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netfilter: nf_conntrack: extend with extra stat counter

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I suspect an unfortunatly series of events occuring under a DDoS
attack, in function __nf_conntrack_find() nf_contrack_core.c.

Adding a stats counter to see if the search is restarted too often.

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Jesper Dangaard Brouer 2010-04-23 12:34:56 +02:00 committed by Patrick McHardy
parent cecc74de25
commit af740b2c8f
4 changed files with 12 additions and 7 deletions
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1
include/linux/netfilter/nf_conntrack_common.h
View File

@ -113,6 +113,7 @@ struct ip_conntrack_stat {
unsigned int expect_new;
unsigned int expect_create;
unsigned int expect_delete;
unsigned int search_restart;
};
/* call to create an explicit dependency on nf_conntrack. */

7
net/ipv4/netfilter/nf_conntrack_l3proto_ipv4_compat.c
View File

@ -336,12 +336,12 @@ static int ct_cpu_seq_show(struct seq_file *seq, void *v)
const struct ip_conntrack_stat *st = v;
if (v == SEQ_START_TOKEN) {
seq_printf(seq, "entries searched found new invalid ignore delete delete_list insert insert_failed drop early_drop icmp_error expect_new expect_create expect_delete\n");
seq_printf(seq, "entries searched found new invalid ignore delete delete_list insert insert_failed drop early_drop icmp_error expect_new expect_create expect_delete search_restart\n");
return 0;
}
seq_printf(seq, "%08x %08x %08x %08x %08x %08x %08x %08x "
"%08x %08x %08x %08x %08x %08x %08x %08x \n",
"%08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
nr_conntracks,
st->searched,
st->found,
@ -358,7 +358,8 @@ static int ct_cpu_seq_show(struct seq_file *seq, void *v)
st->expect_new,
st->expect_create,
st->expect_delete
st->expect_delete,
st->search_restart
);
return 0;
}

4
net/netfilter/nf_conntrack_core.c
View File

@ -319,8 +319,10 @@ __nf_conntrack_find(struct net *net, u16 zone,
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (get_nulls_value(n) != hash)
if (get_nulls_value(n) != hash) {
NF_CT_STAT_INC(net, search_restart);
goto begin;
}
local_bh_enable();
return NULL;

7
net/netfilter/nf_conntrack_standalone.c
View File

@ -252,12 +252,12 @@ static int ct_cpu_seq_show(struct seq_file *seq, void *v)
const struct ip_conntrack_stat *st = v;
if (v == SEQ_START_TOKEN) {
seq_printf(seq, "entries searched found new invalid ignore delete delete_list insert insert_failed drop early_drop icmp_error expect_new expect_create expect_delete\n");
seq_printf(seq, "entries searched found new invalid ignore delete delete_list insert insert_failed drop early_drop icmp_error expect_new expect_create expect_delete search_restart\n");
return 0;
}
seq_printf(seq, "%08x %08x %08x %08x %08x %08x %08x %08x "
"%08x %08x %08x %08x %08x %08x %08x %08x \n",
"%08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
nr_conntracks,
st->searched,
st->found,
@ -274,7 +274,8 @@ static int ct_cpu_seq_show(struct seq_file *seq, void *v)
st->expect_new,
st->expect_create,
st->expect_delete
st->expect_delete,
st->search_restart
);
return 0;
}