netdev - [PATCH net-next v2] openvswitch: Pad OVS_PACKET_ATTR

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Message-ID: <20140114162749.GC24121@casper.infradead.org>
Date:	Tue, 14 Jan 2014 16:27:49 +0000
From:	Thomas Graf <tgraf@...g.ch>
To:	Zoltan Kiss <zoltan.kiss@...rix.com>
Cc:	Thomas Graf <tgraf@...hat.com>, Jesse Gross <jesse@...ira.com>,
	David Miller <davem@...emloft.net>,
	"dev@...nvswitch.org" <dev@...nvswitch.org>,
	netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next v2] openvswitch: Pad OVS_PACKET_ATTR_PACKET if
 linear copy was performed

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>
---
v2: initialize padding to 0's

 net/openvswitch/datapath.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index df46928..3ca9121 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -396,7 +396,7 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
 		.dst_sk = ovs_dp_get_net(dp)->genl_sock,
 		.snd_portid = upcall_info->portid,
 	};
-	size_t len;
+	size_t len, plen;
 	unsigned int hlen;
 	int err, dp_ifindex;
 
@@ -466,6 +466,11 @@ 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) &&
+	    (plen = (ALIGN(user_skb->len, NLA_ALIGNTO) - user_skb->len)) > 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);
--
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