/** Builds attribute representing OID string and adds 'index' attributes where required
*
* Will convert an OID string in the format @verbatim .1.2.3.4.5.0 @endverbatim
* into a pair with a #fr_dict_attr_t of the dictionary attribute matching the OID
* string, as evaluated from the specified parent.
*
* If an OID component does not match a child of a previous OID component, but a child
* with attribute number 0 exists, and a child with attribute number 1 also exists,
* the child with attribute number 0 will be used as an 'index' pair, and will be
* created with the value of the non matching OID component.
*
* Parsing will then resume using the child with attribute number 1.
*
* This allows traversals of SNMP tables to be represented by the sequence of pairs
* and allows the full range of entry indexes which would not be possible if we represented
* table index numbers as TLV attributes.
*
* @param[in] ctx to allocate new pairs in.
* @param[in] conf radsnmp config.
* @param[in] cursor to add pairs to.
* @param[in] oid string to evaluate.
* @param[in] type SNMP value type.
* @param[in] value to assign to OID attribute (SET operations only).
* @return
* - >0 on success (how much of the OID string we parsed).
* - <=0 on failure (where format error occurred).
*/
static ssize_t radsnmp_pair_from_oid(TALLOC_CTX *ctx, radsnmp_conf_t *conf, fr_cursor_t *cursor,
char const *oid, int type, char const *value)
{
ssize_t slen;
char const *p = oid;
unsigned int attr;
fr_dict_attr_t const *index_attr, *da;
fr_dict_attr_t const *parent = conf->snmp_root;
VALUE_PAIR *vp;
int ret;
if (!oid) return 0;
fr_cursor_tail(cursor);
/*
* Trim first.
*/
if (p[0] == '.') p++;
/*
* Support for indexes. If we can't find an attribute
* matching a child at a given level in the OID tree,
* look for attribute 0 (type integer) at that level.
* We use this to represent the index instead.
*/
for (;;) {
unsigned int num = 0;
slen = fr_dict_attr_by_oid(conf->dict, &parent, &attr, p);
if (slen > 0) break;
p += -(slen);
if (fr_dict_oid_component(&num, &p) < 0) break; /* Just advances the pointer */
assert(attr == num);
p++;
/*
* Check for an index attribute
*/
index_attr = fr_dict_attr_child_by_num(parent, 0);
if (!index_attr) {
fr_strerror_printf("Unknown OID component: No index attribute at this level");
break;
}
if (index_attr->type != FR_TYPE_UINT32) {
fr_strerror_printf("Index is not a \"integer\"");
break;
}
/*
* By convention SNMP entries are at .1
*/
parent = fr_dict_attr_child_by_num(parent, 1);
if (!parent) {
fr_strerror_printf("Unknown OID component: No entry attribute at this level");
break;
}
/*
* Entry must be a TLV type
*/
if (parent->type != FR_TYPE_TLV) {
fr_strerror_printf("Entry is not \"tlv\"");
break;
}
/*
* We've skipped over the index attribute, and
* the index number should be available in attr.
*/
MEM(vp = fr_pair_afrom_da(ctx, index_attr));
vp->vp_uint32 = attr;
fr_cursor_append(cursor, vp);
}
/*
* We errored out processing the OID.
*/
if (slen <= 0) {
error:
fr_cursor_free_list(cursor);
return slen;
}
fr_strerror(); /* Clear pending errors */
/*
* SNMP requests the leaf under the OID with .0.
*/
if (attr != 0) {
da = fr_dict_attr_child_by_num(parent, attr);
if (!da) {
fr_strerror_printf("Unknown leaf attribute %i", attr);
return -(slen);
}
} else {
da = parent;
}
vp = fr_pair_afrom_da(ctx, da);
if (!vp) {
fr_strerror_printf("Failed allocating OID attribute");
return -(slen);
}
/*
* VALUE_PAIRs with no value need a 1 byte value buffer.
*/
if (!value) {
switch (da->type) {
/*
* We can blame the authors of RFC 6929 for
* this hack. Apparently the presence or absence
* of an attribute isn't considered a useful means
* of conveying information, so empty TLVs are
* disallowed.
*/
case FR_TYPE_TLV:
fr_pair_to_unknown(vp);
/* FALL-THROUGH */
case FR_TYPE_OCTETS:
fr_pair_value_memcpy(vp, (uint8_t const *)"\0", 1, true);
break;
case FR_TYPE_STRING:
fr_pair_value_bstrncpy(vp, "\0", 1);
break;
/*
* Fine to leave other values zeroed out.
