[ovs-dev] [PATCH v1 05/10] datapath-windows/Netlink: Fixed NlAttrParseNested
Ankur Sharma
ankursharma at vmware.com
Fri Sep 26 17:34:27 UTC 2014
Hi Sam,
Please find my replies inline.
Regards,
Ankur
________________________________________
From: Samuel Ghinet <sghinet at cloudbasesolutions.com>
Sent: Thursday, September 25, 2014 8:30 AM
To: dev at openvswitch.org
Cc: Ankur Sharma
Subject: RE: [ovs-dev] [PATCH v1 05/10] datapath-windows/Netlink: Fixed NlAttrParseNested
Hello Ankur,
This code confused me a little.
It looks correct, but I would have a few suggestions:
o)
> BOOLEAN
> NlAttrParse(const PNL_MSG_HDR nlMsg, UINT32 attrOffset,
> UINT32 attrLen,
the attrLen field gives the impression that it is the length of one single attribute.
You could try attributesLen, or totalAttrLen or smth similar, perhaps.
[ANKUR]: done
o) I find the functions NlMsgAttrLen and NlMsgPayloadLen a bit confusing:
[CODE]
UINT32
NlMsgAttrLen(const PNL_MSG_HDR nlh)
{
return NlMsgPayloadLen(nlh) - GENL_HDRLEN - OVS_HDRLEN;
}
[/CODE]
NlMsgPayloadLen: when you hear "payload", you think about the buffer, without NL_MSG_HDR, HDRLEN and HDRLEN.
NlMsgAttrLen: I tended to read it like "Netlink Message Attribute Length", and was thinking, it computes the length of the first netlink attribute? Perhaps a name like OvsMsgPayloadLength() would be more intuitive.
[ANKUR]: I have renamed the methods for more clarity.
NlMsgPayload ====> NlHdrPayload
NlMsgPayloadLen ====> NlHdrPayloadLen
NlMsgAttrLen ==> NlMsgAttrsLen
o) I find it a bit odd that a function like NlAttrParse, which parses attributes, would require: the message header, the ovs message payload length and the offset.
Perhaps it would have been simpler if NlAttrParse had assumed that the pointer provided is the beginning of the first netlink attribute, and not validate the message itself.
It is possible such changes would make code clearer a bit.
However, there is existing code that relies on the current format of NlAttrParse, so perhaps on a new patch.
[ANKUR]: Point noted. I have a few more netlink related series coming in next week. This comment will be addressed there.
Acked-by: Samuel Ghinet <sghinet at cloudbasesolutions.com>
________________________________________
Date: Wed, 24 Sep 2014 00:15:39 -0700
From: Ankur Sharma <ankursharma at vmware.com>
To: dev at openvswitch.org
Subject: [ovs-dev] [PATCH v1 05/10] datapath-windows/Netlink: Fixed
NlAttrParseNested
Message-ID: <1411542944-19374-5-git-send-email-ankursharma at vmware.com>
NlAttrParseNested was using the whole netlink payload for iteration.
This is not correct, as it would lead to exceeding the
nested attribute boundries. Fixed the same in this patch.
