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SGSN: add preliminary support for GPRS encryption 

It is already functional enough to allow testing with real
phones. However, note - there are several limitations in the current
implementation:

* only default value for IOV-UI is supported at the moment
* AUTN-based key material is not supported

Related: OS#1582
Change-Id: I8900b906693496e4e6b35be5a86937c58039ed9e
This commit is contained in:
Max 2016-07-06 15:57:01 +02:00 committed by Harald Welte
parent 5aa5196fbf
commit b997f84443
6 changed files with 49 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
openbsc/include/openbsc/gprs_gmm.h
View File

@ -12,7 +12,8 @@ int gsm48_tx_gsm_deact_pdp_acc(struct sgsn_pdp_ctx *pdp);
int gsm0408_gprs_rcvmsg_gb(struct msgb *msg, struct gprs_llc_llme *llme);
int gsm0408_gprs_force_reattach(struct sgsn_mm_ctx *mmctx);
int gsm0408_gprs_force_reattach_oldmsg(struct msgb *msg);
int gsm0408_gprs_force_reattach_oldmsg(struct msgb *msg,
struct gprs_llc_llme *llme);
void gsm0408_gprs_access_granted(struct sgsn_mm_ctx *mmctx);
void gsm0408_gprs_access_denied(struct sgsn_mm_ctx *mmctx, int gmm_cause);
void gsm0408_gprs_access_cancelled(struct sgsn_mm_ctx *mmctx, int gmm_cause);

3
openbsc/include/openbsc/gprs_llc.h
View File

@ -215,7 +215,8 @@ int gprs_llc_tx_ui(struct msgb *msg, uint8_t sapi, int command,
/* Chapter 7.2.1.2 LLGMM-RESET.req */
int gprs_llgmm_reset(struct gprs_llc_llme *llme);
int gprs_llgmm_reset_oldmsg(struct msgb* oldmsg, uint8_t sapi);
int gprs_llgmm_reset_oldmsg(struct msgb* oldmsg, uint8_t sapi,
struct gprs_llc_llme *llme);
/* 04.64 Chapter 7.2.1.1 LLGMM-ASSIGN */
int gprs_llgmm_assign(struct gprs_llc_llme *llme,

3
openbsc/include/openbsc/gprs_sgsn.h
View File

@ -357,9 +357,6 @@ int drop_all_pdp_for_ggsn(struct sgsn_ggsn_ctx *ggsn);
char *gprs_pdpaddr2str(uint8_t *pdpa, uint8_t len);
/* Force re-attachment based on msgb meta data */
int sgsn_force_reattach_oldmsg(struct msgb *oldmsg);
/*
* ctrl interface related work
*/

39
openbsc/src/gprs/gprs_gmm.c
View File

@ -418,9 +418,9 @@ static int gsm48_tx_gmm_id_req(struct sgsn_mm_ctx *mm, uint8_t id_type)
return gsm48_gmm_sendmsg(msg, 1, mm);
}
/* Section 9.4.9: Authentication and Ciphering Request */
/* 3GPP TS 24.008 Section 9.4.9: Authentication and Ciphering Request */
static int gsm48_tx_gmm_auth_ciph_req(struct sgsn_mm_ctx *mm, uint8_t *rnd,
uint8_t key_seq, uint8_t algo)
uint8_t key_seq, bool force_standby)
{
struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 AUTH CIPH REQ");
struct gsm48_hdr *gh;
@ -437,9 +437,11 @@ static int gsm48_tx_gmm_auth_ciph_req(struct sgsn_mm_ctx *mm, uint8_t *rnd,
gh->msg_type = GSM48_MT_GMM_AUTH_CIPH_REQ;
acreq = (struct gsm48_auth_ciph_req *) msgb_put(msg, sizeof(*acreq));
acreq->ciph_alg = algo & 0xf;
acreq->ciph_alg = mm->ciph_algo & 0xf;
/* § 10.5.5.10: */
acreq->imeisv_req = 0x1;
acreq->force_stby = 0x0;
/* § 10.5.5.7: */
acreq->force_stby = force_standby;
/* 3GPP TS 24.008 § 10.5.5.19: */
if (RAND_bytes(&rbyte, 1) != 1) {
LOGP(DMM, LOGL_NOTICE, "RAND_bytes failed for A&C ref, falling "
@ -454,11 +456,11 @@ static int gsm48_tx_gmm_auth_ciph_req(struct sgsn_mm_ctx *mm, uint8_t *rnd,
m_rand = msgb_put(msg, 16+1);
m_rand[0] = GSM48_IE_GMM_AUTH_RAND;
memcpy(m_rand + 1, rnd, 16);
/* § 10.5.1.2: */
m_cksn = msgb_put(msg, 1);
m_cksn[0] = (GSM48_IE_GMM_CIPH_CKSN << 4) | (key_seq & 0x07);
}
/* FIXME: add AUTN for 3g auth according to 3GPP TS 24.008 § 10.5.3.1.1 */
/* FIXME: make sure we don't send any other messages to the MS */
return gsm48_gmm_sendmsg(msg, 1, mm);
@ -652,8 +654,7 @@ static int gsm48_gmm_authorize(struct sgsn_mm_ctx *ctx)
mmctx_timer_start(ctx, 3360, sgsn->cfg.timers.T3360);
return gsm48_tx_gmm_auth_ciph_req(ctx, at->vec.rand,
at->key_seq,
GPRS_ALGO_GEA0);
at->key_seq, false);
}
if (ctx->auth_state == SGSN_AUTH_AUTHENTICATE && ctx->is_authenticated &&
@ -959,7 +960,15 @@ static int gsm48_rx_gmm_att_req(struct sgsn_mm_ctx *ctx, struct msgb *msg,
ctx->ms_radio_access_capa.len);
ctx->ms_network_capa.len = msnc_len;
memcpy(ctx->ms_network_capa.buf, msnc, msnc_len);
if (!gprs_ms_net_cap_gea_supported(ctx->ms_network_capa.buf, msnc_len,
ctx->ciph_algo)) {
reject_cause = GMM_CAUSE_PROTO_ERR_UNSPEC;
LOGMMCTXP(LOGL_NOTICE, ctx, "Rejecting ATTACH REQUEST with MI "
"type %s because MS do not support required %s "
"encryption\n", gsm48_mi_type_name(mi_type),
get_value_string(gprs_cipher_names,ctx->ciph_algo));
goto rejected;
}
#ifdef PTMSI_ALLOC
/* Allocate a new P-TMSI (+ P-TMSI signature) and update TLLI */
/* Don't change the P-TMSI if a P-TMSI re-assignment is under way */
@ -1355,7 +1364,7 @@ static int gsm0408_rcv_gmm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
}
/* Force the MS to re-attach */
rc = sgsn_force_reattach_oldmsg(msg);
rc = gsm0408_gprs_force_reattach_oldmsg(msg, llme);
/* TLLI unassignment */
gprs_llgmm_unassign(llme);
@ -1534,8 +1543,7 @@ static void mmctx_timer_cb(void *_mm)
}
at = &mm->auth_triplet;
gsm48_tx_gmm_auth_ciph_req(mm, at->vec.rand, at->key_seq,
GPRS_ALGO_GEA0);
gsm48_tx_gmm_auth_ciph_req(mm, at->vec.rand, at->key_seq, false);
osmo_timer_schedule(&mm->timer, sgsn->cfg.timers.T3360, 0);
break;
case 3370: /* waiting for IDENTITY RESPONSE */
@ -2094,7 +2102,7 @@ static int gsm0408_rcv_gsm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
if (gh->msg_type == GSM48_MT_GSM_STATUS)
return 0;
return sgsn_force_reattach_oldmsg(msg);
return gsm0408_gprs_force_reattach_oldmsg(msg, llme);
}
switch (gh->msg_type) {
@ -2128,10 +2136,11 @@ static int gsm0408_rcv_gsm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
return rc;
}
int gsm0408_gprs_force_reattach_oldmsg(struct msgb *msg)
int gsm0408_gprs_force_reattach_oldmsg(struct msgb *msg,
struct gprs_llc_llme *llme)
{
int rc;
gprs_llgmm_reset_oldmsg(msg, GPRS_SAPI_GMM);
gprs_llgmm_reset_oldmsg(msg, GPRS_SAPI_GMM, llme);
rc = gsm48_tx_gmm_detach_req_oldmsg(
msg, GPRS_DET_T_MT_REATT_REQ, GMM_CAUSE_IMPL_DETACHED);

