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freebsd-dev/contrib/bsnmp/lib/snmp.c
Enji Cooper 6c9b7542ef Prevent improper memory accesses after calling snmp_pdu_free and snmp_value_free 
snmp_pdu_free: set pdu->nbindings to 0 to limit the damage that
could happen if a pdu was reused after calling the function, and
as both stack and heap allocation types are used in contrib/bsnmp
and usr.sbin/bsnmpd.

snmp_value_free: NULL out value->v.octetstring.octets after calling
free on it to prevent a double-free from occurring.

MFC after:      2 weeks
2016-12-29 00:20:03 +00:00

1449 lines
35 KiB
C
Raw Blame History

/*
* Copyright (c) 2001-2003
* Fraunhofer Institute for Open Communication Systems (FhG Fokus).
* All rights reserved.
*
* Author: Harti Brandt <harti@freebsd.org>
*
* Copyright (c) 2010 The FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by Shteryana Sotirova Shopova
* under sponsorship from the FreeBSD Foundation.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY AUTHOR 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 AUTHOR 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.
*
* $Begemot: bsnmp/lib/snmp.c,v 1.40 2005/10/04 14:32:42 brandt_h Exp $
*
* SNMP
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#ifdef HAVE_STDINT_H
#include <stdint.h>
#elif defined(HAVE_INTTYPES_H)
#include <inttypes.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include "asn1.h"
#include "snmp.h"
#include "snmppriv.h"
static void snmp_error_func(const char *, ...);
static void snmp_printf_func(const char *, ...);
void (*snmp_error)(const char *, ...) = snmp_error_func;
void (*snmp_printf)(const char *, ...) = snmp_printf_func;
/*
* Get the next variable binding from the list.
* ASN errors on the sequence or the OID are always fatal.
*/
static enum asn_err
get_var_binding(struct asn_buf *b, struct snmp_value *binding)
{
u_char type;
asn_len_t len, trailer;
enum asn_err err;
if (asn_get_sequence(b, &len) != ASN_ERR_OK) {
snmp_error("cannot parse varbind header");
return (ASN_ERR_FAILED);
}
/* temporary truncate the length so that the parser does not
* eat up bytes behind the sequence in the case the encoding is
* wrong of inner elements. */
trailer = b->asn_len - len;
b->asn_len = len;
if (asn_get_objid(b, &binding->var) != ASN_ERR_OK) {
snmp_error("cannot parse binding objid");
return (ASN_ERR_FAILED);
}
if (asn_get_header(b, &type, &len) != ASN_ERR_OK) {
snmp_error("cannot parse binding value header");
return (ASN_ERR_FAILED);
}
switch (type) {
case ASN_TYPE_NULL:
binding->syntax = SNMP_SYNTAX_NULL;
err = asn_get_null_raw(b, len);
break;
case ASN_TYPE_INTEGER:
binding->syntax = SNMP_SYNTAX_INTEGER;
err = asn_get_integer_raw(b, len, &binding->v.integer);
break;
case ASN_TYPE_OCTETSTRING:
binding->syntax = SNMP_SYNTAX_OCTETSTRING;
binding->v.octetstring.octets = malloc(len);
if (binding->v.octetstring.octets == NULL) {
snmp_error("%s", strerror(errno));
return (ASN_ERR_FAILED);
}
binding->v.octetstring.len = len;
err = asn_get_octetstring_raw(b, len,
binding->v.octetstring.octets,
&binding->v.octetstring.len);
if (ASN_ERR_STOPPED(err)) {
free(binding->v.octetstring.octets);
binding->v.octetstring.octets = NULL;
}
break;
case ASN_TYPE_OBJID:
binding->syntax = SNMP_SYNTAX_OID;
err = asn_get_objid_raw(b, len, &binding->v.oid);
break;
case ASN_CLASS_APPLICATION|ASN_APP_IPADDRESS:
binding->syntax = SNMP_SYNTAX_IPADDRESS;
err = asn_get_ipaddress_raw(b, len, binding->v.ipaddress);
break;
case ASN_CLASS_APPLICATION|ASN_APP_TIMETICKS:
binding->syntax = SNMP_SYNTAX_TIMETICKS;
err = asn_get_uint32_raw(b, len, &binding->v.uint32);
break;
case ASN_CLASS_APPLICATION|ASN_APP_COUNTER:
binding->syntax = SNMP_SYNTAX_COUNTER;
err = asn_get_uint32_raw(b, len, &binding->v.uint32);
break;
case ASN_CLASS_APPLICATION|ASN_APP_GAUGE:
binding->syntax = SNMP_SYNTAX_GAUGE;
err = asn_get_uint32_raw(b, len, &binding->v.uint32);
break;
case ASN_CLASS_APPLICATION|ASN_APP_COUNTER64:
binding->syntax = SNMP_SYNTAX_COUNTER64;
err = asn_get_counter64_raw(b, len, &binding->v.counter64);
break;
case ASN_CLASS_CONTEXT | ASN_EXCEPT_NOSUCHOBJECT:
binding->syntax = SNMP_SYNTAX_NOSUCHOBJECT;
err = asn_get_null_raw(b, len);
break;
case ASN_CLASS_CONTEXT | ASN_EXCEPT_NOSUCHINSTANCE:
binding->syntax = SNMP_SYNTAX_NOSUCHINSTANCE;
err = asn_get_null_raw(b, len);
break;
case ASN_CLASS_CONTEXT | ASN_EXCEPT_ENDOFMIBVIEW:
binding->syntax = SNMP_SYNTAX_ENDOFMIBVIEW;
err = asn_get_null_raw(b, len);
break;
default:
if ((err = asn_skip(b, len)) == ASN_ERR_OK)
err = ASN_ERR_TAG;
snmp_error("bad binding value type 0x%x", type);
break;
}
if (ASN_ERR_STOPPED(err)) {
snmp_error("cannot parse binding value");
return (err);
}
if (b->asn_len != 0)
snmp_error("ignoring junk at end of binding");
b->asn_len = trailer;
return (err);
}
/*
* Parse the different PDUs contents. Any ASN error in the outer components
* are fatal. Only errors in variable values may be tolerated. If all
* components can be parsed it returns either ASN_ERR_OK or the first
* error that was found.
