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netfilter: nf_conntrack: support conntrack templates 

Support initializing selected parameters of new conntrack entries from a
"conntrack template", which is a specially marked conntrack entry attached
to the skb.

Currently the helper and the event delivery masks can be initialized this
way.

Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Patrick McHardy 2010-02-03 14:13:03 +01:00
parent 0cebe4b416
commit b2a15a604d
8 changed files with 61 additions and 24 deletions
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4
include/linux/netfilter/nf_conntrack_common.h
View File

@ -72,6 +72,10 @@ enum ip_conntrack_status {
/* Connection has fixed timeout. */
IPS_FIXED_TIMEOUT_BIT = 10,
IPS_FIXED_TIMEOUT = (1 << IPS_FIXED_TIMEOUT_BIT),
/* Conntrack is a template */
IPS_TEMPLATE_BIT = 11,
IPS_TEMPLATE = (1 << IPS_TEMPLATE_BIT),
};
/* Connection tracking event types */

5
include/net/netfilter/nf_conntrack.h
View File

@ -272,6 +272,11 @@ nf_conntrack_alloc(struct net *net,
const struct nf_conntrack_tuple *repl,
gfp_t gfp);
static inline int nf_ct_is_template(const struct nf_conn *ct)
{
return test_bit(IPS_TEMPLATE_BIT, &ct->status);
}
/* It's confirmed if it is, or has been in the hash table. */
static inline int nf_ct_is_confirmed(struct nf_conn *ct)
{

3
include/net/netfilter/nf_conntrack_helper.h
View File

@ -47,7 +47,8 @@ extern void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
extern struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
extern int __nf_ct_try_assign_helper(struct nf_conn *ct, gfp_t flags);
extern int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
gfp_t flags);
extern void nf_ct_helper_destroy(struct nf_conn *ct);

2
net/ipv4/netfilter/nf_defrag_ipv4.c
View File

@ -59,7 +59,7 @@ static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
#if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE)
/* Previously seen (loopback)? Ignore. Do this before
fragment check. */
if (skb->nfct)
if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
return NF_ACCEPT;
#endif
#endif

2
net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
View File

@ -212,7 +212,7 @@ static unsigned int ipv6_defrag(unsigned int hooknum,
struct sk_buff *reasm;
/* Previously seen (loopback)? */
if (skb->nfct)
if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
return NF_ACCEPT;
reasm = nf_ct_frag6_gather(skb, nf_ct6_defrag_user(hooknum, skb));

