*
* Basic SNMP Application Layer Gateway
*
- * This IP NAT module is intended for use with SNMP network
- * discovery and monitoring applications where target networks use
+ * This IP NAT module is intended for use with SNMP network
+ * discovery and monitoring applications where target networks use
* conflicting private address realms.
*
- * Static NAT is used to remap the networks from the view of the network
+ * Static NAT is used to remap the networks from the view of the network
* management system at the IP layer, and this module remaps some application
* layer addresses to match.
*
* More information on ALG and associated issues can be found in
* RFC 2962
*
- * The ASB.1/BER parsing code is derived from the gxsnmp package by Gregory
+ * The ASB.1/BER parsing code is derived from the gxsnmp package by Gregory
* McLean & Jochen Friedrich, stripped down for use in the kernel.
*
* Copyright (c) 2000 RP Internet (www.rpi.net.au).
static int debug;
static DEFINE_SPINLOCK(snmp_lock);
-/*
- * Application layer address mapping mimics the NAT mapping, but
+/*
+ * Application layer address mapping mimics the NAT mapping, but
* only for the first octet in this case (a more flexible system
* can be implemented if needed).
*/
u_int8_t to;
};
-
+
/*****************************************************************************
*
* Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
#define ASN1_ERR_DEC_LENGTH_MISMATCH 4
#define ASN1_ERR_DEC_BADVALUE 5
-/*
+/*
* ASN.1 context.
*/
struct asn1_ctx
unsigned char *data;
unsigned int len;
};
-
+
static void asn1_open(struct asn1_ctx *ctx,
- unsigned char *buf,
- unsigned int len)
+ unsigned char *buf,
+ unsigned int len)
{
ctx->begin = buf;
ctx->end = buf + len;
static unsigned char asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
{
unsigned char ch;
-
+
*tag = 0;
-
+
do
{
if (!asn1_octet_decode(ctx, &ch))
return 1;
}
-static unsigned char asn1_id_decode(struct asn1_ctx *ctx,
- unsigned int *cls,
- unsigned int *con,
- unsigned int *tag)
+static unsigned char asn1_id_decode(struct asn1_ctx *ctx,
+ unsigned int *cls,
+ unsigned int *con,
+ unsigned int *tag)
{
unsigned char ch;
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*cls = (ch & 0xC0) >> 6;
*con = (ch & 0x20) >> 5;
*tag = (ch & 0x1F);
-
+
if (*tag == 0x1F) {
if (!asn1_tag_decode(ctx, tag))
return 0;
}
static unsigned char asn1_length_decode(struct asn1_ctx *ctx,
- unsigned int *def,
- unsigned int *len)
+ unsigned int *def,
+ unsigned int *len)
{
unsigned char ch, cnt;
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
if (ch == 0x80)
*def = 0;
else {
*def = 1;
-
+
if (ch < 0x80)
*len = ch;
else {
cnt = (unsigned char) (ch & 0x7F);
*len = 0;
-
+
while (cnt > 0) {
if (!asn1_octet_decode(ctx, &ch))
return 0;
}
static unsigned char asn1_header_decode(struct asn1_ctx *ctx,
- unsigned char **eoc,
- unsigned int *cls,
- unsigned int *con,
- unsigned int *tag)
+ unsigned char **eoc,
+ unsigned int *cls,
+ unsigned int *con,
+ unsigned int *tag)
{
unsigned int def, len;
-
+
if (!asn1_id_decode(ctx, cls, con, tag))
return 0;
-
+
def = len = 0;
if (!asn1_length_decode(ctx, &def, &len))
return 0;
-
+
if (def)
*eoc = ctx->pointer + len;
else
static unsigned char asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
{
unsigned char ch;
-
+
if (eoc == 0) {
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
if (ch != 0x00) {
ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
return 0;
}
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
if (ch != 0x00) {
ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
return 0;
}
static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- long *integer)
+ unsigned char *eoc,
+ long *integer)
{
unsigned char ch;
unsigned int len;
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*integer = (signed char) ch;
len = 1;
-
+
while (ctx->pointer < eoc) {
if (++len > sizeof (long)) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
return 0;
}
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*integer <<= 8;
*integer |= ch;
}
}
static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned int *integer)
+ unsigned char *eoc,
+ unsigned int *integer)
{
unsigned char ch;
unsigned int len;
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*integer = ch;
if (ch == 0) len = 0;
else len = 1;
-
+
while (ctx->pointer < eoc) {
if (++len > sizeof (unsigned int)) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
return 0;
}
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*integer <<= 8;
*integer |= ch;
}
}
static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned long *integer)
+ unsigned char *eoc,
+ unsigned long *integer)
{
unsigned char ch;
unsigned int len;
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*integer = ch;
if (ch == 0) len = 0;
else len = 1;
-
+
