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-rw-r--r--snmplib/snmpksm.c1884
1 files changed, 1884 insertions, 0 deletions
diff --git a/snmplib/snmpksm.c b/snmplib/snmpksm.c
new file mode 100644
index 0000000..06febe2
--- /dev/null
+++ b/snmplib/snmpksm.c
@@ -0,0 +1,1884 @@
+/*
+ * 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 */
+#endif /* NETSNMP_USE_KERBEROS_HEIMDAL */
+
+#ifdef NETSNMP_USE_KERBEROS_HEIMDAL
+#define oid heimdal_oid_renamed
+#endif /* NETSNMP_USE_KERBEROS_HEIMDAL */
+#include <krb5.h>
+#include <com_err.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) ((char *)((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 const char *service_name = NULL;
+
+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);
+
+#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 = "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", c));
+ }
+ 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);
+}
+
+void shutdown_ksm(void)
+{
+}
+
+/*
+ * 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;
+ int retval;
+
+ entry = SNMP_MALLOC_STRUCT(ksm_cache_entry);
+
+ if (!entry)
+ return SNMPERR_MALLOC;
+
+ entry->msgid = msgid;
+ entry->auth_context = auth_context;
+ entry->refcount = 1;
+
+ retval = memdup(&entry->secName, secName, secNameLen);
+
+ if (retval != SNMPERR_SUCCESS) {
+ free(entry);
+ return retval;
+ }
+
+ 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, *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;
+#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(params->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,
+ (char *) 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_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 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", 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",
+ 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_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 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",
+ CHECKSUM_LENGTH(&pdu_checksum), cksum_pointer - (*wholeMsg + 1)));
+
+ DEBUGMSGTL(("ksm", "KSM: Checksum:"));
+
+ for (i = 0; i < CHECKSUM_LENGTH(&pdu_checksum); i++)
+ DEBUGMSG(("ksm", " %02x",
+ (unsigned int) 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",
+ 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",
+ 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 = "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_getremotesubkey(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_getlocalsubkey(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",
+ 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", length,
+ *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",
+ strlen(cname), 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 = (u_char *) "";
+ *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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-29 10:53:55 +0000