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SubjectRe: [PATCH] netfilter: conntrack: add weak IPV6 dependency
Florian Westphal <fw@strlen.de> wrote:
> Arnd Bergmann <arnd@arndb.de> wrote:
> > and that resulted in a new build failure:
> >
> > net/netfilter/nf_conntrack_proto.o:(.rodata+0x788): undefined
> > reference to `nf_conntrack_l4proto_icmpv6'
> > net/ipv6/netfilter/nf_conntrack_reasm.o: In function `nf_ct_frag6_expire':
> > nf_conntrack_reasm.c:(.text+0x2320): undefined reference to
> > `ip6_expire_frag_queue'
> > net/ipv6/netfilter/nf_conntrack_reasm.o: In function `nf_ct_frag6_init':
> > nf_conntrack_reasm.c:(.text+0x2384): undefined reference to `ip6_frag_init'
> > nf_conntrack_reasm.c:(.text+0x2394): undefined reference to `ip6_frag_init'
> > nf_conntrack_reasm.c:(.text+0x2398): undefined reference to `ip6_rhash_params'
> > net/ipv6/netfilter/nf_conntrack_reasm.o: In function `nf_ct_frag6_expire':
> > nf_conntrack_reasm.c:(.text+0x10bc): undefined reference to
> > `ip6_expire_frag_queue'
> >
> > I don't think we can get CONFIG_NF_DEFRAG_IPV6=y to work with IPV6=m.
>
> Yes, not with current implementation, but I still don't think this
> is unavoidable.
>
> In case this is urgent I'm fine with the patch that adds the dependency,
> otherwise I'd like to try and disentangle nf_conntrack_reasm and ipv6.

This links fine for me with IPV6=m:

Pablo, do you think this is too ugly?
It requires some copypastry from ipv6 defrag into nfct ipv6 defrag
to avoid the link errors outlined above.

Rest of defrag uses generic inet_defrag routines.

diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
index 07516d5c2f80..339d0762b027 100644
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -5,10 +5,6 @@
menu "IPv6: Netfilter Configuration"
depends on INET && IPV6 && NETFILTER

-config NF_DEFRAG_IPV6
- tristate
- default n
-
config NF_SOCKET_IPV6
tristate "IPv6 socket lookup support"
help
@@ -349,6 +345,7 @@ config IP6_NF_TARGET_NPT
endif # IP6_NF_NAT

endif # IP6_NF_IPTABLES
-
endmenu

+config NF_DEFRAG_IPV6
+ tristate
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c
index 5e0332014c17..9973aadc6b71 100644
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -142,6 +142,50 @@ static inline u8 ip6_frag_ecn(const struct ipv6hdr *ipv6h)
return 1 << (ipv6_get_dsfield(ipv6h) & INET_ECN_MASK);
}

+static void nfct_expire_frag_queue(struct net *net, struct frag_queue *fq)
+{
+ struct net_device *dev = NULL;
+ struct sk_buff *head;
+
+ rcu_read_lock();
+ spin_lock(&fq->q.lock);
+
+ if (fq->q.flags & INET_FRAG_COMPLETE)
+ goto out;
+
+ inet_frag_kill(&fq->q);
+
+ dev = dev_get_by_index_rcu(net, fq->iif);
+ if (!dev)
+ goto out;
+
+ __IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
+ __IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);
+
+ /* Don't send error if the first segment did not arrive. */
+ head = fq->q.fragments;
+ if (!(fq->q.flags & INET_FRAG_FIRST_IN) || !head)
+ goto out;
+
+ /* But use as source device on which LAST ARRIVED
+ * segment was received. And do not use fq->dev
+ * pointer directly, device might already disappeared.
+ */
+ head->dev = dev;
+ skb_get(head);
+ spin_unlock(&fq->q.lock);
+
+ icmpv6_send(head, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0);
+ kfree_skb(head);
+ goto out_rcu_unlock;
+
+out:
+ spin_unlock(&fq->q.lock);
+out_rcu_unlock:
+ rcu_read_unlock();
+ inet_frag_put(&fq->q);
+}
+
static void nf_ct_frag6_expire(struct timer_list *t)
{
struct inet_frag_queue *frag = from_timer(frag, t, timer);
@@ -151,7 +195,7 @@ static void nf_ct_frag6_expire(struct timer_list *t)
fq = container_of(frag, struct frag_queue, q);
net = container_of(fq->q.net, struct net, nf_frag.frags);

