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osmo-msc/openbsc/src/gprs/gprs_llc.c

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/* GPRS LLC protocol implementation as per 3GPP TS 04.64 */
/* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <errno.h>
#include <stdint.h>
#include <stdbool.h>
#include <openssl/rand.h>
#include <osmocom/core/msgb.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/rate_ctr.h>
#include <osmocom/gprs/gprs_bssgp.h>
#include <openbsc/gsm_data.h>
#include <openbsc/debug.h>
#include <openbsc/gprs_sgsn.h>
#include <openbsc/gprs_gmm.h>
#include <openbsc/gprs_llc.h>
#include <openbsc/crc24.h>
#include <openbsc/sgsn.h>
#include <openbsc/gprs_llc_xid.h>
#include <openbsc/gprs_sndcp.h>
static struct gprs_llc_llme *llme_alloc(uint32_t tlli);
static int gprs_llc_tx_xid(struct gprs_llc_lle *lle, struct msgb *msg,
int command);
static int gprs_llc_tx_u(struct msgb *msg, uint8_t sapi,
int command, enum gprs_llc_u_cmd u_cmd, int pf_bit);
/* BEGIN XID RELATED */
/* Generate XID message */
static int gprs_llc_generate_xid(uint8_t *bytes, int bytes_len,
struct gprs_llc_xid_field *l3_xid_field,
struct gprs_llc_llme *llme)
{
/* Note: Called by gprs_ll_xid_req() */
LLIST_HEAD(xid_fields);
struct gprs_llc_xid_field xid_version;
struct gprs_llc_xid_field xid_n201u;
struct gprs_llc_xid_field xid_n201i;
xid_version.type = GPRS_LLC_XID_T_VERSION;
xid_version.data = (uint8_t *) "\x00";
xid_version.data_len = 1;
xid_n201u.type = GPRS_LLC_XID_T_N201_U;
xid_n201u.data = (uint8_t *) "\x05\xf0";
xid_n201u.data_len = 2;
xid_n201i.type = GPRS_LLC_XID_T_N201_I;
xid_n201i.data = (uint8_t *) "\x05\xf0";
xid_n201i.data_len = 2;
/* Add locally managed XID Fields */
llist_add(&xid_n201i.list, &xid_fields);
llist_add(&xid_n201u.list, &xid_fields);
llist_add(&xid_version.list, &xid_fields);
/* Append layer 3 XID field (if present) */
if (l3_xid_field) {
/* Enforce layer 3 XID type (just to be sure) */
l3_xid_field->type = GPRS_LLC_XID_T_L3_PAR;
/* Add Layer 3 XID field to the list */
llist_add(&l3_xid_field->list, &xid_fields);
}
/* Store generated XID for later reference */
talloc_free(llme->xid);
llme->xid = gprs_llc_copy_xid(llme, &xid_fields);
return gprs_llc_compile_xid(bytes, bytes_len, &xid_fields);
}
/* Generate XID message that will cause the GMM to reset */
static int gprs_llc_generate_xid_for_gmm_reset(uint8_t *bytes,
int bytes_len, uint32_t iov_ui,
struct gprs_llc_llme *llme)
{
/* Called by gprs_llgmm_reset() and
* gprs_llgmm_reset_oldmsg() */
LLIST_HEAD(xid_fields);
struct gprs_llc_xid_field xid_reset;
struct gprs_llc_xid_field xid_iovui;
/* First XID component must be RESET */
xid_reset.type = GPRS_LLC_XID_T_RESET;
xid_reset.data = NULL;
xid_reset.data_len = 0;
/* Add new IOV-UI */
xid_iovui.type = GPRS_LLC_XID_T_IOV_UI;
xid_iovui.data = (uint8_t *) & iov_ui;
xid_iovui.data_len = 4;
/* Add locally managed XID Fields */
llist_add(&xid_iovui.list, &xid_fields);
llist_add(&xid_reset.list, &xid_fields);
/* Store generated XID for later reference */
talloc_free(llme->xid);
llme->xid = gprs_llc_copy_xid(llme, &xid_fields);
return gprs_llc_compile_xid(bytes, bytes_len, &xid_fields);
}
/* Process an incoming XID confirmation */
static int gprs_llc_process_xid_conf(uint8_t *bytes, int bytes_len,
struct gprs_llc_lle *lle)
{
/* Note: This function handles the response of a network originated
