/* Allocate, fill, and return cksumlens array of checksum lengths.
** This array holds just the unique elements from the krb5_cksumarray[].
** array[n] == 0 signals end of data.
**
** The krb5_cksumarray[] was an internal variable that has since been
** replaced by a more general method for storing the data. It should
** not be used. Instead we use real API calls and make a guess for
** what the highest assigned CKSUMTYPE_ constant is. As of 1.2.2
** it is 0x000c (CKSUMTYPE_HMAC_SHA1_DES3). So we will use 0x0010.
*/
static size_t
*populate_cksumlens(void)
{
int i, j, n;
static size_t *cklens = NULL;
#ifdef KRB5_MIT_OLD11
n = krb5_max_cksum;
#else
n = 0x0010;
#endif /* KRB5_MIT_OLD11 */
#ifdef KRB5CHECKAUTH
if (!cklens && !(cklens = (size_t *)
calloc(sizeof(int), n + 1))) return NULL;
for (i = 0; i < n; i++) {
if (!valid_cksumtype(i))
continue; /* array has holes */
for (j = 0; j < n; j++) {
if (cklens[j] == 0) {
cklens[j] = krb5_checksum_size(NULL, i);
break;
/* krb5 elem was new: add */
}
if (cklens[j] == krb5_checksum_size(NULL, i)) {
break;
/* ignore duplicate elements */
}
}
}
#endif /* KRB5CHECKAUTH */
return cklens;
}
int
ksm_rgenerate_out_msg(struct snmp_secmod_outgoing_params *parms)
{
krb5_auth_context auth_context = NULL;
krb5_error_code retcode;
krb5_ccache cc = NULL;
int retval = SNMPERR_SUCCESS;
krb5_data outdata, ivector;
krb5_keyblock *subkey = NULL;
#ifdef MIT_NEW_CRYPTO
krb5_data input;
krb5_enc_data output;
unsigned int numcksumtypes;
krb5_cksumtype *cksumtype_array;
#else /* MIT_NEW_CRYPTO */
krb5_encrypt_block eblock;
#endif /* MIT_NEW_CRYPTO */
size_t blocksize, encrypted_length;
unsigned char *encrypted_data = NULL;
int zero = 0, i;
u_char *cksum_pointer, *endp = *parms->wholeMsg;
krb5_cksumtype cksumtype;
krb5_checksum pdu_checksum;
u_char **wholeMsg = parms->wholeMsg;
size_t *offset = parms->wholeMsgOffset, seq_offset;
struct ksm_secStateRef *ksm_state = (struct ksm_secStateRef *)
parms->secStateRef;
int rc;
DEBUGMSGTL(("ksm", "Starting KSM processing\n"));
outdata.length = 0;
outdata.data = NULL;
ivector.length = 0;
ivector.data = NULL;
pdu_checksum.contents = NULL;
if (!ksm_state) {
/*
* If we don't have a ksm_state, then we're a request. Get a
* credential cache and build a ap_req.
*/
retcode = krb5_cc_default(kcontext, &cc);
if (retcode) {
DEBUGMSGTL(("ksm", "KSM: krb5_cc_default failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
DEBUGMSGTL(("ksm", "KSM: Set credential cache successfully\n"));
/*
* This seems odd, since we don't need this until later (or earlier,
* depending on how you look at it), but because the most likely
* errors are Kerberos at this point, I'll get this now to save
* time not encoding the rest of the packet.
*
* Also, we need the subkey to encrypt the PDU (if required).
*/
retcode =
krb5_mk_req(kcontext, &auth_context,
AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
(char *) service_name, parms->session->peername, NULL,
cc, &outdata);
if (retcode) {
DEBUGMSGTL(("ksm", "KSM: krb5_mk_req failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
DEBUGMSGTL(("ksm", "KSM: ticket retrieved successfully for \"%s/%s\" "
"(may not be actual ticket sname)\n", service_name,
parms->session->peername));
} else {
/*
* Grab the auth_context from our security state reference
*/
auth_context = ksm_state->auth_context;
/*
* Bundle up an AP_REP. Note that we do this only when we
* have a security state reference (which means we're in an agent
* and we're sending a response).
