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gfiber / vendor / opensource / netsnmp / 1844896fbbe502453a13cc05e2b3c7ac8db82d1f / . / snmplib / snmpksm.c
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/*
* snmpksm.c
*
* This code implements the Kerberos Security Model (KSM) for SNMP.
*
* Security number - 2066432
*/
#include <net-snmp/net-snmp-config.h>
#include <sys/types.h>
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
# include <sys/time.h>
# else
# include <time.h>
# endif
#endif
#if HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <errno.h>
#if HAVE_DMALLOC_H
#include <dmalloc.h>
#endif
#ifdef NETSNMP_USE_KERBEROS_HEIMDAL
#ifndef NETSNMP_USE_KERBEROS_MIT
#define OLD_HEIMDAL
#endif /* ! NETSNMP_USE_KERBEROS_MIT */
#else
#define KRB5_DEPRECATED 1
#endif /* NETSNMP_USE_KERBEROS_HEIMDAL */
#ifdef NETSNMP_USE_KERBEROS_HEIMDAL
#define oid heimdal_oid_renamed
#endif /* NETSNMP_USE_KERBEROS_HEIMDAL */
#include <krb5.h>
#ifdef NETSNMP_USE_KERBEROS_HEIMDAL
#undef oid
#endif /* NETSNMP_USE_KERBEROS_HEIMDAL */
#ifdef NETSNMP_USE_KERBEROS_HEIMDAL
#define CHECKSUM_TYPE(x) (x)->cksumtype
#define CHECKSUM_CONTENTS(x) (x)->checksum.data
#define CHECKSUM_LENGTH(x) (x)->checksum.length
#define TICKET_CLIENT(x) (x)->client
#else /* NETSNMP_USE_KERBEROS_HEIMDAL */
#define CHECKSUM_TYPE(x) (x)->checksum_type
#define CHECKSUM_CONTENTS(x) (x)->contents
#define CHECKSUM_LENGTH(x) (x)->length
#define TICKET_CLIENT(x) (x)->enc_part2->client
#endif /* NETSNMP_USE_KERBEROS_HEIMDAL */
#include <net-snmp/output_api.h>
#include <net-snmp/config_api.h>
#include <net-snmp/utilities.h>
#include <net-snmp/library/asn1.h>
#include <net-snmp/library/snmp_api.h>
#include <net-snmp/library/callback.h>
#include <net-snmp/library/keytools.h>
#include <net-snmp/library/snmpv3.h>
#include <net-snmp/library/lcd_time.h>
#include <net-snmp/library/scapi.h>
#include <net-snmp/library/callback.h>
#include <net-snmp/library/snmp_secmod.h>
#include <net-snmp/library/snmpksm.h>
static krb5_context kcontext = NULL;
static krb5_rcache rcache = NULL;
static krb5_keytab keytab = NULL;
static int keytab_setup = 0;
static char *service_name = NULL;
static char service_host[] = "host";
static u_char null_id[] = {0};
static int ksm_session_init(netsnmp_session *);
static void ksm_free_state_ref(void *);
static int ksm_free_pdu(netsnmp_pdu *);
static int ksm_clone_pdu(netsnmp_pdu *, netsnmp_pdu *);
static int ksm_insert_cache(long, krb5_auth_context, u_char *,
size_t);
static void ksm_decrement_ref_count(long);
static void ksm_increment_ref_count(long);
static struct ksm_cache_entry *ksm_get_cache(long);
#if !defined(HAVE_KRB5_AUTH_CON_GETSENDSUBKEY) /* Heimdal */
krb5_error_code krb5_auth_con_getsendsubkey(krb5_context context,
krb5_auth_context auth_context,
krb5_keyblock **keyblock)
{
return krb5_auth_con_getlocalsubkey(context, auth_context, keyblock);
}
krb5_error_code krb5_auth_con_getrecvsubkey(krb5_context context,
krb5_auth_context auth_context,
krb5_keyblock **keyblock)
{
return krb5_auth_con_getremotesubkey(context, auth_context, keyblock);
}
#endif
#define HASHSIZE 64
/*
* Our information stored for the response PDU.
*/
struct ksm_secStateRef {
krb5_auth_context auth_context;
krb5_cksumtype cksumtype;
};
/*
* A KSM outgoing pdu cache entry
*/
struct ksm_cache_entry {
long msgid;
int refcount;
krb5_auth_context auth_context;
u_char *secName;
size_t secNameLen;
struct ksm_cache_entry *next;
};
/*
* Poor man's hash table
*/
static struct ksm_cache_entry *ksm_hash_table[HASHSIZE];
/*
* Stuff to deal with config values
* Note the conditionals that wrap these--i don't know if these are
* needed, since i don't know how library initialization and callbacks
* and stuff work
*/
static int
init_snmpksm_post_config(int majorid, int minorid, void *serverarg,
void *clientarg)
{
if (kcontext == NULL) {
/* not reached, i'd imagine */
return SNMPERR_KRB5;
}
if (service_name == NULL) {
/* always reached, i'd imagine */
char *c = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID,
NETSNMP_DS_LIB_KSM_SERVICE_NAME);
if (c != NULL) {
service_name = c;
}
else {
service_name = service_host;
}
}
if (keytab_setup == 0) {
/* always reached, i'd imagine */
char *c = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID,
NETSNMP_DS_LIB_KSM_KEYTAB);
if (c) {
krb5_error_code retval;
DEBUGMSGTL(("ksm", "Using keytab %s\n", c));
retval = krb5_kt_resolve(kcontext, c, &keytab);
if (retval) {
DEBUGMSGTL(("ksm", "krb5_kt_resolve(\"%s\") failed. KSM "
"config callback failing\n", error_message(retval)));
return SNMPERR_KRB5;
}
}
else {
DEBUGMSGTL(("ksm", "Using default keytab\n"));
}
keytab_setup = 1;
}
return SNMPERR_SUCCESS;
}
/*
* Initialize all of the state required for Kerberos (right now, just call
* krb5_init_context).