* XID-Request. There XID messages reflected by the phone are analyzed
* and processed here. The caller is called by rx_llc_xid(). */
struct llist_head *xid_fields;
struct gprs_llc_xid_field *xid_field;
/* Parse and analyze XID-Response */
xid_fields = gprs_llc_parse_xid(NULL, bytes, bytes_len);
if (xid_fields) {
gprs_llc_dump_xid_fields(xid_fields, LOGL_DEBUG);
llist_for_each_entry(xid_field, xid_fields, list) {
/* Forward SNDCP-XID fields to Layer 3 (SNDCP) */
if (xid_field->type == GPRS_LLC_XID_T_L3_PAR) {
LOGP(DLLC, LOGL_NOTICE,
"Ignoring SNDCP-XID-Field: XID: type=%i, data_len=%i, data=%s\n",
xid_field->type, xid_field->data_len,
osmo_hexdump_nospc(xid_field->data,
xid_field->data_len));
}
/* Process LLC-XID fields: */
else {
/* FIXME: Do something more useful with the
* echoed XID-Information. Currently we
* just ignore the response completely and
* by doing so we blindly accept any changes
* the MS might have done to the our XID
* inquiry. There is a remainig risk of
* malfunction! */
LOGP(DLLC, LOGL_NOTICE,
"Ignoring XID-Field: XID: type=%d, data_len=%d, data=%s\n",
xid_field->type, xid_field->data_len,
osmo_hexdump_nospc(xid_field->data,
xid_field->data_len));
}
}
talloc_free(xid_fields);
}
/* Flush pending XID fields */
talloc_free(lle->llme->xid);
lle->llme->xid = NULL;
return 0;
}
/* Process an incoming XID indication and generate an appropiate response */
static int gprs_llc_process_xid_ind(uint8_t *bytes_request,
int bytes_request_len,
uint8_t *bytes_response,
int bytes_response_maxlen,
struct gprs_llc_lle *lle)
{
/* Note: This function computes the response that is sent back to the
* phone when a phone originated XID is received. The function is
* called by rx_llc_xid() */
int rc = -EINVAL;
struct llist_head *xid_fields;
struct llist_head *xid_fields_response;
struct gprs_llc_xid_field *xid_field;
struct gprs_llc_xid_field *xid_field_response;
/* Flush eventually pending XID fields */
talloc_free(lle->llme->xid);
lle->llme->xid = NULL;
/* Parse and analyze XID-Request */
xid_fields =
gprs_llc_parse_xid(lle->llme, bytes_request, bytes_request_len);
if (xid_fields) {
xid_fields_response = talloc_zero(lle->llme, struct llist_head);
INIT_LLIST_HEAD(xid_fields_response);
gprs_llc_dump_xid_fields(xid_fields, LOGL_DEBUG);
/* Process LLC-XID fields: */
llist_for_each_entry(xid_field, xid_fields, list) {
if (xid_field->type != GPRS_LLC_XID_T_L3_PAR) {
/* FIXME: Check the incoming XID parameters for
* for validity. Currently we just blindly
* accept all XID fields by just echoing them.
* There is a remaining risk of malfunction
* when a phone submits values which defer from
* the default! */
LOGP(DLLC, LOGL_NOTICE,
"Echoing XID-Field: XID: type=%d, data_len=%d, data=%s\n",
xid_field->type, xid_field->data_len,
osmo_hexdump_nospc(xid_field->data,
xid_field->data_len));
xid_field_response =
gprs_llc_dup_xid_field
(lle->llme, xid_field);
llist_add(&xid_field_response->list,
xid_fields_response);
}
}
rc = gprs_llc_compile_xid(bytes_response,
bytes_response_maxlen,
xid_fields_response);
talloc_free(xid_fields_response);
talloc_free(xid_fields);
}
return rc;
}
/* Dispatch XID indications and responses comming from the Phone */
static void rx_llc_xid(struct gprs_llc_lle *lle,
struct gprs_llc_hdr_parsed *gph)
{
uint8_t response[1024];
int response_len;
/* FIXME: 8.5.3.3: check if XID is invalid */
if (gph->is_cmd) {
LOGP(DLLC, LOGL_NOTICE,
