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netfilter: labels: don't emit ct event if labels were not changed

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make the replace function only send a ctnetlink event if the contents
of the new set is different.

Otherwise 'ct label set ct label | bar'

will cause netlink event storm since we "replace" labels for each packet.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2016-04-12 18:14:24 +02:00 committed by Pablo Neira Ayuso
parent b4ef159927
commit 5a8145f7b2
1 changed files with 10 additions and 6 deletions
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16
net/netfilter/nf_conntrack_labels.c
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@ -33,14 +33,18 @@ int nf_connlabel_set(struct nf_conn *ct, u16 bit)
}
EXPORT_SYMBOL_GPL(nf_connlabel_set);
static void replace_u32(u32 *address, u32 mask, u32 new)
static int replace_u32(u32 *address, u32 mask, u32 new)
{
u32 old, tmp;
do {
old = *address;
tmp = (old & mask) ^ new;
if (old == tmp)
return 0;
} while (cmpxchg(address, old, tmp) != old);
return 1;
}
int nf_connlabels_replace(struct nf_conn *ct,
@ -49,6 +53,7 @@ int nf_connlabels_replace(struct nf_conn *ct,
{
struct nf_conn_labels *labels;
unsigned int size, i;
int changed = 0;
u32 *dst;
labels = nf_ct_labels_find(ct);
@ -60,16 +65,15 @@ int nf_connlabels_replace(struct nf_conn *ct,
words32 = size / sizeof(u32);
dst = (u32 *) labels->bits;
if (words32) {
for (i = 0; i < words32; i++)
replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
}
for (i = 0; i < words32; i++)
changed |= replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
size /= sizeof(u32);
for (i = words32; i < size; i++) /* pad */
replace_u32(&dst[i], 0, 0);
nf_conntrack_event_cache(IPCT_LABEL, ct);
if (changed)
nf_conntrack_event_cache(IPCT_LABEL, ct);
return 0;
}
EXPORT_SYMBOL_GPL(nf_connlabels_replace);