*/
default:
break;
}
fr_cursor_append(cursor, vp);
return slen;
}
if (da->type == FR_TYPE_TLV) {
fr_strerror_printf("TLVs cannot hold values");
return -(slen);
}
ret = fr_pair_value_from_str(vp, value, strlen(value), '\0', true);
if (ret < 0) {
slen = -(slen);
goto error;
}
vp = fr_pair_afrom_da(ctx, attr_freeradius_snmp_type);
if (!vp) {
slen = -(slen);
goto error;
}
vp->vp_uint32 = type;
fr_cursor_append(cursor, vp);
return slen;
}
/*
* build a reply to be sent.
*/
static int eap_sim_compose(eap_session_t *eap_session, uint8_t const *hmac_extra, size_t hmac_extra_len)
{
eap_sim_session_t *eap_sim_session = talloc_get_type_abort(eap_session->opaque, eap_sim_session_t);
fr_cursor_t cursor;
fr_cursor_t to_encode;
VALUE_PAIR *head = NULL, *vp;
REQUEST *request = eap_session->request;
fr_sim_encode_ctx_t encoder_ctx = {
.root = fr_dict_root(dict_eap_sim),
.keys = &eap_sim_session->keys,
.iv = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.iv_included = false,
.hmac_md = EVP_sha1(),
.eap_packet = eap_session->this_round->request,
.hmac_extra = hmac_extra,
.hmac_extra_len = hmac_extra_len
};
ssize_t ret;
/* we will set the ID on requests, since we have to HMAC it */
eap_session->this_round->set_request_id = true;
fr_cursor_init(&cursor, &eap_session->request->reply->vps);
fr_cursor_init(&to_encode, &head);
while ((vp = fr_cursor_current(&cursor))) {
if (!fr_dict_parent_common(fr_dict_root(dict_eap_sim), vp->da, true)) {
fr_cursor_next(&cursor);
continue;
}
vp = fr_cursor_remove(&cursor);
/*
* Silently discard encrypted attributes until
* the peer should have k_encr. These can be
* added by policy, and seem to cause
* wpa_supplicant to fail if sent before the challenge.
*/
if (!eap_sim_session->allow_encrypted && fr_dict_parent_common(attr_eap_sim_encr_data, vp->da, true)) {
RWDEBUG("Silently discarding &reply:%s: Encrypted attributes not allowed in this round",
vp->da->name);
talloc_free(vp);
continue;
}
fr_cursor_append(&to_encode, vp);
}
RDEBUG2("Encoding EAP-SIM attributes");
log_request_pair_list(L_DBG_LVL_2, request, head, NULL);
eap_session->this_round->request->type.num = FR_EAP_SIM;
eap_session->this_round->request->id = eap_sim_session->sim_id++ & 0xff;
eap_session->this_round->set_request_id = true;
ret = fr_sim_encode(eap_session->request, head, &encoder_ctx);
fr_cursor_head(&to_encode);
fr_cursor_free_list(&to_encode);
if (ret < 0) {
RPEDEBUG("Failed encoding EAP-SIM data");
return -1;
}
return 0;
}
static int eap_sim_send_start(eap_session_t *eap_session)
{
REQUEST *request = eap_session->request;
VALUE_PAIR **vps, *vp;
uint16_t version;
eap_sim_session_t *eap_sim_session = talloc_get_type_abort(eap_session->opaque, eap_sim_session_t);
RADIUS_PACKET *packet;
rad_assert(eap_session->request != NULL);
rad_assert(eap_session->request->reply);
RDEBUG2("Sending SIM-State");
eap_session->this_round->request->code = FR_EAP_CODE_REQUEST;
eap_sim_session->allow_encrypted = false; /* In case this is after failed fast-resumption */
/* these are the outgoing attributes */
packet = eap_session->request->reply;
vps = &packet->vps;
rad_assert(vps != NULL);
/*
* Add appropriate TLVs for the EAP things we wish to send.