"Received XID indication from phone.\n");
struct msgb *resp;
uint8_t *xid;
resp = msgb_alloc_headroom(4096, 1024, "LLC_XID");
response_len =
gprs_llc_process_xid_ind(gph->data, gph->data_len,
response, sizeof(response),
lle);
xid = msgb_put(resp, response_len);
memcpy(xid, response, response_len);
gprs_llc_tx_xid(lle, resp, 0);
} else {
LOGP(DLLC, LOGL_NOTICE,
"Received XID confirmation from phone.\n");
gprs_llc_process_xid_conf(gph->data, gph->data_len, lle);
/* FIXME: if we had sent a XID reset, send
* LLGMM-RESET.conf to GMM */
}
}
/* Set of LL-XID negotiation (See also: TS 101 351, Section 7.2.2.4) */
int gprs_ll_xid_req(struct gprs_llc_lle *lle,
struct gprs_llc_xid_field *l3_xid_field)
{
/* Note: This functions is calle from gprs_sndcp.c */
uint8_t xid_bytes[1024];;
int xid_bytes_len;
uint8_t *xid;
struct msgb *msg;
/* Generate XID */
xid_bytes_len =
gprs_llc_generate_xid(xid_bytes, sizeof(xid_bytes),
l3_xid_field, lle->llme);
/* Only perform XID sending if the XID message contains something */
if (xid_bytes_len > 0) {
/* Transmit XID bytes */
msg = msgb_alloc_headroom(4096, 1024, "LLC_XID");
xid = msgb_put(msg, xid_bytes_len);
memcpy(xid, xid_bytes, xid_bytes_len);
LOGP(DLLC, LOGL_NOTICE, "Sending XID request to phone...\n");
gprs_llc_tx_xid(lle, msg, 1);
} else {
LOGP(DLLC, LOGL_ERROR,
"XID-Message generation failed, XID not sent!\n");
return -EINVAL;
}
return 0;
}
/* END XID RELATED */
/* Entry function from upper level (LLC), asking us to transmit a BSSGP PDU
* to a remote MS (identified by TLLI) at a BTS identified by its BVCI and NSEI */
static int _bssgp_tx_dl_ud(struct msgb *msg, struct sgsn_mm_ctx *mmctx)
{
struct bssgp_dl_ud_par dup;
const uint8_t qos_profile_default[3] = { 0x00, 0x00, 0x20 };
memset(&dup, 0, sizeof(dup));
/* before we have received some identity from the MS, we might
* not yet have a MMC context (e.g. XID negotiation of primarly
* LLC connection from GMM sapi). */
if (mmctx) {
dup.imsi = mmctx->imsi;
dup.drx_parms = mmctx->drx_parms;
dup.ms_ra_cap.len = mmctx->ms_radio_access_capa.len;
dup.ms_ra_cap.v = mmctx->ms_radio_access_capa.buf;
/* make sure we only send it to the right llme */
OSMO_ASSERT(msgb_tlli(msg) == mmctx->gb.llme->tlli
|| msgb_tlli(msg) == mmctx->gb.llme->old_tlli);
}
memcpy(&dup.qos_profile, qos_profile_default,
sizeof(qos_profile_default));
return bssgp_tx_dl_ud(msg, 1000, &dup);
}
/* Section 8.9.9 LLC layer parameter default values */
static const struct gprs_llc_params llc_default_params[NUM_SAPIS] = {
[1] = {
.t200_201 = 5,
.n200 = 3,
.n201_u = 400,
},
[2] = {
.t200_201 = 5,
.n200 = 3,
.n201_u = 270,
},
[3] = {
.iov_i_exp = 27,
.t200_201 = 5,
.n200 = 3,
.n201_u = 500,
.n201_i = 1503,
.mD = 1520,
.mU = 1520,
.kD = 16,
.kU = 16,
},
[5] = {
.iov_i_exp = 27,
.t200_201 = 10,
.n200 = 3,
.n201_u = 500,
.n201_i = 1503,
.mD = 760,
.mU = 760,
.kD = 8,
.kU = 8,
},
[7] = {
.t200_201 = 20,
.n200 = 3,
.n201_u = 270,
},
[8] = {
.t200_201 = 20,
.n200 = 3,
.n201_u = 270,
},
[9] = {
.iov_i_exp = 27,
.t200_201 = 20,
.n200 = 3,
.n201_u = 500,
.n201_i = 1503,
.mD = 380,
.mU = 380,
.kD = 4,
.kU = 4,
},
[11] = {
.iov_i_exp = 27,
.t200_201 = 40,
.n200 = 3,
.n201_u = 500,
.n201_i = 1503,
.mD = 190,
.mU = 190,
.kD = 2,
.kU = 2,
},
};
LLIST_HEAD(gprs_llc_llmes);
void *llc_tall_ctx;
/* lookup LLC Entity based on DLCI (TLLI+SAPI tuple) */
static struct gprs_llc_lle *lle_by_tlli_sapi(const uint32_t tlli, uint8_t sapi)
