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netdevice: Fix promiscuity and allmulti overflow

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Max of promiscuity and allmulti plus positive @inc can cause overflow.
Fox example: when allmulti=0xFFFFFFFF, any caller give dev_set_allmulti() a
positive @inc will cause allmulti be off.
This is not what we want, though it's rare case.
The fix is that only negative @inc will cause allmulti or promiscuity be off
and when any caller makes the counters touch the roof, we return error.

Change of v2:
Change void function dev_set_promiscuity/allmulti to return int.
So callers can get the overflow error.
Caller's fix will be done later.

Change of v3:
1. Since we return error to caller, we don't need to print KERN_ERROR,
KERN_WARNING is enough.
2. In dev_set_promiscuity(), if __dev_set_promiscuity() failed, we
return at once.

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wang Chen 2008-06-18 01:48:28 -07:00 committed by David S. Miller
parent dd574dbfcc
commit dad9b335c6
2 changed files with 47 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/netdevice.h
View File

@ -1476,8 +1476,8 @@ extern int __dev_addr_delete(struct dev_addr_list **list, int *count, void *ad
extern int __dev_addr_add(struct dev_addr_list **list, int *count, void *addr, int alen, int newonly);
extern int __dev_addr_sync(struct dev_addr_list **to, int *to_count, struct dev_addr_list **from, int *from_count);
extern void __dev_addr_unsync(struct dev_addr_list **to, int *to_count, struct dev_addr_list **from, int *from_count);
extern void dev_set_promiscuity(struct net_device *dev, int inc);
extern void dev_set_allmulti(struct net_device *dev, int inc);
extern int dev_set_promiscuity(struct net_device *dev, int inc);
extern int dev_set_allmulti(struct net_device *dev, int inc);
extern void netdev_state_change(struct net_device *dev);
extern void netdev_bonding_change(struct net_device *dev);
extern void netdev_features_change(struct net_device *dev);

55
net/core/dev.c
View File

@ -2771,16 +2771,29 @@ int netdev_set_master(struct net_device *slave, struct net_device *master)
return 0;
}
static void __dev_set_promiscuity(struct net_device *dev, int inc)
static int __dev_set_promiscuity(struct net_device *dev, int inc)
{
unsigned short old_flags = dev->flags;
ASSERT_RTNL();
if ((dev->promiscuity += inc) == 0)
dev->flags &= ~IFF_PROMISC;
else
dev->flags |= IFF_PROMISC;
dev->flags |= IFF_PROMISC;
dev->promiscuity += inc;
if (dev->promiscuity == 0) {
/*
* Avoid overflow.
* If inc causes overflow, untouch promisc and return error.
*/
if (inc < 0)
dev->flags &= ~IFF_PROMISC;
else {
dev->promiscuity -= inc;
printk(KERN_WARNING "%s: promiscuity touches roof, "
"set promiscuity failed, promiscuity feature "
"of device might be broken.\n", dev->name);
return -EOVERFLOW;
}
}
if (dev->flags != old_flags) {
printk(KERN_INFO "device %s %s promiscuous mode\n",
dev->name, (dev->flags & IFF_PROMISC) ? "entered" :
@ -2798,6 +2811,7 @@ static void __dev_set_promiscuity(struct net_device *dev, int inc)
if (dev->change_rx_flags)
dev->change_rx_flags(dev, IFF_PROMISC);
}
return 0;
}
/**
@ -2809,14 +2823,19 @@ static void __dev_set_promiscuity(struct net_device *dev, int inc)
* remains above zero the interface remains promiscuous. Once it hits zero
* the device reverts back to normal filtering operation. A negative inc
* value is used to drop promiscuity on the device.
* Return 0 if successful or a negative errno code on error.
*/
void dev_set_promiscuity(struct net_device *dev, int inc)
int dev_set_promiscuity(struct net_device *dev, int inc)
{
unsigned short old_flags = dev->flags;
int err;
__dev_set_promiscuity(dev, inc);
err = __dev_set_promiscuity(dev, inc);
if (!err)
return err;
if (dev->flags != old_flags)
dev_set_rx_mode(dev);
return err;
}
/**
@ -2829,22 +2848,38 @@ void dev_set_promiscuity(struct net_device *dev, int inc)
* to all interfaces. Once it hits zero the device reverts back to normal
* filtering operation. A negative @inc value is used to drop the counter
* when releasing a resource needing all multicasts.
* Return 0 if successful or a negative errno code on error.
*/
void dev_set_allmulti(struct net_device *dev, int inc)
int dev_set_allmulti(struct net_device *dev, int inc)
{
unsigned short old_flags = dev->flags;
ASSERT_RTNL();
dev->flags |= IFF_ALLMULTI;
if ((dev->allmulti += inc) == 0)
dev->flags &= ~IFF_ALLMULTI;
dev->allmulti += inc;
if (dev->allmulti == 0) {
/*
* Avoid overflow.
* If inc causes overflow, untouch allmulti and return error.
*/
if (inc < 0)
dev->flags &= ~IFF_ALLMULTI;
else {
dev->allmulti -= inc;
printk(KERN_WARNING "%s: allmulti touches roof, "
"set allmulti failed, allmulti feature of "
"device might be broken.\n", dev->name);
return -EOVERFLOW;
}
}
if (dev->flags ^ old_flags) {
if (dev->change_rx_flags)
dev->change_rx_flags(dev, IFF_ALLMULTI);
dev_set_rx_mode(dev);
}
return 0;
}
/*