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netfilter: ctnetlink: allocate right-sized ctnetlink skb

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Try to allocate a Netlink skb roughly the size of the actual
message, with the help from the l3 and l4 protocol helpers.
This is all to prevent a reallocation in netlink_trim() later.

The overhead of allocating the right-sized skb is rather small, with
ctnetlink_alloc_skb() actually being inlined away on my x86_64 box.
The size of the per-proto space is determined at registration time of
the protocol helper.

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Holger Eitzenberger 2009-03-25 21:50:59 +01:00 • committed by Patrick McHardy
parent ea781f197d
commit 2732c4e45b
1 changed files with 64 additions and 1 deletions
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65
net/netfilter/nf_conntrack_netlink.c
View file

@ -405,6 +405,69 @@ nla_put_failure:
}
#ifdef CONFIG_NF_CONNTRACK_EVENTS
/*
* The general structure of a ctnetlink event is
*
* CTA_TUPLE_ORIG
* <l3/l4-proto-attributes>
* CTA_TUPLE_REPLY
* <l3/l4-proto-attributes>
* CTA_ID
* ...
* CTA_PROTOINFO
* <l4-proto-attributes>
* CTA_TUPLE_MASTER
* <l3/l4-proto-attributes>
*
* Therefore the formular is
*
* size = sizeof(headers) + sizeof(generic_nlas) + 3 * sizeof(tuple_nlas)
* + sizeof(protoinfo_nlas)
*/
static struct sk_buff *
ctnetlink_alloc_skb(const struct nf_conntrack_tuple *tuple, gfp_t gfp)
{
struct nf_conntrack_l3proto *l3proto;
struct nf_conntrack_l4proto *l4proto;
int len;
#define NLA_TYPE_SIZE(type) nla_total_size(sizeof(type))
/* proto independant part */
len = NLMSG_SPACE(sizeof(struct nfgenmsg))
+ 3 * nla_total_size(0) /* CTA_TUPLE_ORIG|REPL|MASTER */
+ 3 * nla_total_size(0) /* CTA_TUPLE_IP */
+ 3 * nla_total_size(0) /* CTA_TUPLE_PROTO */
+ 3 * NLA_TYPE_SIZE(u_int8_t) /* CTA_PROTO_NUM */
+ NLA_TYPE_SIZE(u_int32_t) /* CTA_ID */
+ NLA_TYPE_SIZE(u_int32_t) /* CTA_STATUS */
+ 2 * nla_total_size(0) /* CTA_COUNTERS_ORIG|REPL */
+ 2 * NLA_TYPE_SIZE(uint64_t) /* CTA_COUNTERS_PACKETS */
+ 2 * NLA_TYPE_SIZE(uint64_t) /* CTA_COUNTERS_BYTES */
+ NLA_TYPE_SIZE(u_int32_t) /* CTA_TIMEOUT */
+ nla_total_size(0) /* CTA_PROTOINFO */
+ nla_total_size(0) /* CTA_HELP */
+ nla_total_size(NF_CT_HELPER_NAME_LEN) /* CTA_HELP_NAME */
+ NLA_TYPE_SIZE(u_int32_t) /* CTA_SECMARK */
+ 2 * nla_total_size(0) /* CTA_NAT_SEQ_ADJ_ORIG|REPL */
+ 2 * NLA_TYPE_SIZE(u_int32_t) /* CTA_NAT_SEQ_CORRECTION_POS */
+ 2 * NLA_TYPE_SIZE(u_int32_t) /* CTA_NAT_SEQ_CORRECTION_BEFORE */
+ 2 * NLA_TYPE_SIZE(u_int32_t) /* CTA_NAT_SEQ_CORRECTION_AFTER */
+ NLA_TYPE_SIZE(u_int32_t); /* CTA_MARK */
#undef NLA_TYPE_SIZE
rcu_read_lock();
l3proto = __nf_ct_l3proto_find(tuple->src.l3num);
len += l3proto->nla_size;
l4proto = __nf_ct_l4proto_find(tuple->src.l3num, tuple->dst.protonum);
len += l4proto->nla_size;
rcu_read_unlock();
return alloc_skb(len, gfp);
}
static int ctnetlink_conntrack_event(struct notifier_block *this,
unsigned long events, void *ptr)
{
@ -438,7 +501,7 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
if (!item->report && !nfnetlink_has_listeners(group))
return NOTIFY_DONE;
skb = alloc_skb(NLMSG_GOODSIZE, GFP_ATOMIC);
skb = ctnetlink_alloc_skb(tuple(ct, IP_CT_DIR_ORIGINAL), GFP_ATOMIC);
if (!skb)
return NOTIFY_DONE;