*/
enum asn_err
snmp_parse_pdus_hdr(struct asn_buf *b, struct snmp_pdu *pdu, asn_len_t *lenp)
{
if (pdu->type == SNMP_PDU_TRAP) {
if (asn_get_objid(b, &pdu->enterprise) != ASN_ERR_OK) {
snmp_error("cannot parse trap enterprise");
return (ASN_ERR_FAILED);
}
if (asn_get_ipaddress(b, pdu->agent_addr) != ASN_ERR_OK) {
snmp_error("cannot parse trap agent address");
return (ASN_ERR_FAILED);
}
if (asn_get_integer(b, &pdu->generic_trap) != ASN_ERR_OK) {
snmp_error("cannot parse 'generic-trap'");
return (ASN_ERR_FAILED);
}
if (asn_get_integer(b, &pdu->specific_trap) != ASN_ERR_OK) {
snmp_error("cannot parse 'specific-trap'");
return (ASN_ERR_FAILED);
}
if (asn_get_timeticks(b, &pdu->time_stamp) != ASN_ERR_OK) {
snmp_error("cannot parse trap 'time-stamp'");
return (ASN_ERR_FAILED);
}
} else {
if (asn_get_integer(b, &pdu->request_id) != ASN_ERR_OK) {
snmp_error("cannot parse 'request-id'");
return (ASN_ERR_FAILED);
}
if (asn_get_integer(b, &pdu->error_status) != ASN_ERR_OK) {
snmp_error("cannot parse 'error_status'");
return (ASN_ERR_FAILED);
}
if (asn_get_integer(b, &pdu->error_index) != ASN_ERR_OK) {
snmp_error("cannot parse 'error_index'");
return (ASN_ERR_FAILED);
}
}
if (asn_get_sequence(b, lenp) != ASN_ERR_OK) {
snmp_error("cannot get varlist header");
return (ASN_ERR_FAILED);
}
return (ASN_ERR_OK);
}
static enum asn_err
parse_pdus(struct asn_buf *b, struct snmp_pdu *pdu, int32_t *ip)
{
asn_len_t len, trailer;
struct snmp_value *v;
enum asn_err err, err1;
err = snmp_parse_pdus_hdr(b, pdu, &len);
if (ASN_ERR_STOPPED(err))
return (err);
trailer = b->asn_len - len;
v = pdu->bindings;
err = ASN_ERR_OK;
while (b->asn_len != 0) {
if (pdu->nbindings == SNMP_MAX_BINDINGS) {
snmp_error("too many bindings (> %u) in PDU",
SNMP_MAX_BINDINGS);
return (ASN_ERR_FAILED);
}
err1 = get_var_binding(b, v);
if (ASN_ERR_STOPPED(err1))
return (ASN_ERR_FAILED);
if (err1 != ASN_ERR_OK && err == ASN_ERR_OK) {
err = err1;
*ip = pdu->nbindings + 1;
}
pdu->nbindings++;
v++;
}
b->asn_len = trailer;
return (err);
}
static enum asn_err
parse_secparams(struct asn_buf *b, struct snmp_pdu *pdu)
{
asn_len_t octs_len;
u_char buf[256]; /* XXX: calc max possible size here */
struct asn_buf tb;
memset(buf, 0, 256);
tb.asn_ptr = buf;
tb.asn_len = 256;
u_int len = 256;
if (asn_get_octetstring(b, buf, &len) != ASN_ERR_OK) {
snmp_error("cannot parse usm header");
return (ASN_ERR_FAILED);
}
tb.asn_len = len;
if (asn_get_sequence(&tb, &octs_len) != ASN_ERR_OK) {
snmp_error("cannot decode usm header");
return (ASN_ERR_FAILED);
}
octs_len = SNMP_ENGINE_ID_SIZ;
if (asn_get_octetstring(&tb, (u_char *)&pdu->engine.engine_id,
&octs_len) != ASN_ERR_OK) {
snmp_error("cannot decode msg engine id");
return (ASN_ERR_FAILED);
}
pdu->engine.engine_len = octs_len;
if (asn_get_integer(&tb, &pdu->engine.engine_boots) != ASN_ERR_OK) {
snmp_error("cannot decode msg engine boots");
return (ASN_ERR_FAILED);
}
if (asn_get_integer(&tb, &pdu->engine.engine_time) != ASN_ERR_OK) {
snmp_error("cannot decode msg engine time");
return (ASN_ERR_FAILED);
}
octs_len = SNMP_ADM_STR32_SIZ - 1;
if (asn_get_octetstring(&tb, (u_char *)&pdu->user.sec_name, &octs_len)
!= ASN_ERR_OK) {
snmp_error("cannot decode msg user name");
return (ASN_ERR_FAILED);
}
pdu->user.sec_name[octs_len] = '\0';
octs_len = sizeof(pdu->msg_digest);
if (asn_get_octetstring(&tb, (u_char *)&pdu->msg_digest, &octs_len) !=
ASN_ERR_OK || ((pdu->flags & SNMP_MSG_AUTH_FLAG) != 0 &&
octs_len != sizeof(pdu->msg_digest))) {
snmp_error("cannot decode msg authentication param");
return (ASN_ERR_FAILED);
}
octs_len = sizeof(pdu->msg_salt);
if (asn_get_octetstring(&tb, (u_char *)&pdu->msg_salt, &octs_len) !=
ASN_ERR_OK ||((pdu->flags & SNMP_MSG_PRIV_FLAG) != 0 &&
octs_len != sizeof(pdu->msg_salt))) {
snmp_error("cannot decode msg authentication param");
return (ASN_ERR_FAILED);
}
if ((pdu->flags & SNMP_MSG_AUTH_FLAG) != 0) {