*/
void
init_ksm(void)
{
krb5_error_code retval;
struct snmp_secmod_def *def;
int i;
netsnmp_ds_register_config(ASN_OCTET_STR, "snmp", "defKSMKeytab",
NETSNMP_DS_LIBRARY_ID, NETSNMP_DS_LIB_KSM_KEYTAB);
netsnmp_ds_register_config(ASN_OCTET_STR, "snmp", "defKSMServiceName",
NETSNMP_DS_LIBRARY_ID,
NETSNMP_DS_LIB_KSM_SERVICE_NAME);
snmp_register_callback(SNMP_CALLBACK_LIBRARY,
SNMP_CALLBACK_POST_READ_CONFIG,
init_snmpksm_post_config, NULL);
if (kcontext == NULL) {
retval = krb5_init_context(&kcontext);
if (retval) {
DEBUGMSGTL(("ksm", "krb5_init_context failed (%s), not "
"registering KSM\n", error_message(retval)));
return;
}
}
for (i = 0; i < HASHSIZE; i++)
ksm_hash_table[i] = NULL;
def = SNMP_MALLOC_STRUCT(snmp_secmod_def);
if (!def) {
DEBUGMSGTL(("ksm", "Unable to malloc snmp_secmod struct, not "
"registering KSM\n"));
return;
}
def->encode_reverse = ksm_rgenerate_out_msg;
def->decode = ksm_process_in_msg;
def->session_open = ksm_session_init;
def->pdu_free_state_ref = ksm_free_state_ref;
def->pdu_free = ksm_free_pdu;
def->pdu_clone = ksm_clone_pdu;
register_sec_mod(NETSNMP_SEC_MODEL_KSM, "ksm", def);
}
/*
* These routines implement a simple cache for information we need to
* process responses. When we send out a request, it contains an AP_REQ;
* we get back an AP_REP, and we need the authorization context from the
* AP_REQ to decrypt the AP_REP. But because right now there's nothing
* that gets preserved across calls to rgenerate_out_msg to process_in_msg,
* we cache these internally based on the message ID (we also cache the
* passed-in security name, for reasons that are mostly stupid).
*/
static int
ksm_insert_cache(long msgid, krb5_auth_context auth_context,
u_char * secName, size_t secNameLen)
{
struct ksm_cache_entry *entry;
int bucket;
entry = SNMP_MALLOC_STRUCT(ksm_cache_entry);
if (!entry)
return SNMPERR_MALLOC;
entry->msgid = msgid;
entry->auth_context = auth_context;
entry->refcount = 1;
entry->secName = netsnmp_memdup(secName, secNameLen);
if (secName && !entry->secName) {
free(entry);
return SNMPERR_GENERR;
}
entry->secNameLen = secNameLen;
bucket = msgid % HASHSIZE;
entry->next = ksm_hash_table[bucket];
ksm_hash_table[bucket] = entry;
return SNMPERR_SUCCESS;
}
static struct ksm_cache_entry *
ksm_get_cache(long msgid)
{
struct ksm_cache_entry *entry;
int bucket;
bucket = msgid % HASHSIZE;
for (entry = ksm_hash_table[bucket]; entry != NULL;
entry = entry->next)
if (entry->msgid == msgid)
return entry;
return NULL;
}
static void
ksm_decrement_ref_count(long msgid)
{
struct ksm_cache_entry *entry, *entry1;
int bucket;
bucket = msgid % HASHSIZE;
if (ksm_hash_table[bucket] && ksm_hash_table[bucket]->msgid == msgid) {
entry = ksm_hash_table[bucket];
/*
* If the reference count is zero, then free it
*/
if (--entry->refcount <= 0) {
DEBUGMSGTL(("ksm", "Freeing entry for msgid %ld\n", msgid));
krb5_auth_con_free(kcontext, entry->auth_context);
free(entry->secName);
ksm_hash_table[bucket] = entry->next;
free(entry);
}
return;
} else if (ksm_hash_table[bucket])
for (entry1 = ksm_hash_table[bucket], entry = entry1->next;
entry != NULL; entry1 = entry, entry = entry->next)
if (entry->msgid == msgid) {
if (--entry->refcount <= 0) {
DEBUGMSGTL(("ksm", "Freeing entry for msgid %ld\n",
msgid));
krb5_auth_con_free(kcontext, entry->auth_context);
free(entry->secName);
entry1->next = entry->next;
free(entry);
}
return;
}
DEBUGMSGTL(("ksm",
"KSM: Unable to decrement cache entry for msgid %ld.\n",
msgid));
}
static void
ksm_increment_ref_count(long msgid)
{
struct ksm_cache_entry *entry = ksm_get_cache(msgid);
if (!entry) {
DEBUGMSGTL(("ksm", "Unable to find cache entry for msgid %ld "
"for increment\n", msgid));
return;
}
entry->refcount++;
}
/*
* Initialize specific session information (right now, just set up things to
* not do an engineID probe)
*/
static int
ksm_session_init(netsnmp_session * sess)
{
DEBUGMSGTL(("ksm",
"KSM: Reached our session initialization callback\n"));
sess->flags |= SNMP_FLAGS_DONT_PROBE;
return SNMPERR_SUCCESS;
}
/*
* Free our state information (this is only done on the agent side)
*/
static void
ksm_free_state_ref(void *ptr)
{
struct ksm_secStateRef *ref = (struct ksm_secStateRef *) ptr;
DEBUGMSGTL(("ksm", "KSM: Freeing state reference\n"));
krb5_auth_con_free(kcontext, ref->auth_context);
free(ref);
}
/*
* This is called when the PDU is freed; this will decrement reference counts
* for entries in our state cache.
