br_defrag() and br_fragment() indirections are added in case of IPv6 support
comes as a module, to avoid pulling innecessary dependencies in.
The new fraglist iterator and fragment transformer APIs is used to
implement the refragmentation code.
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/linux/netfilter_ipv6.h | 50 ++++++++++++
net/bridge/netfilter/nf_conntrack_bridge.c | 59 +++++++++++++-
net/ipv6/netfilter.c | 123 +++++++++++++++++++++++++++++
3 files changed, 230 insertions(+), 2 deletions(-)
diff --git a/include/linux/netfilter_ipv6.h b/include/linux/netfilter_ipv6.h
index 12113e502656..a21b8c9623ee 100644
--- a/include/linux/netfilter_ipv6.h
+++ b/include/linux/netfilter_ipv6.h
@@ -19,6 +19,7 @@ struct ip6_rt_info {
};
struct nf_queue_entry;
+struct nf_ct_bridge_frag_data;
/*
* Hook functions for ipv6 to allow xt_* modules to be built-in even
@@ -39,6 +40,15 @@ struct nf_ipv6_ops {
int (*fragment)(struct net *net, struct sock *sk, struct sk_buff *skb,
int (*output)(struct net *, struct sock *, struct sk_buff *));
int (*reroute)(struct sk_buff *skb, const struct nf_queue_entry *entry);
+#if IS_MODULE(CONFIG_IPV6)
+ int (*br_defrag)(struct net *net, struct sk_buff *skb, u32 user);
+ int (*br_fragment)(struct net *net, struct sock *sk,
+ struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *));
+#endif
};
#ifdef CONFIG_NETFILTER
@@ -86,6 +96,46 @@ static inline int nf_ip6_route(struct net *net, struct dst_entry **dst,
#endif
}
+static inline int nf_ipv6_br_defrag(struct net *net, struct sk_buff *skb,
+ u32 user)
+{
+#if IS_MODULE(CONFIG_IPV6)
+ const struct nf_ipv6_ops *v6_ops = nf_get_ipv6_ops();
+
+ if (!v6_ops)
+ return 1;
+
+ return v6_ops->br_defrag(net, skb, user);
+#else
+ return nf_ct_frag6_gather(net, skb, user);
+#endif
+}
+
+int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *));
+
+static inline int nf_br_ip6_fragment(struct net *net, struct sock *sk,
+ struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *))
+{
+#if IS_MODULE(CONFIG_IPV6)
+ const struct nf_ipv6_ops *v6_ops = nf_get_ipv6_ops();
+
+ if (!v6_ops)
+ return 1;
+
+ return v6_ops->br_fragment(net, sk, skb, data, output);
+#else
+ return br_ip6_fragment(net, sk, skb, data, output);
+#endif
+}
+
int ip6_route_me_harder(struct net *net, struct sk_buff *skb);
static inline int nf_ip6_route_me_harder(struct net *net, struct sk_buff *skb)
diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
index 2571528ed582..b675cd7c1a82 100644
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -163,6 +163,31 @@ static unsigned int nf_ct_br_defrag4(struct sk_buff *skb,
return NF_STOLEN;
}
+static unsigned int nf_ct_br_defrag6(struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
+ enum ip_conntrack_info ctinfo;
+ struct br_input_skb_cb cb;
+ const struct nf_conn *ct;
+ int err;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct)
+ zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
+
+ br_skb_cb_save(skb, &cb, sizeof(struct inet6_skb_parm));
+
+ err = nf_ipv6_br_defrag(state->net, skb,
+ IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id);
+ /* queued */
+ if (err == -EINPROGRESS)
+ return NF_STOLEN;
+
+ br_skb_cb_restore(skb, &cb, IP6CB(skb)->frag_max_size);
+ return err == 0 ? NF_ACCEPT : NF_DROP;
+}
+
static int nf_ct_br_ip_check(const struct sk_buff *skb)
{
const struct iphdr *iph;
@@ -177,6 +202,23 @@ static int nf_ct_br_ip_check(const struct sk_buff *skb)
len = ntohs(iph->tot_len);
if (skb->len < nhoff + len ||
len < (iph->ihl * 4))
+ return -1;
+
+ return 0;
+}
+
+static int nf_ct_br_ipv6_check(const struct sk_buff *skb)
+{
+ const struct ipv6hdr *hdr;
+ int nhoff, len;
+
+ nhoff = skb_network_offset(skb);
+ hdr = ipv6_hdr(skb);
+ if (hdr->version != 6)
+ return -1;
+
+ len = ntohs(hdr->payload_len) + sizeof(struct ipv6hdr) + nhoff;
+ if (skb->len < len)
return -1;
return 0;
@@ -212,7 +254,19 @@ static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
ret = nf_ct_br_defrag4(skb, &bridge_state);
break;
case htons(ETH_P_IPV6):
- /* fall through */
+ if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
+ return NF_ACCEPT;
+
+ len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
+ if (pskb_trim_rcsum(skb, len))
