdef DEBUG
printf("O");
#endif
}
#ifdef DEBUG
else {
printf(".");
}
#endif
nb=(NBTNsRNB *)((u_char *)nb + SizeOfNsRNB);
bcount -= SizeOfNsRNB;
}
if (nb == NULL || (char *)(nb + 1) > pmax) {
nb = NULL;
}
return ((u_char *)nb);
}
#define SizeOfResourceA 6
typedef struct {
struct in_addr addr;
} NBTNsResourceA;
u_char *
AliasHandleResourceA(
NBTNsResource *q,
char *pmax,
NBTArguments *nbtarg)
{
NBTNsResourceA *a;
u_short bcount;
if (q == NULL || (char *)(q + 1) > pmax)
return(NULL);
/* Forward to Resource A position */
a = (NBTNsResourceA *)( (u_char *)q + sizeof(NBTNsResource) );
/* Check out of length */
bcount = ntohs(q->rdlen);
/* Processing all in_addr array */
#ifdef DEBUG
printf("Arec [%s", inet_ntoa(nbtarg->oldaddr));
printf("->%s]",inet_ntoa(nbtarg->newaddr ));
#endif
while ( bcount != 0 ) {
if (a == NULL || (char *)(a + 1) > pmax)
return(NULL);
#ifdef DEBUG
printf("..%s", inet_ntoa(a->addr) );
#endif
if ( !bcmp(&nbtarg->oldaddr, &a->addr, sizeof(struct in_addr) ) ) {
if ( *nbtarg->uh_sum != 0 ) {
int acc;
u_short *sptr;
sptr = (u_short *) &(a->addr); /* Old */
acc = *sptr++;
acc += *sptr;
sptr = (u_short *) &nbtarg->newaddr; /* New */
acc -= *sptr++;
acc -= *sptr;
ADJUST_CHECKSUM(acc, *nbtarg->uh_sum)
}
a->addr = nbtarg->newaddr;
}
a++; /*XXXX*/
bcount -= SizeOfResourceA;
}
if (a == NULL || (char *)(a + 1) > pmax)
a = NULL;
return ((u_char *)a);
}
typedef struct {
u_short opcode:4, flags:8, resv:4;
} NBTNsResourceNULL;
u_char *
AliasHandleResourceNULL(
NBTNsResource *q,
char *pmax,
NBTArguments *nbtarg)
{
NBTNsResourceNULL *n;
u_short bcount;
if (q == NULL || (char *)(q + 1) > pmax)
return(NULL);
/* Forward to Resource NULL position */
n = (NBTNsResourceNULL *)( (u_char *)q + sizeof(NBTNsResource) );
/* Check out of length */
bcount = ntohs(q->rdlen);
/* Processing all in_addr array */
while ( bcount != 0 ) {
if ((char *)(n + 1) > pmax) {
n = NULL;
break;
}
n++;
bcount -= sizeof(NBTNsResourceNULL);
}
if ((char *)(n + 1) > pmax)
n = NULL;
return ((u_char *)n);
}
u_char *
AliasHandleResourceNS(
NBTNsResource *q,
char *pmax,
NBTArguments *nbtarg)
{
NBTNsResourceNULL *n;
u_short bcount;
if (q == NULL || (char *)(q + 1) > pmax)
return(NULL);
/* Forward to Resource NULL position */
n = (NBTNsResourceNULL *)( (u_char *)q + sizeof(NBTNsResource) );
/* Check out of length */
bcount = ntohs(q->rdlen);
/* Resource Record Name Filed */
q = (NBTNsResource *)AliasHandleName( (u_char *)n, pmax ); /* XXX */
if (q == NULL || (char *)((u_char *)n + bcount) > pmax)
return(NULL);
else
return ((u_char *)n + bcount);
}
typedef struct {
u_short numnames;
} NBTNsResourceNBSTAT;
u_char *
AliasHandleResourceNBSTAT(
NBTNsResource *q,
char *pmax,
NBTArguments *nbtarg)
{
NBTNsResourceNBSTAT *n;
u_short bcount;
if (q == NULL || (char *)(q + 1) > pmax)
return(NULL);
/* Forward to Resource NBSTAT position */
n = (NBTNsResourceNBSTAT *)( (u_char *)q + sizeof(NBTNsResource) );
/* Check out of length */