*/
DEBUGMSGTL(("ksm", "KSM: Starting reply processing.\n"));
retcode = krb5_mk_rep(kcontext, auth_context, &outdata);
if (retcode) {
DEBUGMSGTL(("ksm", "KSM: krb5_mk_rep failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
DEBUGMSGTL(("ksm", "KSM: Finished with krb5_mk_rep()\n"));
}
/*
* If we have to encrypt the PDU, do that now
*/
if (parms->secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
DEBUGMSGTL(("ksm", "KSM: Starting PDU encryption.\n"));
/*
* It's weird -
*
* If we're on the manager, it's a local subkey (because that's in
* our AP_REQ)
*
* If we're on the agent, it's a remote subkey (because that comes
* FROM the received AP_REQ).
*/
if (ksm_state)
retcode = krb5_auth_con_getremotesubkey(kcontext, auth_context,
&subkey);
else
retcode = krb5_auth_con_getlocalsubkey(kcontext, auth_context,
&subkey);
if (retcode) {
DEBUGMSGTL(("ksm",
"KSM: krb5_auth_con_getlocalsubkey failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
/*
* Note that here we need to handle different things between the
* old and new crypto APIs. First, we need to get the final encrypted
* length of the PDU.
*/
#ifdef MIT_NEW_CRYPTO
retcode = krb5_c_encrypt_length(kcontext, subkey->enctype,
parms->scopedPduLen,
&encrypted_length);
if (retcode) {
DEBUGMSGTL(("ksm",
"Encryption length calculation failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
#else /* MIT_NEW_CRYPTO */
krb5_use_enctype(kcontext, &eblock, subkey->enctype);
retcode = krb5_process_key(kcontext, &eblock, subkey);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_process_key failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
encrypted_length = krb5_encrypt_size(parms->scopedPduLen,
eblock.crypto_entry);
#endif /* MIT_NEW_CRYPTO */
encrypted_data = malloc(encrypted_length);
if (!encrypted_data) {
DEBUGMSGTL(("ksm",
"KSM: Unable to malloc %d bytes for encrypt "
"buffer: %s\n", parms->scopedPduLen,
strerror(errno)));
retval = SNMPERR_MALLOC;
#ifndef MIT_NEW_CRYPTO
krb5_finish_key(kcontext, &eblock);
#endif /* ! MIT_NEW_CRYPTO */
goto error;
}
/*
* We need to set up a blank initialization vector for the encryption.
* Use a block of all zero's (which is dependent on the block size
* of the encryption method).
*/
#ifdef MIT_NEW_CRYPTO
retcode = krb5_c_block_size(kcontext, subkey->enctype, &blocksize);
if (retcode) {
DEBUGMSGTL(("ksm",
"Unable to determine crypto block size: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
#else /* MIT_NEW_CRYPTO */
blocksize =
krb5_enctype_array[subkey->enctype]->system->block_length;
#endif /* MIT_NEW_CRYPTO */
ivector.data = malloc(blocksize);
if (!ivector.data) {
DEBUGMSGTL(("ksm", "Unable to allocate %d bytes for ivector\n",
blocksize));
retval = SNMPERR_MALLOC;
goto error;
}
ivector.length = blocksize;
memset(ivector.data, 0, blocksize);
/*
* Finally! Do the encryption!
*/
#ifdef MIT_NEW_CRYPTO
input.data = (char *) parms->scopedPdu;
input.length = parms->scopedPduLen;
output.ciphertext.data = (char *) encrypted_data;
output.ciphertext.length = encrypted_length;
retcode =
krb5_c_encrypt(kcontext, subkey, KSM_KEY_USAGE_ENCRYPTION,
&ivector, &input, &output);
#else /* MIT_NEW_CRYPTO */
retcode = krb5_encrypt(kcontext, (krb5_pointer) parms->scopedPdu,
(krb5_pointer) encrypted_data,
parms->scopedPduLen, &eblock, ivector.data);
krb5_finish_key(kcontext, &eblock);
#endif /* MIT_NEW_CRYPTO */
if (retcode) {
DEBUGMSGTL(("ksm", "KSM: krb5_encrypt failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
*offset = 0;
rc = asn_realloc_rbuild_string(wholeMsg, parms->wholeMsgLen,
offset, 1,
(u_char) (ASN_UNIVERSAL |
ASN_PRIMITIVE |
ASN_OCTET_STR),
encrypted_data,
encrypted_length);
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building encrypted payload failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
DEBUGMSGTL(("ksm", "KSM: Encryption complete.\n"));
} else {
/*
* Plaintext PDU (not encrypted)
*/
if (*parms->wholeMsgLen < parms->scopedPduLen) {
DEBUGMSGTL(("ksm", "Not enough room for plaintext PDU.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
}
/*
* Start encoding the msgSecurityParameters
*
* For now, use 0 for the response hint
*/
DEBUGMSGTL(("ksm", "KSM: scopedPdu added to payload\n"));
seq_offset = *offset;
rc = asn_realloc_rbuild_int(wholeMsg, parms->wholeMsgLen,
offset, 1,
(u_char) (ASN_UNIVERSAL |
ASN_PRIMITIVE |
ASN_INTEGER),
(long *) &zero, sizeof(zero));
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
rc = asn_realloc_rbuild_string(wholeMsg, parms->wholeMsgLen,
offset, 1,
(u_char) (ASN_UNIVERSAL |
ASN_PRIMITIVE |
ASN_OCTET_STR),
(u_char *) outdata.data,
outdata.length);
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building ksm AP_REQ failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
/*
* Now, we need to pick the "right" checksum algorithm. For old
* crypto, just pick CKSUMTYPE_RSA_MD5_DES; for new crypto, pick
* one of the "approved" ones.
