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Fix SNMP Error response PDUs and properly encode them when using v3 auth/encryption.

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Reported by:	harti@
This commit is contained in:
syrinx 2013-10-17 11:49:46 +00:00
parent b7fd4846e5
commit f7282ff245
3 changed files with 49 additions and 8 deletions
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8
contrib/bsnmp/lib/snmp.c
View File

@ -288,11 +288,13 @@ parse_secparams(struct asn_buf *b, struct snmp_pdu *pdu)
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, struct snmp_pdu *pdu)
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, struct asn_buf *resp_b)
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);

2
contrib/bsnmp/lib/snmp.h
View File

@ -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;

47
contrib/bsnmp/lib/snmpagent.c
View File

@ -166,7 +166,7 @@ find_subnode(const struct snmp_value *value)
}
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))