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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 <osmocom/core/msgb.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/talloc.h>
#include <openbsc/gsm_data.h>
#include <openbsc/debug.h>
#include <openbsc/gprs_sgsn.h>
#include <openbsc/gprs_gmm.h>
#include <openbsc/gprs_bssgp.h>
#include <openbsc/gprs_llc.h>
#include <openbsc/crc24.h>
#include <openbsc/sgsn.h>
/* Section 8.9.9 LLC layer parameter default values */
static const struct gprs_llc_params llc_default_params[] = {
[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;
/* If the TLLI is foreign, return its local version */
static inline uint32_t tlli_foreign2local(uint32_t tlli)
{
uint32_t new_tlli;
if (gprs_tlli_type(tlli) == TLLI_FOREIGN) {
new_tlli = tlli | 0x40000000;
DEBUGP(DLLC, "TLLI 0x%08x is foreign, converting to "
"local TLLI 0x%08x\n", tlli, new_tlli);
} else
new_tlli = tlli;
return new_tlli;
}
/* lookup LLC Entity based on DLCI (TLLI+SAPI tuple) */
static struct gprs_llc_lle *lle_by_tlli_sapi(uint32_t tlli, uint8_t sapi)
{
struct gprs_llc_llme *llme;
tlli = tlli_foreign2local(tlli);
llist_for_each_entry(llme, &gprs_llc_llmes, list) {
if (llme->tlli == tlli || llme->old_tlli == tlli)
return &llme->lle[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;
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)
{
llist_del(&llme->list);
talloc_free(llme);
}
enum gprs_llc_cmd {
GPRS_LLC_NULL,
GPRS_LLC_RR,
GPRS_LLC_ACK,
GPRS_LLC_RNR,
GPRS_LLC_SACK,
GPRS_LLC_DM,
GPRS_LLC_DISC,
GPRS_LLC_UA,
GPRS_LLC_SABM,
GPRS_LLC_FRMR,
GPRS_LLC_XID,
GPRS_LLC_UI,
};
static const struct value_string llc_cmd_strs[] = {
{ GPRS_LLC_NULL, "NULL" },
{ GPRS_LLC_RR, "RR" },
{ GPRS_LLC_ACK, "ACK" },
{ GPRS_LLC_RNR, "RNR" },
{ GPRS_LLC_SACK, "SACK" },
{ GPRS_LLC_DM, "DM" },
{ GPRS_LLC_DISC, "DISC" },
{ GPRS_LLC_UA, "UA" },
{ GPRS_LLC_SABM, "SABM" },
{ GPRS_LLC_FRMR, "FRMR" },
{ GPRS_LLC_XID, "XID" },
{ GPRS_LLC_UI, "UI" },
{ 0, NULL }
};
struct gprs_llc_hdr_parsed {
uint8_t sapi;
uint8_t is_cmd:1,
ack_req:1,
is_encrypted:1;
uint32_t seq_rx;
uint32_t seq_tx;
uint32_t fcs;
uint32_t fcs_calc;
uint8_t *data;
uint16_t data_len;
uint16_t crc_length;
enum gprs_llc_cmd cmd;
};
#define LLC_ALLOC_SIZE 16384
#define UI_HDR_LEN 3
#define N202 4
#define CRC24_LENGTH 3
static int gprs_llc_fcs(uint8_t *data, unsigned int len)
{
uint32_t fcs_calc;
fcs_calc = crc24_calc(INIT_CRC24, data, len);
fcs_calc = ~fcs_calc;
fcs_calc &= 0xffffff;
return fcs_calc;
}
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;
}
}
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++;
}
}
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) */
/* Send BSSGP-DL-UNITDATA.req */
return gprs_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);
}
/* Transmit a UI frame over the given SAPI */
int gprs_llc_tx_ui(struct msgb *msg, uint8_t sapi, int command,
void *mmctx)
{
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 = lle_by_tlli_sapi(msgb_tlli(msg), sapi);
if (!lle) {