pdu->digest_ptr = b->asn_ptr - SNMP_USM_AUTH_SIZE;
pdu->digest_ptr -= octs_len + ASN_MAXLENLEN;
}
return (ASN_ERR_OK);
}
static enum snmp_code
pdu_encode_secparams(struct asn_buf *b, struct snmp_pdu *pdu)
{
u_char buf[256], *sptr;
struct asn_buf tb;
size_t auth_off, moved = 0;
auth_off = 0;
memset(buf, 0, 256);
tb.asn_ptr = buf;
tb.asn_len = 256;
if (asn_put_temp_header(&tb, (ASN_TYPE_SEQUENCE|ASN_TYPE_CONSTRUCTED),
&sptr) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_octetstring(&tb, (u_char *)pdu->engine.engine_id,
pdu->engine.engine_len) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_integer(&tb, pdu->engine.engine_boots) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_integer(&tb, pdu->engine.engine_time) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_octetstring(&tb, (u_char *)pdu->user.sec_name,
strlen(pdu->user.sec_name)) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if ((pdu->flags & SNMP_MSG_AUTH_FLAG) != 0) {
auth_off = sizeof(buf) - tb.asn_len + ASN_MAXLENLEN;
if (asn_put_octetstring(&tb, (u_char *)pdu->msg_digest,
sizeof(pdu->msg_digest)) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
} else {
if (asn_put_octetstring(&tb, (u_char *)pdu->msg_digest, 0)
!= ASN_ERR_OK)
return (SNMP_CODE_FAILED);
}
if ((pdu->flags & SNMP_MSG_PRIV_FLAG) != 0) {
if (asn_put_octetstring(&tb, (u_char *)pdu->msg_salt,
sizeof(pdu->msg_salt)) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
} else {
if (asn_put_octetstring(&tb, (u_char *)pdu->msg_salt, 0)
!= ASN_ERR_OK)
return (SNMP_CODE_FAILED);
}
if (asn_commit_header(&tb, sptr, &moved) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if ((pdu->flags & SNMP_MSG_AUTH_FLAG) != 0)
pdu->digest_ptr = b->asn_ptr + auth_off - moved;
if (asn_put_octetstring(b, buf, sizeof(buf) - tb.asn_len) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
pdu->digest_ptr += ASN_MAXLENLEN;
if ((pdu->flags & SNMP_MSG_PRIV_FLAG) != 0 && asn_put_temp_header(b,
ASN_TYPE_OCTETSTRING, &pdu->encrypted_ptr) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
return (SNMP_CODE_OK);
}
/*
* Decode the PDU except for the variable bindings itself.
* If decoding fails because of a bad binding, but the rest can be
* decoded, ip points to the index of the failed variable (errors
* OORANGE, BADLEN or BADVERS).
*/
enum snmp_code
snmp_pdu_decode(struct asn_buf *b, struct snmp_pdu *pdu, int32_t *ip)
{
enum snmp_code code;
if ((code = snmp_pdu_decode_header(b, pdu)) != SNMP_CODE_OK)
return (code);
if (pdu->version == SNMP_V3) {
if (pdu->security_model != SNMP_SECMODEL_USM)
return (SNMP_CODE_FAILED);
if ((code = snmp_pdu_decode_secmode(b, pdu)) != SNMP_CODE_OK)
return (code);
}
code = snmp_pdu_decode_scoped(b, pdu, ip);
switch (code) {
case SNMP_CODE_FAILED:
snmp_pdu_free(pdu);
break;
case SNMP_CODE_BADENC:
if (pdu->version == SNMP_Verr)
return (SNMP_CODE_BADVERS);
default:
break;
}
return (code);
}
enum snmp_code
snmp_pdu_decode_header(struct asn_buf *b, struct snmp_pdu *pdu)
{
int32_t version;
u_int octs_len;
asn_len_t len;
pdu->outer_ptr = b->asn_ptr;
pdu->outer_len = b->asn_len;
if (asn_get_sequence(b, &len) != ASN_ERR_OK) {
snmp_error("cannot decode pdu header");
return (SNMP_CODE_FAILED);
}
if (b->asn_len < len) {
snmp_error("outer sequence value too short");
return (SNMP_CODE_FAILED);
}
if (b->asn_len != len) {
snmp_error("ignoring trailing junk in message");
b->asn_len = len;
}
if (asn_get_integer(b, &version) != ASN_ERR_OK) {
snmp_error("cannot decode version");
return (SNMP_CODE_FAILED);
}
if (version == 0)
pdu->version = SNMP_V1;
else if (version == 1)
pdu->version = SNMP_V2c;
else if (version == 3)
pdu->version = SNMP_V3;
else {
pdu->version = SNMP_Verr;
snmp_error("unsupported SNMP version");
return (SNMP_CODE_BADENC);
}
if (pdu->version == SNMP_V3) {
if (asn_get_sequence(b, &len) != ASN_ERR_OK) {