{
struct gprs_llc_llme *llme;
llist_for_each_entry(llme, &gprs_llc_llmes, list) {
if (llme->tlli == tlli || llme->old_tlli == tlli)
return &llme->lle[sapi];
}
return NULL;
}
struct gprs_llc_lle *gprs_lle_get_or_create(const uint32_t tlli, uint8_t sapi)
{
struct gprs_llc_llme *llme;
struct gprs_llc_lle *lle;
lle = lle_by_tlli_sapi(tlli, sapi);
if (lle)
return lle;
LOGP(DLLC, LOGL_NOTICE, "LLC: unknown TLLI 0x%08x, "
"creating LLME on the fly\n", tlli);
llme = llme_alloc(tlli);
lle = &llme->lle[sapi];
return lle;
}
struct llist_head *gprs_llme_list(void)
{
return &gprs_llc_llmes;
}
/* lookup LLC Entity for RX based on DLCI (TLLI+SAPI tuple) */
static struct gprs_llc_lle *lle_for_rx_by_tlli_sapi(const uint32_t tlli,
uint8_t sapi, enum gprs_llc_cmd cmd)
{
struct gprs_llc_lle *lle;
/* We already know about this TLLI */
lle = lle_by_tlli_sapi(tlli, sapi);
if (lle)
return lle;
/* Maybe it is a routing area update but we already know this sapi? */
if (gprs_tlli_type(tlli) == TLLI_FOREIGN) {
lle = lle_by_tlli_sapi(tlli, sapi);
if (lle) {
LOGP(DLLC, LOGL_NOTICE,
"LLC RX: Found a local entry for TLLI 0x%08x\n",
tlli);
return lle;
}
}
/* 7.2.1.1 LLC belonging to unassigned TLLI+SAPI shall be discarded,
* except UID and XID frames with SAPI=1 */
if (sapi == GPRS_SAPI_GMM &&
(cmd == GPRS_LLC_XID || cmd == GPRS_LLC_UI)) {
struct gprs_llc_llme *llme;
/* FIXME: don't use the TLLI but the 0xFFFF unassigned? */
llme = llme_alloc(tlli);
LOGP(DLLC, LOGL_NOTICE, "LLC RX: unknown TLLI 0x%08x, "
"creating LLME on the fly\n", tlli);
lle = &llme->lle[sapi];
return lle;
}
LOGP(DLLC, LOGL_NOTICE,
"unknown TLLI(0x%08x)/SAPI(%d): Silently dropping\n",
tlli, sapi);
return NULL;
}
static void lle_init(struct gprs_llc_llme *llme, uint8_t sapi)
{
struct gprs_llc_lle *lle = &llme->lle[sapi];
lle->llme = llme;
lle->sapi = sapi;
lle->state = GPRS_LLES_UNASSIGNED;
/* Initialize according to parameters */
memcpy(&lle->params, &llc_default_params[sapi], sizeof(lle->params));
}
static struct gprs_llc_llme *llme_alloc(uint32_t tlli)
{
struct gprs_llc_llme *llme;
uint32_t i;
llme = talloc_zero(llc_tall_ctx, struct gprs_llc_llme);
if (!llme)
return NULL;
llme->tlli = tlli;
llme->old_tlli = 0xffffffff;
llme->state = GPRS_LLMS_UNASSIGNED;
llme->age_timestamp = GPRS_LLME_RESET_AGE;
llme->cksn = GSM_KEY_SEQ_INVAL;
for (i = 0; i < ARRAY_SIZE(llme->lle); i++)
lle_init(llme, i);
llist_add(&llme->list, &gprs_llc_llmes);
return llme;
}
static void llme_free(struct gprs_llc_llme *llme)
{
talloc_free(llme->xid);
llist_del(&llme->list);
talloc_free(llme);
}
#if 0
/* FIXME: Unused code... */
static void t200_expired(void *data)
{
struct gprs_llc_lle *lle = data;
/* 8.5.1.3: Expiry of T200 */
if (lle->retrans_ctr >= lle->params.n200) {
/* FIXME: LLGM-STATUS-IND, LL-RELEASE-IND/CNF */
lle->state = GPRS_LLES_ASSIGNED_ADM;
}
switch (lle->state) {
case GPRS_LLES_LOCAL_EST:
/* FIXME: retransmit SABM */
/* FIXME: re-start T200 */
lle->retrans_ctr++;
break;
case GPRS_LLES_LOCAL_REL:
/* FIXME: retransmit DISC */
/* FIXME: re-start T200 */
lle->retrans_ctr++;
break;
default:
LOGP(DLLC, LOGL_ERROR, "LLC unhandled state: %d\n", lle->state);
break;
}
}
static void t201_expired(void *data)
{
struct gprs_llc_lle *lle = data;
if (lle->retrans_ctr < lle->params.n200) {
/* FIXME: transmit apropriate supervisory frame (8.6.4.1) */
/* FIXME: set timer T201 */