struct gprs_llc_llme *llme;
LOGP(DLLC, LOGL_ERROR, "LLC TX: unknown TLLI 0x%08x, "
"creating LLME on the fly\n", msgb_tlli(msg));
llme = llme_alloc(msgb_tlli(msg));
lle = &llme->lle[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);
return -EFBIG;
}
/* 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;
/* encrypt information field + FCS, if needed! */
if (lle->llme->algo != GPRS_ALGO_GEA0) {
uint32_t iov_ui = 0; /* FIXME: randomly select for TLLI */
uint16_t crypt_len = (fcs + 3) - (llch + 3);
uint8_t cipher_out[GSM0464_CIPH_MAX_BLOCK];
uint32_t iv;
int rc, i;
uint64_t kc = *(uint64_t *)&lle->llme->kc;
/* Compute the 'Input' Paraemeter */
iv = gprs_cipher_gen_input_ui(iov_ui, sapi, nu, oc);
/* Compute the keystream that we need to XOR with the data */
rc = gprs_cipher_run(cipher_out, crypt_len, lle->llme->algo,
kc, iv, GPRS_CIPH_SGSN2MS);
if (rc < 0) {
LOGP(DLLC, LOGL_ERROR, "Error crypting UI frame: %d\n", rc);
return rc;
}
/* XOR the cipher output with the information field + FCS */
for (i = 0; i < crypt_len; i++)
*(llch + 3 + i) ^= cipher_out[i];
/* Mark frame as encrypted */
ctrl[1] |= 0x02;
}
/* Identifiers passed down: (BVCI, NSEI) */
/* Send BSSGP-DL-UNITDATA.req */
return gprs_bssgp_tx_dl_ud(msg, mmctx);
}
/* According to 6.4.1.6 / Figure 11 */
static int msgb_put_xid_par(struct msgb *msg, uint8_t type, uint8_t length, uint8_t *data)
{
uint8_t header_len = 1;
uint8_t *cur;
/* type is a 5-bit field... */
if (type > 0x1f)
return -EINVAL;
if (length > 3)
header_len = 2;
cur = msgb_put(msg, length + header_len);
/* build the header without or with XL bit */
if (length <= 3) {
*cur++ = (type << 2) | (length & 3);
} else {
*cur++ = 0x80 | (type << 2) | (length >> 6);
*cur++ = (length << 2);
}
/* copy over the payload of the parameter*/
memcpy(cur, data, length);
return length + header_len;
}
static void rx_llc_xid(struct gprs_llc_lle *lle,
struct gprs_llc_hdr_parsed *gph)
{
/* FIXME: 8.5.3.3: check if XID is invalid */
if (gph->is_cmd) {
/* FIXME: implement XID negotiation using SNDCP */
struct msgb *resp;
uint8_t *xid;
resp = msgb_alloc_headroom(4096, 1024, "LLC_XID");
xid = msgb_put(resp, gph->data_len);
memcpy(xid, gph->data, gph->data_len);
gprs_llc_tx_xid(lle, resp, 0);
} else {
/* FIXME: if we had sent a XID reset, send
* LLGMM-RESET.conf to GMM */
/* FIXME: implement XID negotiation using SNDCP */
}
}
static void gprs_llc_hdr_dump(struct gprs_llc_hdr_parsed *gph)
{
DEBUGP(DLLC, "LLC SAPI=%u %c %c FCS=0x%06x",
gph->sapi, gph->is_cmd ? 'C' : 'R', gph->ack_req ? 'A' : ' ',
gph->fcs);
if (gph->cmd)
DEBUGPC(DLLC, "CMD=%s ", get_value_string(llc_cmd_strs, gph->cmd));
if (gph->data)
DEBUGPC(DLLC, "DATA ");
DEBUGPC(DLLC, "\n");
}
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);
return -EIO;
}
/* 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;
}
return 0;
}
/* parse a GPRS LLC header, also check for invalid frames */
static int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp,
uint8_t *llc_hdr, int len)