*/
static int
ksm_free_pdu(netsnmp_pdu *pdu)
{
ksm_decrement_ref_count(pdu->msgid);
DEBUGMSGTL(("ksm", "Decrementing cache entry for PDU msgid %ld\n",
pdu->msgid));
return SNMPERR_SUCCESS;
}
/*
* This is called when a PDU is cloned (to increase reference counts)
*/
static int
ksm_clone_pdu(netsnmp_pdu *pdu, netsnmp_pdu *pdu2)
{
ksm_increment_ref_count(pdu->msgid);
DEBUGMSGTL(("ksm", "Incrementing cache entry for PDU msgid %ld\n",
pdu->msgid));
return SNMPERR_SUCCESS;
}
/****************************************************************************
*
* ksm_generate_out_msg
*
* Parameters:
* (See list below...)
*
* Returns:
* SNMPERR_GENERIC On success.
* SNMPERR_KRB5
* ... and others
*
*
* Generate an outgoing message.
*
****************************************************************************/
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 NETSNMP_USE_KERBEROS_MIT
krb5_data input;
krb5_enc_data output;
unsigned int numcksumtypes;
krb5_cksumtype *cksumtype_array;
#elif defined OLD_HEIMDAL /* NETSNMP_USE_KERBEROS_MIT */
krb5_crypto heim_crypto = NULL;
#else /* NETSNMP_USE_KERBEROS_MIT */
krb5_encrypt_block eblock;
#endif /* NETSNMP_USE_KERBEROS_MIT */
size_t blocksize, encrypted_length;
unsigned char *encrypted_data = NULL;
long zero = 0, tmp;
int i;
u_char *cksum_pointer;
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;
#ifdef OLD_HEIMDAL
krb5_data encrypted_scoped_pdu;
#endif /* OLD_HEIMDAL */
int rc;
char *colon = NULL;
DEBUGMSGTL(("ksm", "Starting KSM processing\n"));
outdata.length = 0;
outdata.data = NULL;
ivector.length = 0;
ivector.data = NULL;
CHECKSUM_CONTENTS(&pdu_checksum) = NULL;
if (!ksm_state) {
/*
* If we've got a port number as part of the "peername", then
* suppress this (temporarily) while we build the credential info.
* XXX - what about "udp:host" style addresses?
*/
colon = strrchr(parms->session->peername, ':');
if (colon != NULL) {
*colon='\0';
}
/*
* 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,
service_name, parms->session->peername, NULL,
cc, &outdata);
if (colon != NULL)
*colon=':';
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_getrecvsubkey(kcontext, auth_context,
&subkey);
else
retcode = krb5_auth_con_getsendsubkey(kcontext, auth_context,
&subkey);
if (retcode) {
DEBUGMSGTL(("ksm",
"KSM: krb5_auth_con_getsendsubkey 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 NETSNMP_USE_KERBEROS_MIT
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;
}
#elif defined OLD_HEIMDAL
retcode = krb5_crypto_init(kcontext, subkey, 0, &heim_crypto);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_crypto_init failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
encrypted_length = krb5_get_wrapped_length(kcontext, heim_crypto,
parms->scopedPduLen);
#else /* NETSNMP_USE_KERBEROS_MIT */
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 /* NETSNMP_USE_KERBEROS_MIT */
#ifndef OLD_HEIMDAL /* since heimdal allocs the space for us */
encrypted_data = malloc(encrypted_length);
if (!encrypted_data) {
DEBUGMSGTL(("ksm",
"KSM: Unable to malloc %d bytes for encrypt "
"buffer: %s\n", (int)parms->scopedPduLen,
strerror(errno)));
retval = SNMPERR_MALLOC;
#ifndef NETSNMP_USE_KERBEROS_MIT
krb5_finish_key(kcontext, &eblock);
#endif /* ! NETSNMP_USE_KERBEROS_MIT */
goto error;
}
#endif /* ! OLD_HEIMDAL */
/*
* 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 NETSNMP_USE_KERBEROS_MIT
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;
}
#elif defined (OLD_HEIMDAL) /* NETSNMP_USE_KERBEROS_MIT */
#else /* NETSNMP_USE_KERBEROS_MIT */
blocksize =
krb5_enctype_array[subkey->enctype]->system->block_length;
#endif /* NETSNMP_USE_KERBEROS_MIT */
#ifndef OLD_HEIMDAL /* since allocs the space for us */
ivector.data = malloc(blocksize);
if (!ivector.data) {
DEBUGMSGTL(("ksm", "Unable to allocate %d bytes for ivector\n",
(int)blocksize));
retval = SNMPERR_MALLOC;
goto error;
}
ivector.length = blocksize;
memset(ivector.data, 0, blocksize);
#endif /* OLD_HEIMDAL */
/*
* Finally! Do the encryption!