lle->retrans_ctr++;
}
}
#endif
int gprs_llc_tx_u(struct msgb *msg, uint8_t sapi, int command,
enum gprs_llc_u_cmd u_cmd, int pf_bit)
{
uint8_t *fcs, *llch;
uint8_t addr, ctrl;
uint32_t fcs_calc;
/* Identifiers from UP: (TLLI, SAPI) + (BVCI, NSEI) */
/* Address Field */
addr = sapi & 0xf;
if (command)
addr |= 0x40;
/* 6.3 Figure 8 */
ctrl = 0xe0 | u_cmd;
if (pf_bit)
ctrl |= 0x10;
/* prepend LLC UI header */
llch = msgb_push(msg, 2);
llch[0] = addr;
llch[1] = ctrl;
/* append FCS to end of frame */
fcs = msgb_put(msg, 3);
fcs_calc = gprs_llc_fcs(llch, fcs - llch);
fcs[0] = fcs_calc & 0xff;
fcs[1] = (fcs_calc >> 8) & 0xff;
fcs[2] = (fcs_calc >> 16) & 0xff;
/* Identifiers passed down: (BVCI, NSEI) */
rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_LLC_DL_PACKETS]);
rate_ctr_add(&sgsn->rate_ctrs->ctr[CTR_LLC_DL_BYTES], msg->len);
/* Send BSSGP-DL-UNITDATA.req */
return _bssgp_tx_dl_ud(msg, NULL);
}
/* Send XID response to LLE */
static int gprs_llc_tx_xid(struct gprs_llc_lle *lle, struct msgb *msg,
int command)
{
/* copy identifiers from LLE to ensure lower layers can route */
msgb_tlli(msg) = lle->llme->tlli;
msgb_bvci(msg) = lle->llme->bvci;
msgb_nsei(msg) = lle->llme->nsei;
return gprs_llc_tx_u(msg, lle->sapi, command, GPRS_LLC_U_XID, 1);
}
/* encrypt information field + FCS, if needed! */
static int apply_gea(struct gprs_llc_lle *lle, uint16_t crypt_len, uint16_t nu,
uint32_t oc, uint8_t sapi, uint8_t *fcs, uint8_t *data)
{
uint8_t cipher_out[GSM0464_CIPH_MAX_BLOCK];
if (lle->llme->algo == GPRS_ALGO_GEA0)
return -EINVAL;
/* Compute the 'Input' Paraemeter */
uint32_t fcs_calc, iv = gprs_cipher_gen_input_ui(lle->llme->iov_ui, sapi,
nu, oc);
/* Compute gamma that we need to XOR with the data */
int r = gprs_cipher_run(cipher_out, crypt_len, lle->llme->algo,
lle->llme->kc, iv,
fcs ? GPRS_CIPH_SGSN2MS : GPRS_CIPH_MS2SGSN);
if (r < 0) {
LOGP(DLLC, LOGL_ERROR, "Error producing %s gamma for UI "
"frame: %d\n", get_value_string(gprs_cipher_names,
lle->llme->algo), r);
return -ENOMSG;
}
if (fcs) {
/* Mark frame as encrypted and update FCS */
data[2] |= 0x02;
fcs_calc = gprs_llc_fcs(data, fcs - data);
fcs[0] = fcs_calc & 0xff;
fcs[1] = (fcs_calc >> 8) & 0xff;
fcs[2] = (fcs_calc >> 16) & 0xff;
data += 3;
}
/* XOR the cipher output with the data */
for (r = 0; r < crypt_len; r++)
*(data + r) ^= cipher_out[r];
return 0;
}
/* Transmit a UI frame over the given SAPI:
'encryptable' indicates whether particular message can be encrypted according
to 3GPP TS 24.008 § 4.7.1.2
*/
int gprs_llc_tx_ui(struct msgb *msg, uint8_t sapi, int command,
struct sgsn_mm_ctx *mmctx, bool encryptable)
{
struct gprs_llc_lle *lle;
uint8_t *fcs, *llch;
uint8_t addr, ctrl[2];
uint32_t fcs_calc;
uint16_t nu = 0;
uint32_t oc;
/* Identifiers from UP: (TLLI, SAPI) + (BVCI, NSEI) */
/* look-up or create the LL Entity for this (TLLI, SAPI) tuple */
lle = gprs_lle_get_or_create(msgb_tlli(msg), sapi);
if (msg->len > lle->params.n201_u) {
LOGP(DLLC, LOGL_ERROR, "Cannot Tx %u bytes (N201-U=%u)\n",
msg->len, lle->params.n201_u);
msgb_free(msg);
return -EFBIG;
}
gprs_llme_copy_key(mmctx, lle->llme);
/* Update LLE's (BVCI, NSEI) tuple */
lle->llme->bvci = msgb_bvci(msg);
lle->llme->nsei = msgb_nsei(msg);
/* Obtain current values for N(u) and OC */
nu = lle->vu_send;
oc = lle->oc_ui_send;
/* Increment V(U) */
lle->vu_send = (lle->vu_send + 1) % 512;