*/
vp = fr_pair_afrom_da(packet, attr_eap_sim_version_list);
vp->vp_uint16 = EAP_SIM_VERSION;
fr_pair_add(vps, vp);
/* record it in the ess */
version = htons(EAP_SIM_VERSION);
memcpy(eap_sim_session->keys.gsm.version_list, &version, sizeof(version));
eap_sim_session->keys.gsm.version_list_len = 2;
/*
* Select the right type of identity request attribute
*/
switch (eap_sim_session->id_req) {
case SIM_ANY_ID_REQ:
vp = fr_pair_afrom_da(packet, attr_eap_sim_any_id_req);
break;
case SIM_PERMANENT_ID_REQ:
vp = fr_pair_afrom_da(packet, attr_eap_sim_permanent_id_req);
break;
case SIM_FULLAUTH_ID_REQ:
vp = fr_pair_afrom_da(packet, attr_eap_sim_fullauth_id_req);
break;
default:
rad_assert(0);
}
vp->vp_bool = true;
fr_pair_replace(vps, vp);
/* the SUBTYPE, set to start. */
vp = fr_pair_afrom_da(packet, attr_eap_sim_subtype);
vp->vp_uint16 = EAP_SIM_START;
fr_pair_replace(vps, vp);
/*
* Encode the packet
*/
if (eap_sim_compose(eap_session, NULL, 0) < 0) {
fr_pair_list_free(&packet->vps);
return -1;
}
return 0;
}
/** Decode SIM/AKA/AKA' specific packet data
*
* @note data should point to the subtype field in the EAP packet.
*
* Extracts the SUBTYPE and adds it an attribute, then decodes any TLVs in the
* SIM/AKA/AKA' packet.
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Code | Identifier | Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Type | Subtype | Reserved |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* The first byte of the data pointer should be the subtype.
*
* @param[in] request the current request.
* @param[in] decoded where to write decoded attributes.
* @param[in] dict for looking up attributes.
* @param[in] data to convert to pairs.
* @param[in] data_len length of data to convert.
* @param[in] decoder_ctx holds the state of the decoder.
* @return
* - 0 on success.
* - -1 on failure.
*/
int fr_sim_decode(REQUEST *request, fr_cursor_t *decoded, fr_dict_t const *dict,
uint8_t const *data, size_t data_len, fr_sim_decode_ctx_t *decoder_ctx)
{
ssize_t rcode;
uint8_t const *p = data;
uint8_t const *end = p + data_len;
/*
* Move the cursor to the end, so we know if
* any additional attributes were added.
*/
fr_cursor_tail(decoded);
/*
* We need at least enough data for the subtype
* and reserved bytes.
*
* Note: Not all packets should contain attrs.
* When the client acknowledges an
* AKA-Notification from the server, the
* AKA-Notification is returns contains no
* attributes.
*/
if (data_len < 3) {
fr_strerror_printf("Packet data too small, expected at least 3 bytes got %zu bytes", data_len);
return -1;
}
p += 3;
/*
* Loop over all the attributes decoding
* them into the appropriate attributes
* in the SIM/AKA/AKA' dict.
*/
while (p < end) {
rcode = fr_sim_decode_pair(request->packet, decoded, dict, p, end - p, decoder_ctx);
if (rcode <= 0) {
RPEDEBUG("Failed decoding AT");
error:
fr_cursor_free_list(decoded); /* Free any attributes we added */
return -1;
}
p += rcode;
rad_assert(p <= end);
}
/*
* No point in doing packet_ctx until we known the rest
* of the data is OK!
*/
{
VALUE_PAIR *vp;
vp = fr_pair_afrom_child_num(request->packet, fr_dict_root(dict), FR_SIM_SUBTYPE);
if (!vp) {
fr_strerror_printf("Failed allocating subtype attribute");
goto error;
}
vp->vp_uint32 = data[0];
fr_cursor_append(decoded, vp);
}
return 0;
}
static int eap_aka_compose(eap_session_t *eap_session)
{
eap_aka_session_t *eap_aka_session = talloc_get_type_abort(eap_session->opaque, eap_aka_session_t);
fr_cursor_t cursor;
fr_cursor_t to_encode;
VALUE_PAIR *head = NULL, *vp;
REQUEST *request = eap_session->request;
ssize_t ret;
fr_sim_encode_ctx_t encoder_ctx = {
.root = fr_dict_root(dict_eap_aka),
.keys = &eap_aka_session->keys,
.iv = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
.iv_included = false,
.hmac_md = eap_aka_session->mac_md,
.eap_packet = eap_session->this_round->request,
.hmac_extra = NULL,
.hmac_extra_len = 0
};
fr_cursor_init(&cursor, &eap_session->request->reply->vps);
fr_cursor_init(&to_encode, &head);
while ((vp = fr_cursor_current(&cursor))) {
if (!fr_dict_parent_common(encoder_ctx.root, vp->da, true)) {
fr_cursor_next(&cursor);
continue;
}
vp = fr_cursor_remove(&cursor);
/*
* Silently discard encrypted attributes until
* the peer should have k_encr. These can be
* added by policy, and seem to cause
* wpa_supplicant to fail if sent before the challenge.
