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netfilter: conntrack: switch connlabels to atomic_t

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The spinlock is back from the day when connabels did not have
a fixed size and reallocation had to be supported.

Remove it.  This change also allows to call the helpers from
softirq or timers without deadlocks.

Also add WARN()s to catch refcounting imbalances.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2023-10-20 14:38:15 +02:00 committed by Pablo Neira Ayuso
parent ee6f05dcd6
commit 643d126036
3 changed files with 10 additions and 11 deletions
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2
include/net/netfilter/nf_conntrack_labels.h
View file

@ -39,7 +39,7 @@ static inline struct nf_conn_labels *nf_ct_labels_ext_add(struct nf_conn *ct)
#ifdef CONFIG_NF_CONNTRACK_LABELS
struct net *net = nf_ct_net(ct);
if (net->ct.labels_used == 0)
if (atomic_read(&net->ct.labels_used) == 0)
return NULL;
return nf_ct_ext_add(ct, NF_CT_EXT_LABELS, GFP_ATOMIC);

2
include/net/netns/conntrack.h
View file

@ -107,7 +107,7 @@ struct netns_ct {
struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb;
struct nf_ip_net nf_ct_proto;
#if defined(CONFIG_NF_CONNTRACK_LABELS)
unsigned int labels_used;
atomic_t labels_used;
#endif
};
#endif

17
net/netfilter/nf_conntrack_labels.c
View file

@ -11,8 +11,6 @@
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_labels.h>
static DEFINE_SPINLOCK(nf_connlabels_lock);
static int replace_u32(u32 *address, u32 mask, u32 new)
{
u32 old, tmp;
@ -60,23 +58,24 @@ EXPORT_SYMBOL_GPL(nf_connlabels_replace);
int nf_connlabels_get(struct net *net, unsigned int bits)
{
int v;
if (BIT_WORD(bits) >= NF_CT_LABELS_MAX_SIZE / sizeof(long))
return -ERANGE;
spin_lock(&nf_connlabels_lock);
net->ct.labels_used++;
spin_unlock(&nf_connlabels_lock);
BUILD_BUG_ON(NF_CT_LABELS_MAX_SIZE / sizeof(long) >= U8_MAX);
v = atomic_inc_return_relaxed(&net->ct.labels_used);
WARN_ON_ONCE(v <= 0);
return 0;
}
EXPORT_SYMBOL_GPL(nf_connlabels_get);
void nf_connlabels_put(struct net *net)
{
spin_lock(&nf_connlabels_lock);
net->ct.labels_used--;
spin_unlock(&nf_connlabels_lock);
int v = atomic_dec_return_relaxed(&net->ct.labels_used);
WARN_ON_ONCE(v < 0);
}
EXPORT_SYMBOL_GPL(nf_connlabels_put);