while (ctx->pointer < eoc) {
if (++len > sizeof (unsigned long)) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
return 0;
}
-
+
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*integer <<= 8;
*integer |= ch;
}
}
static unsigned char asn1_octets_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned char **octets,
- unsigned int *len)
+ unsigned char *eoc,
+ unsigned char **octets,
+ unsigned int *len)
{
unsigned char *ptr;
-
+
*len = 0;
-
+
*octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
if (*octets == NULL) {
if (net_ratelimit())
printk("OOM in bsalg (%d)\n", __LINE__);
return 0;
}
-
+
ptr = *octets;
while (ctx->pointer < eoc) {
if (!asn1_octet_decode(ctx, (unsigned char *)ptr++)) {
}
static unsigned char asn1_subid_decode(struct asn1_ctx *ctx,
- unsigned long *subid)
+ unsigned long *subid)
{
unsigned char ch;
-
+
*subid = 0;
-
+
do {
if (!asn1_octet_decode(ctx, &ch))
return 0;
-
+
*subid <<= 7;
*subid |= ch & 0x7F;
} while ((ch & 0x80) == 0x80);
}
static unsigned char asn1_oid_decode(struct asn1_ctx *ctx,
- unsigned char *eoc,
- unsigned long **oid,
- unsigned int *len)
+ unsigned char *eoc,
+ unsigned long **oid,
+ unsigned int *len)
{
unsigned long subid;
unsigned int size;
unsigned long *optr;
-
+
size = eoc - ctx->pointer + 1;
*oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);
if (*oid == NULL) {
printk("OOM in bsalg (%d)\n", __LINE__);
return 0;
}
-
+
optr = *oid;
-
+
if (!asn1_subid_decode(ctx, &subid)) {
kfree(*oid);
*oid = NULL;
return 0;
}
-
+
if (subid < 40) {
optr [0] = 0;
optr [1] = subid;
optr [0] = 2;
optr [1] = subid - 80;
}
-
+
*len = 2;
optr += 2;
-
+
while (ctx->pointer < eoc) {
if (++(*len) > size) {
ctx->error = ASN1_ERR_DEC_BADVALUE;
*oid = NULL;
return 0;
}
-
+
if (!asn1_subid_decode(ctx, optr++)) {
kfree(*oid);
*oid = NULL;
#define SERR_EOM 2
static inline void mangle_address(unsigned char *begin,
- unsigned char *addr,
- const struct oct1_map *map,
- __sum16 *check);
+ unsigned char *addr,
+ const struct oct1_map *map,
+ __sum16 *check);
struct snmp_cnv
{
unsigned int class;
{ASN1_APL, SNMP_GGE, SNMP_GAUGE}, /* Gauge32 == Unsigned32 */
{ASN1_APL, SNMP_TIT, SNMP_TIMETICKS},
{ASN1_APL, SNMP_OPQ, SNMP_OPAQUE},
-
+
/* SNMPv2 data types and errors */
{ASN1_UNI, ASN1_BTS, SNMP_BITSTR},
{ASN1_APL, SNMP_C64, SNMP_COUNTER64},
};
static unsigned char snmp_tag_cls2syntax(unsigned int tag,
- unsigned int cls,
- unsigned short *syntax)
+ unsigned int cls,
+ unsigned short *syntax)
{
struct snmp_cnv *cnv;
-
+
cnv = snmp_conv;
-
+
while (cnv->syntax != -1) {
if (cnv->tag == tag && cnv->class == cls) {
*syntax = cnv->syntax;
}
static unsigned char snmp_object_decode(struct asn1_ctx *ctx,
- struct snmp_object **obj)
+ struct snmp_object **obj)
{
unsigned int cls, con, tag, len, idlen;
unsigned short type;
unsigned long *lp, *id;
unsigned long ul;
long l;
-
+
*obj = NULL;
id = NULL;
-
+
if (!asn1_header_decode(ctx, &eoc, &cls, &con, &tag))
return 0;
-
+
if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
return 0;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
return 0;
-
+
if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
return 0;
-
+
if (!asn1_oid_decode(ctx, end, &id, &idlen))
return 0;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag)) {
kfree(id);
return 0;
}
-
+
if (con != ASN1_PRI) {
kfree(id);
return 0;
}
-
+
type = 0;
if (!snmp_tag_cls2syntax(tag, cls, &type)) {
kfree(id);
return 0;
}
-
+
l = 0;
switch (type) {
case SNMP_INTEGER:
return 0;
}
*obj = kmalloc(sizeof(struct snmp_object) + len,
- GFP_ATOMIC);
+ GFP_ATOMIC);
if (*obj == NULL) {
kfree(id);
if (net_ratelimit())
return 0;
}
*obj = kmalloc(sizeof(struct snmp_object) + len,
- GFP_ATOMIC);
+ GFP_ATOMIC);
if (*obj == NULL) {
kfree(id);
if (net_ratelimit())
kfree(id);
return 0;
}
-
+
(*obj)->syntax_len = len;
(*obj)->type = type;
(*obj)->id = id;
(*obj)->id_len = idlen;
-
+
if (!asn1_eoc_decode(ctx, eoc)) {
kfree(id);
kfree(*obj);
}
static unsigned char snmp_request_decode(struct asn1_ctx *ctx,
- struct snmp_request *request)
+ struct snmp_request *request)
{
unsigned int cls, con, tag;
unsigned char *end;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
return 0;
-
+
if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
return 0;
-
+
if (!asn1_ulong_decode(ctx, end, &request->id))
return 0;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
return 0;
-
+
if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
return 0;
-
+
if (!asn1_uint_decode(ctx, end, &request->error_status))
return 0;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
return 0;
-
+
if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
return 0;
-
+
if (!asn1_uint_decode(ctx, end, &request->error_index))
return 0;
-
+
return 1;
}
-/*
+/*
* Fast checksum update for possibly oddly-aligned UDP byte, from the
* code example in the draft.