*/
if (!eap_aka_session->allow_encrypted && fr_dict_parent_common(attr_eap_aka_encr_data, vp->da, true)) {
RWDEBUG("Silently discarding &reply:%s: Encrypted attributes not allowed in this round",
vp->da->name);
talloc_free(vp);
continue;
}
fr_cursor_append(&to_encode, vp);
}
RDEBUG2("Encoding EAP-AKA attributes");
log_request_pair_list(L_DBG_LVL_2, request, head, NULL);
eap_session->this_round->request->type.num = eap_aka_session->type;
eap_session->this_round->request->id = eap_aka_session->aka_id++ & 0xff;
eap_session->this_round->set_request_id = true;
ret = fr_sim_encode(eap_session->request, head, &encoder_ctx);
fr_cursor_head(&to_encode);
fr_cursor_free_list(&to_encode);
if (ret < 0) {
RPEDEBUG("Failed encoding EAP-AKA data");
return -1;
}
return 0;
}
/** Send an EAP-AKA identity request to the supplicant
*
* There are three types of user identities that can be implemented
* - Permanent identities such as [email protected]
* Permanent identities can be identified by the leading zero followed by
* by 15 digits (the IMSI number).
* - Ephemeral identities (pseudonyms). These are identities assigned for
* identity privacy so the user can't be tracked. These can identities
* can either be generated as per the 3GPP 'Security aspects of non-3GPP accesses'
* document section 14, where a set of up to 16 encryption keys are used
* to reversibly encrypt the IMSI. Alternatively the pseudonym can be completely
* randomised and stored in a datastore.
* - A fast resumption ID which resolves to data used for fast resumption.
*
* In order to perform full authentication the original IMSI is required for
* forwarding to the HLR. In the case where we can't match/decrypt the pseudonym,
* or can't perform fast resumption, we need to request the full identity from
* the supplicant.
*
* @param[in] eap_session to continue.
* @return
* - 0 on success.
* - <0 on failure.
*/
static int eap_aka_send_identity_request(eap_session_t *eap_session)
{
REQUEST *request = eap_session->request;
eap_aka_session_t *eap_aka_session = talloc_get_type_abort(eap_session->opaque, eap_aka_session_t);
VALUE_PAIR *vp;
RADIUS_PACKET *packet;
fr_cursor_t cursor;
RDEBUG2("Sending AKA-Identity (%s)", fr_int2str(sim_id_request_table, eap_aka_session->id_req, "<INVALID>"));
eap_session->this_round->request->code = FR_EAP_CODE_REQUEST;
eap_aka_session->allow_encrypted = false; /* In case this is after failed fast-resumption */
packet = request->reply;
fr_cursor_init(&cursor, &packet->vps);
/*
* Set the subtype to identity request
*/
vp = fr_pair_afrom_da(packet, attr_eap_aka_subtype);
vp->vp_uint16 = FR_EAP_AKA_SUBTYPE_VALUE_AKA_IDENTITY;
fr_cursor_append(&cursor, vp);
/*
* Select the right type of identity request attribute
*/
switch (eap_aka_session->id_req) {
case SIM_ANY_ID_REQ:
vp = fr_pair_afrom_da(packet, attr_eap_aka_any_id_req);
break;
case SIM_PERMANENT_ID_REQ:
vp = fr_pair_afrom_da(packet, attr_eap_aka_permanent_id_req);
break;
case SIM_FULLAUTH_ID_REQ:
vp = fr_pair_afrom_da(packet, attr_eap_aka_fullauth_id_req);
break;
default:
rad_assert(0);
}
vp->vp_bool = true;
fr_cursor_append(&cursor, vp);
/*
* Encode the packet
*/
if (eap_aka_compose(eap_session) < 0) {
failure:
fr_pair_list_free(&packet->vps);
return -1;
}
/*
* Digest the packet contents, updating our checkcode.
*/
if (!eap_aka_session->checkcode_state &&
fr_sim_crypto_init_checkcode(eap_aka_session, &eap_aka_session->checkcode_state,
eap_aka_session->checkcode_md) < 0) {
RPEDEBUG("Failed initialising checkcode");
goto failure;
}
if (fr_sim_crypto_update_checkcode(eap_aka_session->checkcode_state, eap_session->this_round->request) < 0) {
RPEDEBUG("Failed updating checkcode");
goto failure;
}
return 0;
}
