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SGSN: fix FCS calculation for encrypted frames 

Change-Id: I352bc9db0c17fff773788831c4389ec0a5a30af8
Related: OS#1582
This commit is contained in:
Dieter Spaar 2016-07-11 12:48:07 +02:00 committed by Harald Welte
parent 9ddd8e6267
commit b572d7c45e
1 changed files with 10 additions and 4 deletions
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14
openbsc/src/gprs/gprs_llc.c
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@ -357,7 +357,7 @@ static int apply_gea(struct gprs_llc_lle *lle, uint16_t crypt_len, uint16_t nu,
return -EINVAL;
/* Compute the 'Input' Paraemeter */
uint32_t iv = gprs_cipher_gen_input_ui(lle->llme->iov_ui, sapi,
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,
@ -371,6 +371,12 @@ static int apply_gea(struct gprs_llc_lle *lle, uint16_t crypt_len, uint16_t nu,
}
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;
}
@ -452,9 +458,6 @@ int gprs_llc_tx_ui(struct msgb *msg, uint8_t sapi, int command,
msgb_free(msg);
return rc;
}
/* Mark frame as encrypted */
ctrl[1] |= 0x02;
}
/* Identifiers passed down: (BVCI, NSEI) */
@ -640,6 +643,9 @@ int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv)
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");