- ip6_expire_frag_queue(net, fq);
+ nfct_expire_frag_queue(net, fq);
}

/* Creation primitives. */
@@ -622,16 +666,55 @@ static struct pernet_operations nf_ct_net_ops = {
.exit = nf_ct_net_exit,
};

+static u32 ip6_key_hashfn(const void *data, u32 len, u32 seed)
+{
+ return jhash2(data,
+ sizeof(struct frag_v6_compare_key) / sizeof(u32), seed);
+}
+
+static u32 ip6_obj_hashfn(const void *data, u32 len, u32 seed)
+{
+ const struct inet_frag_queue *fq = data;
+
+ return jhash2((const u32 *)&fq->key.v6,
+ sizeof(struct frag_v6_compare_key) / sizeof(u32), seed);
+}
+
+static int ip6_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
+{
+ const struct frag_v6_compare_key *key = arg->key;
+ const struct inet_frag_queue *fq = ptr;
+
+ return !!memcmp(&fq->key, key, sizeof(*key));
+}
+
+static const struct rhashtable_params nfct_rhash_params = {
+ .head_offset = offsetof(struct inet_frag_queue, node),
+ .hashfn = ip6_key_hashfn,
+ .obj_hashfn = ip6_obj_hashfn,
+ .obj_cmpfn = ip6_obj_cmpfn,
+ .automatic_shrinking = true,
+};
+
+static void nfct_frag_init(struct inet_frag_queue *q, const void *a)
+{
+ struct frag_queue *fq = container_of(q, struct frag_queue, q);
+ const struct frag_v6_compare_key *key = a;
+
+ q->key.v6 = *key;
+ fq->ecn = 0;
+}
+
int nf_ct_frag6_init(void)
{
int ret = 0;

- nf_frags.constructor = ip6_frag_init;
+ nf_frags.constructor = nfct_frag_init;
nf_frags.destructor = NULL;
nf_frags.qsize = sizeof(struct frag_queue);
nf_frags.frag_expire = nf_ct_frag6_expire;
nf_frags.frags_cache_name = nf_frags_cache_name;
- nf_frags.rhash_params = ip6_rhash_params;
+ nf_frags.rhash_params = nfct_rhash_params;
ret = inet_frags_init(&nf_frags);
if (ret)
goto out;
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 6c65d756e603..e0ab50c58dc4 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -50,7 +50,7 @@ config NF_CONNTRACK
tristate "Netfilter connection tracking support"
default m if NETFILTER_ADVANCED=n
select NF_DEFRAG_IPV4
- select NF_DEFRAG_IPV6 if IPV6
+ select NF_DEFRAG_IPV6 if IPV6 != n
help
Connection tracking keeps a record of what packets have passed
through your machine, in order to figure out how they are related
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 0b3851e825fa..53bd1ed1228a 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -6,7 +6,7 @@ nf_conntrack-y := nf_conntrack_core.o nf_conntrack_standalone.o nf_conntrack_exp
nf_conntrack_proto_icmp.o \
nf_conntrack_extend.o nf_conntrack_acct.o nf_conntrack_seqadj.o

-nf_conntrack-$(CONFIG_IPV6) += nf_conntrack_proto_icmpv6.o
+nf_conntrack-$(subst m,y,$(CONFIG_IPV6)) += nf_conntrack_proto_icmpv6.o
nf_conntrack-$(CONFIG_NF_CONNTRACK_TIMEOUT) += nf_conntrack_timeout.o
nf_conntrack-$(CONFIG_NF_CONNTRACK_TIMESTAMP) += nf_conntrack_timestamp.o
nf_conntrack-$(CONFIG_NF_CONNTRACK_EVENTS) += nf_conntrack_ecache.o
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