*/
#ifdef NETSNMP_USE_KERBEROS_MIT
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);
#elif defined OLD_HEIMDAL /* NETSNMP_USE_KERBEROS_MIT */
krb5_data_zero(&encrypted_scoped_pdu);
retcode = krb5_encrypt(kcontext, heim_crypto, KSM_KEY_USAGE_ENCRYPTION,
parms->scopedPdu, parms->scopedPduLen,
&encrypted_scoped_pdu);
if (retcode == 0) {
encrypted_length = encrypted_scoped_pdu.length;
encrypted_data = encrypted_scoped_pdu.data;
krb5_data_zero(&encrypted_scoped_pdu);
}
#else /* NETSNMP_USE_KERBEROS_MIT */
retcode = krb5_encrypt(kcontext, (krb5_pointer) parms->scopedPdu,
(krb5_pointer) encrypted_data,
parms->scopedPduLen, &eblock, ivector.data);
krb5_finish_key(kcontext, &eblock);
#endif /* NETSNMP_USE_KERBEROS_MIT */
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;
}
/*
* 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_getrecvsubkey(kcontext, auth_context,
&subkey);
else
retcode = krb5_auth_con_getsendsubkey(kcontext, auth_context,
&subkey);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_auth_con_getsendsubkey failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
#ifdef OLD_HEIMDAL
retcode = krb5_crypto_init(kcontext, subkey, 0, &heim_crypto);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_crypto_init failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
#endif /* OLD_HEIMDAL */
}
/*
* 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 NETSNMP_USE_KERBEROS_MIT
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;
}
CHECKSUM_LENGTH(&pdu_checksum) = blocksize;
#else /* NETSNMP_USE_KERBEROS_MIT */
if (ksm_state)
cksumtype = ksm_state->cksumtype;
else
#ifdef OLD_HEIMDAL
{
/* no way to tell what kind of checksum to use without trying */
retval = krb5_create_checksum(kcontext, heim_crypto,
KSM_KEY_USAGE_CHECKSUM, 0,
parms->scopedPdu, parms->scopedPduLen,
&pdu_checksum);
if (retval) {
DEBUGMSGTL(("ksm", "Unable to create a checksum: %s\n",
error_message(retval)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
cksumtype = CHECKSUM_TYPE(&pdu_checksum);
}
#else /* OLD_HEIMDAL */
cksumtype = CKSUMTYPE_RSA_MD5_DES;
#endif /* OLD_HEIMDAL */
#ifdef OLD_HEIMDAL
if (!krb5_checksum_is_keyed(kcontext, cksumtype)) {
#else /* OLD_HEIMDAL */
if (!is_keyed_cksum(cksumtype)) {
#endif /* OLD_HEIMDAL */
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;
}
#ifdef OLD_HEIMDAL
if (!krb5_checksum_is_collision_proof(kcontext, cksumtype)) {
#else /* OLD_HEIMDAL */
if (!is_coll_proof_cksum(cksumtype)) {
#endif /* OLD_HEIMDAL */
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;
}
#ifdef OLD_HEIMDAL
if (CHECKSUM_CONTENTS(&pdu_checksum) != NULL ) {
/* we did the bogus checksum--don't need to ask for the size again
* or initialize cksumtype; just free the bits */
free(CHECKSUM_CONTENTS(&pdu_checksum));
CHECKSUM_CONTENTS(&pdu_checksum) = NULL;
}
else {
retval = krb5_checksumsize(kcontext, cksumtype,
&CHECKSUM_LENGTH(&pdu_checksum));
if (retval) {
DEBUGMSGTL(("ksm", "Unable to determine checksum length: %s\n",
error_message(retval)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
#else /* OLD_HEIMDAL */
CHECKSUM_LENGTH(&pdu_checksum) = krb5_checksum_size(kcontext, cksumtype);
#endif /* OLD_HEIMDAL */
CHECKSUM_TYPE(&pdu_checksum) = cksumtype;
#ifdef OLD_HEIMDAL
}
#endif /* OLD_HEIMDAL */
#endif /* NETSNMP_USE_KERBEROS_MIT */
/*
* 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 += CHECKSUM_LENGTH(&pdu_checksum);
memset(*wholeMsg + *parms->wholeMsgLen - *offset, 0, CHECKSUM_LENGTH(&pdu_checksum));
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),
CHECKSUM_LENGTH(&pdu_checksum));
if (rc == 0) {
DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
retval = SNMPERR_TOO_LONG;
goto error;
}
tmp = cksumtype;
rc = asn_realloc_rbuild_int(wholeMsg, parms->wholeMsgLen,
parms->wholeMsgOffset, 1,
(u_char) (ASN_UNIVERSAL |
ASN_PRIMITIVE |
ASN_INTEGER),
&tmp, sizeof(tmp));
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).