+ return NF_ACCEPT;
+
+ if (nf_ct_br_ipv6_check(skb))
+ return NF_ACCEPT;
+
+ bridge_state.pf = NFPROTO_IPV6;
+ ret = nf_ct_br_defrag6(skb, &bridge_state);
+ break;
default:
nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
return NF_ACCEPT;
@@ -254,7 +308,8 @@ nf_ct_bridge_refrag(struct sk_buff *skb, const struct nf_hook_state *state,
nf_br_ip_fragment(state->net, state->sk, skb, &data, output);
break;
case htons(ETH_P_IPV6):
- return NF_ACCEPT;
+ nf_br_ip6_fragment(state->net, state->sk, skb, &data, output);
+ break;
default:
WARN_ON_ONCE(1);
return NF_DROP;
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 1240ccd57f39..c6665382acb5 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -16,6 +16,9 @@
#include <net/ip6_route.h>
#include <net/xfrm.h>
#include <net/netfilter/nf_queue.h>
+#include <net/netfilter/nf_conntrack_bridge.h>
+#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
+#include "../bridge/br_private.h"
int ip6_route_me_harder(struct net *net, struct sk_buff *skb)
{
@@ -109,6 +112,122 @@ int __nf_ip6_route(struct net *net, struct dst_entry **dst,
}
EXPORT_SYMBOL_GPL(__nf_ip6_route);
+int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+ struct nf_ct_bridge_frag_data *data,
+ int (*output)(struct net *, struct sock *sk,
+ const struct nf_ct_bridge_frag_data *data,
+ struct sk_buff *))
+{
+ int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
+ struct ip6_frag_state state;
+ u8 *prevhdr, nexthdr = 0;
+ unsigned int mtu, hlen;
+ int hroom, err = 0;
+ __be32 frag_id;
+
+ err = ip6_find_1stfragopt(skb, &prevhdr);
+ if (err < 0)
+ goto blackhole;
+ hlen = err;
+ nexthdr = *prevhdr;
+
+ mtu = skb->dev->mtu;
+ if (frag_max_size > mtu ||
+ frag_max_size < IPV6_MIN_MTU)
+ goto blackhole;
+
+ mtu = frag_max_size;
+ if (mtu < hlen + sizeof(struct frag_hdr) + 8)
+ goto blackhole;
+ mtu -= hlen + sizeof(struct frag_hdr);
+
+ frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
+ &ipv6_hdr(skb)->saddr);
+
+ if (skb->ip_summed == CHECKSUM_PARTIAL &&
+ (err = skb_checksum_help(skb)))
+ goto blackhole;
+
+ hroom = LL_RESERVED_SPACE(skb->dev);
+ if (skb_has_frag_list(skb)) {
+ unsigned int first_len = skb_pagelen(skb);
+ struct ip6_fraglist_iter iter;
+ struct sk_buff *frag2;
+
+ if (first_len - hlen > mtu ||
+ skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
+ goto blackhole;
+
+ if (skb_cloned(skb))
+ goto slow_path;
+
+ skb_walk_frags(skb, frag2) {
+ if (frag2->len > mtu ||
+ skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr)))
+ goto blackhole;
+
+ /* Partially cloned skb? */
+ if (skb_shared(frag2))
+ goto slow_path;
+ }
+
+ err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id,
+ &iter);
+ if (err < 0)
+ goto blackhole;
+
+ for (;;) {
+ /* Prepare header of the next frame,
+ * before previous one went down.
+ */
+ if (iter.frag)
+ ip6_fraglist_prepare(skb, &iter);
+
+ err = output(net, sk, data, skb);
+ if (err || !iter.frag)
+ break;
+
+ skb = ip6_fraglist_next(&iter);
+ }
+
+ kfree(iter.tmp_hdr);
+ if (!err)
+ return 0;
+
+ kfree_skb_list(iter.frag_list);
+ return err;
+ }
+slow_path:
+ /* This is a linearized skbuff, the original geometry is lost for us.
+ * This may also be a clone skbuff, we could preserve the geometry for
+ * the copies but probably not worth the effort.
+ */
+ ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom,
+ LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id,
+ &state);
+
+ while (state.left > 0) {
+ struct sk_buff *skb2;
+
+ skb2 = ip6_frag_next(skb, &state);
+ if (IS_ERR(skb2)) {
+ err = PTR_ERR(skb2);
+ goto blackhole;
+ }
+
+ err = output(net, sk, data, skb2);
+ if (err)
+ goto blackhole;
+ }
+ consume_skb(skb);
+ return err;
+
+blackhole:
+ kfree_skb(skb);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(br_ip6_fragment);
+
static const struct nf_ipv6_ops ipv6ops = {
#if IS_MODULE(CONFIG_IPV6)
.chk_addr = ipv6_chk_addr,
@@ -119,6 +238,10 @@ static const struct nf_ipv6_ops ipv6ops = {
.route_input = ip6_route_input,
.fragment = ip6_fragment,
.reroute = nf_ip6_reroute,
+#if IS_MODULE(CONFIG_NF_CONNTRACK_BRIDGE)
+ .br_defrag = nf_ct_frag6_gather,
+ .br_fragment = br_ip6_fragment,
+#endif
};
int __init ipv6_netfilter_init(void)
--
2.11.0