50
net/netfilter/nf_conntrack_core.c
View File

@ -618,7 +618,7 @@ EXPORT_SYMBOL_GPL(nf_conntrack_free);
/* Allocate a new conntrack: we return -ENOMEM if classification
failed due to stress. Otherwise it really is unclassifiable. */
static struct nf_conntrack_tuple_hash *
init_conntrack(struct net *net,
init_conntrack(struct net *net, struct nf_conn *tmpl,
const struct nf_conntrack_tuple *tuple,
struct nf_conntrack_l3proto *l3proto,
struct nf_conntrack_l4proto *l4proto,
@ -628,6 +628,7 @@ init_conntrack(struct net *net,
struct nf_conn *ct;
struct nf_conn_help *help;
struct nf_conntrack_tuple repl_tuple;
struct nf_conntrack_ecache *ecache;
struct nf_conntrack_expect *exp;
if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) {
@ -648,7 +649,11 @@ init_conntrack(struct net *net,
}
nf_ct_acct_ext_add(ct, GFP_ATOMIC);
nf_ct_ecache_ext_add(ct, 0, 0, GFP_ATOMIC);
ecache = tmpl ? nf_ct_ecache_find(tmpl) : NULL;
nf_ct_ecache_ext_add(ct, ecache ? ecache->ctmask : 0,
ecache ? ecache->expmask : 0,
GFP_ATOMIC);
spin_lock_bh(&nf_conntrack_lock);
exp = nf_ct_find_expectation(net, tuple);
@ -673,7 +678,7 @@ init_conntrack(struct net *net,
nf_conntrack_get(&ct->master->ct_general);
NF_CT_STAT_INC(net, expect_new);
} else {
__nf_ct_try_assign_helper(ct, GFP_ATOMIC);
__nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC);
NF_CT_STAT_INC(net, new);
}
@ -694,7 +699,7 @@ init_conntrack(struct net *net,
/* On success, returns conntrack ptr, sets skb->nfct and ctinfo */
static inline struct nf_conn *
resolve_normal_ct(struct net *net,
resolve_normal_ct(struct net *net, struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
u_int16_t l3num,
@ -718,7 +723,8 @@ resolve_normal_ct(struct net *net,
/* look for tuple match */
h = nf_conntrack_find_get(net, &tuple);
if (!h) {
h = init_conntrack(net, &tuple, l3proto, l4proto, skb, dataoff);
h = init_conntrack(net, tmpl, &tuple, l3proto, l4proto,
skb, dataoff);
if (!h)
return NULL;
if (IS_ERR(h))
@ -755,7 +761,7 @@ unsigned int
nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,
struct sk_buff *skb)
{
struct nf_conn *ct;
struct nf_conn *ct, *tmpl = NULL;
enum ip_conntrack_info ctinfo;
struct nf_conntrack_l3proto *l3proto;
struct nf_conntrack_l4proto *l4proto;
@ -764,10 +770,14 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,
int set_reply = 0;
int ret;
/* Previously seen (loopback or untracked)? Ignore. */
if (skb->nfct) {
NF_CT_STAT_INC_ATOMIC(net, ignore);
return NF_ACCEPT;
/* Previously seen (loopback or untracked)? Ignore. */
tmpl = (struct nf_conn *)skb->nfct;
if (!nf_ct_is_template(tmpl)) {
NF_CT_STAT_INC_ATOMIC(net, ignore);
return NF_ACCEPT;
}
skb->nfct = NULL;
}
/* rcu_read_lock()ed by nf_hook_slow */
@ -778,7 +788,8 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,
pr_debug("not prepared to track yet or error occured\n");
NF_CT_STAT_INC_ATOMIC(net, error);
NF_CT_STAT_INC_ATOMIC(net, invalid);
return -ret;
ret = -ret;
goto out;
}
l4proto = __nf_ct_l4proto_find(pf, protonum);
@ -791,22 +802,25 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,
if (ret <= 0) {
NF_CT_STAT_INC_ATOMIC(net, error);
NF_CT_STAT_INC_ATOMIC(net, invalid);
return -ret;
ret = -ret;
goto out;
}
}
ct = resolve_normal_ct(net, skb, dataoff, pf, protonum,
ct = resolve_normal_ct(net, tmpl, skb, dataoff, pf, protonum,
l3proto, l4proto, &set_reply, &ctinfo);
if (!ct) {
/* Not valid part of a connection */
NF_CT_STAT_INC_ATOMIC(net, invalid);
return NF_ACCEPT;
ret = NF_ACCEPT;
goto out;
}
if (IS_ERR(ct)) {
/* Too stressed to deal. */
NF_CT_STAT_INC_ATOMIC(net, drop);
return NF_DROP;
ret = NF_DROP;
goto out;
}
NF_CT_ASSERT(skb->nfct);
@ -821,11 +835,15 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum,
NF_CT_STAT_INC_ATOMIC(net, invalid);
if (ret == -NF_DROP)
NF_CT_STAT_INC_ATOMIC(net, drop);
return -ret;
ret = -ret;
goto out;
}
if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
nf_conntrack_event_cache(IPCT_REPLY, ct);
out:
if (tmpl)
nf_ct_put(tmpl);
return ret;
}
@ -864,7 +882,7 @@ void nf_conntrack_alter_reply(struct nf_conn *ct,
return;
rcu_read_lock();
__nf_ct_try_assign_helper(ct, GFP_ATOMIC);
__nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC);
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);

17
net/netfilter/nf_conntrack_helper.c
View File

@ -96,13 +96,22 @@ struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
}
EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
int __nf_ct_try_assign_helper(struct nf_conn *ct, gfp_t flags)
int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
gfp_t flags)
{
struct nf_conntrack_helper *helper = NULL;
struct nf_conn_help *help;
int ret = 0;
struct nf_conntrack_helper *helper;
struct nf_conn_help *help = nfct_help(ct);
helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
if (tmpl != NULL) {
help = nfct_help(tmpl);
if (help != NULL)
helper = help->helper;
}
help = nfct_help(ct);
if (helper == NULL)
helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
if (helper == NULL) {
if (help)
rcu_assign_pointer(help->helper, NULL);

2
net/netfilter/nf_conntrack_netlink.c
View File

@ -1249,7 +1249,7 @@ ctnetlink_create_conntrack(struct net *net,
}
} else {
/* try an implicit helper assignation */
err = __nf_ct_try_assign_helper(ct, GFP_ATOMIC);
err = __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC);
if (err < 0)
goto err2;
}