*/
#ifndef OLD_HEIMDAL /* since heimdal allocs the mem for us */
CHECKSUM_CONTENTS(&pdu_checksum) = malloc(CHECKSUM_LENGTH(&pdu_checksum));
if (!CHECKSUM_CONTENTS(&pdu_checksum)) {
DEBUGMSGTL(("ksm", "Unable to malloc %d bytes for checksum\n",
CHECKSUM_LENGTH(&pdu_checksum)));
retval = SNMPERR_MALLOC;
goto error;
}
#endif /* ! OLD_HEIMDAL */
#ifdef NETSNMP_USE_KERBEROS_MIT
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);
#elif defined(OLD_HEIMDAL) /* NETSNMP_USE_KERBEROS_MIT */
retcode = krb5_create_checksum(kcontext, heim_crypto,
KSM_KEY_USAGE_CHECKSUM, cksumtype,
*wholeMsg + *parms->wholeMsgLen
- *offset, *offset, &pdu_checksum);
#else /* NETSNMP_USE_KERBEROS_MIT */
retcode = krb5_calculate_checksum(kcontext, cksumtype, *wholeMsg +
*parms->wholeMsgLen - *offset,
*offset,
(krb5_pointer) subkey->contents,
subkey->length, &pdu_checksum);
#endif /* NETSNMP_USE_KERBEROS_MIT */
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, CHECKSUM_CONTENTS(&pdu_checksum), CHECKSUM_LENGTH(&pdu_checksum));
DEBUGMSGTL(("ksm", "KSM: Writing checksum of %d bytes at offset %d\n",
(int)CHECKSUM_LENGTH(&pdu_checksum),
(int)(cksum_pointer - (*wholeMsg + 1))));
DEBUGMSGTL(("ksm", "KSM: Checksum:"));
for (i = 0; i < CHECKSUM_LENGTH(&pdu_checksum); i++)
DEBUGMSG(("ksm", " %02x",
(unsigned int) ((unsigned char *)CHECKSUM_CONTENTS(&pdu_checksum))[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 (CHECKSUM_CONTENTS(&pdu_checksum))
#ifdef NETSNMP_USE_KERBEROS_MIT
krb5_free_checksum_contents(kcontext, &pdu_checksum);
#else /* NETSNMP_USE_KERBEROS_MIT */
free(CHECKSUM_CONTENTS(&pdu_checksum));
#endif /* NETSNMP_USE_KERBEROS_MIT */
if (ivector.data)
free(ivector.data);
if (subkey)
krb5_free_keyblock(kcontext, subkey);
#ifdef OLD_HEIMDAL /* OLD_HEIMDAL */
if (heim_crypto)
krb5_crypto_destroy(kcontext, heim_crypto);
#endif /* OLD_HEIMDAL */
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;
}
/****************************************************************************
*
* ksm_process_in_msg
*
* Parameters:
* (See list below...)
*
* Returns:
* KSM_ERR_NO_ERROR On success.
* SNMPERR_KRB5
* KSM_ERR_GENERIC_ERROR
* KSM_ERR_UNSUPPORTED_SECURITY_LEVEL
*
*
* Processes an incoming message.
*
****************************************************************************/
int
ksm_process_in_msg(struct snmp_secmod_incoming_params *parms)
{
long temp;
krb5_cksumtype cksumtype;
krb5_auth_context auth_context = NULL;
krb5_error_code retcode;
krb5_checksum checksum;
krb5_data ap_req, ivector;
krb5_flags flags;
krb5_keyblock *subkey = NULL;
#ifdef NETSNMP_USE_KERBEROS_MIT
krb5_data input, output;
krb5_boolean valid;
krb5_enc_data in_crypt;
#elif defined OLD_HEIMDAL /* NETSNMP_USE_KERBEROS_MIT */
krb5_data output;
krb5_crypto heim_crypto = NULL;
#else /* NETSNMP_USE_KERBEROS_MIT */
krb5_encrypt_block eblock;
#endif /* NETSNMP_USE_KERBEROS_MIT */
krb5_ticket *ticket = NULL;
int retval = SNMPERR_SUCCESS, response = 0;
size_t length =
parms->wholeMsgLen - (u_int) (parms->secParams - parms->wholeMsg);
u_char *current = parms->secParams, type;
size_t cksumlength, blocksize;
long hint;
char *cname;
struct ksm_secStateRef *ksm_state;
struct ksm_cache_entry *entry;
DEBUGMSGTL(("ksm", "Processing has begun\n"));
CHECKSUM_CONTENTS(&checksum) = NULL;
ap_req.data = NULL;
ivector.length = 0;
ivector.data = NULL;
/*
* First, parse the security parameters (because we need the subkey inside
* of the ticket to do anything
*/
if ((current = asn_parse_sequence(current, &length, &type,
(ASN_UNIVERSAL | ASN_PRIMITIVE |
ASN_OCTET_STR),
"ksm first octet")) == NULL) {
DEBUGMSGTL(("ksm", "Initial security paramter parsing failed\n"));
retval = SNMPERR_ASN_PARSE_ERR;
goto error;
}
if ((current = asn_parse_sequence(current, &length, &type,
(ASN_SEQUENCE | ASN_CONSTRUCTOR),
"ksm sequence")) == NULL) {
DEBUGMSGTL(("ksm",
"Security parameter sequence parsing failed\n"));
retval = SNMPERR_ASN_PARSE_ERR;
goto error;
}
if ((current = asn_parse_int(current, &length, &type, &temp,
sizeof(temp))) == NULL) {
DEBUGMSGTL(("ksm", "Security parameter checksum type parsing"
"failed\n"));
retval = SNMPERR_ASN_PARSE_ERR;
goto error;
}
cksumtype = temp;
#ifdef NETSNMP_USE_KERBEROS_MIT
if (!krb5_c_valid_cksumtype(cksumtype)) {
DEBUGMSGTL(("ksm", "Invalid checksum type (%d)\n", cksumtype));
retval = SNMPERR_KRB5;
snmp_set_detail("Invalid checksum type");
goto error;
}
if (!krb5_c_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 (!krb5_c_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;
}
#else /* ! NETSNMP_USE_KERBEROS_MIT */
#ifdef OLD_HEIMDAL
/* kludge */
if (krb5_checksumsize(kcontext, cksumtype, &cksumlength)) {
#else /* OLD_HEIMDAL */
if (!valid_cksumtype(cksumtype)) {
#endif /* OLD_HEIMDAL */
DEBUGMSGTL(("ksm", "Invalid checksum type (%d)\n", cksumtype));
retval = SNMPERR_KRB5;
snmp_set_detail("Invalid checksum type");
goto error;
}
#ifdef OLD_HEIMDAL