*/
#ifdef MIT_NEW_CRYPTO
retcode = krb5_c_keyed_checksum_types(kcontext, subkey->enctype,
&numcksumtypes, &cksumtype_array);
if (retcode) {
DEBUGMSGTL(("ksm", "Unable to find appropriate keyed checksum: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
if (numcksumtypes <= 0) {
DEBUGMSGTL(("ksm", "We received a list of zero cksumtypes for this "
"enctype (%d)\n", subkey->enctype));
snmp_set_detail("No valid checksum type for this encryption type");
retval = SNMPERR_KRB5;
goto error;
}
/*
* It's not clear to me from the API which checksum you're supposed
* to support, so I'm taking a guess at the first one
*/
cksumtype = cksumtype_array[0];
krb5_free_cksumtypes(kcontext, cksumtype_array);
DEBUGMSGTL(("ksm", "KSM: Choosing checksum type of %d (subkey type "
"of %d)\n", cksumtype, subkey->enctype));
retcode = krb5_c_checksum_length(kcontext, cksumtype, &blocksize);
if (retcode) {
DEBUGMSGTL(("ksm", "Unable to determine checksum length: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
pdu_checksum.length = blocksize;
#else /* MIT_NEW_CRYPTO */
if (ksm_state)
cksumtype = ksm_state->cksumtype;
else
cksumtype = CKSUMTYPE_RSA_MD5_DES;
if (!is_keyed_cksum(cksumtype)) {
DEBUGMSGTL(("ksm", "Checksum type %d is not a keyed checksum\n",
cksumtype));
snmp_set_detail("Checksum is not a keyed checksum");
retval = SNMPERR_KRB5;
goto error;
}
if (!is_coll_proof_cksum(cksumtype)) {
DEBUGMSGTL(("ksm", "Checksum type %d is not a collision-proof "
"checksum\n", cksumtype));
snmp_set_detail("Checksum is not a collision-proof checksum");
retval = SNMPERR_KRB5;
goto error;
}
pdu_checksum.length = krb5_checksum_size(kcontext, cksumtype);
pdu_checksum.checksum_type = cksumtype;
#endif /* MIT_NEW_CRYPTO */
/*
* Note that here, we're just leaving blank space for the checksum;
* we remember where that is, and we'll fill it in later.
*/
*offset += pdu_checksum.length;
memset(*wholeMsg + *parms->wholeMsgLen - *offset, 0, pdu_checksum.length);
cksum_pointer = *wholeMsg + *parms->wholeMsgLen - *offset;
rc = asn_realloc_rbuild_header(wholeMsg, parms->wholeMsgLen,
parms->wholeMsgOffset, 1,
(u_char) (ASN_UNIVERSAL |
ASN_PRIMITIVE |
ASN_OCTET_STR),
pdu_checksum.length);
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
rc = asn_realloc_rbuild_int(wholeMsg, parms->wholeMsgLen,
parms->wholeMsgOffset, 1,
(u_char) (ASN_UNIVERSAL |
ASN_PRIMITIVE |
ASN_OCTET_STR),
(long *) &cksumtype,
sizeof(cksumtype));
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
rc = asn_realloc_rbuild_sequence(wholeMsg, parms->wholeMsgLen,
parms->wholeMsgOffset, 1,
(u_char) (ASN_SEQUENCE |
ASN_CONSTRUCTOR),
*offset - seq_offset);
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
rc = asn_realloc_rbuild_header(wholeMsg, parms->wholeMsgLen,
parms->wholeMsgOffset, 1,
(u_char) (ASN_UNIVERSAL |
ASN_PRIMITIVE |
ASN_OCTET_STR),
*offset - seq_offset);
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
DEBUGMSGTL(("ksm", "KSM: Security parameter encoding completed\n"));
/*
* We're done with the KSM security parameters - now we do the global
* header and wrap up the whole PDU.