*/
static void fast_csum(__sum16 *csum,
- const unsigned char *optr,
- const unsigned char *nptr,
- int offset)
+ const unsigned char *optr,
+ const unsigned char *nptr,
+ int offset)
{
unsigned char s[4];
*csum = csum_fold(csum_partial(s, 4, ~csum_unfold(*csum)));
}
-/*
+/*
* Mangle IP address.
* - begin points to the start of the snmp messgae
* - addr points to the start of the address
*/
static inline void mangle_address(unsigned char *begin,
- unsigned char *addr,
- const struct oct1_map *map,
- __sum16 *check)
+ unsigned char *addr,
+ const struct oct1_map *map,
+ __sum16 *check)
{
if (map->from == NOCT1(addr)) {
u_int32_t old;
-
+
if (debug)
memcpy(&old, (unsigned char *)addr, sizeof(old));
-
+
*addr = map->to;
-
+
/* Update UDP checksum if being used */
if (*check) {
fast_csum(check,
- &map->from, &map->to, addr - begin);
+ &map->from, &map->to, addr - begin);
}
-
+
if (debug)
printk(KERN_DEBUG "bsalg: mapped %u.%u.%u.%u to "
"%u.%u.%u.%u\n", NIPQUAD(old), NIPQUAD(*addr));
}
static unsigned char snmp_trap_decode(struct asn1_ctx *ctx,
- struct snmp_v1_trap *trap,
- const struct oct1_map *map,
- __sum16 *check)
+ struct snmp_v1_trap *trap,
+ const struct oct1_map *map,
+ __sum16 *check)
{
unsigned int cls, con, tag, len;
unsigned char *end;
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
return 0;
-
+
if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_OJI)
return 0;
-
+
if (!asn1_oid_decode(ctx, end, &trap->id, &trap->id_len))
return 0;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
goto err_id_free;
if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_IPA) ||
(cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_OTS)))
goto err_id_free;
-
+
if (!asn1_octets_decode(ctx, end, (unsigned char **)&trap->ip_address, &len))
goto err_id_free;
-
+
/* IPv4 only */
if (len != 4)
goto err_addr_free;
-
+
mangle_address(ctx->begin, ctx->pointer - 4, map, check);
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
goto err_addr_free;
-
+
if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
goto err_addr_free;
-
+
if (!asn1_uint_decode(ctx, end, &trap->general))
goto err_addr_free;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
goto err_addr_free;
-
+
if (cls != ASN1_UNI || con != ASN1_PRI || tag != ASN1_INT)
goto err_addr_free;
-
+
if (!asn1_uint_decode(ctx, end, &trap->specific))
goto err_addr_free;
-
+
if (!asn1_header_decode(ctx, &end, &cls, &con, &tag))
goto err_addr_free;
-
+
if (!((cls == ASN1_APL && con == ASN1_PRI && tag == SNMP_TIT) ||
(cls == ASN1_UNI && con == ASN1_PRI && tag == ASN1_INT)))
goto err_addr_free;
-
+
if (!asn1_ulong_decode(ctx, end, &trap->time))
goto err_addr_free;
-
+
return 1;
err_addr_free:
static void hex_dump(unsigned char *buf, size_t len)
{
size_t i;
-
+
for (i = 0; i < len; i++) {
if (i && !(i % 16))
printk("\n");
* (And this is the fucking 'basic' method).