{
uint8_t *ctrl = llc_hdr+1;
if (len <= CRC24_LENGTH)
return -EIO;
ghp->crc_length = len - CRC24_LENGTH;
ghp->ack_req = 0;
/* Section 5.5: FCS */
ghp->fcs = *(llc_hdr + len - 3);
ghp->fcs |= *(llc_hdr + len - 2) << 8;
ghp->fcs |= *(llc_hdr + len - 1) << 16;
/* Section 6.2.1: invalid PD field */
if (llc_hdr[0] & 0x80)
return -EIO;
/* This only works for the MS->SGSN direction */
if (llc_hdr[0] & 0x40)
ghp->is_cmd = 0;
else
ghp->is_cmd = 1;
ghp->sapi = llc_hdr[0] & 0xf;
/* Section 6.2.3: check for reserved SAPI */
switch (ghp->sapi) {
case 0:
case 4:
case 6:
case 0xa:
case 0xc:
case 0xd:
case 0xf:
return -EINVAL;
}
if ((ctrl[0] & 0x80) == 0) {
/* I (Information transfer + Supervisory) format */
uint8_t k;
ghp->data = ctrl + 3;
if (ctrl[0] & 0x40)
ghp->ack_req = 1;
ghp->seq_tx = (ctrl[0] & 0x1f) << 4;
ghp->seq_tx |= (ctrl[1] >> 4);
ghp->seq_rx = (ctrl[1] & 0x7) << 6;
ghp->seq_rx |= (ctrl[2] >> 2);
switch (ctrl[2] & 0x03) {
case 0:
ghp->cmd = GPRS_LLC_RR;
break;
case 1:
ghp->cmd = GPRS_LLC_ACK;
break;
case 2:
ghp->cmd = GPRS_LLC_RNR;
break;
case 3:
ghp->cmd = GPRS_LLC_SACK;
k = ctrl[3] & 0x1f;
ghp->data += 1 + k;
break;
}
ghp->data_len = (llc_hdr + len - 3) - ghp->data;
} else if ((ctrl[0] & 0xc0) == 0x80) {
/* S (Supervisory) format */
ghp->data = NULL;
ghp->data_len = 0;
if (ctrl[0] & 0x20)
ghp->ack_req = 1;
ghp->seq_rx = (ctrl[0] & 0x7) << 6;
ghp->seq_rx |= (ctrl[1] >> 2);
switch (ctrl[1] & 0x03) {
case 0:
ghp->cmd = GPRS_LLC_RR;
break;
case 1:
ghp->cmd = GPRS_LLC_ACK;
break;
case 2:
ghp->cmd = GPRS_LLC_RNR;
break;
case 3:
ghp->cmd = GPRS_LLC_SACK;
break;
}
} else if ((ctrl[0] & 0xe0) == 0xc0) {
/* UI (Unconfirmed Inforamtion) format */
ghp->cmd = GPRS_LLC_UI;
ghp->data = ctrl + 2;
ghp->data_len = (llc_hdr + len - 3) - ghp->data;
ghp->seq_tx = (ctrl[0] & 0x7) << 6;
ghp->seq_tx |= (ctrl[1] >> 2);
if (ctrl[1] & 0x02) {
ghp->is_encrypted = 1;
/* FIXME: encryption */
}
if (ctrl[1] & 0x01) {
/* FCS over hdr + all inf fields */
} else {
/* FCS over hdr + N202 octets (4) */
if (ghp->crc_length > UI_HDR_LEN + N202)
ghp->crc_length = UI_HDR_LEN + N202;
}
} else {
/* U (Unnumbered) format: 1 1 1 P/F M4 M3 M2 M1 */
ghp->data = NULL;
ghp->data_len = 0;
switch (ctrl[0] & 0xf) {
case GPRS_LLC_U_NULL_CMD:
ghp->cmd = GPRS_LLC_NULL;
break;
case GPRS_LLC_U_DM_RESP:
ghp->cmd = GPRS_LLC_DM;
break;
case GPRS_LLC_U_DISC_CMD:
ghp->cmd = GPRS_LLC_DISC;
break;
case GPRS_LLC_U_UA_RESP:
ghp->cmd = GPRS_LLC_UA;
break;
case GPRS_LLC_U_SABM_CMD:
ghp->cmd = GPRS_LLC_SABM;
break;
case GPRS_LLC_U_FRMR_RESP:
ghp->cmd = GPRS_LLC_FRMR;
break;
case GPRS_LLC_U_XID:
ghp->cmd = GPRS_LLC_XID;
ghp->data = ctrl + 1;
ghp->data_len = (llc_hdr + len - 3) - ghp->data;
break;
default:
return -EIO;
}
}
/* FIXME: parse sack frame */
if (ghp->cmd == GPRS_LLC_SACK) {
LOGP(DLLC, LOGL_NOTICE, "Unsupported SACK frame\n");
return -EIO;
}
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 bssgp_ud_hdr *udh = (struct bssgp_ud_hdr *) msgb_bssgph(msg);
struct gprs_llc_hdr *lh = (struct gprs_llc_hdr *) msgb_llch(msg);
