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-rw-r--r--src/gprs/gprs_llc.c1132
1 files changed, 1132 insertions, 0 deletions
diff --git a/src/gprs/gprs_llc.c b/src/gprs/gprs_llc.c
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index 000000000..2be663f98
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+++ b/src/gprs/gprs_llc.c
@@ -0,0 +1,1132 @@
+/* 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/gsm_subscriber.h>
+#include <openbsc/gprs_llc_xid.h>
+#include <openbsc/gprs_sndcp_comp.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_version.list, &xid_fields);
+ llist_add(&xid_n201u.list, &xid_fields);
+ llist_add(&xid_n201i.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 MS 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;
+ struct gprs_llc_xid_field *xid_field_request;
+ struct gprs_llc_xid_field *xid_field_request_l3 = NULL;
+
+ /* Pick layer3 XID from the XID request we have sent last */
+ if (lle->llme->xid) {
+ llist_for_each_entry(xid_field_request, lle->llme->xid, list) {
+ if (xid_field_request->type == GPRS_LLC_XID_T_L3_PAR)
+ xid_field_request_l3 = xid_field_request;
+ }
+ }
+
+ /* 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 &&
+ xid_field_request_l3) {
+ sndcp_sn_xid_conf(xid_field,
+ xid_field_request_l3, lle);
+ }
+
+ /* 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 %s, data_len=%d, data=%s\n",
+ get_value_string(gprs_llc_xid_type_names,
+ 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
+ * MS when a mobile 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;
+
+ /* 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 MS submits values which defer from
+ * the default! */
+ LOGP(DLLC, LOGL_NOTICE,
+ "Echoing XID-Field: XID: type %s, data_len=%d, data=%s\n",
+ get_value_string(gprs_llc_xid_type_names,
+ 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);
+ }
+ }
+
+ /* Forward SNDCP-XID fields to Layer 3 (SNDCP) */
+ llist_for_each_entry(xid_field, xid_fields, list) {
+ if (xid_field->type == GPRS_LLC_XID_T_L3_PAR) {
+
+ xid_field_response =
+ talloc_zero(lle->llme,
+ struct gprs_llc_xid_field);
+ rc = sndcp_sn_xid_ind(xid_field,
+ xid_field_response, lle);
+ if (rc == 0)
+ llist_add(&xid_field_response->list,
+ xid_fields_response);
+ else
+ talloc_free(xid_field_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 MS */
+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 MS.\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);
+ if (response_len < 0) {
+ LOGP(DLLC, LOGL_ERROR,
+ "invalid XID indication received!\n");
+ } else {
+ 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 MS.\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;
+ const char *ftype;
+
+ /* 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);
+ if (l3_xid_field)
+ ftype = get_value_string(gprs_llc_xid_type_names,
+ l3_xid_field->type);
+ else
+ ftype = "NULL";
+ LOGP(DLLC, LOGL_NOTICE, "Sending XID type %s (%d bytes) request"
+ " to MS...\n", ftype, xid_bytes_len);
+ 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);
+
+ llme->comp.proto = gprs_sndcp_comp_alloc(llme);
+ llme->comp.data = gprs_sndcp_comp_alloc(llme);
+
+ return llme;
+}
+
+static void llme_free(struct gprs_llc_llme *llme)
+{
+ gprs_sndcp_comp_free(llme->comp.proto);
+ gprs_sndcp_comp_free(llme->comp.data);
+ 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 ยง 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;
+ }
+ }
+
+ rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_LLC_DL_PACKETS]);
+ rate_ctr_add(&sgsn->rate_ctrs->ctr[CTR_LLC_DL_BYTES], msg->len);
+
+ /* 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 = NULL;
+ 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));
+ 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;
+ }
+ gprs_llc_hdr_dump(&llhp, lle);
+ /* 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);
+}