snmp_error("cannot decode pdu global data header");
return (SNMP_CODE_FAILED);
}
if (asn_get_integer(b, &pdu->identifier) != ASN_ERR_OK) {
snmp_error("cannot decode msg indetifier");
return (SNMP_CODE_FAILED);
}
if (asn_get_integer(b, &pdu->engine.max_msg_size)
!= ASN_ERR_OK) {
snmp_error("cannot decode msg size");
return (SNMP_CODE_FAILED);
}
octs_len = 1;
if (asn_get_octetstring(b, (u_char *)&pdu->flags,
&octs_len) != ASN_ERR_OK) {
snmp_error("cannot decode msg flags");
return (SNMP_CODE_FAILED);
}
if (asn_get_integer(b, &pdu->security_model) != ASN_ERR_OK) {
snmp_error("cannot decode msg size");
return (SNMP_CODE_FAILED);
}
if (pdu->security_model != SNMP_SECMODEL_USM)
return (SNMP_CODE_FAILED);
if (parse_secparams(b, pdu) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
} else {
octs_len = SNMP_COMMUNITY_MAXLEN;
if (asn_get_octetstring(b, (u_char *)pdu->community,
&octs_len) != ASN_ERR_OK) {
snmp_error("cannot decode community");
return (SNMP_CODE_FAILED);
}
pdu->community[octs_len] = '\0';
}
return (SNMP_CODE_OK);
}
enum snmp_code
snmp_pdu_decode_scoped(struct asn_buf *b, struct snmp_pdu *pdu, int32_t *ip)
{
u_char type;
asn_len_t len, trailer;
enum asn_err err;
if (pdu->version == SNMP_V3) {
if (asn_get_sequence(b, &len) != ASN_ERR_OK) {
snmp_error("cannot decode scoped pdu header");
return (SNMP_CODE_FAILED);
}
len = SNMP_ENGINE_ID_SIZ;
if (asn_get_octetstring(b, (u_char *)&pdu->context_engine,
&len) != ASN_ERR_OK) {
snmp_error("cannot decode msg context engine");
return (SNMP_CODE_FAILED);
}
pdu->context_engine_len = len;
len = SNMP_CONTEXT_NAME_SIZ;
if (asn_get_octetstring(b, (u_char *)&pdu->context_name,
&len) != ASN_ERR_OK) {
snmp_error("cannot decode msg context name");
return (SNMP_CODE_FAILED);
}
pdu->context_name[len] = '\0';
}
if (asn_get_header(b, &type, &len) != ASN_ERR_OK) {
snmp_error("cannot get pdu header");
return (SNMP_CODE_FAILED);
}
if ((type & ~ASN_TYPE_MASK) !=
(ASN_TYPE_CONSTRUCTED | ASN_CLASS_CONTEXT)) {
snmp_error("bad pdu header tag");
return (SNMP_CODE_FAILED);
}
pdu->type = type & ASN_TYPE_MASK;
switch (pdu->type) {
case SNMP_PDU_GET:
case SNMP_PDU_GETNEXT:
case SNMP_PDU_RESPONSE:
case SNMP_PDU_SET:
break;
case SNMP_PDU_TRAP:
if (pdu->version != SNMP_V1) {
snmp_error("bad pdu type %u", pdu->type);
return (SNMP_CODE_FAILED);
}
break;
case SNMP_PDU_GETBULK:
case SNMP_PDU_INFORM:
case SNMP_PDU_TRAP2:
case SNMP_PDU_REPORT:
if (pdu->version == SNMP_V1) {
snmp_error("bad pdu type %u", pdu->type);
return (SNMP_CODE_FAILED);
}
break;
default:
snmp_error("bad pdu type %u", pdu->type);
return (SNMP_CODE_FAILED);
}
trailer = b->asn_len - len;
b->asn_len = len;
err = parse_pdus(b, pdu, ip);
if (ASN_ERR_STOPPED(err))
return (SNMP_CODE_FAILED);
if (b->asn_len != 0)
snmp_error("ignoring trailing junk after pdu");
b->asn_len = trailer;
return (SNMP_CODE_OK);
}
enum snmp_code
snmp_pdu_decode_secmode(struct asn_buf *b, struct snmp_pdu *pdu)
{
u_char type;
enum snmp_code code;
uint8_t digest[SNMP_USM_AUTH_SIZE];
if (pdu->user.auth_proto != SNMP_AUTH_NOAUTH &&
(pdu->flags & SNMP_MSG_AUTH_FLAG) == 0)
return (SNMP_CODE_BADSECLEVEL);
if ((code = snmp_pdu_calc_digest(pdu, digest)) !=
SNMP_CODE_OK)
return (SNMP_CODE_FAILED);
if (pdu->user.auth_proto != SNMP_AUTH_NOAUTH &&
memcmp(digest, pdu->msg_digest, sizeof(pdu->msg_digest)) != 0)
return (SNMP_CODE_BADDIGEST);
if (pdu->user.priv_proto != SNMP_PRIV_NOPRIV && (asn_get_header(b, &type,
&pdu->scoped_len) != ASN_ERR_OK || type != ASN_TYPE_OCTETSTRING)) {
snmp_error("cannot decode encrypted pdu");
return (SNMP_CODE_FAILED);
}
pdu->scoped_ptr = b->asn_ptr;
if (pdu->user.priv_proto != SNMP_PRIV_NOPRIV &&
(pdu->flags & SNMP_MSG_PRIV_FLAG) == 0)
return (SNMP_CODE_BADSECLEVEL);
if ((code = snmp_pdu_decrypt(pdu)) != SNMP_CODE_OK)
return (SNMP_CODE_FAILED);
return (code);
}
/*
* Check whether what we have is the complete PDU by snooping at the