if (!krb5_checksum_is_keyed(kcontext, cksumtype)) {
#else /* OLD_HEIMDAL */
if (!is_keyed_cksum(cksumtype)) {
#endif /* OLD_HEIMDAL */
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;
}
#ifdef OLD_HEIMDAL
if (!krb5_checksum_is_collision_proof(kcontext, cksumtype)) {
#else /* OLD_HEIMDAL */
if (!is_coll_proof_cksum(cksumtype)) {
#endif /* OLD_HEIMDAL */
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;
}
#endif /* NETSNMP_USE_KERBEROS_MIT */
CHECKSUM_TYPE(&checksum) = cksumtype;
cksumlength = length;
if ((current = asn_parse_sequence(current, &cksumlength, &type,
(ASN_UNIVERSAL | ASN_PRIMITIVE |
ASN_OCTET_STR), "ksm checksum")) ==
NULL) {
DEBUGMSGTL(("ksm",
"Security parameter checksum parsing failed\n"));
retval = SNMPERR_ASN_PARSE_ERR;
goto error;
}
CHECKSUM_CONTENTS(&checksum) = malloc(cksumlength);
if (!CHECKSUM_CONTENTS(&checksum)) {
DEBUGMSGTL(("ksm", "Unable to malloc %d bytes for checksum.\n",
(int)cksumlength));
retval = SNMPERR_MALLOC;
goto error;
}
memcpy(CHECKSUM_CONTENTS(&checksum), current, cksumlength);
CHECKSUM_LENGTH(&checksum) = cksumlength;
CHECKSUM_TYPE(&checksum) = cksumtype;
/*
* Zero out the checksum so the validation works correctly
*/
memset(current, 0, cksumlength);
current += cksumlength;
length = parms->wholeMsgLen - (u_int) (current - parms->wholeMsg);
if ((current = asn_parse_sequence(current, &length, &type,
(ASN_UNIVERSAL | ASN_PRIMITIVE |
ASN_OCTET_STR), "ksm ap_req")) ==
NULL) {
DEBUGMSGTL(("ksm", "KSM security parameter AP_REQ/REP parsing "
"failed\n"));
retval = SNMPERR_ASN_PARSE_ERR;
goto error;
}
ap_req.length = length;
ap_req.data = malloc(length);
if (!ap_req.data) {
DEBUGMSGTL(("ksm",
"KSM unable to malloc %d bytes for AP_REQ/REP.\n",
(int)length));
retval = SNMPERR_MALLOC;
goto error;
}
memcpy(ap_req.data, current, length);
current += length;
length = parms->wholeMsgLen - (u_int) (current - parms->wholeMsg);
if ((current = asn_parse_int(current, &length, &type, &hint,
sizeof(hint))) == NULL) {
DEBUGMSGTL(("ksm",
"KSM security parameter hint parsing failed\n"));
retval = SNMPERR_ASN_PARSE_ERR;
goto error;
}
/*
* Okay! We've got it all! Now try decoding the damn ticket.
*
* But of course there's a WRINKLE! We need to figure out if we're
* processing a AP_REQ or an AP_REP. How do we do that? We're going
* to cheat, and look at the first couple of bytes (which is what
* the Kerberos library routines do anyway).
*
* If there are ever new Kerberos message formats, we'll need to fix
* this here.
*
* If it's a _response_, then we need to get the auth_context
* from our cache.
*/
if (ap_req.length
#ifndef NETSNMP_USE_KERBEROS_HEIMDAL
&& (ap_req.data[0] == 0x6e || ap_req.data[0] == 0x4e)) {
#else /* NETSNMP_USE_KERBEROS_HEIMDAL */
&& (((char *)ap_req.data)[0] == 0x6e || ((char *)ap_req.data)[0] == 0x4e)) {
#endif
/*
* We need to initalize the authorization context, and set the
* replay cache in it (and initialize the replay cache if we
* haven't already
*/
retcode = krb5_auth_con_init(kcontext, &auth_context);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_auth_con_init failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
if (!rcache) {
krb5_data server;
server.data = service_host;
server.length = strlen(server.data);
retcode = krb5_get_server_rcache(kcontext, &server, &rcache);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_get_server_rcache failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
}
retcode = krb5_auth_con_setrcache(kcontext, auth_context, rcache);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_auth_con_setrcache failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
retcode = krb5_rd_req(kcontext, &auth_context, &ap_req, NULL,
keytab, &flags, &ticket);
krb5_auth_con_setrcache(kcontext, auth_context, NULL);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_rd_req() failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
retcode =
krb5_unparse_name(kcontext, TICKET_CLIENT(ticket), &cname);
if (retcode == 0) {
DEBUGMSGTL(("ksm", "KSM authenticated principal name: %s\n",
cname));
free(cname);
}
/*
* Check to make sure AP_OPTS_MUTUAL_REQUIRED was set
*/
if (!(flags & AP_OPTS_MUTUAL_REQUIRED)) {
DEBUGMSGTL(("ksm",
"KSM MUTUAL_REQUIRED not set in request!\n"));
retval = SNMPERR_KRB5;
snmp_set_detail("MUTUAL_REQUIRED not set in message");
goto error;
}
retcode =
krb5_auth_con_getrecvsubkey(kcontext, auth_context, &subkey);
if (retcode) {
DEBUGMSGTL(("ksm", "KSM remote subkey retrieval failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
#ifndef NETSNMP_USE_KERBEROS_HEIMDAL
} else if (ap_req.length && (ap_req.data[0] == 0x6f ||
ap_req.data[0] == 0x4f)) {
#else /* NETSNMP_USE_KERBEROS_HEIMDAL */
} else if (ap_req.length && (((char *)ap_req.data)[0] == 0x6f ||
((char *)ap_req.data)[0] == 0x4f)) {
#endif /* NETSNMP_USE_KERBEROS_HEIMDAL */
/*
* Looks like a response; let's see if we've got that auth_context
* in our cache.
*/
krb5_ap_rep_enc_part *repl = NULL;
response = 1;
entry = ksm_get_cache(parms->pdu->msgid);
if (!entry) {
DEBUGMSGTL(("ksm",
"KSM: Unable to find auth_context for PDU with "
"message ID of %ld\n", parms->pdu->msgid));
retval = SNMPERR_KRB5;
goto error;
}
auth_context = entry->auth_context;
/*
* In that case, let's call the rd_rep function
*/
retcode = krb5_rd_rep(kcontext, auth_context, &ap_req, &repl);
if (repl)
krb5_free_ap_rep_enc_part(kcontext, repl);
if (retcode) {
DEBUGMSGTL(("ksm", "KSM: krb5_rd_rep() failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
goto error;
}
DEBUGMSGTL(("ksm", "KSM: krb5_rd_rep() decoded successfully.\n"));
retcode =
krb5_auth_con_getsendsubkey(kcontext, auth_context, &subkey);
if (retcode) {
DEBUGMSGTL(("ksm", "Unable to retrieve local subkey: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail("Unable to retrieve local subkey");
goto error;
}
} else {
#ifndef NETSNMP_USE_KERBEROS_HEIMDAL
DEBUGMSGTL(("ksm", "Unknown Kerberos message type (%02x)\n",
ap_req.data[0]));
#else /* NETSNMP_USE_KERBEROS_HEIMDAL */
DEBUGMSGTL(("ksm", "Unknown Kerberos message type (%02x)\n",
((char *)ap_req.data)[0]));
#endif
retval = SNMPERR_KRB5;
snmp_set_detail("Unknown Kerberos message type");
goto error;
}
#ifdef NETSNMP_USE_KERBEROS_MIT
input.data = (char *) parms->wholeMsg;
input.length = parms->wholeMsgLen;
retcode =
krb5_c_verify_checksum(kcontext, subkey, KSM_KEY_USAGE_CHECKSUM,
&input, &checksum, &valid);
#elif defined(OLD_HEIMDAL) /* NETSNMP_USE_KERBEROS_MIT */
retcode = krb5_crypto_init(kcontext, subkey, 0, &heim_crypto);
if (retcode) {
DEBUGMSGTL(("ksm", "krb5_crypto_init failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
retcode = krb5_verify_checksum(kcontext, heim_crypto,
KSM_KEY_USAGE_CHECKSUM, parms->wholeMsg,
parms->wholeMsgLen, &checksum);
#else /* NETSNMP_USE_KERBEROS_MIT */
retcode = krb5_verify_checksum(kcontext, cksumtype, &checksum,
parms->wholeMsg, parms->wholeMsgLen,
(krb5_pointer) subkey->contents,
subkey->length);
#endif /* NETSNMP_USE_KERBEROS_MIT */
if (retcode) {
DEBUGMSGTL(("ksm", "KSM checksum verification failed: %s\n",
error_message(retcode)));
retval = SNMPERR_KRB5;
snmp_set_detail(error_message(retcode));
goto error;
}
/*
* Don't ask me why they didn't simply return an error, but we have
* to check to see if "valid" is false.
*/
#ifdef NETSNMP_USE_KERBEROS_MIT
if (!valid) {
DEBUGMSGTL(("ksm", "Computed checksum did not match supplied "
"checksum!\n"));
retval = SNMPERR_KRB5;
snmp_set_detail
("Computed checksum did not match supplied checksum");
goto error;
}
#endif /* NETSNMP_USE_KERBEROS_MIT */
/*
* Handle an encrypted PDU. Note that it's an OCTET_STRING of the
* output of whatever Kerberos cryptosystem you're using (defined by
* the encryption type). Note that this is NOT the EncryptedData
* sequence - it's what goes in the "cipher" field of EncryptedData.
*/
if (parms->secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
if ((current = asn_parse_sequence(current, &length, &type,
(ASN_UNIVERSAL | ASN_PRIMITIVE |
ASN_OCTET_STR), "ksm pdu")) ==
NULL) {
DEBUGMSGTL(("ksm", "KSM sPDU octet decoding failed\n"));
retval = SNMPERR_ASN_PARSE_ERR;
goto error;
}
/*
* The PDU is now pointed at by "current", and the length is in
* "length".
*/
DEBUGMSGTL(("ksm", "KSM starting sPDU decode\n"));
/*
* We need to set up a blank initialization vector for the decryption.
* Use a block of all zero's (which is dependent on the block size
* of the encryption method).
