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gprs_gmm: Check for RAT change and ensure this only happens for RAU/ATT 

Change-Id: I38cb31907eddeade5350cdb648df179408d908d2
Related: OS#3727
This commit is contained in:
Daniel Willmann 2020-01-30 12:30:40 +01:00
parent 394aa533e9
commit d999e54aa2
1 changed files with 27 additions and 0 deletions
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27
src/sgsn/gprs_gmm.c
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@ -1099,6 +1099,16 @@ static inline void ptmsi_update(struct sgsn_mm_ctx *ctx)
osmo_fsm_inst_dispatch(ctx->gmm_fsm, E_GMM_COMMON_PROC_INIT_REQ, NULL);
}
/* Detect if RAT has changed */
static bool mmctx_did_rat_change(struct sgsn_mm_ctx *mmctx, struct msgb *msg)
{
if (MSG_IU_UE_CTX(msg) && mmctx->ran_type != MM_CTX_T_UTRAN_Iu)
return true;
if (!MSG_IU_UE_CTX(msg) && mmctx->ran_type != MM_CTX_T_GERAN_Gb)
return true;
return false;
}
/* 3GPP TS 24.008 § 9.4.1 Attach request */
static int gsm48_rx_gmm_att_req(struct sgsn_mm_ctx *ctx, struct msgb *msg,
struct gprs_llc_llme *llme)
@ -1944,6 +1954,23 @@ int gsm0408_rcv_gmm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
return rc;
}
/* A RAT change is only expected/allowed for RAU/Attach Req */
if (mmctx && mmctx_did_rat_change(mmctx, msg)) {
switch (gh->msg_type) {
case GSM48_MT_GMM_RA_UPD_REQ:
case GSM48_MT_GMM_ATTACH_REQ:
break;
default:
/* This shouldn't happen with other message types and
* we need to error out to prevent a crash */
LOGMMCTXP(LOGL_NOTICE, mmctx, "Dropping GMM %s which was received on different "
"RAT (mmctx ran_type=%u, msg_iu_ue_ctx=%p\n",
get_value_string(gprs_msgt_gmm_names, gh->msg_type),
mmctx->ran_type, MSG_IU_UE_CTX(msg));
return -EINVAL;
}
}
/*
* For a few messages, mmctx may be NULL. For most, we want to ensure a
* non-NULL mmctx. At the same time, we want to keep the message