/* Increment Overflow Counter, if needed */
if ((lle->vu_send + 1) / 512)
lle->oc_ui_send += 512;
/* Address Field */
addr = sapi & 0xf;
if (command)
addr |= 0x40;
/* Control Field */
ctrl[0] = 0xc0;
ctrl[0] |= nu >> 6;
ctrl[1] = (nu << 2) & 0xfc;
ctrl[1] |= 0x01; /* Protected Mode */
/* prepend LLC UI header */
llch = msgb_push(msg, 3);
llch[0] = addr;
llch[1] = ctrl[0];
llch[2] = ctrl[1];
/* append FCS to end of frame */
fcs = msgb_put(msg, 3);
fcs_calc = gprs_llc_fcs(llch, fcs - llch);
fcs[0] = fcs_calc & 0xff;
fcs[1] = (fcs_calc >> 8) & 0xff;
fcs[2] = (fcs_calc >> 16) & 0xff;
if (lle->llme->algo != GPRS_ALGO_GEA0 && encryptable) {
int rc = apply_gea(lle, fcs - llch, nu, oc, sapi, fcs, llch);
if (rc < 0) {
msgb_free(msg);
return rc;
}
}
/* Identifiers passed down: (BVCI, NSEI) */
/* Send BSSGP-DL-UNITDATA.req */
return _bssgp_tx_dl_ud(msg, mmctx);
}
static int gprs_llc_hdr_rx(struct gprs_llc_hdr_parsed *gph,
struct gprs_llc_lle *lle)
{
switch (gph->cmd) {
case GPRS_LLC_SABM: /* Section 6.4.1.1 */
lle->v_sent = lle->v_ack = lle->v_recv = 0;
if (lle->state == GPRS_LLES_ASSIGNED_ADM) {
/* start re-establishment (8.7.1) */
}
lle->state = GPRS_LLES_REMOTE_EST;
/* FIXME: Send UA */
lle->state = GPRS_LLES_ABM;
/* FIXME: process data */
break;
case GPRS_LLC_DISC: /* Section 6.4.1.2 */
/* FIXME: Send UA */
/* terminate ABM */
lle->state = GPRS_LLES_ASSIGNED_ADM;
break;
case GPRS_LLC_UA: /* Section 6.4.1.3 */
if (lle->state == GPRS_LLES_LOCAL_EST)
lle->state = GPRS_LLES_ABM;
break;
case GPRS_LLC_DM: /* Section 6.4.1.4: ABM cannot be performed */
if (lle->state == GPRS_LLES_LOCAL_EST)
lle->state = GPRS_LLES_ASSIGNED_ADM;
break;
case GPRS_LLC_FRMR: /* Section 6.4.1.5 */
break;
case GPRS_LLC_XID: /* Section 6.4.1.6 */
rx_llc_xid(lle, gph);
break;
case GPRS_LLC_UI:
if (gprs_llc_is_retransmit(gph->seq_tx, lle->vu_recv)) {
LOGP(DLLC, LOGL_NOTICE,
"TLLI=%08x dropping UI, N(U=%d) not in window V(URV(UR:%d).\n",
lle->llme ? lle->llme->tlli : -1,
gph->seq_tx, lle->vu_recv);
/* HACK: non-standard recovery handling. If remote LLE
* is re-transmitting the same sequence number for
* three times, don't discard the frame but pass it on
* and 'learn' the new sequence number */
if (gph->seq_tx != lle->vu_recv_last) {
lle->vu_recv_last = gph->seq_tx;
lle->vu_recv_duplicates = 0;
} else {
lle->vu_recv_duplicates++;
if (lle->vu_recv_duplicates < 3)
return -EIO;
LOGP(DLLC, LOGL_NOTICE, "TLLI=%08x recovering "
"N(U=%d) after receiving %u duplicates\n",
lle->llme ? lle->llme->tlli : -1,
gph->seq_tx, lle->vu_recv_duplicates);
}
}
/* Increment the sequence number that we expect in the next frame */
lle->vu_recv = (gph->seq_tx + 1) % 512;
/* Increment Overflow Counter */
if ((gph->seq_tx + 1) / 512)
lle->oc_ui_recv += 512;
break;
default:
LOGP(DLLC, LOGL_NOTICE, "Unhandled command: %d\n", gph->cmd);
break;
}
return 0;
}
/* receive an incoming LLC PDU (BSSGP-UL-UNITDATA-IND, 7.2.4.2) */
int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv)
{
struct gprs_llc_hdr *lh = (struct gprs_llc_hdr *) msgb_llch(msg);
struct gprs_llc_hdr_parsed llhp;
struct gprs_llc_lle *lle;
bool drop_cipherable = false;
int rc = 0;
/* Identifiers from DOWN: NSEI, BVCI, TLLI */
memset(&llhp, 0, sizeof(llhp));
rc = gprs_llc_hdr_parse(&llhp, (uint8_t *) lh, TLVP_LEN(tv, BSSGP_IE_LLC_PDU));
gprs_llc_hdr_dump(&llhp);
if (rc < 0) {
LOGP(DLLC, LOGL_NOTICE, "Error during LLC header parsing\n");