26
openbsc/src/gprs/gprs_llc.c
View File

@ -22,6 +22,8 @@
#include <errno.h>
#include <stdint.h>
#include <openssl/rand.h>
#include <osmocom/core/msgb.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/timer.h>
@ -598,7 +600,8 @@ int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv)
case GPRS_SAPI_SNDCP9:
case GPRS_SAPI_SNDCP11:
/* Ask an upper layer for help. */
return sgsn_force_reattach_oldmsg(msg);
return gsm0408_gprs_force_reattach_oldmsg(msg,
lle->llme);
default:
break;
}
@ -769,13 +772,18 @@ int gprs_llgmm_unassign(struct gprs_llc_llme *llme)
int gprs_llgmm_reset(struct gprs_llc_llme *llme)
{
struct msgb *msg = msgb_alloc_headroom(4096, 1024, "LLC_XID");
int random = rand();
struct gprs_llc_lle *lle = &llme->lle[1];
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();
}
/* 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);
msgb_put_xid_par(msg, GPRS_LLC_XID_T_IOV_UI, 4, (uint8_t *) &llme->iov_ui);
/* Reset some of the LLC parameters. See GSM 04.64, 8.5.3.1 */
lle->vu_recv = 0;
@ -787,15 +795,21 @@ int gprs_llgmm_reset(struct gprs_llc_llme *llme)
return gprs_llc_tx_xid(lle, msg, 1);
}
int gprs_llgmm_reset_oldmsg(struct msgb* oldmsg, uint8_t sapi)
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");
int random = rand();
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();
}
/* 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);
msgb_put_xid_par(msg, GPRS_LLC_XID_T_IOV_UI, 4, (uint8_t *) &llme->iov_ui);
/* FIXME: Start T200, wait for XID response */

6
openbsc/src/gprs/gprs_sgsn.c
View File

@ -169,6 +169,7 @@ struct sgsn_mm_ctx *sgsn_mm_ctx_alloc(uint32_t tlli,
ctx->gb.tlli = tlli;
ctx->mm_state = GMM_DEREGISTERED;
ctx->auth_triplet.key_seq = GSM_KEY_SEQ_INVAL;
ctx->ciph_algo = sgsn->cfg.cipher;
ctx->ctrg = rate_ctr_group_alloc(ctx, &mmctx_ctrg_desc, tlli);
INIT_LLIST_HEAD(&ctx->pdp_list);
@ -604,11 +605,6 @@ int drop_all_pdp_for_ggsn(struct sgsn_ggsn_ctx *ggsn)
return num;
}
int sgsn_force_reattach_oldmsg(struct msgb *oldmsg)
{
return gsm0408_gprs_force_reattach_oldmsg(oldmsg);
}
void sgsn_update_subscriber_data(struct sgsn_mm_ctx *mmctx)
{
OSMO_ASSERT(mmctx != NULL);