Author: syrinx
Date: Thu Oct 17 11:49:46 2013
New Revision: 256678
URL: http://svnweb.freebsd.org/changeset/base/256678
Log:
Fix SNMP Error response PDUs and properly encode them when using v3
auth/encryption.
Reported by: harti@
Modified:
head/contrib/bsnmp/lib/snmp.c
head/contrib/bsnmp/lib/snmp.h
head/contrib/bsnmp/lib/snmpagent.c
Modified: head/contrib/bsnmp/lib/snmp.c
==============================================================================
--- head/contrib/bsnmp/lib/snmp.c Thu Oct 17 11:45:31 2013
(r256677)
+++ head/contrib/bsnmp/lib/snmp.c Thu Oct 17 11:49:46 2013
(r256678)
@@ -288,11 +288,13 @@ parse_secparams(struct asn_buf *b, struc
memset(buf, 0, 256);
tb.asn_ptr = buf;
tb.asn_len = 256;
+ u_int len;
- if (asn_get_octetstring(b, buf, &tb.asn_len) != ASN_ERR_OK) {
+ 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");
@@ -864,7 +866,7 @@ snmp_fix_encoding(struct asn_buf *b, str
return (SNMP_CODE_FAILED);
pdu->scoped_len = b->asn_ptr - pdu->scoped_ptr;
- if ((code = snmp_pdu_fix_padd(b, pdu))!= ASN_ERR_OK)
+ if (snmp_pdu_fix_padd(b, pdu) != ASN_ERR_OK)
return (SNMP_CODE_FAILED);
if (pdu->security_model != SNMP_SECMODEL_USM)
@@ -997,7 +999,7 @@ snmp_pdu_encode(struct snmp_pdu *pdu, st
if ((err = snmp_pdu_encode_header(resp_b, pdu)) != SNMP_CODE_OK)
return (err);
for (idx = 0; idx < pdu->nbindings; idx++)
- if ((err = snmp_binding_encode(resp_b, &pdu->bindings[idx]))
+ if (snmp_binding_encode(resp_b, &pdu->bindings[idx])
!= ASN_ERR_OK)
return (SNMP_CODE_FAILED);
Modified: head/contrib/bsnmp/lib/snmp.h
==============================================================================
--- head/contrib/bsnmp/lib/snmp.h Thu Oct 17 11:45:31 2013
(r256677)
+++ head/contrib/bsnmp/lib/snmp.h Thu Oct 17 11:49:46 2013
(r256678)
@@ -182,7 +182,7 @@ struct snmp_pdu {
/* fixes for encoding */
size_t outer_len;
- size_t scoped_len;
+ asn_len_t scoped_len;
u_char *outer_ptr;
u_char *digest_ptr;
u_char *encrypted_ptr;
Modified: head/contrib/bsnmp/lib/snmpagent.c
==============================================================================
--- head/contrib/bsnmp/lib/snmpagent.c Thu Oct 17 11:45:31 2013
(r256677)
+++ head/contrib/bsnmp/lib/snmpagent.c Thu Oct 17 11:49:46 2013
(r256678)
@@ -166,7 +166,7 @@ find_subnode(const struct snmp_value *va
}
static void
-snmp_pdu_create_response(struct snmp_pdu *pdu, struct snmp_pdu *resp)
+snmp_pdu_create_response(const struct snmp_pdu *pdu, struct snmp_pdu *resp)
{
memset(resp, 0, sizeof(*resp));
strcpy(resp->community, pdu->community);
@@ -952,18 +952,57 @@ enum snmp_ret
snmp_make_errresp(const struct snmp_pdu *pdu, struct asn_buf *pdu_b,
struct asn_buf *resp_b)
{
+ u_char type;
asn_len_t len;
struct snmp_pdu resp;
enum asn_err err;
enum snmp_code code;
- memset(&resp, 0, sizeof(resp));
+ snmp_pdu_create_response(pdu, &resp);
+
if ((code = snmp_pdu_decode_header(pdu_b, &resp)) != SNMP_CODE_OK)
return (SNMP_RET_IGN);
- if (pdu_b->asn_len < len)
+ if (pdu->version == SNMP_V3) {
+ if (resp.user.priv_proto != SNMP_PRIV_NOPRIV &&
+ (asn_get_header(pdu_b, &type, &resp.scoped_len) != ASN_ERR_OK
+ || type != ASN_TYPE_OCTETSTRING)) {
+ snmp_error("cannot decode encrypted pdu");
+ return (SNMP_RET_IGN);
+ }
+
+ if (asn_get_sequence(pdu_b, &len) != ASN_ERR_OK) {
+ snmp_error("cannot decode scoped pdu header");
+ return (SNMP_RET_IGN);
+ }
+
+ len = SNMP_ENGINE_ID_SIZ;
+ if (asn_get_octetstring(pdu_b, (u_char *)resp.context_engine,
+ &len) != ASN_ERR_OK) {
+ snmp_error("cannot decode msg context engine");
+ return (SNMP_RET_IGN);
+ }
+ resp.context_engine_len = len;
+ len = SNMP_CONTEXT_NAME_SIZ;
+ if (asn_get_octetstring(pdu_b, (u_char *)resp.context_name,
+ &len) != ASN_ERR_OK) {
+ snmp_error("cannot decode msg context name");
+ return (SNMP_RET_IGN);
+ }
+ resp.context_name[len] = '\0';
+ }
+
+
+ if (asn_get_header(pdu_b, &type, &len) != ASN_ERR_OK) {
+ snmp_error("cannot get pdu header");
return (SNMP_RET_IGN);
- pdu_b->asn_len = len;
+ }
+
+ if ((type & ~ASN_TYPE_MASK) !=
+ (ASN_TYPE_CONSTRUCTED | ASN_CLASS_CONTEXT)) {
+ snmp_error("bad pdu header tag");
+ return (SNMP_RET_IGN);
+ }
err = snmp_parse_pdus_hdr(pdu_b, &resp, &len);
if (ASN_ERR_STOPPED(err))
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