bcount = ntohs(q->rdlen);
if (q == NULL || (char *)((u_char *)n + bcount) > pmax)
return(NULL);
else
return ((u_char *)n + bcount);
}
u_char *
AliasHandleResource(
u_short count,
NBTNsResource *q,
char *pmax,
NBTArguments
*nbtarg)
{
while ( count != 0 ) {
/* Resource Record Name Filed */
q = (NBTNsResource *)AliasHandleName( (u_char *)q, pmax );
if (q == NULL || (char *)(q + 1) > pmax)
break;
#ifdef DEBUG
printf("type=%02x, count=%d\n", ntohs(q->type), count );
#endif
/* Type and Class filed */
switch ( ntohs(q->type) ) {
case RR_TYPE_NB:
q = (NBTNsResource *)AliasHandleResourceNB(
q,
pmax,
nbtarg
);
break;
case RR_TYPE_A:
q = (NBTNsResource *)AliasHandleResourceA(
q,
pmax,
nbtarg
);
break;
case RR_TYPE_NS:
q = (NBTNsResource *)AliasHandleResourceNS(
q,
pmax,
nbtarg
);
break;
case RR_TYPE_NULL:
q = (NBTNsResource *)AliasHandleResourceNULL(
q,
pmax,
nbtarg
);
break;
case RR_TYPE_NBSTAT:
q = (NBTNsResource *)AliasHandleResourceNBSTAT(
q,
pmax,
nbtarg
);
break;
default:
printf(
"\nUnknown Type of Resource %0x\n",
ntohs(q->type)
);
break;
}
count--;
}
fflush(stdout);
return ((u_char *)q);
}
int AliasHandleUdpNbtNS(
struct ip *pip, /* IP packet to examine/patch */
struct alias_link *link,
struct in_addr *alias_address,
u_short *alias_port,
struct in_addr *original_address,
u_short *original_port )
{
struct udphdr * uh;
NbtNSHeader * nsh;
u_char * p;
char *pmax;
NBTArguments nbtarg;
/* Set up Common Parameter */
nbtarg.oldaddr = *alias_address;
nbtarg.oldport = *alias_port;
nbtarg.newaddr = *original_address;
nbtarg.newport = *original_port;
/* Calculate data length of UDP packet */
uh = (struct udphdr *) ((char *) pip + (pip->ip_hl << 2));
nbtarg.uh_sum = &(uh->uh_sum);
nsh = (NbtNSHeader *)((char *)uh + (sizeof(struct udphdr)));
p = (u_char *)(nsh + 1);
pmax = (char *)uh + ntohs( uh->uh_ulen );
if ((char *)(nsh + 1) > pmax)
return(-1);
#ifdef DEBUG
printf(" [%s] ID=%02x, op=%01x, flag=%02x, rcode=%01x, qd=%04x"
", an=%04x, ns=%04x, ar=%04x, [%d]-->",
nsh->dir ? "Response": "Request",
nsh->nametrid,
nsh->opcode,
nsh->nmflags,
nsh->rcode,
ntohs(nsh->qdcount),
ntohs(nsh->ancount),
ntohs(nsh->nscount),
ntohs(nsh->arcount),
(u_char *)p -(u_char *)nsh
);
#endif
/* Question Entries */
if (ntohs(nsh->qdcount) !=0 ) {
p = AliasHandleQuestion(
ntohs(nsh->qdcount),
(NBTNsQuestion *)p,
pmax,
&nbtarg
);
}
/* Answer Resource Records */
if (ntohs(nsh->ancount) !=0 ) {
p = AliasHandleResource(
ntohs(nsh->ancount),
(NBTNsResource *)p,
pmax,
&nbtarg
);
}
/* Authority Resource Recodrs */
if (ntohs(nsh->nscount) !=0 ) {
p = AliasHandleResource(
ntohs(nsh->nscount),
(NBTNsResource *)p,
pmax,
&nbtarg
);
}
/* Additional Resource Recodrs */
if (ntohs(nsh->arcount) !=0 ) {
p = AliasHandleResource(
ntohs(nsh->arcount),
(NBTNsResource *)p,
pmax,
&nbtarg
);
}
#ifdef DEBUG
PrintRcode(nsh->rcode);
#endif
return ((p == NULL) ? -1 : 0);
}
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