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netfilter: conntrack: remove prealloc support

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It was used by the nat extension, but since commit
7c96643519 ("netfilter: move nat hlist_head to nf_conn") its only needed
for connections that use MASQUERADE target or a nat helper.

Also it seems a lot easier to preallocate a fixed size instead.

With default settings, conntrack first adds ecache extension (sysctl
defaults to 1), so we get 40(ct extension header) + 24 (ecache) == 64 byte
on x86_64 for initial allocation.

Followup patches can constify the extension structs and avoid
the initial zeroing of the entire extension area.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2017-04-20 09:54:22 +02:00 committed by Pablo Neira Ayuso
parent 495dcb56d0
commit 54044b1f02
3 changed files with 4 additions and 52 deletions
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6
include/net/netfilter/nf_conntrack_extend.h
View File

@ -88,21 +88,15 @@ static inline void nf_ct_ext_free(struct nf_conn *ct)
/* Add this type, returns pointer to data or NULL. */
void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp);
#define NF_CT_EXT_F_PREALLOC 0x0001
struct nf_ct_ext_type {
/* Destroys relationships (can be NULL). */
void (*destroy)(struct nf_conn *ct);
enum nf_ct_ext_id id;
unsigned int flags;
/* Length and min alignment. */
u8 len;
u8 align;
/* initial size of nf_ct_ext. */
u8 alloc_size;
};
int nf_ct_extend_register(struct nf_ct_ext_type *type);

49
net/netfilter/nf_conntrack_extend.c
View File

@ -18,6 +18,7 @@
static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM];
static DEFINE_MUTEX(nf_ct_ext_type_mutex);
#define NF_CT_EXT_PREALLOC 128u /* conntrack events are on by default */
void __nf_ct_ext_destroy(struct nf_conn *ct)
{
@ -46,9 +47,8 @@ EXPORT_SYMBOL(__nf_ct_ext_destroy);
static void *
nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp)
{
unsigned int off, len;
unsigned int off, len, alloc;
struct nf_ct_ext_type *t;
size_t alloc_size;
rcu_read_lock();
t = rcu_dereference(nf_ct_ext_types[id]);
@ -59,10 +59,10 @@ nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp)
off = ALIGN(sizeof(struct nf_ct_ext), t->align);
len = off + t->len;
alloc_size = t->alloc_size;
rcu_read_unlock();
*ext = kzalloc(alloc_size, gfp);
alloc = max(len, NF_CT_EXT_PREALLOC);
*ext = kzalloc(alloc, gfp);
if (!*ext)
return NULL;
@ -115,41 +115,6 @@ void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
}
EXPORT_SYMBOL(nf_ct_ext_add);
static void update_alloc_size(struct nf_ct_ext_type *type)
{
int i, j;
struct nf_ct_ext_type *t1, *t2;
enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1;
/* unnecessary to update all types */
if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) {
min = type->id;
max = type->id;
}
/* This assumes that extended areas in conntrack for the types
whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */
for (i = min; i <= max; i++) {
t1 = rcu_dereference_protected(nf_ct_ext_types[i],
lockdep_is_held(&nf_ct_ext_type_mutex));
if (!t1)
continue;
t1->alloc_size = ALIGN(sizeof(struct nf_ct_ext), t1->align) +
t1->len;
for (j = 0; j < NF_CT_EXT_NUM; j++) {
t2 = rcu_dereference_protected(nf_ct_ext_types[j],
lockdep_is_held(&nf_ct_ext_type_mutex));
if (t2 == NULL || t2 == t1 ||
(t2->flags & NF_CT_EXT_F_PREALLOC) == 0)
continue;
t1->alloc_size = ALIGN(t1->alloc_size, t2->align)
+ t2->len;
}
}
}
/* This MUST be called in process context. */
int nf_ct_extend_register(struct nf_ct_ext_type *type)
{
@ -161,12 +126,7 @@ int nf_ct_extend_register(struct nf_ct_ext_type *type)
goto out;
}
/* This ensures that nf_ct_ext_create() can allocate enough area
before updating alloc_size */
type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align)
+ type->len;
rcu_assign_pointer(nf_ct_ext_types[type->id], type);
update_alloc_size(type);
out:
mutex_unlock(&nf_ct_ext_type_mutex);
return ret;
@ -178,7 +138,6 @@ void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
{
mutex_lock(&nf_ct_ext_type_mutex);
RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL);
update_alloc_size(type);
mutex_unlock(&nf_ct_ext_type_mutex);
synchronize_rcu();
}

1
net/netfilter/nf_nat_core.c
View File

@ -717,7 +717,6 @@ static struct nf_ct_ext_type nat_extend __read_mostly = {
.align = __alignof__(struct nf_conn_nat),
.destroy = nf_nat_cleanup_conntrack,
.id = NF_CT_EXT_NAT,
.flags = NF_CT_EXT_F_PREALLOC,
};
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)