return rc;
}
switch (gprs_tlli_type(msgb_tlli(msg))) {
case TLLI_LOCAL:
case TLLI_FOREIGN:
case TLLI_RANDOM:
case TLLI_AUXILIARY:
break;
default:
LOGP(DLLC, LOGL_ERROR,
"Discarding frame with strange TLLI type\n");
break;
}
/* find the LLC Entity for this TLLI+SAPI tuple */
lle = lle_for_rx_by_tlli_sapi(msgb_tlli(msg), llhp.sapi, llhp.cmd);
if (!lle) {
switch (llhp.sapi) {
case GPRS_SAPI_SNDCP3:
case GPRS_SAPI_SNDCP5:
case GPRS_SAPI_SNDCP9:
case GPRS_SAPI_SNDCP11:
/* Ask an upper layer for help. */
return gsm0408_gprs_force_reattach_oldmsg(msg, NULL);
default:
break;
}
return 0;
}
/* reset age computation */
lle->llme->age_timestamp = GPRS_LLME_RESET_AGE;
/* decrypt information field + FCS, if needed! */
if (llhp.is_encrypted) {
if (lle->llme->algo != GPRS_ALGO_GEA0) {
rc = apply_gea(lle, llhp.data_len + 3, llhp.seq_tx,
lle->oc_ui_recv, lle->sapi, NULL,
llhp.data);
if (rc < 0)
return rc;
llhp.fcs = *(llhp.data + llhp.data_len);
llhp.fcs |= *(llhp.data + llhp.data_len + 1) << 8;
llhp.fcs |= *(llhp.data + llhp.data_len + 2) << 16;
} else {
LOGP(DLLC, LOGL_NOTICE, "encrypted frame for LLC that "
"has no KC/Algo! Dropping.\n");
return 0;
}
} else {
if (lle->llme->algo != GPRS_ALGO_GEA0 &&
lle->llme->cksn != GSM_KEY_SEQ_INVAL)
drop_cipherable = true;
}
/* We have to do the FCS check _after_ decryption */
llhp.fcs_calc = gprs_llc_fcs((uint8_t *)lh, llhp.crc_length);
if (llhp.fcs != llhp.fcs_calc) {
LOGP(DLLC, LOGL_INFO, "Dropping frame with invalid FCS\n");
return -EIO;
}
/* Update LLE's (BVCI, NSEI) tuple */
lle->llme->bvci = msgb_bvci(msg);
lle->llme->nsei = msgb_nsei(msg);
/* Receive and Process the actual LLC frame */
rc = gprs_llc_hdr_rx(&llhp, lle);
if (rc < 0)
return rc;
rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_LLC_UL_PACKETS]);
rate_ctr_add(&sgsn->rate_ctrs->ctr[CTR_LLC_UL_BYTES], msg->len);
/* llhp.data is only set when we need to send LL_[UNIT]DATA_IND up */
if (llhp.cmd == GPRS_LLC_UI && llhp.data && llhp.data_len) {
msgb_gmmh(msg) = llhp.data;
switch (llhp.sapi) {
case GPRS_SAPI_GMM:
/* send LL_UNITDATA_IND to GMM */
rc = gsm0408_gprs_rcvmsg_gb(msg, lle->llme,
drop_cipherable);
break;
case GPRS_SAPI_SNDCP3:
case GPRS_SAPI_SNDCP5:
case GPRS_SAPI_SNDCP9:
case GPRS_SAPI_SNDCP11:
/* send LL_DATA_IND/LL_UNITDATA_IND to SNDCP */
rc = sndcp_llunitdata_ind(msg, lle, llhp.data, llhp.data_len);
break;
case GPRS_SAPI_SMS:
/* FIXME */
case GPRS_SAPI_TOM2:
case GPRS_SAPI_TOM8:
/* FIXME: send LL_DATA_IND/LL_UNITDATA_IND to TOM */
default:
LOGP(DLLC, LOGL_NOTICE, "Unsupported SAPI %u\n", llhp.sapi);
rc = -EINVAL;
break;
}
}
return rc;
}
/* Propagate crypto parameters MM -> LLME */
void gprs_llme_copy_key(struct sgsn_mm_ctx *mm, struct gprs_llc_llme *llme)
{
if (!mm)
return;
if (mm->ciph_algo != GPRS_ALGO_GEA0) {
llme->algo = mm->ciph_algo;
if (llme->cksn != mm->auth_triplet.key_seq &&
mm->auth_triplet.key_seq != GSM_KEY_SEQ_INVAL) {
memcpy(llme->kc, mm->auth_triplet.vec.kc,
gprs_cipher_key_length(mm->ciph_algo));
llme->cksn = mm->auth_triplet.key_seq;
}
} else
llme->cksn = GSM_KEY_SEQ_INVAL;
}
/* 04.64 Chapter 7.2.1.1 LLGMM-ASSIGN */
int gprs_llgmm_assign(struct gprs_llc_llme *llme,
uint32_t old_tlli, uint32_t new_tlli)
{
unsigned int i;
if (old_tlli == 0xffffffff && new_tlli != 0xffffffff) {
/* TLLI Assignment 8.3.1 */
/* New TLLI shall be assigned and used when (re)transmitting LLC frames */
