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ipvs: Restrict sync message to 255 connections

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The nr_conns variable in the sync message header is only eight bits wide
and will overflow on interfaces with a large MTU. As a result the backup
won't parse all connections contained in the sync buffer. On regular
ethernet with an MTU of 1500 this isn't a problem, because we can't
overflow the value, but consider jumbo frames being used on a cross-over
connection between both directors.

We now restrict the size of the sync buffer, so that we never put more
than 255 connections into a single sync buffer.

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
Signed-off-by: Simon Horman <horms@verge.net.au>
This commit is contained in:
Sven Wegener 2008-09-19 20:41:56 +02:00 committed by Simon Horman
parent f5fff5dc8a
commit e6f225ebb7
1 changed files with 4 additions and 2 deletions
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6
net/ipv4/ipvs/ip_vs_sync.c
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@ -30,6 +30,7 @@
#include <linux/err.h>
#include <linux/kthread.h>
#include <linux/wait.h>
#include <linux/kernel.h>
#include <net/ip.h>
#include <net/sock.h>
@ -99,6 +100,7 @@ struct ip_vs_sync_thread_data {
*/
#define SYNC_MESG_HEADER_LEN 4
#define MAX_CONNS_PER_SYNCBUFF 255 /* nr_conns in ip_vs_sync_mesg is 8 bit */
struct ip_vs_sync_mesg {
__u8 nr_conns;
@ -516,8 +518,8 @@ static int set_sync_mesg_maxlen(int sync_state)
num = (dev->mtu - sizeof(struct iphdr) -
sizeof(struct udphdr) -
SYNC_MESG_HEADER_LEN - 20) / SIMPLE_CONN_SIZE;
sync_send_mesg_maxlen =
SYNC_MESG_HEADER_LEN + SIMPLE_CONN_SIZE * num;
sync_send_mesg_maxlen = SYNC_MESG_HEADER_LEN +
SIMPLE_CONN_SIZE * min(num, MAX_CONNS_PER_SYNCBUFF);
IP_VS_DBG(7, "setting the maximum length of sync sending "
"message %d.\n", sync_send_mesg_maxlen);
} else if (sync_state == IP_VS_STATE_BACKUP) {