*/
if (*parms->wholeMsgLen < parms->globalDataLen) {
DEBUGMSGTL(("ksm", "Building global data failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
*offset += parms->globalDataLen;
memcpy(*wholeMsg + *parms->wholeMsgLen - *offset,
parms->globalData, parms->globalDataLen);
rc = asn_realloc_rbuild_sequence(wholeMsg, parms->wholeMsgLen,
offset, 1,
(u_char) (ASN_SEQUENCE |
ASN_CONSTRUCTOR),
*offset);
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building master packet sequence.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
DEBUGMSGTL(("ksm", "KSM: PDU master packet encoding complete.\n"));
/*
* Now we need to checksum the entire PDU (since it's built).
*/
pdu_checksum.contents = malloc(pdu_checksum.length);
if (!pdu_checksum.contents) {
DEBUGMSGTL(("ksm", "Unable to malloc %d bytes for checksum\n",
pdu_checksum.length));
retval = SNMPERR_MALLOC;
goto error;
}
/*
* If we didn't encrypt the packet, we haven't yet got the subkey.
* Get that now.
*/
if (!subkey) {
if (ksm_state)
retcode = krb5_auth_con_getremotesubkey(kcontext, auth_context,
&subkey);
else
retcode = krb5_auth_con_getlocalsubkey(kcontext, auth_context,
&subkey);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_auth_con_getlocalsubkey failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
}
#ifdef MIT_NEW_CRYPTO
input.data = (char *) (*wholeMsg + *parms->wholeMsgLen - *offset);
input.length = *offset;
retcode = krb5_c_make_checksum(kcontext, cksumtype, subkey,
KSM_KEY_USAGE_CHECKSUM, &input,
&pdu_checksum);
#else /* MIT_NEW_CRYPTO */
retcode = krb5_calculate_checksum(kcontext, cksumtype, *wholeMsg +
*parms->wholeMsgLen - *offset,
*offset,
(krb5_pointer) subkey->contents,
subkey->length, &pdu_checksum);
#endif /* MIT_NEW_CRYPTO */
if (retcode) {
DEBUGMSGTL(("ksm", "Calculate checksum failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
DEBUGMSGTL(("ksm", "KSM: Checksum calculation complete.\n"));
memcpy(cksum_pointer, pdu_checksum.contents, pdu_checksum.length);
DEBUGMSGTL(("ksm", "KSM: Writing checksum of %d bytes at offset %d\n",
pdu_checksum.length, cksum_pointer - (*wholeMsg + 1)));
DEBUGMSGTL(("ksm", "KSM: Checksum:"));
for (i = 0; i < pdu_checksum.length; i++)
DEBUGMSG(("ksm", " %02x",
(unsigned int) pdu_checksum.contents[i]));
DEBUGMSG(("ksm", "\n"));
/*
* If we're _not_ called as part of a response (null ksm_state),
* then save the auth_context for later using our cache routines.
*/
if (!ksm_state) {
if ((retval = ksm_insert_cache(parms->pdu->msgid, auth_context,
(u_char *) parms->secName,
parms->secNameLen)) !=
SNMPERR_SUCCESS)
goto error;
auth_context = NULL;
}
DEBUGMSGTL(("ksm", "KSM processing complete!\n"));
error:
if (pdu_checksum.contents)
#ifdef MIT_NEW_CRYPTO
krb5_free_checksum_contents(kcontext, &pdu_checksum);
#else /* MIT_NEW_CRYPTO */
free(pdu_checksum.contents);
#endif /* MIT_NEW_CRYPTO */
if (ivector.data)
free(ivector.data);
if (subkey)
krb5_free_keyblock(kcontext, subkey);
if (encrypted_data)
free(encrypted_data);
if (cc)
krb5_cc_close(kcontext, cc);
if (auth_context && !ksm_state)
krb5_auth_con_free(kcontext, auth_context);
return retval;
}