diff options
| author | Harald Welte <laforge@gnumonks.org> | 2010-06-30 23:15:57 +0200 |
|---|---|---|
| committer | Harald Welte <laforge@gnumonks.org> | 2010-07-02 22:55:39 +0200 |
| commit | 1b8827ae5b51394374a357e6ab63edd867a79f37 (patch) | |
| tree | 312749031ddaa45941364ad95cb769c9a356742a | |
| parent | d07b4f99cef6906702c555cfcb923d0d76473916 (diff) | |
[SGSN] LLC: Make sure we calculate FCS after decryption
| -rw-r--r-- | openbsc/src/gprs/gprs_llc.c | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/openbsc/src/gprs/gprs_llc.c b/openbsc/src/gprs/gprs_llc.c index 4c870d3fd..cd0a64f3a 100644 --- a/openbsc/src/gprs/gprs_llc.c +++ b/openbsc/src/gprs/gprs_llc.c @@ -200,6 +200,7 @@ struct gprs_llc_hdr_parsed { uint32_t fcs_calc; uint8_t *data; uint16_t data_len; + uint16_t crc_length; enum gprs_llc_cmd cmd; }; @@ -480,13 +481,11 @@ static int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp, { uint8_t *ctrl = llc_hdr+1; int is_sack = 0; - unsigned int crc_length; - uint32_t fcs_calc; if (len <= CRC24_LENGTH) return -EIO; - crc_length = len - CRC24_LENGTH; + ghp->crc_length = len - CRC24_LENGTH; ghp->ack_req = 0; @@ -591,8 +590,8 @@ static int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp, /* FCS over hdr + all inf fields */ } else { /* FCS over hdr + N202 octets (4) */ - if (crc_length > UI_HDR_LEN + N202) - crc_length = UI_HDR_LEN + N202; + 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 */ @@ -628,11 +627,6 @@ static int gprs_llc_hdr_parse(struct gprs_llc_hdr_parsed *ghp, } } - if (!ghp->is_encrypted) { - /* calculate what FCS we expect */ - ghp->fcs_calc = gprs_llc_fcs(llc_hdr, crc_length); - } - /* FIXME: parse sack frame */ if (ghp->cmd == GPRS_LLC_SACK) { LOGP(DLLC, LOGL_NOTICE, "Unsupported SACK frame\n"); @@ -729,6 +723,7 @@ int gprs_llc_rcvmsg(struct msgb *msg, struct tlv_parsed *tv) } /* 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; |