* enclosing structure header. This returns:
* -1 if there are ASN.1 errors
* 0 if we need more data
* > 0 the length of this PDU
*/
int
snmp_pdu_snoop(const struct asn_buf *b0)
{
u_int length;
asn_len_t len;
struct asn_buf b = *b0;
/* <0x10|0x20> <len> <data...> */
if (b.asn_len == 0)
return (0);
if (b.asn_cptr[0] != (ASN_TYPE_SEQUENCE | ASN_TYPE_CONSTRUCTED)) {
asn_error(&b, "bad sequence type %u", b.asn_cptr[0]);
return (-1);
}
b.asn_len--;
b.asn_cptr++;
if (b.asn_len == 0)
return (0);
if (*b.asn_cptr & 0x80) {
/* long length */
length = *b.asn_cptr++ & 0x7f;
b.asn_len--;
if (length == 0) {
asn_error(&b, "indefinite length not supported");
return (-1);
}
if (length > ASN_MAXLENLEN) {
asn_error(&b, "long length too long (%u)", length);
return (-1);
}
if (length > b.asn_len)
return (0);
len = 0;
while (length--) {
len = (len << 8) | *b.asn_cptr++;
b.asn_len--;
}
} else {
len = *b.asn_cptr++;
b.asn_len--;
}
if (len > b.asn_len)
return (0);
return (len + b.asn_cptr - b0->asn_cptr);
}
/*
* Encode the SNMP PDU without the variable bindings field.
* We do this the rather uneffective way by
* moving things around and assuming that the length field will never
* use more than 2 bytes.
* We need a number of pointers to apply the fixes afterwards.
*/
enum snmp_code
snmp_pdu_encode_header(struct asn_buf *b, struct snmp_pdu *pdu)
{
enum asn_err err;
u_char *v3_hdr_ptr;
if (asn_put_temp_header(b, (ASN_TYPE_SEQUENCE|ASN_TYPE_CONSTRUCTED),
&pdu->outer_ptr) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->version == SNMP_V1)
err = asn_put_integer(b, 0);
else if (pdu->version == SNMP_V2c)
err = asn_put_integer(b, 1);
else if (pdu->version == SNMP_V3)
err = asn_put_integer(b, 3);
else
return (SNMP_CODE_BADVERS);
if (err != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->version == SNMP_V3) {
if (asn_put_temp_header(b, (ASN_TYPE_SEQUENCE |
ASN_TYPE_CONSTRUCTED), &v3_hdr_ptr) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_integer(b, pdu->identifier) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_integer(b, pdu->engine.max_msg_size) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->type != SNMP_PDU_RESPONSE &&
pdu->type != SNMP_PDU_TRAP &&
pdu->type != SNMP_PDU_TRAP2 &&
pdu->type != SNMP_PDU_REPORT)
pdu->flags |= SNMP_MSG_REPORT_FLAG;
if (asn_put_octetstring(b, (u_char *)&pdu->flags, 1)
!= ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_integer(b, pdu->security_model) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_commit_header(b, v3_hdr_ptr, NULL) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->security_model != SNMP_SECMODEL_USM)
return (SNMP_CODE_FAILED);
if (pdu_encode_secparams(b, pdu) != SNMP_CODE_OK)
return (SNMP_CODE_FAILED);
/* View-based Access Conntrol information */
if (asn_put_temp_header(b, (ASN_TYPE_SEQUENCE |
ASN_TYPE_CONSTRUCTED), &pdu->scoped_ptr) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_octetstring(b, (u_char *)pdu->context_engine,
pdu->context_engine_len) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (asn_put_octetstring(b, (u_char *)pdu->context_name,
strlen(pdu->context_name)) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
} else {
if (asn_put_octetstring(b, (u_char *)pdu->community,
strlen(pdu->community)) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
}
if (asn_put_temp_header(b, (ASN_TYPE_CONSTRUCTED | ASN_CLASS_CONTEXT |
pdu->type), &pdu->pdu_ptr) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->type == SNMP_PDU_TRAP) {
if (pdu->version != SNMP_V1 ||
asn_put_objid(b, &pdu->enterprise) != ASN_ERR_OK ||
asn_put_ipaddress(b, pdu->agent_addr) != ASN_ERR_OK ||
asn_put_integer(b, pdu->generic_trap) != ASN_ERR_OK ||
asn_put_integer(b, pdu->specific_trap) != ASN_ERR_OK ||
asn_put_timeticks(b, pdu->time_stamp) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
} else {
if (pdu->version == SNMP_V1 && (pdu->type == SNMP_PDU_GETBULK ||