*/
static int snmp_parse_mangle(unsigned char *msg,
- u_int16_t len,
- const struct oct1_map *map,
- __sum16 *check)
+ u_int16_t len,
+ const struct oct1_map *map,
+ __sum16 *check)
{
unsigned char *eoc, *end;
unsigned int cls, con, tag, vers, pdutype;
struct asn1_ctx ctx;
struct asn1_octstr comm;
struct snmp_object **obj;
-
+
if (debug > 1)
hex_dump(msg, len);
asn1_open(&ctx, msg, len);
-
- /*
+
+ /*
* Start of SNMP message.
*/
if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
return 0;
if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
return 0;
-
- /*
+
+ /*
* Version 1 or 2 handled.
*/
if (!asn1_header_decode(&ctx, &end, &cls, &con, &tag))
printk(KERN_DEBUG "bsalg: snmp version: %u\n", vers + 1);
if (vers > 1)
return 1;
-
+
/*
* Community.
*/
return 0;
if (debug > 1) {
unsigned int i;
-
+
printk(KERN_DEBUG "bsalg: community: ");
for (i = 0; i < comm.len; i++)
printk("%c", comm.data[i]);
printk("\n");
}
kfree(comm.data);
-
+
/*
* PDU type
*/
[SNMP_PDU_INFORM] = "inform",
[SNMP_PDU_TRAP2] = "trapv2"
};
-
+
if (pdutype > SNMP_PDU_TRAP2)
printk(KERN_DEBUG "bsalg: bad pdu type %u\n", pdutype);
else
if (pdutype != SNMP_PDU_RESPONSE &&
pdutype != SNMP_PDU_TRAP1 && pdutype != SNMP_PDU_TRAP2)
return 1;
-
+
/*
* Request header or v1 trap
*/
if (pdutype == SNMP_PDU_TRAP1) {
struct snmp_v1_trap trap;
unsigned char ret = snmp_trap_decode(&ctx, &trap, map, check);
-
+
if (ret) {
kfree(trap.id);
kfree((unsigned long *)trap.ip_address);
- } else
+ } else
return ret;
-
+
} else {
struct snmp_request req;
-
+
if (!snmp_request_decode(&ctx, &req))
return 0;
-
+
if (debug > 1)
printk(KERN_DEBUG "bsalg: request: id=0x%lx error_status=%u "
"error_index=%u\n", req.id, req.error_status,
req.error_index);
}
-
+
/*
* Loop through objects, look for IP addresses to mangle.
*/
if (!asn1_header_decode(&ctx, &eoc, &cls, &con, &tag))
return 0;
-
+
if (cls != ASN1_UNI || con != ASN1_CON || tag != ASN1_SEQ)
return 0;
-
+
obj = kmalloc(sizeof(struct snmp_object), GFP_ATOMIC);
if (obj == NULL) {
if (net_ratelimit())
printk(KERN_WARNING "OOM in bsalg(%d)\n", __LINE__);
- return 0;
+ return 0;
}
while (!asn1_eoc_decode(&ctx, eoc)) {
unsigned int i;
-
+
if (!snmp_object_decode(&ctx, obj)) {
if (*obj) {
kfree((*obj)->id);
kfree(*obj);
- }
+ }
kfree(obj);
return 0;
}
printk("%lu", (*obj)->id[i]);
}
printk(": type=%u\n", (*obj)->type);
-
+
}
if ((*obj)->type == SNMP_IPADDR)
mangle_address(ctx.begin, ctx.pointer - 4 , map, check);
-
+
kfree((*obj)->id);
kfree(*obj);
}
kfree(obj);
-
+
if (!asn1_eoc_decode(&ctx, eoc))
return 0;
-
+
return 1;
}
*
*****************************************************************************/
-/*
+/*
* SNMP translation routine.
*/
static int snmp_translate(struct ip_conntrack *ct,
- enum ip_conntrack_info ctinfo,
- struct sk_buff **pskb)
+ enum ip_conntrack_info ctinfo,
+ struct sk_buff **pskb)
{
struct iphdr *iph = (*pskb)->nh.iph;
struct udphdr *udph = (struct udphdr *)((__be32 *)iph + iph->ihl);
map.from = NOCT1(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip);
map.to = NOCT1(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip);
}
-
+
if (map.from == map.to)
return NF_ACCEPT;
-
+
if (!snmp_parse_mangle((unsigned char *)udph + sizeof(struct udphdr),
- paylen, &map, &udph->check)) {
+ paylen, &map, &udph->check)) {
if (net_ratelimit())
printk(KERN_WARNING "bsalg: parser failed\n");
return NF_DROP;
if (!(ct->status & IPS_NAT_MASK))
return NF_ACCEPT;
- /*
+ /*
* Make sure the packet length is ok. So far, we were only guaranteed
* to have a valid length IP header plus 8 bytes, which means we have
* enough room for a UDP header. Just verify the UDP length field so we
* Module stuff.
*
*****************************************************************************/
-
+
static int __init ip_nat_snmp_basic_init(void)
{
int ret = 0;
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff