Change in osmo-bts[master]: OML: Reject segmented OML messages

[Harald Welte]

Harald Welte has uploaded this change for review. ( https://gerrit.osmocom.org/12871


Change subject: OML: Reject segmented OML messages
......................................................................

OML: Reject segmented OML messages

TS 12.21 describes segmenting of OML messages using placement
fist/middle/last and the "sequence' number of the OML header. We don't
implement this and hence must ignore or reject any related messages.

Before this patch however, we simply treated such segments as if they
were a complete OML message.  Let's fix that.

Change-Id: Idd42cf4edc1bf9ab366853bd9b0f7afd9c060910
Closes: OS#3795
---
M src/common/oml.c
1 file changed, 9 insertions(+), 1 deletion(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/71/12871/1

diff --git a/src/common/oml.c b/src/common/oml.c
index 4dfaaf4..2ae5af5 100644
--- a/src/common/oml.c
+++ b/src/common/oml.c
@@ -1422,13 +1422,21 @@
 	struct abis_om_hdr *oh = msgb_l2(msg);
 	int ret = 0;
 
-	if (msgb_l2len(msg) < 1) {
+	if (msgb_l2len(msg) < sizeof(*oh)) {
 		LOGP(DOML, LOGL_NOTICE, "OML message too short\n");
 		msgb_free(msg);
 		return -EIO;
 	}
 	msg->l3h = (unsigned char *)oh + sizeof(*oh);
 
+	/* We don't implement de-segmentation of segmented OML messages */
+	if (oh->placement != ABIS_OM_PLACEMENT_ONLY || oh->sequence != 0) {
+		oml_tx_failure_event_rep(&bts->mo, OSMO_EVT_MAJ_UKWN_MSG,
+					 "Unsupported segmented O&M message\n");
+		msgb_free(msg);
+		return -EIO;
+	}
+
 	switch (oh->mdisc) {
 	case ABIS_OM_MDISC_FOM:
 		if (msgb_l2len(msg) < sizeof(*oh)) {

-- 
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Idd42cf4edc1bf9ab366853bd9b0f7afd9c060910
Gerrit-Change-Number: 12871
Gerrit-PatchSet: 1
Gerrit-Owner: Harald Welte <laforge at gnumonks.org>
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