pdu->type == SNMP_PDU_INFORM ||
pdu->type == SNMP_PDU_TRAP2 ||
pdu->type == SNMP_PDU_REPORT))
return (SNMP_CODE_FAILED);
if (asn_put_integer(b, pdu->request_id) != ASN_ERR_OK ||
asn_put_integer(b, pdu->error_status) != ASN_ERR_OK ||
asn_put_integer(b, pdu->error_index) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
}
if (asn_put_temp_header(b, (ASN_TYPE_SEQUENCE|ASN_TYPE_CONSTRUCTED),
&pdu->vars_ptr) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
return (SNMP_CODE_OK);
}
static enum asn_err
snmp_pdu_fix_padd(struct asn_buf *b, struct snmp_pdu *pdu)
{
asn_len_t padlen;
if (pdu->user.priv_proto == SNMP_PRIV_DES && pdu->scoped_len % 8 != 0) {
padlen = 8 - (pdu->scoped_len % 8);
if (asn_pad(b, padlen) != ASN_ERR_OK)
return (ASN_ERR_FAILED);
pdu->scoped_len += padlen;
}
return (ASN_ERR_OK);
}
enum snmp_code
snmp_fix_encoding(struct asn_buf *b, struct snmp_pdu *pdu)
{
size_t moved = 0;
enum snmp_code code;
if (asn_commit_header(b, pdu->vars_ptr, NULL) != ASN_ERR_OK ||
asn_commit_header(b, pdu->pdu_ptr, NULL) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->version == SNMP_V3) {
if (asn_commit_header(b, pdu->scoped_ptr, NULL) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
pdu->scoped_len = b->asn_ptr - pdu->scoped_ptr;
if (snmp_pdu_fix_padd(b, pdu) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->security_model != SNMP_SECMODEL_USM)
return (SNMP_CODE_FAILED);
if (snmp_pdu_encrypt(pdu) != SNMP_CODE_OK)
return (SNMP_CODE_FAILED);
if (pdu->user.priv_proto != SNMP_PRIV_NOPRIV &&
asn_commit_header(b, pdu->encrypted_ptr, NULL) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
}
if (asn_commit_header(b, pdu->outer_ptr, &moved) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
pdu->outer_len = b->asn_ptr - pdu->outer_ptr;
pdu->digest_ptr -= moved;
if (pdu->version == SNMP_V3) {
if ((code = snmp_pdu_calc_digest(pdu, pdu->msg_digest)) !=
SNMP_CODE_OK)
return (SNMP_CODE_FAILED);
if ((pdu->flags & SNMP_MSG_AUTH_FLAG) != 0)
memcpy(pdu->digest_ptr, pdu->msg_digest,
sizeof(pdu->msg_digest));
}
return (SNMP_CODE_OK);
}
/*
* Encode a binding. Caller must ensure, that the syntax is ok for that version.
* Be sure not to cobber b, when something fails.
*/
enum asn_err
snmp_binding_encode(struct asn_buf *b, const struct snmp_value *binding)
{
u_char *ptr;
enum asn_err err;
struct asn_buf save = *b;
if ((err = asn_put_temp_header(b, (ASN_TYPE_SEQUENCE |
ASN_TYPE_CONSTRUCTED), &ptr)) != ASN_ERR_OK) {
*b = save;
return (err);
}
if ((err = asn_put_objid(b, &binding->var)) != ASN_ERR_OK) {
*b = save;
return (err);
}
switch (binding->syntax) {
case SNMP_SYNTAX_NULL:
err = asn_put_null(b);
break;
case SNMP_SYNTAX_INTEGER:
err = asn_put_integer(b, binding->v.integer);
break;
case SNMP_SYNTAX_OCTETSTRING:
err = asn_put_octetstring(b, binding->v.octetstring.octets,
binding->v.octetstring.len);
break;
case SNMP_SYNTAX_OID:
err = asn_put_objid(b, &binding->v.oid);
break;
case SNMP_SYNTAX_IPADDRESS:
err = asn_put_ipaddress(b, binding->v.ipaddress);
break;
case SNMP_SYNTAX_TIMETICKS:
err = asn_put_uint32(b, ASN_APP_TIMETICKS, binding->v.uint32);
break;
case SNMP_SYNTAX_COUNTER:
err = asn_put_uint32(b, ASN_APP_COUNTER, binding->v.uint32);
break;
case SNMP_SYNTAX_GAUGE:
err = asn_put_uint32(b, ASN_APP_GAUGE, binding->v.uint32);
break;
case SNMP_SYNTAX_COUNTER64:
err = asn_put_counter64(b, binding->v.counter64);
break;
case SNMP_SYNTAX_NOSUCHOBJECT:
err = asn_put_exception(b, ASN_EXCEPT_NOSUCHOBJECT);
break;
case SNMP_SYNTAX_NOSUCHINSTANCE:
err = asn_put_exception(b, ASN_EXCEPT_NOSUCHINSTANCE);
break;
case SNMP_SYNTAX_ENDOFMIBVIEW:
err = asn_put_exception(b, ASN_EXCEPT_ENDOFMIBVIEW);
break;
}
if (err != ASN_ERR_OK) {
*b = save;
return (err);
}
err = asn_commit_header(b, ptr, NULL);
if (err != ASN_ERR_OK) {
*b = save;
return (err);
}
return (ASN_ERR_OK);
}
/*
* Encode an PDU.