struct gprs_llc_hdr_parsed llhp;
struct gprs_llc_lle *lle;
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_by_tlli_sapi(msgb_tlli(msg), llhp.sapi);
/* 7.2.1.1 LLC belonging to unassigned TLLI+SAPI shall be discarded,
* except UID and XID frames with SAPI=1 */
if (!lle) {
if (llhp.sapi == GPRS_SAPI_GMM &&
(llhp.cmd == GPRS_LLC_XID || llhp.cmd == GPRS_LLC_UI)) {
struct gprs_llc_llme *llme;
/* FIXME: don't use the TLLI but the 0xFFFF unassigned? */
llme = llme_alloc(msgb_tlli(msg));
LOGP(DLLC, LOGL_DEBUG, "LLC RX: unknown TLLI 0x%08x, "
"creating LLME on the fly\n", msgb_tlli(msg));
lle = &llme->lle[llhp.sapi];
} else {
LOGP(DLLC, LOGL_NOTICE,
"unknown TLLI/SAPI: Silently dropping\n");
return 0;
}
}
/* decrypt information field + FCS, if needed! */
if (llhp.is_encrypted) {
uint32_t iov_ui = 0; /* FIXME: randomly select for TLLI */
uint16_t crypt_len = llhp.data_len + 3;
uint8_t cipher_out[GSM0464_CIPH_MAX_BLOCK];
uint32_t iv;
uint64_t kc = *(uint64_t *)&lle->llme->kc;
int rc, i;
if (lle->llme->algo == GPRS_ALGO_GEA0) {
LOGP(DLLC, LOGL_NOTICE, "encrypted frame for LLC that "
"has no KC/Algo! Dropping.\n");
return 0;
}
iv = gprs_cipher_gen_input_ui(iov_ui, lle->sapi, llhp.seq_tx,
lle->oc_ui_recv);
rc = gprs_cipher_run(cipher_out, crypt_len, lle->llme->algo,
kc, iv, GPRS_CIPH_MS2SGSN);
if (rc < 0) {
LOGP(DLLC, LOGL_ERROR, "Error decrypting frame: %d\n",
rc);
return rc;
}
/* XOR the cipher output with the information field + FCS */
for (i = 0; i < crypt_len; i++)
*(llhp.data + i) ^= cipher_out[i];
} else {
if (lle->llme->algo != GPRS_ALGO_GEA0) {
LOGP(DLLC, LOGL_NOTICE, "unencrypted frame for LLC "
"that is supposed to be encrypted. Dropping.\n");
return 0;
}
}
/* 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;
/* llhp.data is only set when we need to send LL_[UNIT]DATA_IND up */
if (llhp.data) {
msgb_gmmh(msg) = llhp.data;
switch (llhp.sapi) {
case GPRS_SAPI_GMM:
/* send LL_UNITDATA_IND to GMM */
rc = gsm0408_gprs_rcvmsg(msg, lle->llme);
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;
}
/* 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,
enum gprs_ciph_algo alg, const uint8_t *kc)
{
unsigned int i;
/* Update the crypto parameters */
llme->algo = alg;
if (alg != GPRS_ALGO_GEA0)
memcpy(llme->kc, kc, sizeof(llme->kc));
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 toth Old and New on Rx */
llme->old_tlli = llme->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;
}
/* 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");
int random = rand();
/* First XID component must be RESET */
msgb_put_xid_par(msg, GPRS_LLC_XID_T_RESET, 0, NULL);
/* randomly select new IOV-UI */
msgb_put_xid_par(msg, GPRS_LLC_XID_T_IOV_UI, 4, (uint8_t *) &random);
/* FIXME: Start T200, wait for XID response */
return gprs_llc_tx_xid(&llme->lle[1], msg, 1);
}
int gprs_llc_init(const char *cipher_plugin_path)
{
return gprs_cipher_load(cipher_plugin_path);
}
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