netdev - [PATCH net 1/5] openvswitch: Pad OVS_PACKET_ATTR

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Message-Id: <1391583561-25399-2-git-send-email-jesse@nicira.com>
Date:	Tue,  4 Feb 2014 22:59:17 -0800
From:	Jesse Gross <jesse@...ira.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, dev@...nvswitch.org,
	Thomas Graf <tgraf@...g.ch>,
	Zoltan Kiss <zoltan.kiss@...rix.com>,
	Jesse Gross <jesse@...ira.com>
Subject: [PATCH net 1/5] openvswitch: Pad OVS_PACKET_ATTR_PACKET if linear copy was performed

From: Thomas Graf <tgraf@...g.ch>

While the zerocopy method is correctly omitted if user space
does not support unaligned Netlink messages. The attribute is
still not padded correctly as skb_zerocopy() will not ensure
padding and the attribute size is no longer pre calculated
though nla_reserve() which ensured padding previously.

This patch applies appropriate padding if a linear data copy
was performed in skb_zerocopy().

Signed-off-by: Thomas Graf <tgraf@...g.ch>
Acked-by: Zoltan Kiss <zoltan.kiss@...rix.com>
Signed-off-by: Jesse Gross <jesse@...ira.com>
---
 net/openvswitch/datapath.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index df46928..d1a73a6 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -466,6 +466,14 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
 
 	skb_zerocopy(user_skb, skb, skb->len, hlen);
 
+	/* Pad OVS_PACKET_ATTR_PACKET if linear copy was performed */
+	if (!(dp->user_features & OVS_DP_F_UNALIGNED)) {
+		size_t plen = NLA_ALIGN(user_skb->len) - user_skb->len;
+
+		if (plen > 0)
+			memset(skb_put(user_skb, plen), 0, plen);
+	}
+
 	((struct nlmsghdr *) user_skb->data)->nlmsg_len = user_skb->len;
 
 	err = genlmsg_unicast(ovs_dp_get_net(dp), user_skb, upcall_info->portid);
-- 
1.8.3.2

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