*/
enum snmp_code
snmp_pdu_encode(struct snmp_pdu *pdu, struct asn_buf *resp_b)
{
u_int idx;
enum snmp_code err;
if ((err = snmp_pdu_encode_header(resp_b, pdu)) != SNMP_CODE_OK)
return (err);
for (idx = 0; idx < pdu->nbindings; idx++)
if (snmp_binding_encode(resp_b, &pdu->bindings[idx])
!= ASN_ERR_OK)
return (SNMP_CODE_FAILED);
return (snmp_fix_encoding(resp_b, pdu));
}
static void
dump_binding(const struct snmp_value *b)
{
u_int i;
char buf[ASN_OIDSTRLEN];
snmp_printf("%s=", asn_oid2str_r(&b->var, buf));
switch (b->syntax) {
case SNMP_SYNTAX_NULL:
snmp_printf("NULL");
break;
case SNMP_SYNTAX_INTEGER:
snmp_printf("INTEGER %d", b->v.integer);
break;
case SNMP_SYNTAX_OCTETSTRING:
snmp_printf("OCTET STRING %lu:", b->v.octetstring.len);
for (i = 0; i < b->v.octetstring.len; i++)
snmp_printf(" %02x", b->v.octetstring.octets[i]);
break;
case SNMP_SYNTAX_OID:
snmp_printf("OID %s", asn_oid2str_r(&b->v.oid, buf));
break;
case SNMP_SYNTAX_IPADDRESS:
snmp_printf("IPADDRESS %u.%u.%u.%u", b->v.ipaddress[0],
b->v.ipaddress[1], b->v.ipaddress[2], b->v.ipaddress[3]);
break;
case SNMP_SYNTAX_COUNTER:
snmp_printf("COUNTER %u", b->v.uint32);
break;
case SNMP_SYNTAX_GAUGE:
snmp_printf("GAUGE %u", b->v.uint32);
break;
case SNMP_SYNTAX_TIMETICKS:
snmp_printf("TIMETICKS %u", b->v.uint32);
break;
case SNMP_SYNTAX_COUNTER64:
snmp_printf("COUNTER64 %lld", b->v.counter64);
break;
case SNMP_SYNTAX_NOSUCHOBJECT:
snmp_printf("NoSuchObject");
break;
case SNMP_SYNTAX_NOSUCHINSTANCE:
snmp_printf("NoSuchInstance");
break;
case SNMP_SYNTAX_ENDOFMIBVIEW:
snmp_printf("EndOfMibView");
break;
default:
snmp_printf("UNKNOWN SYNTAX %u", b->syntax);
break;
}
}
static __inline void
dump_bindings(const struct snmp_pdu *pdu)
{
u_int i;
for (i = 0; i < pdu->nbindings; i++) {
snmp_printf(" [%u]: ", i);
dump_binding(&pdu->bindings[i]);
snmp_printf("\n");
}
}
static __inline void
dump_notrap(const struct snmp_pdu *pdu)
{
snmp_printf(" request_id=%d", pdu->request_id);
snmp_printf(" error_status=%d", pdu->error_status);
snmp_printf(" error_index=%d\n", pdu->error_index);
dump_bindings(pdu);
}
void
snmp_pdu_dump(const struct snmp_pdu *pdu)
{
char buf[ASN_OIDSTRLEN];
const char *vers;
static const char *types[] = {
[SNMP_PDU_GET] = "GET",
[SNMP_PDU_GETNEXT] = "GETNEXT",
[SNMP_PDU_RESPONSE] = "RESPONSE",
[SNMP_PDU_SET] = "SET",
[SNMP_PDU_TRAP] = "TRAPv1",
[SNMP_PDU_GETBULK] = "GETBULK",
[SNMP_PDU_INFORM] = "INFORM",
[SNMP_PDU_TRAP2] = "TRAPv2",
[SNMP_PDU_REPORT] = "REPORT",
};
if (pdu->version == SNMP_V1)
vers = "SNMPv1";
else if (pdu->version == SNMP_V2c)
vers = "SNMPv2c";
else if (pdu->version == SNMP_V3)
vers = "SNMPv3";
else
vers = "v?";
switch (pdu->type) {
case SNMP_PDU_TRAP:
snmp_printf("%s %s '%s'", types[pdu->type], vers, pdu->community);
snmp_printf(" enterprise=%s", asn_oid2str_r(&pdu->enterprise, buf));
snmp_printf(" agent_addr=%u.%u.%u.%u", pdu->agent_addr[0],
pdu->agent_addr[1], pdu->agent_addr[2], pdu->agent_addr[3]);
snmp_printf(" generic_trap=%d", pdu->generic_trap);
snmp_printf(" specific_trap=%d", pdu->specific_trap);
snmp_printf(" time-stamp=%u\n", pdu->time_stamp);
dump_bindings(pdu);
break;
case SNMP_PDU_GET:
case SNMP_PDU_GETNEXT:
case SNMP_PDU_RESPONSE:
case SNMP_PDU_SET:
case SNMP_PDU_GETBULK:
case SNMP_PDU_INFORM:
case SNMP_PDU_TRAP2:
case SNMP_PDU_REPORT:
snmp_printf("%s %s '%s'", types[pdu->type], vers, pdu->community);
dump_notrap(pdu);
break;
default:
snmp_printf("bad pdu type %u\n", pdu->type);
break;
}
}
void
snmp_value_free(struct snmp_value *value)
{
if (value->syntax == SNMP_SYNTAX_OCTETSTRING) {
free(value->v.octetstring.octets);
value->v.octetstring.octets = NULL;
}
value->syntax = SNMP_SYNTAX_NULL;
}
int
snmp_value_copy(struct snmp_value *to, const struct snmp_value *from)
{
to->var = from->var;
to->syntax = from->syntax;
if (from->syntax == SNMP_SYNTAX_OCTETSTRING) {
if ((to->v.octetstring.len = from->v.octetstring.len) == 0)
to->v.octetstring.octets = NULL;
else {
to->v.octetstring.octets = malloc(to->v.octetstring.len);
if (to->v.octetstring.octets == NULL)
return (-1);
(void)memcpy(to->v.octetstring.octets,
from->v.octetstring.octets, to->v.octetstring.len);
}
} else
to->v = from->v;
return (0);
}
void
