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net: write once on dev->allmulti and dev->promiscuity

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In the following patch we want to read dev->allmulti
and dev->promiscuity locklessly from rtnl_fill_ifinfo()

In this patch I change __dev_set_promiscuity() and
__dev_set_allmulti() to write these fields (and dev->flags)
only if they succeed, with WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Eric Dumazet 2024-05-03 19:20:55 +00:00 committed by Paolo Abeni
parent ad13b5b0d1
commit 55a2c86c8d
1 changed files with 20 additions and 16 deletions
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36
net/core/dev.c
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@ -8544,27 +8544,29 @@ static void dev_change_rx_flags(struct net_device *dev, int flags)
static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
{
unsigned int old_flags = dev->flags;
unsigned int promiscuity, flags;
kuid_t uid;
kgid_t gid;
ASSERT_RTNL();
dev->flags |= IFF_PROMISC;
dev->promiscuity += inc;
if (dev->promiscuity == 0) {
promiscuity = dev->promiscuity + inc;
if (promiscuity == 0) {
/*
* Avoid overflow.
* If inc causes overflow, untouch promisc and return error.
*/
if (inc < 0)
dev->flags &= ~IFF_PROMISC;
else {
dev->promiscuity -= inc;
if (unlikely(inc > 0)) {
netdev_warn(dev, "promiscuity touches roof, set promiscuity failed. promiscuity feature of device might be broken.\n");
return -EOVERFLOW;
}
flags = old_flags & ~IFF_PROMISC;
} else {
flags = old_flags | IFF_PROMISC;
}
if (dev->flags != old_flags) {
WRITE_ONCE(dev->promiscuity, promiscuity);
if (flags != old_flags) {
WRITE_ONCE(dev->flags, flags);
netdev_info(dev, "%s promiscuous mode\n",
dev->flags & IFF_PROMISC ? "entered" : "left");
if (audit_enabled) {
@ -8615,25 +8617,27 @@ EXPORT_SYMBOL(dev_set_promiscuity);
static int __dev_set_allmulti(struct net_device *dev, int inc, bool notify)
{
unsigned int old_flags = dev->flags, old_gflags = dev->gflags;
unsigned int allmulti, flags;
ASSERT_RTNL();
dev->flags |= IFF_ALLMULTI;
dev->allmulti += inc;
if (dev->allmulti == 0) {
allmulti = dev->allmulti + inc;
if (allmulti == 0) {
/*
* Avoid overflow.
* If inc causes overflow, untouch allmulti and return error.
*/
if (inc < 0)
dev->flags &= ~IFF_ALLMULTI;
else {
dev->allmulti -= inc;
if (unlikely(inc > 0)) {
netdev_warn(dev, "allmulti touches roof, set allmulti failed. allmulti feature of device might be broken.\n");
return -EOVERFLOW;
}
flags = old_flags & ~IFF_ALLMULTI;
} else {
flags = old_flags | IFF_ALLMULTI;
}
if (dev->flags ^ old_flags) {
WRITE_ONCE(dev->allmulti, allmulti);
if (flags != old_flags) {
WRITE_ONCE(dev->flags, flags);
netdev_info(dev, "%s allmulticast mode\n",
dev->flags & IFF_ALLMULTI ? "entered" : "left");
dev_change_rx_flags(dev, IFF_ALLMULTI);