*/
#ifdef NETSNMP_USE_KERBEROS_MIT
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;
}
#elif defined(OLD_HEIMDAL) /* NETSNMP_USE_KERBEROS_MIT */
#else /* NETSNMP_USE_KERBEROS_MIT */
blocksize =
krb5_enctype_array[subkey->enctype]->system->block_length;
#endif /* NETSNMP_USE_KERBEROS_MIT */
#ifndef OLD_HEIMDAL
ivector.data = malloc(blocksize);
if (!ivector.data) {
DEBUGMSGTL(("ksm", "Unable to allocate %d bytes for ivector\n",
(int)blocksize));
retval = SNMPERR_MALLOC;
goto error;
}
ivector.length = blocksize;
memset(ivector.data, 0, blocksize);
#ifndef NETSNMP_USE_KERBEROS_MIT
krb5_use_enctype(kcontext, &eblock, subkey->enctype);
retcode = krb5_process_key(kcontext, &eblock, subkey);
if (retcode) {
DEBUGMSGTL(("ksm", "KSM key post-processing failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
#endif /* !NETSNMP_USE_KERBEROS_MIT */
#endif /* ! OLD_HEIMDAL */
if (length > *parms->scopedPduLen) {
DEBUGMSGTL(("ksm", "KSM not enough room - have %d bytes to "
"decrypt but only %d bytes available\n", (int)length,
(int)*parms->scopedPduLen));
retval = SNMPERR_TOO_LONG;
#ifndef NETSNMP_USE_KERBEROS_MIT
#ifndef OLD_HEIMDAL
krb5_finish_key(kcontext, &eblock);
#endif /* ! OLD_HEIMDAL */
#endif /* ! NETSNMP_USE_KERBEROS_MIT */
goto error;
}
#ifdef NETSNMP_USE_KERBEROS_MIT
in_crypt.ciphertext.data = (char *) current;
in_crypt.ciphertext.length = length;
in_crypt.enctype = subkey->enctype;
output.data = (char *) *parms->scopedPdu;
output.length = *parms->scopedPduLen;
retcode =
krb5_c_decrypt(kcontext, subkey, KSM_KEY_USAGE_ENCRYPTION,
&ivector, &in_crypt, &output);
#elif defined (OLD_HEIMDAL) /* NETSNMP_USE_KERBEROS_MIT */
retcode = krb5_decrypt(kcontext, heim_crypto, KSM_KEY_USAGE_ENCRYPTION,
current, length, &output);
if (retcode == 0) {
*parms->scopedPdu = (char *) output.data;
*parms->scopedPduLen = output.length;
krb5_data_zero(&output);
}
#else /* NETSNMP_USE_KERBEROS_MIT */
retcode = krb5_decrypt(kcontext, (krb5_pointer) current,
*parms->scopedPdu, length, &eblock,
ivector.data);
krb5_finish_key(kcontext, &eblock);
#endif /* NETSNMP_USE_KERBEROS_MIT */
if (retcode) {
DEBUGMSGTL(("ksm", "Decryption failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
*parms->scopedPduLen = length;
} else {
/*
* Clear PDU
*/
*parms->scopedPdu = current;
*parms->scopedPduLen =
parms->wholeMsgLen - (current - parms->wholeMsg);
}
/*
* A HUGE GROSS HACK
*/
*parms->maxSizeResponse = parms->maxMsgSize - 200;
DEBUGMSGTL(("ksm", "KSM processing complete\n"));
/*
* Set the secName to the right value (a hack for now). But that's
* only used for when we're processing a request, not a response.
*/
if (!response) {
retcode = krb5_unparse_name(kcontext, TICKET_CLIENT(ticket),
&cname);
if (retcode) {
DEBUGMSGTL(("ksm", "KSM krb5_unparse_name failed: %s\n",
error_message(retcode)));
snmp_set_detail(error_message(retcode));
retval = SNMPERR_KRB5;
goto error;
}
if (strlen(cname) > *parms->secNameLen + 1) {
DEBUGMSGTL(("ksm",
"KSM: Principal length (%d) is too long (%d)\n",
(int)strlen(cname), (int)*parms->secNameLen));
retval = SNMPERR_TOO_LONG;
free(cname);
goto error;
}
strcpy(parms->secName, cname);
*parms->secNameLen = strlen(cname);
free(cname);
/*
* Also, if we're not a response, keep around our auth_context so we
* can encode the reply message correctly
*/
ksm_state = SNMP_MALLOC_STRUCT(ksm_secStateRef);
if (!ksm_state) {
DEBUGMSGTL(("ksm", "KSM unable to malloc memory for "
"ksm_secStateRef\n"));
retval = SNMPERR_MALLOC;
goto error;
}
ksm_state->auth_context = auth_context;
auth_context = NULL;
ksm_state->cksumtype = cksumtype;
*parms->secStateRef = ksm_state;
} else {
/*
* We _still_ have to set the secName in process_in_msg(). Do
* that now with what we were passed in before (we cached it,
* remember?)
*/
memcpy(parms->secName, entry->secName, entry->secNameLen);
*parms->secNameLen = entry->secNameLen;
}
/*
* Just in case
*/
parms->secEngineID = null_id;
*parms->secEngineIDLen = 0;
auth_context = NULL; /* So we don't try to free it on success */
error:
if (retval == SNMPERR_ASN_PARSE_ERR &&
snmp_increment_statistic(STAT_SNMPINASNPARSEERRS) == 0)
DEBUGMSGTL(("ksm", "Failed to increment statistics.\n"));
if (subkey)
krb5_free_keyblock(kcontext, subkey);
#ifdef OLD_HEIMDAL /* OLD_HEIMDAL */
if (heim_crypto)
krb5_crypto_destroy(kcontext, heim_crypto);
#endif /* OLD_HEIMDAL */
if (CHECKSUM_CONTENTS(&checksum))
free(CHECKSUM_CONTENTS(&checksum));
if (ivector.data)
free(ivector.data);
if (ticket)
krb5_free_ticket(kcontext, ticket);
if (!response && auth_context)
krb5_auth_con_free(kcontext, auth_context);
if (ap_req.data)
free(ap_req.data);
return retval;
}