netdev - [PATCH][EBTABLES] Fix alignment checks in ebt

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Date:	Tue, 26 Feb 2008 17:38:05 +0300
From:	Pavel Emelyanov <xemul@...nvz.org>
To:	Bart De Schuymer <bart.de.schuymer@...dora.be>
CC:	ebtables-devel@...ts.sourceforge.net,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: [PATCH][EBTABLES] Fix alignment checks in ebt_among.ko module.

When trying to do

	# ebtables -A FORWARD --among-src 0:12:34:56:78:9a=192.168.0.10 -j ACCEPT

on x86_64 box the ebt_among->check() callback warns me that

	ebtables: among: wrong size: 1060 against expected 1056, rounded to 1056

Checking the ebtables sources, I found that the alignment is done
differently in the tool and the kernel. Tool makes it like this:

	EBT_ALIGN(sizeof(struct ebt_among_info)) + X

while the kernel module like this:

	EBT_ALIGN(sizeof(struct ebt_among_info) + X)

So the suggested fix is to move the alignment in the kernel. After
the fix the rule is added and appears in the ebtables -L output.

Originally developed by Evgeny Kravtsunov.

Prepared against net-2.6 tree.

Signed-off-by: Evgeny Kravtsunov <emkravts@...nvz.org>
Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>

---

diff --git a/net/bridge/netfilter/ebt_among.c b/net/bridge/netfilter/ebt_among.c
index 70b6dca..349a543 100644
--- a/net/bridge/netfilter/ebt_among.c
+++ b/net/bridge/netfilter/ebt_among.c
@@ -182,7 +182,7 @@ static int ebt_among_check(const char *tablename, unsigned int hookmask,
 			   unsigned int datalen)
 {
 	const struct ebt_among_info *info = data;
-	int expected_length = sizeof(struct ebt_among_info);
+	int expected_length = EBT_ALIGN(sizeof(struct ebt_among_info));
 	const struct ebt_mac_wormhash *wh_dst, *wh_src;
 	int err;
 
@@ -191,7 +191,7 @@ static int ebt_among_check(const char *tablename, unsigned int hookmask,
 	expected_length += ebt_mac_wormhash_size(wh_dst);
 	expected_length += ebt_mac_wormhash_size(wh_src);
 
-	if (datalen != EBT_ALIGN(expected_length)) {
+	if (datalen != expected_length) {
 		printk(KERN_WARNING
 		       "ebtables: among: wrong size: %d "
 		       "against expected %d, rounded to %Zd\n",
--
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