/* If old TLLI != 0xffffffff was assigned to LLME, then TLLI
* old is unassigned. Only TLLI new shall be accepted when
* received from peer. */
if (llme->old_tlli != 0xffffffff) {
llme->old_tlli = 0xffffffff;
llme->tlli = new_tlli;
} else {
/* If TLLI old == 0xffffffff was assigned to LLME, then this is
* TLLI assignmemt according to 8.3.1 */
llme->old_tlli = 0xffffffff;
llme->tlli = new_tlli;
llme->state = GPRS_LLMS_ASSIGNED;
/* 8.5.3.1 For all LLE's */
for (i = 0; i < ARRAY_SIZE(llme->lle); i++) {
struct gprs_llc_lle *l = &llme->lle[i];
l->vu_send = l->vu_recv = 0;
l->retrans_ctr = 0;
l->state = GPRS_LLES_ASSIGNED_ADM;
/* FIXME Set parameters according to table 9 */
}
}
} else if (old_tlli != 0xffffffff && new_tlli != 0xffffffff) {
/* TLLI Change 8.3.2 */
/* Both TLLI Old and TLLI New are assigned; use New when
* (re)transmitting. Accept both Old and New on Rx */
llme->old_tlli = old_tlli;
llme->tlli = new_tlli;
llme->state = GPRS_LLMS_ASSIGNED;
} else if (old_tlli != 0xffffffff && new_tlli == 0xffffffff) {
/* TLLI Unassignment 8.3.3) */
llme->tlli = llme->old_tlli = 0;
llme->state = GPRS_LLMS_UNASSIGNED;
for (i = 0; i < ARRAY_SIZE(llme->lle); i++) {
struct gprs_llc_lle *l = &llme->lle[i];
l->state = GPRS_LLES_UNASSIGNED;
}
llme_free(llme);
} else
return -EINVAL;
return 0;
}
/* TLLI unassignment */
int gprs_llgmm_unassign(struct gprs_llc_llme *llme)
{
return gprs_llgmm_assign(llme, llme->tlli, 0xffffffff);
}
/* Chapter 7.2.1.2 LLGMM-RESET.req */
int gprs_llgmm_reset(struct gprs_llc_llme *llme)
{
struct msgb *msg = msgb_alloc_headroom(4096, 1024, "LLC_XID");
struct gprs_llc_lle *lle = &llme->lle[1];
uint8_t xid_bytes[1024];
int xid_bytes_len;
uint8_t *xid;
LOGP(DLLC, LOGL_NOTICE, "LLGM Reset\n");
if (RAND_bytes((uint8_t *) &llme->iov_ui, 4) != 1) {
LOGP(DLLC, LOGL_NOTICE, "RAND_bytes failed for LLC XID reset, "
"falling back to rand()\n");
llme->iov_ui = rand();
}
/* Generate XID message */
xid_bytes_len = gprs_llc_generate_xid_for_gmm_reset(xid_bytes,
sizeof(xid_bytes),llme->iov_ui,llme);
if(xid_bytes_len < 0)
return -EINVAL;
xid = msgb_put(msg, xid_bytes_len);
memcpy(xid, xid_bytes, xid_bytes_len);
/* Reset some of the LLC parameters. See GSM 04.64, 8.5.3.1 */
lle->vu_recv = 0;
lle->vu_send = 0;
lle->oc_ui_send = 0;
lle->oc_ui_recv = 0;
/* FIXME: Start T200, wait for XID response */
return gprs_llc_tx_xid(lle, msg, 1);
}
int gprs_llgmm_reset_oldmsg(struct msgb* oldmsg, uint8_t sapi,
struct gprs_llc_llme *llme)
{
struct msgb *msg = msgb_alloc_headroom(4096, 1024, "LLC_XID");
uint8_t xid_bytes[1024];
int xid_bytes_len;
uint8_t *xid;
LOGP(DLLC, LOGL_NOTICE, "LLGM Reset\n");
if (RAND_bytes((uint8_t *) &llme->iov_ui, 4) != 1) {
LOGP(DLLC, LOGL_NOTICE, "RAND_bytes failed for LLC XID reset, "
"falling back to rand()\n");
llme->iov_ui = rand();
}
/* Generate XID message */
xid_bytes_len = gprs_llc_generate_xid_for_gmm_reset(xid_bytes,
sizeof(xid_bytes),llme->iov_ui,llme);
if(xid_bytes_len < 0)
return -EINVAL;
xid = msgb_put(msg, xid_bytes_len);
memcpy(xid, xid_bytes, xid_bytes_len);
/* FIXME: Start T200, wait for XID response */
msgb_tlli(msg) = msgb_tlli(oldmsg);
msgb_bvci(msg) = msgb_bvci(oldmsg);
msgb_nsei(msg) = msgb_nsei(oldmsg);
return gprs_llc_tx_u(msg, sapi, 1, GPRS_LLC_U_XID, 1);
}
int gprs_llc_init(const char *cipher_plugin_path)
{
return gprs_cipher_load(cipher_plugin_path);
}
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