snmp_pdu_init_secparams(struct snmp_pdu *pdu)
{
int32_t rval;
if (pdu->user.auth_proto != SNMP_AUTH_NOAUTH)
pdu->flags |= SNMP_MSG_AUTH_FLAG;
switch (pdu->user.priv_proto) {
case SNMP_PRIV_DES:
memcpy(pdu->msg_salt, &pdu->engine.engine_boots,
sizeof(pdu->engine.engine_boots));
rval = random();
memcpy(pdu->msg_salt + sizeof(pdu->engine.engine_boots), &rval,
sizeof(int32_t));
pdu->flags |= SNMP_MSG_PRIV_FLAG;
break;
case SNMP_PRIV_AES:
rval = random();
memcpy(pdu->msg_salt, &rval, sizeof(int32_t));
rval = random();
memcpy(pdu->msg_salt + sizeof(int32_t), &rval, sizeof(int32_t));
pdu->flags |= SNMP_MSG_PRIV_FLAG;
break;
default:
break;
}
}
void
snmp_pdu_free(struct snmp_pdu *pdu)
{
u_int i;
for (i = 0; i < pdu->nbindings; i++)
snmp_value_free(&pdu->bindings[i]);
pdu->nbindings = 0;
}
/*
* Parse an ASCII SNMP value into the binary form
*/
int
snmp_value_parse(const char *str, enum snmp_syntax syntax, union snmp_values *v)
{
char *end;
switch (syntax) {
case SNMP_SYNTAX_NULL:
case SNMP_SYNTAX_NOSUCHOBJECT:
case SNMP_SYNTAX_NOSUCHINSTANCE:
case SNMP_SYNTAX_ENDOFMIBVIEW:
if (*str != '\0')
return (-1);
return (0);
case SNMP_SYNTAX_INTEGER:
v->integer = strtoll(str, &end, 0);
if (*end != '\0')
return (-1);
return (0);
case SNMP_SYNTAX_OCTETSTRING:
{
u_long len; /* actual length of string */
u_long alloc; /* allocate length of string */
u_char *octs; /* actual octets */
u_long oct; /* actual octet */
u_char *nocts; /* to avoid memory leak */
u_char c; /* actual character */
# define STUFFC(C) \
if (alloc == len) { \
alloc += 100; \
if ((nocts = realloc(octs, alloc)) == NULL) { \
free(octs); \
return (-1); \
} \
octs = nocts; \
} \
octs[len++] = (C);
len = alloc = 0;
octs = NULL;
if (*str == '"') {
str++;
while((c = *str++) != '\0') {
if (c == '"') {
if (*str != '\0') {
free(octs);
return (-1);
}
break;
}
if (c == '\\') {
switch (c = *str++) {
case '\\':
break;
case 'a':
c = '\a';
break;
case 'b':
c = '\b';
break;
case 'f':
c = '\f';
break;
case 'n':
c = '\n';
break;
case 'r':
c = '\r';
break;
case 't':
c = '\t';
break;
case 'v':
c = '\v';
break;
case 'x':
c = 0;
if (!isxdigit(*str))
break;
if (isdigit(*str))
c = *str++ - '0';
else if (isupper(*str))
c = *str++ - 'A' + 10;
else
c = *str++ - 'a' + 10;
if (!isxdigit(*str))
break;
if (isdigit(*str))
c += *str++ - '0';
else if (isupper(*str))
c += *str++ - 'A' + 10;
else
c += *str++ - 'a' + 10;
break;
case '0': case '1': case '2':
case '3': case '4': case '5':
case '6': case '7':
c = *str++ - '0';
if (*str < '0' || *str > '7')
break;
c = *str++ - '0';
if (*str < '0' || *str > '7')
break;
c = *str++ - '0';
break;
default:
break;
}
}
STUFFC(c);
}
} else {
while (*str != '\0') {
oct = strtoul(str, &end, 16);
str = end;
if (oct > 0xff) {
free(octs);
return (-1);
}
STUFFC(oct);
if (*str == ':')
str++;
else if(*str != '\0') {
free(octs);
return (-1);
}
}
}
v->octetstring.octets = octs;
v->octetstring.len = len;
return (0);
# undef STUFFC
}
case SNMP_SYNTAX_OID:
{
u_long subid;
v->oid.len = 0;
for (;;) {
if (v->oid.len == ASN_MAXOIDLEN)
return (-1);
subid = strtoul(str, &end, 10);
str = end;
if (subid > ASN_MAXID)
return (-1);
v->oid.subs[v->oid.len++] = (asn_subid_t)subid;
if (*str == '\0')
break;
if (*str != '.')
return (-1);
str++;
}
return (0);
}
case SNMP_SYNTAX_IPADDRESS:
{
struct hostent *he;
if (inet_pton(AF_INET, str, &v->ipaddress) == 1)
return (0);
if ((he = gethostbyname2(str, AF_INET)) == NULL)
return (-1);
if (he->h_addrtype != AF_INET)
return (-1);
memcpy(v->ipaddress, he->h_addr, sizeof(v->ipaddress));
return (0);
}
case SNMP_SYNTAX_COUNTER:
case SNMP_SYNTAX_GAUGE:
case SNMP_SYNTAX_TIMETICKS:
{
uint64_t sub;
sub = strtoull(str, &end, 0);
if (*end != '\0' || sub > 0xffffffff)
return (-1);
v->uint32 = (uint32_t)sub;
return (0);
}
case SNMP_SYNTAX_COUNTER64:
v->counter64 = strtoull(str, &end, 0);
if (*end != '\0')
return (-1);
return (0);
}
abort();
}
static void
snmp_error_func(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
fprintf(stderr, "SNMP: ");
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
va_end(ap);
}
static void
snmp_printf_func(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
}
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