---
datapath-windows/ovsext/Datapath.c | 4 +++-
datapath-windows/ovsext/Netlink/Netlink.c | 15 ++++++++++++---
datapath-windows/ovsext/Netlink/Netlink.h | 8 ++++----
3 files changed, 19 insertions(+), 8 deletions(-)
diff --git a/datapath-windows/ovsext/Datapath.c b/datapath-windows/ovsext/Datapath.c
index 0dfdd57..ffb7d44 100644
--- a/datapath-windows/ovsext/Datapath.c
+++ b/datapath-windows/ovsext/Datapath.c
@@ -949,7 +949,8 @@ OvsSubscribeEventCmdHandler(POVS_USER_PARAMS_CONTEXT usrParamsCtx,
(POVS_OPEN_INSTANCE)usrParamsCtx->ovsInstance;
POVS_MESSAGE msgIn = (POVS_MESSAGE)usrParamsCtx->inputBuffer;
- rc = NlAttrParse(&msgIn->nlMsg, sizeof (*msgIn),policy, attrs, 2);
+ rc = NlAttrParse(&msgIn->nlMsg, sizeof (*msgIn),
+ NlMsgAttrLen((PNL_MSG_HDR)msgIn), policy, attrs, 2);
if (!rc) {
status = STATUS_INVALID_PARAMETER;
goto done;
@@ -1107,6 +1108,7 @@ HandleDpTransaction(POVS_USER_PARAMS_CONTEXT usrParamsCtx,
if (usrParamsCtx->ovsMsg->genlMsg.cmd == OVS_DP_CMD_SET) {
if (!NlAttrParse((PNL_MSG_HDR)msgIn,
NLMSG_HDRLEN + GENL_HDRLEN + OVS_HDRLEN,
+ NlMsgAttrLen((PNL_MSG_HDR)msgIn),
ovsDatapathSetPolicy, dpAttrs, ARRAY_SIZE(dpAttrs))) {
return STATUS_INVALID_PARAMETER;
}
diff --git a/datapath-windows/ovsext/Netlink/Netlink.c b/datapath-windows/ovsext/Netlink/Netlink.c
index 5c74ec0..a72d846 100644
--- a/datapath-windows/ovsext/Netlink/Netlink.c
+++ b/datapath-windows/ovsext/Netlink/Netlink.c
@@ -969,6 +969,7 @@ NlAttrFindNested(const PNL_ATTR nla, UINT16 type)
*/
BOOLEAN
NlAttrParse(const PNL_MSG_HDR nlMsg, UINT32 attrOffset,
+ UINT32 attrLen,
const NL_POLICY policy[],
PNL_ATTR attrs[], UINT32 n_attrs)
{
@@ -979,14 +980,21 @@ NlAttrParse(const PNL_MSG_HDR nlMsg, UINT32 attrOffset,
RtlZeroMemory(attrs, n_attrs * sizeof *attrs);
- if ((NlMsgSize(nlMsg) < attrOffset) || (!(NlMsgAttrLen(nlMsg)))) {
+
+ /* There is nothing to parse */
+ if (!(NlMsgAttrLen(nlMsg))) {
+ ret = TRUE;
+ goto done;
+ }
+
+ if ((NlMsgSize(nlMsg) < attrOffset)) {
OVS_LOG_WARN("No attributes in nlMsg: %p at offset: %d",
nlMsg, attrOffset);
goto done;
}
NL_ATTR_FOR_EACH (nla, left, NlMsgAt(nlMsg, attrOffset),
- NlMsgSize(nlMsg) - attrOffset)
+ attrLen)
{
UINT16 type = NlAttrType(nla);
if (type < n_attrs && policy[type].type != NL_A_NO_ATTR) {
@@ -1035,9 +1043,10 @@ done:
*/
BOOLEAN
NlAttrParseNested(const PNL_MSG_HDR nlMsg, UINT32 attrOffset,
+ UINT32 attrLen,
const NL_POLICY policy[],
PNL_ATTR attrs[], UINT32 n_attrs)
{
return NlAttrParse(nlMsg, attrOffset + NLA_HDRLEN,
- policy, attrs, n_attrs);
+ attrLen - NLA_HDRLEN, policy, attrs, n_attrs);
}
diff --git a/datapath-windows/ovsext/Netlink/Netlink.h b/datapath-windows/ovsext/Netlink/Netlink.h
index 80f98dd..023c673 100644
--- a/datapath-windows/ovsext/Netlink/Netlink.h
+++ b/datapath-windows/ovsext/Netlink/Netlink.h
@@ -125,11 +125,11 @@ const PNL_ATTR NlAttrFind__(const PNL_ATTR attrs,
const PNL_ATTR NlAttrFindNested(const PNL_ATTR nla,
UINT16 type);
BOOLEAN NlAttrParse(const PNL_MSG_HDR nlMsg, UINT32 attrOffset,
- const NL_POLICY policy[],
+ UINT32 attrLen, const NL_POLICY policy[],
PNL_ATTR attrs[], UINT32 n_attrs);
-BOOLEAN NlParseNested(const PNL_ATTR, const NL_POLICY policy[],
- PNL_ATTR attrs[], UINT32 n_attrs);
-
+BOOLEAN NlAttrParseNested(const PNL_MSG_HDR nlMsg, UINT32 attrOffset,
+ UINT32 attrLen, const NL_POLICY policy[],
+ PNL_ATTR attrs[], UINT32 n_attrs);
/*
* --------------------------------------------------------------------------
* Returns the length of attribute.
--
1.9.1
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