From b997f8444313ff7ab99d66b400fc79cae8302166 Mon Sep 17 00:00:00 2001 From: Max Date: Wed, 6 Jul 2016 15:57:01 +0200 Subject: 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 --- openbsc/src/gprs/gprs_gmm.c | 39 ++++++++++++++++++++++++--------------- openbsc/src/gprs/gprs_llc.c | 26 ++++++++++++++++++++------ openbsc/src/gprs/gprs_sgsn.c | 6 +----- 3 files changed, 45 insertions(+), 26 deletions(-) (limited to 'openbsc/src/gprs') diff --git a/openbsc/src/gprs/gprs_gmm.c b/openbsc/src/gprs/gprs_gmm.c index 492c766c2..61edc650a 100644 --- a/openbsc/src/gprs/gprs_gmm.c +++ b/openbsc/src/gprs/gprs_gmm.c @@ -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); diff --git a/openbsc/src/gprs/gprs_llc.c b/openbsc/src/gprs/gprs_llc.c index b271e21ca..bc856e98e 100644 --- a/openbsc/src/gprs/gprs_llc.c +++ b/openbsc/src/gprs/gprs_llc.c @@ -22,6 +22,8 @@ #include #include +#include + #include #include #include @@ -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 */ diff --git a/openbsc/src/gprs/gprs_sgsn.c b/openbsc/src/gprs/gprs_sgsn.c index 711887e08..c2f2d5ba5 100644 --- a/openbsc/src/gprs/gprs_sgsn.c +++ b/openbsc/src/gprs/gprs_sgsn.c @@ -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); -- cgit v1.2.3